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Background: Complex mechanisms participate in microglial activation after a traumatic brain injury (TBI). TBI can induce autophagy and apoptosis in neurons and glial cells, and moderate hypothermia plays a protective role in the acute phase of TBI. In the present study, we evaluated the effect of TBI and moderate hypothermia on microglial activation and investigated the possible roles of autophagy/apoptosis and toll-like receptor 4 (TLR4)., Methods: The TBI model was induced with a fluid percussion TBI device. Moderate hypothermia was achieved under general anesthesia by partial immersion in a water bath for 4 h. All rats were killed 24 h after the TBI., Results: Our results showed downregulation of the microglial activation and autophagy, but upregulation of microglial apoptosis, upon post-TBI hypothermia treatment. The expression of TLR4 and downstream myeloid differentiation primary response 88 (MyD88) was attenuated. Moderate hypothermia reduced neural cell death post-TBI., Conclusions: Moderate hypothermia can reduce the number of activated microglia by inhibiting autophagy and promoting apoptosis, probably through a negative modulation between autophagy and apoptosis. Moderate hypothermia may attenuate the pro-inflammatory function of microglia by inhibiting the MyD88-dependent TLR4 signaling pathway.

Objective: We evaluated the role of microglia autophagy in microglia activation after traumatic brain injury (TBI) in rats., Methods: TBI was induced by a fluid percussion TBI device. All rats were killed 24 hours after TBI. The ipsilateral hippocampus in all rats was analyzed with hematoxylin-eosin staining. Immunohistochemistry and Western blotting of ionized calcium-binding adapter molecule 1 was used to determine changes in microglia activation. Double staining of microtubule-associated protein light chain 3, Beclin-1, and ionized calcium-binding adapter molecule 1 was used to assess changes of microglia autophagy. Enzyme-linked immunosorbent assay of tumor necrosis factor-α and interleukin-1β was used to evaluate changes in inflammatory responses. Terminal deoxyribonucleotidyl transferase-mediated deoxyuridine 5'-triphosphate nick-end labeling staining was used to determine cell death in the ipsilateral hippocampus., Results: At 24 hours after TBI, microglial cells became activated, and the autophagy inhibitor 3-methyladenine (3-MA) further promoted microglia activation. Protein light chain 3- and Beclin-1-positive microglial cells were increased after TBI, whereas 3-MA decreased the number of positive microglial cells, increasing the expression of tumor necrosis factor-α and interleukin-1β; terminal deoxyribonucleotidyl transferase-mediated deoxyuridine 5'-triphosphate nick-end labeling staining demonstrated that 3-MA could increase the number of terminal deoxyribonucleotidyl transferase-mediated deoxyuridine 5'-triphosphate nick-end labeling-positive cells (16.83 ± 0.83 vs. 11 ± 0.82, P < 0.001)., Conclusions: Our data demonstrated that TBI induced microglia activation and microglia autophagy. Inhibition of microglia autophagy with 3-MA increased microglia activation and neural apoptosis. These findings indicate that targeting microglia autophagy may be a therapeutic strategy for TBI., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Aims: This study aimed to investigate the relationship between microglial metabolism and neuroinflammation by examining the impact of citrate accumulation in microglia and its potential regulation through Cs K215 hypoacetylation. Methods: Experimental approaches included assessing Cs enzyme activity through Cs K215Q mutation and investigating the inhibitory effects of hesperidin, a natural flavanone glycoside, on citrate synthase. Microglial phagocytosis and expression of pro‐inflammatory cytokines were also examined in relation to Cs K215Q mutation and hesperidin treatment. Results: Cs K215Q mutation and hesperidin exhibited significant inhibitory effects on Cs enzyme activity, microglial citrate accumulation, phagocytosis, and pro‐inflammatory cytokine expression. Interestingly, Sirt3 knockdown aggravated microglial pro‐inflammatory functions during neuroinflammation, despite its proven role in Cs deacetylation. Conclusion: Cs K215Q mutation and hesperidin effectively inhibited microglial pro‐inflammatory functions without reversing the metabolic reprogramming. These findings suggest that targeting Cs K215 hypoacetylation and utilizing hesperidin may hold promise for modulating neuroinflammation in microglia. [ABSTRACT FROM AUTHOR]