抵抗女性生殖道沙眼衣原体感染的免疫新策略

沙眼衣原体是引起沙眼和泌尿生殖道感染的主要病原体。据世界卫生组织2015年统计,全球每年约有1.3亿沙眼衣原体感染新发病例。研究表明CD4^+Th1型细胞免疫应答在抵抗沙眼衣原体感染中发挥着重要作用。因此,研究者依照抗沙眼衣原体感染的免疫应答特点,构建出许多候选疫苗,但都没有成功地应用于临床。近年研究发现,生殖道黏膜组织不仅存在体液免疫和细胞免疫,还驻留着一些引人注目的免疫细胞,提示增强黏膜免疫可作为预防沙眼衣原体感染的潜在途径,是抵抗生殖道沙眼衣原体感染的免疫新策略。本文全面概述了黏膜免疫与女性生殖道沙眼衣原体感染的研究进展,并为今后研制沙眼衣原体疫苗提供一些建议。     

Prevalence of Chlamydia trachomatis and genital mycoplasmas in asymptomatic women.

To establish the prevalence of Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum in women attending a family planning and a prenatal clinic in Halifax, cervical swabs were obtained at the time of the first visit from 491 women who had no symptoms of genital infection. Among the women attending the family planning clinic M. hominis occurred in combination with C. trachomatis more frequently than expected (p less than 0.05). It occurred in the absence of U. urealyticum in only a few cases (13% of the occurrences in the family planning clinic and 6% of those in the prenatal clinic). C. trachomatis was significantly more prevalent in women under 25 years of age (p less than 0.04). However, mycoplasmas were as prevalent in women over 30 years as in those under 30. There were no significant differences in the infection rates of the organisms by trimester among pregnant women. More research is necessary for a proper understanding of the role of M. hominis and U. urealyticum in genitourinary infections and pregnancy outcomes.     

Interaction of Chlamydia trachomatis with human genital epithelium in culture

Primary cultures of human endometrial and ectocervical epithelial cells were examined as a new model system to study genital infection by Chlamydia trachomatis. Initial studies demonstrated that these cells were indeed susceptible to chlamydial infection. Inocula, adjusted to produce inclusions in 50 to 80% of equivalent numbers of standard McCoy cells, resulted in infection rates of approximately 15 to 30% for the columnar cells of the endometrium and 5 to 10% for the squamous cells of the ectocervix. Exposure of cultures to DEAE-dextran and centrifugation-assisted inoculation, manipulations reported to enhance infection of HeLa and McCoy cells, did not alter the number of inclusion-positive genital cells. Addition of cycloheximide to the post-inoculation culture medium slightly increased numbers of inclusion-bearing cells while growth of genital cells in hormone-supplemented medium resulted in a variable effect on inclusion development and a significant reduction in the association of radiolabelled organisms with these cells. The basis for the different levels of infection in McCoy versus genital cell cultures was revealed by immunofluorescence analysis of chlamydial association with host cells immediately after inoculation. Chlamydiae failed to adhere to many cells in the genital cell cultures while adherence to McCoy cells was uniform. In addition, the association of radiolabelled C. trachomatis was significantly lower with genital cells than with McCoy cells. Finally, culture conditions were defined which markedly inhibited inclusion development without an immediate loss of chlamydial growth potential. This investigation indicates that primary genital cell cultures are susceptible to chlamydial infection and will be valuable for studies on the nature of C. trachomatis interactions with natural human target cells.     

The role of intracellular glutathione in the progression of Chlamydia trachomatis infection

The productive internalization in the host cell of Chlamydia trachomatis elementary bodies and their infectivity depends on the degree of reduction of disulfide bonds in the outer envelope of the elementary body. We have hypothesized that the reducing agent may be intracellular glutathione (GSH). Three approaches were used to modulate the intracellular GSH concentration: (1) treatment of cells with buthionine sulfoximine, which causes irreversible inhibition of GSH biosynthesis; (2) hydrogen peroxide-induced oxidation of GSH by intracellular glutathione peroxidases; and (3) treatment of cells with N-acetyl-l-cysteine (NAC), a precursor of glutathione. In the first two cases, we observed a four- to sixfold inhibition of C. trachomatis infection, whereas in NAC-treated cells we detected an increase in the size of chlamydial inclusions. Using a proteomics approach, we showed that the inhibition of chlamydial infection does not combine with alterations in protein expression patterns after cell treatment. These results suggest that GSH plays a key role in the reduction of disulfide bonds in the C. trachomatis outer envelope at an initial stage of the infection.     

Chlamydia trachomatis infection in rural Nova Scotia.

OBJECTIVE: To examine the demographic characteristics of patients who underwent testing for Chlamydia trachomatis and to determine the clinical and behavioural characteristics and the types of treatment for those who had positive test results. DESIGN: Case series. SETTING: Rural county in Nova Scotia. PATIENTS: All residents of the county for whom testing for C. trachomatis was ordered at the regional hospital from Sept. 1, 1990, to Mar. 31, 1991. MAIN OUTCOME MEASURES: Rates of testing and of positive test results by age and sex. Comparison of patient and physician characteristics in relation to testing rates. RESULTS: Of the 1116 patients tested 58 (5.2%) had positive test results. Females accounted for 82.8% of those with positive results whose sex could be determined. Among the females the mean age of those with a positive result was 22.3 years, as compared with 27.5 years for those with a negative result (p < 0.0001). Females 15 to 19 years of age were less likely to have a test performed than women 20 to 29 years and were more likely to have a positive test result than the women in the older groups. Almost 9% of the testing among the females was in those over 39 years of age, although no infection was seen in this age group. The number of tests ordered per general or family practitioner varied from 1 to 154; the physicians'' sex, practice location and length of time in practice did not predict the rates of positive test results. Treatment was most often in keeping with that recommended by national guidelines. Four (8.5%) of the 47 patients with positive results who were interviewed were not aware of their diagnosis, either because they had not returned for follow-up or had not being notified by the physician''s office. CONCLUSIONS: The frequency of testing for C. trachomatis infection may be less than is desirable among young patients, who, if tested, are more likely than older patients to have positive results. More understanding of the diagnostic approach taken by physicians is needed.     

Endocervical Chlamydia trachomatis infection in Canadian adolescents.

The highest prevalence rate of sexually transmitted chlamydial infection is among adolescent girls. To determine the rate among predominantly asymptomatic girls who were seen at a pediatric gynecology unit and to identify those at high risk we screened 541 such patients from Jan. 1 to Dec. 31, 1986, by means of direct fluorescent antibody testing; 422 (78.0%) were asymptomatic. The most common reason for presentation was a request for contraceptive advice (the reason for 59.2% of the patients). Of the 446 patients (82.4%) who were sexually active 66 (14.7%) had evidence of chlamydial infection; none of the 93 sexually inactive patients were infected. Neisseria gonorrhoeae was isolated from eight (1.5%) of the patients. The risk factors that correlated with chlamydial infection were abnormal vaginal discharge, abdominopelvic pain and an abnormal Papanicolaou test result. Because of the high morbidity rate associated with genital chlamydial infection and the high prevalence rate among adolescent girls, most of whom are asymptomatic, all sexually active teenagers should be screened.     

Serologic evidence of Chlamydia trachomatis infection and risk of preterm birth.

OBJECTIVE: To determine whether serologic evidence of Chlamydia trachomatis during pregnancy is a risk factor for preterm delivery (before 37 weeks'' gestation). DESIGN: Chart review. SETTING: Antenatal clinics associated with a teaching hospital. PATIENTS: A group of 103 unselected consecutive patients presenting for routine prenatal care. OUTCOME MEASURES: Pregnancy outcome and C. trachomatis serologic status. RESULTS: A total of 21 women (20%) were found to be seropositive for IgG antibodies to C. trachomatis. They were similar to the seronegative women with respect to maternal age, parity, history of preterm birth, obstetric or medical problems, smoking status, history of drug abuse, educational status and psychosocial stressors. The seropositive women were significantly more likely than the seronegative women to have a preterm birth (24% [5/21] v. 7% [6/82]i p = 0.029, odds ratio 3.96, 95% confidence interval 1.08 to 14.57), an infant with a lower mean gestational age at birth (262 [standard deviation (SD) 19] days v. 273 [SD 15] days; p = 0.0052) and an infant with a lower mean birth weight (3125 [SD 692] g v. 3473 [SD 696] g; p = 0.0434). The positive predictive value of a seropositive result for preterm birth was 31% (5/16); the negative predictive value of a seronegative result for preterm birth was 8% (6/76). CONCLUSION: Women with serologic evidence of C. trachomatis may be at risk for preterm birth. Further study is required to determine whether serologic testing for C. trachomatis should be a routine part of prenatal care.     

IgA antibodies to Chlamydia trachomatis and metabolic syndrome

Chlamydia pneumoniae may trigger atherogenesis. Chlamydia trachomatis (CT) can also induce endothelial activation. However, its role in metabolic syndrome (METS), a proatherogenic entity, has remained unexplored. In this study the frequencies of IgA and IgG anti-CT antibodies were evaluated by immunoenzymatic assay in METS patients and healthy controls. The survey included 238 individuals (148 with METS). The mean age was 59.7 years. IgA anti-CT antibodies were found significantly more frequently in METS patients (16.9%) than in controls (5.6%) (P= 0.015). The role of such IgA response in METS should be further investigated.     

Prior exposure to infection with Chlamydia pneumoniae can influence the T-cell-mediated response to Chlamydia trachomatis

Using T-cell clones derived from patients with Chlamydia trachomatis (CT)-induced reactive arthritis, we identified target antigens and mapped the peptide epitopes that were recognized. Several epitopes were conserved in homologous proteins of Chlamydia pneumoniae (CPN), and it was shown that these epitopes were generated following processing of the CPN proteins or CPN elementary bodies, i.e. the T-cell clones were indeed CT and CPN cross-reactive. Given that CPN infection is frequent, we wished to determine whether prior infection with CPN could have an effect on the response to subsequent infection with CT. First, we showed that the CPN antigen, OmcB, was recognized by polyclonal peripheral blood T cells from additional subjects with CT-induced reactive arthritis; they were chosen to be HLA-DR-matched with the T-cell clones used to map epitopes in OmcB. Responses to a peptide previously shown to be conserved in CT and CPN OmcB were also seen, but only in CPN-seropositive individuals. These subjects also produced interferon-gamma (IFN-gamma) in response to CPN OmcB, and did not recognize a nonconserved epitope in OmcB. Secondly, OmcB-responsive clones from CPN-seropositive subjects were dominated by those recognizing the cross-reactive epitope, despite the recent exposure of these subjects to CT. Lastly, healthy CPN-seropositive subjects, without evidence of exposure to CT, showed greater responses, measured as IFN-gamma secretion, to CT proteins in vitro than those shown by seronegative subjects. This is consistent with the idea that prior CPN infection primes a Th1 T-cell response to CT antigens. This finding is relevant to the pathogenesis of the sequelae of CT infection (trachoma, infertility and arthritis), which may be influenced by prior exposure to CPN, and to the choice of CT antigens as vaccine candidates.     

Identification of an iron-responsive protein that is antigenic in patients with Chlamydia trachomatis genital infections

Chlamydia trachomatis is an important cause of immune-mediated damage to the reproductive tract of infected patients. Certain chlamydial antigens and host genetic factors have been identified as contributing to immunopathological events, but a comprehensive understanding of specific components involved in destructive vs. protective immune responses to chlamydial infections is far from clear. In this study, it is shown that C. trachomatis-infected patients generate antibodies against an iron-responsive chlamydial protein, YtgA. The identity of YtgA was confirmed by mass spectrometry following two-dimensional polyacrylamide gel electrophoresis and Western blot analysis. This finding underscores a necessity to examine patient sera samples to identify chlamydial antigens that are likely encountered and important to the immune response during human infections.     

Immunobiology of monocytes and macrophages during Chlamydia trachomatis infection

Infections caused by the intracellular bacterium Chlamydia trachomatis are a global health burden affecting more than 100 million people annually causing damaging long-lasting infections. In this review, we will present and discuss important aspects of the interaction between C. trachomatis and monocytes/macrophages.     

Chlamydia trachomatis infection and human papillomavirus in women with cervical neoplasia in Pernambuco-Brazil

Chlamydia trachomatis (CT) is the most common bacterial cause of sexually transmitted disease. High-risk human papillomavirus (HR-HPV) is considered the main etiological agent for cervical neoplasia. Evidences showed that the presence of co-infection of CT and HR-HPV plays a central role in the etiology of cervical intraepithelial neoplasia (CIN) and cervical cancer. The goals of this study were: evaluate the human papillomavirus (HPV) and CT prevalence among Brazilian women with abnormal cytology and provide the effect of this association on the severity of cervical neoplasia. The population of this study was composed by 142 women with incident histological incidence of CIN grades I, II, III or cervical cancer from Recife, Northeast of Brazil. The polymerase chain reaction method on a cervical brush specimen was used to detect both agents and the automatic sequencing method was used for HPV genotyping assay. The prevalence of HPV and CT was 100 and 24.65 %, respectively. Thirteen types of HPV were detected; HPV 16, 18, 31 and 33 were the most common. The most prevalent HPV types were HPV 16 and 18. A significant association between CT positive and HPV 16 infection was found (p < 0.0106; OR = 5.31; 95 % IC 1.59–17.67). In the study population, there was diversity of HPV infections, with high-risk types being the most common. Also, the data collected suggest that CT infection may play an important role in the natural history of HPV infection.     

The multifaceted role of oestrogen in enhancing Chlamydia trachomatis infection in polarized human endometrial epithelial cells

The oestrogen receptor (ER) α-β+ HEC-1B and the ERα+β+ Ishikawa (IK) cell lines were investigated to dissect the effects of oestrogen exposure on several parameters of Chlamydia trachomatis infection. Antibody blockage of ERα or ERβ alone or simultaneously significantly decreased C. trachomatis infectivity (45-68%). Addition of the ERβ antagonist, tamoxifen, to IK or HEC-1B prior to or after chlamydial infection caused a 30-90% decrease in infectivity, the latter due to disrupted eukaryotic organelles. In vivo, endometrial glandular epithelial cells are stimulated by hormonally influenced stromal signals. Accordingly, chlamydial infectivity was significantly increased by 27% and 21% in IK and HEC-1B cells co-cultured with SHT-290 stromal cells exposed to oestrogen. Endometrial stromal cell/epithelial cell co-culture revealed indirect effects of oestrogen on phosphorylation of extracellular signal-regulated kinase and calcium-dependant phospholipase A2 and significantly increased production of interleukin (IL)-8 and IL-6 in both uninfected and chlamydiae-infected epithelial cells. These results indicate that oestrogen and its receptors play multiple roles in chlamydial infection: (i) membrane oestrogen receptors (mERs) aid in chlamydial entry into host cells, and (ii) mER signalling may contribute to inclusion development during infection. Additionally, enhancement of chlamydial infection is affected by hormonally influenced stromal signals in conjunction with direct oestrogen stimulation of the human epithelia.     

Characterization of estrogen-responsive epithelial cell lines and their infectivity by genital Chlamydia trachomatis

Chlamydial attachment and infectivity in vitro and ascending disease and sequelae in vivo have been reported to be enhanced/modulated by estrogen. Endometrial carcinoma cell lines Ishikawa and HEC-1B and the breast cancer lines MCF-7 and HCC-1806 were examined for Chlamydia trachomatis E infectivity. Estrogen receptor (ER) presence was confirmed by Western blot and qRT-PCR analyses. FACS analysis was used to determine the percent of plasma membrane-localized ERs (mERs), and their activity was tested by estrogen binding and competitive estrogen antagonists assays. Chlamydiae grew in all cell lines with HEC (90%) > MCF-7 (57%)>Ishikawa (51%) > HCC-1806 (20%). The cell line ER isoform composition was re-defined as: ERalpha + ERbeta + for MCF-7, HCC-1806 and Ishikawa; and ERbeta only for HEC-1B. HeLa cells were also tested and found to express ERbeta, but not ERalpha. A small percentage of both ERs were surface-exposed and functionally active. The endometrium-predominant ERbeta isoform was found in all cell lines, including those most representative of the common sites of C. trachomatis infection. Thus, the role of chlamydial attachment/infectivity will now be analyzed in ERbeta+and-isogenic HEC-1B cells.     

Antigen-specific CD8+ T cells respond to Chlamydia trachomatis in the genital mucosa

Following sexual transmission, Chlamydia trachomatis specifically targets genital tract epithelial cells. Because epithelial cells are readily recognized by CD8+ T cells, the response of CD8+ T cells to Chlamydia infection has been explored in a number of studies. It has been shown that CD8+ T cells are present in the genital tracts of mice following C. trachomatis infection, but the specificity of these T cells has remained undefined. To determine whether Chlamydia-specific CD8+ T cells migrate to the genital tract in response to Chlamydia infection, we generated retrogenic mice that express a TCR specific for a Chlamydia-specific T cell Ag CrpA. T cells from the retrogenic mice were transferred into naive recipient animals to increase the frequency of Chlamydia-specific T cells to a level at which they could be tracked during primary infection. We observed that the Chlamydia-specific retrogenic T cells proliferated in lymph nodes draining the genital tract in response to genital infection with C. trachomatis. Furthermore, we found that these cells acquired the ability to produce IFN-gamma and migrated into the genital mucosa of the infected mice.