1
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Evans L, Barral P. CD1 molecules: Beyond antigen presentation. Mol Immunol 2024; 170:1-8. [PMID: 38579449 DOI: 10.1016/j.molimm.2024.03.011] [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: 09/28/2022] [Revised: 03/18/2024] [Accepted: 03/29/2024] [Indexed: 04/07/2024]
Abstract
CD1 molecules are well known for their role in binding and presenting lipid antigens to mediate the activation of CD1-restricted T cells. However, much less appreciated is the fact that CD1 molecules can have additional "unconventional" roles which impact the activation and functions of CD1-expressing cells, ultimately controlling tissue homeostasis as well as the progression of inflammatory and infectious diseases. Some of these roles are mediated by so-called reverse signalling, by which crosslinking of CD1 molecules at the cell surface initiates intracellular signalling. On the other hand, CD1 molecules can also control metabolic and inflammatory pathways in CD1-expressing cells through cell-intrinsic mechanisms independent of CD1 ligation. Here, we review the evidence for "unconventional" functions of CD1 molecules and the outcomes of such roles for health and disease.
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Affiliation(s)
- Lauren Evans
- The Peter Gorer Department of Immunobiology. King's College London, London, UK; The Francis Crick Institute, London, UK
| | - Patricia Barral
- The Peter Gorer Department of Immunobiology. King's College London, London, UK; The Francis Crick Institute, London, UK.
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2
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Balasko A, Graydon C, Fowke KR. Novel in vitro invariant natural killer T cell functional assays. J Immunol Methods 2021; 499:113171. [PMID: 34706265 DOI: 10.1016/j.jim.2021.113171] [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: 08/04/2021] [Revised: 09/16/2021] [Accepted: 10/12/2021] [Indexed: 11/25/2022]
Abstract
BACKGROUND Invariant Natural Killer T (iNKT) cells are innate lymphocytes bridging the innate and adaptive immune systems and are critical first responders against cancer and infectious diseases. iNKT cell phenotype and functionality are studied using in vitro stimulation assays assessing cytokine response and proliferation capabilities. The most common stimulant is the glycolipid α-Galactosyl Ceramide (α-GalCer), which stimulates iNKT cells when presented by CD1d, an MHC class I-like molecule expressed by antigen-presenting cells (APC). Another stimulant used is α-GalCer-loaded DimerX, a CD1d-Ig fusion protein which stimulates iNKT cells in an APC-independent fashion. Here, we demonstrate use of the PBS-57-loaded CD1d-tetramer as an APC-independent stimulant, where PBS-57 is an α-GalCer analogue. METHODS Using healthy fresh (n = 4) and frozen (n = 7) peripheral blood mononuclear cells (PBMCs), 10-h cytokine response (measuring IFN-γ production) and 10-day proliferation assays were performed assessing iNKT functionality using α-GalCer, CD1d-tetramer and DimerX stimulants. RESULTS All stimulants effectively induced IFN-γ production in both fresh and frozen PBMC. After the 10-h activation, CD1d-tetramer was significantly more effective than α-GalCer (p = 0.032) in inducing IFN-γ production in fresh PBMC and significantly more effective than both α-GalCer (p = 0.004) and DimerX (p = 0.021) in frozen PBMC. Similarly, all stimulants induced strong proliferation responses in all samples, although this was only significant in the frozen PBMC. No significant differences in proliferation were observed between stimulants. SIGNIFICANCE This study supports PBS-57-loaded CD1d-tetramer as an effective in vitro APC-independent iNKT cell stimulant, which is comparable to or even more effective than α-GalCer and DimerX. As CD1d is downregulated during infectious disease and cancer as evasion strategies, in vitro assays which are APC-independent can assist in providing objective insight to iNKT activation by not relying on CD1d expression by APCs. Overall, the novel CD1d-tetramer stimulation equips researchers with an expanded "toolkit" to successfully assess iNKT cell function.
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Affiliation(s)
- Allison Balasko
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada.
| | - Colin Graydon
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada
| | - Keith R Fowke
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada; Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya; Department of Community Health Sciences, University of Manitoba, Winnipeg, Canada; Partners for Health and Development in Africa, Nairobi, Kenya.
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3
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Tucker AN, Carlson TJ, Sarkar A. Challenges in Drug Discovery for Intracellular Bacteria. Pathogens 2021; 10:pathogens10091172. [PMID: 34578204 PMCID: PMC8468363 DOI: 10.3390/pathogens10091172] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/26/2021] [Accepted: 09/04/2021] [Indexed: 01/04/2023] Open
Abstract
Novel drugs are needed to treat a variety of persistent diseases caused by intracellular bacterial pathogens. Virulence pathways enable many functions required for the survival of these pathogens, including invasion, nutrient acquisition, and immune evasion. Inhibition of virulence pathways is an established route for drug discovery; however, many challenges remain. Here, we propose the biggest problems that must be solved to advance the field meaningfully. While it is established that we do not yet understand the nature of chemicals capable of permeating into the bacterial cell, this problem is compounded when targeting intracellular bacteria because we are limited to only those chemicals that can permeate through both human and bacterial outer envelopes. Unfortunately, many chemicals that permeate through the outer layers of mammalian cells fail to penetrate the bacterial cytoplasm. Another challenge is the lack of publicly available information on virulence factors. It is virtually impossible to know which virulence factors are clinically relevant and have broad cross-species and cross-strain distribution. In other words, we have yet to identify the best drug targets. Yes, standard genomics databases have much of the information necessary for short-term studies, but the connections with patient outcomes are yet to be established. Without comprehensive data on matters such as these, it is difficult to devise broad-spectrum, effective anti-virulence agents. Furthermore, anti-virulence drug discovery is hindered by the current state of technologies available for experimental investigation. Antimicrobial drug discovery was greatly advanced by the establishment and standardization of broth microdilution assays to measure the effectiveness of antimicrobials. However, the currently available models used for anti-virulence drug discovery are too broad, as they must address varied phenotypes, and too expensive to be generally adopted by many research groups. Therefore, we believe drug discovery against intracellular bacterial pathogens can be advanced significantly by overcoming the above hurdles.
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4
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Chen H, Peng B, Yang C, Xie L, Zhong S, Sun Z, Li Z, Wang C, Liu X, Tang X, Zhong G, Lu C. The role of an enzymatically inactive CPAF mutant vaccination in Chlamydia muridarum genital tract infection. Microb Pathog 2021; 160:105137. [PMID: 34390765 DOI: 10.1016/j.micpath.2021.105137] [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: 05/26/2021] [Revised: 08/06/2021] [Accepted: 08/09/2021] [Indexed: 10/20/2022]
Abstract
Chlamydia trachomatis urogenital tract infection causes pelvic inflammatory disease and infertility, increases the risk of co-infection with HPV and HIV. Chlamydial vaccination is considered the most promising approach to prevent and control its infection. Among various chlamydial vaccine candidates, chlamydial protease-like activity factor (CPAF) have been reported to provide robust protective immunity against genital chlamydial infection in mice with reduced vaginal shedding and oviduct pathology. However, CPAF is a serine protease which has enzymatical activity to degrade a large number of substrates. In order to increase the safety of CPAF vaccine, in this study, we used a mutant CPAF that is deficient in enzymatical activity to determine whether proteolytic activity of CPAF affect its vaccine efficacy. The wild type or mutant CPAF immunization causes a significant lower chlamydial shedding from the vaginal and resolve the infection as early as day 20, compared to day 28 in adjuvant control mice. More important, reduced upper reproductive tract pathology were also observed in these two groups. The mutant or wild type CPAF immunization induced not only robust splenic IFN-γ and serum IgG2a but also sIgA secretion in the vaginal fluids. Furthermore, neutralization of chlamydia with immune sera did not provide protection against oviduct pathology. However, adoptive transfer of CD4+ splenocytes isolated from the mutant or wild type CPAF immunized mice resulted in a significant and comparable reduced oviduct pathology. Our results indicate mutant CPAF vaccination is as same efficacy as wild type, and the protection relies on CD4+ T cells, which will further promote the development of CPAF as clinical chlamydial vaccine.
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Affiliation(s)
- Hui Chen
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Bo Peng
- Cancer Research Institute, University of South China, Hengyang, Hunan, China
| | - Chunfen Yang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of University of South China, Hengyang, Hunan, China
| | - Lijuan Xie
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Shufang Zhong
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Zhenjie Sun
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Zhongyu Li
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Chuan Wang
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Xiao Liu
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Xin Tang
- Cancer Research Institute, University of South China, Hengyang, Hunan, China
| | - Guangming Zhong
- Department of Microbiology, Immunology, and Molecular Genetics, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Chunxue Lu
- Institute of Pathogenic Biology and Key Laboratory of Special Pathogen Prevention and Control of Hunan Province, Hengyang Medical College, University of South China, Hengyang, Hunan, China.
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5
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Chlamydia and Its Many Ways of Escaping the Host Immune System. J Pathog 2019; 2019:8604958. [PMID: 31467721 PMCID: PMC6699355 DOI: 10.1155/2019/8604958] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 07/02/2019] [Indexed: 12/18/2022] Open
Abstract
The increasing number of new cases of Chlamydia infection worldwide may be attributed to the pathogen's ability to evade various host immune responses. Summarized here are means of evasion utilized by Chlamydia enabling survival in a hostile host environment. The pathogen's persistence involves a myriad of molecular interactions manifested in a variety of ways, e.g., formation of membranous intracytoplasmic inclusions and cytokine-induced amino acid synthesis, paralysis of phagocytic neutrophils, evasion of phagocytosis, inhibition of host cell apoptosis, suppression of antigen presentation, and induced expression of a check point inhibitor of programmed host cell death. Future studies could focus on the targeting of these molecules associated with immune evasion, thus limiting the spread and tissue damage caused by this pathogen.
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6
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Sanchez LR, Godoy GJ, Gorosito Serrán M, Breser ML, Fiocca Vernengo F, Engel P, Motrich RD, Gruppi A, Rivero VE. IL-10 Producing B Cells Dampen Protective T Cell Response and Allow Chlamydia muridarum Infection of the Male Genital Tract. Front Immunol 2019; 10:356. [PMID: 30881362 PMCID: PMC6405527 DOI: 10.3389/fimmu.2019.00356] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 02/12/2019] [Indexed: 12/26/2022] Open
Abstract
A significant proportion of individuals develop chronic, persistent and recurrent genital tract infections with Chlamydia trachomatis, which has been attributed to the numerous strategies that the bacterium uses to subvert host immune responses. Animal chlamydia models have demonstrated that protective immune response is mediated by CD4+ Th1 cytokine responses. Herein, we demonstrate that early after infecting the male genital tract, C. muridarum triggers the production of IL-10 by splenic and lymph node cells. In addition, C. muridarum triggers IL-6 and TNFα secretion. Data obtained from in vitro and in vivo experiments revealed B cells as the major IL-10 contributors. Indeed, purified B cells produced high amounts of IL-10 and also exhibited enhanced expression of inhibitory molecules such as CD39, PD-L1 and PD1 after C. muridarum stimulation. In vitro experiments performed with sorted cell subsets revealed that Marginal Zone B cells were the main IL-10 producers. In vitro and in vivo studies using TLR-deficient mice indicated that TLR4 signaling pathway was essential for IL-10 production. In addition, in vivo treatments to neutralize IL-10 or deplete B cells indicated that IL-10 and B cells played a significant role in delaying bacterial clearance ability. Moreover, the latter was confirmed by adoptive cell transfer experiments in which the absence of IL-10-producing B cells conferred the host a greater capability to induce Th1 responses and clear the infection. Interestingly, NOD mice, which were the least efficient in clearing the infection, presented much more Marginal Zone B counts and also enhanced TLR4 expression on Marginal Zone B cells when compared to B6 and BALB/c mice. Besides, treatment with antibodies that selectively deplete Marginal Zone B cells rendered mice more capable of inducing enhanced IFNγ responses and clearing the infection. Our findings suggest that B cells play a detrimental role in C. muridarum infection and that activation by innate receptors like TLR4 and IL-10 production by these cells could be used by Chlamydia spp. as a strategy to modulate the immune response establishing chronic infections in susceptible hosts.
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Affiliation(s)
- Leonardo R Sanchez
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Gloria J Godoy
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Melisa Gorosito Serrán
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maria L Breser
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Facundo Fiocca Vernengo
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Pablo Engel
- Immunology Unit, Department of Biomedical Sciences, Immunology and Neurosciences, Medical School, University of Barcelona, Barcelona, Spain
| | - Ruben D Motrich
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Adriana Gruppi
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Virginia E Rivero
- Centro de Investigaciones en Bioquímica Clínica e Inmunología, CIBICI-CONICET, Córdoba, Argentina.,Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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7
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Hapil FZ, Wingender G. The interaction between invariant Natural Killer T cells and the mucosal microbiota. Immunology 2018; 155:164-175. [PMID: 29893412 DOI: 10.1111/imm.12958] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 05/21/2018] [Indexed: 02/06/2023] Open
Abstract
The surface of mammalian bodies is colonized by a multitude of microbial organisms, which under normal conditions support the host and are considered beneficial commensals. This requires, however, that the composition of the commensal microbiota is tightly controlled and regulated. The host immune system plays an important role in the maintenance of this microbiota composition. Here we focus on the contribution of one particular immune cell type, invariant Natural Killer T (iNKT) cells, in this process. The iNKT cells are a unique subset of T cells characterized by two main features. First, they express an invariant T-cell receptor that recognizes glycolipid antigens presented by CD1d, a non-polymorphic major histocompatibility complex class I-like molecule. Second, iNKT cells develop as effector/memory cells and swiftly exert effector functions, like cytokine production and cytotoxicity, after activation. We outline the influence that the mucosal microbiota can have on iNKT cells, and how iNKT cells contribute to the maintenance of the microbiota composition.
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Affiliation(s)
| | - Gerhard Wingender
- Izmir Biomedicine and Genome Center, Balcova/Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, Balcova/Izmir, Turkey
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8
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Ibana JA, Sherchand SP, Fontanilla FL, Nagamatsu T, Schust DJ, Quayle AJ, Aiyar A. Chlamydia trachomatis-infected cells and uninfected-bystander cells exhibit diametrically opposed responses to interferon gamma. Sci Rep 2018; 8:8476. [PMID: 29855501 PMCID: PMC5981614 DOI: 10.1038/s41598-018-26765-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/18/2018] [Indexed: 12/13/2022] Open
Abstract
The intracellular bacterial pathogen, Chlamydia trachomatis, is a tryptophan auxotroph. Therefore, induction of the host tryptophan catabolizing enzyme, indoleamine-2,3-dioxgenase-1 (IDO1), by interferon gamma (IFNγ) is one of the primary protective responses against chlamydial infection. However, despite the presence of a robust IFNγ response, active and replicating C. trachomatis can be detected in cervical secretions of women. We hypothesized that a primary C. trachomatis infection may evade the IFNγ response, and that the protective effect of this cytokine results from its activation of tryptophan catabolism in bystander cells. To test this hypothesis, we developed a novel method to separate a pool of cells exposed to C. trachomatis into pure populations of live infected and bystander cells and applied this technique to distinguish between the effects of IFNγ on infected and bystander cells. Our findings revealed that the protective induction of IDO1 is suppressed specifically within primary infected cells because Chlamydia attenuates the nuclear import of activated STAT1 following IFNγ exposure, without affecting STAT1 levels or phosphorylation. Critically, the IFNγ-mediated induction of IDO1 activity is unhindered in bystander cells. Therefore, the IDO1-mediated tryptophan catabolism is functional in these cells, transforming these bystander cells into inhospitable hosts for a secondary C. trachomatis infection.
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Affiliation(s)
- Joyce A Ibana
- Immunopharmacology Research Laboratory, Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines.
| | - Shardulendra P Sherchand
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
| | - Francis L Fontanilla
- Immunopharmacology Research Laboratory, Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City, 1101, Philippines
| | - Takeshi Nagamatsu
- Department of Obstetrics and Gynecology, Faculty Medicine, University of Tokyo, Tokyo, Japan
| | - Danny J Schust
- Department of Obstetrics, Gynecology, and Women's Health, University of Missouri, Columbia, MO, 15276, USA
| | - Alison J Quayle
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
| | - Ashok Aiyar
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
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9
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Brutkiewicz RR, Yunes-Medina L, Liu J. Immune evasion of the CD1d/NKT cell axis. Curr Opin Immunol 2018; 52:87-92. [PMID: 29734045 DOI: 10.1016/j.coi.2018.04.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/19/2018] [Indexed: 01/03/2023]
Abstract
Many reviews on the CD1d/NKT cell axis focus on the ability of CD1d-restricted NKT cells to serve as effector cells in a variety of disorders, be they infectious diseases, cancer or autoimmunity. In contrast, here, we discuss the ways that viruses, bacteria and tumor cells can evade the CD1d/NKT cell axis. As a result, these disease states have a better chance to establish a foothold and potentially cause problems for the subsequent adaptive immune response, as the host tries to rid itself of infections or tumors.
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Affiliation(s)
- Randy R Brutkiewicz
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202-5181, United States.
| | - Laura Yunes-Medina
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202-5181, United States
| | - Jianyun Liu
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202-5181, United States
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10
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Dixit S, Sahu R, Verma R, Duncan S, Giambartolomei GH, Singh SR, Dennis VA. Caveolin-mediated endocytosis of the Chlamydia M278 outer membrane peptide encapsulated in poly(lactic acid)-Poly(ethylene glycol) nanoparticles by mouse primary dendritic cells enhances specific immune effectors mediated by MHC class II and CD4 + T cells. Biomaterials 2018; 159:130-145. [PMID: 29324305 PMCID: PMC5801148 DOI: 10.1016/j.biomaterials.2017.12.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 12/14/2017] [Accepted: 12/22/2017] [Indexed: 12/18/2022]
Abstract
We previously developed a Chlamydia trachomatis nanovaccine (PPM) by encapsulating a chlamydial M278 peptide within poly(lactic acid)-poly(ethylene glycol) biodegradable nanoparticles that immunopotentiated Chlamydia-specific immune effector responses in mice. Herein, we investigated the mechanistic interactions of PPM with mouse bone marrow-derived dendritic cells (DCs) for its uptake, trafficking, and T cell activation. Our results reveal that PPM triggered enhanced expression of effector cytokines and chemokines, surface activation markers (Cd1d2, Fcgr1), pathogen-sensing receptors (TLR2, Nod1), co-stimulatory (CD40, CD80, CD86) and MHC class I and II molecules. Co-culturing of PPM-primed DCs with T cells from C. muridarum vaccinated mice yielded an increase in Chlamydia-specific immune effector responses including CD3+ lymphoproliferation, CD3+CD4+ IFN-γ-secreting cells along with CD3+CD4+ memory (CD44high and CD62Lhigh) and effector (CD44high and CD62Llow) phenotypes. Intracellular trafficking analyses revealed an intense expression and colocalization of PPM predominantly in endosomes. PPM also upregulated the transcriptional and protein expression of the endocytic mediator, caveolin-1 in DCs. More importantly, the specific inhibition of caveolin-1 led to decreased expression of PPM-induced cytokines and co-stimulatory molecules. Our investigation shows that PPM provided enhancement of uptake, probably by exploiting the caveolin-mediated endocytosis pathway, endosomal processing, and MHC II presentation to immunopotentiate Chlamydia-specific immune effector responses mediated by CD4+ T cells.
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Affiliation(s)
- Saurabh Dixit
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL 36104, USA
| | - Rajnish Sahu
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL 36104, USA
| | - Richa Verma
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL 36104, USA
| | - Skyla Duncan
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL 36104, USA
| | - Guillermo H Giambartolomei
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Shree R Singh
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL 36104, USA
| | - Vida A Dennis
- Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL 36104, USA.
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11
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Abstract
Etiology, transmission and protection: Chlamydia
trachomatis is the leading cause of bacterial sexually transmitted
infection (STI) globally. However, C. trachomatis also causes
trachoma in endemic areas, mostly Africa and the Middle East, and is a leading
cause of preventable blindness worldwide. Epidemiology, incidence and
prevalence: The World Health Organization estimates 131 million
new cases of C. trachomatis genital infection occur annually.
Globally, infection is most prevalent in young women and men (14-25 years),
likely driven by asymptomatic infection, inadequate partner treatment and
delayed development of protective immunity.
Pathology/Symptomatology: C.
trachomatis infects susceptible squamocolumnar or transitional
epithelial cells, leading to cervicitis in women and urethritis in men. Symptoms
are often mild or absent but ascending infection in some women may lead to
Pelvic Inflammatory Disease (PID), resulting in reproductive sequelae such as
ectopic pregnancy, infertility and chronic pelvic pain. Complications of
infection in men include epididymitis and reactive arthritis.
Molecular mechanisms of infection: Chlamydiae
manipulate an array of host processes to support their obligate intracellular
developmental cycle. This leads to activation of signaling pathways resulting in
disproportionate influx of innate cells and the release of tissue damaging
proteins and pro-inflammatory cytokines. Treatment and
curability: Uncomplicated urogenital infection is treated with
azithromycin (1 g, single dose) or doxycycline (100 mg twice daily x 7 days).
However, antimicrobial treatment does not ameliorate established disease. Drug
resistance is rare but treatment failures have been described. Development of an
effective vaccine that protects against upper tract disease or that limits
transmission remains an important goal.
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Affiliation(s)
- Catherine M O'Connell
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Morgan E Ferone
- Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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12
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Invariant natural killer T cells: front line fighters in the war against pathogenic microbes. Immunogenetics 2016; 68:639-48. [PMID: 27368411 DOI: 10.1007/s00251-016-0933-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/21/2016] [Indexed: 12/22/2022]
Abstract
Invariant natural killer T (iNKT) cells constitute a unique subset of innate-like T cells that have been shown to have crucial roles in a variety of immune responses. iNKT cells are characterized by their expression of both NK cell markers and an invariant T cell receptor (TCR) α chain, which recognizes glycolipids presented by the MHC class I-like molecule CD1d. Despite having a limited antigen repertoire, the iNKT cell response can be very complex, and participate in both protective and harmful immune responses. The protective role of these cells against a variety of pathogens has been particularly well documented. Through the use of these pathogen models, our knowledge of the breadth of the iNKT cell response has been expanded. Specific iNKT cell antigens have been isolated from several different bacteria, from which iNKT cells are critical for protection in mouse models. These responses can be generated by direct, CD1d-mediated activation, or indirect, cytokine-mediated activation, or a combination of the two. This can lead to secretion of a variety of different Th1, Th2, or Th17 cytokines, which differentially impact the downstream immune response against these pathogens. This critical role is emphasized by the conservation of these cells between mice and humans, warranting further investigation into how iNKT cells participate in protective immune responses, with the ultimate goal of harnessing their potential for treatment.
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13
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Bavoil PM, Byrne GI. Analysis of CPAF mutants: new functions, new questions (the ins and outs of a chlamydial protease). Pathog Dis 2015; 71:287-91. [PMID: 24942261 DOI: 10.1111/2049-632x.12194] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/06/2014] [Indexed: 12/18/2022] Open
Abstract
The role of the chlamydial protease CPAF, previously described as a secreted serine protease processing a wealth of host and chlamydial proteins to promote chlamydial intracellular growth, has recently been questioned by studies from the groups of Tan and Sütterlin, who demonstrated that the reported proteolysis of almost a dozen substrates by CPAF occurred during preparation of cell lysates rather than in intact cells. Valdivia et al. have now compared near-isogenic pairs of CPAF-deficient and secretion-deficient mutants of Chlamydia trachomatis and their wild-type parent. Their report, published in this issue of Pathogens and Disease, is a landmark study in the emerging era of Chlamydia genetics. The results of Tan and Sütterlin are confirmed with a few additions. While CPAF's role in pathogenesis is diminished considerably from these studies, CPAF remains an important factor in chlamydial biology as (1) CPAF mutants produce less infectious yield than wild type; and (2) CPAF is responsible for proteolytic cleavage of vimentin and LAP-1, but only after lysis of the inclusion membrane, not upon CPAF secretion to the cytosol. Here, we briefly review the evidence in support of CPAF's active secretion from the mid-to-late inclusion and conclude that new experimentation to establish whether or not CPAF is actively secreted should precede any new investigation of CPAF's cellular activities during mid-to-late development.
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Affiliation(s)
- Patrik M Bavoil
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD, USA
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14
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Snavely EA, Kokes M, Dunn JD, Saka HA, Nguyen BD, Bastidas RJ, McCafferty DG, Valdivia RH. Reassessing the role of the secreted protease CPAF in Chlamydia trachomatis infection through genetic approaches. Pathog Dis 2014; 71:336-51. [PMID: 24838663 DOI: 10.1111/2049-632x.12179] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/10/2014] [Accepted: 04/10/2014] [Indexed: 12/30/2022] Open
Abstract
The secreted Chlamydia protease CPAF cleaves a defined set of mammalian and Chlamydia proteins in vitro. As a result, this protease has been proposed to modulate a range of bacterial and host cellular functions. However, it has recently come into question the extent to which many of its identified substrates constitute bona fide targets of proteolysis in infected host cell rather than artifacts of postlysis degradation. Here, we clarify the role played by CPAF in cellular models of infection by analyzing Chlamydia trachomatis mutants deficient for CPAF activity. Using reverse genetic approaches, we identified two C. trachomatis strains possessing nonsense, loss-of-function mutations in cpa (CT858) and a third strain containing a mutation in type II secretion (T2S) machinery that inhibited CPAF activity by blocking zymogen secretion and subsequent proteolytic maturation into the active hydrolase. HeLa cells infected with T2S(-) or CPAF(-) C. trachomatis mutants lacked detectable in vitro CPAF proteolytic activity and were not defective for cellular traits that have been previously attributed to CPAF activity, including resistance to staurosporine-induced apoptosis, Golgi fragmentation, altered NFκB-dependent gene expression, and resistance to reinfection. However, CPAF-deficient mutants did display impaired generation of infectious elementary bodies (EBs), indicating an important role for this protease in the full replicative potential of C. trachomatis. In addition, we provide compelling evidence in live cells that CPAF-mediated protein processing of at least two host protein targets, vimentin filaments and the nuclear envelope protein lamin-associated protein-1 (LAP1), occurs rapidly after the loss of the inclusion membrane integrity, but before loss of plasma membrane permeability and cell lysis. CPAF-dependent processing of host proteins correlates with a loss of inclusion membrane integrity, and so we propose that CPAF plays a role late in infection, possibly during the stages leading to the dismantling of the infected cell prior to the release of EBs during cell lysis.
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Affiliation(s)
- Emily A Snavely
- Department of Molecular Genetics and Microbiology, Center for Microbial Pathogenesis, Duke University Medical Center, Durham, NC, USA
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15
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Dowds CM, Kornell SC, Blumberg RS, Zeissig S. Lipid antigens in immunity. Biol Chem 2014; 395:61-81. [PMID: 23999493 PMCID: PMC4128234 DOI: 10.1515/hsz-2013-0220] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 08/27/2013] [Indexed: 02/07/2023]
Abstract
Lipids are not only a central part of human metabolism but also play diverse and critical roles in the immune system. As such, they can act as ligands of lipid-activated nuclear receptors, control inflammatory signaling through bioactive lipids such as prostaglandins, leukotrienes, lipoxins, resolvins, and protectins, and modulate immunity as intracellular phospholipid- or sphingolipid-derived signaling mediators. In addition, lipids can serve as antigens and regulate immunity through the activation of lipid-reactive T cells, which is the topic of this review. We will provide an overview of the mechanisms of lipid antigen presentation, the biology of lipid-reactive T cells, and their contribution to immunity.
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Affiliation(s)
- C. Marie Dowds
- Department of Internal Medicine I, University Medical Center
Schleswig-Holstein, Schittenhelmstraße 12, D-24105 Kiel,
Germany
| | - Sabin-Christin Kornell
- Department of Internal Medicine I, University Medical Center
Schleswig-Holstein, Schittenhelmstraße 12, D-24105 Kiel,
Germany
| | - Richard S. Blumberg
- Division of Gastroenterology, Hepatology, and Endoscopy, Brigham
and Women’s Hospital, Harvard Medical School, 75 Francis Street,
Boston, MA 02115, USA
| | - Sebastian Zeissig
- Department of Internal Medicine I, University Medical Center
Schleswig-Holstein, Schittenhelmstraße 12, D-24105 Kiel,
Germany
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16
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Han J, Rho SB, Lee JY, Bae J, Park SH, Lee SJ, Lee SY, Ahn C, Kim JY, Chun T. Human cytomegalovirus (HCMV) US2 protein interacts with human CD1d (hCD1d) and down-regulates invariant NKT (iNKT) cell activity. Mol Cells 2013; 36:455-64. [PMID: 24213674 PMCID: PMC3887943 DOI: 10.1007/s10059-013-0221-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/06/2013] [Accepted: 09/09/2013] [Indexed: 02/06/2023] Open
Abstract
To avoid host immune surveillance, human cytomegalovirus (HCMV) encoded endoplasmic reticulum (ER)-membrane glycoprotein US2, which interferes with antigen presenting mechanism of Major histocompatibility complex (MHC) class Ia and class II molecules. However, not many attempts have been made to study the effect of HCMV US2 on the expression of MHC class Ib molecules. In this study, we examined the effect of HCMV US2 on the expression and function of human CD1d (hCD1d), which presents glycolipid antigens to invariant NKT (iNKT) cells. Our results clearly showed that the physiological interaction between ER lumenal domain of HCMV US2 and α3 domain of hCD1d was observed within ER. Compared with mature form of hCD1d, immature form of hCD1d is more susceptible to ubiquitin-dependent proteasomal degradation mediated by HCMV US2. Moreover, the ectopic expression of HCMV US2 leads to the down-modulation of iNKT cell activity without significant change of hCD1d expression. These results will advance our understanding of the function of HCMV US2 in immune evasive mechanisms against anti-viral immunity of iNKT cells.
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Affiliation(s)
- Jihye Han
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | | | - Jae Yeon Lee
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Joonbeom Bae
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | - Se Ho Park
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
| | | | | | | | | | - Taehoon Chun
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Korea
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17
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Kinjo Y, Kitano N, Kronenberg M. The role of invariant natural killer T cells in microbial immunity. J Infect Chemother 2013; 19:560-70. [PMID: 23846426 PMCID: PMC3822041 DOI: 10.1007/s10156-013-0638-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Indexed: 10/26/2022]
Abstract
Invariant natural killer T cells (iNKT cells) are unique lymphocytes with characteristic features, such as expression of an invariant T-cell antigen receptor (TCR) α-chain, recognition of glycolipid antigens presented by CD1d molecules, and ability to rapidly produce large amounts of cytokines, including interferon-γ (IFN-γ) and interleukin 4 (IL-4) upon TCR stimulation. Many studies have demonstrated that iNKT cells participate in immune response against diverse microbes, including bacteria, fungi, protozoan parasites, and viruses. Generally, these cells play protective roles in host defense against infections. However, in some contexts they play pathogenic roles, by inducing or augmenting inflammation. Recent reports show that iNKT cells recognize glycolipid antigens from pathogenic bacteria including Streptococcus pneumoniae, and they contribute to host defense against infection. iNKT cell responses to these microbial glycolipid antigens are highly conserved between rodents and humans, suggesting that iNKT cells are evolutionally conserved because their invariant TCR is useful in detecting certain pathogens. Furthermore, glycolipid-mediated iNKT cell activation during immunization has adjuvant activity, enhancing humoral and cell-mediated responses. Therefore, iNKT cell activation is an attractive target for developing new vaccines for infectious diseases.
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Affiliation(s)
- Yuki Kinjo
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo, 162-8640, Japan.
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18
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Chlamydia trachomatis infection results in a modest pro-inflammatory cytokine response and a decrease in T cell chemokine secretion in human polarized endocervical epithelial cells. Cytokine 2013; 63:151-65. [PMID: 23673287 DOI: 10.1016/j.cyto.2013.04.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 01/19/2023]
Abstract
The endocervical epithelium is a major reservoir for Chlamydia trachomatis in women, and genital infections are extended in their duration. Epithelial cells act as mucosal sentinels by secreting cytokines and chemokines in response to pathogen challenge and infection. We therefore determined the signature cytokine and chemokine response of primary-like endocervix-derived epithelial cells in response to a common genital serovar (D) of C. trachomatis. For these studies, we used a recently-established polarized, immortalized, endocervical epithelial cell model (polA2EN) that maintains, in vitro, the architectural and functional characteristics of endocervical epithelial cells in vivo including the production of pro-inflammatory cytokines. PolA2EN cells were susceptible to C. trachomatis infection, and chlamydiae in these cells underwent a normal developmental cycle as determined by a one-step growth curve. IL1α protein levels were increased in both apical and basolateral secretions of C. trachomatis infected polA2EN cells, but this response did not occur until 72h after infection. Furthermore, protein levels of the pro-inflammatory cytokines and chemokines IL6, TNFα and CXCL8 were not significantly different between C. trachomatis infected polA2EN cells and mock infected cells at any time during the chlamydial developmental cycle up to 120h post-infection. Intriguingly, C. trachomatis infection resulted in a significant decrease in the constitutive secretion of T cell chemokines IP10 and RANTES, and this required a productive C. trachomatis infection. Examination of anti-inflammatory cytokines revealed a high constitutive apical secretion of IL1ra from polA2EN cells that was not significantly modulated by C. trachomatis infection. IL-11 was induced by C. trachomatis, although only from the basolateral membrane. These results suggest that C. trachomatis can use evasion strategies to circumvent a robust pro-inflammatory cytokine and chemokine response. These evasion strategies, together with the inherent immune repertoire of endocervical epithelial cells, may aid chlamydiae in establishing, and possibly sustaining, an intracellular niche in microenvironments of the endocervix in vivo.
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19
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Bastidas RJ, Elwell CA, Engel JN, Valdivia RH. Chlamydial intracellular survival strategies. Cold Spring Harb Perspect Med 2013; 3:a010256. [PMID: 23637308 DOI: 10.1101/cshperspect.a010256] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen and the causative agent of blinding trachoma. Although Chlamydia is protected from humoral immune responses by residing within remodeled intracellular vacuoles, it still must contend with multilayered intracellular innate immune defenses deployed by its host while scavenging for nutrients. Here we provide an overview of Chlamydia biology and highlight recent findings detailing how this vacuole-bound pathogen manipulates host-cellular functions to invade host cells and maintain a replicative niche.
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Affiliation(s)
- Robert J Bastidas
- Department of Molecular Genetics and Microbiology, Center for Microbial Pathogenesis, Duke University Medical Center, Durham, NC 27710, USA
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20
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Jiang J, Karimi O, Ouburg S, Champion CI, Khurana A, Liu G, Freed A, Pleijster J, Rozengurt N, Land JA, Surcel HM, Tiitinen A, Paavonen J, Kronenberg M, Morré SA, Kelly KA. Interruption of CXCL13-CXCR5 axis increases upper genital tract pathology and activation of NKT cells following chlamydial genital infection. PLoS One 2012; 7:e47487. [PMID: 23189125 PMCID: PMC3506621 DOI: 10.1371/journal.pone.0047487] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 09/12/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Regulation of immune responses is critical for controlling inflammation and disruption of this process can lead to tissue damage. We reported that CXCL13 was induced in fallopian tube tissue following C. trachomatis infection. Here, we examined the influence of the CXCL13-CXCR5 axis in chlamydial genital infection. METHODOLOGY AND PRINCIPAL FINDINGS Disruption of the CXCL13-CXCR5 axis by injecting anti-CXCL13 Ab to BALB/c mice or using Cxcr5-/- mice increased chronic inflammation in the upper genital tract (UGT; uterine horns and oviducts) after Chlamydia muridarum genital infection (GT). Further studies in Cxcr5-/- mice showed an elevation in bacterial burden in the GT and increased numbers of neutrophils, activated DCs and activated NKT cells early after infection. After resolution, we noted increased fibrosis and the accumulation of a variety of T cells subsets (CD4-IFNγ, CD4-IL-17, CD4-IL-10 & CD8-TNFα) in the oviducts. NKT cell depletion in vitro reduced IL-17α and various cytokines and chemokines, suggesting that activated NKT cells modulate neutrophils and DCs through cytokine/chemokine secretion. Further, chlamydial glycolipids directly activated two distinct types of NKT cell hybridomas in a cell-free CD1d presentation assay and genital infection of Cd1d-/- mice showed reduced oviduct inflammation compared to WT mice. CXCR5 involvement in pathology was also noted using single-nucleotide polymorphism analysis in C. trachomatis infected women attending a sub-fertility clinic. Women who developed tubal pathology after a C. trachomatis infection had a decrease in the frequency of CXCR5 SNP +10950 T>C (rs3922). CONCLUSIONS/SIGNIFICANCE These experiments indicate that disruption of the CXCL13-CXCR5 axis permits increased activation of NKT cells by type I and type II glycolipids of Chlamydia muridarum and results in UGT pathology potentially through increased numbers of neutrophils and T cell subsets associated with UGT pathology. In addition, CXCR5 appears to contribute to inter-individual differences in human tubal pathology following C. trachomatis infection.
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Affiliation(s)
- Janina Jiang
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Ouafae Karimi
- Laboratory of Immunogenetics, Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands
| | - Sander Ouburg
- Laboratory of Immunogenetics, Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands
| | - Cheryl I. Champion
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Archana Khurana
- La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Guangchao Liu
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Amanda Freed
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jolein Pleijster
- Department of Obstetrics and Gynaecology, University Medical Center Groningen, Groningen, The Netherlands
| | - Nora Rozengurt
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- CURE DDRC Morphology and Images Core, University of California Los Angeles, Los Angeles, California, United States of America
| | - Jolande A. Land
- Department of Obstetrics and Gynaecology, University Medical Center Groningen, Groningen, The Netherlands
| | - Helja-Marja Surcel
- National Institute for Health and Welfare, Kastelli Research Centre, Oulu, Finland
| | - Aila' Tiitinen
- Department of Obstetrics and Gynecology, University Hospital, University of Helsinki, Helsinki, Finland
| | - Jorma Paavonen
- Department of Obstetrics and Gynecology, University Hospital, University of Helsinki, Helsinki, Finland
| | - Mitchell Kronenberg
- La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Servaas A. Morré
- Laboratory of Immunogenetics, Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands
- Institute of Public Health Genomics, Department of Genetics and Cell Biology, Research Institutes, School of Public Health and Primary Care (CAPHRI) and Growth and Development (GROW), Faculty of Health, Medicine & Life Sciences, University of Maastricht, Maastricht, The Netherlands
| | - Kathleen A. Kelly
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- California NanoSystems, University of California Los Angeles, Los Angeles, California, United States of America
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21
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Chen AL, Johnson KA, Lee JK, Sütterlin C, Tan M. CPAF: a Chlamydial protease in search of an authentic substrate. PLoS Pathog 2012; 8:e1002842. [PMID: 22876181 PMCID: PMC3410858 DOI: 10.1371/journal.ppat.1002842] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 06/22/2012] [Indexed: 01/13/2023] Open
Abstract
Bacteria in the genus Chlamydia are major human pathogens that cause an intracellular infection. A chlamydial protease, CPAF, has been proposed as an important virulence factor that cleaves or degrades at least 16 host proteins, thereby altering multiple cellular processes. We examined 11 published CPAF substrates and found that there was no detectable proteolysis when CPAF activity was inhibited during cell processing. We show that the reported proteolysis of these putative CPAF substrates was due to enzymatic activity in cell lysates rather than in intact cells. Nevertheless, Chlamydia-infected cells displayed Chlamydia-host interactions, such as Golgi reorganization, apoptosis resistance, and host cytoskeletal remodeling, that have been attributed to CPAF-dependent proteolysis of host proteins. Our findings suggest that other mechanisms may be responsible for these Chlamydia-host interactions, and raise concerns about all published CPAF substrates and the proposed roles of CPAF in chlamydial pathogenesis. Chlamydia are bacteria that invade eukaryotic host cells and live within a membrane-bound compartment called the chlamydial inclusion. Growth and survival of these important human and animal pathogens depends on extensive interactions with the host cell, which allow chlamydiae to acquire critical nutrients and to avoid host anti-microbial defenses. Chlamydiae are proposed to cause many of these host-pathogen interactions through the cleavage or degradation of host proteins by the chlamydial protease CPAF, which is secreted into the host cytoplasm. Here, we raise questions about the proposed roles of this virulence factor during infection, as well as its published substrates. We found that there was no detectable cleavage or degradation of 11 previously reported CPAF substrates in Chlamydia-infected cells and that CPAF-mediated proteolysis of these host proteins occurs during cell harvest and lysis. However, we still observed host-pathogen interactions previously attributed to CPAF proteolysis of these proteins, suggesting that Chlamydia is likely to cause these effects on the host cell through other mechanisms. Our findings call for a re-evaluation of all published CPAF substrates as well as the proposed roles of this protease in chlamydial pathogenesis.
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Affiliation(s)
- Allan L. Chen
- Department of Microbiology and Molecular Genetics, University of California at Irvine, Irvine, California, United States of America
| | - Kirsten A. Johnson
- Department of Microbiology and Molecular Genetics, University of California at Irvine, Irvine, California, United States of America
- Department of Developmental and Cell Biology, University of California at Irvine, Irvine, California, United States of America
| | - Jennifer K. Lee
- Department of Microbiology and Molecular Genetics, University of California at Irvine, Irvine, California, United States of America
- Department of Developmental and Cell Biology, University of California at Irvine, Irvine, California, United States of America
| | - Christine Sütterlin
- Department of Developmental and Cell Biology, University of California at Irvine, Irvine, California, United States of America
- * E-mail: (CS); (MT)
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California at Irvine, Irvine, California, United States of America
- Department of Medicine, University of California at Irvine, Irvine, California, United States of America
- * E-mail: (CS); (MT)
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22
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The human CD10 lacking an N-glycan at Asn(628) is deficient in surface expression and neutral endopeptidase activity. Biochim Biophys Acta Gen Subj 2012; 1820:1715-23. [PMID: 22766194 DOI: 10.1016/j.bbagen.2012.06.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 06/22/2012] [Accepted: 06/25/2012] [Indexed: 11/22/2022]
Abstract
BACKGROUND CD10, also known as neprilysin or enkephalinase exhibiting neutral endopeptidase (NEP) activity, is expressed by B-lineage hematopoietic cells as well as a variety of cells from normal tissues. It cleaves peptides such as cytokines to act for terminating inflammatory responses. Although CD10 molecules of the human pre-B-cell line NALM-6 have 6 consensus N-glycosylation sites, three of them are known to be N-glycosylated by X-ray crystallography. METHODS In order to investigate the role of N-glycans in the full expression of NEP activity, we modified N-glycans by treatment of NALM6 cells with various glycosidases or alter each of the consensus N-glycosylation sites by generating site-directed mutagenesis and compared the NEP activities of the sugar-altered CD10 with those of intact CD10. RESULTS CD10 of the human B-cell line NALM-6 was dominantly localized in raft microdomains and heterogeneously N-glycosylated. Although neither desialylation nor further degalactosylation caused defective NEP activity, removal of only a small part of N-glycans by treatment with glycopeptidase F under non-denaturing conditions decreased NEP activity completely. All of the three consensus sites of CD10 in HEK293 cells introduced with wild type-CD10 were confirmed to be N-glycosylated. Surface expression of N-glycan at Asn(628)-deleted CD10 by HEK293 cells was greatly decreased as well as it lost entire NEP activities. CONCLUSIONS N-glycosylation at Asn(628) is essential not only for NEP activities, but also for surface expression. GENERAL SIGNIFICANCE Quality control system does not allow dysfunctional ecto-type proteases to express on plasma membrane.
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23
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Ibana JA, Aiyar A, Quayle AJ, Schust DJ. Modulation of MICA on the surface of Chlamydia trachomatis-infected endocervical epithelial cells promotes NK cell-mediated killing. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 2012; 65:32-42. [PMID: 22251247 PMCID: PMC5029121 DOI: 10.1111/j.1574-695x.2012.00930.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 01/09/2012] [Accepted: 01/09/2012] [Indexed: 12/24/2022]
Abstract
Chlamydia trachomatis serovars D-K are obligate intracellular bacteria that have tropism for the columnar epithelial cells of the genital tract. Chlamydia trachomatis infection has been reported to induce modifications in immune cell ligand expression on epithelial host cells. In this study, we used an in vitro infection model that resulted in a partial infection of C. trachomatis-exposed primary-like immortalized endocervical epithelial cells (A2EN). Using this model, we demonstrated that expression of the natural killer (NK) cell activating ligand, MHC class I-related protein A (MICA), was upregulated on C. trachomatis-infected, but not on noninfected bystander cells. MICA upregulation was concomitant with MHC class I downregulation and impacted the susceptibility of C. trachomatis-infected cells to NK cell activity. The specificity of MICA upregulation was reflected by a higher cytolytic activity of an NK cell line (NK92MI) against C. trachomatis-infected cells compared with uninfected control cells. Significantly, data also indicated that NK cells exerted a partial, but incomplete sterilizing effect on C. trachomatis as shown by the reduction in recoverable inclusion forming units (IFU) when cocultured with C. trachomatis-infected cells. Taken together, our data suggest that NK cells may play a significant role in the ability of the host to counter C. trachomatis infection.
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Affiliation(s)
- Joyce Altamarino Ibana
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Science Center, New Orleans, LA, USA
| | - Ashok Aiyar
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Science Center, New Orleans, LA, USA
| | - Alison Jane Quayle
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Science Center, New Orleans, LA, USA
| | - Danny Joseph Schust
- Department of Obstetrics, Gynecology and Women’s Health, University of Missouri School of Medicine, Columbia, MO, USA
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24
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Comparative screening of Chlamydia trachomatis infection in women population in tehran, iran. IRANIAN RED CRESCENT MEDICAL JOURNAL 2012; 14:289-93. [PMID: 22829988 PMCID: PMC3398636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Accepted: 01/27/2012] [Indexed: 12/02/2022]
Abstract
BACKGROUND There are more than 30 different sexually transmissible agents while the most common one is Chlamydia trachomatis. In this prospective study, we decided to compare the prevalence of infection in symptomatic and asymptomatic females. METHODS Two hundred sixty urine samples of women in two groups (symptomatic and asymptomatic) were collected from patients attending Mehrad Hospital in Tehran, Iran and tested by polymerase chain reaction. RESULTS Thirty nine women in both groups were infected (14.99%), while 27/130 subjects were in symptomatic group (20.76%), compared with 12/130 person in asymptomatic group (9.23%). No statistically significant difference was found between two groups. Data analysis showed infection with C. trachomatis in symptomatic women to be significantly associated with history of sexually transmitted infections, white blood cells in urine and epithelial cells in urine. CONCLUSION The present study recommends that targeted screening programs in high risk sexually active women (like as individuals who had a history of STIs) are needed as part of case-finding strategies and treatment.
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The Chlamydia protease CPAF regulates host and bacterial proteins to maintain pathogen vacuole integrity and promote virulence. Cell Host Microbe 2011; 10:21-32. [PMID: 21767809 DOI: 10.1016/j.chom.2011.06.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 06/02/2011] [Accepted: 06/24/2011] [Indexed: 11/23/2022]
Abstract
The obligate intracellular bacterial pathogen Chlamydia trachomatis injects numerous effector proteins into the epithelial cell cytoplasm to manipulate host functions important for bacterial survival. In addition, the bacterium secretes a serine protease, chlamydial protease-like activity factor (CPAF). Although several CPAF targets are reported, the significance of CPAF-mediated proteolysis is unclear due to the lack of specific CPAF inhibitors and the diversity of host targets. We report that CPAF also targets chlamydial effectors secreted early during the establishment of the pathogen-containing vacuole ("inclusion"). We designed a cell-permeable CPAF-specific inhibitory peptide and used it to determine that CPAF prevents superinfection by degrading early Chlamydia effectors translocated during entry into a preinfected cell. Prolonged CPAF inhibition leads to loss of inclusion integrity and caspase-1-dependent death of infected epithelial cells. Thus, CPAF functions in niche protection, inclusion integrity and pathogen survival, making the development of CPAF-specific protease inhibitors an attractive antichlamydial therapeutic strategy.
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Jeoung M, Bridges PJ. Cyclic regulation of apoptotic gene expression in the mouse oviduct. Reprod Fertil Dev 2011; 23:638-44. [PMID: 21635812 DOI: 10.1071/rd11011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 02/07/2011] [Indexed: 12/14/2022] Open
Abstract
The oviduct is a dynamic structure whose function relies upon cyclic changes in the morphology of both ciliated and secretory luminal epithelial cells. Unfortunately, infection of these epithelial cells by sexually transmitted pathogens can lead to pelvic inflammatory disease, ectopic pregnancies and infertility. The disruption of normal, cyclic apoptosis in the oviducal epithelium appears to be a causal factor of oviducal pathology and therefore, these pathways represent a potential target for diagnosis and therapeutic intervention. The objective of this study was to determine the pattern of expression for apoptotic genes in the oviduct of the naturally cycling mouse, generating fundamental information that can be applied to the development of animal models for research and the identification of targets for disease intervention. Whole oviducts were collected from regular cycling mice killed at 1p.m. on each day of the oestrous cycle and the expression of 84 apoptotic genes determined by targeted PCR super-array. Intact and cleaved caspases were then evaluated by western blotting. The expression of mRNA for genes classified as pro-apoptotic (Bad, Bak1 and Bok) and anti-apoptotic (Bag3, Bnip2 and Xiap) was regulated by day (P < 0.05). Differences in the temporal expression of several p53-related genes (Trp53bp2, Trp53inp1 and Trp73), those specific to the TNF superfamily (Tnfrsf10 and Tnfsf10b) and one caspase (Casp14) were also observed (P < 0.05). The cleaved forms of Caspases-3, -6 and -12 were all detected throughout the oestrous cycle. These results represent the first pathway-wide analysis of apoptotic gene expression in the murine oviduct.
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Affiliation(s)
- Myoungkun Jeoung
- Division of Clinical and Reproductive Sciences, University of Kentucky, Lexington, KY 40536, USA
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Antichlamydial antibodies, human fertility, and pregnancy wastage. Infect Dis Obstet Gynecol 2011; 2011:525182. [PMID: 21949601 PMCID: PMC3178110 DOI: 10.1155/2011/525182] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Accepted: 06/21/2011] [Indexed: 11/17/2022] Open
Abstract
Genital infections with Chlamydia trachomatis (C. trachomatis) continue to be a worldwide epidemic. Immune response to chlamydia is important to both clearance of the disease and disease pathogenesis. Interindividual responses and current chlamydial control programs will have enormous effects on this disease and its control strategies. Humoral immune response to C. trachomatis occurs in humans and persistent antibody levels appear to be most directly correlated with more severe and longstanding disease and with reinfection. There is a close correlation between the presence of antichlamydial antibodies in females and tubal factor infertility; the closest associations have been found for antibodies against chlamydial heat shock proteins. The latter antibodies have also been shown to be useful among infertile patients with prior ectopic pregnancy, and their presence has been correlated with poor IVF outcomes, including early pregnancy loss. We review the existing literature on chlamydial antibody testing in infertile patients and present an algorithm for such testing in the infertile couple.
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Petyaev IM, Zigangirova NA, Tsibezov VV, Ross A, Bashmakov YK. Monoclonal antibodies against lipopolysaccharide of Chlamydia trachomatis with cross reactivity to human ApoB. Hybridoma (Larchmt) 2011; 30:131-6. [PMID: 21529285 DOI: 10.1089/hyb.2010.0107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Splenocytes obtained from mice immunized with whole purified elementary bodies of Chlamydia trachomatis were used for hybridoma construction. The resulting clones were screened with ELISA using chlamydial lipopolysaccharide (LPS) and full-length human apolipoprotein B (ApoB). One analyzed clone producing IgG1 (MAb 7B5) showed simultaneous recognition of chlamydial LPS and human ApoB, suggesting the presence of common antigenic epitopes in their structures. MAb 7B5 exhibited agreeable activity in immunoblot analysis conducted using chlamydial extracts or full-length human ApoB as well as in immunofluorescence (IF) detecting typical inclusion bodies of C. trachomatis and C. pneumoniae in the infected eukaryotic host cells. The removal of LPS from chlamydial suspensions with lauroyl sarcosyl led to a complete disappearance of IF associated with the elementary bodies of C. trachomatis. Therefore, immunologic response to chlamydial antigen may be associated with the generation of ApoB-specific antibody. Molecular mimicry and subsequent formation of cross-reactive antibodies might be an essential mechanism explaining the appearance of circulating auto-antibodies against low density lipoproteins (LDL) in patients with atherosclerosis. Moreover, newly generated MAb 7B5 can be a useful tool in the laboratory diagnosis of chlamydial infections.
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Affiliation(s)
- Ivan M Petyaev
- Cambridge Theranostics Ltd., Babraham Research Campus, Babraham, Cambridge, United Kingdom
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Wang J, Frohlich KM, Buckner L, Quayle AJ, Luo M, Feng X, Beatty W, Hua Z, Rao X, Lewis ME, Sorrells K, Santiago K, Zhong G, Shen L. Altered protein secretion of Chlamydia trachomatis in persistently infected human endocervical epithelial cells. MICROBIOLOGY-SGM 2011; 157:2759-2771. [PMID: 21737500 DOI: 10.1099/mic.0.044917-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chlamydia trachomatis is the most common bacterial infection of the human reproductive tract globally; however, the mechanisms underlying the adaptation of the organism to its natural target cells, human endocervical epithelial cells, are not clearly understood. To secure its intracellular niche, C. trachomatis must modulate the host cellular machinery by secreting virulence factors into the host cytosol to facilitate bacterial growth and survival. Here we used primary human endocervical epithelial cells and HeLa cells infected with C. trachomatis to examine the secretion of bacterial proteins during productive growth and persistent growth induced by ampicillin. Specifically, we observed a decrease in secretable chlamydial protease-like activity factor (CPAF) in the cytosol of host epithelial cells exposed to ampicillin with no evident reduction of CPAF product by C. trachomatis. In contrast, the expression of CopN and Tarp was downregulated, suggesting that C. trachomatis responds to ampicillin exposure by selectively altering the expression of secretable proteins. In addition, we observed a greater accumulation of outer-membrane vesicles from C. trachomatis in persistently infected cells. Taken together, these results suggest that the regulation of both gene expression and the secretion of chlamydial virulence proteins is involved in the adaptation of the bacteria to a persistent infection state in human genital epithelial cells.
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Affiliation(s)
- Jin Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Kyla M Frohlich
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Lyndsey Buckner
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Alison J Quayle
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Miao Luo
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Xiaogeng Feng
- Department of Molecular Biology and Biochemistry, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Wandy Beatty
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Ziyu Hua
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Xiancai Rao
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Maria E Lewis
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Kelly Sorrells
- Department of Pathology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Kerri Santiago
- Department of Pathology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Li Shen
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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Ibana JA, Schust DJ, Sugimoto J, Nagamatsu T, Greene SJ, Quayle AJ. Chlamydia trachomatis immune evasion via downregulation of MHC class I surface expression involves direct and indirect mechanisms. Infect Dis Obstet Gynecol 2011; 2011:420905. [PMID: 21747639 PMCID: PMC3123996 DOI: 10.1155/2011/420905] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Accepted: 02/15/2011] [Indexed: 11/10/2022] Open
Abstract
Genital C. trachomatis infections typically last for many months in women. This has been attributed to several strategies by which C. trachomatis evades immune detection, including well-described methods by which C. trachomatis decreases the cell surface expression of the antigen presenting molecules major histocompatibility complex (MHC) class I, MHC class II, and CD1d in infected genital epithelial cells. We have harnessed new methods that allow for separate evaluation of infected and uninfected cells within a mixed population of chlamydia-infected endocervical epithelial cells to demonstrate that MHC class I downregulation in the presence of C. trachomatis is mediated by direct and indirect (soluble) factors. Such indirect mechanisms may aid in priming surrounding cells for more rapid immune evasion upon pathogen entry and help promote unfettered spread of C. trachomatis genital infections.
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Affiliation(s)
- Joyce A. Ibana
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Science Center, New Orleans, LA 70112, USA
| | - Danny J. Schust
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri School of Medicine, Columbia, MO 65202, USA
| | - Jun Sugimoto
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri School of Medicine, Columbia, MO 65202, USA
| | - Takeshi Nagamatsu
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri School of Medicine, Columbia, MO 65202, USA
| | - Sheila J. Greene
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Science Center, New Orleans, LA 70112, USA
| | - Alison J. Quayle
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Science Center, New Orleans, LA 70112, USA
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Zhong G. Chlamydia trachomatis secretion of proteases for manipulating host signaling pathways. Front Microbiol 2011; 2:14. [PMID: 21687409 PMCID: PMC3109274 DOI: 10.3389/fmicb.2011.00014] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Accepted: 01/19/2011] [Indexed: 12/23/2022] Open
Abstract
The human pathogen Chlamydia trachomatis secretes numerous effectors into host cells in order to successfully establish and complete the intracellular growth cycle. Three C. trachomatis proteases [chlamydial proteasome/protease-like activity factor (CPAF), tail-specific protease (Tsp), and chlamydial high temperature requirement protein A (cHtrA)] have been localized in the cytosol of the infected cells either by direct immunofluorescence visualization or functional implication. Both CPAF and Tsp have been found to play important roles in C. trachomatis interactions with host cells although the cellular targets of cHtrA have not been identified. All three proteases contain a putative N-terminal signal sequence, suggesting that they may be secreted via a sec-dependent pathway. However, these proteases are also found in chlamydial organism-free vesicles in the lumen of the chlamydial inclusions before they are secreted into host cell cytosol, suggesting that these proteases may first be translocated into the periplasmic region via a sec-dependent pathway and then exported outside of the organisms via an outer membrane vesicles (OMVs) budding mechanism. The vesiculized proteases in the inclusion lumen can finally enter host cell cytosol via vesicle fusing with or passing through the inclusion membrane. Continuing identification and characterization of the C. trachomatis-secreted proteins (CtSPs) will not only promote our understanding of C. trachomatis pathogenic mechanisms but also allow us to gain novel insights into the OMV pathway, a well-known mechanism used by bacteria to export virulence factors although its mechanism remains elusive.
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Affiliation(s)
- Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
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Wu L, Van Kaer L. Natural killer T cells in health and disease. Front Biosci (Schol Ed) 2011; 3:236-51. [PMID: 21196373 DOI: 10.2741/s148] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Natural killer T (NKT) cells are a subset of T lymphocytes that share surface markers and functional characteristics with both conventional T lymphocytes and natural killer cells. Most NKT cells express a semi-invariant T cell receptor that reacts with glycolipid antigens presented by the major histocompatibility complex class I-related protein CD1d on the surface of antigen-presenting cells. NKT cells become activated during a variety of infections and inflammatory conditions, rapidly producing large amounts of immunomodulatory cytokines. NKT cells can influence the activation state and functional properties of multiple other cell types in the immune system and, thus, modulate immune responses against infectious agents, autoantigens, tumors, tissue grafts and allergens. One attractive aspect of NKT cells is that their immunomodulatory activities can be readily harnessed with cognate glycolipid antigens, such as the marine sponge-derived glycosphingolipid alpha-galactosylceramide. These properties of NKT cells are being exploited for therapeutic intervention to prevent or treat cancer, infections, and autoimmune and inflammatory diseases.
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Affiliation(s)
- Lan Wu
- Department of Microbiology and Immunology, Room A-5301, Medical Center North, 1161 21st Avenue South, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2363, USA
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Christian J, Vier J, Paschen SA, Häcker G. Cleavage of the NF-κB family protein p65/RelA by the chlamydial protease-like activity factor (CPAF) impairs proinflammatory signaling in cells infected with Chlamydiae. J Biol Chem 2010; 285:41320-7. [PMID: 21041296 DOI: 10.1074/jbc.m110.152280] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Chlamydiae are obligate intracellular bacteria that frequently cause human disease. Chlamydiae replicate in a membranous vacuole in the cytoplasm termed inclusion but have the ability to transport proteins into the host cell cytosol. Chlamydial replication is associated with numerous changes of host cell functions, and these changes are often linked to proteolytic events. It has been shown earlier that the member of the NF-κB family of inflammation-associated transcription factors, p65/RelA, is cleaved during chlamydial infection, and a chlamydial protease has been implicated. We here provide evidence that the chlamydial protease chlamydial protease-like activity factor (CPAF) is responsible for degradation of p65/RelA during infection. This degradation was seen in human and in mouse cells infected with either Chlamydia trachomatis or Chlamydia pneumoniae where it correlated with the expression of CPAF and CPAF activity. Isolated expression of active C. trachomatis or C. pneumoniae CPAF in human or mouse cells yielded a p65 fragment of indistinguishable size from the one generated during infection. Expression of active CPAF in human cells caused a mild reduction in IκBα phosphorylation but a strong reduction in NF-κB reporter activity in response to interleukin-1β. Infection with C. trachomatis likewise reduced this responsiveness. IL-1β-dependent secretion of IL-8 was further reduced by CPAF expression. Secretion of CPAF is, thus, a mechanism that reduces host cell sensitivity to a proinflammatory stimulus, which may facilitate bacterial growth in vivo.
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Affiliation(s)
- Jan Christian
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, 81675 Munich, Germany
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Bobard A, Mellouk N, Enninga J. Spotting the right location- imaging approaches to resolve the intracellular localization of invasive pathogens. Biochim Biophys Acta Gen Subj 2010; 1810:297-307. [PMID: 21029766 DOI: 10.1016/j.bbagen.2010.10.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/16/2010] [Accepted: 10/18/2010] [Indexed: 10/18/2022]
Abstract
BACKGROUND A common strategy of microbial pathogens is to invade host cells during infection. The invading microbes explore different intracellular compartments to find their preferred niche. SCOPE OF REVIEW Imaging has been instrumental to unravel paradigms of pathogen entry, to identify their exact intracellular location, and to understand the underlying mechanisms for the formation of pathogen-containing niches. Here, we provide an overview of imaging techniques that have been applied to monitor the intracellular lifestyle of pathogens, focusing mainly on bacteria that either remain in vacuolar-bound compartments or rupture the endocytic vacuole to escape into the host's cellular cytoplasm. MAJOR CONCLUSIONS We will depict common molecular and cellular paradigms that are preferentially exploited by pathogens. A combination of electron microscopy, fluorescence microscopy, and time-lapse microscopy has been the driving force to reveal underlying cell biological processes. Furthermore, the development of highly sensitive and specific fluorescent sensor molecules has allowed for the identification of functional aspects of niche formation by intracellular pathogens. GENERAL SIGNIFICANCE Currently, we are beginning to understand the sophistication of the invasion strategies used by bacterial pathogens during the infection process- innovative imaging has been a key ingredient for this. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine.
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Affiliation(s)
- Alexandre Bobard
- Institut Pasteur, Groupe "Dynamique des Interactions Hôte-Pathogène, Paris, France
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CD1d, a sentinel molecule bridging innate and adaptive immunity, is downregulated by the human papillomavirus (HPV) E5 protein: a possible mechanism for immune evasion by HPV. J Virol 2010; 84:11614-23. [PMID: 20810727 DOI: 10.1128/jvi.01053-10] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
CD1d and CD1d-restricted natural killer T (NKT) cells serve as a natural bridge between innate and adaptive immune responses to microbes. CD1d downregulation is utilized by a variety of microbes to evade immune detection. We demonstrate here that CD1d is downregulated in human papillomavirus (HPV)-positive cells in vivo and in vitro. CD1d immunoreactivity was strong in HPV-negative normal cervical epithelium but absent in HPV16-positive CIN1 and HPV6-positive condyloma lesions. We used two cell lines for in vitro assay; one was stably CD1d-transfected cells established from an HPV-negative cervical cancer cell line, C33A (C33A/CD1d), and the other was normal human vaginal keratinocyte bearing endogenous CD1d (Vag). Flow cytometry revealed that cell surface CD1d was downregulated in both C33A/CD1d and Vag cells stably transfected with HPV6 E5 and HPV16 E5. Although the steady-state levels of CD1d protein decreased in both E5-expressing cell lines compared to empty retrovirus-infected cells, CD1d mRNA levels were not affected. Confocal microscopy demonstrated that residual CD1d was not trafficked to the E5-expressing cell surface but colocalized with E5 near the endoplasmic reticulum (ER). In the ER, E5 interacted with calnexin, an ER chaperone known to mediate folding of CD1d. CD1d protein levels were rescued by the proteasome inhibitor, MG132, indicating a role for proteasome-mediated degradation in HPV-associated CD1d downregulation. Taken together, our data suggest that E5 targets CD1d to the cytosolic proteolytic pathway by inhibiting calnexin-related CD1d trafficking. Finally, CD1d-mediated production of interleukin-12 from the C33A/CD1d cells was abrogated in both E5-expressing cell lines. Decreased CD1d expression in the presence of HPV E5 may help HPV-infected cells evade protective immunological surveillance.
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Skwor T, Kandel RP, Basravi S, Khan A, Sharma B, Dean D. Characterization of humoral immune responses to chlamydial HSP60, CPAF, and CT795 in inflammatory and severe trachoma. Invest Ophthalmol Vis Sci 2010; 51:5128-36. [PMID: 20463311 DOI: 10.1167/iovs.09-5113] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
PURPOSE Chlamydia trachomatis (Ct) remains the leading global cause of preventable blindness. There are limited data on humoral immune responses in trachoma. Evaluating these responses is important for understanding host-pathogen interactions and informing vaccine design. Antibodies to chlamydial heat shock protein 60 (cHSP60) have been associated with infertility and trachomatous scarring. Other proteins, including chlamydial protease-associated factor (CPAF) and a hypothetical protein unique to the family Chlamydiaceae, CT795, elicit strong immune responses in urogenital infections, but their role in trachomatous disease is unknown. METHODS This study was conducted to expand on previous cHSP60 findings and evaluate the association of CPAF and CT795 antibodies with ocular Ct infection and disease. Clinical trachoma grading was performed, and conjunctival samples were obtained from individuals with trachomatous trichiasis (TT; one or more inturned eyelashes) or inflammatory trachoma without trichiasis and control subjects without disease, all of whom resided in trachoma-endemic regions of Nepal. Ct infection was determined using commercial PCR. IgG and IgA tear antibodies against cHSP60, CT795, and CPAF fusion proteins were measured by quantitative ELISA. RESULTS Significantly higher IgG antibody levels were found against cHSP60, CPAF, and CT795 in the inflammatory cases compared with levels in the controls (P < 0.005 for all three). Ct infection was independently associated with IgG antibodies against all three immunogens in the inflammatory cases but not in the controls (P = 0.025, P = 0.03 and P = 0.017, respectively). Only IgG antibodies against CPAF were significantly elevated among the TT cases (P = 0.013). CONCLUSIONS Among individuals with trachoma, IgG antibody responses to CPAF are likely to be both a marker and risk factor for inflammatory trachoma and severe trachomatous disease.
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Affiliation(s)
- Troy Skwor
- Center for Immunobiology and Vaccine Development, Children's Hospital Oakland Research Institute, Oakland, California 94609, USA
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Role of high-mobility group box 1 protein and poly(ADP-ribose) polymerase 1 degradation in Chlamydia trachomatis-induced cytopathicity. Infect Immun 2010; 78:3288-97. [PMID: 20421386 DOI: 10.1128/iai.01404-09] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
As intracellular bacteria, chlamydiae block the apoptotic pathways of their host cells. However, the infection of epithelial cells causes the loss of cell membrane integrity and can result in nonapoptotic death. Normally, cells undergoing necrosis release high-mobility group box 1 protein (HMGB1) that acts as an important proinflammatory mediator. Here, we show that in Chlamydia trachomatis-infected HeLa cells HMGB1 is not translocated from the nucleus to the cytosol and not released from injured cells in increased amounts. At 48 h after infection, degradation of HMGB1 was observed. In infected cells, poly(ADP-ribose) polymerase 1 (PARP-1), a DNA repair enzyme that also regulates HMGB1 translocation, was found to be cleaved into fragments that correspond to a necrosis like pattern of PARP-1 degradation. Cell-free cleavage assays and immunoprecipitation using purified proteolytic fractions from infected cells demonstrated that the chlamydial-protease-like activity factor (CPAF) is responsible for the cleavage of both HMGB1 and PARP-1. Proteolytic cleavage of PARP-1 was accompanied by a significant decrease in the enzymatic activity in a time-dependent manner. The loss of PARP-1 function obviously affects the viability of Chlamydia-infected cells because silencing of PARP-1 in uninfected HeLa cells with specific small interfering RNA results in increased cell membrane permeability. Our findings suggest that the Chlamydia-specific protease CPAF interferes with necrotic cell death pathways. By the degradation of HMGB1 and PARP-1, the pathogen may have evolved a strategy to reduce the inflammatory response to membrane-damaged cells in vivo.
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Liu J, Shaji D, Cho S, Du W, Gervay-Hague J, Brutkiewicz RR. A threonine-based targeting signal in the human CD1d cytoplasmic tail controls its functional expression. THE JOURNAL OF IMMUNOLOGY 2010; 184:4973-81. [PMID: 20368272 DOI: 10.4049/jimmunol.0901448] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD1d molecules are MHC class I-like molecules that present lipids to a unique subpopulation of T cells called NKT cells. The cytoplasmic tail of human CD1d possesses a tyrosine-based endosomal targeting motif (YXXZ). As such, these molecules traffic through the endocytic pathway, where it is believed that they are loaded with the antigenic lipid that stimulates NKT cells. In the current study, it was found that the T322 residue in the human CD1d tail is a major signal controlling transport to the cell surface and thus its functional expression. Mimicking the phosphorylation of this residue or removal of the entire cytoplasmic tail negates its ability to regulate CD1d trafficking, resulting in lysosomal targeting and degradation. These results demonstrate an important role of a heretofore unknown signal in the cytoplasmic tail of CD1d that may have relevance to other type I integral membrane proteins that traverse through the endocytic pathway.
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Affiliation(s)
- Jianyun Liu
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Karyagina AS, Alexeevsky AV, Spirin SA, Zigangirova NA, Gintsburg AL. Effector proteins of chlamydiae. Mol Biol 2009. [DOI: 10.1134/s0026893309060016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Zhong G. Killing me softly: chlamydial use of proteolysis for evading host defenses. Trends Microbiol 2009; 17:467-74. [PMID: 19765998 DOI: 10.1016/j.tim.2009.07.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 04/06/2009] [Accepted: 07/13/2009] [Indexed: 12/13/2022]
Abstract
Chlamydial infections in humans cause severe health problems, including blinding trachoma and sexually transmitted diseases. Although the involved pathogenic mechanisms remain unclear, the ability to replicate and maintain long-term residence in the infected cells seems to significantly contribute to chlamydial pathogenicity. These obligate intracellular parasites maintain a delicate balance between exploiting and protecting their host: they occupy intracellular space and acquire nutrients from the infected cells, but at the same time they have to maintain the integrity of the host cells for the completion of their intracellular growth. For this purpose, chlamydiae hijack certain signaling pathways that prevent the host cells from undergoing apoptosis induced by intracellular stress and protect the infected cells from recognition and attack by host defenses. Interestingly, one of the strategies that chlamydiae use for these purposes is the induction of limited proteolysis of host proteins, which is the main focus of this article.
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Affiliation(s)
- Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Abstract
Chlamydia sp. are responsible for a wide range of diseases of significant clinical and public health importance. In this review, we highlight how recent cellular and functional genomic approaches have significantly increased our knowledge of the pathogenic mechanisms used by these genetically intractable bacteria. As the extensive repertoire of chlamydial proteins that are translocated into the mammalian host is identified and characterized, a molecular understanding of how Chlamydiae co-opt host cellular functions and block innate immune pathways is beginning to emerge.
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Affiliation(s)
- Jordan L Cocchiaro
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
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Wu L, Gabriel CL, Parekh VV, Van Kaer L. Invariant natural killer T cells: innate-like T cells with potent immunomodulatory activities. ACTA ACUST UNITED AC 2009; 73:535-45. [DOI: 10.1111/j.1399-0039.2009.01256.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Giles DK, Wyrick PB. Trafficking of chlamydial antigens to the endoplasmic reticulum of infected epithelial cells. Microbes Infect 2008; 10:1494-503. [PMID: 18832043 DOI: 10.1016/j.micinf.2008.09.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2008] [Revised: 08/29/2008] [Accepted: 09/02/2008] [Indexed: 01/02/2023]
Abstract
Confinement of the obligate intracellular bacterium Chlamydia trachomatis to a membrane-bound vacuole, termed an inclusion, within infected epithelial cells neither prevents secretion of chlamydial antigens into the host cytosol nor protects chlamydiae from innate immune detection. However, the details leading to chlamydial antigen presentation are not clear. By immunoelectron microscopy of infected endometrial epithelial cells and in isolated cell secretory compartments, chlamydial major outer membrane protein (MOMP), lipopolysaccharide (LPS) and the inclusion membrane protein A (IncA) were localized to the endoplasmic reticulum (ER) and co-localized with multiple ER markers, but not with markers of the endosomes, lysosomes, Golgi nor mitochondria. Chlamydial LPS was also co-localized with CD1d in the ER. Since the chlamydial antigens, contained in everted inclusion membrane vesicles, were found within the host cell ER, these data raise additional implications for antigen processing by infected uterine epithelial cells for classical and non-classical T cell antigen presentation.
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Affiliation(s)
- David K Giles
- Department of Microbiology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614, USA
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Paschen SA, Christian JG, Vier J, Schmidt F, Walch A, Ojcius DM, Häcker G. Cytopathicity of Chlamydia is largely reproduced by expression of a single chlamydial protease. ACTA ACUST UNITED AC 2008; 182:117-27. [PMID: 18625845 PMCID: PMC2447887 DOI: 10.1083/jcb.200804023] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chlamydiae replicate in a vacuole within epithelial cells and commonly induce cell damage and a deleterious inflammatory response of unknown molecular pathogenesis. The chlamydial protease-like activity factor (CPAF) translocates from the vacuole to the cytosol, where it cleaves several cellular proteins. CPAF is synthesized as an inactive precursor that is processed and activated during infection. Here, we show that CPAF can be activated in uninfected cells by experimentally induced oligomerization, reminiscent of the activation mode of initiator caspases. CPAF activity induces proteolysis of cellular substrates including two novel targets, cyclin B1 and PARP, and indirectly results in the processing of pro-apoptotic BH3-only proteins. CPAF activation induces striking morphological changes in the cell and, later, cell death. Biochemical and ultrastructural analysis of the cell death pathway identify the mechanism of cell death as nonapoptotic. Active CPAF in uninfected human cells thus mimics many features of chlamydial infection, implicating CPAF as a major factor of chlamydial pathogenicity, Chlamydia-associated cell damage, and inflammation.
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Affiliation(s)
- Stefan A Paschen
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, D-81675 Munich, Germany
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Expression of CD1d and ligand-induced cytokine production are tissue specific in mucosal epithelia of the human lower reproductive tract. Infect Immun 2008; 76:3011-8. [PMID: 18458073 DOI: 10.1128/iai.01672-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mucosal epithelia of the human lower reproductive tract (vagina, cervix, and penile urethra) are exposed to sexually transmitted microbes, including Chlamydia trachomatis. The in vivo susceptibility of each tissue type to infection with C. trachomatis is quite distinct. CD1d is expressed on the surface of antigen-presenting cells, including mucosal epithelial cells, and interacts specifically with invariant NKT cells. Invariant NKT cells play a role in both innate and adaptive immune responses to microbes. Here we assessed CD1d expression in normal reproductive tissues by using immunohistochemistry. Immortalized epithelial cell lines from the human lower reproductive tract (vagina, endocervix, and penile urethra) were examined for CD1d expression and for ligand-induced cytokine production induced by CD1d cross-linking. CD1d expression in normal tissue was strong in the vagina but weak in the endocervix and penile urethra. Gamma interferon exposure induced CD1d transcription in all of the cell types studied, with the strongest induction in vaginal cells. Flow cytometry revealed cell surface expression of CD1d in vaginal and penile urethral epithelial cells but not in endocervical cells. Ligation of surface-expressed CD1d by monoclonal antibody cross-linking promoted interleukin-12 (IL-12) and IL-15, but not IL-10, production in vaginal and penile urethral cells. No induction was demonstrated in endocervical cells. CD1d-mediated cytokine production in penile urethral cells was abrogated by C. trachomatis infection. Basal deficiency in CD1d-mediated immune responsiveness may result in susceptibility to sexually transmitted agents. Decreased CD1d-mediated signaling may help C. trachomatis evade detection by innate immune cells.
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Interactions between CdsD, CdsQ, and CdsL, three putative Chlamydophila pneumoniae type III secretion proteins. J Bacteriol 2008; 190:2972-80. [PMID: 18281400 DOI: 10.1128/jb.01997-07] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chlamydophila pneumoniae is a gram-negative obligate intracellular bacterial pathogen that causes pneumonia and bronchitis and may contribute to atherosclerosis. The developmental cycle of C. pneumoniae includes a morphological transition from an infectious extracellular elementary body (EB) to a noninfectious intracellular reticulate body (RB) that divides by binary fission. The C. pneumoniae genome encodes a type III secretion (T3S) apparatus that may be used to infect eukaryotic cells and to evade the host immune response. In the present study, Cpn0712 (CdsD), Cpn0704 (CdsQ), and Cpn0826 (CdsL), three C. pneumoniae genes encoding yersiniae T3S YscD, YscQ, and YscL homologs, respectively, were cloned and expressed as histidine- and glutathione S-transferase (GST)-tagged proteins in Escherichia coli. Purified recombinant proteins were used to raise hyper-immune polyclonal antiserum and were used in GST pull-down and copurification assays to identify protein-protein interactions. CdsD was detected in both EB and RB lysates by Western blot analyses, and immunofluorescent staining demonstrated the presence of CdsD within inclusions. Triton X-114 solubilization and phase separation of chlamydial EB proteins indicated that CdsD partitions with cytoplasmic proteins, suggesting it is not an integral membrane protein. GST pull-down assays indicated that recombinant CdsD interacts with CdsQ and CdsL, and copurification assays with chlamydial lysates confirmed that native CdsD interacts with CdsQ and CdsL. To the best of our knowledge, this is the first report demonstrating interactions between YscD, YscQ, and YscL homologs of bacterial T3S systems. These novel protein interactions may play important roles in the assembly or function of the chlamydial T3S apparatus.
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Chlamydia effector proteins and new insights into chlamydial cellular microbiology. Curr Opin Microbiol 2008; 11:53-9. [DOI: 10.1016/j.mib.2008.01.003] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 01/03/2008] [Accepted: 01/18/2008] [Indexed: 12/28/2022]
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Mori L, De Libero G. Presentation of lipid antigens to T cells. Immunol Lett 2008; 117:1-8. [PMID: 18243339 DOI: 10.1016/j.imlet.2007.11.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Revised: 11/28/2007] [Accepted: 11/30/2007] [Indexed: 11/20/2022]
Abstract
T cells specific for lipid antigens participate in regulation of the immune response during infections, tumor immunosurveillance, allergy and autoimmune diseases. T cells recognize lipid antigens as complexes formed with CD1 antigen-presenting molecules, thus resembling recognition of MHC-peptide complexes. The biophysical properties of lipids impose unique mechanisms for their delivery, internalization into antigen-presenting cells, membrane trafficking, processing, and loading of CD1 molecules. Each of these steps is controlled at molecular and celular levels and determines lipid immunogenicity. Lipid antigens may derive from microbes and from the cellular metabolism, thus allowing the immune system to survey a large repertoire of immunogenic molecules. Recognition of lipid antigens facilitates the detection of infectious agents and the initiation of responses involved in immunoregulation and autoimmunity. This review focuses on the presentation mechanisms and specific recognition of self and bacterial lipid antigens and discusses the important open issues.
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Affiliation(s)
- Lucia Mori
- Experimental Immunology, Department of Research, University Hospital, Basel, Hebelstrasse 20, CH-4031 Basel, Switzerland
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