TNF-{alpha} Production from CD8+ T Cells Mediates Oviduct Pathological Sequelae Following Primary Genital Chlamydia muridarum Infection

South Texas Center for Emerging Infectious Diseases, Department of Biology, University of Texas at San Antonio, San Antonio, Texas 78249, USA.
Infection and immunity (Impact Factor: 3.73). 07/2011; 79(7):2928-35. DOI: 10.1128/IAI.05022-11
Source: PubMed


The immunopathogenesis of Chlamydia trachomatis-induced oviduct pathological sequelae is not well understood. Mice genetically deficient in perforin (perforin−/− mice) or tumor necrosis factor alpha (TNF-α) production (TNF-α−/− mice) displayed comparable vaginal chlamydial clearance rates but significantly reduced oviduct pathology (hydrosalpinx)
compared to that of wild-type mice. Since both perforin and TNF-α are effector mechanisms of CD8+ T cells, we evaluated the role of CD8+ T cells during genital Chlamydia muridarum infection and oviduct sequelae. Following vaginal chlamydial challenge, (i) mice deficient in TAP I (and therefore the major
histocompatibility complex [MHC] I pathway and CD8+ T cells), (ii) wild-type mice depleted of CD8+ T cells, and (iii) mice genetically deficient in CD8 (CD8−/− mice) all displayed similar levels of vaginal chlamydial clearance but significantly reduced hydrosalpinx, compared to those
of wild-type C57BL/6 mice, suggesting a role for CD8+ T cells in chlamydial pathogenesis. Repletion of CD8−/− mice with wild-type or perforin−/−, but not TNF-α−/−, CD8+ T cells at the time of challenge restored hydrosalpinx to levels observed in wild-type C57BL/6 mice, suggesting that TNF-α
production from CD8+ T cells is important for pathogenesis. Additionally, repletion of TNF-α−/− mice with TNF-α+/+ CD8+ T cells significantly enhanced the incidence of hydrosalpinx and oviduct dilatation compared to those of TNF-α−/− mice but not to the levels found in wild-type mice, suggesting that TNF-α production from CD8+ T cells and non-CD8+ cells cooperates to induce optimal oviduct pathology following genital chlamydial infection. These results provide compelling
new evidence supporting the contribution of CD8+ T cells and TNF-α production to Chlamydia-induced reproductive tract sequelae.

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    • "These authors concluded that perforin-dependent cytolytic CD8 + T cells do not control endocervical bacterial loads. An alternative contribution of CD8 + T cells to oviduct pathology via TNF-α secretion was suggested by studies in mice by Murthy et al., (2011). Overall there is a dearth of data regarding immune responses to chlamydial infections of the male urogenital tract despite the fact that infected males may develop several sequelae including urethritis, epididymitis, orchitis, and chronic prostatitis. "
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    ABSTRACT: Sexually transmitted infections (STIs) comprise more than 30 different bacterial, viral, protozoal, and yeast infections acquired during sexual intercourse and therefore directly afflicting the genital tracts or gaining systemic access across the genital mucosae. Effective vaccines have been developed against only two viral STIs (hepatitis B and human papillomavirus). For most STIs, the nature of the immune responses induced and the parameters of immunity against them are poorly understood. However, progress has been made in comprehending responses especially against Neisseria gonorrhoeae, Chlamydia trachomatis, Haemophilus ducreyi, and Candida albicans. An emerging aspect is that these well-adapted human pathogens exploit the unique characteristics of immunity in the reproductive tracts, eliciting responses favorable to their own survival and suppressing those that would be detrimental to them. Elucidation of the mechanisms whereby STI pathogens manipulate the host's immune responses will lead to novel approaches for therapy and vaccine development.
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    • "As seen in our previous study, treating wild type C57BL/6 mice with MLA did not change the severity of reproductive tract pathology (data not shown). Perforin knockout mice trended toward less pathology than wild type mice (50% less; p value = 0.17) consistent with previously published data [8], [15]. "
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    ABSTRACT: CD4 T cells are critical for clearing experimental Chlamydia muridarum genital tract infections. Two independent in vitro CD4 T cell mechanisms have been identified for terminating Chlamydia replication in epithelial cells. One mechanism, requiring IFN-γ and T cell-epithelial cell contact, terminates infection by triggering epithelial production of nitric oxide to chlamydiacidal levels; the second is dependent on T cell degranulation. We recently demonstrated that there are two independent in vivo clearance mechanisms singly sufficient for clearing genital tract infections within six weeks; one dependent on iNOS, the other on Plac8. Redundant genital tract clearance mechanisms bring into question negative results in single-gene knockout mice. Two groups have shown that perforin-knockout mice were not compromised in their ability to clear C. muridarum genital tract infections. Because cell lysis would be detrimental to epithelial nitric oxide production we hypothesized that perforin was not critical for iNOS-dependent clearance, but posited that perforin could play a role in Plac8-dependent clearance. We tested whether the Plac8-dependent clearance was perforin-dependent by pharmacologically inhibiting iNOS in perforin-knockout mice. In vitro we found that perforin was detrimental to iNOS-dependent CD4 T cell termination of Chlamydia replication in epithelial cells. In vivo, unexpectedly, clearance in perforin knockout mice was delayed to the end of week 7 regardless of iNOS status. The discordant in vitro/in vivo results suggest that the perforin's contribution to bacterial clearance in vivo is not though enhancing CD4 T cell termination of Chlamydia replication in epithelial cells, but likely via a mechanism independent of T cell-epithelial cell interactions.
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    • "While natural immunity confers resistance to reinfection, at least a subset of immune responses has been shown to be instrumental in the causation of pathologies. For example, several factors including activation of toll-like receptor-2 [5], neutrophil and matrix metalloprotease responses [6], [7], and CD8+ T cells and TNF-α production [8] have been shown to contribute to the development of chlamydial pathological sequelae in the mouse model. Thus, the development of varying degrees of immune responses among individuals in a population, and pathological responses specifically, may determine the development of disease sequelae in some but not all infected women. "
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    ABSTRACT: Chlamydia trachomatis is the most common bacterial sexually transmitted disease in the world and specifically in the United States, with the highest incidence in age-groups 14-19 years. In a subset of females, the C. trachomatis genital infection leads to serious pathological sequelae including pelvic inflammatory disease, ectopic pregnancy, and infertility. Chlamydia pneumoniae, another member of the same genus, is a common cause of community acquired respiratory infection with significant number of children aged 5-14 yr displaying sero-conversion. Since these bacteriae share several antigenic determinants, we evaluated whether intranasal immunization with live C. pneumoniae (1×10(6) inclusion forming units; IFU) in 5 week old female C57BL/6 mice would induce cross-species protection against subsequent intravaginal challenge with Chlamydia muridarum (5×10(4) IFU), which causes a similar genital infection and pathology in mice as C. trachomatis in humans. Mice vaccinated intranasally with live C. pneumoniae, but not mock (PBS) immunized animals, displayed high levels of splenic cellular antigen-specific IFN-γ production and serum antibody response against C. muridarum and C. trachomatis. Mice vaccinated with C. pneumoniae displayed a significant reduction in the vaginal C. muridarum shedding as early as day 12 after secondary i.vag. challenge compared to PBS (mock) immunized mice. At day 19 after C. muridarum challenge, 100% of C. pneumoniae vaccinated mice had cleared the infection compared to none (0%) of the mock immunized mice, which cleared the infection by day 27. At day 80 after C. muridarum challenge, C. pneumoniae vaccinated mice displayed a significant reduction in the incidence (50%) and degree of hydrosalpinx compared to mock immunized animals (100%). These results suggest that respiratory C. pneumoniae infection induces accelerated chlamydial clearance and reduction of oviduct pathology following genital C. muridarum challenge, and may have important implications to the C. trachomatis-induced reproductive disease in humans.
    Full-text · Article · May 2013 · PLoS ONE
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