The protective effect of A20 on atherosclerosis in apolipoprotein E-deficient mice is associated with reduced expression of NF-κB target genes

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Abstract
Up-regulation of inflammatory responses is considered a driving force of atherosclerotic lesion development. One key regulator of inflammation is the A20 (also called TNF-alpha-induced protein 3 or Tnfaip3) gene, which is responsible for NF-kappaB termination and maps to an atherosclerosis susceptibility locus revealed by quantitative trait locus-mapping studies at mouse proximal chromosome 10. In the current study, we examined the role of A20 in atherosclerotic lesion development. At the aortic root lesion size was found to be increased in C57BL/6 (BG) apolipoprotein E-deficient (ApoE(-/-)) mice haploinsufficient for A20, compared with B6 ApoE(-/-) controls that expressed A20 normally (60% in males and 23% in females; P < 0.001 and P < 0.05, respectively). In contrast, lesion size was found to be decreased in F(1) (B6 x FVB/N) mice overexpressing A20 by virtue of containing an A20 BAC transgene compared with nontransgenic controls (30% in males, P < 0.001, and 17% in females, P = 0.02). The increase in lesions in the A20 haploinsufficient mice correlated with increased expression of proatherosclerotic NF-kappaB target genes, such as vascular cell adhesion molecule 1, intercellular adhesion molecule 1, and macrophage-colony-stimulating factor, and elevated plasma levels of NF-kappaB-driven cytokines. These findings suggest that A20 diminishes atherosclerosis by decreasing NF-kappaB activity, thereby modulating the proinflammatory state associated with lesion development.