Effect of estrogen and progesterone on macrophage activation during wound healing

Age-related impaired wound healing leads to substantial morbidity and mortality along with a large financial burden to health services. There is accumulating evidence that the tissue damage associated with chronic wounds is initiated and propagated by an inappropriately excessive inflammatory response. Research on age-related impaired wound healing suggests that the decline in sex steroid hormones with age may have a substantial influence on the inflammatory response in vivo. Topical and systemic estrogen treatments have shown an increased rate of healing by reducing inflammation, however the underlying mechanisms are little understood. In vitro studies also suggest progesterone may play a role in modulating inflammation. Macrophages are essential mediators of inflammation and wound healing. Macrophages can be activated in a classical or alternative manner in parallel with the T(H)1/T(H)2 dichotomy, respectively. Using a murine incisional wound healing model this study was carried out to investigate the roles of estrogen and progesterone on macrophage activation during the wound healing response. Our findings suggest with a reduction of steroid hormones following ovariectomy, alternatively activated macrophage markers (Fizz1 and Ym1) were reduced, with this effect being reversed with the administration of estrogen or progesterone; suggesting that with the reduction of steroid hormones macrophages are activated in a classical manner, promoting inflammation, whereas estrogen or progesterone are contributing toward macrophage activation in an alternative manner, driving wound repair, angiogenesis, and remodeling.