Objective:To explore the effect of necroptosis inhibitor necrosulfonamide (NSA) on traumatic brain injury (TBI) mouse model and BV2 cell pyroptosis model and their mechanisms.Methods:(1) In vivo experiments: 50 mice were randomly divided into sham-operated group, TBI group, TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group, with 10 mice in each group. TBI model was established using a modified Feeney's weight-drop method; 4 h after modeling, 90% corn oil, 1 mg/kg NSA, 5 mg/kg NSA, or 10 mg/kg NSA was administered into the mice, respectively. Mice in the sham-operated group only had circular bone window opened without being subjected to impact. At 48 hours after modeling, neurological function was evaluated by modified neurological function score (mNSS), serum lactate dehydrogenase (LDH) content was detected by LDH detection kit, contents of interleukin (IL)-18, IL-1β and tumor necrosis factor-α (TNF-α) in the brain tissues were detected by enzyme-linked immunosorbent assay (ELISA), and expressions and localizations of ionized calcium binding adaptor molecule 1 (IBA-1), cysteinyl aspartate specific proteinase-1 (Caspase-1) p20 and gasdermin D (GSDMD) in the injured parietal cortex were detected by double immunofluorescent staining. (2) In vitro experiments: BV2 cells were divided into control group, lipopolysaccharide (LPS)+adenosine triphosphate (ATP)+dimethyl sulfoxide (DMSO) group, LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group. Cells in the latter 4 groups were induced by LPS+ATP to establish BV2 cell pyroptosis model, and incubated with 2 μL DMSO, 5 μmol/L NSA, 10 μmol/L NSA, and 15 μmol/L NSA for 1 hour, respectively; cells in the control group were cultured conventionally. Contents of LDH, IL-1β, IL-18, and TNF-α in the cell culture supernatant were detected by ELISA; pyroptosis was detected by calcein acetoxymethyl ester (CAM)/propidium iodide (PI) double staining; protein expressions of nucleotide binding domain-like receptor protein 3 (NLRP3), Caspase-1 p20, GSDMD, and N-terminal fragment of GSDMD (GSDMD-N) were detected by Western blotting. Results:(1) Compared with the TBI group, the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had decreased mNSS score and serum LDH content, decreased IL-1β and IL-18 contents in the brain tissues and number of Caspase-1 p20 + cells in the injured parietal cortex, successively, with significant differences ( P<0.05). Compared with the TBI group ([287.80±12.26] cells/mm 2), the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group had decreased number of Iba-1 +GSDMD + cells in the injured parietal cortex ([213.70±11.87] cells/mm 2, [205.30±9.15] cells/mm 2, [131.70±13.69] cells/mm 2),successively, with significant differences ( P<0.05). Compared with the TBI group, the TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 + cells in the injured parietal cortex, and the TBI+10 mg/kg NSA group had significantly decreased TNF-α content in the brain tissues and number of GSDMD + cells in the injured parietal cortex ( P<0.05). Compared with the TBI group ([247.20±9.88] cells/mm 2), the TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 +Caspase-1 p20 + cells in the injured parietal cortex ([181.70±9.37] cells/mm 2, P<0.05). (2) Compared with the LPS+ATP+DMSO group, the LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group had decreased IL-18 content in the supernatant, successively, with significant differences ( P<0.05); and compared with the LPS+ATP+DMSO group, the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased contents of LDH, IL-1β, and TNF-α in the supernatant and ratio of PI +/CAM + cell counts ( P<0.05). Compared with the LPS+ATP+DMSO group (2.62±0.50), the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased Caspase-1 p20 protein expression (1.36±0.14, 1.32±0.07, P<0.05). Compared with the LPS+ATP+DMSO group (5.00±1.67), the LPS+ATP+5 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD protein expression (1.42±0.26, 1.68±0.32, P<0.05). Compared with the LPS+ATP+DMSO group (2.28±0.24), the LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD-N protein expression (1.23±0.08, P<0.05). Conclusion:NSA can inhibit microglial pyroptosis after TBI by inhibiting the Caspase-1 p20/GSDMD pathway, thereby playing a neuroprotective role.

Objective:To explore the effect of necroptosis inhibitor necrosulfonamide (NSA) on traumatic brain injury (TBI) mouse model and BV2 cell pyroptosis model and their mechanisms.Methods:(1) In vivo experiments: 50 mice were randomly divided into sham-operated group, TBI group, TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group, with 10 mice in each group. TBI model was established using a modified Feeney's weight-drop method; 4 h after modeling, 90% corn oil, 1 mg/kg NSA, 5 mg/kg NSA, or 10 mg/kg NSA was administered into the mice, respectively. Mice in the sham-operated group only had circular bone window opened without being subjected to impact. At 48 hours after modeling, neurological function was evaluated by modified neurological function score (mNSS), serum lactate dehydrogenase (LDH) content was detected by LDH detection kit, contents of interleukin (IL)-18, IL-1β and tumor necrosis factor-α (TNF-α) in the brain tissues were detected by enzyme-linked immunosorbent assay (ELISA), and expressions and localizations of ionized calcium binding adaptor molecule 1 (IBA-1), cysteinyl aspartate specific proteinase-1 (Caspase-1) p20 and gasdermin D (GSDMD) in the injured parietal cortex were detected by double immunofluorescent staining. (2) In vitro experiments: BV2 cells were divided into control group, lipopolysaccharide (LPS)+adenosine triphosphate (ATP)+dimethyl sulfoxide (DMSO) group, LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group. Cells in the latter 4 groups were induced by LPS+ATP to establish BV2 cell pyroptosis model, and incubated with 2 μL DMSO, 5 μmol/L NSA, 10 μmol/L NSA, and 15 μmol/L NSA for 1 hour, respectively; cells in the control group were cultured conventionally. Contents of LDH, IL-1β, IL-18, and TNF-α in the cell culture supernatant were detected by ELISA; pyroptosis was detected by calcein acetoxymethyl ester (CAM)/propidium iodide (PI) double staining; protein expressions of nucleotide binding domain-like receptor protein 3 (NLRP3), Caspase-1 p20, GSDMD, and N-terminal fragment of GSDMD (GSDMD-N) were detected by Western blotting. Results:(1) Compared with the TBI group, the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had decreased mNSS score and serum LDH content, decreased IL-1β and IL-18 contents in the brain tissues and number of Caspase-1 p20 + cells in the injured parietal cortex, successively, with significant differences ( P<0.05). Compared with the TBI group ([287.80±12.26] cells/mm 2), the TBI+1 mg/kg NSA group, TBI+5 mg/kg NSA group, and TBI+10 mg/kg NSA group had decreased number of Iba-1 +GSDMD + cells in the injured parietal cortex ([213.70±11.87] cells/mm 2, [205.30±9.15] cells/mm 2, [131.70±13.69] cells/mm 2),successively, with significant differences ( P<0.05). Compared with the TBI group, the TBI+5 mg/kg NSA group and TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 + cells in the injured parietal cortex, and the TBI+10 mg/kg NSA group had significantly decreased TNF-α content in the brain tissues and number of GSDMD + cells in the injured parietal cortex ( P<0.05). Compared with the TBI group ([247.20±9.88] cells/mm 2), the TBI+10 mg/kg NSA group had significantly decreased number of Iba-1 +Caspase-1 p20 + cells in the injured parietal cortex ([181.70±9.37] cells/mm 2, P<0.05). (2) Compared with the LPS+ATP+DMSO group, the LPS+ATP+5 μmol/L NSA group, LPS+ATP+10 μmol/L NSA group, and LPS+ATP+15 μmol/L NSA group had decreased IL-18 content in the supernatant, successively, with significant differences ( P<0.05); and compared with the LPS+ATP+DMSO group, the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased contents of LDH, IL-1β, and TNF-α in the supernatant and ratio of PI +/CAM + cell counts ( P<0.05). Compared with the LPS+ATP+DMSO group (2.62±0.50), the LPS+ATP+10 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased Caspase-1 p20 protein expression (1.36±0.14, 1.32±0.07, P<0.05). Compared with the LPS+ATP+DMSO group (5.00±1.67), the LPS+ATP+5 μmol/L NSA group and LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD protein expression (1.42±0.26, 1.68±0.32, P<0.05). Compared with the LPS+ATP+DMSO group (2.28±0.24), the LPS+ATP+15 μmol/L NSA group had significantly decreased GSDMD-N protein expression (1.23±0.08, P<0.05). Conclusion:NSA can inhibit microglial pyroptosis after TBI by inhibiting the Caspase-1 p20/GSDMD pathway, thereby playing a neuroprotective role.