Vaccination to protect against infection of the female reproductive tract

Infection of the female genital tract can result in serious morbidities and mortalities from reproductive disability, pelvic inflammatory disease and cancer, to impacts on the fetus, such as infant blindness. While therapeutic agents are available, frequent testing and treatment is required to prevent the occurrence of the severe disease sequelae. Hence, sexually transmitted infections remain a major public health burden with ongoing social and economic barriers to prevention and treatment. Unfortunately, while there are two success stories in the development of vaccines to protect against HPV infection of the female reproductive tract, many serious infectious agents impacting on the female reproductive tract still have no vaccines available. Vaccination to prevent infection of the female reproductive tract is an inherently difficult target, with many impacting factors, such as appropriate vaccination strategies/mechanisms to induce a suitable protective response locally in the genital tract, variation in the local immune responses due to the hormonal cycle, selection of vaccine antigen(s) that confers effective protection against multiple variants of a single pathogen (e.g., the different serovars of Chlamydia trachomatis) and timing of the vaccine administration prior to infection exposure. Despite these difficulties, there are numerous ongoing efforts to develop effective vaccines against these infectious agents and it is likely that this important human health field will see further major developments in the next 5 years.     

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.     

Vaccination to protect against infection of the female reproductive tract

Infection of the female genital tract can result in serious morbidities and mortalities from reproductive disability, pelvic inflammatory disease and cancer, to impacts on the fetus, such as infant blindness. While therapeutic agents are available, frequent testing and treatment is required to prevent the occurrence of the severe disease sequelae. Hence, sexually transmitted infections remain a major public health burden with ongoing social and economic barriers to prevention and treatment. Unfortunately, while there are two success stories in the development of vaccines to protect against HPV infection of the female reproductive tract, many serious infectious agents impacting on the female reproductive tract still have no vaccines available. Vaccination to prevent infection of the female reproductive tract is an inherently difficult target, with many impacting factors, such as appropriate vaccination strategies/mechanisms to induce a suitable protective response locally in the genital tract, variation in the local immune responses due to the hormonal cycle, selection of vaccine antigen(s) that confers effective protection against multiple variants of a single pathogen (e.g., the different serovars of Chlamydia trachomatis) and timing of the vaccine administration prior to infection exposure. Despite these difficulties, there are numerous ongoing efforts to develop effective vaccines against these infectious agents and it is likely that this important human health field will see further major developments in the next 5 years.     

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.     

Evaluation of urogenitalChlamydia trachomatis infections by cell culture and the polymerase chain reaction using a closed system

Two hundred and fifty-four specimens from males and females consulting a clinic for sexually transmitted diseases were analyzed for genitalChlamydia trachomatis infection. Each clinical sample was tested by the cell culture technique and the polymerase chain reaction using a closed system. When the two test systems were compared, the overall sensitivity of the polymerase chain reaction was 96% and the specificity 94% when compared to the cell culture technique. By use of a closed system for DNA extraction and sample transfer for the polymerase chain reaction, contamination of the samples was minimized. The polymerase chain reaction detected a higher number ofChlamydia trachomatis infections among both symptomatic and asymptomatic females and males, and it also detectedChlamydia trachomatis at an earlier stage of infection when compared to cell culture. The polymerase chain reaction did not detectChlamydia trachomatis after sufficient antibiotic treatment of the chlamydial infections.     

Lack of utility of risk score and gynecological examination for screening for sexually transmitted infections in sexually active adolescents

Background  

Sexually transmitted infections constitute the main health risk among adolescents. In developing countries the diagnosis and treatment of cervical infections is based on the syndromic approach. In this study we estimated the prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae among female adolescents from a Health Sector of the city of Goiania, Brazil, and validated cervicitis diagnosis using World Health Organization/Ministry of Health risk score and gynecological examination.     

Efficacy of single-dose azithromycin versus doxycycline in the treatment of cervical infections caused byChlamydia trachomatis

The efficacy of single-dose azithromycin therapy in the treatment of cervicalChlamydia trachomatis infections was compared to that of a standard seven-day course of treatment with doxycycline. Cervical samples from 60 patients reacted positively in an enzyme immunoassay for detection ofChlamydia trachomatis. In 31 patientsChlamydia trachomatis was isolated from the sample taken before treatment. Fourteen of the 31 patients were treated with doxycycline and 17 with azithromycin. All cultures of samples taken one and four weeks after the start of therapy were negative. All 31 isolates showed a similar pattern of MICs for the seven antibiotics tested, including azithromycin and doxycycline. No differences were observed between isolates of different serovars. In samples from four patients chlamydial DNA could be detected by PCR one week after the start of the therapy and in two patients also after four weeks. No difference in microbiological parameters could be observed between the two treatment groups. It is concluded that single-dose azithromycin is as effective as a seven-day course of doxycycline in the therapy of cervicalChlamydia trachomatis infections.     

Genital Chlamydia trachomatis: Understanding the Roles of Innate and Adaptive Immunity in Vaccine Research

SUMMARY

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted disease worldwide, and despite significant advances in chlamydial research, a prophylactic vaccine has yet to be developed. This Gram-negative obligate intracellular bacterium, which often causes asymptomatic infection, may cause pelvic inflammatory disease (PID), ectopic pregnancies, scarring of the fallopian tubes, miscarriage, and infertility when left untreated. In the genital tract, Chlamydia trachomatis infects primarily epithelial cells and requires Th1 immunity for optimal clearance. This review first focuses on the immune cells important in a chlamydial infection. Second, we summarize the research and challenges associated with developing a chlamydial vaccine that elicits a protective Th1-mediated immune response without inducing adverse immunopathologies.     

Chlamydial infections and the quinolones

Some of the newer fluoroquinolones may be suitable agents for the treatment ofChlamydia trachomatis infections and non-gonococcal urethritis. To date, small studies with both ofloxacin and fleroxacin appear to achieve cure rates of 85–100% for urethritis and cervicitis due toChlamydia trachomatis. However, large well-designed clinical trials are required to determine the efficacy and acceptance of these and other fluoroquinolones in the treatment of patients with genital or respiratory syndromes due to chlamydiae or other bacterial pathogens causing infections with similar manifestations.     

Chlamydia trachomatis Infection in the Female Reproductive Tract of the Rat: Influence of Progesterone on Infectivity and Immune Response

As the most common cause of sexually transmitted disease in women, chlamydial infections can lead to pelvic inflammatory disease, infertility, and ectopic pregnancy. To better understand the role played by sex hormones in modulating the immune response of the genital tract to microbial infections, we have developed a rat model to study Chlamydia trachomatis infection. Inbred female Lewis rats were primed with progesterone and inoculated by intrauterine instillation of C. trachomatis (mouse pneumonitis strain MoPn) into each uterine horn. When infected animals were examined for the presence of chlamydial antigens 14 days postinfection, both the uterus and vagina were found to be positive compared to those of saline-treated animals, which did not show specific staining. The involvement of local and systemic immune systems following chlamydial infection was determined by analyzing major histocompatibility complex (MHC) class II expression in the reproductive tract and lymphocyte proliferation in response to mitogenic and chlamydia-specific stimulation of cells from the spleen and lymph nodes (LN) draining the reproductive tract. Enhanced proliferation was observed in LN following mitogenic but not antigenic (MOMP [major outer membrane protein]) stimulation. In contrast, spleen cell proliferation was lower in chlamydia-infected rats than in saline-treated controls. MHC class II expression, an indicator of inflammatory responses, was upregulated in the uterus, on glandular epithelial cells, and adjacent to glands in response to chlamydial infection. In other experiments, when rats were infected at estrus and diestrus without prior progesterone priming, chlamydial inclusions were not detected in either the uterus or vagina. However, enhanced lymphocyte proliferation was observed in response to mitogenic and MOMP stimulation in the reproductive tract-draining LN from estrous and diestrous animals. These findings indicate that under appropriate endocrine conditions, the rat uterus is susceptible to C. trachomatis infection and that immune responses to this pathogen can be detected locally and systemically. Further, they suggest that clearance of the infection from the reproductive tract involves immune cells from the LN draining the reproductive tract.

Chlamydia trachomatis is an obligate intracellular gram-negative bacteria that is known to infect the genital tract and ocular epithelium. Disease caused by this organism can range from acute self-limiting infection to chronic inflammatory conditions, which can result in pelvic inflammatory disease, infertility, and ectopic pregnancy (12). Chlamydial infection of the urogenital tract is currently the leading cause of sexually transmitted disease in adolescents and women in the United States and Europe (11). Despite the recognition of chlamydial infection as a major public health concern, immune responses to human chlamydial infection are not well understood. Both T-cell-mediated and humoral responses are known to be involved in resolution of chlamydial infection. However, protective immunity developed as a result of chlamydial infection is transient, and reinfections are common (12).Animal models to study chlamydial infections have been developed in the mouse, guinea pig, marmoset, and nonhuman primate (13, 15). In mice, for example, inoculations of chlamydiae via intravaginal and intrauterine routes are known to cause cervicitis or salpingitis, respectively (17, 18). In this species, intravaginal infection with human serovars of chlamydiae was dependent on pretreatment with progesterone (18). In the guinea pig, however, pretreatment with estradiol markedly enhanced the course of infection with guinea pig inclusion conjunctivitis (16). In all cases, endocrine balance at the time of exposure to chlamydiae appeared to play a crucial role for host susceptibility.Previous work from our laboratory has demonstrated that sex hormones regulate the mucosal immune response in the female reproductive tract. Using the rat as a model system, we and others have shown that stage of the estrous cycle and treatment with sex hormones, specifically estradiol and progesterone, influence both the afferent and efferent arms of the immune system (for a review see reference 19). For example, antigen presentation, immunoglobulin A (IgA) transport, immune cell traffic into the reproductive tract, and cytokine production in the uterus and vagina have been shown to be under hormonal control. The aims of the present study were (i) to determine if infection could be successfully established in rats following intrauterine exposure to chlamydiae with or without progesterone treatment and (ii) to determine if immune responses occur locally and at sites distal to the reproductive tract in response to chlamydial infection.     

Detection ofChlamydia trachomatis in clinical specimens by the polymerase chain reaction

Sequences derived from the endogenous plasmid ofChlamydia trachomatis and from the genes coding for ribosomal 16S RNA ofChlamydia psittaci were used as primers and oligonucleotide probes for detection of chlamydiae by the polymerase chain reaction. The endogenous plasmid primers generated specific amplified products of 517 bp with all knownChlamydia trachomatis serovars. No specific products ofChlamydia psittaci andChlamydia pneumoniae could be detected using these primers. With the rRNA primers specific amplified products of 208 bp were generated withChlamydia psittaci, Chlamydia trachomatis andChlamydia pneumoniae. No specific amplified products were detected with DNA isolated from a variety of microorganisms from the urogenital and the respiratory tract. Of 156 clinical specimens used for evaluation of the polymerase chain reaction, 26 were found to be positive forChlamydia trachomatis on culture. All 26 culture positive samples were also found to be positive forChalmydia trachomatis DNA by the polymerase chain reaction with both primer sets. Two culture negative samples were also found to be positive by this technique. The polymerase chain reaction thus seems to be a sensitive and reliable method for detection ofChlamydia trachomatis.     

Hypothesis: Chlamydia trachomatis infection of the female genital tract is controlled by Type 2 immunity

Chlamydia trachomatis is an obligate intracellular bacterium sexually transmitted to more than 90 million individuals each year. As this level of infectivity implies, C. trachomatis is a successful human parasite; a success facilitated by its ability to cause asymptomatic infection. Host defense against C. trachomatis in the female genital tract is not well defined, but current dogma suggests infection is controlled largely by T_H1 immunity. Conversely, it is well established that T_H2 immunity controls allergens, helminths, and other extracellular pathogens that cause repetitive or persistent T cell stimulation but do not induce the exuberant inflammation that drives T_H1 and T_H17 immunity. As C. trachomatis persists in female genital tract epithelial cells but does not elicit over tissue inflammation, we now posit that defense is maintained by Type 2 immune responses that control bacterial growth but minimize immunopathological damage to vital reproductive tract anatomy. Evaluation of this hypothesis may uncover novel mechanisms by which Type 2 immunity can control growth of C. trachomatis and other intracellular pathogens, while confirmation that T_H2 immunity was selected by evolution to control C. trachomatis infection in the female genital tract will transform current research, now focused on developing vaccines that elicit strong, and therefore potentially tissue destructive, Chlamydia-specific T_H1 immunity.     

Detection of Seroconversion and Persistence of Chlamydia trachomatis Antibodies in Five Different Serological Tests

 Microimmunofluorescence (MIF), a Chlamydia trachomatis species-specific enzyme immunoassay incorporating lipopolysaccharide-extracted Chlamydia trachomatis L2 elementary bodies, two different synthetic peptide-based species-specific tests, and a recombinant lipopolysaccharide genus-specific test were performed on multiple follow-up sera (n=104 total) from 16 women with Chlamydia trachomatis-positive cervical swabs. These women included five with IgG seroconversions, five with Chlamydia trachomatis reinfections after initial therapy, and six with serologic follow-up of more than 6 years after antibiotic therapy. Of all the tests employed in this study, MIF IgG reverted earliest to negative titers, while MIF IgA was the least sensitive. The lipopolysaccharide-extracted elementary body enzyme immunoassay exhibited the closest correlation with the MIF test. The highest test sensitivity was observed in one of the synthetic peptide-based tests, which detected earliest seroconversions and longest IgG persistence. The other synthetic peptide-based test gave false-negative results in 2 of 16 women and did not detect seroconversion earlier than the MIF test. Seroconversion and persistence of genus-specific IgG – cross-reactivity with Chlamydia pneumoniae– against lipopolysaccharide were similar to species-specific IgG. A significant serologic response to reinfection was observed only in women with signs of pelvic inflammatory disease. Species-specific tests of high sensitivity and reproducibility are best suited for gynecological diagnostic purposes.     

Chlamydia muridarum Major Outer Membrane Protein‐Specific Antibodies Inhibit In Vitro Infection but Enhance Pathology In Vivo

Citation Cunningham KA, Carey AJ, Hafner L, Timms P, Beagley KW. Chlamydia muridarum major outer membrane protein‐specific antibodies inhibit in vitro infection but enhance pathology in vivo. Am J Reprod Immunol 2011; 65: 118–126 Problem Chlamydia trachomatis is a significant worldwide health problem, and the often‐asymptomatic disease can result in infertility. To develop a successful vaccine, a complete understanding of the immune response to chlamydial infection and development of genital tract pathology is required. Method of Study We utilized the murine genital model of chlamydial infection. Mice were immunized with chlamydial major outer membrane protein, and vaginal lavage was assessed for the presence of neutralizing antibodies. These samples were then pre‐incubated with Chlamydia muridarum and administered to the vaginal vaults of immune‐competent female BALB/c mice to determine the effect on infection. Results The administration of C. muridarum in conjunction with neutralizing antibodies reduced the numbers of mice infected, but a surprising finding was that this accelerated the development of severe oviduct pathology. Conclusion Antibodies play an under‐recognized role in chlamydial infection and pathology development, which possibly involves interaction with Th1 immunity.     

Immune response toChlamydia trachomatis heat-shock protein in infertile female patients and influence ofChlamydia pneumoniae antibodies

A total of 446 sera from 245 patients with primary or secondary infertility, all of whom were examined laparoscopically, 117 patients withChlamydia trachomatis-positive cervical swabs, and 84 control persons (50 obstetric patients and 34 female blood donors) were tested for antibodies toChlamydia trachomatis and toChlamydia pneumoniae with the microimmunofluorescence (MIF) test. MIF test antibody rates were highest in patients with complete tubal occlusion (73%) and in patients with provenChlamydia trachomatis infection (74%), whereas only 9 to 10% of the control group showedChlamydia trachomatis antibodies. Reaction to the 60 kDa antigen ofChlamydia trachomatis, a heat-shock protein (hsp) analogue, has been suggested as a possible marker for the development of chronic sequelae afterChlamydia trachomatis infection. Immunoblot analysis of 222 sera (169 infertility patients, 20 antigen-positive patients, and 33 mothers) showed a significantly higher anti-hsp antibody rate in patients with complete tubal occlusion than in infertility patients with normal fallopian tubes (76% vs. 19%, p<0.001). The presence of antibodies not only toChlamydia trachomatis but also toChlamydia pneumoniae in the MIF test was associated with a significantly higher rate of anti-hsp antibodies and with complete tubal occlusion. This association did not appear to be due to cross-reactivity betweenChlamydia pneumoniae and Chlamydia trachomatis antibodies in the MIF test.     

The Combination of the Gastrointestinal Integrin (α4β7) and Selectin Ligand Enhances T-Cell Migration to the Reproductive Tract During Infection with Chlamydia trachomatis

Problem  Chlamydia trachomatis causes sexually transmitted infection and reproductive dysfunction worldwide. Identifying a population of endocervical T-cells to target in vaccine development is likely to enhance efficacy of a vaccine and reduce reproductive tract dysfunction.
Method of study  Endocervical samples were obtained from young women and flow cytometric analysis was used to identify lymphocytes that appeared in the genital tract in response to sexually transmitted bacterial infections caused by C. trachomatis.
Results  Increased numbers of α4β7+CLA+ memory T-cells, a unique T-cell phenotype, were found in the endocervix of human female subjects infected with C. trachomatis .
Conclusion A unique population of memory T lymphocytes expressing both α4β7 and CLA gain access to reproductive tract tissues during a sexually transmitted infection with C. trachomatis and should be considered in development of vaccines against sexually transmitted infections.     

Immunology: Circulating antibodies to Chlamydia trachomatis in women: relationship to antisperm and antichiamydial antibodies in semen of male partners

The relation between antibodies to Chlamydia trachomatis andspermatozoa in sera of 112 asymptomatic female partners of infertilecouples with no history of C.trachomatis infections and antichlamydialantibodies in semen or antisperm antibodies on ejaculated spermatozoaof their male partners was examined. Samples were tested forimmunoglobulin (Ig)A and IgG antibodies to C.trachomatis byenzyme-linked immunosorbent assay; antisperm antibodies in seraand on motile spermatozoa were assayed by immunobead binding.IgG antibodies to C.trachomatis were detected in 24 (21.4%)of the women; only five (4.5%) women were positive for antichlamydialIgA. Antichlamydial IgG was detected in sera from 10 (40.0%)of 25 women whose partners had antichlamydial IgA in semen asopposed to 14 (16.1%) of 87 women whose partners' semen werenegative for this antibody (P=0.02). Similarly, antichlamydialIgG was detected in sera from five (50%) of 10 women whose partnershad antichlamydial IgG in semen as opposed to 19 (18.6%) of102 women whose partners' semen lacked this antibody (P=0.03).There was no relation between antichlamydial antibodies in womenand circulating antichlamydial antibodies in men. A strong correlation(P=0.001) was observed between IgG antichlamydial antibodiesin a woman's serum and antisperm antibodies on ejaculated spermatozoaof her partner [8 of 14 (57.1%) versus 16 of 98 (163%)]. Conversely,antichlamydial antibodies in a woman's serum was unrelated tothe presence of antisperm antibodies in either her own serumor her partner's serum. The data demonstrate that chlamydialinfections of the male genital tract, which are associated withantisperm antibody formation on ejaculated spermatozoa, arelikely to be transmitted to the female partner. In contrast,the presence of antichlamydial antibodies in sera does not necessarilyappear to indicate an infection of the genital tract and isnot associated with the heterosexual transmission of C.trachomatis.     

Epidemiology of chlamydial infection of the human genital tract: Evidence for the existence of latent infections

A group of 536 women attending a clinic for sexually transmitted diseases was investigated for cervical infection byNeisseria gonorrhoeae andChlamydia trachomatis. Conclusions have been reached concerning the existence and significance of latent and subclinical chlamydial infection of the female genital tract, and on the sexual infectivity ofChlamydia trachomatis to women. The results of the study indicate (1) demonstrable chlamydial infection in 25 % of all women attending the clinic for the first time, and in 11 % of those with unknown contact history; (2) sexual transmission ofChlamydia trachomatis; 45 % of women exposed to chlamydiae contract the infection compared with 75 % of those exposed toNeisseria gonorrhoeae; (3) the possibility of reactivation of latent chlamydial infection byNeisseria gonorrhoeae in some women.     

A distinct cellular profile is seen in the human endocervix during Chlamydia trachomatis infection

Problem The endocervix is a major target of Chlamydia trachomatis infection, but little is known about the immune repertoire in this tissue, or its response to these common bacteria. Method of study Using a cytobrush, we isolated cells from the endocervix of 20 women during C. trachomatis infection, and post‐antibiotic treatment. Endocervical swabs and blood were taken in parallel. Endocervical cells were enumerated, and endocervical and blood T cells immunophenotyped. Chlamydia trachomatis was genotyped by sequence analysis of the OmpA gene, and quantified by culture. Results Chlamydia trachomatis genotypes were D, E, F and Ia, and infectious burden varied considerably. Endocervical T cell and neutrophil numbers were highly elevated during infection, with both CD4 and CD8 T‐cell subsets accumulating. Regardless of the presence or absence of infection, the endocervical cell infiltrate was dominated by effector memory T cells, and the numbers of CCR5 and CD103 expressing T cells was significantly higher than in the blood. Human leukocyte antigen (HLA‐DR) expression by endocervical T cells was significantly increased during infection. Conclusion The human endocervix exhibits a distinct cellular response to C. trachomatis infection that can be longitudinally evaluated by cytobrush sampling. Infecting organisms can be sampled and analyzed in parallel.     

Relationship between female genital tract infections,mucosal interleukin‐17 production and local T helper type 17 cells

T helper type 17 (Th17) cells play an important role in immunity to fungal and bacterial pathogens, although their role in the female genital tract, where exposure to these pathogens is common, is not well understood. We investigated the relationship between female genital tract infections, cervicovaginal interleukin-17 (IL-17) concentrations and Th17 cell frequencies. Forty-two cytokines were measured in cervicovaginal lavages from HIV-uninfected and HIV-infected women. Frequencies of Th17 cells (CD3⁺ CD4⁺ IL-17a⁺) were evaluated in cervical cytobrushes and blood by flow cytometry. Women were screened for Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis and herpes simplex virus 2 by PCR, and candidal infections and bacterial vaginosis by Gram stain. Women with bacterial sexually transmitted infections (STIs), specifically chlamydia and gonorrhoea, had higher genital IL-17 concentrations than women with no STI, whereas women with candidal pseudohyphae/spores had lower IL-17 concentrations compared with women without candidal infections. Viral STIs (herpes simplex virus 2 and HIV) were not associated with significant changes in genital IL-17 concentrations. Genital IL-17 concentrations correlated strongly with other inflammatory cytokines and growth factors. Although Th17 cells were depleted from blood during HIV infection, cervical Th17 cell frequencies were similar in HIV-uninfected and HIV-infected women. Cervical Th17 cell frequencies were also not associated with STIs or candida, although few women had a STI. These findings suggest that IL-17 production in the female genital tract is induced in response to bacterial but not viral STIs. Decreased IL-17 associated with candidal infections suggests that candida may actively suppress IL-17 production or women with dampened IL-17 responses may be more susceptible to candidal outgrowth