Adenine suppresses inflammatory response in vascular smooth muscle cells via modulating AMPK/p53/NF-κB cascade

Abstract

Vascular smooth muscle cells (VSMCs) play crucial roles in vascular inflammation-associated diseases. While adenine, a purine compound, exhibits anti-inflammatory properties, its effects on VSMC inflammation remain poorly characterized. This investigation examined adenine's impact on proinflammatory mediators in lipopolysaccharide (LPS)-activated rat aortic smooth muscle cells (A7r5) and elucidated the underlying mechanisms. Cell viability, gene expression, cytokine secretion, and signaling pathways were evaluated using MTT assay, qPCR, ELISA, and western blotting techniques. Results demonstrated that adenine concentrations ≤400 μM maintained A7r5 cell viability while significantly suppressing LPS-induced mRNA expression and protein production of tumor necrosis factor-alpha (TNFα), monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), IL-1β, and IL-8. Additionally, LPS increased inducible nitric oxide synthase (iNOS) expression and nitric oxide production. Mechanistic analysis revealed that LPS treatment reduced p53 phosphorylation while enhancing ERK, JNK, and p38 phosphorylation alongside NF-κB activation. Co-treatment with adenine and LPS activated AMPK signaling, increased p53 phosphorylation, and simultaneously reduced ERK phosphorylation and NF-κB activation. AMPK inhibition abolished adenine-induced p53 phosphorylation, restored ERK and NF-κB activation, and reversed the suppression of proinflammatory mediator production. Furthermore, combined inhibition of ERK, NF-κB, and p53 pathways enhanced adenine's inhibitory effects on NF-κB activation and inflammatory mediator production. In conclusion, adenine effectively attenuates inflammatory mediator expression and secretion in LPS-stimulated A7r5 cells by modulating the AMPK/p53/NF-κB signaling cascade. These findings suggest adenine possesses significant anti-inflammatory potential with therapeutic implications for VSMC-mediated vascular inflammation.

Keywords: AMPK; Adenine; Proinflammatory mediators; Vascular smooth muscle cell; p53.