Reperfusion and cytoprotective agents are a mutually beneficial pair in ischaemic stroke therapy: an overview of pathophysiology, pharmacological targets and candidate drugs focusing on excitotoxicity and free radical

Epigenetic regulation of the inflammatory response in stroke

Stroke is classified as ischemic or hemorrhagic, and there are few effective treatments for either type. Immunologic mechanisms play a critical role in secondary brain injury following a stroke, which manifests as cytokine release, blood-brain barrier disruption, neuronal cell death, and ultimately behavioral impairment. Suppressing the inflammatory response has been shown to mitigate this cascade of events in experimental stroke models. However, in clinical trials of anti-inflammatory agents, long-term immunosuppression has not demonstrated significant clinical benefits for patients. This may be attributable to the dichotomous roles of inflammation in both tissue injury and repair, as well as the complex pathophysiologic inflammatory processes in stroke. Inhibiting acute harmful inflammatory responses or inducing a phenotypic shift from a pro-inflammatory to an anti-inflammatory state at specific time points after a stroke are alternative and promising therapeutic strategies. Identifying agents that can modulate inflammation requires a detailed understanding of the inflammatory processes of stroke. Furthermore, epigenetic reprogramming plays a crucial role in modulating post-stroke inflammation and can potentially be exploited for stroke management. In this review, we summarize current findings on the epigenetic regulation of the inflammatory response in stroke, focusing on key signaling pathways including nuclear factor-kappa B, Janus kinase/signal transducer and activator of transcription, and mitogen-activated protein kinase as well as inflammasome activation. We also discuss promising molecular targets for stroke treatment. The evidence to date indicates that therapeutic targeting of the epigenetic regulation of inflammation can shift the balance from inflammation-induced tissue injury to repair following stroke, leading to improved post-stroke outcomes.

Safety and efficacy of GD-11 in patients with ischaemic stroke: a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial

BACKGROUND

GD-11, a novel brain cytoprotective drug, was designed to be actively taken up and transported across the blood-brain barrier via the glucose transporter. This study aimed to evaluate the safety and efficacy of GD-11 for improving the recovery of patients with acute ischaemic stroke (AIS).

METHODS

A double-blind, randomised, placebo-controlled, phase 2 trial was conducted at 15 clinical sites in China. Patients aged 18-80 years with AIS within 48 hours were randomly assigned (1:1:1) to receive 160 mg GD-11, 80 mg GD-11 and placebo, two times a day for 10 days. The primary endpoint was a modified Rankin Scale (mRS) score of 0-1 at 90 days after treatment. The safety outcome was any adverse events within 90 days.

RESULTS

From 17 November 2022 to 22 March 2023, a total of 80 patients in the 160 mg GD-11 group, 79 patients in the 80 mg GD-11 group and 80 patients in the placebo group were included. The proportion of an mRS score of 0-1 at day 90 was 77.5% in the 160 mg GD-11 group, 72.2% in the 80 mg GD-11 group and 67.5% in the placebo group. Though no significant difference was found (p=0.3671), a numerically higher proportion was observed in the GD-11 group, especially in the 160 mg GD-11 group. The incidence of adverse events was similar across the three groups (p=0.1992).

CONCLUSION

GD-11 was safe and well-tolerated. A dosage of GD-11 160 mg two times a day was recommended for a large trial to investigate the efficacy.

S-Nitrosylation of Dexras1 Controls Post-Stroke Recovery via Regulation of Neuronal Excitability and Dendritic Remodeling

AIMS

Stroke is a major public health concern leading to high rates of death and disability worldwide, unfortunately with no effective treatment available for stroke recovery during the repair phase.

METHODS

Photothrombotic stroke was induced in mice. Adeno-associated viruses (AAV) were microinjected into the peri-infarct cortex immediately after photothrombotic stroke. Grid-walking task and cylinder task were used to assess motor function. Western blotting, Golgi staining, and electrophysiology recordings were performed to uncover the mechanisms.

RESULTS

The ternary complex of neuronal nitric oxide synthase (nNOS), carboxy-terminal PDZ ligand of nNOS (CAPON) and dexamethasone-induced ras protein 1 (Dexras1) is structurally beneficial for S-nitrosylation of Dexras1 (SNO-Dexras1). In our previous study, uncoupling nNOS-CAPON interaction by Tat-CAPON-12C promoted functional recovery after stroke. Here, we show that ischemia elevated the levels of nNOS-Dexras1 complex and SNO-Dexras1 in the peri-infarct cortex in the days 4-10 after stroke induction, and as excepted, Tat-CAPON-12C, a peptide disrupting nNOS-CAPON interaction, significantly reversed these changes. The above information implies that repressed SNO-Dexras1 may mediate functional-promoting effects of Tat-CAPON-12C and SNO-Dexras1 could be the vital molecular substrate for post-stroke functional recovery in the repair phage. Inhibiting the ischemia-induced SNO-Dexras1 by AAV vector-mediated knockdown of Dexras1 or over-expression of dominant negative Dexras1 (Dexras1-C11S) produced sustained recovery of motor function from stroke. In contrast, up-regulation of SNO-Dexras1 by over-expressing Dexras1 worsened stroke outcome. Using electrophysiology recordings, we also observed that silence of Dexras1 in the peri-infarct cortex increased the spike number and the miniature excitatory postsynaptic currents (mEPSCs) frequency, suggesting enhancement of neuronal excitability. In addition, silence of Dexras1 increased dendritic complexity in cultured neuron and more importantly enhanced dendritic spine density in the peri-infarct cortex, implying dendritic remodeling.

CONCLUSION

Thus, inhibition of SNO-Dexras1 positively regulates post-stroke functional recovery via enhanced neuronal excitability and dendritic remodeling. Our results identify that SNO-Dexras1 may serve as a novel target for promoting motor functional restoration from stroke in the delayed phase, shedding light on stroke treatment.

Naringenin Protected Against Blood Brain Barrier Breakdown after Ischemic Stroke through GSK-3β/ β-Catenin Pathway

Protection against blood-brain barrier (BBB) dysfunction is key to reduce the cerebral ischemia injury as its breakdown causes edema formation and extravasation of blood components and immune cells. The maintenance of BBB integrity requires the GSK-3β/β-catenin pathway activity. Naringenin (NAR), an effective monomer from Chinese herbal medicine, had potent protective effect on brain inflammatory and oxidative injury. However, whether NAR could protect the integrity of BBB during cerebral ischemia injury and the involvement of GSK-3β/β-catenin pathway in the beneficial effect of NAR was unknown. Therefore, mouse middle cerebral artery occlusion/reperfusion (IR) model was employed to answer these questions. NAR was intraperitoneally administrated once daily for 6 days immediately after IR with the dose of 10 mg/kg. BBB damage was evaluated with Evans blue. Protein levels of GSK-3β and β-catenin in vascular endothelial cells at penumbra were assessed with western blotting and immunofluorescence. The experimental data suggested that NAR improved neurological deficits, decreased the percentage of infarct volumes and neuronal apoptosis at 7d after IR. NAR improved BBB damage as evidenced by a lower permeability of Evans blue dye and upregulation of tight junction proteins such as zonula occludens-1(ZO-1), Occludin and Claudin-5. Importantly, GSK-3β/β-catenin pathway activity was related to the improvement of BBB integrity rendered by NAR. Our findings demonstrated that NAR might become a potential therapeutic drug for IR.

Acute Ischemic Stroke in the Clinic and the Laboratory: Targets for Translational Research

Ischemic stroke research has enabled significant advancements in diagnosis, treatment, and management of this debilitating disease, yet challenges remain standing in the way of better patient prognoses. In this narrative review, a fictional case illustrates challenges and uncertainties that medical professionals still face - penumbra identification, lack of neuroprotective agents, side-effects of tissue plasminogen activator, dearth of molecular biomarkers, incomplete microvascular reperfusion or no-reflow, post-recanalization hyperperfusion, blood pressure management and procedural anesthetic effects. The current state of the field is broadly reviewed per topic, with the aim to introduce a broad audience (scientist and clinician alike) to recent successes in translational stroke research and pending scientific queries that are tractable for preclinical assessment. Opportunities for co-operation between clinical and experimental stroke experts are highlighted to increase the size and frequency of strides the field makes to improve our understanding of this disease and ways of treating it.

Dynamic Changes and Clinical Significance of Plasma Galectin-3 in Patients with Acute Ischemic Stroke Undergoing Endovascular Therapy

Purpose

Galectin-3 is a key regulator of microglial proliferation and activation and may have dual and time-dependent effects on ischemic stroke. This study aimed to prospectively investigate the dynamic changes in Galectin-3 levels in patients with acute ischemic stroke receiving endovascular therapy and its clinical significance.

Patients and Methods

A total of 105 patients with acute ischemic stroke who underwent endovascular therapy were prospectively enrolled. Plasma Galectin-3 was quantitatively detected by an enzyme-linked immunosorbent assay before the operation and at 1 day, 3 days and 7 days after the operation. A linear mixed-effect model, Pearson correlation analysis and receiver operating characteristic (ROC) curve analysis were used to evaluate the dynamic changes in the plasma Galectin-3 concentration and its relationship with clinical outcomes.

Results

Increases in plasma Galectin-3 levels at 1 day and 3 days after surgery were associated with early neurological deterioration and death (both P <0.05). Increased Galectin-3 levels before surgery and at 1 day and 3 days after surgery were associated with poor prognosis (P <0.05). Pearson correlation analysis revealed that Galectin-3 levels before surgery (r =0.318, P =0.002), at 1 day (r =0.318, P =0.001), 3 days (r =0.429, P < 0.001) and 7 days after surgery (r =0.340, P =0.001) were positively correlated with NIHSS scores. The ROC curve results showed that Galectin-3 concentration had a certain predictive value for death at 1 day (AUC=0.707, P=0.013), 3 days (AUC=0.708, P=0.016) and 7 days after the operation (AUC=0.708, P=0.016), but this predictive value was lower than that of the NIHSS score.

Conclusion

In acute ischemic stroke patients receiving endovascular therapy, an increase in the plasma Galectin-3 levels were associated with death, poor prognosis, and early neurological deterioration. Galectin-3 levels were significantly correlated with the NIHSS score and had a certain predictive value for death.