RIPK1 Expression Associates With Inflammation in Early Atherosclerosis in Humans and Can Be Therapeutically Silenced to Reduce NF-κB Activation and Atherogenesis in Mice

Abstract

Background: Chronic activation of the innate immune system drives inflammation and contributes directly to atherosclerosis. Previously, we showed that macrophages in the atherogenic plaque undergo RIPK3-MLKL-dependent programmed necroptosis in response to sterile ligands such as oxidized LDL and damage-associated patterns (DAMPs) and necroptosis is active in advanced atherosclerotic plaques. Upstream of the RIPK3-MLKL necroptotic machinery lies RIPK1, which acts as a master switch that controls whether the cell undergoes NFκB-dependent inflammation, caspase-dependent apoptosis or necroptosis in response to extracellular stimuli. We therefore set out to investigate the role of RIPK1 in the development of atherosclerosis, which is largely driven by NFκB-dependent inflammation at early stages. We hypothesize that, unlike RIPK3 and MLKL, RIPK1 primarily drives NFκB-dependent inflammation in early atherogenic lesions and knocking down RIPK1 will reduce inflammatory cell activation and protect against the progression of atherosclerosis. Methods: We examined expression of RIPK1 protein and mRNA in both human and mouse atherosclerotic lesions, and using loss-of-function approaches in vitro in macrophages and endothelial cells to measure inflammatory responses. We administered weekly injections of RIPK1 anti-sense oligonucleotides (ASO) to Apoe -/- mice fed a cholesterol-rich (Western) diet for 8 weeks. Results: We find RIPK1 expression is abundant in early-stage atherosclerotic lesions in both humans and mice. Treatment with RIPK1 ASOs led to a reduction in aortic sinus and en face lesion areas (47.2% or 58.8% decrease relative to control, p<0.01) and plasma inflammatory cytokines (IL-1α, IL-17A, p<0.05) compared to controls. RIPK1 knockdown in macrophages decreased inflammatory genes (NFκB, TNFα, IL-1α) and in vivo LPS- and atherogenic diet-induced NF-κB activation. In endothelial cells, knockdown of RIPK1 prevented NF-κB translocation to the nucleus in response to TNFα, where accordingly there was a reduction in gene expression of IL1B, E-selectin and monocyte attachment. Conclusions: We have identified RIPK1 as a central driver of inflammation in atherosclerosis by its ability to activate the NF-κB pathway and promote inflammatory cytokine release. Given the high levels of RIPK1 expression in human atherosclerotic lesions, our study suggests RIPK1 as a future therapeutic target to reduce residual inflammation in patients at high risk of coronary artery disease.

Stage-Dependent Impact of RIPK1 Inhibition on Atherogenesis: Dual Effects on Inflammation and Foam Cell Dynamics

“…Taking advantage of ApoE SA / SA mice, a new model combining both hypercholesterolemia and hypertension that rapidly develops atherosclerosis (manuscript under submission), we examined the impact of RIPK1 inhibition on advanced atherosclerosis. Here, we report that RIPK1 inhibition protected against early atherosclerosis, confirming a recent observation ( 14 ), however, surprisingly, it promoted atherogenesis in late stage. This reflects a dual action of RIPK1 in inflammation and cholesterol metabolism related to foam cell formation.…”

“…Due to its crucial role in cell death and inflammation, RIPK1 has implicated as a potential therapeutic target for cardiovascular diseases. RIPK1 is expressed in human and mouse atherosclerosis lesions ( 14 ), highly in macrophages ( 15 ). RIPK1 Inhibition is protective in myocardial infarction ( 16 ) and early atherosclerosis ( 17 ) in mice.…”

Six Hub Genes Associated with Erectile Dysfunction And Acute Myocardial Infarction Based On GEO

“…Karunakaran et al identi ed RIPK1 as a central driver of in ammation in atherosclerosis by its ability to activate the NF-κB pathway and promote in ammatory cytokine release. RIPK1 will be a promising therapeutic target to reduce residual in ammation in patients at high risk of coronary artery disease [11].…”

Chinese Herbal Medicines and Active Metabolites: Potential Antioxidant Treatments for Atherosclerosis

“…As the disease continues, these foam cells undergo apoptosis, causing the accumulation of extracellular lipids to form lipid-rich plaque cores, enlarged lipid or necrotic cores, that protrude into the artery. In advanced stages of atherosclerosis, the apoptosis of SMCs and the decomposition of collagen and elastin (exacerbated by the inflammatory process ( Karunakaran et al, 2021 )) cause rupture of the fibrous cap around the lipid core and incite coagulation factors to interact with tissue factors, leading to thrombus formation and associated complications ( Figure 1 ).…”