Alteraciones de la autofagia mediadas por la acumulación de esfingomielina en la enfermedad de Niemann Pick tipo A

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular: Fecha de lectura: 04-06-2014Las enfermedades genéticas de depósito lisosomal se consideran enfermedades raras. Sin embargo, en conjunto las sufren 1 de cada 8000 habitantes afectando en la actualidad a casi un millón de pacientes, en su mayoría niños, sin posibilidad de tratamiento. Es por tanto urgente comprender los mecanismos moleculares patológicos en estas enfermedades para desarrollar terapias. El lisosoma es la etapa final de un proceso celular denominado autofagia que contribuye a degradar el material de desecho en las células siendo esencial para el mantenimiento de su homeostasis. El proceso de autofagia transcurre a través de un flujo mediado por la interacción de multitud de complejos proteicos y lípidos que finaliza con la fusión entre el autofagosoma y el lisosoma donde el cargo es degradado por las enzimas lisosomales. Este proceso es especialmente importante en neuronas y en consecuencia su alteración se ha asociado a numerosas enfermedades neurodegenerativas. A pesar de ello no se conoce el mecanismo por el que el flujo autofágico se ve afectado en muchas de ellas. En esta tesis nos hemos centrado en el estudio de las alteraciones en autofagia en la enfermedad de depósito lisosomal Niemann Pick tipo A causada por mutaciones en el gen de la esfingomielinasa ácida. Esta enfermedad cursa con una severa afectación neurológica que conduce a la muerte en la infancia. Nuestros estudios, realizados en cerebros de ratones carentes de la esfingomielinasa ácida que son un modelo de la enfermedad y en fibroblastos extraídos de pacientes, muestran la acumulación aberrante de vesículas de origen autofágico así como de sustratos de la autofagia no degradados. Los resultados indican que esta acumulación se debe a un bloqueo del flujo autofágico. Este bloqueo no está causado por alteraciones en la iniciación del proceso ni en la fusión entre autofagosomas y lisosomas si no por una deficiencia en la degradación final. Esto último se debe a la permeabilización parcial del lisosoma que deslocaliza en el citosol a la ezima lisosomal Catepsina B. Experimentos realizados en cultivos primarios de neuronas y en fibroblastos humanos en los que se moduló la cantidad de esfingomielina, lípido que se acumula por la falta de función de la esfingomielinasa ácida, apuntan al aumento de los niveles de este lípido como responsable de la permeabilización lisosomal y los problemas de autofagia. Nuestros resultados caracterizan los mecanismos patogénicos que subyacen a la enfermedad de Niemann Pick tipo A aportando además información sobre el relevante papel de la esfingomielina en la autofagia. Asimismo, ofrecen nuevas perspectivas para el desarrollo de una terapia para la enfermedad de Niemann Pick tipo A que podrían ser relevantes para otras enfermedades lisosomales donde también se acumula la esfingomielinaLysosomal Storage Disorders (LSDs) are considered rare diseases. However, altogether their incidence is 1 in 8000 births affecting one million people all over the world. Most LSDs impact pediatric population and are untreatable and fatal. It is therefore urgent to understand the molecular mechanisms underlying these pathologies in order to develop new therapies. The lysosome is the final step of a cellular process called autophagy, which contributes to eliminate cellular waste and is essential to maintein cellular homeostasis. The autophagy process progresses through a flux mediated by protein complex interactions and lipids. Its final stage is the fusion between autophagosomes and lysosomes where the cargo is degraded by lysosomal enzymes. This process is especially important in neurons. In agreement, alterations in the autophagy flux have been associated to several neurodegenerative disorders. Nonetheless, the mechanisms by which autophagy is impaired remain elusive in most of the diseases. In this PhD work we have focused on the study of autophagy alterations in Niemann Pick disease type A (NPA). This disease is a LSD caused by mutations in the gene encoding the acid sphingomyelinase. NPA is characterized by a severe neurological involvement leading to death early in childhood. Our studies carried out in brains from acid sphingomyelinase knockout mice, which are a model for the disease, as well as in primay fibroblast cultures obtained from NPA patients, show the aberrant accumulation of autophagic vesicles and of autophagy substrates. We found that this accumulation is due to blockage of the autophagy flux, which is not the consequence of initiation alterations or defective fusion between autophagosomes and lysosomes but of the deficient autophagolysosomal degradation. In turn, this is caused by the permeabilization of the lysosomal membrane, which leads to the cytosolic release of the lysosomal protease Cathepsin B. Experiments carried out in mouse neuronal cultures and human fibroblasts in which we modulated the amount of sphingomyelin, a lipid that accumulates upon acid sphingomyelinase loss of function, point to the increased levels of this lipid as the responsible of lysosomal membrane permeabilization and autophagy flux blockage. Our results characterize the molecular mechanisms underlying NPA, providing also information on the relevant role of sphingomyelin in autophagy. In addition, they offer new perspectives for the development of a therapy for NPA that might be also relevant for other LSDs in which sphingomyelin accumulate

Control of Inflammation by Calorie Restriction Mimetics: On the Crossroad of Autophagy and Mitochondria

Mitochondrial metabolism and autophagy are two of the most metabolically active cellular processes, playing a crucial role in regulating organism longevity. In fact, both mitochondrial dysfunction or autophagy decline compromise cellular homeostasis and induce inflammation. Calorie restriction (CR) is the oldest strategy known to promote healthspan, and a plethora of CR mimetics have been used to emulate its beneficial effects. Herein, we discuss how CR and CR mimetics, by modulating mitochondrial metabolism or autophagic flux, prevent inflammatory processes, protect the intestinal barrier function, and dampen both inflammaging and neuroinflammation. We outline the effects of some compounds classically known as modulators of autophagy and mitochondrial function, such as NAD+ precursors, metformin, spermidine, rapamycin, and resveratrol, on the control of the inflammatory cascade and how these anti-inflammatory properties could be involved in their ability to increase resilience to age-associated diseasesThis research was funded by the H2020-EU.1.1. European Research Council (ERC-2016-StG 715322-EndoMitTalk), and Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI16/188, PI19/855), Fondo Europeo de Desarrollo Regional (FEDER). M.M. is supported by the Miguel Servet program from Instituto de Salud Carlos III (CPII19/00014, Instituto de Investigación del Hospital 12 de Octubre

Rewiring Vascular Metabolism Prevents Sudden Death due to Aortic Ruptures-Brief Report.

The goal of this study was to determine whether boosting mitochondrial respiration prevents the development of fatal aortic ruptures triggered by atherosclerosis and hypertension. Ang-II (angiotensin-II) was infused in ApoE (Apolipoprotein E)-deficient mice fed with a western diet to induce acute aortic aneurysms and lethal ruptures. We found decreased mitochondrial respiration and mitochondrial proteins in vascular smooth muscle cells from murine and human aortic aneurysms. Boosting NAD levels with nicotinamide riboside reduced the development of aortic aneurysms and sudden death by aortic ruptures. Targetable vascular metabolism is a new clinical strategy to prevent fatal aortic ruptures and sudden death in patients with aortic aneurysms.This study was supported by the Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI16/188, PI19/855), the European Regional Development Fund (ERDF), and the European Commission through H2020-EU.1.1 and European Research Council grant ERC-2016-StG 715322-EndoMitTalk. This work was partially supported by Comunidad de Madrid (S2017/ BMD-3867 RENIM-CM), co-financed by European Structural and Investment Fund. M. Mittelbrunn is supported by the Miguel Servet Program (CP 19/014, Fundación de Investigación del Hospital 12 de Octubre). J. Oller and E. Gabandé-Rodríguez are supported by Juan de la Cierva (IJC2019-040152-I and IJC2018-036850-I respectively). Support was also provided by Ministerio de Ciencia e Innovación grants (RTI2018-099246-B-I00, Comunidad de Madrid and Fondo Social Europeo funds (AORTASANA-CM; J. Miguel Redondo), J. Miguel Redondo was also funded by Fundación La Caixa (HR18-00068), The Marfan Foundation USA and the CIBER-CV of Ministerio de Ciencia e Innovación (CB16/11/00264).S

T cells with dysfunctional mitochondria induce multimorbidity and premature senescence

The effect of immunometabolism on age-associated diseases remains uncertain. In this work, we show that T cells with dysfunctional mitochondria owing to mitochondrial transcription factor A (TFAM) deficiency act as accelerators of senescence. In mice, these cells instigate multiple aging-related features, including metabolic, cognitive, physical, and cardiovascular alterations, which together result in premature death. T cell metabolic failure induces the accumulation of circulating cytokines, which resembles the chronic inflammation that is characteristic of aging (“inflammaging”). This cytokine storm itself acts as a systemic inducer of senescence. Blocking tumor necrosis factor-a signaling or preventing senescence with nicotinamide adenine dinucleotide precursors partially rescues premature aging in mice with Tfam-deficient T cells. Thus, T cells can regulate organismal fitness and life span, which highlights the importance of tight immunometabolic control in both aging and the onset of age-associated diseases.This study was supported by the Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI16/02188 and PI19/00855; and PI16/02110 to B.I.), the European Regional Development Fund (ERDF), and the European Commission through H2020-EU.1.1 and European Research Council grant ERC-2016-StG 715322-EndoMitTalk. This work was partially supported by Comunidad de Madrid (S2017/BMD-3867 RENIM-CM). M.M. is supported by the Miguel Servet Program (CPII 19/00014). G.S.-H. is supported by FPI-UAM, J.O. (FJCI-2017-33855) and E.G.-R. (IJC2018-036850) by Juan de la Cierva, and E.C. by Atracción de Talento Investigador 2017-T2/BMD-5766 (Comunidad de Madrid and UAM). B.I. was supported by ERC research grant ERC-2018-CoG 819775-MATRIX

Extracellular Tuning of Mitochondrial Respiration Leads to Aortic Aneurysm

Marfan syndrome (MFS) is an autosomal dominant disorder of the connective tissue caused by mutations in the FBN1 (fibrillin-1) gene encoding a large glycoprotein in the extracellular matrix called fibrillin-1. The major complication of this connective disorder is the risk to develop thoracic aortic aneurysm. To date, no effective pharmacologic therapies have been identified for the management of thoracic aortic disease and the only options capable of preventing aneurysm rupture are endovascular repair or open surgery. Here, we have studied the role of mitochondrial dysfunction in the progression of thoracic aortic aneurysm and mitochondrial boosting strategies as a potential treatment to managing aortic aneurysms.Fondo de Investigacion Sanitaria del Instituto de Salud Carlos III (PI16/188, PI19/855), the European Regional D evelopment Fund, and the European Commission through H2020-EU.1.1, European Research Council grant ERC-2016-StG 715322-EndoMitTalk, and Gobierno de Espana SAF2016-80305P. This work was partially supported by Comunidad de Madrid (S2017/BMD 3867 RENIM-CM) and cofinanced by the European Structural and Investment Fund. M.M. is supported by the Miguel Servet Program (CP 19/014, Fundacion de Investigacion del Hospital 12 de Octubr

Immuno(T)herapy for age‐related diseases

During the last decade, the stimulation of T‐cell function by the blockage of immunosuppressive checkpoints has experienced an outstanding impact in the treatment of cancer. Development of the chimeric antigen receptor T‐cell technology has also emerged as a powerful alternative for patients suffering from oncological processes, especially those affected by hematological neoplasms. Recent evidence suggest that the use of immunotherapy could be extended to non‐oncological diseases and could be especially relevant for age‐associated disorders, opening exciting therapeutic options for a wide range of diseases of the elderly. Here we comment on the emergence of T‐cell‐based immunotherapies as feasible approaches that could revolutionize the future of GeroScience

The role of T cells in age-related diseases

Age-related T cell dysfunction can lead to failure of immune tolerance mechanisms, resulting in aberrant T cell-driven cytokine and cytotoxic responses that ultimately cause tissue damage. In this Review, we discuss the role of T cells in the onset and progression of age-associated conditions, focusing on cardiovascular disorders, metabolic dysfunction, neuroinflammation and defective tissue repair and regeneration. We present different mechanisms by which T cells contribute to inflammageing and might act as modulators of age-associated diseases, including through enhanced pro-inflammatory and cytotoxic activity, defective clearance of senescent cells or regulation of the gut microbiota. Finally, we propose that ‘resetting’ immune system tolerance or targeting pathogenic T cells could open up new therapeutic opportunities to boost resilience to age-related diseases.This study was supported by the Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI19/855), the European Regional Development Fund (ERDF) and the European Commission through H2020-EU.1.1, European Research Council grant ERC-2016-StG 715322-EndoMitTalk and the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with Universidad Autónoma de Madrid in the line of action encouraging youth research doctors, in the context of the V PRICIT (Regional Programme of Research and Technological Innovation) (SI1/PJI/2019-00073). M.M. is supported by the Miguel Servet Program (CP 19/014, Fundación de Investigación del Hospital 12 de Octubre). M.M.G.H. and E.G.-R. are supported by an FPU grant (FPU19/02576) and a Juan de la Cierva grant (IJC2018-036850-I), respectively, both from Ministerio de Ciencia, Innovación y Universidades (Spain).Peer reviewe

The role of T cells in age-related diseases

Age-related T cell dysfunction can lead to failure of immune tolerance mechanisms, resulting in aberrant T cell-driven cytokine and cytotoxic responses that ultimately cause tissue damage. In this Review, we discuss the role of T cells in the onset and progression of age-associated conditions, focusing on cardiovascular disorders, metabolic dysfunction, neuroinflammation and defective tissue repair and regeneration. We present different mechanisms by which T cells contribute to inflammageing and might act as modulators of age-associated diseases, including through enhanced pro-inflammatory and cytotoxic activity, defective clearance of senescent cells or regulation of the gut microbiota. Finally, we propose that ‘resetting’ immune system tolerance or targeting pathogenic T cells could open up new therapeutic opportunities to boost resilience to age-related diseases.Comisión EuropeaConsejo Europeo de InvestigaciónInstituto de Salud Carlos III/Fondo Europeo de Desarrollo RegionalUniversidad Autónoma de MadridPrograma Miguel ServetDepto. de Genética, Fisiología y MicrobiologíaFac. de Ciencias BiológicasTRUEpu

Seladin-1/DHCR24 Is Neuroprotective by Associating EAAT2 Glutamate Transporter to Lipid Rafts in Experimental Stroke

3β-Hydroxysteroid-Δ24 reductase (DHCR24) or selective alzheimer disease indicator 1 (seladin-1), an enzyme of cholesterol biosynthetic pathway, has been implicated in neuroprotection, oxidative stress, and inflammation. However, its role in ischemic stroke remains unexplored. The aim of this study was to characterize the effect of seladin-1/DHCR24 using an experimental stroke model in mice.status: publishe