Skin immunity during pregnancy

Abstract Pregnancy presents a challenging immunological dilemma. The maternal immune system must tolerate fetal antigens, which implies pregnancy may induce specific mechanisms of immunoregulation. Yet within this regulatory milieu, protection against pathogens must be maintained. How does the maternal immune system navigate these opposing demands? Successfully navigating this immunological dilemma is essential for supporting the reproductive fitness of the organism, and generally, the survival of any mammalian species. Of particular importance in this context are barrier tissues, like the skin, which represent the primary portal of entry for pathogens. These barrier tissues are an especially important first line of defense during pregnancy, since adaptive immunity must be regulated to tolerate the fetal antigens which distribute throughout maternal tissues. However, little is known about how immunity in barrier tissues is altered during pregnancy. Our preliminary studies have identified an increase in ceramide levels in the skin during pregnancy. Ceramides have been shown to be critical mediators of skin barrier function, and may prevent pathogens from breaching the skin. Additionally, in the setting of S. aureus infection, pregnant skin demonstrated increased infiltration of innate immune cells, as well as an increase in type I immunity among adaptive cells. Together, these data suggest that the protective mechanisms of the skin are altered during pregnancy. Further insights in this area may elucidate an especially critical role for barrier tissue immunity in defending against infection during pregancy, and may eventually help guide improved clinical strategies to prevent and treat infections in pregnant mothers. Supported by Perelman School of Medicine's Medical Scientist Training Program and intramural research funding from NIAID.