sirolimus and Mitochondrial-Diseases

Preclinical work aimed at developing new therapies for mitochondrial diseases has recently given new hopes and opened unexpected perspectives for the patients affected by these pathologies. In contrast, only minor progresses have been achieved so far in the translation into the clinics. Many challenges are still ahead, including the need for a better characterization of the pharmacological effects of the different approaches and the design of appropriate clinical trials with robust outcome measures for this extremely heterogeneous, rare, and complex group of disorders. In this review, we will discuss the most important achievements and the major challenges in this very dynamic research field.

Topics: Animals; Antioxidants; Clinical Trials as Topic; Diet, Ketogenic; Genetic Therapy; Humans; Hypoxia; Mechanistic Target of Rapamycin Complex 1; Mitochondria; Mitochondrial Diseases; Mutation; Phenotype; Reactive Oxygen Species; Sirolimus

Aging results in progressive deteriorations in the structure and function of the heart and is a dominant risk factor for cardiovascular diseases, the leading cause of death in Western populations. Although the phenotypes of cardiac aging have been well characterized, the molecular mechanisms of cardiac aging are just beginning to be revealed. With the continuously growing elderly population, there is a great need for interventions in cardiac aging. This article will provide an overview of the phenotypic changes of cardiac aging, the molecular mechanisms underlying these changes, and will present some of the recent advances in the development of interventions to delay or reverse cardiac aging.

Topics: Aging; Animals; Calcium; Caloric Restriction; Cardiovascular Diseases; Extracellular Matrix; Female; Forecasting; Heart; Homeostasis; Humans; Longevity; Male; Mice; MicroRNAs; Mitochondrial Diseases; Models, Biological; Neurotransmitter Agents; Oxidative Stress; Renin-Angiotensin System; Signal Transduction; Sirolimus; Stem Cell Transplantation

Mitochondrial diseases represent a spectrum of disorders caused by impaired mitochondrial function, ranging in severity from mortality during infancy to progressive adult-onset disease. Mitochondrial dysfunction is also recognized as a molecular hallmark of the biological ageing process. Rapamycin, a drug that increases lifespan and health during normative ageing, also increases survival and reduces neurological symptoms in a mouse model of the severe mitochondrial disease Leigh syndrome. The Ndufs4 knockout (Ndufs4

Topics: Acarbose; Animals; Disease Models, Animal; Electron Transport Complex I; Leigh Disease; Mice; Mitochondria; Mitochondrial Diseases; Sirolimus

Mice missing the Complex I subunit NADH:Ubiquinone Oxidoreductase Fe-S Protein 4 (NDUFS4) of the electron transport chain are a leading model of the severe mitochondrial disease Leigh syndrome. These mice have enabled a better understanding of mitochondrial dysfunction in human disease, as well as in the discovery of interventions that can potentially suppress mitochondrial disease manifestations. In addition, increasing evidence suggests significant overlap between interventions that increase survival in NDUFS4 knockout mice and that extend life span during normative aging. This chapter discusses the practical aspects of handling and studying these mice, which can be challenging due to their severe disease phenotype. Common procedures such as breeding, genotyping, weaning, or treating these transgenic mice are also discussed.

Topics: Aging; Animal Feed; Animals; Electron Transport Complex I; Female; Genotyping Techniques; Humans; Leigh Disease; Male; Mice, Knockout; Mitochondrial Diseases; Sirolimus

Mitochondrial DNA (mtDNA) depletion syndrome (MDS) is a group of severe, tissue-specific diseases of childhood with unknown pathogenesis. Brain-specific MDS manifests as devastating spongiotic encephalopathy with no curative therapy. Here, we report cell type-specific stress responses and effects of rapamycin treatment and ketogenic diet (KD) in mice with spongiotic encephalopathy mimicking human MDS, as these interventions were reported to improve some mitochondrial disease signs or symptoms. These mice with astrocyte-specific knockout of

Topics: Animals; Astrocytes; Brain Diseases; Diet, Ketogenic; Disease Models, Animal; DNA Helicases; DNA Replication; DNA, Mitochondrial; Female; Ketosis; Male; Mice; Mice, Inbred C57BL; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Mutation; Neurons; Sirolimus; Stress, Physiological

Leigh syndrome is a fatal neurometabolic disorder caused by defects in mitochondrial function. Mechanistic target of rapamycin (mTOR) inhibition with rapamycin attenuates disease progression in a mouse model of Leigh syndrome (Ndufs4 knock-out (KO) mouse); however, the mechanism of rescue is unknown. Here we identify protein kinase C (PKC) downregulation as a key event mediating the beneficial effects of rapamycin treatment of Ndufs4 KO mice. Assessing the impact of rapamycin on the brain proteome and phosphoproteome of Ndufs4 KO mice, we find that rapamycin restores mitochondrial protein levels, inhibits signalling through both mTOR complexes and reduces the abundance and activity of multiple PKC isoforms. Administration of PKC inhibitors increases survival, delays neurological deficits, prevents hair loss and decreases inflammation in Ndufs4 KO mice. Thus, PKC may be a viable therapeutic target for treating severe mitochondrial disease.

Topics: Animals; Brain Chemistry; Down-Regulation; Electron Transport Complex I; Leigh Disease; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondrial Diseases; Protein Kinase C; Protein Kinase Inhibitors; Proteome; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Mitochondrial diseases represent a significant clinical challenge. Substantial efforts have been devoted to identifying therapeutic strategies for mitochondrial disorders, but effective interventions have remained elusive. Recently, we reported attenuation of disease in a mouse model of the human mitochondrial disease Leigh syndrome through pharmacological inhibition of the mechanistic target of rapamycin (mTOR). The human mitochondrial disorder MELAS/MIDD (Mitochondrial Encephalopathy with Lactic Acidosis and Stroke-like Episodes/Maternally Inherited Diabetes and Deafness) shares many phenotypic characteristics with Leigh syndrome. MELAS/MIDD often leads to organ failure and transplantation and there are currently no effective treatments. To examine the therapeutic potential of mTOR inhibition in human mitochondrial disease, four kidney transplant recipients with MELAS/MIDD were switched from calcineurin inhibitors to mTOR inhibitors for immunosuppression. Primary fibroblast lines were generated from patient dermal biopsies and the impact of rapamycin was studied using cell-based end points. Metabolomic profiles of the four patients were obtained before and after the switch. pS6, a measure of mTOR signaling, was significantly increased in MELAS/MIDD cells compared to controls in the absence of treatment, demonstrating mTOR overactivation. Rapamycin rescued multiple deficits in cultured cells including mitochondrial morphology, mitochondrial membrane potential, and replicative capacity. Clinical measures of health and mitochondrial disease progression were improved in all four patients following the switch to an mTOR inhibitor. Metabolomic analysis was consistent with mitochondrial function improvement in all patients.

Topics: Adult; Allografts; Animals; Calcineurin Inhibitors; Cells, Cultured; Deafness; Diabetes Mellitus, Type 2; Disease Progression; Female; Graft Rejection; Humans; Immunosuppressive Agents; Kidney; Kidney Failure, Chronic; Kidney Transplantation; Male; MELAS Syndrome; Membrane Potential, Mitochondrial; Mice; Middle Aged; Mitochondria; Mitochondrial Diseases; Primary Cell Culture; Sirolimus; TOR Serine-Threonine Kinases; Treatment Outcome

The vast majority of mitochondrial disorders have limited the clinical management to palliative care. Rapamycin has emerged as a potential therapeutic drug for mitochondrial diseases since it has shown therapeutic benefits in a few mouse models of mitochondrial disorders. However, the underlying therapeutic mechanism is unclear, the minimal effective dose needs to be defined and whether this therapy can be generally used is unknown.. We have evaluated whether low and high doses of rapamycin administration may result in therapeutic effects in a mouse model (Coq9. Low dose of rapamycin induces metabolic changes in liver and transcriptomics modifications in midbrain. The high dose of rapamycin induces further changes in the transcriptomics profile in midbrain due to the general inhibition of mTORC1. However, neither low nor high dose of rapamycin were able to improve the mitochondrial bioenergetics, the brain injuries and the phenotypic characteristics of Coq9. These results may be due to the lack of microgliosis-derived neuroinflammation, the limitation to induce autophagy, or the need of a functional CoQ-junction. Therefore, the translation of rapamycin therapy into the clinic for patients with mitochondrial disorders requires, at least, the consideration of the particularities of each mitochondrial disease. FUND: Supported by the grants from "Fundación Isabel Gemio - Federación Española de Enfermedades Neuromusculares - Federación FEDER" (TSR-1), the NIH (P01HD080642) and the ERC (Stg-337327).

Topics: Animals; Autophagy; Cell Respiration; Disease Models, Animal; Gene Expression Profiling; Humans; Metabolomics; Mice; Mitochondria; Mitochondrial Diseases; Mitochondrial Encephalomyopathies; Phenotype; Sirolimus; Treatment Outcome; Ubiquinone

Topics: Humans; Mitochondrial Diseases; Sirolimus

Mitochondrial disorders affecting oxidative phosphorylation (OxPhos) are caused by mutations in both the nuclear and mitochondrial genomes. One promising candidate for treatment is the drug rapamycin, which has been shown to extend lifespan in multiple animal models, and which was previously shown to ameliorate mitochondrial disease in a knock-out mouse model lacking a nuclear-encoded gene specifying an OxPhos structural subunit (Ndufs4). In that model, relatively high-dose intraperitoneal rapamycin extended lifespan and improved markers of neurological disease, via an unknown mechanism. Here, we administered low-dose oral rapamycin to a knock-in (KI) mouse model of authentic mtDNA disease, specifically, progressive mtDNA depletion syndrome, resulting from a mutation in the mitochondrial nucleotide salvage enzyme thymidine kinase 2 (TK2). Importantly, low-dose oral rapamycin was sufficient to extend Tk2KI/KI mouse lifespan significantly, and did so in the absence of detectable improvements in mitochondrial dysfunction. We found no evidence that rapamycin increased survival by acting through canonical pathways, including mitochondrial autophagy. However, transcriptomics and metabolomics analyses uncovered systemic metabolic changes pointing to a potential 'rapamycin metabolic signature.' These changes also implied that rapamycin may have enabled the Tk2KI/KI mice to utilize alternative energy reserves, and possibly triggered indirect signaling events that modified mortality through developmental reprogramming. From a therapeutic standpoint, our results support the possibility that low-dose rapamycin, while not targeting the underlying mtDNA defect, could represent a crucial therapy for the treatment of mtDNA-driven, and some nuclear DNA-driven, mitochondrial diseases.

Topics: Animals; Autophagy; Disease Models, Animal; DNA, Mitochondrial; Dose-Response Relationship, Drug; Electron Transport Complex I; Female; Gene Knock-In Techniques; Male; Mice; Mitochondria; Mitochondrial Diseases; Mutation; Oxidative Phosphorylation; Signal Transduction; Sirolimus; Syndrome; Thymidine Kinase

Pediatric mitochondrial disorders are a devastating category of diseases caused by deficiencies in mitochondrial function. Leigh Syndrome (LS) is the most common of these diseases with symptoms typically appearing within the first year of birth and progressing rapidly until death, usually by 6-7 years of age. Our lab has recently shown that genetic inhibition of the mechanistic target of rapamycin (TOR) rescues the short lifespan of yeast mutants with defective mitochondrial function, and that pharmacological inhibition of TOR by administration of rapamycin significantly rescues the shortened lifespan, neurological symptoms, and neurodegeneration in a mouse model of LS. However, the mechanism by which TOR inhibition exerts these effects, and the extent to which these effects can extend to other models of mitochondrial deficiency, are unknown. Here, we probe the effects of TOR inhibition in a Drosophila model of complex I deficiency. Treatment with rapamycin robustly suppresses the lifespan defect in this model of LS, without affecting behavioral phenotypes. Interestingly, this increased lifespan in response to TOR inhibition occurs in an autophagy-independent manner. Further, we identify a fat storage defect in the ND2 mutant flies that is rescued by rapamycin, supporting a model that rapamycin exerts its effects on mitochondrial disease in these animals by altering metabolism.

Topics: Animals; Animals, Genetically Modified; Autophagy; Disease Models, Animal; Drosophila melanogaster; Drosophila Proteins; Electron Transport Complex I; Lipid Metabolism; Longevity; Mitochondrial Diseases; Mutation; Oxidative Stress; Protein Kinase Inhibitors; Signal Transduction; Sirolimus; Time Factors; TOR Serine-Threonine Kinases

Mitochondrial respiratory chain (RC) disease therapies directed at intra-mitochondrial pathology are largely ineffective. Recognizing that RC dysfunction invokes pronounced extra-mitochondrial transcriptional adaptations, particularly involving dysregulated translation, we hypothesized that translational dysregulation is itself contributing to the pathophysiology of RC disease. Here, we investigated the activities, and effects from direct inhibition, of a central translational regulator (mTORC1) and its downstream biological processes in diverse genetic and pharmacological models of RC disease. Our data identify novel mechanisms underlying the cellular pathogenesis of RC dysfunction, including the combined induction of proteotoxic stress, the ER stress response and autophagy. mTORC1 inhibition with rapamycin partially ameliorated renal disease in B6.Pdss2(kd/kd) mice with complexes I-III/II-III deficiencies, improved viability and mitochondrial physiology in gas-1(fc21) nematodes with complex I deficiency, and rescued viability across a variety of RC-inhibited human cells. Even more effective was probucol, a PPAR-activating anti-lipid drug that we show also inhibits mTORC1. However, directly inhibiting mTORC1-regulated downstream activities yielded the most pronounced and sustained benefit. Partial inhibition of translation by cycloheximide, or of autophagy by lithium chloride, rescued viability, preserved cellular respiratory capacity and induced mitochondrial translation and biogenesis. Cycloheximide also ameliorated proteotoxic stress via a uniquely selective reduction of cytosolic protein translation. RNAseq-based transcriptome profiling of treatment effects in gas-1(fc21) mutants provide further evidence that these therapies effectively restored altered translation and autophagy pathways toward that of wild-type animals. Overall, partially inhibiting cytosolic translation and autophagy offer novel treatment strategies to improve health across the diverse array of human diseases whose pathogenesis involves RC dysfunction.

Topics: Animals; Autophagy; Cell Survival; Cycloheximide; Cytosol; Disease Models, Animal; Electron Transport; Endoplasmic Reticulum Stress; Enzyme Activation; Gene Expression Profiling; Humans; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Knockout; Mitochondria; Mitochondrial Diseases; Models, Biological; Multiprotein Complexes; Phosphorylation; Probucol; Protein Biosynthesis; Ribosomal Protein S6 Kinases; Sirolimus; TOR Serine-Threonine Kinases; Transcriptome

Topics: Animals; Leigh Disease; Mitochondrial Diseases; Molecular Targeted Therapy; Multiprotein Complexes; Neuroprotective Agents; Sirolimus; TOR Serine-Threonine Kinases

Mitochondrial dysfunction contributes to numerous health problems, including neurological and muscular degeneration, cardiomyopathies, cancer, diabetes, and pathologies of aging. Severe mitochondrial defects can result in childhood disorders such as Leigh syndrome, for which there are no effective therapies. We found that rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, robustly enhances survival and attenuates disease progression in a mouse model of Leigh syndrome. Administration of rapamycin to these mice, which are deficient in the mitochondrial respiratory chain subunit Ndufs4 [NADH dehydrogenase (ubiquinone) Fe-S protein 4], delays onset of neurological symptoms, reduces neuroinflammation, and prevents brain lesions. Although the precise mechanism of rescue remains to be determined, rapamycin induces a metabolic shift toward amino acid catabolism and away from glycolysis, alleviating the buildup of glycolytic intermediates. This therapeutic strategy may prove relevant for a broad range of mitochondrial diseases.

Topics: Animals; Brain; Disease Models, Animal; Electron Transport Complex I; Glycolysis; Leigh Disease; Mechanistic Target of Rapamycin Complex 1; Mice; Mice, Knockout; Mice, Mutant Strains; Mitochondria; Mitochondrial Diseases; Molecular Targeted Therapy; Multiprotein Complexes; Neuroprotective Agents; Sirolimus; TOR Serine-Threonine Kinases

Topics: Animals; Leigh Disease; Mechanistic Target of Rapamycin Complex 1; Mitochondrial Diseases; Molecular Targeted Therapy; Multiprotein Complexes; Neuroprotective Agents; Sirolimus; TOR Serine-Threonine Kinases

Increasing evidence implicates mitochondrial dysfunction as an early, important event in the pathogenesis of critical illness-induced multiple organ failure. We previously demonstrated that prevention of hyperglycemia limits damage to mitochondria in vital organs, thereby reducing morbidity and mortality. We now hypothesize that inadequate activation of mitochondrial repair processes (clearance of damaged mitochondria by autophagy, mitochondrial fusion/fission, and biogenesis) may contribute to accumulation of mitochondrial damage, persistence of organ failure, and adverse outcome of critical illness.. Prospective, randomized studies in a critically ill rabbit model.. University laboratory.. Three-month-old male rabbits.. We studied whether vital organ mitochondrial repair pathways are differentially affected in surviving and nonsurviving hyperglycemic critically ill animals in relation to mitochondrial and organ damage. Next, we investigated the impact of preventing hyperglycemia over time and of administering rapamycin as an autophagy activator.. In both liver and kidney of hyperglycemic critically ill rabbits, we observed signs of insufficient autophagy, including accumulation of p62 and a concomitant decrease in the microtubule-associated protein light-chain-3-II/microtubule-associated protein light-chain-3-I ratio. The phenotype of insufficient autophagy was more pronounced in nonsurviving than in surviving animals. Molecular markers of insufficient autophagy correlated with impaired mitochondrial function and more severe organ damage. In contrast, key players in mitochondrial fusion/fission or biogenesis were not significantly different regarding survival status. Therefore, we focused on autophagy to study the impact of preventing hyperglycemia. Both after 3 and 7 days of illness, autophagy was better preserved in normoglycemic than in hyperglycemic rabbits, which correlated with improved mitochondrial function and less organ damage. Stimulation of autophagy in kidney with rapamycin correlated with protection of renal function.. Our findings put forward insufficient autophagy as a potentially important contributor to mitochondrial and organ damage in critical illness and open perspectives for therapies that activate autophagy during critical illness.

Topics: Animals; Autophagy; Biomarkers; Critical Illness; Hyperglycemia; Immunosuppressive Agents; Kidney; Male; Microtubule-Associated Proteins; Mitochondria, Liver; Mitochondrial Diseases; Mitochondrial Dynamics; Mitophagy; Multiple Organ Failure; Prospective Studies; Rabbits; Random Allocation; Sirolimus; Survival Analysis