CYTOKINES AND CORPUS-LUTEUM

This minireview present main findings concerning the contribution of c ytokines to the regulation of some key processes of luteal functions. Data concerning the prevulatory follicles invasion by white blood cell s and the migration of macrophages, granulocytes and T lymphocytes int o corpus luteum suggest that local secretion of regulatory cytokines m ay be involved in regulating corpus luteum formation and demise as wel l its maintenance in early pregnancy. Several lines of evidence indica te that the pro-inflammatory cytokines such as IL-1, IL-6 and TNF-alph a modulate the steroidogenic changes which take place during luteiniza tion. For instance, an inhibition of E2 biosynthesis is evidenced in g ranulosa cells in human or porcine species with IL-1, in rat with TNF- a and in bovine with IL-6. Moreover, IL-1 stimulates P4 production but to a much lower extent than LH, and PGE2 synthesis by rat thecal cell s. The potential relevance of pro-inflammatory cytokines in the mechan isms controlling luteolysis is suggested by the ability of IL-1 and TN F-alpha to decrease both P4 production and the survival of bovine lute al cells. As opposed to ruminants, TNF-alpha has no effect in human lu teal cells but potentiates the decrease of P4 secretion induced by IFN -gamma. Finally, data regarding the participation of trophoblast inter ferons in the mechanisms for maintaining the corpus luteum at the esta blishment of pregnancy are now available in ruminants. From these obse rvations and others, we can consider that cytokines are involved in th e regulation of the corpus luteum function.