Progesterone activates multiple innate immune pathways in Chlamydia trachomatis-infected endocervical cells

Murine modeling of menstruation identifies immune correlates of protection during Chlamydia muridarum challenge

The menstrual cycle influences the risk of acquiring sexually transmitted infections (STIs), including Chlamydia trachomatis (C. trachomatis), although the underlying immune contributions are poorly defined. A mouse model simulating the immune-mediated process of menstruation could provide valuable insights into tissue-specific determinants of protection against chlamydial infection within the cervicovaginal and uterine mucosae comprising the female reproductive tract (FRT). Here, we used the pseudopregnancy approach in naïve C57Bl/6 mice and performed vaginal challenge with Chlamydia muridarum (C. muridarum) at decidualization, endometrial tissue remodeling, or uterine repair. This strategy identified that the time frame comprising uterine repair correlated with robust infection and greater bacterial burden as compared with mice on hormonal contraception, while challenges during endometrial remodeling were least likely to result in a productive infection. By comparing the infection site at early time points following chlamydial challenge, we found that a greater abundance of innate effector populations and proinflammatory signaling, including IFNγ correlated with protection. FRT immune profiling in uninfected mice over pseudopregnancy or in pig-tailed macaques over the menstrual cycle identified NK cell infiltration into the cervicovaginal tissues and lumen over the course of endometrial remodeling. Notably, NK cell depletion over this time frame reversed protection, with mice now productively infected with C. muridarum following challenge. This study shows that the pseudopregnancy murine menstruation model recapitulates immune changes in the FRT as a result of endometrial remodeling and identifies NK cell localization at the FRT as essential for immune protection against primary C. muridarum infection.

IL-17C is a driver of damaging inflammation during Neisseria gonorrhoeae infection of human Fallopian tube

The human pathogen Neisseria gonorrhoeae ascends into the upper female reproductive tract to cause damaging inflammation within the Fallopian tubes and pelvic inflammatory disease (PID), increasing the risk of infertility and ectopic pregnancy. The loss of ciliated cells from the epithelium is thought to be both a consequence of inflammation and a cause of adverse sequelae. However, the links between infection, inflammation, and ciliated cell extrusion remain unresolved. With the use of ex vivo cultures of human Fallopian tube paired with RNA sequencing we defined the tissue response to gonococcal challenge, identifying cytokine, chemokine, cell adhesion, and apoptosis related transcripts not previously recognized as potentiators of gonococcal PID. Unexpectedly, IL-17C was one of the most highly induced genes. Yet, this cytokine has no previous association with gonococcal infection nor pelvic inflammatory disease and thus it was selected for further characterization. We show that human Fallopian tubes express the IL-17C receptor on the epithelial surface and that treatment with purified IL-17C induces pro-inflammatory cytokine secretion in addition to sloughing of the epithelium and generalized tissue damage. These results demonstrate a previously unrecognized but critical role of IL-17C in the damaging inflammation induced by gonococci in a human explant model of PID.

Endometrial responses to bacterial and viral infection: a scoping review

BACKGROUND

The endometrium is a highly dynamic tissue that undergoes dramatic proliferation and differentiation monthly in order to prepare the uterus for implantation and pregnancy. Intrauterine infection and inflammation are being increasingly recognized as potential causes of implantation failure and miscarriage, as well as obstetric complications later in gestation. However, the mechanisms by which the cells of the endometrium respond to infection remain understudied and recent progress is slowed in part owing to similar overlapping studies being performed in different species.

OBJECTIVE AND RATIONALE

The aim of this scoping review is to systematically summarize all published studies in humans and laboratory animals that have investigated the innate immune sensing and response of the endometrium to bacteria and viruses, and the signaling mechanisms involved. This will enable gaps in our knowledge to be identified to inform future studies.

SEARCH METHODS

The Cochrane Library, Ovid Embase/Medline, PubMed, Scopus, Google Scholar, and Web of Science databases were searched using a combination of controlled and free text terms for uterus/endometrium, infections, and fertility to March 2022. All primary research papers that have reported on endometrial responses to bacterial and viral infections in the context of reproduction were included. To focus the scope of the current review, studies in domesticated animals, included bovine, porcine, caprine, feline, and canine species were excluded.

OUTCOMES

This search identified 42 728 studies for screening and 766 full-text studies were assessed for eligibility. Data was extracted from 76 studies. The majority of studies focused on endometrial responses to Escherichia coli and Chlamydia trachomatis, with some studies of Neisseria gonorrhea, Staphylococcus aureus, and the Streptococcus family. Endometrial responses have only been studied in response to three groups of viruses thus far: HIV, Zika virus, and the herpesvirus family. For most infections, both cellular and animal models have been utilized in vitro and in vivo, focusing on endometrial production of cytokines, chemokines, and antiviral/antimicrobial factors, and the expression of innate immune signaling pathway mediators after infection. This review has identified gaps for future research in the field as well as highlighted some recent developments in organoid systems and immune cell co-cultures that offer new avenues for studying endometrial responses to infection in more physiologically relevant models that could accelerate future findings in this area.

WIDER IMPLICATIONS

This scoping review provides an overarching summary and benchmark of the current state of research on endometrial innate immune responses to bacterial and viral infection. This review also highlights some exciting recent developments that enable future studies to be designed to deepen our understanding of the mechanisms utilized by the endometrium to respond to infection and their downstream effects on uterine function.

Decidualization dampens toll-like receptor mediated inflammatory responses in human endometrial stromal cells by upregulating IκBα

Endometrial stromal cells (EnSCs) are the major cell type of the human endometrium and they undergo dramatic differentiation, termed decidualization, every month that enables them to be receptive to implantation. Appropriate decidualization and EnSC function is key for a successful pregnancy. EnSC function may be affected when the uterus is exposed to bacterial and viral infection. However, how human EnSCs respond to viral and bacterial components have not been well-studied and it remains unclear whether uterine innate immune responses change during decidualization. This study demonstrated that viral double-stranded RNA [Poly(I:C)] and bacterial lipopolysaccharide (LPS) upregulated undecidualized human EnSC production of a large array of proinflammatory cytokines and chemokines, and revealed that these immune responses were significantly dampened during decidualization in vitro and in vivo. This dampened response was associated with increased NFKBIA transcription during decidualization that leads to the accumulation of this negative regulator in decidualizing EnSCs that can bind to NFκB p65 and prevents its nuclear translocation and downstream Toll-like receptor signaling. These findings highlight that endometrial responses to infection may vary at different stages of the menstrual cycle which may be important for preparing the endometrium to support the growth of the semi-allogenic blastocyst. This work emphasizes the need to consider menstrual cycle stage, sex hormone levels and the differentiation status of cells when examining inflammatory responses in the future.

Adherence enables Neisseria gonorrhoeae to overcome zinc limitation imposed by nutritional immunity proteins

Neisseria gonorrhoeae (Gc) must overcome limitation of metals such as zinc to colonize mucosal surfaces in its obligate human host. While the zinc-binding nutritional immunity proteins calprotectin (S100A8/A9) and psoriasin (S100A7) are abundant in human cervicovaginal lavage fluid, Gc possesses TonB-dependent transporters TdfH and TdfJ that bind and extract zinc from the human version of these proteins, respectively. Here we investigated the contribution of zinc acquisition to Gc infection of epithelial cells of the female genital tract. We found that TdfH and TdfJ were dispensable for survival of strain FA1090 Gc that were associated with Ect1 human immortalized epithelial cells, when zinc was limited by calprotectin and psoriasin. In contrast, suspension-grown bacteria declined in viability under the same conditions. Exposure to murine calprotectin, which Gc cannot use as a zinc source, similarly reduced survival of suspension-grown Gc, but not Ect1-associated Gc. We ruled out epithelial cells as a contributor to the enhanced growth of cell-associated Gc under zinc limitation. Instead, we found that attachment to glass was sufficient to enhance bacterial growth when zinc was sequestered. We compared the transcriptional profiles of WT Gc adherent to glass coverslips or in suspension, when zinc was sequestered with murine calprotectin or provided in excess, from which we identified open reading frames that were increased by zinc sequestration in adherent Gc. One of these, ZnuA, was necessary but not sufficient for survival of Gc under zinc-limiting conditions. These results show that adherence protects Gc from zinc-dependent growth restriction by host nutritional immunity proteins.

Effect of Female Sex Hormones on the Immune Response against Chlamydia abortus and on Protection Conferred by an Inactivated Experimental Vaccine in a Mouse Model

Mice are valuable models extensively used to test vaccine candidates against Chlamydia abortus and to clarify immunopathological mechanisms of the bacteria. As this pathogen has the ability to reactivate during pregnancy, it is important to deepen the knowledge and understanding of some of the effects of female hormones on immunity and vaccination. This study is aimed at describing the role of sex hormones in the pathology of OEA during chlamydial clearance using ovariectomised mice and also gaining an understanding of how 17β-oestradiol or progesterone may impact the effectiveness of vaccination. Animals were treated with sex hormones and infected with C. abortus, and the kinetics of infection and immune response were analysed by means of bacterial isolation, histopathology, and immunohistochemistry. In a second phase of the study, protection conferred by an experimental vaccine after hormone treatment was assessed. Oestradiol showed a stimulatory effect on the immune response during infection, with a more efficient recruitment of macrophages and T-cells at the infection site. Furthermore, after vaccination, oestradiol-treated animals showed a stronger protection against infection, indicating that this hormone has a positive effect, stimulating a specific memory response to the pathogen.

Primary ectocervical epithelial cells display lower permissivity to Chlamydia trachomatis than HeLa cells and a globally higher pro-inflammatory profile

The tumoral origin and extensive passaging of HeLa cells, a most commonly used cervical epithelial cell line, raise concerns on their suitability to study the cell responses to infection. The present study was designed to isolate primary epithelial cells from human ectocervix explants and characterize their susceptibility to C. trachomatis infection. We achieved a high purity of isolation, assessed by the expression of E-cadherin and cytokeratin 14. The infectious progeny in these primary epithelial cells was lower than in HeLa cells. We showed that the difference in culture medium, and the addition of serum in HeLa cultures, accounted for a large part of these differences. However, all things considered the primary ectocervical epithelial cells remained less permissive than HeLa cells to C. trachomatis serovar L2 or D development. Finally, the basal level of transcription of genes coding for pro-inflammatory cytokines was globally higher in primary epithelial cells than in HeLa cells. Transcription of several pro-inflammatory genes was further induced by infection with C. trachomatis serovar L2 or serovar D. In conclusion, primary epithelial cells have a strong capacity to mount an inflammatory response to Chlamydia infection. Our simplified purification protocol from human explants should facilitate future studies to understand the contribution of this response to limiting the spread of the pathogen to the upper female genital tract.

Toll-Like Receptor 3 Deficiency Leads to Altered Immune Responses to Chlamydia trachomatis Infection in Human Oviduct Epithelial Cells

Reproductive tract pathology caused by Chlamydia trachomatis infection is an important global cause of human infertility. To better understand the mechanisms associated with Chlamydia-induced genital tract pathogenesis in humans, we used CRISPR genome editing to disrupt Toll-like receptor 3 (TLR3) function in the human oviduct epithelial (hOE) cell line OE-E6/E7 in order to investigate the possible role(s) of TLR3 signaling in the immune response to Chlamydia Disruption of TLR3 function in these cells significantly diminished the Chlamydia-induced synthesis of several inflammation biomarkers, including interferon beta (IFN-β), interleukin-6 (IL-6), interleukin-6 receptor alpha (IL-6Rα), soluble interleukin-6 receptor beta (sIL-6Rβ, or gp130), IL-8, IL-20, IL-26, IL-34, soluble tumor necrosis factor receptor 1 (sTNF-R1), tumor necrosis factor ligand superfamily member 13B (TNFSF13B), matrix metalloproteinase 1 (MMP-1), MMP-2, and MMP-3. In contrast, the Chlamydia-induced synthesis of CCL5, IL-29 (IFN-λ1), and IL-28A (IFN-λ2) was significantly increased in TLR3-deficient hOE cells compared to their wild-type counterparts. Our results indicate a role for TLR3 signaling in limiting the genital tract fibrosis, scarring, and chronic inflammation often associated with human chlamydial disease. Interestingly, we saw that Chlamydia infection induced the production of biomarkers associated with persistence, tumor metastasis, and autoimmunity, such as soluble CD163 (sCD163), chitinase-3-like protein 1, osteopontin, and pentraxin-3, in hOE cells; however, their expression levels were significantly dysregulated in TLR3-deficient hOE cells. Finally, we demonstrate using hOE cells that TLR3 deficiency resulted in an increased amount of chlamydial lipopolysaccharide (LPS) within Chlamydia inclusions, which is suggestive that TLR3 deficiency leads to enhanced chlamydial replication and possibly increased genital tract pathogenesis during human infection.

Effect of female sex hormones on the developmental cycle of Chlamydia abortus compared to a penicillin-induced model of persistent infection

Background

Chlamydia abortus, an obligate intracellular pathogen with an affinity for placenta, causes reproductive failure. In non-pregnant animals, an initial latent infection is established until the next gestation, when the microorganism is reactivated, causing abortion. The precise mechanisms that trigger the awakening of C. abortus are still unknown. Sexual hormones such as estradiol and progesterone have been shown to affect the outcome of infection in other species of the family Chlamydiaceae, while estrogens increase chlamydial infection, progesterone has the opposite effect. To try to establish whether there is a relationship between these events and the latency/ reactivation of C. abortus in the reproductive tract of small ruminants, ovine endometrial (LE) and trophoblastic (AH-1) cells were treated with estradiol or progesterone prior to their infection with C. abortus. The results are compared with those obtained for treatment with penicillin prior to infection, which is a well-established model for studying persistent infection in other chlamydial species. Cells were examined by transmission electron microscopy, and an mRNA expression analysis of 16 genes related to the chlamydial developmental cycle was made.

Results

The changes observed in this study by the action of sex hormones seem to depend on the type of cell where the infection develops. In addition, while the changes are morphologically similar to those induced by treatment with penicillin, the patterns of gene expression are different. Gene expression patterns therefore, seem to depend on the persistence induced models of C. abortus used. Hormone treatments induced aberrant forms in infected endometrial cells but did not affect the chlamydial morphology in trophoblast cells. At the genetic level, hormones did not induce significant changes in the expression of the studied genes.

Conclusions

The results suggest that penicillin induces a state of persistence in in vitro cultured C. abortus with characteristic morphological features and gene transcriptional patterns. However, the influence of hormones on the C. abortus developmental cycle is mediated by changes in the host cell environment. Furthermore, a persistent state in C. abortus cannot be characterised by a single profile of gene expression pattern, but may change depending on the model used to induce persistence.

Effect of progesterone on the vaccination and immune response against Chlamydia abortus in sheep

Chlamydia abortus produces ovine enzootic abortion (OEA). Symptoms are not observed until the organism colonises the placenta, eventually causing abortion. Infected animals become carriers and will shed the organism in the following oestruses. This process suggests that sex hormones might play an important role in the physiopathology of OEA, affecting the success of chlamydial clearance and also jeopardising the effectiveness of vaccination. However, the mechanisms through which sex hormones are involved in chlamydial pathogenicity remain unclear. The aim of this study, therefore, was to determine the effect of progesterone on the immune response against C. abortus and on the protection conferred by an experimental inactivated vaccine in sheep. Eighteen sheep were ovariectomised and divided into four groups: vaccinated and progesterone-treated (V-PG), vaccinated and non-treated (V-NT), non-vaccinated and non-treated (NV-NT) and non-vaccinated and progesterone-treated sheep (NV-PG). Animals from both PG groups were treated with commercial medroxyprogesterone acetate impregnated intravaginal sponges before and during the vaccination (V-PG) or just before challenge (NV-PG). The animals from both V groups were subcutaneously immunised with an experimental inactivated vaccine, which was seen to confer high protection in previous studies. All sheep were challenged intratracheally with C. abortus strain AB7 and were sacrificed on day 8 post-infection. Morbidity was measured as the variation in rectal temperature and samples of sera were collected for antibody and cytokine (IFN-γ and IL-10) analysis by commercial ELISA. In addition, lung and lymph node samples were collected for chlamydial detection by qPCR and for histopathological and immunohistochemical analyses. Sheep from the V-PG group showed less severe or no lesions and lower morbidity than the other groups. They also had the highest abundance of regulatory T-cells. The sheep from V-NT also manifested high antibody levels against C. abortus and less severe lesions than those observed in non-vaccinated sheep, which showed high morbidity, low antibody levels and severe lesions, especially in NV-NT. These results confirm the effectiveness of the experimental vaccine employed and suggest that progesterone could enhance the effect.

The complexity of interactions between female sex hormones and Chlamydia trachomatis infections

PURPOSE OF REVIEW

This review focuses specifically on the mechanisms by which female sex hormones, estrogen and progesterone, affect Chlamydia trachomatis infections in vivo and in vitro.

RECENT FINDINGS

Recent data support previous work indicating that estrogen enhances chlamydial development via multiple mechanisms. Progesterone negatively impacts Chlamydia infections also through multiple mechanisms, particularly by altering the immune response. Conflicting data exist regarding the effect of synthetic hormones, such as those found in hormonal contraceptives, on chlamydial infections.

SUMMARY

Numerous studies over the years have indicated that female sex hormones affect C. trachomatis infection. However, we still do not have a clear understanding of how these hormones alter Chlamydia disease transmission and progression. The studies reviewed here indicate that there are many variables that determine the outcome of Chlamydia/hormone interactions, including: 1) the specific hormone, 2) hormone concentration, 3) cell type or area of the genital tract, 4) hormone responsiveness of cell lines, and 5) animal models.

Update on regulation and effector functions of Th17 cells

T-helper cells that produce IL-17 are recognized as a significant subset within cell-mediated adaptive immunity. These cells are implicated in both the pathology of inflammatory disorders as well as the clearance of extracellular infections and the maintenance of the microbiota. However, the dynamic nature of this cell type has created controversy in understanding Th17 induction as well as Th17 phenotyping, since these cells may switch from Th17 to Treg or Th17 to Th1 cytokine profiles under certain conditions. This review highlights recent advances in Th17 cells in understanding their role in commensal regulation, sex difference in immune outcomes and the immunology of pregnancy, as well as inventive experimental models that have allowed for an increased understanding of Th17 regulation and induction.

Intrauterine delivery of subunit vaccines induces a systemic and mucosal immune response in rabbits

PROBLEM

Mucosal vaccines have long been sought after to improve protection though the production of both a mucosal and systemic immune response, and are thought to be particularly effective at the site of induction. Development of such vaccines has, however, been delayed by the general propensity to develop immune tolerance to antigens encountered at mucosal sites. This study aimed to determine whether an appropriately formulated subunit vaccine delivered to the uterine lumen would effectively trigger induction of immunity over tolerance.

METHODS

Ovalbumin (OVA), truncated glycoprotein D (tGD) from bovine herpesvirus, and a fusion protein of porcine parvovirus VP2 and bacterial thioredoxin (rVP2-TrX) were each formulated with a tri-adjuvant combination of Poly(I : C) (PIC), a host defense peptide (HDP), and a polyphosphazene (PCEP). A single dose of vaccine was delivered either intramuscularly (IM) or into the uterine lumen of intact female rabbits, and the humoral response subsequently evaluated both systemically and at local and distal mucosal sites.

RESULTS

Vaccination through either route-induced antigen-specific humoral responses systemically and within the local (uterus) and distal mucosa (lungs and vagina). The observed mucosal response was not compartmentalized to, or within, the upper genital tract and the degree of response appeared to be at least in part antigen dependant.

CONCLUSION

The results of this study provide proof of principle that the uterus can be used as an induction site for subunit vaccination and that vaccine formulation with appropriate adjuvants can trigger both systemic and mucosal immunity when administered IM or into the uterine lumen.

Genital tract lesions in sexually mature Göttingen minipigs during the initial stages of experimental vaginal infection with Chlamydia trachomatis serovar D

Background

Chlamydia is one of the most common sexually transmitted diseases in humans worldwide, causing chronic lesions in the reproductive tract. Due to its often asymptomatic course, there is limited knowledge about the initial changes in the genital tract following infection. This study employs a novel sexually mature minipig model to investigate the initial histopathological changes following vaginal infection with Chlamydia trachomatis serovar D.

Results

A vaginal inoculation resulted in an infection primarily affecting the lower genital tract. The histopathological changes were characterized by a subepithelial inflammation consisting of neutrophils and mononuclear cells, followed by an increase in the number of plasma cells within the sub-epithelial stroma of the vagina. Detection of Chlamydia was associated with expression of cyclooxygenase-2 and interleukin-8 by superficial epithelial cells. The infection was self-limiting, with a duration of 7 days.

Conclusion

Neutrophils, plasma cells and IL-8 have been linked with Chlamydia genital infection of unknown duration in human patients. In this study, we observe a similar pattern of local immune response/inflammation following experimental inoculation suggesting this porcine model shows promise as a model for translational chlamydia research.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0793-6) contains supplementary material, which is available to authorized users.

Progesterone induces the expression of lipocalin-2 through Akt-c-Myc pathway during mouse decidualization

Lipocalin-2 (Lcn2) is a small glycoprotein involved in a number of biological processes such as inflammation and antibacterial response. In our study, Lcn2 is expressed in the subluminal stromal cells at implantation site on day 5 of pregnancy. The expression of Lcn2 in stromal cells is under the control of progesterone through Akt-c-Myc signaling pathway. Data from Lcn2 knockdown and recombinant protein treatments indicate that Lcn2 promotes mPGES-1 expression in stromal cells. The expression of Lcn2 and mPGES-1 is strongly stimulated by lipopolysaccharide (LPS), indicating that Lcn2 mediates LPS-induced inflammation. These findings shed light on the role of Lcn2 during decidualization.

Natural Course of Chlamydia trachomatis Bacterial Load in the Time Interval between Screening and Treatment in Anogenital Samples

INTRODUCTION

Although Chlamydia trachomatis (CT) is the most common bacterial sexually transmitted infection worldwide, little is known about the natural course of the bacterial load during infection. We investigated the natural course of the bacterial load in the interval between screening and returning for treatment in genital and anorectal CT-infections.

MATERIALS & METHODS

CT-positive patients, visiting our STI-clinic in the Netherlands from June 2011-January 2014, provided a second urogenital and/or anorectal sample when returning for treatment (diagnostic sample = T1; treatment sample = T2). Patient-record provided data about the days between samples and the date of last unsafe sex. Included patients were ≥18 years old, HIV-negative and did not report antibiotic use in the study-interval. CT load was quantified using qPCR. CT load was log-transformed, and a CT load difference (Δ-CT load) of >1 log was deemed clinically relevant. Chi-square test compared load category distributions over time (decrease/equal/increase), between sample types.

RESULTS

274 patients provided 296 paired samples. Majority of samples had a stable CT load in the interval T1-T2 (66.3%, 73.1% and 48.6% for vaginal swabs, urine and anorectal swabs resp. p = 0.07). Load decreased in 17-41% of patients, while ±10% of patients showed an increase in CT load. No association between Δ-CT load and the interval T1-T2 was observed. Large variations can be seen in CT load at T1 and over time.

DISCUSSION

The majority (±90%) of patients have a stable or decreasing CT load in the time interval between screening and returning for treatment. The number of days between sampling was not associated with change in CT load. In the first month after the last unsafe sex, only stable CT loads were seen. Our data seems to indicate that when most patients visit an STI-clinic, recommended 2 weeks after infection, the infection has already been established or is in its downward phase.

Identification of TRIM22 as a progesterone-responsive gene in Ishikawa endometrial cancer cells

Progesterone plays important roles in implantation and maintains pregnancy. It antagonizes estrogen-mediated cell proliferation and promotes differentiation in the uterus. The action of progesterone is mediated by specific receptors, namely, the progesterone receptors (PRs). We generated two Ishikawa cell clones stably expressing PR isoform A (PR-A) and identified progesterone-responsive genes using cDNA microarray analysis. Fifteen genes were identified as progesterone-responsive gene candidates by microarray analysis and their progesterone-responsiveness was shown by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis. Out of these 15 genes, we focused on TRIM22. A database search revealed a progesterone response element (PRE) located from the -25 to -11 bp region upstream of TRIM22 exon 1. This PRE had a 1-bp mismatch in the consensus PRE sequence. A chromatin immunoprecipitation assay revealed that the interaction of PR with the TRIM22 PRE region increased in a hormone-dependent manner. The progesterone-dependent enhancer activity of TRIM22 PRE was demonstrated using a luciferase assay. Based on these results, we propose that TRIM22 is a direct target gene of PR and that it can mediate progesterone actions in uterine cells.

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.

Progesterone antagonizes the positive influence of estrogen on Chlamydia trachomatis serovar E in an Ishikawa/SHT-290 co-culture model

Studies indicate that estrogen enhances Chlamydia trachomatis serovar E infection in genital epithelial cells. Hormones have direct and indirect effects on endometrial epithelial cells. Estrogen and progesterone exposure induces endometrial stromal cells to release effectors that subsequently regulate growth and maturation of uterine epithelial cells. Estrogen enhances C. trachomatis infection by aiding entry and intracellular development in endometrial epithelial cell (Ishikawa, IK)/SHT-290 stromal cell co-culture. Enhanced chlamydial infection was mediated by direct estrogen-stimulated signaling events in epithelial cells and indirectly via estrogen-induced stromal cell effectors. The current study investigates the effects of hormones on chlamydial development using culture conditions representative of the menstrual cycle. Chlamydia trachomatis-infected IK or IK/SHT-290 cultures were exposed to 10(-8) M estrogen (E2), 10(-7) M progesterone (P4) or a combination of both hormones (10(-8) M E2 followed by 10(-9) M E2/10(-7) M P4). Chlamydial infectivity and progeny production were significantly decreased (30-66%) in cultures exposed to progesterone or estrogen/progesterone combination compared to estrogen alone. Thus, progesterone antagonized the positive effects of estrogen on chlamydial infection. These data indicate the susceptibility of endometrial epithelial cells to C. trachomatis infection during the menstrual cycle is altered by phase specific actions of sex hormones in the genital tract.