A balance between pathogenic and regulatory cells is crucial for the control of autoimmune disease development.  Indeed, a dysregulation of the immune response, including aberrant regulatory cell and antigen presenting cell (APC) function, plays a major role in the induction of diabetes in NOD mice and lupus in (NZWxNZB)F1 mice.  In these mice, the deficiency in CD4+CD25+ regulatory T cell number and function, as well as the presence of APC exhibiting pro-inflammatory characteristics, lead to the induction of pathogenic  cells.  Microorganisms have been shown to prevent diabetes and lupus development, and are capable of evading immune response via induction of tolerogenic APC and regulatory cells. Therefore, developing strategies that enhance tolerogenic APC and the levels and activity of this regulatory T cell population could lead to the prevention and amelioration of these autoimmune diseases, e.g., enhancing immunoregulation in autoimmune-prone mice using components of the gut microbiota or natural anti-inflammatory compounds such as curcumin.