Cholesterol crystals use complement to increase NLRP3 signaling pathways in coronary and carotid atherosclerosis

Abstract

Background During atherogenesis, cholesterol precipitates into cholesterol crystals (CC) in the vessel wall, which trigger plaque inflammation by activating the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome. We investigated the relationship between CC, complement and NLRP3 in patients with cardiovascular disease. Methods We analysed plasma, peripheral blood mononuclear cells (PBMC) and carotid plaques from patients with advanced atherosclerosis applying ELISAs, multiplex cytokine assay, qPCR, immunohistochemistry, and gene profiling. Findings Transcripts of interleukin (IL)-1beta(β) and NLRP3 were increased and correlated in PBMC from patients with acute coronary syndrome (ACS). Priming of these cells with complement factor 5a (C5a) and tumour necrosis factor (TNF) before incubation with CC resulted in increased IL-1β protein when compared to healthy controls. As opposed to healthy controls, systemic complement was significantly increased in patients with stable angina pectoris or ACS. In carotid plaques, complement C1q and C5b-9 complex accumulated around CC-clefts, and complement receptors C5aR1, C5aR2 and C3aR1 were higher in carotid plaques compared to control arteries. Priming human carotid plaques with C5a followed by CC incubation resulted in pronounced release of IL-1β, IL-18 and IL-1α. Additionally, mRNA profiling demonstrated that C5a and TNF priming followed by CC incubation upregulated plaque expression of NLRP3 inflammasome components. Interpretation We demonstrate that CC are important local- and systemic complement activators, and we reveal that the interaction between CC and complement could exert its effect by activating the NLRP3 inflammasome, thus promoting the progression of atherosclerosis.

Identification of Potential Key Genes Involved in the Carotid Atherosclerosis

“…The genes (CD33, CD53, CYBB, FCER1G, FPR2, LILRB2) enriched for immunity-related genes. In carotid plaques, C3aR1 26 and FCER1G 27 is higher compared to control arteries. CCR1 alters the immuno-inflammatory response in atherosclerosis.…”

Identification of key pathways and genes in carotid atherosclerosis through bioinformatics analysis of RNA-seq data

“…Inflammation-induced by cholesterol crystals (CC) is the crucial step in the progression of CAS. CCs mediate complement activation and induce plaque inflammation by activating NACHT, LRR, and PYD domains harboring protein 3 (NLRP3) [ 25 ]. Elsewhere, Gregersen reported that plasma IL-27 levels in CAS patients were significantly higher than that of normal subjects.…”

Bioinformatics analysis of common differential genes of coronary artery disease and carotid atherosclerosis

“…Complement C5a Receptor 1 (C5AR1) combines with complement C5a to recruit monocytes and neutrophils, which are involved in a variety of in ammatory disease processes. In patients with carotid artery plaque, C5a, C5AR1,and the release of IL-1β, IL-18 and IL-1α34 28 are signi cantly increased compared with healthy carotid artery tissue, indicating C5AR1 may be a promoter in progression of atherosclerosis.…”