Hormonal control of collagen metabolism. Part II.

Natural and synthetic glucocorticoids are known to effect collagen metabolism. This influence is responsible for several side-effects of a long term therapy with glucocorticoids. Molecular mechanisms of these phenomena are complex, and are only partially elucidated. It has been found that glucocorticoids decrease amount of mRNA coding procollagen chains. Posttranslational modifications including hydroxylation of proline and lysine residues and glycosylation of hydroxylysine residues in procollagen are depressed by glucocorticoids. This is caused by depressed activity of the specific enzymes of intracellular stages of collagen biosynthesis. Extracellular maturation of collagen is affected by steroids but changes reported depend upon rate of the collagen turnover. The effect of glucocorticoids on collagen degradation is a subject of controversy; there are a few data that the hormones decrease activity of collagenolytic enzymes. Possible indirect mechanisms of effect of glucocorticoids on the collagen metabolism include modulatory role of these hormones in inflammatory cell activity as well as a release of various humor mediators. Pathophysiological aspect of hormonal regulation of collagen metabolism by glucocorticoids in hepatic and pulmonary fibrosis as well as keloids are also reviewed.