The Role of Cholesterol Crystals in increase of NLRP3 Inflammasome affecting Coronary Artery Disease & Carotid Atherosclerosis
Reporters: Justin D. Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN
The Voice of Dr. Justin D. Pearlman, MD, PhD, FACC
The study published in Lancet https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(20)30361-3/fulltext
shows plausible evidence for a sequence of events following atheroma crystal formation in blood vessel walls leading to inflammation and consequential injuries from atherosclerosis. The liquid crystal behavior of atheroma was first demonstrated in original PhD dissertation by JDPearlman MD PhD who demonstrated that 0.5 C temperature shift at body temperature converts the physical state of atheroma lipids to crystalline, known as liquid-crystal behavior, and studies he performed with NMR (nuclear magnetic resonance) and EPR (electron paramagnetic resonance) demonstrated that triglyceride levels impact the transition temperature. The current study shows a cascade of responses to the atheroma crystallization that leads to damaging inflammation and risk of acute obstruction. In particular, the current study demonstrates accumulation of blood complement factor complexes C1q and C5b-9, along with increases in complement receptors C5aR1, C5aR2 and C3aR1. Priming human carotid plaques with C5a followed by cholesterol crystal incubation resulted in pronounced release of interleukins IL-1β, IL-18 and IL-1α. Further understanding of the dominant pathways linking atheroma crystallization to unstable plaque with clinical consequences (heart attack, stroke) points to additional opportunities for medication or gene therapy to mitigate the harm.
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.
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