Macrophage – the Central Link of the Endometrial Tissue Communication System

Abstract

This study deals with the problem of the macrophage cell population as one of the most significant structures for monitoring and controlling the endometrial tissue homeostasis, where these cells coordinate the work of cell  populations  composing  the  communication  system.  Due  to the possibility  of polarizing  their  phenotype, macrophages are able to perform many functions by regulating the structural transformations of the endometrium depending on the phase of the cycle or occurrence of a pathology. A high concentration of estrogen in the follicular phase is a signal for endometrial macrophages to trigger a series of events that affect all other cell populations, including endometrial mesenchymal stem cells. These interactions result in the activation of the proliferation of fibroblast-like cells with their subsequent maturation, as well as angiogenesis and neurogenesis, being the stromal component of the endometrium functional layer. Of particular interest is the impact of macrophages on the replenishment of the glandular component of the endometrium functional layer within the glandular remodeling process, which is based on the epithelial-mesenchymal transition. In the phase of secretion, endometrial macrophages coordinate the creation of a cellular microenvironment to ensure the tolerance of maternal immune cells to antigens of the fetus, as well as maintaining homeostasis and placental growth. In the absence of fertilization, macrophages actively contribute to the destruction of the main substance of the endometrial tissue; this ensures menstrual decay in the desquamation phase. This study considers the role of the macrophages functional imbalance as a pathogenetic link of certain pathologies of the endometrium and pregnancy. Thus, it is demonstrated the central role of the macrophage population in controlling the communication system of the endometrial tissue. Insight of these aspects opens up new opportunities for managing the menstrual cycle, planning and maintaining pregnancy.