Search

Background: Neuroinflammation is the major pathogenesis of cerebral ischemia. Microglia are activated and polarized to either the pro-inflammatory M1 phenotype or anti-inflammatory M2 phenotype, which act as a critical mediator of neuroinflammation. Sestrin2 has pro-survival properties against ischemic brain injury. However, whether sestrin2 has an anti-inflammatory function by shifting microglia polarization and its underlying mechanism is unknown., Methods: Adult male C57BL/6 mice (N = 108) underwent transient middle cerebral artery occlusion (tMCAO) and were treated with exogenous sestrin2. Neurological deficit scores and infarct volume were determined. Cell apoptosis was examined by TUNEL staining and Western blotting. The expression of inflammatory mediators, M1/M2-specific markers, and signaling pathways were detected by reverse transcription-polymerase chain reaction, immunostaining, and Western blotting. To explore the underlying mechanism, primary neurons were subjected to oxygen-glucose deprivation (OGD) and then treated with oxygenated condition medium of BV2 cells incubated with different doses of sestrin2., Results: Sestrin2 attenuated the neurological deficits, infarction volume, and cell apoptosis after tMCAO compared to those in the control (p < 0.05). Sestrin2 had an anti-inflammatory effect and could suppress M1 microglia polarization and promote M2 microglia polarization. Condition medium from BV2 cells cultured with sestrin2 reduced neuronal apoptosis after OGD in vitro. Furthermore, we demonstrated that sestrin2 drives microglia to the M2 phenotype by inhibiting the mammalian target of rapamycin (mTOR) signaling pathway and restoring autophagic flux., Conclusions: Sestrin2 exhibited neuroprotection by shifting microglia polarization from the M1 to M2 phenotype in ischemic mouse brain, which may be due to suppression of the mTOR signaling pathway and the restoration of autophagic flux.

Cerebral aneurysm growth is characterized by vessel wall frailness, although the underlying cellular mechanisms are unclear. Here, we examined the relationship between inflammatory smooth muscle cells (SMCs) and endothelial cells (ECs) in cerebral aneurysms, including the mechanisms underlying inflammatory SMC-induced changes in ECs. Five saccular cerebral aneurysms were collected and five temporal artery samples were used as controls. Cells and cytokines were detected by immunohistochemistry and TUNEL (transferase dUTP nick end labeling) assays performed to evaluate apoptosis. Human umbilical vein endothelial cells (HUVECs) were seeded on collagen I, IV, and VI-coated plates for cell adhesion assays and inflammatory SMCs (iSMCs) were established by culture in flexible silicone chambers subjected to cyclic mechanical stretch. HUVECs were cultured in iSMC-conditioned medium, followed by evaluation of their viability, apoptosis, and function, and determination of VEGF (vascular endothelial growth factor) -A and integrin levels by western blotting. Aneurysm tissue contained fewer SMCs and lacked ECs. In aneurysm walls, more matrix metalloproteinase (MMP) -1, MMP-3, and apoptotic cells were detected, accompanied by decreased collagen IV and VI levels. Cell adhesion assays revealed that more HUVECs were attached in collagen IV and VI-coated plates compared with controls. iSMC-conditioned medium significantly reduced HUVEC viability and apoptosis showed an increased trend; however, the difference was not significant. iSMC medium also reduced tube formation and migration of HUVECs. Moreover, iSMC medium reduced HUVEC expression of VEGF-A, integrin α1, integrin α2, and integrin β. Our data demonstrate a lack of SMCs and ECs in aneurysm walls, accompanied by elevated MMP and decreased collagen levels. In vitro assays showed that iSMCs induced reduction in EC adhesion, and caused EC dysfunction. Understanding of the relationships among SMC, EC, and collagens during aneurysm progression provides an additional therapeutic option for prevention of cerebral aneurysm progression.

Background and Purpose: Diabetes mellitus increases stroke incidence and mortality and hampers functional recovery after stroke. Fingolimod has been shown to improve neurofunctional recovery and reduce brain infarction after ischemic injury in mice without comorbidities. In this work, we investigated the effects of fingolimod in diabetic mice after transient middle cerebral artery occlusion (tMCAO). Methods: Hyperglycemia was induced by a single bolus streptozotocin injection. Adult male ICR mice (n = 86) underwent 1-h tMCAO surgery and received intraperitoneal injection of fingolimod (1 mg/kg) or vehicle immediately after reperfusion. Clark neurological score, brain infarction and edema, blood–brain barrier (BBB) integrity, apoptosis, and inflammation were evaluated at 24 h after tMCAO. Results: Fingolimod treatment reduced the number of infiltrated inflammatory cells and lowered the mRNA level of Tnf α. It also increased the ratio of Bcl-2/Bax. However, fingolimod significantly aggravated brain edema and reduced the expression levels of tight junction proteins ZO-1 and Occludin. The negative impacts of fingolimod on BBB integrity outweighed its beneficial effects in anti-inflammation, which resulted in the lack of improvement in endpoint outcomes at 24 h after tMCAO. Conclusion: Caution should be taken in considering the acute treatment using fingolimod for ischemic stroke with diabetes comorbidity. [ABSTRACT FROM AUTHOR]

Neuroinflammation has been recognized as a major contributor to brain injury caused by intracerebral hemorrhage (ICH). Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome acts as an important mediator of inflammatory response in various inflammation-related diseases including hemorrhagic insults. Cordycepin has recently been shown to possess anti-inflammatory effect; however, its role and the possible underlying mechanisms in ICH remain unclear. This study was designed to investigate the neuroprotective effect of cordycepin in mice models of ICH and to elucidate the underlying molecular mechanisms. ICH was induced in male ICR mice by injecting autologous blood infusion stereotactically. Cordycepin was then given intraperitoneally (i.p.) at 30 min after ICH induction. The results demonstrated that NLRP3 inflammasome was activated and exacerbated the inflammatory progression after ICH. Cordycepin treatment significantly alleviated neurological deficits, brain edema, and perihematomal tissue damage following ICH. These changes were accompanied by downregulated NLRP3 inflammasome components expression and a reduction of production and release of inflammasome substrates interleukin-1beta (IL-1β) and interleukin-18 (IL-18). Furthermore, cordycepin ameliorated neuronal death in the perihematomal regions, accompanied by a large reduction in the expression of high-mobility group protein B 1 (HMGB1) post-ICH. In conclusion, this study provides in vivo evidence that cordycepin confers neuroprotective effect in the models of ICH, possibly through the suppression of NLRP3 inflammasome activation. [ABSTRACT FROM AUTHOR]