Intranasal Delivery of Mitochondria Attenuates Brain Injury by AMPK and SIRT1/PGC-1α Pathways in a Murine Model of Photothrombotic Stroke

Ischemic stroke is one of the major causes of morbidity and mortality worldwide. Mitochondria play a vital role in the pathological processes of cerebral ischemic injury, but its transplantation and underlying mechanisms remain unclear. In the present study, we examined the effects of mitochondrial therapy on the modulation of AMPK and SIRT1/PGC-1α signaling pathway, oxidative stress, and NLRP3 inflammasome activation after photothrombotic ischemic stroke (pt-MCAO). The adult male mice were subjected to the pt-MCAO in which the proximal-middle cerebral artery was exposed with a 532-nm laser beam for 4 min by retro-orbital injection of a photosensitive dye (Rose Bengal: 15 mg/kg) before the laser light exposure and isolated mitochondria (100 μg protein) were administered intranasally at 30 min, 24 h, and 48 h following post-stroke. After 72 h, mice were tested for neurobehavioral outcomes and euthanized for infarct volume, brain edema, and molecular analysis. First, we found that mitochondria therapy significantly decreased brain infarct volume and brain edema, improved neurological dysfunction, attenuated ischemic stroke-induced oxidative stress, and neuroinflammation. Second, mitochondria treatment inhibited NLRP3 inflammasome activation. Finally, mitochondria therapy accelerated p-AMPKα(Thr172) and PGC-1α expression and resorted SIRT1 protein expression levels in pt-MCAO mice. In conclusion, our results demonstrate that mitochondria therapy exerts neuroprotective effects by inhibiting oxidative damage and inflammation, mainly dependent on the heightening activation of the AMPK and SIRT1/PGC-1α signaling pathway. Thus, intranasal delivery of mitochondria might be considered a new therapeutic strategy for ischemic stroke treatment.

Genetic and Pharmacological Modulation of P75 Neurotrophin Receptor Attenuate Brain Damage After Ischemic Stroke in Mice

The precursor nerve growth factor (ProNGF) and its receptor p75 neurotrophin receptor (p75NTR) are upregulated in several brain diseases, including ischemic stroke. The activation of p75NTR is associated with neuronal apoptosis and inflammation. Thus, we hypothesized that p75NTR modulation attenuates brain damage and improves functional outcomes after ischemic stroke. Two sets of experiments were performed. (1) Adult wild-type (WT) C57BL/6 J mice were subjected to intraluminal suture-middle cerebral artery occlusion (MCAO) to induce cerebral ischemia. Pharmacological inhibitor of p75NTR, LM11A-31 (50 mg/kg), or normal saline was administered intraperitoneally (IP) 1 h post-MCAO, and animals survived for 24 h. (2) Adult p75NTR heterozygous knockout (p75NTR+/-) and WT were subjected to photothrombotic (pMCAO) to induce ischemic stroke, and the animals survived for 72 h. The sensory-motor function of animals was measured using Catwalk XT. The brain samples were collected to assess infarction volume, edema, hemorrhagic transformation, neuroinflammation, and signaling pathway at 24 and 72 h after the stroke. The findings described that pharmacological inhibition and genetic knocking down of p75NTR reduce infarction size, edema, and hemorrhagic transformation following ischemic stroke. Additionally, p75NTR modulation significantly decreased several anti-apoptosis markers and improved sensory motor function compared to the WT mice following ischemic stroke. Our observations exhibit that the involvement of p75NTR in ischemic stroke and modulation of p75NTR could improve the outcome of ischemic stroke by increasing cell survival and enhancing motor performance. LM11A-31 has the potential to be a promising therapeutic agent for ischemic stroke. However, more evidence is needed to illuminate the efficacy of LM11A-31 in ischemic stroke.

Lost in Translation: Neurotrophins Biology and Function in the Neurovascular Unit

The neurovascular unit (NVU) refers to the functional building unit of the brain and the retina, where neurons, glia, and microvasculature orchestrate to meet the demand of the retina's and brain's function. Neurotrophins (NTs) are structural families of secreted proteins and are known for exerting neurotrophic effects on neuronal differentiation, survival, neurite outgrowth, synaptic formation, and plasticity. NTs include several molecules, such as nerve growth factor, brain-derived neurotrophic factor, NT-3, NT-4, and their precursors. Furthermore, NTs are involved in signaling pathways such as inflammation, apoptosis, and angiogenesis in a nonneuronal cell type. Interestingly, NTs and the precursors can bind and activate the p75 neurotrophin receptor (p75NTR) at low and high affinity. Mature NTs bind their cognate tropomyosin/tyrosine-regulated kinase receptors, crucial for maintenance and neuronal development in the brain and retina axis. Activation of p75NTR results in neuronal apoptosis and cell death, while tropomysin receptor kinase upregulation contributes to differentiation and cell growth. Recent findings indicate that modulation of NTs and their receptors contribute to neurovascular dysfunction in the NVU. Several chronic metabolic and acute ischemic diseases affect the NVU, including diabetic and ischemic retinopathy for the retina, as well as stroke, acute encephalitis, and traumatic brain injury for the brain. This work aims to review the current evidence through published literature studying the impact of NTs and their receptors, including the p75NTR receptor, on the injured and healthy brain-retina axis.

A modified murine photothrombotic stroke model: a minimally invasive and reproducible cortical and sub-cortical infarct volume and long-term deficits

Ischemic stroke is one of the major causes of devastating neurological disabilities and mortality worldwide. Despite extensive research for treatment approaches, there remains limited therapy in the stroke field. Therefore, more research is required for reproducibility to understand stroke pathology in pre-clinical studies. In the current modified method, mice were subjected to photothrombotic stroke (pt-MCA; proximal-middle cerebral artery was exposed with a 532 nm laser beam for 4 min) by retro-orbital injection of photosensitive dye, Rose Bengal (15 mg/kg) before the laser light exposure. Sensorimotor deficits were assessed by rotarod and catwalk test at 72 h following post-pt-MCAO, and brain samples were collected for infarct volume and hemorrhagic transformation (HT) assessments. Cognitive impairments were assessed by a novel objective recognition and Morris's water maze tests at the end of the follow-up. pt-MCAO animals significantly reduced body weight and impaired motor and cognitive functions. Furthermore, pt-MCAO animals showed apparent infarction, brain edema, and increased HT compared to the sham animals. Additionally, this method enables concurrent measurement of short-term and long-term neurological dysfunction with relatively larger cortical and sub-cortical infarct volume following pt-MCAO. With respect to the other models, this modified model offers enhanced reproducibility regarding infarct volume and cognitive/functional outcomes and avoids complications associated with critical surgeries and craniotomy. In conclusion, this modified model helps to understand stroke pathogenesis and minimize the animals' numbers which help to increase the scientific and statistical potential in pre-clinical studies.

Transplantation of Exercise-Induced Extracellular Vesicles as a Promising Therapeutic Approach in Ischemic Stroke

Clinical evidence affirms physical exercise is effective in preventive and rehabilitation approaches for ischemic stroke. This sustainable efficacy is independent of cardiovascular risk factors and associates substantial reprogramming in circulating extracellular vesicles (EVs). The intricate journey of pluripotent exercise-induced EVs from parental cells to the whole-body and infiltration to cerebrovascular entity offers several mechanisms to reduce stroke incidence and injury or accelerate the subsequent recovery. This review delineates the potential roles of EVs as prospective effectors of exercise. The candidate miRNA and peptide cargo of exercise-induced EVs with both atheroprotective and neuroprotective characteristics are discussed, along with their presumed targets and pathway interactions. The existing literature provides solid ground to hypothesize that the rich vesicles link exercise to stroke prevention and rehabilitation. However, there are several open questions about the exercise stressors which may optimally regulate EVs kinetic and boost brain mitochondrial adaptations. This review represents a novel perspective on achieving brain fitness against stroke through transplantation of multi-potential EVs generated by multi-parental cells, which is exceptionally reachable in an exercising body.

Abstract TMP114: Modulation Of P75ntr Improves Neuroprotection Following Ischemic Stroke

Background: Stroke is a serious cause of mortality in the United States. Tissue plasminogen activator (tPA) is the only effective drug. However, it increases the risk of cerebral hemorrhage due to its narrow therapeutic window. Previous studies have shown the role of neurotrophins in several brain diseases. P75 NTR which is the receptor of tumor necrosis family is highly expressed in stroke and associated with neuronal apoptosis. Downregulation of p75 NTR attenuates brain injury. This study aims to find the role of p75 NTR in the outcome of stroke.

Methods: Two different sets of experiments were performed. 1. Young adult C57BL/6 mice were subjected to ischemic stroke using intraluminal suture model. P75 NTR modulator (LM11A-31) was administered following stroke. Brain samples were collected 24 hours after injury. 2. Young adult C57BL/6 and p75 heterozygous mice were subjected to stroke using Rose Bengal photothrombotic method. Mice were tested for neurobehavioral analysis and samples were collected 72h after stroke.

Results: We found that administration of LM11A-31 significantly reduced infarction volume, edema, and hemorrhagic transformation 24h after stroke in mice. Also, LM11A-31 reduced several inflammatory markers including tumor necrosis factor- alpha (TNF-α), nuclear factor kappa-light-chain (p-NFκb/t-NFκb), and c- Jun N-terminal kinases (p-JNK/t-JNK), and significantly increased the expression of several anti-inflammatory signaling, including protein kinase B (p-Akt/t-Akt) and extracellular signal-regulated kinase ½ (p-ERK1/2/t-ERK1/2) after stroke. Furthermore, we found that p75 NTR heterozygous mice remarkably demonstrated less infarction, edema, and hemorrhagic transformation than wild-type mice after stroke. Moreover, p75 NTR heterozygous significantly showed better motor function.

Conclusion: This study suggests that p75 NTR modulation can be a potential pharmacological target for improving the outcome of ischemic stroke.

Abstract WP234: Mitochondria Therapy Mitigates Neuroinflammation And Provides Neuroprotection Against Ischemic Stroke In Mice

Background: Ischemic stroke is the second prevalent life-threat problem associated with long-lasting neurological disabilities and a high mortality rate worldwide. Despite this, therapeutic options remain limited. Recently, mitochondria transplantation therapy has emerged as a potential approach for increasing brain protection. This study aimed to investigate the protective role of mitochondria transplantation against ischemic stroke-induced behavioral deficits and molecular alterations in a photothrombotic stroke model.

Methods: Ischemic stroke was induced by a Rose Bengal photothrombosis method in young adult C57BL/6 mice. Repeated doses of isolated liver mitochondria (100μg/mouse) were administrated intranasally at 1 h, 3 h, 24 h, and 48 h post-stroke. After 72 h, mice were tested for behavioral outcomes and euthanized, and tissues were harvested to measure infarct volume, brain edema, and molecular analysis.

Results: Mitochondria-treated mice showed a significant improvement in behavioral outcomes, reduction in infarct size, and brain edema compared to the vehicle-treated group. Additionally, mitochondria significantly inhibited the protein expression of NOD-like receptor protein-3, phospho-nuclear factor kappa-B, cleaved-interleukin-1β, apoptosis-associated speck-like protein, glial fibrillary acidic protein, and ionized calcium-binding adapter molecule-1 proteins. Furthermore, mitochondria treatment showed a lower expression of nitrotyrosine, and 4-hydroxynonenal and higher expression of endothelial nitric oxide synthase and sulfotransferase-4A1 proteins, oxidative stress markers ( Table 1 ).

Conclusion: Taken together, these data indicate that mitochondria reveal neuroprotection through the attenuation of inflammation against stroke. Further investigations into the role of neuroprotection of mitochondria transplantation are needed to determine whether it can be an effective therapy for stroke patients.

Protective Role of Short-Chain Fatty Acids against Ang- II-Induced Mitochondrial Dysfunction in Brain Endothelial Cells: A Potential Role of Heme Oxygenase 2

OBJECTIVES

Short-chain fatty acids (SCFAs), the main metabolites released from the gut microbiota, are altered during hypertension and obesity. SCFAs play a beneficial role in the cardiovascular system. However, the effect of SCFAs on cerebrovascular endothelial cells is yet to be uncovered. In this study, we use brain endothelial cells to investigate the in vitro effect of SCFAs on heme oxygenase 2 (HO-2) and mitochondrial function after angiotensin II (Ang-II) treatment.

METHODS

Brain human microvascular endothelial cells were treated with Ang-II (500 nM for 24 h) in the presence and absence of an SCFAs cocktail (1 μM; acetate, propionate, and butyrate) and/or HO-2 inhibitor (SnPP 5 μM). At the end of the treatment, HO-2, endothelial markers (p-eNOS and NO production), inflammatory markers (TNFα, NFκB-p50, and -p65), calcium homeostasis, mitochondrial membrane potential, mitochondrial ROS and H2O2, and mitochondrial respiration were determined in all groups of treated cells.

KEY RESULTS

Our data showed that SCFAs rescued HO-2 after Ang-II treatment. Additionally, SCFAs rescued Ang-II-induced eNOS reduction and mitochondrial membrane potential impairment and mitochondrial respiration damage. On the other hand, SCFAs reduced Ang-II-induced inflammation, calcium dysregulation, mitochondrial ROS, and H2O2. All of the beneficial effects of SCFAs on endothelial cells and mitochondrial function occurred through HO-2.

CONCLUSIONS

SCFAs treatment restored endothelial cells and mitochondrial function following Ang-II-induced oxidative stress. SCFAs exert these beneficial effects by acting on HO-2. Our results are opening the door for more studies to investigate the effect the of SCFAs/HO-2 axis on hypertension and obesity-induced cerebrovascular diseases.

Pro-survival Phenotype of HIF-1α: Neuroprotection Through Inflammatory Mechanisms

Hypoxia-inducible factor 1 (HIF-1) is a major player in the oxygen sensor system as well as a transcription factor. HIF-1 is also associated in the pathogenesis of many brain diseases including Alzheimer's disease (AD), epilepsy and stroke. HIF-1 regulates the expression of many genes such as those involved in glycolysis, erythropoiesis, angiogenesis and proliferation in hypoxic condition. Despite several studies, the mechanism through which HIF-1 confers neuroprotection remains unclear, one of them is modulating metabolic profiles and inflammatory pathways. Characterization of the neuroprotective role of HIF-1 may be through its stabilization and the regulation of target genes that aid in the early adaptation to the oxidative stressors. It is interesting to note that mounting data from recent years point to an additional crucial regulatory role for hypoxia-inducible factors (HIFs) in inflammation. HIFs in immune cells regulate the production of glycolytic energy as well as innate immunity, pro-inflammatory gene expression, and mediates activation of pro-survival pathways. The present review highlights the contribution of HIF-1 to neuroprotection where inflammation is the crucial factor in the pathogenesis contributing to neural death. The potential mechanisms that contribute to neuroprotection as a result of the downstream targets of HIF-1α are discussed. Such mechanisms include those mediated through IL-10, an anti-inflammatory molecule involved in activating pro-survival signaling mechanisms via AKT/ERK and JAK/STAT pathways.

Intra-arterial verapamil improves functional outcomes of thrombectomy in a preclinical model of extended hyperglycemic stroke

The abrupt hyperglycemic reperfusion following thrombectomy has been shown to harm the efficacy of the intervention in stroke patients with large vessel occlusion. Studies of ours and others have shown thioredoxin-interacting protein (TXNIP) is critically involved in hyperglycemic stroke injury. We recently found verapamil ameliorates cerebrovascular toxicity of tissue plasminogen activators in hyperglycemic stroke. The present study aims to answer if verapamil exerts direct neuroprotective effects and alleviates glucose toxicity following thrombectomy in a preclinical model of hyperglycemic stroke. Primary cortical neural (PCN) cultures were exposed to hyperglycemic reperfusion following oxygen-glucose deprivation (OGD), with or without verapamil treatment. In a mouse model of intraluminal stroke, animals were subjected to 4 h middle cerebral artery occlusion (MCAO) and intravenous glucose infusion. Glucose infusion lasted one more hour at reperfusion, along with intra-arterial (i.a.) verapamil infusion. Animals were subjected to sensorimotor function tests and histological analysis of microglial phenotype at 72 h post-stroke. According to our findings, glucose concentrations (2.5-20 mM) directly correlated with TXNIP expression in OGD-exposed PCN cultures. Verapamil (100 nM) effectively improved PCN cell neurite growth and reduced TXNIP expression as well as interaction with NOD-like receptor pyrin domain-containing-3 (NLRP3) inflammasome, as determined by immunoblotting and immunoprecipitation. In our mouse model of extended hyperglycemic MCAO, i.a. verapamil (0.5 mg/kg) could attenuate neurological deficits induced by hyperglycemic stroke. This was associated with reduced microglial pro-inflammatory transition. This finding encourages pertinent studies in hyperglycemic patients undergoing thrombectomy where the robust reperfusion may exacerbate glucose toxicity.

Verapamil inhibits TXNIP-NLRP3 inflammasome activation and preserves functional recovery after intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH) is the second most common type of stroke with no satisfactory treatment. Recent studies from our group and others indicated a potential positive effect of verapamil, a commonly prescribed calcium channel blocker, with thioredoxin-interacting protein (TXNIP) inhibitor properties, in ischemic stroke and cognitive disorders. It is unclear whether there would be a beneficial effect of verapamil administration in ICH. Therefore, this study was designed to determine the neuroprotective effects of verapamil in a murine ICH model. ICH was induced by stereotactic injection of collagenase type VII (0.075 U) into the right striatum of adult male C57BL/6 mice. Verapamil (0.15 mg/kg) or saline was administered intravenously at 1 h post-ICH followed by oral (1 mg/kg/d) administration in drinking water for 28 days. Motor and cognitive function were assessed using established tests for motor coordination, spatial learning, short- and long-term memory. A subset of animals was sacrificed at 72 h after ICH for molecular analysis. Verapamil treatment reduced expression of TXNIP and NOD-like receptor pyrin domain-containing-3 inflammasome activation in the perihematomal area. These protective effects of verapamil were associated with decreased proinflammatory mediators, microglial activation, and blood-brain barrier permeability markers and paralleled less phosphorylated nuclear factor kappa B level. Our findings also demonstrate that long-term low-dose verapamil effectively attenuated motor and cognitive impairments. Taken together, these data indicate that verapamil has therapeutic potential in improving acute motor function after ICH. Further investigations are needed to confirm whether verapamil treatment could be a promising candidate for clinical trials.

Contralesional angiotensin type 2 receptor activation contributes to recovery in experimental stroke

We and others have previously shown that angiotensin II receptor type 2 receptor (AT2R) is upregulated in the contralesional hemisphere after stroke in normoglycemic Wistar rats. In this study, we examined the expression of AT2R in type 2 diabetic Goto-Kakizaki (GK) rats and control Wistars after stroke. We also tested the contribution of the contralesional AT2R in recovery after stroke through a specific knockdown of the AT2R in this hemisphere only. Two experiments were conducted. In the first experiment, GK rats were subjected to middle cerebral artery occlusion (MCAO) and treated with the angiotensin II receptor type 1 receptor (AT1R) blocker candesartan or saline at reperfusion. Stroke outcomes, as well as AT2R expression, were examined and compared to control Wistars at 24 h. In the second experiment, localized AT2R knockdown was achieved through intrastriatal injection of short hairpin RNA (shRNA) lentiviral particles or non-targeting control into the left-brain hemisphere of Wistar rats. After 14 days, rats were subjected to right MCAO and treated with the AT2R agonist, Compound 21 (C21), or saline for 7 days. Behavioral outcomes were assessed for up to 10 days. In the first experiment, stroke reduced the expression of AT2R in GK rats. Candesartan treatment failed to improve the neurobehavioral outcomes, preserve vascular integrity or reduce oxidative/nitrative stress or apoptotic markers at 24 h post stroke in these animals. In the second experiment, contralesional AT2R knockdown reduced the C21-mediated functional recovery after stroke. In conclusion, contralesional AT2R upregulation after stroke is blunted in diabetic rats which show reduced sensitivity to post-stroke candesartan treatment. Contralesional AT2R could be involved in C21-mediated functional recovery after stroke.

Direct AT2R Stimulation Slows Post-stroke Cognitive Decline in the 5XFAD Alzheimer's Disease Mice

Alzheimer's disease (AD), currently the single leading cause of death still on the rise, almost always coexists alongside vascular cognitive impairment (VCI). In fact, the ischemic disease affects up to 90% of AD patients, with strokes and major infarctions representing over a third of vascular lesions. Studies also confirmed that amyloid plaques, typical of AD, are much more likely to cause dementia if strokes or cerebrovascular damage also exist, leading to the term "mixed pathology" cognitive impairment. Although its incidence is expected to grow, there are no satisfactory treatments. There is hence an urgent need for safe and effective therapies that preserve cognition, maintain function, and prevent the clinical deterioration that results from the progression of this irreversible, neurodegenerative disease. To our knowledge, this is the first study to investigate the effects of long-term treatment with C21, a novel angiotensin II type 2 receptor (AT2R) agonist, on the development of "mixed pathology" cognitive impairment. This was accomplished using a unique model that employs the fundamental elements of both AD and VCI. Treatment with C21/vehicle was started 1 h post-stroke and continued for 5 weeks in mice with concurrent AD pathology. Efficacy was established through a series of functional tests assessing various aspects of cognition, including spatial learning, short-term/working memory, long-term/reference memory, and cognitive flexibility, in addition to the molecular markers characteristic of AD. Our findings demonstrate that C21 treatment preserves cognitive function, maintains cerebral blood flow, and reduces Aβ accumulation and toxic tau phosphorylation in AD animals post-stroke.

Candesartan Effectively Preserves Cognition in Senescence Accelerated Mouse Prone 8 (SAMP8) mice

Background:

Alzheimer’s disease (AD) has become a worldwide crisis with no effective therapeutic options. The medications currently available for AD are only palliative; their effect is temporary, and they are associated with unfavorable side effects. Even the newest medication aducanumab, granted accelerated FDA approval in 2021, failed to show cognitive benefits in clinical trials and continued approval requires verification in subsequent clinical trials. There is an urgent need for safe and effective therapies to preserve cognition and effectively manage AD. Generally, a new drug product takes several years for FDA approval and exceeds 2.5 billion dollars in research and development, with most new drug products never even reaching the market. This has led to a recent shift for repurposing/repositioning existing FDA-approved medications, to new therapeutic indications.

Objective:

To investigate the effects of long-term treatment with candesartan, an FDA-approved angiotensin-II type-1 receptor blocker (ARB), on the development of cognitive impairment associated with premature aging.

Methods:

Candesartan was given at a dose of 1 mg/kg/d in an AD model of senescence-accelerated mouse prone-8 (SAMP8) and senescence-accelerated mouse resistant (SAMR1) mice. Oral treatment with candesartan or vehicle was started, in 2-month-old mice and administered continuously for 4-months.

Results:

Low-dose candesartan prevented the development of cognitive impairment, otherwise associated with accelerated aging, in SAMP8 mice, by reducing inflammation and nitro-oxidative stress. Candesartan did not affect the cognitive function of control SAMR1 mice.

Conclusion:

Early ARB treatment might be beneficial in preventing age-related cognitive deficits in AD-prone individuals.

Diabetes Mellitus during the Pandemic Covid-19: Prevalence, Pathophysiology, Mechanism, and Management: An updated overview

BACKGROUND

Diabetes mellitus (DM) is among the most frequently reported comorbidities in patients tainted with the pandemic coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). With a high pervasiveness of diabetes mellitus, there is an urgency to understand the special aspects of COVID-19 in hyperglycemic patients. Diabetic patients are at higher risk than the general population of viral or bacterial infections, thus require special attention since diabetes is linked with severe, critical, and lethal modes of COVID-19.

OBJECTIVE

The objective of this study was to focus on epidemiology, pathophysiology, mechanism, and management of DM with COVID-19.

METHODS

The search was carried out on databases portals such as Pubmed, EMBASE, Google Scholar, and CINAHL with the keywords, i.e., COVID-19, coronavirus, SARS-CoV-2, diabetes, covid-19, etc. Result: DM and COVID-19 disease conditions can impact each other in terms of clinical progression and outcome. Available laboratory/clinical observations suggest that hyperglycemia-induced immune dysfunction, inflated lactate grades, and cytokines storm may play critical roles in the seriousness of COVID-19 in patients with diabetes; however, the exact mechanisms linking diabetes and COVID-19 remain to be further clarified.

CONCLUSION

Standards to constrain the disease spread at the individual and community level are the key to extenuate the speedily rising pandemic, while definitive treatment, like plasma therapy, chemoprophylaxis, or vaccine for COVID-19, has yet to be discovered.

Thioredoxin interacting protein, a key molecular switch between oxidative stress and sterile inflammation in cellular response

Tissue and systemic inflammation have been the main culprit behind the cellular response to multiple insults and maintaining homeostasis. Obesity is an independent disease state that has been reported as a common risk factor for multiple metabolic and microvascular diseases including nonalcoholic fatty liver disease (NAFLD), retinopathy, critical limb ischemia, and impaired angiogenesis. Sterile inflammation driven by high-fat diet, increased formation of reactive oxygen species, alteration of intracellular calcium level and associated release of inflammatory mediators, are the main common underlying forces in the pathophysiology of NAFLD, ischemic retinopathy, stroke, and aging brain. This work aims to examine the contribution of the pro-oxidative and pro-inflammatory thioredoxin interacting protein (TXNIP) to the expression and activation of NLRP3-inflammasome resulting in initiation or exacerbation of sterile inflammation in these disease states. Finally, the potential for TXNIP as a therapeutic target and whether TXNIP expression can be modulated using natural antioxidants or repurposing other drugs will be discussed.

Renin-Angiotensin System Alterations in the Human Alzheimer's Disease Brain

BACKGROUND

Understanding Alzheimer's disease (AD) in terms of its various pathophysiological pathways is essential to unravel the complex nature of the disease process and identify potential therapeutic targets. The renin-angiotensin system (RAS) has been implicated in several brain diseases, including traumatic brain injury, ischemic stroke, and AD.

OBJECTIVE

This study was designed to evaluate the protein expression levels of RAS components in postmortem cortical and hippocampal brain samples obtained from AD versus non-AD individuals.

METHODS

We analyzed RAS components in the cortex and hippocampus of postmortem human brain samples by western blotting and immunohistochemical techniques in comparison with age-matched non-demented controls.

RESULTS

The expression of AT1R increased in the hippocampus, whereas AT2R expression remained almost unchanged in the cortical and hippocampal regions of AD compared to non-AD brains. The Mas receptor was downregulated in the hippocampus. We also detected slight reductions in ACE-1 protein levels in both the cortex and hippocampus of AD brains, with minor elevations in ACE-2 in the cortex. We did not find remarkable differences in the protein levels of angiotensinogen and Ang II in either the cortex or hippocampus of AD brains, whereas we observed a considerable increase in the expression of brain-derived neurotrophic factor in the hippocampus.

CONCLUSION

The current findings support the significant contribution of RAS components in AD pathogenesis, further suggesting that strategies focusing on the AT1R and AT2R pathways may lead to novel therapies for the management of AD.

Endothelial Thioredoxin-Interacting Protein Depletion Reduces Hemorrhagic Transformation in Hyperglycemic Mice after Embolic Stroke and Thrombolytic Therapy

We hypothesize that endothelial-specific thioredoxin-interacting protein knock-out (EC-TXNIP KO) mice will be more resistant to the neurovascular damage (hemorrhagic-transformation-HT) associated with hyperglycemia (HG) in embolic stroke. Adult-male EC-TXNIP KO and wild-type (WT) littermate mice were injected with-streptozotocin (40 mg/kg, i.p.) for five consecutive days to induce diabetes. Four-weeks after confirming HG, mice were subjected to embolic middle cerebral artery occlusion (eMCAO) followed by tissue plasminogen activator (tPA)-reperfusion (10 mg/kg at 3 h post-eMCAO). After the neurological assessment, animals were sacrificed at 24 h for neurovascular stroke outcomes. There were no differences in cerebrovascular anatomy between the strains. Infarct size, edema, and HT as indicated by hemoglobin (Hb)-the content was significantly higher in HG-WT mice, with or without tPA-reperfusion, compared to normoglycemic WT mice. Hyperglycemic EC-TXNIP KO mice treated with tPA tended to show lower Hb-content, edema, infarct area, and less hemorrhagic score compared to WT hyperglycemic mice. EC-TXNIP KO mice showed decreased expression of inflammatory mediators, apoptosis-associated proteins, and nitrotyrosine levels. Further, vascular endothelial growth factor-A and matrix-metalloproteinases (MMP-9/MMP-3), which degrade junction proteins and increase blood-brain-barrier permeability, were decreased in EC-TXNIP KO mice. Together, these findings suggest that vascular-TXNIP could be a novel therapeutic target for neurovascular damage after stroke.

Compound 21, a Direct AT2R Agonist, Induces IL-10 and Inhibits Inflammation in Mice Following Traumatic Brain Injury

Recent studies demonstrated that the angiotensin type 2 receptor (AT2R) agonist, compound 21 (C21), provides neuroprotection and enhances recovery in experimental stroke. However, C21 has never been tested in traumatic brain injury (TBI). Here, we aim to examine whether C21 confers protection after TBI. Unilateral cortical impact injury was induced in young adult C57BL/6 mice. C21 (0.03 mg/kg, i.p.) was administered at 1 h and 3 h post-TBI. After neurological severity score (NSS) assessments, all animals were sacrificed for immunoblotting analysis at 24 h post-TBI. C21 treatment significantly ameliorated NSS and reduced TBI's biomarkers [high mobility group box 1 (HMGB1), aquaporin-4 (AQ4)] and inflammatory markers [interlukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α)] in the pericontusional areas compared to saline TBI. Further, C21 treatment induced interleukin-10 (IL-10) and phosphorylation of endothelial nitric oxide synthase (eNOS) after TBI. C21 also attenuated pro-apoptotic activation of poly (ADP-ribose) polymerase (PARP) and caspase-3. These findings support the therapeutic potential of C21 against TBI.

Manifestation of renin angiotensin system modulation in traumatic brain injury

Traumatic brain injury (TBI) alters brain function and is a crucial public health concern worldwide. TBI triggers the release of inflammatory mediators (cytokines) that aggravate cerebral damage, thereby affecting clinical prognosis. The renin angiotensin system (RAS) plays a critical role in TBI pathophysiology. RAS is widely expressed in many organs including the brain. Modulation of the RAS in the brain via angiotensin type 1 (AT₁) and type 2 (AT₂) receptor signaling affects many pathophysiological processes, including TBI. AT₁R is highly expressed in neurons and astrocytes. The upregulation of AT₁R mediates the effects of angiotensin II (ANG II) including release of proinflammatory cytokines, cell death, oxidative stress, and vasoconstriction. The AT₂R, mainly expressed in the fetal brain during development, is also related to cognitive function. Activation of this receptor pathway decreases neuroinflammation and oxidative stress and improves overall cell survival. Numerous studies have illustrated the therapeutic potential of inhibiting AT₁R and activating AT₂R for treatment of TBI with variable outcomes. In this review, we summarize studies that describe the role of brain RAS signaling, through AT₁R and AT₂R in TBI, and its modulation with pharmacological approaches.

Verapamil Prevents Development of Cognitive Impairment in an Aged Mouse Model of Sporadic Alzheimer's Disease

Currently, dementia is the only leading cause of death that is still on the rise, with total costs already exceeding those of cancer and heart disease and projected to increase even further in the coming years. Unfortunately, there are no satisfactory treatments and attempts to develop novel, more effective treatments have been extremely costly, albeit unsuccessful thus far. This has led us to investigate the use of established drugs, licensed for other therapeutic indications, for their potential application in cognitive disorders. This strategy, referred to as "drug repositioning," has been successful in many other areas including cancer and cardiovascular diseases. To our knowledge, this is the first study to investigate the effects of long-term treatment with verapamil, a calcium channel blocker commonly prescribed for various cardiovascular conditions and recently applied for prevention of cluster headaches, on the development of cognitive impairment in aged animals. Verapamil was studied at a low dose (1mg/kg/d) in a mouse model of sporadic Alzheimer's disease (sAD). Oral treatment with verapamil or vehicle was started, 24 h post-intracerebroventricular (ICV) streptozotocin/(STZ), in 12-month-old animals and continued for 3 months. Cognitive function was assessed using established tests for spatial learning, short-term/working memory, and long-term/reference memory. Our findings demonstrate that long-term low-dose verapamil effectively prevents development of ICV/STZ-induced cognitive impairment. It mitigates the astrogliosis and synaptic toxicity otherwise induced by ICV/STZ in the hippocampus of aged animals. These findings indicate that long-term, low-dose verapamil may delay progression of sAD in susceptible subjects of advanced age.

ER stress associated TXNIP-NLRP3 inflammasome activation in hippocampus of human Alzheimer's disease

Although the exact etiology of Alzheimer's disease (AD) is poorly understood, experimental and clinical evidences suggest the contribution of neuroinflammation in the pathogenesis of AD. Pathologically, AD brain is characterized by an imbalance in redox status, elevated endoplasmic reticulum (ER) stress, synaptic dysfunction, inflammation, and progressive neurodegeneration. It has been noted that continuous accumulation of amyloid-beta (Aβ) and intracellular neurofibrillary tangles (NFTs) in AD brain trigger ER stress, which contributes to neurodegeneration. Similarly, experimental evidences supports the hypothesis that thioredoxin-interacting protein (TXNIP), an endogenous regulator of redox regulator thioredoxin (TRX), is activated by ER stress and contributes to activation of NLRP3 (NOD-like receptor protein 3) inflammatory cascade in hippocampus of the AD brain. Hippocampus of postmortem human AD and aged matched non-AD controls were analyzed for the expression ER stress markers and TXNIP-NLRP3 inflammasome at cellular and molecular levels. We found higher expression of TXNIP at protein and transcript levels in close association with pathological markers of AD such as Aβ and NFTs in AD hippocampus. In addition, our results demonstrated that TXNIP was co-localized in neurons and microglia. Moreover, expression of binding immunoglobulin protein (BiP), activated eukaryotic initiation factor-2α (eIf2α) and C/EBP homology protein (CHOP), proteins involved the development of ER stress, were elevated in AD hippocampus. Further, elevated expression of effector molecules of NLRP3 inflammasome activation such as apoptosis associated speck-like protein (ASC), cleaved caspase-1 and cleaved interleukin-1β were observed in the AD hippocampus. The study suggests that TXNIP could be a link that connect ER stress with neuroinflammation. Thus, TXNIP can be a possible therapeutic target to mitigate the progression of neuroinflammation in the pathogenesis of AD.

Thioredoxin interacting protein regulates age-associated neuroinflammation

Immune system hypersensitivity is believed to contribute to mental frailty in the elderly. Solid evidence indicates NOD-like receptor pyrin domain containing-3 (NLRP3)-inflammasome activation intimately connects aging-associated chronic inflammation (inflammaging) to senile cognitive decline. Thioredoxin interacting protein (TXNIP), an inducible protein involved in oxidative stress, is essential for NLRP3 inflammasome activity. This study aims to find whether TXNIP/NLRP3 inflammasome pathway is involved in senile dementia. According to our studies on sex-matched mice, TXNIP was significantly upregulated in aged animals, paralleled by the NLRP3-inflammasome over-activity leading to enhanced caspase-1 cleavage and IL-1β maturation, in both sexes. This was closely associated with depletion of the anti-aging and cognition enhancing protein klotho, in aged males. Txnip knockout reversed age-related NLRP3-hyperactivity and enhanced thioredoxin (TRX) levels. Further, TXNIP inhibition along with verapamil replicated TXNIP/NLRP3-inflammasome downregulation in aged animals, with FOXO-1 and mTOR upregulation. These alterations concurred with substantial improvements in both cognitive and sensorimotor abilities. Together, these findings substantiate the pivotal role of TXNIP to drive inflammaging in parallel with klotho depletion and functional decline, and delineate thioredoxin system as a potential target to decelerate senile dementia.

Verapamil as an Adjunct Therapy to Reduce tPA Toxicity in Hyperglycemic Stroke: Implication of TXNIP/NLRP3 Inflammasome

Thrombolytic therapy has remained quite challenging in hyperglycemic patients for its association with poor prognosis and increased hemorrhagic conversions. We recently showed that tissue plasminogen activator (tPA)-induced cerebrovascular damage is associated with thioredoxin-interacting protein (TXNIP) upregulation, which has an established role in the detrimental effects of hyperglycemia. In the present work, we investigated whether verapamil, an established TXNIP inhibitor, may provide protection against hyperglycemic stroke and tPA-induced blood-brain barrier (BBB) disruption. Acute hyperglycemia was induced by intraperitoneal administration of 20% glucose, 15 min prior to transient middle cerebral artery occlusion (tMCAO). Verapamil (0.15 mg/kg) or saline was intravenously infused with tPA at hyperglycemic reperfusion, 1 h post tMCAO. After 24 h of ischemia/reperfusion (I/R), mice were assessed for neurobehavioral deficits followed by sacrifice and evaluation of brain infarct volume, edema, and microbleeding. Alterations in TXNIP, inflammatory mediators, and BBB markers were further analyzed using immunoblotting or immunostaining techniques. As adjunctive therapy, verapamil significantly reduced tPA-induced BBB leakage, matrix metalloproteinase 9 (MMP-9) upregulation, and tight junction protein deregulation, which resulted in lesser hemorrhagic conversions. Importantly, verapamil strongly reversed tPA-induced TXNIP/NLRP3 (NOD-like receptor pyrin domain-containing-3) inflammasome activation and reduced infarct volume. This concurred with a remarkable decrease in high-mobility group box protein 1 (HMGB-1) and nuclear factor kappa B (NF-κB) stimulation, leading to less priming of NLRP3 inflammasome. This preclinical study supports verapamil as a safe adjuvant that may complement thrombolytic therapy by inhibiting TXNIP's detrimental role in hyperglycemic stroke.

The NLRP3 inflammasome: a potential therapeutic target for traumatic brain injury

Although the precise mechanisms contributing to secondary brain injury following traumatic brain injury are complex and obscure, a number of studies have demonstrated that inflammatory responses are an obvious and early feature in the pathogenesis of traumatic brain injury. Inflammasomes are multiprotein complexes that prompt the stimulation of caspase-1 and subsequently induce the maturation and secretion of proinflammatory cytokines, such as interleukin-1β and interleukin-18. These cytokines play a pivotal role in facilitating innate immune responses and inflammation. Among various inflammasome complexes, the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is the best characterized, a crucial role for NLRP3 has been demonstrated in various brain diseases, including traumatic brain injury. Several recent studies have revealed the contribution of NLRP3 inflammasome in identifying cellular damage and stimulating inflammatory responses to aseptic tissue injury after traumatic brain injury. Even more important, blocking or inhibiting the activation of the NLRP3 inflammasome may have substantial potential to salvage tissue damage during traumatic brain injury. In this review, we summarize recently described mechanisms that are involved in the activation and regulation of the NLRP3 inflammasome. Moreover, we review the recent investigations on the contribution of the NLRP3 inflammasome in the pathophysiology of TBI, and current advances and challenges in potential NLRP3-targeted therapies. A significant contribution of NLRP3 inflammasome activation to traumatic brain injury implies that therapeutic approaches focused on targeting specific inflammasome components could significantly improve the traumatic brain injury outcomes.

The Brain AT2R-a Potential Target for Therapy in Alzheimer's Disease and Vascular Cognitive Impairment: a Comprehensive Review of Clinical and Experimental Therapeutics

Dementia is a potentially avertable tragedy, currently considered among the top 10 greatest global health challenges of the twenty-first century. Dementia not only robs individuals of their dignity and independence, it also has a ripple effect that starts with the inflicted individual's family and projects to the society as a whole. The constantly growing number of cases, along with the lack of effective treatments and socioeconomic impact, poses a serious threat to the sustainability of our health care system. Hence, there is a worldwide effort to identify new targets for the treatment of Alzheimer's disease (AD), the leading cause of dementia. Due to its multifactorial etiology and the recent clinical failure of several novel amyloid-β (Aβ) targeting therapies, a comprehensive "multitarget" approach may be most appropriate for managing this condition. Interestingly, renin angiotensin system (RAS) modulators were shown to positively impact all the factors involved in the pathophysiology of dementia including vascular dysfunction, Aβ accumulation, and associated cholinergic deficiency, in addition to tau hyperphosphorylation and insulin derangements. Furthermore, for many of these drugs, the preclinical evidence is also supported by epidemiological data and/or preliminary clinical trials. The purpose of this review is to provide a comprehensive update on the major causes of dementia including the risk factors, current diagnostic criteria, pathophysiology, and contemporary treatment strategies. Moreover, we highlight the angiotensin II receptor type 2 (AT2R) as an effective drug target and present ample evidence supporting its potential role and clinical applications in cognitive impairment to encourage further investigation in the clinical setting.

Tissue Plasminogen Activator Promotes TXNIP-NLRP3 Inflammasome Activation after Hyperglycemic Stroke in Mice

Hyperglycemia has been shown to counterbalance the beneficial effects of tissue plasminogen activator (tPA) and increase the risk of intracerebral hemorrhage in ischemic stroke. Thioredoxin interacting protein (TXNIP) mediates hyperglycemia-induced oxidative damage and inflammation in the brain and reduces cerebral glucose uptake/utilization. We have recently reported that TXNIP-induced NLRP3 (NOD-like receptor pyrin domain-containing-3) inflammasome activation contributes to neuronal damage after ischemic stroke. Here, we tested the hypothesis that tPA induces TXNIP-NLRP3 inflammasome activation after ischemic stroke, in hyperglycemic mice. Acute hyperglycemia was induced in mice by intraperitoneal (IP) administration of a 20% glucose solution. This was followed by transient middle cerebral artery occlusion (t-MCAO), with or without intravenous (IV) tPA administered at reperfusion. The IV-tPA exacerbated hyperglycemia-induced neurological deficits, ipsilateral edema and hemorrhagic transformation, and accentuated peroxisome proliferator activated receptor-γ (PPAR-γ) upregulation and TXNIP/NLRP3 inflammasome activation after ischemic stroke. Higher expression of TXNIP in hyperglycemic t-MCAO animals augmented glucose transporter 1 (GLUT-1) downregulation and increased vascular endothelial growth factor-A (VEGF-A) expression/matrix metallopeptidase 9 (MMP-9) signaling, all of which result in blood brain barrier (BBB) disruption and increased permeability to endogenous immunoglobulin G (IgG). It was also associated with a discernible buildup of nitrotyrosine and accumulation of dysfunctional tight junction proteins: zonula occludens-1 (ZO-1), occludin and claudin-5. Moreover, tPA administration triggered activation of high mobility group box protein 1 (HMGB-1), nuclear factor kappa B (NF-κB), and tumor necrosis factor-α (TNF-α) expression in the ischemic penumbra of hyperglycemic animals. All of these observations suggest a powerful role for TXNIP-NLRP3 inflammasome activation in the tPA-induced toxicity seen with hyperglycemic stroke.

Abstract WMP82: Inhibition of Thioredoxin Interacting Protein Attenuates Tissue Plasminogen Activator Induced Brain Damage Under Acute Hyperglycemia in Murine Stroke Model

Background and Hypothesis: Acute hyperglycemia (AHG) worsens stroke outcome and increases the risk of intracerebral hemorrhage after tissue plasminogen activator (tPA) treatment, independent of preexisting diabetes. We have previously reported that genetic deletion of thioredoxin interacting protein exerts neuroprotection after experimental stroke. Here we tested the hypothesis that pharmacological inhibition of TXNIP, with verapamil protects against tPA-induced brain damage under AHG in a mouse model of focal cerebral ischemia.

Methods: Transient focal cerebral ischemia was induced by a 60 min middle cerebral artery occlusion (MCAO) followed by 23 h reperfusion in mice. AHG was induced by administration of 20% glucose (ip), 15 minutes before MCAO. Verapamil (0.015 mg/kg, iv) and tPA (iv), or saline was administered at 1 h post-occlusion. After 24 h of I/R, mice were tested for neurobehavioral outcome and were evaluated for infarct size and expression inflammatory mediators, and blood brain barrier markers.

Results: AHG aggravated brain edema, blood brain disruption and neuroinflammation. Treatment with verapamil significantly reduced in the infarct size (41%, p<0.05), hemorrhage (36%) and edema (36%, p<0.05) compared to saline treated controls. Furthermore, verapamil significantly inhibited the TXNIP mediated activation of NLRP3-inflammsome and ameliorated blood brain barrier leakage (Table 1).

Conclusion: Taken together, these data indicate that inhibition of TXNIP with verapamil may have therapeutic implications on ischemic stroke in the acute hyperglycemic condition.

Metabolic Syndrome, Brain Insulin Resistance, and Alzheimer's Disease: Thioredoxin Interacting Protein (TXNIP) and Inflammasome as Core Amplifiers

Empirical evidence indicates a strong association between insulin resistance and pathological alterations related to Alzheimer's disease (AD) in different cerebral regions. While cerebral insulin resistance is not essentially parallel with systemic metabolic derangements, type 2 diabetes mellitus (T2DM) has been established as a risk factor for AD. The circulating "toxic metabolites" emerging in metabolic syndrome may engage several biochemical pathways to promote oxidative stress and neuroinflammation leading to impair insulin function in the brain or "type 3 diabetes". Thioredoxin-interacting protein (TXNIP) as an intracellular amplifier of oxidative stress and inflammasome activation may presumably mediate central insulin resistance. Emerging data including those from our recent studies has demonstrated a sharp TXNIP upregulation in stroke, aging and AD and well underlining the significance of this hypothesis. With the main interest to illustrate TXNIP place in type 3 diabetes, the present review primarily briefs the potential mechanisms contributing to cerebral insulin resistance in a metabolically deranged environment. Then with a particular focus on plausible TXNIP functions to drive and associate with AD pathology, we present the most recent evidence supporting TXNIP as a promising therapeutic target in AD as an age-associated dementia.

Dose-response, therapeutic time-window and tPA-combinatorial efficacy of compound 21: A randomized, blinded preclinical trial in a rat model of thromboembolic stroke

The aim of this translational, randomized, controlled, blinded preclinical trial was to determine the effect of compound 21 (C21) in embolic stroke. Rats were subjected to embolic-middle cerebral artery occlusion (eMCAO). They received C21 (0.01, 0.03 and 0.06 mg/kg/d) or saline (orally) for five days, with the first-dose given IV at 3 h post-eMCAO. For the time-window study, the optimal-dose of C21 was initiated at 3, 6 or 24 h post-eMCAO and continued for five days. For the combinatorial study, animals received IV-tissue plasminogen activator (tPA) at either 2 or 4 h, with IV-C21 (0.01 mg/kg) or saline at 3 h post-eMCAO and daily thereafter for five days. After performing the behavior tests, brains were collected for analyses. The dose-response study showed significant motor improvements with the lowest-dose (0.01 mg/kg) of C21. In the time-window study, this same dose resulted in improvements when given 6 h and 24 h post-eMCAO. Moreover, C21-treated animals performed better on the novel object recognition test. Neither the single treatment with C21 or tPA (4 h) nor the combination therapy was effective in reducing the hemorrhage or infarct size, although C21 alone lowered sensorimotor deficit scores post-eMCAO. Future studies should focus on the long-term cognitive benefits of C21, rather than acute neuroprotection.

Angiotensin II type 2 receptor stimulation with compound 21 improves neurological function after stroke in female rats: a pilot study

The angiotensin II type 2 receptor (AT2R) agonist, compound 21 (C21), has been shown to be neurovascularly protective after ischemic stroke in male rats. In the current study, we aim to study the impact of C21 treatment on female rats. Young female Wistar rats were subjected to different durations of middle cerebral artery occlusion (MCAO) (3 h, 2 h, and 1 h) using a silicone-coated monofilament, treated at reperfusion with 0.03 mg/kg ip of C21 and followed up for different times (1, 3, and 14 days) after stroke. Behavioral tests were performed (Bederson, paw grasp, beam walk, and rotarod), and animals were euthanized for infarct size analysis and Western blot analysis. In vitro, primary male and female brain microvascular endothelial cells (ECs) were grown in culture, and the expression of the AT2R was compared between males and females. At 1 day, C21 treatment resulted in an improvement in Bederson scores. However, at 3 days and 14 days, the impact of C21 on stroke outcomes was less robust. In vitro, the expression of the AT2R was significantly higher in female ECs compared with male ECs. In conclusion, C21 improves Bederson scores after stroke in female rats when administered early at reperfusion. The ability of C21 to exert its neuroprotective effects might be affected by fluctuating levels of female hormones. NEW & NOTEWORTHY The present study shows the neuroprotective impact of C21 on ischemic stroke in female rats and how the protective effects of C21 can be influenced by the hormonal status of female rodents.

Abstract WP137: Angiotensin Type 2 Receptor Stimulation With Compound 21 Prevents Delayed Cognitive Impairment in Hypertensive, Ovariectomized Female Rats After Ischemic Stroke: A Randomized, Blinded, Preclinical Study

Introduction: The angiotensin type 2 receptor (AT2R) agonist, compound 21 (C21), has been shown to be neuroprotective and neurorestorative after stroke in male rats. Here, we aim to determine the long-term impact of C21 treatment on hypertensive female rats after stroke.

Methods: Twenty female ovariectomized spontaneously hypertensive rats (SHRs), 16 weeks of age, were subjected to 1h MCAO and randomized at 24h to receive either vehicle or IP C21 0.03 mg/kg for 5 days followed by oral C21 (0.12mg/kg/day) for 5 weeks in drinking water. Sensorimotor behavior tests (modified Bederson, 0-8, where 8 is normal) were performed at 24h and weekly, while cognitive assessments (Passive Avoidance and Novel Object Recognition) were performed at weeks 5 and 6.

Results: (mean±SEM) All stroked animals survived and showed improved motor performance at 6 weeks, with no effect of C21. However, C21 treatment significantly improved non-spatial working memory and reference memory without an effect on anxiety level at 6 weeks post-stroke.

Conclusions: AT2R stimulation using C21 improves sensorimotor function and prevents the development of cognitive impairment in ovariectomized female rats, even when initiated at 24 hours after stroke.

Thioredoxin-Interacting Protein (TXNIP) Associated NLRP3 Inflammasome Activation in Human Alzheimer's Disease Brain

Alzheimer's disease (AD) is the most common form of age-associated dementia characterized by amyloid-β plaques and neurofibrillary tangles. Recent studies have demonstrated that thioredoxin-interacting protein (TXNIP), an endogenous regulator of redox/glucose induced stress and inflammation, is now known to be upregulated in stroke, traumatic brain injury, diabetes and AD. We hypothesized that TXNIP overexpression sustains neurodegeneration through activation of the nucleotide binding and oligomerization domain-like receptor protein 3 in human AD brains. We analyzed TXNIP and the components of the NLRP3 inflammasome in the cortex of postmortem human brain samples by western blotting, real-time PCR, and immunohistochemical techniques in comparison with age-matched non-demented controls. Our results demonstrate that TXNIP protein as well as its mRNA levels in the cortex was significantly upregulated in AD compared to control brains. Moreover, using double immunofluorescence staining, TXNIP and interlukin-1β (IL-1β) were co-localized near Aβ plaques and p-tau. These results suggest an association between TXNIP overexpression levels and AD pathogenesis. Further, a significant increased expression of cleaved caspase-1 and IL-1β, the products of inflammasome activation, was detected in the cortex of AD brains. Together, these findings suggest that TXNIP, an upstream promising new therapeutic target, is a molecular link between inflammation and AD. The significant contribution of TXNIP to AD pathology suggests that strategies focusing on specific targeting of the TXNIP-NLRP3 inflammasome may lead to novel therapies for the management of AD and other age-related dementias.

RAS modulation prevents progressive cognitive impairment after experimental stroke: a randomized, blinded preclinical trial

Background

With the aging population, the prevalence and incidence of cerebrovascular disease will continue to rise, as well as the number of individuals with vascular cognitive impairment/dementia (VCID). No specific FDA-approved treatments for VCID exist. Although clinical evidence supports that angiotensin receptor blockers (ARBs) prevent cognitive decline in older adults, whether ARBs have a similar effect on VCID after stroke is unknown. Moreover, these agents reduce BP, which is undesirable in the acute stroke period, so we believe that giving C21 in this acute phase or delaying ARB administration would enable us to achieve the neurovascular benefits without the risk of unintended and potentially dangerous, acute BP lowering.

Methods

The aim of our study was to determine the impact of candesartan (ARB) or compound-21 (an angiotensin type 2 receptor––AT2R––agonist) on long-term cognitive function post-stroke, in spontaneously hypertensive rats (SHRs). We hypothesized that AT2R stimulation, either directly with C21, or indirectly by blocking the angiotensin type 1 receptor (AT1R) with candesartan, initiated after stroke, would reduce cognitive impairment. Animals were subjected to a 60-min transient middle cerebral artery occlusion and randomly assigned to either saline/C21 monotherapy, for the full study duration (30 days), or given sequential therapy starting with saline/C21 (7 days) followed by candesartan for the remainder of the study (21 days). Outcome measures included sensorimotor/cognitive-function, amyloid-β determination, and histopathologic analyses.

Results

Treatment with RAS modulators effectively preserved cognitive function, reduced cytotoxicity, and prevented chronic-reactive microgliosis in SHRs, post-stroke. These protective effects were apparent even when treatment was delayed up to 7 days post-stroke and were independent of blood pressure and β-amyloid accumulation.

Conclusion

Collectively, our findings demonstrate that RAS modulators effectively prevent cognitive impairment after stroke, even when treatment is delayed.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1262-x) contains supplementary material, which is available to authorized users.

Silencing VEGF-B Diminishes the Neuroprotective Effect of Candesartan Treatment After Experimental Focal Cerebral Ischemia

The pro-survival effect of VEGF-B has been documented in different in vivo and in vitro models. We have previously shown an enhanced VEGF-B expression in response to candesartan treatment after focal cerebral ischemia. In this study, we aimed to silence VEGF-B expression to assess its contribution to candesartan's benefit on stroke outcome. Silencing VEGF-B expression was achieved by bilateral intracerebroventricular injections of lentiviral particles containing short hairpin RNA (shRNA) against VEGF-B. Two weeks after lentiviral injections, rats were subjected to either 90 min or 3 h of middle cerebral artery occlusion (MCAO) and randomized to intravenous candesartan (1 mg/kg) or saline at reperfusion. Animals were sacrificed at 24 or 72 h and brains were collected and analyzed for hemoglobin (Hb) excess and infarct size, respectively. Functional outcome at 24, 48 and 72 h was assessed blindly. Candesartan treatment improved neurobehavioral and motor function, and decreased infarct size and Hb. While silencing VEGF-B expression diminished candesartan's neuroprotective effect, candesartan-mediated vascular protection was maintained even in the absence of VEGF-B suggesting that this growth factor is not the mediator of candesartan's vascular protective effects. However, VEGF-B is a mediator of neuroprotection achieved by candesartan and represents a potential drug target to improve stroke outcome. Further studies are needed to elucidate the underlying molecular mechanisms of VEGF-B in neuroprotection and recovery after ischemic stroke.

Inhibition of the NLRP3-inflammasome as a potential approach for neuroprotection after stroke

Activation of the NOD-like receptor protein (NLRP3)-inflammasome has been postulated to mediate inflammatory responses to brain damage during ischemic/reperfusion (I/R) injury. We therefore hypothesized that MCC950, a selective NLRP3-inflammasome inhibitor provides protection in mouse model of transient middle cerebral artery occlusion (tMCAO). Focal cerebral ischemia was induced by 60 min tMCAO followed by intraperitoneal administration of MCC950 (50 mg/kg) or saline at 1 h and 3 h post-occlusion. After 24 h of I/R, mice were tested for neurological outcome and were sacrificed for the analysis of infarct size and estimating NLRP3-inflammasome and apoptotic markers as well. Spectrophotometric method was used to determine hemoglobin (Hb) content as a marker of intracerebral hemorrhage. MCC950-treated mice showed a substantial reduction in infarction, edema and Hb content compared to saline controls in parallel with improved neurological deficits. MCC950 reduced expression of NLRP3-inflammasome cleavage products Caspase-1 and interlukin-1β (IL-1β) in penumbral region. These protective effects of MCC950 were associated with decreased TNF-α levels as well as poly (ADP-ribose) polymerase (PARP) and Caspase-3 cleavage and paralleled less phosphrylated NFκBp65 and IκBα levels. Taken together, these data indicate that inhibition of NLRP3-inflammasome with MCC950 has therapeutic potential in ischemic stroke models. Further investigations into the therapeutic efficacy and protocols are needed to confirm whether MCC950 treatment could be a promising candidate for clinical trials.

MCC950, the Selective Inhibitor of Nucleotide Oligomerization Domain-Like Receptor Protein-3 Inflammasome, Protects Mice against Traumatic Brain Injury

Nucleotide oligomerization domain (NOD)-like receptor protein-3 (NLRP3) inflammasome may intimately contribute to sustaining damage after traumatic brain injury (TBI). This study aims to examine whether specific modulation of NLPR3 inflammasome by MCC950, a novel selective NLRP3 inhibitor, confers protection after experimental TBI. Unilateral cortical impact injury was induced in young adult C57BL/6 mice. MCC950 (50 mg/kg, intraperitoneally) or saline was administration at 1 and 3 h post-TBI. Animals were tested for neurological function and then sacrificed at 24 or 72 h post-TBI. Immunoblotting and histological analysis were performed to identify markers of NLRP3 inflammasome and proapoptotic activity in pericontusional areas of the brains at 24 or 72 h post-TBI. MCC950 treatment provided a significant improvement in neurological function and reduced cerebral edema in TBI animals. TBI upregulated NLRP3, apoptosis-associated speck-like adapter protein (ASC), cleaved caspase-1, and interlukein-1β (IL-1β) in the perilesional area. MCC950 efficiently repressed caspase-1 and IL-1β with a transient effect on ASC and NLRP3 post-TBI. MCC950 treatment also provided protection against proapoptotic activation of poly (ADP-ribose) polymerase and caspase-3 associated with TBI. A concurrent inhibition of inflammasome priming was also detectable at the nuclear factor kappa B/p65 and caspase-1 level. Our findings support the implication of NLRP3 inflammasome in the pathogenesis of TBI and further suggests the therapeutic potential of MCC950.

Abstract TP88: Delayed Therapeutic Window for Prevention of Progressive Cognitive Impairment After Experimental Stroke

Background: With the aging population, the prevalence and incidence of cerebrovascular disease will continue to rise, as will the number of individuals with post-stroke cognitive impairment (PSCI). Unfortunately, no specific FDA approved treatments for PSCI exist. Although clinical trial evidence supports that renin angiotensin system (RAS) modulation by angiotensin receptor blockers (ARBs) prevent cognitive decline in older adults. The aim of our study was to determine the impact of the ARB candesartan or the AT2R agonist, C21, after stroke, on long-term cognitive function in spontaneously hypertensive rats (SHRs).

Methods: Thirty three SHRs were subjected to a 60 minute transient middle cerebral artery occlusion (MCAO) and randomly assigned to either Saline/ C21 (0.3 mg/kg, IP) only or Saline/ C21 (7 days) followed by candesartan (0.3 mg/kg) IP for the remainder of the study. Outcome measures included sensorimotor and cognitive function, performed using a sequence of blinded tests, and assessed at baseline and up to 28 days post-stroke. Animals were sacrificed at 30 days and their brains collected for amyloid-β protein determination and histopathologic analyses.

Results: Chronic administration of C21, or candesartan prevented PSCI, even when treatment was initiated at 7 days after the ischemic insult. The groups treated with C21 and candesartan demonstrated superior performance on the novel NOR test, compared to saline treated animals. C21 (first 7 days) only or C2 and candesartan treatments had markedly lower hippocampal concentrations of Aβ1-42 at 30 days post-stroke than those treated with saline. Sensorimotor deficits (Bederson and beam walk scores) were pronounced at 24 h post-stroke and all treatment groups showed similar recovery at 28 days post stroke. C21 had no effect on BP compared to saline-treated controls.

Conclusion: Collectively, our findings demonstrate that RAS modulators effectively prevent PSCI, even when treatment is delayed.

Abstract WP94: MCC950, a Novel Selective NLRP3-inflammasome Inhibitor Provides Protection in a Murine Model of Focal Cerebral Ischemia

Background and Hypothesis: Activation of the NOD-like receptor protein (NLRP3) inflammasome has been postulated in mediating inflammatory responses to brain damage during ischemic reperfusion (I/R) injury. In this study, we therefore hypothesized that MCC950, a selective NLRP3-inflammasome inhibitor provides protection in a mouse model of ischemic stroke.

Methods: Transient focal cerebral ischemia was induced by 60 min middle cerebral artery occlusion (MCAO) followed by 23 h reperfusion in mice. MCC950 (50 mg/kg) or saline was administered intraperitoneally at 1 h and 3 h post-occlusion. After 24 h of I/R, mice were tested for neurobehavioral outcome and were sacrificed for infarct size analysis and estimation of inflammasome and apoptotic markers.

Results: MCC950-treated mice showed a substantial reduction (28%) in the infarct size (% contralateral hemisphere) and edema (29%) compared to saline controls. Further, administration of MCC950 after MCAO reduced the brain hemorrhage compared to saline treated mice. MCC950 treatment significantly (P<0.05) inhibited the expression of NLRP3-inflammsome components, and suppressed inflammatory and apoptotic damage ( Table 1 ).

Conclusion: Taken together, these data indicate that inhibition of NLRP3-inflammasome with MCC950 may have therapeutic potential in ischemic stroke model. Further investigations into the role and mechanisms of NLRP3 inhibition are needed to determine whether it can be an effective therapy for stroke patients.

Abstract TP100: Angiotensin Type 2 Receptor Stimulation With Compound 21 Improves Stroke Outcome in Female Rats: Possible Role for Peroxisome Proliferator-activated Receptor Gamma

Introduction: The angiotensin type 2 receptor (AT2R) agonist, compound 21 (C21), has been shown to be neuro-protective, pro-angiogenic and anti-inflammatory after stroke in male rats. Here we aimed to study the effect of C21 treatment on ovary-intact female rats after stroke.

Methods: Female Wistar rats were subjected to 3 h middle cerebral artery occlusion (MCAO) using a silicone-coated monofilament and treated at reperfusion with IP C21 0.03 mg/kg. Rats were sacrificed at 24 h and brains collected for infarct analysis. Another cohort of female rats were subjected to MCAO and treated at reperfusion with C21 for 2 days. Animals were followed up and sacrificed at 72 h. Behavioral tests (Bederson, Paw grasp, Beam walk and Rotarod) were performed at 24 h and 72 h, and whole brains were collected for western blotting.

Results (mean±SEM): C21 treatment in females resulted in a decrease in infarct size, improvement in Bederson, Paw grasp and rotarod scores. Interestingly, C21 treatment showed a trend toward increased expression of the transcription factor PPARγ at 72 h in sham and stroked animals suggesting a novel crosstalk between the AT2R and PPARγ after ischemic stroke. In addition, stroke surgery resulted in a decrease in the AT2R expression. However, sham treated animals had an increase in the AT2R expression.

Conclusions: AT2R stimulation using C21 improves stroke outcome in ovary-intact female rats.

Abstract TP89: Angiotensin Receptor (AT2R) Agonist C21 Accelerates Cognitive Functional Recovery After Permanent Stroke in Aged Animals

Background and objectives: Post stroke cognitive impairment (PSCI) is an understudied, long-term complication of stroke, impacting nearly 30-40% of all stroke survivors. No cure is available once the cognitive deterioration manifests. Compound 21 (C21), a novel selective non-peptide angiotensin receptor (AT2R) agonist, has also shown therapeutic efficacy in a variety of experimental stroke models, but C21 effect on PSCI model is lacking. To our knowledge, this is the first study to investigate the long-term effects of C21 treatment on the development of PSCI in aged animals.

Methods: Distal docal cerebral ischemia was induced in 14-month-old male Wistar rats by direct electro-coagulation of middle cerebral artery for permanent occlusion (pMCAO). Animals were randomly assigned to receive either C21 or vehicle which was initiated the following day, and continued for a total of 30 days (0.12 mg/kg/d, orally). Outcome measures for sensorimotor and cognitive function were performed using a sequence of tests, all blindly conducted and assessed at baseline as well as at different time points post-pMCAO. Repeated measures ANOVA mixed models were used to examine differences in behavioral outcomes.

Results: C21 reduced weight loss and enhanced recovery (Table). Treatment with C21 showed significant improvement in non-spatial and short-term working memory compared to vehicle. Moreover, C21 preserved reference memory and facilitated associative learning compared to vehicle treated rats after pMCAO. Further, C21 prevented Aβ 1-42 . C21 did not show any effect on motor deficits score compared to vehicle.

Conclusion: Our findings demonstrate that the angiotensin receptor (AT2R) agonist C21 effectively preserves cognitive function and prevents the development of PSCI in aged animals.

Mechanisms of acute neurovascular protection with AT1 blockade after stroke: Effect of prestroke hypertension

Stroke is a leading cause of adult disability worldwide. Improving stroke outcome requires an orchestrated interplay that involves up regulation of pro-survival pathways and a concomitant suppression of pro-apoptotic mediators. In this investigation, we assessed the involvement of eNOS in the AT1 blocker-mediated protective and pro-recovery effects in animals with hypertension. We also evaluated the effect of acute eNOS inhibition in hypertensive animals. To achieve these goals, spontaneously hypertensive rats (SHR) were implanted with blood pressure transmitters, and randomized to receive either an eNOS inhibitor (L-NIO) or saline one hour before cerebral ischemia induction. After 3 hours of ischemia, animals were further randomized to receive either candesartan or saline at the time of reperfusion and sacrificed either 24 hours or 7 days later. Candesartan induced an early protective effect that was independent of eNOS inhibition (50% improvement in motor function). However, the protective effect of candesartan was associated with about five fold up regulation of BDNF expression and about three fold reduction in ER stress markers, in an eNOS dependent manner. The early benefit of a single dose of candesartan, present at 24 hours after stroke, was diminished at 7 days, perhaps due to a failure to induce an angiogenic response in these hypertensive animals. In conclusion, our findings demonstrate an early prorecovery effect of candesartan at both functional and molecular levels. Candesartan induced prorecovery signaling was mediated through eNOS. This effect was not maintained at 7 days after experimental ischemia.

MyD88 contributes to neuroinflammatory responses induced by cerebral ischemia/reperfusion in mice

Myeloid differentiation primary-response protein-88 (MyD88) is one of adaptor proteins mediating Toll-like receptors (TLRs) signaling. Activation of MyD88 results in the activation of nuclear factor kappa B (NFκB) and the increase of inflammatory responses. Evidences have demonstrated that TLRs signaling contributes to cerebral ischemia/reperfusion (I/R) injury. However, the role of MyD88 in this mechanism of action is disputed and needs to be clarified. In the present study, in a mouse model of cerebral I/R, we examined the activities of NFκB and interferon factor-3 (IRF3), and the inflammatory responses in ischemic brain tissue using ELISA, Western blots, and real-time PCR. Neurological function and cerebral infarct size were also evaluated 24 h after cerebral I/R. Our results showed that NFκB activity increased in ischemic brains, but IRF3 was not activated after cerebral I/R, in wild-type (WT) mice. MyD88 deficit inhibited the activation of NFκB, and the expression of interleukin-1β (IL-1β), IL-6, Beclin-1 (BECN1), pellino-1, and cyclooxygenase-2 (COX-2) increased by cerebral I/R compared with WT mice. Interestingly, the expression of interferon Beta 1 (INFB1) and vascular endothelial growth factor (VEGF) increased in MyD88 KO mice. Unexpectedly, although the neurological function improved in the MyD88 knockout (KO) mice, the deficit of MyD88 failed to reduce cerebral infarct size compared to WT mice. We concluded that MyD88-dependent signaling contributes to the inflammatory responses induced by cerebral I/R. MyD88 deficit may inhibit the increased inflammatory response and increase neuroprotective signaling.

Progesterone improves long-term functional and histological outcomes after permanent stroke in older rats

Previous studies have shown progesterone to be beneficial in animal models of central nervous system injury, but less is known about its longer-term sustained effects on recovery of function following stroke. We evaluated progesterone's effects on a panel of behavioral tests up to 8 weeks after permanent middle cerebral artery occlusion (pMCAO). Male Sprague-Dawley rats 12m.o. were subjected to pMCAO and, beginning 3h post-pMCAO, given intraperitoneal injections of progesterone (8mg/kg) or vehicle, followed by subcutaneous injections at 8h and then every 24h for 7 days, with tapering of the last 2 treatments. The rats were then tested on functional recovery at 3, 6 and 8 weeks post-stroke. We observed that progesterone-treated animals showed attenuation of infarct volume and improved functional outcomes at 8 weeks after stroke on grip strength, sensory neglect, motor coordination and spatial navigation tests. Progesterone treatments significantly improved motor deficits in the affected limb on a number of gait parameters. Glial fibrillary acidic protein expression was increased in the vehicle group and considerably lowered in the progesterone group at 8 weeks post-stroke. With repeated post-stroke testing, sensory neglect and some aspects of spatial learning performance showed spontaneous recovery, but on gait and grip-strength measres progesterone given only in the acute stage of stroke (first 7 days) showed sustained beneficial effects on all other measures of functional recovery up to 8 weeks post-stroke.

Abstract WP113: Dose-response and Therapeutic Time-window of Compound 21: a Randomized Preclinical Trial in Rat Model of Thromboembolic Stroke

Background: We and others have previously shown promising results with the use of the angiotensin type 2 receptor agonist, compound 21 (C21), in experimental stroke. Here we aimed to determine the best dose and time window for C21 in a clinically relevant embolic stroke model.

Methods: This study was conducted as a translational, randomized, controlled, blinded preclinical trial with the guidance of our biostatistician. Male Wistar rats (8-9 weeks old) were subjected to embolic middle cerebral artery occlusion (eMCAO). For the dose-response study, animals received C21 (0.01, 0.03 and 0.06 mg/kg/d) or saline (orally) for 5 days, with the first dose given IV at 3 h post-eMCAO. For the time-window study, the optimal dose of C21 was initiated at 3, 6 or 24 h post-eMCAO and daily thereafter, for 5 days. Behavioral outcomes (Bederson, paw grasp and grip strength) were blindly assessed at days, 1, 3, 5 and 7. Rats were then sacrificed and their brains collected for infarct size and vascular density analyses. Results (Table): In the dose-response study, repeated-measures ANOVA showed significant (p < 0.05) behavioral improvement with the low dose (0.01 mg/kg). This dose was associated with higher vascularity in the ischemic penumbra, detected by laminin staining, compared to saline treated controls (65±6 vs 46±7 p < 0.05). In the time-window study, the 0.01 mg/kg dose displayed non-statistically significant improvements when given 3 h and 6 h after eMCAO. There were no differences between doses or time-windows for either % infarct size or tissue loss.

Conclusions: C21 given at 0.01 mg/kg/d was effective in improving behavioral dysfunction after embolic stroke when administered within 6 h. Compound C21 shows promise as a potential therapeutic agent and should be examined for safety and efficacy in clinical trials for ischemic stroke.

Abstract WP101: Involvement of the Contralesional Angiotensin Type 2 Receptor in Compound 21 Mediated Functional Recovery After Stroke

Introduction: We have recently shown that the angiotensin type 2 receptor (AT2R) agonist, compound 21 (C21), provides sustained functional recovery after ischemic stroke. This was associated with upregulation of the AT2R and the neurotrophin, brain derived neurotrophic factor (BDNF), in the contralesional brain hemisphere. Here, we aimed to study the contribution of this hemisphere in C21 mediated functional recovery after stroke through localized knockdown of the AT2R.

Methods: male wistar rats (34) received two intrastriatal injections of short hairpin RNA (shRNA) lentiviral particles against AT2R, or non-targeting control vector (NTC) into the left brain hemisphere to achieve localized AT2R knockdown. After 14 days, rats were subjected to 90 minutes right middle cerebral artery occlusion (MCAO) and received either C21 (0.03 mg/kg) or saline at reperfusion (IV) then daily (IP) for 7 days. Rats were blindly assessed for behavioral outcome up to 10 days as well as molecular analysis. Results (table): PCR and Western blotting confirmed successful knockdown of the AT2R in the left (contralesional) hemisphere by about 50%. All groups showed worsened outcome on days 1 to 3 then recovered on days 7 to 10. The C21/NTC group showed better behavioral outcome compared to other groups at days 7 and 10, while the saline/shRNA group was associated with the least recovery. Using Western blotting, C21/NTC group showed higher BDNF and lower proBDNF (pro-form) levels in the ischemic and contralesional hemispheres respectively. Expression of the pro-apoptotic P75NTR receptor of proBDNF was decreased with C21 treatment irrespective of AT2R knockdown.

Conclusion: Contralesional AT2R could be involved in C21 mediated functional recovery after stroke.

Brain-Derived Neurotrophic Factor Knockdown Blocks the Angiogenic and Protective Effects of Angiotensin Modulation After Experimental Stroke

Angiotensin type 1 receptor blockers (ARBs) have been shown to be neuroprotective and neurorestorative in experimental stroke. The mechanisms proposed include anti-inflammatory, antiapoptotic effects, as well as stimulation of endogenous trophic factors leading to angiogenesis and neuroplasticity. We aimed to investigate the involvement of the neurotrophin, brain-derived neurotrophic factor (BDNF), in ARB-mediated functional recovery after stroke. To achieve this aim, Wistar rats received bilateral intracerebroventricular (ICV) injections of short hairpin RNA (shRNA) lentiviral particles or nontargeting control (NTC) vector, to knock down BDNF in both hemispheres. After 14 days, rats were subjected to 90-min middle cerebral artery occlusion (MCAO) and received the ARB, candesartan, 1 mg/kg, or saline IV at reperfusion (one dose), then followed for another 14 days using a battery of behavioral tests. BDNF protein expression was successfully reduced by about 70 % in both hemispheres at 14 days after bilateral shRNA lentiviral particle injection. The NTC group that received candesartan showed better functional outcome as well as increased vascular density and synaptogenesis as compared to saline treatment. BDNF knockdown abrogated the beneficial effects of candesartan on neurobehavioral outcome, vascular density, and synaptogenesis. In conclusion, BDNF is directly involved in candesartan-mediated functional recovery, angiogenesis, and synaptogenesis.