OTUD7B exacerbates atherosclerosis by promoting RIPK1-dependent vascular smooth muscle cell necroptosis.

BACKGROUND

Atherosclerosis is a vascular disease characterized by lipid deposition, chronic inflammation, and cell death. Necroptosis, a form of programmed necrosis, plays a critical role in atherosclerosis progression. This study investigates the expression of the deubiquitinating enzyme OTUD7B in atherosclerosis and its mechanism in regulating vascular injury via the RIPK1-mediated necroptosis pathway.

METHODS

An atherosclerosis model was established in mice fed a high-fat diet combined with partial carotid ligation. OTUD7B and necroptosis-related proteins RIPK1, RIPK3, and phosphorylated MLKL (p-MLKL) were detected in arterial tissues. In vitro, a necroptosis model was induced in human aortic smooth muscle cells (HA-SMCs) using the TSZ protocol. OTUD7B was knocked down to assess cell viability, inflammatory cytokine levels, and necroptosis. OTUD7B knockdown and RIPK1 co-overexpression were employed to validate its protective effects and dependency in vivo.

RESULTS

OTUD7B was significantly upregulated in plaques of atherosclerosis mice, concomitant with increased expression and phosphorylation of RIPK1 and RIPK3, as well as elevated p-MLKL levels. TUNEL staining and ELISA confirmed elevated necroptosis and inflammation. In vitro, OTUD7B knockdown markedly alleviated HA-SMC injury, suppressed the expression and phosphorylation of necroptosis markers, and reduced IL-1β/TNF-α release. In vivo OTUD7B knockdown attenuated plaque formation, lipid deposition, necroptosis, and inflammation. Mechanistically, RIPK1 overexpression significantly reversed the protective effects of OTUD7B knockdown, restoring RIPK1/RIPK3 phosphorylation and downstream signaling, indicating its functional dependency on the RIPK1 pathway. Co-immunoprecipitation further confirmed a direct OTUD7B-RIPK1 interaction, facilitating downstream signaling activation.

CONCLUSION

OTUD7B exacerbates necroptosis and inflammation in vascular smooth muscle cells by activating the RIPK1-RIPK3-MLKL axis, thereby playing a detrimental role in AS. This study identifies OTUD7B as a potential therapeutic target for atherosclerosis intervention.