Поздняя форма болезни Помпе: диагностические и терапевтические подходы

Болезнь Помпе — клинически гетерогенное заболевание, в основе патогенеза которого лежит избыточное накопление гликогена лизосомами в результате мутации гена GAA и потери активности фермента кислой α‑глюкозидазы. Неонатальная форма заболевания, проявляющаяся сердечной, дыхательной и печеночной недостаточностью, имеет неблагоприятный прогноз. Поздние, медленно прогрессирующие хронические формы, проявляющиеся в возрасте после 1 года жизни с преимущественным поражением скелетной и дыхательной мускулатуры, имеют более благоприятное течение. Понимание и уточнение тонкостей патофизиологических процессов при болезни Помпе, а также разработка заместительной энзимотерапии (ЗЭТ) вызвали новую волну интереса к данной патологии. При ранних формах ЗЭТ имеет достаточно высокую эффективность в отличие от пациентов с поздними формами, что объясняется уже имеющимися значительными нарушениями клеточных и тканевых функций в результате избыточного накопления гликогена. С целью улучшения прогноза при поздних формах заболевания требуется как можно более раннее назначение ЗЭТ, что возможно только при своевременной постановке диагноза. Основным и самым простым способом диагностики болезни Помпе является определение активности фермента по сухому кровяному пятну. Вопрос о том, следует ли проводить ЗЭТ всем пациентам с поздней формой заболевания, остается открытым

A study on the safety and efficacy of reveglucosidase alfa in patients with late-onset Pompe disease.

BackgroundLate-onset Pompe disease is a rare genetic neuromuscular disorder caused by lysosomal acid alpha-glucosidase (GAA) deficiency that ultimately results in mobility loss and respiratory failure. Current enzyme replacement therapy with recombinant human (rh)GAA has demonstrated efficacy in subjects with late-onset Pompe disease. However, long-term effects of rhGAA on pulmonary function have not been observed, likely related to inefficient delivery of rhGAA to skeletal muscle lysosomes and associated deficits in the central nervous system. To address this limitation, reveglucosidase alfa, a novel insulin-like growth factor 2 (IGF2)-tagged GAA analogue with improved lysosomal uptake, was developed. This study evaluated the pharmacokinetics, safety, and exploratory efficacy of reveglucosidase alfa in 22 subjects with late-onset Pompe disease who were previously untreated with rhGAA.ResultsReveglucosidase alfa plasma concentrations increased linearly with dose, and the elimination half-life was <1.2 h. Eighteen of 22 subjects completed 72 weeks of treatment. The most common adverse events were hypoglycemia (63%), dizziness, fall, headache, and nausea (55% for each). Serious adverse events included hypersensitivity (n = 1), symptomatic hypoglycemia (n = 2), presyncope (n = 1), and acute cardiac failure (n = 1). In the dose-escalation study, all treated subjects tested positive for anti-reveglucosidase alfa, anti-rhGAA, anti-IGF1, and anti-IGF2 antibodies at least once. Subjects receiving 20 mg/kg of reveglucosidase alfa demonstrated increases in predicted maximum inspiratory pressure (13.9%), predicted maximum expiratory pressure (8.0%), forced vital capacity (-0.4%), maximum voluntary ventilation (7.4 L/min), and mean absolute walking distance (22.3 m on the 6-min walk test) at 72 weeks.ConclusionsAdditional studies are needed to further assess the safety and efficacy of this approach. Improvements in respiratory muscle strength, lung function, and walking endurance in subjects with LOPD may make up for the risk of hypersensitivity reactions and hypoglycemia. Reveglucosidase alfa may provide a new treatment option for patients with late-onset Pompe disease.Trial registrationISRCTN01435772 and ISRCTN01230801 , registered 27 October 2011

July 2017 ENCALS statement on edaravone

Peer reviewe

The D4Z4 Macrosatellite Repeat Acts as a CTCF and A-Type Lamins-Dependent Insulator in Facio-Scapulo-Humeral Dystrophy

Both genetic and epigenetic alterations contribute to Facio-Scapulo-Humeral Dystrophy (FSHD), which is linked to the shortening of the array of D4Z4 repeats at the 4q35 locus. The consequence of this rearrangement remains enigmatic, but deletion of this 3.3-kb macrosatellite element might affect the expression of the FSHD-associated gene(s) through position effect mechanisms. We investigated this hypothesis by creating a large collection of constructs carrying 1 to >11 D4Z4 repeats integrated into the human genome, either at random sites or proximal to a telomere, mimicking thereby the organization of the 4q35 locus. We show that D4Z4 acts as an insulator that interferes with enhancer–promoter communication and protects transgenes from position effect. This last property depends on both CTCF and A-type Lamins. We further demonstrate that both anti-silencing activity of D4Z4 and CTCF binding are lost upon multimerization of the repeat in cells from FSHD patients compared to control myoblasts from healthy individuals, suggesting that FSHD corresponds to a gain-of-function of CTCF at the residual D4Z4 repeats. We propose that contraction of the D4Z4 array contributes to FSHD physio-pathology by acting as a CTCF-dependent insulator in patients

A study on the safety and efficacy of reveglucosidase alfa in patients with late-onset Pompe disease

Abstract Background Late-onset Pompe disease is a rare genetic neuromuscular disorder caused by lysosomal acid alpha-glucosidase (GAA) deficiency that ultimately results in mobility loss and respiratory failure. Current enzyme replacement therapy with recombinant human (rh)GAA has demonstrated efficacy in subjects with late-onset Pompe disease. However, long-term effects of rhGAA on pulmonary function have not been observed, likely related to inefficient delivery of rhGAA to skeletal muscle lysosomes and associated deficits in the central nervous system. To address this limitation, reveglucosidase alfa, a novel insulin-like growth factor 2 (IGF2)-tagged GAA analogue with improved lysosomal uptake, was developed. This study evaluated the pharmacokinetics, safety, and exploratory efficacy of reveglucosidase alfa in 22 subjects with late-onset Pompe disease who were previously untreated with rhGAA. Results Reveglucosidase alfa plasma concentrations increased linearly with dose, and the elimination half-life was <1.2 h. Eighteen of 22 subjects completed 72 weeks of treatment. The most common adverse events were hypoglycemia (63%), dizziness, fall, headache, and nausea (55% for each). Serious adverse events included hypersensitivity (n = 1), symptomatic hypoglycemia (n = 2), presyncope (n = 1), and acute cardiac failure (n = 1). In the dose-escalation study, all treated subjects tested positive for anti-reveglucosidase alfa, anti-rhGAA, anti-IGF1, and anti-IGF2 antibodies at least once. Subjects receiving 20 mg/kg of reveglucosidase alfa demonstrated increases in predicted maximum inspiratory pressure (13.9%), predicted maximum expiratory pressure (8.0%), forced vital capacity (−0.4%), maximum voluntary ventilation (7.4 L/min), and mean absolute walking distance (22.3 m on the 6-min walk test) at 72 weeks. Conclusions Additional studies are needed to further assess the safety and efficacy of this approach. Improvements in respiratory muscle strength, lung function, and walking endurance in subjects with LOPD may make up for the risk of hypersensitivity reactions and hypoglycemia. Reveglucosidase alfa may provide a new treatment option for patients with late-onset Pompe disease. Trial registration ISRCTN01435772 and ISRCTN01230801 , registered 27 October 2011

Dystrophie musculaire facio-scapulo-humérale (étude physiopathologique sur myoblastes humains et applications en thérapie cellulaire)

La DMFSH est associée à une contraction de l allèle D4Z4 localisé sur le chromosome 4q35 et à une dérégulation de la transcription des gènes situés en proximité, parmi lesquels FRG1 et ANT1. Nous avons analysé les propriétés biologiques de myoblastes obtenus à partir de muscles non dystrophiques et dystrophiques de patients atteints de DMFSH et sujets contrôles, ainsi que l expression des gènes et protéines ANT1 et FRG1 et l épissage des certains pre-ARNms spécifiques par ces cellules. A la différence des myoblastes provenant des muscles non dystrophiques, ceux provenant des muscles dystrophiques montrent une morphologie altérée et un défaut dans la prolifération et la différenciation myogénique. Le défaut de prolifération est associé à un blocage du cycle cellulaire en G0/G1 et à un processus de sénescence cellulaire précoce. De façon intéressante, le degré de dystrophie des muscles de patients atteints de DMFSH corrèle d une part avec l importance des anomalies biologiques détectées dans les cultures cellulaires correspondantes et d autre part avec la surexpression de FRG1 et ANT1. De plus, la surexpression de la protéine FRG1 est associée avec la dérégulation de l épissage des pre-ARNms spécifiques. Nos résultats suggèrent que dans la DMFSH, l hétérogénéité de l atteinte musculaire dépend de la susceptibilité différentielle des myoblastes à la contraction du locus D4Z4, qui se traduit par une dérégulation spécifique de l expression de ANT1 et FRG1 et par des altérations de la biogenèse de ARNm. Ces résultats nous ont permis d envisager un essai clinique de phase I/II de transfert autologue des myoblastes chez des patients atteints de DMFSH. Les résultats préliminaires de cet essai sont présentés et discutés.FSHD is associated to contraction of D4Z4 allele on chromosome 4q35 inducing a deregulation in expression of some proximal genes, including ANT1 and FRG1. We analyzed the biological properties of myoblasts cultured from dystrophic and non dystrophic muscles of FSHD patients and matched controls, together with the gene and protein expression of FRG1 and ANT1, and the splicing pattern of specific pre-RNAs. In contrast with myoblasts derived from non dystrophic territories, myoblasts derived from dystrophic muscles display altered morphology, proliferation and differentiation abilities in vitro and in vivo. Proliferation defect is related to a cell cycle arrest at G0/G1 and to premature cell senescence. Interestingly, the degree of dystrophic changes in FSHD muscles correlates with the extent of the abnormalities detected in corresponding cell cultures and with FRG1 and ANT1 gene and protein over-expression. Moreover FRG1 overexpression is associated with aberrant splicing patterns of specific pre-RNAs. Based upon these results we speculate that, in FSHD, heterogeneity of muscle wasting might be related to different susceptibilities of myoblasts to D4Z4 contraction, resulting in differential ANT1 and FRG1 overexpression and aberrant splicing of specific pre-mRNAs. Moreover, a phase I/II clinical trial of autologous myoblast transfer was set up in our Department. The preliminary results will be presented and discussed.NICE-BU Sciences (060882101) / SudocSudocFranceF

Challenges in diagnosis and treatment of late-onset Pompe disease.

International audiencePURPOSE OF REVIEW: The first reports published in 2010 on enzyme replacement therapy in late-onset Pompe disease (LOPD) allow us now to stand back and adapt the strategies. In the meantime, substantial progress has been made in basic and applied research on animal models to enhance the efficacy of treatments. This brief review highlights the new concepts in a contemporary approach. RECENT FINDINGS: Interest in LOPD rose since its acknowledgement as a treatable myopathy. New insights from extensive analysis of injurious mechanisms resulted, over the past years, in the development of enzyme replacement therapy and a better understanding of its limits. SUMMARY: It seems reasonable to consider Pompe disease as a large spectrum of a single ubiquitous lysosomal disease resulting from an enzyme defect, more severe in newborns because of rapid cardiopulmonary and hepatic failures, with a much better prognosis when symptomatic after 12 months. This late-onset form demands therapy to avoid progressive motor disability and pulmonary insufficiency. Diagnosis is easy to confirm through rapid and reliable biochemical tests with sampling of blood dots on filter paper. When started early, treatment would avoid serious irrevocable damage to cells. Increasing precocity of diagnosis and efficacy of treatments are the core challenges for the next few years

Neuropathies périphériques et hémopathies B (de l'étude clinique des neuropathies associées à une gammapathie monoclonale IgM à activité anti-MAG au mécanisme de mort cellulaire induit par le Fingolimod (FTY720) dans les hémopathies B)

Les neuropathies à anticorps anti-MAG sont secondaires à une gammapathie monoclonale IgM dirigée contre la MAG des gaines de myéline des nerfs périphériques. Le traitement est celui de l hémopathie sous jacente. Même si les thérapeutiques sont de plus en plus efficaces, les hémopathies restent le plus souvent incurables. Le rituximab est couramment utilisé dans le traitement des neuropathies à anticorps anti MAG, mais son efficacité n a pas pu être clairement démontrée dans deux études contrôlées. Le FTY720 ou fingolimod est un sphingolipide, analogue de la sphingosine, qui inhibe les récepteurs de la sphingosine-1-phosphate (S1P). Il est utilisé comme immunosuppresseur dans la Sclérose en Plaques. Des études ont également rapporté un effet cytotoxique du FTY720 dans des hémopathies sans toutefois clairement expliquer son mécanisme d action. L objectif de ce travail est d élucider les mécanismes moléculaires de l effet cytotoxique du FTY720 dans un modèle d hémopathie B, la leucémie lymphoïde chronique (LLC). Des cellules leucémiques primaires de LLC et une lignée cellulaire MEC1 ont été utilisées comme modèle expérimental in vitro. Le FTY720, comme la sphingosine, entraîne une cytotoxicité dose dépendante dans la LLC. Cet effet, médié par la forme non phosphorylée de FTY720, est indépendant des récepteurs au S1P. Le FTY720 induit l expression de marqueurs d apoptose: exposition de la phosphaJdylsérine, clivage de PARP et de caspase 3. Cependant sa toxicité apparaît indépendante des caspases. La lipidation accrue de LC3 et la formation d autophagolysosomes indiquent que le FTY720 augmente également le flux autophagique. Cependant, des inhibiteurs de l autophagie ne permettent pas de bloquer la mort cellulaire induite par le FTY720, suggérant que l autophagie a ici un rôle protecteur vis à vis de la toxicité du FTY720. Plusieurs éléments permettent de conclure que le FTY720 est responsable d une nécrose cellulaire : aspect morphologique de nécrose en microscopie électronique, perméabilisation membranaire précoce avec relocalisation cytoplasmique de HMGB1, libération extracellulaire de LDH, perméabilisation de la membrane lysosomale associée à une activation des cathepsines. Au niveau moléculaire, l action du FTY720 n est pas bloquée par la nécrostatine 1, indiquant que la nécrose induite par le FTY720 est indépendante de RIPK1 (receptor interacJng protein 1), une kinase clef des voies extrinsèques de nécrose cellulaire programmée. Par contre, nos travaux ont établi l implication de DRP1 (dynamin related protein), une enzyme régulatrice de la fission mitochondriale, dans le processus de nécrose induite par le FTY720. En plus d une relocalisation précoce de DRP1 à la mitochondrie accompagnée d une augmentation de sa phosphorylation sur des sites régulateurs de son activité, nos expériences montrent que la suppression de son expression par interférence à ARN dans les cellules leucémiques réduit fortement la mort cellulaire induite par le FTY720. Le FTY720 est donc responsable dans la LLC d une nécrose cellulaire programmée dépendante de DRP1. Nos résultats illustrent l implication des sphingolipides dans la régulation de la survie cellulaire et dans les voies de nécrose programmée. Le FTY720 a un mode d action original différent de l apoptose induite par les chimiothérapies classiques. Le FTY720 pourrait donc être une alternative thérapeutique dans les néoplasies B résistantes aux chimiothérapies usuelles et dans certaines manifestations auto immunes des hémopathies comme les neuropathies à anticorps anti MAG.Fingolimod (FTY720) is an immunosuppressive drug that was recently approved for the treatment of multiple sclerosis and is currently under pre-clinical investigation as a therapy for a number of haematological malignancies. Previous studies have indicated a role for FTY720 in inducing autophagy and caspase-independent cell death in cancer cells through incompletely characterized molecular mechanisms. Our study thus aims at a beeer understanding of the way of action of FTY720. In chronic lymphocytic leukaemia (CLL) cells, FTY720 induced cell death with typical features of apoptosis, including phosphatidylserine exposure and caspase-3 activation, and features of autophagy, including LC3 conversion, autophagolysosome formation and lysosomal cathepsins activation. However, neither caspase nor autophagy blockade prevented the cytotoxic effect of FTY720, suggesting another mechanism of cell death. Using electron and fluorescence microscopy, flow cytometry and biochemical analyses, we found that FTY720 treatment increased a fraction of annexin V-/7-AAD+ cells both in primary and transformed leukemic cells and induced morphological changes representative of necrosis, including oncosis, mitochondrial and plasma membrane alteration. FTY720 treatment resulted in increased plasma membrane permeability as shown by the extracellular translocation of the nuclear high mobility group box 1 (HMGB1) protein and by the release into the culture medium of the cytosolic enzyme lactate dehydrogenase (LDH). Interestingly, cell death induced by FTY720 was not prevented by pharmacological inhibition of RIPK1 and PP2A. In contrast, FTY720- induced necrosis was accompanied by an early relocation to the mitochondria of Dynamin Related Protein 1, DRP1. Importantly, FTY720 stimulation led to ma tior changes in the phosphorylation of serine residues associated with the mitochondrial fission activity of DRP1. Finally, siRNA- mediated knockdown of DRP1 significantly reduced necrotic cell death induced by FTY720. In this study, we thus demonstrate that in leukemic cells the cytotoxic effect of the immunosuppressive drug Fingolimod involves a DRP1- dependent regulated necrosis. These observations are important in line of the future development of Fingolimod as a new therapeutic agent in haematological malignancies.NICE-Bibliotheque electronique (060889901) / SudocSudocFranceF

Facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is characterized by a typical and asymmetric pattern of muscle involvement and disease progression. Two forms of FSHD, FSHD1 and FSHD2, have been identified displaying identical clinical phenotype but different genetic and epigenetic basis. Autosomal dominant FSHD1 (95% of patients) is characterized by chromatin relaxation induced by pathogenic contraction of a macrosatellite repeat called D4Z4 located on the 4q subtelomere (FSHD1 patients harbor 1 to 10 D4Z4 repeated units). Chromatin relaxation is associated with inappropriate expression of DUX4, a retrogene, which in muscles induces apoptosis and inflammation. Consistent with this hypothesis, individuals carrying zero repeat on chromosome 4 do not develop FSHD1. Not all D4Z4 contracted alleles cause FSHD. Distal to the last D4Z4 unit, a polymorphic site with two allelic variants has been identified: 4qA and 4qB. 4qA is in cis with a functional polyadenylation consensus site. Only contractions on 4qA alleles are pathogenic because the DUX4 transcript is polyadenylated and translated into stable protein. FSHD2 is instead a digenic disease. Chromatin relaxation of the D4Z4 locus is caused by heterozygous mutations in the SMCHD1 gene encoding a protein essential for chromatin condensation. These patients also harbor at least one 4qA allele in order to express stable DUX4 transcripts. FSHD1 and FSHD2 may have an additive effect: patients harboring D4Z4 contraction and SMCHD1 mutations display a more severe clinical phenotype than with either defect alone. Knowledge of the complex genetic and epigenetic defects causing these diseases is essential in view of designing novel therapeutic strategies. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis

Place de la honte dans la clinique palliative : analyse du discours du malade atteint de SLA

La sclérose latérale amyotrophique est une maladie neurodégénérative grave au pronostic inéluctable, due à une altération du fonctionnement des cellules nerveuses qui commandent la motricité volontaire. Le travail clinique auprès des patients atteints de cette maladie fait apparaître un sentiment de honte caractéristique. L’hypothèse ici envisagée par les auteurs prend en compte les deux instances psychiques de la personnalité que sont l’Idéal du Moi et le Moi-Idéal dans l’oeuvre freudienne. Les éléments déterminants en sont : d’une part le rapport de l’Idéal du Moi avec l’expérience d’une atteinte narcissique et de la blessure irréversible qu’elle provoque, d’autre part le Moi-Idéal en rapport avec la déchéance ressentie dans la honte consécutive à la pathologie de la sclérose latérale amyotrophique, honte de se réduire à un objet de soins, honte de la déchéance infligée par la paralysie évolutive et ses radicales conséquences. Notre réflexion insiste, à travers des évocations cliniques, sur cette cooccurrence entre sclérose latérale amyotrophique, rupture des assises narcissiques et sentiment de honte