Endothelial EGLN3-PKM2 signaling induces the formation of acute astrocytic barrier to alleviate immune cell infiltration after subarachnoid hemorrhage.

BACKGROUND: Most subarachnoid hemorrhage (SAH) patients have no obvious hematoma lesions but exhibit blood-brain barrier dysfunction and vasogenic brain edema. However, there is a few days between blood‒brain barrier dysfunction and vasogenic brain edema. The present study sought to investigate whether this phenomenon is caused by endothelial injury induced by the acute astrocytic barrier, also known as the glial limitans. METHODS: Bioinformatics analyses of human endothelial cells and astrocytes under hypoxia were performed based on the GEO database. Wild-type, EGLN3 and PKM2 conditional knock-in mice were used to confirm glial limitan formation after SAH. Then, the effect of endothelial EGLN3-PKM2 signaling on temporal and spatial changes in glial limitans was evaluated in both in vivo and in vitro models of SAH. RESULTS: The data indicate that in the acute phase after SAH, astrocytes can form a temporary protective barrier, the glia limitans, around blood vessels that helps maintain barrier function and improve neurological prognosis. Molecular docking studies have shown that endothelial cells and astrocytes can promote glial limitans-based protection against early brain injury through EGLN3/PKM2 signaling and further activation of the PKC/ERK/MAPK signaling pathway in astrocytes after SAH. CONCLUSION: Improving the ability to maintain glial limitans may be a new therapeutic strategy for improving the prognosis of SAH patients.

TIMP-3 Alleviates White Matter Injury After Subarachnoid Hemorrhage in Mice by Promoting Oligodendrocyte Precursor Cell Maturation.

Subarachnoid hemorrhage (SAH) is associated with high mortality and disability rates, and secondary white matter injury is an important cause of poor prognosis. However, whether brain capillary pericytes can directly affect the differentiation and maturation of oligodendrocyte precursor cells (OPCs) and subsequently affect white matter injury repair has still been revealed. This study was designed to investigate the effect of tissue inhibitor of metalloproteinase-3 (TIMP-3) for OPC differentiation and maturation. PDGFRßret/ret and wild-type C57B6J male mice were used to construct a mouse model of SAH via endovascular perforation in this study. Mice were also treated with vehicle, TIMP-3 RNAi or TIMP-3 RNAi + TIMP-3 after SAH. The effect of TIMP-3 on the differentiation and maturation of OPCs was determined using behavioral score, ELISA, transmission electron microscopy, immunofluorescence staining and cell culture. We found that TIMP-3 was secreted mainly by pericytes and that SAH and TIMP-3 RNAi caused a significant decrease in the TIMP-3 content, reaching a nadir at 24 h, followed by gradual recovery. In vitro, the myelin basic protein content of oligodendrocytes after oxyhemoglobin treatment was increased by TIMP-3 overexpression. The data indicates TIMP-3 could promote the differentiation and maturation of OPCs and subsequently improve neurological outcomes after SAH. Therefore, TIMP-3 could be beneficial for repair after white matter injury and could be a potential therapeutic target in SAH.

Targeting brain-peripheral immune responses for secondary brain injury after ischemic and hemorrhagic stroke.

The notion that the central nervous system is an immunologically immune-exempt organ has changed over the past two decades, with increasing evidence of strong links and interactions between the central nervous system and the peripheral immune system, both in the healthy state and after ischemic and hemorrhagic stroke. Although primary injury after stroke is certainly important, the limited therapeutic efficacy, poor neurological prognosis and high mortality have led researchers to realize that secondary injury and damage may also play important roles in influencing long-term neurological prognosis and mortality and that the neuroinflammatory process in secondary injury is one of the most important influences on disease progression. Here, we summarize the interactions of the central nervous system with the peripheral immune system after ischemic and hemorrhagic stroke, in particular, how the central nervous system activates and recruits peripheral immune components, and we review recent advances in corresponding therapeutic approaches and clinical studies, emphasizing the importance of the role of the peripheral immune system in ischemic and hemorrhagic stroke.

Standard vs. Modified Antiplatelet Therapy Based on Thromboelastography With Platelet Mapping for Preventing Bleeding Events in Patients Undergoing Stent-Assisted Coil for a Ruptured Intracranial Aneurysm.

Background and Purpose: Stent-assisted coiling (SAC) of intracranial aneurysms is usually treated with antiplatelet therapy to reduce the risk of postoperative ischemic events. However, using the same antiplatelet therapy for all patients may increase the risk of bleeding in patients with aneurysmal subarachnoid hemorrhage (aSAH). Thromboelastography-platelet mapping (TEG-PM) measures platelet function, which reflects the effect of antiplatelet drugs. This study aimed to evaluate the benefits of individualized antiplatelet regimens based on TEG-PM parameters for patients with aSAH who underwent SAC. Methods: We retrospectively included patients with aSAH who treated with SAC during the period from June 2012 to December 2019. Patients were divided into two groups: patients whose antiplatelet therapy adjusted by TEG-PM parameters after surgery (adjustment group) and patients who were treated with standard dual antiplatelet therapy without TEG-PM test (control group). The occurrence of major/minor bleeding events, major/minor thromboembolic events, and favorable outcome (modified Rankin scale <3) were compared in both groups during hospitalization. Results: Of 188 aSAH patients considered for this study, 145 met the criteria for inclusion and were included in the analysis (93 patients in the adjustment group and 52 patients in the control group). The risks of minor bleeding events (1.1 vs. 9.6%, p = 0.02) were significantly lower in patients in the adjustment group. However, there was no significant difference in the rate of major bleeding events at discharge between adjustment and control groups (p = 0.35). The rates of thromboembolic events and favorable outcome were similar in both groups (22.6 vs. 28.8%, p = 0.42, 95.7 vs. 96.2%, p = 1.00). Furthermore, the minor thromboembolic events rate was significantly lower in the patients treated with treatment plan C (p = 0.02 for treatment plan C vs. treatment A, p = 0.03 for treatment plan C vs. treatment plan B). However, there was no significant difference in the rate of other mentioned above complications and favorable outcomes among patients treated with different antiplatelet regimens. Conclusions: Individualized antiplatelet therapy based on TEG-PM parameters might positively impact the bleeding risk of aSAH patients, without increasing the risk for clinically relevant thromboembolic events.