Itaconate Attenuates Homocysteine-induced Nod-like Receptor Family Protein 3 Inflammasome-mediated Pyroptosis in Hippocampal Neurons: Involvement of Inhibiting Succinate Dehydrogenase Complex Subunit A Level.

Abstract: Elevated homocysteine (Hcy) levels are associated with various neurodegenerative diseases. Elucidating the pathogenesis of Hcy-associated neurotoxicity and exploring novel approaches for preventing and treating Hcy-induced neurotoxicity are of paramount significance. This study will be based on nod-like receptor family protein 3 (NLRP3)-mediated pyroptosis and succinate dehydrogenase (SDH) to study the mechanisms underlying the neurotoxicity of Hcy in HT-22 cells, a mouse hippocampal neuronal cell line, and the protective role and mechanisms of itaconate against Hcy-associated neurotoxicity. Cell viability was assessed by CCK-8 assay. The contents of interleukin-1 beta (IL-1β) and IL-18 in the culture supernatant were detected by enzyme-linked immunosorbent assay. The expressions of pyroptosis-related proteins and succinate dehydrogenase complex subunit A (SDHA) were measured by Western blot analysis. The colocalization of gasdermin D (GSDMD) and the cell membrane was observed by Immunofluorescence. Our findings indicate that Hcy treatment significantly decreased HT22 cell viability and increased the inflammatory response. Furthermore, Hcy treatment enhanced GSDMD-N expression level, promoted the membrane localization of GSDMD, and increased the expression levels of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and cleaved-caspase-1 in HT22 cells. Notably, itaconate reversed the effects of Hcy on neurotoxicity, as evidenced by increased cell viability and decreased NLRP3 inflammasome-mediated pyroptosis in HT22 cells. Furthermore, itaconate reduced the expression level of SDHA in Hcy-exposed HT22 cells. These findings highlight that NLRP3 inflammasome-mediated pyroptosis and the activation of SDHA play crucial roles in Hcy-induced neuronal injury and that itaconate protects against Hcy-induced NLRP3 inflammasome-mediated pyroptosis via suppressing SDHA expression.