Inhibiting the inflammasome with MCC950 counteracts muscle pyroptosis and improves Duchenne muscular dystrophy

Background: Duchenne muscular dystrophy (DMD) is the most common inherited human myopathy. Typically, the secondary process involving severe inflammation and necrosis exacerbate disease progression. Previously, we reported that the NLRP3 inflammasome complex plays a crucial role in this disorder. Moreover, pyroptosis, a form of programmed necrotic cell death, is triggered by NLRP3 via gasdermin D (GSDMD). So far, pyroptosis has never been described either in healthy muscle or in dystrophic muscle. The aim of this study was to unravel the role of NLRP3 inflammasome in DMD and explore a potentially promising treatment with MCC950 that selectively inhibits NLRP3. Methods: Four‐week‐old mdx mice (n=6 per group) were orally treated for 2 months with MCC950 (mdx‐T), a highly potent, specific, small-molecule inhibitor of NLRP3, and compared with untreated (mdx) and wild-type (WT) mice. In vivo functional tests were carried out to measure the global force and endurance of mice. Ex vivo biochemical and molecular analyses were performed to evaluate the pathophysiology of the skeletal muscle. Finally, in vitro tests were conducted on primary cultures of DMD human myotubes. Results: After MCC950 treatment, mdx mice exhibited a significant reduction of inflammation, macrophage infiltration and oxidative stress (-20 to -65%, P<0.05 vs untreated mdx). Mdx‐T mice displayed considerably less myonecrosis (-54%, P<0.05 vs mdx) and fibrosis (-75%, P<0.01 vs mdx). Moreover, a more mature myofibre phenotype, characterized by larger-sized fibres and higher expression of mature myosin heavy chains 1 and 7 was observed. Mdx-T also exhibited enhanced force and resistance to fatigue (+20 to 60%, P<0.05 or less). These beneficial effects resulted from MCC950 inhibition of both active caspase-1 (-46%, P=0.075) and cleaved gasdermin D (N-GSDMD) (-42% in medium-sized-fibres, P<0.001). Finally, the anti-inflammatory action and the anti-pyroptotic effect of MCC950 were also recapitulated in DMD human myotubes. Conclusion: Specific inhibition of the NLRP3 inflammasome can significantly attenuate the dystrophic phenotype. A novel finding of this study is the overactivation of GSDMD, which is hampered by MCC950. This ultimately leads to less inflammation and pyroptosis and to a better muscle maturation and function. Targeting NLRP3 might lead to an effective therapeutic approach for a better management of DMD.Fund for Scientific Research de Bélgica (FNRS)-PDR/T.0026.2

Therapeutic potential of Adiponectin and AdipoRon in Duchenne Muscular Dystrophy

Adiponectin (ApN) is a hormone known to possess powerful anti-inflammatory effects on various tissues, including the skeletal muscle. Duchenne Muscular Dystrophy (DMD) is the most devastating type of muscular dystrophy. Although dystrophin mutations represent the primary cause of DMD, it is the secondary processes involving persistent inflammation and subsequent impaired regeneration that likely exacerbate disease progression. This work highlights the involvement of ApN as well as an agonist of its receptors, AdipoRon, in DMD. We show that ApN and AdipoRon markedly reduce inflammation and muscle damage while improving strength and myogenesis in a mouse model of DMD. This protection is mainly ascribed to the activation of APMK pathway after binding to AdipoR1, ApN muscle receptor. This study may offer new promising therapeutic prospects for the management of muscle inflammatory disorders and myopathies.(BIFA - Sciences biomédicales et pharmaceutiques) -- UCL, 201

Potential therapeutic action of AdipoRon in Duchenne Muscular Dystrophy

Adiponectin (ApN) is a hormone tightly linked to the metabolic syndrome where it exerts anti-diabetic actions. It is also known to possess powerful anti-inflammatory effects on skeletal muscle exposed to acute and chronic inflammation, through AdipoR1 (ApN muscle receptor) and AMPK pathway. These effects have been studied in the context of Duchenne muscular dystrophy (DMD), a disease caused by dystrophin deficiency and characterized by a progressive muscle weakness/necrosis together with a significant inflammatory component. In mdx mice, a murine model of the disease, ApN had powerful protective effects against muscle inflammation, oxidative stress and significantly improved physical performance as well as myogenesis. Therefore, ApN constitutes a new interesting therapeutic agent for the management of DMD. Recently, an orally active ApN receptor agonist, AdipoRon, has been identified. This synthetic small molecule has the advantage of being more easily produced and administrated than ApN. The aim of this work was to determine if AdipoRon has similar effects to those of ApN on the dystrophic muscle. To achieve this, we treated mdx mice daily with AdipoRon for 8 weeks. Results demonstrated that this treatment improved the physical performance of the mdx mouse and prevented the progression of the dystrophic pathology by counteracting excessive inflammation and oxidative reactions. AdipoRon also improved muscle regeneration and promoted a muscle fiber shift towards a more oxidative phenotype protecting thus the muscle membrane from mechanical damage. The anti-inflammatory properties of AdipoRon were also recapitulated in vitro in human myotubes. These results demonstrate that AdipoRon exerts beneficial effects similar to those of ApN on the dystrophic muscle, thus making it a promising therapeutic prospect for the treatment of DMD and other muscular diseases where inflammation plays an important role

Les modulateurs de la réponse immune issus du génie génétique en cours de développement (perspectives thérapeutiques en dermatologie)

CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Puissance des effets anti-inflammatoires de l’adiponectine sur le muscle squelettique

Introduction L’adiponectine, ApN est une adipokine abaissée en cas de syndrome métabolique, ce qui joue un rôle-clef dans la pathogénie de ce syndrome. Nous avons montré que l’ApN exerce d’importants effets anti-inflammatoires sur le muscle squelettique chez des souris soumises à un régime obésogène. Le but de ce travail est de tester la puissance des effets anti-inflammatoires de l’ApN en choisissant un modèle d’inflammation musculaire sévère et soutenue. Matériels et Méthodes Des souris mdx (atteintes de la myopathie de Duchenne, où l’inflammation joue un rôle aggravant la déficience génétique) ont été croisées avec des souris Tg-ApN (surexprimant l’ApN) afin de générer des souris mdx-Tg-ApN. Des marqueurs d’inflammation / stress oxydatif (TNF-α, IL-1β, NF-κB, CD68, CD3, PRDX3, PRDX5, HNE) ont été étudiés/quantifiés par immunohistochimie, ELISA et Western Blot. Ensuite, des tests fonctionnels ont déterminé la force musculaire des souris. Enfin, l’importance de l’atteinte musculaire a été quantifiée par injection d’Evans Blue Dye (EBD) après un exercice excentrique. Résultats Comparé aux souris témoins, le muscle des souris mdx présente un marquage important (+ 10 à 15 fois ; p<0,001), pour des facteurs pro-inflammatoires (TNF-α, IL-1β, NF-κB) ou de stress oxydatif (péroxyrédoxines 3/5, 4-hydroxynonénal) ainsi qu’une infiltration majeure de macrophages et de lymphocytes. Ces anomalies sont drastiquement réduites chez les souris mdx-Tg-ApN (– 60 à 75 % vs mdx ; p<0,001). Les souris mdx-Tg-ApN montrent aussi une force musculaire globale accrue (+ 50 % vs mdx ; p<0,01) ainsi qu’une quantité réduite d’EBD dans leurs fibres musculaires (– 50 à 60 % vs mdx ; p<0,001). Conclusion L’ApN se révèle un très puissant agent anti-inflammatoire sur le muscle en cas d’agression. Ces propriétés anti-inflammatoires majeures sont d’intérêt dans le syndrome métabolique ainsi que dans d’autres maladies où l’inflammation joue un rôle pathogénique initiateur ou aggravateur

Adiponectin and Its Mimics on Skeletal Muscle: Insulin Sensitizers, Fat Burners, Exercise Mimickers, Muscling Pills … or Everything Together?

Adiponectin (ApN) is a hormone abundantly secreted by adipocytes and it is known to be tightly linked to the metabolic syndrome. It promotes insulin-sensitizing, fat-burning, and anti-atherosclerotic actions, thereby effectively counteracting several metabolic disorders, including type 2 diabetes, obesity, and cardiovascular diseases. ApN is also known today to possess powerful anti-inflammatory/oxidative and pro-myogenic effects on skeletal muscles exposed to acute or chronic inflammation and injury, mainly through AdipoR1 (ApN specific muscle receptor) and AMP-activated protein kinase (AMPK) pathway, but also via T-cadherin. In this review, we will report all the beneficial and protective properties that ApN can exert, specifically on the skeletal muscle as a target tissue. We will highlight its effects and mechanisms of action, first in healthy skeletal muscle including exercised muscle, and second in diseased muscle from a variety of pathological conditions. In the end, we will go over some of AdipoRs agonists that can be easily produced and administered, and which can greatly mimic ApN. These interesting and newly identified molecules could pave the way towards future therapeutic approaches to potentially prevent or combat not only skeletal muscle disorders but also a plethora of other diseases with sterile inflammation or metabolic dysfunction

Downregulation of the NLRP3 inflammasome by adiponectin rescues Duchenne muscular dystrophy

BACKGROUND: The hormone adiponectin (ApN) exerts powerful anti-inflammatory effects on skeletal muscle and can reverse devastating myopathies, like Duchenne muscular dystrophy (DMD), where inflammation exacerbates disease progression. The NLRP3 inflammasome plays a key role in the inflammation process, and its aberrant activation leads to several inflammatory or immune diseases. Here we investigated the expression of the NLRP inflammasome in skeletal muscle and its contribution to DMD. RESULTS: We find that NLRP3 is expressed in skeletal muscle and show that ApN downregulates NLRP3 via its anti-inflammatory mediator, miR-711. This repression occurs both in vitro in C2C12 myotubes and in vivo after either local (via muscle electrotransfer) or systemic (by using transgenic mice) ApN supplementation. To explore the role of the NLRP3 inflammasome in a murine model of DMD, we crossed mdx mice with Nlrp3-knockout mice. In mdx mice, all components of the inflammasome were upregulated in muscle, and the complex was overactivated. By contrast, in mdx mice lacking Nlrp3, there was a reduction in caspase-1 activation, inflammation and oxidative stress in dystrophic muscle, and these mice showed higher global muscle force/endurance than regular mdx mice as well as decreased muscle damage. To investigate the relevance of NLPR3 regulation in a human disease context, we characterized NLRP3 expression in primary cultures of myotubes from DMD subjects and found a threefold increase compared to control subjects. This overexpression was attenuated by ApN or miR-711 mimic treatments. CONCLUSIONS: The NLRP3 inflammasome plays a key pathogenic role in DMD and muscle inflammation, thereby opening new therapeutic perspectives for these and other related disorders

Potential Therapeutic Action of Adiponectin in Duchenne Muscular Dystrophy.

Adiponectin (ApN) is a hormone that exhibits anti-inflammatory effects on skeletal muscle exposed to acute and chronic inflammation. We have previously tested the implication of ApN in Duchenne muscular dystrophy (DMD) using mdx mice, a model of DMD, and by generating transgenic mdx mice overexpressing ApN. We showed that ApN can act as a preventive agent and delay disease progression by reducing muscle inflammation/injury and improving force/myogenesis. Herein, we took an opposite approach and crossed mdx mice with ApN knockout mice, to obtain mdx mice with ApN depletion. The aims were to test whether ApN deficiency could worsen the mdx phenotype and whether ApN supplementation can reverse several muscle abnormalities once the disease is settled. mdx-knockout mice exhibited lower muscle force/endurance as well as increased muscle damage when compared to regular mdx mice. Local administration of the ApN gene significantly reduced the expression of several oxidative stress/inflammatory markers and increased the expression of myogenic markers in the skeletal muscle. Finally, the presence of ApN markedly reduced the activity of NF-κB, a key player in muscle inflammation and myogenesis. ApN proves to be a powerful protector of the skeletal muscle capable of reversing the disease progression, thus making it a potential therapeutic agent for DMD

New targets to alleviate skeletal muscle inflammation: role of microRNAs regulated by adiponectin.

Muscle inflammation worsens metabolic disorders as well as devastating myopathies. The hormone adiponectin (ApN) has emerged has a master regulator of inflammation/immunity in several tissues including the skeletal muscle. In this work, we explore whether microRNAs regulated by ApN may represent novel mechanisms for controlling muscle inflammation. By screening arrays, we found miR-711 as a strong candidate for mediating ApN action. Thus, ApN-knockout mice showed decreased muscular expression of miR-711 together with enhanced inflammation/oxidative stress markers, while mice overexpressing ApN showed increased miR-711 levels. Likewise, electrotransfer of the ApN gene in muscle of ApN-knockout mice upregulated miR-711 while reducing inflammation and oxidative stress. Similar data were obtained in murine C2C12 cells or in human primary myotubes treated with ApN. MiR-711 overexpression downregulated several components of the Toll-like receptor-4 (TLR4) pathway, which led to repression of NF-κB activity and downstream pro-inflammatory cytokines. MiR-711 blockade had opposite effects. Moreover, muscle electrotransfer of pre-miR-711 recapitulated in vivo the anti-inflammatory effects observed in vitro. Thus, miR-711, which is upregulated by ApN represses TLR4 signaling, acting therefore as a major mediator of the anti-inflammatory action of ApN. This novel miRNA and its related target genes may open new therapeutic perspectives for controlling muscle inflammation