Although SSc is heterogeneous in the extent of organ involvement and prognosis, it is accepted that all SSc cases have a progressive and usually devastating course. Since vasculopathy precedes fibrosis in this disease, a focus on understanding its natural history and preventative measures for vascular dysfunction has profound implications. This pilot work suggests that measurement of endothelial dysfunction with flow mediated dilatation (FMD) holds promise as novel method to assess disease progression as well as the therapeutic efficacy of the pharmacologic compound tetrahydrobiopterin (BH4) in SSc. The investigators believe that BH4, which targets the endothelium, has great promise to reduce SSc-related tissue hypoxia, end organ damage, and potentially may impact underlying disease progression. The first aim will adopt an integrative approach and validate a novel, non-invasive technique, FMD to define vasculopathy in SSc. The second aim and third aim (which is reported in this PRS report) will examine if BH4 is effective in ameliorating vascular dysfunction in patients with SSc and determine the role of oxidative stress in BH4-mediated improvements in vascular function in patients with SSc. The overarching goal of these aims is to improve vasculopathy detection and management in Veterans with SSc.
