Plasma osteopontin versus intima media thickness of the common carotid arteries in well-characterised patients with systemic lupus erythematosus

Objective: The progress of accelerated atherosclerosis in systemic lupus erythematosus (SLE) is incompletely understood. Circulating osteopontin (OPN) is increased in autoimmune conditions, e.g. SLE, and its serum concentration wasrecently reported to associate with subclinical atherosclerosis in SLE, as measured by carotid intima-media thickness.The aim of this study was to investigate whether OPN may be used as a surrogate biomarker of subclinical atherosclerosis in SLE patients with different disease phenotypes.Methods: We recruited 60 well-characterised SLE cases and 60 age- and sex-matched healthy controls. The SLE caseswere divided into three different disease phenotypes: SLE with antiphospholipid syndrome (APS), lupus nephritis, andisolated skin and joint involvement. Plasma OPN was detected by ELISA (QuantikineVR, R&D Systems). Common carotidarteries intima media thickness was compared between the studied groups in relation to OPN levels and risk factors forvascular changes. Intima media thickness of common carotid arteries was measured by using a sensitive ultrasoundtechnique (LOGIQTM E9 ultrasound, GE Healthcare).Results: OPN levels were significantly higher among the entire SLE group (n ¼ 60) compared to the healthy controls(P ¼ 0.03). SLE cases with concomitant APS (n ¼ 20) showed higher OPN levels than the controls (P ¼ 0.004), whereasnone of the other two subgroups differed significantly from the healthy controls. OPN and intima media thickness werecorrelated to several traditional risk factors of atherosclerosis, as well as to SLE-related factors. Yet, no significantcorrelation was observed between OPN levels and ultrasound findings of the common carotid arteries.Conclusions: In line with previous studies, we observed increased OPN levels among SLE patients as compared tomatched controls. However, the OPN concentrations did not correlate with intima media thickness of the commoncarotid arteries. Based on our findings, the use of OPN as a surrogate biomarker of subclinical atherosclerosis in SLEsubjects, regardless of clinical phenotypes, cannot be recommended.