High level of interleukin-1β in trichomoniasis may increase susceptibility to unexplained female infertility

Background: Inflammation in the upper reproductive tract may increase the risk of infertility in women with trichomoniasis. Increased levels of the pro-inflammatory cytokine (IL-1β), and particular gene polymorphisms, are associated with a higher incidence of trichomoniasis in women with unexplained infertility.Objective: To investigate the potential role of IL-1β level and gene polymorphisms in the development of unexplained infertility among those with trichomoniasis.Patients and Methods: This cross-sectional study recruited 103 female patients diagnosed with unexplained infertility. Vaginal swab samples were analyzed using three methods: wet mount microscopy, culture, and molecular identification targeting the beta-actin gene. Serum IL-1β levels were measured using ELISA. Polymorphism of the gene encoding IL-1β at positions +3954C/T and -31T/C was characterized using a PCR-fragment length polymorphism (PCR-RFLP) assay.Results: The overall occurrence of T. vaginalis in unexplained infertile females was estimated at 25.2% by PCR, compared to 7.8% by wet mount microscopic examination, and 10.7% by vaginal swab culture. The level of IL-1β in women infected with T. vaginalis was significantly (P=0.028) higher than in women without infection (19.8±7.4 vs. 15.0± 10.1 pg/ml. Results of gene polymorphism revealed that the CC genotype (-31T/C) was shown as a possible risk factor for trichomoniasis. A statistically significant association was found between trichomoniasis, and unexplained infertility.Conclusion: This study highlights the possible role of trichomoniasis as one of the unexplained female infertility reasons. Compared to other methods, molecular diagnosis is the best to identify T. vaginalis. Elevated IL-1β levels in trichomoniasis is highly suggestive to attribute unexplained female infertility to trichomoniasis.