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

Oridonin attenuates hind limb ischemia-reperfusion injury by modulating Nrf2-mediated oxidative stress and NLRP3-mediated inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Oridonin (Ori), extracted from Isodon rubescens (Hemsl.) H.Hara, is a well-known traditional Chinese herbal medicinal product that possesses antioxidant and anti-inflammatory activities. Oxidative stress and inflammation are the main pathophysiological mechanisms in hindlimb IR injury. However, whether Ori has a protective effect on hind limb IR injury is unknown.

AIM OF THE STUDY

The present study was designed to determine the effect of Ori on hindlimb IR injury and its relationship with oxidative stress and inflammation.

MATERIALS AND METHODS

The hind limb IR injury model in mice was used to evaluate the protective effect and related mechanisms of Ori. Forty-eight C57BL/6 mice (n = 12 per group) were randomly divided into four groups: Sham group; IR group; IR + Ori (10 mg/kg) group and IR + Ori (20 mg/kg) group. Mice in the IR and IR + Ori groups were subjected to hindlimb IR injury, while mice in the Sham group were subjected to no hindlimb IR injury. HE staining, Masson's staining, TTC staining, DHE staining, TUNEL staining, western blotting analysis and quantitative real-time PCR were employed to explore the mechanisms by which Ori exerts a protective effect on a classical hindlimb IR model in mice.

RESULTS

We found that Ori pretreatment prevented muscle damage and decreased cell apoptosis levels compared with the vehicle control. Moreover, the SOD2, CAT, MDA and ROS levels in muscle showed that Ori could significantly reduce oxidative stress in hindlimb IR mice, while the IL-1β and TNF-α levels in muscle showed that Ori could significantly attenuate IR-induced inflammation. We also found that Ori could increase the expression of Nrf2 and its downstream protein HO-1 and inhibit the expression levels of NLRP3-related proteins (NLRP3, ASC and Caspase-1) in vivo.

CONCLUSIONS

Our study suggested that Ori has a protective effect on hindlimb IR injury, which may be related to Nrf2-mediated oxidative stress and NLRP3-mediated inflammasome activation.

Relaxin Inhibits the Cardiac Myofibroblast NLRP3 Inflammasome as Part of Its Anti-Fibrotic Actions via the Angiotensin Type 2 and ATP (P2X7) Receptors

Chronic NLRP3 inflammasome activation can promote fibrosis through its production of interleukin (IL)-1β and IL-18. Conversely, recombinant human relaxin (RLX) can inhibit the pro-fibrotic interactions between IL-1β, IL-18 and transforming growth factor (TGF)-β1. Here, the broader extent by which RLX targeted the myofibroblast NLRP3 inflammasome to mediate its anti-fibrotic effects was elucidated. Primary human cardiac fibroblasts (HCFs), stimulated with TGF-β1 (to promote myofibroblast (HCMF) differentiation), LPS (to prime the NLRP3 inflammasome) and ATP (to activate the NLRP3 inflammasome) (T+L+A) or benzoylbenzoyl-ATP (to activate the ATP receptor; P2X7R) (T+L+Bz), co-expressed relaxin family peptide receptor-1 (RXFP1), the angiotensin II type 2 receptor (AT2R) and P2X7R, and underwent increased protein expression of toll-like receptor (TLR)-4, NLRP3, caspase-1, IL-1β and IL-18. Whilst RLX co-administration to HCMFs significantly prevented the T+L+A- or T+L+Bz-stimulated increase in these end points, the inhibitory effects of RLX were annulled by the pharmacological antagonism of either RXFP1, AT2R, P2X7R, TLR-4, reactive oxygen species (ROS) or caspase-1. The RLX-induced amelioration of left ventricular inflammation, cardiomyocyte hypertrophy and fibrosis in isoproterenol (ISO)-injured mice, was also attenuated by P2X7R antagonism. Thus, the ability of RLX to ameliorate the myofibroblast NLRP3 inflammasome as part of its anti-fibrotic effects, appeared to involve RXFP1, AT2R, P2X7R and the inhibition of TLR-4, ROS and caspase-1.

Aging, sex and NLRP3 inflammasome in cardiac ischaemic disease

Experimentally, many strong cardioprotective treatments have been identified in different animal models of acute ischaemia/reperfusion injury (IRI) and coronary artery disease (CAD). However, the translation of these cardioprotective therapies for the benefit of the patients into the clinical scenario has been very disappointing. The reasons for this lack are certainly multiple. Indeed, many confounding factors we must deal in clinical reality, such as aging, sex and inflammatory processes are neglected in many experiments. Due to the pivotal role of aging, sex and inflammation in determining cardiac ischaemic disease, in this review, we take into account age as a modifier of tolerance to IRI in the two sexes, dissecting aging and myocardial reperfusion injury mechanisms and the sex differences in tolerance to IRI. Then we focus on the role of the gut microbiota and the NLRP3 inflammasome in myocardial IRI and on the possibility to consider NLRP3 inflammasome as a potential target in the treatment of CAD in relationship with age and sex. Finally, we consider the cardioprotective mechanisms and cardioprotective treatments during aging in the two sexes.

Rapid Inflammasome Activation Is Attenuated in Post-Myocardial Infarction Monocytes

Inflammasomes are crucial gatekeepers of the immune response, but their maladaptive activation associates with inflammatory pathologies. Besides canonical activation, monocytes can trigger non-transcriptional or rapid inflammasome activation that has not been well defined in the context of acute myocardial infarction (AMI). Rapid transcription-independent inflammasome activation induced by simultaneous TLR priming and triggering stimulus was measured by caspase-1 (CASP1) activity and interleukin release. Both classical and intermediate monocytes from healthy donors exhibited robust CASP1 activation, but only classical monocytes produced high mature interleukin-18 (IL18) release. We also recruited a limited number of coronary artery disease (CAD, n=31) and AMI (n=29) patients to evaluate their inflammasome function and expression profiles. Surprisingly, monocyte subpopulations isolated from blood collected during percutaneous coronary intervention (PCI) from AMI patients presented diminished CASP1 activity and abrogated IL18 release despite increased NLRP3 gene expression. This unexpected attenuated rapid inflammasome activation was accompanied by a significant increase of TNFAIP3 and IRAKM expression. Moreover, TNFAIP3 protein levels of circulating monocytes showed positive correlation with high sensitive troponin T (hsTnT), implying an association between TNFAIP3 upregulation and the severity of tissue injury. We suggest this monocyte attenuation to be a protective phenotype aftermath following a very early inflammatory wave in the ischemic area. Damage-associated molecular patterns (DAMPs) or other signals trigger a transitory negative feedback loop within newly recruited circulating monocytes as a mechanism to reduce post-injury tissue damage.

Modern Concepts in Cardiovascular Disease: Inflamm-Aging

The improvements in healthcare services and quality of life result in a longer life expectancy and a higher number of aged individuals, who are inevitably affected by age-associated cardiovascular (CV) diseases. This challenging demographic shift calls for a greater effort to unravel the molecular mechanisms underlying age-related CV diseases to identify new therapeutic targets to cope with the ongoing aging "pandemic". Essential for protection against external pathogens and intrinsic degenerative processes, the inflammatory response becomes dysregulated with aging, leading to a persistent state of low-grade inflammation known as inflamm-aging. Of interest, inflammation has been recently recognized as a key factor in the pathogenesis of CV diseases, suggesting inflamm-aging as a possible driver of age-related CV afflictions and a plausible therapeutic target in this context. This review discusses the molecular pathways underlying inflamm-aging and their involvement in CV disease. Moreover, the potential of several anti-inflammatory approaches in this context is also reviewed.

Emerging Roles of Inflammasomes in Cardiovascular Diseases

Cardiovascular diseases are known as the leading cause of morbidity and mortality worldwide. As an innate immune signaling complex, inflammasomes can be activated by various cardiovascular risk factors and regulate the activation of caspase-1 and the production and secretion of proinflammatory cytokines such as IL-1β and IL-18. Accumulating evidence supports that inflammasomes play a pivotal role in the progression of atherosclerosis, myocardial infarction, and heart failure. The best-known inflammasomes are NLRP1, NLRP3, NLRC4, and AIM2 inflammasomes, among which NLRP3 inflammasome is the most widely studied in the immune response and disease development. This review focuses on the activation and regulation mechanism of inflammasomes, the role of inflammasomes in cardiovascular diseases, and the research progress of targeting NLRP3 inflammasome and IL-1β for related disease intervention.

The Role of Purinergic Signaling in Heart Transplantation

Heart transplantation remains the optimal treatment option for patients with end-stage heart disease. Growing evidence demonstrates that purinergic signals mediated by purine nucleotides and nucleosides play vital roles in heart transplantation, especially in the era of ischemia-reperfusion injury (IRI) and allograft rejection. Purinergic signaling consists of extracellular nucleotides and nucleosides, ecto-enzymes, and cell surface receptors; it participates in the regulation of many physiological and pathological processes. During transplantation, excess adenosine triphosphate (ATP) levels are released from damaged cells, and driver detrimental inflammatory responses largely via purinergic P2 receptors. Ecto-nucleosidases sequentially dephosphorylate extracellular ATP to ADP, AMP, and finally adenosine. Adenosine exerts a cardioprotective effect by its anti-inflammatory, antiplatelet, and vasodilation properties. This review focused on the role of purinergic signaling in IRI and rejection after heart transplantation, as well as the clinical applications and prospects of purinergic signaling.

Properties and Functions of Fibroblasts and Myofibroblasts in Myocardial Infarction

The adult mammalian heart contains abundant interstitial and perivascular fibroblasts that expand following injury and play a reparative role but also contribute to maladaptive fibrotic remodeling. Following myocardial infarction, cardiac fibroblasts undergo dynamic phenotypic transitions, contributing to the regulation of inflammatory, reparative, and angiogenic responses. This review manuscript discusses the mechanisms of regulation, roles and fate of fibroblasts in the infarcted heart. During the inflammatory phase of infarct healing, the release of alarmins by necrotic cells promotes a pro-inflammatory and matrix-degrading fibroblast phenotype that may contribute to leukocyte recruitment. The clearance of dead cells and matrix debris from the infarct stimulates anti-inflammatory pathways and activates transforming growth factor (TGF)-β cascades, resulting in the conversion of fibroblasts to α-smooth muscle actin (α-SMA)-expressing myofibroblasts. Activated myofibroblasts secrete large amounts of matrix proteins and form a collagen-based scar that protects the infarcted ventricle from catastrophic complications, such as cardiac rupture. Moreover, infarct fibroblasts may also contribute to cardiac repair by stimulating angiogenesis. During scar maturation, fibroblasts disassemble α-SMA+ stress fibers and convert to specialized cells that may serve in scar maintenance. The prolonged activation of fibroblasts and myofibroblasts in the infarct border zone and in the remote remodeling myocardium may contribute to adverse remodeling and to the pathogenesis of heart failure. In addition to their phenotypic plasticity, fibroblasts exhibit remarkable heterogeneity. Subsets with distinct phenotypic profiles may be responsible for the wide range of functions of fibroblast populations in infarcted and remodeling hearts.

Mesenchymal stem cell-derived exosomal microRNA-182-5p alleviates myocardial ischemia/reperfusion injury by targeting GSDMD in mice

Recent evidence indicates that exosomes derived from mesenchymal stem cells (MSCs) confer protective effects against myocardial ischemia/reperfusion (I/R) injury. Exosomes are carriers of potentially protective endogenous molecules, including microRNAs (miRNAs/miRs). The current study set out to test the effects of transferring miR-182-5p from MSC-derived exosomes into myocardial cells on myocardial I/R injury. First, an I/R mouse model was developed by left anterior descending coronary artery occlusion, and myocardial cells were exposed to hypoxia/reoxygenation (H/R) for in vitro I/R model establishment. Loss- and gain-of-function experiments of miR-182-5p and GSDMD were conducted to explore the effects of miR-182-5p via MSC-derived exosomes on cell pyroptosis and viability. GSDMD was robustly expressed in I/R-injured myocardial tissues and H/R-exposed myocardial cells. GSDMD upregulation promoted H/R-induced myocardial cell pyroptosis and reduced viability, corresponding to increased lactate dehydrogenase release, reactive oxygen species production, and pyroptosis. A luciferase assay demonstrated GSDMD as a target of miR-182-5p. In addition, exosomal miR-182-5p was found to diminish GSDMD-dependent cell pyroptosis and inflammation induced by H/R. Furthermore, MSC-derived exosomes carrying miR-182-5p improved cardiac function and reduced myocardial infarction, accompanied with reduced inflammation and cell pyroptosis in vivo. Taken together, our findings suggest a cardioprotective effect of exosomal miR-182-5p against myocardial I/R injury, shedding light on an attractive therapeutic strategy.

How Pyroptosis Contributes to Inflammation and Fibroblast-Macrophage Cross-Talk in Rheumatoid Arthritis

About thirty years ago, a new form of pro-inflammatory lytic cell death was observed and termed pyroptosis. Only in 2015, gasdermins were defined as molecules that create pores at the plasma membrane and drive pyroptosis. Today, we know that gasdermin-mediated death is an important antimicrobial defence mechanism in bacteria, yeast and mammals as it destroys the intracellular niche for pathogen replication. However, excessive and uncontrolled cell death also contributes to immunopathology in several chronic inflammatory diseases, including arthritis. In this review, we discuss recent findings where pyroptosis contributes to tissue damage and inflammation with a main focus on injury-induced and autoimmune arthritis. We also review novel functions and regulatory mechanisms of the pyroptotic executors gasdermins. Finally, we discuss possible models of how pyroptosis may contribute to the cross-talk between fibroblast and macrophages, and also how this cross-talk may regulate inflammation by modulating inflammasome activation and pyroptosis induction.

Acute exposure to phthalates during recovery from a myocardial infarction induces greater inflammasome activation in male C57bl/6N mice

Plasticizers escape from medical devices used in cardiac surgery into patient blood and tissues. Increased di-ethylhexyl phthalate (DEHP) exposure is correlated with chronic inflammation in vivo and increased cytokine release in exposed monocytes in vitro. To determine if acute phthalate exposure enhanced inflammation in a model of cardiac damage, we measured immune cell infiltration, inflammasome expression and cardiac function in male C57bl/6 N mice exposed to phthalates during recovery from a surgically-induced myocardial infarction (MI). Phthalate exposed mice had greater neutrophil and pro-inflammatory macrophage infiltration, greater cardiac dilation and reduced cardiac function when compared with control mice. The greater expression of NLRP3 and NLRP6, but not AIM2 or P2xR7, in the infarcts of phthalate exposed versus control mice suggests a selectivity in pattern recognition receptor activation. Treatment of human THP-1 macrophages with phthalates revealed increased NLRP3 and NLRP6 expression and induction of a pro-inflammatory macrophage population. Pre-treatment with the PPARγ antagonist GW9662 reduced these increases. An increase in expression of IL-1R, MyD88 and IRAK4 in infarcts of phthalate exposed mice and THP-1 cells argues for greater priming downstream of IL-1R signaling and increased susceptibility for inflammasome activation. Importantly, these effects were moderated in vivo when phthalate exposure was reduced by 90% and when the NLRP3 antagonist MCC950 was co-administered. Our study suggests that reductions in phthalate exposure, which might be realized using plasticizers with a reduced ability to leach out from plastic, or short-term treatment with an anti-inflammasome may improve healing post-surgery.

GSK-3β-mediated activation of NLRP3 inflammasome leads to pyroptosis and apoptosis of rat cardiomyocytes and fibroblasts

We previously demonstrated that GSK-3β mediates NLRP3 inflammasome activation and IL-1β production in cardiac fibroblasts (CFs) after myocardial infarction (MI). In this study, we show how GSK-3β-mediated activation of the NLRP3 inflammasome/caspase-1/IL-1β pathway leads to apoptosis and pyroptosis of cardiomyocytes (CMs) and CFs. Administration of lipopolysaccharide (LPS)/ATP to primary newborn rat cardiac fibroblasts (RCFs) led to increase in proteins of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, IL-1β, and IL-18. Additionally, the expression of caspase-3 and N-terminal fragments of gasdermin D (N-GSDMD) and the Bax/Bcl-2 ratio increased. Administration of the GSK-3β inhibitor SB216763 reduced the levels of apoptosis- and pyroptosis-related proteins regulated by NLRP3 inflammasome activation in RCFs. Next, we transferred the culture supernatant of LPS/ATP-treated RCFs to in vitro primary newborn rat cardiomyocytes (RCMs). The results showed that SB216763 attenuate the upregulation of the ratios of Bax/Bcl-2 and the expression of caspase-3 and N-GSDMD in RCMs. Direct stimulation of RCMs and H9c2 cells with recombinant rat IL-1β increased the p-GSK-3β/GSK-3β and Bax/Bcl-2 ratios and the expression of caspase-3 and N-GSDMD, while both SB216763 and TLR1 (an IL-1β receptor inhibitor) markedly reduced these effects, as assessed using propidium iodide positive staining and the lactate dehydrogenase release assay. The caspase-11 inhibitor wedelolactone decreased the expression level of N-GSDMD but did not alter the p-GSK-3β/GSK-3β ratio. Lastly, we established a Sprague-Dawley rat MI model to confirm that SB216763 diminished the increase in caspase-3 and N-GSDMD expression and the Bax/Bcl-2 ratio in the ischemic area. These data demonstrate that GSK-3β regulates apoptosis and pyroptosis of RCMs and RCFs due to NLRP3 inflammasome activation in RCFs.

Circulating Mitochondrial DNA and Inter-Organelle Contact Sites in Aging and Associated Conditions

Mitochondria are primarily involved in cell bioenergetics, regulation of redox homeostasis, and cell death/survival signaling. An immunostimulatory property of mitochondria has also been recognized which is deployed through the extracellular release of entire or portioned organelle and/or mitochondrial DNA (mtDNA) unloading. Dynamic homo- and heterotypic interactions involving mitochondria have been described. Each type of connection has functional implications that eventually optimize mitochondrial activity according to the bioenergetic demands of a specific cell/tissue. Inter-organelle communications may also serve as molecular platforms for the extracellular release of mitochondrial components and subsequent ignition of systemic inflammation. Age-related chronic inflammation (inflamm-aging) has been associated with mitochondrial dysfunction and increased extracellular release of mitochondrial components—in particular, cell-free mtDNA. The close relationship between mitochondrial dysfunction and cellular senescence further supports the central role of mitochondria in the aging process and its related conditions. Here, we provide an overview of (1) the mitochondrial genetic system and the potential routes for generating and releasing mtDNA intermediates; (2) the pro-inflammatory pathways elicited by circulating mtDNA; (3) the participation of inter-organelle contacts to mtDNA homeostasis; and (4) the link of these processes with senescence and age-associated conditions.

The Interplay of Hypoxia Signaling on Mitochondrial Dysfunction and Inflammation in Cardiovascular Diseases and Cancer: From Molecular Mechanisms to Therapeutic Approaches

Simple Summary

The regulation of hypoxia has recently emerged as having a central impact in mitochondrial function and dysfunction in various diseases, including the major disorders threatening worldwide: cardiovascular diseases and cancer. Despite the studies in this matter, its effective role in protection and disease progression even though its direct molecular mechanism in both disorders is still to be elucidated. This review aims to cover the current knowledge about the effect of hypoxia on mitochondrial function and dysfunction, and inflammation, in cardiovascular diseases and cancer, and reports further therapeutic strategies based on the modulation of hypoxic pathways.

Abstract

Cardiovascular diseases (CVDs) and cancer continue to be the primary cause of mortality worldwide and their pathomechanisms are a complex and multifactorial process. Insufficient oxygen availability (hypoxia) plays critical roles in the pathogenesis of both CVDs and cancer diseases, and hypoxia-inducible factor 1 (HIF-1), the main sensor of hypoxia, acts as a central regulator of multiple target genes in the human body. Accumulating evidence demonstrates that mitochondria are the major target of hypoxic injury, the most common source of reactive oxygen species during hypoxia and key elements for inflammation regulation during the development of both CVDs and cancer. Taken together, observations propose that hypoxia, mitochondrial abnormality, oxidative stress, inflammation in CVDs, and cancer are closely linked. Based upon these facts, this review aims to deeply discuss these intimate relationships and to summarize current significant findings corroborating the molecular mechanisms and potential therapies involved in hypoxia and mitochondrial dysfunction in CVDs and cancer.

Curcumin Ameliorates Cardiac Fibrosis by Regulating Macrophage-Fibroblast Crosstalk via IL18-P-SMAD2/3 Signaling Pathway Inhibition

Ethnopharmacological relevance: Curcumin is a bright yellow chemical produced by plants of the Curcuma longa species. Chemically, curcumin is a diarylheptanoid, belonging to the group of curcuminoids. The therapeutic potential of curcumin has been widely investigated, including its utilization in various of cardiovascular diseases. However, its effect in cardiac remodeling post myocardial infarction and underlying mechanism remains to be uncover.

Aim: To evaluate the therapeutic effect and underlying mechanism of curcumin on cardiac fibrosis after myocardial infarction via macrophage-fibroblast crosstalk.

Methods: Male C57BL/6 (C57) mice were subjected to left anterior descending coronary artery ligation to establish myocardial infarction and intragastrically fed vehicle or curcumin (50 mg/kg or 100 mg/kg) for 4 weeks. In parallel, neonatal rat cardiac fibroblasts were isolated and co-cultured with liposaccharide (LPS− or LPS+) curcumin-treated macrophages, followed by TGF-β stimulation for 24 h. Cardiac function was determined by 2-dimensional echocardiography, and cardiac fibrosis was measured by picrosirius red staining. Apoptosis of macrophages was investigated by flow cytometry; all pro-fibrotic protein expression (EDA-Fibronectin, Periostin, Vimentin, and α-SMA) as well as TGF-βR1 downstream signaling activation reflected by phosphorylated SMAD2/3 (p-SMAD2 and p-SMAD3) were demonstrated by western blotting.

Results: Curcumin significantly ameliorated the inflammation process subsequent to myocardial infarction, reflected by decreased expression of CD68+ and CD3+ cells, accompanied by dramatically improved cardiac function compared with the placebo group. In addition, cardiac fibrosis is inhibited by curcumin administration. Interestingly, no significant reduction in fibrotic gene expression was observed when isolated cardiac fibroblasts were directly treated with curcumin in vitro; however, pro-fibrotic protein expression was significantly attenuated in CF, which was co-cultured with LPS-stimulated macrophages under curcumin treatment compared with the placebo group. Mechanistically, we discovered that curcumin significantly downregulated pro-inflammatory cytokines in macrophages, which in turn inhibited IL18 expression in co-cultured cardiac fibroblasts using bulk RNA sequencing, and the TGF-β1-p-SMAD2/3 signaling network was also discovered as the eventual target downstream of IL18 in curcumin-mediated anti-fibrosis signaling.

Conclusion: Curcumin improves cardiac function and reduces cardiac fibrosis after myocardial infarction. This effect is mediated by the inhibition of macrophage-fibroblast crosstalk in the acute phase post-MI and retrained activation of IL18-TGFβ1-p-SMAD2/3 signaling in cardiac fibroblasts.

NLRP3 inflammasome as a novel therapeutic target for heart failure

Heart failure (HF) is a leading cause of mortality worldwide. The pathogenesis of HF is complex and has not yet been fully elucidated, which has slowed drug development and long-term treatments. Inflammasome-mediated responses occur during the progression of HF. It has been reported that energy metabolism and metabolites of intestinal flora are also involved in the process of HF, and they interact with each other to promote the progression of HF. NLR family pyrin domain containing 3 (NLRP3) inflammasome may be a key target in the relationship between inflammation-mediated energy metabolism and metabolites of intestinal flora. Elucidating the relationship among the above three factors may help to identify new molecular targets for the prevention and treatment of HF and ultimately affect the course of HF. In this study, we systematically summarize evidence regarding the relationship among NLRP3 inflammasome, energy metabolism, intestinal microflora metabolites, and inflammation, as well as highlight advantages of NLRP3 inflammasome in treating HF.

Targeting the Inflammasome in Cardiovascular Disease

The pathogenesis of cardiovascular disease (CVD) is complex and multifactorial, and inflammation plays a central role. Inflammasomes are multimeric protein complexes that are activated in a 2-step manner in response to infection or tissue damage. Upon activation the proinflammatory cytokines, interleukins-1β and -18 are released. In the last decade, the evidence that inflammasome activation plays an important role in CVD development became stronger. We discuss the role of different inflammasomes in the pathogenesis of CVD, focusing on atherosclerosis and heart failure. This review also provides an overview of existing experimental studies and clinical trials on inflammasome inhibition as a therapeutic target in these disorders.

ZNF561-AS1 Regulates Cell Proliferation and Apoptosis in Myocardial Infarction Through miR-223-3p/NLRP3 Axis

Long non-coding RNAs (lncRNAs) have been widely recognized as important regulators in myocardial infarction (MI) and other heart diseases. Our study aimed to investigate the mechanism and biological function of an unknown lncRNA zinc finger protein 561 antisense RNA 1 (ZNF561-AS1) in MI. After confirming the MI model was successful, we applied reverse transcription quantitative polymerase chain reaction and Western blot (WB) and found that the expression of NLR family pyrin domain containing 3 (NLRP3), interleukin (IL)-1β, and IL-18 was substantially increased in infarct and border zones of MI mice heart at 24 h and 72 h compared with that in sham-operated models. Moreover, we found that NLRP3 expression was promoted in hypoxia human cardiomyocytes (HCMs). Through cell function assays including CCK-8, 5-Ethynyl-2’-deoxyuridine (EdU), flow cytometry, and TdT-mediated dUTP Nick-End Labeling (TUNEL), supported by WB analysis, we verified that silencing of NLRP3 facilitated proliferation but impeded apoptosis of hypoxia-induced myocardial cell. Moreover, Ago2-RIP and RNA pull-down assays displayed that NLRP3 could combine with miR-223-3p. Luciferase reporter assays further confirmed that NLRP3 was directly targeted by miR-223-3p. Simultaneously, we found that miR-223-3p was the downstream gene of ZNF561-AS1. In addition, we conducted a series of rescue experiments to affirm that ZNF561-AS1 regulated cell proliferation and apoptosis in MI through miR-223-3p/NLRP3 axis.

Protective Effects of the Soluble Receptor for Advanced Glycation End-Products on Pyroptosis during Myocardial Ischemia-Reperfusion

Ischemia-reperfusion injury (IRI) is an inevitable process when reperfusion therapy undergoes in acute myocardial infarction patients, which will lead to cardiac cell death. Many factors have been found to protect the myocardium, one of which was the soluble receptor for advanced glycation end-products (sRAGE) that protected the myocardium from apoptosis and autophagy. However, pyroptosis is also an important form of cell death that occurs during ischemia-reperfusion (I/R), whose critical molecule, NLR family pyrin domain containing 3 (NLRP3), was ever reported to be inhibited by sRAGE; therefore, it is hypothesized that sRAGE may decrease the cardiac pyroptosis induced by I/R. The results showed that sRAGE protected cardiomyocytes from I/R-induced pyroptosis by decreasing the expression level of NLRP3, gasdermin D (GSDMD), interleukin-1β (IL-1β), and interleukin-18 (IL-18). Meanwhile, the results from primary cultured cardiomyocytes showed that the NF-κB pathway mediated the effects of sRAGE on pyroptosis. Therefore, it is concluded that sRAGE protects the heart from pyroptosis through inhibiting the NF-κB pathway during myocardial ischemia-reperfusion.

Targeting the NLRP3 inflammasome in cardiovascular diseases

The NACHT, leucine-rich repeat (LRR), and pyrin domain (PYD)-containing protein 3 (NLRP3) inflammasome is an intracellular sensing protein complex that plays a major role in innate immunity. Following tissue injury, activation of the NLRP3 inflammasome results in cytokine production, primarily interleukin(IL)-1β and IL-18, and, eventually, inflammatory cell death - pyroptosis. While a balanced inflammatory response favors damage resolution and tissue healing, excessive NLRP3 activation causes detrimental effects. A key involvement of the NLRP3 inflammasome has been reported across a wide range of cardiovascular diseases (CVDs). Several pharmacological agents selectively targeting the NLRP3 inflammasome system have been developed and tested in animals and early phase human studies with overall promising results. While the NLRP3 inhibitors are in clinical development, multiple randomized trials have demonstrated the safety and efficacy of IL-1 blockade in atherothrombosis, heart failure and recurrent pericarditis. Furthermore, the non-selective NLRP3 inhibitor colchicine has been recently shown to significantly reduce cardiovascular events in patients with chronic coronary disease. In this review, we will outline the mechanisms driving NLRP3 assembly and activation, and discuss the pathogenetic role of the NLRP3 inflammasome in CVDs, providing an overview of the current and future therapeutic approaches targeting the NLRP3 inflammasome.

Huoxue Qianyang Qutan recipe attenuates cardiac fibrosis by inhibiting the NLRP3 inflammasome signalling pathway in obese hypertensive rats

CONTEXT

HuoXue QianYang QuTan Recipe (HQQR) is used to manage hypertension and cardiac remodelling, but the mechanism is elusive.

OBJECTIVE

To determine the mechanism of HQQR on obesity hypertension (OBH)-related myocardial fibrosis.

MATERIALS AND METHODS

OBH models were prepared using spontaneously hypertensive rats (SHRs) and divided (n = 6) into saline, low-dose (19.35 g/kg/d) HQQR, high-dose (38.7 g/kg/d) HQQR, and valsartan (30 mg/kg/d) groups for 10 weeks. Systolic blood pressure (SBP), and Lee's index were measured. Heart tissues were examined by histology. HQQR's effects were examined on cardiac fibroblasts (CFs) stimulated with angiotensin II and treated with HQQR, a caspase-1 inhibitor, siNLRP3, and oeNLRP3.

RESULTS

HQQR(H) reduced SBP (201.67 ± 21.00 vs. 169.00 ± 10.00), Lee's index (321.50 ± 3.87 vs. 314.58 ± 3.88), and left ventricle mass index (3.26 ± 0.27 vs. 2.71 ± 0.12) in vivo. HQQR reduced percentage of fibrosis area (18.99 ± 3.90 vs. 13.37 ± 3.39), IL-1β (10.07 ± 1.16 vs. 5.35 ± 1.29), and inhibited activation of NLRP3/caspase-1/IL-1β pathway. HQQR also inhibiting the proliferation (1.09 ± 0.02 vs. 0.84 ± 0.01), fibroblast to myofibroblast transition (14.74 ± 3.39 vs. 3.97 ± 0.53), and collagen deposition (Col I; 0.50 ± 0.02 vs. 0.27 ± 0.05 and Col III; 0.48 ± 0.21 vs. 0.26 ± 0.11) with different concentrations selected based on IC₅₀ in vitro (all ps < 0.05). NLRP3 interference further confirmed HQQR inhibiting NLRP3 inflammasome signalling.

CONCLUSION

HQQR blunted cardiac fibrosis development in OBH and suppressed CFs proliferation by directly interfering with the NLRP3/caspase-1/IL-1β pathway.

CircRNA circ-NNT mediates myocardial ischemia/reperfusion injury through activating pyroptosis by sponging miR-33a-5p and regulating USP46 expression

Pyroptosis has been implicated in the pathophysiology of myocardial infarction (MI) in rodents, but its contribution to reperfusion injury in MI patients is unclear. Here, we evaluated pyroptosis in MI patients in vitro and in vivo models of myocardial ischemia/reperfusion (I/R) injury. We also investigated the molecular mechanisms that regulate pyroptosis and myocardial I/R injury in these in vitro and in vivo models. The study showed that MI patients exhibited elevated serum concentrations of the pyroptosis-related pro-inflammatory cytokines IL-1β and IL-18. Increased levels of IL-1β and IL-18 as well as the pyroptosis-related inflammatory caspases (caspase-1 and 11) were detected in cultured cardiomyocytes after anoxia/reoxygenation (A/R) and in cardiac tissues after I/R. Circ-NNT and USP46 were upregulated while miR-33a-5p was downregulated in MI patients, as well as in cultured cardiomyocytes after A/R and cardiac tissues after I/R. Circ-NNT or USP46 knockdown or miR-33a-5p overexpression inhibited the expression of pro-caspase-1, cleaved caspase-1, pro-caspase-11, cleaved caspase-11, IL-1β, and IL-18 in A/R cardiomyocytes and attenuated myocardial infarction in I/R mice. The results from luciferase reporter assays and gene overexpression/knockdown studies indicated that miR-33a-5p directly targets USP46, and circ-NNT regulates USP46 by acting as a miR-33a-5p sponge. Direct association between circ-NNT and miR-33a-5p in cardiomyocytes was confirmed by pull-down assays. In summary, pyroptosis is activated during myocardial I/R and contributes to reperfusion injury. Circ-NNT promotes pyroptosis and myocardial I/R injury by acting as a miR-33a-5p sponge to regulate USP46. This circ-NNT→miR-33a-5p→USP46 signaling axis may serve as a potential target for the development of cardio-protective agents to improve the clinical outcome of reperfusion therapy.

IL-1β in atherosclerotic vascular calcification: From bench to bedside

Atherosclerotic vascular calcification contributes to increased risk of death in patients with cardiovascular diseases. Assessing the type and severity of inflammation is crucial in the treatment of numerous cardiovascular conditions. IL-1β, a potent proinflammatory cytokine, plays diverse roles in the pathogenesis of atherosclerotic vascular calcification. Several large-scale, population cohort trials have shown that the incidence of cardiovascular events is clinically reduced by the administration of anti-IL-1β therapy. Anti-IL-1β therapy might reduce the incidence of cardiovascular events by affecting atherosclerotic vascular calcification, but the mechanism underlying this effect remains unclear. In this review, we summarize current knowledge on the role of IL-1β in atherosclerotic vascular calcification, and describe the latest results reported in clinical trials evaluating anti-IL-1β therapies for the treatment of cardiovascular diseases. This review will aid in improving current understanding of the pathophysiological roles of IL-1β and mechanisms underlying its activity.

Retinol-Binding Protein 4 Promotes Cardiac Injury After Myocardial Infarction Via Inducing Cardiomyocyte Pyroptosis Through an Interaction With NLRP3

Background

Acute myocardial infarction (AMI) is one of the leading causes of cardiovascular morbidity and mortality worldwide. Pyroptosis is a form of inflammatory cell death that plays a major role in the development and progression of cardiac injury in AMI. However, the underlying mechanisms for the activation of pyroptosis during AMI are not fully elucidated.

Methods and Results

Here we show that RBP4 (retinol‐binding protein 4), a previous identified proinflammatory adipokine, was increased both in the myocardium of left anterior descending artery ligation‐induced AMI mouse model and in ischemia‐hypoxia‒induced cardiomyocyte injury model. The upregulated RBP4 may contribute to the activation of cardiomyocyte pyroptosis in AMI because overexpression of RBP4 activated NLRP3 (nucleotide‐binding oligomerization domain‐like receptor family pyrin domain‐containing 3) inflammasome, promoted the precursor cleavage of Caspase‐1, and subsequently induced GSDMD (gasdermin‐D)‐dependent pyroptosis. In contrast, knockdown of RBP4 alleviated ischemia‐hypoxia‒induced activation of NLRP3 inflammasome signaling and pyroptosis in cardiomyocytes. Mechanistically, coimmunoprecipitation assay showed that RBP4 interacted directly with NLRP3 in cardiomyocyte, while genetic knockdown or pharmacological inhibition of NLRP3 attenuated RBP4‐induced pyroptosis in cardiomyocytes. Finally, knockdown of RBP4 in heart decreased infarct size and protected against AMI‐induced pyroptosis and cardiac dysfunction in mice.

Conclusions

Taken together, these findings reveal RBP4 as a novel modulator promoting cardiomyocyte pyroptosis via interaction with NLRP3 in AMI. Therefore, targeting cardiac RBP4 might represent a viable strategy for the prevention of cardiac injury in patients with AMI.

Iguratimod Alleviates Myocardial Ischemia/Reperfusion Injury Through Inhibiting Inflammatory Response Induced by Cardiac Fibroblast Pyroptosis via COX2/NLRP3 Signaling Pathway

Background: NLRP3 inflammasome contributes a lot to sterile inflammatory response and pyroptosis in ischemia/reperfusion (I/R) injury. Cardiac fibroblasts (CFs) are regarded as semi-professional inflammatory cells and they exert an immunomodulatory role in heart. Iguratimod provides a protective role in several human diseases through exerting a powerful anti-inflammatory effect. However, it is still unclear whether iguratimod could alleviate myocardial I/R injury and whether inflammation triggered by NLRP3-related pyroptosis of CFs is involved in this process. Methods: Transcriptomics analysis for GSE160516 dataset was conducted to explore the biological function of differentially expressed genes during myocardial I/R. In vivo, mice underwent ligation of left anterior descending coronary artery for 30 min followed by 24 h reperfusion. In vitro, primary CFs were subjected to hypoxia for 1 h followed by reoxygenation for 3 h (H/R). Iguratimod was used prior to I/R or H/R. Myocardial infarct area, serum level of cardiac troponin I (cTnI), pathology of myocardial tissue, cell viability, lactate dehydrogenase (LDH) release, and the expression levels of mRNA and protein for pyroptosis-related molecules were measured. Immunofluorescence was applied to determine the cellular localization of NLRP3 protein in cardiac tissue. Results: During myocardial I/R, inflammatory response was found to be the most significantly enriched biological process, and nucleotide-binding oligomerization domain (NOD)-like receptor signaling was a crucial pathway in mediating cardiac inflammation. In our experiments, pretreatment with iguratimod significantly ameliorated I/R-induced myocardial injury and H/R-induced pyroptosis of CFs, as evidenced by reduced myocardial infarct area, serum cTnI level, and LDH release in supernatants, as well as improved pathology of cardiac tissue and cell viability. Immunofluorescence analysis showed that NLRP3 was mainly localized in CFs. Moreover, iguratimod inhibited the expression of pro-inflammatory cytokines and pyroptosis-related molecules, including NLRP3, cleaved caspase-1, and GSDMD-N. Conclusion: Our results suggested that inflammatory response mediated by NOD-like receptor signaling is of vital importance in myocardial I/R injury. Iguratimod protected cardiomyocytes through reducing the cascade of inflammation in heart by inhibiting cardiac fibroblast pyroptosis via the COX2/NLRP3 signaling pathway.

Regulation of the Immune Microenvironment by an NLRP3 Inhibitor Contributes to Attenuation of Acute Right Ventricular Failure in Rats with Pulmonary Arterial Hypertension

Background

Right heart failure is the terminal stage of PAH. When PAH patients suffer from pulmonary infection or puerperal infection heart failure often rapidly develops. Low dose of lipopolysaccharide induces rapid right ventricular failure in rats with pulmonary arterial hypertension.

Purpose

The objective of this study was to investigate whether the NLRP3 inflammasome mediates disturbance of the ventricular immune microenvironment of PAH rats and promotes right ventricular failure.

Methods

Intraperitoneal injection of monocrotaline was used to induce PAH in rats. Right ventricular function was measured via echocardiography before and after the rats were treated with lipopolysaccharide and MCC950. The degree of immune microenvironment disturbance in right ventricular tissue was measured with a rat chemokine and cytokine antibody array, Western blot, flow cytometry and quantitative real-time PCR analysis.

Results

After the rats were injected with LPS, they exhibited right ventricular dysfunction and a significant increase in right ventricular tissue inflammation with elevated M1 macrophage proportion. Administration of MCC950 suppressed inflammation and improved right ventricular function. The number of M1 macrophages was decreased after MCC950 treatment. NLRP3 inflammasome inhibition ameliorated LPS-induced changes in the immune microenvironment in the right heart and right ventricular dysfunction in rats with PAH.

Conclusion

Selective inhibition of NLRP3 pathway interfered the interaction between hypertrophic cardiomyocytes and macrophages in the initial stage of inflammation and maintained the immune microenvironment balance, eventually contributing to attenuation of LPS-induced acute heart failure in PAH rats.

An Epigenetic Insight into NLRP3 Inflammasome Activation in Inflammation-Related Processes

Aberrant NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome activation in innate immune cells, triggered by diverse cellular danger signals, leads to the production of inflammatory cytokines (IL-1β and IL-18) and cell death by pyroptosis. These processes are involved in the pathogenesis of a wide range of diseases such as autoimmune, neurodegenerative, renal, metabolic, vascular diseases and cancer, and during physiological processes such as aging. Epigenetic dynamics mediated by changes in DNA methylation patterns, chromatin assembly and non-coding RNA expression are key regulators of the expression of inflammasome components and its further activation. Here, we review the role of the epigenome in the expression, assembly, and activation of the NLRP3 inflammasome, providing a critical overview of its involvement in the disease and discussing how targeting these mechanisms by epigenetic treatments could be a useful strategy for controlling NLRP3-related inflammatory diseases.

Beclin1 controls caspase-4 inflammsome activation and pyroptosis in mouse myocardial reperfusion-induced microvascular injury

BACKGROUND

Myocardial reperfusion injury is often accompanied by cell death and inflammatory reactions. Recently, pyroptosis is gradually recognized as pivotal role in cardiovascular disease. However, little is known about the regulatory role of beclin1 in the control of caspase-4 activation and pyroptosis. The present study confirmed whether beclin1 regulates caspase-4 mediated pyroptosis and thereby protects Human Cardiac microvascular endothelial cells (HCMECs) against injury.

METHODS

TTC and Evan's blue dye, western blot, immunofluorescence and immunohistochemistry staining were performed in wild mice and transgenic mice with overexpression of beclin 1(BECN1-Tg). CMECs were transfected with a beclin1 lentivirus. The cell cytotoxicity was analyzed by LDH-Cytotoxicity Assay Kit. The protein levels of autophagy protein (Beclin1, p62 and LC3II/LC3I) and caspase-4/GSDMD pathway were determined by western blot. Autophagic vacuoles in cells were monitored with RFP-GFP-LC3 using fluorescence microscope.

RESULTS

I/R caused caspase-4 activity and gasdermin D expression increase in vivo and in vitro. Overexpression of beclin1 in heart tissue and CMECs suppressed the caspase-4 activity and decreased the levels of gasdermin D; meanwhile beclin1 overexpression also reduced IL-1β levels, promoted autophagy (p62 expression was inhibited while LC3II expression was increased) in the heart and CMECs. Interestingly, beclin1 overexpression increased animal survival and attenuated myocardial infarct size (45 ± 6.13 vs 22 ± 4.37), no-reflow area (39 ± 5.22 vs 16 ± 2.54) post-myocardial ischemia reperfusion.

CONCLUSIONS

Induction of beclin-1 signaling can be a potential therapeutic target in myocardial reperfusion-induced microvascular injury. Video Abstract.

NETs promote pathogenic cardiac fibrosis and participate in ventricular aneurysm formation after ischemia injury through the facilitation of perivascular fibrosis

Fibrosis has been widely investigated in acute phase of myocardial infarction (MI). However, the mechanism of sustained fibrosis after MI hasn't been elucidated, which eventually gives rise to ventricular aneurysm (VA) formation chronic while lethal. Neutrophil as vital cell facilitating the fibrotic repair after acute MI may not project its effect to chronic phase unless neutrophil extracellular traps (NETs) were secreted and accumulating. The aim of this study was to investigate whether NETs contribute to the sustained fibrosis and VA formation after MI. We identified NETs in ventricular aneurysm of patients. Accordingly, NETs increased in peripheral blood of VA patients. Moreover, in rat VA NETs were also identified. Stimulated by NETs, the migration of fibroblast was enhanced and the differentiation of cardiac myofibroblast was initiated. Smad, MAPK and RhoA signaling pathways were activated by NETs incubation. And additional deposition with DNase I to disrupt NETs and abrogated NETs induced fibrosis both in vivo and vitro. These results collectively demonstrate a novel profibrotic role for NETs in chronic cardiac fibrosis and VA formation.

Molecular biology of autoinflammatory diseases

The long battle between humans and various physical, chemical, and biological insults that cause cell injury (e.g., products of tissue damage, metabolites, and/or infections) have led to the evolution of various adaptive responses. These responses are triggered by recognition of damage-associated molecular patterns (DAMPs) and/or pathogen-associated molecular patterns (PAMPs), usually by cells of the innate immune system. DAMPs and PAMPs are recognized by pattern recognition receptors (PRRs) expressed by innate immune cells; this recognition triggers inflammation. Autoinflammatory diseases are strongly associated with dysregulation of PRR interactomes, which include inflammasomes, NF-κB-activating signalosomes, type I interferon-inducing signalosomes, and immuno-proteasome; disruptions of regulation of these interactomes leads to inflammasomopathies, relopathies, interferonopathies, and proteasome-associated autoinflammatory syndromes, respectively. In this review, we discuss the currently accepted molecular mechanisms underlying several autoinflammatory diseases.

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.

Minimizing Ischemia Reperfusion Injury in Xenotransplantation

The recent dramatic advances in preventing "initial xenograft dysfunction" in pig-to-non-human primate heart transplantation achieved by minimizing ischemia suggests that ischemia reperfusion injury (IRI) plays an important role in cardiac xenotransplantation. Here we review the molecular, cellular, and immune mechanisms that characterize IRI and associated "primary graft dysfunction" in allotransplantation and consider how they correspond with "xeno-associated" injury mechanisms. Based on this analysis, we describe potential genetic modifications as well as novel technical strategies that may minimize IRI for heart and other organ xenografts and which could facilitate safe and effective clinical xenotransplantation.

Interleukin-18 accelerates cardiac inflammation and dysfunction during ischemia/reperfusion injury by transcriptional activation of CXCL16

Myocardial ischemia/reperfusion(I/R) injury elicits an inflammatory response that drives tissue damage and cardiac remodeling. The trafficking and recruitment of inflammatory cells are controlled by C-X-C motif chemokine ligands and their receptors. CXCL16, a hallmark of acute coronary syndromes, is responsible for the recruitment of macrophages, monocytes and T lymphocytes. However, its role in cardiac I/R injury remains poorly characterized. Here we reported that CXCL16-mediated cardiac infiltration of CD11b⁺Ly6C⁺ cells played a crucial role in IL-18-induced myocardial inflammation, apoptosis and left ventricular(LV) dysfunction during I/R. Treatment with CXCL16 shRNA attenuated I/R-induced cardiac injury, LV remodeling and cardiac inflammation by reducing the recruitment of inflammatory cells and the release of TNFα, IL-17 and IFN-γ in the heart. We found that I/R-mediated NLRP3/IL-18 signaling pathway triggered CXCL16 transcription in cardiac vascular endothelial cells(VECs). Two binding sites of FOXO3 were found at the promoter region of CXCL16. By luciferase report assay and ChIP analysis, we confirmed that FOXO3 was responsible for endothelial CXCL16 transcription. A pronounced reduction of CXCL16 was observed in FOXO3 siRNA pretreated-VECs. Further experiments revealed that IL-18 activated FOXO3 by promoting the phosphorylation of STAT3 but not STAT4. An interaction between FOXO3 and STAT3 enhanced the transcription of CXCL16 induced by FOXO3. Treatment with Anakinra or Stattic either effectively inhibited IL-18-mediated nuclear import of FOXO3 and CXCL16 transcription. Our findings suggested that IL-18 accelerated I/R-induced cardiac damage and dysfunction through activating CXCL-16 and CXCL16-mediated cardiac infiltration of the CD11b⁺Ly6C⁺ cells. CXCL16 might be a novel therapeutic target for the treatment of I/R-related ischemic heart diseases.

Chronic low-grade inflammation in heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) is currently the predominant form of HF with a dramatic increase in risk with age. Low-grade inflammation, as occurs with aging (termed "inflammaging"), is a common feature of HFpEF pathology. Suppression of proinflammatory pathways has been associated with attenuated HFpEF disease severity and better outcomes. From this perspective, inflammasome signaling plays a central role in mediating chronic inflammation and cardiovascular disease progression. However, the causal link between the inflammasome-immune signaling axis on the age-dependent progression of HFpEF remains conjectural. In this review, we summarize the current understanding of the role of inflammatory pathways in age-dependent cardiac function decline. We will also evaluate recent advances and evidence regarding the inflammatory pathway in the pathophysiology of HFpEF, with special attention to inflammasome signaling.

Cellular mechanisms and pathways in myocardial reperfusion injury

Despite the progress of cardiovascular medicine, ischemia-reperfusion injury can contribute to increased mortality and prolonged hospitalization after myocardial infarction. Ischemia-reperfusion injury pathophysiology encompasses many cells including cardiomyocytes, fibroblasts, mesenchymal stromal cells, vascular endothelial and smooth muscle cells, platelets, polymorphonuclear cells, macrophages, and T lymphocytes. However, specific mechanisms for all contributing cells and molecular pathways are still under investigation. What is definitely known is that endothelial dysfunction, immunity activation and inflammatory response are crucial events during ischemia-reperfusion injury while toll-like receptors, inflammasomes, reactive oxygen species, intracellular calcium overload and mitochondrial permeability transition pore opening consist of key molecular mediators. Indicatively, cardiac fibroblasts through inflammasome activation mediate the initial inflammatory response. Cardiac mesenchymal stromal cells can respond to myocardial injury by pro-inflammatory activation. Endothelial cell activation contributes to the impaired vasomotion, inflammation and thrombotic events and together with platelet activation leads to microcirculation dysfunction and polymorphonuclear cells recruitment promoting inflammation. Polymorphonuclear cells and monocytes/macrophages subsets are critically involved in the inflammation process by producing toxic proteolytic enzymes and reactive oxygen species. T cells subsets are also involved in several stages of ischemia-reperfusion injury. In this review, we summarize the specific contribution of each of the above cells and the related molecular pathways in the pathophysiology of ischemia-reperfusion injury.

Galectin-3 Derived from HucMSC Exosomes Promoted Myocardial Fibroblast-to-Myofibroblast Differentiation Associated with β-catenin Upregulation

Background and Objectives

Galectin-3 promotes fibroblast-to-myofibroblast differentiation and facilitates injury repair. Previous studies have shown that exosomes derived from human umbilical cord mesenchymal stem cells (hucMSC-ex) promote the differentiation of myocardial fibroblasts into myofibroblasts under inflammatory environment. Whether hucMSC-ex derived Galectin-3 (hucMSC-ex-Galectin-3) plays an important role in fibroblast-to-myofibroblast differentiation is the focus of this study.

Methods and Results

Galectin-3 was knocked-down by siRNA in hucMSCs, and then exosomes were extracted. Fibroblasts were treated with LPS, LPS＋hucMSC-ex, LPS＋negative control-siRNA-ex (NC-ex), or LPS＋Galectin-3-siRNA-ex (si-ex) in vitro. The coronary artery of the left anterior descending (LAD) branch was permanently ligated, followed by intramyocardial injection with phosphate buffered saline(PBS), hucMSC-ex, hucMSC-NC-ex, or hucMSC-si-ex in vivo. Western blot, RT-PCR, and immunohistochemistry were used to detect the expression of markers related to fibroblast-to-myofibroblast differentiation and inflammatory factors. Migration and contraction functions of fibroblasts were evaluated using Transwell migration and collagen contraction assays, respectively. β-catenin expression was detected by western blot and immunofluorescence. The results showed that hucMSC-ex increased the protein expression of myofibroblast markers, anti-inflammatory factors, and β-catenin. HucMSC-ex also reduced the migration and promoted the contractility of fibroblasts. However, hucMSC-si-ex did not show these activities.

Conclusions

HucMSC-ex-Galectin-3 promoted the differentiation of cardiac fibroblasts into myofibroblasts in an inflammatory environment, which was associated with increased β-catenin levels.

TAX1BP1 protects against myocardial infarction-associated cardiac anomalies through inhibition of inflammasomes in a RNF34/MAVS/NLRP3-dependent manner

Acute myocardial infarction (MI), one of the most common cardiovascular emergencies, is a leading cause of morbidity and mortality. Ample evidence has revealed an essential role for inflammasome activation and autophagy in the pathogenesis of acute MI. Tax1-binding protein 1 (TAX1BP1), an adaptor molecule involved in termination of proinflammatory signaling, serves as an important selective autophagy adaptor, but its role in cardiac ischemia remains elusive. This study examined the role of TAX1BP1 in myocardial ischemic stress and the underlying mechanisms involved. Levels of TAX1BP1 were significantly downregulated in heart tissues of patients with ischemic heart disease and in a left anterior descending (LAD) ligation-induced model of acute MI. Adenovirus carrying TAX1BP1 was delivered into the myocardium. The acute MI induced procedure elicited an infarct and cardiac dysfunction, the effect of which was mitigated by TAX1BP1 overexpression with little effect from viral vector alone. TAX1BP1 nullified acute MI-induced activation of the NLRP3 inflammasome and associated mitochondrial dysfunction. TAX1BP1 overexpression suppressed NLRP3 mitochondrial localization by inhibiting the interaction of NLRP3 with mitochondrial antiviral signaling protein (MAVS). Further investigation revealed that ring finger protein 34 (RNF34) was recruited to interact with TAX1BP1 thereby facilitating autophagic degradation of MAVS through K27-linked polyubiquitination of MAVS. Knockdown of RNF34 using siRNA nullified TAX1BP1 yielded protection against hypoxia-induced MAVS mitochondrial accumulation, NLRP3 inflammasome activation and associated loss of mitochondrial membrane potential. Taken together, our results favor a cardioprotective role for TAX1BP1 in acute MI through repression of inflammasome activation in a RNF34/MAVS-dependent manner.

Mild Hypothermia Therapy Lowers the Inflammatory Level and Apoptosis Rate of Myocardial Cells of Rats with Myocardial Ischemia-Reperfusion Injury via the NLRP3 Inflammasome Pathway

Objective

To explore the protective effects and mechanism of mild hypothermia treatment in the treatment of myocardial ischemia-reperfusion injury. Material and Methods. A total of 20 Sprague-Dawley (SD) rats were assigned to 4 groups: the blank control group, sham operation group, ischemia reperfusion group, and mild hypothermia therapy group (each n = 5). Some indexes were detected. In addition, myocardial cell models of oxygen-glucose deprivation/reoxygenation injury (OGD) were established. The expression of mRNA IL-6 and TNF-α and the key enzyme levels of apoptosis (cleaved-Caspase-3) and the NLRP3 inflammasome/p53 signaling pathway in the models were determined.

Results

The expression of serum IL-6 and TNF-α in the mild hypothermia therapy group was significantly lower than that in the ischemia reperfusion group. The mild hypothermia therapy group also showed a significantly lower TUNEL cell count and NLRP3 and p53 phosphorylation levels than the ischemia reperfusion group (all p < 0.05). The in vitro mild hypothermia + OGD group also showed significantly lower mRNA expression of IL-6 and TNF-α and levels of cleaved Caspase-3, NLRP3, and phosphorylated p53 protein than the OGD group (all p < 0.05).

Conclusion

In conclusion, mild hypothermia therapy can inhibit the apoptosis and myocardial inflammation of cells induced by MI/R injury in rats and inhibiting the activity of the NLRP3 inflammasome pathway and p53 signaling pathway may be the mechanism.

Promise of the NLRP3 Inflammasome Inhibitors in In Vivo Disease Models

Nucleotide-binding oligomerization domain NOD-like receptors (NLRs) are conserved cytosolic pattern recognition receptors (PRRs) that track the intracellular milieu for the existence of infection, disease-causing microbes, as well as metabolic distresses. The NLRP3 inflammasome agglomerates are consequent to sensing a wide spectrum of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Certain members of the NLR family have been documented to lump into multimolecular conglomerates called inflammasomes, which are inherently linked to stimulation of the cysteine protease caspase-1. Following activation, caspase-1 severs the proinflammatory cytokines interleukin (IL)-1β and IL-18 to their biologically active forms, with consequent commencement of caspase-1-associated pyroptosis. This type of cell death by pyroptosis epitomizes a leading pathway of inflammation. Accumulating scientific documentation has recorded overstimulation of NLRP3 (NOD-like receptor protein 3) inflammasome involvement in a wide array of inflammatory conditions. IL-1β is an archetypic inflammatory cytokine implicated in multiple types of inflammatory maladies. Approaches to impede IL-1β's actions are possible, and their therapeutic effects have been clinically demonstrated; nevertheless, such strategies are associated with certain constraints. For instance, treatments that focus on systemically negating IL-1β (i.e., anakinra, rilonacept, and canakinumab) have been reported to result in an escalated peril of infections. Therefore, given the therapeutic promise of an NLRP3 inhibitor, the concerted escalated venture of the scientific sorority in the advancement of small molecules focusing on direct NLRP3 inflammasome inhibition is quite predictable.

HIF-1α-Mediated miR-623 Regulates Apoptosis and Inflammatory Responses of Nucleus Pulposus Induced by Oxidative Stress via Targeting TXNIP

Excessive apoptosis and inflammatory responses of nucleus pulposus (NP) cells induced by oxidative stress contribute to intervertebral disc degeneration (IVDD). Though some microRNAs are associated with IVDD, the specific microRNA that can mediate apoptotic and inflammatory responses of NP cells induced by oxidative stress synchronously still needs further identification. Here, we find that microRNA-623 (miR-623) is downregulated in IVDD and its expression is regulated by hypoxia-inducible factor-1α (HIF-1α) under oxidative stress conditions. Mechanistically, HIF-1α is observed to promote miR-623 expression by directly binding to its promoter region (-1,994/-1,987 bp). Functionally, miR-623 is found to work as an intermediator in alleviating apoptosis and inflammatory responses of NP cells induced by oxidative stress via regulating thioredoxin-interacting protein (TXNIP) expression by directly targeting its 3'-untranslated region (3'-UTR). Thus, on elucidating the expression and functional mechanisms of miR-623, our study suggests that miR-623 can be a valuable therapeutic target for treating oxidative stress-induced IVDD.

Suppressing Pyroptosis Augments Post-Transplant Survival of Stem Cells and Cardiac Function Following Ischemic Injury

The acute demise of stem cells following transplantation significantly compromises the efficacy of stem cell-based cell therapeutics for infarcted hearts. As the stem cells transplanted into the damaged heart are readily exposed to the hostile environment, it can be assumed that the acute death of the transplanted stem cells is also inflicted by the same environmental cues that caused massive death of the host cardiac cells. Pyroptosis, a highly inflammatory form of programmed cell death, has been added to the list of important cell death mechanisms in the damaged heart. However, unlike the well-established cell death mechanisms such as necrosis or apoptosis, the exact role and significance of pyroptosis in the acute death of transplanted stem cells have not been explored in depth. In the present study, we found that M1 macrophages mediate the pyroptosis in the ischemia/reperfusion (I/R) injured hearts and identified miRNA-762 as an important regulator of interleukin 1β production and subsequent pyroptosis. Delivery of exogenous miRNA-762 prior to transplantation significantly increased the post-transplant survival of stem cells and also significantly ameliorated cardiac fibrosis and heart functions following I/R injury. Our data strongly suggest that suppressing pyroptosis can be an effective adjuvant strategy to enhance the efficacy of stem cell-based therapeutics for diseased hearts.

LuQi Formula Regulates NLRP3 Inflammasome to Relieve Myocardial-Infarction-Induced Cardiac Remodeling in Mice

Background

Excessive activation of the nod-like receptor family pyrin domain containing 3(NLRP3) inflammasome plays a significant role in the progression of cardiac injury. In China, it has been well recognized that Chinese herbal medicine is markedly effective in treating cardiovascular diseases (CVDs). LuQi Formula (LQF) has been used clinically for more than 10 years and confirmed to be effective in improving cardiac function and inhibiting apoptosis. However, the specific mechanisms underlying its efficacy are mostly unknown. This study aimed to evaluate whether LQF could alleviate cardiac injury and apoptosis by regulating the NLRP3 inflammasome and the caspase-3/Bax pathway.

Purpose

In this study, we investigated the effects of LQF on cardiac remodeling in a mouse model of myocardial infarction (MI) in vivo.

Methods

Forty male C57BL/6 mice were randomly divided into four groups: the sham group, the model group, the LQF group, and the perindopril group, with a sample size (n) of 10 mice in each group. Except the sham group, the other groups received left anterior descending (LAD) coronary artery ligation to induce MI and then treated with LQF, perindopril, or saline. Six weeks after MI, echocardiography was used to evaluate cardiac structure and function. Myocardial tissue morphology was observed by haematoxylin and eosin (H&E) staining, and heart samples were stained with Masson's trichrome to analyse myocardial fibrosis. Myocardial hypertrophy was observed by fluorescent wheat germ agglutinin (WGA) staining. The expressions of NLRP3, ASC, Cle-caspase-1, IL-1β, TXNIP, Cle-caspase-3, Bcl-2, and Bax in heart tissues were assessed by western blot analysis. mRNA expressions of ANP and BNP in heart tissues were measured by RT-PCR. The expression of reactive oxygen species in myocardial tissue was detected by using a DCFH-DA probe.

Results

Echocardiographic analysis showed that compared with the model group, the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in the LQF and perindopril group were increased (P < 0.05), left ventricular internal diameter end diastole (LVIDd) and left ventricular internal diameter end-systole (LVIDs) were reduced (P < 0.05), and H&E and Masson's trichrome staining of cardiac tissues showed that LQF and perindopril could partially reverse ventricular remodeling and alleviate myocardial fibrosis (P < 0.05). WGA fluorescence results showed that compared with the model group, myocardial hypertrophy was significantly reduced in the LQF and perindopril group. We also found that LQF and perindopril reduce the oxidative stress response in the heart of MI mice. The protein expression of NLRP3, ASC, Cle-caspase-1, IL-1β, TXNIP, Cle-caspase-3, and Bax was downregulated in the LHF and perindopril treatment group, and Bcl-2 expression was upregulated.

Conclusion

LQF and perindopril significantly attenuated cardiac injury and apoptosis in the MI model. In addition, we found that LQF effectively inhibited the activation of the NLRP3/ASC/caspase-1/IL-1β cascade, decreased inflammatory infiltration, delayed ventricular remodeling, and downregulated caspase-3/Bax signaling, which can effectively reduce the apoptosis of cardiomyocytes. Perindopril showed the same mechanism.

The Role of Pyroptosis in Ischemic and Reperfusion Injury of the Heart

While ischemia itself can kill heart muscle, much of the infarction after a transient period of coronary artery occlusion has been found to result from injury during reperfusion. Here we review the role of inflammation and possible pyroptosis in myocardial reperfusion injury. Current evidence suggests pyroptosis's contribution to infarction may be considerable. Pyroptosis occurs when inflammasomes activate caspases that in turn cleave off an N-terminal fragment of gasdermin D. This active fragment makes large pores in the cell membrane thus killing the cell. Inhibition of inflammation enhances cardiac tolerance to ischemia and reperfusion injury. Stimulation of the purinergic P2X7 receptor and the β-adrenergic receptor and activation of nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) by toll-like receptor (TLR) agonists are all known to contribute to ischemia/reperfusion (I/R) cardiac injury through inflammation, potentially by pyroptosis. In contrast, stimulation of the cannabinoid CB2 receptor reduces I/R cardiac injury and inhibits this pathway. MicroRNAs, Akt, the phosphate and tension homology deleted on chromosome 10 protein (PTEN), pyruvate dehydrogenase and sirtuin-1 reportedly modulate inflammation in cardiomyocytes during I/R. Cryopyrin and caspase-1/4 inhibitors are reported to increase cardiac tolerance to ischemic and reperfusion cardiac injury, presumably by suppressing inflammasome-dependent inflammation. The ambiguity surrounding the role of pyroptosis in reperfusion injury arises because caspase-1 also activates cytotoxic interleukins and proteolytically degrades a surprisingly large number of cytosolic enzymes in addition to activating gasdermin D.

Loss of Hepatic Angiotensinogen Attenuates Sepsis-Induced Myocardial Dysfunction

Rationale: The renin-angiotensin system (RAS) is a complex regulatory network that maintains normal physiological functions. The role of the RAS in sepsis-induced myocardial dysfunction (SIMD) is poorly defined. Angiotensinogen (AGT) is the unique precursor of the RAS and gives rise to all angiotensin peptides. The effects and mechanisms of AGT in development of SIMD have not been defined. Objective: To determine a role of AGT in SIMD and investigate the underlying mechanisms. Methods and Results: Either intraperitoneal injection of lipopolysaccharide (LPS) or cecal ligation and puncture (CLP) significantly enhanced AGT abundances in liver, heart, and plasma. Deficiency of hepatocyte-derived AGT (hepAGT), rather than cardiomyocyte-derived AGT (carAGT), alleviated septic cardiac dysfunction in mice and prolonged survival time. Further investigations revealed that the effects of hepAGT on SIMD were partially associated with augmented angiotensin II (AngII) production in circulation. In addition, hepAGT was internalized by LDL receptor-related protein 1 (LRP1) in cardiac fibroblasts (CF), and subsequently activated NLRP3 inflammasome via an AngII-independent pathway, ultimately promoting SIMD by suppressing Sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) abundances in cardiomyocytes (CM). Conclusions: HepAGT promoted SIMD via both AngII-dependent and AngII-independent pathways. We identified a liver-heart axis by which AGT regulated development of SIMD. Our study may provide a potential novel therapeutic target for SIMD.

Inflammatory Cytokines, Immune Cells, and Organ Interactions in Heart Failure

Despite mounting evidence demonstrating the significance of inflammation in the pathophysiological mechanisms of heart failure (HF), most large clinical trials that target the inflammatory responses in HF yielded neutral or even worsening outcomes. Further in-depth understanding about the roles of inflammation in the pathogenesis of HF is eagerly needed. This review summarizes cytokines, cardiac infiltrating immune cells, and extracardiac organs that orchestrate the complex inflammatory responses in HF and highlights emerging therapeutic targets.

Atrial fibrosis as a dominant factor for the development of atrial fibrillation: facts and gaps

Atrial fibrillation (AF), the most commonly diagnosed arrhythmia, affects a notable percentage of the population and constitutes a major risk factor for thromboembolic events and other heart-related conditions. Fibrosis plays an important role in the onset and perpetuation of AF through structural and electrical remodelling processes. Multiple molecular pathways are involved in atrial substrate modification and the subsequent maintenance of AF. In this review, we aim to recapitulate underlying molecular pathways leading to atrial fibrosis and to indicate existing gaps in the complex interplay of atrial fibrosis and AF.

Vincristine attenuates cardiac fibrosis through the inhibition of NLRP3 inflammasome activation

Vincristine (VCR) is widely used in cancer therapies, although its benefits on cardiac fibrosis remain unknown. Here, we investigated VCR's efficacy on cardiac fibrosis and elucidated the underlying mechanism of action. Network pharmacology was employed to predict the mechanism of VCR action on cardiac fibrosis. We induced cardiac fibrosis in adult male Sprague-Dawley (SD) rats via isoproterenol (ISO) injection, followed by treatment with VCR or vehicle. After 10 days of treatment, VCR-treated rats exhibited a significantly lower heart/body weight ratio relative to those treated with the vehicle. Moreover, cardiac fibrosis was alleviated in VCR-treated rats relative to vehicle-treated rats. The results revealed the down-regulation of mature caspase-1, interleukin (IL)-1β, and IL-18 in VCR-treated rats relative to vehicle-treated rats. We also observed less colocalization between the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) and apoptosis-associated speck-like protein containing a CARD (ASC) in VCR-treated rats compared with vehicle-treated rats. We then cultured neonatal rat cardiac fibroblasts (NRCFs) and exposed them to lipopolysaccharide (LPS) and adenosine triphosphate (ATP) in the presence or absence of VCR. The results indicated that VCR mediated the down-regulation of caspase-1, IL-1β, and IL-18 and the colocalization of NLRP3 and ASC in LPS+ATP-stimulated cardiac fibroblasts (CFs). We found evidence that VCR attenuates cardiac fibrosis by directly suppressing the activation of the NLRP3 inflammasome. These findings provide novel insights into VCR's mechanism of action in alleviating cardiac fibrosis.

Exogenous stromal cell-derived factor-1 (SDF-1) suppresses the NLRP3 inflammasome and inhibits pyroptosis in synoviocytes from osteoarthritic joints via activation of the AMPK signaling pathway

Objective

NLRP3 inflammasome may play a key role in OA pathogenesis. Stromal cell-derived factor-1 (SDF-1) is a homeostatic CXC chemokine. Since the role of SDF-1 in OA has not been explored, this study aimed to examine the effect of SDF-1 on NLRP3 inflammasome and pyroptosis in synoviocytes from OA joints.

Materials and methods

Human synovium was obtained from OA patients for isolation of primary synoviocytes and a murine model of collagenase-induced OA was established for testing intra-articular injections of SDF-1. Immunoblotting assays were used to examine the effects and underlying mechanism of action of SDF-1 on NLRP3 inflammasome and synoviocyte pyroptosis in synoviocytes. Inhibitors of AMPK and PI3K–mTOR were utilized to investigate the key signaling pathways involved in SDF-1-mediated OA inflammasome formation and pyroptosis.

Results

Synoviocytes from OA joints exhibited significantly higher expression of NLRP3 inflammasome and biomarkers of synoviocyte pyroptosis relative to healthy individuals. This was confirmed in the collagenase-induced OA model, where OA synoviocytes had a significantly lower SDF-1 expression than healthy ones. SDF-1 treatment in synoviocytes of OA patients and collagenase-induced OA led to significant downregulation in the expression of NLRP3 inflammasome and synoviocyte pyroptosis biomarkers. Inhibition of the AMPK signaling pathway significantly suppressed the inhibitory effect of SDF-1 on NLRP3 inflammasome expression of OA synoviocytes. However, blocking the SDF-1-activated PI3K–mTOR signaling pathway could still suppress the expression of NLRP3 inflammasome and synoviocyte pyroptosis biomarkers.

Conclusions

SDF-1 ameliorates NLRP3 inflammasome and pyroptosis in OA synoviocytes through activation of the AMPK signaling pathway. Therefore, SDF-1 may be a novel therapeutic target for OA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10787-021-00814-x.

Resveratrol improves cardiac function and left ventricular fibrosis after myocardial infarction in rats by inhibiting NLRP3 inflammasome activity and the TGF-β1/SMAD2 signaling pathway

BACKGROUND

Several studies have shown that resveratrol (RES), a naturally occurring polyphenol found in many plants, is beneficial for preventing cardiovascular diseases. However, the mechanism underlying the RES-mediated protection against myocardial infarction has not yet been revealed entirely. In this study, we investigated the protective effects of RES on cardiac function in a rat model of acute myocardial infarction (AMI) and the related underlying mechanisms.

METHODS

Male Sprague-Dawley rats were randomly divided into four groups: Sham (sham operation), Sham-RES, AMI (AMI induction), and AMI-RES. The rat AMI model was established by the permanent ligation of left anterior descending coronary artery method. The rats in the RES-treated groups were gavaged with RES (50 mg/kg/day) daily for 45 days after the Sham operation or AMI induction; rats in the Sham and AMI groups were gavaged with deionized water. Cardiac function was evaluated by echocardiography. Atrial interstitial fibrosis was assessed by hematoxylin-eosin or Masson's trichrome staining. Real-time PCR and western blotting analyses were performed to examine the levels of signaling pathway components.

RESULTS

RES supplementation decreased the inflammatory cytokine levels, improved the cardiac function, and ameliorated atrial interstitial fibrosis in the rats with AMI. Furthermore, RES supplementation inhibited NLRP3 inflammasome activity, decreased the TGF-β1 production, and downregulated the p-SMAD2/SMAD2 expression in the heart.

CONCLUSION

RES shows notable cardioprotective effects in a rat model of AMI; the possible mechanisms underlying these effects may involve the improvement of cardiac function and atrial interstitial fibrosis via the RES-mediated suppression of NLRP3 inflammasome activity and inhibition of the TGF-β1/SMAD2 signaling pathway in the heart.