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Bonhomme D, Santecchia I, Escoll P, Papadopoulos S, Vernel-Pauillac F, Boneca IG, Werts C. Leptospiral lipopolysaccharide dampens inflammation through upregulation of autophagy adaptor p62 and NRF2 signaling in macrophages. Microbes Infect 2024; 26:105274. [PMID: 38081475 DOI: 10.1016/j.micinf.2023.105274] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 12/05/2023] [Accepted: 12/06/2023] [Indexed: 12/17/2023]
Abstract
Leptospira interrogans are pathogenic bacteria responsible for leptospirosis, a worldwide zoonosis. All vertebrates can be infected, and some species like humans are susceptible to the disease whereas rodents such as mice are resistant and become asymptomatic renal carriers. Leptospires are stealth bacteria that are known to escape several immune recognition pathways and resist killing mechanisms. We recently published that leptospires may survive intracellularly in and exit macrophages, avoiding xenophagy, a pathogen-targeting form of autophagy. Interestingly, the latter is one of the antimicrobial mechanisms often highjacked by bacteria to evade the host immune response. In this study we explored whether leptospires subvert the key molecular players of autophagy to facilitate infection. We showed in macrophages that leptospires triggered a specific accumulation of autophagy-adaptor p62 in puncta-like structures, without altering autophagic flux. We demonstrated that Leptospira-induced p62 accumulation is a passive mechanism depending on the leptospiral virulence factor LPS signaling via TLR4/TLR2. p62 is a central pleiotropic protein, also mediating cell stress and death, via the translocation of transcription factors. We demonstrated that Leptospira-driven accumulation of p62 induced the translocation of transcription factor NRF2, a key player in the anti-oxidant response. However, NRF2 translocation upon Leptospira infection did not result as expected in antioxydant response, but dampened the production of inflammatory mediators such as iNOS/NO, TNF and IL6. Overall, these findings highlight a novel passive bacterial mechanism linked to LPS and p62/NRF2 signaling that decreases inflammation and contributes to the stealthiness of leptospires.
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Affiliation(s)
- Delphine Bonhomme
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France
| | - Ignacio Santecchia
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France
| | - Pedro Escoll
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Unité Biologie des Bactéries Intracellulaires, Paris, France
| | - Stylianos Papadopoulos
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France
| | - Frédérique Vernel-Pauillac
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France
| | - Ivo G Boneca
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France
| | - Catherine Werts
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France.
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Bonhomme D, Cavaillon JM, Werts C. The dangerous liaisons in innate immunity involving recombinant proteins and endotoxins: Examples from the literature and the Leptospira field. J Biol Chem 2024; 300:105506. [PMID: 38029965 PMCID: PMC10777017 DOI: 10.1016/j.jbc.2023.105506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 11/15/2023] [Accepted: 11/20/2023] [Indexed: 12/01/2023] Open
Abstract
Endotoxins, also known as lipopolysaccharides (LPS), are essential components of cell walls of diderm bacteria such as Escherichia coli. LPS are microbe-associated molecular patterns that can activate pattern recognition receptors. While trying to investigate the interactions between proteins and host innate immunity, some studies using recombinant proteins expressed in E. coli reported interaction and activation of immune cells. Here, we set out to provide information on endotoxins that are highly toxic to humans and bind to numerous molecules, including recombinant proteins. We begin by outlining the history of the discovery of endotoxins, their receptors and the associated signaling pathways that confer extreme sensitivity to immune cells, acting alone or in synergy with other microbe-associated molecular patterns. We list the various places where endotoxins have been found. Additionally, we warn against the risk of data misinterpretation due to endotoxin contamination in recombinant proteins, which is difficult to estimate with the Limulus amebocyte lysate assay, and cannot be completely neutralized (e.g., treatment with polymyxin B or heating). We further illustrate our point with examples of recombinant heat-shock proteins and viral proteins from severe acute respiratory syndrome coronavirus 2, dengue and HIV, for which endotoxin contamination has eventually been shown to be responsible for the inflammatory roles previously ascribed. We also critically appraised studies on recombinant Leptospira proteins regarding their putative inflammatory roles. Finally, to avoid these issues, we propose alternatives to express recombinant proteins in nonmicrobial systems. Microbiologists wishing to undertake innate immunity studies with their favorite pathogens should be aware of these difficulties.
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Affiliation(s)
- Delphine Bonhomme
- Institut Pasteur, Université Cité Paris, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France
| | | | - Catherine Werts
- Institut Pasteur, Université Cité Paris, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la Paroi Bactérienne, Paris, France.
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Varma VP, Bankala R, Kumar A, Gawai S, Faisal SM. Differential modulation of innate immune response by lipopolysaccharide of Leptospira. Open Biol 2023; 13:230101. [PMID: 37935355 PMCID: PMC10645091 DOI: 10.1098/rsob.230101] [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: 05/30/2023] [Accepted: 08/16/2023] [Indexed: 11/09/2023] Open
Abstract
Leptospirosis is a worldwide zoonosis caused by pathogenic Leptospira spp. having more than 300 serovars. These serovars can infect a variety of hosts, some being asymptomatic carriers and others showing varied symptoms of mild to severe infection. Since lipopolysaccharide (LPS) is the major antigen which defines serovar specificity, this different course of infection may be attributed to a differential innate response against this antigen. Previous studies have shown that Leptospira LPS is less endotoxic. However, it is unclear whether there is a difference in the ability of LPS isolated from different serovars to modulate the innate response. In this study, we purified LPS from three widely prevalent pathogenic serovars, i.e. Icterohaemorrhagiae strain RGA, Pomona, Hardjo, and from non-pathogenic L. biflexa serovar semeranga strain Potac 1 collectively termed as L-LPS and tested their ability to modulate innate response in macrophages from both resistant (mice) and susceptible (human and bovine) hosts. L-LPS induced differential response being more proinflammatory in mouse and less proinflammatory in human and bovine macrophages but overall less immunostimulatory than E. coli LPS (E-LPS). Irrespective of serovar, this response was TLR2-dependent in humans, whereas TLR4-dependent/CD14-independent in mouse using MyD88 adapter and signalling through P38 and ERK-dependent MAP kinase pathway. L-LPS-activated macrophages were able to phagocytose Leptospira and this effect was significantly higher or more pronounced when the macrophages were stimulated with L-LPS from the corresponding serovar. L-LPS activated both canonical and non-canonical inflammasome, producing IL-1β without inducing pyroptosis. Further, L-LPS induced both TNF-mediated early and NO-mediated late apoptosis. Altogether, these results indicate that L-LPS induces a differential innate response that is quite distinct from that induced by E-LPS and may be attributed to the structural differences and its atypical nature.
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Affiliation(s)
- Vivek P. Varma
- Laboratory of Vaccine Immunology, National Institute of Animal Biotechnology, Hyderabad 500032, India
- Graduate Studies, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Ramudu Bankala
- Laboratory of Vaccine Immunology, National Institute of Animal Biotechnology, Hyderabad 500032, India
| | - Ajay Kumar
- Laboratory of Vaccine Immunology, National Institute of Animal Biotechnology, Hyderabad 500032, India
- Regional Centre for Biotechnology, Faridabad, India
| | - Shashikant Gawai
- Laboratory of Vaccine Immunology, National Institute of Animal Biotechnology, Hyderabad 500032, India
| | - Syed M. Faisal
- Laboratory of Vaccine Immunology, National Institute of Animal Biotechnology, Hyderabad 500032, India
- Regional Centre for Biotechnology, Faridabad, India
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Krangvichian P, Techawiwattanaboon T, Palaga T, Ritprajak P, Kueanjinda P, Kaewraemruaen C, Patarakul K. Impaired functions of human monocyte-derived dendritic cells and induction of regulatory T cells by pathogenic Leptospira. PLoS Negl Trop Dis 2023; 17:e0011781. [PMID: 37983293 PMCID: PMC10695387 DOI: 10.1371/journal.pntd.0011781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 12/04/2023] [Accepted: 11/08/2023] [Indexed: 11/22/2023] Open
Abstract
Leptospirosis is a global zoonosis caused by pathogenic Leptospira. The disease outcome is influenced by the interplay between innate and adaptive immune responses. Dendritic cells (DCs) play a crucial role in shaping the adaptive immune response. A recent study revealed that pathogenic Leptospira limited the activation of human monocyte-derived dendritic cells (MoDCs) compared to non-pathogenic Leptospira, but their impact on T-cell responses has not been investigated. Our study is the first to explore how viable pathogenic and non-pathogenic Leptospira affect the interaction between human MoDCs and T cells. We found that MoDCs infected with pathogenic leptospires (L. interrogans serovar Pomona and a clinical isolate, MoDCs-P) exhibited lower levels of CD80 and CD83 expression, suggesting partially impaired MoDC maturation, induced regulatory T cells (Tregs) while failing to induce CD4+ T cell proliferation, compared to MoDCs infected with non-pathogenic leptospires (L. biflexa serovar Patoc and L. meyeri serovar Ranarum, MoDCs-NP). In contrast, non-pathogenic leptospires enhanced MoDC maturation and induced higher T cell proliferation including IFN-γ-producing CD4+ T cells, indicative of a Th1-type response. Furthermore, pathogenic leptospires induced higher MoDC apoptosis through a cysteine aspartic acid-specific protease-3 (caspase-3)-dependent pathway and upregulated expression of the prostaglandin-endoperoxide synthase 2 (PTGS2) gene. Notably, prostaglandin E2 (PGE2), a product of the PTGS2 pathway, was found at higher levels in the sera of patients with acute leptospirosis and in the supernatant of MoDCs-P, possibly contributing to Treg induction, compared to those of healthy donors and MoDCs-NP, respectively. In conclusion, this study reveals a novel immunosuppressive strategy employed by pathogenic Leptospira to evade host immunity by partially impairing MoDC maturation and inducing Tregs. These findings deepen our understanding of leptospirosis pathogenesis in humans and may provide a novel strategy to modulate DCs for the prevention and treatment of the disease.
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Affiliation(s)
- Pratomporn Krangvichian
- Medical Microbiology, Interdisciplinary Program, Graduate School, Chulalongkorn University, Bangkok, Thailand
| | - Teerasit Techawiwattanaboon
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
| | - Tanapat Palaga
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
- Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Patcharee Ritprajak
- Research Unit in Integrative Immuno-Microbial Biochemistry and Bioresponsive Nanomaterials, Department of Microbiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Patipark Kueanjinda
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Chamraj Kaewraemruaen
- Department of Science and Bioinnovation, Faculty of Liberal Arts and Science, Kasetsart University, Kamphaeng Saen Campus, Nakhon Pathom, Thailand
| | - Kanitha Patarakul
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
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Greenwood CS, Wynosky-Dolfi MA, Beal AM, Booty LM. Gasdermins assemble; recent developments in bacteriology and pharmacology. Front Immunol 2023; 14:1173519. [PMID: 37266429 PMCID: PMC10230072 DOI: 10.3389/fimmu.2023.1173519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/02/2023] [Indexed: 06/03/2023] Open
Abstract
The discovery of gasdermin D (GSDMD) as the terminal executioner of pyroptosis provided a large piece of the cell death puzzle, whilst simultaneously and firmly putting the gasdermin family into the limelight. In its purest form, GSDMD provides a connection between the innate alarm systems to an explosive, inflammatory form of cell death to jolt the local environment into immunological action. However, the gasdermin field has moved rapidly and significantly since the original seminal work and novel functions and mechanisms have been recently uncovered, particularly in response to infection. Gasdermins regulate and are regulated by mechanisms such as autophagy, metabolism and NETosis in fighting pathogen and protecting host. Importantly, activators and interactors of the other gasdermins, not just GSDMD, have been recently elucidated and have opened new avenues for gasdermin-based discovery. Key to this is the development of potent and specific tool molecules, so far a challenge for the field. Here we will cover some of these recently discovered areas in relation to bacterial infection before providing an overview of the pharmacological landscape and the challenges associated with targeting gasdermins.
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Affiliation(s)
- Claudine S. Greenwood
- Chemical Biology, GSK, Stevenage, United Kingdom
- Pure and Applied Chemistry, University of Strathclyde, Glasgow, United Kingdom
| | | | - Allison M. Beal
- Immunology Research Unit, GSK, Philadelphia, PA, United States
| | - Lee M. Booty
- Immunology Network, GSK, Stevenage, United Kingdom
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