SIRT1 and systemic sclerosis: Circulating levels of SIRT1 were significantly decreased in SSc patients (median 0.94 ng/mL, IQR 0.53–1.59 ng/mL) compared to healthy controls (median 1.38 ng/mL, IQR 0.84–3.72 ng/mL; p < 0.001; Figure 1A).