Steroid hormone dependent inflammation and regulation in the endometrium in women with dysfunctional menstrual cycles: Is there a role for toll-like receptor activation via PAMPs and DAMPs?

Summary Sentence The role of microbial and immunological menstrual cycle dependent changes within the endometrium may provide insight into the underlying causes of dysfunctional menstrual cycles. Abstract The ovarian steroid hormones control cyclic cellular proliferation, differentiation, inflammatory cell recruitment, apoptosis, tissue degradation and regeneration associated with the menstrual cycle as well as the response to pathogen challenge. Women with dysfunctional menstrual cycles (menorrhagia and dysmenorrhea) exhibit altered cytokine and prostaglandin expression in the endometrium implying ongoing recruitment of innate immune mediators. Activation of TLRs by endogenous and/or exogenous ligands caused by cell damage resulting from ongoing inflammation, endogenous microbiota or dysbiosis may contribute to the inflammatory symptoms associated with these conditions. The role of the upper genital tract endogenous microbiota in promoting genital tract homeostasis through possible promotion of re-epithelialization or anti-inflammatory mediators warrants further investigation