Ghrelin reduces cerebral ischemic injury in rats by reducing M1 microglia/macrophages

The purpose of this study was to investigate the effect of Ghrelin on the polarization of microglia/ macrophages after cerebral ischemia (CI) in rats. 60 wild-type SD rats were randomly divided into sham group, CI group, CI+Ghrelin group, 20 rats in each group. The modified Longa suture method was used to establish the middle cerebral artery occlusion (MCAO) model in rats. Before surgery, Ghrelin was injected subcutaneously (100μg/kg, twice a day) for 4 consecutive weeks. After modeling, neurological function scores were performed with three behavioral experiments: mNSS score, Corner test, and Rotarod test, to evaluate the recovery of neurological function after Ghrelin treatment. At the same time, the brain tissues were collected and stained with 2,3,5-triphenyltetrazolium chloride (TTC) to detect the cerebral infarct volume. RT-qPCR was used to detect the expression of TNF-α and IL-1β in the ischemic brain tissue, and the TUNEL staining was used to detect the apoptosis of brain tissue. Flow cytometry was used to detect the percentage of M1 type microglia/macrophages which were isolated by trypsin digestion of fresh cerebral cortex. Then, the Western blotting and immunofluorescence method were used to detect the phosphorylation level of AKT (P-AKT) and AKT. Compared with the CI group, the neurological function of the rats in the CI+Ghrelin group was dramatically improved, and the cerebral infarction area was dramatically reduced. At the same time, the expression of TNF-α and IL-1β in the ischemic brain tissue of rats in the CI+Ghrelin group decreased, and the apoptotic cells in the brain tissue also decreased. Compared with the CI treatment group, the activation of M1 microglia/macrophages in the cortex of the ischemic side of the infarct and the peri-infarct area in the CI+Ghrelin group was dramatically inhibited. At the same time, the ratio of P-AKT/AKT of the brain tissue in the CI+Ghrelin group was dramatically higher than that of the CI group. In the rat cerebral ischemia model, Ghrelin can promote the repair of brain damage and the recovery of neurological function after ischemia. Its mechanism may be related to activating AKT to selectively reduce M1 microglia/macrophages, reducing inflammation and cell apoptosis in brain tissue.

Translational Stroke Research Review: Using the Mouse to Model Human Futile Recanalization and Reperfusion Injury in Ischemic Brain Tissue

The approach to reperfusion therapies in stroke patients is rapidly evolving, but there is still no explanation why a substantial proportion of patients have a poor clinical prognosis despite successful flow restoration. This issue of futile recanalization is explained here by three clinical cases, which, despite complete recanalization, have very different outcomes. Preclinical research is particularly suited to characterize the highly dynamic changes in acute ischemic stroke and identify potential treatment targets useful for clinical translation. This review surveys the efforts taken so far to achieve mouse models capable of investigating the neurovascular underpinnings of futile recanalization. We highlight the translational potential of targeting tissue reperfusion in fully recanalized mouse models and of investigating the underlying pathophysiological mechanisms from subcellular to tissue scale. We suggest that stroke preclinical research should increasingly drive forward a continuous and circular dialogue with clinical research. When the preclinical and the clinical stroke research are consistent, translational success will follow.

Abstract 1122‐000123: Association of 24‐hour Blood Pressure Parameters Post‐Thrombectomy with Functional Outcomes According to Collateral Status

Introduction : Higher blood pressure (BP) most post mechanical thrombectomy (MT) can restore perfusion to the ischemic brain tissue depending on collateral status. We aim to determine the association of 24‐hour post‐MT BP parameters with the functional outcome depending on the pre‐MT collateral status. Methods : We performed a retrospective chart review of patients who underwent MT at a comprehensive stroke center from 7/2014 to 12/2020. The patients were divided into two groups (good versus bad) depending on collateral status. A board‐certified neuroradiologist, who was blinded to the clinical outcomes, used collateral grading scales of Mass ≥3 and modified‐Tan>50% to designate good collaterals on the pre‐MT CT Angiogram. A binary logistic regression analysis was performed, controlling for age, sex, NIHSS, ASPECTS≥6, TICI score≥2b, time to thrombectomy, LDL, Hemoglobin‐A1C, intravenous‐alteplase, with the 24‐hour post‐MT BP parameters as the predictors. The outcomes were good functional outcome (3‐month mRS≤2) and mortality. Results : 220 patients met the inclusion criteria. 24‐hour BP parameters of standard deviation (SD) SBP (OR, 1.16; 95% CI,1.01‐1.33; P 0.047) and maximum DBP (OR, 1.05; 95% CI,1.01‐1.09; P 0.036) had an association with a good functional outcome, while SD SBP (OR, 1.15; 95% CI,1.01‐1.31; P 0.045), coefficient variation (CV) SBP (OR, 1.19; 95% CI,1.01‐1.41; P 0.043), SBP range (OR, 1.04; 95% CI,1.01‐1.07; P 0.046), maximum DBP (OR, 0.95; 95% CI,0.91‐0.99; P 0.016), pulse pressure (OR, 1.09; 95% CI,1.02‐1.16; P 0.022) and SBP ≥140 (OR, 5.85; 95% CI,1.11‐30.85; P 0.038) had an association with mortality in patients with good collaterals according to Mass grading. 24‐hour BP parameters of SD SBP (OR, 1.13; 95% CI,1.04‐1.24; P 0.007), CV SBP (OR, 1.18; 95% CI,1.05‐1.32; P 0.006), SBP range (OR, 1.04; 95% CI,1.01‐1.06; P 0.008) and maximum DBP (OR, 0.97; 95% CI,0.94‐1; P 0.02) had an association with mortality in patients with good collaterals according to modified‐Tan grading. There was no such association in patients with bad collaterals Conclusions : Various 24‐hour BP parameters post‐MT are associated with a functional outcome or mortality in patients with good collaterals, unlike in patients with bad collaterals.

Can immature granulocytes indicate mortality in patients with acute ischemic stroke?

Background & Objective: Stroke is the most common cause of permanent disability and the most important cause of mortality. Acute ischemic stroke (AIS) reveals inflammation in the ischemic brain tissue. Ischemic tissue causes proinflammatory cytokine release and aggregation of immune cells. Therefore in this study, we aimed to investigate the role of immature granulocyte (IG) in showing 30-day mortality in patients with AİS. Methods: This study was designed as a single-centered, retrospective cohort study. Patients aged >18 years who were diagnosed with AIS in the tertiary emergency department were included in this study. Patients were divided into two groups as low (<0.6%) and high (≥0.6%) by IG values. Demographic and laboratory parameters were compared between the groups at admission to the emergency department. Results: Our study consisted of 172 patients diagnosed with AIS, who met the inclusion criteria. The average age of the study group was 69.19 ± 14.34 years, and 94 (54.7%) of the patients were male. 98 (56.9%) patients were in the low IG group, and 74 (43.1%) of them were in the poor outcome group. IG at the cut-off value of 1.3 was shown to predict mortality in patients with AIS with 80.5% sensitivity and 93.2% specificity (area under the curve: 0.715 95% CI: 0.623-0.807, p <0.001) Conclusion: The results of our study showed that IG is a new and simple predictor to predict 30-day prognosis in patients with AIS.

A dietary vitamin B12 deficiency impairs motor function and changes neuronal survival and choline metabolism after ischemic stroke to the sensorimotor cortex in middle aged male and female mice

The majority of the population is growing older, in 2000, 10% of the total population of the world was over 60 years old and the proportion is projected to increase to 21% by 2050. Currently, ischemic stroke predominately affects the elderly. Nutrition is a modifiable risk factor for stroke, as people age their ability to absorb some nutrients decreases. A primary example is vitamin B12, most older adults are deficient in vitamin B12 because of changes in breakdown and absorption of the vitamin that take place during the aging process. Using a mouse model system, we investigated the role of vitamin B12 deficiency in ischemic stroke outcome and investigate mechanistic changes in ischemic versus non-ischemic brain tissue. At 10-weeks of age male and female C57Bl/6J mice were put on control or vitamin B12 deficient diets for 4-weeks prior to ischemic damage. At 14 weeks of age, we induced ischemic stroke in the sensorimotor cortex using the photothrombosis model. Animals were continued on diets for 4 weeks after damage. At 18 weeks of age, we assessed stroke outcome using the accelerating rotarod and forepaw placement tasks. After the collection of behavioral data, we euthanized animals and collected brain, blood, and liver tissues to assess histological and biochemical measurements. All animals maintained on the vitamin B12 deficient diet had increased levels of total homocysteine in plasma and liver tissue. Male and female mice maintained on a vitamin B12 deficient diet had impairments in balance and coordination on the accelerating rotarod compared to control diet animals after ischemic stroke. In ischemic brain tissue no difference between groups in lesion volume was observed. More neuronal survival was present in ischemic brain tissue of the vitamin B12 deficient group compared to controls. There were changes in choline metabolites in ischemic brain tissue as a result of diet and sex. In conclusion, the data presented in this study confirms that a vitamin B12 deficiency impacts motor function in older adult male and female mice after ischemic stroke. The mechanisms driving this change may be a result of neuronal survival and compensation in choline metabolism within the damaged brain tissue.

Integrative cerebral blood flow regulation in ischemic stroke

Optimizing cerebral perfusion is key to rescuing salvageable ischemic brain tissue. Despite being an important determinant of cerebral perfusion, there are no effective guidelines for blood pressure (BP) management in acute stroke. The control of cerebral blood flow (CBF) involves a myriad of complex pathways which are largely unaccounted for in stroke management. Due to its unique anatomy and physiology, the cerebrovascular circulation is often treated as a stand-alone system rather than an integral component of the cardiovascular system. In order to optimize the strategies for BP management in acute ischemic stroke, a critical reappraisal of the mechanisms involved in CBF control is needed. In this review, we highlight the important role of collateral circulation and re-examine the pathophysiology of CBF control, namely the determinants of cerebral perfusion pressure gradient and resistance, in the context of stroke. Finally, we summarize the state of our knowledge regarding cardiovascular and cerebrovascular interaction and explore some potential avenues for future research in ischemic stroke.

Inhibition of Notch1 Signal Promotes Brain Recovery by Modulating Glial Activity

BackgroundNotch1 signaling inhibiton with N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine t-butylester] (DAPT) treatment could promote brain recovery and the intervention effect is different between striatum (STR) and cortex (CTX), which might be accounted for changed glial activities but the in-depth mechanism is still unknown. The purpose of this study was to identify whether DAPT could modulate microglial subtype shifts and astroglial-endfeet aquaporin-4 (AQP4) mediated waste solute drainage.MethodsSprague-Dawley rats (n=10) were subjected to 90min of middle cerebral artery occlusion (MCAO) and were treated with DAPT (n=5) or act as control with no treatment (n=5). Two groups of rats underwent MRI scans at 24h and 4 week following stroke, and sacrificed at 4 week after stroke for immunofluorescence (IF).ResultsCompared with control rats, MRI data showed brain recovery in ipsilateral STR but not CTX. And IF showed decreased pro-inflammatory M1 microglia and increased anti-inflammatory M2 microglia in striatal lesion core and peri-lesions of STR, CTX. Meanwhile, IF showed decreased AQP4 polarity in ischemic brain tissue, however, AQP4 polarity in striatal peri-lesions of DAPT treated rats was higher than that in control rats but shows no difference in cortical peri-lesions between control and treated rats. ConclusionsThe present study indicated that DAPT could promote protective microglia subtype shift and striatal astrocyte mediated waste solute drainage.

The Role of NF-κB Triggered Inflammation in Cerebral Ischemia

Cerebral ischemia is a devastating disease that affects many people worldwide every year. The neurodegenerative damage as a consequence of oxygen and energy deprivation, to date, has no known effective treatment. The ischemic insult is followed by an inflammatory response that involves a complex interaction between inflammatory cells and molecules which play a role in the progression towards cell death. However, there is presently a matter of controversy over whether inflammation could either be involved in brain damage or be a necessary part of brain repair. The inflammatory response is triggered by inflammasomes, key multiprotein complexes that promote secretion of pro-inflammatory cytokines. An early event in post-ischemic brain tissue is the release of certain molecules and reactive oxygen species (ROS) from injured neurons which induce the expression of the nuclear factor-kappaB (NF-κB), a transcription factor involved in the activation of the inflammasome. There are conflicting observations related to the role of NF-κB. While some observe that NF-κB plays a damaging role, others suggest it to be neuroprotective in the context of cerebral ischemia, indicating the need for additional investigation. Here we discuss the dual role of the major inflammatory signaling pathways and provide a review of the latest research aiming to clarify the relationship between NF-κB mediated inflammation and neuronal death in cerebral ischemia.

Low Hypoperfusion Intensity Ratio Is Associated with a Favorable Outcome Even in Large Ischemic Core and Delayed Recanalization Time

In ischemic brain tissue, hypoperfusion severity can be assessed using the hypoperfusion intensity ratio (HIR). We evaluated the link between HIR and clinical outcomes after successful recanalization by endovascular treatment. We retrospectively reviewed 162 consecutive patients who underwent endovascular treatment for intracranial large vessel occlusion. The HIR was calculated using an automated software program, with initial computed tomography perfusion images. The HIR was compared between patients with and without favorable outcomes. To observe the modifying effect of the HIR on the well-known major outcome determinants, regression analyses were performed in the low and high HIR groups. The median HIR value was significantly lower in patients with a favorable outcome, with an optimal cut-off point of 0.54. The HIR was an independent factor for a favorable outcome in a specific multivariable model and was significantly correlated with the Alberta Stroke Program Early Computed Tomography Score (ASPECTS). In contrast to the high HIR group, the low HIR group showed that ASPECTS and onset-to-recanalization time were not independently associated with a favorable outcome. Finally, the low HIR group had a more favorable outcome even in cases with an unfavorable ASPECTS and onset-to-recanalization time. The HIR could be useful in predicting outcomes after successful recanalization.