Extracellular Matrix: Immunity and Inflammation

The extracellular matrix (ECM) is the non-cellular component of any tissues and organs. It provides not only support, tensile strength, and scaffolding for tissues and cells, but also biochemical signals and specialized proteins. The destabilization or alteration of the ECM structural and chemical composition affects growth, morphogenesis, differentiation, migration, communication, survival of all cells as well as inflammation and immune response. Inflammation is a complex defense mechanism characterized by leukocyte migration from the vasculature to control tissue damage induced by pathogenic (bacterial or viral), traumatic, or toxic injury with subsequent deposition of extracellular matrix resulting in tissue repair. At sites of injury, phagocytic cells, namely macrophages and neutrophils, provide innate cell-mediated immunity, and immune cells are influenced in their migration by the topography and composition of the matrix architecture. The physical and biochemical ECM properties are also able to modulate a number of processes in immune cells, especially lymphocytes that can ultimately lead to inefficient immune response. Among the large number of molecules responsible for ECM homeostasis, matrix metalloproteinases, versican, hyaluronan, and thrombospondins are the most involved in inflammation and immunity.