Oestrogens in rheumatic diseases: friend or foe?

Immunological and epidemiological evidences suggest that female sex hormones play an important role in the aetiology and pathophysiology of chronic inflammatory diseases; however, whether (or when) oestrogens are friends or foes in inflammatory/immune-mediated rheumatic diseases is still a matter of debate. Several significant factors generate confusion and opposite conclusions in evaluating the role of oestrogens in inflammatory/immune diseases. These factors include the relatively superficial translation done from the animal studies to the human condition, the different effects of oestrogens on their different receptors or on different target cells, the different oestrogen concentrations employed and finally, opposite effects (especially on cell proliferation) exerted by different peripheral oestrogen metabolites. However, as supported by the higher prevalence of rheumatic autoimmune diseases in women, oestrogens are generally considered as enhancers of cell proliferation and humoral immune response.