Characteristics of epidermolysis bullosa skin fibroblasts in vitro
Epidermolysis bullosa (EB) is a heterogeneous group of rare hereditary mechanobullous diseases. Three different sub-groups exist: simplex (EBS), with blistering within the epidermis; junctional (EBL) with blistering at the dermo-epidermal junction and dystrophic, either dominantly (EBDD) or recessively (EBDr) inherited where blisters form within the dermis. The aim of this project was to characterise collagen, collagenase and glycosaminoglycan (GAG) metabolism in fibroblasts cultured from the skin of patients with different forms of EB and to determine as far as possible how two drugs currently used to treat the disease, phenytoin and vitamin E, affect these functions. Thirty patients donated skin samples to establish fibroblast cultures and fibroblast lines were cultivated from 18 (7 from EBS, 6 from EBDr, 3 from EBDD and 2 from EBL)Twenty four skin samples were examined by electron microscopy for confirmation of diagnosis and to study certain ultrastructural features of the disease. No difference was found between the proliferation rates of any of the EB groups and an age-matched healthy control group (mean - SEM: 88 - 13%). Similarly no statistically significant difference was found between the GAG outputs of control and EB groups. Protein synthesis in the EB group differed significantly from the controls, with a selective increase in collagen synthesis over synthes of non-collagenous protein. Collagenase levels were highest in the EBDr fibroblast cultures and the bulk of the enzyme appeared to be in the active form. The EBS cultures gave collagenase levels which were intermediate between those of controls and EBDr, and most of the enzyme was in the latent form which requires activation by trypsin in vitro. Phenytoin did not affect the proliferation rate of any of the groups but vitamin E caused a significant increase in the rate of I proliferation of control fibroblasts. Phenytoin produced a decrease in protein synthesis at 300-500 μM. The effect of phenytoin on GAG output differed between groups; the drug increasing GAG accumulation in controls whilst depressing levels in the EBS group. Vitamin E did not directly affect GAG secretion.