Spontaneous secretion of interleukin-17 and -22 by human cervical cells in Chlamydia trachomatis infection

Haematopoietic innate interleukin 17A production drives immunopathology in female mouse genital Chlamydia muridarum infection

Chlamydia trachomatis infection is the leading cause of bacterial urogenital infection and has been demonstrated to drive inflammation and scarring of the reproductive tract. Recent studies have identified key triggers of proinflammatory adaptive immune responses driven by innate leukocytes and epithelia driving immunopathology. Utilizing chimeric mouse models, we investigated the definitive source and role of IL17 and IL17 signalling receptors during early Chlamydia muridarum infection of the female urogenital tract. Bone marrow transplants from wild-type (WT) and IL17A-/- mice to recipients demonstrated equivocal infection kinetics in the reproductive tract, but interestingly, adoptive transfer of IL17A-/- immune cells to WT recipients resulted in no infertility, suggesting a haematopoietic (as opposed to tissue) source of IL17 driving immunopathology. To further delineate the role of IL17 in immunopathology, we infected WT and IL17 receptor A (IL17RA)-/- female mice and observed a significant reduction in immunopathology in IL17RA-/- mice. WT bone marrow transplants to IL17RA-/- recipient mice prevented hydrosalpinx, suggesting signalling through IL17RA drives immunopathology. Furthermore, early chemical inhibition of IL17 signalling significantly reduced hydrosalpinx, suggesting IL17 acts as an innate driver of disease. Early during the infection, IL17 was produced by γδ T cells in the cervico-vagina, but more importantly, by neutrophils at the site of infertility in the oviducts. Taken together, these data suggest innate production of IL17 by haematopoietic leukocytes drives immunopathology in the epithelia during early C. muridarum infection of the female reproductive tract.

The role of infected epithelial cells in Chlamydia-associated fibrosis

Ocular, genital, and anogenital infection by the obligate intracellular pathogen Chlamydia trachomatis have been consistently associated with scar-forming sequelae. In cases of chronic or repeated infection of the female genital tract, infection-associated fibrosis of the fallopian tubes can result in ectopic pregnancy or infertility. In light of this urgent concern to public health, the underlying mechanism of C. trachomatis-associated scarring is a topic of ongoing study. Fibrosis is understood to be an outcome of persistent injury and/or dysregulated wound healing, in which an aberrantly activated myofibroblast population mediates hypertrophic remodeling of the basement membrane via deposition of collagens and other components of the extracellular matrix, as well as induction of epithelial cell proliferation via growth factor signaling. Initial study of infection-associated immune cell recruitment and pro-inflammatory signaling have suggested the cellular paradigm of chlamydial pathogenesis, wherein inflammation-associated tissue damage and fibrosis are the indirect result of an immune response to the pathogen initiated by host epithelial cells. However, recent work has revealed more direct routes by which C. trachomatis may induce scarring, such as infection-associated induction of growth factor signaling and pro-fibrotic remodeling of the extracellular matrix. Additionally, C. trachomatis infection has been shown to induce an epithelial-to-mesenchymal transition in host epithelial cells, prompting transdifferentiation into a myofibroblast-like phenotype. In this review, we summarize the field's current understanding of Chlamydia-associated fibrosis, reviewing key new findings and identifying opportunities for further research.

The Role of IL-17 During Infections in the Female Reproductive Tract

Interleukin-17 (IL-17A) is a cytokine involved in a complex array of both protective and detrimental processes. Although early biological studies focused on the pro-inflammatory function of IL-17 in the context of autoimmune and inflammatory disorders, it has become increasingly evident that the roles of IL-17 are far more nuanced. Recent work has demonstrated that the functions of IL-17 are highly context- and tissue-dependent, and there is a fine balance between the pathogenic and protective functions of IL-17. This is especially evident in mucosal tissues such as the female reproductive tract, where IL-17 has been shown to play an important role in the immune response generated during fungal, bacterial and viral infections associated with protection, but also with inflammation. In this review, we discuss the evolving landscape of IL-17 biology within the context of the vaginal mucosa, focusing on key findings that highlight the importance of this cytokine in genital mucosal immunity.

Microbiota-Dependent Effects of IL-22

Cytokines are important contributors to immune responses against microbial and environmental threats and are of particular importance at epithelial barriers. These interfaces are continuously exposed to external factors and thus require immune components to both protect the host from pathogen invasion and to regulate overt inflammation. Recently, substantial efforts have been devoted to understanding how cytokines act on certain cells at barrier sites, and why the dysregulation of immune responses may lead to pathogenesis. In particular, the cytokine IL-22 is involved in preserving an intact epithelium, maintaining a balanced microbiota and a functioning defense system against external threats. However, a tight regulation of IL-22 is generally needed, since uncontrolled IL-22 production can lead to the progression of autoimmunity and cancer. Our aim in this review is to summarize novel findings on IL-22 and its interactions with specific microbial stimuli, and subsequently, to understand their contributions to the function of IL-22 and the clinical outcome. We particularly focus on understanding the detrimental effects of dysregulated control of IL-22 in certain disease contexts.

Mechanisms of sexually transmitted infection-induced inflammation in women: implications for HIV risk

INTRODUCTION

Globally, sexually transmitted infections (STI) affect >300 million people annually, and are a major cause of sexual and reproductive health complications in women. In this commentary, we describe how STIs interact with the immune and non-immune cells, both within and below the cervicovaginal mucosal barrier, to cause inflammation, which in turn has been associated with increased HIV acquisition risk.

DISCUSSION

STIs have a major impact on the female genital mucosa, which is an important biological and physical barrier that forms the first line of defence against invading microorganisms such as HIV. Pattern recognition of STI pathogens, by receptors expressed either on the cell surface or inside the cell, typically triggers inflammation at the mucosal barrier. The types of mucosal responses vary by STI, and can be asymptomatic or culminate in the formation of discharge, ulcers and/or warts. While the aim of this response is to clear the invading microbes, in many cases these responses are either evaded or cause pathology that impairs barrier integrity and increases HIV access to target cells in the sub-mucosa. In addition, innate responses to STIs can result in an increased number of immune cells, including those that are the primary targets of HIV, and may contribute to the association between STIs and increased susceptibility to HIV acquisition. Many of these cells are mediators of adaptive immunity, including tissue-resident cells that may also display innate-like functions. Bacterial vaginosis (BV) is another common cause of inflammation, and evidence for multiple interactions between BV, STIs and HIV suggest that susceptibility to these conditions should be considered in concert.

CONCLUSIONS

STIs and other microbes can induce inflammation in the genital tract, perturbing the normal robust function of the mucosal barrier against HIV. While the impact of STIs on the mucosal immune system and HIV acquisition is often under-appreciated, understanding their interactions of the infections with the immune responses play an important role in improving treatment and reducing the risk of HIV acquisition. The frequent sub-clinical inflammation associated with STIs underscores the need for better STI diagnostics to reverse the immunological consequences of infection.

Effects of Th17 cells and IL-17 in the progression of cervical carcinogenesis with high-risk human papillomavirus infection

The existence of Th17 cells and IL‐17 was recently shown in several types of infectious diseases, but their distribution and functions in cervical lesions with high‐risk human papillomavirus (HPV) infection have not been fully elucidated. In this study, the frequency of Th17 cells in peripheral blood samples obtained from 28 cervical squamous cell carcinoma patients, 26 CIN1 patients, 30 CIN2 patients, 29 CIN3 patients, 25 high‐risk HPV‐infected women with normal cervical cytology, and 30 healthy controls was determined by flow cytometry. Besides, the levels of IL‐17 in peripheral blood samples as well as in supernatant of cervical tissue homogenate were assessed by enzyme‐linked immunosorbent assay (ELISA) simultaneously. We found that during the disease progression of cervical lesions, the proportion of Th17 cells in the total CD4⁺ cells showed a gradually increased tendency compared with the controls (P < 0.05). Moreover, levels of IL‐17 in serum and supernatant of cervical tissue homogenate showed the same tendency as the proportion of Th17 cells (P < 0.05). When compared in pairs, the levels of IL‐17 in supernatant differed significantly among the study groups and the control group (P < 0.05), but no significant difference was observed in serum (P > 0.05). In conclusions, the results indicate that Th17 cells and IL‐17 may play a role of immune enhancement in the infection of high‐risk HPV especially in the cervical microenvironment, which contribute to the disease progression of its associated cervical lesions.

MAIT cells reside in the female genital mucosa and are biased towards IL-17 and IL-22 production in response to bacterial stimulation

The female genital tract (FGT) mucosa is a critically important site for immune defense against microbes. Mucosal-associated invariant T (MAIT) cells are an innate-like T-cell population that recognizes microbial riboflavin metabolite antigens in an MR1-dependent manner. The role of MAIT cells in the FGT mucosa is unknown. Here, we found that MAIT cells and MR1+ antigen-presenting cells were present in the upper and lower FGT, with distinct tissue localization of MAIT cells in endometrium vs. cervix. The MAIT cells from the FGT and blood displayed a distinct phenotype with expression of interleukin (IL)-18Rα, CD127, α4β7, PD-1, as well as the transcription factors promyelocytic leukemia zinc finger (PLZF), RORγt, Helios, Eomes, and T-bet. Their expression levels of PLZF and Eomes were lower in the FGT compared with blood. When stimulated with Escherichia coli, MAIT cells from the FGT displayed a bias towards IL-17 and IL-22 expression, whereas blood MAIT cells produced primarily IFN-γ, TNF, and Granzyme B. Furthermore, both FGT- and blood-derived MAIT cells were polyfunctional and contributed to the T-cell-mediated response to E. coli. Thus, MAIT cells in the genital mucosa have a distinct IL-17/IL-22 profile and may have an important role in the immunological homeostasis and control of microbes at this site.

Antibody and Cytokine Responses of Koalas (Phascolarctos cinereus) Vaccinated with Recombinant Chlamydial Major Outer Membrane Protein (MOMP) with Two Different Adjuvants

Developing a vaccine against Chlamydia is key to combating widespread mortalities and morbidities associated with this infection in koalas (Phascolarctos cinereus). In previous studies, we have shown that two or three doses of a Recombinant Major Outer Membrane Protein (rMOMP) antigen-based vaccine, combined with immune stimulating complex (ISC) adjuvant, results in strong cellular and humoral immune responses in koalas. We have also separately evaluated a single dose vaccine, utilising a tri-adjuvant formula that comprises polyphosphazine based poly I: C and host defense peptides, with the same antigen. This formulation also produced strong cellular and humoral immune responses in captive koalas. In this current study, we directly compared the host immune responses of two sub-groups of wild Chlamydia negative koalas in one population vaccinated with the rMOMP protein antigen and adjuvanted with either the ISC or tri-adjuvant formula. Overall, both adjuvants produced strong Chlamydia-specific cellular (IFN-γ and IL-17A) responses in circulating PBMCs as well as MOMP-specific and functional, in vitro neutralising antibodies. While the immune responses were similar, there were adjuvant-specific immune differences between the two adjuvants, particularly in relation to the specificity of the MOMP epitope antibody responses.

Characterization of IL-22 and IL-17 Expressing Leukocytes in the Cervix

PROBLEM

Identification of the types of cells that produce IL-17 and IL-22 in the genital tract can clarify the roles that these cytokines play in responses to pathogens.

METHOD OF STUDY

We isolated and stimulated cells from cervical tissue to identify and characterize cytokine-producing cells.

RESULTS

Upon stimulation of CD3+ CD4+ endocervical cells, 1.6, 3.4, and 1.5% were induced to produce IL-22, IL-17, and both cytokines, respectively. Stimulation of CD3+ CD4+ ectocervical cells resulted in 3.3% IL-22+, 5.5% IL-17(+) and 2.6% IL-22(+) IL17+ cells. CD45+ CD3- cells had relatively high endogenous levels of cytokine expression that did not increase upon stimulation. Innate lymphoid cells (ILCs) made up 5.7-8% of CD45+ cervical cells and stimulation caused increases in IL-17 and IL-22.

CONCLUSION

These studies show that the majority of the CD45+ leukocytes that can be induced to produce IL-22 and IL-17 in cervix are CD3+ CD4+, but ILCs are also present and can make both cytokines.

Human and Pathogen Factors Associated with Chlamydia trachomatis-Related Infertility in Women

Chlamydia trachomatis is the most common bacterial sexually transmitted pathogen worldwide. Infection can result in serious reproductive pathologies, including pelvic inflammatory disease, ectopic pregnancy, and infertility, in women. However, the processes that result in these reproductive pathologies have not been well defined. Here we review the evidence for the human disease burden of these chlamydial reproductive pathologies. We then review human-based evidence that links Chlamydia with reproductive pathologies in women. We present data supporting the idea that host, immunological, epidemiological, and pathogen factors may all contribute to the development of infertility. Specifically, we review the existing evidence that host and pathogen genotypes, host hormone status, age of sexual debut, sexual behavior, coinfections, and repeat infections are all likely to be contributory factors in development of infertility. Pathogen factors such as infectious burden, treatment failure, and tissue tropisms or ascension capacity are also potential contributory factors. We present four possible processes of pathology development and how these processes are supported by the published data. We highlight the limitations of the evidence and propose future studies that could improve our understanding of how chlamydial infertility in women occurs and possible future interventions to reduce this disease burden.

CXCL10, CXCL11, HLA-A and IL-1β are induced in peripheral blood mononuclear cells from women with Chlamydia trachomatis related infertility

Chlamydia trachomatis infections can result in the development of serious sequelae such as pelvic inflammatory disease and tubal infertility. In this study, peripheral blood mononuclear cells from women who were undergoing or had recently undergone IVF treatment were cultured ex vivo with C. trachomatis to identify the immune responses associated with women who had serological evidence of a history of Chlamydia infection. Cytokines secreted into the supernatant from the cultures were measured using ELISA, and the level of IL-1β was found to be significantly higher in Chlamydia positive women than Chlamydia negative women. qRT-PCR analysis of the expression of 88 immune-related genes showed trends towards an upregulation of CXCL10, CXCL11 and HLA-A in Chlamydia positive women compared with Chlamydia negative women. These findings support that some women launch a more marked proinflammatory response upon infection with C. trachomatis and this may be associated with why C. trachomatis induces infertility in some infected women.

Resolution of Chlamydia trachomatis Infection Is Associated with a Distinct T Cell Response Profile

Chlamydia trachomatis is the causative agent of the most frequently reported bacterial sexually transmitted infection, the total burden of which is underestimated due to the asymptomatic nature of the infection. Untreated C. trachomatis infections can cause significant morbidities, including pelvic inflammatory disease and tubal factor infertility (TFI). The human immune response against C. trachomatis, an obligate intracellular bacterium, is poorly characterized but is thought to rely on cell-mediated immunity, with CD4(+) and CD8(+) T cells implicated in protection. In this report, we present immune profiling data of subjects enrolled in a multicenter study of C. trachomatis genital infection. CD4(+) and CD8(+) T cells from subjects grouped into disease-specific cohorts were screened using a C. trachomatis proteomic library to identify the antigen specificities of recall T cell responses after natural exposure by measuring interferon gamma (IFN-γ) levels. We identified specific T cell responses associated with the resolution of infection, including unique antigens identified in subjects who spontaneously cleared infection and different antigens associated with C. trachomatis-related sequelae, such as TFI. These data suggest that novel and unique C. trachomatis T cell antigens identified in individuals with effective immune responses can be considered as targets for vaccine development, and by excluding antigens associated with deleterious sequelae, immune-mediated pathologies may be circumvented.

The potential protective role of the combination of IL-22 and TNF-α against genital tract Chlamydia trachomatis infection

Th22 cells are a novel class of lymphocytes characterized by the secretion of both IL-22 and TNF-α. In summary, Th22 cells have little or no direct impact on other immune cells, but exert selective effects on epithelia. It is not known, however, whether Th22 cells play a role in genital mucosal immunity. Here, we demonstrate that IL-22 and TNF-α synergistically induce several immunomodulatory molecules, such as the antimicrobial peptide mBD-2 (murine β-defensin 2) and the antimicrobial chemokines CXCL-9, -10, and -11 in primary murine oviduct epithelial cells (MOECs). The induction of innate immunity is relevant in an in vitro infection model, in which MOECs stimulated with Th22 cell supernatants or recombinant IL-22 and TNF-α effectively inhibit the growth of Chlamydia trachomatis and maintain the survival of the epithelia compared with IL-22 or TNF-α alone. In summary, we demonstrate that the Th22 cell cytokines IL-22 and TNF-α play important roles in genital tract infection. The potential for Th22 cell cytokines to modulate innate immune mediators may lead to the development of new topical agents to treat and/or prevent immune-mediated sexually transmitted diseases (STDs). In summary, we demonstrate that IL-22 and TNF-α represent a potent, synergistic cytokine combination for inducing genital mucosal immunity.

Pathogenesis of fallopian tube damage caused by Chlamydia trachomatis infections

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted disease worldwide resulting in 4-5 million new cases of Chlamydia annually and an estimated 100 million cases per annum. Infections of the lower female genital tract (FGT) frequently are asymptomatic; thus, they often remain undiagnosed or untreated. If infections are either not resolved or left untreated, chlamydia can ascend to the upper FGT and infect the fallopian tubes (FTs) causing salpingitis that may lead to functional damage of the FTs and tubal factor infertility (TFI). Clinical observations and experimental data have indicated a role for antibodies against C. trachomatis proteins such as the 60-kDa heat shock protein 60 (cHSP60) in the immunopathogenesis of TFI. When released from infected cells, cHSP60 can induce proinflammatory immune responses that may functionally impair the FTs leading to fibrosis and luminal occlusion. Chlamydial pathogenesis of irreversible and permanent tubal damage is a consequence of innate and adaptive host immune responses to ongoing or repeated infections. The extracellular matrix that is regulated by metalloproteinases may also be modified by chlamydial infections of the FGT. This review will highlight protective and pathogenic immune responses to ongoing and repeated chlamydial infections of the FGT. It will also present two recent hypotheses to explain mechanisms that may contribute to FT damage during a C. trachomatis infection. If Chlamydia immunopathology can be controlled, it might yield a method of inducing fibrosis and thus provide a means of nonsurgical permanent contraception for women.

Interleukin 17A is an immune marker for chlamydial disease severity and pathogenesis in the koala (Phascolarctos cinereus)

The koala (Phascolarctos cinereus) is an iconic Australian marsupial species that is facing many threats to its survival. Chlamydia pecorum infections are a significant contributor to this ongoing decline. A major limiting factor in our ability to manage and control chlamydial disease in koalas is a limited understanding of the koala's cell-mediated immune response to infections by this bacterial pathogen. To identify immunological markers associated with chlamydial infection and disease in koalas, we used koala-specific Quantitative Real Time PCR (qrtPCR) assays to profile the cytokine responses of Peripheral Blood Mononuclear Cells (PBMCs) collected from 41 koalas with different stages of chlamydial disease. Target cytokines included the principal Th1 (Interferon gamma; IFNγ), Th2 (Interleukin 10; IL10), and pro-inflammatory cytokines (Tumor Necrosis Factor alpha; TNFα). A novel koala-specific IL17A qrtPCR assay was also developed as part of this study to quantitate the gene expression of this Th17 cytokine in koalas. A statistically significant higher IL17A gene expression was observed in animals with current chlamydial disease compared to animals with asymptomatic chlamydial infection. A modest up-regulation of pro-inflammatory cytokines, such as TNFα and IFNγ, was also observed in these animals with signs of current chlamydial disease. IL10 gene expression was not evident in the majority of animals from both groups. Future longitudinal studies are now required to confirm the role played by cytokines in pathology and/or protection against C. pecorum infection in the koala.

Frequency of Chlamydia trachomatis-specific T cell interferon-γ and interleukin-17 responses in CD4-enriched peripheral blood mononuclear cells of sexually active adolescent females

An evaluation of CD4 T cell responses to candidate Chlamydia trachomatis vaccine antigens was conducted in an adolescent female cohort exposed through natural infection to explore antigen immunogenicity and correlation with protection from reinfection. The frequency of peripheral blood CD4 T cell IFN-γ and IL-17 responses to three candidate vaccine antigens, polymorphic membrane protein G (PmpG), F (PmpF), and major outer membrane protein (MOMP), were determined by ELISPOT; responses to chlamydial heat shock protein 60 (HSP60) and to elementary bodies (EB) were included for comparison. Responses of Infected (n=8), Seropositive/Uninfected (n=13), and Seronegative/Uninfected (n=18) participants were compared. The median CD4 IFN-γ response to EB was significantly increased in Infected (P=0.003) and Seropositive/Uninfected (P=0.002) versus Seronegative/Uninfected female subjects. Higher rates of positive IFN-γ responders to EB, PmpF, and MOMP were detected in Seropositive/Uninfected versus Seronegative/Uninfected participants (P=0.021). IL-17 responses were generally low. A positive IFN-γ response to any of the antigens tested was associated with a trend toward a reduced risk of reinfection, although not statistically significant. Among this adolescent cohort, chlamydial-specific CD4 IFN-γ but not IL-17 responses were detected in acutely and previously infected participants and a positive CD4 IFN-γ response was associated with a non-significant reduced risk of reinfection.

Interleukin-22 promotes T helper 1 (Th1)/Th17 immunity in chlamydial lung infection

The role of interleukin-22 (IL-22) in intracellular bacterial infections is a controversial issue, although the contribution of this cytokine to host defense against extracellular bacterial pathogens has been well established. In this study, we focused on an intra-cellular bacterium, Chlamydia, and evaluated the production and function of IL-22 in host defense against chlamydial lung infection using a mouse model. We found that Chlamydia muridarum infection elicited quick IL-22 responses in the lung, which increased during infection and were reduced when bacterial loads decreased. More importantly, blockade of endogenous IL-22 using neutralizing anti-IL-22 monoclonal antibodies (mAb) resulted in more severe disease in the mice, leading to significantly higher weight loss and bacterial growth and much more severe pathological changes than treatment with isotype control antibody. Immunological analyses identified significantly lower T helper 1 (Th1) and Th17 responses in the IL-22-neutralized mice. In contrast, intranasal administration of exogenous IL-22 significantly enhanced protection following chlamydial lung infection, which was associated with a significant increase of Th17 response. The data demonstrate that IL-22 is a critical cytokine, mediating host defense against chlamydial lung infection and coordinating the function of distinct Th-cell subsets, particularly Th1 and Th17, in the process.

IL-23 induces IL-22 and IL-17 production in response to Chlamydia muridarum genital tract infection, but the absence of these cytokines does not influence disease pathogenesis

OBJECTIVE

Chlamydia trachomatis infections are a significant cause of reproductive tract pathology. Protective and pathological immune mediators must be differentiated to design a safe and effective vaccine.

METHODS

Wild-type mice and mice deficient in IL-22 and IL-23 were infected intravaginally with Chlamydia muridarum, and their course of infection and oviduct pathology were compared. Local genital tract and draining lymph node immune responses were also examined in IL-23-deficient mice.

RESULTS

IL-22- and IL-23-deficient mice exhibited normal susceptibility to infection and oviduct pathology. IL-23 was required for the development of a Chlamydia-specific Th17 response in the lymph nodes and for production of IL-22 and IL-17 in the genital tract. However, influx of Th1 and innate immune cells was not compromised in the absence of IL-23.

CONCLUSION

IL-22 and IL-23 play either redundant or minimal roles in the pathogenesis of Chlamydia infection in the mouse model. Induction of Th17-associated cytokines by a Chlamydia vaccine should be avoided as these responses are not central to resolution of infection and have pathologic potential.

IL-22 levels are associated with Trichomonas vaginalis infection in the lower genital tract

PROBLEM

IL-22 has important functions at mucosal surfaces, including the induction of antimicrobial peptides and maintenance of epithelium. However, IL-22 has not been investigated in the genital tract during TV infection.

METHODS OF STUDY

Women who visited an STD clinic and women from a cohort with frequent Trichomoniasis were studied. IL-22, IL-17, and antimicrobial peptides were measured in cervicovaginal lavage by ELISA.

RESULTS

In women visiting the STD clinic, those without STDs (n = 10) had a median IL-22 of 0 pg/mL, while women with infections (n = 30) had 27 pg/mL (P = 0.04). In the cohort, women with Trichomoniasis (n = 19) had significantly higher IL-22 than women with no infections (n = 21, 74 versus 0 pg/mL, P = 0.0001). IL-17 was also significantly increased in Trichomoniasis, and there was a correlation between IL-22 and IL-17 (P = 0.001).

CONCLUSION

IL-22 is increased in STDs generally and in Trichomoniasis specifically suggesting an antimicrobial response of the mucosa and an epithelial repair process induced by the STDs.

Transient detection of Chlamydial-specific Th1 memory cells in the peripheral circulation of women with history of Chlamydia trachomatis genital tract infection

PROBLEM

Development of safe and effective Chlamydia trachomatis vaccines requires better understanding of the host immune responses elicited by natural infection.

METHOD OF STUDY

Peripheral blood mononuclear cells isolated from women with or without history of genital tract chlamydial infection were stimulated with inactivated C. trachomatis elementary bodies (EB) in ELISPOT assays that enumerated frequencies of cells producing interferon (IFN)-γ or interleukin (IL)-17.

RESULTS

IFN-γ-positive cells were highest among women sampled 30-60 days after diagnosis of C. trachomatis infection and treatment initiation, while the numbers of IFN-γ-positive cells were equally low among uninfected women and women sampled <30 or >60 days after diagnosis of infection. Conversely, IL-17-positive cell numbers were uniformly low among all participants.

CONCLUSION

Dramatically reduced numbers of Chlamydia-specific Th1 memory cells in the peripheral circulation of study participants sampled more than 2 months after diagnosis, and initiation of treatment provides new insight into the results from C. trachomatis vaccine trials, in which immunization with EB provided only short-lived protection. Our results also suggest that an effective vaccine against this weakly antigenic intracellular pathogen will need to generate immunological memory more durable than that elicited by natural infection.

In Vivo Peripheral Blood Proinflammatory T Cells in Patients with Ankylosing Spondylitis

Objective.

Previous reports have shown an increase in peripheral blood mononuclear cells’ (PBMC) Th17 cell subpopulation and tumor necrosis factor-α (TNF-α) secretion after in vitro stimulation with anti-CD3/CD28 or phorbol myristate acetate/ionomycin in ankylosing spondylitis (AS). The aim of our study was to determine whether there is a Th17 polarization not subjected to in vitro stimulation in patients with AS.

Methods.

Nonstimulated PBMC were analyzed from 46 patients with AS, including 7 (15.2%) receiving tumor necrosis factor-α (TNF-α) inhibitors, 20 patients with rheumatoid arthritis, and 25 healthy controls. The surface phenotype of freshly isolated PBMC was determined by flow cytometry. Th1, Th2, Th17, and Treg subsets were defined as CD3+CD4+IFN-γ+, CD3+CD4+IL-4+, CD3+CD4+IL-17A+, and CD3+CD4+FoxP3+, respectively. Serum cytokines and interleukin 8 (IL-8) levels were quantified by Luminex technology.

Results.

The percentages of Th17 and Th1 cells in AS were higher than in healthy controls (7.4% ± 1.8% vs 0.7% ± 0.2% and 4.0% ± 1.3% vs 1.1% ± 0.3%, respectively; p < 0.0001). Th17 and Th1 cell subsets in patients taking TNF-α inhibitors were lower than in those naive to such therapeutics and similar to healthy controls. Serum levels of IL-6, IL-17A, TNF-α, and IL-8 were significantly higher in patients with AS compared to controls.

Conclusion.

The percentages of Th17 and Th1 cells in PBMC without in vitro stimulation, as well as cytokine and IL-8 levels, were significantly increased in patients with AS compared with healthy controls. These T cell subsets and cytokine profiles of patients with AS taking TNF-α inhibitors were similar to those of healthy controls.

Diversion of the immune response to Neisseria gonorrhoeae from Th17 to Th1/Th2 by treatment with anti-transforming growth factor β antibody generates immunological memory and protective immunity

The immune response to Neisseria gonorrhoeae is poorly understood, but its extensive antigenic variability and resistance to complement are thought to allow it to evade destruction by the host’s immune defenses. We propose that N. gonorrhoeae also avoids inducing protective immune responses in the first place. We previously found that N. gonorrhoeae induces interleukin-17 (IL-17)-dependent innate responses in mice and suppresses Th1/Th2-dependent adaptive responses in murine cells in vitro through the induction of transforming growth factor β (TGF-β). In this study using a murine model of vaginal gonococcal infection, mice treated with anti-TGF-β antibody during primary infection showed accelerated clearance of N. gonorrhoeae, with incipient development of Th1 and Th2 responses and diminished Th17 responses in genital tract tissue. Upon secondary reinfection, mice that had been treated with anti-TGF-β during primary infection showed anamnestic recall of both Th1 and Th2 responses, with the development of antigonococcal antibodies in sera and secretions, and enhanced resistance to reinfection. In mouse knockout strains defective in Th1 or Th2 responses, accelerated clearance of primary infection due to anti-TGF-β treatment was dependent on Th1 activity but not Th2 activity, whereas resistance to secondary infection resulting from anti-TGF-β treatment during primary infection was due to both Th1- and Th2-dependent memory responses. We propose that N. gonorrhoeae proactively elicits Th17-driven innate responses that it can resist and concomitantly suppresses Th1/Th2-driven specific adaptive immunity that would protect the host. Blockade of TGF-β reverses this pattern of host immune responsiveness and facilitates the emergence of protective antigonococcal immunity.

Pathogen-host interactions during infectious disease are conventionally thought of as two-way reactions, that of the host against the pathogen and vice versa, with the outcome dependent on which one ultimately prevails. We propose that Neisseria gonorrhoeae, a pathogen that has become extremely well adapted to its exclusive human host, proactively directs the manner in which the host responds in ways that are beneficial to its own survival but detrimental to the host. Gonorrhea is a widely prevalent sexually transmitted infection, and naturally occurring gonococcal strains are becoming resistant to most available antibiotics, yet no effective vaccine has been developed. These new insights into the immune response to N. gonorrhoeae should lead to novel therapeutic strategies and facilitate new approaches to vaccine development.

Evaluation of a broadly protective Chlamydia-cholera combination vaccine candidate

The need to simultaneously target infections with epidemiological overlap in the population with a single vaccine provides the basis for developing combination vaccines. Vibrio cholerae ghosts (rVCG) offer an attractive approach for developing vaccines against a number of human and animal pathogens. In this study, we constructed a multisubunit vaccine candidate co-expressing the serovar D-derived Porin B and polymorphic membrane protein-D proteins of Chlamydia trachomatis and evaluated its ability to simultaneously induce broad-based chlamydial immunity and elicit a vibriocidal antibody response to the Vibrio carrier envelope. Intramuscular (IM) immunization with the vaccine candidate elicited high levels of antigen-specific genital mucosal and systemic Th1 cell-mediated and humoral immune responses against heterologous serovars and strains, including serovars E-H and L. Also, in addition to the multisubunit vaccine, the single subunit constructs conferred significant cross protection against the heterologous mouse strain, Chlamydia muridarum. Furthermore, all mice immunized with rVCG vaccine constructs responded with a significant rise in vibriocidal antibody titer, the surrogate marker for protection in cholera. These findings demonstrate the ability of the multisubunit vaccine to induce cross protective chlamydial as well as vibriocidal immunity and establish the possibility of developing a broadly efficacious Chlamydia-cholera combination vaccine.