Surface Expression of Fractalkine Receptor (CX3CR1) on CD4+/CD28− T Cells in RA Patients and Correlation with Atherosclerotic Damage

Abstract

Rheumatoid arthritis (RA) is associated with accelerated atherosclerosis. Fractalkine, a CX3C/chemokine (CX3CL1), mediates monocytes-macrophage infiltration in activated endothelium, suggesting its specific role in atherosclerosis-related inflammation. In this study, we evaluate the following in early RA patients: the expression of fractalkine receptor (CX3CR1) on CD4+/CD28- T cells, a subset involved in atherosclerotic infiltration; the correlation between this subset and validated markers of early atherosclerosis. CD4+ T cells were isolated by immunomagnetics beads in 50 early RA patients and 26 healthy controls (HC). After isolation, CD4+/CD28-/CX3CR1+ T lymphocytes were assessed by FACS analysis. Endothelial dysfunction was evaluated by both carotid intima-media thickness (IMT) and flow-mediated vasodilation (FMV). We observed: a higher expansion of CD4+/CD28- subset in RA patients when compared to HC (7.7%, 5.15-9.7 vs. 0.7%, 0.2-1.5, P < 0.01; respectively); this expansion directly correlated with increased IMT (0.91 mm, 0.5-1.3 vs. 0.7 mm, 0.2-1, P < 0.01; RA vs. C, respectively) and inversely correlated with FMV (3.5%, 1.7-7 vs. 9%, 3.5-11, P < 0.01; RA vs. C, respectively); the large majority of CD4+/CD28-, in RA, coexpressed CX3CR1 (93%, 67-99 vs. 30%, 10-48, P < 0.01; RA vs. C, respectively); this expansion significantly correlated with both the parameters of premature vascular damage and DAS 28. Our data suggest that CX3CL1/CX3CR1 axis might play a role in the induction and development of the endothelial dysfunction during RA.