New Mechanistic Insights, Novel Treatment Paradigms, and Clinical Progress in Cerebrovascular Diseases.

The past decade has brought tremendous progress in diagnostic and therapeutic options for cerebrovascular diseases as exemplified by the advent of thrombectomy in ischemic stroke, benefitting a steeply increasing number of stroke patients and potentially paving the way for a renaissance of neuroprotectants. Progress in basic science has been equally impressive. Based on a deeper understanding of pathomechanisms underlying cerebrovascular diseases, new therapeutic targets have been identified and novel treatment strategies such as pre- and post-conditioning methods were developed. Moreover, translationally relevant aspects are increasingly recognized in basic science studies, which is believed to increase their predictive value and the relevance of obtained findings for clinical application.This review reports key results from some of the most remarkable and encouraging achievements in neurovascular research that have been reported at the 10th International Symposium on Neuroprotection and Neurorepair. Basic science topics discussed herein focus on aspects such as neuroinflammation, extracellular vesicles, and the role of sex and age on stroke recovery. Translational reports highlighted endovascular techniques and targeted delivery methods, neurorehabilitation, advanced functional testing approaches for experimental studies, pre-and post-conditioning approaches as well as novel imaging and treatment strategies. Beyond ischemic stroke, particular emphasis was given on activities in the fields of traumatic brain injury and cerebral hemorrhage in which promising preclinical and clinical results have been reported. Although the number of neutral outcomes in clinical trials is still remarkably high when targeting cerebrovascular diseases, we begin to evidence stepwise but continuous progress towards novel treatment options. Advances in preclinical and translational research as reported herein are believed to have formed a solid foundation for this progress.

Microglial IRF5-IRF4 regulatory axis regulates neuroinflammation after cerebral ischemia and impacts stroke outcomes.

Microglial activation plays a central role in poststroke inflammation and causes secondary neuronal damage; however, it also contributes in debris clearance and chronic recovery. Microglial pro- and antiinflammatory responses (or so-called M1-M2 phenotypes) coexist and antagonize each other throughout the disease progress. As a result of this balance, poststroke immune responses alter stroke outcomes. Our previous study found microglial expression of interferon regulatory factor 5 (IRF5) and IRF4 was related to pro- and antiinflammatory responses, respectively. In the present study, we genetically modified the IRF5 and IRF4 signaling to explore their roles in stroke. Both in vitro and in vivo assays were utilized; IRF5 or IRF4 small interfering RNA (siRNA), lentivirus, and conditional knockout (CKO) techniques were employed to modulate IRF5 or IRF4 expression in microglia. We used a transient middle cerebral artery occlusion model to induce stroke and examined both acute and chronic stroke outcomes. Poststroke inflammation was evaluated with flow cytometry, RT-PCR, MultiPlex, and immunofluorescence staining. An oscillating pattern of the IRF5-IRF4 regulatory axis function was revealed. Down-regulation of IRF5 signaling by siRNA or CKO resulted in increased IRF4 expression, enhanced M2 activation, quenched proinflammatory responses, and improved stroke outcomes, whereas down-regulation of IRF4 led to increased IRF5 expression, enhanced M1 activation, exacerbated proinflammatory responses, and worse functional recovery. Up-regulation of IRF4 or IRF5 by lentivirus induced similar results. We conclude that the IRF5-IRF4 regulatory axis is a key determinant in microglial activation. The IRF5-IRF4 regulatory axis is a potential therapeutic target for neuroinflammation and ischemic stroke.

Pilot dose-escalation study of caffeine plus ethanol (caffeinol) in acute ischemic stroke.

BACKGROUND AND PURPOSE: In animal models, the combination of caffeine and ethanol (caffeinol) provides robust neuroprotection at blood levels that should be easily and safely achieved in humans. This study was designed to determine the safety and tolerability of ascending doses of this combination in stroke patients. METHODS: This Food and Drug Administration-approved open-label, single-arm, dose-escalation study had 3 original dose groups: group 1, caffeine 6 mg/kg plus ethanol 0.2 g/kg; groups 2 and 3, incremental increases of caffeine and ethanol by 2 mg/kg and 0.2 g/kg, respectively. Intravenous thrombolysis was encouraged if patients qualified. Drug was started within 6 hours of stroke onset, and blood levels of caffeine and ethanol were drawn at baseline and end of infusion. The target blood caffeine and ethanol ranges were 8 to 10 microg/mL and 30 to 50 mg/dL, respectively. Clinical outcome measurements included the National Institutes of Health Stroke Scale at the end of infusion, at 24 hours, and at discharge. Potential complications from caffeine and ethanol were recorded. Cases were reviewed by an independent stroke neurologist for safety. RESULTS: A total of 23 patients were recruited. Target blood caffeine and ethanol levels were reached in 0 of the 4 patients in the first group. The second dose group (caffeine 8 mg/kg plus ethanol 0.4 g/kg) included 8 patients. The median end-of-infusion caffeine and ethanol levels were within the desired target ranges. Two days after infusion, 1 patient in this group with preexisting cardiac disease and end-of-infusion caffeine and ethanol levels of 10.7 microg/mL and 69 mg/dL developed reversible congestive heart failure and required transfer to an intensive care unit. The original third dose group was canceled given achievement of target blood caffeine and ethanol levels in group 2. However, 3 new dose groups were created in an attempt to minimize the dose of ethanol. Although blood levels were proportional to dose, none of these new dose groups provided optimal blood levels. Congestive heart failure occurred in 1 other patient with previously asymptomatic cardiomyopathy. No other side effects were noted. Concomitant thrombolytic therapy was given in 8 patients, 1 of whom died of intracerebral hemorrhage. CONCLUSIONS: Caffeinol alone or combined with intravenous tissue plasminogen activator can be administered safely. Caffeine 8 mg/kg plus ethanol 0.4 g/kg produces target caffeine and ethanol levels of 8 to 10 microg/mL and 30 to 50 mg/dL, respectively. A randomized, placebo-controlled trial is needed to determine the neuroprotective effect of this combination.