Sex differences in spontaneous versus induced animal models of autoimmunity

There is a supposed link between autoimmune diseases and sex hormones. To better understand the pathogenesis of human autoimmune diseases, an animal model is a good tool that can also help in developing novel therapeutics for diseases. Animal models of diseases can be divided into naturally occurring or induced by physical, chemical, or biological factors. Most human autoimmune diseases like systemic lupus erythematosus (SLE), Sjogren's syndrome (SS), primary biliary cirrhosis (PBC), Hashimoto's thyroiditis (HT), rheumatoid arthritis (RA), and multiple sclerosis (MS) have increased incidence and prevalence in females, but so far, sex differences and hormone therapy in spontaneous or chemical induced animal models of autoimmunity are not entirely clear. Possible reasons for the differing incidence and prevalence of autoimmune diseases in human and animal models is the focus of interest. This review described the known effects of the female sex hormones, estrogen and progesterone, on immune cells in order to clarify sex differences in autoimmune diseases. Data from both human and autoimmune animal studies were reviewed to determine reasons for these differences, and to integrate the role of sex differences and hormone therapy in spontaneous- versus chemical-induced animal models of human autoimmune diseases to clarify sex differences in autoimmunity.