Regulation of Monocyte Perilipin-2 Expression in Acute and Chronic Coronary Syndromes: Pathogenetic Implications

PLIN2 is involved in the lipid metabolism of macrophages resident in atherosclerotic plaques, and its upregulation leads to lipid droplets (LDs) accumulation. LDs enlargement results in the macrophage transformation into foam cells, a key step for the onset of atherosclerosis. In the present study, we investigated the role of PLIN2 and its regulation mechanisms in atherosclerosis and plaque instability in patients with a diagnosis of ST-elevation myocardial infarction (STEMI) and chronic coronary syndrome (CCS). We enrolled STEMI (n = 122) and CCS patients (n = 45). Peripheral blood mononuclear cells were isolated from whole blood samples. The PLIN2 protein level was analyzed in CD14+ monocytes by flow cytometry. Lipidomic panel and proteasome activity were evaluated. PLIN2 protein expression was significantly correlated with the age of CAD patients. We found no significant difference in monocyte lipid content between the two patient groups. The PLIN2 increased in STEMI as compared to CCS patients (p < 0.001). The proteasome activity being higher in STEMI as compared to CCS patients (p < 0.001), significant inverse correlations were evident between PLIN2 levels and proteasome activity in the CCS groups (p = 0.02). PLIN2 expression was higher in STEMI as compared to CCS patients, suggesting an involvement in plaque instability. Despite the proteasome activity being higher in STEMI patients, probably due to the elevated inflammatory burden, PLIN2 could escape proteasome degradation in a more efficient manner in STEMI as compared to CCS patients.