Ezetimibe Attenuates Oxidative Stress and Neuroinflammation via the AMPK/Nrf2/TXNIP Pathway after MCAO in Rats.

Oxidative stress and neuroinflammation play essential roles in ischemic stroke-induced brain injury. Previous studies have reported that Ezetimibe (Eze) exerts antioxidative stress and anti-inflammatory properties in hepatocytes. In the present study, we investigated the effects of Eze on oxidative stress and neuroinflammation in a rat middle cerebral artery occlusion (MCAO) model. One hundred and ninety-eight male Sprague-Dawley rats were used. Animals assigned to MCAO were given either Eze or its control. To explore the downstream signaling of Eze, the following interventions were given: AMPK inhibitor dorsomorphin and nuclear factor erythroid 2-related factor 2 (Nrf2) siRNA. Intranasal administration of Eze, 1 h post-MCAO, further increased the endogenous p-AMPK expression, reducing brain infarction, neurologic deficits, neutrophil infiltration, microglia/macrophage activation, number of dihydroethidium- (DHE-) positive cells, and malonaldehyde (MDA) levels. Specifically, treatment with Eze increased the expression of p-AMPK, Nrf2, and HO-1; Romo-1, thioredoxin-interacting protein (TXNIP), NOD-like receptor protein 3 (NLRP3), Cleaved Caspase-1, and IL-1ß were reduced. Dorsomorphin and Nrf2 siRNA reversed the protective effects of Eze. In summary, Eze decreases oxidative stress and subsequent neuroinflammation via activation of the AMPK/Nrf2/TXNIP pathway after MCAO in rats. Therefore, Eze may be a potential therapeutic approach for ischemic stroke patients.

[Expression of Translocator Protein in Early Brain Injury After Subarachnoid Hemorrhage in Mice].

OBJECTIVE: To evaluate the expression of translocator protein (TSPO) in brain tissue within 72 h after subarachnoid hemorrhage (SAH) in mice. METHODS: Forty-four C57BL/6J mice were randomly divided into two groups, 17 in the Sham group and 27 in the SAH group. SAH mice model was performed by endovascular perforation as previously described with slight modifications. Sham group mice were performed by the same method but without piercing the blood vessels. Before and 6 h, 24 h, 48 h, 72 h after modeling, the two groups were scored with modified Garcia score for neurological function. At 6 h, 24 h, 48 h, 72 h after modeling, the mice were sacrificed. Sham group mice were sacrificed at 24 h after modeling. The expression of TSPO in brain tissue was evaluated by Western blot, positron emission tomography-computed tomography (PET-CT) and immunofluorescence staining. Fluorescent double staining was used to assess the relationship of TSPO and microglia. RESULTS: The neurological function scores of the SAH group mice decreased with time and then increased. The expression of TSPO in the brain tissue increased first and then decreased with time, and there was a negative correlation between them (r=-0.615 6, P < 0.01). PET-CT showed that the tracer intake of mouse brain tissue after SAH was higher than that of Sham group, and the difference was statistically significant (P < 0.05). Immunofluorescence staining showed that TSPO increased in the parietal cortex and basal cortex of the SAH group. And fluorescent double staining suggested that TSPO colocalized with Iba-1 which was a specific marker of microglia. CONCLUSIONS: In the early brain injury after SAH, the expression of TSPO in brain is widely increased, and the expression level increases first and then decreases. TSPO could participate in the activation of microglia and regulate the occurrence and development of brain injury after SAH.

Peli1 Contributions in Microglial Activation, Neuroinflammatory Responses and Neurological Deficits Following Experimental Subarachnoid Hemorrhage.

Early brain injury (EBI) following subarachnoid hemorrhage (SAH) is closely associated with neuroinflammation. Microglial activation is an early event that leads to neuroinflammation after SAH. Peli1 is an E3 ubiquitin ligase that mediates the induction of pro-inflammatory cytokines in microglia. Here we report Peli1 contributions in SAH mediated brain pathology. An SAH model was induced by endovascular perforation in adult male C57BL/6J mice. Peli1 was markedly induced in mice brains in a time-dependent manner and was predominantly expressed in CD16/32-positive microglia after SAH. Using genetic approaches, we demonstrated that decreased Peli1 significantly improved neurological deficits, attenuated brain edema, reduced over-expression of pro-inflammatory cytokine IL-6 and modified apoptotic/antiapoptotic biomarkers. In addition, Peli1 downregulation suppressed ERK and JNK phosphorylation levels via the downregulation of cIAP1/2 expression, subsequently reducing inducible nitric oxide synthase (iNOS) expression after SAH. Therefore, these findings demonstrate that Peli1 contributes to microglia-mediated neuroinflammation in EBI by mediating cIAP1/2 activation, thus promoting the activation of MyD88-dependent MAPK pathway after experimental SAH. Our findings also showed that Peli1 could promote the expression of M1 microglia polarization biomarker CD16/32 and iNOS after SAH. Targeting Peli1 exerts neuroprotective effects during EBI after SAH, thus could provide potential option for prevention-therapy in high-risk individuals.

Apolipoprotein E ε4: A Possible Risk Factor of Intracranial Pressure and White Matter Perfusion in Good-Grade Aneurysmal Subarachnoid Hemorrhage Patients at Early Stage.

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating and complicated disease with significant morbidity and mortality. Previous studies have shown that genetic susceptibility may play an important role in the outcome of a given individual with aSAH. This study evaluates the potential association in effects of the APOE allele on the early brain injury (EBI) in light of elevated intracranial pressure (ICP) and cerebral perfusion disorders in a consecutive series of non-comatose Chinese patients with aSAH. A total of 122 patients with aSAH (54 males and 68 females) were enrolled in this study. Demographic and clinical data were collected. We measured ICP before microsurgical clipping or endovascular coiling during the first 72 h after aneurysm rupture. Computed tomography perfusion (CTP) examination in patients was performed before treatment. The distributions of APOE genotypes and alleles matched Hardy-Weinberg law (p > 0.05). In this study, 68 patients (55.7%) had a normal ICP, whereas 54 (44.3%) had an elevated ICP. Fourteen of 21 patients with APOE ε4 had an elevated ICP, which was significantly different from those without APOE ε4 (p = 0.03). The patients with the ε4 allele had a higher incidence of elevated ICP [p = 0.009, 95% confidence interval (CI) = 1.481-15.432, odds ratio = 4.780] than those without this allele. For CTP measurements, a lower mean cerebral blood flow (difference, -4.74; 95% CI, 0.53-8.94 s, p = 0.03), longer mean transit time (difference, 0.47; 95% CI, -0.87 to -0.78, p = 0.02), and time-to-peak (difference, 2.29; 95% CI, -3.64 to -0.93 s, p = 0.02) were observed in patients with ε4 allele than in those without in the internal capsule regions. In conclusion, the APOE ε4 allele predisposes patients to elevated ICP and perfusion disorders in white matter regions during the first 72 h after aSAH. The presence of an APOE ε4 allele plays an important role in the EBI response to aSAH.