1
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Bain W, Ahn B, Peñaloza HF, McElheny CL, Tolman N, van der Geest R, Gonzalez-Ferrer S, Chen N, An X, Hosuru R, Tabary M, Papke E, Kohli N, Farooq N, Bachman W, Olonisakin TF, Xiong Z, Griffith MP, Sullivan M, Franks J, Mustapha MM, Iovleva A, Suber T, Shanks RQ, Ferreira VP, Stolz DB, Van Tyne D, Doi Y, Lee JS. In vivo evolution of a Klebsiella pneumoniae capsule defect with wcaJ mutation promotes complement-mediated opsono-phagocytosis during recurrent infection. J Infect Dis 2024:jiae003. [PMID: 38271564 DOI: 10.1093/infdis/jiae003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/17/2023] [Accepted: 01/03/2024] [Indexed: 01/27/2024] Open
Abstract
BACKGROUND Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) bloodstream infections are associated with high mortality. We studied clinical bloodstream KPC-Kp isolates to investigate mechanisms of resistance to complement, a key host defense against bloodstream infection. METHODS We tested growth of KPC-Kp isolates in human serum. In serial isolates from a single patient, we performed whole genome sequencing and tested for complement resistance and binding by mixing study, direct ELISA, flow cytometry, and electron microscopy. We utilized an isogenic deletion mutant in phagocytosis assays and an acute lung infection model. RESULTS We found serum resistance in 16 of 59 (27%) KPC-Kp clinical bloodstream isolates. In five genetically-related bloodstream isolates from a single patient, we noted a loss-of-function mutation in the capsule biosynthesis gene, wcaJ. Disruption of wcaJ was associated with decreased polysaccharide capsule, resistance to complement-mediated killing, and surprisingly, increased binding of complement proteins. Furthermore, an isogenic wcaJ deletion mutant exhibited increased opsono-phagocytosis in vitro and impaired in vivo control in the lung after airspace macrophage depletion in mice. CONCLUSIONS Loss of function in wcaJ led to increased complement resistance, complement binding, and opsono-phagocytosis, which may promote KPC-Kp persistence by enabling co-existence of increased bloodstream fitness and reduced tissue virulence.
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Affiliation(s)
- William Bain
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Veterans Health Administration Pittsburgh Healthcare System, Pittsburgh, PA, USA
| | - Brian Ahn
- Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Anschutz Medical Campus School of Medicine, Denver, CO, USA
| | - Hernán F Peñaloza
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Christi L McElheny
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nathanial Tolman
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Rick van der Geest
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Shekina Gonzalez-Ferrer
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nathalie Chen
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiaojing An
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ria Hosuru
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mohammadreza Tabary
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Erin Papke
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Naina Kohli
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nauman Farooq
- Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - William Bachman
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tolani F Olonisakin
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Zeyu Xiong
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Marissa P Griffith
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mara Sullivan
- Center for Biologic Imaging, Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jonathan Franks
- Center for Biologic Imaging, Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Mustapha M Mustapha
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Alina Iovleva
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tomeka Suber
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Robert Q Shanks
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Donna B Stolz
- Center for Biologic Imaging, Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Daria Van Tyne
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yohei Doi
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Janet S Lee
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Division of Pulmonary and Critical Care Medicine, Washington University in St. Louis, St. Louis, MO, USA
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2
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van der Lans SPA, Janet-Maitre M, Masson FM, Walker KA, Doorduijn DJ, Janssen AB, van Schaik W, Attrée I, Rooijakkers SHM, Bardoel BW. Colistin resistance mutations in phoQ can sensitize Klebsiella pneumoniae to IgM-mediated complement killing. Sci Rep 2023; 13:12618. [PMID: 37537263 PMCID: PMC10400624 DOI: 10.1038/s41598-023-39613-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 07/27/2023] [Indexed: 08/05/2023] Open
Abstract
Due to multi-drug resistance, physicians increasingly use the last-resort antibiotic colistin to treat infections with the Gram-negative bacterium Klebsiella pneumoniae. Unfortunately, K. pneumoniae can also develop colistin resistance. Interestingly, colistin resistance has dual effects on bacterial clearance by the immune system. While it increases resistance to antimicrobial peptides, colistin resistance has been reported to sensitize certain bacteria for killing by human serum. Here we investigate the mechanisms underlying this increased serum sensitivity, focusing on human complement which kills Gram-negatives via membrane attack complex (MAC) pores. Using in vitro evolved colistin resistant strains and a fluorescent MAC-mediated permeabilization assay, we showed that two of the three tested colistin resistant strains, Kp209_CSTR and Kp257_CSTR, were sensitized to MAC. Transcriptomic and mechanistic analyses focusing on Kp209_CSTR revealed that a mutation in the phoQ gene locked PhoQ in an active state, making Kp209_CSTR colistin resistant and MAC sensitive. Detailed immunological assays showed that complement activation on Kp209_CSTR in human serum required specific IgM antibodies that bound Kp209_CSTR but did not recognize the wild-type strain. Together, our results show that developing colistin resistance affected recognition of Kp209_CSTR and its killing by the immune system.
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Affiliation(s)
- Sjors P A van der Lans
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Manon Janet-Maitre
- Bacterial Pathogenesis and Cellular Responses Group, UMR5075, Institute of Structural Biology, University Grenoble Alpes, Grenoble, France
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Frerich M Masson
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Kimberly A Walker
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Dennis J Doorduijn
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Axel B Janssen
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Willem van Schaik
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Ina Attrée
- Bacterial Pathogenesis and Cellular Responses Group, UMR5075, Institute of Structural Biology, University Grenoble Alpes, Grenoble, France
| | - Suzan H M Rooijakkers
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Bart W Bardoel
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.
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3
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Opstrup KV, Christiansen G, Birkelund S. Beta-lactam induced morphological changes in serum of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae blood isolates. Microbes Infect 2023; 25:105036. [PMID: 35944888 DOI: 10.1016/j.micinf.2022.105036] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 07/15/2022] [Accepted: 07/26/2022] [Indexed: 02/04/2023]
Abstract
Klebsiella pneumoniae is an opportunistic pathogen, which frequently causes bacteremia. Ceftazidime and meropenem, two important beta-lactam antibiotics for treatment of K. pneumoniae infections, induce morphological changes in bacteria when examined in vitro. Thirty clinical Klebsiella spp. Bacteremia isolates were analyzed for antimicrobial resistance and serum resistance. To determine whether complement influenced the resistance to ceftazidime of extended-spectrum beta-lactamase producing-isolates and sensitivity to meropenem, one serum resistant and one partly serum sensitive isolate were analyzed in normal human serum, heat-inactivated human serum, and growth medium with addition of beta-lactam antibiotics. HA391 was resistant to ceftazidime and had identical minimum inhibitory concentrations for meropenem in normal human serum, heat-inactivated serum and RPMI. In normal human serum, HA233 was inhibited by ceftazidime and had lower inhibitory concentrations of meropenem. Morphological changes induced by serum and beta-lactam antibiotics were analyzed by light- and electron microscopy. Light microscopy showed elongation of bacteria treated with ceftazidime. By electron microscopy membrane attack complexes were observed for HA233 in normal human serum, thereby facilitating beta-lactam antibiotics access to the periplasmic space and the peptidoglycan layer, explaining the increased killing of HA233 by beta-lactam antibiotics. Complement did not enhance beta-lactam killing of HA391, underlining the importance of serum susceptibility.
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Affiliation(s)
- Katharina V Opstrup
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg, Denmark.
| | - Gunna Christiansen
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg, Denmark.
| | - Svend Birkelund
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg, Denmark.
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4
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Opstrup KV, Bennike TB, Christiansen G, Birkelund S. Complement killing of clinical Klebsiella pneumoniae isolates is serum concentration dependent. Microbes Infect 2022; 25:105074. [PMID: 36336240 DOI: 10.1016/j.micinf.2022.105074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022]
Abstract
Klebsiella pneumoniae is an opportunistic gram-negative pathogen causing serious infections, including sepsis. In plasma, activation of the complement cascades is important for killing bacteria. Thirty clinical Klebsiella spp. blood isolates were analyzed for serum susceptibility in 75% normal human serum (NHS). Twenty-two were serum resistant and eight were serum sensitive, and subsequently tested in 5-75% NHS. Two isolates were killed in 5% and the remaining six in 50%-75% NHS. The two 5% sensitive isolates showed binding of complement (C)4 and C3 in 5% NHS with formation of membrane attack complex (MAC). Inhibition of the classical/lectin mediated pathways (CP/LP) using a C4 specific nanobody, hC4Nb8, led to survival of both isolates in 5% NHS. Using nanobody hC3Nb1, inhibiting the alternative pathway (AP), the isolates were killed in 5% NHS, and amplification of the CP/LP by AP was not necessary for killing. Sole AP killing of these isolates when inhibiting CP/LP with hC4Nb8 was observed in 50% NHS, stressing the concentration dependent functionality of AP. For the less sensitive isolates, killing required activation of CP/LP and AP demonstrated by inhibition with nanobodies. AP inhibition resulted in no C3 deposition on the serum resistant isolate, supporting that AP was the sole activation pathway.
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Affiliation(s)
- Katharina V Opstrup
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark
| | - Tue B Bennike
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark
| | - Gunna Christiansen
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark
| | - Svend Birkelund
- Department of Health Science and Technology, Medical Microbiology and Immunology, Aalborg University, Fredrik Bajers Vej 5, 9220, Aalborg East, Denmark.
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5
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Huang X, Li X, An H, Wang J, Ding M, Wang L, Li L, Ji Q, Qu F, Wang H, Xu Y, Lu X, He Y, Zhang JR. Capsule type defines the capability of Klebsiella pneumoniae in evading Kupffer cell capture in the liver. PLoS Pathog 2022; 18:e1010693. [PMID: 35914009 PMCID: PMC9342791 DOI: 10.1371/journal.ppat.1010693] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 06/22/2022] [Indexed: 11/21/2022] Open
Abstract
Polysaccharide capsule is the main virulence factor of K. pneumoniae, a major pathogen of bloodstream infections in humans. While more than 80 capsular serotypes have been identified in K. pneumoniae, only several serotypes are frequently identified in invasive infections. It is documented that the capsule enhances bacterial resistance to phagocytosis, antimicrobial peptides and complement deposition under in vitro conditions. However, the precise role of the capsule in the process of K. pneumoniae bloodstream infections remains to be elucidated. Here we show that the capsule promotes K. pneumoniae survival in the bloodstream by protecting bacteria from being captured by liver resident macrophage Kupffer cells (KCs). Our real-time in vivo imaging revealed that blood-borne acapsular K. pneumoniae mutant is rapidly captured and killed by KCs in the liver sinusoids of mice, whereas, to various extents, encapsulated strains bypass the anti-bacterial machinery in a serotype-dependent manner. Using capsule switched strains, we show that certain high-virulence (HV) capsular serotypes completely block KC’s capture, whereas the low-virulence (LV) counterparts confer partial protection against KC’s capture. Moreover, KC’s capture of the LV K. pneumoniae could be in vivo neutralized by free capsular polysaccharides of homologous but not heterologous serotypes, indicating that KCs specifically recognize the LV capsules. Finally, immunization with inactivated K. pneumoniae enables KCs to capture the HV K. pneumoniae. Together, our findings have uncovered that KCs are the major target cells of K. pneumoniae capsule to promote bacterial survival and virulence, which can be reversed by vaccination. Klebsiella pneumoniae is a major human pathogen. While capsule is the main virulence factor of the pathogen, only several of more than 80 capsule serotypes are frequently identified in invasive infections. However, it remains unclear how capsule contributes to K. pneumoniae virulence. Here we show that capsule type defines K. pneumoniae virulence by differential escape of immune surveillance in the liver. While low-virulence (LV) types are captured by Kupffer cells (KCs), high-virulence (HV) types circumvent the anti-bacterial machinery. Further, inactivated K. pneumoniae vaccine enables KCs to capture the HV K. pneumoniae and protects mice from lethal infection. Our findings explain the clinical prevalence of HV capsule types, and provide promising insights for future vaccine development.
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Affiliation(s)
- Xueting Huang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
| | - Xiuyuan Li
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
| | - Haoran An
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
| | - Juanjuan Wang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
| | - Ming Ding
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
| | - Lijun Wang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China
| | - Lulu Li
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
| | - Quanjiang Ji
- School of Physical Science and Technology, Shanghai Tech University, Shanghai, China
| | - Fen Qu
- The Center of Clinical Diagnosis Laboratory, 302 Hospital of PLA, Beijing, China
- China Aviation General Hospital of China Medical University, Beijing, China
| | - Hui Wang
- Department of Clinical Laboratory, Peking University People’s Hospital, Beijing, China
| | - Yingchun Xu
- Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | - Xinxin Lu
- Department of Clinical Laboratory, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yuan He
- Research Beyond Borders, Boehringer Ingelheim (China), Shanghai, China
| | - Jing-Ren Zhang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
- * E-mail:
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6
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Mabrook M, Abd El-Aziz AM, Youssif M A, Hassan R. Inhibition of CL-11 reduces pulmonary inflammation in a mouse model of Klebsiella pneumoniae lung infection. Microb Pathog 2022; 164:105408. [PMID: 35063609 DOI: 10.1016/j.micpath.2022.105408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/08/2022] [Accepted: 01/13/2022] [Indexed: 11/24/2022]
Abstract
Infection caused by K. pneumoniae is associated with severe inflammation due to stimulation of the innate immune components including the complement system, which is the main player of the innate immune response. Excessive complement-mediated inflammation may cause severe lung injury. Here we clearly show that K. pneumoniae binds to different lectin pathway carbohydrate recognition molecules and activates the complement cascade via the LP. Administration of anti-CL-11 antibodies 6 h before the infection impairs LP functional activity but it shows no effect on the survival time of mice infected with K. pneumoniae. Similarly, no significant difference in bacterial load in blood and lung tissues was observed between mice that received anti-CL-11 and control group treated with an isotype antibody. Interestingly, treatment of mice with anti-CL-11 prior to infection significantly improved histopathological changes and lung injury score induced by K. pneumoniae. Moreover, administration of anti-CL-11 reduced leukocytes infiltration into lung tissues and decreased the levels of the inflammatory mediators TNF-α, IL-6, and IL-1β in the infected mice. These findings indicate that inhibition of the LP could secure a significant level of protection against lung injury during the infection caused by K. pneumoniae.
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Affiliation(s)
- Maha Mabrook
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Abeer M Abd El-Aziz
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
| | - Ali Youssif M
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt; Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom.
| | - Ramadan Hassan
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, 35516, Egypt
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7
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Ali YM, Lynch NJ, Khatri P, Bamigbola IE, Chan ACY, Yabuki M, Demopulos GA, Heeney JL, Pai S, Baxendale H, Schwaeble WJ. Secondary Complement Deficiency Impairs Anti-Microbial Immunity to Klebsiella pneumoniae and Staphylococcus aureus During Severe Acute COVID-19. Front Immunol 2022; 13:841759. [PMID: 35572551 PMCID: PMC9094484 DOI: 10.3389/fimmu.2022.841759] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 03/21/2022] [Indexed: 01/08/2023] Open
Abstract
A high incidence of secondary Klebsiella pneumoniae and Staphylococcus aureus infection were observed in patients with severe COVID-19. The cause of this predisposition to infection is unclear. Our data demonstrate consumption of complement in acute COVID-19 patients reflected by low levels of C3, C4, and loss of haemolytic activity. Given that the elimination of Gram-negative bacteria depends in part on complement-mediated lysis, we hypothesised that secondary hypocomplementaemia is rendering the antibody-dependent classical pathway activation inactive and compromises serum bactericidal activity (SBA). 217 patients with severe COVID-19 were studied. 142 patients suffered secondary bacterial infections. Klebsiella species were the most common Gram-negative organism, found in 58 patients, while S. aureus was the dominant Gram-positive organism found in 22 patients. Hypocomplementaemia was observed in patients with acute severe COVID-19 but not in convalescent survivors three months after discharge. Sera from patients with acute COVID-19 were unable to opsonise either K. pneumoniae or S. aureus and had impaired complement-mediated killing of Klebsiella. We conclude that hyperactivation of complement during acute COVID-19 leads to secondary hypocomplementaemia and predisposes to opportunistic infections.
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Affiliation(s)
- Youssif M. Ali
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
- *Correspondence: Youssif M. Ali, ; Wilhelm J. Schwaeble,
| | - Nicholas J. Lynch
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Priyanka Khatri
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Ifeoluwa E. Bamigbola
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Andrew C. Y. Chan
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | | | | | - Jonathan L. Heeney
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Sumita Pai
- Royal Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom
| | - Helen Baxendale
- Royal Papworth Hospital NHS Foundation Trust, Cambridge, United Kingdom
| | - Wilhelm J. Schwaeble
- Department of Veterinary Medicine, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
- *Correspondence: Youssif M. Ali, ; Wilhelm J. Schwaeble,
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8
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Spiga L, Jimenez AG, Santos RL, Winter SE. How microbiological tests reflect bacterial pathogenesis and host adaptation. Braz J Microbiol 2021; 52:1745-1753. [PMID: 34251610 PMCID: PMC8578236 DOI: 10.1007/s42770-021-00571-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/29/2021] [Indexed: 10/20/2022] Open
Abstract
Historically, clinical microbiological laboratories have often relied on isolation of pure cultures and phenotypic testing to identify microorganisms. These clinical tests are often based on specific biochemical reactions, growth characteristics, colony morphology, and other physiological aspects. The features used for identification in clinical laboratories are highly conserved and specific for a given group of microbes. We speculate that these features might be the result of evolutionary selection and thus may reflect aspects of the life cycle of the organism and pathogenesis. Indeed, several of the metabolic pathways targeted by diagnostic tests in some cases may represent mechanisms for host colonization or pathogenesis. Examples include, but are not restricted to, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella enterica, Shigella spp., and enteroinvasive Escherichia coli (EIEC). Here, we provide an overview of how some common tests reflect molecular mechanisms of bacterial pathogenesis.
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Affiliation(s)
- Luisella Spiga
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Angel G Jimenez
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Renato L Santos
- Departamento de Clínica E Cirurgia Veterinárias, Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - Sebastian E Winter
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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9
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Opoku-Temeng C, Malachowa N, Kobayashi SD, DeLeo FR. Innate Host Defense against Klebsiella pneumoniae and the Outlook for Development of Immunotherapies. J Innate Immun 2021; 14:167-181. [PMID: 34628410 DOI: 10.1159/000518679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/14/2021] [Indexed: 11/19/2022] Open
Abstract
Klebsiella pneumoniae (K. pneumoniae) is a Gram-negative commensal bacterium and opportunistic pathogen. In healthy individuals, the innate immune system is adept at protecting against K. pneumoniae infection. Notably, the serum complement system and phagocytic leukocytes (e.g., neutrophils) are highly effective at eliminating K. pneumoniae and thereby preventing severe disease. On the other hand, the microbe is a major cause of healthcare-associated infections, especially in individuals with underlying susceptibility factors, such as pre-existing severe illness or immune suppression. The burden of K. pneumoniae infections in hospitals is compounded by antibiotic resistance. Treatment of these infections is often difficult largely because the microbes are usually resistant to multiple antibiotics (multidrug resistant [MDR]). There are a limited number of treatment options for these infections and new therapies, and preventative measures are needed. Here, we review host defense against K. pneumoniae and discuss recent therapeutic measures and vaccine approaches directed to treat and prevent severe disease caused by MDR K. pneumoniae.
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Affiliation(s)
- Clement Opoku-Temeng
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Natalia Malachowa
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Scott D Kobayashi
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Frank R DeLeo
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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10
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Ren H, Zhang J, Zhou J, Xu C, Fan Z, Pan X, Li S, Liang Y, Chen S, Xu J, Wang P, Zhang Y, Zhu G, Liu H, Jin Y, Bai F, Cheng Z, Pletzer D, Wu W. Synergistic bactericidal activities of tobramycin with ciprofloxacin and azithromycin against Klebsiella pneumoniae. J Antibiot (Tokyo) 2021; 74:528-537. [PMID: 34050325 DOI: 10.1038/s41429-021-00427-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 11/09/2022]
Abstract
Trans-translation is a unique bacterial ribosome rescue system that plays important roles in the tolerance to environmental stresses. It is composed of an ssrA-encoded tmRNA and a protein SmpB. In this study, we examined the role of trans-translation in antibiotic tolerance in Klebsiella pneumoniae and explored whether the inhibition of this mechanism could enhance the bactericidal activities of antibiotics. We found that deletion of the ssrA gene reduced the survival of K. pneumoniae after treatment with kanamycin, tobramycin, azithromycin, and ciprofloxacin, indicating an important role of the trans-translation in bacterial antibiotic tolerance. By using a modified ssrA gene with a 6×His tag we demonstrated that tobramycin suppressed the azithromycin and ciprofloxacin-elicited activation of trans-translation. The results were further confirmed with a trans-translation reporter system that is composed of a normal mCherry gene and a gfp gene without the stop codon. Compared to each individual antibiotic, combination of tobramycin with azithromycin or ciprofloxacin synergistically enhanced the killing activities against planktonic K. pneumoniae cells and improved bacterial clearance in a murine cutaneous abscess infection model. In addition, the combination of tobramycin and ciprofloxacin increased the bactericidal activities against biofilm-associated cells. Overall, our results suggest that the combination of tobramycin with azithromycin or ciprofloxacin is a promising strategy in combating K. pneumoniae infections.
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Affiliation(s)
- Huan Ren
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Jingyi Zhang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Jingyi Zhou
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Congjuan Xu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Zheng Fan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Shouyi Li
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Yuying Liang
- Department of laboratory medicine, 5th medical center of PLA general hospital, Beijing, 100071, China
| | - Shuiping Chen
- Department of laboratory medicine, 5th medical center of PLA general hospital, Beijing, 100071, China
| | - Jun Xu
- NHC Key Laboratory of Hormones and Development (Tianjin Medical University), Tianjin Key Laboratory of Metabolic Diseases, Diabetic foot Department, Tianjin Medical University Metabolic Disease Hospital & Chu Hsien-I Memorial Hospital, Tianjin, 300070, China
| | - Penghua Wang
- NHC Key Laboratory of Hormones and Development (Tianjin Medical University), Tianjin Key Laboratory of Metabolic Diseases, Diabetic foot Department, Tianjin Medical University Metabolic Disease Hospital & Chu Hsien-I Memorial Hospital, Tianjin, 300070, China
| | - Yanhong Zhang
- Nankai University Affiliated Hospital (Tianjin Forth Hospital), Tianjin, 300222, China
| | - Guangbo Zhu
- Tianjin Union Medical Center, Nankai University Affiliated Hospital, Tianjin, 300121, China
| | - Huimin Liu
- Tianjin Union Medical Center, Nankai University Affiliated Hospital, Tianjin, 300121, China
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Daniel Pletzer
- Department of Microbiology & Immunology, University of Otago, Dunedin, 9054, New Zealand
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China.
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11
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Abstract
Klebsiella pneumoniae are Gram-negative facultative anaerobes that are found within host-associated commensal microbiomes, but they can also cause a wide range of infections that are often difficult to treat. These infections are caused by different pathotypes of K. pneumoniae, called either classical or hypervirulent strains. Klebsiella pneumoniae are Gram-negative facultative anaerobes that are found within host-associated commensal microbiomes, but they can also cause a wide range of infections that are often difficult to treat. These infections are caused by different pathotypes of K. pneumoniae, called either classical or hypervirulent strains. These two groups are genetically distinct, inhabit nonoverlapping geographies, and cause different types of harmful infections in humans. These distinct bacterial groups have also been found to interact differently with the host immune system. Initial innate immune defenses against K. pneumoniae infection include complement, macrophages, neutrophils, and monocytes; these defenses are primary strategies employed by the host to clear infections. K. pneumoniae pathogenesis depends upon the interactions between the microbe and each of these host defenses, and it is becoming increasingly apparent that bacterial genetic diversity impacts the outcomes of these interactions. Here, we highlight recent advances in our understanding of K. pneumoniae pathogenesis, with a focus on how bacterial evolution and diversity impact K. pneumoniae interactions with mammalian innate immune host defenses. We also discuss outstanding questions regarding how K. pneumoniae can frustrate normal immune responses, capitalize upon states of immunocompromise, and cause infections with high mortality.
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Shen X, Yin L, Ma H, Pan X, Zhang D, Zhao R, Dai Y, Hou H, Hu X. Comprehensive genomic analysis and characterization of a new ST 174 type Klebsiella variicola strain isolated from chicken embryos. INFECTION GENETICS AND EVOLUTION 2021; 90:104768. [PMID: 33588064 DOI: 10.1016/j.meegid.2021.104768] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 12/31/2020] [Accepted: 02/10/2021] [Indexed: 10/22/2022]
Abstract
Klebsiella variicola is a widespread opportunistic pathogen that causes infections in humans and animals. Herein a novel Klebsiella strain, AHKv-S01, was isolated and identified from dead chicken embryos in Anhui, China. Its genome contained a circular chromosome of 5,505,304 bp, with 5244 protein-coding genes, and an integrative conjugative element region containing 79 ORF sequences. AHKv-S01 was given a new sequence type number-174. Phylogenetic analyses showed that rpoB partial nucleotide sequences were highly reliable for identifying Klebsiella spp. Most of the 340 unique genes of AHKv-S01 were involved in cell envelop biogenesis, transcription, transport, and metabolic processes. Moreover, AHKv-S01 was sensitive to several antibiotics, but it showed strong resistance to penicillins, macrolides, and lincosamide. The genome contained three drug efflux pump superfamilies, β-lactamase genes, and fosfomycin resistance-related genes. Most drug resistance genes showed amino acid mutations. Multiple virulence and pathogenic factors were also identified, and they were mainly related to adhesion, secretion, iron acquisition, and immune evasion. Chicken embryo lethality assay results revealed that the 7-day chicken embryo lethality rate was 80%, 40%, and 50% for AHKv-S01, K. pneumoniae ATCC10031, and K. pneumoniae CICC24714, respectively. The median lethal dose of AHKv-S01 was 39.9 CFU/embryo. Even low infection levels of AHKv-S01 caused a significant reduction in chicken embryo hatchability. Severe pathological changes to the liver, heart, and brain tissues of embryos infected with AHKv-S01 were observed, and these changes appeared earlier in the heart and brain than in the liver. To conclude, our results provide a foundation for further studies aiming to assess the potential risk of K. variicola to poultry populations and production yields.
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Affiliation(s)
- Xuehuai Shen
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China
| | - Lei Yin
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China
| | - Haitian Ma
- Key Laboratory of Animal Physiology and Biochemistry, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xiaocheng Pan
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China.
| | - Danjun Zhang
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China.
| | - Ruihong Zhao
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China
| | - Yin Dai
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China
| | - Hongyan Hou
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China
| | - Xiaomiao Hu
- Institute of Animal Husbandry and Veterinary Science, Anhui Academy of Agricultural Sciences, Livestock and Poultry Epidemic Diseases Research Center of Anhui Province, Anhui, China; Anhui Province Key Laboratory of Livestock and Poultry Product Safety Engineering, Anhui, China
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Lausen M, Thomsen ME, Christiansen G, Karred N, Stensballe A, Bennike TB, Birkelund S. Analysis of complement deposition and processing on Chlamydia trachomatis. Med Microbiol Immunol 2020; 210:13-32. [PMID: 33206237 DOI: 10.1007/s00430-020-00695-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 10/27/2020] [Indexed: 12/25/2022]
Abstract
Chlamydia trachomatis (C. trachomatis) is the leading cause of sexually transmitted bacterial infections worldwide, with over 120 million annual cases. C. trachomatis infections are associated with severe reproductive complications in women such as extrauterine pregnancy and tubal infertility. The infections are often long lasting, associated with immunopathology, and fail to elicit protective immunity which makes recurrent infections common. The immunological mechanisms involved in C. trachomatis infections are only partially understood. Murine infection models suggest that the complement system plays a significant role in both protective immunity and immunopathology during primary Chlamydia infections. However, only limited structural and mechanistic evidence exists on complement-mediated immunity against C. trachomatis. To expand our current knowledge on this topic, we analyzed global complement deposition on C. trachomatis using comprehensive in-depth mass spectrometry-based proteomics. We show that factor B, properdin, and C4b bind to C. trachomatis demonstrating that C. trachomatis-induced complement activation proceeds through at least two activation pathways. Complement activation leads to cleavage and deposition of C3 and C5 activation products, causing initiation of the terminal complement pathway and deposition of C5b, C6, C7, C8, C9 on C. trachomatis. Interestingly, using immunoelectron microscopy, we show that C5b-9 deposition occurred sporadically and only in rare cases formed complete lytic terminal complexes, possibly caused by the presence of the negative regulators vitronectin and clusterin. Finally, cleavage analysis of C3 demonstrated that deposited C3b is degraded to the opsonins iC3b and C3dg and that this complement opsonization facilitates C. trachomatis binding to human B-cells.
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Affiliation(s)
- Mads Lausen
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark.
| | - Mikkel Eggert Thomsen
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark
| | - Gunna Christiansen
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark.,Department of Biomedicine, Aarhus University, Wilhelms Meyers Allé 4, 8000, Aarhus, Denmark
| | - Nichlas Karred
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark
| | - Allan Stensballe
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark
| | - Tue Bjerg Bennike
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark
| | - Svend Birkelund
- Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 3b, 9220, Aalborg Ø, Denmark
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14
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Genomic Profiling Reveals Distinct Routes To Complement Resistance in Klebsiella pneumoniae. Infect Immun 2020; 88:IAI.00043-20. [PMID: 32513855 PMCID: PMC7375759 DOI: 10.1128/iai.00043-20] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/28/2020] [Indexed: 12/19/2022] Open
Abstract
The serum complement system is a first line of defense against bacterial invaders. Resistance to killing by serum enhances the capacity of Klebsiella pneumoniae to cause infection, but it is an incompletely understood virulence trait. Identifying and characterizing the factors responsible for preventing activation of, and killing by, serum complement could inform new approaches to treatment of K. pneumoniae infections. Here, we used functional genomic profiling to define the genetic basis of complement resistance in four diverse serum-resistant K. pneumoniae strains (NTUH-K2044, B5055, ATCC 43816, and RH201207), and explored their recognition by key complement components. The serum complement system is a first line of defense against bacterial invaders. Resistance to killing by serum enhances the capacity of Klebsiella pneumoniae to cause infection, but it is an incompletely understood virulence trait. Identifying and characterizing the factors responsible for preventing activation of, and killing by, serum complement could inform new approaches to treatment of K. pneumoniae infections. Here, we used functional genomic profiling to define the genetic basis of complement resistance in four diverse serum-resistant K. pneumoniae strains (NTUH-K2044, B5055, ATCC 43816, and RH201207), and explored their recognition by key complement components. More than 90 genes contributed to resistance in one or more strains, but only three, rfaH, lpp, and arnD, were common to all four strains. Deletion of the antiterminator rfaH, which controls the expression of capsule and O side chains, resulted in dramatic complement resistance reductions in all strains. The murein lipoprotein gene lpp promoted capsule retention through a mechanism dependent on its C-terminal lysine residue; its deletion led to modest reductions in complement resistance. Binding experiments with the complement components C3b and C5b-9 showed that the underlying mechanism of evasion varied in the four strains: B5055 and NTUH-K2044 appeared to bypass recognition by complement entirely, while ATCC 43816 and RH201207 were able to resist killing despite being associated with substantial levels of C5b-9. All rfaH and lpp mutants bound C3b and C5b-9 in large quantities. Our findings show that, even among this small selection of isolates, K. pneumoniae adopts differing mechanisms and utilizes distinct gene sets to avoid complement attack.
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15
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Opsonophagocytosis of Chlamydia pneumoniae by Human Monocytes and Neutrophils. Infect Immun 2020; 88:IAI.00087-20. [PMID: 32284372 DOI: 10.1128/iai.00087-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/07/2020] [Indexed: 01/08/2023] Open
Abstract
The human respiratory tract pathogen Chlamydia pneumoniae, which causes mild to severe infections, has been associated with the development of chronic inflammatory diseases. To understand the biology of C. pneumoniae infections, several studies have investigated the interaction between C. pneumoniae and professional phagocytes. However, these studies have been conducted under nonopsonizing conditions, making the role of opsonization in C. pneumoniae infections elusive. Thus, we analyzed complement and antibody opsonization of C. pneumoniae and evaluated how opsonization affects chlamydial infectivity and phagocytosis in human monocytes and neutrophils. We demonstrated that IgG antibodies and activation products of complement C3 and C4 are deposited on the surface of C. pneumoniae elementary bodies when incubated in human serum. Complement activation limits C. pneumoniae infectivity in vitro and has the potential to induce bacterial lysis by the formation of the membrane attack complex. Coculture of C. pneumoniae and freshly isolated human leukocytes showed that complement opsonization is superior to IgG opsonization for efficient opsonophagocytosis of C. pneumoniae in monocytes and neutrophils. Neutrophil-mediated phagocytosis of C. pneumoniae was crucially dependent on opsonization, while monocytes retained minor phagocytic potential under nonopsonizing conditions. Complement opsonization significantly enhanced the intracellular neutralization of C. pneumoniae in peripheral blood mononuclear cells and neutrophils and almost abrogated the infectious potential of C. pneumoniae In conclusion, we demonstrated that complements limit C. pneumoniae infection in vitro by interfering with C. pneumoniae entry into permissive cells by direct complement-induced lysis and by tagging bacteria for efficient phagocytosis in both monocytes and neutrophils.
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