Functional changes in scleroderma fibroblasts co-cultured with autologous peripheral blood mononuclear cells (PBMCS)

Introduction: Increasing evidence suggest that an interplay between T cells and fibroblasts plays a pivotal role in promoting matrix accumulation in systemic sclerosis (SSc). Aim: We investigated if the co-culturing of fibroblasts derived from SSc patients with autologous PBMCs could induce peculiar modifications in any cell types. Materials and methods: Fibroblasts were obtained from the skin of patients undergoing biopsy for diagnostic purposes. PBMCs were obtained from the same patients. All the patients were fully informed of the meaning of the study and accepted to donate blood. Cells were taken in culture at 37 ˚C5% CO2 for ten days, then cells were stained with monoclonal antibodies for HLA-DR, CD3, CD4, CD56, CD95, TCRab, TCRcd, After the staining, cells were analyzed by flow-cytometry using a FACScalibur. Results: We found that T cells bearing an ab receptor were expanded in the co-cultures. Moreover, these cells were positive for the expression of HLA-DR, suggesting an activation of T cells induced by co-culturing with autologous fibroblasts. No expansion of cd T cells nor CD56 positive T cells was found. SSc fibroblasts, which have already been reported to have a basal high expression of CD95 (FAS), were found to up-regulate FAS in these experiments. Conclusions: We recently showed that peripheral blood T cells from SSc patients expand when co-cultured with autologous fibroblasts and acquire the same T cell clonotypes that are increased in the affected skin. The results presented here further support that such expansion may be due to a specific antigenic activity of fibroblasts on T cells. In addition, the up-regulation of FAS expression on SSc fibroblasts may be related to phenotypic changes that indicate an increased ability of these cells to escape normal pathways leading to cell death. The meaning of these findings in the pathogenesis of SSc remains to be further investigated.