Pathogenesis of genital tract disease due to Chlamydia trachomatis

Murine MicroRNA-214 regulates intracellular adhesion molecule (ICAM1) gene expression in genital Chlamydia muridarum infection

The hallmark of chlamydial infection is the development of upper genital pathology in the form of hydrosalpinx and oviduct and/or tubal dilatation. Although molecular events leading to genital tissue presentation and cellular architectural remodelling are unclear, early-stage host immune responses are believed to contribute to these long-term sequelae. Recently, we reported the contribution of selected infection-associated microRNAs (miRs) in the generation of host immunity at early-stage infection (day 6 after intravaginal Chlamydia muridarum challenge in C57BL/6 mice). In this report, we describe the contribution of an infection-associated microRNA, i.e. miR-214, to host immunity. Chlamydia muridarum infection in the C57BL/6 mouse genital tract significantly down-regulated miR-214 while up-regulating intracellular adhesion molecule 1 (ICAM1) gene expression. These in vivo observations were confirmed by establishing direct regulation of ICAM-1 by miR-214 in ex vivo genital cell cultures in the presence of miR-214 mimic and inhibitor. Because, ICAM-1 contributes to recruitment of neutrophils following infection, we also demonstrated that alteration of ICAM1 by miR-214 in interleukin-17A-deficient (IL-17A(-/-) ) mice correlated with reduction of neutrophils infiltrating genital tissue at day 6 after challenge. Additionally, these early-stage events resulted in significantly decreased genital pathology in IL-17A(-/-) mice compared with C57BL/6 mice. This report provides evidence for early-stage regulation of ICAM1 by microRNAs, resulting in reduction of genital pathology associated with chlamydial infection.

Porcine retinal cell line VIDO R1 and Chlamydia suis to modelize ocular chlamydiosis

Human ocular Chlamydia trachomatis infections can lead to trachoma, the major cause of infectious blindness worldwide. Trachoma control strategies are very helpful but logistically challenging, and a trachoma vaccine is needed but not available. Pigs are a valuable large animal model for various immunological questions and could facilitate the study of human ocular chlamydial infections. In addition, a recent study identified the zoonotic potential of Chlamydia suis, the natural pathogen of pigs. In terms of the One Health Initiative, understanding the host-pathogen-interactions and finding a vaccine for porcine chlamydia infections would also benefit human health. Thus, we infected the porcine retinal cell line VIDO R1 with C. suis and analyzed the chlamydial life cycle and the innate immune response of the infected cells. Our results indicate that C. suis completes its life cycle in VIDO R1 cells within 48 h, comparable to C. trachomatis in humans. C. suis infection of VIDO R1 cells led to increased levels of various innate immune mediators like pathogen recognition receptors, cytokines and chemokines including IL6, TNFα, and MMP9, also most relevant in human C. trachomatis infections. These results illustrate the first steps in the host-pathogen-interactions of ocular C. suis infections in pigs and show their similarity to C. trachomatis infections in humans, justifying further testing of pigs as an animal model for human trachoma.

Chlamydia muridarum infection of macrophages elicits bactericidal nitric oxide production via reactive oxygen species and cathepsin B

The ability of certain species of Chlamydia to inhibit the biogenesis of phagolysosomes permits their survival and replication within macrophages. The survival of macrophage-adapted chlamydiae correlates with the multiplicity of infection (MOI), and optimal chlamydial growth occurs in macrophages infected at an MOI of ≤1. In this study, we examined the replicative capacity of Chlamydia muridarum in the RAW 264.7 murine macrophage cell line at different MOIs. C. muridarum productively infected these macrophages at low MOIs but yielded few viable elementary bodies (EBs) when macrophages were infected at a moderate (10) or high (100) MOI. While high MOIs caused cytotoxicity and irreversible host cell death, macrophages infected at a moderate MOI did not show signs of cytotoxicity until late in the infectious cycle. Inhibition of host protein synthesis rescued C. muridarum in macrophages infected at a moderate MOI, implying that chlamydial growth was blocked by activated defense mechanisms. Conditioned medium from these macrophages was antichlamydial and contained elevated levels of interleukin 1β (IL-1β), IL-6, IL-10, and beta interferon (IFN-β). Macrophage activation depended on Toll-like receptor 2 (TLR2) signaling, and cytokine production required live, transcriptionally active chlamydiae. A hydroxyl radical scavenger and inhibitors of inducible nitric oxide synthase (iNOS) and cathepsin B also reversed chlamydial killing. High levels of reactive oxygen species (ROS) led to an increase in cathepsin B activity, and pharmacological inhibition of ROS and cathepsin B reduced iNOS expression. Our data demonstrate that MOI-dependent TLR2 activation of macrophages results in iNOS induction via a novel ROS- and cathepsin-dependent mechanism to facilitate C. muridarum clearance.

Diversity of Cervicovaginal Cytokine Response to Incident Chlamydia trachomatis Infection Among a Prospective Cohort of Young Women

PROBLEM

Animal, in vitro, and ex vivo studies have identified several cytokines involved in host immunity to genital Chlamydia trachomatis (CT) infection. However, in vivo cytokine responses are not well described. Our objectives were to document cervicovaginal cytokine levels and intrawoman cytokine changes during incident CT in a prospective cohort.

METHODS

From our prospective cohort, 62 women had incident CT, comprising a CT-negative visit followed by a CT-positive visit. At these visits, cytokine protein levels (IL-6, IL-8, IL-1α, IL-1β, MIP-1α, RANTES, IFN-γ) were measured using cervicovaginal lavages and the MILLIPLEX(™) /Luminex(®) multiplex assay. Quartiles were defined for each cytokine from all 124 visits.

RESULTS

At the group level, RANTES was higher (P < 0.01) at the CT-positive visit than at baseline, but the other cytokines did not significantly differ. For intrawoman cytokine changes, women with a cytokine level that increased at least one quartile higher (going from baseline to the CT-positive visit) ranged between 26 and 53%. Women with a cytokine level staying in the same quartile ranged between 32 and 48%. Women with a cytokine level that decreased at least one quartile lower ranged between 15 and 37%.

CONCLUSION

Intrawoman cervicovaginal cytokine changes during incident CT appear heterogeneous and may reflect differences in natural host immunity.

Dynamics of NKT-Cell Responses to Chlamydial Infection

Natural killer T (NKT) cells have gained great attention owing to their critical functional roles in immunity to various pathogens. In this review, we provide an overview of the current knowledge on the role of NKT cells in host defense against and pathogenesis due to Chlamydia, which is an intracellular bacterial pathogen that poses a threat to the public health worldwide. Accumulating evidence has demonstrated that NKT cells, particularly invariant NKT (iNKT) cells, play a crucial role in host defense against chlamydial infections, especially in C. pneumoniae infection. iNKT cells can promote type-1 protective responses to C. pneumoniae by inducing enhanced production of IL-12 by dendritic cells (DCs), in particular CD8α+ DCs, which promote the differentiation of naive T cells into protective IFN-γ-producing Th1/Tc1 type CD4+/CD8+ T cells. This iNKT-cell-mediated modulation of DC function is largely dependent upon CD40–CD40L interaction, IFN-γ production, and cell-to-cell contact. In addition, iNKT cells modulate the function of natural killer cells. NKT cells may be also involved in the pathogenesis of some chlamydial diseases by inducing different patterns of cytokine production. A better understanding of NKT-cell biology will enable us to rationally design prophylactic and therapeutic tools to combat infectious diseases.

SNP marker discovery in koala TLR genes

Toll-like receptors (TLRs) play a crucial role in the early defence against invading pathogens, yet our understanding of TLRs in marsupial immunity is limited. Here, we describe the characterisation of nine TLRs from a koala immune tissue transcriptome and one TLR from a draft sequence of the koala genome and the subsequent development of an assay to study genetic diversity in these genes. We surveyed genetic diversity in 20 koalas from New South Wales, Australia and showed that one gene, TLR10 is monomorphic, while the other nine TLR genes have between two and 12 alleles. 40 SNPs (16 non-synonymous) were identified across the ten TLR genes. These markers provide a springboard to future studies on innate immunity in the koala, a species under threat from two major infectious diseases.

Cervicovaginal levels of proinflammatory cytokines are increased during chlamydial infection in bacterial vaginosis but not in lactobacilli-dominated flora

OBJECTIVE

The purpose of this study was to assess the cervicovaginal levels of proinflammatory cytokines in women with Chlamydia trachomatis (CT) infection in the presence of bacterial vaginosis (BV) and normal flora and to compare with those negative for CT.

MATERIALS AND METHODS

In this cross-sectional study, nonpregnant women were enrolled at 2 outpatient clinics and at 1 primary medical care unit in São Paulo State, Brazil. Cervicovaginal samples from 256 women with BV, of which 68 (26.6%) had concomitant CT infection and 188 (73.4%) were CT-negative, were measured for interleukin-1β (IL-1β), IL-6, and IL-8 by enzyme-linked immunosorbent assay. A matching number of samples from women with normal flora, CT-positive (n = 68) and negative (n = 188), were evaluated as control. Cytokine levels were compared by Mann-Whitney test and differences were considered significant at p < .05.

RESULTS

In CT-negative women, IL-1β was increased in BV (p < .001) when compared to normal flora, while the levels of IL-6 and IL8 were unchanged. The presence of CT infection was not associated with differences on cytokine levels in women with normal flora. However, women with BV had higher levels of IL-1β (p = .02), IL-6 (p = .02), and IL-8 (p = .03) in the presence of CT when compared to those who tested negative for CT.

CONCLUSIONS

Detection of endocervical CT is associated with increased cervicovaginal IL-1β, IL-6, and IL-8 levels in women with concomitant BV but not in those with normal flora.

Pelvic inflammatory disease in the adolescent: a poignant, perplexing, potentially preventable problem for patients and physicians

PURPOSE OF REVIEW

The present review considers recent pelvic inflammatory disease literature. It remains a difficult condition to accurately diagnose and manage in the adolescent woman. Failure of accurate diagnosis and prompt management leads to complications, including chronic pelvic pain and infertility.

RECENT FINDINGS

Annual chlamydia screening of sexually active adolescents is an important method for early identification of this common cause of this disorder. Youth with positive screens can be lost for treatment if effective follow-up plans are not in place in clinical practice. The intrauterine device is not a risk factor for this condition in adolescents and is a recommended contraceptive device in sexually active adolescent women. A variety of chlamydial antigens are being used to help differentiate lower genital infection from upper genital disorder. Clinicians are not following established protocols for its diagnosis and management.

SUMMARY

Sequelae can be reduced in adolescent women if clinicians continue with regular chlamydia screening in sexually active adolescent women, have a low index of suspicion for pelvic inflammatory disease, carefully follow accepted treatment protocols, and teach youth comprehensive sexuality education including regular condom use. Funded research is needed to develop improved diagnosis and management tools as well as a chlamydia vaccine.

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.

NOD1 in contrast to NOD2 functional polymorphism influence Chlamydia trachomatis infection and the risk of tubal factor infertility

Intracellular pattern-recognition receptors NOD1 and NOD2 are capable of sensing common structural units of bacterial walls. Recognition triggers specific immune signalling pathways and leads to pro-inflammatory cytokine upregulation and adequate immune response. We investigated whether two functional polymorphisms in NOD1 and NOD2 exert an effect on susceptibility to (STD patients) and severity of (female patients visiting the fertility clinic) Chlamydia trachomatis infection in 807 Dutch Caucasian women. A significant association of the NOD1 +32656 GG insertion variant with protection against infection with C. trachomatis has been detected [p: 0.0057; OR: 0.52]. When comparing C. trachomatis-positive women without symptoms to C. trachomatis-positive women with symptoms, and to C. trachomatis-positive women with TFI, we observed an increasing trend in carriage of the GG allele [Ptrend: 0.0003]. NOD2 1007fs failed to reveal an association. We hypothesize that the underlying mechanism might be a functional effect of the GG insertion on IFN-beta-dependent regulation of immune response in the genital tract. The research is part of an ongoing effort of identifying key polymorphisms that determine the risk of TFI and effectively translating them into the clinical setting for the purpose of optimizing diagnostic management of women at risk for developing TFI.

Female reproductive hormones and biomarkers of oxidative stress in genital Chlamydia infection in tubal factor infertility

BACKGROUND

Genital Chlamydia infection (GCI) and the associated pathologies have been implicated in tubal infertility. Though the actual pathologic mechanisms are still uncertain, oxidative stress and other factors have been implicated. The purpose of the study was to determine the possible contribution of female reproductive hormones and biomarkers of oxidative stress in genital Chlamydial infection to tubal occlusion.

METHODS

This prospective case control study was carried out by recruiting 150 age matched women grouped into infertile Chlamydia positive women (n = 50), fertile Chlamydia positive women (n = 50) and fertile Chlamydia negative women as controls (n = 50). High vaginal swabs and endocervical swabs were collected for screening Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, Treponema pallidum, Staphylococcus aureus, and Candida albicans. Sera were collected for estimation of Chlamydia trachomatis antibody, female reproductive hormones [Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Oestradiol (E2), Progesterone (P4), Prolactin (PRL)] and biomarkers of oxidative stress [Total Antioxidant Capacity (TAC) and 8-hydroxyl-2-deoxyguanosine (8-OHdG)] by enzyme immunoassay (EIA). Data were analyzed using chi square, analysis of variance and LSD Post hoc to determine mean differences at p = 0.05.

RESULTS

Among women with GCI, higher levels of LH and 8-OHdG were observed in infertile Chlamydia positive women compared to fertile Chlamydia positive women (p < 0.05). Higher levels of LH and 8-OHdG and lower TAC levels were observed in infertile Chlamydia positive women compared to fertile Chlamydia negative controls (p < 0.05).

CONCLUSION

Mechanisms including oxidative DNA damage and reduced antioxidant capacity may be involved in the pathology of Chlamydia induced tubal damage.

Role of Chlamydia trachomatis and emerging Chlamydia-related bacteria in ectopic pregnancy in Vietnam

In this case-control study, we investigated the seroprevalence and molecular evidence of Chlamydia trachomatis and Waddlia chondrophila in ectopic pregnancies (EP) and uneventful control pregnancies in 343 women from Vietnam. Whereas presence of C. trachomatis IgG was strongly associated with EP [adjusted odds ratio (aOR) 5·41, 95% confidence interval (CI) 2·58-11·32], its DNA remained undetected in all tubal lesions. We confirmed an independent association between antibodies against Waddlia and previous miscarriage (aOR 1·87, 95% CI 1·02-3·42). Further investigations are needed to understand the clinical significance of Waddlia's high seroprevalence (25·9% in control pregnancies) in this urban population.

Andrographolide inhibits intracellular Chlamydia trachomatis multiplication and reduces secretion of proinflammatory mediators produced by human epithelial cells

Chlamydia trachomatis is the most common sexually transmitted bacterial disease worldwide. Untreated C. trachomatis infections may cause inflammation and ultimately damage tissues. Here, we evaluated the ability of Andrographolide (Andro), a natural diterpenoid lactone component of Andrographis paniculata, to inhibit C. trachomatis infection in cultured human cervical epithelial cells. We found that Andro exposure inhibited C. trachomatis growth in a dose- and time-dependent manner. The greatest inhibitory effect was observed when exponentially growing C. trachomatis was exposed to Andro. Electron micrographs demonstrated the accumulation of unusual, structurally deficient chlamydial organisms, correlated with a decrease in levels of OmcB expressed at the late stage of infection. Additionally, Andro significantly reduced the secretion of interleukin6, CXCL8 and interferon-γ-induced protein10 produced by host cells infected with C. trachomatis. These results indicate the efficacy of Andro to perturb C. trachomatis transition from the metabolically active reticulate body to the infectious elementary body and concurrently reduce the production of a proinflammatory mediator by epithelial cells in vitro. Further dissection of Andro's anti-Chlamydia action may provide identification of novel therapeutic targets.

Biological and behavioral risks for incident Chlamydia trachomatis infection in a prospective cohort

OBJECTIVE

To identify biological and behavioral risks for incident Chlamydia trachomatis among a prospective cohort of young women followed frequently.

METHODS

Our cohort of 629 women from two outpatient sites was seen every 4 months (October 2000 through April 2012) for behavioral interviews and infection testing. C trachomatis was tested annually and any time patients reported symptoms or possible exposure using commercial nucleic acid amplification tests. Analyses excluded baseline prevalent C trachomatis infections. Risk factors for incident C trachomatis were assessed using Cox proportional hazards models. Significant risks (P<.10) from bivariate models were entered in a multivariate model adjusted for four covariates chosen a priori (age, race or ethnicity, condom use, study site). Backward stepwise elimination produced a final parsimonious model retaining significant variables (P<.05) and the four adjustment variables.

RESULTS

The 629 women attended 9,594 total visits. Median follow-up time was 6.9 years (interquartile range 3.2-9.8), during which 97 (15%) women had incident C trachomatis. In the final multivariate model, incident C trachomatis was independently associated with human papillomavirus at the preceding visit (P<.01), smoking (P=.02), and weekly use of substances besides alcohol and marijuana (P<.01) since the prior visit. Among 207 women with available colpophotographs (1,742 visits), cervical ectopy was not a significant risk factor (P range=.16-.39 for ectopy as continuous and ordinal variables).

CONCLUSION

Novel risks for C trachomatis include preceding human papillomavirus, smoking, and substance use, which may reflect both biological and behavioral mechanisms of risk such as immune modulation, higher-risk sexual networks, or both. Improved understanding of the biological bases for C trachomatis risk would inform our strategies for C trachomatis control.

Reconceptualizing the chlamydial inclusion as a pathogen-specified parasitic organelle: an expanded role for Inc proteins

Chlamydia is an obligate intracellular pathogen that develops in the host cell in a vacuole termed the chlamydial inclusion. The prevailing concept of the chlamydial inclusion is of a parasitophorous vacuole. Here, the inclusion is the recipient of one-way host-pathogen interactions thus draining nutrients from the cell and negatively impacting it. While Chlamydia orchestrates some aspects of cell function, recent data indicate host cells remain healthy up until, and even after, chlamydial egress. Thus, while Chlamydia relies on the host cell for necessary metabolites, the overall function of the host cell, during chlamydial growth and development, is not grossly disturbed. This is consistent with the obligate intracellular organism's interest to maintain viability of its host. To this end, Chlamydia expresses inclusion membrane proteins, Incs, which serve as molecular markers for the inclusion membrane. Incs also contribute to the physical structure of the inclusion membrane and facilitate host-pathogen interactions across it. Given the function of Incs and the dynamic interactions that occur at the inclusion membrane, we propose that the inclusion behaves similarly to an organelle-albeit one that benefits the pathogen. We present the hypothesis that the chlamydial inclusion acts as a pathogen-specified parasitic organelle. This representation integrates the inclusion within existing subcellular trafficking pathways to divert a subset of host-derived metabolites thus maintaining host cell homeostasis. We review the known interactions of the chlamydial inclusion with the host cell and discuss the role of Inc proteins in the context of this model and how this perspective can impact the study of these proteins. Lessons learnt from the chlamydial pathogen-specified parasitic organelle can be applied to other intracellular pathogens. This will increase our understanding of how intracellular pathogens engage the host cell to establish their unique developmental niches.

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.

Differential infection outcome of Chlamydia trachomatis in human blood monocytes and monocyte-derived dendritic cells

Background

Chlamydia trachomatis is an intracellular bacteria which consist of three biovariants; trachoma (serovars A-C), urogenital (serovars D-K) and lymphogranuloma venereum (L1-L3), causing a wide spectrum of disease in humans. Monocytes are considered to disseminate this pathogen throughout the body while dendritic cells (DCs) play an important role in mediating immune response against bacterial infection. To determine the fate of C. trachomatis within human peripheral blood monocytes and monocyte-derived DCs, these two sets of immune cells were infected with serovars Ba, D and L2, representative of the three biovariants of C. trachomatis.

Results

Our study revealed that the different serovars primarily infect monocytes and DCs in a comparable fashion, however undergo differential infection outcome, serovar L2 being the only candidate to inflict active infection. Moreover, the C. trachomatis serovars Ba and D become persistent in monocytes while the serovars predominantly suffer degradation within DCs. Effects of persistence gene Indoleamine 2, 3-dioxygenase (IDO) was not clearly evident in the differential infection outcome. The heightened levels of inflammatory cytokines secreted by the chlamydial infection in DCs compared to monocytes seemed to be instrumental for this consequence. The immune genes induced in monocytes and DCs against chlamydial infection involves a different set of Toll-like receptors, indicating that distinct intracellular signalling pathways are adopted for immune response.

Conclusion

Our results demonstrate that the host pathogen interaction in chlamydia infection is not only serovar specific but manifests cell specific features, inducing separate immune response cascade in monocytes and DCs.

The porcine innate immune system: an update

Over the last few years, we have seen an increasing interest and demand for pigs in biomedical research. Domestic pigs (Sus scrofa domesticus) are closely related to humans in terms of their anatomy, genetics, and physiology, and often are the model of choice for the assessment of novel vaccines and therapeutics in a preclinical stage. However, the pig as a model has much more to offer, and can serve as a model for many biomedical applications including aging research, medical imaging, and pharmaceutical studies to name a few. In this review, we will provide an overview of the innate immune system in pigs, describe its anatomical and physiological key features, and discuss the key players involved. In particular, we compare the porcine innate immune system to that of humans, and emphasize on the importance of the pig as model for human disease.

Membrane vesicle production by Chlamydia trachomatis as an adaptive response

Bacteria have evolved specific adaptive responses to cope with changing environments. These adaptations include stress response phenotypes with dynamic modifications of the bacterial cell envelope and generation of membrane vesicles (MVs). The obligate intracellular bacterium, Chlamydia trachomatis, typically has a biphasic lifestyle, but can enter into an altered growth state typified by morphologically aberrant chlamydial forms, termed persistent growth forms, when induced by stress in vitro. How C. trachomatis can adapt to a persistent growth state in host epithelial cells in vivo is not well understood, but is an important question, since it extends the host-bacterial relationship in vitro and has thus been indicated as a survival mechanism in chronic chlamydial infections. Here, we review recent findings on the mechanistic aspects of bacterial adaptation to stress with a focus on how C. trachomatis remodels its envelope, produces MVs, and the potential important consequences of MV production with respect to host-pathogen interactions. Emerging data suggest that the generation of MVs may be an important mechanism for C. trachomatis intracellular survival of stress, and thus may aid in the establishment of a chronic infection in human genital epithelial cells.

Reassessing the role of the secreted protease CPAF in Chlamydia trachomatis infection through genetic approaches

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.

Increased susceptibility to vaginal simian/human immunodeficiency virus transmission in pig-tailed macaques coinfected with Chlamydia trachomatis and Trichomonas vaginalis

BACKGROUND

Sexually transmitted infections (STIs) are associated with an increased risk of human immunodeficiency virus (HIV) infection, but their biological effect on HIV susceptibility is not fully understood.

METHODS

Female pig-tailed macaques inoculated with Chlamydia trachomatis and Trichomonas vaginalis (n = 9) or medium (controls; n = 7) were repeatedly challenged intravaginally with SHIVSF162p3. Virus levels were evaluated by real-time polymerase chain reaction, plasma and genital cytokine levels by Luminex assays, and STI clinical signs by colposcopy.

RESULTS

Simian/HIV (SHIV) susceptibility was enhanced in STI-positive macaques (P = .04, by the log-rank test; relative risk, 2.5 [95% confidence interval, 1.1-5.6]). All STI-positive macaques were SHIV infected, whereas 3 controls (43%) remained uninfected. Moreover, relative to STI-negative animals, SHIV infections occurred earlier in the menstrual cycle in STI-positive macaques (P = .01, by the Wilcoxon test). Levels of inflammatory cytokines (interferon γ, interleukin 6, and granulocyte colony-stimulating factor [G-CSF]) were higher in STI-positive macaques during STI inoculation and SHIV exposure periods (P ≤ .05, by the Wilcoxon test).

CONCLUSIONS

C. trachomatis and T. vaginalis infection increase the susceptibility to SHIV, likely because of prolonged genital tract inflammation. These novel data demonstrate a biological link between these nonulcerative STIs and the risk of SHIV infection, supporting epidemiological associations of HIV and STIs. This study establishes a macaque model for studies of high-risk HIV transmission and prevention.

Steroids alone or as adjunctive therapy with doxycycline fail to improve oviduct damage in mice infected with Chlamydia muridarum

In women, Chlamydia trachomatis can ascend from the cervix to the fallopian tubes, where an overly aggressive host inflammatory response can cause scarring that leads to chronic pelvic pain, infertility, or ectopic pregnancy. Although screening and treatment programs for women have resulted in decreased rates of sequelae, morbidities associated with oviduct scarring continue to occur. Since corticosteroids have anti-inflammatory and antifibrotic effects, we tested the ability of dexamethasone to inhibit inflammation and prevent oviduct scarring in mice genitally infected with Chlamydia muridarum. The administration of 1 or 2.5 mg/kg of body weight of dexamethasone on days 7 to 21 of infection resulted in reduced accumulation of inflammatory cells in the oviducts compared to that in controls. However, a concomitant increase in bacterial burden was observed, and chronic oviduct disease was not reduced. Adjunctive administration of a prolonged (21-day) or short (3-day) course of dexamethasone in combination with the antibiotic doxycycline also failed to reduce chronic oviduct pathology compared to antibiotic treatment alone. Steroids administered alone or adjunctively with antibiotics failed to prevent oviduct damage in this murine model of C. trachomatis infection.

Towards a safe and effective chlamydial vaccine: lessons from the eye

As well as being the most common bacterial sexually transmitted infection, Chlamydia trachomatis (Ct) is the leading infectious cause of blindness. The pathogenesis of ocular chlamydial infection (trachoma) is similar to that of genital infection. In the 1960s the efficacy of Ct vaccines against ocular infection was evaluated in major field trials in Saudi Arabia, Taiwan, The Gambia, India and Ethiopia. These trials showed that it was possible to induce short term immunity to ocular infection, and to reduce the incidence of inflammatory trachoma, by parenteral immunisation with killed or live whole organism vaccines. In one study, it was also shown that the incidence of scarring sequelae was reduced in vaccinated children. Detailed studies in non-human primates conducted at this time suggested that vaccination could lead to more severe inflammatory disease on subsequent challenge. Since that time there have been many studies on the immunological correlates of protective immunity and immunopathology in ocular Ct infection in humans and non-human primates, and on host genetic polymorphisms associated with protection from adverse sequelae. These have provided important information to guide the development and evaluation of a human Ct vaccine.

Usefulness of 11C-choline positron emission tomography for genital chlamydial infection assessment in a BALB/c murine model

PURPOSE

The aim of this study is to explore the feasibility of 11C-Choline PET in the assessment of the degree of inflammation in the Chlamydia muridarum genital infection model.

PROCEDURES

Forty female Balb/c mice received 2.5 mg of medroxyprogesterone acetate i.m. 9 and 2 days prior to the infection: 21 mice were infected by C. muridarum into the vaginal vault, 12 mice were treated with inactivated chlamydiae, and 7 mice were SPG buffer-treated as negative controls. Three healthy control mice were not treated with progesterone. Mice in each category were randomly subdivided in two groups: (1) sacrificed at 5, 10, 15, and 20 days for histological analysis and (2) undergoing 11C-Choline PET at days 5, 10, and 20 post-infection (20 MBq of 11C-Choline, uptake time of 10 min, acquisition through a small-animal PET tomograph for 15 min).

RESULTS

Infected animals showed a significantly higher standardized uptake value than both controls and animals inoculated with heat-inactivated chlamydiae in each PET scan (P<0.05). All organs of the infected animals had scores of inflammation ranging between 2 and 3 at day 5, decreasing to 1-2 at day 20.

CONCLUSIONS

This preliminary result demonstrated that 11C-Choline PET can highlight a specific proliferation mechanism of inflammatory cells induced by C. muridarum, thanks to a very high sensitivity in detecting very small amounts of tracer in inflammatory cells.

Simultaneous transcriptional profiling of bacteria and their host cells

We developed an RNA-Seq-based method to simultaneously capture prokaryotic and eukaryotic expression profiles of cells infected with intracellular bacteria. As proof of principle, this method was applied to Chlamydia trachomatis-infected epithelial cell monolayers in vitro, successfully obtaining transcriptomes of both C. trachomatis and the host cells at 1 and 24 hours post-infection. Chlamydiae are obligate intracellular bacterial pathogens that cause a range of mammalian diseases. In humans chlamydiae are responsible for the most common sexually transmitted bacterial infections and trachoma (infectious blindness). Disease arises by adverse host inflammatory reactions that induce tissue damage & scarring. However, little is known about the mechanisms underlying these outcomes. Chlamydia are genetically intractable as replication outside of the host cell is not yet possible and there are no practical tools for routine genetic manipulation, making genome-scale approaches critical. The early timeframe of infection is poorly understood and the host transcriptional response to chlamydial infection is not well defined. Our simultaneous RNA-Seq method was applied to a simplified in vitro model of chlamydial infection. We discovered a possible chlamydial strategy for early iron acquisition, putative immune dampening effects of chlamydial infection on the host cell, and present a hypothesis for Chlamydia-induced fibrotic scarring through runaway positive feedback loops. In general, simultaneous RNA-Seq helps to reveal the complex interplay between invading bacterial pathogens and their host mammalian cells and is immediately applicable to any bacteria/host cell interaction.

Pelvic inflammatory disease: current concepts in pathogenesis, diagnosis and treatment

Pelvic inflammatory disease (PID) is characterized by infection and inflammation of the upper genital tract in women and can cause significant reproductive health sequelae for women. Although a definitive diagnosis of PID is made by laparoscopic visualization of inflamed, purulent fallopian tubes, PID is generally a clinical diagnosis and thus represents a diagnostic challenge. Therefore, diagnosis and treatment algorithms advise a high index of suspicion for PID in any woman of reproductive age with pelvic or abdominal pain. Antibiotic therapy should be started early, and given for an adequate period of time to reduce the risk of complications. Coverage for anaerobic organisms should be considered in most cases.

Ovarian steroid hormones: effects on immune responses and Chlamydia trachomatis infections of the female genital tract

Female sex hormones are known to regulate the adaptive and innate immune functions of the female reproductive tract. This review aims to update our current knowledge of the effects of the sex hormones estradiol and progesterone in the female reproductive tract on innate immunity, antigen presentation, specific immune responses, antibody secretion, genital tract infections caused by Chlamydia trachomatis, and vaccine-induced immunity.

Genetic variation in Chlamydia trachomatis and their hosts: impact on disease severity and tissue tropism

Chlamydia trachomatis infections are a global health problem. This obligate intracellular bacterial pathogen comprises lymphogranuloma venereum (L1-L3), ocular (A-C) and genital (D-K) serovars. Although genetically similar, each serovar group differs in disease severity and tissue tropism through mechanisms that are not well understood. It is clear that host genetic differences also play a role in chlamydial disease outcome and key host polymorphisms are beginning to emerge from both human and experimental animal studies. In this review, we will highlight pathogen and host genes that link genetic diversity, disease severity and tissue tropism. We will also use this information to provide new insights that may be helpful in developing improved management strategies for these important pathogens.

Chlamydia trachomatis infection of the male genital tract: an update

Chlamydia trachomatis (CT) is the most prevalent cause of sexually transmitted diseases. Although the prevalence of chlamydial infection is similar in men and women, current research and screening are still focused on women, who develop the most severe complications, leaving the study of male genital tract (MGT) infection underrated. Herein, we reviewed the literature on genital CT infection with special focus on the MGT. Data indicate that CT certainly infects different parts of the MGT such as the urethra, seminal vesicles, prostate, epididymis and testis. However, whether or not CT infection has detrimental effects on male fertility is still controversial. The most important features of CT infection are its chronic nature and the presence of a mild inflammation that remains subclinical in most individuals. Chlamydia antigens and pathogen recognition receptors (PRR), expressed on epithelial cells and immune cells from the MGT, have been studied in the last years. Toll-like receptor (TLR) expression has been observed in the testis, epididymis, prostate and vas deferens. It has been demonstrated that recognition of chlamydial antigens is associated with TLR2, TLR4, and possibly, other PRRs. CT recognition by PRRs induces a local production of cytokines/chemokines, which, in turn, provoke chronic inflammation that might evolve in the onset of an autoimmune process in genetically susceptible individuals. Understanding local immune response along the MGT, as well as the crosstalk between resident leukocytes, epithelial, and stromal cells, would be crucial in inducing a protective immunity, thus adding to the design of new therapeutic approaches to a Chlamydia vaccine.

Screening and treating Chlamydia trachomatis genital infection to prevent pelvic inflammatory disease: interpretation of findings from randomized controlled trials

We critically reviewed randomized controlled trials evaluating chlamydia screening to prevent pelvic inflammatory disease (PID) and explored factors affecting interpretation and translation of trial data into public health prevention. Taken together, data from these trials offer evidence that chlamydia screening and treatment is an important and useful intervention to reduce the risk of PID among young women. However, the magnitude of benefit to be expected from screening may have been overestimated based on the earliest trials. It is likely that chlamydia screening programs have contributed to declines in PID incidence through shortening prevalent infections, although the magnitude of their contribution remains unclear. Program factors such as screening coverage as well as natural history factors such as risk of PID after repeat chlamydia infection can be important in determining the impact of chlamydia screening on PID incidence in a population. Uptake of chlamydia screening is currently suboptimal, and expansion of screening among young, sexually active women remains a priority. To reduce transmission and repeat infections, implementation of efficient strategies to treat partners of infected women is also essential. Results of ongoing randomized evaluations of the effect of screening on community-wide chlamydia prevalence and PID will also be valuable.

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.

Vesicle-associated membrane protein 4 and syntaxin 6 interactions at the chlamydial inclusion

The predominant players in membrane fusion events are the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) family of proteins. We hypothesize that SNARE proteins mediate fusion events at the chlamydial inclusion and are important for chlamydial lipid acquisition. We have previously demonstrated that trans-Golgi SNARE syntaxin 6 localizes to the chlamydial inclusion. To investigate the role of syntaxin 6 at the chlamydial inclusion, we examined the localization and function of another trans-Golgi SNARE and syntaxin 6-binding partner, vesicle-associated membrane protein 4 (VAMP4), at the chlamydial inclusion. In this study, we demonstrate that syntaxin 6 and VAMP4 colocalize to the chlamydial inclusion and interact at the chlamydial inclusion. Furthermore, in the absence of VAMP4, syntaxin 6 is not retained at the chlamydial inclusion. Small interfering RNA (siRNA) knockdown of VAMP4 inhibited chlamydial sphingomyelin acquisition, correlating with a log decrease in infectious progeny. VAMP4 retention at the inclusion was shown to be dependent on de novo chlamydial protein synthesis, but unlike syntaxin 6, VAMP4 recruitment is observed in a species-dependent manner. Notably, VAMP4 knockdown inhibits sphingomyelin trafficking only to inclusions in which it localizes. These data support the hypothesis that VAMP proteins play a central role in mediating eukaryotic vesicular interactions at the chlamydial inclusion and, thus, support chlamydial lipid acquisition and chlamydial development.

Molecular characterisation and expression analysis of interferon gamma in response to natural Chlamydia infection in the koala, Phascolarctos cinereus

Interferon gamma (IFNγ) is a key Th1 cytokine, with a principal role in the immune response against intracellular organisms such as Chlamydia. Along with being responsible for significant morbidity in human populations, Chlamydia is also responsible for wide spread infection and disease in many animal hosts, with reports that many Australian koala subpopulations are endemically infected. An understanding of the role played by IFNγ in koala chlamydial diseases is important for the establishment of better prophylactic and therapeutic approaches against chlamydial infection in this host. A limited number of IFNγ sequences have been published from marsupials and no immune reagents to measure expression have been developed. Through preliminary analysis of the koala transcriptome, we have identified the full coding sequence of the koala IFNγ gene. Transcripts were identified in spleen and lymph node tissue samples. Phylogenetic analysis demonstrated that koala IFNγ is closely related to other marsupial IFNγ sequences and more distantly related to eutherian mammals. To begin to characterise the role of this important cytokine in the koala's response to chlamydial infection, we developed a quantitative real time PCR assay and applied it to a small cohort of koalas with and without active chlamydial disease, revealing significant differences in expression patterns between the groups. Description of the IFNγ sequence from the koala will not only assist in understanding this species' response to its most important pathogen but will also provide further insight into the evolution of the marsupial immune system.

Perforin-2 restricts growth of Chlamydia trachomatis in macrophages

Chlamydia trachomatis is a Gram-negative obligate intracellular bacterium that preferentially infects epithelial cells. Professional phagocytes provide C. trachomatis only a limited ability to survive and are proficient killers of chlamydiae. We present evidence herein that identifies a novel host defense protein, perforin-2, that plays a significant role in the eradication of C. trachomatis during the infection of macrophages. Knockdown of perforin-2 in macrophages did not alter the invasion of host cells but did result in chlamydial growth that closely mirrored that detected in HeLa cells. C trachomatis L2, serovar B, and serovar D and C. muridarum were all equally susceptible to perforin-2-mediated killing. Interestingly, induction of perforin-2 expression in epithelial cells is blocked during productive chlamydial growth, thereby protecting chlamydiae from bactericidal attack. Ectopic expression of perforin-2 in HeLa cells, however, does result in killing. Overall, our data implicate a new innate resistance protein in the control of chlamydial infection and may help explain why the macrophage environment is hostile to chlamydial growth.

Flavonoid naringenin: a potential immunomodulator for Chlamydia trachomatis inflammation

Chlamydia trachomatis, the agent of bacterial sexually transmitted infections, can manifest itself as either acute cervicitis, pelvic inflammatory disease, or a chronic asymptomatic infection. Inflammation induced by C. trachomatis contributes greatly to the pathogenesis of disease. Here we evaluated the anti-inflammatory capacity of naringenin, a polyphenolic compound, to modulate inflammatory mediators produced by mouse J774 macrophages infected with live C. trachomatis. Infected macrophages produced a broad spectrum of inflammatory cytokines (GM-CSF, TNF, IL-1β, IL-1α, IL-6, IL-12p70, and IL-10) and chemokines (CCL4, CCL5, CXCL1, CXCL5, and CXCL10) which were downregulated by naringenin in a dose-dependent manner. Enhanced protein and mRNA gene transcript expressions of TLR2 and TLR4 in addition to the CD86 costimulatory molecule on infected macrophages were modulated by naringenin. Pathway-specific inhibition studies disclosed that p38 mitogen-activated-protein kinase (MAPK) is involved in the production of inflammatory mediators by infected macrophages. Notably, naringenin inhibited the ability of C. trachomatis to phosphorylate p38 in macrophages, suggesting a potential mechanism of its attenuation of concomitantly produced inflammatory mediators. Our data demonstrates that naringenin is an immunomodulator of inflammation triggered by C. trachomatis, which possibly may be mediated upstream by modulation of TLR2, TLR4, and CD86 receptors on infected macrophages and downstream via the p38 MAPK pathway.

Beyond "safe sex"--can we fight adolescent pelvic inflammatory disease?

Pelvic inflammatory disease (PID) is a common disorder affecting sexually active adolescents. The Centers for Disease Control and Prevention (CDC) and European CDC report Chlamydia trachomatis as the most common sexually transmitted infection and one of the main etiological agents causing PID. C. trachomatis' and PID's high prevalence may be attributed to multiple factors including high-risk sexual behaviors, sensitive laboratory diagnostics (polymerase chain reaction), and the introduction of chlamydia screening programs. The pathogenesis of C. trachomatis infection is complex with recent data highlighting the role of toll-like receptor 2 and four in the mediation of the inflammatory cascade. The authors review the etiology of the disease, explore its pathogenesis, and discuss a variety of strategies that may be implemented to reduce the prevalence of C. trachomatis including: (a) behavioral risk reduction, (b) effective screening of asymptomatic females, (c) targeted male screening, (d) implementation of a sensitive, rapid, self-administered point-of-care testing, and (e) development of an effective vaccine.

Chlamydial intracellular survival strategies

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.

Stimulating an immune response? Oral sex is associated with less endometritis

Secondary analysis of the PID Evaluation and Clinical Health (PEACH) data suggests that among women presenting with signs and symptoms of pelvic inflammatory disease (PID), those who reported oral sex were less likely to have endometritis (adjusted odds ratio [OR] 0.5 [0.3-0.8]) than those who did not report oral sex. Adaptive immunity requires antigenic priming of the lymphatic system. As lymphatic tissue is abundant in the oropharynx, oral sex could lead to effective immune stimulation and prevent PID. To determine whether oral sex could be a protective factor for PID the relationship between self-reported oral sex and endometritis was analysed among 619 women with clinically suspected PID who participated in the PEACH study. Nearly one quarter of participants reported oral sex in the past four weeks. These women also reported a higher number of sexual partners, a new partner within the past four weeks and a higher frequency of sexual intercourse (all P < 0.03). They were more likely to smoke (P < 0.0001), drink alcohol (P < 0.004) and use recreational drugs (P < 0.02). Participants reporting oral sex were significantly less likely to be black or to have a positive test for Neisseria gonorrhoeae (7.8% versus 21.6%, P = 0.001). Women who disclosed oral sex were significantly less likely to have endometritis after adjusting for race, number of partners, recent new partner, smoking, alcohol use and drug use (adjusted OR 0.5 [0.3-0.8]). This is the first paper showing a negative association between oral sex and endometritis. This may be mediated by a protective immune response in the genital tract following priming in the oropharynx. This hypothesis needs to be tested in further studies.

Human female genital tract infection by the obligate intracellular bacterium Chlamydia trachomatis elicits robust Type 2 immunity

While Chlamydia trachomatis infections are frequently asymptomatic, mechanisms that regulate host response to this intracellular Gram-negative bacterium remain undefined. This investigation thus used peripheral blood mononuclear cells and endometrial tissue from women with or without Chlamydia genital tract infection to better define this response. Initial genome-wide microarray analysis revealed highly elevated expression of matrix metalloproteinase 10 and other molecules characteristic of Type 2 immunity (e.g., fibrosis and wound repair) in Chlamydia-infected tissue. This result was corroborated in flow cytometry and immunohistochemistry studies that showed extant upper genital tract Chlamydia infection was associated with increased co-expression of CD200 receptor and CD206 (markers of alternative macrophage activation) by endometrial macrophages as well as increased expression of GATA-3 (the transcription factor regulating T_H2 differentiation) by endometrial CD4⁺ T cells. Also among women with genital tract Chlamydia infection, peripheral CD3⁺ CD4⁺ and CD3⁺ CD4^- cells that proliferated in response to ex vivo stimulation with inactivated chlamydial antigen secreted significantly more interleukin (IL)-4 than tumor necrosis factor, interferon-γ, or IL-17; findings that repeated in T cells isolated from these same women 1 and 4 months after infection had been eradicated. Our results thus newly reveal that genital infection by an obligate intracellular bacterium induces polarization towards Type 2 immunity, including Chlamydia-specific T_H2 development. Based on these findings, we now speculate that Type 2 immunity was selected by evolution as the host response to C. trachomatis in the human female genital tract to control infection and minimize immunopathological damage to vital reproductive structures.

Bacteriological agents which play a role in the development of infertility

This study was carried out to determine the prevalence of the bacterial agents Chlamydia trachomatis (C. trachomatis), Neisseria gonorrhoeae (N. gonorrhoeae), Mycoplasma hominis (M. hominis) and Ureaplasma urealyticum (U. urealyticum) and the conditions which may play a role in the development of female infertility, in the county of Iaşi in North-Eastern Romania. Cervical and blood samples were collected from 176 infertile women and 45 pregnant women in the third trimester. Classical methods and real time PCR were applied to each cervical sample to detect the presence of these sexually transmitted microorganisms; the ELISA method was applied to blood samples to detect C. trachomatis antibodies (IgA, IgM and IgG). The proportion of C. trachomatis IgG was significantly higher in the infertile group (23.8%) than in the pregnant group (4.4%), p < 0.05. For C. trachomatis antigen (Ag) and N. gonorrhoeae Ag no differences were observed between the two groups. The prevalence of mycoplasma genital infections was higher in the pregnant group (U. urealyticum - 53.3% and M. hominis - 20%) than in the infertile group (U. urealyticum - 39.7% and M. hominis - 7.3%). Higher rate of co-infection with C. trachomatis and mycoplasma were observed among the infertile women (25.7%) than among the pregnant women (7.7%). This combination could be involved in the appearance of pelvic inflammatory disease (PID) and its sequela, including infertility. C. trachomatis IgG determination still remains the gold standard for the diagnosis of PID and should be used as a screening test for the prediction of tubal damage in infertile women. In view of the large number of cases involving the co-existence of genital infections with C. trachomatis, M. hominis and U. urealyticum, it is clearly necessary to perform screening for all three microorganisms among all women of reproductive age but especially those who are infertile.

Trachoma: protective and pathogenic ocular immune responses to Chlamydia trachomatis

Trachoma, caused by Chlamydia trachomatis (Ct), is the leading infectious blinding disease worldwide. Chronic conjunctival inflammation develops in childhood and leads to eyelid scarring and blindness in adulthood. The immune response to Ct provides only partial protection against re-infection, which can be frequent. Moreover, the immune response is central to the development of scarring pathology, leading to loss of vision. Here we review the current literature on both protective and pathological immune responses in trachoma. The resolution of Ct infection in animal models is IFNγ-dependent, involving Th1 cells, but whether this is the case in human ocular infection still needs to be confirmed. An increasing number of studies indicate that innate immune responses arising from the epithelium and other innate immune cells, along with changes in matrix metalloproteinase activity, are important in the development of tissue damage and scarring. Current trachoma control measures, which are centred on repeated mass antibiotic treatment of populations, are logistically challenging and have the potential to drive antimicrobial resistance. A trachoma vaccine would offer significant advantages. However, limited understanding of the mechanisms of both protective immunity and immunopathology to Ct remain barriers to vaccine development.

Detection of C. trachomatis in the serum of the patients with urogenital chlamydiosis

Extragenital chlamydial complications may be associated with systemic spread of infection, but haematogenous route for C. trachomatis dissemination has not been clearly demonstrated. Here we report that serum specimens obtained from patients with chlamydiosis contain elementary bodies of C. trachomatis shown by culture and immunogold electron microscopy. We have found that 31 of the 52 patients had serum precipitates which were infective to McCoy cells. Immunostaining revealed very small inclusions resembling those reported during persistent C. trachomatis infection in vitro. DNA specimens from 49 (out of 52) patients with chlamydiosis gave positive PCR readings. The viability of the pathogen present in the sera was confirmed by chlamydial RNA detection in the cell monolayer inoculated by the serum precipitates. By using DNA isolation protocol from 1 mL of serum and quantitative TaqMan PCR, it was estimated that bacterial load in patients' sera was 2 × 10²–10³ GE/mL. These findings for the first time demonstrated that C. trachomatis can be disseminated directly by the plasma, independently from blood cell, which may represent a new possible pathway of the chronic infection development. Therefore, new methodological approaches for detection of C. trachomatis in the serum of patients with complicated and chronic chlamydiosis could be important in the diagnosis of the infection regardless of its anatomical localization.

Interruption of CXCL13-CXCR5 axis increases upper genital tract pathology and activation of NKT cells following chlamydial genital infection

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.