Prediction of organ involvement in systemic sclerosis by serum biomarkers and peripheral endothelial function

To identify prognostic factors among serum biomarkers and endothelial vasodilator function findings in patients with systemic sclerosis (SSc). This is a clinical observational study. We assessed 60 consecutive SSc patients (44 limited cutaneous-type, 16 diffuse cutaneous-type). Circulating growth differentiation factor-15 (GDF-15), placenta growth factor (PlGF), endostatin, vascular endothelial growth factor (VEGF), and pentraxin 3 (PTX3) were measured by ELISA. Peripheral endothelial function was measured by forearm blood dilatation response to brachial artery occlusion using noninvasive plethysmography (EndoPAT2000), which is associated with nitric-oxide-dependent vasodilatation and yields a reactive hyperemia index (RHI). We evaluated whether abnormalities in these values were associated with type of SSc - namely, diffuse cutaneous SSc (dcSSc) or limited cutaneous SSc (lcSSc) - or organ involvement including interstitial lung disease (ILD), digital ulcer (DU) and estimated right ventricular systolic pressure (RVSP) by echocardiography >30 mmHg. SSc patients showed significantly elevated serum GDF-15, PlGF, endostatin and VEGF but not PTX3 compared with controls. GDF-15 and PlGF were high in dcSSc patients. EndoPAT-RHI was low, and incidence of RVSP >30 mmHg was high in dcSSc. Multivariate analysis revealed that elevated GDF-15 was highly predictive of dcSSc, ILD or RVSP >30 mmHg. PlGF for DU was also found. Conversely, a low EndoPAT-RHI value was predictive of the presence of dcSSc, ILD or DU. This is the first study to inclusively investigate the relationships among biomarkers, EndoPAT-RHI and organ involvement in patients with SSc. Our data suggest a complex pathological progression of SSc through fibrotic impairment and microvascular damage.