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

Activation of the ROS/TXNIP/NLRP3 pathway disrupts insulin-dependent glucose uptake in skeletal muscle of insulin-resistant obese mice

Oxidative stress and the activation of the nucleotide-binding domain, leucine-rich-containing family, pyrin domain containing 3 (NLRP3) inflammasome have been linked to insulin resistance in skeletal muscle. In immune cells, the exacerbated generation of reactive oxygen species (ROS) activates the NLRP3 inflammasome, by facilitating the interaction between thioredoxin interacting protein (TXNIP) and NLRP3. However, the precise role of ROS/TXNIP-dependent NLRP3 inflammasome activation in skeletal muscle during obesity-induced insulin resistance remains undefined. Here, we induced insulin resistance in C57BL/6J mice by feeding them for 8 weeks with a high-fat diet (HFD) and explored whether the ROS/TXNIP/NLRP3 pathway was involved in the induction of insulin resistance in skeletal muscle. Skeletal muscle fibers from insulin-resistant mice exhibited increased oxidative stress, as evidenced by elevated malondialdehyde levels, and altered peroxiredoxin 2 dimerization. Additionally, these fibers displayed augmented activation of the NLRP3 inflammasome, accompanied by heightened ROS-dependent proximity between TXNIP and NLRP3, which was abolished by the antioxidant N-acetylcysteine (NAC). Inhibition of the NLRP3 inflammasome with MCC950 or suppressing the ROS/TXNIP/NLRP3 pathway with NAC restored insulin-dependent glucose uptake in muscle fibers from insulin-resistant mice. These findings provide insights into the mechanistic link between oxidative stress, NLRP3 inflammasome activation, and obesity-induced insulin resistance in skeletal muscle.

Hyperglycemia induces microglial pyroptosis by increasing oxygen extraction rate: Implication in neurological impairment during ischemic stroke

Elevated levels of blood glucose in patients with ischemic stroke are associated with a worse prognosis. The present study aimed to explore whether hyperglycemia promotes microglial pyroptosis by increasing the oxygen extraction rate in an acute ischemic stroke model. C57BL/6 mice that underwent middle cerebral artery occlusion were used for assessment of blood glucose level and neurological function. The cerebral oxygen extraction ratio (CERO2), oxygen consumption rate (OCR) and partial pressure of brain tissue oxygen (PbtO2) were measured. To investigate the significance of the NOD‑like receptor protein 3 (NLRP3) inflammasome, NLRP3‑/‑ mice were used, and the expression levels of NLRP3, caspase‑1, full‑length gasdermin D (GSDMD‑FL), GSDMD‑N domain (GSDMD‑N), IL‑1β and IL‑18 were evaluated. In addition, Z‑YVAD‑FMK, a caspase‑1 inhibitor, was used to treat microglia to determine whether activation of the NLRP3 inflammasome was required for the enhancing effect of hyperglycemia on pyroptosis. It was revealed that hyperglycemia accelerated cerebral injury in the acute ischemic stroke model, as evidenced by decreased latency to fall and the percentage of foot fault. Hyperglycemia aggravated hypoxia by increasing the oxygen extraction rate, as evidenced by increased CERO2 and OCR, and decreased PbtO2 in response to high glucose treatment. Furthermore, hyperglycemia‑induced microglial pyroptosis was confirmed by detection of increased levels of caspase‑1, GSDMD‑N, IL‑1β and IL‑18 and a decreased level of GSDMD‑FL. However, the knockout of NLRP3 attenuated these effects. Pharmacological inhibition of caspase‑1 also reduced the expression levels of GSDMD‑N, IL‑1β and IL‑18 in microglial cells. These results suggested that hyperglycemia stimulated NLRP3 inflammasome activation by increasing the oxygen extraction rate, thus leading to the aggravation of pyroptosis following ischemic stroke.

Mechanism and treatment of intracerebral hemorrhage focus on mitochondrial permeability transition pore

Intracerebral hemorrhage (ICH) is the second most common subtype of stroke, characterized by high mortality and a poor prognosis. Despite various treatment methods, there has been limited improvement in the prognosis of ICH over the past decades. Therefore, it is imperative to identify a feasible treatment strategy for ICH. Mitochondria are organelles present in most eukaryotic cells and serve as the primary sites for aerobic respiration and energy production. Under unfavorable cellular conditions, mitochondria can induce changes in permeability through the opening of the mitochondrial permeability transition pore (mPTP), ultimately leading to mitochondrial dysfunction and contributing to various diseases. Recent studies have demonstrated that mPTP plays a role in the pathological processes associated with several neurodegenerative diseases including Parkinson's disease, Alzheimer's disease, Huntington's disease, ischemic stroke and ischemia-reperfusion injury, among others. However, there is limited research on mPTP involvement specifically in ICH. Therefore, this study comprehensively examines the pathological processes associated with mPTP in terms of oxidative stress, apoptosis, necrosis, autophagy, ferroptosis, and other related mechanisms to elucidate the potential mechanism underlying mPTP involvement in ICH. This research aims to provide novel insights for the treatment of secondary injury after ICH.

Targeting TXNIP in endothelial progenitors mitigates IL-8-induced neutrophil recruitment under metabolic stress

BACKGROUND

This study explores the potential role of Thioredoxin-interacting protein (TXNIP) silencing in endothelial colony-forming cells (ECFCs) within the scope of age-related comorbidities and impaired vascular repair. We aim to elucidate the effects of TXNIP silencing on vasculogenic properties, paracrine secretion, and neutrophil recruitment under conditions of metabolic stress.

METHODS

ECFCs, isolated from human blood cord, were transfected with TXNIP siRNA and exposed to a high glucose and β-hydroxybutyrate (BHB) medium to simulate metabolic stress. We evaluated the effects of TXNIP silencing on ECFCs' functional and secretory responses under these conditions. Assessments included analyses of gene and protein expression profiles, vasculogenic properties, cytokine secretion and neutrophil recruitment both in vitro and in vivo. The in vivo effects were examined using a murine model of hindlimb ischemia to observe the physiological relevance of TXNIP modulation under metabolic disorders.

RESULTS

TXNIP silencing did not mitigate the adverse effects on cell recruitment, vasculogenic properties, or senescence induced by metabolic stress in ECFCs. However, it significantly reduced IL-8 secretion and consequent neutrophil recruitment under these conditions. In a mouse model of hindlimb ischemia, endothelial deletion of TXNIP reduced MIP-2 secretion and prevented increased neutrophil recruitment induced by age-related comorbidities.

CONCLUSIONS

Our findings suggest that targeting TXNIP in ECFCs may alleviate ischemic complications exacerbated by metabolic stress, offering potential clinical benefits for patients suffering from age-related comorbidities.

A role of NLRP3 and MMP9 in migraine progression: a systematic review of translational study

Background

Migraines affect one billion individuals globally, with a higher occurrence among young adults and women. A significant survey in the United States indicated that 17.1% of women and 5.6% of men suffer from migraines. This study seeks to investigate the potential connection between NLRP3 and MMP9 in migraine pathology.

Methods

The research involved searching databases such as PubMed, Scopus, Science Direct, Google Scholar, and Proquest, with the search concluding on March 31, 2024. Following PRISMA guidelines, PICO data were collected, focusing exclusively on animal models induced by Nitroglycerine (10 mg/kg), while excluding clinical studies.

Results

The study, originally registered in Prospero Reg. No. CRD42022355893, conducted bias analysis using SYRCLE's RoB tool and evaluated author consensus using GraphPad v9.5.1. Out of 7,359 search results, 22 papers met the inclusion criteria. Inter-rater reliability among reviewers was assessed using Cohen's kappa statistics.

Conclusion

This review summarizes 22 preclinical studies on Nitroglycerin (NTG), NLRP3, MMP9, and related biomarkers in migraine. They reveal that NTG, especially at 10 mg/kg, consistently induces migraine-like symptoms in rodents by activating NLRP3 inflammasome and stimulating proinflammatory molecule production.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, CRD42022355893.

HMGB1: A New Target for Ischemic Stroke and Hemorrhagic Transformation

Stroke in China is distinguished by its high rates of morbidity, recurrence, disability, and mortality. The ultra-early administration of rtPA is essential for restoring perfusion in acute ischemic stroke, though it concurrently elevates the risk of hemorrhagic transformation. High-mobility group box 1 (HMGB1) emerges as a pivotal player in neuroinflammation after brain ischemia and ischemia-reperfusion. Released passively by necrotic cells and actively secreted, including direct secretion of HMGB1 into the extracellular space and packaging of HMGB1 into intracellular vesicles by immune cells, glial cells, platelets, and endothelial cells, HMGB1 represents a prototypical damage-associated molecular pattern (DAMP). It is intricately involved in the pathogenesis of atherosclerosis, thromboembolism, and detrimental inflammation during the early phases of ischemic stroke. Moreover, HMGB1 significantly contributes to neurovascular remodeling and functional recovery in later stages. Significantly, HMGB1 mediates hemorrhagic transformation by facilitating neuroinflammation, directly compromising the integrity of the blood-brain barrier, and enhancing MMP9 secretion through its interaction with rtPA. As a systemic inflammatory factor, HMGB1 is also implicated in post-stroke depression and an elevated risk of stroke-associated pneumonia. The role of HMGB1 extends to influencing the pathogenesis of ischemia by polarizing various subtypes of immune and glial cells. This includes mediating excitotoxicity due to excitatory amino acids, autophagy, MMP9 release, NET formation, and autocrine trophic pathways. Given its multifaceted role, HMGB1 is recognized as a crucial therapeutic target and prognostic marker for ischemic stroke and hemorrhagic transformation. In this review, we summarize the structure and redox properties, secretion and pathways, regulation of immune cell activity, the role of pathophysiological mechanisms in stroke, and hemorrhage transformation for HMGB1, which will pave the way for developing new neuroprotective drugs, reduction of post-stroke neuroinflammation, and expansion of thrombolysis time window.

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.

Increased serum levels of high-mobility group box 1 protein and the location characteristics in the patients of intracranial aneurysms

OBJECTIVE

Inflammation-related factors play a crucial role in intracranial aneurysms (IA) initiation, progression, and rupture. High mobility group box 1 (HMGB-1) serves as an alarm to drive the pathogenesis of the inflammatory disease. This study aimed to evaluate the role of HMGB-1 in IA and explore the correlation with other inflammatory-related factors.

METHODS

A total of twenty-eight adult male Japanese white rabbits were included in with elastase-induced aneurysms, n = 18) and the control group (normal rabbits, n = 10). To assess the expression of HMGB-1, both reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) was performed on serum samples obtained from human subjects (10 patients with IA and 10 healthy donors) as well as from rabbits (aneurysm group and control group). Immunohistochemistry and immunofluorescence were employed to evaluate the expression levels of elastic fibers, HMGB-1, tumor necrosis factor-alpha (TNF-α), and triggering receptor expressed on myeloid cells-1 (TREM-1).

RESULTS

The expression of HMGB-1 was found to be significantly higher in the IA group compared to the control group, both at the mRNA and protein levels (P < 0.0001). Similar findings were observed in the rabbit aneurysm model group compared to the control group (P < 0.0001). HMGB-1 expression was observed to be more abundant in the inner wall of the aneurysm compared to the external wall, whereas in the control group, it was rarely scattered. Additionally, the localization patterns of TNF-α and TREM-1 exhibited similar characteristics to HMGB-1.

CONCLUSION

Our findings demonstrate that HMGB-1 is highly expressed in both IA patients and rabbit aneurysm models. Furthermore, the similar localization patterns of HMGB-1, TNF-α, and TREM-1 suggest their potential involvement in the inflammatory processes associated with IA. These results highlight the potential of HMGB-1 as a novel therapeutic target for IA.

Inflammasomes in neurological disorders - mechanisms and therapeutic potential

Inflammasomes are molecular scaffolds that are activated by damage-associated and pathogen-associated molecular patterns and form a key element of innate immune responses. Consequently, the involvement of inflammasomes in several diseases that are characterized by inflammatory processes, such as multiple sclerosis, is widely appreciated. However, many other neurological conditions, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, stroke, epilepsy, traumatic brain injury, sepsis-associated encephalopathy and neurological sequelae of COVID-19, all involve persistent inflammation in the brain, and increasing evidence suggests that inflammasome activation contributes to disease progression in these conditions. Understanding the biology and mechanisms of inflammasome activation is, therefore, crucial for the development of inflammasome-targeted therapies for neurological conditions. In this Review, we present the current evidence for and understanding of inflammasome activation in neurological diseases and discuss current and potential interventional strategies that target inflammasome activation to mitigate its pathological consequences.

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.

The Role of Matrix Metalloproteinases in Hemorrhagic Transformation in the Treatment of Stroke with Tissue Plasminogen Activator

Ischemic stroke is a leading cause of disability and mortality worldwide. The only approved treatment for ischemic stroke is thrombolytic therapy with tissue plasminogen activator (tPA), though this approach often leads to a severe complication: hemorrhagic transformation (HT). The pathophysiology of HT in response to tPA is complex and not fully understood. However, numerous scientific findings suggest that the enzymatic activity and expression of matrix metalloproteinases (MMPs) in brain tissue play a crucial role. In this review article, we summarize the current knowledge of the functioning of various MMPs at different stages of ischemic stroke development and their association with HT. We also discuss the mechanisms that underlie the effect of tPA on MMPs as the main cause of the adverse effects of thrombolytic therapy. Finally, we describe recent research that aimed to develop new strategies to modulate MMP activity to improve the efficacy of thrombolytic therapy. The ultimate goal is to provide more targeted and personalized treatment options for patients with ischemic stroke to minimize complications and improve clinical outcomes.

Transcutaneous Electrical Nerve Stimulation (TENS) Alleviates Brain Ischemic Injury by Regulating Neuronal Oxidative Stress, Pyroptosis, and Mitophagy

Background

As a noninvasive treatment, transcutaneous electrical nerve stimulation (TENS) has been utilized to treat various diseases in clinic. However, whether TENS can be an effective intervention in the acute stage of ischemic stroke still remains unclear. In the present study, we aimed to explore whether TENS could alleviate brain infarct volume, reduce oxidative stress and neuronal pyroptosis, and activate mitophagy following ischemic stroke.

Methods

TENS was performed at 24 h after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats for 3 consecutive days. Neurological scores, the volume of infarction, and the activity of SOD, MDA, GSH, and GSH-px were measured. Moreover, western blot was performed to detect the related protein expression, including Bcl-2, Bax, TXNIP, GSDMD, caspase-1, NLRP3, BRCC3, HIF-1α, BNIP3, LC3, and P62. Real-time PCR was performed to detect NLRP3 expression. Immunofluorescence was performed to detect the levels of LC3.

Results

There was no significant difference of neurological deficit scores between the MCAO group and the TENS group at 2 h after MCAO/R operation (P > 0.05), while the neurological deficit scores of TENS group significantly decreased in comparison with MCAO group at 72 h following MACO/R injury (P < 0.05). Similarly, TENS treatment significantly reduced the brain infarct volume compared with the MCAO group (P < 0.05). Moreover, TENS decreased the expression of Bax, TXNIP, GSDMD, caspase-1, BRCC3, NLRP3, and P62 and the activity of MDA as well as increasing the level of Bcl-2, HIF-1α, BNIP3, and LC3 and the activity of SOD, GSH, and GSH-px (P < 0.05).

Conclusions

In conclusion, our results indicated that TENS alleviated brain damage following ischemic stroke via inhibiting neuronal oxidative stress and pyroptosis and activating mitophagy, possibly via the regulation of TXNIP, BRCC3/NLRP3, and HIF-1α/BNIP3 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.

Chronic kidney disease and NLRP3 inflammasome: Pathogenesis, development and targeted therapeutic strategies

Chronic kidney disease (CKD) is a global health concern and public health priority. The condition often involves inflammation due to the accumulation of toxins and the reduced clearance of inflammatory cytokines, leading to gradual loss of kidney function. Because of the tremendous burden of CKD, finding effective treatment strategies against inflammation is crucial. Substantial evidence suggests an association between kidney disease and the inflammasome. As a well-known multiprotein signaling complex, the NLR family pyrin domain containing 3 (NLRP3) inflammasome plays an important role in inducing renal inflammation and fibrosis. Small molecule inhibitors targeting the NLRP3 inflammasome are potential agents for the treatment of CKD.The NLRP3 inflammasome activation amplifies the inflammation response, promoting pyroptotic cell death. Thus, it may contribute to the onset and progression of CKD, but the mechanism behind inflammasome activation in CKD remains obscure.In this review, we summarized recent findings on the role of the NLRP3 inflammasome in CKD and new strategies targeting the NLRP3 inflammasome.

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.

The acute-to-chronic glycemic ratio correlates with the severity of illness at admission in patients with diabetes experiencing acute ischemic stroke

Acute hyperglycemia is a powerful indicator of the severity of acute ischemic stroke (AIS); however, the relationship between these two factors is not very clear in patients with diabetes. We aimed to retrospectively evaluate data from 335 consecutive patients who experienced AIS from November 2015 to November 2016 to investigate whether a comprehensive assessment of blood glucose levels is a more valuable indicator of the severity of AIS or the presence of acute hyperglycemia in patients with diabetes. We collected demographic data, clinical manifestation information, clinical scores, and laboratory data [including fasting blood glucose and glycated hemoglobin (HbA1c) levels]. We estimated prehospital mean blood glucose concentrations using the following formula [1.59 * HbA1c (%) – 2.59] to calculate the “Acute-to-Chronic Glycemic Ratio” (AC ratio). The AC ratio differed significantly among patients grouped according to the National Institutes of Health Stroke Scale/Score (NIHSS) at admission (admission NIHSS) (p = 0.006). Univariate regression analysis revealed a correlation between the AC ratio and admission NIHSS [standardized β-coefficient (Std. B) = 0.164, p = 0.004]. The adjusted linear regression analysis revealed a correlation between both HbA1c (Std. B = 0.368, p = 0.038) and the AC ratio (Std. B = 0.262, p = 0.022) and admission NIHSS. The AC ratio (Std. B = 0.161, p = 0.012) was related to admission NIHSS in the stepwise variable selection. For an admission NIHHS &gt; 4, the AC ratio (Std. B = 0.186, p = 0.047) was related to admission NIHSS in the stepwise variable selection. The AC ratio (Std. B = 1.163, p = 0.006 and Std. B = 0.565, p = 0.021, respectively) were related to admission NIHSS in both large-artery atherosclerosis (LAA) and small-vessel occlusion (SVO) subgroups. Thus, the AC ratio is related to admission NIHSS in patients with diabetes who experienced AIS and may be a better indicator of severity than acute blood glucose levels.

Plasminogen activator inhibitor 1 and gestational diabetes: the causal relationship

Plasminogen activator inhibitor 1 (PAI-1) also known as serpin E1 or endothelial plasminogen activator inhibitor, is produced from endothelial cells and adipose tissue. PAI-1 inhibits tissue plasminogen activator (tPA) and urokinase (uPA) preventing activation of plasminogen and fibrinolysis. Gestational diabetes mellitus (GDM) is defined as glucose intolerance and hyperglycemia during pregnancy. The underlying mechanism of GDM is due to the reduction of insulin secretion or the development of insulin resistance (IR). Normal PAI-1 is a crucial mediator for maintaining pregnancy, though aberrantly high PAI-1 promotes inflammation and thrombosis with increased risk of pregnancy loss. Increasing PAI-1 level had been shown to be an early feature of cardio-metabolic derangement in women with GDM. As well, GDM is regarded as an independent predictor for increasing PAI-1 levels compared to normal pregnancy. Taken together, GDM seems to be the causal factor in the increase of PAI-1 via induction of IR, hyperglycemia and hypertriglyceridemia. In conclusion, GDM triggers expression and release of PAI-1 which linked with GDM severity due to exaggerated pro-inflammatory and inflammatory cytokines with the development of IR. High PAI-1 levels in GDM may induce hypofibrinolysis and thrombotic complications.

Exosomal miR-17-5p from adipose-derived mesenchymal stem cells inhibits abdominal aortic aneurysm by suppressing TXNIP-NLRP3 inflammasome

Background

Preclinical studies have suggested that adipose-derived mesenchymal stem cells (ADSCs) transplantation can suppress abdominal aortic inflammation and aneurysm expansion through paracrine factors. Yet, the mechanism of action is not fully understood. In the present study, we further examined the function and mechanism of ADSC-derived exosomes (ADSC-exos) and their microRNA-17-5p (miR-17-5p) on the abdominal aortic aneurysm (AAA) progression.

Methods

ADSC-exos were isolated and identified. DiR and PKH67 staining were used to trace ADSC-exo in vivo and in vitro. Raw264.7 cells were applied to perform in vitro experiments, while a murine AAA model induced using angiotensin II (Ang II) was used for in vivo testing. The expression level of miR-17-5p in macrophages and Ang II-treated macrophages after ADSC-exos treatment was determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The target relation between miR-17-5p and thioredoxin-interacting protein (TXNIP) was identified by a dual-luciferase reporter gene assay. Artificial activation and block of experiments of miR-17-5p and TXNIP were conducted to clarify their functions in inflammation during AAA progression. The severity of AAA between groups was assessed by maximal aorta diameter, AAA incidence, survival rate, and histological stainings. Besides, inflammasome-related proteins and macrophage pyroptosis were further evaluated using western blot, RT-qPCR, and enzyme-linked immunosorbent assay (ELISA).

Results

The ADSC-exos were isolated and identified. In vivo testing showed that ADSC-exos were mainly distributed in the liver. Meanwhile, in vitro experiments suggested that ADSC-derived exosomes were taken up by macrophages, while inside, ADSC-exos miR-17-5p decreased a TXNIP induced by Ang II by directly binding to its 3′-untranslated region (3’UTR). Furthermore, overexpression of miR-17-5p enhanced the therapeutic function of ADSC-exos on inflammation during AAA expansion in vivo, while its inhibition reversed this process. Finally, overexpressed TXNIP triggered macrophage pyroptosis and was alleviated by ADSC-derived exosomes in vitro.

Conclusion

ADSC-exos miR-17-5p regulated AAA progression and inflammation via the TXNIP-NLRP3 signaling pathway, thus providing a novel insight in AAA treatment.

Caspase-1: A Promising Target for Preserving Blood–Brain Barrier Integrity in Acute Stroke

The blood–brain barrier (BBB) acts as a physical and biochemical barrier that plays a fundamental role in regulating the blood-to-brain influx of endogenous and exogenous components and maintaining the homeostatic microenvironment of the central nervous system (CNS). Acute stroke leads to BBB disruption, blood substances extravasation into the brain parenchyma, and the consequence of brain edema formation with neurological impairment afterward. Caspase-1, one of the evolutionary conserved families of cysteine proteases, which is upregulated in acute stroke, mainly mediates pyroptosis and compromises BBB integrity via lytic cellular death and inflammatory cytokines release. Nowadays, targeting caspase-1 has been proven to be effective in decreasing the occurrence of hemorrhagic transformation (HT) and in attenuating brain edema and secondary damages during acute stroke. However, the underlying interactions among caspase-1, BBB, and stroke still remain ill-defined. Hence, in this review, we are concerned about the roles of caspase-1 activation and its associated mechanisms in stroke-induced BBB damage, aiming at providing insights into the significance of caspase-1 inhibition on stroke treatment in the near future.

Blood-Brain Barrier Transporters: Opportunities for Therapeutic Development in Ischemic Stroke

Globally, stroke is a leading cause of death and long-term disability. Over the past decades, several efforts have attempted to discover new drugs or repurpose existing therapeutics to promote post-stroke neurological recovery. Preclinical stroke studies have reported successes in identifying novel neuroprotective agents; however, none of these compounds have advanced beyond a phase III clinical trial. One reason for these failures is the lack of consideration of blood-brain barrier (BBB) transport mechanisms that can enable these drugs to achieve efficacious concentrations in ischemic brain tissue. Despite the knowledge that drugs with neuroprotective properties (i.e., statins, memantine, metformin) are substrates for endogenous BBB transporters, preclinical stroke research has not extensively studied the role of transporters in central nervous system (CNS) drug delivery. Here, we review current knowledge on specific BBB uptake transporters (i.e., organic anion transporting polypeptides (OATPs in humans; Oatps in rodents); organic cation transporters (OCTs in humans; Octs in rodents) that can be targeted for improved neuroprotective drug delivery. Additionally, we provide state-of-the-art perspectives on how transporter pharmacology can be integrated into preclinical stroke research. Specifically, we discuss the utility of in vivo stroke models to transporter studies and considerations (i.e., species selection, co-morbid conditions) that will optimize the translational success of stroke pharmacotherapeutic experiments.

Acute Hyperglycemia Exacerbates Hemorrhagic Transformation after Embolic Stroke and Reperfusion with tPA: A Possible Role of TXNIP-NLRP3 Inflammasome

OBJECTIVES

Acute hyperglycemia (HG) exacerbates reperfusion injury after stroke. Our recent studies showed that acute HG upregulates thioredoxin-interacting protein (TXNIP) expression, which in turn induces inflammation and neurovascular damage in a suture model of ischemic stroke. The aim of the present study was to investigate the effect of acute HG on TXNIP-associated neurovascular damage, in a more clinically relevant murine model of embolic stroke and intravenous tissue plasminogen activator (IV-tPA) reperfusion.

MATERIALS AND METHODS

HG was induced in adult male mice, by intraperitoneal injection of 20% glucose. This was followed by embolic middle cerebral artery occlusion (eMCAO), with or without IV-tPA (10 mg/kg) given 3 h post embolization. Brain infarction, edema, hemoglobin content, expression of matrix metalloproteinase (MMP-9), vascular endothelial growth factor A (VEGFA), tight junction proteins (claudin-5, occluding, and zonula occludens-1), TXNIP, and NOD-like receptor protein3 (NLRP3)-inflammasome activation were evaluated at 24 h after eMCAO.

RESULTS

HG alone significantly increased TXNIP in the brain after eMCAO, and this was associated with exacerbated hemorrhagic transformation (HT; as measured by hemoglobin content). IV-tPA in HG conditions showed a trend to decrease infarct volume, but worsened HT after eMCAO, suggesting that HG reduces the therapeutic efficacy of IV-tPA. Further, HG and tPA-reperfusion did not show significant differences in expression of MMP-9, VEGFA, junction proteins, and NLRP3 inflammasome activation between the groups.

CONCLUSION

The current findings suggest a potential role for TXNIP in the occurrence of HT in hyperglycemic conditions following eMCAO. Further studies are needed to understand the precise role of vascular TXNIP on HG/tPA-induced neurovascular damage after stroke.

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.

A Novel Long-Noncoding RNA LncZFAS1 Prevents MPP+-Induced Neuroinflammation Through MIB1 Activation

Parkinson's disease remains one of the leading neurodegenerative diseases in developed countries. Despite well-defined symptomology and pathology, the complexity of Parkinson's disease prevents a full understanding of its etiological mechanism. Mechanistically, α-synuclein misfolding and aggregation appear to be central for disease progression, but mitochondrial dysfunction, dysfunctional protein clearance and ubiquitin/proteasome systems, and neuroinflammation have also been associated with Parkinson's disease. Particularly, neuroinflammation, which was initially thought to be a side effect of Parkinson's disease pathogenesis, has now been recognized as driver of Parkinson's disease exacerbation. Next-generation sequencing has been used to identify a plethora of long noncoding RNAs (lncRNA) with important transcriptional regulatory functions. Moreover, a myriad of lncRNAs are known to be regulators of inflammatory signaling and neurodegenerative diseases, including IL-1β secretion and Parkinson's disease. Here, LncZFAS1 was identified as a regulator of inflammasome activation, and pyroptosis in human neuroblast SH-SY5Y cells following MPP⁺ treatment, a common in vitro Parkinson's disease cell model. Mechanistically, TXNIP ubiquitination through MIB1 E3 ubiquitin ligase regulates NLRP3 inflammasome activation in neuroblasts. In contrast, MPP⁺ activates the NLPR3 inflammasome through miR590-3p upregulation and direct interference with MIB1-dependent TXNIP ubiquitination. LncZFAS overexpression inhibits this entire pathway through direct interference with miR590-3p, exposing a novel research idea regarding the mechanism of Parkinson's disease.

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.

AIM2 deletion enhances blood-brain barrier integrity in experimental ischemic stroke

Aims

Ischemic stroke is a life‐threatening disease with limited therapeutic strategies. Blood‐brain barrier (BBB) disruption is a critical pathological process that contributes to poor outcomes in ischemic stroke. We previously showed that the microglial inhibition of the inflammasome sensor absent in melanoma 2 (AIM2) suppressed the inflammatory response and protected against ischemic stroke. However, whether AIM2 is involved in BBB disruption during cerebral ischemia is unknown.

Methods

Middle cerebral artery occlusion (MCAO) and oxygen‐glucose deprivation/reoxygenation (OGD/R) were used to mimic cerebral ischemia in mice and brain microvascular endothelial cells (HBMECs), respectively. The infarct volume, neurological deficits, and BBB permeability were measured in mice after MCAO. Transendothelial electrical resistance (TEER) and neutrophil adhesion to the HBMEC monolayer were assessed after OGD/R treatment. Western blot and immunofluorescence analyses were conducted to evaluate the expression of related proteins.

Results

AIM2 was shown to be expressed in brain endothelial cells and upregulated after ischemic stroke in the mouse brain. AIM2 deletion reduced the infarct volume, improved neurological and motor functions, and decreased BBB disruption. In vitro, OGD/R significantly increased the protein levels of AIM2 and ICAM‐1 and decreased those of the tight junction (TJ) proteins ZO‐1 and occludin. AIM2 knockdown effectively protected BBB integrity by promoting the expression of TJ proteins and decreasing ICAM‐1 expression and neutrophil adhesion. Mechanistically, AIM2 knockdown reversed the OGD/R‐induced increases in ICAM‐1 expression and STAT3 phosphorylation in brain endothelial cells. Furthermore, treatment with the p‐STAT3 inhibitor AG490 mitigated the effect of AIM2 on BBB breakdown.

Conclusion

Our findings indicated that inhibiting AIM2 preserved the BBB integrity after ischemic stroke, at least partially by modulating STAT3 activation and that AIM2 may be a promising therapeutic target for cerebral ischemic stroke.

Uncoupling Protein 2 Deficiency Enhances NLRP3 Inflammasome Activation Following Hyperglycemia-Induced Exacerbation of Cerebral Ischemia and Reperfusion Damage In Vitro and In Vivo

Mitochondrial uncoupling protein 2 (UCP2) deficiency exacerbates brain damage following cerebral ischemia/reperfusion (I/R). The Nod-like receptor protein-3 (NLRP3) inflammasome also plays a vital role in cerebral I/R damage. However, the effect of UCP2 on NLRP3 inflammasome-mediated hyperglycemia and I/R damage is not clear. In the present study, UCP2-knockout (UCP2-/-) and wild-type (WT) mice were used to establish a model of middle cerebral artery occlusion (MCAO) and reperfusion under normo- and hyperglycemic conditions. HT22 cells were established as a model of oxygen-glucose deprivation and reoxygenation (OGD/R) with high glucose to mimic hyperglycemia and I/R in vitro. HT22 cells were treated with/without different concentrations of the UCP2-specific inhibitor genipin for different periods of time. The results showed that UCP2 deficiency significantly increased histopathological changes and apoptosis after cerebral I/R damage in hyperglycemic mice. Moreover, UCP2 deficiency enhanced NLRP3 inflammasome activation in neurons when cerebral I/R damage was exacerbated by hyperglycemia. Furthermore, UCP2 deficiency enhanced NLRP3 inflammasome activation and reactive oxygen species (ROS) production in HT22 cells under OGD/R and high-glucose conditions. UCP2 deficiency aggravated hyperglycemia-induced exacerbation of cerebral I/R damage. UCP2 deficiency also enhanced NLRP3 inflammasome activation and ROS production in neurons in vitro and in vivo. These findings suggest that UCP2 deficiency enhances NLRP3 inflammasome activation following hyperglycemia-induced exacerbation of cerebral I/R damage in vitro and in vivo. UCP2 may be a potential therapeutic target for hyperglycemia-induced exacerbation of cerebral I/R damage.

Hemorrhagic Transformation in Ischemic Stroke and the Role of Inflammation

Hemorrhagic transformation (HT) is a common complication in patients with acute ischemic stroke. It occurs when peripheral blood extravasates across a disrupted blood brain barrier (BBB) into the brain following ischemic stroke. Preventing HT is important as it worsens stroke outcome and increases mortality. Factors associated with increased risk of HT include stroke severity, reperfusion therapy (thrombolysis and thrombectomy), hypertension, hyperglycemia, and age. Inflammation and the immune system are important contributors to BBB disruption and HT and are associated with many of the risk factors for HT. In this review, we present the relationship of inflammation and immune activation to HT in the context of reperfusion therapy, hypertension, hyperglycemia, and age. Differences in inflammatory pathways relating to HT are discussed. The role of inflammation to stratify the risk of HT and therapies targeting the immune system to reduce the risk of HT are presented.

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.

Peroxynitrite activates NLRP3 inflammasome and contributes to hemorrhagic transformation and poor outcome in ischemic stroke with hyperglycemia

This study aims to test the hypothesis that peroxynitrite-mediated inflammasome activation could be a crucial player in the blood-brain barrier (BBB) disruption, hemorrhagic transformation (HT) and poor outcome in ischemic stroke with hyperglycemia. We used an experimental rat stroke model subjected to 90 min of middle cerebral artery occlusion plus 24 h or 7 days of reperfusion with or without acute hyperglycemia. We detected the production of peroxynitrite, the expression of NADPH oxidase, iNOS, MMPs and NLRP3 inflammasome in the ischemic brains, and evaluated infarct volume, brain edema, HT, neurological deficit score and survival rates. Our results show that: (1) Hyperglycemia increased the expression of NADPH oxidase subunits p47phox and p67phox, and iNOS, and the production of peroxynitrite. (2) Hyperglycemia increased infarct volume, aggravated the BBB hyperpermeability, induced brain edema and HT, and worsened neurological outcomes. These brain damages and poor outcome were reversed by the treatments of FeTmPyP (a representative peroxynitrite decomposition catalyst, PDC), peroxynitrite scavenger uric acid, and iNOS inhibitor 1400W. Furthermore, the activations of MMPs and NLRP3 inflammasome including pro/active-caspase-1 and IL-1β were inhibited both PDC and 1400W, indicating the roles of peroxynitrite in the inductions of MMPs and NLRP3 inflammasome in the ischemic brains under hyperglycemia. (3) NLRP3 inflammasome inhibitor MCC950, caspase-1 inhibitor VX-765 and IL-1β inhibitor diacerein attenuated brain edema, minimized hemorrhagic transformation and improved neurological outcome, demonstrating the roles of NLRP3 inflammasome in the hyperglycemia-mediated HT and poor outcome in the ischemic stroke rats with acute hyperglycemia. In conclusion, peroxynitrite could mediate activations of MMPs and NLRP3 inflammasome, aggravate the BBB damage and HT, and induce poor outcome in ischemic stroke with hyperglycemia. Therefore, targeting peroxynitrite-mediated NLRP3 inflammasome could be a promising strategy for ischemic stroke with hyperglycemia.

The Emerging Role of TXNIP in Ischemic and Cardiovascular Diseases; A Novel Marker and Therapeutic Target

Thioredoxin interacting protein (TXNIP) is a metabolism- oxidative- and inflammation-related marker induced in cardiovascular diseases and is believed to represent a possible link between metabolism and cellular redox status. TXNIP is a potential biomarker in cardiovascular and ischemic diseases but also a novel identified target for preventive and curative medicine. The goal of this review is to focus on the novelties concerning TXNIP. After an overview in TXNIP involvement in oxidative stress, inflammation and metabolism, the remainder of this review presents the clues used to define TXNIP as a new marker at the genetic, blood, or ischemic site level in the context of cardiovascular and ischemic diseases.

Strategies to prevent hemorrhagic transformation after reperfusion therapies for acute ischemic stroke: A literature review

BACKGROUND

Reperfusion therapies by tissue plasminogen activator (tPA) and mechanical thrombectomy (MT) have ushered in a new era in the treatment of acute ischemic stroke (AIS). However, reperfusion therapy-related HT remains an enigma.

AIM

To provide a comprehensive review focused on emerging concepts of stroke and therapeutic strategies, including the use of protective agents to prevent HT after reperfusion therapies for AIS.

METHODS

A literature review was performed using PubMed and the ClinicalTrials.gov database.

RESULTS

Risk of HT increases with delayed initiation of tPA treatment, higher baseline glucose level, age, stroke severity, episode of transient ischemic attack within 7 days of stroke onset, and hypertension. At a molecular level, HT that develops after thrombolysis is thought to be caused by reactive oxygen species, inflammation, remodeling factor-mediated effects, and tPA toxicity. Modulation of these pathophysiological mechanisms could be a therapeutic strategy to prevent HT after tPA treatment. Clinical mechanisms underlying HT after MT are thought to involve smoking, a low Alberta Stroke Program Early CT Score, use of general anesthesia, unfavorable collaterals, and thromboembolic migration. However, the molecular mechanisms are yet to be fully investigated. Clinical trials with MT and protective agents have also been planned and good outcomes are expected.

CONCLUSION

To fully utilize the easily accessible drug-tPA-and the high recanalization rate of MT, it is important to reduce bleeding complications after recanalization. A future study direction could be to investigate the recovery of neurological function by combining reperfusion therapies with cell therapies and/or use of pleiotropic protective agents.

Melatonin exerts neuroprotective effects by inhibiting neuronal pyroptosis and autophagy in STZ-induced diabetic mice

Diabetes mellitus (DM) patients are at a higher risk of developing brain injury characterized by neuronal death. Melatonin, a hormone produced by the pineal gland, exerts neuroprotective effects against brain damage. However, the effect of melatonin on diabetes-induced brain injury has not been elucidated. This study was to evaluate the role of melatonin against neuronal death in DM and to elucidate the underlying mechanisms. Herein, we found that melatonin administration significantly alleviated the neuronal death in both streptozotocin (STZ)-induced diabetic mice and high glucose (HG)-treated neuronal cells. Melatonin inhibited neuronal pyroptosis and excessive autophagy, as evidenced by decreased levels of NLRP3, cleaved caspase-1, GSDMD-N, IL-1β, LC3, Beclin1, and ATG12 both in vivo and in vitro. MicroRNA-214-3p (miR-214-3p) was decreased in DM mice and HG-treated cells, and such a downregulation was corrected by melatonin, which was accompanied by repression of caspase-1 and ATG12. Furthermore, downregulation of miR-214-3p abrogated the anti-pyroptotic and anti-autophagic actions of melatonin in vitro. Our results indicate that melatonin exhibits a neuroprotective effect by inhibiting neuronal pyroptosis and excessive autophagy through modulating the miR-214-3p/caspase-1 and miR-214-3p/ATG12 axes, respectively, and it might be a potential agent for the treatment of brain damage in the setting of DM.

Neuroinflammation Mediated by NLRP3 Inflammasome After Intracerebral Hemorrhage and Potential Therapeutic Targets

Intracerebral hemorrhage (ICH) is the most fatal subtype of stroke; there is still a lack of effective treatment. Microglia are a major component of the innate immune system, and they respond to acute brain injury by activating and forming classic M1-like (pro-inflammatory) or alternative M2-like (anti-inflammatory) phenotype. The existence of the polarization indicates that the role of microglia in disease's progression and recovery after ICH is still unclear, perhaps involving microglial secretion of anti-inflammatory or pro-inflammatory cytokines and chemokines. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome is considered to be the main participant in neuroinflammation. Recent evidence has shown that NLRP3 inflammasome can be activated after ICH, resulting in inflammatory cascade reactions and aggravating brain injury. Furthermore, previous studies have reported that NLRP3 inflammasome is mainly present in microglia, so we speculate that its activation may be strongly associated with microglial polarization. Many scholars have investigated the role of brain injury caused by NLRP3 inflammasome after ICH, but the precise operating mechanisms remain uncertain. This review summarized the activation mechanism of NLRP3 inflammasome after ICH and the possible mechanism of NLRP3 inflammasome promoting neuroinflammation and aggravating nerve injury and discussed the relevant potential therapeutic targets.

Effects of β-Adrenergic Blockade on Metabolic and Inflammatory Responses in a Rat Model of Ischemic Stroke

Ischemic stroke provokes an inflammatory response concurrent with both sympathetic nervous system activation and hyperglycemia. Currently, their crosstalk and consequences in stroke outcomes are of clinical attraction. We have provided experimental evidence showing the suppressive effects of the nonselective β-adrenoreceptor antagonist propranolol on hyperglycemia, inflammation, and brain injury in a rat model experiencing cerebral ischemia. Pretreatment with propranolol protected against postischemic brain infarction, edema, and apoptosis. The neuroprotection caused by propranolol was accompanied by a reduction in fasting glucose, fasting insulin, glucose tolerance impairment, plasma C-reactive protein, plasma free fatty acids, plasma corticosterone, brain oxidative stress, and brain inflammation. Pretreatment with insulin alleviated-while glucose augmented-postischemic brain injury and inflammation. Additionally, the impairment of insulin signaling in the gastrocnemius muscles was noted in rats with cerebral ischemia, with propranolol improving the impairment by reducing oxidative stress and tumor necrosis factor-α signaling. The anti-inflammatory effects of propranolol were further demonstrated in isoproterenol-stimulated BV2 and RAW264.7 cells through its ability to decrease cytokine production. Despite their potential benefits, stroke-associated hyperglycemia and inflammation are commonly linked with harmful consequences. Our findings provide new insight into the anti-inflammatory, neuroprotective, and hypoglycemic mechanisms of propranolol in combating neurodegenerative diseases, such as stroke.