A potential new approach for treating systemic sclerosis: Dedifferentiation of SSc fibroblasts and change in the microenvironment by blocking store-operated Ca2+ entry.

Transforming growth factor-β (TGF-β) is an important target for treating systemic sclerosis (SSc). However, our study revealed three levels of TGF-β1 expression in SSc patients, indicating that inhibiting TGF-β is not sufficient to treat SSc. A previous clinical trial also displayed disappointing results. Thus, our study attempted to search for a potential novel approach. Ingenuity Pathway Analysis (IPA) indicated that the SSc pathological pathways were closely associated with store-operated Ca2+ entry (SOCE)-regulated signals, and SOCE activity was found to be increased in SSc fibroblasts. Further treatment of SSc fibroblasts with SOCE inhibitors, 2APB, and associated calcium channel inhibitors SKF96365, and indomethacin, showed that the SOCE inhibitors selectively decreased fibrosis markers and altered the cell morphology. Consequently, SOCE inhibitors, especially 2APB and indomethacin, caused the dedifferentiation of SSc fibroblasts via cytoskeleton remodeling and altered collagen secretion and restored the cell mobility. We further explained SSc pathogenesis as fibroblast differentiation with SOCE. Treatment with exogenous factors, gelatin-1, FAM20A and human albumin, which were identified from the conditioned medium of SSc fibroblasts, was important for regulating the differentiation of fibroblasts with higher levels of SOCE and α-SMA. Conclusively, to treat SSc, blockage of the increased SOCE activity in SSc induces the dedifferentiation of SSc fibroblasts and simultaneously changes the extracellular matrix (ECM) structure to limit SSc pathogenesis.