Understanding the Connection Between Common Stroke Comorbidities, Their Associated Inflammation, and the Course of the Cerebral Ischemia/Reperfusion Cascade

Sevoflurane postconditioning ameliorates cerebral ischemia-reperfusion injury in rats via TLR4/MyD88/TRAF6 signaling pathway

To determine whether sevoflurane postconditioning protects against cerebral ischemia reperfusion (I/R) injury and its potential mechanism, we employed bioinformatic analysis, neurological assessments, and western blot analysis, as well as triphenyl tetrazolium chloride, hematoxylin and eosin, Nissl, and immunofluorescence staining. We identified 103 differentially expressed genes induced by cerebral I/R, including 75 upregulated genes and 28 downregulated genes enriched for certain biological processes (involving regulation of inflammatory responses, cellular responses to interleukin 1, and chemokine activity) and signaling pathways (such as transcriptional misregulation in cancer, interleukin-17 signaling, rheumatoid arthritis, MAPK signaling, and Toll-like receptor signaling). As a typical path in Toll-like receptor signaling pathway, in the current study, we investigated the protective effect of sevoflurane postconditioning in cerebral I/R rats and further explore the role of TLR4/MyD88/TRAF6 signaling pathway in it. The results showed cerebral I/R-induced neurological deficits were comparatively less severe following sevoflurane postconditioning. In addition, TLR4/MyD88/TRAF6 signaling pathway-related proteins and neuropathic damage were ameliorated in aged rats following sevoflurane postconditioning, while the TLR4 agonist lipopolysaccharide aggravated these changes. Together, these findings suggest that sevoflurane postconditioning ameliorates cerebral I/R injury by a mechanism involving inhibition of the TLR4/MyD88/TRAF6 signaling pathway to suppress neuroinflammatory responses.

TJ-M2010-5, a novel CNS drug candidate, attenuates acute cerebral ischemia-reperfusion injury through the MyD88/NF-κB and ERK pathway

Background: Cerebral ischemia-reperfusion injury (CIRI) inevitably occurs after vascular recanalization treatment for ischemic stroke. The accompanying inflammatory cascades have a major impact on outcome and regeneration after ischemic stroke. Evidences have demonstrated that TLR/MyD88/NF-κB signaling contributes to CIRI. This study aimed to investigate the druggability of MyD88 in the central nervous system (CNS) and the neuroprotective and anti-neuroinflammatory effects of the MyD88 inhibitor TJ-M2010-5 on CIRI. Methods: A middle cerebral artery occlusion (MCAO) model was used to simulate CIRI in mice. BV-2 cells were stimulated with oxygen glucose deprivation/reoxygenation (OGD/R) or lipopolysaccharide, and SH-SY5Y cells were induced by OGD/R in vitro. Neurological deficit scores and cerebral infarction volumes were evaluated. Immunofluorescence staining was performed to measure neuronal damage and apoptosis in the brain. The anti-neuroinflammatory effect of TJ-M2010-5 was evaluated by analyzing the expression of inflammatory cytokines, activation of microglia, and infiltration of peripheral myeloid cells. The expression of proteins of the MyD88/NF-κB and ERK pathway was detected by Simple Western. The concentrations of TJ-M2010-5 in the blood and brain were analyzed by liquid chromatography-mass spectrometry. Results: The cerebral infarction volume decreased in mice treated with TJ-M2010-5, with the most prominent decrease being approximately 80% of the original infarction volume. Neuronal loss and apoptosis were reduced following TJ-M2010-5 treatment. TJ-M2010-5 inhibited the infiltration of peripheral myeloid cells and the activation of microglia. TJ-M2010-5 also downregulated the expression of inflammatory cytokines and inhibited the MyD88/NF-κB and ERK pathway. Furthermore, TJ-M2010-5 showed good blood-brain barrier permeability and no neurotoxicity. Conclusion: TJ-M2010-5 has an excellent therapeutic effect on CIRI as a novel CNS drug candidate by inhibiting excessive neuroinflammatory responses.

Diagnostic model constructed by nine inflammation-related genes for diagnosing ischemic stroke and reflecting the condition of immune-related cells

Background

Ischemic cerebral infarction is the most common type of stroke with high rates of mortality, disability, and recurrence. However, the known diagnostic biomarkers and therapeutic targets for ischemic stroke (IS) are limited. In the current study, we aimed to identify novel inflammation-related biomarkers for IS using machine learning analysis and to explore their relationship with the levels of immune-related cells in whole blood samples.

Methods

Gene expression profiles of healthy controls and patients with IS were download from the Gene Expression Omnibus. Analysis of differentially expressed genes (DEGs) was performed in healthy controls and patients with IS. Single-sample gene set enrichment analysis was performed to calculate inflammation scores, and weighted gene co-expression network analysis was used to analyze genes in significant modules associated with inflammation scores. Key DEGs in significant modules were then analyzed using LASSO regression analysis for constructing a diagnostic model. The effectiveness and specificity of the diagnostic model was verified in healthy controls and patients with IS and with cerebral hemorrhage (CH) using qRT-PCR. The relationship between diagnostic score and the levels of immune-related cells in whole blood were analyzed using Pearson correlations.

Results

A total of 831 DEGs were identified. Both chronic and acute inflammation scores were higher in patients with IS, while 54 DEGs were also clustered in the gene modules associated with chronic and acute inflammation scores. Among them, a total of 9 genes were selected to construct a diagnostic model. Interestingly, RT-qPCR showed that the diagnostic model had better diagnostic value for IS but not for CH. The levels of lymphocytes were lower in blood of patients with IS, while the levels of monocytes and neutrophils were increased. The diagnostic score of the model was negatively associated with the levels of lymphocytes and positively associated with levels of monocytes and neutrophils.

Conclusions

Taken together, the diagnostic model constructed using the inflammation-related genes TNFSF10, ID1, PAQR8, OSR2, PDK4, PEX11B, TNIP1, FFAR2, and JUN exhibited high and specific diagnostic value for IS and reflected the condition of lymphocytes, monocytes, and neutrophils in the blood. The diagnostic model may contribute to the diagnosis of IS.

Neuroprotective effects of nobiletin on cerebral ischemia/reperfusion injury rats by inhibiting Rho/ROCK signaling pathway

Background

Nobiletin (NOB), an active natural flavonoid component of citrus, is used in Traditional Chinese Medicine for its anti-inflammatory activity, but its efficacy in cerebral ischemia/reperfusion (I/R) injury remains unclear.

Methods

In a middle cerebral artery occlusion (MCAO) rat model, MCAO rats were administered (Sham group and MCAO model group treated with an equal volume of solvent, NOB group treated with 10 or 20 mg/kg NOB) once a day for 7 days before cerebral ischemia and again after reperfusion, 2,3,5-triphenyltetrazolium chloride (TTC) staining was applied to assess the infarct area. Neurological function was evaluated by the modified neurological severity score and Morris water maze. The levels of inflammatory factors, interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α), were examined by enzyme-linked immunosorbent assay (ELISA). Histopathological staining evaluated neuron apoptosis in brain tissue. In an oxygen-glucose deprivation PC12 cell (OGD PC12) model, the proliferation, migration and apoptosis of OGD PC12 cells were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and cell migration assays and flow cytometry. The gene and protein expression levels of Ras homolog gene family, member A (Rho A), ras-related C3 botulinum toxin substrate 1 (Rac 1), Rho-associated kinase 1 (ROCK 1), ROCK 2 in the Rho/ROCK pathway were measured by Real-time PCR (RT-PCR), immunohistochemistry and western blot.

Results

In rats with cerebral I/R injury, NOB significantly decreased the infarcted area, neuron apoptosis in brain tissue and expressions of IL-6, IL-1β, and TNF-α. It also improved neurological deficits in brain tissue and enhanced learning and memory ability. Further, NOB had a protective effect on OGD PC12 cells, increasing proliferation and migration and decreasing apoptosis. The expressions of Rho A, Rac 1, ROCK 1 and ROCK 2 were high in cerebral I/R injury rats, but were downregulated by NOB in I/R injury rats' brain tissue and OGD PC12 cells.

Conclusions

Nobiletin had a neuroprotective effect in rats with cerebral I/R injury, and its potential mechanism is decreasing neuron apoptosis by inhibiting the Rho/ROCK signaling pathway. These results suggest NOB is a promising neuroprotective agent for patients with cerebral ischemia.

Nrf2 Regulates Oxidative Stress and Its Role in Cerebral Ischemic Stroke

Cerebral ischemic stroke is characterized by acute ischemia in a certain part of the brain, which leads to brain cells necrosis, apoptosis, ferroptosis, pyroptosis, etc. At present, there are limited effective clinical treatments for cerebral ischemic stroke, and the recovery of cerebral blood circulation will lead to cerebral ischemia-reperfusion injury (CIRI). Cerebral ischemic stroke involves many pathological processes such as oxidative stress, inflammation, and mitochondrial dysfunction. Nuclear factor erythroid 2-related factor 2 (Nrf2), as one of the most critical antioxidant transcription factors in cells, can coordinate various cytoprotective factors to inhibit oxidative stress. Targeting Nrf2 is considered as a potential strategy to prevent and treat cerebral ischemia injury. During cerebral ischemia, Nrf2 participates in signaling pathways such as Keap1, PI3K/AKT, MAPK, NF-κB, and HO-1, and then alleviates cerebral ischemia injury or CIRI by inhibiting oxidative stress, anti-inflammation, maintaining mitochondrial homeostasis, protecting the blood-brain barrier, and inhibiting ferroptosis. In this review, we have discussed the structure of Nrf2, the mechanisms of Nrf2 in cerebral ischemic stroke, the related research on the treatment of cerebral ischemia through the Nrf2 signaling pathway in recent years, and expounded the important role and future potential of the Nrf2 pathway in cerebral ischemic stroke.

E3 Ubiquitin Ligase FBXO3 Drives Neuroinflammation to Aggravate Cerebral Ischemia/Reperfusion Injury

Ischemic stroke, one of the most universal causes of human mortality and morbidity, is pathologically characterized by inflammatory cascade, especially during the progression of ischemia/reperfusion (I/R) injury. F-Box Protein 3 (FBXO3), a substrate-recognition subunit of SKP1-cullin 1-F-box protein (SCF) E3 ligase complexes, has recently been proven to be severed as an underlying pro-inflammatory factor in pathological processes of diverse diseases. Given these considerations, the current study aims at investigating whether FBXO3 exerts impacts on inflammation in cerebral I/R injury. In this study, first, it was verified that FBXO3 protein expression increased after a middle cerebral artery occlusion/reperfusion (MCAO/R) model in Sprague-Dawley (SD) rats and was specifically expressed in neurons other than microglia or astrocytes. Meanwhile, in mouse hippocampal neuronal cell line HT22 cells, the elevation of FBXO3 protein was observed after oxygen and glucose deprivation/reoxygenation (OGD/R) treatment. It was also found that interference of FBXO3 with siRNA significantly alleviated neuronal damage via inhibiting the inflammatory response in I/R injury both in vivo and in vitro. The FBXO3 inhibitor BC-1215 was used to confirm the pro-inflammatory effect of FBXO3 in the OGD/R model as well. Furthermore, by administration of FBXO3 siRNA and BC-1215, FBXO3 was verified to reduce the protein level of Homeodomain-Interacting Protein Kinase 2 (HIPK2), likely through the ubiquitin-proteasome system (UPS), to aggravate cerebral I/R injury. Collectively, our results underline the detrimental effect FBXO3 has on cerebral I/R injury by accelerating inflammatory response, possibly through ubiquitylating and degrading HIPK2. Despite the specific interaction between FBXO3 and HIPK2 requiring further study, we believe that our data suggest the therapeutic relevance of FBXO3 to ischemic stroke and provide a new perspective on the mechanism of I/R injury.

Potential mechanisms of acupuncture in enhancing cerebral perfusion of ischemic stroke

Ischemic stroke is the predominant cause of long-term disability and death worldwide. It is attributable to the sudden interruption of regional cerebral blood flow, resulting in brain cell death and neurological impairment. Acupuncture is a widely used adjuvant treatment for ischemic stroke in China and shows promising efficacy in clinical practice. This review mainly focused on the evidence to illustrate several possible mechanisms of acupuncture therapy on cerebral perfusion in ischemic stroke. Studies have shown that acupuncture is probably effective in the enhancement of cerebral perfusion after ischemic stroke. It promotes the improvement of hemodynamics, the release of vasoactive substances, the formation of new blood vessels, as well as the restitution of microcirculation. Multiple factors may contribute to the variability in acupuncture's therapeutic effects, including the acupoint selection, stimulation frequency and intensity, and retaining needle time. Acupuncture has the potential to become a non-pharmacological adjuvant approach to enhance cerebral perfusion in ischemic stroke. Future studies are required to gain our insight into acupuncture as well as accelerate its clinical translation.

Parthenolide modulates cerebral ischemia-induced microglial polarization and alleviates neuroinflammatory injury via the RhoA/ROCK pathway

BACKGROUND

Microglia can be activated as proinflammatory (M1) phenotypes and anti-inflammatory (M2) phenotypes after stroke. Parthenolide (PTL) has anti-inflammatory and protective effects on neurological diseases, but until now, the exact mechanisms of these processes after stroke have been unclear. The purpose of this study was to determine the effect of PTL on microglial polarization after stroke and its target for inducing microglial polarization.

METHODS

Triphenyltetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and neurological evaluation were performed in a focal transient cerebral ischemia rat model. The human microglia exposed to lipopolysaccharide (LPS) was used for in vitro experiments. Microglial polarization was assessed by RT-PCR and immunostaining. Inflammatory cytokine assays and western blotting were used to investigate the molecular mechanisms underlying PTL-mediated microglial polarization in vivo and in vitro.

RESULTS

PTL significantly reduced cerebral infarction and neuronal apoptosis in rats with cerebral ischemia, reduced the level of inflammatory factors and alleviated neurological deficits. PTL treatment decreased the expression of microglia/macrophage markers in M1 macrophages and increased the expression of microglia/macrophage markers in M2 macrophages after stroke, which induced the transformation of microglia cells from the M1 phenotype to the M2 phenotype. Furthermore, PTL significantly reduced RhoA/ROCK-NF-κB pathway activity and downregulated the effects of pentanoic acid (ROCK agonist).

CONCLUSIONS

PTL has been shown to mediate neuroinflammation and protect against ischemic brain injury by regulating microglial polarization via the RhoA/ROCK pathway.

Therapeutic Potential and Mechanisms of Novel Simple O-Substituted Isoflavones against Cerebral Ischemia Reperfusion

Isoflavones have been widely studied and have attracted extensive attention in fields ranging from chemotaxonomy and plant physiology to human nutrition and medicine. Isoflavones are often divided into three subgroups: simple O-substituted derivatives, prenylated derivatives, and glycosides. Simple O-substituted isoflavones and their glycosides, such as daidzein (daidzin), genistein (genistin), glycitein (glycitin), biochanin A (astroside), and formononetin (ononin), are the most common ingredients in legumes and are considered as phytoestrogens for daily dietary hormone replacement therapy due to their structural similarity to 17-β-estradiol. On the basis of the known estrogen-like potency, these above isoflavones possess multiple pharmacological activities such as antioxidant, anti-inflammatory, anticancer, anti-angiogenetic, hepatoprotective, antidiabetic, antilipidemic, anti-osteoporotic, and neuroprotective activities. However, there are very few review studies on the protective effects of these novel isoflavones and their related compounds in cerebral ischemia reperfusion. This review primarily focuses on the biosynthesis, metabolism, and neuroprotective mechanism of these aforementioned novel isoflavones in cerebral ischemia reperfusion. From these published works in in vitro and in vivo studies, simple O-substituted isoflavones could serve as promising therapeutic compounds for the prevention and treatment of cerebral ischemia reperfusion via their estrogenic receptor properties and neuron-modulatory, antioxidant, anti-inflammatory, and anti-apoptotic effects. The detailed mechanism of the protective effects of simple O-substituted isoflavones against cerebral ischemia reperfusion might be related to the PI3K/AKT/ERK/mTOR or GSK-3β pathway, eNOS/Keap1/Nrf-2/HO-1 pathway, TLRs/TIRAP/MyD88/NFκ-B pathway, and Bcl-2-regulated anti-apoptotic pathway. However, clinical trials are needed to verify their potential on cerebral ischemia reperfusion because past studies were conducted with rodents and prophylactic administration.

Predictive value of longitudinal changes of serum matrix metalloproteinase-9 and brain-derived neurotrophic factor in acute ischemic stroke

Background

Matrix metalloproteinase-9 (MMP-9) and brain-derived neurotrophic factor (BDNF) have documented roles in the inflammatory injury cascade of neurovascular units following ischemic brain injury. However, their dynamic changes and predictive values after acute ischemic stroke (AIS) have not been well elucidated.

Objective

To investigate the temporal profiles of serum MMP-9 and BDNF concentrations and their relationship with the prognosis in patients with AIS.

Methods

MMP-9 and BDNF levels were measured in 42 AIS patients in prospectively collected blood samples, which were taken on the first day (Day 1), the second day (Day 2), and the fifth day (Day 5) after admission. Healthy subjects (n = 40) were used as controls. The AIS patients were divided into groups of good functional prognosis (n = 24) and poor prognosis (n = 18) according to their modified Rankin Scale score at 3 months. Longitudinal analysis of MMP-9 and BDNF and their association with neurological prognosis was performed using repeated measurement ANOVA.

Results

At baseline (Day 1), the levels of serum MMP-9 and BDNF were significantly higher in the AIS group than in the normal control group (P < 0.01). Repeated measurement ANOVA showed a significant main effect and interaction of MMP-9 between good prognosis and the poor group (P < 0.05). Further simple-effect analysis showed that the MMP-9 level was significantly increased in the poor prognosis group compared with the good prognosis group at T5 (P < 0.05). There were no significant time-dependent or the interaction effect (all P > 0.05), but a main effect (P < 0.05) for BDNF. Compared with the poor prognosis group, the simple-effect results indicated that the BDNF level of the good prognosis group was lower at Day 1, while the same was reversed for expression at Day 5 (P < 0.05).

Conclusion

MMP-9 and BDNF are closely related to the prognosis of patients with AIS in a time-dependent manner. The dynamic changes of the two biomarkers are superior to baseline levels in predicting the prognosis of AIS patients. A sustained decrease in MMP-9 and an increase in BDNF levels in AIS patients after several days of treatment implied a favourable prognosis.

Diabetic Retinopathy May Covariate With Stroke in Diabetes Mellitus

Diabetes mellitus is a chronic metabolic disorder with increasing prevalence per hour. Cataracts are one of the most common eye complications, and they affect all structures of the eye. The incidence of cataracts is increasing in patients with diabetes by several mechanisms. With the advancement of technology, cataract surgery is now a necessary procedure for diabetic patients. High-risk complications, like diabetic macular oedema, diabetic retinopathy (DR), phakic, postoperative cyst, and postoperative macular oedema, and macular oedema and endophthalmitis following surgery for a pseudocyst, could result in blindness. The importance of preoperative, intraoperative, and postoperative factors cannot be overestimated in managing complications and improving visual outcomes. DR can be a severe problem if it worsens and causes non-proliferative or proliferative DR or if fluid accumulation in the eye is diagnosed as macular oedema. A woman progressing to sight-threatening DR during childbearing age experiences distress and often requires ocular treatment. Diabetes that has been present for a more extended period, as well as more significant hyperglycaemia, hypertension, cardiovascular diseases, and elevated blood pressure, substantially predict the development of DR. Oxidative stress can be caused by hyperglycaemia, irregular metabolic processes, and people with DR developing neurodegeneration. Therefore, controlling postprandial hyperglycaemia is crucial for preventing DR. Femtosecond laser technology, multifocal intraocular lenses, and other surgical innovations are popularly referred to as surgical management; it will be engaged in the coming era to determine whether there will be a continued reduction in the complication of cataract surgery. This article aims to review the correlation of DR with stroke and its screening and to outline the critical management strategies. 

The relationship between red blood cell distribution width at admission and post-stroke fatigue in the acute phase of acute ischemic stroke

Introduction

Post-stroke fatigue (PSF) is a common complication in the patients with acute ischemic stroke (AIS). This prospective study aimed to investigate the relationship between red blood cell distribution width (RDW) at admission and PSF in the acute phase.

Methods

The AIS patients were enrolled in Nantong Third People's Hospital, consecutively. PSF in the acute phase was scored according to the Fatigue Severity Scale. Levels of RDW were measured at admission. The associations were analyzed using multivariate regression and restricted cubic splines (RCS).

Results

From April 2021 to March 2022, a total of 206 AIS patients (mean age, 69.3 ± 10.7 years; 52.9% men) were recruited. After the adjustment for potential confounding factors, RDW at admission remained the independent associated factor with PSF in the acute phase (OR [odds ratio], 1.635; 95% CI [confidence interval], 1.153–2.318; P = 0.006). The linear dose-response associations of RDW with PSF in the acute phase were found, based on the RCS model (P for non-linearity = 0.372; P for linearity = 0.037). These results remained significant in other models.

Conclusions

RDW at admission could serve as a novel biomarker of PSF in the acute phase of AIS.

Dexmedetomidine pretreatment alleviates cerebral ischemia/reperfusion injury by inhibiting neuroinflammation through the JAK2/STAT3 pathway

Dexmedetomidine (DEX) is known to provide neuroprotection against cerebral ischemia and reperfusion injury (CIRI), but the exact mechanisms remain unclear. This study was conducted to investigate whether DEX pretreatment conferred neuroprotection against CIRI by inhibiting neuroinflammation through the JAK2/STAT3 signaling pathway. Middle cerebral artery occlusion (MCAO) was performed to establish a cerebral ischemia/reperfusion (I/R) model. Specific-pathogen-free male Sprague-Dawley rats were randomly divided into Sham, I/R, DEX, DEX+IL-6, and AG490 (a selective inhibitor of JAK2) groups. The Longa score, TTC staining, and HE staining were used to evaluate brain damage. ELISA was used to exam levels of TNF-α. Western blotting was used to assess the levels of JAK2, phosphorylated-JAK2 (p-JAK2), STAT3, and phosphorylated-STAT3 (p-STAT3). Our results suggested that both pretreatment with DEX and AG490 decreased the Longa score and cerebral infarct areas following cerebral I/R. After treatment with IL-6, the effects of DEX on abrogating these pathological changes were reduced. HE staining revealed that I/R-induced neuronal pathological changes were attenuated by DEX application, consistent with the AG490 group. However, these effects of DEX were abolished by IL-6. Furthermore, TNF-α levels were significantly increased in the I/R group, accompanied by an increase in the levels of the p-JAK2 and p-STAT3. DEX and AG490 pretreatment down-regulated the expressions of TNF-α, p-JAK2, and p-STAT3. In contrast, the down-regulation of TNF-α, p-JAK2, and p-STAT3 induced by DEX was reversed by IL-6. Collectively, our results indicated that DEX pretreatment conferred neuroprotection against CIRI by inhibiting neuroinflammation via negatively regulating the JAK2/STAT3 signaling pathway.

Anti-Inflammatory Effects of Natural Products on Cerebral Ischemia

Cerebral ischemia with high mortality and morbidity still requires the effectiveness of medical treatments. A growing number of investigations have shown strong links between inflammation and cerebral ischemia. Natural medicine’s treatment methods of cerebral ischemic illness have amassed a wealth of treatment experience and theoretical knowledge. This review summarized recent progress on the disease inflammatory pathways as well as 26 representative natural products that have been routinely utilized to treat cerebral ischemic injury. These natural products have exerted anti-inflammatory effects in cerebral ischemia based on their inflammatory mechanisms, including their inflammatory gene expression patterns and their related different cell types, and the roles of inflammatory mediators in ischemic injury. Overall, the combination of the potential therapeutic interventions of natural products with the inflammatory mechanisms will make them be applicable for cerebral ischemic patients in the future.