Chlamydia trachomatis and Reproductive health
Year: 2019
Type: dissertation
Study design: Observational Study
Abstract: Chlamydia trachomatis infection is the most common bacterial sexually transmitted infection (STI) worldwide. It has been linked to severe reproductive morbidity, including tubal factor infertility (TFI), ectopic pregnancy (EP), miscarriage and preterm delivery (PTD), but the evidence has mostly been based on clinical case-control studies, and the data retrieved from population-based studies have been limited. The aim of this thesis was to study the role of C. trachomatis infection in adverse pregnancy outcomes and subfertility. To evaluate the link between C. trachomatis infection and EP, miscarriage and PTD, we performed a population-based, biobank health registry study. We used national health registries to identify the cases with adverse pregnancy outcomes (n=2950). The cases were linked to the Finnish Maternity Cohort serum bank to obtain samples for serological analysis. C. trachomatis major outer membrane protein (MOMP)–specific IgG antibodies were determined from the serum samples. Our results confirmed the association between C. trachomatis infection and EP, alhough C. trachomatis seroprevalence was lower than expected. The seroprevalence rate and the link between antichlamydial antibodies and EP were strongest among women over 35 years of age. We did not find a serological link between C. trachomatis infection and miscarriage or PTD. Cell-mediated immune response is crucial in the resolution of C. trachomatis infection, but it may play an important role in the pathogenesis of Fallopian tube damage. The link between serum C. trachomatis IgG antibodies and TFI has been well established, and chlamydia antibody testing (CAT) has been introduced as a screening test for TFI in the initial infertility workup to select high-risk patients for further tubal evaluation. We studied the role of C. trachomatis infection in subfertility by measuring C. trachomatis–specific immune responses in a cohort of subfertile women (n=258). Cell-mediated immune response was analyzed from peripheral blood samples by an in vitro lymphocyte proliferation test using C. trachomatis elementary body (EB) and recombinant chlamydial 60 kDA heat shock protein (cHSP60) as lymphocyte-stimulating antigens. Serum C. trachomatis–specific IgG antibody responses were studied using C. trachomatis MOMP, cHSP60, and C. trachomatis TroA and HtrA as antigens. Our aim was to develop a specific and sensitive non-invasive test for TFI prediction in subfertile women to simplify infertility workup. According to our results, the accuracy of C. trachomatis serology in evaluating TFI can be improved by combining serum C. trachomatis MOMP and cHSP60 IgG antibody tests or combining markers of C. trachomatis–specific cell-mediated and humoral immune responses. C. trachomatis may impair fertility by mechanisms other than occluding the Fallopian tubes, such as causing functional tubal damage or inflammation in the endometrium. We studied the role of C. trachomatis infection in unexplained infertility by analyzing C. trachomatis–specific immune responses in women with no specific etiology for subfertility. Neither humoral nor cell-mediated immune response to C. trachomatis were associated with unexplained infertility. The presence of serum antichlamydial IgG antibodies was linked to a prolonged time for spontaneous pregnancy, but pregnancy outcomes, including live birth rate, did not differ between seropositive and seronegative women. The highest prevalence of C. trachomatis infection is seen in young, sexually active women aged 20–25 years. Studies estimating the risk of long-term sequelae following C. trachomatis infection are important, because women diagnosed with chlamydial infection are usually worried and need counseling for their future fertility. Our study, together with other population-based data, suggests that the long-term risks following chlamydial infection are lower than previously thought. Since the development of TFI is multifactorial, C. trachomatis immune markers in TFI prediction are only of modest value. TFI prevalence was low in our study (8.5%), which is in line with the declining trend of C. trachomatis–associated reproductive problems in the population. This results most likely from the successful C. trachomatis screening programs, which have led to the effective treatment of chlamydial infections before they ascend to the upper genital tract. The risk of reproductive problems is, however, significantly higher after recurrent chlamydial infection, and preventive strategies should be planned to recognize the core group at the highest risk for recurrent infection.
Source: Työväentutkimus Vuosikirja
Author: Tiina Rantsi
Language: English
Subfield: Microbiology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2907332460