Sulindac-derived retinoid X receptor-α modulator attenuates atherosclerotic plaque progression and destabilization in ApoE-/- mice.
Background and Purpose Atherosclerosis is a chronic inflammatory disease, and retinoid X receptor-alpha (RXR alpha) is an intriguing anti-atherosclerosis target. This study investigated whether and how an RXR alpha modulator, K-80003, derived from a non-steroidal anti-inflammatory drug attenuates atherosclerotic plaque progression and destabilization. Experimental Approach Our previously established ApoE(-/-) mouse model of carotid vulnerable plaque progression was treated with K-80003 or vehicle for 4 or 8 weeks. Samples of carotid arteries and serum were collected to determine atherosclerotic lesion size, histological features, expression of related proteins, and lipid profiles. In vitro studies were carried out in 7-ketocholesterol (7-KC)-stimulated macrophages treated with or without K-80003. Key Results K-80003 significantly reduced lesion size, plaque rupture, macrophage infiltration, and inflammatory cytokine levels. Plaque macrophages positive for nuclear p65 (RelA) NF-kappa B subunit were markedly reduced after K-80003 treatment. Also, K-80003 treatment inhibited 7-KC-induced p65 nuclear translocation, I kappa B alpha degradation, and transcription of NF-kappa B target genes. In addition, K-80003 inhibited NF-kappa B pathway mainly through the reduction of p62/sequestosome 1 (SQSTM1), probably due to promotion of autophagic flux by K-80003. Mechanistically, cytoplasmic localization of RXR alpha was associated with decreased autophagic flux. Increasing cytoplasmic RXR alpha expression by overexpression of RXR alpha/385 mutant decreased autophagic flux in RAW264.7 cells. Finally, K-80003 strongly inhibited 7-KC-induced RXR alpha cytoplasmic translocation. Conclusions and Implications K-80003 suppressed atherosclerotic plaque progression and destabilization by promoting macrophage autophagic flux and consequently inhibited the p62/SQSTM1-mediated NF-kappa B proinflammatory pathway. Thus, targeting RXR alpha-mediated autophagy-inflammation axis by its noncanonical modulator may represent a promising strategy to treat atherosclerosis.