Sapaly Delphine, Cheguillaume Flore, Weill Laure, Clerc Zoé, Biondi Olivier, Bendris Sabrina, Buon Céline, Slika Rasha, Piller Elsie, Sundaram Venkat Krishnan, da Silva Ramos Andreia, Amador Maria Del Mar, Lenglet Timothée, Debs Rabab, Le Forestier Nadine, Pradat Pierre-François, Salachas François, Lacomblez Lucette, Hesters Adèle, Borderie Didier, Devos David, Desnuelle Claude, Rolland Anne-Sophie, Periou Baptiste, Vasseur Stéphane, Chapart Maud, Le Ber Isabelle, Fauret-Amsellem Anne-Laure, Millecamps Stéphanie, Maisonobe Thierry, Leonard-Louis Sarah, Behin Anthony, Authier François-Jérôme, Evangelista Teresinha, Charbonnier Frédéric, Bruneteau Gaëlle
University Paris Cité and Inserm UMR_S1124, 75270, 75006 Paris, France.
Laboratoire de Biologie de l'Exercice pour la Performance et la Santé (LBEPS), UMR, Université d'Evry, IRBA, Université de Paris Saclay, 91000 Évry-Courcouronnes, France.
Brain. 2025 Mar 6;148(3):788-802. doi: 10.1093/brain/awae270.
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting motor neurons, with a typical lifespan of 3-5 years. Altered metabolism is a key feature of ALS that strongly influences prognosis, with an increase in whole body energy expenditure and changes in skeletal muscle metabolism, including greater reliance on fat oxidation. Dyslipidaemia has been described in ALS as part of the metabolic dysregulation, but its role in the pathophysiology of the disease remains controversial. Among the lipids, cholesterol is of particular interest as a vital component of cell membranes, playing a key role in signal transduction and mitochondrial function in muscle. The aim of this study was to investigate whether motor dysfunction in ALS might be associated with dysregulation of muscle cholesterol metabolism. We determined cholesterol content and analysed the expression of key determinants of the cholesterol metabolism pathway in muscle biopsies from 13 ALS patients and 10 asymptomatic ALS-mutation gene carriers compared to 16 control subjects. Using human control primary myotubes, we investigated the potential contribution of cholesterol dyshomeostasis to reliance on mitochondrial fatty acid. We found that cholesterol accumulates in the skeletal muscle of ALS patients and that cholesterol overload significantly correlates with disease severity evaluated by the Revised ALS Functional Rating Scale. These defects are associated with overexpression of the genes of the lysosomal cholesterol transporters Niemann-Pick type C1 (NPC1) and 2 (NPC2), which are required for cholesterol transfer from late endosomes/lysosomes to cellular membranes. Most notably, a significant increase in NPC2 mRNA levels could be detected in muscle samples from asymptomatic ALS-mutation carriers, long before disease onset. We found that filipin-stained unesterified cholesterol accumulated in the lysosomal compartment in ALS muscle samples, suggesting dysfunction of the NPC1/2 system. Accordingly, we report here that experimental NPC1 inhibition or lysosomal pH alteration in human primary myotubes was sufficient to induce the overexpression of NPC1 and NPC2 mRNA. Finally, acute NPC1 inhibition in human control myotubes induced a shift towards a preferential use of fatty acids, thus reproducing the metabolic defect characteristic of ALS muscle. We conclude that cholesterol homeostasis is dysregulated in ALS muscle from the presymptomatic stage. Targeting NPC1/2 dysfunction may be a new therapeutic strategy for ALS to restore muscle energy metabolism and slow motor symptom progression.
肌萎缩侧索硬化症（ALS）是一种影响运动神经元的进行性神经退行性疾病，典型生存期为3至5年。代谢改变是ALS的一个关键特征，对预后有重大影响，表现为全身能量消耗增加以及骨骼肌代谢变化，包括对脂肪氧化的更大依赖。血脂异常在ALS中被描述为代谢失调的一部分，但其在疾病病理生理学中的作用仍存在争议。在脂质中，胆固醇作为细胞膜的重要组成部分特别受关注，它在肌肉的信号转导和线粒体功能中起关键作用。本研究的目的是调查ALS中的运动功能障碍是否可能与肌肉胆固醇代谢失调有关。我们测定了胆固醇含量，并分析了13例ALS患者、10例无症状ALS突变基因携带者以及16例对照受试者肌肉活检样本中胆固醇代谢途径关键决定因素的表达。利用人类对照原代肌管，我们研究了胆固醇稳态失衡对线粒体脂肪酸依赖的潜在影响。我们发现胆固醇在ALS患者的骨骼肌中积累，并且胆固醇过载与修订的ALS功能评定量表评估的疾病严重程度显著相关。这些缺陷与溶酶体胆固醇转运蛋白尼曼-皮克C1型（NPC1）和2型（NPC2）基因的过表达有关，这两种蛋白是胆固醇从晚期内体/溶酶体转运到细胞膜所必需的。最值得注意的是，在无症状ALS突变携带者的肌肉样本中，早在疾病发作之前就能检测到NPC2 mRNA水平显著升高。我们发现，在ALS肌肉样本中，荧光素染色的未酯化胆固醇在溶酶体区室中积累，提示NPC1/2系统功能障碍。因此，我们在此报告，在人类原代肌管中实验性抑制NPC1或改变溶酶体pH足以诱导NPC1和NPC2 mRNA的过表达。最后，在人类对照肌管中急性抑制NPC1会导致向优先使用脂肪酸的转变，从而重现了ALS肌肉的代谢缺陷特征。我们得出结论，在ALS肌肉中，从症状前期阶段开始胆固醇稳态就失调了。针对NPC1/2功能障碍可能是一种新的ALS治疗策略，以恢复肌肉能量代谢并减缓运动症状进展。
