Cytokine Gene Expression and Distribution of Inflammatory Leukocytes in the Periimplantation Mouse Uterus

During both the estrous cycle and pregnancy, the uterus undergoes significant changes that have many similarities to inflammatory processes. These changes include edema, prostaglandin and leukotriene production, neovascularization, and infiltration of blood-borne cells including macrophages (1), lymphocytes (2), neutrophils (3, 4) and eosinophils (5); each of these responses occurs as part of the normal physiology of this organ. Leukocyte influx in the rodent uterus occurs in response to estrogen in ovariectomized adult and in immature animals (5), and this infiltration resembles one of the major events in a classical inflammatory response (6). Classical inflammatory processes entail complex interactions between many cell types and involve not only the infiltration, but also the activation of leukocytes. The concomitant production of various soluble mediators, including macrophage-derived cytokines (7, 8), is central to the inflammatory response. Although the presence of macrophages and other inflammatory cells within the endometrial stroma has been detected by morphological and histochemical means, their activation in the uterus during early pregnancy has not been examined.