Endothelium (EC) is a key component of blood–brain barrier (BBB), and has an important position in the neurovascular unit. Its dysfunction and death after cerebral ischemic/reperfusion (I/R) injury not only promote evolution of neuroinflammation and brain edema, but also increase the risk of intracerebral hemorrhage of thrombolytic therapies. However, the mechanism and specific interventions of EC death after I/R injury are poorly understood. Here we showed that necroptosis was a mechanism underlying EC death, which promoted BBB breakdown after I/R injury. Treatment of rats with receptor interacting protein kinase 1 (RIPK1)-inhibitor, necrostatin-1 reduced endothelial necroptosis and BBB leakage. We furthermore showed that perivascular M1-like microglia-induced endothelial necroptosis leading to BBB disruption requires tumor necrosis factor-α (TNF-α) secreted by M1 type microglia and its receptor, TNF receptor 1 (TNFR1), on endothelium as the primary mediators of these effects. More importantly, anti-TNFα (infliximab, a potent clinically used drug) treatment significantly ameliorate endothelial necroptosis, BBB destruction and improve stroke outcomes. Our data identify a previously unexplored role for endothelial necroptosis in BBB disruption and suggest infliximab might serve as a potential drug for stroke therapy.

The mechanism of blood‐brain barrier (BBB) disruption, involved in poststroke edema and hemorrhagic transformation, is important but elusive. We investigated microRNA‐150 (miR‐150)‐mediated mechanism in the disruption of BBB after stroke in rats. We found that up‐regulation of miR‐150 increased permeability of BBB as detected by MRI after permanent middle cerebral artery occlusion in vivo as well as increased permeability of brain microvascular endothelial cells after oxygen‐glucose deprivation in vitro. The expression of claudin‐5, a key tight junction protein, was decreased in the ischemic boundary zone after up‐regulation of miR‐150. We found in brain microvascular endothelial cells that overexpression of miR‐150 decreased not only cell survival rate but also the expression levels of claudin‐5 after oxygen‐glucose deprivation. With dual‐luciferase assay, we confirmed that miR‐150 could directly regulate the angiopoietin receptor Tie‐2. Moreover, silencing Tie‐2 with lentivirus‐delivered small interfering RNA reversed the effect of miR‐150 on endothelial permeability, cell survival, and claudin‐5 expression. Furthermore, poststroke treatment with antagomir‐150, a specific miR‐150 antagonist, contributed to BBB protection, infarct volume reduction, and amelioration of neurologic deficits. Collectively, our findings suggested that miR‐150 could regulate claudin‐5 expression and endothelial cell survival by targeting Tie‐2, thus affecting the permeability of BBB after permanent middle cerebral artery occlusion in rats, and that miR‐150 might be a potential alternative target for the treatment of stroke.—Fang, Z., He, Q.‐W., Li, Q., Chen, X.‐L., Baral, S., Jin, H.‐J., Zhu, Y.‐Y., Li, M., Xia, Y.‐P., Mao, L., Hu, B. MicroRNA‐150 regulates blood‐brain barrier permeability via Tie‐2 after permanent middle cerebral artery occlusion in rats. FASEB J. 30, 2097–2107 (2016). www.fasebj.org

Blood‐brain barrier (BBB) disruption caused by reperfusion injury after ischemic stroke is an intractable event conducive to further injury. Brain pericytes play a vital role in maintaining BBB integrity by interacting with other components of the BBB. In this study, we found that sphingosine‐1‐phosphate receptor (S1PR)2 expressed in pericytes was significantly up‐regulated after ischemia in vivo and in vitro. By using a S1PR2 antagonist (JTE‐013), we showed that S1PR2 plays a critical role in the induction of BBB permeability of transient middle cerebral artery occlusion (tMCAO) rats and the in vitro BBB model. Furthermore, we discovered that S1PR2 may decrease N‐cadherin expression and increase pericyte migration via NF‐κB p65 signal and found that S1PR2 could be regulated by miR‐149–5p negatively, which was decreased in the ischemic boundary zone and cultured pericytes after ischemia. Overexpression of miR‐149–5p in cultured pericytes substantially increased N‐cadherin expression and decreased pericyte migration, which decreased BBB leakage in the in vitro model. Up‐regulating miR‐149–5p by intracerebroventricular injection of agomir‐149–5p attenuated BBB permeability and improved the outcomes of tMCAO rats significantly. Thus, our data suggest that miR‐149–5p may serve as a potential target for treatment of BBB disruption after ischemic stroke.—Wan, Y., Jin, H.‐J., Zhu, Y.‐Y., Fang Z., Mao, L., He, Q., Xia, Y.‐P., Li, M., Li, Y., Chen, X., Hu, B. MicroRNA‐149–5p regulates blood‐brain barrier permeability after transient middle cerebral artery occlusion in rats by targeting S1PR2 of pericytes. FASEB J. 32, 3133–3148 (2018). www.fasebj.org

Cerebral ischemia–reperfusion injury (CIRI) is a complex pathological process that arises when blood flow is restored to the brain after ischemia, often resulting in significant neuronal damage and triggering secondary inflammatory responses. This review explores the immune mechanisms underlying CIRI, focusing on the activation and polarization of resident central nervous system (CNS) cells—particularly microglia and astrocytes—and the infiltration of peripheral immune cells such as neutrophils, monocytes/macrophages, and T lymphocytes. We discuss the central role of microglia in the neuroinflammatory cascade, their polarization between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes, and how this process influences neuronal damage and tissue repair. This review highlights the roles of the complement system, inflammasome activation, and blood–brain barrier disruption as key drivers of inflammation and neuronal injury. Additionally, we elaborate on the dynamic interactions between resident and infiltrating immune cells, which amplify inflammation and impede post-ischemic recovery. Finally, we discuss emerging therapeutic strategies targeting immune modulation, including cytokine regulation, microglial reprogramming, and targeted drug delivery systems, which offer promising avenues for improving outcomes in ischemic stroke.

Only 10%-20% of colorectal cancer (CRC) patients observe effective responses to 5-fluorouracil (5-FU) based chemo-treatment. We used real-time PCR array and Western blot analysis to examine the expression alteration of acetyltransferases and deacetylases in 5-FU resistant CRC cell lines as compared to their respective parental CRC cell lines. Unlike other acetyltransferases and deacetylases, we found that the expression of acetyltransferase P300/CBP-associated factor (PCAF) is consistently decreased in three 5-FU resistant CRC cell lines. Similarly, knockdown of PCAF in HCT116 CRC parental cell line also increases the resistance to 5-FU and attenuates 5-FU-induced apoptosis. Mechanistically, we demonstrated that increased binding of trimethylated histone H3K27 in the promoter region of PCAF attenuated its transcription in 5-FU resistant HCT116/5-FU cells. Decreased PCAF impairs the acetylation of p53 and attenuates the p53-dependent transcription of p21, which results in the increased cyclin D1 and phosphorylation of Retinoblastoma 1. Conversely, overexpression of PCAF in CRC cell lines increases p21 and their susceptibility to 5-FU in vitro and in vivo. However, knockdown of p21 abolishes the beneficial effects of PCAF overexpression on increasing the sensitivity of HCT116/5-FU cells to 5-FU. Also, the reduced intensity of PCAF immunostaining was observed in the precancerous lesion, and microarray data from the public database further demonstrated the association between PCAF down-regulation and poor survival outcome. Our data suggest that PCAF-mediated p53 acetylation is an essential regulatory mechanism for increasing the susceptibility of CRC to 5-FU.

Background: Intestinal barrier dysfunction would lead to a rigorous inflammatory reaction due to the translocation of intestinal lumen-derived bacteria and endotoxins. The aim of the present study was to investigate whether intestinal barrier dysfunction occurs in patients with acute Stanford type A aortic dissection (ATAAD) and to determine its potential relationship with the plasma levels of several inflammatory biomarkers in the progression of ATAAD. Design and Methods: Serum samples from a total of 46 patients with ATAAD and 36 healthy volunteers were prospectively collected and analyzed. The serum levels of diamine oxidase (DAO), lactate dehydrogenase (LDH), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and C-reactive protein (CRP) were measured using colorimetric assay, enzyme-linked immunosorbent assay, and immunoturbidimetric assay. Results: Serum levels of DAO, LDH, IL-6, TNF-α, and CRP in patients with ATAAD were significantly higher than those in healthy participants. A significantly positive correlation between DAO activity and IL-6 ( r = .56, P < .001), TNF-α ( r = .63, P < .001), and CRP ( r = .53, P < .001) was observed. Moreover, the activity of DAO correlated negatively with the Pao₂/fraction of inspired oxygen (Fio₂) ratio ( r = −.39, P = .007). Conclusions: Intestinal barrier dysfunction, reflected by an increased level of serum DAO, may play an important role in the development of systemic inflammatory responses in patients with ATAAD. Therefore, strategies of preserving a normal intestinal barrier function may open new horizons in the treatment of inflammation-related adverse events in the setting of ATAAD.