Deficiency of mouse mast cell protease 4 mitigates cardiac dysfunctions in mice after myocardium infarction

Mast Cells in Cardiac Remodeling: Focus on the Right Ventricle

In response to various stressors, cardiac chambers undergo structural remodeling. Long-term exposure of the right ventricle (RV) to pressure or volume overload leads to its maladaptive remodeling, associated with RV failure and increased mortality. While left ventricular adverse remodeling is well understood and therapeutic options are available or emerging, RV remodeling remains underexplored, and no specific therapies are currently available. Accumulating evidence implicates the role of mast cells in RV remodeling. Mast cells produce and release numerous inflammatory mediators, growth factors and proteases that can adversely affect cardiac cells, thus contributing to cardiac remodeling. Recent experimental findings suggest that mast cells might represent a potential therapeutic target. This review examines the role of mast cells in cardiac remodeling, with a specific focus on RV remodeling, and explores the potential efficacy of therapeutic interventions targeting mast cells to mitigate adverse RV remodeling.

Is chymase 1 a therapeutic target in cardiovascular disease?

INTRODUCTION

Non-angiotensin converting enzyme mechanisms of angiotensin II production remain underappreciated in part due to the success of current therapies to ameliorate the impact of primary hypertension and atherosclerotic diseases of the heart and the blood vessels. This review scrutinize the current literature to highlight chymase role as a critical participant in the pathogenesis of cardiovascular disease and heart failure.

AREAS COVERED

We review the contemporaneous understanding of circulating and tissue biotransformation mechanisms of the angiotensins focusing on the role of chymase as an alternate tissue generating pathway for angiotensin II pathological mechanisms of action.

EXPERT OPINION

While robust literature documents the singularity of chymase as an angiotensin II-forming enzyme, particularly when angiotensin converting enzyme is inhibited, this knowledge has not been fully recognized to clinical medicine. This review discusses the limitations of clinical trials' that explored the benefits of chymase inhibition in accounting for the failure to duplicate in humans what has been demonstrated in experimental animals.

Pathophysiological Role of Chymase-Activated Matrix Metalloproteinase-9

Chymase present in mast cells can directly form matrix metalloproteinase (MMP)-9 from proMMP-9. Chymase-activated MMP-9 has been reportedly closely related to the pathogenesis of various diseases, and inflammation-related diseases in particular. Upregulated chymase and MMP-9 have been observed in tissues from patients and animal models of aortic aneurysm, inflammatory gastrointestinal and hepatic diseases, acute pancreatic failure, atopic dermatitis and rheumatoid arthritis. Chymase at these regions is only derived from mast cells, while MMP-9 is derived from macrophages and neutrophils in addition to mast cells. Chymase inhibitors attenuate MMP-9 formation from pro-MMP-9, and ameliorate the development and progression of these disorders, along with reduction in inflammatory cell numbers. MMP-9 activated by chymase might also be involved in angiogenesis in the tumor environment. Development of angiogenesis around several cancers is closely related to the expression of chymase and MMP-9, and postoperative survival curves have revealed that patients with a higher number of chymase positive cells have lower survival rates. In this review, we wanted to clarify the role of chymase-activated MMP-9, which might become an important therapeutic target for various inflammatory disorders.

Mast Cells Induce Ductular Reaction Mimicking Liver Injury in Mice Through Mast Cell-Derived Transforming Growth Factor Beta 1 Signaling

BACKGROUND AND AIMS

Following liver injury, mast cells (MCs) migrate into the liver and are activated in patients with cholestasis. Inhibition of MC mediators decreases ductular reaction (DR) and liver fibrosis. Transforming growth factor beta 1 (TGF-β1) contributes to fibrosis and promotes liver disease. Our aim was to demonstrate that reintroduction of MCs induces cholestatic injury through TGF-β1.

APPROACH AND RESULTS

Wild-type, Kit^W-sh (MC-deficient), and multidrug resistance transporter 2/ABC transporter B family member 2 knockout mice lacking l-histidine decarboxylase were injected with vehicle or PKH26-tagged murine MCs pretreated with 0.01% dimethyl sulfoxide (DMSO) or the TGF-β1 receptor inhibitor (TGF-βRi), LY2109761 (10 μM) 3 days before sacrifice. Hepatic damage was assessed by hematoxylin and eosin (H&E) and serum chemistry. Injected MCs were detected in liver, spleen, and lung by immunofluorescence (IF). DR was measured by cytokeratin 19 (CK-19) immunohistochemistry and F4/80 staining coupled with real-time quantitative PCR (qPCR) for interleukin (IL)-1β, IL-33, and F4/80; biliary senescence was evaluated by IF or qPCR for p16, p18, and p21. Fibrosis was evaluated by sirius red/fast green staining and IF for synaptophysin 9 (SYP-9), desmin, and alpha smooth muscle actin (α-SMA). TGF-β1 secretion/expression was measured by enzyme immunoassay and qPCR. Angiogenesis was detected by IF for von Willebrand factor and vascular endothelial growth factor C qPCR. In vitro, MC-TGF-β1 expression/secretion were measured after TGF-βRi treatment; conditioned medium was collected. Cholangiocytes and hepatic stellate cells (HSCs) were treated with MC-conditioned medium, and biliary proliferation/senescence was measured by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and qPCR; HSC activation evaluated for α-SMA, SYP-9, and collagen type-1a expression. MC injection recapitulates cholestatic liver injury characterized by increased DR, fibrosis/TGF-β1 secretion, and angiogenesis. Injection of MC-TGF-βRi reversed these parameters. In vitro, MCs induce biliary proliferation/senescence and HSC activation that was reversed with MCs lacking TGF-β1.

CONCLUSIONS

Our study demonstrates that reintroduction of MCs mimics cholestatic liver injury and that MC-derived TGF-β1 may be a target in chronic cholestatic liver disease.

The Roles of Noncardiomyocytes in Cardiac Remodeling

Cardiac remodeling is a common characteristic of almost all forms of heart disease, including cardiac infarction, valvular diseases, hypertension, arrhythmia, dilated cardiomyopathy and other conditions. It is not merely a simple outcome induced by an increase in the workload of cardiomyocytes (CMs). The remodeling process is accompanied by abnormalities of cardiac structure as well as disturbance of cardiac function, and emerging evidence suggests that a wide range of cells in the heart participate in the initiation and development of cardiac remodeling. Other than CMs, there are numerous noncardiomyocytes (non-CMs) that regulate the process of cardiac remodeling, such as cardiac fibroblasts and immune cells (including macrophages, lymphocytes, neutrophils, and mast cells). In this review, we summarize recent knowledge regarding the definition and significant effects of various non-CMs in the pathogenesis of cardiac remodeling, with a particular emphasis on the involved signaling mechanisms. In addition, we discuss the properties of non-CMs, which serve as targets of many cardiovascular drugs that reduce adverse cardiac remodeling.

Novel Insight into the in vivo Function of Mast Cell Chymase: Lessons from Knockouts and Inhibitors

Mast cells are now recognized as key players in diverse pathologies, but the mechanisms by which they contribute in such settings are only partially understood. Mast cells are packed with secretory granules, and when they undergo degranulation in response to activation the contents of the granules are expelled to the extracellular milieu. Chymases, neutral serine proteases, are the major constituents of the mast cell granules and are hence released in large amounts upon mast cell activation. Following their release, chymases can cleave one or several of a myriad of potential substrates, and the cleavage of many of these could potentially have a profound impact on the respective pathology. Indeed, chymases have recently been implicated in several pathological contexts, in particular through studies using chymase inhibitors and by the use of chymase-deficient animals. In many cases, chymase has been shown to account for mast cell-dependent detrimental effects in the respective conditions and is therefore emerging as a promising drug target. On the other hand, chymase has been shown to have protective roles in other pathological settings. More unexpectedly, chymase has also been shown to control certain homeostatic processes. Here, these findings are reviewed.

Wenxin Granules Influence the TGFβ-P38/JNK MAPK Signaling Pathway and Attenuate the Collagen Deposition in the Left Ventricle of Myocardial Infarction Rats

Background

A large number of proinflammatory/anti-inflammatory cytokines are produced in the extracellular matrix (ECM) after myocardial infarction (MI), and the inflammatory pathways activated by these inflammatory stimuli are involved in the regulation of lesions with excessive accumulation of ECM. Wenxin granules can play a protective role against MI, but the mechanism of its effect on the inflammatory pathway and ECM collagen expression is still unclear.

Objective

To verify the effect of Wenxin granules on the inflammatory pathway and collagen expression after MI.

Method

The proximal left anterior descending coronary artery in rats was ligated to induce acute MI. Then, animals were randomly assigned to the model group, the Carvedilol group, and the Wenxin Granules group. In addition, sham operation rats were used as the control group. 10 rats were allocated in each group. Gavage was given once a day for 4 weeks. The changes of cardiac hemodynamics were detected by the catheter method, morphological changes were observed by HE staining, and myocardial tissue collagen volume was counted by Immunohistochemistry combined with Masson staining, and the expression of inflammatory TGFβ-p38/JNK MAPK signal pathway markers was detected by Western blot.

Results

Wenxin granules could significantly improve the hemodynamics, so that the fibrosis scar was relatively dense and uniform, and the residual myocardium was relatively neat, while Collagen type I and III volume and TGFβ expression levels were lessened. Although there were no differences in the expression of CTGF, p38, and JNK proteins, their phosphorylation levels showed significant differences.

Conclusion

Wenxin granules can affect the inflammation-related TGFβ-p38/JNK MAPK signaling pathway and change the structural properties of myocardium and scar after MI by attenuated collagen deposition in the left ventricular myocardial tissue to improve cardiac function.