1
|
Berndsen ZT, Akhtar M, Thapa M, Vickers T, Schmitz A, Torres JL, Baboo S, Kumar P, Khatoom N, Sheikh A, Hamrick M, Diedrich JK, Martinez-Bartolome S, Garrett PT, Yates JR, Turner JS, Laird RM, Poly F, Porter CK, Copps J, Ellebedy AH, Ward AB, Fleckenstein JM. Repeat modules and N-linked glycans define structure and antigenicity of a critical enterotoxigenic E. coli adhesin. bioRxiv 2024:2024.05.08.593125. [PMID: 38766097 PMCID: PMC11100705 DOI: 10.1101/2024.05.08.593125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of cases of infectious diarrhea annually, predominantly in children from low-middle income regions. Notably, in children, as well as human volunteers challenged with ETEC, diarrheal severity is significantly increased severity in blood group A (bgA) individuals. EtpA, is a secreted glycoprotein adhesin that functions as a blood group A lectin to promote critical interactions between ETEC and blood group A glycans on intestinal epithelia for effective bacterial adhesion and toxin delivery. EtpA is highly immunogenic resulting in robust antibody responses following natural infection and experimental challenge of human volunteers with ETEC. To understand how EtpA directs ETEC-blood group A interactions and stimulates adaptive immunity, we mutated EtpA, mapped its glycosylation by mass-spectrometry (MS), isolated polyclonal (pAbs) and monoclonal antibodies (mAbs) from vaccinated mice and ETEC-infected human volunteers, and determined structures of antibody-EtpA complexes by cryo-electron microscopy. Both bgA and mAbs that inhibited EtpA-bgA interactions and ETEC adhesion, bound to the C-terminal repeat domain highlighting this region as crucial for ETEC pathogen-host interaction. MS analysis uncovered extensive and heterogeneous N-linked glycosylation of EtpA and cryo-EM structures revealed that mAbs directly engage these unique glycan containing epitopes. Finally, electron microscopy-based polyclonal epitope mapping revealed antibodies targeting numerous distinct epitopes on N and C-terminal domains, suggesting that EtpA vaccination generates responses against neutralizing and decoy regions of the molecule. Collectively, we anticipate that these data will inform our general understanding of pathogen-host glycan interactions and adaptive immunity relevant to rational vaccine subunit design. Author summary Enterotoxigenic E. coli (ETEC), a leading cause of diarrhea disproportionately affecting young children in low-income regions, are a priority for vaccine development. Individuals possessing A blood-type are more susceptible to severe cholera-like disease. EtpA, a secreted, immunogenic, blood group A binding protein, is a current vaccine target antigen. Here, we determined the atomic structure of EtpA in complex with protective as well as non-protective monoclonal antibodies targeting two different domains of the protein, allowing us to pinpoint key regions involved in blood-group A antigen recognition and uncover the mechanism of antibody-based protection. In addition, we show through mass-spectrometry that EtpA is extensively and heterogeneously glycosylated at surface-exposed asparagine residues by a promiscuous and low-fidelity glycosyltransferase, EtpC, and that this unique form of bacterial glycosylation is critical for to development of protective immune responses. Lastly, polyclonal antibodies from vaccinated mice as well as monoclonal antibodies obtained from ETEC-infected human volunteers revealed that the highly antigenic surface of EtpA exhibits both protective and non-protective epitopes. These results greatly expand our understanding of ETEC pathogenesis, and the immune responses elicited by these common infections, providing valuable information to aid in the rational design and testing of subunit vaccines.
Collapse
|
2
|
Sabui S, Anthonymuthu S, Ramamoorthy K, Skupsky J, Jennings TSK, Rahmatpanah F, Fleckenstein JM, Said HM. Effect of knocking out mouse Slc44a4 on colonic uptake of the microbiota-generated thiamine pyrophosphate and on colon physiology. Am J Physiol Gastrointest Liver Physiol 2024. [PMID: 38713615 DOI: 10.1152/ajpgi.00065.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/30/2024] [Indexed: 05/09/2024]
Abstract
Humans/mammals obtain vitamin B1 from dietary and gut microbiota sources. Considerable amount of the microbiota generated vitamin exists in the form of thiamine pyrophosphate (TPP), and colonocytes are capable of absorbing TPP via a specific carrier-mediated process that involves the colonic TPP transporter (cTPPT; encoded by SLC44A4). Little is known about the relative contribution of SLC44A4 toward total colonic carrier-mediated TPP uptake, and its role in colon physiology. To address these issues, we generated an Slc44a4 knockout (KO) mouse model (by Cre-Lox recombination) and found a near complete inhibition in colonic carrier-mediated 3H-TPP uptake in the Slc44a4 KO compared to Wild-type-littermates (WT). We also observed a significant reduction in KO mice body weight and a shortening of their colon compared to WT. Using RNAseq and Ingenuity Pathway Analysis (IPA) approaches, we found that knocking out the colonic Slc44a4 to lead to changes in level of expression of many genes, including up-regulation in those associated with intestinal inflammation/colitis. Finally, we found that the Slc44a4 KO mice to be more susceptible to the effect of the colitogenic dextran sodium sulfate (DSS) compared to WT animals, a finding that lends support to the recent prediction by multiple genome-wide association studies (GWAS) that the SLC44A4 is a possible colitis susceptibility gene. In summary, results of these investigations show that the Slc44a4 is the predominant/only transporter involved in colonic uptake of TPP, that the transporter is important for colon physiology, and that its deletion increases susceptibility to inflammation.
Collapse
Affiliation(s)
- Subrata Sabui
- Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Selvaraj Anthonymuthu
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Kalidas Ramamoorthy
- Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| | - Jonathan Skupsky
- Medicine, University of California, Irvine, Irvine, CA, United States
| | | | - Farah Rahmatpanah
- Pathology and Laboratory Medicine, University of California, Irvine, Irvine, CA, United States
| | - James M Fleckenstein
- Department of Medicine, Washington University in St. Louis, St. Louis, MO, United States
| | - Hamid M Said
- Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States
| |
Collapse
|
3
|
Anthonymuthu S, Sabui S, Lee K, Sheikh A, Fleckenstein JM, Said HM. Bacterial lipopolysaccharide inhibits colonic carrier-mediated uptake of thiamin pyrophosphate: roles for TLR4 receptor and NF-κB/P38/JNK signaling pathway. Am J Physiol Cell Physiol 2023; 325:C758-C769. [PMID: 37519229 PMCID: PMC10635650 DOI: 10.1152/ajpcell.00272.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/20/2023] [Accepted: 07/20/2023] [Indexed: 08/01/2023]
Abstract
This study investigated the effect of the bacterial endotoxin lipopolysaccharide (LPS) on colonic uptake of thiamin pyrophosphate (TPP), the biologically active form of vitamin B1 that is generated by gut microbiota. We used three complementary models in our study: in vitro (human-derived colonic epithelial NCM460), ex vivo (human differentiated colonoid monolayers), and in vivo (mouse colonic tissue). The results showed that exposure of NCM460 cells to LPS leads to a significant inhibition of carrier-mediated TPP uptake as well as in decreased expression of the colonic TPP transporter (cTPPT) protein, mRNA, and heterologous nuclear RNA (hnRNA) compared with untreated controls. Similarly, exposure of human differentiated colonoid monolayers and mice to LPS caused significant inhibition in colonic carrier-mediated TPP uptake and in cTPPT protein, mRNA, and hnRNA expression. The effect of LPS on colonic TPP uptake and cTTPT expression was also found to be associated with a significant reduction in activity of the SLC44A4 promoter as well as in decreased expression of the nuclear factor Elf-3 (E74-like ETS transcription factor 3), which is needed for promoter activity. Finally, we found that knocking down the Toll-like receptor 4 (TLR4) and blocking the nuclear factor kappa B (NF-κB), JNK, and p38 signaling pathways with the use of pharmacological inhibitors lead to significant abrogation in the degree of LPS-mediated inhibition in TPP uptake and cTPPT expression. These results demonstrated that exposure of colonic epithelia to LPS inhibits colonic TPP uptake via transcriptional mechanism(s) and that the effect is mediated via TLR4 receptor and NF-κB/p38/JNK signaling pathways.NEW & NOTEWORTHY This study examined the effect of the bacterial lipopolysaccharide (LPS) on the colonic uptake of thiamin pyrophosphate (TPP), the biologically active form of vitamin B1. Three complementary models were used: in vitro (human NCM460 cells), ex vivo (human colonoids), and in vivo (mice). The results showed LPS to significantly suppress TPP uptake and the expression of its transporter, and that these effects are mediated via the membrane TLR4 receptor, and involve the NF-κB/p38/JNK signaling pathways.
Collapse
Affiliation(s)
- Selvaraj Anthonymuthu
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, California, United States
| | - Subrata Sabui
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, California, United States
- Department of Medical Research, Tibor Rubin VA Medical Center, Long Beach, California, United States
| | - Katherine Lee
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, California, United States
| | - Alaullah Sheikh
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States
- Veterans Affairs Medical Center, St. Louis, Missouri, United States
| | - Hamid M Said
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, California, United States
- Department of Medicine, School of Medicine, University of California, Irvine, California, United States
- Department of Medical Research, Tibor Rubin VA Medical Center, Long Beach, California, United States
| |
Collapse
|
4
|
Kuhlmann FM, Grigura V, Vickers TJ, Prouty MG, Iannotti LL, Dulience SJL, Fleckenstein JM. Seroprevalence Study of Conserved Enterotoxigenic Escherichia coli Antigens in Globally Diverse Populations. Microorganisms 2023; 11:2221. [PMID: 37764065 PMCID: PMC10536235 DOI: 10.3390/microorganisms11092221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/28/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) are common causes of infectious diarrhea among young children of low-and middle-income countries (LMICs) and travelers to these regions. Despite their significant contributions to the morbidity and mortality associated with childhood and traveler's diarrhea, no licensed vaccines are available. Current vaccine strategies may benefit from the inclusion of additional conserved antigens, which may contribute to broader coverage and enhanced efficacy, given their key roles in facilitating intestinal colonization and effective enterotoxin delivery. EatA and EtpA are widely conserved in diverse populations of ETEC, but their immunogenicity has only been studied in controlled human infection models and a population of children in Bangladesh. Here, we compared serologic responses to EatA, EtpA and heat-labile toxin in populations from endemic regions including Haitian children and subjects residing in Egypt, Cameroon, and Peru to US children and adults where ETEC infections are sporadic. We observed elevated IgG and IgA responses in individuals from endemic regions to each of the antigens studied. In a cohort of Haitian children, we observed increased immune responses following exposure to each of the profiled antigens. These findings reflect the wide distribution of ETEC infections across multiple endemic regions and support further evaluation of EatA and EtpA as candidate ETEC vaccine antigens.
Collapse
Affiliation(s)
- Frederick Matthew Kuhlmann
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
| | - Vadim Grigura
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
| | - Timothy J. Vickers
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
| | | | - Lora L. Iannotti
- Institute for Public Health, Brown School, Washington University in Saint Louis, Saint Louis, MO 63110, USA; (L.L.I.); (S.J.L.D.)
| | - Sherlie Jean Louis Dulience
- Institute for Public Health, Brown School, Washington University in Saint Louis, Saint Louis, MO 63110, USA; (L.L.I.); (S.J.L.D.)
| | - James M. Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
- Medicine Service, Infectious Diseases, Saint Louis VA Health Care System, St. Louis, MO 63110, USA
| |
Collapse
|
5
|
Ntui CM, Fleckenstein JM, Schubert WD. Structural and biophysical characterization of the secreted, β-helical adhesin EtpA of Enterotoxigenic Escherichia coli. PLoS One 2023; 18:e0287100. [PMID: 37343026 PMCID: PMC10284417 DOI: 10.1371/journal.pone.0287100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a diarrhoeal pathogen associated with high morbidity and mortality especially among young children in developing countries. At present, there is no vaccine for ETEC. One candidate vaccine antigen, EtpA, is a conserved secreted adhesin that binds to the tips of flagellae to bridge ETEC to host intestinal glycans. EtpA is exported through a Gram-negative, two-partner secretion system (TPSS, type Vb) comprised of the secreted EtpA passenger (TpsA) protein and EtpB (TpsB) transporter that is integrated into the outer bacterial membrane. TpsA proteins share a conserved, N-terminal TPS domain followed by an extensive C-terminal domain with divergent sequence repeats. Two soluble, N-terminal constructs of EtpA were prepared and analysed respectively including residues 67 to 447 (EtpA67-447) and 1 to 606 (EtpA1-606). The crystal structure of EtpA67-447 solved at 1.76 Å resolution revealed a right-handed parallel β-helix with two extra-helical hairpins and an N-terminal β-strand cap. Analyses by circular dichroism spectroscopy confirmed the β-helical fold and indicated high resistance to chemical and thermal denaturation as well as rapid refolding. A theoretical AlphaFold model of full-length EtpA largely concurs with the crystal structure adding an extended β-helical C-terminal domain after an interdomain kink. We propose that robust folding of the TPS domain upon secretion provides a template to extend the N-terminal β-helix into the C-terminal domains of TpsA proteins.
Collapse
Affiliation(s)
- Clifford Manyo Ntui
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri, United States of Ameirca
- Infectious Disease Service Saint Louis VA Health Care System, Saint Louis, Missouri, United States of Ameirca
| | - Wolf-Dieter Schubert
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| |
Collapse
|
6
|
Abstract
The pathogenic Escherichia coli can be parsed into specific variants (pathovars) depending on their phenotypic behavior and/or expression of specific virulence factors. These pathogens are built around chromosomally-encoded core attributes and through acquisition of specific virulence genes that direct their interaction with the host. Engagement of E. coli pathovars with CEACAMs is determined both by core elements common to all E. coli as well as extrachromosomally-encoded pathovar-specific virulence traits, which target amino terminal immunoglobulin variable-like (IgV) regions of CEACAMs. Emerging data suggests that engagement of CEACAMs does not unilaterally benefit the pathogen and that these interactions may also provide an avenue for pathogen elimination.
Collapse
Affiliation(s)
- Alaullah Sheikh
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - James M. Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, United States
- Infectious Diseases, Medicine Service, Veterans Affairs Saint Louis Health Care System, Saint Louis, MO, United States
| |
Collapse
|
7
|
Anthonymuthu S, Sabui S, Sheikh A, Fleckenstein JM, Said HM. Tumor necrosis factor α impedes colonic thiamin pyrophosphate and free thiamin uptake: involvement of JNK/ERK 1/2-mediated pathways. Am J Physiol Cell Physiol 2022; 323:C1664-C1680. [PMID: 36342158 PMCID: PMC9744649 DOI: 10.1152/ajpcell.00458.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 10/31/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Abstract
The aim of this study was to examine the effect of TNFα (i.e., a predominant proinflammatory cytokine produced during chronic gut inflammation) on colonic uptake of thiamin pyrophosphate (TPP) and free thiamin, forms of vitamin B1 that are produced by the gut microbiota and are absorbed via distinct carrier-mediated systems. We utilized human-derived colonic epithelial CCD841 and NCM460 cells, human differentiated colonoid monolayers, and mouse intact colonic tissue preparations together with an array of cellular/molecular approaches in our investigation. The results showed that exposure of colonic epithelial cells to TNFα leads to a significant inhibition in TPP and free thiamin uptake. This inhibition was associated with: 1) a significant suppression in the level of expression of the colonic TPP transporter (cTPPT; encoded by SLC44A4), as well as thiamin transporters-1 & 2 (THTR-1 & -2; encoded by SLC19A2 & SLC19A3, respectively); 2) marked inhibition in activity of the SLC44A4, SLC19A2, and SLC19A3 promoters; and 3) significant suppression in level of expression of nuclear factors that are needed for activity of these promoters (i.e., CREB-1, Elf-3, NF-1A, SP-1). Furthermore, the inhibitory effects were found to be mediated via JNK and ERK1/2 signaling pathways. We also examined the level of expression of cTPPT and THTR-1 & -2 in colonic tissues of patients with active ulcerative colitis and found the levels to be significantly lower than in healthy controls. These findings demonstrate that exposure of colonocytes to TNFα suppresses TPP and free thiamin uptake at the transcriptional level via JNK- and Erk1/2-mediated pathways.
Collapse
Affiliation(s)
- Selvaraj Anthonymuthu
- Department of Physiology and Biophysics, University of California, Irvine, California
| | - Subrata Sabui
- Department of Physiology and Biophysics, University of California, Irvine, California
- Department of Medicine, University of California, Irvine, California
- Department of Medical Research, VA Medical Center, Long Beach, California
| | - Alaullah Sheikh
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
- Veterans Affairs Medical Center, St. Louis, Missouri
| | - Hamid M Said
- Department of Physiology and Biophysics, University of California, Irvine, California
- Department of Medicine, University of California, Irvine, California
- Department of Medical Research, VA Medical Center, Long Beach, California
| |
Collapse
|
8
|
Sheikh A, Tumala B, Vickers TJ, Martin JC, Rosa BA, Sabui S, Basu S, Simoes RD, Mitreva M, Storer C, Tyksen E, Head RD, Beatty W, Said HM, Fleckenstein JM. Enterotoxigenic Escherichia coli heat-labile toxin drives enteropathic changes in small intestinal epithelia. Nat Commun 2022; 13:6886. [PMID: 36371425 PMCID: PMC9653437 DOI: 10.1038/s41467-022-34687-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 11/01/2022] [Indexed: 11/14/2022] Open
Abstract
Enterotoxigenic E. coli (ETEC) produce heat-labile (LT) and/or heat-stable (ST) enterotoxins, and commonly cause diarrhea in resource-poor regions. ETEC have been linked repeatedly to sequelae in children including enteropathy, malnutrition, and growth impairment. Although cellular actions of ETEC enterotoxins leading to diarrhea are well-established, their contributions to sequelae remain unclear. LT increases cellular cAMP to activate protein kinase A (PKA) that phosphorylates ion channels driving intestinal export of salt and water resulting in diarrhea. As PKA also modulates transcription of many genes, we interrogated transcriptional profiles of LT-treated intestinal epithelia. Here we show that LT significantly alters intestinal epithelial gene expression directing biogenesis of the brush border, the major site for nutrient absorption, suppresses transcription factors HNF4 and SMAD4 critical to enterocyte differentiation, and profoundly disrupts microvillus architecture and essential nutrient transport. In addition, ETEC-challenged neonatal mice exhibit substantial brush border derangement that is prevented by maternal vaccination with LT. Finally, mice repeatedly challenged with toxigenic ETEC exhibit impaired growth recapitulating the multiplicative impact of recurring ETEC infections in children. These findings highlight impacts of ETEC enterotoxins beyond acute diarrheal illness and may inform approaches to prevent major sequelae of these common infections including malnutrition that impact millions of children.
Collapse
Affiliation(s)
- Alaullah Sheikh
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Brunda Tumala
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Tim J Vickers
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - John C Martin
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Bruce A Rosa
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Subrata Sabui
- Departments of Medicine and Physiology/Biophysics, School of Medicine, University of California-Irvine, Irvine, CA, 92697, USA
- Department of Research, VA Medical Center, Long Beach, CA, 90822, USA
| | - Supratim Basu
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Rita D Simoes
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Makedonka Mitreva
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Chad Storer
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Erik Tyksen
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Richard D Head
- The McDonnell Genome Institute, Washington University School of Medicine, St. Louis, MO, 63110, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Wandy Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO, 63110, USA
| | - Hamid M Said
- Departments of Medicine and Physiology/Biophysics, School of Medicine, University of California-Irvine, Irvine, CA, 92697, USA
- Department of Research, VA Medical Center, Long Beach, CA, 90822, USA
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
- Infectious Diseases, Medicine Service, Veterans Affairs Saint Louis Health Care System, Saint Louis, MO, 63106, USA.
| |
Collapse
|
9
|
Sheikh A, Wangdi T, Vickers TJ, Aaron B, Palmer M, Miller MJ, Kim S, Herring C, Simoes R, Crainic JA, Gildersleeve JC, van der Post S, Hansson GC, Fleckenstein JM. Enterotoxigenic Escherichia coli Degrades the Host MUC2 Mucin Barrier To Facilitate Critical Pathogen-Enterocyte Interactions in Human Small Intestine. Infect Immun 2022; 90:e0057221. [PMID: 34807735 PMCID: PMC8853678 DOI: 10.1128/iai.00572-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 11/12/2021] [Indexed: 02/08/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) isolates are genetically diverse pathological variants of E. coli defined by the production of heat-labile (LT) and/or heat-stable (ST) toxins. ETEC strains are estimated to cause hundreds of millions of cases of diarrheal illness annually. However, it is not clear that all strains are equally equipped to cause disease, and asymptomatic colonization with ETEC is common in low- to middle-income regions lacking basic sanitation and clean water where ETEC are ubiquitous. Recent molecular epidemiology studies have revealed a significant association between strains that produce EatA, a secreted autotransporter protein, and the development of symptomatic infection. Here, we demonstrate that LT stimulates production of MUC2 mucin by goblet cells in human small intestine, enhancing the protective barrier between pathogens and enterocytes. In contrast, using explants of human small intestine as well as small intestinal enteroids, we show that EatA counters this host defense by engaging and degrading the MUC2 mucin barrier to promote bacterial access to target enterocytes and ultimately toxin delivery, suggesting that EatA plays a crucial role in the molecular pathogenesis of ETEC. These findings may inform novel approaches to prevention of acute diarrheal illness as well as the sequelae associated with ETEC and other pathogens that rely on EatA and similar proteases for efficient interaction with their human hosts.
Collapse
Affiliation(s)
- Alaullah Sheikh
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Tamding Wangdi
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Tim J. Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Bailey Aaron
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Margot Palmer
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Mark J. Miller
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Seonyoung Kim
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Cassandra Herring
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Rita Simoes
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Jennifer A. Crainic
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Jeffrey C. Gildersleeve
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Sjoerd van der Post
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Gunnar C. Hansson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
- Medicine Service, Veterans Affairs Medical Center, Saint Louis, Missouri, USA
| |
Collapse
|
10
|
Sabui S, Ramamoorthy K, Romero JM, Simoes RD, Fleckenstein JM, Said HM. Hypoxia inhibits colonic uptake of the microbiota-generated forms of vitamin B1 via HIF-1α-mediated transcriptional regulation of their transporters. J Biol Chem 2022; 298:101562. [PMID: 34998824 PMCID: PMC8800108 DOI: 10.1016/j.jbc.2022.101562] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/29/2021] [Accepted: 01/02/2022] [Indexed: 01/19/2023] Open
Abstract
Hypoxia exerts profound effects on cell physiology, but its effect on colonic uptake of the microbiota-generated forms of vitamin B1 (i.e., thiamin pyrophosphate [TPP] and free thiamine) has not been described. Here, we used human colonic epithelial NCM460 cells and human differentiated colonoid monolayers as in vitro and ex vivo models, respectively, and were subjected to either chamber (1% O2, 5% CO2, and 94% N2) or chemically (desferrioxamine; 250 μM)-induced hypoxia followed by determination of different physiological-molecular parameters. We showed that hypoxia causes significant inhibition in TPP and free thiamin uptake by colonic NCM460 cells and colonoid monolayers; it also caused a significant reduction in the expression of TPP (SLC44A4) and free thiamin (SLC19A2 and SLC19A3) transporters and in activity of their gene promoters. Furthermore, hypoxia caused a significant induction in levels of hypoxia-inducible transcription factor (HIF)-1α but not HIF-2α. Knocking down HIF-1α using gene-specific siRNAs in NCM460 cells maintained under hypoxic conditions, on the other hand, led to a significant reversal in the inhibitory effect of hypoxia on TPP and free thiamin uptake as well as on the expression of their transporters. Finally, a marked reduction in level of expression of the nuclear factors cAMP responsive element-binding protein 1 and gut-enriched Krüppel-like factor 4 (required for activity of SLC44A4 and SLC19A2 promoters, respectively) was observed under hypoxic conditions. In summary, hypoxia causes severe inhibition in colonic TPP and free thiamin uptake that is mediated at least in part via HIF-1α-mediated transcriptional mechanisms affecting their respective transporters.
Collapse
Affiliation(s)
- Subrata Sabui
- Department of Physiology and Biophysics, UCI, Irvine, California, USA; Department of Research, VA Medical Center, Long Beach, California, USA
| | | | - Jose M Romero
- Department of Research, VA Medical Center, Long Beach, California, USA; Department of Medicine, UCI, Irvine, California, USA
| | - Rita D Simoes
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St Louis, Missouri, USA
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St Louis, Missouri, USA; Department Medicine Service, Veterans Affairs Medical Center, St Louis, Missouri, USA
| | - Hamid M Said
- Department of Physiology and Biophysics, UCI, Irvine, California, USA; Department of Research, VA Medical Center, Long Beach, California, USA; Department of Medicine, UCI, Irvine, California, USA.
| |
Collapse
|
11
|
Abstract
Enterotoxigenic Escherichia coli (ETEC) are ubiquitous diarrheal pathogens that thrive in areas lacking basic human needs of clean water and sanitation. These genetically plastic organisms cause tremendous morbidity among disadvantaged young children, in the form of both acute diarrheal illness and sequelae of malnutrition and growth impairment. The recent discovery of additional plasmid-encoded virulence factors and elucidation of their critical role in the molecular pathogenesis of ETEC may inform new approaches to the development of broadly protective vaccines. Although the pathogens have been closely linked epidemiologically with nondiarrheal sequelae, these conditions remain very poorly understood. Similarly, while canonical effects of ETEC toxins on cellular signaling promoting diarrhea are clear, emerging data suggest that these toxins may also drive changes in intestinal architecture and associated sequelae. Elucidation of molecular events underlying these changes could inform optimal approaches to vaccines that prevent acute diarrhea and ETEC-associated sequelae.
Collapse
Affiliation(s)
- James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University in St Louis, School of Medicine, St Louis, Missouri, USA
- Infectious Disease Section, Medicine Service, St Louis Veterans Affairs Health Care System, St Louis, Missouri, USA
| | - Alaullah Sheikh
- Department of Medicine, Division of Infectious Diseases, Washington University in St Louis, School of Medicine, St Louis, Missouri, USA
| |
Collapse
|
12
|
Abstract
The enterotoxigenic Escherichia coli (ETEC) are a diverse and genetically plastic pathologic variant (pathovar) of E. coli defined by their production of heat-labile (LT) and heat-stable (ST) enterotoxins. These pathogens, which came to recognition more than four decades ago in patients presenting with severe cholera-like diarrhea, are now known to cause hundreds of millions of cases of symptomatic infection annually. Children in low-middle income regions of the world lacking access to clean water and basic sanitation are disproportionately affected by ETEC. In addition to acute diarrheal morbidity, these pathogens remain a significant cause of mortality in children under the age of five years and have also been linked repeatedly to sequelae of childhood malnutrition and growth stunting. Vaccines that could prevent ETEC infections therefore remain a high priority. Despite several decades of effort, a licensed vaccine that protects against the breadth of these pathogens remains an aspirational goal, and the underlying genetic plasticity of E. coli has posed a fundamental challenge to development of a vaccine that can encompass the complete antigenic spectrum of ETEC. Nevertheless, novel strategies that include toxoids, a more complete understanding of ETEC molecular pathogenesis, structural details of target immunogens, and the discovery of more highly conserved antigens essential for virulence should accelerate progress and make a broadly protective vaccine feasible.
Collapse
Affiliation(s)
- James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri, USA
- Medicine Service, Infectious Diseases, John Cochran Saint Louis Veterans Affairs Health Care System, Saint Louis, Missouri, USA
| |
Collapse
|
13
|
Fleckenstein JM, Bitoun JP. Changing the locks on intestinal signaling. Cell Host Microbe 2021; 29:1335-1337. [PMID: 34499858 DOI: 10.1016/j.chom.2021.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Endogenous peptides and structurally similar bacterial heat-stable enterotoxins (ST) bind guanylate cyclase-C (GC-C), resulting in fluid homeostasis or diarrhea, respectively. In this issue of Cell Host & Microbe, Carey et al., show how bats have evolutionarily maintained homeostatic signaling while avoiding pathogenic effects of ST.
Collapse
Affiliation(s)
- James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine, 660 South Euclid Avenue, Saint Louis, MO 63110, USA; Medicine Service, Infectious Diseases, Veterans Affairs Health Care System, Saint Louis, MO 63106, USA.
| | - Jacob P Bitoun
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, USA
| |
Collapse
|
14
|
Wang GC, Wallace MJ, Krishnan G, Olson PD, Carlson AL, Dantas G, Fleckenstein JM. Spontaneous Bacterial Peritonitis Caused by Bordetella hinzii. Emerg Infect Dis 2021; 27:2966-2968. [PMID: 34463239 PMCID: PMC8545000 DOI: 10.3201/eid2711.211428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Although Bordetella hinzii coccobacilli is most commonly identified in respiratory tracts of birds and rodents, this organism has occasionally been isolated in human infections. We describe a case of B. hinzii spontaneous bacterial peritonitis in Missouri, USA. Whole-genome sequencing of blood and peritoneal fluid isolates confirmed B. hinzii infection.
Collapse
|
15
|
Ramamoorthy K, Sabui S, Srinivasan P, Al-Juburi S, Pham Q, Chu BD, Simoes RD, Fleckenstein JM, Said HM. Effect of chronic alcohol exposure on gut vitamin B7 uptake: involvement of epigenetic mechanisms and effect of alcohol metabolites. Am J Physiol Gastrointest Liver Physiol 2021; 321:G123-G133. [PMID: 34077272 PMCID: PMC8410103 DOI: 10.1152/ajpgi.00144.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vitamin B7 (biotin) is essential for normal health and its deficiency/suboptimal levels occur in a variety of conditions including chronic alcoholism. Mammals, including humans, obtain biotin from diet and gut-microbiota via absorption along the intestinal tract. The absorption process is carrier mediated and involves the sodium-dependent multivitamin transporter (SMVT; SLC5A6). We have previously shown that chronic alcohol exposure significantly inhibits intestinal/colonic biotin uptake via suppression of Slc5a6 transcription in animal and cell line models. However, little is known about the transcriptional/epigenetic factors that mediate this suppression. In addition, the effect of alcohol metabolites (generated via alcohol metabolism by gut microbiota and host tissues) on biotin uptake is still unknown. To address these questions, we first demonstrated that chronic alcohol exposure inhibits small intestinal and colonic biotin uptake and SMVT expression in human differentiated enteroid and colonoid monolayers. We then showed that chronic alcohol exposures of both, Caco-2 cells and mice, are associated with a significant suppression in expression of the nuclear factor KLF-4 (needed for Slc5a6 promoter activity), as well as with epigenetic alterations (histone modifications). We also found that chronic exposure of NCM460 human colonic epithelial cells as well as human differentiated colonoid monolayers, to alcohol metabolites (acetaldehyde, ethyl palmitate, ethyl oleate) significantly inhibited biotin uptake and SMVT expression. These findings shed light onto the molecular/epigenetic mechanisms that mediate the inhibitory effect of chronic alcohol exposure on intestinal biotin uptake. They further show that alcohol metabolites are also capable of inhibiting biotin uptake in the gut.NEW & NOTEWORTHY Using complementary models, including human differentiated enteroid and colonoid monolayers, this study shows the involvement of molecular and epigenetic mechanisms in mediating the inhibitory effect of chronic alcohol exposure on biotin uptake along the intestinal tract. The study also shows that alcohol metabolites (generated by gut microbiota and host tissues) cause inhibition in gut biotin uptake.
Collapse
Affiliation(s)
- Kalidas Ramamoorthy
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Subrata Sabui
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Padmanabhan Srinivasan
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Saleh Al-Juburi
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Quang Pham
- 1Department of Physiology/Biophysics, University of California, Irvine, California
| | - Brian D. Chu
- 1Department of Physiology/Biophysics, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| | - Rita D. Simoes
- 3Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri
| | - James M. Fleckenstein
- 3Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri,4Veterans Affairs Medical Center, St. Louis Missouri
| | - Hamid M. Said
- 1Department of Physiology/Biophysics, University of California, Irvine, California,2Department of Medicine, University of California, Irvine, California,5Veterans Affairs Medical Center, Long Beach, California
| |
Collapse
|
16
|
Walker R, Kaminski RW, Porter C, Choy RKM, White JA, Fleckenstein JM, Cassels F, Bourgeois L. Vaccines for Protecting Infants from Bacterial Causes of Diarrheal Disease. Microorganisms 2021; 9:1382. [PMID: 34202102 PMCID: PMC8303436 DOI: 10.3390/microorganisms9071382] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 12/22/2022] Open
Abstract
The global diarrheal disease burden for Shigella, enterotoxigenic Escherichia coli (ETEC), and Campylobacter is estimated to be 88M, 75M, and 75M cases annually, respectively. A vaccine against this target trio of enteric pathogens could address about one-third of diarrhea cases in children. All three of these pathogens contribute to growth stunting and have demonstrated increasing resistance to antimicrobial agents. Several combinations of antigens are now recognized that could be effective for inducing protective immunity against each of the three target pathogens in a single vaccine for oral administration or parenteral injection. The vaccine combinations proposed here would result in a final product consistent with the World Health Organization's (WHO) preferred product characteristics for ETEC and Shigella vaccines, and improve the vaccine prospects for support from Gavi, the Vaccine Alliance, and widespread uptake by low- and middle-income countries' (LMIC) public health stakeholders. Broadly protective antigens will enable multi-pathogen vaccines to be efficiently developed and cost-effective. This review describes how emerging discoveries for each pathogen component of the target trio could be used to make vaccines, which could help reduce a major cause of poor health, reduced cognitive development, lost economic productivity, and poverty in many parts of the world.
Collapse
Affiliation(s)
- Richard Walker
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA;
| | - Robert W. Kaminski
- Department of Diarrheal Disease Research, Walter Reed Institute of Research, Silver Spring, MD 20910, USA;
| | - Chad Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA;
| | - Robert K. M. Choy
- Center for Vaccine Innovation and Access, PATH, San Francisco, CA 94108, USA;
| | - Jessica A. White
- Center for Vaccine Innovation and Access, PATH, Seattle, WA 98121, USA; (J.A.W.); (F.C.)
| | - James M. Fleckenstein
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA;
- Medicine Service, Saint Louis VA Health Care System, St. Louis, MO 63106, USA
| | - Fred Cassels
- Center for Vaccine Innovation and Access, PATH, Seattle, WA 98121, USA; (J.A.W.); (F.C.)
| | - Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA;
| |
Collapse
|
17
|
Abstract
Acute bacterial gastroenteritis is among the most common infections worldwide, with millions of infections annually in the United States. Much of the illness is foodborne, occurring as both sporadic cases and large multistate outbreaks. Pathogen evolution through genetic exchange of virulence traits and antibiotic resistance determinants poses challenges for empiric therapy. Culture-independent diagnostic tests in clinical laboratories afford rapid diagnosis and expanded identification of pathogens. However, cultures remain important to generate sensitivity data and strain archiving for outbreak investigations. Most infections are self-limited, permitting judicious selection of antibiotic use in more severe forms of illness.
Collapse
Affiliation(s)
- James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine, Campus Box 8051, 660 South Euclid Avenue, Saint Louis, MO 63110, USA; Infectious Disease Section, Medicine Service, Veterans Affairs Saint Louis Health Care System, 915 North Grand Boulevard, Saint Louis, MO 63106, USA.
| | - F Matthew Kuhlmann
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine, Campus Box 8051, 660 South Euclid Avenue, Saint Louis, MO 63110, USA
| | - Alaullah Sheikh
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine, Campus Box 8051, 660 South Euclid Avenue, Saint Louis, MO 63110, USA
| |
Collapse
|
18
|
Foulke-Abel J, Yu H, Sunuwar L, Lin R, Fleckenstein JM, Kaper JB, Donowitz M. Phosphodiesterase 5 (PDE5) restricts intracellular cGMP accumulation during enterotoxigenic Escherichia coli infection. Gut Microbes 2020; 12:1752125. [PMID: 32378997 PMCID: PMC7524150 DOI: 10.1080/19490976.2020.1752125] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/09/2020] [Accepted: 03/27/2020] [Indexed: 02/06/2023] Open
Abstract
Diarrhea caused by enterotoxigenic Escherichia coli (ETEC) has a continuing impact on residents and travelers in underdeveloped countries. Both heat-labile (LT) and heat-stable (ST) enterotoxins contribute to pathophysiology via induction of cyclic nucleotide synthesis, and previous investigations focused on intracellular signal transduction rather than possible intercellular second messenger signaling. We modeled ETEC infection in human jejunal enteroid/organoid monolayers (HEM) and evaluated cyclic nucleotide pools, finding that intracellular cAMP was significantly increased but also underwent apical export, whereas cGMP was minimally retained intracellularly and predominantly effluxed into the basolateral space. LT and virulence factors including EatA, EtpA, and CfaE promoted ST release and enhanced ST-stimulated cGMP production. Intracellular cGMP was regulated by MK-571-sensitive export in addition to degradation by phosphodiesterase 5. HEMs had limited ST-induced intracellular cGMP accumulation compared to T84 or Caco-2 models. Cyclic nucleotide export/degradation demonstrates additional complexity in the mechanism of ETEC infection and may redirect understanding of diarrheal onset.
Collapse
Affiliation(s)
- Jennifer Foulke-Abel
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine , Baltimore, MD, USA
| | - Huimin Yu
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine , Baltimore, MD, USA
| | - Laxmi Sunuwar
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine , Baltimore, MD, USA
| | - Ruxian Lin
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine , Baltimore, MD, USA
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine , St. Louis, MO, USA
| | - James B Kaper
- Department of Microbiology & Immunology, University of Maryland School of Medicine , Baltimore, MD, USA
| | - Mark Donowitz
- Division of Gastroenterology & Hepatology, Department of Medicine, Johns Hopkins University School of Medicine , Baltimore, MD, USA
| |
Collapse
|
19
|
Kuhlmann FM, Martin J, Hazen TH, Vickers TJ, Pashos M, Okhuysen PC, Gómez-Duarte OG, Cebelinski E, Boxrud D, del Canto F, Vidal R, Qadri F, Mitreva M, Rasko DA, Fleckenstein JM. Conservation and global distribution of non-canonical antigens in Enterotoxigenic Escherichia coli. PLoS Negl Trop Dis 2019; 13:e0007825. [PMID: 31756188 PMCID: PMC6897418 DOI: 10.1371/journal.pntd.0007825] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/06/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Enterotoxigenic Escherichia coli (ETEC) cause significant diarrheal morbidity and mortality in children of resource-limited regions, warranting development of effective vaccine strategies. Genetic diversity of the ETEC pathovar has impeded development of broadly protective vaccines centered on the classical canonical antigens, the colonization factors and heat-labile toxin. Two non-canonical ETEC antigens, the EtpA adhesin, and the EatA mucinase are immunogenic in humans and protective in animal models. To foster rational vaccine design that complements existing strategies, we examined the distribution and molecular conservation of these antigens in a diverse population of ETEC isolates. METHODS Geographically diverse ETEC isolates (n = 1159) were interrogated by PCR, immunoblotting, and/or whole genome sequencing (n = 46) to examine antigen conservation. The most divergent proteins were purified and their core functions assessed in vitro. RESULTS EatA and EtpA or their coding sequences were present in 57.0% and 51.5% of the ETEC isolates overall, respectively; and were globally dispersed without significant regional differences in antigen distribution. These antigens also exhibited >93% amino acid sequence identity with even the most divergent proteins retaining the core adhesin and mucinase activity assigned to the prototype molecules. CONCLUSIONS EtpA and EatA are well-conserved molecules in the ETEC pathovar, suggesting that they serve important roles in virulence and that they could be exploited for rational vaccine design.
Collapse
Affiliation(s)
- F. Matthew Kuhlmann
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| | - John Martin
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Tracy H. Hazen
- Department of Microbiology and Immunology and Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Tim J. Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Madeline Pashos
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Pablo C. Okhuysen
- The Department of Infectious Diseases, Infection Control and Employee Health, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Oscar G. Gómez-Duarte
- Department of Pediatrics, Division of Infectious Diseases, University at Buffalo, The State University of New York, Buffalo, New York, United States of America
| | | | - Dave Boxrud
- Minnesota Department of Health, St. Paul, Minnesota, United States of America
| | - Felipe del Canto
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Roberto Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Instituto Milenio de Inmunonología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Makedonka Mitreva
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - David A. Rasko
- Department of Microbiology and Immunology and Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, United States of America
| |
Collapse
|
20
|
Rasko DA, Del Canto F, Luo Q, Fleckenstein JM, Vidal R, Hazen TH. Comparative genomic analysis and molecular examination of the diversity of enterotoxigenic Escherichia coli isolates from Chile. PLoS Negl Trop Dis 2019; 13:e0007828. [PMID: 31747410 PMCID: PMC6901236 DOI: 10.1371/journal.pntd.0007828] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 12/09/2019] [Accepted: 10/04/2019] [Indexed: 02/02/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is one of the most common diarrheal pathogens in the low- and middle-income regions of the world, however a systematic examination of the genomic content of isolates from Chile has not yet been undertaken. Whole genome sequencing and comparative analysis of a collection of 125 ETEC isolates from three geographic locations in Chile, allowed the interrogation of phylogenomic groups, sequence types and genes specific to isolates from the different geographic locations. A total of 80.8% (101/125) of the ETEC isolates were identified in E. coli phylogroup A, 15.2% (19/125) in phylogroup B, and 4.0% (5/125) in phylogroup E. The over-representation of genomes in phylogroup A was significantly different from other global ETEC genomic studies. The Chilean ETEC isolates could be further subdivided into sub-clades similar to previously defined global ETEC reference lineages that had conserved multi-locus sequence types and toxin profiles. Comparison of the gene content of the Chilean ETEC identified genes that were unique based on geographic location within Chile, phylogenomic classifications or sequence type. Completion of a limited number of genomes provided insight into the ETEC plasmid content, which is conserved in some phylogenomic groups and not conserved in others. These findings suggest that the Chilean ETEC isolates contain unique virulence factor combinations and genomic content compared to global reference ETEC isolates.
Collapse
Affiliation(s)
- David A. Rasko
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| | - Felipe Del Canto
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Qingwei Luo
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Veterans Affairs Medical Center, Saint Louis, Missouri, United States of America
| | - Roberto Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Instituto Milenio de Inmunología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Tracy H. Hazen
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| |
Collapse
|
21
|
Kumar P, Kuhlmann FM, Chakraborty S, Bourgeois AL, Foulke-Abel J, Tumala B, Vickers TJ, Sack DA, DeNearing B, Harro CD, Wright WS, Gildersleeve JC, Ciorba MA, Santhanam S, Porter CK, Gutierrez RL, Prouty MG, Riddle MS, Polino A, Sheikh A, Donowitz M, Fleckenstein JM. Enterotoxigenic Escherichia coli-blood group A interactions intensify diarrheal severity. J Clin Invest 2019; 129:2980. [PMID: 31259744 DOI: 10.1172/jci130874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
22
|
Brown JW, Badahdah A, Iticovici M, Vickers TJ, Alvarado DM, Helmerhorst EJ, Oppenheim FG, Mills JC, Ciorba MA, Fleckenstein JM, Bullitt E. A Role for Salivary Peptides in the Innate Defense Against Enterotoxigenic Escherichia coli. J Infect Dis 2019. [PMID: 29528423 DOI: 10.1093/infdis/jiy032] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Background Diarrheal disease from enterotoxigenic Escherichia coli (ETEC) causes significant worldwide morbidity and mortality in young children residing in endemic countries and is the leading cause of traveler's diarrhea. As ETEC enters the body through the oral cavity and cotransits the digestive tract with salivary components, we hypothesized that the antimicrobial activity of salivary proteins might extend beyond the oropharynx into the proximal digestive tract. Results Here, we show that the salivary peptide histatin-5 binds colonization factor antigen I pili, thereby blocking adhesion of ETEC to intestinal epithelial cells. Mechanistically, we demonstrate that histatin-5 stiffens the typically dynamic pili, abolishing their ability to function as spring-like shock absorbers, thereby inhibiting colonization within the turbulent vortices of chyme in the gastrointestinal tract. Conclusions Our data represent the first report of a salivary component exerting specific antimicrobial activity against an enteric pathogen and suggest that histatin-5 and related peptides might be exploited for prophylactic and/or therapeutic uses. Numerous viruses, bacteria, and fungi traverse the oropharynx to cause disease, so there is considerable opportunity for various salivary components to neutralize these pathogens prior to arrival at their target organ. Identification of additional salivary components with unexpectedly broad antimicrobial spectra should be a priority.
Collapse
Affiliation(s)
- Jeffrey W Brown
- Department of Physiology and Biophysics, Boston University School of Medicine, Massachusetts.,Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri
| | - Arwa Badahdah
- Department of Periodontology and Oral Biology, Boston University Goldman School of Dental Medicine, Massachusetts
| | - Micah Iticovici
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri
| | - Tim J Vickers
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St Louis, Missouri
| | - David M Alvarado
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri
| | - Eva J Helmerhorst
- Department of Molecular and Cell Biology, Boston University, Massachusetts
| | - Frank G Oppenheim
- Department of Molecular and Cell Biology, Boston University, Massachusetts.,Department of Biochemistry, Henry M. Goldman School of Dental Medicine, Boston University, Massachusetts
| | - Jason C Mills
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri.,Department of Developmental Biology, Washington University School of Medicine, St Louis, Missouri.,Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri
| | - Matthew A Ciorba
- Division of Gastroenterology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St Louis, Missouri.,Department of Molecular Microbiology and Microbial Pathogenesis Program, Washington University School of Medicine, St Louis, Missouri.,Department of USA Medicine Service, Veterans Affairs Medical Center, St Louis, Missouri
| | - Esther Bullitt
- Department of Physiology and Biophysics, Boston University School of Medicine, Massachusetts
| |
Collapse
|
23
|
Abstract
PURPOSE OF REVIEW Review recent developments pertaining to the epidemiology, molecular pathogenesis, and sequelae of enterotoxigenic Escherichia coli (ETEC) infections in addition to discussion of challenges for vaccinology. RECENT FINDINGS ETEC are a major cause of diarrheal illness in resource poor areas of the world where they contribute to unacceptable morbidity and continued mortality particularly among young children; yet, precise epidemiologic estimates of their contribution to death and chronic disease have been difficult to obtain. Although most pathogenesis studies, and consequently vaccine development have focused intensively on canonical antigens, more recently identified molecules unique to the ETEC pathovar may inform our understanding of ETEC virulence, and the approach to broadly protective vaccines. ETEC undeniably continue to have a substantial impact on global health; however, further studies are needed to clarify the true impact of these infections, particularly in regions where access to care may be limited. Likewise, our present understanding of the relationship of ETEC infection to non-diarrheal sequelae is presently limited, and additional effort will be required to achieve a mechanistic understanding of these diseases and to fulfill Koch's postulates on a molecular level. Precise elucidation of the role played by novel virulence factors, the global burden of acute illness, and the contribution of these pathogens and/or their toxins to non-diarrheal morbidity remain important imperatives.
Collapse
Affiliation(s)
- James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO, 63110, USA.
- Medicine Service, Veterans Affairs Medical Center, Saint Louis, MO, USA.
| | - F Matthew Kuhlmann
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, 660 South Euclid Avenue, Saint Louis, MO, 63110, USA
| |
Collapse
|
24
|
Zhu Y, Luo Q, Davis SM, Westra C, Vickers TJ, Fleckenstein JM. Molecular Determinants of Enterotoxigenic Escherichia coli Heat-Stable Toxin Secretion and Delivery. Infect Immun 2018; 86:e00526-18. [PMID: 30126899 PMCID: PMC6204697 DOI: 10.1128/iai.00526-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 08/15/2018] [Indexed: 01/19/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC), a heterogeneous diarrheal pathovar defined by production of heat-labile (LT) and/or heat-stable (ST) toxins, causes substantial morbidity among young children in the developing world. Studies demonstrating a major burden of ST-producing ETEC have focused interest on ST toxoids for ETEC vaccines. We examined fundamental aspects of ST biology using ETEC strain H10407, which carries estH and estP genes encoding STh and STp, respectively, in addition to eltAB genes responsible for LT. Here, we found that deletion of estH significantly diminished cyclic GMP (cGMP) activation in target epithelia, while deletion of estP had a surprisingly modest impact, and a dual estH estP mutant was not appreciably different from the estH mutant. However, we noted that either STh or STp recombinant peptides stimulated cGMP production and that the loss of estP was compensated by enhanced estH transcription. We also found that the TolC efflux protein was essential for toxin secretion and delivery, providing a potential avenue for efflux inhibitors in treatment of acute diarrheal illness. In addition, we demonstrated that the EtpA adhesin is required for optimal delivery of ST and that antibodies against either the adhesin or STh significantly impaired toxin delivery and cGMP activation in target T84 cells. Finally, we used FLAG epitope fusions to demonstrate that the STh propeptide sequence is secreted by ETEC, potentially providing additional epitopes for antibody neutralization. These studies collectively extend our understanding of ETEC pathogenesis and potentially inform additional avenues to mitigate disease by these common diarrheal pathogens.
Collapse
Affiliation(s)
- Yuehui Zhu
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Qingwei Luo
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sierra M Davis
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Chase Westra
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Tim J Vickers
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Medicine Service, Department of Veterans Affairs Medical Center, St. Louis, Missouri, USA
| |
Collapse
|
25
|
Fleckenstein JM. Providing Structure to Enterotoxigenic Escherichia coli Vaccine Development. J Infect Dis 2018; 216:1-3. [PMID: 28541516 DOI: 10.1093/infdis/jix146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 03/17/2017] [Indexed: 01/09/2023] Open
Affiliation(s)
- James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine.,Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri
| |
Collapse
|
26
|
Chakraborty S, Randall A, Vickers TJ, Molina D, Harro CD, DeNearing B, Brubaker J, Sack DA, Bourgeois AL, Felgner PL, Liang X, Mani S, Wenzel H, Townsend RR, Gilmore PE, Darsley MJ, Rasko DA, Fleckenstein JM. Human Experimental Challenge With Enterotoxigenic Escherichia coli Elicits Immune Responses to Canonical and Novel Antigens Relevant to Vaccine Development. J Infect Dis 2018; 218:1436-1446. [PMID: 29800314 PMCID: PMC6151082 DOI: 10.1093/infdis/jiy312] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 05/22/2018] [Indexed: 11/12/2022] Open
Abstract
Background Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal illness in the developing world. Enterotoxigenic E coli vaccinology has been challenged by genetic diversity and heterogeneity of canonical antigens. Examination of the antigenic breadth of immune responses associated with protective immunity could afford new avenues for vaccine development. Methods Antibody lymphocyte supernatants (ALS) and sera from 20 naive human volunteers challenged with ETEC strain H10407 and from 10 volunteers rechallenged 4-6 weeks later with the same strain (9 of whom were completely protected on rechallenge) were tested against ETEC proteome microarrays containing 957 antigens. Results Enterotoxigenic E coli challenge stimulated robust serum and mucosal (ALS) responses to canonical vaccine antigens (CFA/I, and the B subunit of LT) as well as a small number of antigens not presently targeted in ETEC vaccines. These included pathovar-specific secreted proteins (EtpA, EatA) as well as highly conserved E coli antigens including YghJ, flagellin, and pertactin-like autotransporter proteins, all of which have previously afforded protection against ETEC infection in preclinical studies. Conclusions Taken together, studies reported here suggest that immune responses after ETEC infection involve traditional vaccine targets as well as a select number of more recently identified protein antigens that could offer additional avenues for vaccine development for these pathogens.
Collapse
Affiliation(s)
| | - Arlo Randall
- Antigen Discovery, Inc. (ADI), Irvine, California
| | - Tim J Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri
| | - Doug Molina
- Antigen Discovery, Inc. (ADI), Irvine, California
| | - Clayton D Harro
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Barbara DeNearing
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Jessica Brubaker
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - David A Sack
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | | | - Xiaowu Liang
- Antigen Discovery, Inc. (ADI), Irvine, California
| | | | | | - R Reid Townsend
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine
| | - Petra E Gilmore
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine
| | | | - David A Rasko
- The Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland
| | - James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri
- Medicine Service, John Cochran VA Medical Center, St. Louis, Missouri
| |
Collapse
|
27
|
Kumar P, Kuhlmann FM, Chakraborty S, Bourgeois AL, Foulke-Abel J, Tumala B, Vickers TJ, Sack DA, DeNearing B, Harro CD, Wright WS, Gildersleeve JC, Ciorba MA, Santhanam S, Porter CK, Gutierrez RL, Prouty MG, Riddle MS, Polino A, Sheikh A, Donowitz M, Fleckenstein JM. Enterotoxigenic Escherichia coli-blood group A interactions intensify diarrheal severity. J Clin Invest 2018; 128:3298-3311. [PMID: 29771685 DOI: 10.1172/jci97659] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 05/03/2018] [Indexed: 12/27/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) infections are highly prevalent in developing countries, where clinical presentations range from asymptomatic colonization to severe cholera-like illness. The molecular basis for these varied presentations, which may involve strain-specific virulence features as well as host factors, has not been elucidated. We demonstrate that, when challenged with ETEC strain H10407, originally isolated from a case of cholera-like illness, blood group A human volunteers developed severe diarrhea more frequently than individuals from other blood groups. Interestingly, a diverse population of ETEC strains, including H10407, secrete the EtpA adhesin molecule. As many bacterial adhesins also agglutinate red blood cells, we combined the use of glycan arrays, biolayer inferometry, and noncanonical amino acid labeling with hemagglutination studies to demonstrate that EtpA is a dominant ETEC blood group A-specific lectin/hemagglutinin. Importantly, we have also shown that EtpA interacts specifically with glycans expressed on intestinal epithelial cells from blood group A individuals and that EtpA-mediated bacterial-host interactions accelerate bacterial adhesion and effective delivery of both the heat-labile and heat-stable toxins of ETEC. Collectively, these data provide additional insight into the complex molecular basis of severe ETEC diarrheal illness that may inform rational design of vaccines to protect those at highest risk.
Collapse
Affiliation(s)
- Pardeep Kumar
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - F Matthew Kuhlmann
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - A Louis Bourgeois
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jennifer Foulke-Abel
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brunda Tumala
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Tim J Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Barbara DeNearing
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Clayton D Harro
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - W Shea Wright
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Jeffrey C Gildersleeve
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Matthew A Ciorba
- Department of Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Srikanth Santhanam
- Department of Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Chad K Porter
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Ramiro L Gutierrez
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Michael G Prouty
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Mark S Riddle
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Alexander Polino
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alaullah Sheikh
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA.,Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.,Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, USA
| |
Collapse
|
28
|
Sahl JW, Sistrunk JR, Baby NI, Begum Y, Luo Q, Sheikh A, Qadri F, Fleckenstein JM, Rasko DA. Insights into enterotoxigenic Escherichia coli diversity in Bangladesh utilizing genomic epidemiology. Sci Rep 2017; 7:3402. [PMID: 28611468 PMCID: PMC5469772 DOI: 10.1038/s41598-017-03631-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/28/2017] [Indexed: 11/08/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) cause more than 500,000 deaths each year in the developing world and are characterized on a molecular level by the presence of genes that encode the heat-stable (ST) and/or heat-labile (LT) enterotoxins, as well as surface structures, known as colonization factors (CFs). Genome sequencing and comparative genomic analyses of 94 previously uncharacterized ETEC isolates demonstrated remarkable genomic diversity, with 28 distinct sequence types identified in three phylogenomic groups. Interestingly, there is a correlation between the genomic sequence type and virulence factor profiles based on prevalence of the isolate, suggesting that there is an optimal combination of genetic factors required for survival, virulence and transmission in the most successful clones. A large-scale BLAST score ratio (LS-BSR) analysis was further applied to identify ETEC-specific genomic regions when compared to non-ETEC genomes, as well as genes that are more associated with clinical presentations or other genotypic markers. Of the strains examined, 21 of 94 ETEC isolates lacked any previously identified CF. Homology searches with the structural subunits of known CFs identified 6 new putative CF variants. These studies provide a roadmap to exploit genomic analyses by directing investigations of pathogenesis, virulence regulation and vaccine development.
Collapse
Affiliation(s)
- Jason W Sahl
- Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore Street, Suite 600, Baltimore, MD, 21201, USA
- Translational Genomics Research Institute, Flagstaff, AZ, 86001, USA
| | - Jeticia R Sistrunk
- Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore Street, Suite 600, Baltimore, MD, 21201, USA
| | - Nabilah Ibnat Baby
- Centre for Vaccine Sciences, Immunology Laboratory, International Centre Center for Diarrhoeal Disease Research, Mohakhali, Dhaka, 1212, Bangladesh
| | - Yasmin Begum
- Centre for Vaccine Sciences, Immunology Laboratory, International Centre Center for Diarrhoeal Disease Research, Mohakhali, Dhaka, 1212, Bangladesh
| | - Qingwei Luo
- Department of Medicine, Division of Infectious Diseases, Washington, USA
| | - Alaullah Sheikh
- Centre for Vaccine Sciences, Immunology Laboratory, International Centre Center for Diarrhoeal Disease Research, Mohakhali, Dhaka, 1212, Bangladesh
- The Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University in St. Louis, Washington, USA
| | - Firdausi Qadri
- Centre for Vaccine Sciences, Immunology Laboratory, International Centre Center for Diarrhoeal Disease Research, Mohakhali, Dhaka, 1212, Bangladesh
| | - James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington, USA
- The Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University in St. Louis, Washington, USA
- Medicine Service, Veterans Affairs Medical Center, St. Louis, MO, USA
| | - David A Rasko
- Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore Street, Suite 600, Baltimore, MD, 21201, USA.
| |
Collapse
|
29
|
Sheikh A, Rashu R, Begum YA, Kuhlman FM, Ciorba MA, Hultgren SJ, Qadri F, Fleckenstein JM. Highly conserved type 1 pili promote enterotoxigenic E. coli pathogen-host interactions. PLoS Negl Trop Dis 2017; 11:e0005586. [PMID: 28531220 PMCID: PMC5456409 DOI: 10.1371/journal.pntd.0005586] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/02/2017] [Accepted: 04/21/2017] [Indexed: 12/22/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC), defined by their elaboration of heat-labile (LT) and/or heat-stable (ST) enterotoxins, are a common cause of diarrheal illness in developing countries. Efficient delivery of these toxins requires ETEC to engage target host enterocytes. This engagement is accomplished using a variety of pathovar-specific and conserved E. coli adhesin molecules as well as plasmid encoded colonization factors. Some of these adhesins undergo significant transcriptional modulation as ETEC encounter intestinal epithelia, perhaps suggesting that they cooperatively facilitate interaction with the host. Among genes significantly upregulated on cell contact are those encoding type 1 pili. We therefore investigated the role played by these pili in facilitating ETEC adhesion, and toxin delivery to model intestinal epithelia. We demonstrate that type 1 pili, encoded in the E. coli core genome, play an essential role in ETEC virulence, acting in concert with plasmid-encoded pathovar specific colonization factor (CF) fimbriae to promote optimal bacterial adhesion to cultured intestinal epithelium (CIE) and to epithelial monolayers differentiated from human small intestinal stem cells. Type 1 pili are tipped with the FimH adhesin which recognizes mannose with stereochemical specificity. Thus, enhanced production of highly mannosylated proteins on intestinal epithelia promoted FimH-mediated ETEC adhesion, while conversely, interruption of FimH lectin-epithelial interactions with soluble mannose, anti-FimH antibodies or mutagenesis of fimH effectively blocked ETEC adhesion. Moreover, fimH mutants were significantly impaired in delivery of both heat-stable and heat-labile toxins to the target epithelial cells in vitro, and these mutants were substantially less virulent in rabbit ileal loop assays, a classical model of ETEC pathogenesis. Collectively, our data suggest that these highly conserved pili play an essential role in virulence of these diverse pathogens.
Collapse
Affiliation(s)
- Alaullah Sheikh
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Rasheduzzaman Rashu
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddrb), Mohakhali, Dhaka, Bangladesh
| | - Yasmin Ara Begum
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddrb), Mohakhali, Dhaka, Bangladesh
| | - F. Matthew Kuhlman
- Division of Infectious Disease, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Matthew A. Ciorba
- Division of Gastroenterology, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Scott J. Hultgren
- Department of Molecular Microbiology, Washington University in Saint Louis, Saint Louis, Missouri, United States of America
- Center for Women’s Infectious Disease Research (CWIDR), Washington University in Saint Louis, Saint Louis, Missouri, United States of America
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddrb), Mohakhali, Dhaka, Bangladesh
| | - James M. Fleckenstein
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Division of Infectious Disease, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Medicine Service, Veterans Affairs Medical Center, Saint Louis, Missouri, United States of America
- * E-mail:
| |
Collapse
|
30
|
Abrahamian FM, Aldape MJ, Aldasoro E, Allen UD, Al-Sum H, Anadkat MJ, Anders K, Angelakis E, Angus BJ, Antoniadou A, Arena F, Arends JE, Arribas JR, Artenstein AW, Atherton JC, Aucott JN, Aw TC, Babcock HM, Bailey R, Bailey TC, Banks AZ, Barillo DJ, Barrette EP, Bauer MP, Bayston R, Beard CB, Beardsley J, Beeching NJ, Bégué RE, Beldi G, Benson CA, Berbari EF, Berenger JM, Berger C, Bernardino JI, Bille J, Billioux AC, Bitnun A, Blair I, Blanche S, Bleck TP, Bleeker-Rovers CP, Bleijenberg G, Bloch KC, Blum J, Blumberg EA, Bonomo RA, Bonten MJ, Bourayou R, Bouza E, Brandt KA, Bretelle F, Brisse S, Britton WJ, Brook I, Brouwer MC, Browne SK, Bryant AE, Bühler S, Bulger EM, Buller RML, Burke LA, Burri C, Butler MW, Calandra T, Calfee DP, Calvo-Cano A, Cameron DW, Carcillo JA, Carson G, Chambers ST, Charrel RN, Nguyen VCV, Chevaliez S, Chiller TM, Christaki E, Chung KK, Clifford DB, Clumeck N, Cohen J, Collinge J, Conlon CP, Conrad C, Cooke FJ, Cope JR, Corey GR, Cross JH, Cunha BA, Cunha CB, D'Journo B, Daikos GL, Daniels JM, Davidson RN, Day NP, De Cock KM, de Silva TI, de Vries HJ, de Wit S, Delaloye J, Denning DW, Dennis DT, Dhanireddy S, Dielubanza EJ, Diemert DJ, Doganay M, Doherty T, Dolecek C, Dondorp AM, Douglas A, Drancourt M, Dubourg G, Dudley MN, Durand G, Eckhardt BJ, Efstratiou A, Ekkelenkamp MB, Eranki A, Erdem H, Escota GV, Evans HL, Eziefula AC, Fenollar F, Fenwick A, Fierer J, Finch RG, Fleckenstein JM, Forstner C, Foschi F, Fournier PE, French MA, Gage KL, Garcia LS, Gascon J, Gastañaduy AS, Gautret P, Geisler WM, Ghanem KG, Giani T, Giannella M, Gilliam BL, Gilliet M, Glaser CA, Glupczynski Y, Gnann JW, Goldstein EJ, Gottstein B, Gouriet F, Gravitt PE, Green MD, Green ST, Groll AH, Gulick RM, Gupta A, Habib G, Harbarth S, Harris M, Hayden FG, Hetem DJ, Hill PC, Hirschel B, Hodowanec AC, Hoffart L, Hoffmann C, Holland SM, Horby PW, Horne DJ, Hraiech S, Hull MW, Huttner A, Ingram RJ, Islam J, Ison MG, James SH, Jenkins C, Jenkins SG, Jensen JS, Johnston C, Jones TB, Jordan SJ, Julian KG, Kato Y, Kauffman CA, Kaye KS, Keane MP, Keeney J, Kelly P, Kent SJ, Kern WV, Keynan Y, Kim AA, Koné-Paut I, Kosmidis C, Kroes AC, Kroon FP, Ksiazek TG, Kuhlmann FM, Kuijper EJ, Kwon JH, Kyei GB, Lacombe K, Lagacé-Wiens P, Lagier JC, Lamagni T, Landraud L, Lanternier F, LaPlante KL, Lawn SD, Lawrence SJ, Leblebicioglu H, Lee N, Leggett JE, Lehours P, Levy PY, Leyh RG, Lillis RA, Limmathurotsakul D, Lin J, Lindquist HA, Lipsky BA, Liscynesky C, Looney D, Lortholary O, Lowy FD, Luft BJ, Mackowiak PA, MacPherson PA, Maghraoui-Slim V, Mallon PW, Mangino JE, Manuel O, Marchetti O, Marks KM, Marr KA, Marrazzo J, Marschall J, Martin DH, Matonti F, Matulewicz RS, Mayer KH, McCulloh RJ, McGready R, Mdodo R, Mead S, Mégraud F, Meintjes G, Metcalf SC, Michaels MG, Migliori GB, Miles MA, Miller A, Mimiaga MJ, Mingeot-Leclercq MP, Misch EA, Mitreva M, Montaner JS, Moore CB, Muñoz P, Muñoz J, Murray CK, Musso D, Mutengo M, Mutizwa MM, Naber KG, Natarajan P, Neme S, Newton PN, Nichols RA, Nicolle LE, Nosten F, Notarangelo LD, Nutman TB, Nyirjesy P, O'Connell PR, Opal SM, Ormerod LP, Osmon DR, Pankert MB, Pantaleo G, Papazian L, Parente DM, Parola P, Parsaei S, Pascual MA, Patel R, Patrozou E, Pawlotsky JM, Peacock SJ, Pechère JC, Pelegrin I, Peters BS, Peters EJ, Petersen JM, Petersen LR, Petraitis V, Pham LL, Picado A, Pilatz A, Pilmis B, Pinazo MJ, Pletz MW, Pogue JM, Polgreen EL, Polgreen PM, Posfay-Barbe KM, Powderly WG, Presti R, Prod'hom G, Puolakkainen M, Quinn TC, Raoult D, Razonable RR, Read RC, Redfield RR, Rentenaar RJ, Reynolds SJ, Ribi C, Richardson MD, Ritter ML, Roch A, Rockstroh JK, Rojek A, Romero JR, Rooijakkers SH, Rosenbluth D, Rosenzweig SD, Rossolini GM, Rubinstein E, Ryan G, Safren SA, Sahasrabuddhe VV, Saikku PA, Sajadi MM, Salvaggio MR, Santos CA, Satlin MJ, Schaeffer AJ, Schimmer C, Schooley RT, Schumacher RF, Sha BE, Shapiro DS, Sheehan G, Shlaes DM, Shoham S, Simmons CP, Simon DW, Simon MS, Simonsen KA, Slack MP, Smith TT, Sobel JD, Souli M, Sridhar S, Steckelberg JM, Stevens DL, Strah H, Sturm AW, Sungkanuparph S, Tabrizi SJ, Tacconelli E, Tan CS, Taplitz RA, Thomas G, Thomas LD, Thuny F, Thwaites G, Tissot F, Tønjum T, Torriani FJ, Toso C, Tulkens PM, Tunkel AR, Turner CE, Ustianowski AP, van Bambeke F, van Crevel R, van de Beek D, van Delden C, van der Eerden MM, van der Meer JW, van der Poll T, van Ingen J, van Putten J, Vaudaux BP, Vermund SH, Viscidi RP, Visvanathan K, Visvesvara GS, von Seidlein L, Wagenlehner FM, Wald A, Walsh TJ, Warhurst DC, Warnock DW, Warrell DA, Warrell MJ, Warris A, Watkins RR, Weatherall DJ, Weber R, Weidner W, White JR, White PJ, Whitehorn J, Whitley RJ, Whitty CJ, Wiersinga WJ, Wilcox MH, Williams TN, Wilson CC, Wilson ME, Wisplinghoff H, Wood R, Wunderink RG, Wyles D, Yang ZT, Yoder JS, Zaidi NA, Zimmer AJ, Zuckerman JN, Zumla A. List of Contributors. Infect Dis (Lond) 2017. [DOI: 10.1016/b978-0-7020-6285-8.00234-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
|
31
|
Kuhlmann FM, Santhanam S, Kumar P, Luo Q, Ciorba MA, Fleckenstein JM. Blood Group O-Dependent Cellular Responses to Cholera Toxin: Parallel Clinical and Epidemiological Links to Severe Cholera. Am J Trop Med Hyg 2016; 95:440-3. [PMID: 27162272 DOI: 10.4269/ajtmh.16-0161] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/01/2016] [Indexed: 12/25/2022] Open
Abstract
Because O blood group has been associated with more severe cholera infections, it has been hypothesized that cholera toxin (CT) may bind non-O blood group antigens of the intestinal mucosae, thereby preventing efficient interaction with target GM1 gangliosides required for uptake of the toxin and activation of cyclic adenosine monophosphate (cAMP) signaling in target epithelia. Herein, we show that after exposure to CT, human enteroids expressing O blood group exhibited marked increase in cAMP relative to cells derived from blood group A individuals. Likewise, using CRISPR/Cas9 engineering, a functional group O line (HT-29-A(-/-)) was generated from a parent group A HT-29 line. CT stimulated robust cAMP responses in HT-29-A(-/-) cells relative to HT-29 cells. These findings provide a direct molecular link between blood group O expression and differential cellular responses to CT, recapitulating clinical and epidemiologic observations.
Collapse
Affiliation(s)
- F Matthew Kuhlmann
- Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri
| | - Srikanth Santhanam
- Division of Gastroenterology, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri
| | - Pardeep Kumar
- Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri
| | - Qingwei Luo
- Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri
| | - Matthew A Ciorba
- Division of Gastroenterology, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri. Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, Saint Louis, Missouri
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri. Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, Saint Louis, Missouri. Veterans Affairs Medical Center, Saint Louis, Missouri.
| |
Collapse
|
32
|
Abstract
Enterotoxigenic Escherichia coli (ETEC) are a genetically diverse E. coli pathovar that share in the ability to produce heat-labile toxin and/or heat-stable toxins. While these pathogens contribute substantially to the burden of diarrheal illness in developing countries, at present, there is no suitable broadly protective vaccine to prevent these common infections. Most vaccine development attempts to date have followed a classical approach involving a relatively small group of antigens. The extraordinary underlying genetic plasticity of E. coli has confounded the antigen valency requirements based on this approach. The recent discovery of additional virulence proteins within this group of pathogens, as well as the availability of whole-genome sequences from hundreds of ETEC strains to facilitate identification of conserved molecules, now permits a reconsideration of the classical approaches, and the exploration of novel antigenic targets to complement existing strategies overcoming antigenic diversity that has impeded progress toward a broadly protective vaccine. Progress to date in antigen discovery and methods currently available to explore novel immunogens are outlined here.
Collapse
Affiliation(s)
- James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, Campus Box 8051, 660 South Euclid Avenue, St. Louis, MO, USA.
- Molecular Microbiology and Molecular Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO, USA.
- Medicine Service, Veterans Affairs Medical Center, St. Louis, MO, USA.
| | - David A Rasko
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| |
Collapse
|
33
|
Luo Q, Qadri F, Kansal R, Rasko DA, Sheikh A, Fleckenstein JM. Conservation and immunogenicity of novel antigens in diverse isolates of enterotoxigenic Escherichia coli. PLoS Negl Trop Dis 2015; 9:e0003446. [PMID: 25629897 PMCID: PMC4309559 DOI: 10.1371/journal.pntd.0003446] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 11/26/2014] [Indexed: 12/12/2022] Open
Abstract
Background Enterotoxigenic Escherichia coli (ETEC) are common causes of diarrheal morbidity and mortality in developing countries for which there is currently no vaccine. Heterogeneity in classical ETEC antigens known as colonization factors (CFs) and poor efficacy of toxoid-based approaches to date have impeded development of a broadly protective ETEC vaccine, prompting searches for novel molecular targets. Methodology Using a variety of molecular methods, we examined a large collection of ETEC isolates for production of two secreted plasmid-encoded pathotype-specific antigens, the EtpA extracellular adhesin, and EatA, a mucin-degrading serine protease; and two chromosomally-encoded molecules, the YghJ metalloprotease and the EaeH adhesin, that are not specific to the ETEC pathovar, but which have been implicated in ETEC pathogenesis. ELISA assays were also performed on control and convalescent sera to characterize the immune response to these antigens. Finally, mice were immunized with recombinant EtpA (rEtpA), and a protease deficient version of the secreted EatA passenger domain (rEatApH134R) to examine the feasibility of combining these molecules in a subunit vaccine approach. Principal Findings EtpA and EatA were secreted by more than half of all ETEC, distributed over diverse phylogenetic lineages belonging to multiple CF groups, and exhibited surprisingly little sequence variation. Both chromosomally-encoded molecules were also identified in a wide variety of ETEC strains and YghJ was secreted by 89% of isolates. Antibodies against both the ETEC pathovar-specific and conserved E. coli antigens were present in significantly higher titers in convalescent samples from subjects with ETEC infection than controls suggesting that each of these antigens is produced and recognized during infection. Finally, co-immunization of mice with rEtpA and rEatApH134R offered significant protection against ETEC infection. Conclusions Collectively, these data suggest that novel antigens could significantly complement current approaches and foster improved strategies for development of broadly protective ETEC vaccines. Infectious diarrhea is one of the leading causes of death among young children in developing countries, and a major cause of morbidity in all age groups. The enterotoxigenic Escherichia coli contribute substantially to this burden of diarrheal illness, and have been a focus of vaccine development efforts for more than forty years following their discovery as a cause of severe diarrheal illness. The heat-labile, and/or heat stable enterotoxins that define ETEC are produced by a diverse population of Escherichia coli. This inherent genetic plasticity of E. coli has made it difficult to identify antigens specific to ETEC that are highly conserved. Therefore, identification of protective antigens shared by many ETEC strains will likely play an essential role in development of the next iteration of vaccines.
Collapse
Affiliation(s)
- Qingwei Luo
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh, Mohakhali, Dhaka, Bangladesh
| | - Rita Kansal
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - David A. Rasko
- Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alaullah Sheikh
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, United States of America
- * E-mail:
| |
Collapse
|
34
|
Fleckenstein JM, Sheikh A. Designing vaccines to neutralize effective toxin delivery by enterotoxigenic Escherichia coli. Toxins (Basel) 2014; 6:1799-812. [PMID: 24918359 PMCID: PMC4073130 DOI: 10.3390/toxins6061799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 04/23/2014] [Accepted: 05/15/2014] [Indexed: 12/03/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) are a leading cause of diarrheal illness in developing countries. Despite the discovery of these pathogens as a cause of cholera-like diarrhea over 40 years ago, and decades of vaccine development effort, there remains no broadly protective ETEC vaccine. The discovery of new virulence proteins and an improved appreciation of the complexity of the molecular events required for effective toxin delivery may provide additional avenues to pursue in development of an effective vaccine to prevent severe diarrhea caused by these important pathogens.
Collapse
Affiliation(s)
- James M Fleckenstein
- Division of Infectious Diseases, Washington University School of Medicine, 660 South Euclid Avenue; Saint Louis, MO 63110, USA.
| | - Alaullah Sheikh
- Molecular Microbiology and Microbiobial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, Campus Box 8051, 660 South Euclid Avenue; Saint Louis, MO 63110, USA.
| |
Collapse
|
35
|
Abstract
Enterotoxigenic Escherichia coli (ETEC) are the most common bacterial pathogens causing diarrhea in developing countries where they lead to hundreds of thousands of deaths, mostly in children. These organisms are a leading cause of diarrheal illness in travelers to endemic countries. ETEC pathogenesis, and consequently vaccine approaches, have largely focused on plasmid-encoded enterotoxins or fimbrial colonization factors. To date these approaches have not yielded a broadly protective vaccine. However, recent studies suggest that ETEC pathogenesis is more complex than previously appreciated and involves additional plasmid and chromosomally encoded virulence molecules that can be targeted in vaccines. Here, we review recent novel antigen discovery efforts, potential contribution of these proteins to the molecular pathogenesis of ETEC and protective immunity, and the potential implications for development of next generation vaccines for important pathogens. These proteins may help to improve the effectiveness of future vaccines by making them simpler and possibly broadly protective because of their conserved nature.
Collapse
Affiliation(s)
- James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, USA
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, USA
- Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, USA
| | - Alaullah Sheikh
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, USA
| | - Firdausi Qadri
- Centre for Vaccine Sciences, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| |
Collapse
|
36
|
Abstract
The enterotoxigenic Escherichia coli are a pervasive cause of serious diarrheal illness in developing countries. Presently, there is no vaccine to prevent these infections, and many features of the basic pathogenesis of these organisms remain poorly understood. Until very recently most pathogenesis studies had focused almost exclusively on a small subset of known "classical" virulence genes, namely fimbrial colonization factors and the heat-labile (LT) and heat stable (ST) enterotoxins. However, recent investigations of pathogen-host interactions reveal a surprisingly complex and intricately orchestrated engagement involving the interplay of classical and "novel" virulence genes, as well as participation of genes highly conserved in the E. coli species. These studies may inform further rational approaches to vaccine development for these important pathogens.
Collapse
Affiliation(s)
- James M Fleckenstein
- Department of Medicine; Washington University School of Medicine; St. Louis, MO USA,Medicine Service; Veterans Affairs Medical Center; St. Louis, MO USA,Correspondence to: James M Fleckenstein,
| | - George M Munson
- Department of Microbiology and Immunology; University of Miami; Miller School of Medicine; Miami, FL USA
| | - David A Rasko
- Department of Microbiology and Immunology; University of Maryland School of Medicine; Baltimore, MD USA,Institute for Genome Sciences; University of Maryland School of Medicine; Baltimore, MD USA
| |
Collapse
|
37
|
Harris JA, Roy K, Woo-Rasberry V, Hamilton DJ, Kansal R, Qadri F, Fleckenstein JM. Directed evaluation of enterotoxigenic Escherichia coli autotransporter proteins as putative vaccine candidates. PLoS Negl Trop Dis 2011; 5:e1428. [PMID: 22163060 PMCID: PMC3232201 DOI: 10.1371/journal.pntd.0001428] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022] Open
Abstract
Background Enterotoxigenic Escherichia coli (ETEC) is a major diarrheal pathogen in developing countries, where it accounts for millions of infections and hundreds of thousands of deaths annually. While vaccine development to prevent diarrheal illness due to ETEC is feasible, extensive effort is needed to identify conserved antigenic targets. Pathogenic Escherichia coli, including ETEC, use the autotransporter (AT) secretion mechanism to export virulence factors. AT proteins are comprised of a highly conserved carboxy terminal outer membrane beta barrel and a surface-exposed amino terminal passenger domain. Recent immunoproteomic studies suggesting that multiple autotransporter passenger domains are recognized during ETEC infection prompted the present studies. Methodology Available ETEC genomes were examined to identify AT coding sequences present in pathogenic isolates, but not in the commensal E. coli HS strain. Passenger domains of the corresponding autotransporters were cloned and expressed as recombinant antigens, and the immune response to these proteins was then examined using convalescent sera from patients and experimentally infected mice. Principal Findings Potential AT genes shared by ETEC strains, but absent in the E. coli commensal HS strain were identified. Recombinant passenger domains derived from autotransporters, including Ag43 and an AT designated pAT, were recognized by antibodies from mice following intestinal challenge with H10407, and both Ag43 and pAT were identified on the surface of ETEC by flow cytometry. Likewise, convalescent sera from patients with ETEC diarrhea recognized Ag43 and pAT, suggesting that these proteins are expressed during both experimental and naturally occurring ETEC infections and that they are immunogenic. Vaccination of mice with recombinant passenger domains from either pAT or Ag43 afforded protection against intestinal colonization with ETEC. Conclusions Passenger domains of conserved autotransporter proteins could contribute to protective immune responses that develop following infection with ETEC, and these antigens consequently represent potential targets to explore in vaccine development. Diarrheal diseases are responsible for more than 1.5 million deaths annually in developing countries. Enterotoxigenic E. coli (ETEC) are among the most common bacterial causes of diarrhea, accounting for an estimated 300,000–500,000 deaths each year, mostly in young children. There unfortunately is not yet a vaccine that can offer sustained, broad-based protection against ETEC. While most vaccine development effort has focused on plasmid-encoded finger-like ETEC adhesin structures known as colonization factors, additional effort is needed to identify conserved target antigens. Epidemiologic studies suggest that immune responses to uncharacterized, chromosomally encoded antigens could contribute to protection resulting from repeated infections. Earlier studies of immune responses to ETEC infection had identified a class of surface-expressed molecules known as autotransporters (AT). Therefore, available ETEC genome sequences were examined to identify conserved ETEC autotransporters not shared by the commensal E. coli HS strain, followed by studies of the immune response to these antigens, and tests of their utility as vaccine components. Two chromosomally encoded ATs, identified in ETEC, but not in HS, were found to be immunogenic and protective in an animal model, suggesting that conserved AT molecules contribute to protective immune responses that follow natural ETEC infection and offering new potential targets for vaccines.
Collapse
Affiliation(s)
- Jessica A. Harris
- University of Tennessee College of Medicine, Memphis, Tennessee, United States of America
| | - Koushik Roy
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, Tennessee, United States of America
| | - Virginia Woo-Rasberry
- Research Services, Veterans Affairs Medical Center, Memphis, Tennessee, United States of America
| | - David J. Hamilton
- Department of Comparative Medicine, University of Tennessee Health Sciences Center, Memphis, Tennessee, United States of America
| | - Rita Kansal
- Research Services, Veterans Affairs Medical Center, Memphis, Tennessee, United States of America
| | - Firdausi Qadri
- International Centre for Diarrheal Disease Research, Dhaka, Bangladesh
| | - James M. Fleckenstein
- Department of Medicine, University of Tennessee Health Sciences Center, Memphis, Tennessee, United States of America
- Department of Molecular Sciences, University of Tennessee Health Sciences Center, Memphis, Tennessee, United States of America
- Department of Medicine, Veterans Affairs Medical Center, Memphis, Tennessee, United States of America
- * E-mail:
| |
Collapse
|
38
|
Roy K, Kansal R, Bartels SR, Hamilton DJ, Shaaban S, Fleckenstein JM. Adhesin degradation accelerates delivery of heat-labile toxin by enterotoxigenic Escherichia coli. J Biol Chem 2011; 286:29771-9. [PMID: 21757737 PMCID: PMC3191018 DOI: 10.1074/jbc.m111.251546] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 07/07/2011] [Indexed: 12/12/2022] Open
Abstract
Many enteric pathogens, including enterotoxigenic Escherichia coli (ETEC), produce one or more serine proteases that are secreted via the autotransporter (or type V) bacterial secretion pathway. These molecules have collectively been referred to as SPATE proteins (serine protease autotransporter of the Enterobacteriaceae). EatA, an autotransporter previously identified in ETEC, possesses a functional serine protease motif within its secreted amino-terminal passenger domain. Although this protein is expressed by many ETEC strains and is highly immunogenic, its precise function is unknown. Here, we demonstrate that EatA degrades a recently characterized adhesin, EtpA, resulting in modulation of bacterial adhesion and accelerated delivery of the heat-labile toxin, a principal ETEC virulence determinant. Antibodies raised against the passenger domain of EatA impair ETEC delivery of labile toxin to epithelial cells suggesting that EatA may be an effective target for vaccine development.
Collapse
Affiliation(s)
| | - Rita Kansal
- Research Services, Veterans Affairs Medical Center, Memphis, Tennessee 38104, and
| | | | | | - Salwa Shaaban
- the Faculty of Pharmacy, Beni-Sueif University, 62514 Beni-Sueif, Egypt
| | - James M. Fleckenstein
- From the Departments of Medicine
- Molecular Sciences, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163
- the Medicine and
| |
Collapse
|
39
|
Abstract
Leishmania species are obligate intracellular parasites transmitted by various types of female sand flies. The clinical syndrome that results depends on a number of factors including the Leishmania species and immune response of the host. Here, we report successful treatment of lingual leishmaniasis complicating visceral disease in an immunocompetent patient.
Collapse
Affiliation(s)
- Shirin A Mazumder
- Division of Infectious Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA.
| | | | | | | | | | | | | |
Collapse
|
40
|
Fleckenstein JM, Hardwidge PR, Munson GP, Rasko DA, Sommerfelt H, Steinsland H. Molecular mechanisms of enterotoxigenic Escherichia coli infection. Microbes Infect 2010; 12:89-98. [PMID: 19883790 PMCID: PMC10647112 DOI: 10.1016/j.micinf.2009.10.002] [Citation(s) in RCA: 202] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 10/22/2009] [Accepted: 10/24/2009] [Indexed: 10/20/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) are a major cause of diarrheal illness in developing countries, and perennially the most common cause of traveller's diarrhea. ETEC constitute a diverse pathotype that elaborate heat-labile and/or heat-stable enterotoxins. Recent molecular pathogenesis studies reveal sophisticated pathogen-host interactions that might be exploited in efforts to prevent these important infections. While vaccine development for these important pathogens remains a formidable challenge, extensive efforts that attempt to exploit new genomic and proteomic technology platforms in discovery of novel targets are presently ongoing.
Collapse
|
41
|
Abstract
This protocol describes the purification of a recombinant high molecular weight (HMW) two-partner secretion exoprotein (generically referred to as TpsA proteins) from Escherichia coli using methods developed recently to obtain highly purified flagellin-free recombinant EtpA (rEtpA) glycoprotein. The protocol addresses problems frequently encountered with the expression of these HMW proteins, namely plasmid instability and protein degradation, as well as a recently recognized issue of flagellin contamination. Briefly, the TpsA protein of interest is expressed with its outer membrane transporter (TpsB) protein in a flagellin-minus recombinant E. coli background. Culture supernatants are collected, concentrated through high molecular weight cutoff filters, followed by purification by size exclusion column chromatography. Details are included for the expression of HMW TpsA glycoproteins as polyhistidine-tagged molecules, which can be further purified by metal affinity chromatography (MAC). Using this protocol, it is possible to obtain highly purified microgram-milligram quantities of the TpsA protein of interest within 2-3 days.
Collapse
Affiliation(s)
- James M Fleckenstein
- Department of Veterans Affairs Medical Center Research (151), Memphis, Tennessee, USA.
| | | |
Collapse
|
42
|
Roy K, Hamilton D, Ostmann MM, Fleckenstein JM. Vaccination with EtpA glycoprotein or flagellin protects against colonization with enterotoxigenic Escherichia coli in a murine model. Vaccine 2009; 27:4601-8. [DOI: 10.1016/j.vaccine.2009.05.076] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 05/07/2009] [Accepted: 05/27/2009] [Indexed: 11/17/2022]
|
43
|
Abstract
Enterotoxigenic Escherichia coli (ETEC), leading causes of diarrhoeal morbidity and mortality in developing countries, are heterogenous pathogens that elaborate heat-labile (LT) and/or heat-stable (ST) enterotoxins which elicit watery, cholera-like diarrhoea. The molecular events permitting efficient delivery of LT remain undefined. Here, we characterize the role of host-pathogen interaction as it relates to the delivery of LT by ETEC. Separation of bacteria from target intestinal epithelial monolayers by semipermeable filters prevented activation of adenylate cyclase suggesting that pathogen-host cell contact is required for efficient toxin delivery. Likewise, a non-motile strain bearing a mutation in the flagellar fliD gene was deficient in delivery of LT relative to the ETEC (H10407) prototype. Although LT secretion via the type II secretion system (T2SS) was responsive to a variety of environmental factors, neither toxin release nor delivery depended on transcriptional activation of genes encoding LT or the T2SS. Fusions of green fluorescent protein to GspM (a component of the T2SS system for LT) and to LT demonstrated that both T2SS and toxin are distributed at one pole of the ETEC bacterium. Optimal LT delivery may occur in a polarized fashion with transfer of preformed toxin upon close interaction with host cells, preventing neutralization of LT.
Collapse
Affiliation(s)
- F Chuck Dorsey
- Research Service, Veterans Affairs Medical Center, Memphis, TN, USA
| | | | | |
Collapse
|
44
|
Abstract
Enterotoxigenic Escherichia coli (ETEC) remains a formidable cause of diarrheal illness worldwide. At present, there is no vaccine that provides broad-based protection against ETEC. A 'phoA-based self-cloning mutagenesis system, TnphoA.ts, employed to identify novel ETEC surface antigens, led to identification of an ETEC two-partner secretion locus (etpBAC) on the pCS1 virulence plasmid of prototype strain H10407. Cloning and expression of etpBAC in recombinant E. coli LMG194(pJY019) resulted in secretion of a high-molecular-weight (HMW) glycosylated exoprotein. This glycoprotein, EtpA, exhibits linear peptide sequence and predicted structural homologies with known HMW adhesins produced by other two-partner secretion loci. Antibodies directed against recombinant EtpA (anti-rEtpA.6H) recognized an HMW protein in culture supernatants of ETEC strains H10407 and LMG194(pJY019) but not in culture supernatant of strain H10407-P, which lacks the 92-kb pCS1 plasmid, or an isogenic etpA mutant. etpA mutants were deficient in adherence to intestinal epithelial cells in vitro, and anti-rEtpA.6H antibodies inhibited association of H10407 with target epithelial cells. Cloning and expression of etpB in recombinant E. coli were sufficient to confer adherence. Screening of multiple ETEC isolates for the etpBAC locus by colony hybridization and by EtpA immunoblotting suggested that EtpA is one of the most common antigens secreted by these pathogens. Together, these results indicate that the newly identified ETEC two-partner secretion locus directs the secretion of a high-molecular-weight glycosylated protein, EtpA, that in concert with the putative EtpB transporter participates in adherence of H10407 to epithelial cells, thereby expanding the repertoire of potential ETEC virulence proteins and vaccine candidates.
Collapse
Affiliation(s)
- James M Fleckenstein
- Medicine Service (151), Veterans Affairs Medical Center, 1030 Jefferson Avenue, Memphis, TN 38104, USA.
| | | | | | | |
Collapse
|
45
|
Allen KP, Randolph MM, Fleckenstein JM. Importance of heat-labile enterotoxin in colonization of the adult mouse small intestine by human enterotoxigenic Escherichia coli strains. Infect Immun 2006; 74:869-75. [PMID: 16428729 PMCID: PMC1360293 DOI: 10.1128/iai.74.2.869-875.2006] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 08/01/2005] [Accepted: 10/21/2005] [Indexed: 01/28/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) infections are a significant cause of diarrheal disease and infant mortality in developing countries. Studies of ETEC pathogenesis relevant to vaccine development have been greatly hampered by the lack of a suitable small-animal model of infection with human ETEC strains. Here, we demonstrate that adult immunocompetent outbred mice can be effectively colonized with the prototypical human ETEC H10407 strain (colonization factor antigen I; heat-labile and heat-stable enterotoxin positive) and that production of heat-labile holotoxin provides a significant advantage in colonization of the small intestine in this model.
Collapse
Affiliation(s)
- Kenneth P Allen
- Department of Comparative Medicine, University of Tenessee Health Science Center, Memphis, TN 38104, USA
| | | | | |
Collapse
|
46
|
Patel SK, Dotson J, Allen KP, Fleckenstein JM. Identification and molecular characterization of EatA, an autotransporter protein of enterotoxigenic Escherichia coli. Infect Immun 2004; 72:1786-94. [PMID: 14977988 PMCID: PMC356008 DOI: 10.1128/iai.72.3.1786-1794.2004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) strains remain a formidable cause of diarrheal disease. To identify novel surface proteins of ETEC, we performed TnphoA mutagenesis of prototype ETEC strain H10407 and discovered a secreted protein not previously recognized in ETEC. DNA sequencing of the interrupted locus in mutant TnphoA.977 revealed a candidate 4,095-bp open reading frame without significant homology to commensal E. coli K-12 genomic DNA. Translation of this sequence revealed that it encoded a predicted peptide of 147.7 kDa that bears significant homology to members of the autotransporter family of bacterial virulence factors, particularly the serine protease autotransporters of the Enterobacteriaceae proteins. The gene identified in H10407, eatA (ETEC autotransporter A), encodes a potential serine protease motif (GDSGSP) in the secreted amino-terminal domain, and the predicted peptide shows more than 80% homology with SepA, a virulence protein secreted by Shigella flexneri. DNA hybridization and PCR demonstrated that eatA resides on the 92-kDa pCS1 virulence plasmid of H10407 and that it is present in multiple clinical ETEC strains. Immunoblots with antisera directed against a recombinant EatA passenger protein fragment identified a 110-kDa protein in supernatants purified from H10407 but not from the TnphoA.977 mutant or H10407-P, which lacks pCS1. EatA possesses serine protease activity that is abolished by mutations within a serine protease catalytic triad formed by residues H(134), D(162), and S(267). Finally, interruption of the eatA gene retarded fluid accumulation in the rabbit ileal loop model, suggesting that this autotransporter contributes to the virulence of ETEC.
Collapse
Affiliation(s)
- Seema K Patel
- Department of Medicine, University of Tennessee Health Science Center, Veterans Affairs Medical Center, Memphis, Tennessee, USA
| | | | | | | |
Collapse
|
47
|
Patel SK, Fleckenstein JM. 323 FUNCTIONAL CHARACTERIZATION OF EATA, AN AUTOTRANSPORTER PROTEN OF ENTEROTOXIGENIC E. COLI. J Investig Med 2004. [DOI: 10.1136/jim-52-suppl1-876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
48
|
Patel SK, Fleckenstein JM. 158 FUNCTIONAL CHARACTERIZATION OF EATA, AN AUTOTRANSPORTER PROTEN OF ENTEROTOXIGENIC E. COLI. J Investig Med 2004. [DOI: 10.1136/jim-52-suppl1-711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
49
|
Fleckenstein JM, Holland JT, Hasty DL. Interaction of an uuter membrane protein of enterotoxigenic Escherichia coli with cell surface heparan sulfate proteoglycans. Infect Immun 2002; 70:1530-7. [PMID: 11854241 PMCID: PMC127767 DOI: 10.1128/iai.70.3.1530-1537.2002] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously shown that enterotoxigenic invasion protein A (Tia), a 25-kDa outer membrane protein encoded on an apparent pathogenicity island of enterotoxigenic Escherichia coli (ETEC) strain H10407, mediates attachment to and invasion into cultured human gastrointestinal epithelial cells. The epithelial cell receptor(s) for Tia has not been identified. Here we show that Tia interacts with cell surface heparan sulfate proteoglycans. Recombinant E. coli expressing Tia mediated invasion into wild-type epithelial cell lines but not invasion into proteoglycan-deficient cells. Furthermore, wild-type eukaryotic cells, but not proteoglycan-deficient eukaryotic cells, attached to immobilized polyhistidine-tagged recombinant Tia (rTia). Binding of epithelial cells to immobilized rTia was inhibited by exogenous heparan sulfate glycosaminoglycans but not by hyaluronic acid, dermatan sulfate, or chondroitin sulfate. Similarly, pretreatment of eukaryotic cells with heparinase I, but not pretreatment of eukaryotic cells with chrondroitinase ABC, inhibited attachment to rTia. In addition, we also observed heparin binding to both immobilized rTia and recombinant E. coli expressing Tia. Heparin binding was inhibited by a synthetic peptide representing a surface loop of Tia, as well as by antibodies directed against this peptide. Additional studies indicated that Tia, as a prokaryotic heparin binding protein, may also interact via sulfated proteoglycan molecular bridges with a number of mammalian heparan sulfate binding proteins. These findings suggest that the binding of Tia to host epithelial cells is mediated at least in part through heparan sulfate proteoglycans and that ETEC belongs on the growing list of pathogens that utilize these ubiquitous cell surface molecules as receptors.
Collapse
Affiliation(s)
- James M Fleckenstein
- Medicine Services, Veterans Affairs Medical Center, Memphis, Tennessee 38104, USA.
| | | | | |
Collapse
|
50
|
Fleckenstein JM, Kopecko DJ. Breaching the mucosal barrier by stealth: an emerging pathogenic mechanism for enteroadherent bacterial pathogens. J Clin Invest 2001; 107:27-30. [PMID: 11134175 PMCID: PMC198550 DOI: 10.1172/jci11792] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- J M Fleckenstein
- Medicine Service, Veterans Affairs Medical Center, Memphis, Tennessee 38104, USA
| | | |
Collapse
|