Pathogenesis of Chlamydia induced pelvic inflammatory disease

Effect of the purinergic receptor P2X7 on Chlamydia infection in cervical epithelial cells and vaginally infected mice

Ligation of the purinergic receptor, P2X7R, with its agonist ATP has been previously shown to inhibit intracellular infection by chlamydiae and mycobacteria in macrophages. The effect of P2X7R on chlamydial infection had never been investigated in the preferred target cells of chlamydiae, cervical epithelial cells, nor in vaginally infected mice. In this study, we show that treatment of epithelial cells with P2X7R agonists inhibits partially Chlamydia infection in epithelial cells. Chelation of ATP with magnesium or pretreatment with a P2X7R antagonist blocks the inhibitory effects of ATP. Similarly to previous results obtained with macrophages, ATP-mediated inhibition of infection in epithelial cells requires activation of host-cell phospholipase D. Vaginal infection was also more efficient in P2X7R-deficient mice, which also displayed a higher level of acute inflammation in the endocervix, oviduct, and mesosalpingeal tissues than in infected wild-type mice. However, secretion of IL-1beta, which requires P2X7R ligation during infection by other pathogens, was decreased mildly and only at short times of infection. Taken together, these results suggest that P2X7R affects Chlamydia infection by directly inhibiting infection in epithelial cells, rather than through the ability of P2X7R to modulate IL-1beta secretion.

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.

Host-Cell Survival and Death During Chlamydia Infection

Different Chlamydia trachomatis strains are responsible for prevalent bacterial sexually-transmitted disease and represent the leading cause of preventable blindness worldwide. Factors that predispose individuals to disease and mechanisms by which chlamydiae cause inflammation and tissue damage remain unclear. Results from recent studies indicate that prolonged survival and subsequent death of infected cells and their effect on immune effector cells during chlamydial infection may be important in determining the outcome. Survival of infected cells is favored at early times of infection through inhibition of the mitochondrial pathway of apoptosis. Death at later times displays features of both apoptosis and necrosis, but pro-apoptotic caspases are not involved. Most studies on chlamydial modulation of host-cell death until now have been performed in cell lines. The consequences for pathogenesis and the immune response will require animal models of chlamydial infection, preferably mice with targeted deletions of genes that play a role in cell survival and death.

IL-10 polymorphism and cell-mediated immune response to Chlamydia trachomatis

Chlamydia trachomatis infection induces an inflammatory response that is crucial in resolving acute infection but may also play a key role in the pathogenesis of C trachomatis associated infertility. The immune response is linked to cytokine secretion pattern which is influenced by the host genetic background. To study a relationship between interleukin-10 (IL-10) promoter -1082 polymorphism and cell-mediated immune response during C trachomatis infection in vitro, lymphocyte proliferation and cytokine (IL-10, IFN-gamma, TNF-alpha, IL-2, IL-4 and IL-5) secretion were analysed in subjects with different IL-10 genotypes. Enhanced IL-10 secretion and reduced antigen-specific lymphocyte proliferative and IFN-gamma responses were found in subjects with IL-10 -1082 GG genotype when compared to those with -1082 AA genotype. CD14+ monocytes were main source of IL-10 indicating that these cells are important regulators of the antigen-specific cell-mediated responses during active C trachomatis infection. We conclude that impaired cell-mediated response to C trachomatis is associated with IL-10 genotype in subjects with high IL-10 producing capacity. A comparison of immune markers between subjects with a history of noncomplicated and complicated infection is needed to further understand the confounding factors associated with the development of C trachomatis associated sequelae.

Women presenting with lower abdominal pain: A missed opportunity for chlamydia screening?

INTRODUCTION

Many young women presenting with lower abdominal pain are referred to general surgeons with possible appendicitis. For some of these patients there will be a gynaecological cause for their pain. There has been a steady increase in the incidence of Chlamydia infections and pelvic inflammatory disease (PID) among the general population. Therefore, are general surgeons considering this as a diagnosis for lower abdominal pain in women?

METHODS

One hundred and ninety three women who had been admitted with lower abdominal pain to a single hospital between 1999 and 2001 were identified using computerised records and the notes were examined. One hundred and eighty six women were included in the audit. Investigations and treatments instigated for these patients were then carefully recorded.

RESULTS

Seventy-four patients underwent appendicectomy, of which 59 were histologically confirmed. Eighty-nine patients (47.8%) of admissions had no final diagnosis and were not screened for Chlamydia trachomatis. Sexual history was recorded in only 51% of admissions. Vaginal swabs were sent in only 7.3% of admissions.

CONCLUSION

Current guidelines for Chlamydia trachomatis screening produced by the Chief Medical Officer (CMO) include screening in women presenting with lower abdominal pain as well as those with post-coital or intermenstrual bleeding. Most women who present with classical symptoms of PID will present to gynaecological specialities for further management. However, a significant number of women presenting atypically will be referred to surgeons to exclude gastrointestinal causes for their lower abdominal pain. These women could and probably should be screened for Chlamydia trachomatis.

Delivery of Chlamydia vaccines

The plethora of ocular, genital and respiratory diseases of Chlamydia, including nongonococcal urethritis, cervicitis pelvic inflammatory disease, ectopic pregnancy, tubal factor infertility, conjunctivitis, blinding trachoma and interstitial pneumonia, and chronic diseases that may include atherosclerosis, multiple sclerosis, adult onset asthma and Alzheimer's disease, still pose a considerable public health challenge to many nations. Although antibiotics are effective against Chlamydia when effectively diagnosed, asymptomatic infections are rampart, making clinical presentation of complications often the first evidence of an infection. Consequently, the current medical opinion is that an effective prophylactic vaccine would constitute the best approach to protect the human population from the most severe consequences of these infections. Clinical and experimental studies have demonstration that Chlamydia immunity in animals and humans is mediated by T cells and a complementary antibody response, and the completion of the genome sequencing of several isolates of Chlamydia is broadening our knowledge of the immunogenic antigens with potential vaccine value. Thus, major advances have been made in defining the essential elements of a potentially effective subunit vaccine design and parameters for evaluation. However, the challenge to develop effective delivery systems and human compatible adjuvants that would boost the immune response to achieve long-lasting protective immunity remains an elusive objective in chlamydial vaccine research. In response to evolving molecular and cellular technologies and novel vaccinology approaches, considerable progress is being made in the construction of novel delivery systems, such as DNA and plasmid expression systems, viral vectors, living and nonliving bacterial delivery systems, the use of chemical adjuvants, lipoprotein constructs and the codelivery of vaccines and specific immuno-modulatory biological agonists targeting receptors for chemokines, Toll-like receptors, and costimulatory molecules. The application of these novel delivery strategies to Chlamydia vaccine design could culminate in timely achievement of an efficacious vaccine.

Intersections between adverse pregnancy outcomes

Reproductive failure in a variety of forms, whether it be infertility, miscarriage, pre-eclampsia, prematurity or intrauterine growth restriction, may aggregate within individuals. This observation, although rarely studied, suggests that single pathophysiologies may be associated with a variety of reproductive morbidities. In this review, hyperimmune responsiveness to pregnancy is provided as one example of a process leading to a multitude of adverse impacts on healthy childbearing. Further research on reproductive failure as a spectrum is warranted.

The consequences for human reproduction of a robust inflammatory response

Innate and adaptive immune responsiveness is variable within the population. Since robust immune reactions are critical to the survival of humans, the existence of immune variability in the population suggests the existence of competing, alternative phenotypes. Although women with powerful immune responsiveness may be more likely to survive to reproduce, their reproductive experiences may be less successful than women who are not as responsive. Normal pregnancy elicits a maternal inflammatory reaction. This can be understood on the basis of maternal-fetal conflict theory: inflammation is a component of the maternal attempt to limit excessive fetal demands. However, an overly aggressive inflammatory reaction has been shown to relate to a variety of adverse reproductive outcomes. Reviewed here are several examples, including the fallopian tube damage that results from pelvic inflammatory disease, the upregulated inflammatory response among women who develop preeclampsia, an association between immune hyperresponsiveness and premature delivery, and the relationship between autoimmune diseases and multiple adverse pregnancy outcomes. The hypothesis that immune hyperresponsiveness limits reproductive capacity suggests many avenues for research.

Immunology of Chlamydia infection: implications for a Chlamydia trachomatis vaccine

Sexually transmitted Chlamydia trachomatis infections are a serious public-health problem. With more than 90 million new cases occurring annually, C. trachomatis is the most common cause of bacterial sexually transmitted disease worldwide. Recent progress in elucidating the immunobiology of Chlamydia muridarum infection of mice has helped to guide the interpretation of immunological findings in studies of human C. trachomatis infection and has led to the development of a common model of immunity. In this review, we describe our current understanding of the immune response to infection with Chlamydia spp. and how this information is improving the prospects for development of a vaccine against infection with C. trachomatis.

Prevalence of Chlamydia trachomatis in Asymptomatic Brazilian Military Conscripts

BACKGROUND

Few data are available on the prevalence and risk factors for Chlamydia trachomatis infection among young men in Brazil.

OBJECTIVES

To assess prevalence and risk factors for C. trachomatis infection in male military conscripts.

METHODS

In 2000, 627 young men recruited for military service in Goiania, Goias, Brazil, were enrolled in this cross-sectional study. Participants completed a demographic and sexual risk behavior questionnaire, and urine samples were screened for C. trachomatis by polymerase chain reaction.

RESULTS

The prevalence of chlamydial infection among asymptomatic conscripts was 5.0% (95% confidence interval [CI], 3.3-7.3). In multivariate analysis, failure to use condoms (odds ratio [OR](adjusted) 5.3; 95% confidence interval [CI], 1.2-23.4; P = 0.028) and having more than 2 sexual partners in the last 2 months (OR(adjusted) 2.6; 95% CI, 1.1-6.9; P = 0.049) were significantly associated with positivity for C. trachomatis.

CONCLUSIONS

A substantial number of asymptomatic young male military recruits were infected with C. trachomatis, and risk factors for this infection were related to sexual behavior. Further research is required to determine if routine screening may be considered as a strategy to reduce prevalence among this population.

The diagnosis ofTrichomonas vaginalis in liquid-based Pap tests: Correlation with PCR

The conventional Papanicolaou smear (CPS) is not considered accurate for the diagnosis of Trichomonas vaginalis (T. vaginalis), and women noted to carry the organism on CPS are recommended to undergo confirmatory testing. Liquid-based preparations have been shown to facilitate the diagnosis of squamous lesions and may also facilitate the diagnosis of T. vaginalis. We used polymerase chain reaction (PCR) to investigate the accuracy of the diagnosis of T. vaginalis by the liquid-based Pap test (LBP). LBP with the diagnosis of T. vaginalis from a 12-mo period were identified. Residual samples from these cases were subjected to PCR for T. vaginalis as were the residual samples of a control group of 195 LBP (including 103 inflammatory LBP and 69 cases of atypical squamous cells) in which T. vaginalis was not diagnosed cytologically. PCR confirmed the presence of T. vaginalis in 50 of 51 (98%) LBP and identified 2 additional cases. Morphologic identification of T. vaginalis on LBP is highly accurate and should not require confirmatory testing.

Characterization of Chlamydia trachomatis omp1 genotypes detected in eye swab samples from remote Australian communities

Chlamydia trachomatis conjunctival samples collected over a 6-month period from individuals with clinical signs of trachoma and located in remote communities in the Australian Northern Territory were differentially characterized according to serovar and variants. The rationale was to gain an understanding of the epidemiology of an apparent increased prevalence of acute trachoma in areas thought to be less conducive to this disease. Characterization was performed through sequencing of a region of the omp1 gene spanning the four variable domains and encoding the major outer membrane protein. Nucleotide and deduced amino acid sequences were genotyped by using a BLAST similarity search and were examined by phylogenetic analyses to illustrate evolutionary relationships between the clinical and GenBank reference strains. The predominant genotype identified corresponded to that of serovar C (87.1%), followed by the genotype corresponding to serovar Ba (12.9%). All nucleotide and amino acid sequences exhibited minor levels of variation with respect to GenBank reference sequences. The omp1 nucleotide sequences of the clinical samples best aligned with those of the conjunctival C. trachomatis reference strains C/TW-3/OT and Ba/Apache-2. All clinical samples (of serovar C) exhibited four or five nucleotide changes compared with C/TW-3/OT, while all serovar Ba samples had one or two nucleotide differences from Ba/Apache-2. Phylogenetic analyses revealed close relationships between these Northern Territory chlamydial samples and the respective reference strains, although the high proportion of sequence variants suggests an evolutionarily distinct C. trachomatis population causing eye infections in Australia. Given that such genotypic information has gone unreported, these findings provide knowledge and a foundation for trachoma-associated C. trachomatis variants circulating in the Northern Territory.

Associations among human leukocyte antigen (HLA) class II DQ variants, bacterial sexually transmitted diseases, endometritis, and fertility among women with clinical pelvic inflammatory disease

BACKGROUND

We investigated associations between HLA class II DQ alleles, chlamydial and gonococcal cervicitis, endometritis, and infertility among women with pelvic inflammatory disease (PID).

METHODS

Ninety-two women with clinical signs and symptoms of mild-to-moderate PID, enrolled in the PEACH Study, were evaluated. For all HLA class II DQ alleles with a prevalence of 10% or greater in the population, we assessed demographics, cervical infections, endometrial pathology, and fertility outcomes.

RESULTS

Chlamydial cervicitis, gonococcal cervicitis, endometritis, and infertility were all more common among women carrying the DQA *0301 allele after adjustment for race. Endometritis and infertility were somewhat less common (or pregnancy more common) among women carrying the DQA *0501 and DQB *0402 alleles.

CONCLUSION

Among women with signs and symptoms of PID, carriage of the DQA *0301, DQA *0501, and DQB *0402 alleles altered the occurrence of lower genital tract infection, upper genital tract inflammation, and infertility.

Pelvic inflammatory disease and sepsis

Pelvic inflammatory disease affects approximately 1 million women per year in the United States alone and has a variety of causative organisms. Because the diagnosis of PID is based on clinical judgment, health care providers need to be guided by the CDC recommendations for diagnosing and treating PID. Because presenting symptoms are often vague, the health care provider should assess female patients for risky behaviors that may lead to PID and should use screening data when making clinical judgments and differential diagnoses. Whenever possible, female patients with PID should be treated as outpatients. If diagnosis and treatment are not performed in a timely manner, PID may cause sepsis, septic shock, and even death. Even if they survive, as many as 15% to 20% of these women experience long-term sequelae of PID, such as ectopic pregnancy, tubo-ovarian abscess, infertility, dyspareunia, and chronic pelvic pain. The best treatments for PID are interventions that lead to prevention and early detection. The critical care nurse has an important role in recognizing the variables that may lead to PID-related sepsis and in encouraging health-seeking and health-maintenance behaviors among women with these diagnoses.

Chlamydia vaccines: strategies and status

The ultimate goal of current chlamydial vaccine efforts is to utilise either conventional or modern vaccinology approaches to produce a suitable immunisation regimen capable of inducing a sterilising, long-lived heterotypic protective immunity at mucosal sites of infection to curb the severe morbidity and worldwide prevalence of chlamydial infections. This lofty goal poses tremendous challenges that include the need to clearly define the relevant effectors mediating immunity, the antigens responsible for inducing these effectors, the anti-chlamydial action(s) of effectors, and establishment of the most effective method of vaccine delivery. Tackling these challenges is further compounded by the biological complexity of chlamydia, the existence of multiple serovariants, the capacity to induce both protective and deleterious immune effectors, and the occurrence of asymptomatic and persistent infections. Thus, novel molecular, immunological and genetic approaches are urgently needed to extend the frontiers of current knowledge, and develop new paradigms to guide the production of an effective vaccine regimen. Progress made in the last 15 years has culminated in various paradigm shifts in the approaches to designing chlamydial vaccines. The dawn of the current immunological paradigm for antichlamydial vaccine design has its antecedence in the recognition that chlamydial immunity is mediated primarily by a T helper type1 (Th1) response, requiring the induction and recruitment of specific T cells into the mucosal microenvironment. Additionally, the ancillary role of humoral immune response in complementing the Th1-driven protective immunity, through ensuring adequate memory and optimal Th1 response during a reinfection, has been recognised. With continued progress in chlamydial genomics and proteomics, select chlamydial proteins, including structural, membrane and secretory proteins, are being targeted as potential subunit vaccine candidates. However, the development of an effective adjuvant, delivery vehicle or system for a potential subunit vaccine is still an elusive objective in these efforts. Promising delivery vehicles include DNA and virus vectors, bacterial ghosts and dendritic cells. Finally, a vaccine still represents the best approach to protect the greatest number of people against the ocular, pulmonary and genital diseases caused by chlamydial infections. Therefore, considering the urgency and the enormity of these challenges, a partially protective vaccine preventing certain severe sequelae would constitute an acceptable short-term goal to control Chlamydia. However, more research efforts and support are needed to achieve the worthy goal of protecting a significant number of the world's population from the devastating consequences of chlamydial invasion of the human mucosal epithelia.

Screening and genotyping of genital Chlamydia trachomatis in urine specimens from male and female clients of youth-health centers in Stockholm County

BACKGROUND

The current study was conducted in the context of the current increase in cases of Chlamydia trachomatis infections, the development of new diagnostic strategies, and an outreach to community-based youth center screening sites.

GOAL

The goal was to define the prevalence of genital C trachomatis infection among clients of youth-health clinics and to evaluate the feasibility of implementing genotyping as a tool for epidemiologic studies with use of urine specimens.

STUDY DESIGN

This was a prospective pilot study at two community-based youth-health clinics for teenagers and adolescents. Enrollment followed a high school educational program and public advertising campaign on the common occurrence of nonsymptomatic or only mildly symptomatic chlamydial infection among sexually active young people. Voluntary, confidential, free screening of first-void urine was provided, and the samples were tested by polymerase chain reaction (PCR). Demographic and behavioral data were obtained. Positive samples were differentiated into genovars by genotyping with restriction fragment length polymorphism analysis of the PCR-amplified omp1 gene.

RESULTS

The prevalence of nonsymptomatic or mildly symptomatic chlamydial infection was 6.0% among women and 9.3% among men. A significant increase in the risk of infection was associated with a history of sexually transmitted disease (STD) (P < 0.01). There was no statistical risk correlating with partner change during the past year, infrequent or inconsistent condom use during the past year, present use of contraceptive pills, smoking habits, or recent alcohol consumption. Genotype E was most common (60%) among both sexes. Genotypes F and K were second most prevalent for men (20%), and genotype D was second most prevalent for women (15%). Genotype K or F was found in 23% of cases.

CONCLUSION

Screening programs targeting sexually active adolescents attending youth-health clinics are important for detection of C trachomatis. Genotyping might become an efficient tool in epidemiologic studies. The impact of educational school- and community-based programs on STD among young people needs further evaluation.

Biology of trichomonosis

Trichomonas vaginalis is emerging as a major pathogen of men and women and is associated with serious health consequences. Advances in diagnosis and treatment are presented. The complexity of trichomonad pathogenesis is illustrated in the interaction of this parasite with human cells, tissues and the immune system. It is now becoming evident that the interaction of trichomonads with the host is frequently modulated by environmental signals. The molecular biology of trichomonads is still in its infancy, but analysis of genes, genomic structure and transcriptional mechanisms suggest that trichomonads combine both prokaryotic and eukaryotic features. Evidence for the ancient divergence of trichomonads from other eukaryotic lineages is discussed.