Alteration of Collagen Composition and Cross-Linking in Keloid Tissues

Abstract

Collagen composition and cross-linking in human keloid and normal skin tissues were analyzed biochemically.CNBr peptides were separated by 2-dimensional (2-D) mapping and high performance liquid chromatography (HPLC).The amounts of type I and type III collagen was quantified by 2-D scanning densitometry of flourographs of 2-D maps derived from samples radioactively labelled in vitro by [3H]-NaBH4 in dimethylformamide.Keloid tissues contained 31.6 ± 2.2 percent type III collagen as compared to 21.4 ± 2.7 percent type III present in normal human skin dermis.HPLC profiles of CNBr pep tides showed that approximately 5 percent of the high molecular weight material in keloids is mercaptoethanol reducible, compared to insignificant amounts in normal skin.2-D maps derived from CNBr peptides of keloid collagen demonstrated thiol reduction sensitive αl(III)-CB9 dimer as well as 24,000- and 32,000-dalton CNBr peptides, which were not mercaptoethanol reduction sensitive in normal skin due to crosslinking via the lysyl oxidase pathway.Also, a group of 20,000- to 25,000-dalton CNBr peptides, in the α1 (1)-CB6 cross-linking region were prominent in keloid tissues.