The IRE1α Pathway Links Endoplasmic Reticulum Stress to Atherosclerosis-Related Inflammation and Lipid Accumulation

Endoplasmic reticulum stress (ER stress) is closely related to the pathogenesis of atherosclerosis through various mechanisms, including inflammatory responses and foam cell formation. However, the mechanisms by which ER stress contributes to atherosclerosis require further elucidation. In this study, we investigate the impact of the inositol-requiring enzyme 1 alpha (IRE1α) arm of the unfolded protein response (UPR) in the expression of inflammatory cytokines in monocytes and intracellular lipid accumulation in macrophages, which play a crucial role in the immune response associated with atherosclerosis. We created an IRE1α knockout (KO) THP-1 monocytic cell line using the CRISPR/Cas9 gene-editing technology and subsequently differentiated these cells into macrophages. We conducted a comparative analysis of IRE1α KO cells and control THP-1 cells, focusing on several parameters: morphological features, lipopolysaccharide (LPS)-induced proinflammatory cytokine responses, specifically interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor (TNF) α measured by quantitative real-time PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA), as well as intracellular cholesterol accumulation and the expression levels of CD36 and ABCA1 genes following exposure to low-density lipoproteins (LDLs) derived from patients with atherosclerosis. Our findings demonstrate that IRE1α KO resulted in significant reduction of TNF, IL-1β, and IL-6 expression following LPS stimulation (p  < 0.05). ELISA confirmed significantly reduced cytokine secretion in IRE1α KO monocytes compared to controls. Furthermore, IRE1α deficiency impaired the cellular response to atherogenic LDL, preventing lipid-induced upregulation of scavenger receptor CD36 and cholesterol efflux transporter ABCA1. Thus, IRE1α serves as a critical regulator of both inflammatory cytokine expression and lipid metabolism in THP-1 cells, highlighting its potential as a therapeutic target for inflammatory diseases and atherosclerosis. Targeting IRE1α could offer new strategies to address inflammation and lipid dysregulation in cardiovascular diseases.