Innate immune response in systemic autoimmune diseases: a potential target of therapy.

Innate immunity refers to defense mechanisms that are always present, ready to combat microbes and other offending agents. Innate immunity acts as a first-line defense and activates the conventional immune responses; however, it has been speculated that the importance of innate immunity in initiation and development of some disorders is more than just the "first line of defense". Autoimmune diseases, caused by immune system overactivation, are among the most challenging scientific and clinical problems, and there is still much to be learned about their pathogenesis. We aimed to provide a comprehensive overview of available documents about the role of innate immunity in systemic autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, polymyositis, and systemic sclerosis. This study highlights the innate immunity pathways or molecules that are under investigation for therapy of these diseases.