Nintedanib decreases muscle fibrosis and improves muscle function in a murine model of dystrophinopathy

Duchenne muscle dystrophy (DMD) is a genetic disorder characterized by progressive skeletal muscle weakness. Dystrophin deficiency induces instability of the sarcolemma during muscle contraction that leads to muscle necrosis and replacement of muscle by fibro-adipose tissue. Several therapies have been developed to counteract the fibrotic process. We report the effects of nintedanib, a tyrosine kinase inhibitor, in the mdx murine model of DMD. Nintedanib reduced proliferation and migration of human fibroblasts in vitro and decreased the expression of fibrotic genes such as COL1A1, COL3A1, FN1, TGFB1, and PDGFA. We treated seven mdx mice with 60 mg/kg/day nintedanib for 1 month. Electrophysiological studies showed an increase in the amplitude of the motor action potentials and an improvement of the morphology of motor unit potentials in the animals treated. Histological studies demonstrated a significant reduction of the fibrotic areas present in the skeletal muscles. Analysis of mRNA expression from muscles of treated mice showed a reduction in Col1a1, Col3a1, Tgfb1, and Pdgfa. Western blot showed a reduction in the expression of collagen I in skeletal muscles. In conclusion, nintedanib reduced the fibrotic process in a murine model of dystrophinopathy after 1 month of treatment, suggesting its potential use as a therapeutic drug in DMD patients.España, Ministerio de Economía y Competitividad BFU2016-74975-PEspaña, Instituto Ramón y Cajal PI13/0134

Survey on the management of Pompe disease in routine clinical practice in Spain

Antibodies; Diagnosis; Pompe diseaseAnticuerpos; Diagnóstico; Enfermedad de pompeAnticossos; Diagnòstic; Malaltia de pompeBackground Despite the availability of several clinical guidelines, not all health professionals use their recommendations to manage patients with Pompe disease, a rare genetic disorder involving high-impact therapy. Through several discussion meetings and a survey, the present study aimed to learn about the management of Pompe disease in routine clinical practice in Spain, to improve clinical care in a real-life situation. Results The survey was sent to 42 healthcare professionals who manage patients with Pompe disease in their clinical practice. Although most respondents followed the clinical guidelines, clinical practice differed from the expert recommendations in many cases. Approximately 7% did not request a genetic study to confirm the diagnosis before starting treatment, and 21% considered that only two dried blood spot determinations suffice to establish the diagnosis. About 76% requested anti-GAA antibodies when there is a suspicion of lack of treatment efficacy, though a significant percentage of respondents have never requested such antibodies. According to 31% of the respondents, significant impairment of motor function and/or respiratory insufficiency is a requirement for authorizing medication at their hospital. Up to 26% waited for improvements over the clinical follow-up to maintain treatment and withdrew it in the absence of improvement since they did not consider disease stabilization to be a satisfactory outcome. Conclusions The results highlight the lack of experience and/or knowledge of some professionals caring for patients with Pompe disease. It is necessary to develop and disseminate simple guidelines that help to apply the expert recommendations better or centralize patient follow-up in highly specialized centers.Sanofi has sponsored this project without participating in the article’s design, data analysis, or writing

Comprehensive functional characterization of SGCB coding variants predicts pathogenicity in limb-girdle muscular dystrophy type R4/2E

Genetic testing is essential for patients with a suspected hereditary myopathy. More than 50% of patients clinically diagnosed with a myopathy carry a variant of unknown significance in a myopathy gene, often leaving them without a genetic diagnosis. Limb-girdle muscular dystrophy (LGMD) type R4/2E is caused by mutations in β-sarcoglycan (SGCB). Together, β-, α-, γ-, and δ-sarcoglycan form a 4-protein transmembrane complex (SGC) that localizes to the sarcolemma. Biallelic loss-of-function mutations in any subunit can lead to LGMD. To provide functional evidence for the pathogenicity of missense variants, we performed deep mutational scanning of SGCB and assessed SGC cell surface localization for all 6,340 possible amino acid changes. Variant functional scores were bimodally distributed and perfectly predicted pathogenicity of known variants. Variants with less severe functional scores more often appeared in patients with slower disease progression, implying a relationship between variant function and disease severity. Amino acid positions intolerant to variation mapped to points of predicted SGC interactions, validated in silico structural models, and enabled accurate prediction of pathogenic variants in other SGC genes. These results will be useful for clinical interpretation of SGCB variants and improving diagnosis of LGMD; we hope they enable wider use of potentially life-saving gene therapy

Hypoxia triggers IFN-I production in muscle: Implications in dermatomyositis

Dermatomyositis is an inflammatory myopathy characterized by symmetrical proximal muscle weakness and skin changes. Muscle biopsy hallmarks include perifascicular atrophy, loss of intramuscular capillaries, perivascular and perimysial inflammation and the overexpression of IFN-inducible genes. Among them, the retinoic-acid inducible gene 1 (RIG-I) is specifically overexpressed in perifascicular areas of dermatomyositis muscle. The aim of this work was to study if RIG-I expression may be modulated by hypoxia using an in vitro approach. We identified putative hypoxia response elements (HRE) in RIG-I regulatory regions and luciferase assays confirmed that RIG-I is a new HIF-inducible gene. We observed an increase expression of RIG-I both by Real time PCR and Western blot in hypoxic conditions in human muscle cells. Cell transfection with a constitutive RIG-I expression vector increased levels of phospho-IRF-3, indicating that RIG-I promotes binding of transcription factors to the enhancer sequence of IFN. Moreover, release of IFN-beta was observed in hypoxic conditions. Finally, HIF-1 alpha overexpression was confirmed in the muscle biopsies and in some RIG-I positive perifascicular muscle fibres but not in controls. Our results indicate that hypoxia triggers the production of IFN-I in vitro, and may contribute to the pathogenesis of DM together with other inflammatory factors

Wide-field optical properties estimation of whole limbs in muscle dystrophy murine models via SFDI: a case study

This manuscript analyzes the optical properties of dystrophic mice legs, which have been obtained by Spatial Frequency Domain Imaging (SFDI). We used a custom-built SFDI system with spectrometric capabilities so that wavelength-resolved absorption (μa) and scattering (μ′s) coefficients can be calculated. Samples were measured sequentially at ten different frequencies to find their frequency-dependent diffuse reflectance. Additionally, the Monte Carlo method has been applied to generate a Look-Up Table (LUT) to speed up the estimation of the optical parameters, with the GPU-accelerated version of Monte Carlo for Multi-Layered tissues (MCML), CUDAMCML. We found that the diffuse reflectance (Rd) has a different behavior in terms of the wavelength (λ), which gave rise to different values of µa and μ′s in terms of λ. Given that the μa is related to the chemical composition, the differences in wavelength could be used to quantify the presence of chemical components in the samples and, the μ′s, which relates to the internal structure, can be utilized to identify dystrophy centers inside the mice leg.Support for this work was provided by the projects PREVAL 21/07 (FUSIOMUSCLE), SUBVTC-2021-0038 (HYPERfusionTRANS), EQC 2019-006589-P, DTS22-00127(hyPERfusioCAM), DTS17-00055 (INTRACARDIO) and DISFOS (PID2019-107270RB-C21/AEI/ 10.13039/ 501100011033), financed by the ISCIII, the Fundación Instituto de Investigaci´on Valdecilla (IDIVAL) and the Spanish Ministry of Science, Innovation and Universities, co-financed with FEDER funds

Colorimetric fusion of attenuation and birefringence in OCT signatures: a screening tool for evaluating muscular degradation in alpha-sarcoglican deficit murine models

In this work, intensity and polarization OCT were applied, simultaneously, to alpha-sarcoglycan deficit mice models, and a new visualization technique was implemented, based on encoding the attenuation and birefringence values in the HSV color space. Our samples consisted of 14 ex-vivo mice quadriceps at different disease stages (one, three, and six-month-old mice) and four healthy ones for reference. The healthy muscles present a different birefringence distribution to the dystrophic ones, while attenuation values for both kinds of samples lay in the same range. Nevertheless, the attenuation provides an increase in contrast and textural features that are not visible by only using birefringence, while the latter, encoded in the H coordinate, helps to easily identify damage inside the samples by color.Support for this work was provided by the projects PREVAL 21/07 (FUSIOMUSCLE), SUBVTC-2021-0038 (HYPERfusionTRANS), EQC 2019-006589-P, DTS17-00055 (INTRACARDIO) and DISFOS (PID2019-107270RB-C21/AEI/10.13039/ 501100011033), financed by the ISCIII, the Fundaci´on Instituto de Investigación Valdecilla (IDIVAL) and the Spanish Ministry of Science, Innovation and Universities, co-financed with FEDER funds

Applying the win ratio method in clinical trials of orphan drugs: an analysis of data from the COMET trial of avalglucosidase alfa in patients with late-onset Pompe disease

Background: Clinical trials for rare diseases often include multiple endpoints that capture the effects of treatment on different disease domains. In many rare diseases, the primary endpoint is not standardized across trials. The win ratio approach was designed to analyze multiple endpoints of interest in clinical trials and has mostly been applied in cardiovascular trials. Here, we applied the win ratio approach to data from COMET, a phase 3 trial in late-onset Pompe disease, to illustrate how this approach can be used to analyze multiple endpoints in the orphan drug context. Methods: All possible participant pairings from both arms of COMET were compared sequentially on changes at week 49 in upright forced vital capacity (FVC) % predicted and six-minute walk test (6MWT). Each participant’s response for the two endpoints was first classified as a meaningful improvement, no meaningful change, or a meaningful decline using thresholds based on published minimal clinically important differences (FVC ± 4% predicted, 6MWT ± 39 m). Each comparison assessed whether the outcome with avalglucosidase alfa (AVA) was better than (win), worse than (loss), or equivalent to (tie) the outcome with alglucosidase alfa (ALG). If tied on FVC, 6MWT was compared. In this approach, the treatment effect is the ratio of wins to losses (“win ratio”), with ties excluded. Results: In the 2499 possible pairings (51 receiving AVA × 49 receiving ALG), the win ratio was 2.37 (95% confidence interval [CI], 1.30–4.29, p = 0.005) when FVC was compared before 6MWT. When the order was reversed, the win ratio was 2.02 (95% CI, 1.13–3.62, p = 0.018). Conclusion: The win ratio approach can be used in clinical trials of rare diseases to provide meaningful insight on treatment benefits from multiple endpoints and across disease domains

Different Approaches to Analyze Muscle Fat Replacement With Dixon MRI in Pompe Disease

Altres ajuts: Asociación Española de Enfermos de Glucogenosis (AEEG)Quantitative MRI is an increasingly used method to monitor disease progression in muscular disorders due to its ability to measure changes in muscle fat content (reported as fat fraction) over a short period. Being able to objectively measure such changes is crucial for the development of new treatments in clinical trials. However, the analysis of the images involved continues to be a daunting task because of the time needed. Whether a more specific analysis selecting individual muscles or a global one analyzing the whole thigh or compartments could be a suitable alternative has only been marginally studied. In our study we compare three methods of analysis of 2-point-dixon images in a cohort of 34 patients with late onset Pompe disease followed over a period of one year. We measured fat fraction on MRIs obtained at baseline and at year 1, and we calculated the increment of fat fraction. We correlated the results obtained with the results of muscle function tests to investigate whether the three methods of analysis were equivalent or not. We observed significant differences between the three methods in the estimation of the fat fraction at both baseline and year 1, but no difference was found in the increment in fat fraction between baseline and year 1. When we correlated the fat fraction obtained with each method and the muscle function tests, we found a significant correlation with most tests in all three methods, although in most comparisons the highest correlation coefficient was found with the analysis of individual muscles. We conclude that the fastest strategy of analysis assessing compartments or the whole thigh could be reliable for certain cohorts of patients where the variable to study is the fat increment. In other sorts of studies, an individual muscle approach seems the most reliable technique

Quantitative muscle MRI to follow up late onset Pompe patients : a prospective study

Late onset Pompe disease (LOPD) is a slow, progressive disorder characterized by skeletal and respiratory muscle weakness. Enzyme replacement therapy (ERT) slows down the progression of muscle symptoms. Reliable biomarkers are needed to follow up ERT-treated and asymptomatic LOPD patients in clinical practice. In this study, 32 LOPD patients (22 symptomatic and 10 asymptomatic) underwent muscle MRI using 3-point Dixon and were evaluated at the time of the MRI with several motor function tests and patient-reported outcome measures, and again after one year. Muscle MRI showed a significant increase of 1.7% in the fat content of the thigh muscles in symptomatic LOPD patients. In contrast, there were no noteworthy differences between muscle function tests in the same period of time. We did not observe any significant changes either in muscle MRI or in muscle function tests in asymptomatic patients over the year. We conclude that 3-point Dixon muscle MRI is a useful tool for detecting changes in muscle structure in symptomatic LOPD patients and could become part of the current follow-up protocol in daily clinics