Blocking the IL-1β signalling pathway prevents chronic viral myocarditis and cardiac remodeling

A review of therapeutic approaches for post-infarction left ventricular remodeling

Left ventricular remodeling is an adaptive process initially developed in response to acute myocardial infarction (AMI), but it ends up with negative adverse outcomes such as infarcted wall thinning, ventricular dilation, and cardiac dysfunction. A prolonged excessive inflammatory reaction to cardiomyocytes death and necrosis plays the crucial role in the pathophysiological mechanisms. The pharmacological treatment includes nitroglycerine, β-blockers, ACEi/ARBs, SGLT2i, mineralocorticoid receptor antagonists, and some miscellaneous aspects. Stem cells therapy, CD34+ cells transplantation and gene therapy constitute the promissing therapeutic approaches for post AMI cardiac remodeling, thereby enhancing angiogenesis, cardiomyocytes differenciation and left ventricular function on top of inhibiting apoptosis, inflammation, and collagen deposition. All these lead to reduce infarct size, scar formation and myocardial fibrosis.

Innate and adaptive immunity in acute myocarditis

Acute myocarditis is an acute inflammatory cardiomyopathy associated with cardiac damage triggered by a virus or a pathological immune activation. It may present with a wide range of clinical presentations, ranging from mild symptoms to severe forms like fulminant myocarditis, characterized by hemodynamic compromise and cardiogenic shock. The immune system plays a central role in the pathogenesis of myocarditis. In fact, while its function is primarily protective, aberrant responses can be detrimental. In this context, both innate and adaptive immunity play pivotal roles; notably, the innate system offers a non-specific and immediate defense, while the adaptive provides specialized protection with immunological memory. However, dysregulation in these systems can misidentify cardiac tissue, triggering autoimmune reactions and possibly leading to significant cardiac tissue damage. This review highlights the importance of innate and adaptive immune responses in the progression and treatment of acute myocarditis.

Macrophages in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

Effectiveness and safety of IL1 inhibition with anakinra in chronic refractory idiopathic myocarditis

AIM

The aim of this study was to evaluate the effectiveness and safety of the anti-IL-1 receptor anakinra in patients with chronic active myocarditis refractory to standard therapy.

METHODS AND RESULTS

In this retrospective, observational study, we enrolled 6 patients with chronically active myocarditis treated with anakinra on-top-of standard treatment. Response to treatment was evaluated at different time points [disease onset (T0), anakinra beginning (T1), three months from anakinra beginning (T2), last available follow-up (T3)], and was assessed by variations in New York Heart Association (NYHA) functional class, laboratory tests [C-reactive protein (CRP), a high-sensitivity cardiac troponin T (cTnT), and Nt-proBNP], left ventricular ejection fraction (LVEF), and cardiac magnetic resonance (CMR) edema or late gadolinium enhancement. The number of premature ventricular complexes (PVCs) at 24-h EKG-recordings was considered in patients with arrhythmic manifestations. No differences were found between T0 and T1 in terms of CRP, Nt-ProBNP, and LVEF. Before anakinra beginning, all patients were still symptomatic. At T2, all patients were symptom-free, in NYHA class I. A significant decrease in CRP (p = 0.03) and a significant improvement in LVEF (p = 0.03) were observed. Sustained arrhythmic manifestations were found in 4 out of 6 patients. In this subgroup, anakinra showed effectiveness in reducing the arrhythmic burden. At T3, the improvement in laboratory values and cardiac function persisted. The arrhythmic burden remained abated.

CONCLUSIONS

All patients had a rapid improvement in systemic inflammation, cardiac function, and arrhythmic burden with anti-IL1 therapy, indicating that anakinra may be an effective treatment in chronic active idiopathic myocarditis, refractory to standard treatment.

The inflammatory spectrum of cardiomyopathies

Infiltration of the myocardium with various cell types, cytokines and chemokines plays a crucial role in the pathogenesis of cardiomyopathies including inflammatory cardiomyopathies and myocarditis. A more comprehensive understanding of the precise immune mechanisms involved in acute and chronic myocarditis is essential to develop novel therapeutic approaches. This review offers a comprehensive overview of the current knowledge of the immune landscape in cardiomyopathies based on etiology. It identifies gaps in our knowledge about cardiac inflammation and emphasizes the need for new translational approaches to improve our understanding thus enabling development of novel early detection methods and more effective treatments.

Jingfang Granule mitigates Coxsackievirus B3-induced myocardial damage by modulating mucolipin 1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Jingfang Granules (JFG) originate from the traditional herbal formula Jingfang Baidu powder. It has the effects of inducing sweating and dispelling wind. It is a classic medication used for treating external pathogenic factors and viral diseases. However, the therapeutic mechanism of JFG for viral myocarditis needs further clarification.

AIM OF THE STUDY

This study aimed to explore the therapeutic efficacy of JFG on coxsackievirus B3-induced viral myocarditis (VMC), along with the elucidation of its underlying mechanisms.

MATERIALS AND METHODS

C57 BL/6JNifdc mice were divided randomly into several groups: control, model, Jingfang Granule groups (0.23, 0.46, and 0.69 g/20g, respectively), and a positive group (oseltamivir, 19.33 mg/kg). Following the establishment of the VMC model, the mice underwent an 8 -week treatment regimen. Pathological alterations in cardiac tissues and inflammatory protein expression were monitored. Differential gene analysis was conducted utilizing transcriptomic techniques. The differential gene mucolipin 1 (Mcoln1) was knocked down by transfection with siRNA in H9C2 cell, and investigative techniques such as immunoblotting, qRT-PCR, immunofluorescence, JC-1 staining, reactive oxygen species (ROS) detection, and mitochondrial stress testing were employed to examine its mechanism of action.

RESULTS

JFG significantly mitigates the pathological damage observed in the cardiac tissues of CVB3-induced VMC mice and attenuates the expression of inflammatory genes. Subsequently, differentially expressed genes are identified through transcriptomic analysis and validated via PCR. Among these, the upregulation of Mcoln1 promotes autophagy, facilitating the clearance of damaged mitochondria and excessive ROS. This has been substantiated through in vitro experiments. Excessive ROS precipitates a reduction in mitochondrial membrane potential, instigating cell apoptosis. In accordance with TUNEL staining results, JFG acts to inhibit cell apoptosis. To ascertain whether Mcoln1 is a crucial target for JFG in treating VMC, Mcoln1 was suppressed in H9C2 cells. The suppression of Mcoln1 hinders the elevation in autophagy levels post-JFG treatment, obstructs the enhancement of mitochondrial function, and impedes the clearance of ROS. Furthermore, the inhibitory effect of JFG on cell apoptosis is attenuated.

CONCLUSION

The research findings indicate that JFG has a protective effect on CVB3-induced H9C2 cell injury. JFG may exert its effects in VMC treatment by enhancing autophagy to suppress cell apoptosis through the mitochondrial pathway, thereby counteracting cell damage.

Pathogenic pathways and therapeutic targets of inflammation in heart diseases: A focus on Interleukin-1

BACKGROUND

An exuberant and dysregulated inflammatory response contributes to the development and progression of cardiovascular diseases (CVDs).

METHODS

This narrative review includes original articles and reviews published over the past 20 years and found through PubMed. The following search terms (or combination of terms) were considered: "acute pericarditis," "recurrent pericarditis," "myocarditis," "cardiac sarcoidosis," "atherosclerosis," "acute myocardial infarction," "inflammation," "NLRP3 inflammasome," "Interleukin-1" and "treatment."

RESULTS

Recent evidence supports the role of inflammation across a wide spectrum of CVDs including myocarditis, pericarditis, inflammatory cardiomyopathies (i.e. cardiac sarcoidosis) as well as atherosclerotic CVD and heart failure. Interleukins (ILs) are the signalling mediators of the inflammatory response. The NACHT, leucine-rich repeat and pyrin-domain containing protein 3 (NLRP3) inflammasome play a key role in producing IL-1β, the prototypical pro-inflammatory cytokine involved in CVDs. Other pro-inflammatory cytokines (e.g. tumour necrosis factor) have been implicated in cardiac sarcoidosis. As a proof of this, IL-1 blockade has been proven efficacious in pericarditis and chronic coronary syndrome.

CONCLUSION

Tailored strategies aiming at quenching the inflammatory response have emerged as promising to treat CVDs. In this review article, we summarize recent evidence regarding the role of inflammation across a broad spectrum of CVDs. We also review novel evidence regarding targeted therapeutic strategies.

CD4+TEM cells drive the progression from acute myocarditis to dilated cardiomyopathy in CVB3-induced BALB/c mice

Acute viral myocarditis can progress to chronic myocarditis leading to dilated cardiomyopathy (DCM). Persistent CD4+ T-cell-mediated autoimmunity triggered by infection plays a critical role in this progression. Increasing evidence demonstrates that effector memory CD4+T (CD4+TEM) cells, a subset of memory CD4+ T cells, are crucial pathogenic mediators of many autoimmune diseases. However, the role of CD4+TEM cells during the progression from acute viral myocarditis to DCM remains unknown. In this study, we observed an increase in CD4+TEM cells both in the periphery and the heart, and memory CD4+ T cells were the predominant sources of IL-17A and IFN-γ among inflamed heart-infiltrating CD4+ T cells during the progression from acute myocarditis to chronic myocarditis and DCM in CVB3-induced BALB/c mice. Moreover, splenic CD4+TEM cells sorted from DCM mice induced by CVB3 were found to respond to cardiac self-antigens ex vivo. Additionally, adoptive transfer experiments substantiated their pathogenic impact, inducing sustained myocardial inflammation, tissue fibrosis, cardiac injury, and impairment of cardiac systolic function in vivo. Our findings illustrate that long-lived CD4+TEM cells are important contributors to the progression from acute viral myocarditis into DCM.

Investigating the virulence of coxsackievirus B6 strains and antiviral treatments in a neonatal murine model

Coxsackievirus B6 (CVB6), a member of the human enterovirus family, is associated with severe diseases such as myocarditis in children. However, to date, only a limited number of CVB6 strains have been identified, and their characterization in animal models has been lacking. To address this gap, in this study, a neonatal murine model of CVB6 infection was established to compare the replication and virulence of three infectious-clone-derived CVB6 strains in vivo. The results showed that following challenge with a lethal dose of CVB6 strains, the neonatal mice rapidly exhibited a series of clinical signs, such as weight loss, limb paralysis, and death. For the two high-virulence CVB6 strains, histological examination revealed myocyte necrosis in skeletal and cardiac muscle, and immunohistochemistry confirmed the expression of CVB6 viral protein in these tissues. Real-time PCR assay also revealed higher viral loads in the skeletal and cardiac muscle than in other tissues at different time points post infection. Furthermore, the protective effect of passive immunization with antisera and a neutralizing monoclonal antibody against CVB6 infection was evaluated in the neonatal mouse model. This study should provide insights into the pathogenesis of CVB6 and facilitate further research in the development of vaccines and antivirals against CVBs.

Reconstituted Extracellular Vesicles from Human Platelets Decrease Viral Myocarditis in Mice

Patients with viral myocarditis are at risk of sudden death and may progress to dilated cardiomyopathy (DCM). Currently, no disease-specific therapies exist to treat viral myocarditis. Here it is examined whether reconstituted, lyophilized extracellular vesicles (EVs) from platelets from healthy men and women reduce acute or chronic myocarditis in male mice. Human-platelet-derived EVs (PEV) do not cause toxicity, damage, or inflammation in naïve mice. PEV administered during the innate immune response significantly reduces myocarditis with fewer epidermal growth factor (EGF)-like module-containing mucin-like hormone receptor-like 1 (F4/80) macrophages, T cells (cluster of differentiation molecules 4 and 8, CD4 and CD8), and mast cells, and improved cardiac function. Innate immune mediators known to increase myocarditis are decreased by innate PEV treatment including Toll-like receptor (TLR)4 and complement. PEV also significantly reduces perivascular fibrosis and remodeling including interleukin 1 beta (IL-1β), transforming growth factor-beta 1, matrix metalloproteinase, collagen genes, and mast cell degranulation. PEV given at days 7-9 after infection reduces myocarditis and improves cardiac function. MicroRNA (miR) sequencing reveals that PEV contains miRs that decrease viral replication, TLR4 signaling, and T-cell activation. These data show that EVs from the platelets of healthy individuals can significantly reduce myocarditis and improve cardiac function.

Immune mechanisms of group B coxsackievirus induced viral myocarditis

Viral myocarditis is known to be a primary cause of dilated cardiomyopathy (DCM) that can lead to heart failure and sudden cardiac death and is invariably caused by myocardial viral infection following active inflammatory destruction of the myocardium. Although acute viral myocarditis frequently recovers on its own, current chronic myocarditis therapies are unsatisfactory, where the persistence of viral or immunological insults to the heart may play a role. Cellular and mouse experimental models that utilized the most prevalent Coxsackievirus group B type 3 (CVB3) virus infection causing myocarditis have illustrated the pathophysiology of viral myocarditis. In this review, immunological insights into the different stages of development of viral myocarditis were discussed, concentrating on the mechanisms of innate and adaptive immunity in the development of CVB3-induced myocarditis.

Obesity Enables NLRP3 Activation and Induces Myocardial Fibrosis via Hyperacetylation of HADHa

Obesity increases the risk of myocardial fibrosis, a pathological change in most heart diseases, but the mechanism has not been fully elucidated. Here, we found that mice with high-fat diet-induced obesity had more severe myocardial fibrosis than control mice under normal and ischemia/reperfusion (I/R) conditions, which could be alleviated by neutralizing antibodies against interleukin (IL)-1β and IL-18, downstream products of the nucleotide-binding oligomerization-like receptor protein 3 (NLRP3) inflammasome, and the NLRP3 inhibitor MCC950. Mechanistically, mitochondrial hyperacetylation in obese mouse hearts recruited apoptosis-associated speck-like protein containing a CARD (ASC) to mitochondria and thus facilitated NLRP3 inflammasome assembly. Acetylation of K255 on hydroxyl-CoA dehydrogenase α subunit (HADHa) was identified to trigger the mitochondrial localization of ASC. Blockade of HADHa-K255 acetylation downregulated mitochondrial ASC, suppressed the NLRP3 inflammasome, and attenuated post-I/R myocardial fibrosis in obese mouse hearts. In obese human patients, the extent of myocardial fibrosis according to T1 MRI was positively correlated with the plasma levels of IL-1β and IL-18, supporting the connection of NLRP3 inflammation to obesity-induced myocardial fibrosis. In conclusion, our study demonstrates that the heart is susceptible to fibrosis under obesity through hyperacetylated HADHa-mediated activation of the NLRP3 inflammasome.

ARTICLE HIGHLIGHTS

Cardiac Fibrosis in heart failure: Focus on non-invasive diagnosis and emerging therapeutic strategies

Heart failure is a leading cause of mortality and hospitalization worldwide. Cardiac fibrosis, resulting from the excessive deposition of collagen fibers, is a common feature across the spectrum of conditions converging in heart failure. Eventually, either reparative or reactive in nature, in the long-term cardiac fibrosis contributes to heart failure development and progression and is associated with poor clinical outcomes. Despite this, specific cardiac antifibrotic therapies are lacking, making cardiac fibrosis an urgent unmet medical need. In this context, a better patient phenotyping is needed to characterize the heterogenous features of cardiac fibrosis to advance toward its personalized management. In this review, we will describe the different phenotypes associated with cardiac fibrosis in heart failure and we will focus on the potential usefulness of imaging techniques and circulating biomarkers for the non-invasive characterization and phenotyping of this condition and for tracking its clinical impact. We will also recapitulate the cardiac antifibrotic effects of existing heart failure and non-heart failure drugs and we will discuss potential strategies under preclinical development targeting the activation of cardiac fibroblasts at different levels, as well as targeting additional extracardiac processes.

Celastrol relieves myocardial infarction-induced cardiac fibrosis by inhibiting NLRP3 inflammasomes in rats

BACKGROUND

Myocardial infarction (MI) triggers a strong inflammatory response mediating by NLRP3 inflammasome which is associated with cardiac fibrosis. The key players in this response are Interleukin (IL)-1 and IL-18, which are regulated by NLRP3 inflammasomes. Celastrol, a traditional Chinese medicine with strong anti-inflammatory activity, has recently reported as a cardioprotective agent. However, the mechanisms by which celastrol is cardioprotective in MI remain elusive. We hypothesized that Celastrol could reduce IL-1β and IL-18 expression and ameliorate myocardial fibrosis after myocardial infarction in rats, improve poor heart remodeling, and preserve heart function.

METHODS

Myocardial infarction (MI) was caused by ligating the left anterior descending of male SD rats. Celastrol (1 mg/kg) or saline was administered every other day for 4 weeks. Heart function and fibrosis were assessed. Inflammatory and fibrotic markers in the myocardia were evaluated with immunohistochemistry, western blot, and ELISA. Molecular docking was employed to predict Celastrol's binding to NLRP3 protein. The effects of Celastrol on the expression of NLRP3 inflammasome and myocardial fibrosis genes were then examined in vitro.

RESULTS

Celastrol maintained the left ventricular fractional shortening (FS) and ejection fraction (EF). Fibrosis was significantly reduced in animals treated with 1 mg/kg Celastrol (15.17 ± 1.82%) relative to controls (29.88 ± 4.28%). Celastrol also significantly reduced the NLRP3, IL-18, and IL-1β levels, together with macrophage and neutrophil infiltration in the myocardium. Molecular docking predicted that NLRP3 would bind tightly to Celastrol [Docking energy: -8.9 (kcal/mol)]. In vitro experiments showed reduced NLRP3 inflammasome and myocardial fibrosis-associated proteins expression in neonatal rat cardiac fibroblasts treated with Celastrol.

CONCLUSIONS

In post-MI rats, Celastrol, a naturally occurring active ingredient, was able to reduce myocardial fibrosis and improve cardiac function, according to our study. These effects may result from inhibiting the NLRP3 inflammasome and attenuating the early inflammatory storm after MI, suggesting that Celastrol may be useful in treating acute MI.

A combination of Sophora flavescens alkaloids and Panax quinquefolium saponins attenuates coxsackievirus B3‑induced acute myocarditis in mice via NF‑κB signaling

Timely treatment of viral myocarditis (VMC), a form of cardiac inflammation caused by viral infections, can reduce the occurrence of dilated cardiomyopathy and sudden death. Our previous study demonstrated the anti-inflammatory and anti-fibrotic effects of KX, a combination of Sophora flavescens alkaloids and Panax quinquefolium saponins, on an autoimmune myocarditis model in vivo. The present study explored the effects of KX on coxsackievirus B3 (CVB3)-induced acute VMC in mice. Mice were randomly divided into four groups: Control, VMC, KX-high (275 mg/kg) and KX-low (138 mg/kg). Mice in the VMC, KX-high and KX-low groups received injections of CVB3 to establish the VMC model, and those in the KX-high and KX-low groups also received KX by gavage (10 ml/kg) 2 h after virus injection until euthanasia was performed on day 7 or 21. Mice in the control group received an equal KX volume of purified water. The levels of lactate dehydrogenase (LDH), creatine kinase-myocardial band (CK-MB), cardiac troponin I (cTn-I), IL-1β, IL-6, TNF-α and high-sensitive C-reactive protein (hs-CRP) in mouse serum was measured using ELISA. Myocardial tissue structure and degree of injury were observed using hematoxylin and eosin staining. Western blotting and reverse transcription-quantitative PCR were performed to detect the expression levels of NF-κB pathway-related mRNA and protein in myocardial tissue. The results showed that the inflammation and myocardial damage levels of the mice in the VMC group were higher at 7 days than those at 21 days. At both 7 and 21 days, KX decreased the serum CK-MB, LDH, cTn-I, IL-6, TNF-α and hs-CRP levels, and inhibited NF-κB pathway-related mRNA and protein expression in the myocardium of mice. These findings indicated that KX may reduce the inflammatory response and attenuate the pathological damage in the acute and subacute phases of CVB3-induced VMC through the NF-κB pathway.

Roles of inflammasomes in viral myocarditis

Viral myocarditis (VMC), characterized by viral infection-induced inflammation, is a life-threatening disease associated with dilated cardiomyopathy or heart failure. Innate immunity plays a crucial role in the progression of inflammation, in which inflammasomes provide a platform for the secretion of cytokines and mediate pyroptosis. Inflammasomes are rising stars gaining increasing attention. The nucleotide oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, the caspase recruitment domain-containing protein 8 (CARD8) inflammasome, and the caspase-11 inflammasome are three inflammasomes that were reported to affect the process and prognosis of VMC. These inflammasomes can be activated by a wide range of cellular events. Accumulating evidence has suggested that inflammasomes are involved in different stages of VMC, including the trigger and progression of myocardial injury and remodeling after infection. In this review, we summarized the pathways involving inflammasomes in VMC and discussed the potential therapies targeting inflammasomes and related pathways.

Role of Coxsackievirus B3-Induced Immune Responses in the Transition from Myocarditis to Dilated Cardiomyopathy and Heart Failure

Dilated cardiomyopathy (DCM) is a cardiac disease marked by the stretching and thinning of the heart muscle and impaired left ventricular contractile function. While most patients do not develop significant cardiac diseases from myocarditis, disparate immune responses can affect pathological outcomes, including DCM progression. These altered immune responses, which may be caused by genetic variance, can prolong cytotoxicity, induce direct cleavage of host protein, or encourage atypical wound healing responses that result in tissue scarring and impaired mechanical and electrical heart function. However, it is unclear which alterations within host immune profiles are crucial to dictating the outcomes of myocarditis. Coxsackievirus B3 (CVB3) is a well-studied virus that has been identified as a causal agent of myocarditis in various models, along with other viruses such as adenovirus, parvovirus B19, and SARS-CoV-2. This paper takes CVB3 as a pathogenic example to review the recent advances in understanding virus-induced immune responses and differential gene expression that regulates iron, lipid, and glucose metabolic remodeling, the severity of cardiac tissue damage, and the development of DCM and heart failure.

IL-37 alleviates Coxsackievirus B3-induced viral myocarditis via inhibiting NLRP3 inflammasome-mediated pyroptosis

Our study aims to verify the potential effects and underlying mechanisms of IL-37 in Coxsackievirus B3 (CVB3)-induced viral myocarditis (VMC). VMC model was established by intraperitoneal injection of CVB3 into 6-week-old male balb-c mice on day 0. Each mouse of the IL-37-control group and IL-37-VMC CVB3 groups was intraperitoneally injected with IL-37 on day 4 and day 7. The cardiac function was evaluated by transthoracic echocardiography including LVEF, LVFE, IVSs and IVSd. Myocardial injury was measured by Elisa for serum cTnI. The inflammation infiltration and fibrosis were evaluated by hematoxylin and eosin (HE) staining and Masson staining. The expression levels of NLRP3 inflammasome components in pyroptosis were determined by western blot, Elisa, and immunofluorescent analysis. We also detected the expression of IL-37-IL-1R8 in PBMCs by immunofluorescence after injection with CVB3 and IL-37. Compared with the VMC group, mice received CVB3 and IL-37 have improved cardiac function, reduced inflammation infiltration and fibrosis, and with lower expression of cTnI, IL-1β, IL-18 and NLRP3 inflammasome component. IL-37 weakened the upregulation of GSDMD and phosphorylation of NF-κB p65 induced by CVB3. Exogenous addition of IL-37 with CVB3 further increases the production of IL-37-IL-1R8 -IL-18RA complex in vitro. Our findings indicate that IL-37 alleviates CVB3-induced VMC, which may be produced by inhibiting NLRP3 inflammasome-mediated pyroptosis, NF-κB signaling pathway, and IL-37-IL-1R8 -IL-18RA complex.

Immuno-cardio-oncology: Killing two birds with one stone?

Inflammation and a dysregulated immune system are common denominators of cancer and cardiovascular disease (CVD). Immuno-cardio-oncology addresses the interconnected immunological aspect in both cancer and CVD and the integration of immunotherapies and anti-inflammatory therapies in both distinct disease entities. Building on prominent examples of convergent inflammation (IL-1ß biology) and immune disbalance (CD20 cells) in cancer and CVD/heart failure, the review tackles both the roadblocks and opportunities of repurposed use of IL-1ß drugs and anti-CD20 antibodies in both fields, and discusses the use of advanced therapies e.g. chimeric antigen receptor (CAR) T cells, that can address the raising burden of both cancer and CVD. Finally, it is discussed how inspired by precision medicine in oncology, the use of biomarker-driven patient stratification is needed to better guide anti-inflammatory/immunomodulatory therapeutic interventions in cardiology.

Cardiopulmonary work up of patients with and without fatigue 6 months after COVID-19

The pathogenesis of long-Covid symptoms remains incompletely understood. Therefore, we aimed to determine cardiopulmonary limitations 6 months after surviving COVID-19 using pulmonary function tests, echocardiographic studies to the point of analysis of global-longitudinal-strain (GLS), which describes the cycling myocardium deformation and provides better data on left ventricular (LV) dysfunction than LV ejection fraction (LVEF), and validated questionnaires. Overall, 60 consecutive hospitalized patients were included (61 ± 2 years, 40% treated in the ICU). At follow-up (194 ± 3 days after discharge), fatigue was the most prevalent symptom (28%). Patients with fatigue were more symptomatic overall and characterized by worse quality of life (QoL) scores compared to patients without fatigue (all p < 0.05), mainly due to limited mobility and high symptom burden. While PFT variables and LVEF were normal in the vast majority of patients (LVEF = 52% (45-52%)), GLS was significantly reduced (- 15% (- 18 to - 14%)). However, GLS values were not different between patients with and without fatigue. In conclusion, fatigue was the most prevalent long-Covid symptom in our cohort, which was associated with worse QoL mainly due to limited mobility and the high burden of concomitant symptoms. Patients showed a subtle myocardial dysfunction 6 months after surviving COVID-19, but this did not relate to the presence of fatigue.

Roles of transient receptor potential channel 6 in glucose-induced cardiomyocyte injury

BACKGROUND

Diabetic cardiomyopathy (DCM) is a serious complication of end-stage diabetes that presents symptoms such as cardiac hypertrophy and heart failure. The transient receptor potential channel 6 (TRPC6) protein is a very important selective calcium channel that is closely related to the development of various cardiomyopathies.

AIM

To explore whether TRPC6 affects cardiomyocyte apoptosis and proliferation inhibition in DCM.

METHODS

We compared cardiac function and myocardial pathological changes in wild-type mice and mice injected with streptozotocin (STZ), in addition to comparing the expression of TRPC6 and P-calmodulin-dependent protein kinase II (P-CaMKII) in them. At the same time, we treated H9C2 cardiomyocytes with high glucose and then evaluated the effects of addition of SAR, a TRPC6 inhibitor, and KN-93, a CaMKII inhibitor, to such H9C2 cells in a high-glucose environment.

RESULTS

We found that STZ-treated mice had DCM, decreased cardiac function, necrotic cardiomyocytes, and limited proliferation. Western blot and immunofluorescence were used to detect the expression levels of various appropriate proteins in the myocardial tissue of mice and H9C2 cells. Compared to those in the control group, the expression levels of the apoptosis-related proteins cleaved caspase 3 and Bax were significantly higher in the experimental group, while the expression of the proliferation-related proteins proliferating cell nuclear antigen (PCNA) and CyclinD1 was significantly lower. In vivo and in vitro, the expression of TRPC6 and P-CaMKII increased in a high-glucose environment. However, addition of inhibitors to H9C2 cells in a high-glucose environment resulted in alleviation of both apoptosis and proliferation inhibition.

CONCLUSION

The inhibition of apoptosis and proliferation of cardiomyocytes in a high-glucose environment may be closely related to activation of the TRPC6/P-CaMKII pathway.

Soluble ST2 Is a Sensitive and Specific Biomarker for Fulminant Myocarditis

Background

The aim of the study was to identify biomarkers that can facilitate early diagnosis and treatment of fulminant myocarditis (FM) in order to reduce mortality.

Methods and Results

First, the expression profiles of circulating cytokines were determined in the plasma samples from 4 patients with FM and 4 controls using human cytokine arrays. The results showed that 39 cytokines from patients with FM were changed at admission. Among them, 8 cytokines returned to normal levels at discharge, including soluble ST2 (sST2), which showed the most marked dynamic changes from disease onset to resolution. Then, in a cohort of 76 patients with FM, 57 patients with acute hemodynamic dysfunction attributable to other causes, and 56 patients with non‐FM, receiver operating characteristic curve analyses suggested that plasma sST2 level was able to differentiate FM from non‐FM or other FM‐unrelated acute heart failure more robustly N‐terminal pro‐B‐type natriuretic peptide or cardiac troponin I. Moreover, longitudinal analysis of plasma sST2 was performed in 10 patients with FM during hospitalization and 16 patients with FM during follow‐up. Finally, the diagnostic value was validated in an additional 26 patients with acute onset of unstable hemodynamics. The cutoff value of plasma sST2 for optimal diagnosis of FM was established at 58.39 ng/mL, where a sensitivity of 85.7% and specificity of 94.7% were achieved.

Conclusions

Elevated sST2 level was associated with mechanical stress or inflammation. Especially, sST2 might be used as a potential biomarker for the rapid diagnosis of FM, which was characterized by strong mechanical stretch stimulation and severe inflammatory response.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03268642.

LuQi Formula Ameliorates Myocardial Fibrosis by Suppressing TLR4/MyD88/NF-κB Pathway and NLRP3 Inflammasome Activation in Mice with Myocardial Infarction

Background

Myocardial fibrosis caused by myocardial infarction (MI) is the key factor leading to cardiac remodeling; nod-like receptor family pyrin domain-containing 3 (NLRP3) plays an important role in regulation of myocardial injury; however, its relationship with TLR4/MyD88/NF-κB signaling pathway is largely unreported. In recent years, traditional Chinese medicine (TCM) prevention and treatment of cardiovascular diseases has shown its unique advantages and broad application prospects. LuQi Formula (LQF) has been used for more than 20 years in Shuguang Hospital (Shanghai, China), and it was confirmed that it can improve the clinical symptoms of patients after MI. Here, we investigated the mechanism of LQF by suppressing NLRP3 inflammasome activation and TLR4/MyD88/NF-κB pathway in mice with MI.

Purpose

The purpose of this study was to verify the positive effects of the LQF in ameliorating myocardial fibrosis and inflammasome infiltration in the MI mice in vivo.

Methods

Forty mice were randomized into four groups: the sham group, the MI group, the LQF group, and the perindopril group (n = 10 per group). Left anterior descending (LAD) coronary artery ligation was performed in all groups except the sham group. The mice were treated with LQF after MI. After 4 weeks, LDH, cTnI, IL-1β, and IL-18 were measured by enzyme-linked immunosorbent assay (ELISA) kit, and cardiac function was evaluated by echocardiography. Hematoxylin and eosin (H&E) and Masson staining were used to evaluate the myocardial injury and fibrosis. Western blot was used to evaluate the expression of collagen I, α-SMA, NLRP3 inflammasome, and TLR4/MyD88/NF-κB signaling pathway. Immunohistochemical analysis was used to further detect the expression of Fibronectin, α-SMA, collagen I, collagen III, NLRP3, and NF-κB in myocardial tissue.

Results

Compared with the MI group, the ejection fraction (EF) and fractional shortening (FS) in the LQF group were significantly improved, while the left ventricular end diastolic diameter (LVEDd) and left ventricular internal dimension systole (LVIDs) were significantly decreased. The representative staining of H&E and Masson showed that treatment with LQF could effectively reduce myocardial injury and fibrosis. ELISA results showed that serum LDH, cTnI, TNF-α, IL-18, and IL-1β in LQF group were significantly lower than those in MI group. The western blot results showed that the expressions of collagen I and α-SMA were decreased significantly in the LQF group. Moreover, the expressions of NLRP3 inflammasome and TLR4/MyD88/NF-κB signaling pathway were downregulated in the LQF treatment group.

Conclusion

Our results suggested that LQF could significantly improve cardiac function and ameliorate myocardial fibrosis. In addition, we found that LQF could downregulate the TLR4/MyD88/NF-κB signaling pathway and then inhibit the activation of NLRP3 inflammasome, suggesting that LQF alleviated cardiac fibrosis by decreasing the TLR4/MyD88/NF-κB signaling pathway and then inhibited NLRP3 inflammasome activation in MI mice, which indicates potential therapeutic effect of LQF on patients with MI.

Clinical characteristics and outcome of biopsy-proven myocarditis in children - Results of the German prospective multicentre registry "MYKKE"

BACKGROUND

Heart failure (HF) due to myocarditis might not respond in the same way to standard therapy as HF due to other aetiologies. The aim of this study was to investigate the value of endomyocardial biopsies (EMB) for clinical decision-making and its relation to the outcome of paediatric patients with myocarditis.

METHODS

Clinical and EMB data of children with myocarditis collected for the MYKKE-registry between 2013 and 2020 from 23 centres were analysed. EMB studies included histology, immunohistology, and molecular pathology. The occurrence of major adverse cardiac events (MACE) including mechanical circulatory support (MCS), heart transplantation, and/or death was defined as a combined endpoint.

RESULTS

Myocarditis was diagnosed in 209/260 patients: 64% healing/chronic lymphocytic myocarditis, 23% acute lymphocytic myocarditis (AM), 14% healed myocarditis, no giant cell myocarditis. The median age was 12.8 (1.4-15.9) years. Time from symptom-onset to EMB was 11.0 (4.0-29.0) days. Children with AM and high amounts of mononuclear cell infiltrates were significantly younger with signs of HF compared to those with healing/chronic or healed myocarditis. Myocardial viral DNA/RNA detection had no significant effect on outcome. The worst event-free survival was seen in patients with healing/chronic myocarditis (24%), followed by acute (31%) and healed myocarditis (58%, p = 0.294). A weaning rate of 64% from MCS was found in AM.

CONCLUSIONS

EMB provides important information on the type and stage of myocardial inflammation and supports further decision-making. Children with fulminant clinical presentation, high amounts of mononuclear cell infiltrates or healing/chronic inflammation and young age have the highest risk for MACE.

Fulminant myocarditis in adults: a narrative review

Fulminant myocarditis (FM) is an uncommon syndrome characterized by sudden and severe hemodynamic compromise secondary to acute myocardial inflammation, often presenting as profound cardiogenic shock, life-threatening ventricular arrhythmias and/or electrical storm. FM may be refractory to conventional therapies and require mechanical circulatory support (MCS). The immune system has been recognized as playing a pivotal role in the pathophysiology of myocarditis, leading to an increased focus on immunosuppressive treatment strategies. Recent data have highlighted not only the fact that FM has significantly worse outcomes than non-FM, but that prognosis and management strategies of FM are heavily dependent on histological subtype, placing greater emphasis on the role of endomyocardial biopsy in diagnosis. The impact of subtype on severity and prognosis will likewise influence how aggressively the myocarditis is managed, including whether MCS is warranted. Many patients with refractory cardiogenic shock secondary to FM end up requiring MCS, with venoarterial extracorporeal membrane oxygenation demonstrating favorable survival rates, particularly when initiated prior to the development of multiorgan failure. Among the challenges facing the field are the need to more precisely identify immunopathophysiological pathways in order to develop targeted therapies, and the need to better optimize the timing and management of MCS to minimize complications and maximize outcomes.

Cellular Phenotypic Transformation in Heart Failure Caused by Coronary Heart Disease and Dilated Cardiomyopathy: Delineating at Single-Cell Level

Heart failure (HF) is known as the final manifestation of cardiovascular diseases. Although cellular heterogeneity of the heart is well understood, the phenotypic transformation of cardiac cells in progress of HF remains obscure. This study aimed to analyze phenotypic transformation of cardiac cells in HF through human single-cell RNA transcriptome profile. Here, phenotypic transformation of cardiomyocytes (CMs), endothelial cells (ECs), and fibroblasts was identified by data analysis and animal experiments. Abnormal myosin subunits including the decrease in Myosin Heavy Chain 6, Myosin Light Chain 7 and the increase in Myosin Heavy Chain 7 were found in CMs. Two disease phenotypes of ECs named inflammatory ECs and muscularized ECs were identified. In addition, myofibroblast was increased in HF and highly associated with abnormal extracellular matrix. Our study proposed an integrated map of phenotypic transformation of cardiac cells and highlighted the intercellular communication in HF. This detailed definition of cellular transformation will facilitate cell-based mapping of novel interventional targets for the treatment of HF.

Cardiac Magnetic Resonance Imaging Findings in 2954 COVID-19 Adult Survivors: A Comprehensive Systematic Review

Background

Recent studies have utilized MRI to determine the extent to which COVID‐19 survivors may experience cardiac sequels after recovery.

Purpose

To systematically review the main cardiac MRI findings in COVID‐19 adult survivors.

Study type

Systematic review.

Subjects

A total of 2954 COVID‐19 adult survivors from 16 studies.

Field Strength/sequence

Late gadolinium enhancement (LGE), parametric mapping (T1‐native, T2, T1‐post (extracellular volume fraction [ECV]), T2‐weighted sequences (myocardium/pericardium), at 1.5 T and 3  T.

Assessment

A systematic search was performed on PubMed, Embase, and Google scholar databases using Boolean operators and the relevant key terms covering COVID‐19, cardiac injury, CMR, and follow‐up. MRI data, including (if available) T1, T2, extra cellular volume, presence of myocardial or pericardial late gadolinium enhancement (LGE) and left and right ventricular ejection fraction were extracted.

Statistical Tests

The main results of the included studies are summarized. No additional statistical analysis was performed.

Results

Of 1601 articles retrieved from the initial search, 12 cohorts and 10 case series met our eligibility criteria. The rate of raised T1 in COVID‐19 adult survivors varied across studies from 0% to 73%. Raised T2 was detected in none of patients in 4 out of 15 studies, and in the remaining studies, its rate ranged from 2% to 60%. In most studies, LGE (myocardial or pericardial) was observed in COVID‐19 survivors, the rate ranging from 4% to 100%. Myocardial LGE mainly had nonischemic patterns. None of the cohort studies observed myocardial LGE in “healthy” controls. Most studies found that patients who recovered from COVID‐19 had a significantly greater T1 and T2 compared to participants in the corresponding control group.

Data Conclusion

Findings of MRI studies suggest the presence of myocardial and pericardial involvement in a notable number of patients recovered from COVID‐19.

Level of Evidence

3

Technical Efficacy Stage

3

Pathogenesis of arrhythmogenic cardiomyopathy: role of inflammation

Arrhythmogenic cardiomyopathy (AC) is an inherited disease characterized by progressive breakdown of heart muscle, myocardial tissue death, and fibrofatty replacement. In most cases of AC, the primary lesion occurs in one of the genes encoding desmosomal proteins, disruption of which increases membrane fragility at the intercalated disc. Disrupted, exposed desmosomal proteins also serve as epitopes that can trigger an autoimmune reaction. Damage to cell membranes and autoimmunity provoke myocardial inflammation, a key feature in early stages of the disease. In several preclinical models, targeting inflammation has been shown to blunt disease progression, but translation to the clinic has been sparse. Here we review current understanding of inflammatory pathways and how they interact with injured tissue and the immune system in AC. We further discuss the potential role of immunomodulatory therapies in AC.

Toll-Like Receptors: Are They Taking a Toll on the Heart in Viral Myocarditis?

Myocarditis is an inflammatory disease of the heart with viral infections being the most common aetiology. Its complex biology remains poorly understood and its clinical management is one of the most challenging in the field of cardiology. Toll-like receptors (TLRs), a family of evolutionarily conserved pattern recognition receptors, are increasingly known to be implicated in the pathophysiology of viral myocarditis. Their central role in innate and adaptive immune responses, and in the inflammatory reaction that ensues, indeed makes them prime candidates to profoundly affect every stage of the disease process. This review describes the pathogenesis and pathophysiology of viral myocarditis, and scrutinises the role of TLRs in every phase. We conclude with directions for future research in this field.

Sex Differences, Genetic and Environmental Influences on Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is characterized by dilatation of the left ventricle and impaired systolic function and is the second most common cause of heart failure after coronary heart disease. The etiology of DCM is diverse including genetic pathogenic variants, infection, inflammation, autoimmune diseases, exposure to chemicals/toxins as well as endocrine and neuromuscular causes. DCM is inherited in 20–50% of cases where more than 30 genes have been implicated in the development of DCM with pathogenic variants in TTN (Titin) most frequently associated with disease. Even though male sex is a risk factor for heart failure, few studies have examined sex differences in the pathogenesis of DCM. We searched the literature for studies examining idiopathic or familial/genetic DCM that reported data by sex in order to determine the sex ratio of disease. We found 31 studies that reported data by sex for non-genetic DCM with an average overall sex ratio of 2.5:1 male to female and 7 studies for familial/genetic DCM with an overall average sex ratio of 1.7:1 male to female. No manuscripts that we found had more females than males in their studies. We describe basic and clinical research findings that may explain the increase in DCM in males over females based on sex differences in basic physiology and the immune and fibrotic response to damage caused by mutations, infections, chemotherapy agents and autoimmune responses.

Cardiac Involvement in Recovered Patients From COVID-19: A Preliminary 6-Month Follow-Up Study

Background: Accumulating evidence has revealed that coronavirus disease 2019 (COVID-19) patients may be complicated with myocardial injury during hospitalization. However, data regarding persistent cardiac involvement in patients who recovered from COVID-19 are limited. Our goal is to further explore the sustained impact of COVID-19 during follow-up, focusing on the cardiac involvement in the recovered patients. Methods: In this prospective observational follow-up study, we enrolled a total of 40 COVID-19 patients (20 with and 20 without cardiac injury during hospitalization) who were discharged from Zhongnan Hospital of Wuhan University for more than 6 months, and 27 patients (13 with and 14 without cardiac injury during hospitalization) were finally included in the analysis. Clinical information including self-reported symptoms, medications, laboratory findings, Short Form 36-item scores, 6-min walk test, clinical events, electrocardiogram assessment, echocardiography measurement, and cardiac magnetic resonance imaging was collected and analyzed. Results: Among 27 patients finally included, none of patients reported any obvious cardiopulmonary symptoms at the 6-month follow-up. There were no statistically significant differences in terms of the quality of life and exercise capacity between the patients with and without cardiac injury. No significant abnormalities were detected in electrocardiogram manifestations in both groups, except for nonspecific ST-T changes, premature beats, sinus tachycardia/bradycardia, PR interval prolongation, and bundle-branch block. All patients showed normal cardiac structure and function, without any statistical differences between patients with and without cardiac injury by echocardiography. Compared with patients without cardiac injury, patients with cardiac injury exhibited a significantly higher positive proportion in late gadolinium enhancement sequences [7/13 (53.8%) vs. 1/14 (7.1%), p = 0.013], accompanied by the elevation of circulating ST2 level [median (interquartile range) = 16.6 (12.1, 22.5) vs. 12.5 (9.5, 16.7); p = 0.044]. Patients with cardiac injury presented higher levels of aspartate aminotransferase, creatinine, high-sensitivity troponin I, lactate dehydrogenase, and N-terminal pro-B-type natriuretic peptide than those without cardiac injury, although these indexes were within the normal range for all recovered patients at the 6-month follow-up. Among patients with cardiac injury, patients with positive late gadolinium enhancement presented higher cardiac biomarker (high-sensitivity troponin I) and inflammatory factor (high-sensitivity C-reactive protein) on admission than the late gadolinium enhancement-negative subgroup. Conclusions: Our preliminary 6-month follow-up study with a limited number of patients revealed persistent cardiac involvement in 29.6% (8/27) of recovered patients from COVID-19 after discharge. Patients with cardiac injury during hospitalization were more prone to develop cardiac fibrosis during their recovery. Among patients with cardiac injury, those with relatively higher cardiac biomarkers and inflammatory factors on admission appeared more likely to have cardiac involvement in the convalescence phase.

Myeloid-Derived Suppressor Cells Restrain Natural Killer Cell Activity in Acute Coxsackievirus B3-Induced Myocarditis

Murine models of coxsackievirus B3 (CVB3)-induced myocarditis well represent the different outcomes of this inflammatory heart disease. Previously, we found that CVB3-infected A.BY/SnJ mice, susceptible for severe acute and chronic myocarditis, have lower natural killer (NK) cell levels than C57BL/6 mice, with mild acute myocarditis. There is evidence that myeloid-derived suppressor cells (MDSC) may inhibit NK cells, influencing the course of myocarditis. To investigate the MDSC/NK interrelationship in acute myocarditis, we used CVB3-infected A.BY/SnJ mice. Compared to non-infected mice, we found increased cell numbers of MDSC in the spleen and heart of CVB3-infected A.BY/SnJ mice. In parallel, S100A8 and S100A9 were increased in the heart, spleen, and especially in splenic MDSC cells compared to non-infected mice. In vitro experiments provided evidence that MDSC disrupt cytotoxic NK cell function upon co-culturing with MDSC. MDSC-specific depletion by an anti-Ly6G antibody led to a significant reduction in the virus load and injury in hearts of infected animals. The decreased cardiac damage in MDSC-depleted mice was associated with fewer Mac3⁺ macrophages and CD3⁺ T lymphocytes and a reduced cardiac expression of S100A8, S100A9, IL-1β, IL-6, and TNF-α. In conclusion, impairment of functional NK cells by MDSC promotes the development of chronic CVB3 myocarditis in A.BY/SnJ mice.

The innate immune response in myocarditis

Acute myocarditis is an inflammatory condition of the heart characterised by cellular injury and the influx of leucocytes, including neutrophils, monocytes, macrophages and lymphocytes. While this response is vital for tissue repair, excessive scar deposition and maladaptive ventricular remodelling can result in a legacy of heart failure. It is increasingly recognised as a clinical phenomenon due, in part, to increased availability of cardiac magnetic resonance imaging in patients presenting with chest pain in the absence of significant coronary artery disease. Emerging epidemiological evidence has associated myocarditis with poor outcomes in the context of left ventricular impairment, and even when the left ventricle is preserved outcomes are less benign than once thought. Despite this, our understanding of the contribution of the inflammatory response to the pathophysiology of acute myocarditis lags behind that of acute myocardial infarction, which is the vanguard cardiovascular condition for inflammation research. We recently reviewed monocyte and macrophage phenotype and function in acute myocardial infarction, concluding that their plasticity and heterogeneity might account for conflicting evidence from attempts to target specific leucocyte subpopulations. Here, we revise our understanding of myocardial inflammation, which is predominantly derived from myocardial infarction research, review experimental evidence for the immune response in acute myocarditis, focusing on innate immunity, and discuss potential future directions for immunotherapy research in acute myocarditis.

Metformin attenuates post-epidural fibrosis by inhibiting the TGF-β1/Smad3 and HMGB1/TLR4 signaling pathways

Excessive post‐epidural fibrosis is a common cause of recurrent back pain after spinal surgery. Though various treatment methods have been conducted, the safe and effective drug for alleviating post‐epidural fibrosis remains largely unknown. Metformin, a medicine used in the treatment of type 2 diabetes, has been noted to relieve fibrosis in various organs. In the present study, we aimed to explore the roles and mechanisms of metformin in scar formation in a mouse model of laminectomy. Post‐epidural fibrosis developed in a mouse model of laminectomy by spinous process and the T12‐L2 vertebral plate with a rongeur. With the administration of metformin, post‐epidural fibrosis was reduced, accompanied with decreased collagen and fibronectin in the scar tissues. Mechanistically, metformin decreased fibronectin and collagen deposition in fibroblast cells, and this effect was dependent on the HMGB1/TLR4 and TGF‐β1/Smad3 signalling pathways. In addition, metformin influenced the metabolomics of the fibroblast cells. Taken together, our study suggests that metformin may be a potential option to mitigate epidural fibrosis after laminectomy.

Cholinergic modulation of the immune system - A novel therapeutic target for myocardial inflammation

The immune system and the nervous system depend on each other for their fine tuning and working, thus cooperating to maintain physiological homeostasis and prevent infections. The cholinergic system regulates the mobilization, differentiation, secretion, and antigen presentation of adaptive and innate immune cells mainly through α7 nicotinic acetylcholine receptors (α7nAChRs). The neuro-immune interactions are established and maintained by the following mechanisms: colocalization of immune and neuronal cells at defined anatomical sites, expression of the non-neuronal cholinergic system by immune cells, and the acetylcholine receptor-mediated activation of intracellular signaling pathways. Based on these immunological mechanisms, the protective effects of cholinergic system in animal models of diseases were summarized in this paper, such as myocardial infarction/ischemia-reperfusion, viral myocarditis, and endotoxin-induced myocardial damage. In addition to maintaining hemodynamic stability and improving the energy metabolism of the heart, both non-neuronal acetylcholine and neuronal acetylcholine in the heart can alleviate myocardial inflammation and remodeling to exert a significant cardioprotective effect. The new findings on the role of cholinergic agonists and vagus nerve stimulation in immune regulation are updated, so as to develop improved approaches to treat inflammatory heart disease.

Involvement of ROS/NLRP3 Inflammasome Signaling Pathway in Doxorubicin-Induced Cardiotoxicity

Doxorubicin (Dox) is widely used in cancer therapy, but the clinical application is limited by its cardiotoxicity. The underlying mechanism of Dox-induced cardiotoxicity remains unclear. Present study aimed to evaluate the role of NLRP3 inflammasome in Dox-induced cardiotoxicity. The NLRP3 inflammasome was activated in the myocardium of Dox-treating (5 mg/kg, once every other day, cumulative dosage to 15 mg/kg and sacrificed after 2 days of last Dox injection) C57BL/6 mice as shown by the up-regulation of NLRP3 and Caspase-1 p20. Dox (1 μM for 48 h) induced the apoptosis of H9c2 cells and primary cardiomyocytes concomitantly with up-regulation of NLRP3, ASC and Caspase-1 p20 expressions, as well as the increased IL-1β secretion, suggesting the activation of NLRP3 inflammasome. These effects of Dox on H9c2 cells and primary cardiomyocytes can be reversed by MCC950, a specific inhibitor of NLRP3. In view of the key role of ROS on the Dox-induced cardiotoxicity, the relationship between ROS and NLRP3 was further investigated. The ROS level was increased in myocardium, H9c2 cells and primary cardiomyocytes after treating with Dox. Decreasing ROS level by NAC can inhibit the NLRP3 inflammasome activation, secretion of IL-1β and apoptosis in Dox-treating H9c2 cells and primary cardiomyocytes. Collectively, this study reveals a crucial role of ROS/NLRP3-associated inflammasome activation in Dox-induced cardiotoxicity, and NLRP3 inflammasome may represent a new therapeutic target for Dox-induced cardiotoxicity.

Pharmacological Modulation of Cardiac Remodeling after Myocardial Infarction

Cardiac remodeling describes a series of structural and functional changes in the heart after myocardial infarction (MI). Adverse post-MI cardiac remodeling directly jeopardizes the recovery of cardiac functions and the survival rate in MI patients. Several classes of drugs are proven to be useful to reduce the mortality of MI patients. However, it is an ongoing challenge to prevent the adverse effects of cardiac remodeling. The present review aims to identify the pharmacological therapies from the existing clinical drugs for the treatment of adverse post-MI cardiac remodeling. Post-MI cardiac remodeling is a complex process involving ischemia/reperfusion, inflammation, cell death, and deposition of extracellular matrix (ECM). Thus, the present review included two parts: (1) to examine the basic pathophysiology in the cardiovascular system and the molecular basis of cardiac remodeling and (2) to identify the pathological aspects of cardiac remodeling and the potential of the existing pharmacotherapies. Ultimately, the present review highlights drug repositioning as a strategy to discover effective therapies from the existing drugs against post-MI cardiac remodeling.

Fulminant myocarditis: a comprehensive review from etiology to treatments and outcomes

Fulminant myocarditis (FM) is characterized by a rapid progressive decline in cardiac function and a high mortality rate. Since the first report of FM patients in the 1980s, several clinical trials and research studies have been published increasing our knowledge regarding FM. Currently, the diagnosis of FM depends on various techniques including electrocardiography, echocardiography, endomyocardial biopsy, and cardiac magnetic resonance. The development of mechanical circulation support (MCS) devices and progress in our understanding of the pathophysiological mechanisms underlying FM, treatment regimens have evolved from simple symptomatic treatment to a life support-based comprehensive treatment approach. The core mechanism underlying the development of FM is the occurrence of an inflammatory cytokine storm. This review provides a comprehensive account of the current understanding of FM pathophysiology and knowledge regarding its etiology, pathophysiology, treatments, and outcomes.

Total Glucosides of Peony Protect Cardiomyocytes against Oxidative Stress and Inflammation by Reversing Mitochondrial Dynamics and Bioenergetics

Total glucosides of peony (TGP) are used to treat rheumatoid arthritis and systemic lupus erythematosus. We explored the protective effects of TGP on cardiomyocyte oxidative stress and inflammation in the presence of hydrogen peroxide by focusing on mitochondrial dynamics and bioenergetics. Our study demonstrated that hydrogen peroxide significantly repressed cardiomyocyte viability and promoted cell apoptosis through induction of the mitochondrial death pathway. TGP treatment sustained cardiomyocyte viability, reduced cardiomyocyte apoptosis, and decreased inflammation and oxidative stress. Molecular investigation indicated that hydrogen peroxide caused mitochondrial dynamics disruption and bioenergetics reduction in cardiomyocytes, but this alteration could be normalized by TGP. We found that disruption of mitochondrial dynamics abolished the regulatory effects of TGP on mitochondrial bioenergetics; TGP modulated mitochondrial dynamics through the AMP-activated protein kinase (AMPK) pathway; and inhibition of AMPK alleviated the protective effects of TGP on mitochondria. Our results showed that TGP treatment reduces cardiomyocyte oxidative stress and inflammation in the presence of hydrogen peroxide by correcting mitochondrial dynamics and enhancing mitochondrial bioenergetics. Additionally, the regulatory effects of TGP on mitochondrial function seem to be mediated through the AMPK pathway. These findings are promising for myocardial injury in patients with rheumatoid arthritis and systemic lupus erythematosus.

Adding insult to injury - Inflammation at the heart of cardiac fibrosis

The fibrotic response has evolutionary worked in tandem with the inflammatory response to facilitate healing following injury or tissue destruction as a result of pathogen clearance. However, excessive inflammation and fibrosis are key pathological drivers of organ tissue damage. Moreover, fibrosis can occur in several conditions associated with chronic inflammation that are not directly caused by overt tissue injury or infection. In the heart, in particular, fibrotic adverse cardiac remodeling is a key pathological driver of cardiac dysfunction in heart failure. Cardiac fibroblast activation and immune cell activation are two mechanistic domains necessary for fibrotic remodeling in the heart, and, independently, their contributions to cardiac fibrosis and cardiac inflammation have been studied and reviewed thoroughly. The interdependence of these two processes, and how their cellular components modulate each other's actions in response to different cardiac insults, is only recently emerging. Here, we review recent literature in cardiac fibrosis and inflammation and discuss the mechanisms involved in the fibrosis-inflammation axis in the context of specific cardiac stresses, such as myocardial ischemia, and in nonischemic heart conditions. We discuss how the search for anti-inflammatory and anti-fibrotic therapies, so far unsuccessful to date, needs to be based on our understanding of the interdependence of immune cell and fibroblast activities. We highlight that in addition to the extensively reviewed role of immune cells modulating fibroblast function, cardiac fibroblasts are central participants in inflammation that may acquire immune like cell functions. Lastly, we review the gut-heart axis as an example of a novel perspective that may contribute to our understanding of how immune and fibrotic modulation may be indirectly modulated as a potential area for therapeutic research.

Cardiac fibrosis

Myocardial fibrosis, the expansion of the cardiac interstitium through deposition of extracellular matrix proteins, is a common pathophysiologic companion of many different myocardial conditions. Fibrosis may reflect activation of reparative or maladaptive processes. Activated fibroblasts and myofibroblasts are the central cellular effectors in cardiac fibrosis, serving as the main source of matrix proteins. Immune cells, vascular cells and cardiomyocytes may also acquire a fibrogenic phenotype under conditions of stress, activating fibroblast populations. Fibrogenic growth factors (such as transforming growth factor-β and platelet-derived growth factors), cytokines [including tumour necrosis factor-α, interleukin (IL)-1, IL-6, IL-10, and IL-4], and neurohumoral pathways trigger fibrogenic signalling cascades through binding to surface receptors, and activation of downstream signalling cascades. In addition, matricellular macromolecules are deposited in the remodelling myocardium and regulate matrix assembly, while modulating signal transduction cascades and protease or growth factor activity. Cardiac fibroblasts can also sense mechanical stress through mechanosensitive receptors, ion channels and integrins, activating intracellular fibrogenic cascades that contribute to fibrosis in response to pressure overload. Although subpopulations of fibroblast-like cells may exert important protective actions in both reparative and interstitial/perivascular fibrosis, ultimately fibrotic changes perturb systolic and diastolic function, and may play an important role in the pathogenesis of arrhythmias. This review article discusses the molecular mechanisms involved in the pathogenesis of cardiac fibrosis in various myocardial diseases, including myocardial infarction, heart failure with reduced or preserved ejection fraction, genetic cardiomyopathies, and diabetic heart disease. Development of fibrosis-targeting therapies for patients with myocardial diseases will require not only understanding of the functional pluralism of cardiac fibroblasts and dissection of the molecular basis for fibrotic remodelling, but also appreciation of the pathophysiologic heterogeneity of fibrosis-associated myocardial disease.

Neutrophil peptide-1 promotes the repair of sciatic nerve injury through the expression of proteins related to nerve regeneration

Objectives Small-molecule polypeptide neutrophil peptide 1 (NP-1) was reported to promote the regeneration of the sciatic nerve after denervation, but the mechanisms underlying this effect of NP-1 are unclear. Here, we established a Sprague-Dawley rat model of crush injury to study the effect of a single intermuscular injection of NP-1 on the repair of injured peripheral nerves and elucidate the possible underlying mechanism.Methods 39 rats were randomly selected to join this study and divided into the blank control group (normal group, n=9), experimental group (NP-1 group, n=15), and negative control group (NS group, n=15). The dynamic expression of cytokines in different groups of nerve tissues during Wallerian degeneration was observed using protein chips at different time points after injury. Recovery of injured nerves was determined based on the general condition, local gross morphology of the nerve suture site, sciatic nerve function index, neuroelectrophysiology, and osmic acid staining at 6 weeks after the surgery. The recovery of effector function was determined based on wet weight, hematoxylin-eosin staining, modified Gomori staining, and nicotinamide adenine dinucleotide-tetrazolium reductase staining at 6 weeks after the surgery.Results It was found that a single topical administration of NP-1 promoted sciatic nerve regeneration after crush injury and affected the expression of proteins related to neurotrophy, inflammation, cell chemotaxis, and cell generation pathways.

Myocarditis and inflammatory cardiomyopathy: current evidence and future directions

Inflammatory cardiomyopathy, characterized by inflammatory cell infiltration into the myocardium and a high risk of deteriorating cardiac function, has a heterogeneous aetiology. Inflammatory cardiomyopathy is predominantly mediated by viral infection, but can also be induced by bacterial, protozoal or fungal infections as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Despite extensive research, inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. At present, the reason why some patients recover without residual myocardial injury whereas others develop dilated cardiomyopathy is unclear. The relative roles of the pathogen, host genomics and environmental factors in disease progression and healing are still under discussion, including which viruses are active inducers and which are only bystanders. As a consequence, treatment strategies are not well established. In this Review, we summarize and evaluate the available evidence on the pathogenesis, diagnosis and treatment of myocarditis and inflammatory cardiomyopathy, with a special focus on virus-induced and virus-associated myocarditis. Furthermore, we identify knowledge gaps, appraise the available experimental models and propose future directions for the field. The current knowledge and open questions regarding the cardiovascular effects associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also discussed. This Review is the result of scientific cooperation of members of the Heart Failure Association of the ESC, the Heart Failure Society of America and the Japanese Heart Failure Society.

SERCA Overexpression Improves Mitochondrial Quality Control and Attenuates Cardiac Microvascular Ischemia-Reperfusion Injury

Despite significant advances in the treatment of myocardial ischemia-reperfusion (I/R) injury, coronary circulation is a so far neglected target of cardioprotection. In this study, we investigated the molecular mechanisms underlying I/R injury to cardiac microcirculation. Using gene delivery, we analyzed microvascular protective effects of sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) on the reperfused heart and examined the role of SERCA in regulating mitochondrial quality control in cardiac microvascular endothelial cells (CMECs). Our data showed that SERCA overexpression attenuates lumen stenosis, inhibits microthrombus formation, reduces inflammation response, and improves endothelium-dependent vascular relaxation. In vitro experiments demonstrated that SERCA overexpression improves endothelial viability, barrier integrity, and cytoskeleton assembly in CMECs. Mitochondrial quality control, including mitochondrial fusion, mitophagy, bioenergetics, and biogenesis, were disrupted by I/R injury but were restored by SERCA overexpression. SERCA overexpression also restored mitochondrial quality control by inhibiting calcium overload, inactivating xanthine oxidase (XO), and reducing intracellular/mitochondrial reactive oxygen species (ROS). Administration of exogenous XO or a calcium channel agonist abolished the protective effects of SERCA overexpression on mitochondrial quality control and offset the beneficial effects of SERCA overexpression after cardiac microvascular I/R injury. These findings indicate that SERCA overexpression may be an effective approach to targeting cardiac microvascular I/R injury by regulating calcium/XO/ROS signaling and preserving mitochondrial quality control.

SirT3 activates AMPK-related mitochondrial biogenesis and ameliorates sepsis-induced myocardial injury

Sirtuin-3 (SirT3) and AMPK stimulate mitochondrial biogenesis, which increases mitochondrial turnover and cardiomyocyte regeneration. We studied the effects of SirT3, AMPK, and mitochondrial biogenesis on sepsis-induced myocardial injury. Our data showed that after treating cardiomyocytes with lipopolysaccharide, SirT3 and AMPK levels decreased, and this was followed by mitochondrial dysfunction and cardiomyocyte death. Overexpression of SirT3 activated the AMPK pathway and improved mitochondrial biogenesis, which is required to sustain mitochondrial redox balance, maintain mitochondrial respiration, and suppress mitochondrial apoptosis. Inhibition of mitochondrial biogenesis abolished SirT3/AMPK-induced cardioprotection by causing mitochondrial damage. These findings indicate that SirT3 reduces sepsis-induced myocardial injury by activating AMPK-related mitochondrial biogenesis.

Modulation of the acute defence reaction by eplerenone prevents cardiac disease progression in viral myocarditis

Aims

Left ventricular (LV) dysfunction in viral myocarditis is attributed to myocardial inflammation and fibrosis, inducing acute and long‐time cardiac damage. Interventions are not established. On the basis of the link between inflammation, fibrosis, aldosterone, and extracellular matrix regulation, we aimed to investigate the effect of an early intervention with the mineralocorticoid receptor antagonist (MRA) eplerenone on cardiac remodelling in a murine model of persistent coxsackievirus B3 (CVB3)‐induced myocarditis.

Methods and results

SWR/J mice were infected with 5 × 10⁴ plaque‐forming units of CVB3 (Nancy strain) and daily treated either with eplerenone (200 mg/kg body weight) or with placebo starting from Day 1. At Day 8 or 28 post infection, mice were haemodynamically characterized and subsequently sacrificed for immunohistological and molecular biology analyses. Eplerenone did not influence CVB3 load. Already at Day 8, 1.8‐fold (P < 0.05), 1.4‐fold (P < 0.05), 3.2‐fold (P < 0.01), and 2.1‐fold (P < 0.001) reduction in LV intercellular adhesion molecule 1 expression, presence of monocytes/macrophages, oxidative stress, and apoptosis, respectively, was observed in eplerenone‐treated vs. untreated CVB3‐infected mice. In vitro, eplerenone led to 1.4‐fold (P < 0.01) and 1.2‐fold (P < 0.01) less CVB3‐induced cardiomyocyte oxidative stress and apoptosis. Furthermore, collagen production was 1.1‐fold (P < 0.05) decreased in cardiac fibroblasts cultured with medium of eplerenone‐treated vs. untreated CVB3‐infected HL‐1 cardiomyocytes. These ameliorations were in vivo translated into prevention of cardiac fibrosis, as shown by 1.4‐fold (P < 0.01) and 2.1‐fold (P < 0.001) lower collagen content in the LV of eplerenone‐treated vs. untreated CVB3‐infected mice at Days 8 and 28, respectively. This resulted in an early and long‐lasting improvement of LV dimension and function, as indicated by reduced LV end‐systolic volume and end‐diastolic volume, and an increase in LV contractility (dP/dt_max) and LV relaxation (dP/dt_min), respectively (P < 0.05).

Conclusions

Early intervention with the MRA eplerenone modulates the acute host and defence reaction and prevents cardiac disease progression in experimental CVB3‐induced myocarditis without aggravation of viral load. The findings advocate for an initiation of therapy of viral myocarditis as early as possible, even before the onset of inflammation‐induced myocardial dysfunction. This may also have implications for coronavirus disease‐19 therapy.