Dual Role of the Endometrial Microbiome-Immune Axis: From Endometrial Homeostasis to Reproductive Disorders

Abstract: The homeostasis of the uterine environment is crucial for reproductive health. Recent studies have revealed the complex interplay between the endometrial microbiome, immune system, and the endometrium. Under normal physiological conditions, the microbiome, primarily composed of Lactobacillus species, promotes a healthy reproductive environment by maintaining local immune homeostasis, inhibiting the growth of pathogenic microorganisms, and regulating the integrity of the endometrial barrier. However, dysbiosis can abnormally activate local immune responses, disrupting the immune tolerance mechanisms of the endometrium and thereby compromising pregnancy maintenance and overall reproductive health. This study uniquely highlights the role of the endometrial microbiome in modulating immune responses specifically within the uterine environment, a critical factor for reproductive success. Our findings also suggest novel therapeutic strategies targeting microbiome modulation and immune regulation, offering promising avenues for improving reproductive health outcomes. This review aims to explore the regulatory mechanisms of the microbiome-immune axis in both physiological and pathological conditions, with a particular focus on how these interactions specifically influence the uterine environment, while also considering the broader implications of microbiome-immune interactions throughout the entire body. We will analyze its potential role in reproductive health issues and discuss new therapeutic strategies based on microbiome and immune modulation. Keywords: endometrium, microbiota, immune response, reproductive health, immune tolerance, dysbiosis, recurrent miscarriage, infertility, endometritis