| BACKGROUND:Intracerebral hemorrhage(ICH)is the most fatal subtype of stroke,and there is no effective treatment at present.Impaired motor function in patients with ICH is closely related to direct compression of the proximal corticospinal tract(CST)by a hematoma,and secondary proximal and distal CST injury.Among them,neuroinflammation plays a key role in the pathophysiological mechanisms of secondary nerve injury after ICH.After neuroinflammation is triggered,the first immune cells activated are microglia,which secrete a large number of cytokines and promote the progression of inflammation.Microglia are a major component of the innate immune system and they respond to acute brain injury by activating and forming an M1-type(pro-inflammatory)or M2-type(anti-inflammatory)phenotype.NOD-like receptor family 3(NLRP3)inflammasome are considered to be major players in neuroinflammation.Recent studies have shown that the NLRP3 inflammasome can be activated after ICH,leading to an inflammatory cascade response that exacerbates brain injury.The selective NLRP3 inflammasome inhibitor MCC950 has been shown to attenuate brain injury after ICH,but its exact mechanism of action is unclear.In addition,it has been reported that NLRP3 inflammasome is mainly found in microglia,so we speculate that their activation may be closely related to microglia.This study aimed to investigate the effects of MCC950 on proximal and distal CST injury and microglial polarization after ICH,and to investigate the possible interrelationships or mechanisms.OBJECTIVE:To investigate the effect of MCC950,a selective NLRP3 inflammasome inhibitor,on proximal and distal CST injury and microglial polarization after ICH,and to explore its possible relationship or mechanism to provide a theoretical basis for future treatment of ICH as well as to promote motor function rehabilitation in patients with ICH.METHODS:The ICH model was prepared by stereotaxic injection of type Ⅳcollagenase into the basal ganglia region of male C57BL/6 mice.After successful modeling,10 mg/kg MCC950 was injected intraperitoneally into the treatment group,and phosphate buffer saline equal to the volume of MCC950 was given to the model group at the same time.Behavioral assessment was performed by mNSS score(day 1,3,and 7 after successful modeling),and Cylinder test(day 7 and 14).On day 3 after successful modeling,coronal sections of brain tissue were taken and the relative volume ratio of intracranial hematoma was analyzed using Image Pro Plus software;brain edema was analyzed by wet and dry weight method;protein expression of NLRP3 inflammasome complex components and microglia phenotypic markers were detected by Western Blot;M1/M2 microglia were detected by immunofluorescence double-labeling the expression of phenotypic markers was detected by immunofluorescence double-labeling.On day 14 after modeling,immunofluorescence was performed to detect damage to the corticospinal tract aggregation zone in the cervical enlargement.RESULTS:Treatment with MCC950 reduced neurological deficits after ICH,improved brain edema,decreased the relative volume ratio of intracranial hematoma,and reduced the expression of MBP in the corticospinal tract aggregation area of the cervical enlargement;in addition,MCC950 inhibited the protein expression of NLRP3,ASC,Caspase-1,iNOS,and upregulated the protein level of CD 163;decreased the expression of Ibal and iNOS double-positive microglia,and increased the expression of bal and CD163 double-positive microglia.CONCLUSIONS:MCC950 inhibition of NLRP3 inflammasome attenuates neuroinflammation after ICH by regulating microglial polarization,thereby reducing CST inflammatory injury.It may provide a new choice and strategy for the clinical treatment of ICH. |
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