Extracellular Matrix Biomarker, Fibulin-1 and Its Association with Soluble uPAR in a Bi-ethnic South African Population: The SAfrEIC Study

Background Fibulin-1 and soluble urokinase-type plasminogen activator receptor (suPAR) emerged as mediators in the development of sclerotic disease. SuPAR along with C-reactive protein (CRP) and albumin delineate inflammatory processes associated with extracellular matrix turnover in atherosclerosis. We explored the independent relationship of fibulin-1 with these inflammatory markers in a bi-ethnic South African population. Methods This study included 290 Africans (men: n = 130 and women: n = 160) and 343 sex-and age-matched Caucasians (men: n = 160 and women: n = 183). Serum fibulin-1, suPAR, CRP and albumin levels were measured along with conventional cardiovascular and metabolic variables. Results In both single and age-adjusted regression analyses, fibulin-1 correlated with both suPAR and albumin in African men and with suPAR in Caucasian men. These findings were absent in women. In multivariate regression analysis, these associations were confirmed in African men (R-2 = 0.22; beta=0.329; p < 0.001) and Caucasian men (R-2 = 0.14; beta=0.234; p = 0.008). Fibulin-1 independently associated positively with suPAR in all men, but inversely with albumin in African men only. Conclusions These results are indicating the presence of potential subclinical inflammation (suPAR) within the extracellular matrix of endothelial tissue, contributing to the potential onset of cardiac fibrosis or vascular sclerosis among these South African men with lower albumin levels.