Radicals, granuloma formation and fibrosis

Abstract

A granuloma is a chronic inflammatory lesion characterized by large numbers of cells of various types (macrophages, lymphocytes, giant cells, fibroblasts) some degrading and some repairing the tissues. Fibrosis is an excessive and persistent accumulation of collagen producing cells — fibroblasts, and their matrix — predominantly Type I collagen. Fibrosis can affect nearly every organ of the body, including the skin. Examples include adhesive capsulitis of the shoulder, Dupuytren’s contracture of the hand and foot, cystic fibrosis of the lung and cirrhosis of the liver. Important components of normal wound healing include an infiltration and proliferation of fibroblasts and synthesis of matrix by these cells. Thus the biochemical and histological features of normal wound healing and fibrosis are analogous, with the somewhat arbitrary distinction that in fibrosis there is a persistence of these features — particularly collagen accumulation, and there is no return to “normal” or “baseline” biochemistry and morphology.