ELABELA as a Potential Diagnostic Biomarker and Therapeutic Target of Atherosclerosis

Atherosclerosis (AS) is a progressive arterial disease characterized by chronic inflammation and plaque formation in blood vessel walls. ELABELA, an endogenous ligand for the G protein-coupled receptor APJ (apelin peptide jejunum, apelin receptor), has multiple pharmacological activities for protecting the cardiovascular system. This study aimed to determine the potential anti-atherosclerotic effect of ELABELA and reveal the underlying mechanisms. Plasma ELABELA levels were significantly reduced and negatively correlated with plasma MMP2 and MMP9 levels in AS patients and high-fat diet-induced atherosclerotic ApoE-/- mice. Plasma ELABELA levels exhibited a potential diagnostic value for AS patients. Application of ELABELA-21 (ELA-21) significantly decreased atherosclerotic plaque area and inflammation in the aortas from the ApoE-/- mice. ELA-21 administration modulated the balance between M1 and M2 macrophages in the abdominal cavity and aorta roots toward a more anti-inflammatory status, accompanied by reduced MMP2, MMP9, and PRR and enhanced APJ, ACE, and ACE2 protein expression in plaques within aortic roots and decreased plasma sPRR levels. In vitro, ELA-21 effectively suppressed oxidized-low-density lipoprotein-induced foam cell formation and LPS/IFN-{gamma}-induced M1 polarization in THP-1 cells. Interestingly, the anti-inflammatory effect of ELA-21 was further enhanced by APJ inhibitor ML221, accompanied by elevated ACE and ATP6AP2 and reduced ACE2 mRNA levels. Collectively, our data highlighted the diagnostic and therapeutic potential of ELABELA on AS. ELA-21 protects against AS by inhibiting atherosclerotic plaque formation and promoting a more stable plaque phenotype, possibly via restoring the M1/M2 macrophage balance, enhancing macrophage ACE and ACE2 expression, and inhibiting the PRR system. ELABELA may be a novel biomarker and candidate therapeutic target for treating AS.