Connective tissue in skin biopsies from patients suffering systemic sclerosis

Little information is available on elastin during systemic sclerosis since biochemical and morphological data have primarily focused on collagen and glycosaminoglycan alterations of connective tissues in this pathological process. We performed ultrastructural, morphometric, biochemical and in situ hybridisation analyses on skin biopsies from patients affected by scleroderma and from site and age-matched control subjects. Affected skin revealed alterations in the distribution and organisation of collagen bundles and fibrils together with zonal increase of the microfibrillar component. Elastic fibres were significantly more numerous than in control skin, were more frequently vacuolated and characterised by electron-dense inclusions; moreover, morphometric analysis provided evidence for a significant increase of the percentage of both collagen bundles and elastin fibres in the measured tissue, compared to normal skin. Biochemical analysis seemed to confirm the increased elastin content per unit of dried weight tissue in sclerodermic skin. Differences observed among patients were only partially associated with disease duration and/or to severity of clinical manifestations. The abnormal amount of elastic fibres observed in skin biopsies from patients, and data from in situ hybridisation suggest the presence of a deregulation of the whole extracellular matrix that might be related to the role of cytokines such as TGF-beta, which has already been suggested to be involved in systemic sclerosis and in enhanced collagen and elastin production.