Fibroblast expression of CD248 may contribute to exacerbation of microvascular damage during systemic sclerosis.

OBJECTIVES: CD248 is a glycoprotein, highly expressed on pericytes and fibroblasts (FBs), that is implicated in the fibrotic process. During angiogenesis, CD248 can promote vessel regression, binding multimerin-2 (MMRN-2). Thus, we investigated the expression of MMRN-2 in systemic sclerosis (SSc)-skin and of CD248 in isolated SSc-FBs. The anti-angiogenic property of CD248+ SSc-FBs was evaluated by co-culturing these cells with healthy control endothelial cells (HC-ECs). The apoptotic effect of CD248 on HC-ECs was evaluated. Finally, the ability of CD248 to prevent activation of VEGF receptor 2 (VEGFR2) was assessed. METHODS: By IF, MMRN-2 was investigated in SSc-skin and CD248 in SSc FBs. The anti-angiogenic property of CD248+ SSc-FBs was evaluated by HC-ECs/SSc-FBs co-cultures. Lentiviral-induced CD248 short-hairpin RNA delivery was employed for loss-of-function studies in SSc-FBs. HC-ECs were cultured in the presence of CD248 to assess apoptosis by IF and VEGFR2 phosphorylation by western blot. RESULTS: MMRN-2 expression was increased in skin SSc-ECs, whereas CD248 expression was increased in SSc-FBs. Functionally, CD248+-SSc-FBs suppressed angiogenesis in the organotypic model, as assessed by the reduction in total tube length of HC-ECs. This anti-angiogenetic behaviour was reversed by CD248 silencing. Furthermore, the presence of CD248 promoted the apoptosis of HC-ECs. Finally, CD248 prevented activation of VEGFR2 by reducing its phosphorylation after VEGF stimulation. CONCLUSION: CD248 was anti-angiogenic in vitro due to a reduction in tube formation and to induction of apoptosis of ECs. Increased expression of CD248 in SSc could contribute to the microvascular rarefaction observed at the tissue level in SSc. Our results suggest a pathogenic role for CD248-MMRN-2 in SSc.