Special collection on immune regulation and inflammatory mechanisms in reproductive health and disease.

ABSTRACT: Understanding how the immune system intersects with reproductive physiology is central to elucidating fertility mechanisms and the pathophysiology of reproductive disorders. Distinct immunological environments in both male and female reproductive organs are essential to maintain tissue integrity and function, support gametogenesis, enable fertilization, and sustain pregnancy while ensuring effective defence against pathogens. Disruptions in these complex regulatory networks may lead to chronic inflammation, infertility, and poor pregnancy outcomes. Recent breakthroughs have improved our understanding of the roles of immune cells, including mononuclear phagocytes, T cell subsets, and innate lymphoid cells, and non-immune cells in orchestrating immune tolerance, immune response, and inflammation across reproductive tissues in both health and disease contexts. This Reproduction & Fertility special collection on 'Immune Regulation and Inflammatory Mechanisms in Reproductive Health and Disease' sheds light on the interplay between the immune system and reproductive health, highlighting contemporary concepts of immune regulation and inflammatory mechanisms and potential roads for therapeutic and diagnostic innovation. Despite the ongoing gaps, the field is experiencing an exciting bloom in the understanding of mechanisms underlying the contributions of the immune system to reproduction.

LAY SUMMARY: Beyond sex hormones and reproductive organs, reproductive health relies on the proper function of the immune system. Under normal conditions, the immune system protects the body from pathogens and other threats while recognizing the self. In reproductive organs, the immune system must also support the development of sperm and oocytes, as well as fertilization and pregnancy. Thus, infections and inflammation in reproductive organs may lead to infertility and problems during pregnancy. This commentary introduces a special collection in Reproduction & Fertility on the relationship between the immune system and the male and female reproductive tracts. This special collection includes articles showing how immune responses can help or harm fertility and explores new ways to diagnose and treat reproductive disorders, with the goal of improving reproductive health.