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

OBJECTIVES: To identify prognostic factors among serum biomarkers and endothelial vasodilator function findings in patients with systemic sclerosis (SSc).

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.