The NLRP3 inflammasome is up-regulated in cardiac fibroblasts and mediates myocardial ischaemia-reperfusion injury

NLRP3 inflammasome activation contributes to the development of the pro-fibrotic phenotype of lung fibroblasts

Idiopathic pulmonary fibrosis (IPF) is an irreversible progressive interstitial lung disease of unknown cause. The poorly understood pathophysiology of IPF poses substantial challenges to the development of effective anti-lung fibrotic drugs. The NLRP3 inflammasome, a key component of the innate immune system, has recently been linked to the pathogenesis of lung fibrosis. However, the specific contributions of NLRP3 inflammasomes to determination of the pro-fibrotic phenotype of lung fibroblasts, which play a central role in the production of extracellular matrix protein, remain to be investigated. Therefore, the present study was performed to elucidate the involvement of NLRP3 inflammasome signalling pathways in modulation of lung fibroblast proliferation and differentiation. We found that activation of NLRP3 inflammasomes increased in lung fibroblasts derived from individuals with pulmonary fibrosis and in normal lung fibroblasts stimulated with transforming growth factor β and platelet-derived growth factor. Importantly, blockage of NLRP3 inflammasome signalling, either by gene silencing of NLRP3 or using pharmacological inhibitors of NLRP3, caspase-1, or IL-1 receptor, inhibited the proliferation, differentiation, and extracellular matrix protein synthesis of activated lung fibroblasts. Moreover, induction of the reactive oxygen species/thioredoxin-interacting protein axis, an upstream signalling pathway of NLRP3 inflammasomes, was essential for maintenance of the pro-fibrotic phenotype of lung fibroblasts. Interestingly, treatments with pharmacological inhibitors of NLRP3 inflammasomes prevented the progression of bleomycin-induced pulmonary fibrosis in mice. Collectively, these findings suggest that aberrant activation of NLRP3 inflammasomes is a critical event in the pathogenesis of IPF and that targeting NLRP3 inflammasomes may serve as a therapeutic strategy for IPF.

The PINK1/Parkin signaling pathway-mediated mitophagy: a forgotten protagonist in myocardial ischemia/reperfusion injury

Myocardial ischemia causes extensive damage, further exacerbated by reperfusion, a phenomenon called myocardial ischemia/reperfusion injury (MIRI). Nowadays, the pathological mechanisms of MIRI have received extensive attention. Oxidative stress, multiple programmed cell deaths, inflammation and others are all essential pathological mechanisms contributing to MIRI. Mitochondria are the energy supply centers of cells. Numerous studies have found that abnormal mitochondrial function is an essential "culprit" of MIRI, and mitophagy mediated by the phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1)/Parkin signaling pathway is an integral part of maintaining mitochondrial function. Therefore, exploring the association between the PINK1/Parkin signaling pathway-mediated mitophagy and MIRI is crucial. This review will mainly summarize the crucial role of the PINK1/Parkin signaling pathway-mediated mitophagy in MIR-induced several pathological mechanisms and various potential interventions that affect the PINK1/Parkin signaling pathway-mediated mitophagy, thus ameliorating MIRI.

Interleukin-38 ameliorates myocardial Ischemia-Reperfusion injury via inhibition of NLRP3 inflammasome activation in fibroblasts through the IL-1R8/SYK axis

OBJECTIVE

Although IL-38 is recognized for its regulatory role in a spectrum of chronic inflammatory diseases, investigations into its cardiac physiological and pathophysiological functions are nascent. Our aim was to delineate the biological impact of IL-38 in the context of myocardial ischemia-reperfusion injury (MIRI) and to uncover the mechanisms through which it exerts its effects.

METHODS AND RESULTS

In this study, we used an MIRI mouse model, LPS/ATP stimulation, and a hypoxia/reoxygenation cell model to determine the regulatory influence of IL-38 on MIRI. We observed that the administration of recombinant IL-38 to mice led to a reduction in infarct size, an enhancement in cardiac function, and a suppression of NLRP3 inflammasome activation. In contrast, genetic deletion of IL-38 was associated with an increase in infarct size, worsening of cardiac function, and upregulation of NLRP3 inflammasome activity. The detrimental effects associated with the absence of IL-38 were mitigated by the administration of a specific NLRP3 inhibitor, suggesting that the inhibition of NLRP3 is a critical component of the protective effect mediated by IL-38 in MIRI. In vitro assays revealed that IL-38 inhibited NLRP3 inflammasome activation in cardiac fibroblasts through the engagement of IL-1R8 and the modulation of SYK phosphorylation. Silencing of IL-1R8 negated the suppressive effect of IL-38 on the NLRP3 inflammasome.

CONCLUSION

IL-38 acts as a potent negative regulator of inflammasome activation after MIRI. It achieves this regulatory effect within cardiac fibroblasts by inhibiting SYK phosphorylation, a process mediated by IL-1R8.

Inhibition of circDGKZ ameliorates myocardial ischemia/reperfusion injury by targeting miR-345-5p/TLR4

AIMS

This study aims to explore the molecular mechanism of circular RNAs' (circRNAs) potential involvement in myocardial ischaemia-reperfusion injury (MIRI).

METHODS AND RESULTS

Differently expressed genes in myocardial infarction (MI) were identified by screening the GEO database. Serum was collected from MI patients and healthy volunteers (n = 5 for each group). AC16 cells were cultured and exposed to hypoxia/reperfusion (H/R) treatment for the cell experiments. Then candidate genes were validated in human serum and the H/R model. Quantitative real-time PCR and western blot were used to detect expression of key molecules such as circDGKZ, miR-345-5p, and Toll-like receptor 4 (TLR4), as well as pyroptosis markers such as NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), ASC, C-caspase1, interleukin (IL)-1β, and IL-18. CircDGKZ was positively correlated in human serum (P < 0.05) and in AC16 cells (P < 0.01). Knockdown of circDGKZ inhibited cardiomyocyte pyroptosis and the TLR4/nuclear factor kappa B (NF-κB) signalling pathway (all P < 0.05). A luciferase assay was used to detect the molecule interaction. MiR-345-5p was regulated by circDGKZ and regulated TLR4 in cardiomyocytes both through direct interaction (P < 0.01). The stability and distribution of circRNA or linear RNA were examined by subcellular localization and RNA decay assays. CircDGKZ was stably expressed in cardiomyocytes and mainly distributed in the cytoplasm (P < 0.01). Knockdown of circDGKZ also promoted the degradation of NLRP3 by inducing autophagy (P < 0.05). MIRI rat models were constructed (n = 5 for each group), and the cellular results were further confirmed in rat models (P < 0.05).

CONCLUSIONS

Knockdown of circDGKZ interrupted pyroptosis and induced autophagy of cardiomyocytes via regulating miR-345-5p/TLR4/NF-κB.

NLRP3-directed antisense oligonucleotides reduce microglial immunoactivities in vitro

Alzheimer's disease (AD) is associated with the cerebral deposition of Amyloid-β (Aβ) peptide, which leads to NLRP3 inflammasome activation and subsequent release of interleukin-1β (IL-1β) and interleukin-18 (IL-18). NLRP3 reduction has been found to increase microglial clearance, protect from synapse loss, and suppress both the changes to synaptic plasticity and spatial memory dysfunction observed in murine AD models. Here, we test whether NLRP3-directed antisense oligonucleotides (ASOs) can be harnessed as immune modulators in primary murine microglia and human THP-1 cells. NLRP3 mRNA degradation was achieved at 72 h of ASO treatment in primary murine microglia. Consequently, NLRP3-directed ASOs significantly reduced the levels of cleaved caspase-1 and mature IL-1β when microglia were either activated by LPS and nigericin or LPS and Aβ. In human THP-1 cells NLRP3-targeted ASOs also significantly reduced the LPS plus nigericin- or LPS plus Aβ-induced release of mature IL-1β. Together, NLRP3-directed ASOs can suppress NLRP3 inflammasome activity and subsequent release of IL-1β in primary murine microglia and THP-1 cells. ASOs may represent a new and alternative approach to modulate NLRP3 inflammasome activation in neurodegenerative diseases, in addition to attempts to inhibit the complex pharmacologically.

IL-1 blockade in cardiovascular disease: an appraisal of the evidence across different inflammatory paradigms

Pre-clinical and clinical studies suggest a role for inflammation in the pathophysiology of cardiovascular (CV) diseases. The NLRP3 (NACHT, leucine-rich repeat, and pyrin domain-containing protein 3) inflammasome is activated during tissue injury and releases interleukin-1β (IL-1β). We describe three paradigms in which the NLRP3 inflammasome and IL-1β contribute to CV diseases. During acute myocardial infarction (AMI), necrotic cell debris, including IL-1α, induce NLRP3 inflammasome activation and further damage the myocardium contributing to heart failure (HF) (acute injury paradigm). In chronic HF, IL-1β is induced by persistent myocardial overload and injury, neurohumoral activation and systemic comorbidities favoring infiltration and activation of immune cells into the myocardium, microvascular inflammation, and a pro-fibrotic response (chronic inflammation paradigm). In recurrent pericarditis, an autoinflammatory response triggered by cell injury and maintained by the NLRP3 inflammasome/IL-1β axis is present (autoinflammatory disease paradigm). Anakinra, recombinant IL-1 receptor antagonist, inhibits the acute inflammatory response in patients with ST elevation myocardial infarction (STEMI) and acute HF. Canakinumab, IL-1β antibody, blunts systemic inflammation and prevents complications of atherosclerosis in stable patients with prior AMI. In chronic HF, anakinra reduces systemic inflammation and improves cardiorespiratory fitness. In recurrent pericarditis, anakinra and rilonacept, a soluble IL-1 receptor chimeric fusion protein blocking IL-1α and IL-1β, treat and prevent acute flares. In conclusion, the NLRP3 inflammasome and IL-1 contribute to the pathophysiology of CV diseases, and IL-1 blockade is beneficial with different roles in the acute injury, chronic inflammation and autoinflammatory disease paradigms. Further research is needed to guide the optimal use of IL-1 blockers in clinical practice.

The genetic advantage of healthy centenarians: unraveling the central role of NLRP3 in exceptional healthspan

Despite extensive research into extending human healthspan (HS) and compressing morbidity, the mechanisms underlying aging remain elusive. However, a better understanding of the genetic advantages responsible for the exceptional HS of healthy centenarians (HC), who live in good physical and mental health for one hundred or more years, could lead to innovative health-extending strategies. This review explores the role of NLRP3, a critical component of innate immunity that significantly impacts aging. It is activated by pathogen-associated signals and self-derived signals that increase with age, leading to low-grade inflammation implicated in age-related diseases. Furthermore, NLRP3 functions upstream in several molecular aging pathways, regulates cellular senescence, and may underlie the robust health observed in HC. By targeting NLRP3, mice exhibit a phenotype akin to that of HC, the HS of monkeys is extended, and aging symptoms are reversed in humans. Thus, targeting NLRP3 could offer a promising approach to extend HS. Additionally, a paradigm shift is proposed. Given that the HS of the broader population is 30 years shorter than that of HC, it is postulated that they suffer from a form of accelerated aging. The term 'auto-aging' is suggested to describe accelerated aging driven by NLRP3.

Intracerebroventricular infusion of secretoneurin inhibits neuronal NLRP3-Apoptosis pathway and preserves learning and memory after cerebral ischemia

Transient global cerebral ischemia (GCI) results in delayed neuronal death, primarily apoptosis, in the hippocampal CA1 subregion, which leads to severe cognitive deficits. While therapeutic hypothermia is an approved treatment for patients following cardiac arrest, it is associated with various adverse effects. Secretoneurin (SN) is an evolutionarily conserved neuropeptide generated in the brain, adrenal medulla and other endocrine tissues. In this study, SN was infused into the rat brain by intracerebroventricular injection 1 day after GCI, and we demonstrated that SN could significantly preserve spatial learning and memory in the Barnes maze tasks examined on days 14-17 after GCI. To further investigate underlying pathways involved, we demonstrated that, on day 5 after GCI, SN could significantly inhibit GCI-induced expression levels of Apoptosis Inducing Factor (AIF) and cleaved-PARP1, as well as neuronal apoptosis and synaptic loss in the hippocampal CA1 region. Additionally, SN could attenuate GCI-induced activation of both caspase-1 and caspase-3, and the levels of pro-inflammatory cytokines IL-1β and IL-18 in the CA1 region. Mechanically, we observed that treatment with SN effectively inhibited NLRP3 protein elevation and the bindings of NLRP3-ASC and ASC-caspase-1 in hippocampal neurons after GCI. In summary, our data indicate that SN could effectively attenuate NLRP3 inflammasome formation, as well as the activation of caspase-1 and -3, the production of pro-inflammatory cytokines, and ultimately the neuronal apoptotic loss induced by GCI. Potential neuronal pyroptosis, or caspase-1-dependent cell death, could also be involved in ischemic neuronal death, which needs further investigation.

Novel NLRP3 inhibitor INF195: Low doses provide effective protection against myocardial ischemia/reperfusion injury

BACKGROUND

Several factors contribute to ischemia/reperfusion injury (IRI), including activation of the NLRP3 inflammasome and its byproducts, such as interleukin-1β (IL-1β) and caspase-1. However, NLRP3 may paradoxically exhibit cardioprotective properties. This study aimed to assess the protective effects of the novel NLRP3 inhibitor, INF195, both in vitro and ex vivo.

METHODS

To investigate the relationship between NLRP3 and myocardial IRI, we synthetized a series of novel NLRP3 inhibitors, and investigated their putative binding mode via docking studies. Through in vitro studies we identified INF195 as optimal for NLRP3 inhibition. We measured infarct-size in isolated mouse hearts subjected to 30-min global ischemia/one-hour reperfusion in the presence of three different doses of INF195 (5, 10, or 20-μM). We analyzed caspase-1 and IL-1β concentration in cardiac tissue homogenates by ELISA. Statistical significance was determined using one-way ANOVA followed by Tukey's test.

RESULTS AND CONCLUSION

INF195 reduces NLRP3-induced pyroptosis in human macrophages. Heart pre-treatment with 5 and 10-μM INF195 significantly reduces both infarct size and IL-1β levels. Data suggest that intracardiac NLRP3 activation contributes to IRI and that low doses of INF195 exert cardioprotective effects by reducing infarct size. However, at 20-μM, INF195 efficacy declines, leading to a lack of cardioprotection. Research is required to determine if high doses of INF195 have off-target effects or dual roles, potentially eliminating both harmful and cardioprotective functions of NLRP3. Our findings highlight the potential of a new chemical scaffold, amenable to further optimization, to provide NLRP3 inhibition and cardioprotection in the ischemia/reperfusion setting.

Inhibitors of NLRP3 Inflammasome Formation: A Cardioprotective Role for the Gasotransmitters Carbon Monoxide, Nitric Oxide, and Hydrogen Sulphide in Acute Myocardial Infarction

Myocardial ischaemia reperfusion injury (IRI) occurring from acute coronary artery disease or cardiac surgical interventions such as bypass surgery can result in myocardial dysfunction, presenting as, myocardial "stunning", arrhythmias, infarction, and adverse cardiac remodelling, and may lead to both a systemic and a localised inflammatory response. This localised cardiac inflammatory response is regulated through the nucleotide-binding oligomerisation domain (NACHT), leucine-rich repeat (LRR)-containing protein family pyrin domain (PYD)-3 (NLRP3) inflammasome, a multimeric structure whose components are present within both cardiomyocytes and in cardiac fibroblasts. The NLRP3 inflammasome is activated via numerous danger signals produced by IRI and is central to the resultant innate immune response. Inhibition of this inherent inflammatory response has been shown to protect the myocardium and stop the occurrence of the systemic inflammatory response syndrome following the re-establishment of cardiac circulation. Therapies to prevent NLRP3 inflammasome formation in the clinic are currently lacking, and therefore, new pharmacotherapies are required. This review will highlight the role of the NLRP3 inflammasome within the myocardium during IRI and will examine the therapeutic value of inflammasome inhibition with particular attention to carbon monoxide, nitric oxide, and hydrogen sulphide as potential pharmacological inhibitors of NLRP3 inflammasome activation.

Research progress on the natural products in the intervention of myocardial infarction

Coronary heart disease is a prevalent cardiovascular ailment globally, with myocardial infarction (MI) being one of its most severe manifestations. The morbidity and mortality of MI are escalating, showing an increasing trend among younger, highly educated individuals, thereby posing a serious threat to public health. Currently, thrombolysis, percutaneous coronary intervention, and coronary artery bypass grafting are the primary clinical treatments for MI. Although these methods significantly reduce patient mortality, complications often result in poor prognoses. Due to limitations in chemical synthetic drug research, the focus has shifted towards developing herbs based on natural substances. Natural medicines represent a novel approach for safer and more effective MI management and treatment. They can control multiple pathogenic variables by targeting various pathways and systems. This paper investigates the molecular mechanisms of MI and evaluates the application of natural products and medicinal plants in MI treatment over the past 5 years, demonstrating their specific good therapeutic potential and superior tolerance. These natural therapies have been shown to mitigate myocardial cell damage caused by MI through mechanisms such as oxidative stress, inflammation, apoptosis, angiogenesis, myocardial fibrosis, autophagy, endoplasmic reticulum stress, mitophagy, and pyroptosis. This review offers the latest insights into the application of natural products and medicinal plants in MI treatment, elucidating their mechanisms of action and serving as an important reference for MI prevention.

Budesonide and N-acetylcysteine inhibit activation of the NLRP3 inflammasome by regulating miR-381 to alleviate acute lung injury caused by the pyroptosis-mediated inflammatory response

Background

The anti-inflammatory effects of budesonide (BUN) and N-acetylcysteine (NAC) attenuate acute lung injury (ALI). The aim of this study was to investigate the effects of combination therapy consisting of BUN and NAC on ALI and the underlying mechanisms.

Methods

In vitro and in vivo models of ALI were generated by LPS induction. Western blotting was used to detect the expression levels of pyroptosis-related proteins and inflammation-related factors, and RT-qPCR was used to detect the expression of miR-381. Cell proliferation and apoptosis were detected by CCK-8 and flow cytometry, respectively. ELISA was used to detect the levels of inflammation-related factors. HE staining was used to detect lung injury.

Results

The results showed that LPS effectively induced pyroptosis in cells and promoted the expression of pyroptosis-related proteins (Caspase1, Gasdermin D and NLRP3) and inflammatory cytokines (TNF-α, IL-6 and IL-1β). The combination of BUN and NAC significantly alleviated LPS-induced pyroptosis and inflammation. In addition, the combination of BUN and NAC effectively promoted miR-381 expression. Transfection of miR-381 mimics effectively alleviated LPS-induced pyroptosis and inflammation, while transfection of miR-381 inhibitors had the opposite effect. miR-381 negatively regulates NLRP3 expression. Treatment with a miR-381 inhibitor or pc-NLRP3 reversed the effects of the combination of BUN and NAC. In a mouse model of ALI, the combination of BUN and NAC effectively improved lung injury, while treatment with a miR-381 inhibitor or pc-NLRP3 effectively reversed this effect.

Conclusion

Overall, this study revealed that BUN + NAC inhibits the activation of NLRP3 by regulating miR-381, thereby alleviating ALI caused by pyroptosis-mediated inflammation.

Blockade of thromboxane A2 signaling attenuates ethanol-induced myocardial inflammatory response in mice

BACKGROUND

Alcohol-associated cardiomyopathy (ACM) is a cardiac muscle disease characterized by inflammation and oxidative stress. Thromboxane-prostanoid receptor (TP-R) plays an important role in the pathogenesis of cardiovascular disease. Herein, we hypothesize that TP-R mediates alcohol-induced early cardiac injury.

METHODS

Eight-week-old male C57BL/6 wild-type mice were fed a chronic ethanol (ET) or control diet (CON) for 10 days followed by a single binge of ethanol or maltose-dextrin through oral gavage. A cohort of ethanol-fed mice received SQ 29,548 (SQ), a TP-R antagonist. RNA sequencing, real-time PCR, and western blot analysis were performed on left ventricle to investigate alterations in genes and/or proteins mediating oxidative stress, inflammation, and cardiac remodeling. Sirius Red staining was performed to measure myocardial fibrosis.

RESULTS

RNA-sequencing analysis of myocardium from CON and ET groups identified 142 genes that were significantly altered between the two groups. In particular, the gene expression of thioredoxin-interacting protein (TXNIP), a component of NLR family pyrin domain containing 3 (NLRP3) signaling, which mediates oxidative stress and inflammatory response, was upregulated in response to ethanol exposure. The myocardial protein levels of TP-R and thromboxane A2 synthase were increased upon alcohol exposure. Ethanol increased the levels of 4-hydroxynonenal, a marker of oxidative stress, with a concomitant increase in the protein levels of TXNIP and NLRP3, and administration of SQ attenuated these effects. Additionally, ethanol increased the protein levels of pro-inflammatory mediators, including tumor necrosis factor alpha and the NLRP3 downstream product, secretory interleukin 1 beta, and SQ blunted these effects. Finally, the Sirius red staining of the myocardium revealed an increase in collagen deposition in ethanol-fed mice which was attenuated by TP-R antagonism.

CONCLUSION

This study demonstrates that ethanol promotes the NLRP3 signaling pathway within the myocardium, leading to a pro-inflammatory milieu that potentially initiates early myocardial remodeling, and TP-R antagonism attenuates this effect.

Cardiac hypertrophy that affects hyperthyroidism occurs independently of the NLRP3 inflammasome

Cardiac hypertrophy (CH) is an adaptive response to maintain cardiac function; however, persistent stress responses lead to contractile dysfunction and heart failure. Although inflammation is involved in these processes, the mechanisms that control cardiac inflammation and hypertrophy still need to be clarified. The NLRP3 inflammasome is a cytosolic multiprotein complex that mediates IL-1β production. The priming step of NLRP3 is essential for increasing the expression of its components and occurs following NF-κB activation. Hyperthyroidism triggers CH, which can progress to maladaptive CH and even heart failure. We have shown in a previous study that thyroid hormone (TH)-induced CH is linked to the upregulation of S100A8, leading to NF-κB activation. Therefore, we aimed to investigate whether the NLRP3 inflammasome is involved in TH-induced CH and its potential role in CH pathophysiology. Hyperthyroidism was induced in NLRP3 knockout (NLRP3-KO), Caspase-1-KO and Wild Type (WT) male mice of the C57Bl/6J strain, aged 8-12 weeks, by triiodothyronine (7 μg/100 g BW, i.p.) administered daily for 14 days. Morphological and cardiac functional analysis besides molecular assays showed, for the first time, that TH-induced CH is accompanied by reduced NLRP3 expression in the heart and that it occurs independently of the NLRP3 inflammasome and caspase 1-related pathways. However, NLRP3 is important for the maintenance of basal cardiac function since NLRP3-KO mice had impaired diastolic function and reduced heart rate, ejection fraction, and fractional shortening compared with WT mice.

Intracellular and extracellular Cyclophilin a promote cardiac fibrosis through TGF-β signaling in response to angiotensin Ⅱ

Cardiac fibrosis is characterized by abnormal proliferation of cardiac fibroblasts (CFs) and ventricular remodeling, which finally leads to heart failure. Inflammation and oxidative stress play a central role in the development of cardiac fibrosis. CyPA (Cyclophilin A) is a main proinflammatory cytokine secreted under the conditions of oxidative stress. The mechanisms by which intracellular and extracellular CyPA interact with CFs are unclear. Male C57BL/6 J mice received angiotensin Ⅱ (Ang Ⅱ) or vehicle for 4 weeks. Inhibition of CyPA significantly reversed Ang Ⅱ-induced cardiac hypertrophy and fibrosis. Mechanically, TGF-β (Transforming growth factor-β) signaling was found to be an indispensable downstream factor of CyPA-mediated myofibroblast differentiation and proliferation. Furthermore, intracellular CyPA and extracellular CyPA activate TGF-β signaling through NOD-like receptor protein 3 (NLRP3) inflammasome and nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase, respectively. Pharmacological inhibition of CyPA and its receptor CD147 implemented by Triptolide also attenuated the expression of TGF-β signaling and cardiac fibrosis in Ang Ⅱ-model. These studies elucidate a novel mechanism by which CyPA promotes TGF-β and its downstream signaling in CFs and identify CyPA (both intracellular and extracellular) as plausible therapeutic targets for preventing or treating cardiac fibrosis induced by chronic Ang Ⅱ stimulation.

NLRP3 inflammasome: a key player in the pathogenesis of life-style disorders

Proinflammatory cytokines and chemokines play a crucial role in regulating the inflammatory response, which is essential for the proper functioning of our immune system. When infections or threats to the body's defense mechanisms are detected, the innate immune system takes the lead. However, an excessive inflammatory response can lead to the production of high concentrations of cytotoxic molecules, resulting in tissue damage. Inflammasomes are significant contributors to innate immunity, and one of the most extensively studied inflammasome complexes is NOD-like receptor 3 (NLRP3). NLRP3 has a wide range of recognition mechanisms that streamline immune activation and eliminate pathogens. These cytosolic multiprotein complexes are composed of effector, adaptor, and sensor proteins, which are crucial for identifying intracellular bacterial breakdown products and initiating an innate immune cascade. To understand the diverse behavior of NLRP3 activation and its significance in the development of lifestyle-related diseases, one must delve into the study of the immune response and apoptosis mediated by the release of proinflammatory cytokines. In this review, we briefly explore the immune response in the context of lifestyle associated disorders such as obesity, hyperlipidemia, diabetes, chronic respiratory disease, oral disease, and cardiovascular disease.

Protective effects of 4-methylumbelliferone on myocardial ischemia/reperfusion injury in rats through inhibition of oxidative stress and downregulation of TLR4/NF-κB/NLRP3 signaling pathway

Myocardial ischemia-reperfusion injury (MI/R) has been found to be one of the important risk factors for global cardiac mortality and morbidity. The study was conducted to inquire into the protective effect of 4-methylumbilliferon (4-MU) against MI/R in rats and clarify its potential underlying mechanism. Animals were divided into four groups (n = 15) including sham, MI/R, MI/R + vehicle, and MI/R + 4-MU. MI/R was established in Wistar rats by occluding the left anterior descending (LAD) coronary artery for 30 min. 4-MU (25 mg/kg) was injected intraperitoneally before the induction of reperfusion. Cardiac function, fibrosis, oxidant/antioxidant markers, and inflammatory cytokines were evaluated using echocardiography, ELISA, and Western blot assay. As a result of MI/R induction, a decrease in left ventricular contractile function occurred along with increased cardiac fibrosis and tissue damage. The serum levels of TNF-α, IL-1β, and IL-18 increased, while IL-10 decreased. Oxidant/antioxidant changes were evident with increased MDA levels and decreased GSH, SOD, and CAT in the MI/R group. Furthermore, the protein levels of TLR4, NF-κB, and NLRP3 were significantly increased in the heart tissue of MI/R group. Treatment with 4-MU significantly prevented the reduction of cardiac contractile function and its pathological changes as a result of MI/R by inhibiting the increase of serum inflammatory factors and improving the oxidant/antioxidant balance probably through the TLR4/NF-κB/NLRP3 axis. The results of a current study showed that 4-MU had a potential ability to attenuate the cardiac injury by reducing oxidative stress and inflammation in a TLR4/NF-κB/NLRP3-dependent mechanism.

Antifibrotic effect of the P2X7 receptor antagonist A740003 against acute myocardial infarction-induced fibrotic remodelling

Post-acute myocardial infarction (AMI) fibrosis is a pathophysiologic process characterised by activation of the profibrotic mediator, transforming growth factor-β (TGF-β). AMI is associated with a substantial increase in the levels of extracellular adenosine triphosphate (eATP), which acts on the purinergic P2X7-receptor (P2X7-R) and triggers an inflammatory response that contributes to myocardial fibrotic remodelling. P2X7-R has been implicated in several cardiovascular diseases; however, its role in the regulation of cardiac fibrosis remains unclear. Therefore, the current study aimed to determine the effect of the P2X7-R antagonist, A740003, on post-AMI fibrosis, via the profibrotic TGF-β1/Smad signalling pathway, and elucidate whether its effect is mediated via the modulation of GSK-3β. AMI was induced by surgical ligation of the left anterior descending coronary artery, Thereafter, animals were divided into groups: sham control, MI-untreated, MI-vehicle, and MI-A740003 (50 mg/kg/day) and treated for seven days accordingly. The heart weight/body weight ratio of untreated-ligated rats significantly increased by 15.1 %, creatine kinase-MB (CK-MB) significantly increased by 40 %, troponin-I levels significantly increased by 25.4 %, and lactate dehydrogenase significantly increased by 47.2 %, indicating myocardial damage confirmed by morphological changes and massive cardiac fibrosis. The protein expression of cardiac fibronectin, TGF-β1, and p-Smad2 were also upregulated by 143 %, 40 %, and 8 %, respectively, indicating cardiac fibrosis. The treatment of ligated rats with A740003 led to improvement in all the above-mentioned parameters. Overall, A740003 exhibits potential cardio-protective effects on post-AMI fibrotic remodelling in the animal model of AMI through P2X7-R blockade, possibly by downregulating the profibrotic TGF-β1/Smad signalling pathway and restoring GSK-3β phosphorylation. Altogether, treatment with A740003 could serve as a new cardioprotective strategy to attenuate post-AMI fibrotic remodelling.

Neutrophil NLRP3 promotes cardiac injury following acute myocardial infarction through IL-1β production, VWF release and NET deposition in the myocardium

NLRP3 inflammasome has been implicated in neutrophil polarization and extrusion of neutrophil extracellular traps (NETs) in vitro and facilitates secretion of Il1-beta (IL-1β). Permanent ligation of the left anterior descending artery was used to induce MI in WT and NLRP3-/- mice as well as in NLRP3-/- recipient mice transfused with either WT or NLRP3-/- neutrophils. NLRP3 deficiency reduced infarct size to roughly a third of WT heart injury and preserved left ventricular (LV) function at 12 h after MI as assessed by echocardiography and triphenyltetrazolium chloride staining of live tissue. Transfusion of WT but not NLRP3-/- neutrophils after MI increased infarct size in NLRP3-/- mice and significantly reduced LV function. The key features of myocardial tissue in WT neutrophil transfused recipients were increased H3Cit-positive deposits with NET-like morphology and increased tissue levels of IL-1β and plasma levels of von Willebrand Factor (VWF). Flow cytometry analysis also revealed that neutrophil NLRP3 increased the number of labeled and transfused neutrophils in the bone marrow of recipient mice following MI. Our data suggest a key role for neutrophil NLRP3 in the production of IL-1β and deposition of NETs in cardiac tissue exacerbating injury following MI. We provide evidence for a link between neutrophil NLRP3 and VWF release likely enhancing thromboinflammation in the heart. Neutrophil NLRP3 deficiency conferred similar cardioprotective effects to general NLRP3 deletion in MI rendering anti-neutrophil NLRP3 therapy a promising target for early cardioprotective treatment.

Targeting the NLRP3 inflammasome signalling for the management of atrial fibrillation

Inflammatory signalling via the nod-like receptor (NLR) family pyrin domain-containing protein-3 (NLRP3) inflammasome has recently been implicated in the pathophysiology of atrial fibrillation (AF). However, the precise role of the NLRP3 inflammasome in various cardiac cell types is poorly understood. Targeting components or products of the inflammasome and preventing their proinflammatory consequences may constitute novel therapeutic treatment strategies for AF. In this review, we summarise the current understanding of the role of the inflammasome in AF pathogenesis. We first review the NLRP3 inflammasome pathway and inflammatory signalling in cardiomyocytes, (myo)fibroblasts and immune cells, such as neutrophils, macrophages and monocytes. Because numerous compounds targeting NLRP3 signalling are currently in preclinical development, or undergoing clinical evaluation for other indications than AF, we subsequently review known therapeutics, such as colchicine and canakinumab, targeting the NLRP3 inflammasome and evaluate their potential for treating AF.

Y4 RNA fragments from cardiosphere-derived cells ameliorate diabetic myocardial ischemia‒reperfusion injury by inhibiting protein kinase C β-mediated macrophage polarization

The specific pathophysiological pathways through which diabetes exacerbates myocardial ischemia/reperfusion (I/R) injury remain unclear; however, dysregulation of immune and inflammatory cells, potentially driven by abnormalities in their number and function due to diabetes, may play a significant role. In the present investigation, we simulated myocardial I/R injury by inducing ischemia through ligation of the left anterior descending coronary artery in mice for 40 min, followed by reperfusion for 24 h. Previous studies have indicated that protein kinase Cβ (PKCβ) is upregulated under hyperglycemic conditions and is implicated in the development of various diabetic complications. The Y4 RNA fragment is identified as the predominant small RNA component present in the extracellular vesicles of cardio sphere-derived cells (CDCs), exhibiting notable anti-inflammatory properties in the contexts of myocardial infarction and cardiac hypertrophy. Our investigation revealed that the administration of Y4 RNA into the ventricular cavity of db/db mice following myocardial I/R injury markedly enhanced cardiac function. Furthermore, Y4 RNA was observed to facilitate M2 macrophage polarization and interleukin-10 secretion through the suppression of PKCβ activation. The mechanism by which Y4 RNA affects PKCβ by regulating macrophage activation within the inflammatory environment involves the inhibition of ERK1/2 phosphorylation In our study, the role of PKCβ in regulating macrophage polarization during myocardial I/R injury was investigated through the use of PKCβ knockout mice. Our findings indicate that PKCβ plays a crucial role in modulating the inflammatory response associated with macrophage activation in db/db mice experiencing myocardial I/R, with a notable exacerbation of this response observed upon significant upregulation of PKCβ expression. In vitro studies further elucidated the protective mechanism by which Y4 RNA modulates the PKCβ/ERK1/2 signaling pathway to induce M2 macrophage activation. Overall, our findings suggest that Y4 RNA plays an anti-inflammatory role in diabetic I/R injury, suggesting a novel therapeutic approach for managing myocardial I/R injury in diabetic individuals.

Repair of the Infarcted Heart: Cellular Effectors, Molecular Mechanisms and Therapeutic Opportunities

The adult mammalian heart has limited endogenous regenerative capacity and heals through the activation of inflammatory and fibrogenic cascades that ultimately result in the formation of a scar. After infarction, massive cardiomyocyte death releases a broad range of damage-associated molecular patterns that initiate both myocardial and systemic inflammatory responses. TLRs (toll-like receptors) and NLRs (NOD-like receptors) recognize damage-associated molecular patterns (DAMPs) and transduce downstream proinflammatory signals, leading to upregulation of cytokines (such as interleukin-1, TNF-α [tumor necrosis factor-α], and interleukin-6) and chemokines (such as CCL2 [CC chemokine ligand 2]) and recruitment of neutrophils, monocytes, and lymphocytes. Expansion and diversification of cardiac macrophages in the infarcted heart play a major role in the clearance of the infarct from dead cells and the subsequent stimulation of reparative pathways. Efferocytosis triggers the induction and release of anti-inflammatory mediators that restrain the inflammatory reaction and set the stage for the activation of reparative fibroblasts and vascular cells. Growth factor-mediated pathways, neurohumoral cascades, and matricellular proteins deposited in the provisional matrix stimulate fibroblast activation and proliferation and myofibroblast conversion. Deposition of a well-organized collagen-based extracellular matrix network protects the heart from catastrophic rupture and attenuates ventricular dilation. Scar maturation requires stimulation of endogenous signals that inhibit fibroblast activity and prevent excessive fibrosis. Moreover, in the mature scar, infarct neovessels acquire a mural cell coat that contributes to the stabilization of the microvascular network. Excessive, prolonged, or dysregulated inflammatory or fibrogenic cascades accentuate adverse remodeling and dysfunction. Moreover, inflammatory leukocytes and fibroblasts can contribute to arrhythmogenesis. Inflammatory and fibrogenic pathways may be promising therapeutic targets to attenuate heart failure progression and inhibit arrhythmia generation in patients surviving myocardial infarction.

Pyroptosis and mitochondrial function participated in miR-654-3p-protected against myocardial infarction

Myocardial infarction (MI) is one of the leading causes of heart failure with highly complicated pathogeneses. miR-654-3p has been recognized as a pivotal regulator of controlling cell survival. However, the function of miR-654-3p in cardiomyocytes and MI has yet to be reported. This study aimed to identify the role of miR-654-3p in the regulation of myocardial infarction. To understand the contribution of miR-654-3p on heart function, we generated cardiac-specific knockdown and overexpression mice using AAV9 technology in MI injury. Mechanically, we combined cellular and molecular techniques, pharmaceutical treatment, RNA sequencing, and functional testing to elucidate the potential pathological mechanisms. We identified that mice subjected to MI decreased the expression of miR-654-3p in the border and infarcted area. Mice lacking miR-654-3p in the heart showed some inflammation infiltration and myocardial fibrosis, resulting in a mild cardiac injury. Furthermore, we found a deficiency of miR-654-3p in cardiomyocytes resulted in pyroptotic cell death but not other programmed cell death. Intriguingly, miR-654-3p deficiency aggravated MI-induced cardiac dysfunction, accompanied by higher myocardial fibrosis and cardiac enzymes and augmented pyroptosis activation. Cardiac elevating miR-654-3p prevented myocardial fibrosis and inflammation infiltration and decreased pyroptosis profile, thereby attenuating MI-induced cardiac damage. Using RNA sequence and molecular biological approaches, we found overexpression of miR-654-3p in the heart promoted the metabolic ability of the cardiomyocytes by promoting mitochondrial metabolism and mitochondrial respiration function. Our finding identified the character of miR-654-3p in protecting against MI damage by mediating pyroptosis and mitochondrial metabolism. These findings provide a new mechanism for miR-654-3p involvement in the pathogenesis of MI and reveal novel therapeutic targets. miR-654-3p expression was decreased after MI. Mice lacking miR-654-3p in the heart showed some inflammation infiltration and myocardial fibrosis, resulting in a mild cardiac injury. The deficiency of miR-654-3p in cardiomyocytes resulted in pyroptotic cell death. miR-654-3p deficiency aggravated MI-induced cardiac dysfunction, accompanied by higher myocardial fibrosis and cardiac enzymes and augmented pyroptosis activation. Overexpression of miR-654-3p prevented myocardial fibrosis and inflammation infiltration and decreased pyroptosis profile, thereby attenuating MI-induced cardiac damage. Overexpression of miR-654-3p in the heart promoted the metabolic ability of the cardiomyocytes by promoting mitochondrial metabolism and mitochondrial respiration function.

Cardioprotective properties of OMT-28, a synthetic analog of omega-3 epoxyeicosanoids

OMT-28 is a metabolically robust small molecule developed to mimic the structure and function of omega-3 epoxyeicosanoids. However, it remained unknown to what extent OMT-28 also shares the cardioprotective and anti-inflammatory properties of its natural counterparts. To address this question, we analyzed the ability of OMT-28 to ameliorate hypoxia/reoxygenation (HR)-injury and lipopolysaccharide (LPS)-induced endotoxemia in cultured cardiomyocytes. Moreover, we investigated the potential of OMT-28 to limit functional damage and inflammasome activation in isolated perfused mouse hearts subjected to ischemia/reperfusion (IR) injury. In the HR model, OMT-28 (1 μM) treatment largely preserved cell viability (about 75 versus 40% with the vehicle) and mitochondrial function as indicated by the maintenance of NAD+/NADH-, ADP/ATP-, and respiratory control ratios. Moreover, OMT-28 blocked the HR-induced production of mitochondrial reactive oxygen species. Pharmacological inhibition experiments suggested that Gαi, PI3K, PPARα, and Sirt1 are essential components of the OMT-28-mediated pro-survival pathway. Counteracting inflammatory injury of cardiomyocytes, OMT-28 (1 μM) reduced LPS-induced increases in TNFα protein (by about 85% versus vehicle) and NF-κB DNA binding (by about 70% versus vehicle). In the ex vivo model, OMT-28 improved post-IR myocardial function recovery to reach about 40% of the baseline value compared to less than 20% with the vehicle. Furthermore, OMT-28 (1 μM) limited IR-induced NLRP3 inflammasome activation similarly to a direct NLRP3 inhibitor (MCC950). Overall, this study demonstrates that OMT-28 possesses potent cardio-protective and anti-inflammatory properties supporting the hypothesis that extending the bioavailability of omega-3 epoxyeicosanoids may improve their prospects as therapeutic agents.

Initial Despair and Current Hope of Identifying a Clinically Useful Treatment of Myocardial Reperfusion Injury: Insights Derived from Studies of Platelet P2Y12 Antagonists and Interference with Inflammation and NLRP3 Assembly

Myocardial necrosis following the successful reperfusion of a coronary artery occluded by thrombus in a patient presenting with ST-elevation myocardial infarction (STEMI) continues to be a serious problem, despite the multiple attempts to attenuate the necrosis with agents that have shown promise in pre-clinical investigations. Possible reasons include confounding clinical risk factors, the delayed application of protective agents, poorly designed pre-clinical investigations, the possible effects of routinely administered agents that might unknowingly already have protected the myocardium or that might have blocked protection, and the biological differences of the myocardium in humans and experimental animals. A better understanding of the pathobiology of myocardial infarction is needed to stem this reperfusion injury. P2Y12 receptor antagonists minimize platelet aggregation and are currently part of the standard treatment to prevent thrombus formation and propagation in STEMI protocols. Serendipitously, these P2Y12 antagonists also dramatically attenuate reperfusion injury in experimental animals and are presumed to provide a similar protection in STEMI patients. However, additional protective agents are needed to further diminish reperfusion injury. It is possible to achieve additive protection if the added intervention protects by a mechanism different from that of P2Y12 antagonists. Inflammation is now recognized to be a critical factor in the complex intracellular response to ischemia and reperfusion that leads to tissue necrosis. Interference with cardiomyocyte inflammasome assembly and activation has shown great promise in attenuating reperfusion injury in pre-clinical animal models. And the blockade of the executioner protease caspase-1, indeed, supplements the protection already seen after the administration of P2Y12 antagonists. Importantly, protective interventions must be applied in the first minutes of reperfusion, if protection is to be achieved. The promise of such a combination of protective strategies provides hope that the successful attenuation of reperfusion injury is attainable.

Pyroptosis in myocardial ischemia/reperfusion and its therapeutic implications

Ischemic heart disease, a prevalent cardiovascular disease with global significance, is associated with substantial morbidity. Timely and successful reperfusion is crucial for reducing infarct size and enhancing clinical outcomes. However, reperfusion may induce additional myocardium injury, manifesting as myocardial ischemia/reperfusion (MI/R) injury. Pyroptosis is a regulated cell death pathway, the signaling pathway of which is activated during MI/R injury. In this process, the inflammasomes are triggered, initiating the cleavage of gasdermin proteins and pro-interleukins, which results in the formation of membrane pores and the maturation and secretion of inflammatory cytokines. Numerous preclinical evidence underscores the pivotal role of pyroptosis in MI/R injury. Inhibiting pyroptosis is cardioprotective against MI/R injury. Although certain agents exhibiting promise in preclinical studies for attenuating MI/R injury through inhibiting pyroptosis have been identified, the suitability of these compounds for clinical trials remains untested. This review comprehensively summarizes the recent developments in this field, with a specific emphasis on the impact of pyroptosis on MI/R injury. Deciphering these findings not only sheds light on new disease mechanisms but also paves the way for innovative treatments. And then the exploration of the latest advances in compounds that inhibit pyroptosis in MI/R is discussed, which aims to provide insights into potential therapeutic strategies and identify avenues for future research in the pursuit of effective clinical interventions.

The cGAS-STING pathway in cardiovascular diseases: from basic research to clinical perspectives

The cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase-stimulator of interferon genes (cGAS-STING) signaling pathway, an important component of the innate immune system, is involved in the development of several diseases. Ectopic DNA-induced inflammatory responses are involved in several pathological processes. Repeated damage to tissues and metabolic organelles releases a large number of damage-associated molecular patterns (mitochondrial DNA, nuclear DNA, and exogenous DNA). The DNA fragments released into the cytoplasm are sensed by the sensor cGAS to initiate immune responses through the bridging protein STING. Many recent studies have revealed a regulatory role of the cGAS-STING signaling pathway in cardiovascular diseases (CVDs) such as myocardial infarction, heart failure, atherosclerosis, and aortic dissection/aneurysm. Furthermore, increasing evidence suggests that inhibiting the cGAS-STING signaling pathway can significantly inhibit myocardial hypertrophy and inflammatory cell infiltration. Therefore, this review is intended to identify risk factors for activating the cGAS-STING pathway to reduce risks and to simultaneously further elucidate the biological function of this pathway in the cardiovascular field, as well as its potential as a therapeutic target.

Interleukin-1 receptor accessory protein blockade limits the development of atherosclerosis and reduces plaque inflammation

AIMS

The interleukin-1 receptor accessory protein (IL1RAP) is a co-receptor required for signalling through the IL-1, IL-33, and IL-36 receptors. Using a novel anti-IL1RAP-blocking antibody, we investigated the role of IL1RAP in atherosclerosis.

METHODS AND RESULTS

Single-cell RNA sequencing data from human atherosclerotic plaques revealed the expression of IL1RAP and several IL1RAP-related cytokines and receptors, including IL1B and IL33. Histological analysis showed the presence of IL1RAP in both the plaque and adventitia, and flow cytometry of murine atherosclerotic aortas revealed IL1RAP expression on plaque leucocytes, including neutrophils and macrophages. High-cholesterol diet fed apolipoprotein E-deficient (Apoe-/-) mice were treated with a novel non-depleting IL1RAP-blocking antibody or isotype control for the last 6 weeks of diet. IL1RAP blockade in mice resulted in a 20% reduction in subvalvular plaque size and limited the accumulation of neutrophils and monocytes/macrophages in plaques and of T cells in adventitia, compared with control mice. Indicative of reduced plaque inflammation, the expression of several genes related to leucocyte recruitment, including Cxcl1 and Cxcl2, was reduced in brachiocephalic arteries of anti-IL1RAP-treated mice, and the expression of these chemokines in human plaques was mainly restricted to CD68+ myeloid cells. Furthermore, in vitro studies demonstrated that IL-1, IL-33, and IL-36 induced CXCL1 release from both macrophages and fibroblasts, which could be mitigated by IL1RAP blockade.

CONCLUSION

Limiting IL1RAP-dependent cytokine signalling pathways in atherosclerotic mice reduces plaque burden and plaque inflammation, potentially by limiting plaque chemokine production.

25-hydroxycholesterol aggravates oxygen-glucose deprivation/reoxygenation-induced pyroptosis through promoting activation of NLRP3 inflammasome in H9C2 cardiomyocytes

25-hydroxycholesterol (25-HC) plays a role in the regulation of cell survival and immunity. However, the effect of 25-HC on myocardial ischemia/reperfusion (MI/R) injury remains unknown. Our present study aimed to investigate whether 25-HC aggravated MI/R injury through NLRP3 inflammasome-mediated pyroptosis. The overlapping differentially expressed genes (DEGs) in MI/R were identified from the GSE775, GSE45818, GSE58486, and GSE46395 datasets in Gene Expression Omnibus (GEO) database. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted using the database of Annotation, Visualization and Integration Discovery (DAVID). The protein-protein interaction (PPI) network of the overlapping DEGs was established using the Search Tool for the Retrieval of Interacting Genes (STRING) database. These bioinformatics analyses indicated that cholesterol 25-hydroxylase (CH25H) was one of the crucial genes in MI/R injury. The oxygen-glucose deprivation/reoxygenation (OGD/R) cell model was established to simulate MI/R injury. Western blot and RT-qPCR analysis demonstrated that CH25H was significantly upregulated in OGD/R-stimulated H9C2 cardiomyocytes. Moreover, knockdown of CH25H inhibited the OGD/R-induced pyroptosis and nod-like receptor protein 3 (NLRP3) inflammasome activation, as demonstrated by cell counting kit-8 (CCK8), lactate dehydrogenase (LDH), RT-qPCR, and western blotting assays. Conversely, 25-HC, which is synthesized by CH25H, promoted activation of NLRP3 inflammasome in OGD/R-stimulated H9C2 cardiomyocytes. In addition, the NLRP3 inhibitor BAY11-7082 attenuated 25-HC-induced H9C2 cell injury and pyroptosis under OGD/R condition. In conclusion, 25-HC could aggravate OGD/R-induced pyroptosis through promoting activation of NLRP3 inflammasome in H9C2 cells.

Polystyrene nanoplastics and cadmium co-exposure aggravated cardiomyocyte damage in mice by regulating PANoptosis pathway

Micro/nanoplastics (M/NPs) are the novel contaminants ubiquitous in the environment. Cadmium (Cd), a kind of heavy metal pollutant widely distributed, could potentially co-exist with PS-NPs in the environment. However, their combined effects on cardiomyocyte and its molecular mechanism in mammals remained ambiguous. Here, we examined whether PANoptosis, an emerging and complicated kind of programmed cell death, was involved in PS-NPs and Cd co-exposure-elicited cardiac injury. In this study, 60 male mice were orally subjected to environmentally relevant concentrations of PS-NPs (1 mg/kg) and/or CdCl2 (1.5 mg/kg) for 35 days. As we speculated, PS-NPs and Cd co-exposure affected the expression of pyroptosis(Caspase-1, Cleaved-Caspase-1, GSDMD, N-GSDMD, AIM2, Pyrin, NLRP3, IL-18, IL-1β)-, apoptosis(Caspase-3, Cleaved-Caspase-3, Caspase-8, Cleaved-Caspase-8, Caspase-7, BAX)- and necroptosis (t-RIPK3, p-RIPK3, t-RIPK1, p-RIPK1, t-MLKL, p-MLKL, ZBP1)-related genes and protein, resulting in growth restriction and damaged myocardial microstructure in mice. Notably, the combined effects on Cd and PS-NPs even predominantly aggravated the toxic damage. Intriguingly, we fortuitously discovered PS-NPs and/or Cd exposure facilitated linear ubiquitination of certain proteins in mice myocardium. In summation, this study shed light toward the effects of Cd and PS-NPs on cardiotoxicity, advanced the understanding of myocardial PANoptosis and provided a scientific foundation for further exploration of the combined toxicological effects of PS-NPs and heavy metals.

NLRP3 inflammasome and pyroptosis in cardiovascular diseases and exercise intervention

NOD-like receptor protein 3 (NLRP3) inflammasome is an intracellular sensing protein complex that possesses NACHT, leucine-rich repeat, and pyrin domain, playing a crucial role in innate immunity. Activation of the NLRP3 inflammasome leads to the production of pro-inflammatory cellular contents, such as interleukin (IL)-1β and IL-18, and induction of inflammatory cell death known as pyroptosis, thereby amplifying or sustaining inflammation. While a balanced inflammatory response is beneficial for resolving damage and promoting tissue healing, excessive activation of the NLRP3 inflammasome and pyroptosis can have harmful effects. The involvement of the NLRP3 inflammasome has been observed in various cardiovascular diseases (CVD). Indeed, the NLRP3 inflammasome and its associated pyroptosis are closely linked to key cardiovascular risk factors including hyperlipidemia, diabetes, hypertension, obesity, and hyperhomocysteinemia. Exercise compared with medicine is a highly effective measure for both preventing and treating CVD. Interestingly, emerging evidence suggests that exercise improves CVD and inhibits the activity of NLRP3 inflammasome and pyroptosis. In this review, the activation mechanisms of the NLRP3 inflammasome and its pathogenic role in CVD are critically discussed. Importantly, the purpose is to emphasize the crucial role of exercise in managing CVD by suppressing NLRP3 inflammasome activity and proposes it as the foundation for developing novel treatment strategies.

Research progress on the improvement of cardiovascular diseases through the autonomic nervous system regulation of the NLRP3 inflammasome pathway

Cardiovascular disease stands as a leading global cause of mortality. Nucleotide-binding Oligomerization Domain-like Receptor Protein 3 (NLRP3) inflammasome is widely acknowledged as pivotal factor in specific cardiovascular disease progression, such as myocardial infarction, heart failure. Recent investigations underscore a close interconnection between autonomic nervous system (ANS) dysfunction and cardiac inflammation. It has been substantiated that sympathetic nervous system activation and vagus nerve stimulation (VNS) assumes critical roles withinNLRP3 inflammasome pathway regulation, thereby contributing to the amelioration of cardiac injury and enhancement of prognosis in heart diseases. This article reviews the nexus between NLRP3 inflammasome and cardiovascular disorders, elucidating the modulatory functions of the sympathetic and vagus nerves within the ANS with regard to NLRP3 inflammasome. Furthermore, it delves into the potential therapeutic utility of NLRP3 inflammasome to be targeted by VNS. This review serves as a valuable reference for further exploration into the potential mechanisms underlying VNS in the modulation of NLRP3 inflammasome.

Investigating the expression level of miR-17-3p, miR-101-3p, miR-335-3p, and miR-296-3p in the peripheral blood of patients with acute myocardial infarction

The role of inflammation has been proven in acute myocardial infarction (AMI) pathogenesis. Due to the effect of NLRP3 gene expression in the inflammation process of MI, we aimed to explore the expression changes and diagnostic power of four inflammation-related miRNAs including miR-17-3p, miR-101-3p, miR-335-3p, miR-296-3p and their potential target, NLRP3, in ST-segment elevation myocardial infarction (STEMI), and non-STEMI (NSTEMI) patients as two major classes of AMI. The expression level of these genes were evaluated in 300 participants equally divided into three groups of STEMI, NSTEMI, and control using quantitative real-time PCR. The expression level of NLRP3 was upregulated in STEMI and NSTEMI patients compared to control subjects. Besides, the expression levels of miR-17-3p, miR-101-3p, and miR-296-3p were significantly downregulated in STEMI and NSTEMI patients compared to controls. The increased expression of NLRP3 had a very strong inverse correlation with miR-17-3p in patients with STEMI and with miR-101-3p in the STEMI and NSTEMI patients. ROC curve analysis showed that the expression level of miR-17-3p had the highest diagnostic power for discrimination between STEMI patients and controls. Remarkably, the combination of all markers resulted in a higher AUC. In summary, there is a significant association between the expression levels of miR-17-3p, miR-101-3p, miR-335-3p, miR-296-3p, and NLRP3 and the incidence of AMI. Although the miR-17-3p expression level has the highest diagnostic power to distinguish between STEMI patients and control subjects, the combination of these miRNAs and NLRP3 could serve as a novel potential diagnostic biomarker of STEMI.

The role of the NLRP3 inflammasome and pyroptosis in cardiovascular diseases

An intense, stereotyped inflammatory response occurs in response to ischaemic and non-ischaemic injury to the myocardium. The NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome is a finely regulated macromolecular protein complex that senses the injury and triggers and amplifies the inflammatory response by activation of caspase 1; cleavage of pro-inflammatory cytokines, such as pro-IL-1β and pro-IL-18, to their mature forms; and induction of inflammatory cell death (pyroptosis). Inhibitors of the NLRP3 inflammasome and blockers of IL-1β and IL-18 activity have been shown to reduce injury to the myocardium and pericardium, favour resolution of the inflammation and preserve cardiac function. In this Review, we discuss the components of the NLRP3 inflammasome and how it is formed and activated in various ischaemic and non-ischaemic cardiac pathologies (acute myocardial infarction, cardiac dysfunction and remodelling, atherothrombosis, myocarditis and pericarditis, cardiotoxicity and cardiac sarcoidosis). We also summarize current preclinical and clinical evidence from studies of agents that target the NLRP3 inflammasome and related cytokines.

Mesenchymal stromal cells for improvement of cardiac function following acute myocardial infarction: a matter of timing

Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

When Our Best Friend Becomes Our Worst Enemy: The Mitochondrion in Trauma, Surgery, and Critical Illness

Common for major surgery, multitrauma, sepsis, and critical illness, is a whole-body inflammation. Tissue injury is able to trigger a generalized inflammatory reaction. Cell death causes release of endogenous structures termed damage associated molecular patterns (DAMPs) that initiate a sterile inflammation. Mitochondria are evolutionary endosymbionts originating from bacteria, containing molecular patterns similar to bacteria. These molecular patterns are termed mitochondrial DAMPs (mDAMPs). Mitochondrial debris released into the extracellular space or into the circulation is immunogenic and damaging secondary to activation of the innate immune system. In the circulation, released mDAMPS are either free or exist in extracellular vesicles, being able to act on every organ and cell in the body. However, the role of mDAMPs in trauma and critical care is not fully clarified. There is a complete lack of knowledge how they may be counteracted in patients. Among mDAMPs are mitochondrial DNA, cardiolipin, N-formyl peptides, cytochrome C, adenosine triphosphate, reactive oxygen species, succinate, and mitochondrial transcription factor A. In this overview, we present the different mDAMPs, their function, release, targets, and inflammatory potential. In light of present knowledge, the role of mDAMPs in the pathophysiology of major surgery and trauma as well as sepsis, and critical care is discussed.

Deletion of Interleukin-1β Converting Enzyme Alters Mouse Cardiac Structure and Function

Interleukin-1β converting enzyme (ICE, caspase-1) is a thiol protease that cleaves the pro-inflammatory cytokine precursors of IL-1β and IL-18 into active forms. Given the association between caspase-1 and cardiovascular pathology, we analyzed the hearts of ICE knockout (ICE KO) mice to test the hypothesis that caspase-1 plays a significant role in cardiac morphology and function. We characterized the histological and functional changes in the hearts of ICE KO mice compared to the Wild type. The cardiomyocytes from the neonatal ICE KO mice showed an impaired response to oxidative stress. Subsequently, the hearts from the ICE KO mice were hypertrophied, with a significant increase in the left ventricular and septal wall thickness and a greater LV mass/body weight ratio. The ICE KO mice hearts exhibited irregular myofibril arrangements and disruption of the cristae in the mitochondrial structure. Proapoptotic proteins that were significantly increased in the hearts of ICE KO versus the Wild type included pErk, pJNK, p53, Fas, Bax, and caspase 3. Further, the antiapoptotic proteins Bag-1 and Bcl-2 are activated in ICE KO hearts. Functionally, there was an increase in the left ventricular epicardial diameter and volume in ICE KO. In conclusion, our findings support the important role of caspase-1 in maintaining cardiac health; specifically, a significant decrease in caspase-1 is detrimental to the cardiovascular system.

Regulated cell death in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion (I/R) injury most commonly occurs in coronary artery disease when prompt reperfusion is used to salvage the ischemic myocardium. Cardiomyocyte death is a significant component of myocardial I/R injury and its mechanism was previously thought to be limited to apoptosis and necrosis. With the discovery of novel types of cell death, ferroptosis, necroptosis, and pyroptosis have been shown to be involved in myocardial I/R. These new forms of regulated cell death cause cardiomyocyte loss and exacerbate I/R injury by affecting reactive oxygen species (ROS) generation, calcium stress, and inflammatory cascades, subsequently mediating adverse remodeling, cardiac dysfunction, and heart failure. Herein, we review the roles of ferroptosis, necroptosis, and pyroptosis in myocardial I/R and discuss their contribution to pathology.

The E3 ubiquitin ligase MARCH2 protects against myocardial ischemia-reperfusion injury through inhibiting pyroptosis via negative regulation of PGAM5/MAVS/NLRP3 axis

Inflammasome activation and pyroptotic cell death are known to contribute to the pathogenesis of cardiovascular diseases, such as myocardial ischemia-reperfusion (I/R) injury, although the underlying regulatory mechanisms remain poorly understood. Here we report that expression levels of the E3 ubiquitin ligase membrane-associated RING finger protein 2 (MARCH2) were elevated in ischemic human hearts or mouse hearts upon I/R injury. Genetic ablation of MARCH2 aggravated myocardial infarction and cardiac dysfunction upon myocardial I/R injury. Single-cell RNA-seq analysis suggested that loss of MARCH2 prompted activation of NLRP3 inflammasome in cardiomyocytes. Mechanistically, phosphoglycerate mutase 5 (PGAM5) was found to act as a novel regulator of MAVS-NLRP3 signaling by forming liquid-liquid phase separation condensates with MAVS and fostering the recruitment of NLRP3. MARCH2 directly interacts with PGAM5 to promote its K48-linked polyubiquitination and proteasomal degradation, resulting in reduced PGAM5-MAVS co-condensation, and consequently inhibition of NLRP3 inflammasome activation and cardiomyocyte pyroptosis. AAV-based re-introduction of MARCH2 significantly ameliorated I/R-induced mouse heart dysfunction. Altogether, our findings reveal a novel mechanism where MARCH2-mediated ubiquitination negatively regulates the PGAM5/MAVS/NLRP3 axis to protect against cardiomyocyte pyroptosis and myocardial I/R injury.

Buyang Huanwu Decoction suppresses cardiac inflammation and fibrosis in mice after myocardial infarction through inhibition of the TLR4 signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

It has been reported that cardiac inflammation and fibrosis participate in the development of heart failure (HF) following myocardial infarction (MI). Anti-inflammatory and anti-fibrotic treatments exhibit therapeutic efficacy in MI. Buyang Huanwu Decoction (BYHWD) has cardioprotective properties. However, whether BYHWD regulates cardiac inflammation and fibrosis in HF after MI, and the underlying mechanisms, are still unknown.

AIM OF THE STUDY

This study aimed to explore the effects and potential mechanisms of BYHWD on cardiac inflammation and fibrosis after MI.

MATERIALS AND METHODS

An MI model was constructed through ligation of the left anterior descending coronary artery (LAD) in mice. The cardioprotective effects of BYHWD were determined by echocardiography, Masson trichrome staining, wheat germ agglutinin (WGA) staining and haematoxylin and eosin (HE) staining. The effects of BYHWD on inflammation and fibrosis, and on the TLR4 signalling pathway, were explored through immunohistochemistry (IHC), Western blot (WB), enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) in vivo. Next, the effects of BYHWD on primary cardiac fibroblasts (CFs) inflammation and collagen synthesis, and on the TLR4 signalling pathway, were detected using WB, immunofluorescence (IF) and qRT-PCR in vitro. In addition, the suppression and overexpression of TLR4 in CFs were further explored.

RESULTS

BYHWD dose-dependently reduced cardiac inflammation, fibrosis and ventricular dysfunction. The expression levels of collagen Ⅰ/Ⅲ, IL-1β and IL-18, as well as critical proteins in the TLR4 signalling pathway and the NLRP3 inflammasome, were suppressed by BYHWD in the in vivo experiment. BYHWD inhibited CFs inflammation and collagen synthesis, as well as critical proteins in the TLR4 signalling pathway and the NLRP3 inflammasome, in the in vitro experiment. TLR4 suppression mitigated these inhibitory effects of BYHWD while overexpression of TLR4 markedly reversed these inhibitory effects of BYHWD.

CONCLUSION

BYHWD exerts anti-inflammatory and anti-fibrotic effects in mice after MI, and suppresses CFs inflammation and collagen synthesis through suppression of the TLR4 signalling pathway.

The therapeutic potential of ketones in cardiometabolic disease: impact on heart and skeletal muscle

β-Hydroxybutyrate (βOHB) is the major ketone in the body, and it is recognized as a metabolic energy source and an important signaling molecule. While ketone oxidation is essential in the brain during prolonged fasting/starvation, other organs such as skeletal muscle and the heart also use ketones as metabolic substrates. Additionally, βOHB-mediated molecular signaling events occur in heart and skeletal muscle cells, and via metabolism and/or signaling, ketones may contribute to optimal skeletal muscle health and cardiac function. Of importance, when the use of ketones for ATP production and/or as signaling molecules becomes disturbed in the presence of underlying obesity, type 2 diabetes, and/or cardiovascular diseases, these changes may contribute to cardiometabolic disease. As a result of these disturbances in cardiometabolic disease, multiple approaches have been used to elevate circulating ketones with the goal of optimizing either ketone metabolism or ketone-mediated signaling. These approaches have produced significant improvements in heart and skeletal muscle during cardiometabolic disease with a wide range of benefits that include improved metabolism, weight loss, better glycemic control, improved cardiac and vascular function, as well as reduced inflammation and oxidative stress. Herein, we present the evidence that indicates that ketone therapy could be used as an approach to help treat cardiometabolic diseases by targeting cardiac and skeletal muscles.

Fumaria indica (Hausskn.) Pugsley Hydromethanolic Extract: Bioactive Compounds Identification, Hypotensive Mechanism, and Cardioprotective Potential Exploration

Fumaria indica (Hausskn.) Pugsley (FIP), a member of the Papaveraceae family, has a documented history of use in traditional medicine to treat cardiovascular ailments, particularly hypertension, and has shown substantial therapeutic efficacy among native cultures worldwide. However, the identification of bioactive compounds and the mechanism of hypotensive effect with the cardioprotective potential investigations are yet to be determined. The study aimed to identify bioactive compounds, explore the hypotensive mechanism and cardioprotective potential, and assess the safety of Fumaria indica (Hausskn.) Pugsley hydromethanolic extract (Fip.Cr). LC ESI-MS/MS analysis was performed to identify the bioactive compounds. In vitro experiments were conducted on isolated rat aorta and atria, and an in vivo invasive BP measurement model was used. Acute and subacute toxicities were assessed for 14 and 28 days, respectively. Isoproterenol (ISO) was used to develop the rats' myocardial infarction damage model. The mRNA levels of NLRP3 inflammasome and the abundance level of Firmicutes and Lactobacillus were measured by qRT-PCR. The hypotensive effect of FIP bioactive compounds was also investigated using in silico methods. Fip. Cr LC ESI-MS/MS analysis discovered 33 bioactive compounds, including alkaloids and flavonoids. In isolated rat aorta, Fip.Cr reversed contractions induced by K+ (80 mM), demonstrating a calcium entry-blocking function, and had a vasorelaxant impact on phenylephrine (PE) (1 μM)-induced contractions unaffected by L-NAME, ruling out endothelial NO participation. Fip.Cr caused negative chronotropic and inotropic effects in isolated rat atria unaffected by atropine pretreatment, eliminating cardiac muscarinic receptor involvement. Safety evaluation showed no major adverse effects. In vivo, invasive BP measurement demonstrated a hypotensive effect comparable to verapamil. Fip.Cr protected the rats from ISO-induced MI interventions significantly in biometrical and cardiac serum biochemical indicators and histological examinations by reducing inflammation via inhibiting NLRP3 inflammasome and elevating Firmicutes and Lactobacillus levels. The network pharmacology study revealed that the FIP hypotensive mechanism might involve MMP9, JAK2, HMOX1, NOS2, NOS3, TEK, SERPINE1, CCL2, and VEGFA. The molecular docking study revealed that FIP bioactive compounds docked better with CAC1C_ HUMAN than verapamil. These findings demonstrated that Fip.Cr's hypotensive mechanism may include calcium channel blocker activity. Fip.Cr ameliorated ISO-induced myocardial infarction in rats by attenuating inflammation, which might be via inhibiting NLRP3 inflammasome and may prove beneficial for treating MI.

High-Density Lipoproteins at the Interface between the NLRP3 Inflammasome and Myocardial Infarction

Despite significant therapeutic advancements, morbidity and mortality following myocardial infarction (MI) remain unacceptably high. This clinical challenge is primarily attributed to two significant factors: delayed reperfusion and the myocardial injury resulting from coronary reperfusion. Following reperfusion, there is a rapid intracellular pH shift, disruption of ionic balance, heightened oxidative stress, increased activity of proteolytic enzymes, initiation of inflammatory responses, and activation of several cell death pathways, encompassing apoptosis, necroptosis, and pyroptosis. The inflammatory cell death or pyroptosis encompasses the activation of the intracellular multiprotein complex known as the NLRP3 inflammasome. High-density lipoproteins (HDL) are endogenous particles whose components can either promote or mitigate the activation of the NLRP3 inflammasome. In this comprehensive review, we explore the role of inflammasome activation in the context of MI and provide a detailed analysis of how HDL can modulate this process.

Role of cyclophilin A in aggravation of myocardial ischemia reperfusion injury via regulation of apoptosis mediated by thioredoxin-interacting protein

BACKGROUND

The progression and persistence of myocardial ischemia/reperfusion injury (MI/RI) are strongly linked to local inflammatory responses and oxidative stress. Cyclophilin A (CypA), a pro-inflammatory factor, is involved in various cardiovascular diseases. However, the role and mechanism of action of CypA in MI/RI are still not fully understood.

METHODS

We used the Gene Expression Omnibus (GEO) database for bioinformatic analysis. We collected blood samples from patients and controls for detecting the levels of serum CypA using enzyme-linked immunosorbent assay (ELISA) kits. We then developed a myocardial ischemia/reperfusion (I/R) injury model in wild-type (WT) mice and Ppia-/- mice. We utilized echocardiography, hemodynamic measurements, hematoxylin and eosin (H&E) staining, immunohistochemistry, enzyme-linked immunosorbent assay, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining to determine the role of CypA in myocardial I/R injury. Finally, we conducted an in vitrostudy, cell transfection, flow cytometry, RNA interference, and a co-immunoprecipitation assay to clarify the mechanism of CypA in aggravating cardiomyocyte apoptosis.

RESULTS

We found that CypA inhibited TXNIP degradation to enhance oxidative stress-induced cardiomyocyte apoptosis during MI/RI. By comparing and analyzing CypA expression in patients with coronary atherosclerotic heart disease and in healthy controls, we found that CypA was upregulated in patients with Coronary Atmospheric Heart Disease, and its expression was positively correlated with Gensini scores. In addition, CypA deficiency decreased cytokine expression, oxidative stress, and cardiomyocyte apoptosis in I/R-treated mice, eventually alleviating cardiac dysfunction. CypA knockdown also reduced H2O2-induced apoptosis in H9c2 cells. Mechanistically, we found that CypA inhibited K48-linked ubiquitination mediated by atrophin-interacting protein 4 (AIP4) and proteasomal degradation of TXNIP, a thioredoxin-binding protein that mediates oxidative stress and induces apoptosis.

CONCLUSION

These findings highlight the critical role CypA plays in myocardial injury caused by oxidative stress-induced apoptosis, indicating that CypA can be a viable biomarker and a therapeutic target candidate for MI/RI.

Cichoric acid improves isoproterenol-induced myocardial fibrosis via inhibition of HK1/NLRP3 inflammasome-mediated signaling pathways by reducing oxidative stress, inflammation, and apoptosis

Cichoric acid (CA), a natural phenolic compound found in many plants, has been reported to have antioxidant, anti-inflammatory, hypoglycemic, and other effects. The aim of this study was to determine the potential role and underlying mechanisms of CA in isoproterenol (ISO)-induced myocardial fibrosis (MF). The MF model was induced by subcutaneous ISO injection in mice. Blood and heart tissue were collected for examination. Hematoxylin and eosin staining and Masson's trichrome staining were used to evaluate the histopathological changes and collagen deposition. The production of reactive oxygen species markers was observed by fluorescence microscopy, the degree of cardiomyocyte microstructure injury was observed by transmission electron microscope, and oxidative stress factors were detected by kit method, and the effect of CA on inflammatory factors was detected by ELISA. The expression levels of collagen proteins and signaling pathways were further investigated by western blotting. The results showed that CA inhibited the expression of ISO-induced proinflammatory factors (TNF-α, IL-1β, and IL-18) and proteins (HK1, NLRP3, caspase-1, cleaved-caspase-1, and ASC), and regulated the expression of apoptotic factors (caspase-3, cleaved-caspase-3, Bax, and Bcl-2). The results indicated that CA may regulate the HK1/NLRP3 inflammasome pathway by inhibiting HK1 expression and play a protective role in MF.

β-hydroxybutyrate administered at reperfusion reduces infarct size and preserves cardiac function by improving mitochondrial function through autophagy in male mice

Ischemia/reperfusion (I/R) injury after revascularization contributes ∼50% of infarct size and causes heart failure, for which no established clinical treatment exists. β-hydroxybutyrate (β-OHB), which serves as both an energy source and a signaling molecule, has recently been reported to be cardioprotective when administered immediately before I/R and continuously after reperfusion. This study aims to determine whether administering β-OHB at the time of reperfusion with a single dose can alleviate I/R injury and, if so, to define the mechanisms involved. We found plasma β-OHB levels were elevated during ischemia in STEMI patients, albeit not to myocardial protection level, and decreased after revascularization. In mice, compared with normal saline, β-OHB administrated at reperfusion reduced infarct size (by 50%) and preserved cardiac function, as well as activated autophagy and preserved mtDNA levels in the border zone. Our treatment with one dose β-OHB reached a level achievable with fasting and strenuous physical activity. In neonatal rat ventricular myocytes (NRVMs) subjected to I/R, β-OHB at physiologic level reduced cell death, increased autophagy, preserved mitochondrial mass, function, and membrane potential, in addition to attenuating reactive oxygen species (ROS) levels. ATG7 knockdown/knockout abolished the protective effects of β-OHB observed both in vitro and in vivo. Mechanistically, β-OHB's cardioprotective effects were associated with inhibition of mTOR signaling. In conclusion, β-OHB, when administered at reperfusion, reduces infarct size and maintains mitochondrial homeostasis by increasing autophagic flux (potentially through mTOR inhibition). Since β-OHB has been safely tested in heart failure patients, it may be a viable therapeutic to reduce infarct size in STEMI patients.

TXNIP aggravates cardiac fibrosis and dysfunction after myocardial infarction in mice by enhancing the TGFB1/Smad3 pathway and promoting NLRP3 inflammasome activation

Myocardial infarction (MI) results in high mortality. The size of fibrotic scar tissue following MI is an independent predictor of MI outcomes. Thioredoxin-interacting protein (TXNIP) is involved in various fibrotic diseases. Its role in post-MI cardiac fibrosis, however, remains poorly understood. In the present study, we investigate the biological role of TXNIP in post-MI cardiac fibrosis and the underlying mechanism using mouse MI models of the wild-type (WT), Txnip-knockout ( Txnip-KO) type and Txnip-knock-in ( Txnip-KI) type. After MI, the animals present with significantly upregulated TXNIP levels, and their fibrotic areas are remarkably expanded with noticeably impaired cardiac function. These changes are further aggravated under Txnip-KI conditions but are ameliorated in Txnip-KO animals. MI also leads to increased protein levels of the fibrosis indices Collagen I, Collagen III, actin alpha 2 (ACTA2), and connective tissue growth factor (CTGF). The Txnip-KI group exhibits the highest levels of these proteins, while the lowest levels are observed in the Txnip-KO mice. Furthermore, Txnip-KI significantly upregulates the levels of transforming growth factor (TGF)B1, p-Smad3, NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3), Cleaved Caspase-1, and interleukin (IL)1B after MI, but these effects are markedly offset by Txnip-KO. In addition, after MI, the Smad7 level significantly decreases, particularly in the Txnip-KI mice. TXNIP may aggravate the progression of post-MI fibrosis and cardiac dysfunction by activating the NLRP3 inflammasome, followed by IL1B generation and then the enhancement of the TGFB1/Smad3 pathway. As such, TXNIP might serve as a novel potential therapeutic target for the treatment of post-MI cardiac fibrosis.

MicroRNA-30a-5p Promotes Chronic Heart Failure in Rats by Targeting Sirtuin-1 to Activate the Nuclear Factor-κB/NOD-Like Receptor 3 Signaling Pathway

OBJECTIVE

MicroRNA-30a-5p (miR-30a-5p) has been identified as a marker of heart failure; however, its functional mechanisms in chronic heart failure (CHF) remain unknown. We aim to investigate the role of miR-30a-5p targeting sirtuin-1 (SIRT1) in myocardial remodeling in CHF via the nuclear factor-κB/NOD-like receptor 3 (NF-κB/NLRP3) signaling pathway.

METHODS

CHF rat models were established using aortic coarctation. The expression of miR-30a-5p, SIRT1, and the NF-κB/NLRP3 signaling pathway-related factors in CHF rats was determined. The CHF rats were then respectively treated with altered miR-30a-5p or SIRT1 to explore their roles in cardiac function, myocardial function, inflammatory response, pathological changes, and cardiomyocyte apoptosis. The binding relation between miR-30a-5p and SIRT1 was confirmed.

RESULTS

MiR-30a-5p was upregulated whereas SIRT1 was downregulated in myocardial tissues of CHF rats. MiR-30a-5p inhibition or SIRT1 overexpression improved cardiac and myocardial function, and suppressed the inflammatory response, alleviated pathological changes and inhibited cardiomyocyte apoptosis in CHF rats. MiR-30a-5p targeted SIRT1 to regulate the NF-κB/NLRP3 signaling pathway. In CHF rats, downregulated miR-30a-5p and silenced SIRT1 could reverse the beneficial effects of downregulated miR-30a-5p.

CONCLUSION

Inhibited miR-30a-5p inhibits CHF progression via the SIRT1-mediated NF-κB/NLRP3 signaling pathway.

NR3C2 mediates oxidised low-density lipoprotein-induced human coronary endothelial cells dysfunction via modulation of NLRP3 inflammasome activation

Nuclear receptor subfamily 3 group C member 2 (NR3C2) has been revealed to affect the progression of multiple inflammatory diseases, while NR3C2's efficacy in coronary artery disease (CAD) remains largely unsolved. The study intended to elucidate the possible mechanisms of NR3C2 in oxidised low density lipoprotein (ox-LDL)-induced inflammation in human coronary endothelial cells (HCAECs) via regulating NACHT, LRR, and PYD domains-containing protein 3 (NLRP3). Patients who underwent CT angiography or coronary angiography for suspected CAD in our hospital were collected. The patients were divided into the CAD and the non-CAD (NCAD) groups. The expression of NR3C2 and NLRP3 in the peripheral blood of patients in both groups was examined by RT-qPCR. HCAECs were treated with ox-LDL to establish the model. The expression of NR3C2 and NLRP3 in ox-LDL-induced HCAECs was tested by RT-qPCR. The proliferation of HCAECs was measured using CCK-8 assay, the apoptosis of HCAECs was assessed by flow cytometry, and the levels of inflammation-related factors IL-1β and IL-18 in the cell supernatant were evaluated by ELISA. The molecular mechanisms of these factors in the proliferation and apoptosis of HCAECs and in the inflammatory response were further determined by knockdown and overexpression systems. The relationship between NR3C2 and NLRP3 was determined by ChIP and luciferase activity assays and bioinformatics analysis. NR3C2 and NLRP3 levels were elevated in the serum of CAD patients. The ox-LDL treatment elevated NR3C2 levels, evoked apoptosis and inflammation, and impeded cell viability in HCAECs, whereas downregulation of NR3C2 increased cell viability and reduced apoptosis and inflammatory response in ox-LDL-induced inflammation in HCAECs. NR3C2 levels were positively correlated with NLRP3, and NR3C2 elevated NLRP3 expression through transcription. Overexpression of NLRP3 counteracted the impacts of silencing NR3C2 on cell viability, cell apoptosis, and inflammatory response in ox-LDL-induced HCAECs. Our research stresses that NR3C2 transcription promotes NLRP3 to induce inflammatory responses in ox-LDL-induced HCAECs.

Efficacy and safety of inhibiting the NLRP3/IL-1β/IL-6 pathway in patients with ST-elevation myocardial infarction: A meta-analysis

BACKGROUND

The NLRP3/IL-1β/IL-6 pathway plays a key role in mediating inflammatory responses after ST-elevation myocardial infarction (STEMI). However, the clinical benefits of inhibiting this pathway in STEMI are uncertain. We aimed to evaluate the efficacy and safety of inhibiting the NLRP3/IL-1β/IL-6 pathway in STEMI patients.

METHODS

This study followed PRISMA guidelines. PubMed, Embase, CENTRAL and ClinicalTrials.gov databases were searched for randomized controlled trials (RCTs) of inhibiting the NLRP3/IL-1β/IL-6 pathway in STEMI patients within 7 days of symptom onset. The efficacy outcomes included all-cause death, cardiovascular death, recurrent MI, new-onset or worsening heart failure (HF) and stroke. The safety outcomes were serious infection, gastrointestinal adverse events and injection site reactions.

RESULTS

Of 316 screened records, nine trials with 1211 patients were included in the meta-analysis. Colchicine reduced the risk of recurrent MI (RR 0.28, 95% CI 0.10-0.74; I2  = 0.0%). Anakinra was associated with reduced risk of new-onset or worsening HF (RR 0.32, 95% CI 0.13-0.77; I2  = 0.0%) and decreased C-reactive protein levels (SMD -1.34, 95% CI -2.04 to -0.65; I2  = 0.0%). Colchicine and anakinra increased the risk of gastrointestinal adverse events (RR 4.43, 95% CI 2.75-7.13; I2  = 38.1%) and injection site reactions (RR 4.52, 95% CI 1.32-15.49; I2  = 0.8%), respectively. None of the three medications affected the risks of all-cause death, cardiovascular death, stroke and serious infection.

CONCLUSIONS

There is still no large-scale RCT evidence on the efficacy and safety of inhibiting the NLRP3/IL-1β/IL-6 pathway for the treatment of STEMI. Preliminary results from the available RCTs suggest colchicine and anakinra may respectively reduce the risks of recurrent MI and new-onset or worsening HF. The available RCTs in this meta-analysis lack power to determine any differences on mortality.