An increase in AMPK/e-NOS signaling and attenuation of MMP-9 may contribute to remote ischemic perconditioning associated neuroprotection in rat model of focal ischemia

Remote Ischemic Conditioning to Reduce Perihematoma Edema in Patients with Intracerebral Hemorrhage (RICOCHET): A Randomized Control Trial

Background: Early perihematomal edema (PHE) growth is associated with worse functional outcomes at 90 days. Remote Ischemic conditioning (RIC) may reduce perihematomal inflammation if applied early to patients with intracerebral hemorrhage (ICH). We hypothesize that early RIC, delivered for seven days in patients with spontaneous ICH, may reduce PHE growth. Methods: ICH patients presenting within 6 h of symptom onset and hematoma volume < 60 milliliters (mL) were randomized to an RIC + standard care or standard care (SC) group. The primary outcome measure was calculated edema extension distance (EED), with the cm assessed on day seven. Results: Sixty patients were randomized with a mean  ±  SD age of 57.5  ±  10.8 years, and twenty-two (36.7%) were female. The relative baseline median PHE were similar (RIC group 0.75 (0.5-0.9) mL vs. SC group 0.91 (0.5-1.2) mL, p  =  0.30). The median EEDs at baseline were similar (RIC group 0.58 (0.3-0.8) cm vs. SC group 0.51 (0.3-0.8) cm, p  =  0.76). There was no difference in the median day 7 EED (RIC group 1.1 (0.6-1.2) cm vs. SC group 1 (0.9-1.2) cm, p  =  0.75). Conclusions: Early RIC therapy delivered daily for seven days was feasible. However, no decrease in EED was noted with the intervention.

Exploring the molecular mechanism of Yinao Fujian formula on ischemic stroke based on network pharmacology and experimental verification

Background

Ischemic stroke (IS) is a leading cause of long-term disability and even mortality, threatening people's lives. Yinao Fujian (YNFJ) formula is a Traditional Chinese Medicine formula that has been widely used to treat patients with IS. However, the molecular mechanism of YNFJ for the treatment of IS is still elusive. Our study aimed to explore the potential protective effect and the underlying mechanisms of YNFJ on IS using a network pharmacology approach coupled with experimental validation.

Materials and methods

Effective compounds of YNFJ were collected from BATMAN-TCM and TCMSP databases, while IS targets were obtained from GeneCards, OMIM, TTD and DrugBank databases. The protein-protein interaction (PPI) network was constructed to further screen the hub targets of YNFJ in IS treatment. GO and KEGG enrichment analyses were used to identify the critical biological processes and signaling pathways of YNFJ for IS. Moreover, Nissl staining, HE, TTC staining and Tunel staining were used in the MCAO model to prove the neuroprotective effect of YNFJ. Oxidative damage, inflammatory factor release and related pathways were tested in MCAO rat model and hypoxia-induced BV2 cell model, respectively.

Results

We found that YNFJ treatment significantly alleviated MCAO-induced nerve damage and apoptosis. Then, network pharmacology screening combined with literature research revealed IL6, TNF, PTGS2, NFKBIA and NFE2L2 as the critical targets in a PPI network. Moreover, the top 20 signaling pathways and biological processes associated with the protective effects of YNFJ on IS were enriched through GO and KEGG analyses. Further analysis indicated that NF-κB and Nrf2/HO-1 signaling pathways might be highly involved in the protective effects of YNFJ on IS. Finally, in vitro and in vivo experiments confirmed that YNFJ inhibited the release of inflammatory factors (IL-6 and TNF-α) and MDA content, and increased the activity of SOD. In terms of the mechanism, YNFJ inhibited the release of inflammatory factors by suppressing the NF-κB pathway and decreased the expression of iNOS and COX-2 to protect microglia from inflammation damage. In addition, YNFJ initiated the dissociation of Keap-1 and Nrf2, and activated the downstream protein HO-1, NQO1, thus decreasing oxidative stress.

Conclusion

Taken together, the findings in our research showed that the protective effects of YNFJ on IS were mainly achieved by regulating the NF-κB and Nrf2/HO-1 signaling pathways to inhibit oxidative stress damage and inflammatory damage of microglia.

Escin avoids hemorrhagic transformation in ischemic stroke by protecting BBB through the AMPK/Cav-1/MMP-9 pathway

BACKGROUND

Hemorrhagic transformation (HT) seriously affects the clinical application of recombinant tissue plasminogen activator (rt-PA). The main strategy for combating HT is to keep the blood-brain barrier (BBB) stable. Escin is the active ingredient of Aesculus hippocastanum and a natural mixture of triterpene saponins, and may play a part in mitigation of HT.

PURPOSE

This study sought to investigate the effect of Escin in improving rt-PA-induced HT, explore possible mechanisms, and provide new ideas for the treatment of clinical HT.

STUDY DESIGN AND METHODS

In in vivo experiments, transient middle cerebral artery occlusion (tMCAO) was undertaken in 6-week-old and 12-month-old mice, and rt-PA was administered to induce HT injury. The inhibitory effect of Escin on HT and its protective effect on neurobehavior, the BBB, and cerebrovascular endothelial cells was determined. In in vitro experiments, bEnd.3 cells were injured by oxygen-glucose deprivation/reperfusion (OGD/R) and rt-PA. The protective effect of Escin was measured by the CCK8 assay, release of lactate dehydrogenase (LDH), and expression of tight junction (TJ) proteins. In mechanistic studies, the effect of Escin on the adenosine monophosphate-activated kinase / caveolin-1 / matrix metalloprotease-9 (AMPK/Cav-1/MMP-9) pathway was investigated by employing AMPK inhibitor and Cav-1 siRNA.

RESULTS

In mice suffering from ischemia, rt-PA caused HT as well as damage to the BBB and cerebrovascular endothelial cells. Escin reduced the infarct volume, cerebral hemorrhage, improved neurobehavioral deficits, and maintained BBB integrity in rt-PA-treated tMCAO mice while attenuating bEnd.3 cells damage caused by rt-PA and OGD/R injury. Under physiological and pathological conditions, Escin increased the expression of p-AMPK and Cav-1, leading to decreased expression of MMP-9, which further attenuated damage to cerebrovascular endothelial cells, and these effects were verified with AMPK inhibitor and Cav-1 siRNA.

CONCLUSION

We revealed important details of how Escin protects cerebrovascular endothelial cells from HT, these effects were associated with the AMPK/Cav-1/MMP-9 pathway. This study provides experimental foundation for the development of new drugs to mitigate rt-PA-induced HT and the discovery of new clinical application for Escin.

Determination of significant parameters in remote ischemic postconditioning for ischemic stroke in experimental models: A systematic review and meta-analysis study

Objectives

To systematically review studies using remote ischemia postconditioning (RIPostC) for ischemic stroke in experimental models and obtain factors that significantly influence treatment outcomes.

Materials and Methods

Peer‐reviewed studies were identified and selected based on the eligibility criteria, followed by extraction of data on potentially influential factors related to model preparation, postconditioning, and measure time based on outcome measures including infarct size, neurological scales, and cell tests with autophagy, apoptosis, normal‐neuron, and damaged‐neuron counting. Then, all data were preprocessed, grouped, and meta‐analyzed with the indicator of the standardized mean difference.

Results

Fifty‐seven studies with 224 experiments (91 for infarct size, 92 for neurological scales, and 41 for cell‐level tests) were included. There was little statistical difference between different model preparations, treated body parts, number of treatments, and sides. And treatment effect was generally a positive correlation with the duration of conditioning time to stroke onset with exceptions at some time points. Based on infarct size, the number of cycles per treatment, duration of occlusion, and release per cycle showed significant differences. Combined with the effect sizes by other measures, the occlusion/release duration of 8–10 min per cycle is better than 5 min, and three cycles per treatment were most frequently used with good effects. Effect also varied when measuring at different times, showing statistical differences in infarct size and most neurological scales. RIPostC is confirmed as an effective therapeutic intervention for ischemic stroke, while the RIPostC‐mediated autophagy level being activated or inhibited remained conflicting.

Conclusions

Conditioning time, number of cycles per treatment, duration of occlusion, and release per cycle were found to influence the treatment effects of RIPostC significantly. More studies on the relevant influential factors and autophagy mechanisms are warranted.

Diabetes: Chronic Metformin Treatment and Outcome Following Acute Stroke

Aim

To evaluate if in patients with known diabetes, pretreatment metformin will lead to less severe stroke, better outcome, and lower mortality following acute stroke.

Methods

The Qatar stroke database was interrogated for stroke severity and outcome in patients with ischemic stroke. Outcome was compared in nondiabetic vs. diabetic patients and in diabetic patients on metformin vs. other hypoglycemic agents. The National Institute of Health Stroke Scale was used to measure stroke severity and 90-day modified Rankin scale (mRS) score to determine outcome following acute stroke.

Results

In total, 4,897 acute stroke patients [nondiabetic: 2,740 (56%) and diabetic: 2,157 (44%)] were evaluated. There were no significant differences in age, risk factors, stroke severity and type, or thrombolysis between the two groups. At 90 days, mRS (shift analysis) showed significantly poor outcome in diabetic patients (p < 0.001) but no differences in mortality. In the diabetic group, 1,132 patients were on metformin and 1,025 on other hypoglycemic agents. mRS shift analysis showed a significantly better outcome in metformin-treated patients (p < 0.001) and lower mortality (8.1 vs. 4.6% p < 0.001). Multivariate negative binomial analyses showed that the presence of diabetes negatively affected the outcome (90-day mRS) by factor 0.17 (incidence risk ratio, IRR, 1.17; CI [1.08-1.26]; p < 0.001) when all independent variables were held constant. In diabetic patients, pre-stroke treatment with metformin improved the outcome (90-day mRS) by factor 0.14 (IRR 0.86 [CI 0.75-0.97] p = 0.006).

Conclusion

Similar to previous reports, our study shows that diabetes adversely affects stroke outcome. The use of prior metformin is associated with better outcome in patients with ischemic stroke and results in lower mortality. The positive effects of metformin require further research to better understand its mechanism.

Immune Modulation as a Key Mechanism for the Protective Effects of Remote Ischemic Conditioning After Stroke

Remote ischemic conditioning (RIC), which involves a series of short cycles of ischemia in an organ remote to the brain (typically the limbs), has been shown to protect the ischemic penumbra after stroke and reduce ischemia/reperfusion (IR) injury. Although the exact mechanism by which this protective signal is transferred from the remote site to the brain remains unclear, preclinical studies suggest that the mechanisms of RIC involve a combination of circulating humoral factors and neuronal signals. An improved understanding of these mechanisms will facilitate translation to more effective treatment strategies in clinical settings. In this review, we will discuss potential protective mechanisms in the brain and cerebral vasculature associated with RIC. We will discuss a putative role of the immune system and circulating mediators of inflammation in these protective processes, including the expression of pro-and anti-inflammatory genes in peripheral immune cells that may influence the outcome. We will also review the potential role of extracellular vesicles (EVs), biological vectors capable of delivering cell-specific cargo such as proteins and miRNAs to cells, in modulating the protective effects of RIC in the brain and vasculature.

Remote but not Distant: a Review on Experimental Models and Clinical Trials in Remote Ischemic Conditioning as Potential Therapy in Ischemic Stroke

Stroke is one of the main causes of neurological disability worldwide and the second cause of death in people over 65 years old, resulting in great economic and social burden. Ischemic stroke accounts for 85% of total cases, and the approved therapies are based on re-establishment of blood flow, and do not directly target brain parenchyma. Thus, novel therapies are urgently needed. In this review, limb remote ischemic conditioning (RIC) is revised and discussed as a potential therapy against ischemic stroke. The review targets both (i) fundamental research based on experimental models and (ii) clinical research based on clinical trials and human interventional studies with healthy volunteers. Moreover, it also presents two approaches concerning RIC mechanisms in stroke: (i) description of the underlying cerebral cellular and molecular mechanisms triggered by limb RIC that promote neuroprotection against stroke induced damage and (ii) the identification of signaling factors involved in inter-organ communication following RIC procedure. Limb to brain remote signaling can occur via circulating biochemical factors, immune cells, and/or stimulation of autonomic nervous system. In this review, these three hypotheses are explored in both humans and experimental models. Finally, the challenges involved in translating experimentally generated scientific knowledge to a clinical setting are also discussed.

MicroRNA-532-5p upregulation protects neurological deficits after ischemic stroke through inhibition of BTB and CNC homology 1

OBJECTIVE

MicroRNA (miR)-532-5p has been reported to protect against ischemic stroke (IS), while the underlying mechanism of miR-532-5p targeting BTB and CNC homology 1 (BACH1) in IS remains unknown. Thus, we aim to detect the role of miR-532-5p in IS via targeting BACH1.

METHODS

Blood samples were collected from IS patients and healthy controls. Rat middle cerebral artery occlusion (MCAO) models were established and intracerebrally injected with altered miR-532-5p or BACH1 plasmid vectors to reveal their roles in neurological function, brain tissue pathology and inflammation in MCAO. Expression of miR-532-5p and BACH1 in patients' blood samples and rat brain tissues was assessed, and the targeting relationship between miR-532-5p and BACH1 was confirmed.

RESULTS

MiR-532-5p was downregulated and BACH1 was upregulated in IS. BACH1 was targeted by miR-532-5p. Restored miR-532-5p or inhibited BACH1 improved neurological function and inhibited inflammation and apoptosis in MCAO rats. On the contrary, miR-532-5p reduction or BACH1 overexpression had totally opposite effects on MCAO rats. The protective role of miR-532-5p for MCAO rats was reversed by upregulated BACH1.

CONCLUSION

MiR-532-5p upregulation protects against neurological deficits after IS through inhibition of BACH1.