Increased levels of the homeostatic chemokine CXCL13 in human atherosclerosis - Potential role in plaque stabilization

ObjectivesBased on the newly recognized role of the homeostatic chemokines in inflammation, we hypothesized that CXCL13 could modulate atherogenesis and plaque destabilization.MethodsThe study included in vivo analyses in patients with carotid atherosclerosis and in vitro experiments in cells involved in atherogenesis (ie, monocytes/macrophages, vascular smooth muscle cells SMC], and platelets).ResultsOur main findings were: (i) Patients with carotid atherosclerosis (n = 130) had increased plasma levels of CXCL13 with particularly high levels in symptomatic disease. (ii) CXCL13 showed increased expression within atherosclerotic carotid plaques as compared with non-atherosclerotic vessels. (iii) Within the atherosclerotic lesions, CXCR5 and CXCL13 were expressed by macrophages and SMC in all stages of plaque progression. (iv) Releasate from activated platelets and toll-like receptor activation enhanced the expression of CXCL13 in THP-1 monocytes and primary monocytes. (v) In vitro, CXCL13 exerted anti-apoptotic effects in primary monocytes, THP-1 macrophages, and vascular SMC. (vi) CXCL13 increased arginase-1, transforming growth factor-β, and interleukin-10 expression in THP-1 cells and in samples from isolated carotid plaques.ConclusionLevels of CXCL13 are increased in carotid atherosclerosis both systemically and within the atherosclerotic lesion. Based on our in vitro findings, we hypothesize a potential plaque stabilizing effects of CXCL13-CXCR5 interaction.