[Collagen metabolism in hypertrophic and keloid scars]

Imbalance between the synthesis and degradation of collagen is a common sign of tissues of hypertrophic and cheloid scars. The fact that the collagen of abnormal scars of the both types have a polyfunctional linkage with a structure of pyridinol and high amounts of a polyfunctional linkage with a structure of pyrrole (Ehlich's chromogen) in the collagen of cheloid scars support the assumption that the collagen synthesis-degradation imbalance may be due to the enhanced resistance of structurally unchanged collagen to collagenolytic enzymes. The comparative studies of the ratio of type 1 collagen homotrimers to heterotrimers, that of type 1 collagen dimers to monomers, and that of types 1 to type 3 collagen in the pepsin extracts of abnormal scars of various age and patients' intact skin suggest that there are certain differences in the magnitude and scar age-related changes in the expression of collagen genes and posttranslational collagen modifications in the tissue of hypertrophic and cheloid scars. It is suggested that age-specific time course of collagen metabolic and structural changes in the abnormal scars may result from their alterations of the population composition of fibroblasts with a different phenotype.