Connective tissue diseases (CTDs) are systemic autoimmune disorders characterized by a large spectrum of clinical features and multisystemic involvement. Connective tissue disease is any disease that has the connective tissues of the body as a target of pathology.
Connective tissue is any type of biological tissue with an extensive extracellular matrix that supports, binds together, and protects organs. These tissues form a framework, or matrix, for the body, and are composed of two major structural protein molecules: collagen and elastin.
Autoimmunity involves the loss of normal immune homeostasis such that the organism produces an abnormal response to its own self tissue. The hallmark of autoimmune diseases generally involves the presence of self-reactive T cells, autoantibodies and inflammation