Evidence that NF-κB and MAPK Signaling Promotes NLRP Inflammasome Activation in Neurons Following Ischemic Stroke

Novel insights into the molecular mechanisms underlying anti-nociceptive effect of myricitrin against reserpine-induced fibromyalgia model in rats: Implication of SIRT1 and miRNAs

ETHNOPHARMACOLOGICAL RELEVANCE

Manilkara zapota (L.) P. Royen, also termed sapodilla or chikoo, is a significant plant in ethnomedicine because of its long history of traditional medical applications. In diverse cultures, sapodilla is believed to protect against oxidative stress, inflammation, and some chronic diseases because of its high antioxidant content. The naturally occurring antioxidant myricitrin (MYR) flavonoid is primarily found in the leaves and other plant parts of sapodilla and it is well-known for having therapeutic qualities and possible health advantages.

AIM OF THE STUDY

To appraise the possible impact of MYR on a rat model of reserpine-induced fibromyalgia (FM) and explore its mechanism of action.

MATERIALS AND METHODS

Isolation and identification of MYR with more than 99% purity from Manilkara zapota leaves were primarily done and confirmed through chromatographic and spectrophotometric techniques. To develop FM model, reserpine (RSP) was injected daily (1 mg/kg, s.c.) for three successive days. Then, MYR (10 mg/kg, i.p.) and pregabalin (PGB, 30 mg/kg, p.o.) were given daily for another five days. Behavioral changes were assessed through open field test (OFT), hot plate test, and forced swimming test (FST). Further analyses of different brain parameters and signaling pathways were performed to assess monoamines levels, oxidative stress, inflammatory response, apoptotic changes as well as silent information regulator 1 (SIRT1) and micro RNAs (miRNAs) expressions.

RESULTS

From High-Performance Liquid Chromatography (HPLC) analysis, the methanol extract of sapodilla leaves contains 166.17 μg/ml of MYR. Results of behavioral tests showed a significant improvement in RSP-induced nociceptive stimulation, reduced locomotion and exploration and depressive-like behavior by MYR. Biochemical analyses showed that MYR significantly ameliorated the RSP-induced imbalance in brain monoamine neurotransmitters. In addition, MYR significantly attenuated oxidative stress elicited by RSP via up-regulating nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) protein expressions, enhancing superoxide dismutase (SOD) and catalase (CAT) activities, and reducing malondialdehyde (MDA) content in brain. The RSP-provoked inflammatory response was also diminished by MYR treatment as shown by a significant decreased NOD-like receptor protein 3 (NLRP3) inflammasome expression along with reduced levels of interleukin 1 beta (IL-1β) and nuclear factor-κB (NF-κB). Furthermore, the anti-apoptotic activity of MYR was demonstrated by a marked rise in Bcl-2-associated X protein (BAX)/B cell lymphoma-2 (Bcl-2) ratio by lowering Bcl-2 while increasing BAX levels. In addition, MYR treatment significantly boosted the expression of SIRT1 deacetylase in RSP-treated animals. Interestingly, molecular docking showed the ability of MYR to form a stable complex in the binding site of SIRT1. Regarding miRNAs, MYR effectively ameliorated RSP-induced changes in miR-320 and miR-107 gene expressions.

CONCLUSION

Our findings afford new insights into the anti-nociceptive profile of MYR in the RSP-induced FM model in rats. The underlying mechanisms involved direct binding and activation of SIRT1 to influence different signaling cascades, including Nrf2 and NF-κB/NLRP3 together with modulation of miRNAs. However, more in-depth studies are needed before proposing MYR as a new clinically relevant drug in the management of FM.

Drug pairs of Huangqi and Danggui alleviates pyroptosis by promoting autophagy activity via AMPK/mTOR signaling pathway in middle-cerebral artery occlusion/reperfusion in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cerebral ischemia-reperfusion (I/R) injury is a common complication of ischemic stroke, with autophagy and pyroptosis playing key roles. Huangqi and Danggui (HQDG) are a commonly used drug pair of Chinese traditional medicine for clinical treatment of ischemic stroke.

AIM OF THE STUDY

The study aims to investigate the interaction between autophagy and pyroptosis regulated by HQDG through the AMPK/mTOR signaling pathway during cerebral I/R injury.

MATERIALS AND METHODS

Model of middle-cerebral artery occlusion/reperfusion (MCAO/R) in SD rats was established using the Longa suture method. The components of traditional Chinese medicine were detected by liquid chromatography coupled to quadrupole orbitrap high resolution mass spectrometry (LC/MS). Neurological deficits were evaluated by neurological function score. Changes of cerebral blood flow were detected by a laser speckle blood flow imaging instrument. The volume of cerebral infarction was observed by 2,3,5-Chlorotriphenyltetrazolium (TTC) staining. The permeability of the blood-brain barrier was measured by Evans blue test. Neurovascular unit and autophagosomes in brain tissue were assessed by transmission electron microscopy. Neuronal pyroptosis was detected by terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL)/Caspase-1 staining. The expression of autophagy related proteins, pyroptosis related proteins, and AMPK/mTOR pathway related proteins were detected by Western blot.

RESULTS

After cerebral I/R injury, autophagy and pyroptosis, were characterized by increased number of autophagosomes and pyroptosis cells, upregulated expression of Beclin 1, LC3-II/LC3-I, NLRP3, cleaved Caspase-1, IL-1beta, IL-18 proteins, and downregulated expression of P62 proteins. HQDG significantly improved neurological function, reduced the volume of cerebral infarction, increased cerebral blood flow, improved blood-brain barrier permeability and the function of neurovascular units. Autophagy was further activated and pyroptosis was significantly inhibited by HQDG, which promoted increased number of autophagosomes, enhanced expression of Beclin 1, LC3-II/LC3-I proteins, reduced expression of P62, NLRP3, cleaved Caspase-1, IL-1beta, and IL-18 proteins, and downregulated the number of pyroptosis cells. On the other hand, after administering 3-Methyladenine (3-MA) to inhibit autophagy, the above effects of HQDG were significantly inhibited. Besides, HQDG promoted AMPK phosphorylation, and weakened mTOR phosphorylation. However, after the administration of AMPK inhibitor Compound C, HQDG caused increase in Beclin 1 and LC3-II/LC3-I, reduced P62 and NLRP3, and cleaved Caspase-1 protein expression, whereas cerebral blood flow decreased.

CONCLUSION

HQDG alleviated pyroptosis by promoting autophagy via AMPK/mTOR signaling pathway after middle-cerebral artery occlusion/reperfusion in rats, showing its potential for treatment of cerebral I/R injury in humans.

Anti-inflammatory activity and underlying mechanism against sepsis-induced acute lung injury of a low-molecular-weight polysaccharide from the root of Stemona tuberosa Lour

The root of Stemona tuberosa Lour has been used to treat tuberculosis, scabies, and eczema. Polysaccharides are among its main bioactive ingredients. A low-molecular-weight (1819 Da) polysaccharide (SPS2-A) was obtained from the root of S. tuberosa Lour by optimizing three-phase partitioning, purified using an ion chromatography column, and its effects and mechanisms were investigated. Structural analysis revealed that SPS2-A contained arabinose, galactose (Gal), glucose (Glc), xylose, and mannose. The SPS2-A backbone structure comprised sugar residues →4)-α-D-Glcp-(1→, →4)-α-D-Galp-(1→, and →4,6)-β-D-Galp-(1→, while the side chain primarily comprised α-D-Glcp-(1 → connected to the O-6 position of the residue →4,6)-β-D-Galp-(1→. In vitro, SPS2-A downregulated the expression of interleukin-6 in lipopolysaccharide-induced RAW264.7 macrophages. In vivo, SPS2-A significantly downregulated the expression of myeloperoxidase, interleukin-6, interleukin-1β, and tumor necrosis factor-α in bronchoalveolar lavage fluid and lung tissue. Western blotting analysis indicated that SPS2-A reduced lung inflammation in mice with sepsis-induced acute lung injury by activating the nuclear factor κB pathway. These results suggest that SPS2-A is a potential anti-inflammatory candidate for the treatment of sepsis-induced acute lung injury.

Palmitoleate protects against Lipopolysaccharide-induced Inflammation and Inflammasome Activity

Inflammation is part of natural immune defense mechanism against any form of infection or injury. However, prolonged inflammation could perturb cell homeostasis and contribute to the development of metabolic and inflammatory diseases including maternal obesity, diabetes, cardiovascular diseases, and metabolic dysfunction-associated steatotic liver diseases. Polyunsaturated fatty acids have been shown to mitigate inflammatory response by generating specialized pro-resolving lipid mediators which take part in resolution of inflammation. Here, we show that palmitoleate, an omega-7 monounsaturated fatty acid exerts anti-inflammatory properties in response to lipopolysaccharide (LPS)-mediated inflammation. Exposure of bone-marrow derived macrophages (BMDMs) to LPS or TNFα induces robust increase in the expression of pro-inflammatory cytokines and supplementation of palmitoleate inhibited LPS-mediated upregulation of pro-inflammatory cytokines. We also observed that palmitoleate was able to block LPS+ATP-induced inflammasome activation mediated cleavage of pro-caspase 1 and pro-interleukin (IL)-1β. Further, treatment of palmitoleate protects against LPS-induced inflammation in human THP-1 derived macrophages and trophoblasts. Co-exposure of LPS and palmitate (saturated free fatty acid) induces inflammasome and cell death in BMDMs, however, treatment of palmitoleate blocked LPS and palmitate-induced cell death in BMDMs. Further, LPS and palmitate together results in the activation of mitogen activated protein kinases (MAPK) and pretreatment of palmitoleate inhibited the activation of MAPKs and nuclear translocation of nuclear factor kappa B (NF-kB) in BMDMs. In conclusion, palmitoleate shows anti-inflammatory properties against LPS-induced inflammation and LPS+palmitate/ATP-induced inflammasome activity and cell death.

Different expression patterns of inflammation-related genes and serum microRNAs in young-onset ischemic stroke

Brain ischemia results in the activation of a cascade of inflammatory responses, contributing to the pathogenesis of stroke. This study aimed to assess the patterns of possible changes in the expression of specific inflammation-associated protein-encoding genes and miRNAs in the peripheral blood between the acute and chronic phase of young-onset cryptogenic (Cryp) and large-artery atherosclerotic (LAA) stroke. Blood and serum were collected from patients with cryptogenic and large-artery atherosclerotic stroke at the stroke onset and 1-year follow-up. The relative expression of inflammation-related genes was analysed at the mRNA and miRNA levels using real-time quantitative PCR. Moreover, the relationship between the relative gene expression levels and clinical data was assessed using several different statistical approaches. Seventy-three patients were included in this study, with a median age of 47 (IQR, 9) years. Approximately 72% were men. In patients with cryptogenic stroke, at the mRNA level, ICAM1, CXCL8, TNF, NFKBIA, PYCARD, IL1B, and IL18 were observed to be upregulated at the stroke onset compared to the 1-year follow-up. In patients with LAA stroke, only the expression of NFKBIA was significantly higher during acute stroke. Further, the miRNA serum levels of miR-21, miR-122, and miR-155 were higher at the onset of stroke in patients with cryptogenic stroke but not in those with LAA stroke. The differences between the relative gene expression levels during acute stroke and at the 1-year follow-up were more pronounced in patients with cryptogenic stroke with no cardiovascular risk factors. The expression changes of inflammatory genes in whole blood and miRNAs in the serum differ in patients with cryptogenic and LAA stroke.

Neuroinflammation Targeting Pyroptosis: Molecular Mechanisms and Therapeutic Perspectives in Stroke

Pyroptosis is a recently identified type of pro-inflammatory programmed cell death (PCD) mediated by inflammasomes and nucleotide oligomerization domain-like receptors (NLs) and dependent on members of the caspase family. Pyroptosis has been widely reported to participate in the occurrence and progression of various inflammatory diseases, including stroke, a frequently lethal disease with high prevalence and many complications. To date, there have been no effectively therapeutic strategies and methods for treating stroke. Pyroptosis is thought to be closely related to the occurrence and development of stroke. Understanding inflammatory responses induced by the activation of pyroptosis would be hopeful to provide feasible approaches and strategies. Targeting on molecules in the upstream or downstream of pyroptosis pathway has shown promise in the treatment of stroke. The present review summarizes current research on the characteristics of pyroptosis, the function and pathological phenomena of pyroptosis in stroke, the molecule mechanisms related to inflammatory pathways, and the drugs and other molecules that can affect outcomes after stroke. These findings may help identify possible targets or new strategies for the diagnosis and treatment of stroke.

Hepatoprotective effects of zingerone on sodium arsenite-induced hepatotoxicity in rats: Modulating the levels of caspase-3/Bax/Bcl-2, NLRP3/NF-κB/TNF-α and ATF6/IRE1/PERK/GRP78 signaling pathways

OBJECTIVE

Long-term exposure to arsenic has been linked to several illnesses, including hypertension, diabetes, hepatic and renal diseases and cardiovascular malfunction. The aim of the current investigation was to determine whether zingerone (ZN) could shield rats against the hepatotoxicity that sodium arsenite (SA) causes.

METHODS

The following five groups of thirty-five male Sprague Dawley rats were created: I) Control; received normal saline, II) ZN; received ZN, III) SA; received SA, IV) SA + ZN 25; received 10 mg/kg body weight SA + 25 mg/kg body weight ZN, and V) SA + ZN 50; received 10 mg/kg body weight SA + 50 mg/kg body weight ZN. The experiment lasted 14 days, and the rats were sacrificed on the 15th day. While oxidative stress parameters were studied by spectrophotometric method, apoptosis, inflammation and endoplasmic reticulum stress parameters were measured by RT-PCR method.

RESULTS

The SA disrupted the histological architecture and integrity of the liver and enhanced oxidative damage by lowering antioxidant enzyme activity, such as those of glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), glutathione (GSH) level and increasing malondialdehyde (MDA) level in the liver tissue. Additionally, SA increased the mRNA transcript levels of Bcl2 associated x (Bax), caspases (-3, -6, -9), apoptotic protease-activating factor 1 (Apaf-1), p53, tumor necrosis factor-α (TNF-α), nuclear factor kappa B (NF-κB), interleukin-1β (IL-1β), interleukin-6 (IL-6), c-Jun NH2-terminal kinase (JNK), mitogen-activated protein kinase 14 (MAPK14), MAPK15, receptor for advanced glycation endproducts (RAGE) and nod-like receptor family pyrin domain-containing 3 (NLRP3) in the liver tissue. Also produced endoplasmic reticulum stress by raising the mRNA transcript levels of activating transcription factor 6 (ATF-6), protein kinase RNA-like ER kinase (PERK), inositol-requiring enzyme 1 (IRE1), and glucose-regulated protein 78 (GRP-78). These factors together led to inflammation, apoptosis, and endoplasmic reticulum stress. On the other hand, liver tissue treated with ZN at doses of 25 and 50 mg/kg showed significant improvement in oxidative stress, inflammation, apoptosis and endoplasmic reticulum stress.

CONCLUSIONS

Overall, the study's data suggest that administering ZN may be able to lessen the liver damage caused by SA toxicity.

Protective Effects of Carvacrol on Mercuric Chloride-Induced Lung Toxicity Through Modulating Oxidative Stress, Apoptosis, Inflammation, and Autophagy

Mercuric chloride (HgCl2) is extremely toxic to both humans and animals. It could be absorbed via ingestion, inhalation, and skin contact. Exposure to HgCl2 can cause severe health effects, including damages to the gastrointestinal, respiratory, and central nervous systems. The purpose of this work was to explore if carvacrol (CRV) could protect rats lungs from damage caused by HgCl2. Intraperitoneal injections of HgCl2 at a dose of 1.23 mg/kg body weight were given either alone or in conjunction with oral CRV administration at doses of 25 and 50 mg/kg body weight for 7 days. The study included biochemical and histological techniques to examine the lung tissue's oxidative stress, apoptosis, inflammation, and autophagy processes. HgCl2-induced reductions in GSH levels and antioxidant enzymes (SOD, CAT, and GPx) activity were enhanced by CRV co-administration. Furthermore, MDA levels were lowered by CRV. The inflammatory mediators NF-κB, IκB, NLRP3, TNF-α, IL-1β, IL6, COX-2, and iNOS were all reduced by CRV. When exposed to HgCl2, the levels of apoptotic Bax, caspase-3, Apaf1, p53, caspase-6, and caspase-9 increased, but the levels of antiapoptotic Bcl-2 reduced after CRV treatment. CRV decreased levels of Beclin-1, LC3A, and LC3B, which in turn decreased HgCl2-induced autophagy damage. After HgCl2 treatment, higher pathological damage was observed in terms of alveolar septal thickening, congestion, edema, and inflammatory cell infiltration compared to the control group while CRV ameliorated these effects. Consequently, by preventing HgCl2-induced increases in oxidative stress and the corresponding inflammation, autophagy, apoptosis, and disturbance of tissue integrity in lung tissues, CRV might be seen as a useful therapeutic alternative.

A2 reactive astrocyte-derived exosomes alleviate cerebral ischemia-reperfusion injury by delivering miR-628

Ischemia and hypoxia activate astrocytes into reactive types A1 and A2, which play roles in damage and protection, respectively. However, the function and mechanism of A1 and A2 astrocyte exosomes are unknown. After astrocyte exosomes were injected into the lateral ventricle, infarct volume, damage to the blood-brain barrier (BBB), apoptosis and the expression of microglia-related proteins were measured. The dual luciferase reporter assay was used to detect the target genes of miR-628, and overexpressing A2-Exos overexpressed and knocked down miR-628 were constructed. qRT-PCR, western blotting and immunofluorescence staining were subsequently performed. A2-Exos obviously reduced the infarct volume, damage to the BBB and apoptosis and promoted M2 microglial polarization. RT-PCR showed that miR-628 was highly expressed in A2-Exos. Dual luciferase reporter assays revealed that NLRP3, S1PR3 and IRF5 are target genes of miR-628. After miR-628 was overexpressed or knocked down, the protective effects of A2-Exos increased or decreased, respectively. A2-Exos reduced pyroptosis and BBB damage and promoted M2 microglial polarization through the inhibition of NLRP3, S1PR3 and IRF5 via the delivery of miR-628. This study explored the mechanism of action of A2-Exos and provided new therapeutic targets and concepts for treating cerebral ischemia.

The impact of cytokines in neuroinflammation-mediated stroke

Cerebral stroke is ranked as the third most common contributor to global mortality and disability. The involvement of inflammatory mechanisms, both peripherally and within the CNS, holds significance in the pathophysiological cascades following the initiation of stroke. After the onset of acute stroke, predominantly ischemic, a subsequent phase of neuroinflammation ensues. It is a dual-effect process that not only exacerbates injury, leading to cell death, but paradoxically, it also serves a shielding role in facilitating recovery. Cytokines serve as pivotal mediators within the inflammatory cascade, actively contributing to the progression of ischemic damage. Stroke is followed by increased expression of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, etc. leading to the recruitment and stimulation of glial cells and peripheral leukocytes at the site of injury, promoting neuroinflammation. Cytokines can directly induce neuronal injury and death through various mechanisms, including excitotoxicity, oxidative stress, HPA-axis activation, secretion of matrix metalloproteinase and apoptosis. They can also amplify the inflammatory response, leading to further neuronal damage. Therapeutic strategies aimed at modulating cytokine release, immune response and cytokine signalling or activity are being explored as potential interventions to mitigate neuroinflammation and its detrimental effects in stroke. In this review, we have given a concise summary of our current knowledge of the function of various cytokines, brain inflammation and various signalling and molecular pathways including JAK/STAT3, TGF-β/Smad, MAPK, HMGB1/TLR and NF-κB modulated cytokines regulation in stroke. Therapeutic agents such as MCC950, genistein, edaravone, minocycline, etc. targeting various cytokines-associated signalling pathways have shown efficacy in preclinical and clinical trials reducing the pathophysiology of the illness were also addressed in this study.

Voacangine mitigates oxidative stress and neuroinflammation in middle cerebral artery occlusion-induced cerebral ischemia/reperfusion injury by averting the NF-κBp65/MAPK signaling pathways in rats

Ischemic stroke is a leading cause of human mortality. Cerebral ischemia-reperfusion injury (CI/RI) is a primary cause of stroke. Ischemia-reperfusion (I/R) resulting in oxidative stress and inflammatory events may lead to severe neuronal impairments. Thus, anti-oxidative and anti-inflammatory mediators that can alleviate post-I/R neuronal injuries are required for the treatment of CI/RI. An alkaloid, voacangine (VCG) is a recognized antioxidant, anti-inflammatory, and anticancer agent. Hence, the current study intended to explore the neuroprotective potential and the principal mechanisms of VCG in CI/RI. The experimental rats were divided into four sets: control, I/R-induced, I/R + VCG (2.5 mg/kg), I/R + VCG (5 mg/kg). CI/RI was induced by implanting a thread into the middle cerebral artery occlusion (MCAO) model. Brain damages were assessed on the basis of brain edema, brain infarct volume, neurological deficit score, histopathology, oxidative stress, and neuroinflammation. Results revealed that VCG inhibited the triggering of NLRP3 inflammasome, pro-inflammatory cytokines, lipid peroxidation, but enhanced the antioxidant status in MCAO rats. Furthermore, VCG treatment averted brain damage by I/R, neuroinflammation, and oxidative stress by suppressing NF-κBp65/MAPK pathways. The results of the study provide pertinent insights pertaining to the role of VCG as a potential neuroprotective agent against ischemic stroke.

A Synthetic Derivative SH 66 of Homoisoflavonoid from Liliaceae Exhibits Anti-Neuroinflammatory Activity against LPS-Induced Microglial Cells

Naturally occurring homoisoflavonoids isolated from some Liliaceae plants have been reported to have diverse biological activities (e.g., antioxidant, anti-inflammatory, and anti-angiogenic effects). The exact mechanism by which homoisoflavonones exert anti-neuroinflammatory effects against activated microglia-induced inflammatory cascades has not been well studied. Here, we aimed to explore the mechanism of homoisoflavonoid SH66 having a potential anti-inflammatory effect in lipopolysaccharide (LPS)-primed BV2 murine microglial cells. Microglia cells were pre-treated with SH66 followed by LPS (100 ng/mL) activation. SH66 treatment attenuated the production of inflammatory mediators, including nitric oxide and proinflammatory cytokines, by down-regulating mitogen-activated protein kinase signaling in LPS-activated microglia. The SH66-mediated inhibition of the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex and the respective inflammatory biomarker-like active interleukin (IL)-1β were noted to be one of the key pathways of the anti-inflammatory effect. In addition, SH66 increased the neurite length in the N2a neuronal cell and the level of nerve growth factor in the C6 astrocyte cell. Our results demonstrated the anti-neuroinflammatory effect of SH66 against LPS-activated microglia-mediated inflammatory events by down-regulating the NLRP3 inflammasome complex, with respect to its neuroprotective effect. SH66 could be an interesting candidate for further research and development regarding prophylactics and therapeutics for inflammation-mediated neurological complications.

New strategy to treat spinal cord injury: Nafamostat mesilate suppressed NLRP3-mediated pyroptosis during acute phase

Spinal cord injury (SCI) is a devastating condition for which effective clinical treatment is currently lacking. During the acute phase of SCI, myriad pathological changes give rise to subsequent secondary injury. The results of our previous studies indicated that treating rats post-SCI with nafamostat mesilate (NM) protected the blood-spinal cord barrier (BSCB) and exerted an antiapoptotic effect. However, the optimal dosage for mice with SCI and the underlying mechanisms potentially contributing to recovery, especially during the acute phase of SCI, have not been determined. In this study, we first determined the optimal dosage of NM for mice post-SCI (5 mg/kg/day). Subsequently, our RNA-seq findings revealed that NM has the potential to inhibit pyroptosis after SCI. These findings were further substantiated by subsequent Western blot (WB) and Immunofluorescence (IF) analyses in vivo. These results indicate that NM can alleviate NLRP3 (NOD-like receptor thermal protein domain associated protein 3)-mediated pyroptosis by modulating the NF-κB signaling pathway and reducing the protein expression levels of NIMA-related kinase 7 (NEK7) and cathepsin B (CTSB). In vitro experimental results supported our in vivo findings, revealing the effectiveness of NM in suppressing pyroptosis induced by adenosine triphosphate (ATP) and lipopolysaccharide (LPS) in BV2 cells. These results underscore the potential of NM to regulate NLRP3-mediated pyroptosis following SCI. Notably, compared with other synthetic compounds, NM exhibits greater versatility, suggesting that it is a promising clinical treatment option for SCI.

Targeting pyroptosis to treat ischemic stroke: From molecular pathways to treatment strategy

Ischemic stroke is the primary reason for human disability and death, but the available treatment options are limited. Hence, it is imperative to explore novel and efficient therapies. In recent years, pyroptosis (a pro-inflammatory cell death characterized by inflammation) has emerged as an important pathological mechanism in ischemic stroke that can cause cell death through plasma membrane rupture and release of inflammatory cytokines. Pyroptosis is closely associated with inflammation, which exacerbates the inflammatory response in ischemic stroke. The level of inflammasomes, GSDMD, Caspases, and inflammatory factors is increased after ischemic stroke, exacerbating brain injury by mediating pyroptosis. Hence, inhibition of pyroptosis can be a therapeutic strategy for ischemic stroke. In this review, we have summarized the relationship between pyroptosis and ischemic stroke, as well as a series of treatments to attenuate pyroptosis, intending to provide insights for new therapeutic targets on ischemic stroke.

Pannexin1 Channel-Mediated Inflammation in Acute Ischemic Stroke

Emerging evidence suggests that inflammation mediated by the pannexin1 channel contributes significantly to acute ischemic stroke. It is believed that the pannexin1 channel is key in initiating central system inflammation during the early stages of acute ischemic stroke. Moreover, the pannexin1 channel is involved in the inflammatory cascade to maintain the inflammation levels. Specifically, the interaction of pannexin1 channels with ATP-sensitive P2X7 purinoceptors or promotion of potassium efflux mediates the activation of the NLRP3 inflammasome, triggering the release of pro-inflammatory factors such as IL-1 and IL-18, exacerbating and sustaining inflammation of brain. Also, increased release of ATP induced by cerebrovascular injury activates pannexin1 in vascular endothelial cells. This signal directs peripheral leukocytes to migrate into ischemic brain tissue, leading to an expansion of the inflammatory zone. Intervention strategies targeting pannexin1 channels may greatly alleviate inflammation after acute ischemic stroke to improve this patient population's clinical outcomes. In this review, we sought to summarize relevant studies on inflammation mediated by the pannexin1 channel in acute ischemic stroke and discussed the possibility of using brain organoid-on-a-chip technology to screen miRNAs that exclusively target the pannexin1 channel to provide new therapeutic measures for targeted regulation of pannexin1 channel to reduce inflammation in acute ischemic stroke.

Detrimental Roles of Hypoxia-Inducible Factor-1α in Severe Hypoxic Brain Diseases

Hypoxia stabilizes hypoxia-inducible factors (HIFs), facilitating adaptation to hypoxic conditions. Appropriate hypoxia is pivotal for neurovascular regeneration and immune cell mobilization. However, in central nervous system (CNS) injury, prolonged and severe hypoxia harms the brain by triggering neurovascular inflammation, oxidative stress, glial activation, vascular damage, mitochondrial dysfunction, and cell death. Diminished hypoxia in the brain improves cognitive function in individuals with CNS injuries. This review discusses the current evidence regarding the contribution of severe hypoxia to CNS injuries, with an emphasis on HIF-1α-mediated pathways. During severe hypoxia in the CNS, HIF-1α facilitates inflammasome formation, mitochondrial dysfunction, and cell death. This review presents the molecular mechanisms by which HIF-1α is involved in the pathogenesis of CNS injuries, such as stroke, traumatic brain injury, and Alzheimer's disease. Deciphering the molecular mechanisms of HIF-1α will contribute to the development of therapeutic strategies for severe hypoxic brain diseases.

Advancements in research on the immune-inflammatory mechanisms mediated by NLRP3 inflammasome in ischemic stroke and the regulatory role of natural plant products

Ischemic stroke (IS) is a major cause of mortality and disability among adults. Recanalization of blood vessels to facilitate timely reperfusion is the primary clinical approach; however, reperfusion itself may trigger cerebral ischemia-reperfusion injury. Emerging evidence strongly implicates the NLRP3 inflammasome as a potential therapeutic target, playing a key role in cerebral ischemia and reperfusion injury. The aberrant expression and function of NLRP3 inflammasome-mediated inflammation in cerebral ischemia have garnered considerable attention as a recent research focus. Accordingly, this review provides a comprehensive summary of the signaling pathways, pathological mechanisms, and intricate interactions involving NLRP3 inflammasomes in cerebral ischemia-reperfusion injury. Moreover, notable progress has been made in investigating the impact of natural plant products (e.g., Proanthocyanidins, methylliensinine, salidroside, α-asarone, acacia, curcumin, morin, ginsenoside Rd, paeoniflorin, breviscapine, sulforaphane, etc.) on regulating cerebral ischemia and reperfusion by modulating the NLRP3 inflammasome and mitigating the release of inflammatory cytokines. These findings aim to present novel insights that could contribute to the prevention and treatment of cerebral ischemia and reperfusion injury.

Neuroprotective effects of Aucubin against cerebral ischemia-reperfusion injury

AIMS

To study the role of Aucubin (AU) in cerebral ischemia-reperfusion injury and investigate the potential mechanisms.

METHODS

For the in vitro experiment, primary microglia were cultured and stimulated by Lipopolysaccharides (LPS) and treated with AU. Male C57/BL6J mice were used and middle cerebral artery occlusion (MCAO) model was performed to induce cerebral ischemia-reperfusion injury. For the short-term effects, mice administrated with AU (40 mg/kg) for 3 days after MCAO were evaluated for the infarct volume and neurological deficits. The neuroinflammatory factors and microglia activation were determined by Real-time PCR, western blot and immunofluorescence staining. For the long-term effects, MCAO mice were injected daily with AU (5 mg/kg or 10 mg/kg) for 28 days. Behavior tests were used to assess the neurological deficits of MCAO mice, and white matter integrity was determined by myelin basic protein (MBP) staining and black-gold staining.

RESULTS

AU suppressed LPS-induced activation of microglia and pro-inflammatory cytokines release, and downregulated the NF-κB and MAPK pathways in primary microglia. In addition, AU attenuated ischemic injury and inhibited the neuro-inflammatory response in MCAO mice. Moreover, AU induced prolonged improvements in sensorimotor function and memory function following MCAO, and preserved white matter integrity in the long-term experiments.

CONCLUSIONS

AU protected against ischemic injury, which might be correlated with the downregulation of NF-κB and MAPK signaling pathways. Furthermore, AU alleviated cognitive impairment after stroke and restored white matter integrity. Our data indicated that AU might be a potential compound for the treatment of stroke and post-stroke cognitive impairment.

Function and inhibition of P38 MAP kinase signaling: Targeting multiple inflammation diseases

Inflammation is a natural host defense mechanism that protects the body from pathogenic microorganisms. A growing body of research suggests that inflammation is a key factor in triggering other diseases (lung injury, rheumatoid arthritis, etc.). However, there is no consensus on the complex mechanism of inflammatory response, which may include enzyme activation, mediator release, and tissue repair. In recent years, p38 MAPK, a member of the MAPKs family, has attracted much attention as a central target for the treatment of inflammatory diseases. However, many p38 MAPK inhibitors attempting to obtain marketing approval have failed at the clinical trial stage due to selectivity and/or toxicity issues. In this paper, we discuss the mechanism of p38 MAPK in regulating inflammatory response and its key role in major inflammatory diseases and summarize the synthetic or natural products targeting p38 MAPK to improve the inflammatory response in the last five years, which will provide ideas for the development of novel clinical anti-inflammatory drugs based on p38 MAPK inhibitors.

Urban Particulate Matter Triggers Meibomian Gland Dysfunction

Purpose

The meibomian gland (MG), as the largest modified sebaceous gland, is potentially damaged by urban particulate matter (UPM) based on epidemiological evidence, but the specific experimental mechanisms remain unknown. This study investigated the effects of UPM on MG dysfunction (MGD) in rodent models.

Methods

Female C57BL/6J mice received eye drops containing UPM suspension or PBS for 14 days. The proliferative capacity and progenitor of MG were evaluated by immunofluorescence. Cell apoptosis was confirmed by TUNEL assay, along with the analysis of caspase family expression. Lipid accumulation was visualized by Oil Red O staining and LipidTox staining. Ductal hyperkeratinization, neutrophil infiltration, and pyroptosis activation were detected through immunostaining. The relative gene expression and signaling pathway activation were determined by Western blot analysis.

Results

Administration of UPM caused MGD-like clinical signs, manifested as distinct corneal epithelial erosion, increased MG orifice occlusion, and glandular dropout. UPM exposure significantly induced progenitor loss, cellular apoptosis, and lipogenic disorder in MG, by reducing P63/Lrig1 expression and increasing cleaved caspase-8, -9, and -3 and meibum lipogenic protein (HMGCR/SREBP-1) expression. UPM-treated mice exhibited ductal hyperkeratinization and neutrophil recruitment. Simultaneously, pyroptosis was motivated, as indicated by the heightened expression of NLRP3 and the cleavage of caspase-1 and -4 and gasdermin D, as well as the increase in IL-1β and IL-18 downstream. The underlying pathological mechanisms of UPM involve the phosphorylation of mitogen-activated protein kinase and nuclear factor-κB.

Conclusions

These results provided direct evidence for the toxicity of UPM in MG. UPM-induced activation of pyroptosis and mitogen-activated protein kinase/nuclear factor-κB signaling pathway might account for the inflammatory MGD.

Edaravone dexborneol alleviates cerebral ischemia-reperfusion injury through NF-κB/NLRP3 signal pathway

Inflammatory injury following ischemia-reperfusion (I/R) severely limits the efficacy of stroke treatment. Edaravone dexborneol (C.EDA) has been shown to reduce inflammation following a cerebral hemorrhage. However, the precise anti-inflammatory mechanism of C.EDA is unknown. In this study, we investigated whether C.EDA provides neuroprotection after I/R in rats, as well as the potential mechanisms involved. A middle cerebral artery occlusion/reperfusion (I/R) model was created using Sprague-Dawley rats. The blood flow of the central cerebral artery was monitored by a laser speckle imaging system. The neurological score was used to assess behavioral improvement. Cerebral infarction volume was measured by TTC staining. And the integrity of the blood-brain barrier was detected by Evan's blue staining. The expression of the nuclear factor kappa-B (NF-κB)/ the NOD-like receptor protein (NLRP3) inflammasome signal pathway and microglia polarization were detected by immunofluorescence and Western blotting. The cerebral blood flow ratio indicates that the cerebral I/R model was successfully established. After reperfusion for 72 h, the improvement of neurological scores, infarct volume reduction, and integrity of the blood-brain barrier was observed in I/R rats with C.EDA treatment. Meanwhile, the immunofluorescence result showed that the expression of iNOS, NLRP3, and NF-κB protein was decreased and the level of Arg1 was increased. Western blot analysis showed that the expression of NF-κB/NLRP3 signal pathway-related protein was decreased. In conclusion, this study indicates that C.EDA alleviates I/R injury by blocking the activation of the NLRP3 inflammasome and regulating the polarization of M1/M2 microglia via the NF-κB signal pathway.

Role of Mitogen-Activated Protein (MAP) Kinase Pathways in Metabolic Diseases

Physiological processes that govern the normal functioning of mammalian cells are regulated by a myriad of signalling pathways. Mammalian mitogen-activated protein (MAP) kinases constitute one of the major signalling arms and have been broadly classified into four groups that include extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), p38, and ERK5. Each signalling cascade is governed by a wide array of external and cellular stimuli, which play a critical part in mammalian cells in the regulation of various key responses, such as mitogenic growth, differentiation, stress responses, as well as inflammation. This evolutionarily conserved MAP kinase signalling arm is also important for metabolic maintenance, which is tightly coordinated via complicated mechanisms that include the intricate interaction of scaffold proteins, recognition through cognate motifs, action of phosphatases, distinct subcellular localisation, and even post-translational modifications. Aberration in the signalling pathway itself or their regulation has been implicated in the disruption of metabolic homeostasis, which provides a pathophysiological foundation in the development of metabolic syndrome. Metabolic syndrome is an umbrella term that usually includes a group of closely associated metabolic diseases such as hyperglycaemia, hyperlipidaemia, and hypertension. These risk factors exacerbate the development of obesity, diabetes, atherosclerosis, cardiovascular diseases, and hepatic diseases, which have accounted for an increase in the worldwide morbidity and mortality rate. This review aims to summarise recent findings that have implicated MAP kinase signalling in the development of metabolic diseases, highlighting the potential therapeutic targets of this pathway to be investigated further for the attenuation of these diseases.

HuR deficiency abrogated the enhanced NLRP3 signaling in experimental ischemic stroke

Human antigen R (HuR) is a universally expressed RNA-binding protein that plays an essential role in governing the fate of mRNA transcripts. Accumulating evidence indicated that HuR is involved in the development and functions of several cell types. However, its role in cerebral ischemia/reperfusion injury (CIRI) remains unclear. In this study, we found that HuR was significantly upregulated after CIRI. Moreover, we found that silencing HuR could inhibit the inflammatory response of microglia and reduce the damage to neurons caused by oxygen-glucose deprivation/reperfusion treatment. In vivo, we found that microglial HuR deficiency significantly ameliorated CIRI and reduced NLRP3-mediated inflammasome activation. Mechanistically, we found that HuR could regulate NLRP3 mRNA stability by binding to the AU-rich element (ARE) region within the 3' untranslated region (UTR) of NLRP3 mRNA. In addition, we found that the upregulation of HuR was dependent on the upregulation of NADPH oxidase-mediated ROS accumulation. Collectively, our studies revealed that HuR could regulate NLRP3 expression and that HuR deficiency abrogated the enhanced NLRP3 signaling in experimental ischemic stroke. Targeting HuR may be a novel therapeutic strategy for cerebral ischemic stroke treatment.

Mastoparan M Suppressed NLRP3 Inflammasome Activation by Inhibiting MAPK/NF-κB and Oxidative Stress in Gouty Arthritis

Background

Gouty arthritis is characterized by the accumulation of monosodium urate crystals (MSU) in the synovial joints and surrounding tissues. Mastoparan M (Mast-M) is a biologically active peptide composed of 14 amino acids, extracted from wasp venom. This study aims to assess the impact of Mast-M on in vitro and in vivo gouty arthritis induced by lipolyaccharide (LPS) plus MSU crystal stimulation.

Methods

PMA-differentiated THP-1 macrophages were pre-treated with Mast-M or left untreated, followed by stimulation with LPS and MSU crystals. Cell lysates were collected to assess the expression of the NLRP3 inflammasome, inflammatory signaling pathways, and oxidative stress. Furthermore, to evaluate the in vivo anti-inflammatory effect of Mast-M, an experimental acute gouty arthritis mouse model was established through intra-articular injection of MSU crystals.

Results

Mast-M treatment demonstrated significant inhibition of the phosphorylation of MAPKs/NF-κB signaling pathways and reduction in oxidative stress expression in LPS and MSU-induced THP-1 macrophages. This resulted in the suppression of downstream NLRP3 inflammasome activation and IL-1β release. In vivo, Mast-M effectively attenuated the inflammation induced by MSU in mice with gouty arthritis. Specifically, Mast-M reduced swelling in the paws, inhibited the infiltration of neutrophils and macrophages into periarticular tissue, and decreased the activation of the NLRP3 inflammasome and IL-1β production.

Conclusion

Mast-M significantly improves gouty arthritis, and its potential mechanism may be achieved by inhibiting the MAPK/NF-κB pathway and alleviating oxidative stress, thus suppressing the activation of NLRP3 inflammasomes.

Inflammasome Activation Mediates Apoptotic and Pyroptotic Death in Astrocytes Under Ischemic Conditions

Inflammation is a hallmark mechanism of ischemic stroke-induced brain injury. Recent studies have shown that an intracellular multimeric protein complex known as an inflammasome is a key factor for inducing an inflammatory response, and apoptotic and pyroptotic cell death in ischemic stroke. Inflammasome assembly leads to the activation of pro-inflammatory caspases, and the maturation and secretion of pro-inflammatory cytokines IL-1β and IL-18. While the role of inflammasomes in ischemic stroke-induced neuronal death, and microglial activation and cell death have been established, little is known about the role of inflammasomes in astrocytes under ischemic conditions. In this study, we investigated the expression and activation of inflammasome components in protoplasmic and fibrous astrocytes under ischemic conditions. We found that both protoplasmic and fibrous astrocytes expressed a differential increase in inflammasome protein components, and that their activation promoted maturation of IL-1β and IL-18, and secretion of IL-1β, as well as initiating apoptotic and pyroptotic cell death. Pharmacological inhibition of caspase-1 decreased expression of cleaved caspase-1 and production of mature IL-1β, and protected against inflammasome-mediated apoptotic and pyroptotic cell death. Overall, this study provides novel insights into the role of inflammasome signaling in astrocytes under ischemic conditions.

Peripheral inflammation and neurocognitive impairment: correlations, underlying mechanisms, and therapeutic implications

Cognitive impairments, such as learning and memory deficits, may occur in susceptible populations including the elderly and patients who are chronically ill or have experienced stressful events, including surgery, infection, and trauma. Accumulating lines of evidence suggested that peripheral inflammation featured by the recruitment of peripheral immune cells and the release of pro-inflammatory cytokines may be activated during aging and these conditions, participating in peripheral immune system-brain communication. Lots of progress has been achieved in deciphering the core bridging mechanism connecting peripheral inflammation and cognitive impairments, which may be helpful in developing early diagnosis, prognosis evaluation, and prevention methods based on peripheral blood circulation system sampling and intervention. In this review, we summarized the evolving evidence on the prevalence of peripheral inflammation-associated neurocognitive impairments and discussed the research advances in the underlying mechanisms. We also highlighted the prevention and treatment strategies against peripheral inflammation-associated cognitive dysfunction.

Regulated necrosis pathways: a potential target for ischemic stroke

Globally, ischemic stroke causes millions of deaths per year. The outcomes of ischemic stroke are largely determined by the amount of ischemia-related and reperfusion-related neuronal death in the infarct region. In the infarct region, cell injuries follow either the regulated pathway involving precise signaling cascades, such as apoptosis and autophagy, or the nonregulated pathway, which is uncontrolled by any molecularly defined effector mechanisms such as necrosis. However, numerous studies have recently found that a certain type of necrosis can be regulated and potentially modified by drugs and is nonapoptotic; this type of necrosis is referred to as regulated necrosis. Depending on the signaling pathway, various elements of regulated necrosis contribute to the development of ischemic stroke, such as necroptosis, pyroptosis, ferroptosis, pathanatos, mitochondrial permeability transition pore-mediated necrosis and oncosis. In this review, we aim to summarize the underlying molecular mechanisms of regulated necrosis in ischemic stroke and explore the crosstalk and interplay among the diverse types of regulated necrosis. We believe that targeting these regulated necrosis pathways both pharmacologically and genetically in ischemia-induced neuronal death and protection could be an efficient strategy to increase neuronal survival and regeneration in ischemic stroke.

Trends in NLRP3 inflammasome research in ischemic stroke from 2011 to 2022: A bibliometric analysis

BACKGROUND

Ischemic stroke is a leading cause of permanent disability and death globally. The nucleotide-biding oligomaerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a multi-protein complex that plays a role in ischemic stroke. Recently, research on the role of NLRP3 in ischemic stroke has developed rapidly worldwide. However, there is no bibliometric analysis of NLRP3 in ischemic stroke to date.

AIM

Through bibliometric analysis, the aim of this study was to assess the current state of research on NLRP3 in the field of ischemic stroke research worldwide over the past 12 years and to identify important results, major research areas, and emerging trends.

METHODS

Publications related to NLRP3 in ischemic stroke from January 1, 2011 to December 31, 2022 were obtained from the Web of Science Core Collection (WoSCC). We used HistCite, VOSviewer, CiteSpace, and Bibliometrix for bibliometric analysis and visualization. The Total Global Citation Score (TGCS) was employed to assess the impact of publications.

RESULTS

We found that research of NLRP3 in ischemic stroke developed rapidly starting in 2011. 601 relevant studies have been published in 245 journals over the past 12 years. Journal of Neuroinflammation and International Immunopharmacology were the most productive journals and Journal of Neuroinflammation was the most cited journal. Additionally, Stroke and Journal of Cerebral Blood Flow & Metabolism were the most co-cited journal. The most productive country was China (records = 430) and the most productive university was the Zhejiang University (records = 24). Arumugam TV (TGCS = 949) was the most cited author in this field. NLRP3 inflammasome activation, nf-κb, oxidative stress, and inflammation were the knowledge bases for the research in this field.

CONCLUSION

This study is a scientometric study utilizing quantitative and qualitative methods to comprehensively review the publications on NLRP3 in ischemic stroke. This information provides a reference for scholars to further study NLRP3 in ischemic stroke.

Indole-3-carbinol mitigates oxidative stress and inhibits inflammation in rat cerebral ischemia/reperfusion model

Ischemia is a significant pathogenetic factor of stroke with very limited treatment options. The objective of our research was to evaluate the protective properties of indole-3-carbinol (I3C) and its effect on redox status parameters, inflammation, and apoptosis intensity in cerebral ischemia/reperfusion injury (CIRI) in rats. I3C administration to CIRI rats decreased levels of oxidative stress markers and improved aerobic metabolism compared to the animals with CIRI. A decrease in myeloperoxidase activity, proinflammatory cytokines mRNA levels, and expression of redox-sensitive factor Nuclear Factor-κB was observed in rats with CIRI that received I3C. I3C-treated rats with pathology showed decreased caspase activity and apoptosis-inducing factor expression, compared to the animals in the CIRI group. Obtained data indicate that I3C has a neuroprotective and anti-ischemic effect in CIRI that may be related to its antioxidant properties and ability to reduce the inflammatory response and apoptosis.

12/15-lipoxygenase inhibition attenuates neuroinflammation by suppressing inflammasomes

Introduction

Lipoxygenases (LOXs) have essential roles in stroke, atherosclerosis, diabetes, and hypertension. 12/15-LOX inhibition was shown to reduce infarct size and brain edema in the acute phase of experimental stroke. However, the significance of 12/15-LOX on neuroinflammation, which has an essential role in the pathophysiology of stroke, has not been clarified yet.

Methods

In this study, ischemia/recanalization (I/R) was performed by occluding the proximal middle cerebral artery (pMCAo) in mice. Either the 12/15-LOX inhibitor (ML351, 50 mg/kg) or its solvent (DMSO) was injected i.p. at recanalization after 1 h of occlusion. Mice were sacrificed at 6, 24, and 72-h after ischemia induction. Infarct volumes were calculated on Nissl-stained sections. Neurological deficit scoring was used for functional analysis. Lipid peroxidation was determined by the MDA assay, and the inflammatory cytokines IL-6, TNF-alpha, IL-1beta, IL-10, and TGF-beta were quantified by ELISA. The inflammasome proteins NLRP1 and NLRP3, 12/15-LOX, and caspase-1 were detected with immunofluorescence staining.

Results

Infarct volumes, neurological deficit scores, and lipid peroxidation were significantly attenuated in ML351-treated groups at 6, 24, and 72-h. ELISA results revealed that the pro-inflammatory cytokines IL-1beta, IL-6, and TNF-alpha were significantly decreased at 6-h and/or 24-h of I/R, while the anti-inflammatory cytokines IL-10 and TNF-alpha were increased at 24-h or 72-h of ML351 treatment. NLRP1 and NLRP3 immunosignaling were enhanced at three time points after I/R, which were significantly diminished by the ML351 application. Interestingly, NLRP3 immunoreactivity was more pronounced than NLRP1. Hence, we proceeded to study the co-localization of NLRP3 immunoreactivity with 12/15-LOX and caspase-1, which indicated that NLRP3 was co-localized with 12/15-LOX and caspase-1 signaling. Additionally, NLRP3 was found in neurons at all time points but in non-neuronal cells 72 h after I/R.

Discussion

These results suggest that 12/15-LOX inhibition suppresses ischemia-induced inflammation in the acute and subacute phases of stroke via suppressing inflammasome activation. Understanding the mechanisms underlying lipid peroxidation and its associated pathways, like inflammasome activation, may have broader implications for the treatment of stroke and other neurological diseases characterized by neuroinflammation.

NLR family pyrin domain containing 3 (NLRP3) inflammasomes and peripheral neuropathic pain - Emphasis on microRNAs (miRNAs) as important regulators

Neuropathic pain is caused by the lesion or disease of the somatosensory system and can be initiated and/or maintained by both central and peripheral mechanisms. Nerve injury leads to neuronal damage and apoptosis associated with the release of an array of pathogen- or damage-associated molecular patterns to activate inflammasomes. The activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome contributes to neuropathic pain and may represent a novel target for pain therapeutic development. In the current review, we provide an up-to-date summary of the recent findings on the involvement of NLRP3 inflammasome in modulating neuropathic pain development and maintenance, focusing on peripheral neuropathic conditions. Here we provide a detailed review of the mechanisms whereby NLRP3 inflammasomes contribute to neuropathic pain via (1) neuroinflammation, (2) apoptosis, (3) pyroptosis, (4) proinflammatory cytokine release, (5) mitochondrial dysfunction, and (6) oxidative stress. We then present the current research literature reporting on the antinociceptive effects of several natural products and pharmacological interventions that target activation, expression, and/or regulation of NLRP3 inflammasome. Furthermore, we emphasize the effects of microRNAs as another regulator of NLRP3 inflammasome. In conclusion, we summarize the possible caveats and future perspectives that might provide successful therapeutic approaches against NLRP3 inflammasome for treating or preventing neuropathic pain conditions.

Inhibiting NLRP3 inflammasome signaling pathway promotes neurological recovery following hypoxic-ischemic brain damage by increasing p97-mediated surface GluA1-containing AMPA receptors

BACKGROUND

The nucleotide-binding oligomeric domain (NOD)-like receptor protein 3 (NLRP3) inflammasome is believed to be a key mediator of neuroinflammation and subsequent secondary brain injury induced by ischemic stroke. However, the role and underlying mechanism of the NLRP3 inflammasome in neonates with hypoxic-ischemic encephalopathy (HIE) are still unclear.

METHODS

The protein expressions of the NLRP3 inflammasome including NLRP3, cysteinyl aspartate specific proteinase-1 (caspase-1) and interleukin-1β (IL-1β), the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionicacid receptor (AMPAR) subunit, and the ATPase valosin-containing protein (VCP/p97), were determined by Western blotting. The interaction between p97 and AMPA glutamate receptor 1 (GluA1) was determined by co-immunoprecipitation. The histopathological level of hypoxic-ischemic brain damage (HIBD) was determined by triphenyltetrazolium chloride (TTC) staining. Polymerase chain reaction (PCR) and Western blotting were used to confirm the genotype of the knockout mice. Motor functions, including myodynamia and coordination, were evaluated by using grasping and rotarod tests. Hippocampus-dependent spatial cognitive function was measured by using the Morris-water maze (MWM).

RESULTS

We reported that the NLRP3 inflammasome signaling pathway, such as NLRP3, caspase-1 and IL-1β, was activated in rats with HIBD and oxygen-glucose deprivation (OGD)-treated cultured primary neurons. Further studies showed that the protein level of the AMPAR GluA1 subunit on the hippocampal postsynaptic membrane was significantly decreased in rats with HIBD, and it could be restored to control levels after treatment with the specific caspase-1 inhibitor AC-YVAD-CMK. Similarly, in vitro studies showed that OGD reduced GluA1 protein levels on the plasma membrane in cultured primary neurons, whereas AC-YVAD-CMK treatment restored this reduction. Importantly, we showed that OGD treatment obviously enhanced the interaction between p97 and GluA1, while AC-YVAD-CMK treatment promoted the dissociation of p97 from the GluA1 complex and consequently facilitated the localization of GluA1 on the plasma membrane of cultured primary neurons. Finally, we reported that the deficits in motor function, learning and memory in animals with HIBD, were ameliorated by pharmacological intervention or genetic ablation of caspase-1.

CONCLUSION

Inhibiting the NLRP3 inflammasome signaling pathway promotes neurological recovery in animals with HIBD by increasing p97-mediated surface GluA1 expression, thereby providing new insight into HIE therapy.

Scutellaria baicalensis Attenuated Neurological Impairment by Regulating Programmed Cell Death Pathway in Ischemic Stroke Mice

Stroke is a major global health problem that causes significant mortality and long-term disability. Post-stroke neurological impairment is a complication that is often underestimated with the risk of persistent neurological deficits. Although traditional Chinese medicines have a long history of being used for stroke, their scientific efficacy remains unclear. Scutellaria baicalensis, an herbal component known for its anti-inflammatory and antioxidant properties, has traditionally been used to treat brain disorders. This study investigated the therapeutic effects of the Scutellaria baicalensis extraction (SB) during the acute stage of ischemic stroke using photothrombotic (PTB)-induced and transient middle cerebral artery occlusion (tMCAO) model mice. We found that SB mitigated ischemic brain injury, as evidenced by a significant reduction in the modified neurological severity score in the acute stage of PTB and both the acute and chronic stages of tMCAO. Furthermore, we elucidated the regulatory role of SB in the necroptosis and pyroptosis pathways during the acute stage of stroke, underscoring its protective effects. Behavioral assessments demonstrated the effectiveness of SB in ameliorating motor dysfunction and cognitive impairment compared to the group receiving the vehicle. Our findings highlight the potential of SB as a promising therapeutic candidate for stroke. SB was found to help modulate the programmed cell death pathways, promote neuroprotection, and facilitate functional recovery.

Role and regulatory mechanism of microRNA mediated neuroinflammation in neuronal system diseases

MicroRNAs (miRNAs) are small non-coding RNAs with the unique ability to degrade or block specific RNAs and regulate many cellular processes. Neuroinflammation plays the pivotal role in the occurrence and development of multiple central nervous system (CNS) diseases. The ability of miRNAs to enhance or restrict neuroinflammatory signaling pathways in CNS diseases is an emerging and important research area, including neurodegenerative diseases, stroke, and traumatic brain injury (TBI). In this review, we summarize the roles and regulatory mechanisms of recently identified miRNAs involved in neuroinflammation-mediated CNS diseases, aiming to explore and provide a better understanding and direction for the treatment of CNS diseases.

Viral-induced neuronal necroptosis: Detrimental to brain function and regulation by necroptosis inhibitors

Neuronal necroptosis (programmed necrosis) in the CNS naturally occurs through a caspase-independent way and, especially in neurodegenerative diseases (NDDs) such as Alzheimer's disease (AD), Parknson's disease (PD), Amyotrophic Lateral Sclerosis (ALS) and viral infections. Understanding necroptosis pathways (death receptor-dependent and independent), and its connections with other cell death pathways could lead to new insights into treatment. Receptor-interacting protein kinase (RIPK) mediates necroptosis via mixed-lineage kinase-like (MLKL) proteins. RIPK/MLKL necrosome contains FADD, procaspase-8-cellular FLICE-inhibitory proteins (cFLIPs), RIPK1/RIPK3, and MLKL. The necrotic stimuli cause phosphorylation of MLKL and translocate to the plasma membrane, causing an influx of Ca2+ and Na+ ions and, the immediate opening of mitochondrial permeability transition pore (mPTP) with the release of inflammatory cell damage-associated molecular patterns (DAMPs) like mitochondrial DNA (mtDNA), high-mobility group box1 (HMGB1), and interleukin1 (IL-1). The MLKL translocates to the nucleus to induce transcription of the NLRP3 inflammasome complex elements. MLKL-induced NLRP3 activity causes caspase-1 cleavage and, IL-1 activation which promotes neuroinflammation. RIPK1-dependent transcription increases illness-associated microglial and lysosomal abnormalities to facilitate amyloid plaque (Aβ) aggregation in AD. Recent research has linked neuroinflammation and mitochondrial fission with necroptosis. MicroRNAs (miRs) such as miR512-3p, miR874, miR499, miR155, and miR128a regulate neuronal necroptosis by targeting key components of necroptotic pathways. Necroptosis inhibitors act by inhibiting the membrane translocation of MLKL and RIPK1 activity. This review insights into the RIPK/MLKL necrosome-NLRP3 inflammasome interactions during death receptor-dependent and independent neuronal necroptosis, and clinical intervention by miRs to protect the brain from NDDs.

Potential regulatory effects of stem cell exosomes on inflammatory response in ischemic stroke treatment

The high incidence and disability rates of stroke pose a heavy burden on society. Inflammation is a significant pathological reaction that occurs after an ischemic stroke. Currently, therapeutic methods, except for intravenous thrombolysis and vascular thrombectomy, have limited time windows. Mesenchymal stem cells (MSCs) can migrate, differentiate, and inhibit inflammatory immune responses. Exosomes (Exos), which are secretory vesicles, have the characteristics of the cells from which they are derived, making them attractive targets for research in recent years. MSC-derived exosomes can attenuate the inflammatory response caused by cerebral stroke by modulating damage-associated molecular patterns. In this review, research on the inflammatory response mechanisms associated with Exos therapy after an ischemic injury is discussed to provide a new approach to clinical treatment.

A comprehensive review of stroke-related signaling pathways and treatment in western medicine and traditional Chinese medicine

This review provides insight into the complex network of signaling pathways and mechanisms involved in stroke pathophysiology. It summarizes the historical progress of stroke-related signaling pathways, identifying potential interactions between them and emphasizing that stroke is a complex network disease. Of particular interest are the Hippo signaling pathway and ferroptosis signaling pathway, which remain understudied areas of research, and are therefore a focus of the review. The involvement of multiple signaling pathways, including Sonic Hedgehog (SHH), nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE), hypoxia-inducible factor-1α (HIF-1α), PI3K/AKT, JAK/STAT, and AMPK in pathophysiological mechanisms such as oxidative stress and apoptosis, highlights the complexity of stroke. The review also delves into the details of traditional Chinese medicine (TCM) therapies such as Rehmanniae and Astragalus, providing an analysis of the recent status of western medicine in the treatment of stroke and the advantages and disadvantages of TCM and western medicine in stroke treatment. The review proposes that since stroke is a network disease, TCM has the potential and advantages of a multi-target and multi-pathway mechanism of action in the treatment of stroke. Therefore, it is suggested that future research should explore more treasures of TCM and develop new therapies from the perspective of stroke as a network disease.

Modulation of gut microbiota alleviates cerebral ischemia/reperfusion injury in rats by inhibiting M1 polarization of microglia

Gut microbiota affects the gut-brain axis; hence, the modulation of the microbiota has been proposed as a potential therapeutic strategy for cerebral ischemia/reperfusion injury (CIRI). However, the role and mechanism of the gut microbiota in regulating microglial polarization during CIRI remain poorly understood. Herein, using a middle cerebral artery occlusion and reperfusion (MCAO/R) rat model, we evaluated changes in the gut microbiota after CIRI and the potential effects of fecal microbiota transplant (FMT) on the brain. Rats underwent either MCAO/R or sham surgery, and then they received FMT (started 3 days later; continued for 10 days). 2,3,5-Triphenyltetrazolium chloride staining, neurological outcome scale, and Fluoro-Jade C staining showed that MCAO/R induced cerebral infarction, neurological deficits, and neuronal degeneration. In addition, immunohistochemistry or real-time PCR assay showed increased expression levels of M1-macrophage markers-TNF-α, IL-1β, IL-6, and iNOS-in the rats following MCAO/R. Our finding suggests that microglial M1 polarization is involved in CIRI. 16 S ribosomal RNA gene sequencing data revealed an imbalance in the gut microbiota of MCAO/R animals. In contrast, FMT reversed this MCAO/R-induced imbalance in the gut microbiota and ameliorated nerve injury. In addition, FMT prevented the upregulation in the ERK and NF-κB pathways, which reversed the M2-to-M1 microglial shift 10 days after MCAO/R injury in rats. Our primary data showed that the modulation of the gut microbiota can attenuate CIRI in rats by inhibiting microglial M1 polarization through the ERK and NF-κB pathways. However, an understanding of the underlying mechanism requires further study.

The Impact of microRNAs on Mitochondrial Function and Immunity: Relevance to Parkinson's Disease

Parkinson's Disease (PD), the second most common neurodegenerative disorder, is characterised by the severe loss of dopaminergic neurons in the Substantia Nigra pars compacta (SNpc) and by the presence of Lewy bodies. PD is diagnosed upon the onset of motor symptoms, such as bradykinesia, resting tremor, rigidity, and postural instability. It is currently accepted that motor symptoms are preceded by non-motor features, such as gastrointestinal dysfunction. In fact, it has been proposed that PD might start in the gut and spread to the central nervous system. Growing evidence reports that the gut microbiota, which has been found to be altered in PD patients, influences the function of the central and enteric nervous systems. Altered expression of microRNAs (miRNAs) in PD patients has also been reported, many of which regulate key pathological mechanisms involved in PD pathogenesis, such as mitochondrial dysfunction and immunity. It remains unknown how gut microbiota regulates brain function; however, miRNAs have been highlighted as important players. Remarkably, numerous studies have depicted the ability of miRNAs to modulate and be regulated by the host's gut microbiota. In this review, we summarize the experimental and clinical studies implicating mitochondrial dysfunction and immunity in PD. Moreover, we gather recent data on miRNA involvement in these two processes. Ultimately, we discuss the reciprocal crosstalk between gut microbiota and miRNAs. Studying the bidirectional interaction of gut microbiome-miRNA might elucidate the aetiology and pathogenesis of gut-first PD, which could lead to the application of miRNAs as potential biomarkers or therapeutical targets for PD.

The Potential of NLRP3 Inflammasome as a Therapeutic Target in Neurological Diseases

NLRP3 (NLRP3: NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome is the best-described inflammasome that plays a crucial role in the innate immune system and a wide range of diseases. The intimate association of NLRP3 with neurological disorders, including neurodegenerative diseases and strokes, further emphasizes its prominence as a clinical target for pharmacological intervention. However, after decades of exploration, the mechanism of NLRP3 activation remains indefinite. This review highlights recent advances and gaps in our insights into the regulation of NLRP3 inflammasome. Furthermore, we present several emerging pharmacological approaches of clinical translational potential targeting the NLRP3 inflammasome in neurological diseases. More importantly, despite small-molecule inhibitors of the NLRP3 inflammasome, we have focused explicitly on Chinese herbal medicine and botanical ingredients, which may be splendid therapeutics by inhibiting NLRP3 inflammasome for central nervous system disorders. We expect that we can contribute new perspectives to the treatment of neurological diseases.

Chronic cerebral hypoperfusion alters the CypA-EMMPRIN-gelatinase pathway: Implications for vascular dementia

Chronic cerebral hypoperfusion (CCH) is postulated to underlie multiple pathophysiological processes in vascular dementia (VaD), including extracellular matrix dysfunction. While several extracellular matrix proteins, namely cyclophilin A (CypA), extracellular matrix metalloproteinase inducer (EMMPRIN) and gelatinases (matrix metalloproteinases, MMP-2 and -9) have been investigated in acute stroke, their involvement in CCH and VaD remains unclear. In this study, CypA-EMMPRIN-gelatinase proteins were analysed in a clinical cohort of 36 aged, cognitively unimpaired subjects and 48 VaD patients, as well as in a bilateral carotid artery stenosis mouse model of CCH. Lower CypA and higher EMMPRIN levels were found in both VaD serum and CCH mouse brain. Furthermore, gelatinases were differentially altered in CCH mice and VaD patients, with significant MMP-2 increase in CCH brain and serum, whilst serum MMP-9 was elevated in VaD but reduced in CCH, suggesting complex CypA-EMMPRIN-gelatinase regulatory mechanisms. Interestingly, subjects with cortical infarcts had higher serum MMP-2, while white matter hyperintensities, cortical infarcts and lacunes were associated with higher serum MMP-9. Taken together, our data indicate that perturbations of CypA-EMMPRIN signalling may be associated with gelatinase-mediated vascular sequelae, highlighting the potential utility of the CypA-EMMPRIN-gelatinase pathway as clinical biomarkers and therapeutic targets in VaD.

Scutellarin Acts via MAPKs Pathway to Promote M2 Polarization of Microglial Cells

Scutellarin, an herbal agent, is known to possess anti-oxidant and anti-inflammatory properties. In activated microglia, it has been reported that this is achieved through acting on the MAPKs, a key pathway that regulates microglia activation. This study sought to determine if scutellarin would affect the commonly described microglia phenotypes, namely, M1 and M2, thought to contribute to pro- and anti-inflammatory roles, respectively. This is in consideration of its potential effect on the polarization of microglia phenotypes that are featured prominently in cerebral ischemia. For this purpose, we have used an experimentally induced cerebral ischemia rat model and LPS-stimulated BV-2 cell model. Thus, by Western blot and immunofluorescence, we show here a noticeable increase in expression of M2 microglia markers, namely, CD206, Arg1, YM1/2, IL-4 and IL-10 in activated microglia both in vivo and in vitro. Besides, we have confirmed that Scutellarin upregulated expression of Arg1, IL-10 and IL-4 in medium supernatants of BV-2 microglia. Remarkably, scutellarin treatment markedly augmented the increased expression of the respective markers in activated microglia. It is therefore suggested scutellarin can exert the polarization of activated microglia from M1 to M2 phenotype. Because M1 microglia are commonly known to be proinflammatory, while M2 microglia are anti-inflammatory and neuroprotective effect, it stands to reason therefore that with the increase of M2 microglia which became predominant by scutellarin, the local inflammatory response is ameliorated. More importantly, we have found that scutellarin promotes the M2 polarization through inhibiting the JNK and p38 signaling pathways, and concomitantly augmenting the ERK1/2 signaling pathway. This lends its strong support from observations in LPS activated BV-2 microglia treated with p38 and JNK inhibitors in which expression of M2 markers was increased; on the other hand, in cells subjected to ERK1/2 inhibitor treatment, the expression was suppressed. In light of the above, MAPKs pathway is deemed to be a potential therapeutic target of scutellarin in mitigating microglia mediated neuroinflammation in activated microglia.

An emerging role of inflammasomes in spinal cord injury and spinal cord tumor

Spinal cord injury (SCI) and spinal cord tumor are devastating events causing structural and functional impairment of the spinal cord and resulting in high morbidity and mortality; these lead to a psychological burden and financial pressure on the patient. These spinal cord damages likely disrupt sensory, motor, and autonomic functions. Unfortunately, the optimal treatment of and spinal cord tumors is limited, and the molecular mechanisms underlying these disorders are unclear. The role of the inflammasome in neuroinflammation in diverse diseases is becoming increasingly important. The inflammasome is an intracellular multiprotein complex and participates in the activation of caspase-1 and the secretion of pro-inflammatory cytokines such as interleukin (IL)-1β and IL-18. The inflammasome in the spinal cord is involved in the stimulation of immune-inflammatory responses through the release of pro-inflammatory cytokines, thereby mediating further spinal cord damage. In this review, we highlight the role of inflammasomes in SCI and spinal cord tumors. Targeting inflammasomes is a promising therapeutic strategy for the treatment of SCI and spinal cord tumors.

The study of chemical components in Qishiwei Zhenzhu pills and its anti-apoptotic mechanism in cerebral ischemic based on LC-MS and network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Qishiwei Zhenzhu pills are one of the most representative precious treasure proprietary medicines and have been used for nearly 500 years in clinical practice in Chinese. This medicine can prevent diseases and play a certain role in fighting altitude sickness with cerebral ischemia.

AIM OF THE STUDY

This study used LC-MS to analyse the chemical constituents of Qishiwei Zhenzhu pills, which laid a foundation for the improvement of the quality standard and the basic research of pharmacodynamics substances. This study aims to reveal the mechanism of Qishiwei Zhenzhu pills on cerebral ischemia from the perspective of the inflammatory and apoptotic pathway.

MATERIALS AND METHOD

UPLC-Q-TOF-MS was used to analyse the chemical constituents of Qishiwei Zhenzhu pills qualitatively. HPLC-QQQ-MS was used to analyse the contents of Qishiwei Zhenzhu pills quantitatively. The therapeutic target and pathway of Qishiwei Zhenzhu pills in the treatment of ischemic stroke were predicted on the basis of network pharmacology. On the basis of the MCAO rat model, the cerebral infarction rate (TTC staining) and the number of Nissl bodies (toluidine blue staining) were measured, the pathological morphologies of cortex and hippocampus were observed (HE staining), and the mRNA levels were determined by RT-PCR. The protein expressions of Bax, Bcl-2, and Caspase3 in the ischemic brain tissue of rats were determined using the WB method.

RESULTS

A total of 42 chemical constituents, including 11 triterpenoids, 10 flavonoids, 8 organic acids and their derivatives, 4 diterpenoids, 4 tannins, 2 steroids, and 3 other components, were identified from Qishiwei Zhenzhu pills by UPLC-Q-TOF-MS. HPLC-QQQ-MS results found that among the 16 different batches, the content difference between the two batches of preparations with the national drug approval number was small and that the quality was stable. However, significant differences were observed among the preparations of nine medical institutions. Network pharmacology study found that the effect of Qishiwei Zhenzhu pills might be related to the AGE-rage and tumour necrosis factor signalling pathways. Qishiwei Zhenzhu pills could improve the neurobehavioral abnormalities of MCAO rats, reduce the rate of cerebral infarction, improve the pathological changes in the hippocampal area of brain tissue, and increase the number of Nissl body in the brain tissue. Qishiwei Zhenzhu pills tended to reduce the mRNA transcription levels of Bax, Caspase-3, p65, c-fos and VEGF-A and increase the expression of Bcl-2 and MAPK8 mRNA. Moreover, the Bax protein expression tended to decrease, and the bcl-2 protein expression tended to increase.

CONCLUSIONS

A total of 42 chemical components were qualitatively identified from Qishiwei Zhenzhu pills, and 16 chemical components from 16 batches were determined. These components improved the quality standard level of Qishiwei Zhenzhu pills and provided reference for the later exploration of its pharmacodynamics substance basis. The protective mechanism of Qishiwei Zhenzhu pills against ischemic stroke might be related to the downregulation of the apoptosis factor caspase-3.

Escin alleviates stress-induced intestinal dysfunction to protect brain injury by regulating the gut-brain axis in ischemic stroke rats

Hyperactivity of HPA axis results in intestinal dysfunction, which may play a role in brain injury caused by ischemic stroke (IS). Escin shows a neuroprotective effect but it may not penetrate blood brain barrier (BBB). Previous work in our laboratory showed that escin ameliorated intestinal injury in animals. The aim of this study is to investigate whether escin attenuates brain injury by improving intestinal dysfunction in middle cerebral artery occlusion (MCAO) rats, to mimic IS. MCAO rats and lipopolysaccharides (LPS)-induced Caco-2 cells were used to evaluate the effects of escin in vivo and in vitro. The results showed that escin could not penetrate BBB but reduced brain infarct volume, improved neurological function, inhibited neuroinflammation, ameliorated intestinal dysfunction and tissue integrity by increasing the expression of the tight junction protein in vivo and in vitro. Escin reduced the increased corticosterone and endotoxin level in blood of MCAO rats, regulated GR/p38 MAPK/NF-κB signaling pathway in ileal tissue and LPS/TLR4/NF-κB signaling pathway in ischemic brain tissue. These findings suggest that escin could attenuate ischemic brain injury by improving intestinal dysfunction, and it may be a promising way to protect brain injury by protecting intestine, instead of targeting the brain directly after IS.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Research progress on pyroptosis-mediated immune-inflammatory response in ischemic stroke and the role of natural plant components as regulator of pyroptosis: A review

Ischemic stroke (IS) is one of the leading causes of death and disability. Its pathogenesis is not completely clear, and inflammatory cascade is one of its main pathological processes. The current clinical practice of IS is to restore the blood supply to the ischemic area after IS as soon as possible through thrombolytic therapy to protect the vitality and function of neurons. However, blood reperfusion further accelerates ischemic damage and cause ischemia-reperfusion injury. The pathological process of cerebral ischemia-reperfusion injury involves multiple mechanisms, and the exact mechanism has not been fully elucidated. Pyroptosis, a newly discovered form of inflammatory programmed cell death, plays an important role in the initiation and progression of inflammation. It is a pro-inflammatory programmed death mediated by caspase Caspase-1/4/5/11, which can lead to cell swelling and rupture, release inflammatory factors IL-1β and IL-18, and induce an inflammatory cascade. Recent studies have shown that pyroptosis and its mediated inflammatory response are important factors in aggravating ischemic brain injury, and inhibition of pyroptosis may alleviate the ischemic brain injury. Furthermore, studies have found that natural plant components may have a regulatory effect on pyroptosis. Therefore, this review not only summarizes the molecular mechanism of pyroptosis and its role in ischemic stroke, but also the role of natural plant components as regulator of pyroptosis, in order to provide reference information on pyroptosis for the treatment of IS in the future.

Study on insulin resistance and ischemic cerebrovascular disease: A bibliometric analysis via CiteSpace

Background

It is reported that insulin resistance widely exists in non-diabetic patients with a recent history of transient ischemic attack (TIA) or ischemic stroke. There is currently strong evidence to prove the bidirectional effect of glucose metabolism disorders and stroke events. Therefore, it is necessary to retrospectively tease out the current status, hotspots, and frontiers of insulin resistance and ischemic cerebrovascular disease through CiteSpace.

Materials and methods

We searched the Web of Science (WOS) for studies related to insulin resistance and ischemic cerebrovascular disease from 1999 to April 2022, then downloaded the data into CiteSpace to generate a knowledge visualization map.

Results

A total of 1,500 publications relevant to insulin resistance and ischemic cerebrovascular disease were retrieved. The USA had the most articles on this topic, followed by PEOPLES R CHINA and JAPAN. WALTER N KERNAN was the most prolific author, whose research mainly focused on insulin resistance intervention after stroke (IRIS) trial. The most common keywords were myocardial ischemia, metabolic syndrome, ischemic stroke, cerebral ischemia, association, oxidative stress, inflammation, and adipose tissue. Major ongoing research trends include three aspects: (1) the association between insulin resistance and ischemic cerebrovascular disease in non-diabetic patients, (2) the intrinsic pathological mechanism between insulin resistance and ischemic cerebrovascular disease, and (3) early intervention of insulin resistance to improve the prognosis of stroke.

Conclusion

The results of this bibliometric study provide the current status and trends of clinical research publications in the field of insulin resistance and ischemic cerebrovascular disease. Insulin resistance is strongly associated with the occurrence of ischemic stroke, early neurological deterioration in stroke patients, post-stroke depression, and cerebral small vessel disease. Early treatment of insulin resistance can be an effective way to prevent the onset of ischemic stroke and improve stroke prognosis. This study may help researchers to identify hot topics and explore new research directions.

Postbiotic muramyl dipeptide alleviates colitis via activating autophagy in intestinal epithelial cells

The pathogenesis of IBD is complicated and still unclear. Nucleotide-binding oligomerization domain 2 (NOD2) plays a significant role in regulating gut inflammation under the activation of muramyl dipeptide (MDP), which is used as a postbiotic. The study aimed to investigate the effect of MDP on the intestinal barrier in colitis and the mechanism involved. In this study, C57BL/6 mice were challenged with dextran sodium sulfate (DSS) for establishing a colitis model with the pre-treatment of MDP in vivo. Intestinal permeability was reflected by detecting the serum concentration of 4 kDa Fluorescein Isothiocyanate-Dextran. The expression of inflammation, barrier-related proteins, and autophagy was tested by Western Blotting. Proliferation and apoptosis in intestinal epithelial cells were detected by immunohistochemistry. Caco-2 cells were exposed to lipopolysaccharide for imitating inflammation in vitro. The findings showed that administration of MDP ameliorated losses of body weight loss, gross injury, and histology score of the colon in the DSS-induced colitis mice. MDP significantly ameliorated the condition of gut permeability, and promoted intestinal barrier repair by increasing the expression of Zonula occludens-1 and E-cadherin. Meanwhile, MDP promoted proliferation and reduced apoptosis of intestinal epithelial cells. In the experiment group treated with MDP, LC3 was upregulated, and p62 was downregulated, respectively. These results suggested that MDP stimulation attenuates intestinal inflammation both in vivo and in vitro. Potentially, MDP reduced the intestinal barrier damage by regulating autophagy in intestinal epithelial cells. Future trials investigating the effects of MDP-based postbiotics on IBD may be promising.