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الجوانب الوراثية والجزيئية للأداء الرياضي
يكتسب هذا الكتاب أهمية بالغة من حيث الندرة والجودة والقيمة العلمية إنه يعتبر أول كتاب يتخصص في علم الوراثة لدى الرياضي بهذا الحجم باللغة العربية وهو عبارة على حصيلة لنتائج العديد من البحوث العلمية التي تمت خلال العقود القليلة الماضية وتضمن هذا الكتاب خمسة أجزاء مختلفة هي : علم الجينوم وعلم الوراثة، أدلة من دراسات علم الأوبئة الوراثية، مساهمات جينات وعلامات معينة، بيولوجيا الأنظمة للجهد البدني والتدريب والآثار الأخلاقية والمجتمعية ويحتوي هذا الكتاب على العديد من الاكتشافات الحديثة الخاصة بعلم الوراثة المتعلقة بجسم رياضي وفي الأخير يمكن القول إن هذا الكتاب سوف يكون بإذن الله المرجع الأساسي للبحوث والدراسات المتعلقة بهذا الجانب من الاختصاص.
BOOK
Is it time for genetic modifiers to predict prognosis in Duchenne muscular dystrophy?
Patients with Duchenne muscular dystrophy (DMD) show clinically relevant phenotypic variability, despite sharing the same primary biochemical defect (dystrophin deficiency). Factors contributing to this clinical variability include allelic heterogeneity (specific DMD mutations), genetic modifiers (trans-acting genetic polymorphisms) and variations in clinical care. Recently, a series of genetic modifiers have been identified, mostly involving genes and/or proteins that regulate inflammation and fibrosis — processes increasingly recognized as being causally linked with physical disability. This article reviews genetic modifier studies in DMD to date and discusses the effect of genetic modifiers on predicting disease trajectories (prognosis), clinical trial design and interpretation (inclusion of genotype-stratified subgroup analyses) and therapeutic approaches. The genetic modifiers identified to date underscore the importance of progressive fibrosis, downstream of dystrophin deficiency, in driving the disease process. As such, genetic modifiers have shown the importance of therapies aimed at slowing this fibrotic process and might point to key drug targets.Patients with Duchenne muscular dystrophy show clinically relevant phenotypic variability, despite sharing the same primary biochemical defect (dystrophin deficiency). In this Review, the authors provide an overview of the current evidence on Duchenne muscular dystrophy genetic modifiers that contribute to this variability.
Journal Article
Large-scale serum protein biomarker discovery in Duchenne muscular dystrophy
Significance Duchenne muscular dystrophy (DMD) is a rare and devastating muscle disease caused by mutations in the X-linked DMD gene (which encodes the dystrophin protein). Serum biomarkers hold significant potential as objective phenotypic measures of DMD disease state, as well as potential measures of pharmacological effects of and response to therapeutic interventions. Here we describe a proteomics approach to determine serum levels of 1,125 proteins in 93 DMD patients and 45 controls. The study identified 44 biomarkers that differed significantly between patients and controls. These data are being made available to DMD researchers and clinicians to accelerate the search for new diagnostic, prognostic, and therapeutic approaches.
Serum biomarkers in Duchenne muscular dystrophy (DMD) may provide deeper insights into disease pathogenesis, suggest new therapeutic approaches, serve as acute read-outs of drug effects, and be useful as surrogate outcome measures to predict later clinical benefit. In this study a large-scale biomarker discovery was performed on serum samples from patients with DMD and age-matched healthy volunteers using a modified aptamer-based proteomics technology. Levels of 1,125 proteins were quantified in serum samples from two independent DMD cohorts: cohort 1 (The Parent Project Muscular Dystrophy–Cincinnati Children’s Hospital Medical Center), 42 patients with DMD and 28 age-matched normal volunteers; and cohort 2 (The Cooperative International Neuromuscular Research Group, Duchenne Natural History Study), 51 patients with DMD and 17 age-matched normal volunteers. Forty-four proteins showed significant differences that were consistent in both cohorts when comparing DMD patients and healthy volunteers at a 1% false-discovery rate, a large number of significant protein changes for such a small study. These biomarkers can be classified by known cellular processes and by age-dependent changes in protein concentration. Our findings demonstrate both the utility of this unbiased biomarker discovery approach and suggest potential new diagnostic and therapeutic avenues for ameliorating the burden of DMD and, we hope, other rare and devastating diseases.
Journal Article
The effect of IL-1β inhibitor canakinumab (Ilaris®) on IL-6 production in human skeletal muscle cells
Muscle inflammation is one of the hallmarks of Duchenne muscular dystrophy (DMD). Dystrophin-deficient skeletal muscle cells produce higher levels of pro-inflammatory cytokines such as interleukin 1β (IL-1β) in response to toll-like receptor stimulation compared to normal muscle skeletal cells. IL- 1β induces the human skeletal muscle secretion of the myokine Interleukin-6 (IL-6). Here, we evaluated the effect of a human IgG1κ monoclonal antibody (canakinumab (Ilaris®)) that specifically blocks the IL-1β effect on IL-6 secretion by human skeletal muscle cells. Canakinumab is an excellent candidate for therapeutic repositioning to treat DMD because it is an FDA-approved drug to treat periodic fever syndromes and systemic juvenile idiopathic arthritis. Unlike previous generations of IL-1 inhibitors, canakinumab is highly specific for the IL-1β ligand, has a longer half-life, and does not interfere with other IL-1-activated inflammatory pathways. Following cell culture optimization and viability assays to assess toxicity, skeletal muscle cells were stimulated with IL-1β (10 ng/mL) for 48 hours in the presence of nine concentrations of canakinumab ranging from 0.001 nM to 1000 nM, and IL-6 production was measured with an enzyme-linked immunosorbent assay. Pre-incubation of myoblasts with canakinumab before IL-1β-stimulation, significantly reduced IL-6 production at concentrations of 1, 10, 100, 250, and 1000 nM relative to controls, yielding an IC 50 of 0.264 nM. On the other hand, co-incubation of canakinumab with IL-1β before addition to myoblasts resulted in a significant inhibition with the IC 50 reducing to 0.126 nM, less than half of the previous method. Canakinumab also did not affect myotube viability at 10 nM and was also able to significantly reduce the production of IL-6, when the cells were stimulated with IL-1β (10 ng/ml). Taken together, our results show that canakinumab is a potent inhibitor of IL-1β signaling in muscle cells. These results align with previously published pre-clinical work with other IL-1 inhibitors in the mdx mouse model and support further investigation into the clinical utility of repositioning canakinumab to treat DMD.
Journal Article
Genetic Modifiers of Duchenne Muscular Dystrophy and Dilated Cardiomyopathy
Dilated cardiomyopathy (DCM) is a major complication and leading cause of death in Duchenne muscular dystrophy (DMD). DCM onset is variable, suggesting modifier effects of genetic or environmental factors. We aimed to determine if polymorphisms previously associated with age at loss of independent ambulation (LoA) in DMD (rs28357094 in the SPP1 promoter, rs10880 and the VTTT/IAAM haplotype in LTBP4) also modify DCM onset.
A multicentric cohort of 178 DMD patients was genotyped by TaqMan assays. We performed a time-to-event analysis of DCM onset, with age as time variable, and finding of left ventricular ejection fraction < 50% and/or end diastolic volume > 70 mL/m2 as event (confirmed by a previous normal exam < 12 months prior); DCM-free patients were censored at the age of last echocardiographic follow-up.
Patients were followed up to an average age of 15.9 ± 6.7 years. Seventy-one/178 patients developed DCM, and median age at onset was 20.0 years. Glucocorticoid corticosteroid treatment (n = 88 untreated; n = 75 treated; n = 15 unknown) did not have a significant independent effect on DCM onset. Cardiological medications were not administered before DCM onset in this population. We observed trends towards a protective effect of the dominant G allele at SPP1 rs28357094 and recessive T allele at LTBP4 rs10880, which was statistically significant in steroid-treated patients for LTBP4 rs10880 (< 50% T/T patients developing DCM during follow-up [n = 13]; median DCM onset 17.6 years for C/C-C/T, log-rank p = 0.027).
We report a putative protective effect of DMD genetic modifiers on the development of cardiac complications, that might aid in risk stratification if confirmed in independent cohorts.
Journal Article
Bodywide skipping of exons 45–55 in dystrophic mdx52 mice by systemic antisense delivery
Duchenne muscular dystrophy (DMD), the commonest form of muscular dystrophy, is caused by lack of dystrophin. One of the most promising therapeutic approaches is antisense-mediated elimination of frame-disrupting mutations by exon skipping. However, this approach faces two major hurdles: limited applicability of each individual target exon and uncertain function and stability of each resulting truncated dystrophin. Skipping of exons 45–55 at the mutation hotspot of the DMD gene would address both issues. Theoretically it could rescue more than 60% of patients with deletion mutations. Moreover, spontaneous deletions of this specific region are associated with asymptomatic or exceptionally mild phenotypes. However, such multiple exon skipping of exons 45–55 has proved technically challenging. We have therefore designed antisense oligo (AO) morpholino mixtures to minimize self- or heteroduplex formation. These were tested as conjugates with cell-penetrating moieties (vivo-morpholinos). We have tested the feasibility of skipping exons 45–55 in H2K-mdx52 myotubes and in mdx52 mice, which lack exon 52. Encouragingly, with mixtures of 10 AOs, we demonstrated skipping of all 10 exons in vitro, in H2K-mdx52 myotubes and on intramuscular injection into mdx52 mice. Moreover, in mdx52 mice in vivo, systemic injections of 10 AOs induced extensive dystrophin expression at the subsarcolemma in skeletal muscles throughout the body, producing up to 15% of wild-type dystrophin protein levels, accompanied by improved muscle strength and histopathology without any detectable toxicity. This is a unique successful demonstration of effective rescue by exon 45–55 skipping in a dystrophin-deficient animal model.
Journal Article
Biomarker-focused multi-drug combination therapy and repurposing trial in mdx mice
Duchenne muscular dystrophy is initiated by dystrophin deficiency, but downstream pathophysiological pathways such as membrane instability, NFĸB activation, mitochondrial dysfunction, and induction of TGFβ fibrosis pathways are thought to drive the disability. Dystrophin replacement strategies are hopeful for addressing upstream dystrophin deficiency; however, all methods to date use semi-functional dystrophin proteins that are likely to trigger downstream pathways. Thus, combination therapies that can target multiple downstream pathways are important in treating DMD, even for dystrophin-replacement strategies. We sought to define blood pharmacodynamic biomarkers of drug response in the mdx mouse model of Duchenne muscular dystrophy using a series of repurposed drugs. Four-week-old mdx mice were treated for four weeks with four different drugs singly and in combination: vehicle, prednisolone, vamorolone, rituximab, β-aminoisobutyric acid (BAIBA) (11 treatment groups; n = 6/group). Blood was collected via cardiac puncture at study termination, and proteomic profiling was carried out using SOMAscan aptamer panels (1,310 proteins assayed). Prednisolone was tested alone and in combination with other drugs. It was found to have a good concordance of prednisolone-responsive biomarkers (56 increased by prednisolone, 39 decreased) focused on NFκB and TGFβ cascades. Vamorolone shared 45 (80%) of increased biomarkers and 13 (33%) of decreased biomarkers with prednisolone. Comparison of published human corticosteroid-responsive biomarkers to our mdx data showed 14% (3/22) concordance between mouse and human. Rituximab showed fewer drug-associated biomarkers, with the most significant being human IgG. On the other hand, BAIBA treatment (high and low dose) showed a drug-associated increase in 40 serum proteins and decreased 5 serum proteins. Our results suggest that a biomarker approach could be employed for assessing drug combinations in both mouse and human studies.
Journal Article
Sphingosine-1-Phosphate Enhances Satellite Cell Activation in Dystrophic Muscles through a S1PR2/STAT3 Signaling Pathway
Sphingosine-1-phosphate (S1P) activates a widely expressed family of G protein-coupled receptors, serves as a muscle trophic factor and activates muscle stem cells called satellite cells (SCs) through unknown mechanisms. Here we show that muscle injury induces dynamic changes in S1P signaling and metabolism in vivo. These changes include early and profound induction of the gene encoding the S1P biosynthetic enzyme SphK1, followed by induction of the catabolic enzyme sphingosine phosphate lyase (SPL) 3 days later. These changes correlate with a transient increase in circulating S1P levels after muscle injury. We show a specific requirement for SphK1 to support efficient muscle regeneration and SC proliferation and differentiation. Mdx mice, which serve as a model for muscular dystrophy (MD), were found to be S1P-deficient and exhibited muscle SPL upregulation, suggesting that S1P catabolism is enhanced in dystrophic muscle. Pharmacological SPL inhibition increased muscle S1P levels, improved mdx muscle regeneration and enhanced SC proliferation via S1P receptor 2 (S1PR2)-dependent inhibition of Rac1, thereby activating Signal Transducer and Activator of Transcription 3 (STAT3), a central player in inflammatory signaling. STAT3 activation resulted in p21 and p27 downregulation in a S1PR2-dependent fashion in myoblasts. Our findings suggest that S1P promotes SC progression through the cell cycle by repression of cell cycle inhibitors via S1PR2/STAT3-dependent signaling and that SPL inhibition may provide a therapeutic strategy for MD.
Journal Article
Natural Progression of Childhood Asthma Symptoms and Strong Influence of Sex and Puberty
Asthma prevalence, onset, remission and relapse, and healthcare use have been intensively studied. However, asthma symptom progression through childhood and adolescence has not been well studied, in part due to the challenges in obtaining consistent and robust long-term follow-up data on a large series of subjects with asthma.
To use the asthma diary symptom data of the Childhood Asthma Management Program placebo group (5 yr, 418 subjects, and total 564,518 records) to establish sex-specific high-resolution time courses of the natural progression of asthma symptoms through childhood and adolescence.
We used the asthma diary symptom code as a measure of daily disease severity. Annual records of Tanner stage were used to determine the influence of puberty on severity. A data alignment technique was used to derive 13-year time courses of mean symptoms and mean Tanner stage.
Data analyses showed three age- and sex-related phases of asthma symptom progression: Phase 1 (ages 5 and 6 yr)-greater severity in boys; Phase 2 (ages 7 to 9 yr)-no sex difference in severity; and Phase 3 (age 10-17 yr)-greater severity in girls. The continuous decline of symptoms in both sexes stops abruptly at the onset of puberty.
The severity of asthma symptoms varies through childhood and adolescence, and patterns differ by sex. Puberty has a strong influence on symptom progression in both sexes. Progression of symptoms is a distinct aspect of asthma epidemiology.
Journal Article
Myoblasts and macrophages are required for therapeutic morpholino antisense oligonucleotide delivery to dystrophic muscle
Exon skipping is a promising therapeutic strategy for Duchenne muscular dystrophy (DMD), employing morpholino antisense oligonucleotides (PMO-AO) to exclude disruptive exons from the mutant
DMD
transcript and elicit production of truncated dystrophin protein. Clinical trials for PMO show variable and sporadic dystrophin rescue. Here, we show that robust PMO uptake and efficient production of dystrophin following PMO administration coincide with areas of myofiber regeneration and inflammation. PMO localization is sustained in inflammatory foci where it enters macrophages, actively differentiating myoblasts and newly forming myotubes. We conclude that efficient PMO delivery into muscle requires two concomitant events: first, accumulation and retention of PMO within inflammatory foci associated with dystrophic lesions, and second, fusion of PMO-loaded myoblasts into repairing myofibers. Identification of these factors accounts for the variability in clinical trials and suggests strategies to improve this therapeutic approach to DMD.
Exon skipping is a strategy for the treatment of Duchenne muscular dystrophy, but has variable efficacy. Here, the authors show that dystrophin restoration occurs preferentially in areas of myofiber regeneration, where antisense oligonucleotides are stored in macrophages and delivered to myoblasts and newly formed myotubes
Journal Article