Chlamydia trachomatis and chlamydial heat shock protein 60-specific antibody and cell-mediated responses predict tubal factor infertility

Immunity to Sexually Transmitted Bacterial Infections of the Female Genital Tract: Toward Effective Vaccines

Sexually transmitted infections (STIs) caused by bacterial pathogens Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum present significant public health challenges. These infections profoundly impact reproductive health, leading to pelvic inflammatory disease, infertility, and increased susceptibility to other infections. Prevention measures, including antibiotic treatments, are limited by the often-asymptomatic nature of these infections, the need for repetitive and continual screening of sexually active persons, antibiotic resistance for gonorrhea, and shortages of penicillin for syphilis. While vaccines exist for viral STIs like human papillomavirus (HPV) and hepatitis B virus (HBV), there are no vaccines available for bacterial STIs. This review examines the immune responses in the female genital tract to these bacterial pathogens and the implications for developing effective vaccines against bacterial STIs.

Chlamydia trachomatis Seroassays Used in Epidemiologic Research: A Narrative Review and Practical Considerations

Chlamydia trachomatis (CT) is a sexually transmitted infection that can lead to adverse reproductive health outcomes. CT prevalence estimates are primarily derived from screening using nucleic acid amplification tests (NAATs). However, screening guidelines in the United States only include particular subpopulations, and NAATs only detect current infections. In contrast, seroassays identify past CT infections, which is important for understanding the public health impacts of CT, including pelvic inflammatory disease and tubal factor infertility. Older seroassays have been plagued by low sensitivity and specificity and have not been validated using a consistent reference measure, making it challenging to compare studies, define the epidemiology of CT, and determine the effectiveness of control programs. Newer seroassays have better performance characteristics. This narrative review summarizes the "state of the science" for CT seroassays that have been applied in epidemiologic studies and provides practical considerations for interpreting the literature and employing seroassays in future research.

Impact of a positive Chlamydia trachomatis serology on cumulative IVF live birth rate

RESEARCH QUESTION

Does positive Chlamydia trachomatis serology have an impact on the cumulative live birth rate from IVF?

DESIGN

A retrospective matched cohort study compared women with positive Chlamydia trachomatis serology (group A) who underwent IVF treatment between January 2016 and December 2021 with a control group of women with negative Chlamydia trachomatis serology (group B). The main outcome measures were the cumulative live birth rate per IVF cycle and the live birth rate per embryo transfer. Secondary outcomes were the cumulative rates of clinical pregnancy, ectopic pregnancy and pregnancy loss calculated per IVF cycle and per embryo transfer.

RESULTS

A total of 151 women in group A were matched 1:2 to 302 women in group B, representing 220 and 440 IVF cycles, respectively. Women with a history of Chlamydia trachomatis infection had a significantly higher rate of tubal obstruction (P < 0.001), excluded or operated hydrosalpinx (P = 0.002) and/or history of chronic endometritis (P < 0.001). There were no statistically significant differences between the two groups in the mean number of mature oocytes retrieved, fertilization rate or implantation rate. The IVF cumulative live birth rate per cycle was similar in the two groups (36.7% in group A versus 34.9% in group B, P = 0.692). The cumulative rates of clinical pregnancy, pregnancy loss, biochemical pregnancy and ectopic pregnancy were comparable between the two groups.

CONCLUSION

Positive Chlamydia trachomatis serology has no impact on IVF pregnancy outcomes.

Sexually Transmitted Infections and Risk of Epithelial Ovarian Cancer: Results From the Finnish Maternity Cohort

BACKGROUND

Sexually transmitted infections, specifically Chlamydia trachomatis (CT), may be associated with epithelial ovarian cancer (EOC) risk. The association between CT and EOC subtypes is unclear. Our aim was to investigate whether history of CT and other infections (Mycoplasma genitalium [MG], herpes simplex virus type 2 [HSV-2], and human papillomavirus [HPV]) are associated with EOC risk by histotype.

METHODS

We measured antibodies (Abs) to CT, MG, HSV-2, and HPV-16/18 in serum samples in a nested case-control study in the Finnish Maternity Cohort (N = 484 cases 1:1 matched to controls). Logistic regression was used to calculate relative risks (RRs) and 95% confidence intervals (CIs) in seropositive versus seronegative individuals in all cases, as well as serous (n = 249), clear cell and endometrioid (n = 91), and mucinous (n = 144) EOC.

RESULTS

CT seropositivity was not associated with EOC risk (eg, CT pGP3-Ab: RR, 0.92 [95% CI, .72-1.19]), regardless of disease subtype. We observed a positive association between MG seropositivity and mucinous EOC (RR, 1.66 [95% CI, 1.09-2.54]; P for heterogeneity by histotype ≤ .001), but not other subtypes. No associations were observed with seropositivity to multiple STIs.

CONCLUSIONS

CT infection was not associated with EOC risk, with associations observed only for MG and mucinous EOC. Mechanisms linking MG to mucinous EOC remain to be elucidated.

Associations of Chlamydia trachomatis serology with fertility-related and pregnancy adverse outcomes in women: a systematic review and meta-analysis of observational studies

BACKGROUND

Chlamydia trachomatis (CT) infection has an increased risk for fertility-related and pregnancy adverse outcomes partly due to mechanisms related to a pro-inflammatory response to CT-, or cHSP60-induced delayed hypersensitivity. This study aimed to assess the evidence on the association between CT serology and adverse outcomes.

METHODS

PubMed/Medline, Embase and Web of Science databases were searched for observational studies on the association of CT-specific antibodies (e. g. IgG, IgA, IgM, etc.) with infertility, tubal factor infertility (TFIF), ectopic pregnancy (EP), spontaneous abortion (SA), or preterm labor (PL) that were published from database inception to 31 August 2022. Pooled adjusted odds ratios or relative risks with corresponding 95% confidence intervals were calculated using a random effects model. This study was registered with PROSPERO (CRD42022368366).

FINDINGS

We identified 128 studies that met the inclusion criteria, comprising 87 case-control, 34 cross-sectional and 7 cohort studies, for a total of 167 records involving 128,625 women participants included into the meta-analyses. Based on the adjusted estimates, it was found that CT-specific IgG was significantly associated with TFIF (pooled adjusted OR = 2.09, 95% CI 1.33-3.27, I2 = 63.8%) or EP (pooled adjusted OR = 3.00, 95% CI 1.66-5.40, I2 = 93.0%). Analyses of the unadjusted estimates indicated significant associations between CT-specific IgG and infertility, TFIF, EP or SA (four pooled unadjusted ORs ranging between 1.60 and 5.14, I2 ranging between 40% and 83%); IgA and infertility, TFIF, EP (three pooled unadjusted ORs ranging between 3.64 and 4.91, I2 ranging between 0% and 74%); IgM and TFIF (pooled unadjusted OR = 5.70, 95% CI 1.58-20.56, I2 = 56%); or cHSP60 and TFIF (pooled unadjusted OR = 7.83, 95% CI 5.42-11.31, I2 = 49%).

INTERPRETATION

A broad range of CT-specific antibodies have been studied in association with fertility-related and pregnancy adverse outcomes. However, our study identified a low- or moderate-quality evidence for an association of CT serology with the outcomes. There are substantial research gaps in relation to the clinical implications of CT serological biomarkers.

FUNDING

The work was supported by the Chinese Academy of Medical Sciences Initiative for Innovative Medicine (2016-I2M-3-021).

Reproductive system infections in women: lower genital tract syndromes

Gynecological and obstetrical infectious diseases are an important component of women's health. A system approach to gynecological and obstetrical infection helps unify and classify microbial etiology and pathogenesis within a clinical anatomical framework of lower and upper genital tract syndromes. The reproductive system of women includes the vulva, vagina, cervix, uterus, fallopian tubes and ovaries. During pregnancy, additional tissues include the chorioamnion and placenta together with the fetus and amniotic fluid. We review in two parts reproductive system infection syndromes in women using selected research results to illustrate the clinical utility of the system approach in terms of diagnosis, treatment and prevention. We conclude that a reproductive system perspective will lead to improvements in understanding, management and prevention of these diseases.

Immunopathogenesis of genital Chlamydia infection: insights from mouse models

Chlamydiae are pathogenic intracellular bacteria that cause a wide variety of diseases throughout the globe, affecting the eye, lung, coronary arteries and female genital tract. Rather than by direct cellular toxicity, Chlamydia infection generally causes pathology by inducing fibrosis and scarring that is largely mediated by host inflammation. While a robust immune response is required for clearance of the infection, certain elements of that immune response may also damage infected tissue, leading to, in the case of female genital infection, disease sequelae such as pelvic inflammatory disease, infertility and ectopic pregnancy. It has become increasingly clear that the components of the immune system that destroy bacteria and those that cause pathology only partially overlap. In the ongoing quest for a vaccine that prevents Chlamydia-induced disease, it is important to target mechanisms that can achieve protective immunity while preventing mechanisms that damage tissue. This review focuses on mouse models of genital Chlamydia infection and synthesizes recent studies to generate a comprehensive model for immunity in the murine female genital tract, clarifying the respective contributions of various branches of innate and adaptive immunity to both host protection and pathogenic genital scarring.

C-reactive protein as a marker of persistent Chlamydia trachomatis infection is not associated with tubal factor infertility-an independent clinical validation study

STUDY QUESTION

Does C-reactive protein (CRP), as a marker of persisting low-grade inflammation, identify Chlamydia trachomatis IgG antibody test (CAT)-positive women who are at the highest risk for tubal factor infertility (TFI)?

SUMMARY ANSWER

No association was found between slightly elevated CRP (seCRP) levels and TFI in our CAT-positive patient population.

WHAT IS KNOWN ALREADY

In the fertility work-up, CAT is used to estimate the risk for TFI and to select high-risk patients for additional invasive diagnostic procedures (e.g. hysterosalpingography and laparoscopy). However, a high number of false positives exist among CAT-positive patients. In a previous study, it has been suggested that women with TFI may be identified more accurately when combining CAT with CRP, a marker for persistent low-grade inflammation.

STUDY DESIGN, SIZE, DURATION

Our original retrospective cohort consisted of 887 consecutive female patients who visited the fertility clinic of a tertiary care centre between 2007 and 2015. All CAT-positive women who underwent laparoscopy (as the reference test for evaluation of tubal function) and who had not undergone previous pelvic surgery were included in the study. CRP was determined in spare serum samples, and medical data was obtained by chart review.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 101 women (11.4%) were CAT-positive, and 64 of these 101 women (7.2%) met all inclusion criteria. CAT was performed with an ELISA. TFI was assessed by laparoscopy and strictly defined as extensive peri-adnexal adhesions and/or distal occlusion of at least one tube. In spare sera, CRP was performed with a high-sensitivity CRP ELISA, and CRP levels between 3 and 10 mg/L were defined as positive. Analyses were corrected for BMI, endometriosis and smoking.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no statistically significant association between seCRP level and TFI after adjusting for BMI, endometriosis and smoking (odds ratio 1.0; 95% CI 0.3–3.3; n = 64).

LIMITATIONS, REASONS FOR CAUTION

Our retrospective study had a small sample size due to a low CAT-positivity rate and a conservative clinical policy with regard to invasive diagnostic testing. Additionally, CRP levels were only measured once, while they may change throughout the menstrual cycle and in time.

WIDER IMPLICATIONS OF THE FINDINGS

Contrary to previous findings, our results show CRP is not suitable as a marker of persistent low-grade inflammation in CAT-positive women. Other inflammatory markers and immunogenetic host factors should be studied on their clinical validity and utility to improve non-invasive risk assessment for TFI in the fertility work-up.

STUDY FUNDING/COMPETING INTEREST(S)

This work was partially supported by the European EuroTrans-Bio Grant [Reference number 110012 ETB] and the Eurostars grant (E!9372). S.A.M., a full-time employee of Amsterdam University Medical Centres location VUMC (0.56 fte) and the Maastricht University Medical Center (0.44 fte), is the founder (2011) and CEO of TubaScan Ltd, a spin-off company, Dept. of Medical Microbiology and Infection Prevention, Amsterdam UMC, location VUmc, Amsterdam, the Netherlands. S.O. and E.F.v.E. at the time of conducting this research had a partial appointment at TubaScan Ltd.

Predictive Values of Serum Chlamydia trachomatis TroA and HtrA IgG Antibodies as Markers of Persistent Infection in the Detection of Pelvic Adhesions and Tubal Occlusion

Chlamydia trachomatis IgG antibody testing (CAT) has been used as a screening test for tubal factor infertility (TFI), but as the CAT is only a marker of a past exposure to C. trachomatis and not of late sequelae, the positive predictive value (PPV) of the test is low. The persistence of C. trachomatis in the upper genital tract has been suggested as one of the key mechanisms in the development of TFI. Serum antibodies against C. trachomatis TroA and HtrA, proteins expressed specifically during persistent infection, have been suggested as novel biomarkers for TFI diagnostics. We studied serum IgG antibody responses against C. trachomatis TroA, HtrA and MOMP in 79 subfertile women, of whom 28 had laparoscopically proven TFI. We confirmed that the accuracy of CAT in diagnosing TFI is low, whereas TroA IgG and HtrA IgG are more accurate tests in detecting tubal occlusion and pelvic adhesions. However, the sensitivity and negative predictive value (NPV) of TroA IgG and HtrA IgG are still too low to justify their use as a screening test in clinical practice. Individual immunogenetic profiles combined with TroA and HtrA antibody responses might identify women with the highest risk for developing late complications after C. trachomatis infection.

Prevalence and persistence of Chlamydia trachomatis-specific antibodies after occasional and recurrent infections

OBJECTIVES

Population-based Chlamydia trachomatis seroepidemiological studies help to identify trends in chlamydia infection. However, an improved understanding of the antibody response to infection is required when using serology to estimate cumulative incidence. Thus, the objectives of this longitudinal, retrospective, biobank-based study were to assess the appearance and persistence of C. trachomatis major outer membrane protein (MOMP)-specific serum IgG antibodies after infection and to evaluate the role of antibodies in providing protective immunity against recurrent infection.

METHODS

Data of notified C. trachomatis infections in Finland were obtained from the National Infectious Diseases Register. Serum samples were acquired from the Finnish Maternity Cohort. 411 women with single chlamydia infection and 62 women with recurrent infections, and for whom suitable paired serum samples were available, were included in the study. Antibody appearance, persistence after infection and the impact of recurrent infections were evaluated. IgG antibodies specific for MOMP were measured from serum using an ELISA method.

RESULTS

Anti-C. trachomatis MOMP-specific IgG antibodies were detected in 65.5% (269/411) of women within 3 months of notification of infection. In the absence of recurrent infection, seroprevalence declined to 34.5% (142/411) 3-10 years after the initial infection. The serum antibody levels at baseline correlated positively with seroprevalence at follow-up. Reinfection boosted the humoral immune response by increasing seroprevalence and the serum antibody levels. Seroprevalence within 3 months after first notification of infection was 65.5% (19/29) in women who were later diagnosed with recurrent infection, comparable with women with single notification of infection (65.5%, 269/411).

CONCLUSIONS

Approximately one-third of women with single notification of chlamydia infection remain seropositive 3-10 years after the initial infection. The concentration of antibodies remained stable during the follow-up. Recurrent infection boosted the humoral immune response, but reinfection occurred despite the presence of pre-existing antibodies.

Combining individual Chlamydia trachomatis IgG antibodies MOMP, TARP, CPAF, OMP2, and HSP60 for tubal factor infertility prediction

PROBLEM

Tubal factor infertility (TFI) is a severe complication of genital Chlamydia trachomatis infections. In fertility workup, chlamydia antibody test (CAT) is used to predict TFI. The predictive value for TFI of most commonly used CAT is moderate.

METHOD OF STUDY

A total of 183 infertile Dutch Caucasian women were included in this study. All underwent tubal patency testing (hysterosalpingography [HSG] or laparoscopy). Cases had TFI, and controls had no TFI (ie normal findings during HSG or laparoscopy). TFI was categorized based on severity (TFI 1-TFI 4). This study investigated the predictive values of major outer membrane protein (MOMP), translocated actin-recruiting phosphoprotein (TARP), chlamydial protease-like activity factor (CPAF), heat shock protein-60 (HSP60) and outer membrane protein 2 (OMP2) for TFI. A predictive algorithm is developed to detect TFI with a high certainty based on combinations of antibody titres. Serum was tested with the Mikrogen recomLine immunoblot and quantified with the recomScan. A greedy algorithm that explores all possible antibody combinations was developed.

RESULTS

Significant differences in the distributions of antigen titres between cases and controls were observed for CPAF (P = 0.0021), HSP60 (P = 0.0061), MOMP (P = 0.0497) and OMP2 (P = 0.0016). Single antibodies could not discriminate between TFI and controls by themselves. The greedy algorithm performs better in specificity, positive predictive value (PPV), accuracy and clinical utility index than the original Mikrogen algorithm. CPAF combined with HSP60 identified 18.2% of TFI cases with 100% certainty. Most of the TFI 4 cases were identified with cut-offs of CPAF > 10.7 or OMP2 > 3.9.

CONCLUSION

This proof-of-principle study shows that combinations of antibodies in serum are predictive for TFI. A commercially available test can be adapted to predict TFI with a 100% specificity.

Relation between Chlamydia trachomatis infection and pelvic inflammatory disease, ectopic pregnancy and tubal factor infertility in a Dutch cohort of women previously tested for chlamydia in a chlamydia screening trial

OBJECTIVES

A better understanding of Chlamydia trachomatis infection (chlamydia)-related sequelae can provide a framework for effective chlamydia control strategies. The objective of this study was to estimate risks and risk factors of pelvic inflammatory disease (PID), ectopic pregnancy and tubal factor infertility (TFI) with a follow-up time of up until 8 years in women previously tested for chlamydia in the Chlamydia Screening Implementation study (CSI) and participating in the Netherlands Chlamydia Cohort Study (NECCST).

METHODS

Women who participated in the CSI 2008-2011 (n=13 498) were invited in 2015-2016 for NECCST. Chlamydia positive was defined as a positive CSI-PCR test, positive chlamydia serology and/or self-reported infection (time dependent). Data on PID, ectopic pregnancy and TFI were collected by self-completed questionnaires. Incidence rates and HRs were compared between chlamydia-positive and chlamydia-negative women corrected for confounders.

RESULTS

Of 5704 women included, 29.5% (95% CI 28.3 to 30.7) were chlamydia positive. The incidence rate of PID was 1.8 per 1000 person-years (py) (1.6 to 2.2) overall, 4.4 per 1000 py (3.3 to 5.7) among chlamydia positives compared with 1.4 per 1000 py (1.1 to 1.7) for chlamydia negatives. For TFI, this was 0.4 per 1000 py (0.3 to 0.5) overall, 1.3 per 1000 py (0.8 to 2.1) and 0.2 per 1000 py (0.1 to 0.4) among chlamydia positives and negatives, respectively. And for ectopic pregnancy, this was 0.6 per 1000 py (0.5 to 0.8) overall, 0.8 per 1000 py (0.4 to 1.5) and 0.6 per 1000 py (0.4 to 0.8) for chlamydia negatives. Among chlamydia-positive women, the strongest risk factor for PID was symptomatic versus asymptomatic infection (adjusted HR 2.88, 1.4 to 4.5) and for TFI age <20 versus >24 years at first infection (HR 4.35, 1.1 to 16.8).

CONCLUSION

We found a considerably higher risk for PID and TFI in chlamydia-positive women, but the incidence for ectopic pregnancy was comparable between chlamydia-positive and chlamydia-negative women. Overall, the incidence rates of sequelae remained low.

TRIAL REGISTRATION

NTR-5597.

CPAF, HSP60 and MOMP antigens elicit pro-inflammatory cytokines production in the peripheral blood mononuclear cells from genital Chlamydia trachomatis-infected patients

BACKGROUND

Persistent inflammation caused by Chlamydia trachomatis in the female genital compartment represents one of the major causes of pelvic inflammatory disease (PID), ectopic pregnancy and infertility in females. Here, we examined the pro-inflammatory cytokine response following stimulation with three different types of C. trachomatis antigens, viz. chlamydial protease-like factor (CPAF), heat shock protein 60 (HSP60) and major outer membrane protein (MOMP).

METHODS

A total of 19 patients with genital C. trachomatis infection and 10 age-matched healthy controls were recruited for the study. Peripheral blood mononuclear cells (PBMCs) isolated from genital C. trachomatis-infected females were cultured in the presence of CPAF, HSP60 and MOMP antigens, and cytokines were measured by ELISA assay.

RESULTS

We reported that pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) were robustly secreted following antigenic exposure. Notably, CPAP and MOMP were more potent in triggering IL-1β, as compared to HSP60. Elevated levels of the proinflammatory cytokines were also noted in the samples infected with plasmid-bearing C. trachomatis as compared to those infected with plasmid-free strains.

CONCLUSIONS

Our study highlights distinct ability of chlamydial antigens in triggering pro-inflammatory response in the host immune cells.

Predicting tubal factor infertility by using markers of humoral and cell-mediated immune response against Chlamydia trachomatis

PROBLEM

The accuracy of Chlamydia trachomatis antibody test in predicting tubal factor infertility (TFI) is limited, and more accurate methods are needed. Cell-mediated immune response (CMI) is crucial in the resolution of pathogen, but it may play an important role in the pathogenesis of C trachomatis-associated tubal damage. We studied whether combining the markers of C trachomatis-induced CMI to humoral immune response improves the accuracy of serology in TFI prediction.

METHOD OF STUDY

Our prospective study consists of 258 subfertile women, of whom 22 (8.5%) had TFI. Women with other causes for subfertility served as a reference group. Serum C trachomatis major outer membrane protein (MOMP) and chlamydial heat-shock protein 60 (cHSP60) IgG antibodies were measured by ELISA. CMI was studied by lymphocyte proliferation assay in vitro.

RESULTS

Serological markers were more prevalent in women with TFI than in other subfertile women (40.9% vs 12.3% for MOMP IgG and 27.3% vs 10.2% for cHSP60 IgG). The best test combination for TFI was C. trachomatis MOMP and cHSP60 antibody with an accuracy of 90.3%, sensitivity of 22.7% and specificity of 96.6%. Positive post-test probability of this combination was 54.2%, and negative post-test probability was 12.4%. Adding of the markers of CMI did not significantly improve the accuracy of serology in TFI prediction.

CONCLUSION

The accuracy of TFI prediction increases when the combination of C trachomatis MOMP and cHSP60 antibody tests is used. C trachomatis-induced CMI was common in our study population, but the markers of CMI did not predict TFI.

Performance of the multitarget Mikrogen Chlamydia trachomatis IgG ELISA in the prediction of tubal factor infertility (TFI) in subfertile women: comparison with the Medac MOMP IgG ELISA plus

There is a need for more accurate Chlamydia trachomatis (CT) IgG antibody tests for tubal factor infertility (TFI) diagnostics. We evaluated the predictive value for TFI of Medac ELISA plus (MOMP) and multitarget Mikrogen ELISA (MOMP-CPAF-TARP). Based on Medac ELISA plus results, 183 subfertile women underwent either hysterosalpingography or laparoscopy to diagnose TFI. TFI was defined as extensive adhesions and/or distal occlusion of at least one tube. Women not fulfilling the definition of TFI served as controls. Serum was subsequently tested with Mikrogen ELISA and results were compared. 48 patients had TFI, 135 were controls. Mikrogen ELISA tested 125 patients positive/borderline of which 32% had TFI. Medac ELISA plus tested 77 patients positive/borderline of which 29.9% had TFI. Mikrogen tested 40 out of 48 TFI patients positive/borderline, Medac 23 out of 48. Kappa value was 0.34. PPV of Mikrogen ELISA and Medac ELISA plus were respectively 32% (95% CI 26%-39%) and 30% (95% CI 24%-37%), and NPV 86% (95% CI 81%-91%) and 76% (95% CI 70%-82%). Both tests were comparable in the prediction of TFI. However, Mikrogen ELISA had a higher NPV and might be more reliable in identifying patients without TFI. Kappa-value showed limited concordance between both tests.

Chlamydia trachomatis-induced cell-mediated and humoral immune response in women with unexplained infertility

PROBLEM

What is the role of past Chlamydia trachomatis infection in unexplained infertility?

METHOD OF STUDY

This is a prospective study of the impact of past C. trachomatis infection on pregnancy rates in 96 women with unexplained infertility. Both humoral and cell-mediated immune responses (CMI) against C. trachomatis were studied. Serum C. trachomatis IgG antibodies were analyzed using major outer membrane protein (MOMP) peptide-based ELISA. CMI was studied by lymphocyte proliferation (LP) assay in vitro. Data on given fertility treatment, time to pregnancy, and pregnancy outcome were collected.

RESULTS

Altogether, 11.5% of the 96 women had C. trachomatis IgG antibodies. LP response to C. trachomatis was positive in 62.9% women. The overall pregnancy rate or live birth rate did not differ by the presence of antichlamydial antibodies or CMI against C. trachomatis. Time to spontaneous pregnancy was longer among C. trachomatis sero-positive women than among sero-negative women (2.9 years vs 2.0 years, P = .03).

CONCLUSION

Past chlamydial infection does not play a major role in unexplained infertility. Women with unexplained infertility and positive immune response to C. trachomatis do not have reduced pregnancy rates, but time to spontaneous pregnancy is longer among C. trachomatis IgG sero-positive women than among sero-negative women.

Chlamydia trachomatis: the Persistent Pathogen

Chlamydia trachomatis is an obligate intracellular bacterium whose only natural host is humans. Although presenting as asymptomatic in most women, genital tract chlamydial infections are a leading cause of pelvic inflammatory disease, tubal factor infertility, and ectopic pregnancy. C. trachomatis has evolved successful mechanisms to avoid destruction by autophagy and the host immune system and persist within host epithelial cells. The intracellular form of this organism, the reticulate body, can enter into a persistent nonreplicative but viable state under unfavorable conditions. The infectious form of the organism, the elementary body, is again generated when the immune attack subsides. In its persistent form, C. trachomatis ceases to produce its major structural and membrane components, but synthesis of its 60-kDa heat shock protein (hsp60) is greatly upregulated and released from the cell. The immune response to hsp60, perhaps exacerbated by repeated cycles of productive infection and persistence, may promote damage to fallopian tube epithelial cells, scar formation, and tubal occlusion. The chlamydial and human hsp60 proteins are very similar, and hsp60 is one of the first proteins produced by newly formed embryos. Thus, the development of immunity to epitopes in the chlamydial hsp60 that are also present in the corresponding human hsp60 may increase susceptibility to pregnancy failure in infected women. Delineation of host factors that increase the likelihood that C. trachomatis will avoid immune destruction and survive within host epithelial cells and utilization of this knowledge to design individualized preventative and treatment protocols are needed to more effectively combat infections by this persistent pathogen.

Population-attributable fraction of tubal factor infertility associated with chlamydia

BACKGROUND

Chlamydia trachomatis infection is highly prevalent among young women in the United States. Prevention of long-term sequelae of infection, including tubal factor infertility, is a primary goal of chlamydia screening and treatment activities. However, the population-attributable fraction of tubal factor infertility associated with chlamydia is unclear, and optimal measures for assessing tubal factor infertility and prior chlamydia in epidemiological studies have not been established. Black women have increased rates of chlamydia and tubal factor infertility compared with White women but have been underrepresented in prior studies of the association of chlamydia and tubal factor infertility.

OBJECTIVES

The objectives of the study were to estimate the population-attributable fraction of tubal factor infertility associated with Chlamydia trachomatis infection by race (Black, non-Black) and assess how different definitions of Chlamydia trachomatis seropositivity and tubal factor infertility affect population-attributable fraction estimates.

STUDY DESIGN

We conducted a case-control study, enrolling infertile women attending infertility practices in Birmingham, AL, and Pittsburgh, PA, during October 2012 through June 2015. Tubal factor infertility case status was primarily defined by unilateral or bilateral fallopian tube occlusion (cases) or bilateral fallopian tube patency (controls) on hysterosalpingogram. Alternate tubal factor infertility definitions incorporated history suggestive of tubal damage or were based on laparoscopic evidence of tubal damage. We aimed to enroll all eligible women, with an expected ratio of 1 and 3 controls per case for Black and non-Black women, respectively. We assessed Chlamydia trachomatis seropositivity with a commercial assay and a more sensitive research assay; our primary measure of seropositivity was defined as positivity on either assay. We estimated Chlamydia trachomatis seropositivity and calculated Chlamydia trachomatis-tubal factor infertility odds ratios and population-attributable fraction, stratified by race.

RESULTS

We enrolled 107 Black women (47 cases, 60 controls) and 620 non-Black women (140 cases, 480 controls). Chlamydia trachomatis seropositivity by either assay was 81% (95% confidence interval, 73-89%) among Black and 31% (95% confidence interval, 28-35%) among non-Black participants (P < .001). Using the primary Chlamydia trachomatis seropositivity and tubal factor infertility definitions, no significant association was detected between chlamydia and tubal factor infertility among Blacks (odds ratio, 1.22, 95% confidence interval, 0.45-3.28) or non-Blacks (odds ratio, 1.41, 95% confidence interval, 0.95-2.09), and the estimated population-attributable fraction was 15% (95% confidence interval, -97% to 68%) among Blacks and 11% (95% confidence interval, -3% to 23%) among non-Blacks. Use of alternate serological measures and tubal factor infertility definitions had an impact on the magnitude of the chlamydia-tubal factor infertility association and resulted in a significant association among non-Blacks.

CONCLUSION

Low population-attributable fraction estimates suggest factors in addition to chlamydia contribute to tubal factor infertility in the study population. However, high background Chlamydia trachomatis seropositivity among controls, most striking among Black participants, could have obscured an association with tubal factor infertility and resulted in a population-attributable fraction that underestimates the true etiological role of chlamydia. Choice of chlamydia and tubal factor infertility definitions also has an impact on the odds ratio and population-attributable fraction estimates.

Biochemical and Genetic Analysis of the Chlamydia GroEL Chaperonins

Chaperonins are essential for cellular growth under normal and stressful conditions and consequently represent one of the most conserved and ancient protein classes. The paradigm Escherichia coli chaperonin, EcGroEL, and its cochaperonin, EcGroES, assist in the folding of proteins via an ATP-dependent mechanism. In addition to the presence of groEL and groES homologs, groEL paralogs are found in many bacteria, including pathogens, and have evolved poorly understood species-specific functions. Chlamydia spp., which are obligate intracellular bacteria, have reduced genomes that nonetheless contain three groEL genes, Chlamydia groEL (ChgroEL), ChgroEL2, and ChgroEL3 We hypothesized that ChGroEL is the bona fide chaperonin and that the paralogs perform novel Chlamydia-specific functions. To test our hypothesis, we investigated the biochemical properties of ChGroEL and its cochaperonin, ChGroES, and queried the in vivo essentiality of the three ChgroEL genes through targeted mutagenesis in Chlamydia trachomatis ChGroEL hydrolyzed ATP at a rate 25% of that of EcGroEL and bound with high affinity to ChGroES, and the ChGroEL-ChGroES complex could refold malate dehydrogenase (MDH). The chlamydial ChGroEL was selective for its cognate cochaperonin, ChGroES, while EcGroEL could function with both EcGroES and ChGroES. A P35T ChGroES mutant (ChGroESP35T) reduced ChGroEL-ChGroES interactions and MDH folding activities but was tolerated by EcGroEL. Both ChGroEL-ChGroES and EcGroEL-ChGroESP35T could complement an EcGroEL-EcGroES mutant. Finally, we successfully inactivated both paralogs but not ChgroEL, leading to minor growth defects in cell culture that were not exacerbated by heat stress. Collectively, our results support novel functions for the paralogs and solidify ChGroEL as a bona fide chaperonin that is biochemically distinct from EcGroEL.IMPORTANCEChlamydia is an important cause of human diseases, including pneumonia, sexually transmitted infections, and trachoma. The chlamydial chaperonin ChGroEL and chaperonin paralog ChGroEL2 have been associated with survival under stress conditions, and ChGroEL is linked with immunopathology elicited by chlamydial infections. However, their exact roles in bacterial survival and disease remain unclear. Our results further substantiate the hypotheses that ChGroEL is the primary chlamydial chaperonin and that the paralogs play specialized roles during infection. Furthermore, ChGroEL and the mitochondrial GroEL only functioned with their cochaperonin, in contrast to the promiscuous nature of GroEL from E. coli and Helicobacter pylori, which might indicate a divergent evolution of GroEL during the transition from a free-living organism to an obligate intracellular lifestyle.

Sero-epidemiological assessment of Chlamydia trachomatis infection and sub-fertility in Samoan women

Background

In our recent village-based cross-sectional study, the prevalence of nucleic acid amplification technique (NAAT) diagnosed Chlamydia trachomatis (CT) in sexually active Samoan women was very high (36 %), and test positivity was associated with sub-fertility. We conducted a serological and epidemiological analysis in these participants to identify if serological data can provide further insight into the potential contribution of CT to sub-fertility in this population.

Methods

Serological prediction of CT associated sub-fertility was conducted using a series of commercial tests. The correlation between fertility or sub-fertility, behavioral factors, and serologically predicted CT associated sub-fertility was determined.

Results

A positive antibody reaction against the Chlamydia Major Outer Membrane Protein (MOMP) was significantly associated with sub-fertility, with 50 % of infertile women being positive. Serum IgG and IgA antibodies against MOMP correlated with current infection measured by urine NAAT, suggesting longer term infections are common in this population. Chlamydia pneumoniae antibodies were frequently detected in this population (84 %), and unexpectedly, were significantly associated with sub-fertility.

Conclusions

The high prevalence of chlamydial infection and of positive chlamydial sub-fertility results suggests that CT is an important and frequent contributory factor to sub-fertility in this population.

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

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

Analysis of Factors Driving Incident and Ascending Infection and the Role of Serum Antibody in Chlamydia trachomatis Genital Tract Infection

BACKGROUND

Chlamydia trachomatis genital tract infection is a major cause of female reproductive morbidity. Risk factors for ascending infection are unknown, and the role for antibody in protection is not well established.

METHODS

We recruited 225 women from urban outpatient clinics and followed them for a median of 12 months. We performed a cross-sectional analysis of serum anti-chlamydial immunoglobulin G (IgG), behavioral factors, and microbiological factors associated with endometrial infection at enrollment, and a longitudinal analysis of factors associated with incident infection.

RESULTS

Oral contraceptives (adjusted relative risk [RR], 2.02 [95% confidence interval {CI}, 1.38-2.97]) and gonorrhea (adjusted RR, 1.66 [95% CI, 1.07-2.60]) were associated with endometrial infection. Gonorrhea (adjusted hazard ratio [HR], 3.09 [95% CI, 1.41-6.78]), cervical infection at enrollment (adjusted HR, 2.33 [95% CI, 1.07-5.11]), and exposure to uncircumcised partners (adjusted HR, 2.65 [95% CI, 1.21-5.82]) or infected partners (adjusted HR, 4.99 [95% CI, 2.66-9.39]) significantly increased the risk of incident infection. Seropositivity was associated with a reduced cervical burden (P < .05) but no differences in rates of ascending infection (adjusted RR, 1.24 [95% CI, .71-2.19]) or incident infection (adjusted HR, 0.94 [95% CI, .52-1.69]).

CONCLUSIONS

Serum anti-chlamydial IgG is not associated with a lowered rate of ascending or repeat infection. Identification of factors associated with ascending infection and increased risk of incident infection provide guidance for targeted screening of women at increased risk for sequelae.

Pelvic inflammatory disease: identifying research gaps--proceedings of a workshop sponsored by Department of Health and Human Services/National Institutes of Health/National Institute of Allergy and Infectious Diseases, November 3-4, 2011

In November 2011, the National Institutes of Health convened a workshop of basic researchers, epidemiologists, and clinical experts in pelvic inflammatory disease to identify research gaps hindering advances in diagnosis, treatment, and prevention. This article summarizes the presentations, discussions, and conclusions of this group and highlights significant controversies that reveal aspects of pelvic inflammatory disease research that would most greatly benefit from the application of newer molecular, immunologic, and radiologic techniques. Multiple limitations to performing new clinical trials exist; however, emerging data from ongoing clinical trials will add to the current body of knowledge regarding prevention and treatment strategies. In addition, use of established health care databases could serve as a valuable tool for performance of unbiased epidemiologic outcome studies.

Prevalence and diagnostic significance of specific IgA and anti-heat shock protein 60 Chlamydia trachomatis antibodies in subfertile women

The objective of the present study was to evaluate the clinical usefulness of the simultaneous measurement of three serological markers of chlamydial infection in women with tubal factor infertility (TFI) and spontaneous miscarriage. Serum was collected from 87 patients (33 with TFI and 54 with spontaneous miscarriage) and analyzed for the presence of IgG and IgA antibodies against Chlamydia trachomatis MOMP antigen (Dia.Pro) and IgG antibodies to chlamydial heat shock protein 60 (cHSP60) antigen (Medac). We determined a high degree (64.5 %) of seropositivity against chlamydial antigens in our study population. The prevalence of persistent chlamydial infection has tended to be higher in the group of patients with TFI (41.4 %) than in patients with spontaneous miscarriage (21.3 %). The serum level of IgA, as a marker of active infection, was statistically higher in the TFI group with persistent infection than in the corresponding spontaneous miscarriage group (p = 0.008), while the serum level of IgG showed no statistically significant differences compared with the spontaneous miscarriage group with persistent infection (p = 0.227). Also, using the receiver operating characteristic (ROC) curve, we found that the serum level of IgA has the ability to discriminate patients with persistent chlamydial infection between the TFI and miscarriage groups, with a sensitivity and specificity of 74.3 % and 71.4 %, respectively. To the best of our knowledge, the present study is the first study which, besides the already confirmed linkage between serologic evidence of persistent chlamydial infection and TFI, also confirmed associations between spontaneous miscarriage and serologic evidence of persistent chlamydial infection.

Laboratory diagnosis of persistent human chlamydial infection

Diagnostic assays for persistent chlamydial infection are much needed to conduct high-quality, large-scale studies investigating the persistent state in vivo, its disease associations and the response to therapy. Yet in most studies the distinction between acute and persistent infection is based on the interpretation of the data obtained by the assays developed to diagnose acute infections or on complex assays available for research only and/or difficult to establish for clinical use. Novel biomarkers for detection of persistent chlamydial infection are urgently needed. Chlamydial whole genome proteome arrays are now available and they can identify chlamydial antigens that are differentially expressed between acute infection and persistent infection. Utilizing these data will lead to the development of novel diagnostic assays. Carefully selected specimens from well-studied patient populations are clearly needed in the process of translating the proteomic data into assays useful for clinical practice. Before such antigens are identified and validated assays become available, we face a challenge of deciding whether the persistent infection truly induced appearance of the proposed marker or do we just base our diagnosis of persistent infection on the presence of the suggested markers. Consequently, we must bear this in mind when interpreting the available data.

The IL-6 response to Chlamydia from primary reproductive epithelial cells is highly variable and may be involved in differential susceptibility to the immunopathological consequences of chlamydial infection

BACKGROUND

Chlamydia trachomatis infection results in reproductive damage in some women. The process and factors involved in this immunopathology are not well understood. This study aimed to investigate the role of primary human cellular responses to chlamydial stress response proteases and chlamydial infection to further identify the immune processes involved in serious disease sequelae.

RESULTS

Laboratory cell cultures and primary human reproductive epithelial cultures produced IL-6 in response to chlamydial stress response proteases (CtHtrA and CtTsp), UV inactivated Chlamydia, and live Chlamydia. The magnitude of the IL-6 response varied considerably (up to 1000 pg ml(-1)) across different primary human reproductive cultures. Thus different levels of IL-6 production by reproductive epithelia may be a determinant in disease outcome. Interestingly, co-culture models with either THP-1 cells or autologous primary human PBMC generally resulted in increased levels of IL-6, except in the case of live Chlamydia where the level of IL-6 was decreased compared to the epithelial cell culture only, suggesting this pathway may be able to be modulated by live Chlamydia. PBMC responses to the stress response proteases (CtTsp and CtHtrA) did not significantly vary for the different participant cohorts. Therefore, these proteases may possess conserved innate PAMPs. MAP kinases appeared to be involved in this IL-6 induction from human cells. Finally, we also demonstrated that IL-6 was induced by these proteins and Chlamydia from mouse primary reproductive cell cultures (BALB/C mice) and mouse laboratory cell models.

CONCLUSIONS

We have demonstrated that IL-6 may be a key factor for the chlamydial disease outcome in humans, given that primary human reproductive epithelial cell culture showed considerable variation in IL-6 response to Chlamydia or chlamydial proteins, and that the presence of live Chlamydia (but not UV killed) during co-culture resulted in a reduced IL-6 response suggesting this response may be moderated by the presence of the organism.

Effect of IL12A and IL12B polymorphisms on the risk of Chlamydia trachomatis-induced tubal factor infertility and disease severity

BACKGROUND

Interleukin-12 (IL-12) and related cytokines induce activation and differentiation of T cells. Our aim was to investigate the associations between genetic differences in IL-12-family cytokines and the pathogenesis of chlamydial disease.

METHODS

The final study population consisted of 100 women with Chlamydia trachomatis-induced tubal factor infertility (TFI) and 125 pregnant women as controls. Three single nucleotide polymorphisms (SNPs) of IL12A and seven SNPs of IL12B genes were determined from isolated DNA using the Sequenom system with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry.

RESULTS

We found that the IL12B SNP rs3212227 was associated with both susceptibility and severity of TFI. The minor allele C was rare and only one CC homozygote was found among the controls. AC heterozygotes were more common among TFI cases than among controls (P = 0.009) and were associated with increased risk of TFI [odds ratios (OR) = 2.44, 95% confidence intervals (CI) = 1.23-4.87]. Carrying the minor allele C was also associated with disease severity (P for trend = 0.008) and moderate (OR = 2.51, 95% CI = 1.06-5.95) and severe tubal damage (OR = 2.73, 95% CI = 1.15-6.52).

CONCLUSIONS

The results suggest that variation in the IL12B gene partly explains inter-individual differences in disease susceptibility and severity.

Hospital-diagnosed late sequelae after female Chlamydia trachomatis infections in 1990-2006 in Turku, Finland

BACKGROUND

Rather little is known about the late sequelae of previously detected female Chlamydia infections.

METHODS

The late sequelae of previous female Chlamydia infections detected during a 15-year period in a south-western Finnish university hospital were surveyed. Hospital records of women with positive laboratory diagnoses of Chlamydia trachomatis as a sign of genital infection were collected from the years 1990-2006 and subsequently linked to known or suspected in-hospital-treated late Chlamydia complications.

RESULTS

The annual number of late complications has increased in proportion to the increasing trend of detected Chlamydia cases. 239 late complications of the total of 4,920 previously detected Chlamydia-positive infections were observed. The most frequent in-hospital-treated complications were disturbances in early pregnancy (n = 72) and low abdominal pain (n = 67). The others were 45 genital tract or pelvic infections, 34 cases of tubal or unknown infertility and 21 complications of late pregnancy and delivery.

CONCLUSION

The late sequelae of Chlamydia infections need increasing attention in hospitals.

Chlamydia trachomatis infections of the female genital tract: state of the art

Chlamydia trachomatis (CT) is the most common bacterial cause of sexually transmitted infections. CT infections are strongly associated with risk-taking behavior. Recommendations for testing have been implemented in many countries. The effectiveness of the screening programs has been questioned since chlamydia rates have increased. However, the complication rates including pelvic inflammatory disease, tubal factor infertility, and tubal pregnancy have been decreasing, which is good news. The complication rates associated with CT infection have clearly been over-estimated. Genetic predisposition and host immune response play important roles in the pathogenesis of long-term complications. CT plays a co-factor role in the development of cervical neoplasia caused by high-risk human papillomavirus (HPV) types. The evidence linking CT and other adverse pregnancy outcomes is weak. The current nucleic acid amplification tests perform well. A new genetic variant of CT was discovered in Sweden but has only rarely been detected elsewhere. Single-dose azithromycin remains effective against CT. Secondary prevention by screening is still the most important intervention to limit the adverse effects of CT on reproductive health.

Variants in toll-like receptor 1 and 4 genes are associated with Chlamydia trachomatis among women with pelvic inflammatory disease

BACKGROUND

Toll-like receptors (TLRs) are involved in the innate immune response. We examined whether TLR variants are associated with Chlamydia trachomatis infection among women with pelvic inflammatory disease (PID).

METHODS

We tested whether 18 tagging single nucleotide polymorphisms (tagSNPs) assayed in 4 TLR genes (TLR1, TLR2, TLR4, TLR6) and 2 adaptor molecules (TIRAP, MyD88) were associated with C. trachomatis among 205 African American women with clinically suspected PID from the PID Evaluation and Clinical Health Study. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). An empirical P value of <.004 was considered significant.

RESULTS

Women with PID who carried the TLR4 rs1927911 CC genotype had significantly increased odds of C. trachomatis (OR, 3.7; 95% CI, 1.6-8.8; P = .002). The TLR1 rs5743618TT genotype was also associated with C. trachomatis (OR, 2.8; 95% CI, 1.3-6.2; P = .008).

CONCLUSIONS

Among African American women with PID, variants in the TLR1 and TLR4 genes, which may increase signaling, were associated with increased C. trachomatis infection.

Identification of antigen-specific antibody responses associated with upper genital tract pathology in mice infected with Chlamydia muridarum

Urogenital infection with Chlamydia trachomatis in some women can lead to upper genital tract pathologies, such as hydrosalpinx, potentially affecting fertility. In the current study, 27 of 40 mice intravaginally infected with Chlamydia muridarum developed visible hydrosalpinges in the oviduct while the remaining 13 did not, although all infected mice displayed similar infection time courses. Antisera from the 40 mice recognized 130 out of 257 C. muridarum proteins as antigens and 17 as immunodominant antigens. Importantly, the 27 mice with hydrosalpinges preferentially recognized two C. muridarum proteins (TC0582 and TC0912, designated pathology-associated antigens) while the 13 mice with no hydrosalpinx preferentially recognized 10 proteins (TC0047, TC0117, TC0190, TC0197, TC0257, TC0279, TC0326, TC0630, TC0689, and TC0816, designated nonpathology antigens). The preferential recognition was validated by absorption and independently confirmed in Western blots. The C. trachomatis homolog of TC0912 is encoded by a highly polymorphic gene that is associated with ocular pathogenesis. A fragment of TC0912 was found to improve the differentiation of hydrosalpinx from nonhydrosalpinx mice. TC0582 is a highly conserved ATP synthase, and it may contribute to chlamydial pathogenesis via mechanisms similar to those hypothesized for the highly conserved HSP60. Thus, we have identified chlamydial antigens and epitopes that are associated with either susceptibility or resistance to upper genital tract pathology, which will help us to further understand chlamydial pathogenesis and to develop anti-Chlamydia subunit vaccines.

Chlamydia trachomatis and Mycoplasma genitalium plasma antibodies in relation to epithelial ovarian tumors

Objective. To assess associations of Chlamydia trachomatis and Mycoplasma genitalium antibodies with epithelial ovarian tumors. Methods. Plasma samples from 291 women, undergoing surgery due to suspected ovarian pathology, were analyzed with respect to C. trachomatis IgG and IgA, chlamydial Heat Shock Protein 60-1 (cHSP60-1) IgG and M. genitalium IgG antibodies. Women with borderline tumors (n = 12), ovarian carcinoma (n = 45), or other pelvic malignancies (n = 11) were matched to four healthy controls each. Results. Overall, there were no associations of antibodies with EOC. However, chlamydial HSP60-1 IgG antibodies were associated with type II ovarian cancer (P = .002) in women with plasma samples obtained >1 year prior to diagnosis (n = 7). M. genitalium IgG antibodies were associated with borderline ovarian tumors (P = .01). Conclusion. Chlamydial HSP60-1 IgG and M. genitalium IgG antibodies are in this study associated with epithelial ovarian tumors in some subsets, which support the hypothesis linking upper-genital tract infections and ovarian tumor development.

Genome-wide identification of Chlamydia trachomatis antigens associated with tubal factor infertility

OBJECTIVE

To identify Chlamydia trachomatis antigens that can be used to differentially diagnose tubal factor infertility in comparison with previously reported heat shock protein 60.

DESIGN

In vitro study.

SETTING

Academic medical center.

PATIENT(S)

Infertile women with and without tubal pathology diagnosed laparoscopically.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Antibody responses to C. trachomatis in infertile women with or without tubal pathologies using a C. trachomatis genome-wide proteome array.

RESULT(S)

Comparison of the antibody profiles revealed 30 C. trachomatis antigens that were preferentially recognized in women with tubal factor infertility, with a detection sensitivity and specificity of 80.6% and 56.5%, respectively, 10 of which showed 100% specificity. A combination of CT443 and CT381 antigens yielded the highest detection sensitivity (67.7%) while maintaining 100% specificity.

CONCLUSION(S)

These findings have demonstrated that antibodies to CT443 and CT381, when used in combination, have higher sensitivity and specificity in predicting tubal factor infertility than other indicators for tubal factor infertility, such as heat shock protein 60 antibodies (35.5%, 100%) or hysterosalpingogram (65%, 83%). Using a panel of C. trachomatis antigens to serologically diagnose tubal factor infertility can save the patients from undertaking expensive and invasive procedures for determining tubal pathology and choosing treatment plans.

Management of Chlamydia trachomatis genital tract infection: screening and treatment challenges

Chlamydia trachomatis is a prevalent sexually transmitted infection that can lead to serious reproductive morbidity. Management and control of C. trachomatis is a challenge, largely due to its asymptomatic nature and our incomplete understanding of its natural history. Although chlamydia screening programs have been implemented worldwide, several countries have observed increasing rates of reported chlamydia cases. We reviewed the literature relating to the long-term complications of C. trachomatis, as well as screening strategies, treatment, and prevention strategies for reducing chlamydia in the population. Articles from 1950-2010 were identified through a Medline search using the keyword "Chlamydia trachomatis" combined with "screening", "pelvic inflammatory disease", "endometritis", "salpingitis", "infertility", "ectopic pregnancy", "urethritis", "epididymitis", "proctitis", "prostatitis", "reinfection", "cost-effectiveness", "treatment", "vaccines", or "prevention". Progression of C. trachomatis varies, and recurrent infections are common. Currently, there is limited evidence on the effectiveness of chlamydia screening. Higher quality studies are needed to determine the efficacy of more frequent screening, on a broader range of sequelae, including infertility and ectopic pregnancy, in addition to pelvic inflammatory disease. Studies should focus on delineating the natural history of recurrent infections, paying particular attention to treatment failures. Furthermore, alternatives to screening, such as vaccines, should continue to be explored.

Immunopathogenic consequences of Chlamydia trachomatis 60 kDa heat shock protein expression in the female reproductive tract

Chlamydia trachomatis is an obligate intracellular bacterium that infects chiefly urogenital and ocular epithelial cells. In some infected women the microorganism migrates to the upper reproductive tract resulting in a chronic, but asymptomatic, infection. The immune response to this infection, production of interferon-gamma and pro-inflammatory cytokines, results in interruption of chlamydial intracellular replication. However, the Chlamydia remains viable and enters into a persistent state. In this form, most chlamydial genes are inactive. An exception is the gene coding for the 60 kDa heat shock protein (hsp60), which is synthesized in increased amounts and is released into the extracellular milieu. The chronic release of chlamydial hsp60 induces a local pro-inflammatory immune response in fallopian tube epithelia and results in scar formation and tubal occlusion. In addition, long-term exposure of the maternal immune system to the chlamydial hsp60 eventually results in the release of tolerance and generation of an immune response that recognizes regions of the chlamydial hsp60 that are also present in the human hsp60. Production of cross-reacting antibodies and cell-mediated immunity to the human hsp60 is detrimental to subsequent pregnancy outcome and may also possibly increase susceptibility to atherosclerosis, autoimmune disorders, or malignancies.

Chlamydia pneumoniae infection and risk for lung cancer

BACKGROUND

We evaluated the relationship of Chlamydia pneumoniae infection with prospective lung cancer risk using traditional serologic markers [microimmunoflourescence (MIF) IgG and IgA antibodies] and Chlamydia heat shock protein-60 (CHSP-60) antibodies, a marker for chronic chlamydial infection.

METHODS

We conducted a nested case-control study (593 lung cancers and 671 controls) within the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (N = 77,464). Controls were matched to cases by age, sex, randomization year, follow-up time, and smoking (pack-years of smoking, time since quitting). We assessed C. pneumoniae seropositivity and endpoint antibody titers (IgG and IgA against C. pneumoniae elementary bodies and IgG against CHSP-60).

RESULTS

C. pneumoniae seropositivity by microimmunoflourescence IgG or IgA antibodies was not associated with lung cancer [odds ratio of 0.88 and 95% confidence interval (95% CI) of 0.69-1.13 for IgG; odds ratio of 0.98 and 95% CI of 0.75-1.27 for IgA]. In contrast, individuals seropositive for CHSP-60 IgG antibodies had significantly increased lung cancer risk (odds ratio, 1.30; 95% CI, 1.02-1.67), and risk increased with increasing antibody titers (P trend = 0.006). CHSP-60-related risk did not differ significantly by lung cancer histology, follow-up time, or smoking. CHSP-60 seropositivity was associated with increased risk 2 to 5 years before lung cancer diagnosis (odds ratio, 1.77; 95% CI, 1.16-2.71; P trend = 0.006), thus arguing against reverse causality.

CONCLUSIONS

CHSP-60 seropositivity and elevated antibody titers were associated with significantly increased risk for subsequent lung cancer, supporting an etiologic role for C. pneumoniae infection in lung carcinogenesis.

IMPACT

Our results highlight the potential for lung cancer risk reduction through treatments targeted toward C. pneumoniae infections and chronic pulmonary inflammation.

Characterization of humoral immune responses to chlamydial HSP60, CPAF, and CT795 in inflammatory and severe trachoma

PURPOSE

Chlamydia trachomatis (Ct) remains the leading global cause of preventable blindness. There are limited data on humoral immune responses in trachoma. Evaluating these responses is important for understanding host-pathogen interactions and informing vaccine design. Antibodies to chlamydial heat shock protein 60 (cHSP60) have been associated with infertility and trachomatous scarring. Other proteins, including chlamydial protease-associated factor (CPAF) and a hypothetical protein unique to the family Chlamydiaceae, CT795, elicit strong immune responses in urogenital infections, but their role in trachomatous disease is unknown.

METHODS

This study was conducted to expand on previous cHSP60 findings and evaluate the association of CPAF and CT795 antibodies with ocular Ct infection and disease. Clinical trachoma grading was performed, and conjunctival samples were obtained from individuals with trachomatous trichiasis (TT; one or more inturned eyelashes) or inflammatory trachoma without trichiasis and control subjects without disease, all of whom resided in trachoma-endemic regions of Nepal. Ct infection was determined using commercial PCR. IgG and IgA tear antibodies against cHSP60, CT795, and CPAF fusion proteins were measured by quantitative ELISA.

RESULTS

Significantly higher IgG antibody levels were found against cHSP60, CPAF, and CT795 in the inflammatory cases compared with levels in the controls (P < 0.005 for all three). Ct infection was independently associated with IgG antibodies against all three immunogens in the inflammatory cases but not in the controls (P = 0.025, P = 0.03 and P = 0.017, respectively). Only IgG antibodies against CPAF were significantly elevated among the TT cases (P = 0.013).

CONCLUSIONS

Among individuals with trachoma, IgG antibody responses to CPAF are likely to be both a marker and risk factor for inflammatory trachoma and severe trachomatous disease.

Epidemiology of Chlamydia trachomatis infection in women and the cost-effectiveness of screening

BACKGROUND

The majority of Chlamydia trachomatis infections in women are asymptomatic, but may give rise to pelvic inflammatory disease (PID) and tubal infertility. Screening programmes aim at reducing morbidity in individuals by early detection and treatment, and at decreasing the overall prevalence of infection in the population. A number of modelling studies have tried to calculate the threshold prevalence of chlamydia lower genital tract infection above which screening becomes cost-effective. There is considerable debate over the exact complication rates after chlamydia infections, and more precise estimates of PID and tubal infertility are needed, for instance to be inserted in economic models.

METHODS

With reference to key studies and systematic reviews, an overview is provided focusing on the epidemiology of chlamydia infection and the risk-estimates of its late complications.

RESULTS

In the literature, the generally assumed risk of developing PID after lower genital tract chlamydia infection varies considerably, and is up to 30%. For developing tubal infertility after PID the risks are 10-20%. This implies that the risk of test-positive women of developing tubal infertility would range between 0.1 and 6%. We included chlamydia IgG antibody testing in a model and estimated a risk of tubal infertility up to 4.6%.

CONCLUSION

The risk of developing late complications after chlamydia lower genital tract infection appears low. High quality RCTs dealing with the transition from cervicitis to infertility are needed to broaden the evidence. In screening programmes, chlamydia antibody testing, as an intermediate marker for potential adverse sequelae, might enable more precise estimates.

The role of Chlamydia trachomatis infection in male infertility

To study the association between plasma antibodies to Chlamydia trachomatis and male infertility, 90 men from infertile couples attending a University Hospital IVF clinic for IVF/intracytoplasmic sperm injection, and 190 healthy blood donors as control subjects were studied for IgG and IgA antibodies to C. trachomatis, and for the men from infertile couples seminal fluid analysis was performed according to the World Health Organization criteria. The prevalence of plasma IgG antibodies to C. trachomatis was higher among men from infertile couples than control men, and men with chlamydial antibodies had lower sperm counts than those without.

Chlamydia trachomatis-specific heat shock proteins 60 antibodies can serve as prognostic marker in secondary infertile women

BACKGROUND

The magnitude of reproductive morbidity associated with sexually transmitted Chlamydia trachomatis infection is enormous. A predictive serological test for upper genital tract infection would be a desirable diagnostic tool as C. trachomatis infection may lead to various immunopathological sequelae such as infertility, or ectopic pregnancy.

MATERIALS AND METHODS

Female patients (n = 198) attending gynecology outpatient department of Safdarjung hospital were enrolled for the study and clinically characterized into four groups on the basis of their symptoms; discharge, chronic cervicitis, primary and secondary infertility. Serological detection of C. trachomatis was done by ELISA using specific peptide sequences of major outer membrane protein (MOMP), Chlamydia heat shock protein (cHSP60 and 10).

RESULTS

Significant high seropositivity to chlamydial anti-cHSP60 antibodies were detected in patients with secondary infertility. A significant percent of chlamydial reinfection was observed in patients having secondary infertility (82.6%; p < 0.01) and chronic cervicitis (64.28%; p < 0.05). Considering IgG MOMP ELISA as a test standard, anti-cHSP60 antibodies showed higher sensitivity (90.91%) and specificity (89.47%) than cHSP10 ELISA (75.6% and 73.87%) in the secondary infertile group. Further anti-cHSP60 antibodies' detection had a sensitivity of 67.33% and a specificity of 90.67% in secondary infertile women when compared with DFA and PCR.

CONCLUSIONS

Our data suggest that detection of anti-cHSP60 antibodies would help in early prognosis of immunopathological sequelae in C. trachomatis-infected women and thereby in instituting appropriate therapy for controlling C. trachomatis infection at an early stage.

In infertile women, cells from Chlamydia trachomatis infected sites release higher levels of interferon-gamma, interleukin-10 and tumor necrosis factor-alpha upon heat-shock-protein stimulation than fertile women

BACKGROUND

The magnitude of reproductive morbidity associated with sexually transmitted Chlamydia trachomatis infection is enormous. Association of antibodies to chlamydial heat shock proteins (cHSP) 60 and 10 with various disease sequelae such as infertility or ectopic pregnancy has been reported. Cell-mediated immunity is essential in resolution and in protection to Chlamydia as well as is involved in the immunopathogenesis of chlamydial diseases. To date only peripheral cell mediated immune responses have been evaluated for cHSP60. These studies suggest cHSPs as important factors involved in immunopathological condition associated with infection. Hence study of specific cytokine responses of mononuclear cells from the infectious site to cHSP60 and cHSP10 may elucidate their actual role in the cause of immunopathogenesis and the disease outcome.

METHODS

Female patients (n = 368) attending the gynecology out patient department of Safdarjung hospital, New Delhi were enrolled for the study and were clinically characterized into two groups; chlamydia positive fertile women (n = 63) and chlamydia positive infertile women (n = 70). Uninfected healthy women with no infertility problem were enrolled as controls (n = 39). cHSP60 and cHSP10 specific cytokine responses (Interferon (IFN)-gamma, Interleukin (IL)-10, Tumor Necrosis Factor (TNF)-alpha, IL-13 and IL-4) were assessed by ELISA in stimulated cervical mononuclear cell supernatants.

RESULTS

cHSP60 and cHSP10 stimulation results in significant increase in IFN-gamma (P = 0.006 and P = 0.04 respectively) and IL-10 levels (P = 0.04) in infertile group as compared to fertile group. A significant cHSP60 specific increase in TNF-alpha levels (P = 0.0008) was observed in infertile group as compared to fertile group. cHSP60 and cHSP10 specific IFN-gamma and IL-10 levels were significantly correlated (P < 0.0001, r = 0.54 and P = 0.004, r = 0.33 respectively) in infertile group.

CONCLUSION

Our results suggest that exposure to chlamydial heat shock proteins (cHSP60 and cHSP10) could significantly affect mucosal immune function by increasing the release of IFN-gamma, IL-10 and TNF-alpha by cervical mononuclear cells.

Circulating antibodies to a conserved epitope of the Chlamydia trachomatis 60-kDa heat shock protein is associated with decreased spontaneous fertility rate in ectopic pregnant women treated by salpingectomy

PROBLEM

This prospective study was aimed to evaluate whether non-invasive clinical and serologic parameters of tubal disease are predictive for subsequent spontaneous conception and pregnancy outcome after first episode of ectopic pregnancy (EP).

METHOD OF STUDY

Overall, 144 women aged <35 years were enrolled. Outcome of subsequent spontaneous conception was analyzed after 3 years and compared with clinical parameters and antibody responses to Chlamydia trachomatis and epitopes of the 60-kDa chlamydial heat shock protein (CHSP-60).

RESULTS

Antibody response to a conserved epitope of CHSP-60 (amino acids, aa 260-277) was independently correlated with both decreased spontaneous conception and term delivery rates (adjusted odds ratios, OR: 3.6 and 5.4, respectively).

CONCLUSION

Presence of circulating antibodies to a conserved epitope of the CHSP-60 is associated with a lower spontaneous conception rate, and increased likelihood of adverse pregnancy outcome in women treated by salpingectomy for first episode of EP.

Chlamydia trachomatis infection: host immune responses and potential vaccines

Chlamydia trachomatis causes genital tract infections that affect men, women, and children on a global scale. This review focuses on innate and adaptive immune responses in the female reproductive tract (FRT) to genital tract infections with C. trachomatis. It covers C. trachomatis infections and highlights our current knowledge of genital tract infections, serovar distribution, infectious load, and clinical manifestations of these infections in women. The unique features of the immune system of the FRT will be discussed and will include a review of our current knowledge of innate and adaptive immunity to chlamydial infections at this mucosal site. The use of animal models to study the pathogenesis of, and immunity to, Chlamydia infection of the female genital tract will also be discussed and a review of recent immunization and challenge experiments in the murine model of chlamydial FRT infection will be presented.

High titers of Chlamydia trachomatis antibodies in Brazilian women with tubal occlusion or previous ectopic pregnancy

OBJECTIVE

To evaluate serum chlamydia antibody titers (CATs) in tubal occlusion or previous ectopic pregnancy and the associated risk factors.

METHODS

The study population consisted of 55 women wih tubal damage and 55 parous women. CAT was measured using the whole-cell inclusion immunofluorescence test and cervical chlamydial DNA detected by PCR. Odds ratios were calculated to assess variables associated with C. trachomatis infection.

RESULTS

The prevalence of chlamydial antibodies and antibody titers in women with tubal occlusion or previous ectopic pregnancy was significantly higher (P < .01) than in parous women. Stepwise logistic regression analysis showed that chlamydia IgG antibodies were associated with tubal damage and with a larger number of lifetime sexual partners.

CONCLUSIONS

Chlamydia antibody titers were associated with tubal occlusion, prior ectopic pregnancy, and with sexual behavior, suggesting that a chlamydia infection was the major contributor to the tubal damage in these women.

Chlamydial Hsp60-2 is iron responsive in Chlamydia trachomatis serovar E-infected human endometrial epithelial cells in vitro

Chlamydial 60-kDa heat shock proteins (cHsp60s) are known to play a prominent role in the immunopathogenesis of disease. It is also known that several stress-inducing growth conditions, such as heat, iron deprivation, or exposure to gamma interferon, result in the development of persistent chlamydial forms that often exhibit enhanced expression of cHsp60. We have shown previously that the expression of cHsp60 is greatly enhanced in Chlamydia trachomatis serovar E propagated in an iron-deficient medium. The objective of this work was to determine which single cHsp60 or combination of the three cHsp60 homologs encoded by this organism responds to iron limitation. Using monospecific polyclonal peptide antisera that recognize only cHsp60-1, cHsp60-2, or cHsp60-3, we found that expression of cHsp60-2 is responsive to iron deprivation. Overall, our studies suggest that the expression of cHsp60 homologs differs among the mechanisms currently known to induce persistence.