Glycoprotein non-metastatic melanoma protein B promotes pyroptosis of macrophages induced by homocysteine associated with the upregulation of the NOX-2/ NF-κB signaling pathway.

Elevated homocysteine (Hcy) levels are well established as an independent risk factor for atherosclerosis and its associated cardiovascular diseases. Macrophage pyroptosis- mediated inflammation plays a crucial role in the progression of atherosclerosis. Notably, glycoprotein non-metastatic melanoma protein B (GPNMB) expression is increased in macrophages within atherosclerotic plaques; however, whether GPNMB participates in Hcy-induced macrophage pyroptosis remains elusive. In the present study, we found that GPNMB expression was upregulated in Hcy- treated THP-1- derived macrophages. Consistently, serum GPNMB levels were significantly higher in patients with hyperhomocysteinemia (HHcy) compared with healthy controls. Functional experiments showed that silencing GPNMB reduced Hcy-triggered pyroptosis in THP-1-derived macrophages, whereas GPNMB overexpression exerted the opposite effect. Mechanistically, GPNMB upregulated the NOX2/NF-κB signaling pathway in THP-1-derived macrophages. Importantly, the pro-pyroptotic effect of GPNMB overexpression in Hcy-treated THP-1-derived macrophages was counteracted by either inhibition of NADPH oxidase 2 (NOX2) using the specific inhibitor gp91ds-tat or blockade of NF-κB activation with the inhibitor BAY11-7082. Moreover, serum GPNMB levels were correlated with serum Hcy levels and lipid profiles in both healthy individuals and HHcy patients. Collectively, these findings demonstrate that GPNMB facilitates Hcy-induced macrophage pyroptosis associated with the upregulation of the NOX2/NF-κB signaling pathway, highlighting the potential relevance of GPNMB as a candidate target for the clinical management of HHcy-related atherosclerotic cardiovascular disease.