Fibrosis Rescue Improves Cardiac Function in Dystrophin-Deficient Mice and Duchenne Patient-Specific Cardiomyocytes by Immunoproteasome Modulation

Fibrotic extracellular matrix impacts cardiomyocyte phenotype and function in an iPSC-derived isogenic model of cardiac fibrosis

Cardiac fibrosis occurs following insults to the myocardium and is characterized by the abnormal accumulation of non-compliant extracellular matrix (ECM), which compromises cardiomyocyte contractile activity and eventually leads to heart failure. This phenomenon is driven by the activation of cardiac fibroblasts (cFbs) to myofibroblasts and results in changes in ECM biochemical, structural and mechanical properties. The lack of predictive in vitro models of heart fibrosis has so far hampered the search for innovative treatments, as most of the cellular-based in vitro reductionist models do not take into account the leading role of ECM cues in driving the progression of the pathology. Here, we devised a single-step decellularization protocol to obtain and thoroughly characterize the biochemical and micro-mechanical properties of the ECM secreted by activated cFbs differentiated from human induced pluripotent stem cells (iPSCs). We activated iPSC-derived cFbs to the myofibroblast phenotype by tuning basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-β1) signalling and confirmed that activated cells acquired key features of myofibroblast phenotype, like SMAD2/3 nuclear shuttling, the formation of aligned alpha-smooth muscle actin (α-SMA)-rich stress fibres and increased focal adhesions (FAs) assembly. Next, we used Mass Spectrometry, nanoindentation, scanning electron and confocal microscopy to unveil the characteristic composition and the visco-elastic properties of the abundant, collagen-rich ECM deposited by cardiac myofibroblasts in vitro. Finally, we demonstrated that the fibrotic ECM activates mechanosensitive pathways in iPSC-derived cardiomyocytes, impacting on their shape, sarcomere assembly, phenotype, and calcium handling properties. We thus propose human bio-inspired decellularized matrices as animal-free, isogenic cardiomyocyte culture substrates recapitulating key pathophysiological changes occurring at the cellular level during cardiac fibrosis.

The role of the immunoproteasome in cardiovascular disease

The ubiquitinproteasome system (UPS) is the main mechanism responsible for the intracellular degradation of misfolded or damaged proteins. Under inflammatory conditions, the immunoproteasome, an isoform of the proteasome, can be induced, enhancing the antigen-presenting function of the UPS. Furthermore, the immunoproteasome also serves nonimmune functions, such as maintaining protein homeostasis and regulating signalling pathways, and is involved in the pathophysiological processes of various cardiovascular diseases (CVDs). This review aims to provide a comprehensive summary of the current research on the involvement of the immunoproteasome in cardiovascular diseases, with the ultimate goal of identifying novel strategies for the treatment of these conditions.

Ryanodine receptor dysfunction causes senescence and fibrosis in Duchenne dilated cardiomyopathy

BACKGROUND

Duchenne muscular dystrophy (DMD) is an X-linked disorder characterized by progressive muscle weakness due to the absence of functional dystrophin. DMD patients also develop dilated cardiomyopathy (DCM). We have previously shown that DMD (mdx) mice and a canine DMD model (GRMD) exhibit abnormal intracellular calcium (Ca2+) cycling related to early-stage pathological remodelling of the ryanodine receptor intracellular calcium release channel (RyR2) on the sarcoplasmic reticulum (SR) contributing to age-dependent DCM.

METHODS

Here, we used hiPSC-CMs from DMD patients selected by Speckle-tracking echocardiography and canine DMD cardiac biopsies to assess key early-stage Duchenne DCM features.

RESULTS

Dystrophin deficiency was associated with RyR2 remodelling and SR Ca2+ leak (RyR2 Po of 0.03 ± 0.01 for HC vs. 0.16 ± 0.01 for DMD, P < 0.01), which led to early-stage defects including senescence. We observed higher levels of senescence markers including p15 (2.03 ± 0.75 for HC vs. 13.67 ± 5.49 for DMD, P < 0.05) and p16 (1.86 ± 0.83 for HC vs. 10.71 ± 3.00 for DMD, P < 0.01) in DMD hiPSC-CMs and in the canine DMD model. The fibrosis was increased in DMD hiPSC-CMs. We observed cardiac hypocontractility in DMD hiPSC-CMs. Stabilizing RyR2 pharmacologically by S107 prevented most of these pathological features, including the rescue of the contraction amplitude (1.65 ± 0.06 μm for DMD vs. 2.26 ± 0.08 μm for DMD + S107, P < 0.01). These data were confirmed by proteomic analyses, in particular ECM remodelling and fibrosis.

CONCLUSIONS

We identified key cellular damages that are established earlier than cardiac clinical pathology in DMD patients, with major perturbation of the cardiac ECC. Our results demonstrated that cardiac fibrosis and premature senescence are induced by RyR2 mediated SR Ca2+ leak in DMD cardiomyocytes. We revealed that RyR2 is an early biomarker of DMD-associated cardiac damages in DMD patients. The progressive and later DCM onset could be linked with the RyR2-mediated increased fibrosis and premature senescence, eventually causing cell death and further cardiac fibrosis in a vicious cycle leading to further hypocontractility as a major feature of DCM. The present study provides a novel understanding of the pathophysiological mechanisms of the DMD-induced DCM. By targeting RyR2 channels, it provides a potential pharmacological treatment.

Cardiac proteostasis in obesity and cardiovascular disease

Cardiovascular diseases (CVD) are closely linked to protein homeostasis (proteostasis) and its failure. Beside genetic mutations that impair cardiac protein quality control, obesity is a strong risk factor for heart disease. In obesity, adipose tissue becomes dysfunctional and impacts heart function and CVD progression by releasing cytokines that contribute to systemic insulin resistance and cardiovascular dysfunction. In addition, chronic inflammation and lipotoxicity compromise endoplasmic reticulum (ER) function, eliciting stress responses that overwhelm protein quality control beyond its capacity. Impairment of proteostasis-including dysfunction of the ubiquitin-proteasome system (UPS), autophagy, and the depletion of chaperones-is intricately linked to cardiomyocyte dysfunction. Interventions targeting UPS and autophagy pathways are new potential strategies for re-establishing protein homeostasis and improving heart function. Additionally, lifestyle modifications such as dietary interventions and exercise have been shown to promote cardiac proteostasis and overall metabolic health. The pursuit of future research dedicated to proteostasis and protein quality control represents a pioneering approach for enhancing cardiac health and addressing the complexities of obesity-related cardiac dysfunction.

Modeling Duchenne Muscular Dystrophy Cardiomyopathy with Patients' Induced Pluripotent Stem-Cell-Derived Cardiomyocytes

Duchenne muscular dystrophy (DMD) is an X-linked progressive muscle degenerative disease caused by mutations in the dystrophin gene, resulting in death by the end of the third decade of life at the latest. A key aspect of the DMD clinical phenotype is dilated cardiomyopathy, affecting virtually all patients by the end of the second decade of life. Furthermore, despite respiratory complications still being the leading cause of death, with advancements in medical care in recent years, cardiac involvement has become an increasing cause of mortality. Over the years, extensive research has been conducted using different DMD animal models, including the mdx mouse. While these models present certain important similarities to human DMD patients, they also have some differences which pose a challenge to researchers. The development of somatic cell reprograming technology has enabled generation of human induced pluripotent stem cells (hiPSCs) which can be differentiated into different cell types. This technology provides a potentially endless pool of human cells for research. Furthermore, hiPSCs can be generated from patients, thus providing patient-specific cells and enabling research tailored to different mutations. DMD cardiac involvement has been shown in animal models to include changes in gene expression of different proteins, abnormal cellular Ca²⁺ handling, and other aberrations. To gain a better understanding of the disease mechanisms, it is imperative to validate these findings in human cells. Furthermore, with the recent advancements in gene-editing technology, hiPSCs provide a valuable platform for research and development of new therapies including the possibility of regenerative medicine. In this article, we review the DMD cardiac-related research performed so far using human hiPSCs-derived cardiomyocytes (hiPSC-CMs) carrying DMD mutations.

Immunoproteasome Inhibition Ameliorates Aged Dystrophic Mouse Muscle Environment

Muscle wasting is a major pathological feature observed in Duchenne muscular dystrophy (DMD) and is the result of the concerted effects of inflammation, oxidative stress and cell senescence. The inducible form of proteasome, or immunoproteasome (IP), is involved in all the above mentioned processes, regulating antigen presentation, cytokine production and immune cell response. IP inhibition has been previously shown to dampen the altered molecular, histological and functional features of 3-month-old mdx mice, the animal model for DMD. In this study, we described the role of ONX-0914, a selective inhibitor of the PSMB8 subunit of immunoproteasome, in ameliorating the pathological traits that could promote muscle wasting progression in older, 9-month-old mdx mice. ONX-0914 reduces the number of macrophages and effector memory T cells in muscle and spleen, while increasing the number of regulatory T cells. It modulates inflammatory markers both in skeletal and cardiac muscle, possibly counteracting heart remodeling and hypertrophy. Moreover, it buffers oxidative stress by improving mitochondrial efficiency. These changes ultimately lead to a marked decrease of fibrosis and, potentially, to more controlled myofiber degeneration/regeneration cycles. Therefore, ONX-0914 is a promising molecule that may slow down muscle mass loss, with relatively low side effects, in dystrophic patients with moderate to advanced disease.

Inhibition of the immunoproteasome modulates innate immunity to ameliorate muscle pathology of dysferlin-deficient BlAJ mice

Muscle repair in dysferlinopathies is defective. Although macrophage (Mø)-rich infiltrates are prominent in damaged skeletal muscles of patients with dysferlinopathy, the contribution of the immune system to the disease pathology remains to be fully explored. Numbers of both pro-inflammatory M1 Mø and effector T cells are increased in muscle of dysferlin-deficient BlAJ mice. In addition, symptomatic BlAJ mice have increased muscle production of immunoproteasome. In vitro analyses using bone marrow-derived Mø of BlAJ mice show that immunoproteasome inhibition results in C3aR1 and C5aR1 downregulation and upregulation of M2-associated signaling. Administration of immunoproteasome inhibitor ONX-0914 to BlAJ mice rescues muscle function by reducing muscle infiltrates and fibro-adipogenesis. These findings reveal an important role of immunoproteasome in the progression of muscular dystrophy in BlAJ mouse and suggest that inhibition of immunoproteasome may produce therapeutic benefit in dysferlinopathy.

Matricellular Protein CCN5 Gene Transfer Ameliorates Cardiac and Skeletal Dysfunction in mdx/utrn (±) Haploinsufficient Mice by Reducing Fibrosis and Upregulating Utrophin Expression

Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration due to dystrophin gene mutations. Patients with DMD initially experience muscle weakness in their limbs during adolescence. With age, patients develop fatal respiratory and cardiac dysfunctions. During the later stages of the disease, severe cardiac fibrosis occurs, compromising cardiac function. Previously, our research showed that the matricellular protein CCN5 has antifibrotic properties. Therefore, we hypothesized that CCN5 gene transfer would ameliorate cardiac fibrosis and thus improve cardiac function in DMD-induced cardiomyopathy. We utilized mdx/utrn (±) haploinsufficient mice that recapitulated the DMD-disease phenotypes and used an adeno-associated virus serotype-9 viral vector for CCN5 gene transfer. We evaluated the onset of cardiac dysfunction using echocardiography and determined the experimental starting point in 13-month-old mice. Two months after CCN5 gene transfer, cardiac function was significantly enhanced, and cardiac fibrosis was ameliorated. Additionally, running performance was improved in CCN5 gene-transfected mice. Furthermore, in silico gene profiling analysis identified utrophin as a novel transcriptional target of CCN5. This was supplemented by a utrophin promoter assay and RNA-seq analysis, which confirmed that CCN5 was directly associated with utrophin expression. Our results showed that CCN5 may be a promising therapeutic molecule for DMD-induced cardiac and skeletal dysfunction.

Therapeutic Application of Extracellular Vesicles-Capsulated Adeno-Associated Virus Vector via nSMase2/Smpd3, Satellite, and Immune Cells in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is caused by loss-of-function mutations in the dystrophin gene on chromosome Xp21. Disruption of the dystrophin-glycoprotein complex (DGC) on the cell membrane causes cytosolic Ca2+ influx, resulting in protease activation, mitochondrial dysfunction, and progressive myofiber degeneration, leading to muscle wasting and fragility. In addition to the function of dystrophin in the structural integrity of myofibers, a novel function of asymmetric cell division in muscular stem cells (satellite cells) has been reported. Therefore, it has been suggested that myofiber instability may not be the only cause of dystrophic degeneration, but rather that the phenotype might be caused by multiple factors, including stem cell and myofiber functions. Furthermore, it has been focused functional regulation of satellite cells by intracellular communication of extracellular vesicles (EVs) in DMD pathology. Recently, a novel molecular mechanism of DMD pathogenesis-circulating RNA molecules-has been revealed through the study of target pathways modulated by the Neutral sphingomyelinase2/Neutral sphingomyelinase3 (nSMase2/Smpd3) protein. In addition, adeno-associated virus (AAV) has been clinically applied for DMD therapy owing to the safety and long-term expression of transduction genes. Furthermore, the EV-capsulated AAV vector (EV-AAV) has been shown to be a useful tool for the intervention of DMD, because of the high efficacy of the transgene and avoidance of neutralizing antibodies. Thus, we review application of AAV and EV-AAV vectors for DMD as novel therapeutic strategy.

Preventing Cardiomyopathy in DMD: A Randomized Placebo-Controlled Drug Trial

Objective

To determine whether a combination of 2 heart medications would be tolerated and could prevent/delay the onset of cardiomyopathy in boys with Duchenne muscular dystrophy (DMD) compared with placebo.

Methods

This multicenter, parallel group, 1:1 patient randomized, placebo-controlled study of prophylactic perindopril and bisoprolol recruited boys with DMD aged 5-13 years, with normal ventricular function. Repeat assessments of left ventricular (LV) function, electrocardiogram, and adverse event reporting were performed 6 monthly. The primary outcome was change in ejection fraction between arms after 36 months. The study was approved by the National Research Ethics Service Committee East Midlands-Derby.

Results

Eighty-five boys were recruited (76% on steroid therapy) and randomized to combination heart drugs or matched placebo. Group change in left ventricular ejection fraction (LVEF%) at 36 months from baseline was -2.2% ± 6.0% and -2.9% ± 6.1% in active and placebo arms (adjusted mean difference: -2.1, 95% CI -5.2 to 1.1). There was no difference between treatment arms over repeated assessments (analysis of variance) up to 36 months (trial arms p = 0.53); arm-over-time (p = 0.44). Four participants on placebo but none on active therapy were withdrawn due to deteriorations in LV function. Secondary outcomes did not differ between arms either. Thirty-six serious adverse events occurred none due to cardiac events or trial medication.

Conclusions

Combination therapy was well tolerated. Consistent with the previous prophylactic perindopril heart study, there was no evidence of group benefit after 36-month treatment.

Classification of Evidence

This study provides Class I evidence that combination perindopril-bisoprolol therapy was well tolerated but did not change decline in LVEF significantly in boys with DMD.

Systemically Administered Homing Peptide Targets Dystrophic Lesions and Delivers Transforming Growth Factor-β (TGFβ) Inhibitor to Attenuate Murine Muscular Dystrophy Pathology

Muscular dystrophy is a progressively worsening and lethal disease, where accumulation of functionality-impairing fibrosis plays a key pathogenic role. Transforming growth factor-β1 (TGFβ1) is a central signaling molecule in the development of fibrosis in muscular dystrophic humans and mice. Inhibition of TGFβ1 has proven beneficial in mouse models of muscular dystrophy, but the global strategies of TGFβ1 inhibition produce significant detrimental side effects. Here, we investigated whether murine muscular dystrophy lesion-specific inhibition of TGFβ1 signaling by the targeted delivery of therapeutic decorin (a natural TGFβ inhibitor) by a vascular homing peptide CAR (CARSKNKDC) would reduce skeletal muscle fibrosis and pathology and increase functional characteristics of skeletal muscle. We demonstrate that CAR peptide homes to dystrophic lesions with specificity in two muscular dystrophy models. Recombinant fusion protein consisting of CAR peptide and decorin homes selectively to sites of skeletal muscle damage in mdxDBA2/J and gamma-sarcoglycan deficient DBA2/J mice. This targeted delivery reduced TGFβ1 signaling as demonstrated by reduced nuclear pSMAD staining. Three weeks of targeted decorin treatment decreased both membrane permeability and fibrosis and improved skeletal muscle function in comparison to control treatments in the mdxD2 mice. These results show that selective delivery of decorin to the sites of skeletal muscle damage attenuates the progression of murine muscular dystrophy.

Application of Patient-Specific iPSCs for Modelling and Treatment of X-Linked Cardiomyopathies

Inherited cardiomyopathies are among the major causes of heart failure and associated with significant mortality and morbidity. Currently, over 70 genes have been linked to the etiology of various forms of cardiomyopathy, some of which are X-linked. Due to the lack of appropriate cell and animal models, it has been difficult to model these X-linked cardiomyopathies. With the advancement of induced pluripotent stem cell (iPSC) technology, the ability to generate iPSC lines from patients with X-linked cardiomyopathy has facilitated in vitro modelling and drug testing for the condition. Nonetheless, due to the mosaicism of the X-chromosome inactivation, disease phenotypes of X-linked cardiomyopathy in heterozygous females are also usually more heterogeneous, with a broad spectrum of presentation. Recent advancements in iPSC procedures have enabled the isolation of cells with different lyonisation to generate isogenic disease and control cell lines. In this review, we will summarise the current strategies and examples of using an iPSC-based model to study different types of X-linked cardiomyopathy. The potential application of isogenic iPSC lines derived from a female patient with heterozygous Danon disease and drug screening will be demonstrated by our preliminary data. The limitations of an iPSC-derived cardiomyocyte-based platform will also be addressed.

Therapeutic aspects of cell signaling and communication in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a devastating chromosome X-linked disease that manifests predominantly in progressive skeletal muscle wasting and dysfunctions in the heart and diaphragm. Approximately 1/5000 boys and 1/50,000,000 girls suffer from DMD, and to date, the disease is incurable and leads to premature death. This phenotypic severity is due to mutations in the DMD gene, which result in the absence of functional dystrophin protein. Initially, dystrophin was thought to be a force transducer; however, it is now considered an essential component of the dystrophin-associated protein complex (DAPC), viewed as a multicomponent mechanical scaffold and a signal transduction hub. Modulating signal pathway activation or gene expression through epigenetic modifications has emerged at the forefront of therapeutic approaches as either an adjunct or stand-alone strategy. In this review, we propose a broader perspective by considering DMD to be a disease that affects myofibers and muscle stem (satellite) cells, as well as a disorder in which abrogated communication between different cell types occurs. We believe that by taking this systemic view, we can achieve safe and holistic treatments that can restore correct signal transmission and gene expression in diseased DMD tissues.

TAK1 inhibition improves myoblast differentiation and alleviates fibrosis in a mouse model of Duchenne muscular dystrophy

BACKGROUND

Transforming growth factor-β-activated kinase 1 (TAK1) plays a key role in regulating fibroblast and myoblast proliferation and differentiation. However, the TAK1 changes associated with Duchenne muscular dystrophy (DMD) are poorly understood, and it remains unclear how TAK1 regulation could be exploited to aid the treatment of this disease.

METHODS

Muscle biopsies were obtained from control donors or DMD patients for diagnosis (n = 6 per group, male, 2-3 years, respectively). Protein expression of phosphorylated TAK1 was measured by western blot and immunofluorescence analysis. In vivo overexpression of TAK1 was performed in skeletal muscle to assess whether TAK1 is sufficient to induce or aggravate atrophy and fibrosis. To explore whether TAK1 inhibition protects against muscle damage, mdx (loss of dystrophin) mice were treated with adeno-associated virus (AAV)-short hairpin TAK1 (shTAK1) or NG25 (a TAK1 inhibitor). Serum analysis, skeletal muscle performance and histology, muscle contractile function, and gene and protein expression were performed.

RESULTS

We found that TAK1 was activated in the dystrophic muscles of DMD patients (n = 6, +72.2%, P < 0.001), resulting in fibrosis ( +65.9% for fibronectin expression, P < 0.001) and loss of muscle fibres (-32.5%, P < 0.01). Moreover, TAK1 was activated by interleukin-1β, tumour necrosis factor-α, and transforming growth factor-β1 (P < 0.01). Overexpression of TAK1 by AAV vectors further aggravated fibrosis (n = 8, +39.6% for hydroxyproline content, P < 0.01) and exacerbated muscle wasting (-31.6%, P < 0.01) in mdx mice; however, these effects were reversed in mdx mice by treatment with AAV-short hairpin TAK1 (shTAK1) or NG25 (a TAK1 inhibitor). The molecular mechanism underlying these effects may be related to the prevention of TAK1-mediated transdifferentiation of myoblasts into fibroblasts, thereby reducing fibrosis and increasing myoblast differentiation.

CONCLUSIONS

Our findings show that TAK1 activation exacerbated fibrosis and muscle degeneration and that TAK1 inhibition can improve whole-body muscle quality and the function of dystrophic skeletal muscle. Thus, TAK1 inhibition may constitute a novel therapy for DMD.

Metformin Reverses the Enhanced Myocardial SR/ER-Mitochondria Interaction and Impaired Complex I-Driven Respiration in Dystrophin-Deficient Mice

Besides skeletal muscle dysfunction, Duchenne muscular dystrophy (DMD) exhibits a progressive cardiomyopathy characterized by an impaired calcium (Ca²⁺) homeostasis and a mitochondrial dysfunction. Here we aimed to determine whether sarco-endoplasmic reticulum (SR/ER)–mitochondria interactions and mitochondrial function were impaired in dystrophic heart at the early stage of the pathology. For this purpose, ventricular cardiomyocytes and mitochondria were isolated from 3-month-old dystrophin-deficient mice (mdx mice). The number of contacts points between the SR/ER Ca²⁺ release channels (IP3R1) and the porine of the outer membrane of the mitochondria, VDAC1, measured using in situ proximity ligation assay, was greater in mdx cardiomyocytes. Expression levels of IP3R1 as well as the mitochondrial Ca²⁺ uniporter (MCU) and its regulated subunit, MICU1, were also increased in mdx heart. MICU2 expression was however unchanged. Furthermore, the mitochondrial Ca²⁺ uptake kinetics and the mitochondrial Ca²⁺ content were significantly increased. Meanwhile, the Ca²⁺-dependent pyruvate dehydrogenase phosphorylation was reduced, and its activity significantly increased. In Ca²⁺-free conditions, pyruvate-driven complex I respiration was decreased whereas in the presence of Ca²⁺, complex I-mediated respiration was boosted. Further, impaired complex I-mediated respiration was independent of its intrinsic activity or expression, which remains unchanged but is accompanied by an increase in mitochondrial reactive oxygen species production. Finally, mdx mice were treated with the complex I modulator metformin for 1 month. Metformin normalized the SR/ER-mitochondria interaction, decreased MICU1 expression and mitochondrial Ca²⁺ content, and enhanced complex I-driven respiration. In summary, before any sign of dilated cardiomyopathy, the DMD heart displays an aberrant SR/ER-mitochondria coupling with an increase mitochondrial Ca²⁺ homeostasis and a complex I dysfunction. Such remodeling could be reversed by metformin providing a novel therapeutic perspective in DMD.

Role of the Renin-Angiotensin-Aldosterone System in Dystrophin-Deficient Cardiomyopathy

Dystrophin-deficient cardiomyopathy (DDC) is currently the leading cause of death in patients with dystrophinopathies. Targeting myocardial fibrosis (MF) has become a major therapeutic goal in order to prevent the occurrence of DDC. We aimed to review and summarize the current evidence about the role of the renin-angiotensin-aldosterone system (RAAS) in the development and perpetuation of MF in DCC. We conducted a comprehensive search of peer-reviewed English literature on PubMed about this subject. We found increasing preclinical evidence from studies in animal models during the last 20 years pointing out a central role of RAAS in the development of MF in DDC. Local tissue RAAS acts directly mainly through its main fibrotic component angiotensin II (ANG2) and its transducer receptor (AT1R) and downstream TGF-b pathway. Additionally, it modulates the actions of most of the remaining pro-fibrotic factors involved in DDC. Despite limited clinical evidence, RAAS blockade constitutes the most studied, available and promising therapeutic strategy against MF and DDC. Conclusion: Based on the evidence reviewed, it would be recommendable to start RAAS blockade therapy through angiotensin converter enzyme inhibitors (ACEI) or AT1R blockers (ARBs) alone or in combination with mineralocorticoid receptor antagonists (MRa) at the youngest age after the diagnosis of dystrophinopathies, in order to delay the occurrence or slow the progression of MF, even before the detection of any cardiovascular alteration.

Cell Clearing Systems as Targets of Polyphenols in Viral Infections: Potential Implications for COVID-19 Pathogenesis

The novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has generated the ongoing coronavirus disease-2019 (COVID-19) pandemic, still with an uncertain outcome. Besides pneumonia and acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), other features became evident in the context of COVID-19. These includes endothelial and coagulation dysfunction with disseminated intravascular coagulation (DIC), and multiple organ dysfunction syndrome (MODS), along with the occurrence of neurological alterations. The multi-system nature of such viral infection is a witness to the exploitation and impairment of ubiquitous subcellular and metabolic pathways for the sake of its life-cycle, ranging from host cell invasion, replication, transmission, up to a cytopathic effect and overt systemic inflammation. In this frame, alterations in cell-clearing systems of the host are emerging as a hallmark in the pathogenesis of various respiratory viruses, including SARS-CoV-2. Indeed, exploitation of the autophagy and proteasome pathways might contribute not only to the replication of the virus at the site of infection but also to the spreading of either mature virions or inflammatory mediators at both cellular and multisystem levels. In this frame, besides a pharmacological therapy, many researchers are wondering if some non-pharmacological substances might counteract or positively modulate the course of the infection. The pharmacological properties of natural compounds have gained increasing attention in the field of alternative and adjunct therapeutic approaches to several diseases. In particular, several naturally-occurring herbal compounds (mostly polyphenols) are reported to produce widespread antiviral, anti-inflammatory, and anti-oxidant effects while acting as autophagy and (immuno)-proteasome modulators. This article attempts to bridge the perturbation of autophagy and proteasome pathways with the potentially beneficial effects of specific phytochemicals and flavonoids in viral infections, with a focus on the multisystem SARS-CoV-2 infection.

"Betwixt Mine Eye and Heart a League Is Took": The Progress of Induced Pluripotent Stem-Cell-Based Models of Dystrophin-Associated Cardiomyopathy

The ultimate goal of precision disease modeling is to artificially recreate the disease of affected people in a highly controllable and adaptable external environment. This field has rapidly advanced which is evident from the application of patient-specific pluripotent stem-cell-derived precision therapies in numerous clinical trials aimed at a diverse set of diseases such as macular degeneration, heart disease, spinal cord injury, graft-versus-host disease, and muscular dystrophy. Despite the existence of semi-adequate treatments for tempering skeletal muscle degeneration in dystrophic patients, nonischemic cardiomyopathy remains one of the primary causes of death. Therefore, cardiovascular cells derived from muscular dystrophy patients' induced pluripotent stem cells are well suited to mimic dystrophin-associated cardiomyopathy and hold great promise for the development of future fully effective therapies. The purpose of this article is to convey the realities of employing precision disease models of dystrophin-associated cardiomyopathy. This is achieved by discussing, as suggested in the title echoing William Shakespeare's words, the settlements (or "leagues") made by researchers to manage the constraints ("betwixt mine eye and heart") distancing them from achieving a perfect precision disease model.

The ubiquitin-proteasome system in regulation of the skeletal muscle homeostasis and atrophy: from basic science to disorders

Skeletal muscle is one of the most abundant and highly plastic tissues. The ubiquitin-proteasome system (UPS) is recognised as a major intracellular protein degradation system, and its function is important for muscle homeostasis and health. Although UPS plays an essential role in protein degradation during muscle atrophy, leading to the loss of muscle mass and strength, its deficit negatively impacts muscle homeostasis and leads to the occurrence of several pathological phenotypes. A growing number of studies have linked UPS impairment not only to matured muscle fibre degeneration and weakness, but also to muscle stem cells and deficiency in regeneration. Emerging evidence suggests possible links between abnormal UPS regulation and several types of muscle diseases. Therefore, understanding of the role of UPS in skeletal muscle may provide novel therapeutic insights to counteract muscle wasting, and various muscle diseases. In this review, we focussed on the role of proteasomes in skeletal muscle and its regeneration, including a brief explanation of the structure of proteasomes. In addition, we summarised the recent findings on several diseases and elaborated on how the UPS is related to their pathological states.

Selective Inhibition of the Immunoproteasome β5i Prevents PTEN Degradation and Attenuates Cardiac Hypertrophy

Cardiac hypertrophy without appropriate treatment eventually progresses to heart failure. Our recent data demonstrated that the immunoproteasome subunit β5i promotes cardiac hypertrophy. However, whether β5i is a promising therapeutic target for treating hypertrophic remodeling remains unknown. Here, we investigated the effects of PR-957, a β5i-specific inhibitor, on angiotensin II (Ang II)-induced hypertrophic remodeling in the murine heart. The infusion of Ang II increased immunoproteasome chymotrypsin-like activity and β5i catalytic subunit expression in the heart, whereas PR-957 treatment fully blocked the enhanced immunoproteasome activity caused by Ang II. Moreover, the administration of PR-957 significantly suppressed Ang II-induced cardiac hypertrophy, fibrosis, and inflammation. Mechanistically, PR-957 treatment inhibited phosphatase and tensin homolog on chromosome ten (PTEN) degradation, thereby inhibiting multiple signals including AKT/mTOR, ERK1/2, transforming growth factor-β, and IKB/NF-kB. Furthermore, PTEN blocking by its specific inhibitor VO-OHpic markedly attenuated the inhibitory effect of PR-957 on Ang II-induced cardiac hypertrophy in mice. We conclude that PR-957 blocks PTEN degradation and activates its downstream mediators, thereby attenuating Ang II-induced cardiac hypertrophy. These findings highlight that PR-957 may be a potential therapeutic agent for Ang II-induced hypertrophic remodeling.

PTX3 Predicts Myocardial Damage and Fibrosis in Duchenne Muscular Dystrophy

Pentraxin 3 (PTX3) is a main component of the innate immune system by inducing complement pathway activation, acting as an inflammatory mediator, coordinating the functions of macrophages/dendritic cells and promoting apoptosis/necrosis. Additionally, it has been found in fibrotic regions co-localizing with collagen. In this work, we wanted to investigate the predictive role of PTX3 in myocardial damage and fibrosis of Duchenne muscular dystrophy (DMD). DMD is an X-linked recessive disease caused by mutations of the dystrophin gene that affects muscular functions and strength and accompanying dilated cardiomyopathy. Here, we expound the correlation of PTX3 cardiac expression with age and Toll-like receptors (TLRs)/interleukin-1 receptor (IL-1R)-MyD88 inflammatory markers and its modulation by the so-called alarmins IL-33, high-mobility group box 1 (HMGB1), and S100β. These findings suggest that cardiac levels of PTX3 might have prognostic value and potential in guiding therapy for DMD cardiomyopathy.

Advances in Stem Cell Modeling of Dystrophin-Associated Disease: Implications for the Wider World of Dilated Cardiomyopathy

Familial dilated cardiomyopathy (DCM) is mostly caused by mutations in genes encoding cytoskeletal and sarcomeric proteins. In the pediatric population, DCM is the predominant type of primitive myocardial disease. A severe form of DCM is associated with mutations in the DMD gene encoding dystrophin, which are the cause of Duchenne Muscular Dystrophy (DMD). DMD-associated cardiomyopathy is still poorly understood and orphan of a specific therapy. In the last 5 years, a rise of interest in disease models using human induced pluripotent stem cells (hiPSCs) has led to more than 50 original studies on DCM models. In this review paper, we provide a comprehensive overview on the advances in DMD cardiomyopathy disease modeling and highlight the most remarkable findings obtained from cardiomyocytes differentiated from hiPSCs of DMD patients. We will also describe how hiPSCs based studies have contributed to the identification of specific myocardial disease mechanisms that may be relevant in the pathogenesis of DCM, representing novel potential therapeutic targets.

2019 FDA TIDES (Peptides and Oligonucleotides) Harvest

2019 has been an excellent year in terms of peptides and oligonucleotides (TIDES) approved by the FDA. Despite the drop in the number of total drugs approved by the FDA in 2019 in comparison with 2018 (48 vs. 59), the total number of TIDES authorized increased (seven vs. three). Year after year, TIDES are increasingly present in therapy, as imaging agents, theragnostic and constituent moieties of other complex drugs, such as antibody drug conjugates. This means a consolidation of these kinds of drugs in the pharmaceutical arena, paving the way in the coming years for the approval of others for diverse medical indications. Here the TIDES approved in 2019 are analyzed in terms of chemical structure, medical target, mode of action, and adverse effects.

Establishment of a Duchenne muscular dystrophy patient-derived induced pluripotent stem cell line carrying a deletion of exons 51-53 of the dystrophin gene (CCMi003-A)

Duchenne's muscular dystrophy (DMD) is a neuromuscular disorder affecting skeletal and cardiac muscle function, caused by mutations in the dystrophin (DMD) gene. Dermal fibroblasts, isolated from a DMD patient with a reported deletion of exons 51 to 53 in the DMD gene, were reprogramed into induced pluripotent stem cells (iPSCs) by electroporation with episomal vectors containing the reprograming factors: OCT4, SOX2, LIN28, KLF4, and L-MYC. The obtained iPSC line showed iPSC morphology, expression of pluripotency markers, possessed trilineage differentiation potential and was karyotypically normal.