Collagen cross-linking by pyridinoline occurs in non-reversible skin fibrosis.

The extent of the covalent cross-linking of collagen molecules by pyridinoline was measured in skin lesions from patients with chromomycosis, a chronic fungal infection leading to an extensive and chronic dermal fibrosis. These data were compared to those collected from patients with a localized cutaneous leishmaniasis, an acute inflammatory process leading to an extensive and reversible remodelling of the extracellular matrix. The amount of the mature cross-linking amino acid pyridinoline increased in chromomycosis patients when compared to controls and was significantly higher than in leishmaniasis patients. These data confirm and extend our previous studies on liver fibrosis showing that a high level of pyridinoline is associated to irreversible fibrotic lesions. They also suggest that an increase in the mature collagen cross-linking by pyridinoline in the course of fibrosis is not restricted to liver, but might be a general feature of irreversible and chronic fibrosis.