Objectives: SSc is associated with an increased prevalence of atherosclerosis (ATS). This study assessed the prevalence of subclinical ATS as measured by carotid US and explored serum proteins to identify potential biomarkers of SSc-ATS.
Methods: Forty-six SSc female patients and 46 age- and ethnicity-matched controls underwent carotid US to assess the presence of plaque and carotid intima media thickness (CIMT). Abstracted data included demographics, ATS risk factors and serum measurements [cholesterol, proinflammatory high-density lipoprotein (piHDL), CRP, lipoproteins]. Serum cytokines/proteins analyses included circulating type I IFN activity by quantifying IFN-inducible genes, soluble junctional adhesion molecule A (sJAM-A) and 100 serum proteins by using a microplate-based multiplex platform. Proteins significant at P < 0.05 on bivariate analyses for the presence of plaque were used to develop a composite measure.
Results: Patients with SSc had more plaque (45.6% vs 19.5%, P = 0.01) but similar CIMT compared with controls. Multiplex analysis detected significant associations between serum proteins of inflammation, vasculopathy and fibrosis with ATS in SSc, including IL-2, IL-6, CRP, keratinocyte growth factor, intercellular adhesion molecule 1, endoglin, plasminogen activator inhibitor 1 and insulin-like growth factor binding protein 3 associated with carotid plaque. Myeloid progenitor inhibitory factor 1, serum amyloid A, thrombomodulin, N-terminal pro-brain natriuretic peptide (BNP), and Clara cell secretory protein 16 kD correlated with CIMT. The median composite score for the plaque group was 6 and for the no plaque group it was 2 (P < 0.0001).
Conclusion: Patients with SSc have a higher prevalence of carotid plaque than matched controls, and patients with SSc-plaque vs patients without plaque have elevated serum proteins implicated in both vasculopathy and fibrosis. Further studies are needed to evaluate the role of these proteins in SSc compared with healthy controls.
Keywords: atherosclerosis; carotid intima media thickness; endothelial dysfunction; serum proteins; systemic sclerosis; type I interferon.