1
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Barreiro DS, Oliveira RN, Pauleta SR. Bacterial peroxidases – Multivalent enzymes that enable the use of hydrogen peroxide for microaerobic and anaerobic proliferation. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2023.215114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2023]
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2
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Connections between Exoproteome Heterogeneity and Virulence in the Oral Pathogen Aggregatibacter actinomycetemcomitans. mSystems 2022; 7:e0025422. [PMID: 35695491 PMCID: PMC9239275 DOI: 10.1128/msystems.00254-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans is a Gram-negative bacterial pathogen associated with severe periodontitis and nonoral diseases. Clinical isolates of A. actinomycetemcomitans display a rough (R) colony phenotype with strong adherent properties. Upon prolonged culturing, nonadherent strains with a smooth (S) colony phenotype emerge. To date, most virulence studies on A. actinomycetemcomitans have been performed with S strains of A. actinomycetemcomitans, whereas the virulence of clinical R isolates has received relatively little attention. Since the extracellular proteome is the main bacterial reservoir of virulence factors, the present study was aimed at a comparative analysis of this subproteome fraction for a collection of R isolates and derivative S strains, in order to link particular proteins to the virulence of A. actinomycetemcomitans with serotype b. To assess the bacterial virulence, we applied different infection models based on larvae of the greater wax moth Galleria mellonella, a human salivary gland-derived epithelial cell line, and freshly isolated neutrophils from healthy human volunteers. A total number of 351 extracellular A. actinomycetemcomitans proteins was identified by mass spectrometry, with the S strains consistently showing more extracellular proteins than their parental R isolates. A total of 50 known extracellular virulence factors was identified, of which 15 were expressed by all investigated bacteria. Importantly, the comparison of differences in exoproteome composition and virulence highlights critical roles of 10 extracellular proteins in the different infection models. Together, our findings provide novel clues for understanding the virulence of A. actinomycetemcomitans and for development of potential preventive or therapeutic avenues to neutralize this important oral pathogen. IMPORTANCE Periodontitis is one of the most common inflammatory diseases worldwide, causing high morbidity and decreasing the quality of life of millions of people. The bacterial pathogen Aggregatibacter actinomycetemcomitans is strongly associated with aggressive forms of periodontitis. Moreover, it has been implicated in serious nonoral infections, including endocarditis and brain abscesses. Therefore, it is important to investigate how A. actinomycetemcomitans can cause disease. In the present study, we applied a mass spectrometry approach to make an inventory of the virulence factors secreted by different clinical A. actinomycetemcomitans isolates and derivative strains that emerged upon culturing. We subsequently correlated the secreted virulence factors to the pathogenicity of the investigated bacteria in different infection models. The results show that a limited number of extracellular virulence factors of A. actinomycetemcomitans have central roles in pathogenesis, indicating that they could be druggable targets to prevent or treat oral disease.
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3
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Miralda I, Uriarte SM. Periodontal Pathogens' strategies disarm neutrophils to promote dysregulated inflammation. Mol Oral Microbiol 2020; 36:103-120. [PMID: 33128827 PMCID: PMC8048607 DOI: 10.1111/omi.12321] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 10/16/2020] [Accepted: 10/28/2020] [Indexed: 12/26/2022]
Abstract
Periodontitis is an irreversible, chronic inflammatory disease where inflammophilic pathogenic microbial communities accumulate in the gingival crevice. Neutrophils are a major component of the innate host response against bacterial challenge, and under homeostatic conditions, their microbicidal functions typically protect the host against periodontitis. However, a number of periodontal pathogens developed survival strategies to evade neutrophil microbicidal functions while promoting inflammation, which provides a source of nutrients for bacterial growth. Research on periodontal pathogens has largely focused on a few established species: Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. However, advances in culture-independent techniques have facilitated the identification of new bacterial species in periodontal lesions, such as the two Gram-positive anaerobes, Filifactor alocis and Peptoanaerobacter stomatis, whose characterization of pathogenic potential has not been fully described. Additionally, there is not a full understanding of the pathogenic mechanisms used against neutrophils by organisms that are abundant in periodontal lesions. This presents a substantial barrier to the development of new approaches to prevent or ameliorate the disease. In this review, we first summarize the neutrophil functions affected by the established periodontal pathogens listed above, denoting unknown areas that still merit a closer look. Then, we review the literature on neutrophil functions and the emerging periodontal pathogens, F. alocis and P. stomatis, comparing the effects of the emerging microbes to that of established pathogens, and speculate on the contribution of these putative pathogens to the progression of periodontal disease.
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Affiliation(s)
- Irina Miralda
- Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, KY, USA
| | - Silvia M Uriarte
- Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, KY, USA
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4
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Belibasakis GN, Maula T, Bao K, Lindholm M, Bostanci N, Oscarsson J, Ihalin R, Johansson A. Virulence and Pathogenicity Properties of Aggregatibacter actinomycetemcomitans. Pathogens 2019; 8:E222. [PMID: 31698835 PMCID: PMC6963787 DOI: 10.3390/pathogens8040222] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 10/29/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
Aggregatibacter actinomycetemcomitans is a periodontal pathogen colonizing the oral cavity of a large proportion of the human population. It is equipped with several potent virulence factors that can cause cell death and induce or evade inflammation. Because of the large genetic diversity within the species, both harmless and highly virulent genotypes of the bacterium have emerged. The oral condition and age, as well as the geographic origin of the individual, influence the risk to be colonized by a virulent genotype of the bacterium. In the present review, the virulence and pathogenicity properties of A. actinomycetemcomitans will be addressed.
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Affiliation(s)
- Georgios N. Belibasakis
- Division of Oral Diseases, Department of Dental Medicine, Karolinska Institutet, S-141 04 Huddinge, Sweden; (G.N.B.); (K.B.); (N.B.)
| | - Terhi Maula
- Department of Biochemistry, University of Turku, FI-20014 Turku, Finland; (T.M.); (R.I.)
| | - Kai Bao
- Division of Oral Diseases, Department of Dental Medicine, Karolinska Institutet, S-141 04 Huddinge, Sweden; (G.N.B.); (K.B.); (N.B.)
| | - Mark Lindholm
- Department of Odontology, Umeå University, S-901 87 Umeå, Sweden; (M.L.); (J.O.)
| | - Nagihan Bostanci
- Division of Oral Diseases, Department of Dental Medicine, Karolinska Institutet, S-141 04 Huddinge, Sweden; (G.N.B.); (K.B.); (N.B.)
| | - Jan Oscarsson
- Department of Odontology, Umeå University, S-901 87 Umeå, Sweden; (M.L.); (J.O.)
| | - Riikka Ihalin
- Department of Biochemistry, University of Turku, FI-20014 Turku, Finland; (T.M.); (R.I.)
| | - Anders Johansson
- Department of Odontology, Umeå University, S-901 87 Umeå, Sweden; (M.L.); (J.O.)
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5
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Balashova N, Giannakakis A, Brown AC, Koufos E, Benz R, Arakawa T, Tang HY, Lally ET. Generation of a recombinant Aggregatibacter actinomycetemcomitans RTX toxin in Escherichia coli. Gene 2018; 672:106-114. [PMID: 29879499 DOI: 10.1016/j.gene.2018.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/28/2018] [Accepted: 06/03/2018] [Indexed: 10/14/2022]
Abstract
A leukotoxin (LtxA) that is produced by Aggregatibacter actinomycetemcomitans (Aa) is an important virulence determinant in an aggressive form of periodontitis in adolescents. Understanding the function of this protein at the molecular level is critical to elucidating its role in the disease process. To accomplish genetic analysis of the protein structure and relating these observations to toxin function, we have developed an E. coli expression system for the generation and rapid purification of LtxA. Cloning the structural toxin gene, ltxA, from Aa strain JP2 under control of T7 promoter-1 of pCDFDuet-1 vector resulted in expression of a 114 KDa protein which could be easily purified by the presence of a carboxy-terminal engineered double hexahistidine (double-His6) tag and was immunologically reactive with an anti-LtxA monoclonal antibody, but was not cytotoxic. Cloning a second gene, ltxC, an acyltransferase gene, into the vector under control of T7 promoter-2, resulted in expression of the biologically active LtxA. The toxin was extracted from E. coli inclusion bodies, purified by immobilized metal affinity chromatography, and refolded by dialysis. When compared by circular dichroism (CD) spectroscopy analysis, acylated recombinant LtxA has a secondary structure consistent with wt LtxA, while variations in α-helical structure of nonacylated LtxA were observed. No modifications in α-helix were found upon the toxin's binding with liposome-incorporated cholesterol. Our results suggest that pure, biologically active recombinant LtxA can be isolated by a one-step affinity chromatography from E. coli. The toxic and structural properties of the recombinant LtxA are similar to its wt counterpart.
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Affiliation(s)
- Nataliya Balashova
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Alexander Giannakakis
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Angela C Brown
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA
| | - Evan Koufos
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA, USA
| | - Roland Benz
- Department of Life Science and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Tsutomu Arakawa
- Alliance Protein Laboratories, a Division of KBI Biopharma, San Diego, CA, USA
| | - Hsin-Yao Tang
- Proteomics and Metabolomics Facility, The Wistar Institute, Philadelphia, PA, USA
| | - Edward T Lally
- Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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6
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Kanzaki H, Wada S, Narimiya T, Yamaguchi Y, Katsumata Y, Itohiya K, Fukaya S, Miyamoto Y, Nakamura Y. Pathways that Regulate ROS Scavenging Enzymes, and Their Role in Defense Against Tissue Destruction in Periodontitis. Front Physiol 2017; 8:351. [PMID: 28611683 PMCID: PMC5447763 DOI: 10.3389/fphys.2017.00351] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/15/2017] [Indexed: 01/04/2023] Open
Abstract
Periodontitis, an inflammatory disease that affects the tissues surrounding the teeth, is a common disease worldwide. It is caused by a dysregulation of the host inflammatory response to bacterial infection, which leads to soft and hard tissue destruction. In particular, it is the excessive inflammation in response to bacterial plaque that leads to the release of reactive oxygen species (ROS) from neutrophils, which, then play a critical role in the destruction of periodontal tissue. Generally, ROS produced from immune cells exhibit an anti-bacterial effect and play a role in host defense and immune regulation. Excessive ROS, however, can exert cytotoxic effects, cause oxidative damage to proteins, and DNA, can interfere with cell growth and cell cycle progression, and induce apoptosis of gingival fibroblasts. Collectively, these effects enable ROS to directly induce periodontal tissue damage. Some ROS also act as intracellular signaling molecules during osteoclastogenesis, and can thus also play an indirect role in bone destruction. Cells have several protective mechanisms to manage such oxidative stress, most of which involve production of cytoprotective enzymes that scavenge ROS. These enzymes are transcriptionally regulated via NRF2, Sirtuin, and FOXO. Some reports indicate an association between periodontitis and these cytoprotective enzymes' regulatory axes, with superoxide dismutase (SOD) the most extensively investigated. In this review article, we discuss the role of oxidative stress in the tissue destruction manifest in periodontitis, and the mechanisms that protect against this oxidative stress.
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Affiliation(s)
- Hiroyuki Kanzaki
- Maxillo-Oral Disorders, Tohoku University HospitalSendai, Japan.,Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Satoshi Wada
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Tsuyoshi Narimiya
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Yuuki Yamaguchi
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Yuta Katsumata
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Kanako Itohiya
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Sari Fukaya
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Yutaka Miyamoto
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
| | - Yoshiki Nakamura
- Department of Orthodontics, School of Dental Medicine, Tsurumi UniversityYokohama, Japan
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7
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Smith KP, Fields JG, Voogt RD, Deng B, Lam YW, Mintz KP. Alteration in abundance of specific membrane proteins of Aggregatibacter actinomycetemcomitans is attributed to deletion of the inner membrane protein MorC. Proteomics 2015; 15:1859-67. [PMID: 25684173 DOI: 10.1002/pmic.201400505] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 01/08/2015] [Accepted: 02/09/2015] [Indexed: 12/31/2022]
Abstract
Aggregatibacter actinomycetemcomitans is an important pathogen in the etiology of human periodontal and systemic diseases. Inactivation of the gene coding for the inner membrane protein, morphogenesis protein C (MorC), results in pleotropic effects pertaining to the membrane structure and function of this bacterium. The role of this protein in membrane biogenesis is unknown. To begin to understand the role of this conserved protein, stable isotope dimethyl labeling in conjunction with MS was used to quantitatively analyze differences in the membrane proteomes of the isogenic mutant and wild-type strain. A total of 613 proteins were quantified and 601 of these proteins were found to be equal in abundance between the two strains. The remaining 12 proteins were found in lesser (10) or greater (2) abundance in the membrane preparation of the mutant strain compared with the wild-type strain. The 12 proteins were ascribed functions associated with protein quality control systems, oxidative stress responses, and protein secretion. The potential relationship between these proteins and the phenotypes of the MorC mutant strain is discussed.
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Affiliation(s)
- Kenneth P Smith
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, USA
| | - Julia G Fields
- Department of Biology, University of Vermont, Burlington, VT, USA.,Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT, USA
| | - Richard D Voogt
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, USA
| | - Bin Deng
- Department of Biology, University of Vermont, Burlington, VT, USA.,Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT, USA
| | - Ying-Wai Lam
- Department of Biology, University of Vermont, Burlington, VT, USA.,Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT, USA
| | - Keith P Mintz
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, USA
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8
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Cheng YA, Jee J, Hsu G, Huang Y, Chen C, Lin CP. A markerless protocol for genetic analysis of Aggregatibacter actinomycetemcomitans. J Formos Med Assoc 2014; 113:114-23. [PMID: 24530245 DOI: 10.1016/j.jfma.2012.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 05/09/2012] [Accepted: 05/15/2012] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND/PURPOSE The genomes of different Aggregatibacter actinomycetemcomitans (A actinomycetemcomitans) strains contain many strain-specific genes and genomic islands (defined as DNA found in some but not all strains) of unknown functions. Genetic analysis for the functions of these islands will be constrained by the limited availability of genetic markers and vectors for A actinomycetemcomitans. In this study, we tested a novel genetic approach of gene deletion and restoration in a naturally competent A actinomycetemcomitans strain D7S-1. METHODS Specific genes' deletion mutants and mutants restored with the deleted genes were constructed by a markerless loxP/Cre system. In mutants with sequential deletion of multiple genes loxP with different spacer regions were used to avoid unwanted recombinations between loxP sites. RESULTS Eight single-gene deletion mutants, four multiple-gene deletion mutants, and two mutants with restored genes were constructed. No unintended non-specific deletion mutants were generated by this protocol. The protocol did not negatively affect the growth and biofilm formation of A actinomycetemcomitans. CONCLUSION The protocol described in this study is efficient and specific for genetic manipulation of A actinomycetemcomitans, and will be amenable for functional analysis of multiple genes in A actinomycetemcomitans.
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Affiliation(s)
- Ya-An Cheng
- School of Dentistry and Graduate Institute of Clinical Dentistry, National Taiwan University, Taipei, Taiwan
| | - Jason Jee
- Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA, USA
| | - Genie Hsu
- Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA, USA
| | - Yanyan Huang
- Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA, USA
| | - Casey Chen
- Division of Periodontology, Diagnostic Sciences and Dental Hygiene, Herman Ostrow School of Dentistry of the University of Southern California, Los Angeles, CA, USA
| | - Chun-Pin Lin
- School of Dentistry and Graduate Institute of Clinical Dentistry, National Taiwan University, Taipei, Taiwan.
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9
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DiFranco KM, Gupta A, Galusha LE, Perez J, Nguyen TVK, Fineza CD, Kachlany SC. Leukotoxin (Leukothera®) targets active leukocyte function antigen-1 (LFA-1) protein and triggers a lysosomal mediated cell death pathway. J Biol Chem 2012; 287:17618-17627. [PMID: 22467872 DOI: 10.1074/jbc.m111.314674] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Leukotoxin (LtxA) is a protein toxin that is secreted from the oral bacterium, Aggregatibacter actinomycetemcomitans. LtxA targets specifically the β(2) integrin, leukocyte function antigen-1 (LFA-1) on white blood cells (WBCs) and causes cell death. LtxA preferentially targets activated WBCs and is being developed as a therapeutic agent for the treatment of WBC diseases such as hematologic malignancies and autoimmune/inflammatory diseases. However, the mechanism by which interaction between LtxA and LFA-1 results in cell death is not well understood. Furthermore, how LtxA preferentially recognizes activated WBCs is not known. We show here that LtxA interacts specifically with LFA-1 in the active (exposed) conformation. In THP-1 monocytes, LtxA caused rapid activation of caspases, but LtxA could overcome the inhibition of caspases and still intoxicate. In contrast, inhibiting the vesicular trafficking pathway or cathepsin D release from the lysosome resulted in significant inhibition of LtxA-mediated cytotoxicity, indicating a more potent, lysosomal mediated cell death pathway. LtxA caused rapid disruption of the lysosomal membrane and release of lysosomal contents into the cytosol. Binding of LtxA to LFA-1 resulted in the internalization of both LtxA and LFA-1, with LtxA localizing specifically to the lysosomal compartment. To our knowledge, LtxA represents the first bacterial toxin shown to localize to the lysosome where it induces rapid cell death.
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Affiliation(s)
- Kristina M DiFranco
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Anukriti Gupta
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Lindsey E Galusha
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Jarelys Perez
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - To-Vy K Nguyen
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Camille D Fineza
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Scott C Kachlany
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103; Actinobac Biomed, Inc., North Brunswick, New Jersey 08902.
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10
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Maldonado R, Wei R, Kachlany SC, Kazi M, Balashova NV. Cytotoxic effects of Kingella kingae outer membrane vesicles on human cells. Microb Pathog 2011; 51:22-30. [PMID: 21443941 DOI: 10.1016/j.micpath.2011.03.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 03/14/2011] [Accepted: 03/16/2011] [Indexed: 11/20/2022]
Abstract
Kingella kingae is an emerging pathogen causing osteoarticular infections in pediatric patients. Electron microscopy of K. kingae clinical isolates revealed the heterogeneously-sized membranous structures blebbing from the outer membrane that were classified as outer membrane vesicles (OMVs). OMVs purified from the secreted fraction of a septic arthritis K. kingae isolate were characterized. Among several major proteins, K. kingae OMVs contained virulence factors RtxA toxin and PilC2 pilus adhesin. RtxA was also found secreted as a soluble protein in the extracellular environment indicating that the bacterium may utilize different mechanisms for the toxin delivery. OMVs were shown to be hemolytic and possess some leukotoxic activity while high leukotoxicity was detected in the non-hemolytic OMV-free component of the secreted fraction. OMVs were internalized by human osteoblasts and synovial cells. Upon interaction with OMVs, the cells produced increased levels of human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 6 (IL-6) suggesting that these cytokines might be involved in the signaling response of infected joint and bone tissues during natural K. kingae infection. This study is the first report of OMV production by K. kingae and demonstrates that OMVs are a complex virulence factor of the organism causing cytolytic and inflammatory effects on host cells.
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Affiliation(s)
- R Maldonado
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA
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11
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Johansson A. Aggregatibacter actinomycetemcomitans leukotoxin: a powerful tool with capacity to cause imbalance in the host inflammatory response. Toxins (Basel) 2011; 3:242-59. [PMID: 22069708 PMCID: PMC3202821 DOI: 10.3390/toxins3030242] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/01/2011] [Accepted: 03/08/2011] [Indexed: 11/21/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans has been described as a member of the indigenous oral microbiota of humans, and is involved in the pathology of periodontitis and various non-oral infections. This bacterium selectively kills human leukocytes through expression of leukotoxin, a large pore-forming protein that belongs to the Repeat in Toxin (RTX) family. The specificity of the toxin is related to its prerequisite for a specific target cell receptor, LFA-1, which is solely expressed on leukocytes. The leukotoxin causes death of different leukocyte populations in a variety of ways. It activates a rapid release of lysosomal enzymes and MMPs from neutrophils and causes apoptosis in lymphocytes. In the monocytes/macrophages, the toxin activates caspase-1, a cysteine proteinase, which causes a proinflammatory response by the activation and secretion of IL-1β and IL-18. A specific clone (JP2) of A. actinomycetemcomitans with enhanced leukotoxin expression significantly correlates to disease onset in infected individuals. Taken together, the mechanisms by which this toxin kills leukocytes are closely related to the pathogenic mechanisms of inflammatory disorders, such as periodontitis. Therapeutic strategies targeting the cellular and molecular inflammatory host response in periodontal diseases might be a future treatment alternative.
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Affiliation(s)
- Anders Johansson
- Department of Odontology, Umea University, SE-901 87 Umea, Sweden.
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12
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Linhartová I, Bumba L, Mašín J, Basler M, Osička R, Kamanová J, Procházková K, Adkins I, Hejnová-Holubová J, Sadílková L, Morová J, Sebo P. RTX proteins: a highly diverse family secreted by a common mechanism. FEMS Microbiol Rev 2011; 34:1076-112. [PMID: 20528947 PMCID: PMC3034196 DOI: 10.1111/j.1574-6976.2010.00231.x] [Citation(s) in RCA: 355] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Repeats-in-toxin (RTX) exoproteins of Gram-negative bacteria form a steadily growing family of proteins with diverse biological functions. Their common feature is the unique mode of export across the bacterial envelope via the type I secretion system and the characteristic, typically nonapeptide, glycine- and aspartate-rich repeats binding Ca2+ ions. In this review, we summarize the current state of knowledge on the organization of rtx loci and on the biological and biochemical activities of therein encoded proteins. Applying several types of bioinformatic screens on the steadily growing set of sequenced bacterial genomes, over 1000 RTX family members were detected, with the biological functions of most of them remaining to be characterized. Activities of the so far characterized RTX family members are then discussed and classified according to functional categories, ranging from the historically first characterized pore-forming RTX leukotoxins, through the large multifunctional enzymatic toxins, bacteriocins, nodulation proteins, surface layer proteins, up to secreted hydrolytic enzymes exhibiting metalloprotease or lipase activities of industrial interest.
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Affiliation(s)
- Irena Linhartová
- Institute of Microbiology AS CR v.v.i., Academy of Sciences of the Czech Republic, Prague, Czech Republic
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13
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Kachlany SC. Aggregatibacter actinomycetemcomitans leukotoxin: from threat to therapy. J Dent Res 2010; 89:561-70. [PMID: 20200418 DOI: 10.1177/0022034510363682] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium that colonizes the human oral cavity and is the causative agent for localized aggressive periodontitis (LAP), an aggressive form of periodontal disease that occurs in adolescents. A. actinomycetemcomitans secretes a protein toxin, leukotoxin (LtxA), which helps the bacterium evade the host immune response during infection. LtxA is a membrane-active toxin that specifically targets white blood cells (WBCs). In this review, we discuss recent developments in this field, including the identification and characterization of genes and proteins involved in secretion, regulation of LtxA, biosynthesis, newly described activities of LtxA, and how LtxA may be used as a therapy for the treatment of diseases.
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Affiliation(s)
- S C Kachlany
- Department of Oral Biology, New Jersey Dental School, University of Medicine and Dentistry of New Jersey, 185 S. Orange Avenue, Medical Science Building C-636, Newark, NJ 07103, USA.
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14
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Takashima E, Yamada H, Yajima A, Shiomi K, Ōmura S, Kiyoshi K. A quinol peroxidase inhibitor prevents secretion of a leukotoxin fromAggregatibacter actinomycetemcomitans. J Periodontal Res 2010; 45:123-8. [DOI: 10.1111/j.1600-0765.2009.01211.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Takashima E, Konishi K. Characterization of a quinol peroxidase mutant in Aggregatibacter actinomycetemcomitans. FEMS Microbiol Lett 2008; 286:66-70. [PMID: 18616592 DOI: 10.1111/j.1574-6968.2008.01253.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans is an oral pathogen causing localized aggressive periodontitis (LAP). Recently, we characterized for the first time a quinol peroxidase (QPO) that catalyzes peroxidase activity using quinol in the respiratory chain of A. actinomycetemcomitans for the reduction of hydrogen peroxide. In the present study, we characterized the phenotype of a QPO null mutant. The QPO null mutant shows an oxidative stress phenotype, suggesting that QPO plays a certain role in scavenging endogenously generated reactive oxygen species. Notably, we discovered that the QPO null mutant exhibits a production defect of leukotoxin (LtxA), which is a secreted bacterial toxin and is known to target human leukocytes and erythrocytes. This result suggests that QPO would be considered as a potential drug target to inhibit the expression of LtxA from A. actinomycetemcomitans for the treatment and prevention of LAP.
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Affiliation(s)
- Eizo Takashima
- Department of Microbiology, School of Life Dentistry at Tokyo, Nippon Dental University, Tokyo, Japan.
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