Determination of chlamydial load and immune parameters in asymptomatic, symptomatic and infertile women

Sex and Gender Differences in Bacterial Infections

There is a growing awareness of the importance of sex and gender in medicine and research. Women typically have stronger immune responses to self and foreign antigens than men, resulting in sex-based differences in autoimmunity and infectious diseases. In both animals and humans, males are generally more susceptible than females to bacterial infections. At the same time, gender differences in health-seeking behavior, quality of health care, and adherence to treatment recommendations have been reported. This review explores our current understanding of differences between males and females in bacterial diseases. We describe how genetic, immunological, hormonal, and anatomical factors interact to influence sex-based differences in pathophysiology, epidemiology, clinical presentation, disease severity, and prognosis, and how gender roles affect the behavior of patients and providers in the health care system.

Chlamydia trachomatis bacterial load, estimated by Cq values, in urogenital samples from men and women visiting the general practice, hospital or STI clinic

Background

The bacterial load of Chlamydia trachomatis (CT) is assumed to play a role in transmission and sequelae. We assessed urogenital CT cycle quantification (Cq) values, as an indicator for CT load, of men and women diagnosed by general practitioners (GPs), hospital physicians and the STI clinic.

Methods

Urogenital CT-positive samples (n = 2,055 vaginal swabs, n = 77 cervical swabs, n = 1,519 urine samples and n = 19 urethral swabs) diagnosed by GPs, hospital physicians and the STI clinic from the Maastricht Medical Microbiology Laboratory were included (2012–2016). The outcome measure ‘urogenital Cq values’ was used as an inversely proportional measure for CT load. Among all patients, multivariate linear regression analyses were used to assess primary determinants for mean urogenital Cq values, stratified by sex. Additional clinical determinants were assessed among STI clinic patients.

Results

In men, mean urogenital Cq values were similar between GPs, hospital physicians and the STI clinic (32.7 and 33.5 vs. 32.7; p>0.05). Women visiting the GP had lower urogenital Cq values than women visiting the STI clinic (30.2 vs. 30.9; p = <0.001). Women visiting the hospital had higher urogenital Cq values than women visiting the STI clinic (32.4 vs. 30.9; p = <0.001). Among STI clinic women, urogenital Cq values were lower in women with concurrent anorectal CT and in rectally untested women compared to anorectal CT-negative women (30.7 and 30.6 vs. 33.9; p = <0.001).

Conclusion

Men visiting different STI care providers had similar urogenital Cq values, which could be an indicator for similar CT loads. The lower Cq values of women visiting the GP compared to women visiting the STI clinic could be an indicator for higher CT loads and likely higher transmission potential. Notably, urogenital Cq values of STI clinic women were much lower (>3 Cq) when STI clinic women also had anorectal CT. This finding could indicate higher urogenital CT loads and likely higher chances of transmission and sequelae.

Male genital tract immune response against Chlamydia trachomatis infection

Chlamydia trachomatis is the most commonly reported agent of sexually transmitted bacterial infections worldwide. This pathogen frequently leads to persistent, long-term, subclinical infections, which in turn may cause severe pathology in susceptible hosts. This is in part due to the strategies that Chlamydia trachomatis uses to survive within epithelial cells and to evade the host immune response, such as subverting intracellular trafficking, interfering signaling pathways and preventing apoptosis. Innate immune receptors such as toll-like receptors expressed on epithelial and immune cells in the genital tract mediate the recognition of chlamydial molecular patterns. After bacterial recognition, a subset of pro-inflammatory cytokines and chemokines are continuously released by epithelial cells. The innate immune response is followed by the initiation of the adaptive response against Chlamydia trachomatis, which in turn may result in T helper 1-mediated protection or in T helper 2-mediated immunopathology. Understanding the molecular mechanisms developed by Chlamydia trachomatis to avoid killing and host immune response would be crucial for designing new therapeutic approaches and developing protective vaccines. In this review, we focus on chlamydial survival strategies and the elicited immune responses in male genital tract infections.

Insight into infection-mediated prostate damage: Contrasting patterns of C-reactive protein and prostate-specific antigen levels during infection

BACKGROUND

To investigate mechanisms underlying our previous observation of a large rise in serum prostate-specific antigen, a marker of prostate pathology, during both sexually transmitted and systemic infections, we measured serum high-sensitivity C-reactive protein (hsCRP), a marker of systemic inflammation, in our previous case-control study of young, male US military members and compared our findings to those for PSA.

METHODS

We measured hsCRP before and during infection for 299 chlamydia, 112 gonorrhea, and 59 non-chlamydial, non-gonococcal urethritis (NCNGU) cases; before and after infection for 55 infectious mononucleosis (IM) and 90 other systemic/non-genitourinary cases; and for 220-256 controls.

RESULTS

Only gonorrhea cases were significantly more likely to have a large hsCRP rise (≥1.40 mg/L or ≥239%) during infection than controls (P < 0.01). However, gonorrhea, IM, and other systemic/non-genitourinary cases were more likely to have a rise of any magnitude up to one year post-diagnosis than controls (p = 0.038-0.077).

CONCLUSIONS

These findings, which differ from those for PSA, suggest distinct mechanisms of elevation for hsCRP and PSA, and support both direct (eg, prostate infection) and indirect (eg, systemic inflammation-mediated prostate cell damage) mechanisms for PSA elevation. Future studies should explore our PSA findings further for their relevance to both prostate cancer screening and risk.

Development and evaluation of an enzyme-linked immunosorbent assay for the detection of antibodies to a common urogenital derivative of Chlamydia trachomatis plasmid-encoded PGP3

BACKGROUND

Urogenital infection with Chlamydia trachomatis is the most commonly diagnosed sexually transmitted infection in the developed world. Accurate measurement and therefore understanding the seroprevalence of urogenital C. trachomatis infections requires a rigorously optimised and validated ELISA. Previous ELISAs based on the C. trachomatis plasmid-encoded protein, PGP3, have been described but lack standardisation and critical controls or use a less common PGP3 as the capture antigen.

METHODOLOGY/PRINCIPAL FINDINGS

A sensitive and specific indirect ELISA was developed based on recombinant PGP3 derived from a urogenital strain of C. trachomatis, serovar E (pSW2), using a rigorous validation protocol. Serum samples were collected from 166 genitourinary medicine (GUM) clinic patients diagnosed as positive or negative for urogenital C. trachomatis infection by nucleic acid amplification testing (NAATs). Overall sensitivity and specificity compared to NAATs was 68.18% and 98.0%, respectively. Sensitivities for female and male samples were 71.93% and 64.15%, respectively. Comparison of samples from these patients diagnosed positive for C. trachomatis by NAAT and patients diagnosed negative by NAAT revealed statistical significance (p≤0.0001).

CONCLUSIONS

We have developed and validated a sensitive and specific ELISA to detect anti-PGP3 antibodies as an indicator of past and current infection to C. trachomatis using PGP3 from a common urogenital strain. It is anticipated that this assay will be used for seroepidemiological analysis of urogenital C. trachomatis in populations.

Immunity, immunopathology, and human vaccine development against sexually transmitted Chlamydia trachomatis

This review examines the immunity, immunopathology, and contemporary problems of vaccine development against sexually transmitted Chlamydia trachomatis. Despite improved surveillance and treatment initiatives, the incidence of C. trachomatis infection has increased dramatically over the past 30 years in both the developed and developing world. Studies in animal models have shown that protective immunity to C. trachomatis is largely mediated by Th1 T cells producing IFN-γ which is needed to prevent dissemination of infection. Similar protection appears to develop in humans but in contrast to mice, immunity in humans may take years to develop. Animal studies and evidence from human infection indicate that immunity to C. trachomatis is accompanied by significant pathology in the upper genital tract. Although no credible evidence is currently available to indicate that autoimmunity plays a role, nevertheless, this underscores the necessity to design vaccines strictly based on chlamydial-specific antigens and to avoid those displaying even minimal sequence homologies with host molecules. Current advances in C. trachomatis vaccine development as well as alternatives for designing new vaccines for this disease are discussed. A novel approach for chlamydia vaccine development, based on targeting endogenous dendritic cells, is described.

Differential Expression of mRNA Encoding Cytokines and Chemokines in the Reproductive Tract after Infection of Mice with Chlamydia trachomatis

Infection with Chlamydia trachomatis targets epithelial cells within the genital tract which respond by secreting chemokines and cytokines. Persistent inflammation can lead to fibrosis, tubal infertility and/or ectopic pregnancy; many infections are asymptomatic. Most studies have investigated the inflammatory response in the initial stages of infection, less is known about the later stages of infection, especially with a low, potentially asymptomatic, bacterial load. Our objective was to determine the inflammatory mediators involved in clearance of low-grade infection and the potential involvement in chronic inflammation. Six to eight week old C3H/HeJ mice were pretreated with 2.5 mg medroxyprogesterone acetate on day -10 and -3 before infection. Mice (n=3 for 28 d, n=3 for 35 d) were infected with 5 × 10² inclusion-forming units of C. trachomatis, serovar D; vaginal cultures were obtained weekly to monitor infection. Control mice (n=3 for 28 d, n=3 for 35 d) were sham infected. Mice were killed on day 28 (experiment 1) and day 35 (experiment 2) post-infection and vaginal tissue, uterine horns and oviducts collected for analysis of mRNAs encoding inflammatory cytokines and chemokines. Total RNA was isolated and a superarray analysis performed using mouse Cytokines and Chemokines PCR arrays (Qiagen, Valencia, CA). Statistical differences in gene expression were determined using a paired Students t-test. At 28 days after infection, the expression of mRNA encoding 6, 35 and 3 inflammatory genes differed from controls in vaginal, uterine and oviductal tissues, respectively (P<0.05). At 35 days after infection, the expression of mRNA encoding 16, 38 and 14 inflammatory genes differed from controls in vaginal, uterine and oviductal tissues, respectively (P<0.05). Understanding the mechanisms involved in the inflammatory response at later stages of infection should aid in the development of treatment options that minimize the development of asymptomatic, chronic inflammation-induced infertility.

Significant roles played by IL-10 in Chlamydia infections

Chlamydia species are obligate intracellular parasites which cause usually asymptomatic genital tract infections and also are associated with several complications. Previous studies demonstrated that immune responses to Chlamydia species are different and the diseases will be limited to some cases. Additionally, Chlamydia species are able to modulate immune responses via regulating expression of some immune system molecules including cytokines. IL-10, as the main anti-inflammatory cytokine, plays important roles in the induction of immune-tolerance against self-antigen and also immune-homeostasis after microbe elimination. Furthermore, it has been documented that ectopic expression of IL-10 is associated with several chronic infectious diseases. Therefore, it can be hypothesized that changes in the regulation of this cytokine can be associated with infection with several species of Chlamydia and their associated complications. This review collected the recent information regarding the association and relationship of IL-10 with Chlamydia infections. Another aim of this review article is to address recent data regarding the association of genetic variations (polymorphisms) of IL-10 and Chlamydia infections.

The Epidemiology of Chlamydia trachomatis Organism Load During Genital Infection: A Systematic Review

BACKGROUND

The role of organism load in Chlamydia trachomatis infection is not well understood. We conducted a systematic review to investigate the epidemiology of C. trachomatis organism load in human genital chlamydia infection.

METHODS

Embase, PubMed, and Medline databases were searched for literature published through August 2014. English-language publications that quantified load in humans were eligible. Participant characteristics and laboratory data were extracted.

RESULTS

A total of 737 records were identified, and 29 publications involving 40 883 participants were included. In women, load was highest for cervical swabs and lowest for urine specimens. In men, load was highest for rectal swabs and similar for urethral swabs and urine specimens. Evidence of any association between load and age, serovar, risk of transmission, hormone levels, and concurrent sexually transmitted infections was inconsistent. Eight of 9 culture-based studies found an association between load and signs and symptoms, in contrast with only 3 of 8 nucleic acid amplification test (NAAT)-based studies (P = .03).

CONCLUSION

Chlamydia organism load varies by specimen type and site of sampling, and viable chlamydia organism load may be a more important indicator of severity of infection than total load measured by NAAT.

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.

Recent insights into microbial triggers of interleukin-10 production in the host and the impact on infectious disease pathogenesis

Since its initial description as a Th2-cytokine antagonistic to interferon-alpha and granulocyte-macrophage colony-stimulating factor, many studies have shown various anti-inflammatory actions of interleukin-10 (IL-10), and its role in infection as a key regulator of innate immunity. Studies have shown that IL-10 induced in response to microorganisms and their products plays a central role in shaping pathogenesis. IL-10 appears to function as both sword and shield in the response to varied groups of microorganisms in its capacity to mediate protective immunity against some organisms but increase susceptibility to other infections. The nature of IL-10 as a pleiotropic modulator of host responses to microorganisms is explained, in part, by its potent and varied effects on different immune effector cells which influence antimicrobial activity. A new understanding of how microorganisms trigger IL-10 responses is emerging, along with recent discoveries of how IL-10 produced during disease might be harnessed for better protective or therapeutic strategies. In this review, we summarize studies from the past 5 years that have reported the induction of IL-10 by different classes of pathogenic microorganisms, including protozoa, nematodes, fungi, viruses and bacteria and discuss the impact of this induction on the persistence and/or clearance of microorganisms in the host.

Molecular Approach by PCR is the Best Method to Detect the Presence of Chlamydia Trachomatis and to Define the True Agent of Ocular Bacterial Inflammation

Chlamydia trachomatis (Ct) is an atypical agent for acute, subclinical and chronic conjunctivitis in developed countries, as stated by the International League against Trachoma. In order to evaluate the presence of Ct, from a total of 3,520 patients visiting the consulting room of the Eye Clinic of G. d'Annunzio University of Chieti, Italy from 2006–2008, we enrolled 171 patients affected by occasional mild, moderate or severe conjunctivitis in a three-arm prospective open study, using traditional analysis such as Immune Fluorescent Assay and Enzyme–Linked Fluorescent Assay (IFA and ELFA) and molecular analysis with Polymerase Chain Reaction (PCR) procedure for Ct DNA research (Ct DNA). At the same time, microbiological culture was carried out for common germs and mycetes. These patients were analyzed at different subsequent times. In the first arm (Group A) of 82 patients with IFA and ELFA only 10 people (12.2%) resulted positive to Ct infection with both methods. The presence of Ct was never alone, but always overlapped with contaminants, like corynebacteria, staphylococci, streptococci and colonbacteria, randomly distributed, while no growth of mycetes was observed. Of these positive patients, only one 47-year-old female, suffering from a moderate form of ocular chlamydial infection, showed serological conversion against this infection; furthermore, this female had also been suffering from reactive arthritis for sometime. In the second arm (Group B) of 89 patients, we carried out PCR for Ct detection: 82 (94.25%) were found positive to Ct – DNA research, with common germ growth randomly associated, without sex or age prevalence, as in group A; no mycetes were found. The third arm (Group C) included 37 negative patients from Group A with severe or moderate chronic conjunctivitis, randomly recruited between relapsing cases, with the addition of the single previously positive seroconversion case, for a total of 38 patients, who were re-evaluated by PCR Ct-DNA analysis. All these patients, negative to IFA and ELFA, were positive to Ct-DNA analysis. These data indicate a higher rate of Ct infection in patients with severe or moderate chronic conjunctivitis, resistant to usual therapies even after eradication of common germs, thus showing the advantage of introducing this molecular technique of analysis in mild to severe chronic or recurrent conjunctivitis.

Chlamydial infection increases gonococcal colonization in a novel murine coinfection model

Genital tract infections caused by Neisseria gonorrhoeae and Chlamydia trachomatis serovars D to K occur at high incidence in many areas of the world. Despite high rates of coinfection with these pathogens, investigations of host-parasite interactions have focused on each pathogen individually. We describe here a coinfection model in which female BALB/c mice were first infected with the mouse Chlamydia species C. muridarum and then inoculated with N. gonorrhoeae following treatment with water-soluble 17β-estradiol to promote long-term gonococcal infection. Viable gonococci and chlamydiae were recovered for an average of 8 to 10 days, and diplococci and chlamydial inclusions were observed in lower genital tract tissue by immunohistochemical staining. Estradiol treatment reduced proinflammatory cytokine and chemokine levels in chlamydia-infected mice; however, coinfected mice had a higher percentage of vaginal neutrophils compared to mice infected with either pathogen alone. We detected no difference in pathogen-specific antibody levels due to coinfection. Interestingly, significantly more gonococci were recovered from coinfected mice compared to mice infected with N. gonorrhoeae alone. We found no evidence that C. muridarum increases gonococcal adherence to, or invasion of, immortalized murine epithelial cells. However, increased vaginal concentrations of inflammatory mediators macrophage inflammatory protein 2 and tumor necrosis factor alpha were detected in C. muridarum-infected mice prior to inoculation with N. gonorrhoeae concurrently with the downregulation of cathelicidin-related antimicrobial peptide and secretory leukocyte peptidase inhibitor genes. We conclude that female mice can be successfully infected with both C. muridarum and N. gonorrhoeae and that chlamydia-induced alterations in host innate responses may enhance gonococcal infection.