The antifibrotic agent pirfenidone inhibits angiotensin II-induced cardiac hypertrophy in mice

Modulation of the Sirtuin-1 signaling pathway in doxorubicin-induced nephrotoxicity (synergistic amelioration by resveratrol and pirfenidone)

The current study was conducted to determine the precise mechanisms of Sirtuin-1 (Sirt-1), TGF- β (Transforming Growth Factor-β), and long non-coding RNA Metastasis Associated Lung Adenocarcinoma Transcript 1 (LncRNA MALAT-1) in signaling pathways in doxorubicin (DOX)-induced nephrotoxicity. The potential therapeutic effect of Resveratrol and Pirfenidone in DOX toxicity was also assessed. Thirty-six male adult rats were evenly distributed into four groups: Group 1: control rats. Group 2: DOX exposed rats' group, each animal received 7.5 mg/kg DOX as a single intravenous dose, Group 3: DOX exposed group subjected to oral resveratrol (20 mg/kg/daily for two weeks), Group 4: DOX exposed group subjected to oral Pirfenidone (200 mg/kg once daily for 10 days). At the planned time, animals were sacrificed. Renal tissue was collected to assess matrix metalloproteinase-9 (MMP9), inflammatory and apoptotic markers: tumor necrosis factor-alpha (TNF- β, caspase-3, cyclo-oxygenase-2 (COX-2), and oxidative stress markers: nitric oxide (NO), Glutathione (GSH), malondialdehyde (MDA), and superoxide dismutase (SOD). Sirtuin-1 (Sirt-1), TGF-β, and LncRNA MALAT-1 were quantitatively assessed by real-time RT-PCR in the whole blood. Results showed that the DOX group exhibited a significant increase in oxidative stress markers, and inflammatory, and apoptotic markers in the renal tissue. Histologically, the renal tubule lining cells exhibited vacuolar alterations in the cytoplasm, glomerular atrophy, and vascular congestion. Furthermore, renal degeneration was evident, as confirmed by the heightened immuno-expression of MMP9. Exposure to DOX resulted in a significant decrease in Sirtuin-1 (Sirt-1) with a significant increase in the TGFβ, and LncRNA MALAT-1 gene expression. However, pre-treatment with either resveratrol/or Pirefenidone ameliorated the histological renal alterations, regulated the pathways of Sirt-1, TGFβ, and LncRNA MALAT-1, and decreased all oxidative stress, inflammatory and apoptotic markers. In conclusion, DOX exposure leads to renal toxicity by inducing renal degeneration, oxidative stress, and apoptosis. Administration of either resveratrol or Pirfenidone counteracted these changes and protected the kidney against DOX-induced renal damage.

Current experimental and early investigational agents for cardiac fibrosis: where are we at?

INTRODUCTION

Myocardial fibrosis (MF) is induced by factors activating pro-fibrotic pathways such as acute and prolonged inflammation, myocardial ischemic events, hypertension, aging process, and genetically-linked cardiomyopathies. Dynamics and characteristics of myocardial fibrosis development are very different. The broad range of myocardial fibrosis presentations suggests the presence of multiple potential targets.

AREA COVERED

Heart failure treatment involves medications primarily aimed at counteracting neurohormonal activation. While these drugs have demonstrated efficacy against MF, not all specifically target inflammation or fibrosis progression with some exceptions such as RAAS inhibitors. Consequently, new therapies are being developed to address this issue. This article is aimed to describe anti-fibrotic drugs currently employed in clinical practice and emerging agents that target specific pathways, supported by evidence from both preclinical and clinical studies.

EXPERT OPINION

Despite various preclinical findings suggesting the potential utility of new drugs and molecules for treating cardiac fibrosis in animal models, there is a notable scarcity of clinical trials investigating these effects. However, the pathology of damage and repair in the heart muscle involves a complex network of interconnected inflammatory pathways and various types of immune cells. Our comprehension of the positive and negative roles played by specific immune cells and cytokines is an emerging area of research.

Myocardial Interstitial Fibrosis in Hypertensive Heart Disease: From Mechanisms to Clinical Management

Hypertensive heart disease (HHD) can no longer be considered as the beneficial adaptive result of the hypertrophy of cardiomyocytes in response to pressure overload leading to the development of left ventricular hypertrophy. The current evidence indicates that in patients with HHD, pathological lesions in the myocardium lead to maladaptive structural remodeling and subsequent alterations in cardiac function, electrical activity, and perfusion, all contributing to poor outcomes. Diffuse myocardial interstitial fibrosis is probably the most critically involved lesion in these disorders. Therefore, in this review, we will focus on the histological characteristics, the mechanisms, and the clinical consequences of myocardial interstitial fibrosis in patients with HHD. In addition, we will consider the most useful tools for the noninvasive diagnosis of myocardial interstitial fibrosis in patients with HHD, as well as the most effective available therapeutic strategies to prevent its development or facilitate its regression in this patient population. Finally, we will issue a call to action for the need for more fundamental and clinical research on myocardial interstitial fibrosis in HHD.

Human amnion epithelial cell therapy reduces hypertension-induced vascular stiffening and cognitive impairment

Vascular inflammation and fibrosis are hallmarks of hypertension and contribute to the development of cardiovascular disease and cognitive impairment. However, current anti-hypertensive drugs do not treat the underlying tissue damage, such as inflammation-associated fibrosis. Human amnion epithelial cells have several properties amenable for treating vascular pathology. This study tested the effect of amnion epithelial cells on vascular pathology and cognitive impairment during hypertension. Male C57Bl6 mice (8-12 weeks) were administered vehicle (saline; n = 58) or angiotensin II (0.7 mg/kg/d, n = 56) subcutaneously for 14 d. After surgery, a subset of mice were injected with 106 amnion epithelial cells intravenously. Angiotensin II infusion increased systolic blood pressure, aortic pulse wave velocity, accumulation of aortic leukocytes, and aortic mRNA expression of collagen subtypes compared to vehicle-infused mice (n = 9-11, P < 0.05). Administration of amnion epithelial cells attenuated these effects of angiotensin II (P < 0.05). Angiotensin II-induced cognitive impairment was prevented by amnion epithelial cell therapy (n = 7-9, P < 0.05). In the brain, amnion epithelial cells modulated some of the inflammatory genes that angiotensin II promoted differential expression of (n = 6, p-adjusted < 0.05). These findings suggest that amnion epithelial cells could be explored as a potential therapy to inhibit vascular pathology and cognitive impairment during hypertension.

Empagliflozin protects against isoprenaline-induced fibrosis in rat heart through modulation of TGF-β/SMAD pathway

AIM

Cardiac fibrosis is characterized by excessive accumulation of fibrous tissue, particularly collagens, in the myocardium. Accumulated fibrous tissue renders myocardium stiffer and reduces its contractility. Empagliflozin is an oral hypoglycemic agent with extra-diabetic functional profile toward maintaining cardiac functions. The present study aimed to examine protective effect of empagliflozin against an in-vivo model of cardiac fibrosis induced by isoprenaline and targeting TGF-β/SMAD signaling as a possible pathway responsible for such effect.

MAIN METHODS

Sixty animals were divided into six groups; the first was normal, and the second was treated with isoprenaline only (5 mg/kg/day I.P.) as a control. The third received pirfenidone (500 mg/kg/day P.O.), and the remaining groups received graded doses (5, 10, 20 mg/kg respectively) of empagliflozin for 14 days before fibrosis induction by isoprenaline (5 mg/kg/day) for 30 days.

KEY FINDINGS

Isoprenaline increased cardiac enzymes, and cardiac tissues revealed elevated concentrations of transforming growth factor β (TGF-β1), monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor α (TNF-α), and c-jun N-terminal kinase (JNK) proteins. Expression of nuclear factor kappa B (NF-κB), alpha smooth muscle actin (α-SMA), collagens, suppressor of mothers against decapentaplegic (SMADs), connective tissue growth factor (CTGF), and fibronectin was upregulated. Empagliflozin improved the histological picture of heart tissue in comparison to fibrosis developed in controls, and protected against fibrosis through significant modulation of all mentioned parameters' concentrations and expressions.

SIGNIFICANCE

Empagliflozin demonstrated a promising protective approach against biological model of cardiac fibrosis through an anti-fibrotic effect through targeting TGF-β signaling pathways.

Fluorofenidone enhances cardiac contractility by stimulating CICR and CaV1.2

Fluorofenidone (AKF-PD) is a novel pyridone derivative that inhibits fibrosis and inflammation in many tissues. Accordingly, it has been effective in disease models, such as liver failure, nephropathy, and pulmonary fibrosis. However, its potential role in cardiac physiology and pathology has yet to be elucidated. Thus, this paper investigated a possible functional impact of AKF-PD on adult rat cardiac myocytes. Cells were kept in culture for 1-2 days under either control conditions or the presence of AKF-PD (500 μM). They were next examined concerning cell contractility, intracellular Ca2+ homeostasis, and activity of voltage-gated Ca2+ channels. Remarkably, AKF-PD enhanced the percentage of cell shortening and rates of both contraction and relaxation by nearly 100%. A stimulus in Ca2+-induced Ca2+ release (CICR) most likely accounts for these effects because AKF-PD also increased the magnitude of electrically evoked Ca2+ transients. Of note, the compound did not alter the peak value of caffeine-elicited Ca2+ transients, indicating stimulation of CICR at constant sarcoplasmic reticulum Ca2+ load. Since CICR is triggered by the entry of Ca2+ through CaV1.2 (ICa), a possible effect on these Ca2+ channels was also investigated. AKF-PD increased the magnitude of both ICa and maximal macroscopic Ca2+ conductance (Gmax) by about 50%. However, no differences were found in either voltage dependence of inactivation or the amount of maximal immobilization-resistant charge movement (Qmax). Thus, the effect on ICa could be explained by a higher channel's open probability (Po) rather than a greater abundance of channel proteins. Additional data indicate that AKF-PD reduces the rate of Ca2+ extrusion in the presence of caffeine, suggesting inhibition of the Na/Ca exchanger. Overall, these results indicate that AKF-PD upregulates the Po of CaV1.2 and then sequentially enhances ICa, CICR, and contractility. Therefore, the novel compound is also a candidate to be tested in cardiac disease models.

Pirfenidone ameliorates liver steatosis by targeting the STAT3-SCD1 axis

OBJECTIVE

Previous studies reported that pirfenidone (PFD) is associated with liver disease. However, the effects of pirfenidone on energy metabolism and hepatic lipid accumulation are still poorly understood.

METHODS

In this study, C57BL/6J mice were randomly divided into two groups, and fed a normal chow diet (NCD) or a high-fat diet (HFD) for 16 weeks. At the end of the eighth week, half of the mice fed on both diets were treated with PFD. Biochemical and lipid metabolism-related indices were analyzed. Furthermore, Hepa 1-6 cells and mouse primary hepatocytes (MPHs) were incubated with PFD with or without free fatty acid (FFA) treatment. Then, stattic (a p-STAT3 inhibitor) or Ad-shSTAT3 was used to further elucidate the effects of Signal Transducer and Activator of Transcription 3 (STAT3) signaling on PFD regulation of hepatic steatosis.

RESULTS

PFD ameliorated obesity and hepatic lipid deposition in HFD mice by decreasing stearoyl-CoA desaturase 1 (SCD1) expression and upregulating p-STAT3 in the liver. In Hepa 1-6 cells and MPHs, PFD also down-regulated the expression of SCD1. STAT3 inhibition treatment eliminated the benefits of PFD on both SCD1 and hepatic steatosis.

CONCLUSION

In summary, our data reveal that PFD may play an important role in mitigating hepatic steatosis in a STAT3-SCD1-dependent manner.

Activated fibroblasts in cardiac and cancer fibrosis: An overview of analogies and new potential therapeutic options

Heart disease and cancer are two major causes of morbidity and mortality in the industrialized countries, and their increasingly recognized connections are shifting the focus from single disease studies to an interdisciplinary approach. Fibroblast-mediated intercellular crosstalk is critically involved in the evolution of both pathologies. In healthy myocardium and in non-cancerous conditions, resident fibroblasts are the main cell source for synthesis of the extracellular matrix (ECM) and important sentinels of tissue integrity. In the setting of myocardial disease or cancer, quiescent fibroblasts activate, respectively, into myofibroblasts (myoFbs) and cancer-associated fibroblasts (CAFs), characterized by increased production of contractile proteins, and by a highly proliferative and secretory phenotype. Although the initial activation of myoFbs/CAFs is an adaptive process to repair the damaged tissue, massive deposition of ECM proteins leads to maladaptive cardiac or cancer fibrosis, a recognized marker of adverse outcome. A better understanding of the key mechanisms orchestrating fibroblast hyperactivity may help developing innovative therapeutic options to restrain myocardial or tumor stiffness and improve patient prognosis. Albeit still unappreciated, the dynamic transition of myocardial and tumor fibroblasts into myoFbs and CAFs shares several common triggers and signaling pathways relevant to TGF-β dependent cascade, metabolic reprogramming, mechanotransduction, secretory properties, and epigenetic regulation, which might lay the foundation for future antifibrotic intervention. Therefore, the aim of this review is to highlight emerging analogies in the molecular signature underlying myoFbs and CAFs activation with the purpose of identifying novel prognostic/diagnostic biomarkers, and to elucidate the potential of drug repositioning strategies to mitigate cardiac/cancer fibrosis.

Signaling Pathways and Potential Therapeutic Strategies in Cardiac Fibrosis

Cardiac fibrosis constitutes irreversible necrosis of the heart muscle as a consequence of different acute (myocardial infarction) or chronic (diabetes, hypertension, …) diseases but also due to genetic alterations or aging. Currently, there is no curative treatment that is able to prevent or attenuate this phenomenon that leads to progressive cardiac dysfunction and life-threatening outcomes. This review summarizes the different targets identified and the new strategies proposed to fight cardiac fibrosis. Future directions, including the use of exosomes or nanoparticles, will also be discussed.

Treatment of cardiac fibrosis: from neuro-hormonal inhibitors to CAR-T cell therapy

Cardiac fibrosis is characterized by the deposition of extracellular matrix proteins in the spaces between cardiomyocytes following both acute and chronic tissue damage events, resulting in the remodeling and stiffening of heart tissue. Fibrosis plays an important role in the pathogenesis of many cardiovascular disorders, including heart failure and myocardial infarction. Several studies have identified fibroblasts, which are induced to differentiate into myofibroblasts in response to various types of damage, as the most important cell types involved in the fibrotic process. Some drugs, such as inhibitors of the renin-angiotensin-aldosterone system, have been shown to be effective in reducing cardiac fibrosis. There are currently no drugs with primarily anti-fibrotic action approved for clinical use, as well as the evidence of a clinical efficacy of these drugs is extremely limited, despite the numerous encouraging results from experimental studies. A new approach is represented by the use of CAR-T cells engineered in vivo using lipid nanoparticles containing mRNA coding for a receptor directed against the FAP protein, expressed by cardiac myofibroblasts. This strategy has proved to be safe and effective in reducing myocardial fibrosis and improving cardiac function in mouse models of cardiac fibrosis. Clinical studies are required to test this novel approach in humans.

Investigating the possible mechanisms of pirfenidone to be targeted as a promising anti-inflammatory, anti-fibrotic, anti-oxidant, anti-apoptotic, anti-tumor, and/or anti-SARS-CoV-2

Pirfenidone (PFD) is a non-peptide synthetic chemical that inhibits the production of transforming growth factor-beta 1 (TGF-β1), tumor necrosis factor-alpha (TNF-α), platelet-derived growth factor (PDGF), Interleukin 1 beta (IL-1β), and collagen 1 (COL1A1), all of which have been linked to the prevention or removal of excessive scar tissue deposition in many organs. PFD has been demonstrated to decrease apoptosis, downregulate angiotensin-converting enzyme (ACE) receptor expression, reduce inflammation through many routes, and alleviate oxidative stress in pneumocytes and other cells while protecting them from COVID-19 invasion and cytokine storm. Based on the mechanism of action of PFD and the known pathophysiology of COVID-19, it was recommended to treat COVID-19 patients. The use of PFD as a treatment for a range of disorders is currently being studied, with an emphasis on outcomes related to reduced inflammation and fibrogenesis. As a result, rather than exploring the molecule's chemical characteristics, this review focuses on innovative PFD efficacy data. Briefly, herein we tried to investigate, discuss, and illustrate the possible mechanisms of actions for PFD to be targeted as a promising anti-inflammatory, anti-fibrotic, anti-oxidant, anti-apoptotic, anti-tumor, and/or anti-SARS-CoV-2 candidate.

Pirfenidone alleviates cardiac fibrosis induced by pressure overload via inhibiting TGF-β1/Smad3 signalling pathway

Cardiac fibrosis critically injured the cardiac structure and function of the hypertensive patients. However, the anti‐fibrotic strategy is still far from satisfaction. This study aims to determine the effect and mechanism of Pirfenidone (PFD), an anti‐lung fibrosis medicine, in the treatment of cardiac fibrosis and heart failure induced by pressure overload. Male C57BL/6 mice were subjected to thoracic aorta constriction (TAC) or sham surgery with the vehicle, PFD (300 mg/kg/day) or Captopril (CAP, 20 mg/kg/day). After 8 weeks of surgery, mice were tested by echocardiography, and then sacrificed followed by morphological and molecular biological analysis. Compared to the sham mice, TAC mice showed a remarkable cardiac hypertrophy, interstitial and perivascular fibrosis and resultant heart failure, which were reversed by PFD and CAP significantly. The enhanced cardiac expression of TGF‐β1 and phosphorylation of Smad3 in TAC mice were both restrained by PFD. Cardiac fibroblasts isolated from adult C57BL/6 mice were treated by Angiotensin II, which led to significant increases in cellular proliferation and levels of α‐SMA, vimentin, TGF‐β1 and phosphorylated TGF‐β receptor and Smad3. These changes were markedly inhibited by pre‐treatment of PFD. Collectively, PFD attenuates myocardial fibrosis and dysfunction induced by pressure overload via inhibiting the activation of TGF‐β1/Smad3 signalling pathway.

Cardiac Fibrosis in the Pressure Overloaded Left and Right Ventricle as a Therapeutic Target

Myocardial fibrosis is a remodeling process of the extracellular matrix (ECM) following cardiac stress. "Replacement fibrosis" is a term used to describe wound healing in the acute phase of an injury, such as myocardial infarction. In striking contrast, ECM remodeling following chronic pressure overload insidiously develops over time as "reactive fibrosis" leading to diffuse interstitial and perivascular collagen deposition that continuously perturbs the function of the left (L) or the right ventricle (RV). Examples for pressure-overload conditions resulting in reactive fibrosis in the LV are systemic hypertension or aortic stenosis, whereas pulmonary arterial hypertension (PAH) or congenital heart disease with right sided obstructive lesions such as pulmonary stenosis result in RV reactive fibrosis. In-depth phenotyping of cardiac fibrosis has made it increasingly clear that both forms, replacement and reactive fibrosis co-exist in various etiologies of heart failure. While the role of fibrosis in the pathogenesis of RV heart failure needs further assessment, reactive fibrosis in the LV is a pathological hallmark of adverse cardiac remodeling that is correlated with or potentially might even drive both development and progression of heart failure (HF). Further, LV reactive fibrosis predicts adverse outcome in various myocardial diseases and contributes to arrhythmias. The ability to effectively block pathological ECM remodeling of the LV is therefore an important medical need. At a cellular level, the cardiac fibroblast takes center stage in reactive fibrotic remodeling of the heart. Activation and proliferation of endogenous fibroblast populations are the major source of synthesis, secretion, and deposition of collagens in response to a variety of stimuli. Enzymes residing in the ECM are responsible for collagen maturation and cross-linking. Highly cross-linked type I collagen stiffens the ventricles and predominates over more elastic type III collagen in pressure-overloaded conditions. Research has attempted to identify pro-fibrotic drivers causing fibrotic remodeling. Single key factors such as Transforming Growth Factor β (TGFβ) have been described and subsequently targeted to test their usefulness in inhibiting fibrosis in cultured fibroblasts of the ventricles, and in animal models of cardiac fibrosis. More recently, modulation of phenotypic behaviors like inhibition of proliferating fibroblasts has emerged as a strategy to reduce pathogenic cardiac fibroblast numbers in the heart. Some studies targeting LV reactive fibrosis as outlined above have successfully led to improvements of cardiac structure and function in relevant animal models. For the RV, fibrosis research is needed to better understand the evolution and roles of fibrosis in RV failure. RV fibrosis is seen as an integral part of RV remodeling and presents at varying degrees in patients with PAH and animal models replicating the disease of RV afterload. The extent to which ECM remodeling impacts RV function and thus patient survival is less clear. In this review, we describe differences as well as common characteristics and key players in ECM remodeling of the LV vs. the RV in response to pressure overload. We review pre-clinical studies assessing the effect of anti-fibrotic drug candidates on LV and RV function and their premise for clinical testing. Finally, we discuss the mode of action, safety and efficacy of anti-fibrotic drugs currently tested for the treatment of left HF in clinical trials, which might guide development of new approaches to target right heart failure. We touch upon important considerations and knowledge gaps to be addressed for future clinical testing of anti-fibrotic cardiac therapies.

Pirfenidone for Idiopathic Pulmonary Fibrosis and Beyond

Pirfenidone (PFD) slows the progression of idiopathic pulmonary fibrosis (IPF) by inhibiting the exaggerated fibrotic response and possibly through additional mechanisms, such as anti-inflammatory effects. PFD has also been evaluated in other fibrosing lung diseases. Myocardial fibrosis is a common feature of several heart diseases and the progressive deposition of extracellular matrix due to a persistent injury to cardiomyocytes may trigger a vicious cycle that leads to persistent structural and functional alterations of the myocardium. No primarily antifibrotic medications are used to treat patients with heart failure. There is some evidence that PFD has antifibrotic actions in various animal models of cardiac disease and a phase II trial on patients with heart failure and preserved ejection fraction has yielded positive results. This review summarises the evidence about the possible mechanisms of IPF and modulation by PFD, the main results about IPF or non-IPF interstitial pneumonias and also data about PFD as a potential protective cardiac drug.

At the Intersection of Cardiology and Oncology: TGFβ as a Clinically Translatable Therapy for TNBC Treatment and as a Major Regulator of Post-Chemotherapy Cardiomyopathy

Simple Summary

Specific/targeted therapies have been shown to be effective in the treatment of certain cancers. Unfortunately, there is currently no targeted therapy for the treatment of triple-negative breast cancer (TNBC), which is why this subtype of breast cancer is associated with poor patient prognosis. While there is an immense focus on the development of new therapies, the issue of cardiotoxicity following chemotherapeutic treatment is commonly overlooked, despite its role as a leading cause of mortality in cancer survivors. This review aims to discuss the connection of TGF-β signaling and its role in modulating cardiac fibrosis and remodeling, as well as its role in TNBC tumor progression, cancer stem cell enrichment, chemoresistance and relapse. Together, we highlight the modulation of TGF-β as a method to target two of the greatest causes of morbidity and mortality in breast cancer patients.

Abstract

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that accounts for the majority of breast cancer-related deaths due to the lack of specific targets for effective treatments. While there is immense focus on the development of novel therapies for TNBC treatment, a persistent and critical issue is the rate of heart failure and cardiomyopathy, which is a leading cause of mortality and morbidity amongst cancer survivors. In this review, we highlight mechanisms of post-chemotherapeutic cardiotoxicity exposure, evaluate how this is assessed clinically and highlight the transforming growth factor-beta family (TGF-β) pathway and its significance as a mediator of cardiomyopathy. We also highlight recent findings demonstrating TGF-β inhibition as a potent method to prevent cardiac remodeling, fibrosis and cardiomyopathy. We describe how dysregulation of the TGF-β pathway is associated with negative patient outcomes across 32 types of cancer, including TNBC. We then highlight how TGF-β modulation may be a potent method to target mesenchymal (CD44⁺/CD24⁻) and epithelial (ALDH^high) cancer stem cell (CSC) populations in TNBC models. CSCs are associated with tumorigenesis, metastasis, relapse, resistance and diminished patient prognosis; however, due to plasticity and differential regulation, these populations remain difficult to target and continue to present a major barrier to successful therapy. TGF-β inhibition represents an intersection of two fields: cardiology and oncology. Through the inhibition of cardiomyopathy, cardiac damage and heart failure may be prevented, and through CSC targeting, patient prognoses may be improved. Together, both approaches, if successfully implemented, would target the two greatest causes of cancer-related morbidity in patients and potentially lead to a breakthrough therapy.

Pirfenidone Has Anti-fibrotic Effects in a Tissue-Engineered Model of Human Cardiac Fibrosis

A fundamental process in the development and progression of heart failure is fibrotic remodeling, characterized by excessive deposition of extracellular matrix proteins in response to injury. Currently, therapies that effectively target and reverse cardiac fibrosis are lacking, warranting novel therapeutic strategies and reliable methods to study their effect. Using a gelatin methacryloyl hydrogel, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) and human fetal cardiac fibroblasts (hfCF), we developed a multi-cellular mechanically tunable 3D in vitro model of human cardiac fibrosis. This model was used to evaluate the effects of a promising anti-fibrotic drug-pirfenidone-and yields proof-of-concept of the drug testing potential of this platform. Our study demonstrates that pirfenidone has anti-fibrotic effects but does not reverse all TGF-β1 induced pro-fibrotic changes, which provides new insights into its mechanism of action.

Pirfenidone as a novel cardiac protective treatment

Myocardial fibrosis is a common feature of several heart diseases. The progressive deposition of extracellular matrix due to a persistent injury to cardiomyocytes may trigger a vicious cycle that leads to persistent structural and functional alterations of the myocardium. Some drugs (like renin–angiotensin–aldosterone system inhibitors) have been shown to reduce extracellular matrix deposition, but no primarily anti-fibrotic medications are currently used to treat patients with heart failure (HF). Pirfenidone is an oral antifibrotic agent approved for the treatment of idiopathic pulmonary fibrosis. Although its exact mechanism of action is not fully understood, pirfenidone might reduce the expression of profibrotic factors such as transforming growth factor-β (TGF-β), and proinflammatory cytokines, like tumor necrosis factor-α (TNF-α), interleukin (IL)-4, and IL-13, which could modulate the inflammatory response and inhibit collagen synthesis in lung tissue. There is some evidence that pirfenidone has antifibrotic activity in various animal models of cardiac disease. Furthermore, the positive results of the PIROUETTE trial, evaluating pirfenidone in patients with HF with preserved ejection fraction, have been very recently announced. This review summarizes the data about pirfenidone as a potential cardioprotective treatment.

Pirfenidone in heart failure with preserved ejection fraction: a randomized phase 2 trial

In heart failure with preserved ejection fraction (HFpEF), the occurrence of myocardial fibrosis is associated with adverse outcome. Whether pirfenidone, an oral antifibrotic agent without hemodynamic effect, is efficacious and safe for the treatment of HFpEF is unknown. In this double-blind, phase 2 trial ( NCT02932566 ), we enrolled patients with heart failure, an ejection fraction of 45% or higher and elevated levels of natriuretic peptides. Eligible patients underwent cardiovascular magnetic resonance and those with evidence of myocardial fibrosis, defined as a myocardial extracellular volume of 27% or greater, were randomly assigned to receive pirfenidone or placebo for 52 weeks. Forty-seven patients were randomized to each of the pirfenidone and placebo groups. The primary outcome was change in myocardial extracellular volume, from baseline to 52 weeks. In comparison to placebo, pirfenidone reduced myocardial extracellular volume (between-group difference, -1.21%; 95% confidence interval, -2.12 to -0.31; P = 0.009), meeting the predefined primary outcome. Twelve patients (26%) in the pirfenidone group and 14 patients (30%) in the placebo group experienced one or more serious adverse events. The most common adverse events in the pirfenidone group were nausea, insomnia and rash. In conclusion, among patients with HFpEF and myocardial fibrosis, administration of pirfenidone for 52 weeks reduced myocardial fibrosis. The favorable effects of pirfenidone in patients with HFpEF will need to be confirmed in future trials.

Immune Cells and Immunotherapy for Cardiac Injury and Repair

Cardiac injury remains a major cause of morbidity and mortality worldwide. Despite significant advances, a full understanding of why the heart fails to fully recover function after acute injury, and why progressive heart failure frequently ensues, remains elusive. No therapeutics, short of heart transplantation, have emerged to reliably halt or reverse the inexorable progression of heart failure in the majority of patients once it has become clinically evident. To date, most pharmacological interventions have focused on modifying hemodynamics (reducing afterload, controlling blood pressure and blood volume) or on modifying cardiac myocyte function. However, important contributions of the immune system to normal cardiac function and the response to injury have recently emerged as exciting areas of investigation. Therapeutic interventions aimed at harnessing the power of immune cells hold promise for new treatment avenues for cardiac disease. Here, we review the immune response to heart injury, its contribution to cardiac fibrosis, and the potential of immune modifying therapies to affect cardiac repair.

Rationale for the Use of Pirfenidone in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major public health problem with growing prevalence and poor outcomes, mainly due to the lack of an effective treatment. HFpEF pathophysiology is heterogeneous and complex. Recently a “new paradigm” has been proposed, suggesting that cardiovascular and non-cardiovascular coexisting comorbidities lead to a systemic inflammatory state, perturbing the physiology of the endothelium and the perivascular environment and engaging molecular pathways that ultimately converge to myocardial fibrosis. If inflammation and fibrosis are the “fil rouge” in the heterogeneous spectrum of HFpEF, anti-fibrotic and anti-inflammatory drugs may have a role in its treatment. Pirfenidone is an orally bioavailable drug with antifibrotic and anti-inflammatory properties already approved for the treatment of idiopathic pulmonary fibrosis. Pirfenidone has been recently tested in animal models of myocardial fibrosis with promising results. Here we will review the rationale underlying the potential therapeutic effect of Pirfenidone in HFpEF.

Controllable release of pirfenidone by polyvinyl alcohol film embedded soft contact lenses in vitro and in vivo

To increase the amount of pirfenidone (PFD) loaded in polyvinyl alcohol (PVA) film embedded soft contact lens (SCL), and evaluate its function of sustaining delivery of drug in vitro and in vivo. Drug loading efficiency within PVA film and SCLs, drug release from SCLs in vitro, and the effects of parameters of SCLs and external environment on drug release in vitro were evaluated by ultraviolet–visible spectrophotometer at 312 nm. Safety of SCLs was evaluated in vitro by transformed human corneal epithelial cell. Safety in vivo was determined by optical coherence tomography and histology of anterior segment of rabbits. Drug release study in tear fluid and aqueous humor were measured by ultra-performance liquid chromatography. SCLs had smooth surface and were fit for experimental rabbits. Amount of PFD in PVA film and SCLs were 153.515 μg ± 12.508 and 127.438 μg ± 19.674, respectively, PFD in PVA film was significantly higher than SCLs (p=.006) and closed to 150 μg (targeting amount of PFD to be loaded). Thickness of SCLs, molecular weight of PVA, and amount of PVA used in SCLs affected drug release in vitro significantly. Thickness of PVA film and amount of drug in SCLs had no effect on drug release rate in vitro. SCLs were safe in vitro and in vivo, PFD released from SCLs could be detected around 12 hours in tears and aqueous humor, and the concentration of drug was higher than eye drop at all detected time points while amount of PFD in SCLs was lower than eye drop. Drug loaded PVA film embedded SCLs may be a promising ocular drug delivery system.

Pirfenidone Is a Vasodilator: Involvement of KV7 Channels in the Effect on Endothelium-Dependent Vasodilatation in Type-2 Diabetic Mice

Endothelial cell dysfunction and fibrosis are associated with worsening of the prognosis in patients with cardiovascular disease. Pirfenidone has a direct antifibrotic effect, but vasodilatation may also contribute to the effects of pirfenidone. Therefore, in a first study we investigated the mechanisms involved in the relaxant effect of pirfenidone in rat intrapulmonary arteries and coronary arteries from normal mice. Then in a second study, we investigated whether pirfenidone restores endothelial function in the aorta and mesenteric arteries from diabetic animals. From 16–18-week old normal male C57BL/6 mice and normoglycemic (db/db+), and type 2 diabetic (db/db) male and female mice, arteries were mounted in microvascular isometric myographs for functional studies, and immunoblotting was performed. In rat pulmonary arteries and mouse coronary arteries, pirfenidone induced relaxations, which were inhibited in preparations without endothelium. In mouse coronary arteries, pirfenidone relaxation was inhibited in the presence of a nitric oxide (NO) synthase inhibitor, N^G-nitro-l-arginine (L-NOARG), a blocker of large-conductance calcium-activated potassium channels (BK_Ca), iberiotoxin, and a blocker of K_V7 channels, XE991. Patch clamp studies in vascular smooth muscle revealed pirfenidone increased iberiotoxin-sensitive current. In the aorta and mesenteric small arteries from diabetic db/db mice relaxations induced by the endothelium-dependent vasodilator, acetylcholine, were markedly reduced compared to db/db + mice. Pirfenidone enhanced the relaxations induced by acetylcholine in the aorta from diabetic male and female db/db mice. An opener of K_V7 channels, flupirtine, had the same effect as pirfenidone. XE991 reduced the effect of pirfenidone and flupirtine and further reduced acetylcholine relaxations in the aorta. In the presence of iberiotoxin, pirfenidone still increased acetylcholine relaxation in aorta from db/db mice. Immunoblotting for K_V7.4, K_V7.5, and BK_Ca channel subunits were unaltered in aorta from db/db mice. Pirfenidone failed to improve acetylcholine relaxation in mesenteric arteries, and neither changed acetylcholine-induced transient decreases in blood pressure in db/db+ and db/db mice. In conclusion, pirfenidone vasodilates pulmonary and coronary arteries. In coronary arteries from normal mice, pirfenidone induces NO-dependent vasodilatation involving BK_Ca and K_V7 channels. Pirfenidone improves endothelium-dependent vasodilatation in aorta from diabetic animals by a mechanism involving voltage-gated K_V7 channels, a mechanism that may contribute to the antifibrotic effect of pirfenidone.

A Review of Pirfenidone as an Anti-Fibrotic in Idiopathic Pulmonary Fibrosis and Its Probable Role in Other Diseases

Fibrosis is the result of chronic inflammation and is known to pathologically occur in many organs and systems. Pirfenidone (PFD) is an anti-fibrotic known for its use in idiopathic pulmonary fibrosis (IPF). In addition to being an anti-fibrotic, it acts as an anti-inflammatory and antioxidant as well. There have been studies on PFD in other diseases, some clinical and others preclinical. We have compiled and reviewed them to highlight just how widespread PFD use could be. Among many benefits of PFD in IPF, PFD has effectively improved patients' survival in those who had an acute exacerbation of IPF and has reduced respiratory-related hospitalization, among few others. PFD also has shown an improvement in vital capacity in patients with chronic hypersensitive pneumonitis. Also, it has demonstrated anti-fibrotic effects in systemic sclerosis-associated interstitial lung disease. In other diseases outside the lungs, PFD has reversed insulin resistance and proven to be effective in non-alcoholic steatohepatitis (NASH). It has prevented blindness post-alkali injury to the eye and has proven to decrease the proliferation of mesothelioma cells, just to name a few. This review encourages further research in connection with PFD and its use in other diseases and PFD pros in IPF.

Controlling cardiac fibrosis through fibroblast state space modulation

The transdifferentiation of cardiac fibroblasts into myofibroblasts after cardiac injury has traditionally been defined by a unidirectional continuum from quiescent fibroblasts, through activated fibroblasts, and finally to fibrotic-matrix producing myofibroblasts. However, recent lineage tracing and single cell RNA sequencing experiments have demonstrated that fibroblast transdifferentiation is much more complex. Growing evidence suggests that fibroblasts are more heterogenous than previously thought, and many new cell states have recently been identified. This review reexamines conventional fibroblast transdifferentiation paradigms with a dynamic state space lens, which could enable a more complex understanding of how fibroblast state dynamics alters fibrotic remodeling of the heart. This review will define cellular state space, how it relates to fibroblast state transitions, and how the canonical and non-canonical fibrotic signaling pathways modulate fibroblast cell state and cardiac fibrosis. Finally, this review explores the therapeutic potential of fibroblast state space modulation by p38 inhibition, yes-associated protein (YAP) inhibition, and fibroblast reprogramming.

Extended Delivery of Pirfenidone with Novel, Soft Contact Lenses In Vitro and In Vivo

Purpose: The aim of this study was to fabricate pirfenidone (PFD)-loaded soft contact lenses (SCLs), explore their characteristics, and evaluate their efficiency on extended delivery of PFD in vitro and in vivo. Methods: PFD-loaded SCLs were fabricated by embedding an insert of PFD and polyvinyl alcohol (PVA) into 2 layers of silicone elastomer. The optical transparency, water content, and protein deposition were measured. Transformed human corneal epithelial cells were used to test the cytotoxicity of SCLs. The release rate of PFD by SCLs in vitro was evaluated by an ultraviolet-visible spectrophotometer. Toxicity of SCLs was assessed by inspection of ocular surface irritation in rabbits before and after contact lens wear. The concentrations of PFD in tears and aqueous humor of rabbits' eyes as a function of time were determined by high-performance liquid chromatography for SCLs and 30 μL of 0.5% PFD eye drops. Results: SCLs possessed good light transmittance. Blank SCLs had poor water content (0.548% ± 0.330), and an improved water content was found in PVA film-loaded SCLs (11.022% ± 1.508, P = 0.010). No lysozyme and human serum albumin were found in SCLs. There was no significant toxicity of SCLs in vitro and in vivo. SCLs prolonged the residence time of PFD in tears and aqueous humor of rabbit eyes by 5 times compared with the eye drop instillation while around 1/10 of the eye drop dosage was loaded in SCLs. Conclusions: PFD-loaded SCLs can significantly prolong the residence time of PFD and may be a promising ocular drug delivery system.

Myocardial Fibrosis in Heart Failure: Anti-Fibrotic Therapies and the Role of Cardiovascular Magnetic Resonance in Drug Trials

All heart muscle diseases that cause chronic heart failure finally converge into one dreaded pathological process that is myocardial fibrosis. Myocardial fibrosis predicts major adverse cardiovascular events and death, yet we are still missing the targeted therapies capable of halting and/or reversing its progression. Fundamentally it is a problem of disproportionate extracellular collagen accumulation that is part of normal myocardial ageing and accentuated in certain disease states. In this article we discuss the role of cardiovascular magnetic resonance (CMR) imaging biomarkers to track fibrosis and collate results from the most promising animal and human trials of anti-fibrotic therapies to date. We underscore the ever-growing role of CMR in determining the efficacy of such drugs and encourage future trialists to turn to CMR when designing their surrogate study endpoints.

Targeting cardiac fibrosis in heart failure with preserved ejection fraction: mirage or miracle?

Cardiac fibrosis is central to the pathology of heart failure, particularly heart failure with preserved ejection fraction (HFpEF). Irrespective of the underlying profibrotic condition (e.g. ageing, diabetes, hypertension), maladaptive cardiac fibrosis is defined by the transformation of resident fibroblasts to matrix-secreting myofibroblasts. Numerous profibrotic factors have been identified at the molecular level (e.g. TGFβ, IL11, AngII), which activate gene expression programs for myofibroblast activation. A number of existing HF therapies indirectly target fibrotic pathways; however, despite multiple clinical trials in HFpEF, a specific clinically effective antifibrotic therapy remains elusive. Therapeutic inhibition of TGFβ, the master-regulator of fibrosis, has unfortunately proven toxic and ineffective in clinical trials to date, and new approaches are needed. In this review, we discuss the pathophysiology and clinical implications of interstitial fibrosis in HFpEF. We provide an overview of trials targeting fibrosis in HFpEF to date and discuss the promise of potential new therapeutic approaches and targets in the context of underlying molecular mechanisms.

Pirfenidone is a cardioprotective drug: Mechanisms of action and preclinical evidence

Myocardial fibrosis is an endogenous response to different cardiac insults that may become maladaptive over time and contribute to the onset and progression of heart failure (HF). Fibrosis is a direct and indirect target of established HF therapies, namely inhibitors of the renin-angiotensin-aldosterone system, but its resilience to therapy warrants a search for novel, more targeted approaches to myocardial fibrosis. Pirfenidone is a drug approved for idiopathic pulmonary fibrosis, a severe form of idiopathic interstitial pneumonias. Pirfenidone is a small synthetic molecule with high oral bioavailability, exerting an antifibrotic activity, but also anti-oxidant and anti-inflammatory effects. These effects have been attributed to the inhibition of several growth factors (in particular transforming growth factor-β, but also platelet-derived growth factor and beta fibroblast growth factor), matrix metalloproteinases, and pro-inflammatory mediators (such as interleukin-1β and tumour necrosis factor-α), and possibly also an improvement of mitochondrial function and modulation of lymphocyte activation. Given the activation of similar profibrotic pathways in lung and heart disease, the crucial role of fibrosis in several cardiac disorders, and the wide spectrum of activity of pirfenidone, this drug has been evaluated with interest as a potential treatment for cardiac disorders. In animal studies, pirfenidone has shown cardioprotective effects across different species and in a variety of models of cardiomyopathy. In the present review we summarize the pharmacological characteristics of pirfenidone and the data from animal studies supporting its cardioprotective effects.

Pirfenidone attenuates homocysteine‑induced apoptosis by regulating the connexin 43 pathway in H9C2 cells

Pirfenidone (PFD) is an anti-fibrotic agent that is clinically used in the treatment of idiopathic pulmonary fibrosis. PFD has been shown to exert protective effects against damage to orbital fibroblasts, endothelial cells, liver cells and renal proximal tubular cells; however, its effect on myocardial cell apoptosis remains unclear. The present study aimed to characterize the effects of PFD on homocysteine (Hcy)-induced cardiomyocyte apoptosis and investigated the underlying mechanisms. H9C2 rat cardiomyocytes were pre-treated with PFD for 30 min followed by Hcy exposure for 24 h. The effects of PFD on cell cytotoxicity were evaluated by CCK-8 assay. The apoptosis rate of each group was determined by flow cytometry. The protein and mRNA levels of connexin 43 (Cx43), Bax, B-cell lymphoma-2 (Bcl-2) and caspase-3 were measured by western blot analysis and reverse transcription-quantitative PCR, respectively. The present results demonstrated that the apoptotic rate increased following Hcy exposure, whereas the apoptotic rate significantly decreased following PFD pre-treatment. Furthermore, the ratio of Bax/Bcl2 was upregulated following Hcy exposure, and Hcy upregulated the expression levels of cleaved caspase-3 and Cx43. Notably, these effects were prevented by PFD. Additionally, the effects of PFD were inhibited by the Cx43 agonist, AAP10. In summary, the findings of the present study demonstrate that PFD protects H9C2 rat cardiomyocytes against Hcy-induced apoptosis by modulating the Cx43 signaling pathway.

Pirfenidone in Heart Failure with Preserved Ejection Fraction-Rationale and Design of the PIROUETTE Trial

BACKGROUND

The PIROUETTE (PIRfenidOne in patients with heart failUre and preserved lEfT venTricular Ejection fraction) trial is designed to evaluate the efficacy and safety of the anti-fibrotic pirfenidone in patients with chronic heart failure and preserved ejection fraction (HFpEF) and myocardial fibrosis. HFpEF is a diverse syndrome associated with substantial morbidity and mortality. Myocardial fibrosis is a key pathophysiological mechanism of HFpEF and myocardial fibrotic burden is strongly and independently associated with adverse outcome. Pirfenidone is an oral anti-fibrotic agent, without haemodynamic effect, that leads to regression of myocardial fibrosis in preclinical models. It has proven clinical effectiveness in pulmonary fibrosis.

METHODS

The PIROUETTE trial is a randomised, double-blind, placebo-controlled phase II trial evaluating the efficacy and safety of 52 weeks of treatment with pirfenidone in patients with chronic HFpEF (symptoms and signs of heart failure, left ventricular ejection fraction ≥ 45%, elevated natriuretic peptides [BNP ≥ 100 pg/ml or NT-proBNP ≥ 300 pg/ml; or BNP ≥ 300 pg/ml or NT-proBNP ≥ 900 pg/ml if in atrial fibrillation]) and myocardial fibrosis (extracellular matrix (ECM) volume ≥ 27% measured using cardiovascular magnetic resonance). The primary outcome measure is change in myocardial ECM volume. A sub-study will investigate the relationship between myocardial fibrosis and myocardial energetics, and the impact of pirfenidone, using ³¹phosphorus magnetic resonance spectroscopy.

DISCUSSION

PIROUETTE will determine whether pirfenidone is superior to placebo in relation to regression of myocardial fibrosis and improvement in myocardial energetics in patients with HFpEF and myocardial fibrosis (NCT02932566).

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov (NCT02932566) https://clinicaltrials.gov/ct2/show/NCT02932566.

Pressure overload induced right ventricular remodeling is not attenuated by the anti-fibrotic agent pirfenidone

Cardiac fibrosis contributes to the development of heart failure in pulmonary hypertension. We aimed to assess the development of fibrosis and the effects of treatment with the anti-fibrotic agent pirfenidone in pressure overload induced right ventricular (RV) failure. Wistar rat weanlings were randomized to pulmonary trunk banding (PTB) or sham surgery. One week after the procedure, PTB rats were randomized into two groups with either six weeks on standard chow or treatment with pirfenidone mixed in chow (700 mg/kg/day). RV hemodynamic effects were evaluated by echocardiography, cardiac magnetic resonance imaging (MRI), and pressure-volume measurements. Sections from the isolated RV, left ventricle, and septum were sampled systematically; stereological point grids and the nucleator were used to estimate volume of fibrosis and cardiac hypertrophy, respectively. PTB caused RV failure in all rats subjected to the procedure. The volume fraction of fibrosis in the RV increased threefold in PTB rats corresponding to a sixfold increase in total volume of RV fibrosis. Volume fraction of fibrosis and total volume of fibrosis also increased in the septum and in the left ventricle. Pirfenidone reduced body weight but did not improve RV hemodynamics or reduce cardiac fibrosis. RV cardiomyocyte profile area was increased twofold in PTB rats without any effect of pirfenidone. RV pressure overload after PTB induced not only RV but also septal and left ventricular fibrosis assessed by stereology. Treatment with pirfenidone reduced body weight but did not reduce the development of cardiac fibrosis or delay the progression of RV failure.

Association of Angiotensin Modulators With the Course of Idiopathic Pulmonary Fibrosis

BACKGROUND

Angiotensin peptides have been implicated in idiopathic pulmonary fibrosis (IPF) pathogenesis. Angiotensin modulators are used to treat arterial hypertension, a frequent comorbidity of IPF. This post hoc analysis evaluated associations of antihypertensive treatments with disease-related outcomes in IPF.

METHODS

All patients randomized to placebo (n = 624) in the CAPACITY and ASCEND studies were categorized by antihypertensive treatment at baseline. Outcomes of disease progression (first occurrence of ≥ 10% absolute decline in % predicted FVC, ≥ 50-m decline in 6-min walk distance, or death) and all-cause mortality were assessed over 52 weeks.

RESULTS

At baseline, 111 and 121 patients were receiving an angiotensin-converting enzyme inhibitor (ACEi) or an angiotensin II receptor blocker (ARB), respectively; 392 were receiving neither. In multivariable analyses adjusted for differences in baseline characteristics compared with the non-ACEi/ARB group, ACEi treatment (hazard ratio [HR], 0.6 [95% CI, 0.4-0.9]; P = .026), but not ARB (HR, 0.9 [95% CI, 0.6-1.2]; P = .413), was associated with slower disease progression. Furthermore, the increase in all-cause mortality associated with cardiovascular disease was not observed in the ACEi group (HR, 1.1 [95% CI, 0.5-2.9]; P = .782), which presented a similar percentage of IPF-related mortality as the non-ACEi/ARB group (3.6% vs 3.6%). In contrast, patients in the ARB group had greater risk of all-cause mortality (HR, 2.5 [95% CI, 1.2-5.2]). These observations were validated in a pooled analysis that included patients from the INSPIRE trial.

CONCLUSIONS

Prospective clinical trials are needed to evaluate whether angiotensin modulators may be beneficial to clinical outcomes in IPF.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT01366209, NCT00287716, NCT00287729, NCT00075998; URL: www.clinicaltrials.gov).

Towards better definition, quantification and treatment of fibrosis in heart failure. A scientific roadmap by the Committee of Translational Research of the Heart Failure Association (HFA) of the European Society of Cardiology

Fibrosis is a pivotal player in heart failure development and progression. Measurements of (markers of) fibrosis in tissue and blood may help to diagnose and risk stratify patients with heart failure, and its treatment may be effective in preventing heart failure and its progression. A lack of pathophysiological insights and uniform definitions has hampered the research in fibrosis and heart failure. The Translational Research Committee of the Heart Failure Association discussed several aspects of fibrosis in their workshop. Early insidious perturbations such as subclinical hypertension or inflammation may trigger first fibrotic events, while more dramatic triggers such as myocardial infarction

and myocarditis give rise to full blown scar formation and ongoing fibrosis in diseased hearts. Aging itself is also associated with a cardiac phenotype that includes fibrosis. Fibrosis is an extremely heterogeneous phenomenon, as several stages of the fibrotic process exist, each with different fibrosis subtypes and a different composition of various cells and proteins — resulting in a very complex pathophysiology. As a result, detection of fibrosis, e.g. using current cardiac imaging modalities or plasma biomarkers, will detect only specific subforms of fibrosis, but cannot capture all aspects of the complex fibrotic process. Furthermore, several anti‐fibrotic therapies are under investigation, but such therapies generally target aspecific aspects of the fibrotic process and suffer from a lack of precision. This review discusses the mechanisms and the caveats and proposes a roadmap for future research.

Long-Term Regulation of Excitation-Contraction Coupling and Oxidative Stress in Cardiac Myocytes by Pirfenidone

Pirfenidone (PFD) is used to treat human pulmonary fibrosis. Its administration to animals with distinct forms of cardiovascular disease results in striking improvement in cardiac performance. Here, its functional impact on cardiac myocytes was investigated. Cells were kept 1–2 days under either control culture conditions or the presence of PFD (1 mM). Subsequently, they were subjected to electrical stimulation to assess the levels of contractility and intracellular Ca²⁺. The PFD treatment promoted an increase in both peak contraction and kinetics of shortening and relaxation. Moreover, the amplitude and kinetics of Ca²⁺ transients were enhanced as well. Excitation–contraction coupling (ECC) was also investigated, under whole-cell patch-clamp conditions. In keeping with a previous report, PFD increased twofold the density of Ca²⁺ current (I_Ca). Notably, a similar increase in the magnitude of Ca²⁺ transients was also observed. Thus, the gain of ECC was unaltered. Likewise, PFD did not alter the peak amplitude of caffeine-induced Ca²⁺ release, indicating stimulation of Ca²⁺-induced–Ca²⁺-release (CICR) at constant sarcoplasmic reticulum Ca²⁺ load. A phase-plane analysis indicated that PFD promotes myofilament Ca²⁺ desensitization, which is being compensated by higher levels of Ca²⁺ to promote contraction. Interestingly, although the expression of the Na⁺/Ca²⁺ exchanger (NCX) was unaffected, the decay of Ca²⁺ signal in the presence of caffeine was 50% slower in PFD-treated cells (compared with controls), suggesting that PFD downregulates the activity of the exchanger. PFD also inhibited the production of reactive oxygen species, under both, basal conditions and the presence of oxidative insults (acetaldehyde and peroxide hydrogen). Conversely, the production of nitric oxide was either increased (in atrial myocytes) or remained unchanged (in ventricular myocytes). Protein levels of endothelial and neuronal nitric oxide synthases (eNOS and nNOS) were also investigated. eNOS values did not exhibit significant changes. By contrast, a dual regulation was observed for nNOS, which consisted of inhibition and stimulation, in ventricular and atrial myocytes, respectively. In the latter cells, therefore, an up-regulation of nNOS was sufficient to stimulate the synthesis of NO. These findings improve our knowledge of molecular mechanisms of PFD action and may also help in explaining the corresponding cardioprotective effects.

Modulation of subsets of cardiac B lymphocytes improves cardiac function after acute injury

Despite the long-standing recognition that the immune response to acute myocardial injury contributes to adverse left ventricular (LV) remodeling, it has not been possible to effectively target this clinically. Using 2 different in vivo models of acute myocardial injury, we show that pirfenidone confers beneficial effects in the murine heart through an unexpected mechanism that depends on cardiac B lymphocytes. Naive hearts contained a large population of CD19+CD11b-CD23-CD21-IgD+IgMlo lymphocytes, and 2 smaller populations of CD19+CD11b+ B1a and B1b cells. In response to tissue injury, there was an increase in neutrophils, monocytes, macrophages, as well as an increase in CD19+ CD11b- B lymphocytes. Treatment with pirfenidone had no effect on the number of neutrophils, monocytes, or macrophages, but decreased CD19+CD11b- lymphocytes. B cell depletion abrogated the beneficial effects of pirfenidone. In vitro studies demonstrated that stimulation with lipopolysaccharide and extracts from necrotic cells activated CD19+ lymphocytes through a TIRAP-dependent pathway. Treatment with pirfenidone attenuated this activation of B cells. These findings reveal a previously unappreciated complexity of myocardial B lymphocytes within the inflammatory infiltrate triggered by cardiac injury and suggest that pirfenidone exerts beneficial effects in the heart through a unique mechanism that involves modulation of cardiac B lymphocytes.

αv integrins on mesenchymal cells regulate skeletal and cardiac muscle fibrosis

Mesenchymal cells expressing platelet-derived growth factor receptor beta (PDGFRβ) are known to be important in fibrosis of organs such as the liver and kidney. Here we show that PDGFRβ+ cells contribute to skeletal muscle and cardiac fibrosis via a mechanism that depends on αv integrins. Mice in which αv integrin is depleted in PDGFRβ+ cells are protected from cardiotoxin and laceration-induced skeletal muscle fibrosis and angiotensin II-induced cardiac fibrosis. In addition, a small-molecule inhibitor of αv integrins attenuates fibrosis, even when pre-established, in both skeletal and cardiac muscle, and improves skeletal muscle function. αv integrin blockade also reduces TGFβ activation in primary human skeletal muscle and cardiac PDGFRβ+ cells, suggesting that αv integrin inhibitors may be effective for the treatment and prevention of a broad range of muscle fibroses.

Macrophage-derived exosomes induce inflammatory factors in endothelial cells under hypertensive conditions

Hypertension is one of the most important cardiovascular risk factors and results in macrophage infiltration of blood vessels. However, how macrophages coordinate inflammatory responses with endothelial cells (ECs) remains unclear. In this study, we investigated whether exosomes upregulate the expression of inflammatory factors in ECs under hypertensive conditions. Hypertension was induced in rats by continuous infusion of angiotensin II (Ang II). Exosomes were purified from rat serum by density gradient and ultracentrifugation and used to stimulate human coronary artery ECs (HCAECs). Moreover, the interactions between HCAECs and exosomes from human THP-1-derived macrophages were analyzed. Administration of Ang II enhanced the expression of CD68, a macrophage marker, in rat hearts, suggesting enhanced infiltration of macrophages. In addition, the expression of intracellular adhesion molecule-1 (ICAM1) and plasminogen activator inhibitor-1 (PAI-1), a proinflammatory factor, was increased in hypertensive rat hearts compared with control rats. CD68 protein expression and an increase in the expression of some exosome markers were detected in exosomes from hypertensive rat serum. Moreover, the exosomes upregulated the expression levels of ICAM1 and PAI-1 in HCAECs. The level of miR-17, a negative regulator of ICAM1 expression, was markedly decreased in exosomes from hypertensive rat serum compared with exosomes from control rats. Interestingly, Ang II-stimulated THP-1-derived exosomes also enhanced the expression of ICAM1 and PAI-1 and contained reduced levels of miR-17 compared with exosomes from unstimulated cells. These results suggest that inflammation of ECs under hypertensive conditions is caused, at least in part, by macrophage-derived exosomes.

Novel Therapeutic Strategies for Reducing Right Heart Failure Associated Mortality in Fibrotic Lung Diseases

Fibrotic lung diseases carry a significant mortality burden worldwide. A large proportion of these deaths are due to right heart failure and pulmonary hypertension. Underlying contributory factors which appear to play a role in the mechanism of progression of right heart dysfunction include chronic hypoxia, defective calcium handling, hyperaldosteronism, pulmonary vascular alterations, cyclic strain of pressure and volume changes, elevation of circulating TGF-β, and elevated systemic NO levels. Specific therapies targeting pulmonary hypertension include calcium channel blockers, endothelin (ET-1) receptor antagonists, prostacyclin analogs, phosphodiesterase type 5 (PDE5) inhibitors, and rho-kinase (ROCK) inhibitors. Newer antifibrotic and anti-inflammatory agents may exert beneficial effects on heart failure in idiopathic pulmonary fibrosis. Furthermore, right ventricle-targeted therapies, aimed at mitigating the effects of functional right ventricular failure, include β-adrenoceptor (β-AR) blockers, angiotensin-converting enzyme (ACE) inhibitors, antioxidants, modulators of metabolism, and 5-hydroxytryptamine-2B (5-HT2B) receptor antagonists. Newer nonpharmacologic modalities for right ventricular support are increasingly being implemented. Early, effective, and individualized therapy may prevent overt right heart failure in fibrotic lung disease leading to improved outcomes and quality of life.

Role and New Insights of Pirfenidone in Fibrotic Diseases

Pirfenidone (PFD) is a non-peptide synthetic molecule issued as a broad-spectrum anti-fibrotic drug with the ability to decrease TGF-β1, TNF-α, PDGF and COL1A1 expression, which is highly related to prevent or remove excessive deposition of scar tissue in several organs. Basic and clinical evidence suggests that PFD may safely slow or inhibit the progressive fibrosis swelling after tissue injuries. Furthermore, a number of evidence suggests that this molecule will have positive effects in the treatment of other inflammatory diseases. This review contains current research in which PFD has been used as the treatment of several diseases, and focus mainly in the outcomes related to improve inflammation and fibrogenesis. Therefore, the main goal of this review is to focus on the novel findings of PFD efficacy rather than deepen in the chemical aspects of the molecule.

Pirfenidone exhibits cardioprotective effects by regulating myocardial fibrosis and vascular permeability in pressure-overloaded hearts

Although cardiac fibrosis causes heart failure, its molecular mechanisms remain elusive. In this study, we investigated the mechanisms of cardiac fibrosis and examined the effects of the antifibrotic drug pirfenidone (PFD) on chronic heart failure. To understand the responsible mechanisms, we generated an in vivo pressure-overloaded heart failure model via transverse aortic constriction (TAC) and examined the effects of PFD on chronic-phase cardiac fibrosis and function. In the vehicle group, contractile dysfunction and left ventricle fibrosis progressed further from 4 to 8 wk after TAC but were prevented by PFD treatment beginning 4 wk after TAC. We isolated cardiac fibroblasts and vascular endothelial cells from the left ventricles of adult male mice and investigated the cell-type-specific effects of PFD. Transforming growth factor-β induced upregulated collagen 1 expression via p38 phosphorylation and downregulated claudin 5 (Cldn5) expression in cardiac fibroblasts and endothelial cells, respectively; both processes were inhibited by PFD. Moreover, PFD inhibited changes in the collagen 1 and Cldn5 expression levels, resulting in reduced fibrosis and serum albumin leakage into the interstitial space during the chronic phase in TAC hearts. In conclusion, PFD inhibited cardiac fibrosis by suppressing both collagen expression and the increased vascular permeability induced by pressure overload.

Percutaneous carbon dioxide mist treatment has protective effects in experimental myocardial infarction

Percutaneous treatment with carbon dioxide (CO2) mist, CO2 gas dissolved in water, contributes to improved cardiac function after myocardial infarction (MI). In this study, we investigated the effects of repeated pretreatment with CO2 mist on cardiac dysfunction after MI. The CO2 mist was generated by a dry mist production unit. The whole body of rats below the axilla was wrapped in a polyethylene bag, which was sealed and filled with the CO2 mist in the draft cabinet for 30 min daily for 7 days. MI was induced by ligation of the coronary artery in untreated (UT), CO2 gas-pretreated (CG), and CO2 mist-pretreated (CM) rats. The infarct size and the increase in oxidative stress due to MI were significantly smaller in the CM rats than in the UT rats. Furthermore, the expression of inflammation-related genes, such as monocyte chemoattractant protein-1, and fibrosis-related genes, such as transforming growth factor-β1, was significantly suppressed in the CM rats. The CM rats had a better left ventricular ejection fraction than the UT rats 7 days after MI. These parameters in the CG rats were the same as in the UT group. Thus, CO2 mist preparative treatment may be potentially useful for the reduction of MI.

Fluorofenidone-loaded PLGA microspheres for targeted treatment of paraquat-induced acute lung injury in rats

Lung-targeting fluorofenidone (AKF) loaded PLGA microspheres (AKF-MS) for the treatment of paraquat (PQ)-induced acute lung injury in rats, were constructed by a solvent evaporation method.

Novel therapeutic targets in the management of atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia, contributing to increased morbidity and reduced survival through its associations with stroke and heart failure. AF contributes to a four- to fivefold increase in the risk of stroke in the general population and is responsible for 10-15 % of all ischemic strokes. Diagnosis and treatment of AF require considerable health care resources. Current therapies to restore sinus rhythm in AF are suboptimal and are limited either by their pro-arrhythmic effects or by their procedure-related complications. These limitations have necessitated identification of newer therapeutic targets to expand the treatment options. There has been a considerable amount of research interest in investigating the mechanisms of initiation and propagation of AF. Despite extensive research focused on the pathogenesis of AF, a thorough understanding of various pathways mediating initiation and propagation of AF still remains limited. Research efforts focused on the identification of these pathways and molecular mediators have generated a great degree of interest for developing more targeted therapies. This review discusses the potential therapeutic targets and the results from experimental and clinical research investigating these targets.

Repeated remote ischemic conditioning attenuates left ventricular remodeling via exosome-mediated intercellular communication on chronic heart failure after myocardial infarction

BACKGROUND

Remote ischemic conditioning (RIC) by repeated treatment of transient limb ischemia is a clinically applicable method for protecting the heart against injury at the time of reperfusion. In this study, we investigated the effects of repeated RIC on cardiac dysfunction after myocardial infarction (MI).

METHODS AND RESULTS

At 4weeks after MI, rats were separated into the untreated (UT) group or the RIC-treated group. RIC treatment was performed by 5cycles of 5min of bilateral hindlimb ischemia and 5min of reperfusion once a day for 4weeks. Despite comparable MI size, left ventricular (LV) ejection fraction (LVEF) was significantly improved in the RIC group compared with the UT group. Furthermore, the LVEF in the RIC group was improved, although not significantly, after treatment. RIC treatment also prevented the deterioration of LV diastolic function. MI-induced LV interstitial fibrosis in the boundary region and oxidant stress were significantly attenuated by RIC treatment. MicroRNA-29a (miR-29a), a key regulator of tissue fibrosis, was highly expressed in the exosomes and the marginal area of the RIC group. Even in the differentiated C2C12-derived exosomes, miR-29a expression was significantly increased under hypoxic condition. As well as miR-29a, insulin-like growth factor 1 receptor (IGF-1R) was highly expressed both in the exosomes and remote non-infarcted myocardium of the RIC group. IGF-1R expression was also increased in the C2C12-derived exosomes under hypoxic conditions.

CONCLUSIONS

Repeated RIC reduces adverse LV remodeling and oxidative stress by MI. Exosome-mediated intercellular communication may contribute to the beneficial effect of RIC treatment.

Functional and structural impact of pirfenidone on the alterations of cardiac disease and diabetes mellitus

A synthetic compound, termed pirfenidone (PFD), is considered promising for the treatment of cardiac disease. It leads to beneficial effects in animal models of diabetes mellitus (DM); as well as in heart attack, atrial fibrillation, muscular dystrophy, and diabetic cardiomyopathy (DC). The latter is a result of alterations linked to metabolic syndrome as they promote cardiac hypertrophy, fibrosis and contractile dysfunction. Although reduced level of fibrosis and stiffness represent an essential step in the mechanism of PFD action, a wide range of functional effects might also contribute to the therapeutic benefits. For example, PFD stimulates L-type voltage-gated Ca(2+) channels (LTCCs), which are pivotal for a process known as excitation-contraction coupling (ECC). Recent evidence suggests that these two types of actions - namely structural and functional - aid in treating both cardiac disease and DM. This view is supported by the fact that in DC, for example, systolic dysfunction arises from both cardiac stiffness linked to fibrosis and down-regulation of ECC. Thus, not surprisingly, clinical trials have been conducted with PFD in the settings of DM, for treating not only cardiac but also renal disease. This review presents all these concepts, along with the possible mechanisms and pathophysiological consequences.

Tolvaptan attenuates left ventricular fibrosis after acute myocardial infarction in rats

Tolvaptan, a non-peptide V2-receptor antagonist, is a newly developed diuretic agent. Recently, we reported that tolvaptan has diuretic as well as anti-inflammatory and anti-fibrotic actions in chronic heart failure. In this study, we investigated whether tolvaptan has a cardioprotective effect in acute heart failure after myocardial infarction (MI). After MI induction, rats were randomized into 6 groups as follows: vehicle group, group treated with 15 mg∙kg⁻¹∙day⁻¹ furosemide, 2 groups treated with 3 or 10 mg∙kg⁻¹∙day⁻¹ tolvaptan, and 2 groups treated with 15 mg∙kg⁻¹∙day⁻¹ furosemide combined with 3 or 10 mg∙kg⁻¹∙day⁻¹ tolvaptan. Each agent was administered for 2 weeks, and blood pressure levels and infarct sizes were similar in all MI groups. Lower left ventricular end-systolic volumes and greater improvement of left ventricular ejection fraction were observed in the tolvaptan-treated groups compared with the vehicle group. In contrast, furosemide alone did not improve them. Sirius red staining revealed that tolvaptan significantly repressed MI-induced interstitial fibrosis in the left ventricle. MI-induced mRNA expressions related to cardiac load, inflammation, and fibrosis were significantly attenuated in the combination group. The combination treatment also repressed MI-induced mineralocorticoid receptor expression. Tolvaptan, or combination of furosemide and tolvaptan, may improve cardiac function in acute MI.