Background: Systemic lupus erythematosus (SLE) is associated with a markedly elevated risk of developing atherosclerosis. Atherosclerosis is a chronic vascular disease characterized by the progressive accumulation of cholesterol-laden plaques within the walls of arteries. Modified lipoproteins accumulate in the vessel wall, triggering endothelial dysfunction and inflammation. Macrophages and smooth muscle cells transform into cholesterol-laden “foam cells,” culminating in fatty streaks, an early stage of atherosclerosis. Elevated LDL, particularly oxidized LDL (ox-LDL), fosters atherogenesis and inflammatory responses. Reverse cholesterol transport (RCT) plays a crucial role in plaque regression, orchestrated by transmembrane receptors like ABCA-1 and ABCG-1. Mitochondrial oxidative stress induced by ox-LDL generates reactive oxygen species (ROS), leading to lipid peroxidation, and increased toxic carbonyl compounds. Understanding these complex interactions between cholesterol, inflammation, and cellular processes is vital for developing effective strategies to combat and prevent atherosclerosis.

Objectives: This study aimed to investigate the effect of MIP2 on cholesterol metabolism in macrophages and its potential therapeutic role in atherosclerosis.

Methods: THP-1 macrophages were pretreated with MIP2, a TLR signaling antagonist, followed by ox-LDL or LPS stimulation to induce foam cell formation. Cholesterol efflux, inflammatory markers, and key regulatory proteins were assessed using Oil Red O staining, cholesterol assays, Western blotting, qRT-PCR, ELISA, and ROS measurement.

Results: MIP2 significantly attenuated foam cell formation induced by LPS and ox-LDL in THP-1 macrophages (p < 0.001). The inhibitory effect was dose-dependent, with higher MIP2 concentrations leading to a further reduction in lipid accumulation. This suggests that MIP2 effectively interferes with cholesterol uptake and/or retention pathways during atherogenic stimuli. Furthermore, MIP2 treatment elicited a robust upregulation of cholesterol efflux transporters ABCA1, ABCG1, SR-B1, and LXR-α, as well as PPAR-γ, at both mRNA and protein levels (p < 0.001). This finding indicates that MIP2 promotes the clearance of accumulated cholesterol from macrophages, potentially through enhanced cellular efflux activity. Mechanistically, MIP2 induced a concentration-dependent decrease in the phosphorylation of p65, p38, and JNK, key components of inflammatory signaling pathways. This suggests that MIP2’s anti-atherogenic effects may involve the suppression of pro-inflammatory responses triggered by ox-LDL and LPS. Notably, inhibition of p65 phosphorylation using specific pharmacological inhibitors further enhanced the expression of cholesterol efflux transporters and LXR-α, supporting the link between TLR signaling suppression and improved cholesterol homeostasis.

Conclusion: These findings suggest that MIP2 may offer a novel therapeutic strategy for atherosclerosis by simultaneously reducing foam cell formation, promoting cholesterol efflux, and mitigating inflammatory responses. The observed synergy between MIP2 treatment and p65 inhibition highlights the potential for combinatorial approaches targeting both cholesterol metabolism and inflammation in future therapeutic development.

REFERENCES: [1] Berenice Martinez-Shio E, Martin Cardenas-Hernandez A, Jimenez-Suarez V, Sherell Marin-Jauregui L, Castillo-Martin Del Campo C, Gonzalez-Amaro R, Escobedo-Uribe CD and Monsivais-Urenda AE (2022) Differentiation of circulating monocytes into macrophages with metabolically activated phenotype regulates inflammation in dyslipidemia patients. Clin Exp Immunol 208:83-94. doi: 10.1093/cei/uxac013

[2] Boren J, Chapman MJ, Krauss RM et al (2020) Low-density lipoproteins cause atherosclerotic cardiovascular disease: pathophysiological, genetic, and therapeutic insights: a consensus statement from the European Atherosclerosis Society Consensus Panel. Eur Heart J 41:2313-2330. doi: 10.1093/eurheartj/ehz962

Acknowledgements: This work was supported by the new faculty research fund of Ajou University School of Medicine and a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI16C099) and “Clinical faculty research support program” from the Institute of Medical Science, School of Medicine, Ajou University.

Disclosure of Interests: None declared.