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Abstract Acid sphingomyelinase (ASM) inhibitors are widely used for the treatment of post-stroke depression. They promote neurological recovery in animal stroke models via neurorestorative effects. In a previous study, we found that antidepressants including amitriptyline, fluoxetine, and desipramine increase cerebral angiogenesis post-ischemia/reperfusion (I/R) in an ASM-dependent way. To elucidate the underlying mechanisms, we investigated the effects of the functional ASM inhibitor amitriptyline in two models of I/R injury, that is, in human cerebral microvascular endothelial hCMEC/D3 cells exposed to oxygen-glucose deprivation and in mice exposed to middle cerebral artery occlusion (MCAO). In addition to our earlier studies, we now show that amitriptyline increased mitochondrial reactive oxygen species (ROS) formation in hCMEC/D3 cells and increased ROS formation in the vascular compartment of MCAO mice. ROS formation was instrumental for amitriptyline’s angiogenic effects. ROS formation did not result in excessive endothelial injury. Instead, amitriptyline induced a profound metabolic reprogramming of endothelial cells that comprised reduced endothelial proliferation, reduced mitochondrial energy metabolism, reduced endoplasmic reticulum stress, increased autophagy/mitophagy, stimulation of antioxidant responses and inhibition of apoptotic cell death. Specifically, the antioxidant heme oxygenase-1, which was upregulated by amitriptyline, mediated amitriptyline’s angiogenic effects. Thus, heme oxygenase-1 knockdown severely compromised angiogenesis and abolished amitriptyline’s angiogenic responses. Our data demonstrate that ASM inhibition reregulates a complex network of metabolic and mitochondrial responses post-I/R that contribute to cerebral angiogenesis without compromising endothelial survival.

BackgroundOlder adults often face challenges in medication management due to multimorbidity and complex medication regimens, which frequently go unreported. Unrecognized problems, however, may lead to a loss of drug efficacy and harmful side effects. This study aimed to quantify the prevalence of such problems by applying a novel video-based assessment procedure in a sample of elderly patients.MethodsIn this study, 67 elderly in-patients (≥70 years old and regularly taking ≥5 different drugs autonomously) from the ABLYMED study participated in a placebo-based assessment of medication management with five different dosage forms in an instructed manner while being filmed. Patient performance was quantified by the median value of two raters who evaluated each step of medication administration, which were summed to sum scores for each dosage form and an overall impression for each dosage form with a standardized and previously validated rating scheme.ResultsThe median (Q1;Q3) sum score for tablets was 7.0 (5.0;8.0) with a theoretical range between 4.0 and 17.0, for eye-drops 2.0 (1.0;2.0) with a theoretical range between 1.0 and 5.0, for oral drops 4.0 (3.0;6.0) with a theoretical range between 3.0 and 12.0, for pens 7.0 (5.0;9.0) with a theoretical range between 4.0 and 17.0 and for patches 5.0 (4.0;7.0) with a theoretical range between 3.0 and 15.0. The most difficult step of medication administration was peeling off the protective liner of a patch: 30% had severe difficulties or it was not possible, 21% had moderate difficulties and 49% had mild or no difficulties.DiscussionIn a sample of patients with autonomous medication management, our novel assessment procedure identified a substantial fraction of patients with handling problems for each dosage form. This suggests that patients´ medication management problems should be assessed regularly in clinical routine and tackled by patient-individual training or modification of the prescribed drug regimens to achieve effective drug therapy in the elderly.

Abstract Microglia are critically involved in post‐stroke inflammation affecting neurological outcomes. Lipid droplet (LD) accumulation in microglia results in a dysfunctional and pro‐inflammatory state in the aged brain and worsens the outcome of neuroinflammatory and neurodegenerative diseases. However, the role of LD‐rich microglia (LDRM) under stroke conditions is unknown. Using in vitro and in vivo stroke models, herein accumulation patterns of microglial LD and their corresponding microglial inflammatory signaling cascades are studied. Interactions between temporal and spatial dynamics of lipid profiles and microglial phenotypes in different post‐stroke brain regions are found. Hence, microglia display enhanced levels of LD accumulation and elevated perilipin 2 (PLIN2) expression patterns when exposed to hypoxia or stroke. Such LDRM exhibit high levels of TNF‐α, IL‐6, and IL‐1β as well as a pro‐inflammatory phenotype and differentially expressed lipid metabolism‐related genes. These post‐ischemic alterations result in distinct lipid profiles with spatial and temporal dynamics, especially with regard to cholesteryl ester and triacylglycerol levels, further exacerbating post‐ischemic inflammation. The present study sheds new light on the dynamic changes of brain lipid profiles and aggregation patterns of LD in microglia exposed to ischemia, demonstrating a mutual mechanism between microglial phenotype and function, which contributes to progression of brain injury.

Sphingolipids comprise a class of lipids, which are composed of a sphingoid base backbone and are essential structural components of cell membranes. Beyond their role in maintaining cellular integrity, several sphingolipids are pivotally involved in signaling pathways controlling cell proliferation, differentiation, and death. The brain exhibits a particularly high concentration of sphingolipids and dysregulation of the sphingolipid metabolism due to ischemic injury is implicated in consecutive pathological events. Experimental stroke studies revealed that the stress sphingolipid ceramide accumulates in the ischemic brain post-stroke. Specifically, counteracting ceramide accumulation protects against ischemic damage and promotes brain remodeling, which translates into improved behavioral outcome. Sphingomyelin substantially influences cell membrane fluidity and thereby controls the release of extracellular vesicles, which are important vehicles in cellular communication. By modulating sphingomyelin content, these vesicles were shown to contribute to behavioral recovery in experimental stroke studies. Another important sphingolipid that influences stroke pathology is sphingosine-1-phosphate, which has been attributed a pro-angiogenic function, that is presumably mediated by its effect on endothelial function and/or immune cell trafficking. In experimental and clinical studies, sphingosine-1-phosphate receptor modulators allowed to modify clinically significant stroke recovery. Due to their pivotal roles in cell signaling, pharmacological compounds modulating sphingolipids, their enzymes or receptors hold promise as therapeutics in human stroke patients.

Abstract Activation of the kallikrein-kinin system promotes vascular leakage, inflammation, and neurodegeneration in ischemic stroke. Inhibition of plasma kallikrein (PK) – a key component of the KKS – in the acute phase of ischemic stroke has been reported to reduce thrombosis, inflammation, and damage to the blood-brain barrier. However, the role of PK during the recovery phase after cerebral ischemia is unknown. To this end, we evaluated the effect of subacute PK inhibition starting from day 3 on the recovery process after transient middle artery occlusion (tMCAO). Our study demonstrated a protective effect of PK inhibition by reducing infarct volume and improving functional outcome at day 7 after tMCAO. In addition, we observed reduced thrombus formation in cerebral microvessels, fewer infiltrated immune cells, and an improvement in blood-brain barrier integrity. This protective effect was facilitated by promoting tight junction reintegration, reducing detrimental matrix metalloproteinases, and upregulating regenerative angiogenic markers. Our findings suggest that PK inhibition in the subacute phase might be a promising approach to accelerate the post-stroke recovery process.

Abstract Background The intravenous delivery of adult neural precursor cells (NPC) has shown promising results in enabling cerebroprotection, brain tissue remodeling, and neurological recovery in young, healthy stroke mice. However, the translation of cell-based therapies to clinical settings has encountered challenges. It remained unclear if adult NPCs could induce brain tissue remodeling and recovery in mice with hyperlipidemia, a prevalent vascular risk factor in stroke patients. Methods Male mice on a normal (regular) diet or on cholesterol-rich Western diet were exposed to 30 min intraluminal middle cerebral artery occlusion (MCAO). Vehicle or 106 NPCs were intravenously administered immediately after reperfusion, at 3 day and 7 day post-MCAO. Neurological recovery was evaluated using the Clark score, Rotarod and tight rope tests over up to 56 days. Histochemistry and light sheet microscopy were used to examine ischemic injury and brain tissue remodeling. Immunological responses in peripheral blood and brain were analyzed through flow cytometry. Results NPC administration reduced infarct volume, blood–brain barrier permeability and the brain infiltration of neutrophils, monocytes, T cells and NK cells in the acute stroke phase in both normolipidemic and hyperlipidemic mice, but increased brain hemorrhage formation and neutrophil, monocyte and CD4+ and CD8+ T cell counts and activation in the blood of hyperlipidemic mice. While neurological deficits in hyperlipidemic mice were reduced by NPCs at 3 day post-MCAO, NPCs did not improve neurological deficits at later timepoints. Besides, NPCs did not influence microglia/macrophage abundance and activation (assessed by morphology analysis), astroglial scar formation, microvascular length or branching point density (evaluated using light sheet microscopy), long-term neuronal survival or brain atrophy in hyperlipidemic mice. Conclusions Intravenously administered NPCs did not have persistent effects on post-ischemic neurological recovery and brain remodeling in hyperlipidemic mice. These findings highlight the necessity of rigorous investigations in vascular risk factor models to fully assess the long-term restorative effects of cell-based therapies. Without comprehensive studies in such models, the clinical potential of cell-based therapies cannot be definitely determined.

Abstract Background Stroke remains one of the leading causes of long-term disability worldwide, and the development of effective restorative therapies is hindered by an incomplete understanding of intrinsic brain recovery mechanisms. Growing evidence indicates that the brain extracellular matrix (ECM) has major implications for neuroplasticity. Here we explored how perineuronal nets (PNNs), the facet-like ECM layers surrounding fast-spiking interneurons, contribute to neurological recovery after focal cerebral ischemia in mice with and without induced stroke tolerance. Methods We investigated the structural remodeling of PNNs after stroke using 3D superresolution stimulated emission depletion (STED) and structured illumination (SR-SIM) microscopy. Superresolution imaging allowed for the precise reconstruction of PNN morphology using graphs, which are mathematical constructs designed for topological analysis. Focal cerebral ischemia was induced by transient occlusion of the middle cerebral artery (tMCAO). PNN-associated synapses and contacts with microglia/macrophages were quantified using high-resolution confocal microscopy. Results PNNs undergo transient structural changes after stroke allowing for the dynamic reorganization of GABAergic input to motor cortical L5 interneurons. The coherent remodeling of PNNs and their perforating inhibitory synapses precedes the recovery of motor coordination after stroke and depends on the severity of the ischemic injury. Morphological alterations in PNNs correlate with the increased surface of contact between activated microglia/macrophages and PNN-coated neurons. Conclusions Our data indicate a novel mechanism of post stroke neuroplasticity involving the tripartite interaction between PNNs, synapses, and microglia/macrophages. We propose that prolonging PNN loosening during the post-acute period can extend the opening neuroplasticity window into the chronic stroke phase. Graphical Abstract

Due to worldwide demographic change, the number of older persons in the population is increasing. Aging is accompanied by changes of sleep structure, deposition of beta-amyloid (Aß) and tau proteins and vascular changes and can turn into mild cognitive impairment (MCI) as well as dementia. Sleep disorders are discussed both as a risk factor for and as a consequence of MCI/dementia. Cross-sectional and longitudinal population-based as well as case–control studies revealed sleep disorders, especially sleep-disorderded breathing (SDB) and excessive or insufficient sleep durations, as risk factors for all-cause MCI/dementia. Regarding different dementia types, SDB was especially associated with vascular dementia while insomnia/insufficient sleep was related to an increased risk of Alzheimer’s disease (AD). Scarce and still inconsistent evidence suggests that therapy of sleep disorders, especially continuous positive airway pressure (CPAP) in SDB, can improve cognition in patients with sleep disorders with and without comorbid dementia and delay onset of MCI/dementia in patients with sleep disorders without previous cognitive impairment. Regarding potential pathomechanisms via which sleep disorders lead to MCI/dementia, disturbed sleep, chronic sleep deficit and SDB can impair glymphatic clearance of beta-amyloid (Aß) and tau which lead to amyloid deposition and tau aggregation resulting in changes of brain structures responsible for cognition. Orexins are discussed to modulate sleep and Aß pathology. Their diurnal fluctuation is suppressed by sleep fragmentation and the expression suppressed at the point of hippocampal atrophy, contributing to the progression of dementia. Additionally, sleep disorders can lead to an increased vascular risk profile and vascular changes such as inflammation, endothelial dysfunction and atherosclerosis which can foster neurodegenerative pathology. There is ample evidence indicating that changes of sleep structure in aging persons can lead to dementia and also evidence that therapy of sleep disorder can improve cognition. Therefore, sleep disorders should be identified and treated early.

Aim: Stroke is one of the leading causes of death and disability worldwide. Plasma biomarkers have long been used to evaluate physiological or pathological processes and to make predictions about the outcome of stroke patients. The current systematic review is focused on genetic plasma biomarkers as a new potential prognostic indicator for post-stroke recovery. The aim of the present systematic review is to assess the potential of genetic plasma biomarkers associated with stroke to predict post-stroke recovery. Methods: The search strategy used PubMed and Web of Science databases to identified 166 studies that investigated genetic plasma biomarkers in patients with stroke between 2017 and 2021. However, only 21 of them met the inclusion criteria. Results: The identified genetic biomarkers can be divided into: (i) serum/plasma circular RNA (circRNA) associated with stroke onset or recurrence (5; 23.80%), (ii) genetic polymorphisms associated with the atherosclerotic process and stroke recurrence (6; 28.57%), (iii) serum/plasma long non-coding RNA (lncRNA) levels involved in immunity/inflammatory processes (4; 19.04%), (iv) marker of DNA methylation associated with stroke onset and outcome (3; 14.28%), and (v) proteins and pathways of stroke identified by serum/ plasma proteomics/genomics analysis (3; 14.28%). Conclusions: Overall, more than 100 potential biomarkers were found and the data suggest that combinations of plasma genetic biomarkers might be used as a better predictor for stroke.

Ischemic stroke is a highly prevalent condition that frequently results in life-long disability and death. Considerable efforts have been made to establish treatments that prevent secondary ischemic damage and promote stroke recovery. Until now, the recanalization of occluded blood vessels via thrombolysis and thrombectomy, although highly potent, remains the only treatment in humans that enhances stroke outcome. Small extracellular vesicles are non-replicating, nano-sized (70–150 nm) lipid bilayer-enclosed vesicles, which have shown remarkable biological activities in various physiological and pathophysiological contexts. When administered post-stroke, mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) induce neuroprotection, promote brain remodeling and plasticity, and enhance neurological recovery in rodents and non-human primates via mechanisms that involve immunomodulation and anti-inflammation. In this review, experimental studies on the therapeutic actions of MSC-EVs in animal stroke models are summarized and perspectives for clinical translation are outlined.

The available evidence suggests that affective disorders, such as depression and anxiety, increase risk for accelerated cognitive decline and late-life dementia in aging individuals. Behavioral neuropsychology studies also showed that cognitive decline is a central feature of aging impacting the quality of life. Motor deficits are common after traumatic brain injuries and stroke, affect subjective well-being, and are linked with reduced quality of life. Currently, restorative therapies that target the brain directly to restore cognitive and motor tasks in aging and disease are available. However, the very same drugs used for therapeutic purposes are employed by athletes as stimulants either to increase performance for fame and financial rewards or as recreational drugs. Unfortunately, most of these drugs have severe side effects and pose a serious threat to the health of athletes. The use of performance-enhancing drugs by children and teenagers has increased tremendously due to the decrease in the age of players in competitive sports and the availability of various stimulants in many forms and shapes. Thus, doping may cause serious health-threatening conditions including, infertility, subdural hematomas, liver and kidney dysfunction, peripheral edema, cardiac hypertrophy, myocardial ischemia, thrombosis, and cardiovascular disease. In this review, we focus on the impact of doping on psychopathological disorders, cognition, and depression. Occasionally, we also refer to chronic use of therapeutic drugs to increase physical performance and highlight the underlying mechanisms. We conclude that raising awareness on the health risks of doping in sport for all shall promote an increased awareness for healthy lifestyles across all generations.

Background and objectivesEmotional and cognitive deficits are prevalent in strokes involving the thalamus. In contrast to cognitive deficits, emotional deficits have not been studied prospectively in isolated thalamic stroke.MethodsIn 37 ischemic thalamic stroke patients (57.0 [50.0; 69.5] years [median (Q1; Q3)], 21 males, 5 anterior, 12 paramedian, 20 inferolateral vascular territory), and 37 non-stroke control patients matched for age and sex, we prospectively examined depression, anxiety, activities of daily living, and quality of life at 1, 6, 12, and 24 months post-stroke using the Hospital-Anxiety-and-Depression Scale (HADS), Nürnberger-Alters-Alltagsaktivitäten scale (NAA), and Short Form-36 (SF36) questionnaire. Voxel-based lesion-symptom mapping (VLSM) and lesion-subtraction analyzes were performed to determine associations between questionnaire scores and thalamic stroke topography.ResultsAt 1 month post-stroke, anterior thalamic stroke patients had higher depression scores [8.0 (7.5; 10.5)] than paramedian [4.5 (1.0; 5.8)] and inferolateral [4.0 (1.0; 7.0)] thalamic stroke patients. Furthermore, anterior thalamic stroke patients had higher anxiety scores [11.0 (8.0; 14.5)] than their matched controls [2.5 (2.0; 2.5)], paramedian [4.5 (1.0; 5.8)] and inferior [4.0 (1.0; 7.0)] thalamic stroke patients. Depression and anxiety scores in anterior thalamic stroke patients remained high across the follow-up [depression: 9.0 (3.5; 13,8); anxiety:10.05 (2.8, 14.5)].Physical health assessed by SF36 was intact in anterior [1 month post-stroke: T-score = 55.9 (37.0; 57.6)] but reduced in inferolateral [44.5(32.4; 53.1)] thalamic stroke, whereas mental health was reduced in anterior thalamic stroke [32.0 (29.8; 47.3)].VLSM confirmed that voxels in the anterior thalamus around Montreal Neurological Institute (MNI) coordinates X = −8, Y = −12, Z = 2 were more often affected by the stroke in depressed (HADS-score ≥ 8) than non-depressed (HADS-score

Abstract Background Older people often suffer from multimorbidity resulting in polypharmacy. The correct administration of medication is a crucial factor influencing treatment efficacy. However, tools for evaluating the ability to self-administer different dosage forms of medications are lacking. The objectives of the ABLYMED study are to 1) assess the ability to self-administer different dosage forms of medication in older non-demented in-hospital patients who report autonomous management of medication, 2) identify factors influencing the ability to self-administer medication, and 3) develop a standardized tool to validly assess the ability to self-administer different dosage forms of medications based on the final study results. Methods One hundred in-patients from the department of orthopedics and trauma surgery of the University Hospital Düsseldorf ≥ 70 years of age and regularly taking ≥ 5 different drugs autonomously will be prospectively recruited into the observational cross-sectional single-center ABLYMED study. Patients undergo an interview addressing demographic and clinical information, medication history (which medications are taken since when, in which dose and dosage form, and subjective proficiency of taking these medications), medication adherence, and factors possibly influencing adherence including personality traits and perceived quality of the medication regimen. Quality of the medication regimen is also rated by clinicians according to validated lists. Further, patients receive a comprehensive geriatric assessment including measures of cognition, mobility, and functional status. The ability to self-administer medication is assessed by having patients perform different tasks related to medication self-administration, which are video recorded and rated by different experts. The patients’ self-reported ability will be correlated with the observed performance in the self-administration tasks. Further, factors correlating with the reported and observed ability to self-administer medication will be evaluated using correlation and regression models. Based on the final study results, a novel tool to assess the ability of older patients to self-administer medication will be developed. Discussion In addition to guideline-based pharmacotherapy, correct intake of prescribed medication is crucial for optimal therapy of multimorbidity in older people. Tools to validly assess the ability of older patients to self-administer different dosage forms of medications are lacking, but should be included in comprehensive geriatric assessments to secure functional health. Trial registration Development of an assessment instrument to evaluate the ability to manage various dosage forms, DRKS-ID: DRKS00025788 , (date of registration: 07/09/2021).

ACKR3 is a critical regulator of platelet-mediated thrombosis and organ injury following ischemia/reperfusion. Platelet ACKR3 surface expression is independently associated with all-cause mortality in patients with cardiovascular diseases.

How ischaemic stroke affects the brain borders is not fully understood. Here the authors show that a stroke-associated myeloid cell population occurs exclusively in brain parenchyma that shares features with neurodegenerative microglia and blockade of proteins on these cells can ameliorate stroke symptoms.

BackgroundOlder people often experience medication management problems due to multimorbidity, polypharmacy and medication complexity. There is often a large gap between patients’ self-reported and actual abilities to handle the self-administration of their medication. Here we report on the development and evaluation of a new tool to assess the ability of non-demented hospitalized patients to self-administer medication in different dosage forms. To this end, we video-recorded the patients’ medication management performance and implemented a novel assessment scheme, which was applied by several independent raters.MethodsSixty-seven in-patients ≥70 years of age and regularly taking ≥5 different drugs autonomously of the ABLYMED study agreed to the video recording of their medication management performance with five different dosage forms. All raters underwent a training and applied a standardized assessment form and written guide with rating rules for evaluation. In a pilot phase, video recordings of three patients were rated by 19 raters (15 medical students, two expert raters to determine a reference standard, and two main raters who later rated the total sample). In the rating phase, based on the ratings obtained from the two main raters, we determined interrater (assessed every section of 20 patients as agreement between the raters at one point of time) and intrarater (assessed as consistency within each rater across three points of time) agreement by intraclass correlation analysis.ResultsIn the pilot phase we obtained an overall sufficient agreement pattern, with an adjustment of the rating rules for patches. In the rating phase we achieved satisfactory agreement between the two raters (interrater reliability) and across different points of time (intrarater reliability). For two dosage forms (eye-drops and pen), rater training needed to be repeated to reach satisfactory levels.DiscussionOur novel rating procedure was found to be objective, valid and reproducible, given appropriate training of the raters. Our findings are an important part of a larger research project to implement a novel assessment for the ability to self-administer medication in different dosage forms. Further, they can support the development of patient trainings to improve medication management and secure independent living.

Spinal cord injury (SCI) induces neurological deficits associated with long-term functional impairments. Since the current treatments remain ineffective, novel therapeutic options are needed. Besides its effect on bipolar mood disorder, lithium was reported to have neuroprotective activity in different neurodegenerative conditions, including SCI. In SCI, the effects of lithium on long-term neurological recovery and neuroplasticity have not been assessed. We herein investigated the effects of intraperitoneally administered lithium chloride (LiCl) on motor coordination recovery, electromyography (EMG) responses, histopathological injury and remodeling, and axonal plasticity in mice exposed to spinal cord transection. At a dose of 0.2, but not 2.0 mmol/kg, LiCl enhanced motor coordination and locomotor activity starting at 28 days post-injury (dpi), as assessed by a set of behavioral tests. Following electrical stimulation proximal to the hemitransection, LiCl at 0.2 mmol/kg decreased the latency and increased the amplitude of EMG responses in the denervated hindlimb at 56 dpi. Functional recovery was associated with reduced gray and white matter atrophy rostral and caudal to the hemitransection, increased neuronal survival and reduced astrogliosis in the dorsal and ventral horns caudal to the hemitransection, and increased regeneration of long-distance axons proximal and distal to the lesion site in mice receiving 0.2 mmol/kg, but not 2 mmol/kg LiCl, as assessed by histochemical and immunohistochemical studies combined with anterograde tract tracing. Our results indicate that LiCl induces long-term neurological recovery and neuroplasticity following SCI.

Stroke is primarily a neurodegenerative disease but can also severely impact the functions of other vital organs and deteriorate disease outcomes. A malfunction of the gastrointestinal tract (GIT), commonly observed in stroke patients, is often characterized by severe bowel obstruction, intestinal microbiota changes and inflammation. Over-activated immune cells after stroke are the major contributors to endorse intestinal inflammation and may induce damage to single-layer epithelial cell barriers. The post-stroke leakage of intestinal barriers may allow the translocation and dissemination of resident microflora to systemic organs and cause sepsis. This overshooting systemic immune reaction fuels ongoing inflammation in the degenerating brain and slows recovery. Currently, the therapeutic options to treat these GIT-associated anomalies are very limited and further research is required to develop novel treatments. In this mini-review, we first discuss the current knowledge from clinical studies and experimental stroke models that provide strong evidence of the existence of post-stroke GIT complications. Then, we review the literature regarding novel therapeutic approaches that might help to maintain GIT homeostasis and improve neurological outcomes in stroke patients.

Platelets are key mediators of thrombus formation and inflammation during the acute phase of ischaemic stroke. Particularly, the platelet glycoprotein (GP) receptors GPIbα and GPVI have been shown to mediate platelet adhesion and activation in the ischaemic brain. GPIbα and GPVI blockade could reduce infarct volumes and improve functional outcome in mouse models of acute ischaemic stroke, without concomitantly increasing intracerebral haemorrhage. However, the functional role of platelets during long-term stroke recovery has not been elucidated so far.Thus, we here examined the impact of platelet depletion on post-stroke recovery after transient middle cerebral artery occlusion (tMCAO) in adult male mice. Platelet depleting antibodies or isotype control were applied from day 3–28 after tMCAO in mice matched for infarct size. Long-term functional recovery was assessed over the course of 28 days by behavioural testing encompassing motor and sensorimotorical functions, as well as anxiety-like or spontaneous behaviour. Whole brain flow cytometry and light sheet fluorescent microscopy were used to identify resident and infiltrated immune cell types, and to determine the effects of platelet depletion on the cerebral vascular architecture, respectively.We found that delayed platelet depletion does not improve long-term functional outcome in the tMCAO stroke model. Immune cell abundance, the extent of thrombosis and the organisation of the cerebral vasculature were also comparable between platelet-depleted and control mice. Our study demonstrates that, despite their critical role in the acute stroke setting, platelets appear to contribute only marginally to tissue reorganisation and functional recovery at later stroke stages.

Infection is a major reason for poor stroke outcomes, and sepsis is a major cause of stroke-elated deaths. We herein examined whether NMDA receptor blockade, which was reported to exert anti-inflammatory actions, protects against the deleterious consequences of lipopolysaccharide (LPS)-induced sepsis-like state in adult male NMRI mice exposed to transient intraluminal middle cerebral artery occlusion (MCAO). At 24 h post-ischemia, vehicle or Escherichia coli LPS (2 or 4 mg/kg) was intraperitoneally administered, whereas 30 min later vehicle or ketamine (10 mg/kg), which is a non-competitive NMDA receptor antagonist, was intraperitoneally applied. Delivery of LPS at a dosage of 4 mg/kg induced a sepsis-like state characterized by a rectal temperature reduction by ∼4.0°C, increased neurological deficits in Clark score, cylinder and open-field tests, increased brain infarct volume and reduced neuronal survival in the previously ischemic tissue. Notably, additional treatment with ketamine (10 mg/kg) significantly attenuated the sepsis-associated rectal temperature reduction by ∼1.5°C, reduced neurological deficits, reduced infarct volume, and promoted neuronal survival. Ketamine alone did not influence infarct volume or neurological deficits. Real-time PCR data analysis showed that GFAP, CD86, CD206, IL-1β, and IL-10 mRNA levels were significantly increased in ischemic brains of LPS-treated compared with vehicle-treated mice. Additional treatment with ketamine significantly decreased IL-1β and IL-10, but not GFAP, CD86, and CD206 mRNA levels. Our data show that ketamine at a dose that on its own does not confer neuroprotection reverses the adverse effects of LPS-induced sepsis-like state post-ischemia, presumably via immunomodulatory actions.

Following ischemic stroke, polymorphonuclear neutrophils (PMNs) are rapidly recruited to the ischemic brain tissue and exacerbate stroke injury by release of reactive oxygen species (ROS), proteases and proinflammatory cytokines. PMNs may aggravate post-ischemic microvascular injury by obstruction of brain capillaries, contributing to reperfusion deficits in the stroke recovery phase. Thus, experimental studies which specifically depleted PMNs by delivery of anti-Ly6G antibodies or inhibited PMN brain entry, e.g., by CXC chemokine receptor 2 (CXCR2) or very late antigen-4 (VLA-4) blockade in the acute stroke phase consistently reduced neurological deficits and infarct volume. Although elevated PMN responses in peripheral blood are similarly predictive for large infarcts and poor stroke outcome in human stroke patients, randomized controlled clinical studies targeting PMN brain infiltration did not improve stroke outcome or even worsened outcome due to serious complications. More recent studies showed that PMNs have decisive roles in post-ischemic angiogenesis and brain remodeling, most likely by promoting extracellular matrix degradation, thereby amplifying recovery processes in the ischemic brain. In this minireview, recent findings regarding the roles of PMNs in ischemic brain injury and post-ischemic brain remodeling are summarized.