Pyroptosis: A Newly Discovered Therapeutic Target for Ischemia-Reperfusion Injury

E3 ubiquitin ligase MARCH1 reduces inflammation and pyroptosis in cerebral ischemia-reperfusion injury via PCSK9 downregulation

Pyroptosis has been regarded as caspase-1-mediated monocyte death that induces inflammation, showing a critical and detrimental role in the development of cerebral ischemia-reperfusion injury (IRI). MARCH1 is an E3 ubiquitin ligase that exerts potential anti-inflammatory functions. Therefore, the study probed into the significance of MARCH1 in inflammation and pyroptosis elicited by cerebral IRI. Middle cerebral artery occlusion/reperfusion (MCAO/R)-treated mice and oxygen glucose deprivation/reoxygenation (OGD/R)-treated hippocampal neurons were established to simulate cerebral IRI in vivo and in vitro. MARCH1 and PCSK9 expression was tested in MCAO/R-operated mice, and their interaction was identified by means of the cycloheximide assay and co-immunoprecipitation. The functional roles of MARCH1 and PCSK9 in cerebral IRI were subsequently determined by examining the neurological function, brain tissue changes, neuronal viability, inflammation, and pyroptosis through ectopic expression and knockdown experiments. PCSK9 expression was increased in the brain tissues of MCAO/R mice, while PCSK9 knockdown reduced brain damage and neurological deficits. Additionally, inflammation and pyroptosis were inhibited in OGD/R-exposed hippocampal neurons upon PCSK9 knockdown, accompanied by LDLR upregulation and NLRP3 inflammasome inactivation. Mechanistic experiments revealed that MARCH1 mediated ubiquitination and degradation of PCSK9, lowering PCSK9 protein expression. Furthermore, it was demonstrated that MARCH1 suppressed inflammation and pyroptosis after cerebral IRI by downregulating PCSK9 both in vivo and in vitro. Taken together, the present study demonstrate the protective effect of MARCH1 against cerebral IRI through PCSK9 downregulation, which might contribute to the discovery of new therapies for improving cerebral IRI.

The emerging role of regulated cell death in ischemia and reperfusion-induced acute kidney injury: current evidence and future perspectives

Renal ischemia‒reperfusion injury (IRI) is one of the main causes of acute kidney injury (AKI), which is a potentially life-threatening condition with a high mortality rate. IRI is a complex process involving multiple underlying mechanisms and pathways of cell injury and dysfunction. Additionally, various types of cell death have been linked to IRI, including necroptosis, apoptosis, pyroptosis, and ferroptosis. These processes operate differently and to varying degrees in different patients, but each plays a role in the various pathological conditions of AKI. Advances in understanding the underlying pathophysiology will lead to the development of new therapeutic approaches that hold promise for improving outcomes for patients with AKI. This review provides an overview of the recent research on the molecular mechanisms and pathways underlying IRI-AKI, with a focus on regulated cell death (RCD) forms such as necroptosis, pyroptosis, and ferroptosis. Overall, targeting RCD shows promise as a potential approach to treating IRI-AKI.

ALKBH5-mediated m6A demethylation of pri-miR-199a-5p exacerbates myocardial ischemia/reperfusion injury by regulating TRAF3-mediated pyroptosis

Myocardial ischemia‒reperfusion injury (MI/RI) is closely related to pyroptosis. alkB homolog 5 (ALKBH5) is abnormally expressed in the MI/RI models. However, the detailed molecular mechanism of ALKBH5 in MI/RI has not been elucidated. In this study, rats and H9C2 cells served as experimental subjects and received MI/R induction and H/R induction, respectively. The abundance of the targeted molecules was evaluated using RT-qPCR, Western blotting, immunohistochemistry, immunofluorescence, and enzyme-linked immunosorbent assay. The heart functions of the rats were evaluated using echocardiography, and heart injury was evaluated. Cell viability and pyroptosis were determined using cell counting Kit-8 and flow cytometry, respectively. Total m6A modification was measured using a commercial kit, and pri-miR-199a-5p m6A modification was detected by Me-RNA immunoprecipitation (RIP) assay. The interactions among the molecules were validated using RIP and luciferase experiments. ALKBH5 was abnormally highly expressed in H/R-induced H9C2 cells and MI/RI rats. ALKBH5 silencing improved injury and inhibited pyroptosis. ALKBH5 reduced pri-miR-199a-5p m6A methylation to block miR-199a-5p maturation and inhibit its expression. TNF receptor-associated Factor 3 (TRAF3) is a downstream gene of miR-199a-5p. Furthermore, in H/R-induced H9C2 cells, the miR-199a-5p inhibitor-mediated promotion of pyroptosis was reversed by ALKBH5 silencing, and the TRAF3 overexpression-mediated promotion of pyroptosis was offset by miR-199a-5p upregulation. ALKBH5 silencing inhibited pri-miR-199a-5p expression and enhanced pri-miR-199a-5p m6A modification to promote miR-199a-5p maturation and enhance its expression, thereby suppressing pyroptosis to alleviate MI/RI through decreasing TRAF3 expression.

Taohong Siwu decoction reduces acute myocardial ischemia-reperfusion injury by promoting autophagy to inhibit pyroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Taohong Siwu decoction (TSD) is a classic traditional Chinese medicine (TCM) prescription used to promote the blood circulation and alleviate blood stasis. TSD consists of Paeonia lactiflora Pall., Conioselinum anthriscoides (H. Boissieu) Pimenov & Kljuykov, Rehmannia glutinosa (Gaertn.) DC., Prunus persica (L.) Batsch, Angelica sinensis (Oliv.) Diels, and Carthamus creticus L. in the ratio of 3:2:4:3:3:2. Studies on the effects of TSD on myocardial ischemia-reperfusion injury (MIRI) from the perspective of autophagy and pyroptosis have not been reported.

AIM OF THE STUDY

Investigate the effect of TSD on MIRI and explore the underlying mechanisms.

MATERIALS AND METHODS

We searched the main components and corresponding potential targets of TSD on The Pharmacology of Traditional Chinese Medicine Systems database for target prediction. We identified targets for MIRI on Online Mendelian Inheritance in Man and GeneCards databases. The intersection of the compound target and disease target was obtained and a protein-protein interaction network constructed. We undertook enrichment analyses using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases. The results of network pharmacology were verified by in vivo experiments in mice.

RESULTS

In mice, TSD significantly reduced the volume of the myocardial infarct, significantly reduced serum levels of cardiac troponin-nI (CTnI), creatine kinase-myocardial band (CK-MB), malonaldehyde (MDA), interleukin (IL)-6, increased the activity of superoxide dismutase (SOD) and IL-10 level, reduced the level of pyroptosis in myocardial tissue, increased the number of autophagosomes, and significantly reduced the fluorescence intensity of apoptosis-associated speck-like protein (ASC), Nod-like receptor protein 3 (NLRP3), and caspase-1. TSD administration increased the protein expression of microtubule-associated protein light chain 3 (LC3), but reduced the protein expression of p62, NLRP3, ASC, caspase-1, cleaved caspase-1, pro-caspase-1, gasdermin D (GSDMD), GSDMD-N-terminal, IL-18, and IL-1β. Administration of 3-Methyladenin could reverse the effect of TSD in inhibiting inflammation and the release of proinflammatory factors.

CONCLUSION

TSD treatment alleviated MIRI by promoting autophagy to suppress activation of the NLRP3 inflammasome and reducing the release of proinflammatory factors.

Connexin32 gap junction channels deliver miR155-3p to mediate pyroptosis in renal ischemia-reperfusion injury

OBJECTIVES

To explore whether the gap junction (GJ) composed by connexin32(Cx32) mediated pyroptosis in renal ischemia-reperfusion(I/R) injury via transmitting miR155-3p, with aim to provide new strategies for the prevention and treatment of acute kidney injury (AKI) after renal I/R.

METHODS

8-10 weeks of male C57BL/ 6 wild-type mice and Cx32 knockdown mice were divided into two groups respectively: control group and renal I/R group. MCC950 (50 mg/kg. ip.) was used to inhibit NLRP3 in vivo. Human kidney tubular epithelial cells (HK - 2) and rat kidney tubular epithelial cells (NRK-52E) were divided into high-density group and low-density group, and treated with hypoxia reoxygenation (H/R) to mimic I/R. The siRNA and plasmid of Cx32, mimic and inhibitor of miR155-3p were transfected into HK - 2 cells respectively. Kidney pathological and functional injuries were measured. Western Blot and immunofluorescent staining were used to observe the expression of NLRP3, GSDMD, GSDMD-N, IL - 18, and mature IL-18. The secretion of IL-18 and IL-1β in serum, kidney tissue and cells supernatant were detected by enzyme-linked immuno sorbent assay (ELISA) kit, and the expression of NLPR3 and miR155-3p were detected by RT-qPCR and fluorescence in situ hybridization (FISH).

RESULTS

Tubular pyroptosis were found to promote AKI after I/R in vivo and Cx32-GJ regulated pyroptosis by affecting the expression of miR155-3p after renal I/R injury. In vitro, H/R could lead to pyroptosis in HK-2 and NRK-52E cells. When the GJ channels were not formed, and Cx32 was inhibited or knockdown, the expression of miR155-3p was significantly reduced and the pyroptosis was obviously inhibited, leading to the reduction of injury and the increase of survival rate. Moreover, regulating the level of miR155-3p could affect survival rate and pyroptosis in vitro after H/R.

CONCLUSIONS

The GJ channels composed of Cx32 regulated tubular pyroptosis in renal I/R injury by transmitting miR155-3p. Inhibition of Cx32 could reduce the level of miR155-3p further to inhibit pyroptosis, leading to alleviation of renal I/R injury which provided a new strategy for preventing the occurrence of AKI. Video Abstract.

Hydroxysafflor Yellow A Inhibits Pyroptosis and Protecting HUVECs from OGD/R via NLRP3/Caspase-1/GSDMD Pathway

OBJECTIVE

To observe the protective effect and mechanism of hydroxyl safflower yellow A (HSYA) from myocardial ischemia-reperfusion injury on human umbilical vein endothelial cells (HUVECs).

METHODS

HUVECs were treated with oxygen-glucose deprivation reperfusion (OGD/R) to simulate the ischemia reperfusion model, and cell counting kit-8 was used to detect the protective effect of different concentrations (1.25-160 µ mol/L) of HSYA on HUVECs after OGD/R. HSYA 80 µ mol/L was used for follow-up experiments. The contents of inflammatory cytokines interleukin (IL)-18, IL-1 β, monocyte chemotactic protein 1 (MCP-1), tumor necrosis factor α (TNF-α) and IL-6 before and after administration were measured by enzyme-linked immunosorbent assay. The protein expressions of toll-like receptor, NOD-like receptor containing pyrin domain 3 (NLRP3), gasdermin D (GSDMD) and GSDMD-N-terminal domain (GSDMD-N) before and after administration were detected by Western blot. NLRP3 inflammasome inhibitor cytokine release inhibitory drug 3 sodium salt (CRID3 sodium salt, also known as MCC950) and agonist were added, and the changes of NLRP3, cysteine-aspartic acid protease 1 (Caspase-1), GSDMD and GSDMD-N protein expressions were detected by Western blot.

RESULTS

HSYA inhibited OGD/R-induced inflammation and significantly decreased the contents of inflammatory cytokines IL-18, IL-1 β, MCP-1, TNF-α and IL-6 (P<0.01 or P<0.05). At the same time, by inhibiting NLRP3/Caspase-1/GSDMD pathway, HSYA can reduce the occurrence of pyroptosis after OGD/R and reduce the expression of NLRP3, Caspase-1, GSDMD and GSDMD-N proteins (P<0.01).

CONCLUSIONS

The protective effect of HSYA on HUVECs after OGD/R is related to down-regulating the expression of NLRP3 inflammasome and inhibiting pyroptosis.

Non-coding RNAs modulate pyroptosis in myocardial ischemia-reperfusion injury: A comprehensive review

Reperfusion therapy is the most effective treatment for acute myocardial infarction. However, reperfusion itself can also cause cardiomyocytes damage. Pyroptosis has been shown to be an important mode of myocardial cell death during ischemia-reperfusion. Non-coding RNAs (ncRNAs) play critical roles in regulating pyroptosis. The regulation of pyroptosis by microRNAs, long ncRNAs, and circular RNAs may represent a new mechanism of myocardial ischemia-reperfusion injury. This review summarizes the currently known regulatory roles of ncRNAs in myocardial ischemia-reperfusion injury and interactions between ncRNAs. Potential therapeutic strategies using ncRNA modulation are also discussed.

Identification of biomarkers of renal ischemia-reperfusion injury by bioinformatics analysis and single-cell sequencing analysis combined with in vivo validation

BACKGROUND

Renal ischemia-reperfusion injury (IRI) is a serious clinical complication of kidney injury. This research dealt with investigating the hub genes and pathways associated with renal IRI.

METHODS

The transcriptome expression dataset of mouse renal ischemia samples (GSE39548) was obtained from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were filtered by R software for key genes utilized for gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and gene enrichment analysis (GSEA). The gene co-expression network was developed by WGCNA analysis to screen important modules. Hub genes from the intersection of DEGs and WGCNA were subjected to protein-protein interaction (PPI) network. The biomarkers obtained by SVM-REF and LASSO algorithm were validated by other datasets and subjected to GSEA analysis. The expression of biomarkers in renal IRI was detected by qRT-PCR and subjected to single-cell analysis.

RESULTS

A total of 157 DEGs were discovered. Biological function analysis depicted that the DEGs were primarily involved in cytokine-cytokine receptor interaction, as well as the signaling pathways IL-17, MAPK, and TNF. The intersection of DEGs and the genes obtained by WGCNA analysis yielded 149 hubs genes. Based on SVM-REF and LASSO algorithm, cyp1a1 and pdk4 were determined as potential biomarkers in individuals with renal ischemia and showed good diagnostic value. qRT-PCR results depicted that cyp1a1 and pdk4 were significantly up-regulated in renal ischemia mice (P < 0.05). Finally, the single-cell analysis identified the expression of Cyp1a1 and Pdk4 in mice kidney tissue.

CONCLUSION

cyp1a1 and pdk4 were identified to play important roles in renal IRI. This research provides a new perspective and basis for studying the pathogenesis of renal IRI and developing new treatments.

Reducing myocardial infarction by combination of irisin and Dendrobium nobile Lindl through inhibiting nod-like receptor protein-3-related pyroptosis and activating PINK1/Parkin-mitophagy during aging

Aging, a crucial risk factor for ischemic heart disease, has negative impacts on cardioprotective mechanisms. As such, there is still an unmet requirement to explore potential therapies for improving the outcomes of myocardial ischemia/reperfusion (IR) injury in elderly subjects. Here, we aimed to confirm the cardioprotective function of irisin/Dendrobium nobile Lindl (DNL) combination therapy against myocardial IR injury in aged rats, with a focus on the involvement of pyroptosis and mitophagy. Male aged Wistar rats (22-24 months old, 400-450 g; n = 54) underwent myocardial IR or sham surgery. Before IR operation, rats were pretreated with irisin (0.5 mg/kg, intraperitoneally) and/or DNL (80 mg/kg, orally) for 1 or 4 weeks, respectively, at corresponding groups. Cardiac function, lactate dehydrogenase (LDH) and cardiac-specific isoform of troponin-I (cTn-I) levels, the expression of proteins involved in pyroptosis (nod-like receptor protein-3 (NLRP3), apoptosis-associated speck-like protein, c-caspase-1, and GSDMD-N) and mitophagy (PINK1 and Parkin), and pro-inflammatory cytokines levels were evaluated after 24 h of reperfusion. Irisin/DNL combined therapy significantly restored cardiac function and decreased LDH and cTn-I levels. It also downregulated pyroptosis-related proteins, upregulated PINK1 and Parkin, and decreased pro-inflammatory cytokines secretion. Pretreatment with Mdivi-1, as mitophagy inhibitor, abolished the cardioprotective action of dual therapy. This study revealed the cardioprotective effects of irisin/DNL combination therapy against IR-induced myocardial injury in aged rats, and also showed that the mechanism might be associated with suppression of NLRP3-related pyroptosis through enhancing the activity of the PINK1/Parkin mitophagy. This combination therapy is worthy of further detailed studies due to its potential to alleviate myocardial IR injury upon aging.

Tumor Necrosis Factor Family Members and Myocardial Ischemia-Reperfusion Injury: State of the Art and Therapeutic Implications

Ischemic heart disease is the principal cause of death worldwide and clinically manifests as myocardial infarction (MI), stable angina, and ischemic cardiomyopathy. Myocardial infarction is defined as an irreversible injury due to severe and prolonged myocardial ischemia inducing myocardial cell death. Revascularization is helpful in reducing loss of contractile myocardium and improving clinical outcome. Reperfusion rescues myocardium from cell death but also induces an additional injury called ischemia-reperfusion injury. Multiple mechanisms are involved in ischemia-reperfusion injury, such as oxidative stress, intracellular calcium overload, apoptosis, necroptosis, pyroptosis, and inflammation. Various members of the tumor necrosis factor family play a key role in myocardial ischemia-reperfusion injury. In this article, the role of TNFα, CD95L/CD95, TRAIL, and the RANK/RANKL/OPG axis in the regulation of myocardial tissue damage is reviewed together with their potential use as a therapeutic target.

Don't go breaking my heart: Peli1 and myocardial ischemia reperfusion injury

Peli1 plays a key role in macrophage M1 polarization, via IRF5 activation, and thereby contributes to myocardial ischemia/reperfusion injury.