Activation of c-Jun N-terminal kinase and p38 after cerebral ischemia upregulates cerebral sodium-glucose transporter type 1

Increased serum SGLT2 and its potential diagnostic and prognostic value in patients with acute ischemic stroke

BACKGROUND

Recently acquired data suggests that sodium-glucose cotransporter-2 (SGLT2) may be a therapeutic target for cerebral ischemia. The specific impact of SGLT2 in acute ischemic stroke (AIS) remains unknown. We aimed to explore the levels of SGLT2 in AIS patients and its association with functional prognosis.

METHODS

In this study, 132 AIS patients and 44 healthy controls were recruited prospectively to determine serum SGLT2 levels. Logistic regression analysis was employed to assess the association between serum SGLT2 level and stroke risk as well as 3-month outcome. Receiver operating characteristic (ROC) curves were utilized to evaluate predictive values for blood biomarkers.

RESULTS

Serum SGLT2 levels were significantly higher (P =.000) in AIS patients (47.1 (interquartile range [IQR]: 42.4-50.9) ng/mL) than healthy controls (35.7 (IQR: 28.6-39.5) ng/mL). The optimal SGLT2 cutoff point for diagnosing AIS was 39.55 ng/mL, with a sensitivity of 90.2 % and specificity of 77.3 %. Serum levels of SGLT2 were negatively correlated with the onset time of AIS (linear fit R2 = 0.056, P =.006), but were not associated with National Institutes of Health Stroke Scale (NIHSS) scores (r = 0.007, P >.05) and lesion volume (r = -0.151, P >.05). SGLT2 was not remarkably different between patients with unfavorable and favorable outcomes (46.7 (IQR: 41.9-49.6) ng/mL vs 47.6 (IQR: 42.5-51.9) ng/mL; P =.321).

CONCLUSIONS

The serum SGLT2 concentration may be a potential biomarker for the diagnosis of AIS. However, it does not exhibit any association with disease severity or functional prognosis.

Role of Qufeng Tongqiao Prescription in the protection of cerebral ischemia and associated molecular network mechanism

To explore the of Qufeng Tongqiao Prescription in the treatment of cerebral ischemia-reperfusion (CIR) and associated molecular network mechanism. Venny diagram, gene ontology (GO) and kyoto encyclopedia of genes and genomes (KEGG) analysis, protein-protein interaction (PPI), hub genes mining, molecular docking, combined with animal experiments and Nissl stain were performed to determine the molecular network mechanism of Qufeng Tongqiao Prescription for CIR treatment. Fifty three intersecting genes between Qufeng Tongqiao Prescription and cerebral ischemia reperfusion were acquired from Venny analysis. GO analysis showed that the main biological process (BP) was response to lipopolysaccharide, and the main cell localization (CC) process was membrane raft, while the most important molecular function (MF) process is Cytokine receptor binding. Moreover, AGE-RAGE signaling pathway in diabetic complications is the most important signaling pathway in KEGG pathway. Through molecular docking, it was found that Astragalus membranaceus was docked with MAPK14, IL4, FOS, IL6, and JUN; pueraria membranaceus was directly docked with JUN and IL4; Acorus acorus was linked to JUN and MAPK14; Ganoderma ganoderma and human were involved in JUN docking, and Ligusticum chuanqi and pueraria could not be docked with MAPK14, respectively. The results of animal experiments showed that Qufeng Tongqiao Prescription significantly improved behavioral performance and reduced the number of neuronal deaths in rats subjected to CIR, and molecular mechanisms are associated with FOS, IL-6, IL4, JUN, and MAPK14, of there, IL-6, as a vital candidator, which has been confirmed by immunostaining detection. Together, Qufeng Tongqiao Prescription has positive therapeutic effect on CIR, and the underlying mechanism is involved MAPK14, FOS, IL4, and JUN network, while IL-6 may be as a vital target.

Canagliflozin, an Inhibitor of the Na+-Coupled D-Glucose Cotransporter, SGLT2, Inhibits Astrocyte Swelling and Brain Swelling in Cerebral Ischemia

Brain swelling is a major cause of death and disability in ischemic stroke. Drugs of the gliflozin class, which target the Na+-coupled D-glucose cotransporter, SGLT2, are approved for type 2 diabetes mellitus (T2DM) and may be beneficial in other conditions, but data in cerebral ischemia are limited. We studied murine models of cerebral ischemia with middle cerebral artery occlusion/reperfusion (MCAo/R). Slc5a2/SGLT2 mRNA and protein were upregulated de novo in astrocytes. Live cell imaging of brain slices from mice following MCAo/R showed that astrocytes responded to modest increases in D-glucose by increasing intracellular Na+ and cell volume (cytotoxic edema), both of which were inhibited by the SGLT2 inhibitor, canagliflozin. The effect of canagliflozin was studied in three mouse models of stroke: non-diabetic and T2DM mice with a moderate ischemic insult (MCAo/R, 1/24 h) and non-diabetic mice with a severe ischemic insult (MCAo/R, 2/24 h). Canagliflozin reduced infarct volumes in models with moderate but not severe ischemic insults. However, canagliflozin significantly reduced hemispheric swelling and improved neurological function in all models tested. The ability of canagliflozin to reduce brain swelling regardless of an effect on infarct size has important translational implications, especially in large ischemic strokes.

Therapeutic implication of Sonic Hedgehog as a potential modulator in ischemic injury

Sonic Hedgehog (SHh) is a homology protein that is involved in the modeling and development of embryonic tissues. As SHh plays both protective and harmful roles in ischemia, any disruption in the transduction and regulation of the SHh signaling pathway causes ischemia to worsen. The SHh signal activation occurs when SHh binds to the receptor complex of Ptc-mediated Smoothened (Smo) (Ptc-smo), which initiates the downstream signaling cascade. This article will shed light on how pharmacological modifications to the SHh signaling pathway transduction mechanism alter ischemic conditions via canonical and non-canonical pathways by activating certain downstream signaling cascades with respect to protein kinase pathways, angiogenic cytokines, inflammatory mediators, oxidative parameters, and apoptotic pathways. The canonical pathway includes direct activation of interleukins (ILs), angiogenic cytokines like hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and hypoxia-inducible factor alpha (HIF-), which modulate ischemia. The non-canonical pathway includes indirect activation of certain pathways like mTOR, PI3K/Akt, MAPK, RhoA/ROCK, Wnt/-catenin, NOTCH, Forkhead box protein (FOXF), Toll-like receptors (TLR), oxidative parameters such as GSH, SOD, and CAT, and some apoptotic parameters such as Bcl2. This review provides comprehensive insights that contribute to our knowledge of how SHh impacts the progression and outcomes of ischemic injuries.

Neuroprotective effects of an in vitro BBB permeable phenoxythiophene sulfonamide small molecule in glutamate-induced oxidative injury

Reactive oxygen species (ROS) play a central role in oxidative stress-associated neuronal cell death during ischemia. Further investigation into the inhibition of excessive ROS generation post-stroke is urgently required for the treatment of ischemic stroke. In the present study, the neuroprotective properties of the blood-brain barrier (BBB) penetrant B355227 were investigated. B355227 is a chemical analogue of B355252, and the role of the phenoxythiophene sulfonamide compound B355227 was further investigated in a glutamate-induced oxidative injury model. An in vitro model of the BBB was established in the immortalized mouse brain capillary endothelial cell line, bEnd.3. Formation of barrier in Transwell inserts was confirmed using EVOM resistance meter and Caffeine, Imatinib and Axitinib were used to validate the efficacy of the model. The validated BBB assay in combination with high performance liquid chromatography were used to analyse and verify the permeability of B355227 through the barrier. The integrity of the cell junctions after the BBB assays were confirmed using immunofluorescence to visualize the expression of the barrier junction protein zonula occludens-1. Cell survival was measured with Resazurin, a redox indicator dye, in HT22, a hippocampal neuronal cell treated with 5 mM glutamate or co-treated with the B355227 recovered from the BBB permeability experiment. Changes in glutathione levels were detected using a glutathione detection kit, while analyses of ROS, calcium (Ca2+), and mitochondrial membrane potential (MMP) were accomplished with the fluorescent dyes 2',7'-dichlorofluorescein diacetate, Fura-2 AM and MitoTracker Red dyes, respectively. Immunoblotting was also performed to detect the expression and activation of Erk1/2, p-38, JNK, Bax and Bcl-2. The results of the present study demonstrated that B355227 crossed the BBB in vitro and protected HT22 from oxidative injury induced by glutamate exposure. Treatment of cells with B355227 blocked the glutamate-dependent depletion of intracellular glutathione and significantly reduced ROS production. Increased Ca2+ influx and subsequent collapse of the MMP was attenuated by B355227. Furthermore, the results of the present study demonstrated that B355227 protected against oxidative stress via the MAPK pathway, by increasing the activation of Erk1/2, JNK and P38, and restoring anti-apoptotic Bcl-2. Collectively, the results of the present study indicate that B355227 has potent antioxidant and neuroprotective attributes in glutamate-induced neuronal cell death. Further investigation into the role of B355227 in the modulation of glutamate-dependent oxidative stress is required.

Exploration of the mechanism of luteolin against ischemic stroke based on network pharmacology, molecular docking and experimental verification

Stroke is a leading cause of morbidity and mortality worldwide. As the most common type of stroke cases, treatment effectiveness is still limited despite intensive research. Recently, traditional Chinese medicine has attracted attention because of potential benefits for stroke treatment. Among these, luteolin, a natural plant flavonoid compound, offers neuroprotection following against ischemic stroke, although the specific mechanisms are unknown. Here we used network pharmacology, molecular docking, and experimental verification to explore the mechanisms whereby luteolin can benefit stroke recovery. The pharmacological and molecular properties of luteolin were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. The potential targets of luteolin and ischemic stroke were collected from interrogating public databases. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed by Funrich and Database for Annotation, Visualization and Integrated Discovery respectively, a luteolin-target-pathway network constructed using Cytoscape, Autodock vina was used for molecular docking simulation with Discovery Studio was used to visualize and analyze the docked conformations. Lastly, we employed an in vitro model of stroke injury to evaluate the effects of luteolin on cell survival and expression of the putative targets. From 95 candidate luteolin target genes, our analysis identified six core targets . KEGG analysis of the candidate targets identified that luteolin provides therapeutic effects on stroke through TNF signaling and other pathways. Our experimental analyses confirmed the conclusions analyzed above. In summary, the molecular and pharmacological mechanisms of luteolin against stroke are indicated in our study from a systematic perspective.

Mizagliflozin, a selective SGLT1 inhibitor, improves vascular cognitive impairment in a mouse model of small vessel disease

Previously, we showed that sodium/glucose cotransporter 1 (SGLT1) participates in vascular cognitive impairment in small vessel disease. We hypothesized that SGLT1 inhibitors can improve the small vessel disease induced-vascular cognitive impairment. We examined the effects of mizagliflozin, a selective SGLT1 inhibitor, and phlorizin, a non-selective SGLT inhibitor, on vascular cognitive impairment in a mouse model of small vessel disease. Small vessel disease was created using a mouse model of asymmetric common carotid artery surgery (ACAS). Two and/or 4 weeks after ACAS, all experiments were performed. Cerebral blood flow (CBF) was decreased in ACAS compared with sham-operated mice. Phlorizin but not mizagliflozin reversed the decreased CBF of ACAS mice. Both mizagliflozin and phlorizin reversed the ACAS-induced decrease in the latency to fall in a wire hang test of ACAS mice. Moreover, they reversed the ACAS-induced longer escape latencies in the Morris water maze test of ACAS mice. ACAS increased SGLT1 and proinflammatory cytokine gene expressions in mouse brains and phlorizin but not mizagliflozin normalized all gene expressions in ACAS mice. Hematoxylin/eosin staining demonstrated that they inhibited pyknotic cell death in the ACAS mouse hippocampus. In PC12HS cells, IL-1β increased SGLT1 expression and decreased survival rates of cells. Both mizagliflozin and phlorizin increased the survival rates of IL-1β-treated PC12HS cells. These results suggest that mizagliflozin and phlorizin can improve vascular cognitive impairment through the inhibition of neural SGLT1 and phlorizin also does so through the improvement of CBF in a mouse model of small vessel disease.

SGLT1 Knockdown Attenuates Cardiac Fibroblast Activation in Diabetic Cardiac Fibrosis

Background: Cardiac fibroblast (CF) activation is a hallmark feature of cardiac fibrosis in diabetic cardiomyopathy (DCM). Inhibition of the sodium-dependent glucose transporter 1 (SGLT1) attenuates cardiomyocyte apoptosis and delays the development of DCM. However, the role of SGLT1 in CF activation remains unclear.

Methods: A rat model of DCM was established and treated with si‐SGLT1 to examine cardiac fibrosis. In addition, in vitro experiments were conducted to verify the regulatory role of SGLT1 in proliferation and collagen secretion in high-glucose– (HG–) treated CFs.

Results: SGLT1 was found to be upregulated in diabetic cardiac tissues and HG-induced CFs. HG stimulation resulted in increased proliferation and migration, increased the expression of transforming growth factor-β1 and collagen I and collagen III, and increased phosphorylation of p38 mitogen-activated protein kinase and extracellular signal-regulated kinase (ERK) 1/2. These trends in HG-treated CFs were significantly reversed by si-SGLT1. Moreover, the overexpression of SGLT1 promoted CF proliferation and collagen synthesis and increased phosphorylation of p38 mitogen-activated protein kinase and ERK1/2. SGLT1 silencing significantly alleviated cardiac fibrosis, but had no effect on cardiac hypertrophy in diabetic hearts.

Conclusion: These findings provide new information on the role of SGLT1 in CF activation, suggesting a novel therapeutic strategy for the treatment of DCM fibrosis.

Mechanism underlying treatment of ischemic stroke using acupuncture: transmission and regulation

The inflammatory response after cerebral ischemia/reperfusion is an important cause of neurological damage and repair. After cerebral ischemia/reperfusion, microglia are activated, and a large number of circulating inflammatory cells infiltrate the affected area. This leads to the secretion of inflammatory mediators and an inflammatory cascade that eventually causes secondary brain damage, including neuron necrosis, blood-brain barrier destruction, cerebral edema, and an oxidative stress response. Activation of inflammatory signaling pathways plays a key role in the pathological process of ischemic stroke. Increasing evidence suggests that acupuncture can reduce the inflammatory response after cerebral ischemia/reperfusion and promote repair of the injured nervous system. Acupuncture can not only inhibit the activation and infiltration of inflammatory cells, but can also regulate the expression of inflammation-related cytokines, balance the effects of pro-inflammatory and anti-inflammatory factors, and interfere with inflammatory signaling pathways. Therefore, it is important to study the transmission and regulatory mechanism of inflammatory signaling pathways after acupuncture treatment for cerebral ischemia/reperfusion injury to provide a theoretical basis for clinical treatment of this type of injury using acupuncture. Our review summarizes the overall conditions of inflammatory cells, mediators, and pathways after cerebral ischemia/reperfusion, and discusses the possible synergistic intervention of acupuncture in the inflammatory signaling pathway network to provide a foundation to explore the multiple molecular mechanisms by which acupuncture promotes nerve function restoration.

Involvement of descending pain control system regulated by orexin receptor signaling in the induction of central post-stroke pain in mice

Central post-stroke pain (CPSP) is a type of neuropathic pain for which the mechanism and relevant drug pathways remain unknown. Recently, it was reported that intracerebroventricular (ICV) administration of orexin-A suppresses pain and ischemia. In this study, we tested the role of orexin-A in CPSP induction in mice. Male ddY mice were subjected to 30 min of bilateral carotid artery occlusion (BCAO). CPSP was assessed by von Frey test. Colocalization of orexin 1 receptor (OX1R) with various neuron markers were determined by double-immunofluorescence. The hindpaw withdrawal responses to mechanical stimuli were significantly increased 3 days post-BCAO compared with those of sham groups. ICV injection of orexin-A dose-dependently suppressed BCAO-induced mechanical allodynia. These effects were inhibited by pre-treatment with SB334867 (an OX1R antagonist; ICV injection), yohimbine (a noradrenaline α₂ receptor antagonist; intrathecal (IT) injection), and WAY100635 (a serotonin 5-HT_1A receptor antagonist; IT injection), but not TCS OX2 29 (an OX2R antagonist; ICV injection). OX1R colocalized with TH (a noradrenergic neuron marker) and TPH (a serotonergic neuron marker) in the locus ceruleus (LC) and the rostral ventromedial medulla (RVM), respectively. The number of c-Fos positive cells in the LC and the RVM of BCAO mice was increased at 90 min after ICV injection of orexin-A compared to saline group. These results indicate that orexin-A/OX1R signaling plays an important role through activation of the descending pain control system in the induction of CPSP in mice.

Delayed exposure to environmental enrichment improves functional outcome after stroke

Stroke is one of the leading causes of long-term disabilities worldwide. Although exposure to an enriched environment (EE) initiated in the acute phase after stroke has neuroprotective effects and improves stroke outcome, it remains unclear whether EE has positive effects when started in a delayed time frame. Here we show that exposure to EE in the delayed phase notably ameliorates the ischemia-induced impairments in neurological functions and spatial learning and memory. In addition, delayed EE exposure after stroke significantly promotes the survival and neuronal fate choice of hippocampal newborn cells, increases synaptic density of hippocampal mature neurons, and enhances the migration of subventricular zone (SVZ)-derived cells towards the ischemic striatum. Histone deacetylase 2 (HDAC2), synapse-associated proteins and brain-derived neurotrophic factor (BDNF) may respectively mediate these roles of delayed EE. Our findings provide the suggestion that exposure to EE initiated in the delayed phase after stroke promotes plastic changes via affecting neurogenesis, synaptogenesis and neuronal migration, and thus improves stroke outcome. Because EE initiated earlier than 24 h is clinically feasible, our work could be introduced into clinical studies of stroke directly and may provide stroke survivors with a new strategy for their functional recovery.

Effect of ERK inhibitor on corneal neovascularization induced by alkali burn in mice and its mechanism

The objective of this study is to explore the effect of extracellular signal–regulated kinase (ERK) inhibitors on corneal neovascularization induced by alkali burn in mice and its mechanism. A total of 30 standard diet (SD) healthy mice were divided into normal group, alkali burn group, and inhibitor group. Normal group was not treated. Alkali burn group and inhibitor group were used to establish corneal neovascularization model induced by alkali burn. After successful modeling, ERK inhibitor was used to intervene in inhibitor group, and saline of equal volume was used in normal group and alkali burn group. The area of corneal neovascularization was calculated and the expression of vascular endothelial growth factor (VEGF), c-Fos, c-Jun, ERK1/2, and p-ERK1/2 protein in cornea tissue of three groups of mice was detected. The relative expression of vascular area, length, VEGF, c-Fos, c-Jun, ERK1/2, and p-ERK1/2 protein in cornea tissue of mice in alkali burn group was significantly higher than that in normal group and inhibitor group. The relative expression of vascular area, length, VEGF, c-Fos, c-Jun, ERK1/2, and p-ERK1/2 protein in cornea tissue of mice in inhibitor group was higher than that in normal group, and the expression level of PEDF was lower than that in normal group ( P < 0.05). ERK inhibitors inhibit the formation of corneal neovascularization by inhibiting the expression of VEGF, c-Fos, and c-Jun proteins through the action of ERK signaling pathway.

Sodium-glucose transporter as a novel therapeutic target in disease

Glucose is the primary energy fuel of life. A glucose transporter, the sodium-glucose transporter (SGLT), is receiving attention as a novel therapeutic target in disease. This review summarizes the physiological role of SGLT in cerebral ischemia, cancer, cardiac disease, and intestinal ischemia, which has encouraged analysis of SGLT function. In cerebral ischemia and cardiomyopathy, SGLT-1 is involved in worsening of the injury. In addition, SGLT-1 promotes the development of cancer. On the other hand, SGLT-1 has a protective effect against cardiac and intestinal ischemia. Interestingly, SGLT-1 expression levels are increased in some diseased tissue, such as in cerebral ischemia and cancer. This suggests that SGLT-1 may have an important role in many diseases. This review discusses the potential of SGLT as a target for novel therapeutic agents.