Polydatin ameliorates TBI induced secondary brain injury by inhibiting NLRP3-induced neuroinflammation associated with SOD2 acetylation.

Traumatic brain injury (TBI) is a kind of disease with high morbidity, mortality and disability, and its pathogenesis is still unclear. Research shows that nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) activation in neurons and astrocytes is involved in neuroinflammatory cascades after TBI. What's more, Polydatin (PD) has been shown to have a have a protective effect on TBI - induced neuroinflammation, but the mechanisms remain unclear. Here, we speculated that PD could alleviate TBI-induced neuroinflammatory damage through the superoxide dismutase (SOD2)-NLRP3 signal pathway, and SOD2 might regulate NLRP3 inflammasome activation. The model of lateral fluid percussion (LFP) for in vivo and cell stretching injury (SI) for in vitro were established to mimic TBI. NLRP3 chemical inhibitor MCC950, SOD2 inhibitor 2-Methoxyestradiol (2-ME2), and PD were administered immediately after TBI. As a result, the expression of SOD2 acetylation (SOD2 Ac-K122), NLRP3 and cleaved caspase-1 were incresased after TBI both in vivo and in vitro, and using SOD2 inhibitor 2-ME2 significantly promoted SOD2 Ac-K122, NLRP3, and cleaved caspase-1 expression, as well as exacerbated mtROS accumulation and MMP collapse in PC12 cells. However, using NLRP3 inhibitor MCC950 significantly inhibited cleaved caspase-1 activation following TBI both in vivo and in vitro; meanwhile, MCC950 inhibited mtROS accumulation and MMP collapse following TBI. More importantly, PD could inhibit the level of SOD2 Ac-K122, NLRP3 and cleaved caspase-1, while promote the expression of SOD2 following TBI both in vivo and in vitro. PD also inhibited mtROS accumulation and MMP collapse following SI. These results indicated that PD inhibited SOD2 acetylation to alleviate NLRP3 inflammasome activation, thus acting a protective role against TBI neuroinflammation.