Looking for Pyroptosis-Modulating miRNAs as a Therapeutic Target for Improving Myocardium Survival

Exosomes as cutting-edge therapeutics in various biomedical applications: An update on engineering, delivery, and preclinical studies

Exosomes are cell-derived nanovesicles, circulating in different body fluids, and acting as an intercellular mechanism. They can be purified from culture media of different cell types and carry an enriched content of various protein and nucleic acid molecules originating from their parental cells. It was indicated that the exosomal cargo can mediate immune responses via many signaling pathways. Over recent years, the therapeutic effects of various exosome types were broadly investigated in many preclinical studies. Herein, we present an update on recent preclinical studies on exosomes as therapeutic and/or delivery agents for various applications. The exosome origin, structural modifications, natural or loaded active ingredients, size, and research outcomes were summarized for various diseases. Overall, the present article provides an overview of the latest exosome research interests and developments to clear the way for the clinical study design and application.

Dexmedetomidine abates myocardial ischemia reperfusion injury through inhibition of pyroptosis via regulation of miR-665/MEF2D/Nrf2 axis

The current study intended to delve into the mechanisms of dexmedetomidine (Dex) in regulating myocardial pyroptosis against myocardial ischemia/reperfusion injury (MIRI). The rat MIRI models were induced by ligation/release of the coronary artery in vivo and Langendorff perfusion ex vivo. Hemodynamic parameters, infarction sizes, and histopathological changes were assessed to understand the effects of Dex on MIRI. We explored the mechanisms through functional experiments on an H9c2 cell hypoxia/reoxygenation (H/R) model. Cell viability and apoptosis were evaluated using cell counting kit 8 (CCK-8) and AV/PI dual staining respectively. The expressions of miR-665 and MEF2D mRNA were detected by qRT-PCR. Western blot was employed to determine the expression levels of pyroptosis- and signaling pathway- related proteins. The interplays between miR-665 and MEF2D were validated by Dual-luciferase reporter assays. Our findings indicated that Dex preconditioning dramatically attenuated hemodynamic derangements, infarct size, and histopathological damage in rats undergoing MIRI. Dex markedly augmented cell viability, while suppressing cell apoptosis and expressions of NLRP3, cleaved-caspase-1, ASC, GSDMD, IL-1β, and IL-18 in H9c2 cells subjected to H/R injury. MiR-665 was significantly upregulated, MEF2D and Nrf2 downregulated following H/R, whereas Dex preconditioning reversed these changes. MEF2D was validated to be a target gene of miR-665. Overexpression of miR-665 decreased the expression of MEF2D and blunted the protective effects of Dex in H9c2 cells. Moreover, the functional rescue experiment further verified that Dex regulated MEF2D/Nrf2 pathway via miR-665. In conclusion, Dex mitigates MIRI through inhibiting pyroptosis via regulating miR-665/MEF2D/Nrf2 axis.

The role of lncRNA-mediated pyroptosis in cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of death worldwide. Pyroptosis is a unique kind of programmed cell death that varies from apoptosis and necrosis morphologically, mechanistically, and pathophysiologically. Long non-coding RNAs (LncRNAs) are thought to be promising biomarkers and therapeutic targets for the diagnosis and treatment of a variety of diseases, including cardiovascular disease. Recent research has demonstrated that lncRNA-mediated pyroptosis has significance in CVD and that pyroptosis-related lncRNAs may be potential targets for the prevention and treatment of specific CVDs such as diabetic cardiomyopathy (DCM), atherosclerosis (AS), and myocardial infarction (MI). In this paper, we collected previous research on lncRNA-mediated pyroptosis and investigated its pathophysiological significance in several cardiovascular illnesses. Interestingly, certain cardiovascular disease models and therapeutic medications are also under the control of lncRNa-mediated pyroptosis regulation, which may aid in the identification of new diagnostic and therapy targets. The discovery of pyroptosis-related lncRNAs is critical for understanding the etiology of CVD and may lead to novel targets and strategies for prevention and therapy.

miRNA155-5P participated in DDX3X targeted regulation of pyroptosis to attenuate renal ischemia/reperfusion injury

BACKGROUND

Renal ischemia/reperfusion injury (IRI) induced pathological damage to renal microvessels and tubular epithelial cells through multiple factors. However, studies investigated whether miRNA155-5P targeted DDX3X to attenuate pyroptosis were scarce.

RESULTS

The expression of pyroptosis-related proteins (caspase-1, interleukin-1β (IL-1β), NOD-like receptor family pyrin domain containing 3 (NLRP3), and IL-18) were up-regulated in the IRI group. Additionally, miR-155-5p was higher in the IRI group comparing with the sham group. The DDX3X was inhibited by the miR-155-5p mimic more than in the other groups. DEAD-box Helicase 3 X-Linked (DDX3X), NLRP3, caspase-1, IL-1β, IL-18, LDH, and pyroptosis rates were higher in all H/R groups than in the control group. These indicators were higher in the miR-155-5p mimic group than in the H/R and the miR-155-5p mimic negative control (NC) group.

CONCLUSIONS

Current findings suggested that miR-155-5p decreased the inflammation involved in pyroptosis by downregulating the DDX3X/NLRP3/caspase-1 pathway.

METHODS

Using the models of IRI in mouse and the hypoxia-reoxygenation (H/R)-induced injury in human renal proximal tubular epithelial cells (HK-2 cells), we analyzed the changes in renal pathology and the expression of factors correlated with pyroptosis and DDX3X. Real-time reverse transcription polymerase chain reaction (RT-PCR) detected miRNAs and enzyme-linked immunosorbent assay (ELISA) was used to detect lactic dehydrogenase activity. The StarBase and luciferase assays examined the specific interplay of DDX3X and miRNA155-5P. In the IRI group, severe renal tissue damage, swelling, and inflammation were examined.

Therapeutic Implications of Targeting Pyroptosis in Cardiac-related Etiology of Heart Failure

Heart failure remains a considerable clinical and public health problem, it is the dominant cause of death from cardiovascular diseases, besides, cardiovascular diseases are one of the leading causes of death worldwide. The survival of patients with heart failure continues to be low with 45-60% reported deaths within five years. Apoptosis, necrosis, autophagy, and pyroptosis mediate cardiac cell death. Acute cell death is the hallmark pathogenesis of heart failure and other cardiac pathologies. Inhibition of pyroptosis, autophagy, apoptosis, or necrosis reduces cardiac damage and improves cardiac function in cardiovascular diseases. Pyroptosis is a form of inflammatory deliberate cell death that is characterized by the activation of inflammasomes such as NOD-like receptors (NLR), absent in melanoma 2 (AIM2), interferon-inducible protein 16 (IFI-16), and their downstream effector cytokines: Interleukin IL-1β and IL-18 leading to cell death. Recent studies have shown that pyroptosis is also the dominant cell death process in cardiomyocytes, cardiac fibroblasts, endothelial cells, and immune cells. It plays a crucial role in the pathogenesis of cardiac diseases that contribute to heart failure. This review intends to summarize the therapeutic implications targeting pyroptosis in the main cardiac pathologies preceding heart failure.

Chronic intermittent hypoxia induces the pyroptosis of renal tubular epithelial cells by activating the NLRP3 inflammasome

Obstructive sleep apnea syndrome (OSAS) is a respiratory disorder and chronic intermittent hypoxia (CIH) is an important pathological characteristic of OSAS. Injuries on renal tubular epithelial cells were observed under the condition of CIH. Pyroptosis is a programmed mode of cell death following cell apoptosis and cell necrosis, which is mediated by NLRP3 signaling. The present study aims to investigate the effects of CIH on the pyroptosis of renal tubular epithelial cells and the underlying mechanism. Firstly, CIH was induced in two renal tubular epithelial cell lines, HK-2 cells and TCMK-1 cells. As the aggravation of hypoxia, an increasing trend of elevated apoptotic rate was observed in HK-2 cells and TCMK-1 cells, accompanied by the excessive release of ROS and LDH, and upregulation of NLRP3. Subsequently, the CIH model was established on rats. The pathological analysis results indicated that in CIH rats, the glomerular bottom membrane and mesangium were slightly thickened and edema was observed in the renal tubule epithelium. More serious injury was observed in the moderate intermittent hypoxia group. The expression level of IL-1β and IL-18 was promoted as the aggravation of hypoxia, accompanied by the elevated production of LDH and ROS. The expression level of cleaved Caspase-1, Caspase-1, GSDMD, TLR4, MyD88, NF-κB, p-NF-κB, and NLRP3 was found significantly upregulated as the aggravation of hypoxia. Lastly, the pathological changes in rats induced by CIH were dramatically abolished by MCC950, a specific inhibitor of NLRP3. Collectively, CIH triggered the pyroptosis of renal tubular epithelial cells by activating the NLRP3 inflammasome.

MicroRNA-136-5p protects cardiomyocytes from coronary microembolization through the inhibition of pyroptosis

This study investigated how miR-136-5p partially affected cardiomyocyte pyroptosis in rats with coronary microembolization (CME). The cardiac function and structure of rats with CME were evaluated using echocardiography, hematoxylin and eosin staining, Masson staining, and troponin I level. Pyroptosis was induced by lipopolysaccharide (LPS) in isolated rat cardiomyocytes and evaluated by the expression of caspase-1, NOD-like receptor family pyrin domain-containing 3, interleukin-1β, and gasdermin D-N. After cell transfection, the expression of Ataxin-1 like (ATXN1L), pyrin domain-containing 1 (PYDC1), and pyroptosis-related proteins was assessed. Dual-luciferase reporter and immunoprecipitation assays were used to verify the relationships among miR-136-5p, ATXN1L, and capicua (CIC). MiR-136-5p was under-expressed, whereas ATXN1L was overexpressed in rats with CME and in LPS-treated primary cardiomyocytes. MiR-136-5p targeted ATXN1L, and ATXN1L bound to CIC to suppress PYDC1 expression. MiR-136-5p overexpression suppressed pyroptosis by inhibiting the binding of ATXN1L with CIC and promoting PYDC1 expression, which was reversed by simultaneous elevation of ATXN1L. In conclusion, miR-136-5p suppressed pyroptosis by upregulating PYDC1 via ATXN1L/CIC axis, thereby attenuating cardiac damage caused by CME.

miR-302a-3p targets FMR1 to regulate pyroptosis of renal tubular epithelial cells induced by hypoxia-reoxygenation injury

NEW FINDINGS

What is the central question of this study? How does miR-302a-3p play a role in hypoxia-reoxygenation-induced pyroptosis of renal tubular epithelial cells? What is the main finding and its importance? Hypoxia-reoxygenation treatment upregulated the expression of miR-302a-3p in HK-2 cells, and then inhibited the transcription of FMRP translational regulator 1 (FMR1), so as to promote the activation of the NLRP3 inflammasome and aggravate the pyroptosis of HK-2 cells. miR-302a-3p was used as a molecular target in this study, which provides a new theoretical basis for the treatment of renal failure.

ABSTRACT

Hypoxia-reoxygenation (H/R) induction can affect miRNA expression and then control NLR family pyrin domain containing 3 (NLRP3) inflammasome-mediated pyroptosis. This study investigated the mechanism of miR-302a-3p in H/R-induced renal tubular epithelial cell (RTEC) pyroptosis. Human HK-2 RTECs were induced by H/R. Lactate dehydrogenase content, cell activity and pyroptosis, and levels of NLRP3, GSDMD-N, caspase-1, interleukin (IL)-1β, IL-18, superoxide dismutase, and malondialdehyde were detected to verify the effect of H/R on HK-2 cells. The NLRP3 inflammasome action was evaluated after H/R-induced HK-2 cells were treated with BAY11-7082, an inflammasome inhibitor. After inhibiting miR-302a-3p expression, the changes of pyroptosis were observed. The binding relation between miR-302a-3p and FMRP translational regulator 1 (FMR1) was verified. A function-rescue experiment verified the role of FMR1 in the regulation of pyroptosis. H/R-induced HK-2 cells showed significant pyroptosis injury, and the NLRP3 inflammasome was activated. After inhibiting the NLRP3 inflammasome, H/R-induced apoptosis was inhibited. After H/R treatment, miR-302a-3p in HK-2 cells was increased, and miR-302a-3p downregulation limited H/R-induced NLRP3 inflammasome-mediated pyroptosis. FMR1 is the target of miR-302a-3p. Inhibition of FMR1 alleviated the inhibition of H/R-induced HK-2 cell pyroptosis by miR-302a-3p inhibitor. Collectively, inhibiting miR-302a-3p can weaken its targeted inhibition on FMR1, thereby inhibiting the activation of NLRP3 inflammasomes and reducing caspase-1-dependent pyroptosis in HK-2 cells.

Mechanism of total glucosides of paeony in hypoxia/reoxygenation-induced cardiomyocyte pyroptosis

Inflammasome-mediated pyroptosis can aggravate myocardial ischemia/reperfusion injury. Total glucosides of paeony (TGP) is widely used in anti-inflammation. This study investigated the effect of TGP on pyroptosis of hypoxia/reoxygenation (H/R)-induced cardiomyocytes. HL-1 cells were subjected to H/R treatment. H/R-induced cardiomyocytes were treated with TGP at different concentrations (50, 100, and 200 mg/kg). The viability of H/R-induced cardiomyocytes was measured. The levels of lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), and reactive oxygen species (ROS) were determined. The activity of caspase-1, the expressions of NLRP3 and GSDMD-N, and the concentrations of IL-1β and IL-18 were examined. miR-181a-5p expression in H/R cardiomyocytes was determined. The targeting relationship between miR-181a-5p and adenylate cyclase 1 (ADCY1) was verified. Functional rescue experiments were performed to verify the effect of miR-181a-5p or ADCY1 on the pyroptosis of H/R cardiomyocytes. TGP enhanced H/R-induced cardiomyocyte viability in a dose-dependent manner, reduced LDH, MDA, and ROS levels, increased SOD level, decreased caspase-1 activity, reduced NLRP3 and GSDMD-N expressions, and inhibited IL-1β and IL-18 concentrations. TGP suppressed miR-181a-5p expression in H/R cardiomyocytes. miR-181a-5p targeted ADCY1. miR-181a-5p overexpression or ADCY1 inhibition reversed the inhibitory effect of TGP on the pyroptosis of H/R cardiomyocytes. Collectively, TGP alleviated the pyroptosis of H/R cardiomyocytes via the miR-181a-5p/ADCY1 axis.

LncRNA H19 suppresses pyroptosis of cardiomyocytes to attenuate myocardial infarction in a PBX3/CYP1B1-dependent manner

OBJECTIVE

Myocardial infarction (MI) is a major cause of cardiovascular disease which poses great healthy and financial burden for individuals. MI can be mainly induced by hypoxia. Therefore, in this study, we aimed to explore the function and mechanism of lncRNA H19 on hypoxia-induced pyroptosis of cardiomyocytes.

METHOD

Peripheral blood from healthy controls and MI patients was collected for determination of mRNA and protein expression levels of H19 and CYP1B1. The correlation between these two factors was analyzed. Then MI rat model was established and injected with H19 overexpression/CYP1B1 knockdown plasmid, in which the infraction area and pathological morphology were observed. Hypoxic cardiomyocytes were transfected with overexpression or knockdown of H19 and CYP1B1 for determination of NLRP3, ASC, caspase-1, IL-1β, IL-18, CyclinD1, and PCNA. Cell proliferation ability was assessed by CCK8. RIP and dual luciferase gene reporter assay were applied to verify the binding among H19, PBX3 and CYP1B1.

RESULTS

Downregulated H19 and upregulated CYP1B1 were observed in MI patients. A negative correlation was found for H19 and CYP1B1 expressions. Transfection of H19 overexpression or CYP1B1 knockdown could attenuate the MI progression in MI rats. In hypoxic cardiomyocytes, H19 overexpression or CYP1B1 knockdown could also inhibit NLRP3, ASC, caspase-1, IL-1β, and IL-18 in addition to suppressing cell apoptosis rate and promoting cell proliferation rate. Different expression pattern was found in cells transfected with H19 knockdown or CYP1B1 overexpression. Overexpression of CYP1B1 could abrogate the suppressive effect of H19 on pyroptosis of cardiomyocytes. H19 could inhibit activity of CYP1B1 promoters by regulating PBX3.

CONCLUSION

H19 could inhibit CYP1B1 expression in a PBX3-dependent way and thus attenuate cell pyroptosis of cardiomyocytes.

MicroRNA-195 suppresses enterovirus A71-induced pyroptosis in human neuroblastoma cells through targeting NLRX1

Enterovirus A71 (EV-A71) emerged as a leading cause of virus derived infant encephalitis in most Asian countries. Some recent studies point out the critical role of microRNA (miRNA) in the regulation of pyroptosis. However, the role of miRNAs in the regulation of EV-A71 infection-induced pyroptosis was not previously explored. In this study, we utilized microRNA array and real-time PCR to verify that miR-195 significantly down-regulate in EV-A71-infected SH-SY5Y human neuroblastoma cells. An inverse correlation of NLRX1 with miR-195 expression in EV-A71-infected SH-SY5Y cells was found. Target prediction of miR-195 showed that NLRX1 could directly interact with miR-195. Results from luciferase reporter assays, qRT-PCR and western blotting demonstrated the negative regulation between miR-195 and NLRX1. Silencing NLRX1 expression with small interfering RNAs (siRNAs-NLRX1) and over-expression of miR-195 also attenuate the EV-A71 associated pyroptosis. Our findings provided evidence showed that miR-195 can regulate EV-A71 infection-induced pyroptosis, by directly targeting NLRX1.

Long Non-Coding RNA NEAT1 Regulates Pyroptosis in Diabetic Nephropathy via Mediating the miR-34c/NLRP3 Axis

INTRODUCTION

Diabetic nephropathy (DN) is a serious complication of diabetes mellitus and is considered to be a sterile inflammatory disease. Increasing evidence suggest that pyroptosis and subsequent inflammatory response play a key role in the pathogenesis of DN. However, the underlying cellular and molecular mechanisms responsible for pyroptosis in DN are largely unknown.

METHODS

The rat models of DN were successfully established by single 65 mg/kg streptozotocin treatment. Glomerular mesangial cells were exposed to 30 mmol/L high glucose media for 48 h to mimic the DN environment in vitro. Gene and protein expressions were determined by quantitative real-time PCR and Western blot. Cell viability and pyroptosis were measured by MTT assay and flow cytometry analysis, respectively. The relationship between lncRNA NEAT1, miR-34c, and Nod-like receptor protein-3 (NLRP3) was confirmed by luciferase reporter assay.

RESULTS

We found that upregulation of NEAT1 was associated with the increase of pyroptosis in DN models. miR-34c, as a target gene of NEAT1, mediated the effect of NEAT1 on pyroptosis in DN by regulating the expression of NLRP3 as well as the expressions of caspase-1 and interleukin-1β. Either miR-34c inhibition or NLRP3 overexpression could reverse the accentuation of pyroptosis and inflammation by sh-NEAT1 transfection in the in vitro model of DN.

CONCLUSIONS

Our findings suggested NEAT1 and its target gene miR-34c regulated cell pyroptosis via mediating NLRP3 in DN, providing new insights into understanding the molecular mechanisms of pyroptosis in the pathogenesis of DN.

Roseburia intestinalis‑derived flagellin ameliorates colitis by targeting miR‑223‑3p‑mediated activation of NLRP3 inflammasome and pyroptosis

Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD), which is a chronic, relapsing condition associated with the disorder of gut microbial communities. A previous study reported that levels of Roseburia intestinalis (R.I), a butyrate‑producing bacterium, are significantly decreased in patients with IBD and exert an anti‑inflammatory function in dextran sulfate sodium (DSS)‑induced colitis. However, the role of R.I flagellin in UC and its underlying molecular mechanism are not yet fully understood. Therefore, a DSS‑induced colitis model in C57Bl/6 mice and the LPS/ATP‑induced THP‑1 macrophages were treated with R.I flagellin, which were used to investigate the anti‑inflammatory effects of R.I flagellin. The results demonstrated that R.I flagellin decreased colitis‑associated disease activity index, colonic shortening and the pathological damage of the colon tissues in murine colitis models. Furthermore, R.I flagellin decreased the serum levels of proinflammatory cytokines and inhibited activation of the nucleotide‑binding oligomerization segment‑like receptor family 3 (NLRP3) inflammasome in murine colitis. R.I flagellin was also demonstrated to decrease the Gasdermin D to yield the N‑terminal fragment membrane pore and inhibit inflammasome‑triggered pyroptosis. In vitro analysis indicated that microRNA (miR)‑223‑3p was involved in the regulation of R.I flagellin on NLRP3 inflammasome activation. Taken together, the results of the present study demonstrated that R.I flagellin inhibited activation of the NLRP3 inflammasome and pyroptosis via miR‑223‑3p/NLRP3 signaling in macrophages, suggesting that R.I flagellin may be used as a novel probiotic product for the treatment of UC.

Dexmedetomidine inhibits pyroptosis by down-regulating miR-29b in myocardial ischemia reperfusion injury in rats

OBJECTIVE

Dexmedetomidine (DEX) was reported to protect heart against ischemic-reperfusion (IR) but the mechanism herein remains elusive. This study aims to explore the mechanism of DEX on pyroptosis induced by myocardial ischemic reperfusion (MIR).

METHODS

MIR rat models were established and injected DEX or miR-29b agomir/antagomir separately. The possible effect of DEX or miR-29b on myocardial cells was assessed according to measurement on creatine kinase-MB (CK-MB), cardiac troponin I (cTnI), interleukin-1β (IL-1β) and interleukin-18 (IL-18), myocardial infarction size, myocardial injury and apoptosis. Western blot determined the expression levels of nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing CARD (ASC) and cleaved-caspase-1. Hypoxia/reoxygenation (H/R) cell model was established. The lactate dehydrogenase (LDH) content released by myocardial cells was examined. The relation between miR-29b and FoxO3a was confirmed by dual luciferase reporter gene assay. FoxO3a or ARC level was elevated in H/R myocardial cells to detect its effect on pyroptosis.

RESULTS

MIR rat models were successfully established, in which cell pyroptosis was triggered as evidenced by increased expression levels of NLRP3, ASC and cleaved-caspase-1. Rats with DEX precondition had attenuated cell pyroptosis and ameliorated inflammatory response. FoxO3a was a target of miR-29b. MiR-29b agomir or miR-29b antagomir could inhibit or promote the protective effect of DEX on MIR. Overexpression of FoxO3a/ARC axis could suppress myocardial pyroptosis induced by H/R.

CONCLUSION

DEX could ameliorate MIR injury (MIRI) and H/R injury in rats and inhibit H/R induced pyroptosis in myocardial cells via down-regulating miR-29b to activate FoxO3a/ARC axis.

Low shear stress regulates vascular endothelial cell pyroptosis through miR-181b-5p/STAT-3 axis

Low shear stress and pyroptosis both play an important role in the onset and development of atherosclerosis (AS). MicroRNAs (miRNAs) are a kind of short (18-22) nucleotide sequences that can bind to the 3'-untranslated region (3'-UTR) of messenger RNA, thereby regulating programmed cell death including pyroptosis. However, the function of miRNAs in cells subjected to shear stress conditions is unknown. Therefore, we conducted the current study to demonstrate the effect of low shear stress on pyroptosis and the underlying mechanism. Human umbilical vein endothelial cells (HUVECs) stimulated by undisturbed shear stress (5 dynes/cm² ) were the experimental group while HUVECs without shear stress treatment were the control group in our experiments. We observed that shear stress can suppress mechanosensitive miR-181b-5p expression, accompanying the elevated expression of NLRP3 inflammasome-dependent pyroptosis. Introduction of miR-181b-5p could alleviate NLRP3 inflammasome-dependent pyroptosis. Luciferase assay showed specific binding of miR-181b-5p to the 3'-UTR of signal transduction and transcriptional activation factor 3 (STAT-3) gene. Inhibition of STAT-3 gene expression at the posttranscriptional level results in the alleviation of NLRP3 inflammasome-dependent pyroptosis. Besides, the silencing of STAT-3 reduced anti-miR-181b-5p-mediated HUVEC pyroptosis via regulating NLRP3 inflammasome activation. Given the role of mechanosensitive miR-181b-5p and STAT-3 in the shear stress-induced pyroptosis, regulation of their expression levels may be a promising strategy to control AS.

LncRNA KLF3-AS1 in human mesenchymal stem cell-derived exosomes ameliorates pyroptosis of cardiomyocytes and myocardial infarction through miR-138-5p/Sirt1 axis

AIM

Myocardial infarction (MI) is a severe disease with increased mortality and disability rates, posing heavy economic burden for society. Exosomes were uncovered to mediate intercellular communication after MI. This study aims to explore the effect and mechanism of lncRNA KLF3-AS1 in exosomes secreted by human mesenchymal stem cells (hMSCs) on pyroptosis of cardiomyocytes and MI.

METHODS

Exosomes from hMSCs were isolated and identified. Exosomes from hMSCs with transfection of KLF3-AS1 for overexpression were injected into MI rat model or incubated with hypoxia cardiomyocytes. Effect of KLF3-AS1 on MI area, cell viability, apoptosis, and pyroptosis was determined. The relationship among miR-138-5p, KLF3-AS1, and Sirt1 was verified by dual-luciferase reporter assay. Normal cardiomyocytes were transfected with miR-138-5p inhibitor or sh-Sirt1 to clarify whether alteration of miR-138-5p or sh-Sirt1 can regulate the effect of KLF3-AS1 on cardiomyocytes.

RESULTS

Exosomes from hMSCs were successfully extracted. Transfection of KLF3-AS1 exosome in rats and incubation with KLF3-AS1 exosome in hypoxia cardiomyocytes both verified that overexpression of KLF3-AS1 in exosomes leads to reduced MI area, decreased cell apoptosis and pyroptosis, and attenuated MI progression. KLF3-AS1 can sponge miR-138-5p to regulate Sirt1 expression. miR-138-5p inhibitor transfection and KLF3-AS1 exosome incubation contribute to attenuated pyroptosis and MI both in vivo and in vitro, while transfection of sh-Sirt1 could reverse the protective effect of exosomal KLF3-AS1 on hypoxia cardiomyocytes.

CONCLUSION

LncRNA KLF3-AS1 in exosomes secreted from hMSCs by acting as a ceRNA to sponge miR-138-5p can regulate Sirt1 so as to inhibit cell pyroptosis and attenuate MI progression.

β-hydroxybutyrate attenuates renal ischemia-reperfusion injury through its anti-pyroptotic effects

Ketone bodies including β-hydroxybutyrate (β-OHB) have been shown to protect against ischemic tissue injury when present at low concentrations. We evaluated the impact of β-OHB on renal ischemia/reperfusion injury (IRI). Mice were treated with a continuous infusion of β-OHB using an osmotic mini-pump before and after IRI. We also tested the effects of increasing endogenous serum β-OHB levels by fasting. Renal IRI was attenuated by β-OHB treatment compared to saline control, with similar results in the fasting condition. β-OHB treatment reduced the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive cells and increased expression of forkhead transcription factor O3 (FOXO3), an upstream regulator of pyroptosis. Although β-OHB treatment did not impact markers of apoptosis, it decreased the expression of caspase-1 and proinflammatory cytokines, indicating that β-OHB blocked pyroptosis. In a human proximal tubular cell line exposed to hypoxia and reoxygenation, β-OHB reduced cell death in a FOXO3-dependent fashion. Histone acetylation was decreased in kidneys exposed to IRI and in proximal tubular cells exposed to hypoxia and reoxygenation, and this effect was ameliorated by β-OHB through the inactivation of histone deacetylases. In vitro, β-OHB treatment restored histone acetylation at the FOXO3 promoter. Consistent with epigenetic molecular effects, the renoprotective effects of β-OHB were still observed when the continuous infusion was stopped at the time of IRI. Thus, β-OHB attenuates renal IRI through anti-pyroptotic effects, likely mediated by an epigenetic effect on FOXO3 expression.

miR-16 inhibits NLRP3 inflammasome activation by directly targeting TLR4 in acute lung injury

Acute lung injury (ALI) is the leading cause of human death, and it is widely accepted that the runaway inflammation is an important risk for the development of ALI. In the present study, we aimed to investigate the effect of miR-16 on lipopolysaccharide-induced acute lung injury in mice, especially focusing on Toll-like receptor 4 (TLR4) and NF-kB signaling pathway as well as NOD-like receptor protein 3 (NLRP3) inflammasome activation. We established in vivo and in vitro model of ALI using LPS and demonstrated that miR-16 expression was down-regulated in lung tissue as well as A549 cells after 8 h of LPS treatment. Furthermore, when miR-16 levels in lung tissues were up-regulated by miR-16 agomir, it was confirmed that the mRNA and protein levels of NF-κB, NLRP3 inflammasome, and inflammatory factors were decreased by the miR-16 by directly targeting TLR4. We also treated A549 cells with miR-16 mimics and anti-miR-16 to confirm the results. Overall, our experiments showed that miR-16 protects against acute lung injury in mice by regulating the TLR4/ NF-κB pathway and attenuating inflammatory response. This work suggests a potential novel therapeutic approach to combat ALI.

Long noncoding RNA MALAT1 promotes high glucose-induced human endothelial cells pyroptosis by affecting NLRP3 expression through competitively binding miR-22

Cell death and inflammation play critical roles in atherosclerosis. Pyroptosis, a novel proinflammatory programmed cell death process, participates in atherosclerosis pathogenesis. Recently, MALAT1 was identified as a pyroptosis-related long noncoding RNA (lncRNA). Here, we investigated the potential role and underlying mechanism of lncRNA MALAT1 in endothelial cells pyroptosis. We first established an endothelial cell pyroptosis model by stimulating EA.hy926 human endothelial cells (EA.hy926 cells) with high glucose. Then, we investigated lncRNA MALAT1 expression and found that it was upregulated in high glucose-treated EA.hy926 cells. Furthermore, lncRNA MALAT1 knockdown significantly inhibited high glucose-induced pyroptosis in EA.hy926 cells, which may critically influence atherosclerosis. Moreover, miR-22 was a target of lncRNA MALAT1 and was negatively correlated with lncRNA MALAT1. NLRP3 expression was significantly suppressed by transfection with a MALAT1-targeting antisense oligonucleotide (ASO). Ultimately, miR-22 overexpression abrogated the effect of MALAT1 on high glucose-induced EA.hy926 cells pyroptosis. Together, our results suggest that lncRNA MALAT1 promotes high glucose-induced pyroptosis of endothelial cells partly by affecting NLRP3 expression through competitively binding miR-22. Our findings indicate a new regulatory mechanism for endothelial cells pyroptosis under high-glucose stress, providing a novel therapeutic target for atherosclerosis.

Combined Ischemic Postconditioning and Ozone Postconditioning Provides Synergistic Protection Against Renal Ischemia and Reperfusion Injury Through Inhibiting Pyroptosis

OBJECTIVE

To investigate whether ischemic postconditioning (IPO) and ozone postconditioning (OP) could synergistically attenuate renal ischemia-reperfusion (I/R) injury and its possible mechanism.

MATERIALS AND METHODS

An in vivo rat model of renal I/R injury was established, and the serum and kidneys were harvested after reperfusion to assess renal function and histologic changes. For the in vitro study, the cultured NRK-52E cells were subjected to 3 hours of hypoxia (5% CO₂, 1% O₂, and 94% N₂) followed by 24 hours of reoxygenation (5% CO₂, 21% O₂, and 74% N₂). The mRNA expression levels were analyzed by real-time polymerase chain reaction, and the protein expression levels were analyzed by using Western blot, immunofluorescence staining and enzyme-linked immunosorbent assay.

RESULTS

Kidneys undergone I/R showed characteristic renal dysfunction and pyroptosis. IPO or OP could prevent the elevated blood urea nitrogen and creatinine, renal damage, as well as pyroptosis, however, the combined application of them had more obvious protection. Oxidative stress and pyroptosis were increased in hypoxia and reoxygenation (H/R) model using NRK-52E cells. The combination of hypoxic postconditioning and OP had more protective effects on oxidative abnormalities and pyroptosis compared with the single application of hypoxic postconditioning or OP.

CONCLUSION

Our in vivo and in vitro studies show the combination of IPO and OP synergistically prote-cted the kidney from I/R by attenuating pyroptosis in kidney cells.

miR-424 promotes cardiac ischemia/reperfusion injury by direct targeting of CRISPLD2 and regulating cardiomyocyte pyroptosis

As a complex pathophysiological event, myocardial ischemia/reperfusion injury (IRI) can cause heart failure, which has been associated with pyroptosis, a pro-inflammatory programmed cell death. Small endogenous non-coding RNAs have been shown to be involved in myocardial IRI. In the present study, we aimed to investigate whether miR-424 modulated pyroptosis in response to myocardial IRI and determine its underlying regulatory mechanism. An in vivo mouse model of cardiac IRI was established, and contractile function was evaluated by echography. The serum and heart tissue were harvested 24 h after reperfusion to assess the status of pyroptosis. For the in vitro study, H9C2 cells (a rat heart cell line) were subjected to 6 h of hypoxia, followed by 18 h of reoxygenation. The gene expressions at the mRNA level were assessed by real-time PCR, and the expressions at the protein level were examined by western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assay (ELISA). Bioinformatic analysis was applied to predict miR-424 targets, which were then confirmed by a luciferase reporter assay. We found that the expressions of pyroptosis-related proteins, including caspase-1, caspase-11, IL-1β, and IL-18, were significantly increased upon myocardial IRI. Similarly, hypoxia/reoxygenation injury (HRI) also induced pyroptosis in H9C2 cells. Furthermore, our study revealed that the miR-424 expression was substantially increased in I/R heart tissue and H/R-challenged H9C2 cells. In addition, we found that exogenous expression of miR-424 directly targeted cysteine-rich secretory protein LCCL domain-containing 2 (CRISPLD2) and up-regulated the expressions of caspase-1 and the pro-inflammatory cytokines IL-1β and IL-18. Taken together, our findings provided a new signaling pathway of miR-424/CRISPLD2 in cardiac pyroptosis under IRI conditions.

Double-Face of Vasohibin-1 for the Maintenance of Vascular Homeostasis and Healthy Longevity

The structural and functional integrity of endothelium is essential for the maintenance of vascular health. Vasohibin-1 (VASH1), originally isolated as an endothelium-derived angiogenesis inhibitor, has another function to promote stress tolerance of endothelial cells (ECs), and these functions are critical for the maintenance of vascular homeostasis preventing both pathological angiogenesis and stress-induced vascular diseases. The expression of VASH1 is downregulated during replicative senescence of ECs by the alteration of microRNA expression, and this age-associated downregulation of VASH1 might be a risk of deterioration of vascular homeostasis and age-related vascular diseases. Contrary to this expectation, the lack of Vash1 gene in mice exhibited healthy longevity. Thus, VASH1 has double-face for the maintenance of vascular homeostasis and healthy longevity. This feature of VASH1 and its mechanism will be described in this mini review.

Melatonin prevents endothelial cell pyroptosis via regulation of long noncoding RNA MEG3/miR-223/NLRP3 axis

Atherosclerosis (AS) is an inflammatory disease linked to endothelial dysfunction. Melatonin is reported to possess substantial anti-inflammatory properties, which has proven to be effective in AS. Emerging literature suggests that pyroptosis plays a critical role during AS progression. However, whether pyroptosis contributes to endothelial dysfunction and the underlying molecular mechanisms remained unexploited. This study was designed to investigate the antipyroptotic effects of melatonin in atherosclerotic endothelium and to elucidate the potential mechanisms. In this study, high-fat diet (HFD)-treated ApoE^-/- mice were used as an atherosclerotic animal model. We found intragastric administration of melatonin for 12 weeks markedly reduced the atherosclerotic plaque in aorta. Meanwhile, melatonin also attenuated the expression of pyroptosis-related genes, including NLRP3, ASC, cleaved caspase1, NF-κB/GSDMD, GSDMD N-termini, IL-1β, and IL-18 in aortic endothelium of melatonin-treated animals. Consistent antipyroptotic effects were also observed in ox-LDL-treated human aortic endothelial cells (HAECs). We found that lncRNA MEG3 enhanced pyroptosis in HAECs. Moreover, MEG3 acted as an endogenous sponge by sequence complementarity to suppress the function of miR-223 and to increase NLRP3 expression and enhance endothelial cell pyroptosis. Furthermore, knockdown of miR-223 blocked the antipyroptotic actions of melatonin in ox-LDL-treated HAECs. Together, our results suggest that melatonin prevents endothelial cell pyroptosis via MEG3/miR-223/NLRP3 axis in atherosclerosis, and therefore, melatonin replacement might be considered a new strategy for protecting endothelium against pyroptosis, thereby for the treatment of atherosclerosis associated with pyroptosis.

Pancreatic Beta Cell Death: Novel Potential Mechanisms in Diabetes Therapy

PURPOSE OF REVIEW

Describing the diverse molecular mechanisms (particularly immunological) involved in the death of the pancreatic beta cell in type 1 and type 2 diabetes mellitus.

RECENT FINDINGS

Beta cell death is the final event in a series of mechanisms that, up to date, have not been entirely clarified; it represents the pathophysiological mechanism in the natural history of diabetes mellitus. These mechanisms are not limited to an apoptotic process only, which is characteristic of the immune-mediated insulitis in type 1 diabetes mellitus. They also include the action of proinflammatory cytokines, the production of reactive oxygen species, DNA fragmentation (typical of necroptosis in type 1 diabetic patients), excessive production of islet amyloid polypeptide with the consequent endoplasmic reticulum stress, disruption in autophagy mechanisms, and protein complex formation, such as the inflammasome, capable of increasing oxidative stress produced by mitochondrial damage.

SUMMARY

Necroptosis, autophagy, and pyroptosis are molecular mechanisms that modulate the survival of the pancreatic beta cell, demonstrating the importance of the immune system in glucolipotoxicity processes and the potential role for immunometabolism as another component of what once known as the "ominous octet."