BACKGROUND AND PURPOSE:The absence of the protein dystrophin in Duchenne muscular dystrophy (DMD) leads to progressive muscle weakness, failing regeneration and deregulation of nitric oxide (NO) signalling. We focused on L-citrulline, a precursor of L-arginine, required for NO production in muscle, which is reduced in dystrophic mdx muscle. EXPERIMENTAL APPROACH:L-Citrulline was administered (2 mg g-1 die-1), through diet, in comparison and/or in combination with prednisolone (1 mg kg-1, 5 days per week subcutaneously) to 4- to 5-week-old mdx mice for 8 weeks. KEY RESULTS:L-Citrulline increased the levels of L-arginine, L-citrulline and L-ornithine in plasma and quadriceps of mdx mice. L-citrulline, alone or plus prednisolone, significantly improved maximal forelimb force in vivo, while ameliorating diaphragm movement amplitude and reducing diaphragm echodensity. In parallel, ex vivo, we detected a significant improvement of diaphragm force and contraction kinetics in mice treated with L-citrulline alone or in combination with prednisolone. L-citrulline also restored the expression of genes involved in Ca2+ handling during contraction (RyR1, RyR3 and SERCA), while reducing the markers of inflammation and fibrosis (CD68 and TGFβ1) and ameliorating mitochondrial biogenesis-associated genes (PGC1-α and MEF2C). No effect was observed on S-nitrosylation levels of HDAC2 and on diaphragm and gastrocnemius nNOS gene expression, suggesting a NO-independent mechanism underlying the positive outcome observed. CONCLUSIONS:Our results revealed the ability of L-citrulline supplementation to ameliorate in vivo and ex vivo function of diaphragm muscle, highlighting novel metabolic and calcium-related mechanisms of potential clinical interest.

Background: Although Duchenne muscular dystrophy (DMD) is primarily characterized as a skeletal muscle-wasting disorder, the resulting pathophysiological changes extend to multiple non-muscle tissues and organ systems. Among these, renal and urinary tract dysfunctions have been reported, albeit in relatively few studies, as potential complications in DMD patients, sometimes occurring from an early age. Importantly, as life expectancy improves, the incidence of renal impairment is also expected to increase. This narrative review summarizes the available evidence on kidney involvement in DMD and discusses the associated biomarkers of renal dysfunction within the context of multisystem disease progression. Methods: The review draws on data from both human and animal studies and analyzes published evidence to explore kidney involvement in DMD, with a focus on clinical manifestations, biomarkers of renal dysfunction, and potential pathogenic mechanisms. Results: Available data indicate a close association between cardiac and renal dysfunction, particularly in patients with advanced-stage DMD. The review explores potential underlying mechanisms of renal impairment, including intrinsic dystrophin deficiency in the kidney, secondary effects of cardiovascular complications, and the nephrotoxic impact of drug therapies, highlighting renal function as an active determinant of clinical risk. Conclusions: While cardiac function monitoring is already a cornerstone of multidisciplinary care for this multisystem disease, systematic assessment of renal function should also be implemented, with implications for clinical management and drug safety. Moreover, the risk of drug-induced nephrotoxicity warrants attention in both clinical management and the development of novel therapeutic strategies for DMD.

Growth hormone secretagogues (GHSs) are gaining interest as promising therapeutics for Duchenne muscular dystrophy (DMD) due to their broad activity profile and proven benefits in other muscle-wasting conditions. We previously found that JMV2894 - a pseudopeptide GHS - exerts functional, anti-inflammatory, and antifibrotic benefits in classic BL10-mdx mice, supported by in silico predictions of its interaction with ADAMTS-5 and matrix metalloproteinase 9 (MMP-9), both overactivated in DMD. This led us to test JMV2894 in the D2.B10-Dmdmdx/J (D2-mdx) mouse model, chosen for its hyper-fibrotic and atrophic disease phenotype. JMV2894 was administered subcutaneously at 640 or 1280 µg/kg for six weeks to 4-week-old D2-mdx mice, showing good tolerability. In vivo, the treatment partially improved hind limb plantar flexor torque, ultrasound volume, and reduced gastrocnemius (GC) muscle echodensity. While decreasing the expression of matrix-remodeling genes (i.e., MMP-9, ADAMTS-5, transforming growth factor beta-1, type I collagen α1), JMV2894 only mildly alleviated GC muscle fibrosis histologically. However, JMV2894 - particularly at the lower dose - exerted a remarkable anti-atrophic action, evidenced by increased GC myofiber size and decreased gene expression of Atrogin and Muscle RING Finger 1. Enhanced insulin-like growth factor 1 (IGF-1) transcript and plasma levels, along with increased IGF-1 receptor and downstream signalling proteins, suggest that JMV2894 actions are most likely GH-mediated. These effects occurred despite limited muscle drug exposure, highlighting the need for improved formulations to enhance bioavailability. Overall, our results show that GHSs exert different actions in dystrophic settings, likely related to distinct disease phenotype, reflecting the complexity of translational exercise towards universal therapies in DMD.

Rapid and detailed post-marketing surveillance of drugs and vaccine is required to enable assessment of their real-world safety and effectiveness. Spontaneous reporting from healthcare professionals and citizens is recognized as the basic method in the passive post-marketing surveillance of drugs and vaccines, allowing the identification of rare adverse drug reactions (ADRs) and adverse events following immunization (AEFIs). According to the current law, online platforms for ADRs and AEFI reporting and related databases are available in every country and at the global level. Recently, the use of electronic health records and the establishment of networks of databases as different sources of real-world data is emerging allowing high-quality, large-scale evaluations and providing real-world evidence on questions of clinical and regulatory interests. Here, we summarize the adverse event pharmacovigilance reporting systems in place at the global, European and in some European countries, and provide examples from recent literature of how the analysis of pharmacovigilance reports can provide evidence for unexpected and novel adverse drug reactions. Furthermore, we discuss the role of real-world data to generate real-world evidence in pharmacovigilance and regulatory activities.

The Nav1.7 voltage-gated sodium channel recently emerged as a candidate target for developing analgesic drugs due to its contribution to nociception and association with different pain disorders. Despite extensive research, no selective modulator of Nav1.7 has been put into clinic yet. Meanwhile, some non-selective sodium channel blockers, such as lidocaine and mexiletine (Mex), have been used for treating peripheral neuropathy and Nav1.7-related pain syndromes. The development of selective molecules targeting Nav1.7 channels requires robust preclinical tests integrating efficient electrophysiological screening with proper cell models. Here, we used the automated patch clamp platform, Patchliner (Nanion Technologies), and two different cell lines, the human rhabdomyosarcoma TE671 cells endogenously expressing Nav1.7 and HEK293 cells stably expressing heterologous human Nav1.7, to compare the biophysical properties and state-dependent effect of Mex on Nav1.7 channels. Our results show that in voltage-dependent conditions, Mex similarly blocked sodium currents in both cell lines (IC50: 226 ± 16 and 227 ± 14 μM, at -140 mV; 15 ± 1 and 12 ± 1 μM, at -70 mV, for TE671 and HEK293 cells). Likewise, Mex exerted a comparable tonic (0.3 Hz) and use-dependent (20 Hz) block in TE671 and in HEK293 cells (IC50: 96 ± 4 vs 114 ± 9 μM; IC50: 22 ± 2 and 18 ± 2 μM, at 0.3 Hz and 20 Hz). Moreover, Mex negatively shifted the voltage-dependence of inactivation of Nav1.7 channels in a dose-dependent manner in both cell lines. In conclusion, we confirmed the state-dependency of Mex block on Nav1.7 using automated patch clamp and validated two cell lines expressing Nav1.7 as suitable models for drug screening. This approach can help developing Nav1.7 modulators for the treatment of pain disorders.

Myotonia is an inherited rare skeletal muscle disorder which causes sarcolemma hyperexcitability due to alterations of different ion channels (e.g., CLC-1, Nav 1.4). Mexiletine is a class I antiarrhythmic drug approved in non-dystrophic myotonias for its ability to exert a use-dependent block of skeletal muscle sodium channel (Nav1.4). The possibility to discriminate drug action between Nav1.4 and cardiac Nav1.5 is critical for exerting a therapeutic antimyotonic effect, reducing the risk of cardiac toxicity. Furthermore, efficient and reliable pre-clinical tests are pivotal, also with the long-term goal to find novel antimyotonic agents. Our aim was to assess the effects of mexiletine both on Nav1.4 and Nav1.5 using an automated patch clamp platform. Recordings of peak sodium currents of Nav1.4 and Nav1.5 were performed using the automated patch clamp platform Patchliner. The tonic- (0.3 Hz), voltage- (−70 mV at 0.3 Hz) and use-dependent blocks (3 Hz for Nav1.5 and 10 Hz for Nav1.4), consistent with pathophysiological conditions of Nav1.4 and Nav1.5 by mexiletine, were evaluated. We used TE671 cells, which endogenously express Nav 1.4, and CHO cells heterologously express Nav 1.5. Mexiletine was more potent in determining a tonic block of Nav1.5 than of Nav1.4 measured at 0.3 Hz (IC50: 65 μM vs 188 μM). Similarly, voltage-dependent block at −70 mV showed that mexiletine blocked Nav1.5 channels more than Nav1.4 (IC50: 6.6 μM vs 27.4 μM). At cardiac pathophysiological frequency of 3 Hz, mexiletine blocked Nav1.5 with an IC50 of 33.7 μM. Importantly, at stimulation frequencies mimicking the myotonic discharge (10 Hz), mexiletine blocked Nav1.4 channels with high potency, with about 20- and 6-fold reduction of IC50 value vs. tonic block on both Nav1.4 and Nav 1.5, respectively (IC50: 11.5 μM). Data obtained by running pathophysiological protocols on the Patchliner confirmed that mexiletine has more affinity for Nav1.5 channel compared to Nav1.4 in conditions of tonic and voltage-dependent blocks. However, at the high frequency of stimulation, as occurring exclusively in myotonic myofibers (i.e. 10 Hz), mexiletine can act as selective Nav1.4 blocker. This biophysical approach can help the development of novel Nav1.4 blockers with improved safety profile for muscle disorders.

Deoxynojirimycin (DNJ), the first isolated iminosugar, is a natural alkaloid acting as a potent inhibitor of α-glucosidase with high nutritional value. It naturally occurs in plants (especially Morus spp.), microbes, and insects or can be synthesized. Diverse biological activities, such as antihyperglycemic, lipid-lowering, antitumor, antiviral, and anti-inflammatory, have been recognized for this compound. However, DNJ has not been approved as a food supplement until now. Several studies, also in clinics, are carried out on Morus spp. containing DNJ. Among Morus spp., Morus alba L. (white mulberry), Morus nigra L. (black mulberry), and Morus rubra L. (red mulberry) are the three main species that grow all over the world. Some spurious studies have been conducted on Reducose® and Glubloc™, two products that contain DNJ and Morus alba, respectively. However, mulberry allergy, including respiratory allergy, airborne contact urticaria, anaphylaxis, oral allergy syndrome, and food induced urticaria, may be observed. This review aims to explore a crucial and timely question: how DNJ exerts its biological effects and what role it may play in therapeutic applications. We provide a comprehensive summary of the current understanding of DNJ’s pharmacological potential and the methods used for its production. We also report recent developments in clinical studies on Morus alba, Reducose® and Glubloc™.

Epilepsy is a chronic and debilitating neurological disorder characterized by the occurrence of spontaneous and recurrent seizures. Despite the availability of several antiseizure medications (ASMs), people with epilepsy often experience drug resistance and adverse effects. This narrative review provides an overview of the main adverse drug reactions (ADR) caused by ASMs, including neurological, metabolic, skin reactions and drug failure, and of the underlying molecular mechanisms. Given the critical contribution of pharmacogenomics and drug-drug interactions to the occurrence of some ADRs, we provide examples of the role of major allelic variations identified in genes encoding for molecules involved in the pharmacokinetics, pharmacodynamics and immune system and emphasize the activity of ASMs as inhibitors or inducers of metabolic enzymes. Improved knowledge of the benefit-risk profile of drugs, also through enhanced pharmacovigilance activity and following guidelines recommendations, could implement patients care avoiding ADRs and favoring a beneficial personalized medicine particularly in vulnerable patients as children, elderly people and pregnant women.

Non-dystrophic myotonias are inherited rare skeletal muscle disorders characterized by sarcolemma hyperexcitability caused by ion channels mutations. Mexiletine is a class I antiarrhythmic drug approved in myotonia, exerting a use-dependent block of skeletal muscle sodium channel (NaV1.4). Discriminating drug action between NaV1.4 and cardiac NaV1.5 is critical for reducing cardiac toxicity risk. Thus, robust pre-clinical tests are pivotal to aid the development of antimyotonic agents with better safety/efficacy profile. We assessed the effects of mexiletine (Mex) and its highly use-dependent pyrroline analogue (VM11) on NaV1.4 and NaV1.5 by automated patch-clamp platform Patchliner (Nanion) using tissue-specific pathophysiologic stimulation frequencies. Tonic- (0.3 Hz;TB), voltage- (−70/−140 mV at 0.3 Hz;VDB) and use-dependent blocks (3 Hz for NaV1.5 and 10 Hz for NaV1.4;UDB) were evaluated using TE671 cells endogenously expressing NaV1.4 and CHO cells heterologously expressing NaV1.5. Mex was more potent on NaV1.5 than NaV1.4 in TB/VDB conditions (IC50: 24±3 vs 87±5 μM for TB; 2±0.3 vs 15±1 μM for VDB −70 mV; 159±8 vs 226±16 μM for VDB −140mV). Instead, VM11 produced similar TB/VDB (−140 mV) of NaV1.4 and NaV1.5(7±0.6 vs 9±0.5 μM for TB; 48±3 vs 54±5 μM for VDB) but exerted greater VDB at −70 mV on NaV1.5 than NaV1.4 (VM11: 3±0.2 vs 7±0.4 μM). At pathological heart frequencies (3Hz), VM11 blocked NaV1.5 more than Mex (5±0.3 vs 35±1 μM), while at myotonic-like frequency of 10Hz, Mex and VM11 potently blocked NaV1.4 but still at concentrations (24±2 and 3±0.2 μM) in the range of blocking NaV1.5. Patchliner allowed to easily compare potency and use-dependent behavior of Mex-like compounds, disclosing a still narrow safety range even at myotonic-like frequencies. This biophysical approach and the automated patch-clamp platform can help the development of novel NaV1.4 blockers with improved safety profile for muscle disorders (MNESYS_PE0000006).

Ion channels plays a role in muscle cells differentiation/maturation and have an active crosstalk with the dystrophin complex, which is disrupted in Duchenne muscular dystrophy (DMD). Myogenesis is claimed to be altered in DMD, however the possible involvement of ion channels in this process is not known. Here we characterized the electrophysiological asset of myoblasts/myotubes at different time points by using two immortalized mouse (day 0/2/4/6/11) and human (day 0/4/7/12/20) skeletal muscle cell lines: wild-type (2B4 and hWT) and dystrophic counterpart (SF1 and hDMD). We evaluated both inward and outward currents by using manual patch-clamp for current recordings from murine cells and automated patch-clamp Patchliner (Nanion) for human cells. Inward and outward current density of 2B4/SF1 murine cells increased as the differentiation progressed, despite outward currents were 5-fold smaller than inward currents at each time-point. Day-11 SF1 cells had slightly higher inward and outward current density compared to control (−95.2 ± 29.8, n = 6 vs −75.8 ± 14.6 pA/pF, n = 7 at −20mV; 20.8±5, n=11 vs 16.2±2.2 pA/pF, n=13 at +60mV). Like 2B4 cells, hWT cells inward current density increased as the differentiation proceeded. Inward current density at day-20 was higher than at day 4/7 in hWT myotubes (−245 ± 33 n = 9 vs −88 ± 12 n = 8 and −135 ± 18 pA/pF n = 14 at -20mV). hDMD cells presented small inward current densities at day 0/4/7. Then, hDMD inward current density increased up to day-20 (−317 ± 107 pA/pF; n = 9) resulting slightly higher than that of hWT cells. Our results showed a slight increase of inward current density both in the murine and human dystrophic myotubes compared with controls, indicating that intrinsic impairments in ion channel may occur in DMD during differentiation. Also we validated automated patch-clamp as suitable technique for biophysical characterization of differentiating skeletal muscle cells (MNESYS_PE0000006).

IntroductionGrowth hormone secretagogues (GHSs) exert multiple actions, being able to activate GHS-receptor 1a, control inflammation and metabolism, to enhance GH/insulin-like growth factor-1 (IGF-1)-mediated myogenesis, and to inhibit angiotensin-converting enzyme. These mechanisms are of interest for potentially targeting multiple steps of pathogenic cascade in Duchenne muscular dystrophy (DMD).MethodsHere, we aimed to provide preclinical evidence for potential benefits of GHSs in DMD, via a multidisciplinary in vivo and ex vivo comparison in mdx mice, of two ad hoc synthesized compounds (EP80317 and JMV2894), with a wide but different profile. 4-week-old mdx mice were treated for 8 weeks with EP80317 or JMV2894 (320 µg/kg/d, s.c.).ResultsIn vivo, both GHSs increased mice forelimb force (recovery score, RS towards WT: 20% for EP80317 and 32% for JMV2894 at week 8). In parallel, GHSs also reduced diaphragm (DIA) and gastrocnemius (GC) ultrasound echodensity, a fibrosis-related parameter (RS: ranging between 26% and 75%). Ex vivo, both drugs ameliorated DIA isometric force and calcium-related indices (e.g., RS: 40% for tetanic force). Histological analysis highlighted a relevant reduction of fibrosis in GC and DIA muscles of treated mice, paralleled by a decrease in gene expression of TGF-β1 and Col1a1. Also, decreased levels of pro-inflammatory genes (IL-6, CD68), accompanied by an increment in Sirt-1, PGC-1α and MEF2c expression, were observed in response to treatments, suggesting an overall improvement of myofiber metabolism. No detectable transcript levels of GHS receptor-1a, nor an increase of circulating IGF-1 were found, suggesting the presence of a novel receptor-independent mechanism in skeletal muscle. Preliminary docking studies revealed a potential binding capability of JMV2894 on metalloproteases involved in extracellular matrix remodeling and cytokine production, such as ADAMTS-5 and MMP-9, overactivated in DMD.DiscussionOur results support the interest of GHSs as modulators of pathology progression in mdx mice, disclosing a direct anti-fibrotic action that may prove beneficial to contrast pathological remodeling.

The voltage-gated sodium channels represent an important target for drug discovery since a large number of physiological processes are regulated by these channels. In several excitability disorders, including epilepsy, cardiac arrhythmias, chronic pain, and non-dystrophic myotonia, blockers of voltage-gated sodium channels are clinically used. Myotonia is a skeletal muscle condition characterized by the over-excitability of the sarcolemma, resulting in delayed relaxation after contraction and muscle stiffness. The therapeutic management of this disorder relies on mexiletine and other sodium channel blockers, which are not selective for the Nav1.4 skeletal muscle sodium channel isoform. Hence, the importance of deepening the knowledge of molecular requirements for developing more potent and use-dependent drugs acting on Nav1.4. Here, we review the available treatment options for non-dystrophic myotonia and the structure–activity relationship studies performed in our laboratory with a focus on new compounds with potential antimyotonic activity.

In age-related sarcopenia, the gradual loss of skeletal muscle mass, function and strength is underpinned by an imbalanced rate of protein synthesis/breakdown. Hence, an adequate protein intake is considered a valuable strategy to mitigate sarcopenia. Here, we investigated the effects of a 12-week oral supplementation with branched-chain amino acids (BCAAs: leucine, isoleucine, and valine) with recognized anabolic properties, in 17-month-old (AGED) C57BL/6J male mice. BCAAs (2:1:1) were formulated in drinking water, alone or plus two L-Alanine equivalents (2ALA) or dipeptide L-Alanyl-L-Alanine (Di-ALA) to boost BCAAs bioavailability. Outcomes were evaluated on in/ex vivo readouts vs. 6-month-old (ADULT) mice. In vivo hind limb plantar flexor torque was improved in AGED mice treated with BCAAs + Di-ALA or 2ALA (recovery score, R.S., towards ADULT: ≥20%), and all mixtures significantly increased hind limb volume. Ex vivo, myofiber cross-sectional areas were higher in gastrocnemius (GC) and soleus (SOL) muscles from treated mice (R.S. ≥ 69%). Contractile indices of isolated muscles were improved by the mixtures, especially in SOL muscle (R.S. ≥ 20%). The latter displayed higher mTOR protein levels in mice supplemented with 2ALA/Di-ALA-enriched mixtures (R.S. ≥ 65%). Overall, these findings support the usefulness of BCAAs-based supplements in sarcopenia, particularly as innovative formulations potentiating BCAAs bioavailability and effects.

Skeletal muscle atrophy occurs in response to various pathophysiological stimuli, including disuse, aging, and neuromuscular disorders, mainly due to an imbalance of anabolic/catabolic signaling. Branched Chain Amino Acids (BCAAs: leucine, isoleucine, valine) supplements can be beneficial for counteracting muscle atrophy, in virtue of their reported anabolic properties. Here, we carried out a proof-of-concept study to assess the in vivo/ex vivo effects of a 4-week treatment with BCAAs on disuse-induced atrophy, in a murine model of hind limb unloading (HU). BCAAs were formulated in drinking water, alone, or plus two equivalents of L-Alanine (2 ALA) or the dipeptide L-Alanyl-L-Alanine (Di-ALA), to boost BCAAs bioavailability. HU mice were characterized by reduction of body mass, decrease of soleus - SOL - muscle mass and total protein, alteration of postural muscles architecture and fiber size, dysregulation of atrophy-related genes (Atrogin-1, MuRF-1, mTOR, Mstn). In parallel, we provided new robust readouts in the HU murine model, such as impaired in vivo isometric torque and ex vivo SOL muscle contractility and elasticity, as well as altered immune response. An acute pharmacokinetic study confirmed that L-ALA, also as dipeptide, enhanced plasma exposure of BCAAs. Globally, the most sensitive parameters to BCAAs action were muscle atrophy and myofiber cross-sectional area, muscle force and compliance to stress, protein synthesis via mTOR and innate immunity, with the new BCAAs + Di-ALA formulation being the most effective treatment. Our results support the working hypothesis and highlight the importance of developing innovative formulations to optimize BCAAs biodistribution.

Statins are the most prescribed and effective drugs to treat cardiovascular diseases (CVD). Nevertheless, these drugs can be responsible for skeletal muscle toxicity which leads to reduced compliance. The discontinuation of therapy increases the incidence of CVD. Thus, it is essential to assess the risk. In fact, many studies have been performed at preclinical and clinical level to investigate pathophysiological mechanisms and clinical implications of statin myotoxicity. Consequently, new toxicological aspects and new biomarkers have arisen. Indeed, these drugs may affect gene transcription and ion transport and contribute to muscle function impairment. Identifying a marker of toxicity is important to prevent or to cure statin induced myopathy while assuring the right therapy for hypercholesterolemia and counteracting CVD. In this review we focused on the mechanisms of muscle damage discovered in preclinical and clinical studies and highlighted the pathological situations in which statin therapy should be avoided. In this context, preventive or substitutive therapies should also be evaluated.

We explored the involvement of oxytocin receptor ( Oxtr )/transient-receptor-potential-vanilloid-1 ( TRPV1 ) genes and oxytocin (Oxt) on the adaptation of skeletal muscle to cold stress challenge in mice. Oxtr expression in hypothalamic paraventricular (PVN), supraoptic nuclei (SON), and hippocampus (HIPP) were evaluated by immunohistochemistry in parallel with the measurement of circulating Oxt. The Oxtr and TRPV1 gene expressions in soleus (SOL) and tibialis anterior (TA) muscles were investigated by RT-PCR. Histological studies of the cardiac muscle after cold stress were also performed. Male mice ( n = 15) were divided into controls maintained at room temperature (RT = 24°C), exposed to cold stress (CS) at T = 4°C for 6 h , and 5 days. Immunohistochemical studies showed that Oxtr protein expression increased by two-fold ( P = 0.01) in PVN and by 1.5-fold ( P = 0.0001) in HIPP after 6 h- and 5 days of CS but decreased by 2-fold ( P = 0.026) in SON in 5 days. Both Oxtr and TRPV1 gene expression increased after 6 h and 5 days of CS in SOL and TA muscles. Oxtr vs TRPV1 gene expression in SOL and TA muscles evaluated by regression analysis was linearly correlated following CS at 6 h and 5 days but not at control temperature of 24 ± 1°C, supporting the hypothesis of coupling between these genes. The circulating levels of Oxt are unaffected after 6 h of CS but decreased by 0.2-fold ( P = 0.0141) after 5 days-CS. This is the first report that Oxtr and TRPV1 expressions are upregulated in response to cold acclimation in skeletal muscle. The up-regulation of Oxtr in PVN and HIPP balances the decrease of circulating Oxt.

ROS-activated cSrc tyrosine kinase (TK) promotes the degradation of β-dystroglycan (β-DG), a dystrophin-glycoprotein complex component, which may reinforce damaging signals in Duchenne muscular dystrophy (DMD). Therefore, cSrc-TK represents a promising therapeutic target. In mdx mice, a 4-week subcutaneous treatment with dasatinib (DAS), a pan-Src-TKs inhibitor approved as anti-leukemic agent, increased muscle β-DG, with minimal amelioration of morphofunctional indices. To address possible dose/pharmacokinetic (PK) issues, a new oral DAS/hydroxypropyl(HP)-β-cyclodextrin(CD) complex was developed and chronically administered to mdx mice. The aim was to better assess the role of β-DG in pathology progression, meanwhile confirming DAS mechanism of action over the long-term, along with its efficacy and tolerability. The 4-week old mdx mice underwent a 12-week treatment with DAS/HP-β-CD10% dissolved in drinking water, at 10 or 20 mg/kg/day. The outcome was evaluated via in vivo/ex vivo disease-relevant readouts. Oral DAS/HP-β-CD efficiently distributed in mdx mice plasma and tissues in a dose-related fashion. The new DAS formulation confirmed its main upstream mechanism of action, by reducing β-DG phosphorylation and restoring its levels dose-dependently in both diaphragm and gastrocnemius muscle. However, it modestly improved in vivo neuromuscular function, ex vivo muscle force, and histopathology, although the partial recovery of muscle elasticity and the decrease of CK and LDH plasma levels suggest an increased sarcolemmal stability of dystrophic muscles. Our clinically oriented study supports the interest in this new, pediatric-suitable DAS formulation for proper exposure and safety and for enhancing β-DG expression. This latter mechanism is, however, not sufficient by itself to impact on pathology progression. In-depth analyses will be dedicated to elucidating the mechanism limiting DAS effectiveness in dystrophic settings, meanwhile assessing its potential synergy with dystrophin-based molecular therapies.

The authors regret that the fund code provided under Acknowledgement section is incorrect. The research has been supported by PRIN-MIUR (Research Projects of National Interest Ministry of Education, University and Research) project no 2015MJBEM2_005 and The Dutch Duchenne Parent Project NL (DPP NL). The authors would like to apologise for any inconvenience caused. DOI of original article: < https://doi.org/10.1016/j.trsl.2018.09.004 > Annamaria De Luca, Section of Pharmacology, Department of Pharmacy - Drug Sciences, University of Bari “Aldo Moro”, Via E. Orabona 4 _ Campus, 70125 Bari, Italy A long-term treatment with taurine prevents cardiac dysfunction in mdx miceTranslational ResearchVol. 204PreviewTaurine is an amino acid abundantly present in heart and skeletal muscle. Duchenne muscular dystrophy (DMD) is a genetic disorder in which the absence of dystrophin leads to skeletal muscle wasting and heart failure. An altered taurine metabolism has been described in dystrophic animals and short-term taurine administration exerts promising amelioration of early muscular alterations in the mdx mouse model of DMD. To reinforce the therapeutic and nutraceutical taurine potential in DMD, we evaluated the effects of a long-term treatment on cardiac and skeletal muscle function of mdx mice in a later disease stage. Full-Text PDF