Mu He1, Han Li1, Xiaoli Min2, *
1Sichuan Province Forest Center Hospital, Chengdu 610081, PR China - 2Department of Cerebrovascular Disease, The Second Affiliated Hospital, Kunming Medical
Objective: To analyze mitochondrial autophagy and nod-like receptor protein 3 (NLRP3) inflammidas after traumatic brain injury and their correlation with neuroinflammatory responses.
Methods: Five cases of craniocerebral injury (the observation group) and 5 cases of non-craniocerebral injury (control group) were randomly selected. The expressions of autophagy-related proteins and mitochondrial marker proteins in brain tissues of each group were determined. Then 36 clean healthy male SD rats were randomly selected and divided evenly into a sham operation group and a model group. The rat model of brain injury was established. The autophagy inhibitor 3-methyladenine (3-MA), mitochondrial autophagy agent Mdivi-1, and autophagy agonist RAPA were used to regulate the mitochondrial autophagy after brain injury. The expression levels of LC3-Ⅱ, interleukin 1β (IL-1β), and caspase-1 expression were determined in each group. The expression levels of NLRP3, IL-1β, IL-18, and caspase-1 in the brain tissues of each group were measured by using 3-MA and Mdivi-1 to inhibit mitochondrial autophagy. The expression levels of NLRP3, IL-1β, and caspase-1 in the NLRP3 down-regulated group and the NLRP3 down-regulated control group were measured. Six rats to be knockouts of NLRP3, caspase-1, and IL-1βR were selected and bred with C57/B6-J mice. Another six wild-type mice in the same nest were selected as the control group.
Results: Compared with the control group, in the observation group the brain tissue p62, COXIV, TOM40, and MnSOD expression levels clearly declined and the LC3-Ⅱ expression level increased significantly (P<0.01). Compared with the model group, model group rats LC3-Ⅱ and caspase-1, IL-1β expression level increased significantly (P<0.05). Compared with the model group, the expression levels of LC3-Ⅱ in the 3-MA group significantly declined, but the IL-1β and caspase-1 expression levels increased significantly. The LC3-Ⅱ expression level increased significantly and the IL-1β and caspase-1 expression level clearly declined in both the Mdivi-1 and RAPA groups (P<0.05). Compared with the sham operation group, there was no significant difference in the time the rats were on the balance beam before injury (P>0.05). Starting from 1 day after the injury, the time the rats in the Mdivi-1 group stayed on the balance beam was significantly shortened, and the time to find the hidden platform was significantly prolonged starting from 12 days after injury (P<0.01). Compared with the control group, NLRP3, IL-1β, IL-18, and caspase-1 significantly declined in the brain tissue of the observation group (P<0.05). Compared with the NLRP3 down-regulated control group, the expression levels of NLRP3, IL-1β investment, and caspase-1 in the brain tissue of the NLRP3 down-regulated group were significantly reduced (P<0.01). There was no significant difference in the time the rats stayed on the balance beam before injury (P>0.01). From 2 days after injury, compared with the wild-type control group, the NLRP3, IL-1β, and caspase-1 knockout group rats spent significantly more time on the balance beam. From 11 days after injury, rats in the NLRP3, IL-1β, and caspase-1 knockout group took significantly more time to find the hidden platform (P<0.01).
Conclusion: NLRP3 expression and mitochondrial autophagy were significantly increased after craniocerebral injury. Mitochondrial autophagy has a protective effect on nerve function, and inhibiting mitochondrial autophagy will significantly aggravate the neuroinflammatory response and hinder the recovery of nerve function. However, the NLRP3-mediated neuroinflammatory response is significantly enhanced, and down-regulation of NLRP3 expression can significantly reduce the neuroinflammatory response caused by craniocerebral injury, which is conducive to the recovery of nerve function.
Craniocerebral trauma, mitochondrial autophagy, NLRP3 inflammatory corset, neuroinflammatory response, correlation.