The role of NLRP3 inflammasome-mediated pyroptosis in ischemic stroke and the intervention of traditional Chinese medicine

Mesenchymal stem cells and their extracellular vesicles in bone and joint diseases: targeting the NLRP3 inflammasome

The nucleotide-binding oligomerization domain-like-receptor family pyrin domain-containing 3 (NLRP3) inflammasome is a cytosolic multi-subunit protein complex, and recent studies have demonstrated the vital role of the NLRP3 inflammasome in the pathological and physiological conditions, which cleaves gasdermin D to induce inflammatory cell death called pyroptosis and mediates the release of interleukin-1 beta and interleukin-18 in response to microbial infection or cellular injury. Over-activation of the NLRP3 inflammasome is associated with the pathogenesis of many disorders affecting bone and joints, including gouty arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis, and periodontitis. Moreover, mesenchymal stem cells (MSCs) have been discovered to facilitate the inhibition of NLRP3 and maybe ideal for treating bone and joint diseases. In this review, we implicate the structure and activation of the NLRP3 inflammasome along with the detail on the involvement of NLRP3 inflammasome in bone and joint diseases pathology. In addition, we focused on MSCs and MSC-extracellular vesicles targeting NLRP3 inflammasomes in bone and joint diseases. Finally, the existing problems and future direction are also discussed.

Ginsenoside Rb1 ameliorates apical periodontitis via suppressing macrophage pyroptosis

OBJECTIVES

The objectives of current study were to investigate the role and related mechanism of Ginsenoside Rb1 (GRb1) on regulating apical periodontitis (AP) prognosis.

MATERIALS AND METHODS

Clinical specimens were used to determine the involvement of calcium overload-induced macrophage pyroptosis in periapical tissues. Next, a calcium ion-chelating agent (BAPTA-AM) was applied to detect the suppression of intracellular calcium overload in macrophage pyroptosis. Then, network pharmacology, western blot (WB) analysis, and Fluo-4 calcium assay were conducted to explore the role of GRb1 on intracellular calcium overload. To gain a better understanding of GRb1 in calcium overload-induced macrophage pyroptosis linked AP, GRb1-treated AP models were established.

RESULTS

We discovered clinically and experimentally that calcium overload-dependent macrophage pyroptosis is involved in AP pathogenesis, and reducing calcium overload greatly decreased macrophage pyroptosis in an AP cell model. Next, based on GRb1's inhibitory role in aberrant intracellular calcium accumulation, we discovered that GRb1 alleviates AP by suppressing calcium-dependent macrophage pyroptosis in both in vitro and in vivo models.

CONCLUSIONS

GRb1 is an effective therapeutic strategy to rescue the periapical tissues from inflammation due to its anti-pyroptosis function. Thus, the present study supports further investigation of GRb1 as an adjuvant therapy for AP.

β-Caryophyllene mitigates ischemic stroke-induced white matter lesions by inhibiting pyroptosis

β-Caryophyllene (BCP), a selective agonist for cannabinoid receptor 2 (CB2R), has demonstrated promising protective effects in various pathological conditions. However, the neuroprotective effects of BCP on white matter damage induced by ischemic stroke have not been elucidated previously. In this study, we find that BCP not only improves sensorimotor and cognitive function via CB2R but also mitigates white matter lesions in mice following ischemic stroke. Furthermore, BCP enhances the viability of MO3.13 oligodendrocytes after oxygen-glucose deprivation and reoxygenation (OGD/R), attenuating OGD/R-induced cellular damage and pyroptosis. Notably, these protective effects of BCP are partially enhanced by the NLRP3 inhibitor MCC950 and counteracted by the NLRP3 activator nigericin. In addition, nigericin significantly exacerbates neurological outcomes and increases white matter lesions following BCP treatment in middle cerebral artery occlusion (MCAO) mice. These results suggest that BCP may ameliorate neurological deficits and white matter damage induced by cerebral ischemia through inhibiting NLRP3-mediated pyroptosis.

Electroacupuncture improves the learning and memory abilities of rats with PSCI by attenuating the TLR4/NF-κB/NLRP3 signaling pathway on the hippocampal microglia

This study aims to investigate how electroacupuncture regulates the learning and memory abilities of poststroke cognitive impairment (PSCI) rats through the TLR4/NF-κB/NLRP3 signaling pathway on the hippocampal microglia. Thirty male rats were randomly divided into three groups: sham surgery group, PSCI model group, and electroacupuncture group, with 10 rats in each group. Middle cerebral artery occlusion was used to establish the PSCI model. The Zea Longa method was used to score the rats' neurological function. Electroacupuncture was utilized for 21 days to improve PSCI. The learning and memory abilities of rats were tested using the Morris water maze. Hematoxylin-eosin staining and immunofluorescence were used to find the hippocampus' pathological changes. The concentration of interleukin-1β, interleukin-6, tumor necrosis factor-α, and interleukin-18 were detected by ELISA. The mRNA expression levels of associated inflammatory corpuscles were measured by quantitative real-time PCR. The protein expression levels of TLR4, MyD88, NF-κB, and NLRP3 were measured using western blotting. Electroacupuncture improved not only the learning and memory abilities of PSCI rats but also hippocampal morphology. Electroacupuncture inhibited the activation of microglia and the TLR4/NF-κB/NLRP3 signaling pathway. Electroacupuncture also reduced proinflammatory factors and restrained the mRNA levels of NLRP3-associated inflammatory cytokines. Its mechanism was related to inhibiting the expression of the TLR4/NF-κB/NLRP3 signaling pathway, attenuating the release of inflammatory factors, and regulating the activation of hippocampal microglia in the brain.

The role of heat shock protein B8 in neuronal protection against oxidative stress and mitochondrial dysfunction: A literature review

Excessive oxidative stress triggers cerebrovascular and neurodegenerative diseases resulting in acute and chronic brain injury. However, the underlying mechanisms remain unknown. Levels of small heat shock protein B8 (HSPB8), which is highly expressed in the brain, are known to be significantly elevated in cerebral injury models. Exogenous HSPB8 protects the brain against mitochondrial damage. One potential mechanism underlying this protection is that HSPB8 overexpression alleviates the mitochondria-dependent pathways of apoptosis; mitochondrial biogenesis, fission, and mitophagy. Overexpression of HSPB8 may therefore have potential as a clinical therapy for cerebrovascular and neurodegenerative diseases. This review provides an overview of advances in the protective effects of HSPB8 against excessive cerebral oxidative stress, including the modulation of mitochondrial dysfunction and potent signaling pathways.

Elabela ameliorates neuronal pyroptosis and mitochondrial fission via APJ/ZBP1 signaling in ischemic stroke

Pyroptosis signifies a significant form of programmed neuronal demise subsequent to ischemic stroke. In our prior investigations, we demonstrated that the Elabela (ELA)-Apelin receptor (APJ) axis alleviated neuronal death by improving collateral circulation and mitigating ferroptosis in a murine model of middle cerebral artery occlusion (MCAO). However, the connection between ELA and neuronal pyroptosis remains further elucidation. Here, we observed an upregulation of ELA and APJ expression in both murine brain specimens and cultured HT-22 hippocampal neurons exposed to experimental ischemic stroke. ELA administration markedly diminished the infarct size in comparison to controls. ELA treatment ameliorated neurological deficits and anxiety-like symptoms in mice with stroke, concurrently inhibiting pyroptosis and mitochondria fission in neurons. Conversely, ELA knockdown yielded the opposite effects. Utilizing RNA-sequencing analysis, we identified a candidate for pyroptosis priming, Z-DNA-binding protein 1 (ZBP1), which was suppressed in ELA-treated HT-22 neurons during oxygen-glucose deprivation/reperfusion (OGD/R). Subsequent co-immunoprecipitation analyses demonstrated the binding between APJ and ZBP1. Specifically, APJ suppressed ZBP1 to inhibit NLRP3 inflammasome activation and dynamin-related protein 1-mediated mitochondrial fission in neurons. In summary, our findings suggest that ELA functions as a stroke-induced signal limiting neuronal pyroptosis and mitochondrial fission via APJ/ZBP1 signaling, thereby underscoring ELA as a potential therapeutic target for ischemic stroke treatment.

ATP-sensitive potassium channel opener, Nicorandil, inhibits NF-κB/AIM2/GSDMD pathway activation to protect against neuroinflammation in ischemic stroke

The absent in melanoma 2 (AIM2) inflammasome contributes to ischemic brain injury by inducing cell pyroptosis and inflammatory responses. Our research group has previously demonstrated that ATP-sensitive potassium channels (KATP channels) openers can modulate neuronal synaptic plasticity post-ischemic stroke for neuroprotection. However, the specific mechanisms of KATP channels in the inflammatory response following ischemic stroke remain unclear. Here, we assessed cellular damage by observing changes in BV-2 morphology and viability. 2,3,5-Triphenyl tetrazolium chloride (TTC) staining, mNSS scoring, Nissl staining, and TdT-mediated dUTP nick end labeling (TUNEL) staining were used to evaluate behavioral deficits, brain injury severity, and neuronal damage in mice subjected to middle cerebral artery occlusion (MCAO). Quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) were used to measure cell pyroptosis and nuclear factor-kappaB (NF-κB) activation in vivo and in vitro. We observed that AIM2 protein expression was upregulated and localized within the cytoplasm of BV-2 cells. Notably, low-dose Nicorandil treatment reduced inflammatory cytokine secretion and pyroptosis-related protein expression, including AIM2, cleaved cysteinyl aspartate-specific protease-1 (cleaved caspase-1), and Gasdermin D N-terminal (GSDMD-NT). Further investigations revealed that the KATP channel inhibitor 5-HD upregulated p-NF-κB p65, NF-κB p65, and p-IκBα expression, reversing Nicorandil's neuroprotective effect in vivo. In summary, our results suggest that Nicorandil may serve as a potential therapeutic option for ischemic stroke. Targeting AIM2 and NF-κB represents effective strategies for inhibiting neuroinflammation.

ROS induced pyroptosis in inflammatory disease and cancer

Pyroptosis, a form of caspase-1-dependent cell death, also known as inflammation-dependent death, plays a crucial role in diseases such as stroke, heart disease, or tumors. Since its elucidation, pyroptosis has attracted widespread attention from various sectors. Reactive oxygen species (ROS) can regulate numerous cellular signaling pathways. Through further research on ROS and pyroptosis, the level of ROS has been revealed to be pivotal for the occurrence of pyroptosis, establishing a close relationship between the two. This review primarily focuses on the molecular mechanisms of ROS and pyroptosis in tumors and inflammatory diseases, exploring key proteins that may serve as drug targets linking ROS and pyroptosis and emerging fields targeting pyroptosis. Additionally, the potential future development of compounds and proteins that influence ROS-regulated cell pyroptosis is anticipated, aiming to provide insights for the development of anti-tumor and anti-inflammatory drugs.

Protective effects of pioglitazone in renal ischemia-reperfusion injury (RIRI): focus on oxidative stress and inflammation

BACKGROUND

Renal ischemia-reperfusion injury (RIRI) is a critical phenomenon that compromises renal function and is the most serious health concern related to acute kidney injury (AKI). Pioglitazone (Pio) is a known agonist of peroxisome proliferator-activated receptor-gamma (PPAR-γ). PPAR-γ is a nuclear receptor that regulates genes involved in inflammation, metabolism, and cellular differentiation. Activation of PPAR-γ is associated with antiinflammatory and antioxidant effects, which are relevant to the pathophysiology of RIRI. This study aimed to investigate the protective effects of Pio in RIRI, focusing on oxidative stress and inflammation.

METHODS

We conducted a comprehensive literature search using electronic databases, including PubMed, ScienceDirect, Web of Science, Scopus, and Google Scholar.

RESULTS

The results of this study demonstrated that Pio has antioxidant, anti-inflammatory, and anti-apoptotic activities that counteract the consequences of RIRI. The study also discussed the underlying mechanisms, including the modulation of various pathways such as TNF-α, NF-κB signaling systems, STAT3 pathway, KIM-1 and NGAL pathways, AMPK phosphorylation, and autophagy flux. Additionally, the study presented a summary of various animal studies that support the potential protective effects of Pio in RIRI.

CONCLUSION

Our findings suggest that Pio could protect the kidneys from RIRI by improving antioxidant capacity and decreasing inflammation. Therefore, these findings support the potential of Pio as a therapeutic strategy for preventing RIRI in different clinical conditions.

Investigating the Mechanistic of Danhong Injection in Brain Damage Caused by Cardiac I/R Injury via Bioinformatics, Computer Simulation, and Experimental Validation

OBJECTIVE

Cardiac ischemia-reperfusion (I/R) injury has negative effects on the brain and can even lead to the occurrence of ischemic stroke. Clinical evidence shows that Danhong injection (DHI) protects the heart and brain following ischemic events. This study investigated the mechanisms and key active compounds underlying the therapeutic effect of DHI against brain damage induced by cardiac I/R injury.

METHODS

The gene expression omnibus database provided GSE66360 and GSE22255 data sets. The R programming language was used to identify the common differentially expressed genes (cDEGs). Gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed, and protein-protein interaction network was constructed. Active compounds of DHI were collected from the Traditional Chinese Medicine Systems Pharmacology database. Molecular docking and molecular dynamics simulations were performed. The MMPBSA method was used to calculate the binding-free energy. The pkCSM server and DruLiTo software were used for Absorption, Distribution, metabolism, excretion, and toxicity (ADMET) analysis and drug-likeness analysis. Finally, in vitro experiments were conducted to validate the results.

RESULTS

A total of 27 cDEGs had been identified. The PPI and enrichment results indicated that TNF-α was considered to be the core target. A total of 80 active compounds were retrieved. The molecular docking results indicated that tanshinone I (TSI), tanshinone IIA (TSIIA), and hydroxyl safflower yellow A (HSYA) were selected as core active compounds. Molecular dynamics verification revealed that the conformations were relatively stable without significant fluctuations. MMPBSA analysis revealed that the binding energies of TSI, TSIIA, and HSYA with TNF-α were -36.01, -21.71, and -14.80 kcal/mol, respectively. LEU57 residue of TNF-α has the highest contribution. TSI and TSIIA passed both the ADMET analysis and drug-likeness screening, whereas HSYA did not. Experimental verification confirmed that DHI and TSIIA reduced the expression of TNF-α, NLRP3, and IL-1β in the injured H9C2 and rat brain microvascular endothelial cells.

CONCLUSION

TNF-α can be considered to be a key target for BD-CI/R. TSIIA in DHI exerts a significant inhibitory effect on the inflammatory damage of BD-CI/R, providing new insights for future drug development.

Knockdown of NR4A1 alleviates doxorubicin-induced cardiotoxicity through inhibiting the activation of the NLRP3 inflammasome

Doxorubicin (DOX) is a widely used antitumor drug, but its clinical applicability is hampered by the unfortunate side effect of DOX-induced cardiotoxicity (DIC). In our current study, we retrieved three high-throughput sequencing datasets related to DIC from the Gene Expression Omnibus (GEO) datasets. We conducted differential analysis using R (DESeq2) to pinpoint differentially expressed genes (DEGs, and identified 11 genes that were consistently altered in both the control and DOX-treated groups. Notably, our Random Forest analysis of these three GEO datasets highlighted the significance of nuclear receptor subfamily 4 group A member 1 (NR4A1) in the context of DIC. The DOX-induced mouse model and cell model were used for the in vivo and in vitro studies to reveal the role of NR4A1 in DIC. We found that silencing NR4A1 by adeno-associated virus serotype 9 (AAV9) contained shRNA in vivo alleviated the DOX-induced cardiac dysfunction, cardiomyocyte injury and fibrosis. Mechanistically, we found NR4A1 silencing was able to inhibit DOX-induced the cleavage of NLRP3, IL-1β and GSDMD in vivo. Further in vitro studies have shown that inhibition of NR4A1 suppressed DOX-induced cytotoxicity and oxidative stress through the same molecular mechanism. We prove that NR4A1 plays a critical role in DOX-induced cardiotoxicity by inducing pyroptosis via activation of the NLRP3 inflammasome, and it might be a promising therapeutic target for DIC.

Electroacupuncture Alleviates Cerebral Ischemia-reperfusion Injury by Regulating the S1PR2/TLR4/NLRP3 Signaling Pathway via m6A Methylation of lncRNA H19

Electroacupuncture (EA) treatment plays a protective role in cerebral ischemiareperfusion (CIR) injury. However, the underlying molecular mechanism is still not fully elucidated.

METHODS

All rats were randomly divided into five groups: the SHAM group, MCAO group, MCAO+EA (MEA) group, MCAO+METTL3 overexpression+EA (METTL3) group and MCAO+lncRNA H19 overexpression+EA (lncRNA H19) group. The middle cerebral artery occlusion (MCAO) rats were established to mimic CIR injury. The overexpression of lncRNA H19 and METTL3 was induced by stereotactic injection of lentiviruses into the rat lateral ventricles. The rats in the MEA, METTL3, and lncRNA H19 groups were treated with EA therapy on "Renzhong" (DU26) and "Baihui" (DU20) acupoints (3.85/6.25Hz; 1mA). Besides, the neurological deficit scoring, cerebral infarction area, pathological changes in brain tissue, total RNA m6A level, and the expression of METTL3, S1PR2, TLR4, NLRP3 and lncRNA H19 were detected in this experiment.

RESULTS

EA improved the neurological deficit scoring, cerebral infarction area, and pathological injury in MCAO rats, while these beneficial effects of EA on CIR injury were attenuated by the overexpression of METTL3 or lncRNA H19. More importantly, EA down-regulated the total RNA m6A level and the expression of METTL3, S1PR2, TLR4, NLRP3 and lncRNA H19 in MCAO rats. Instead, the overexpression of METTL3 or lncRNA H19 was found to reverse the EA-induced down-regulation.

CONCLUSION

The findings indicated that EA might down-regulate the S1PR2/TLR4/NLRP3 signaling pathway via m6A methylation of lncRNA H19 to alleviate CIR injury. Our findings provide a new insight into the molecular mechanism of EA on CIR injury.

Kynurenic acid inhibits macrophage pyroptosis by suppressing ROS production via activation of the NRF2 pathway

Macrophage pyroptosis and related inflammatory responses play an important role in periodontitis. Kynurenic acid (KA) is hypothesized to have anti‑inflammatory potential, but whether KA can inhibit macrophage pyroptosis and the underlying mechanisms remain unclear. Lipopolysaccharide (LPS) was used to induce pyroptosis in THP‑1‑derived macrophages. KA or ML385 was used to pretreat macrophages, after which, cell viability, NOD‑like receptor protein 3 (NLRP3) inflammasome‑related protein expression, oxidative stress levels and nuclear factor erythroid 2‑related factor 2 (NRF2) expression were measured. The results showed that KA improved the LPS‑induced decrease in macrophage viability and lactate dehydrogenase release. KA prevented THP‑1 macrophage pyroptosis induced by LPS by reducing the expression of NLRP3, Gasdermin‑D, and Caspase1, and decreased the expression of inflammatory factors. KA suppressed NLRP3 inflammasome activation by inhibiting ROS overproduction and increasing Heme Oxygenase 1 and glutathione levels. Moreover, KA promoted NRF2 translocation from the cytoplasm to the nucleus. In addition, the anti‑pyroptotic and antioxidant effects of KA were reversed by ML385 inhibition of NRF2. In the present study, it was found that KA significantly suppressed macrophage pyroptosis induced by LPS. It was further demonstrated that the anti‑pyroptotic effects of KA were mediated by activation of the NRF2 pathway.

Selenium alleviates lead-induced CIK cells pyroptosis and inflammation through IRAK1/TAK1/IKK pathway

The toxic heavy metal lead is widely found in rivers and soils as an environmental pollutant, posing a threat to the health of aquatic organisms. Selenium is an essential trace element and a powerful antioxidant that has been shown to have anti-inflammatory and antioxidant properties as well as alleviating heavy metal poisoning. Many studies have shown that lead poisoning produces inflammatory responses and damage to the kidneys of a wide range of animals, but the effects on cellular pyroptosis and immune function and selenium antagonism in CIK cells are not clear. In this study, 500 μM Pb and 20 nM Se were applied to grass carp kidney cells, and the results showed that Pb exposure to CIK cells resulted in oxidative stress, activation of the IRAK1/TAK1/IKK pathway, up-regulation of the expression of cellular pyroptosis markers GSDMD and NLRP3, and cellular pyroptosis of CIK cells, as well as up-regulation of IL-1β and IL-18, and the generation of cellular inflammatory response. In contrast, Se treatment significantly reduced the ROS level, the expression of cellular pyroptosis markers GSDMD, NLRP3 and inflammatory element IL-1β and IL-18. Taken together, Se alleviated cellular pyroptosis and immune dysfunction caused by Pb exposure through oxidative stress and activation of the IRAK1/TAK1/IKK pathway. This study complements the harmful effects of the heavy metal Pb on fish and the real-life application of selenium in the healthy culture of fish as a reference will be provided.