Diagnóstico clínico e bioquímico da síndrome de Leigh em cinco pacientes colombianos

Leigh syndrome (LS) is a neurodegenerative disease, described as a subacute necrotizing encephalomyelopathy and is one of the most frequent diseases of mitochondrial origin. LS is caused by a deficit in the energy production due to defects in the genes that encode some of the mitochondrial complexes. The affected gene can be due to either nuclear and/or mitochondrial coding, which explains why there are different ways of inheriting the disease, including valoraautosomal recessive and maternal inheritance, which makes its molecular diagnosis even more difficult. Clinically, LS is characterized by regression in cognitive development and motor abilities, as well as movement disorders of rapid progression. Its diagnosis is based on the biochemical demonstration of an increase in lactic acid and lactate / pyruvate ratio, as well as magnetic resonance neuroimaging findings showing focal, bilateral and symmetric lesions in basal ganglia or brainstem associated with leukoencephalopathy and cerebral atrophy. Five cases are reported with clinical and biochemical diagnosis of LS that exemplify the clinical variability and severity found in this group of patients.El síndrome de Leigh (SL) es una enfermedad neurodegenerativa, descrita como una encefalomielopatía necrotizante subaguda, y es una de las enfermedades de origen mitocondrial más frecuentes. El SL es causado por el déficit en la producción de energía, originada en defectos en los genes que codifican alguno de los complejos mitocondriales; el gen afectado puede ser de codificación tanto nuclear como mitocondrial, lo que explica que se encuentren diferentes mecanismos de herencia, incluyendo autosómica recesiva y herencia materna, lo que, a su vez, hace más difícil su diagnóstico molecular. Clínicamente se presenta con regresión del desarrollo cognitivo y pérdida de habilidades motoras con trastorno de movimiento, de rápida progresión. El diagnóstico se basa en la demostración bioquímica de la elevación del ácido láctico y de la relación lactato/piruvato, así como hallazgos en las neuroimágenes por resonancia magnética que muestran lesiones focales, bilaterales y simétricas en ganglios basales o tallo cerebral asociadas a leucoencefalopatía y atrofia cerebral. Se reportan cinco casos con diagnóstico clínico y bioquímico del SL que ejemplifican la variabilidad clínica y gravedad encontrada en este grupo de pacientes.A síndrome de Leigh (SL) é uma doença neurodegenerativa, descrita como uma encefalomielopatia necrotizante subaguda e é uma das doenças de origem mitocondrial mais frequente. A SL é causada pelo déficit na produção de energia originada em defeitos nos genes que codificam algum dos complexos mitocondriais; o gene afetado pode ser de codificação tanto nuclear como mitocondrial, o que explica que se encontrem diferentes mecanismos de herança, incluindo autossômica recessiva e herança materna, o que torna mais difícil seu diagnóstico molecular. Clinicamente se apresenta com regressão do desenvolvimento do desenvolvimento cognitivo e perda de habilidades motoras com transtorno de movimento, de rápida progressão. O diagnóstico se baseia na demonstração bioquímica da elevação do ácido láctico e da relação lactato/piruvato, assim como descobertas nas neuro imagens por ressonância magnética que mostram lesões focais, bilaterais e simétricas em gânglios basais ou talo cerebral associadas a leucoencefalopatia e atrofia cerebral. Reportam-se cinco casos com diagnóstico clínico e bioquímico da SL que exemplificam a variabilidade clínica e gravidade encontrada neste grupo de pacientes

Therapeutic effects of the mitochondrial ROS-redox modulator KH176 in a mammalian model of Leigh Disease

Leigh Disease is a progressive neurometabolic disorder for which a clinical effective treatment is currently still lacking. Here, we report on the therapeutic efficacy of KH176, a new chemical entity derivative of Trolox, in Ndufs4 (-/-) mice, a mammalian model for Leigh Disease. Using in vivo brain diffusion tensor imaging, we show a loss of brain microstructural coherence in Ndufs4 (-/-) mice in the cerebral cortex, external capsule and cerebral peduncle. These findings are in line with the white matter diffusivity changes described in mitochondrial disease patients. Long-term KH176 treatment retained brain microstructural coherence in the external capsule in Ndufs4 (-/-) mice and normalized the increased lipid peroxidation in this area and the cerebral cortex. Furthermore, KH176 treatment was able to significantly improve rotarod and gait performance and reduced the degeneration of retinal ganglion cells in Ndufs4 (-/-) mice. These in vivo findings show that further development of KH176 as a potential treatment for mitochondrial disorders is worthwhile to pursue. Clinical trial studies to explore the potency, safety and efficacy of KH176 are ongoing

The role of tRNA synthetases in neurological and neuromuscular disorders.

Aminoacyl-tRNA synthetases (ARSs) are ubiquitously expressed enzymes responsible for charging tRNAs with their cognate amino acids, therefore essential for the first step in protein synthesis. Although the majority of protein synthesis happens in the cytosol, an additional translation apparatus is required to translate the 13 mitochondrial DNA-encoded proteins important for oxidative phosphorylation. Most ARS genes in these cellular compartments are distinct, but two genes are common, encoding aminoacyl-tRNA synthetases of glycine (GARS) and lysine (KARS) in both mitochondria and the cytosol. Mutations in the majority of the 37 nuclear-encoded human ARS genes have been linked to a variety of recessive and dominant tissue-specific disorders. Current data indicate that impaired enzyme function could explain the pathogenicity, however not all pathogenic ARSs mutations result in deficient catalytic function; thus, the consequences of mutations may arise from other molecular mechanisms. The peripheral nerves are frequently affected, as illustrated by the high number of mutations in cytosolic and bifunctional tRNA synthetases causing Charcot-Marie-Tooth disease (CMT). Here we provide insights on the pathomechanisms of CMT-causing tRNA synthetases with specific focus on the two bifunctional tRNA synthetases (GARS, KARS)

Modulation of oxidative phosphorylation and redox homeostasis in mitochondrial NDUFS4 deficiency via mesenchymal stem cells

Contains fulltext : 174432.pdf (publisher's version ) (Open Access)BACKGROUND: Disorders of the oxidative phosphorylation (OXPHOS) system represent a large group among the inborn errors of metabolism. The most frequently observed biochemical defect is isolated deficiency of mitochondrial complex I (CI). No effective treatment strategies for CI deficiency are so far available. The purpose of this study was to investigate whether and how mesenchymal stem cells (MSCs) are able to modulate metabolic function in fibroblast cell models of CI deficiency. METHODS: We used human and murine fibroblasts with a defect in the nuclear DNA encoded NDUFS4 subunit of CI. Fibroblasts were co-cultured with MSCs under different stress conditions and intercellular mitochondrial transfer was assessed by flow cytometry and fluorescence microscopy. Reactive oxygen species (ROS) levels were measured using MitoSOX-Red. Protein levels of CI were analysed by blue native polyacrylamide gel electrophoresis (BN-PAGE). RESULTS: Direct cellular interactions and mitochondrial transfer between MSCs and human as well as mouse fibroblast cell lines were demonstrated. Mitochondrial transfer was visible in 13.2% and 6% of fibroblasts (e.g. fibroblasts containing MSC mitochondria) for human and mouse cell lines, respectively. The transfer rate could be further stimulated via treatment of cells with TNF-alpha. MSCs effectively lowered cellular ROS production in NDUFS4-deficient fibroblast cell lines (either directly via co-culture or indirectly via incubation of cell lines with cell-free MSC supernatant). However, CI protein expression and activity were not rescued by MSC treatment. CONCLUSION: This study demonstrates the interplay between MSCs and fibroblast cell models of isolated CI deficiency including transfer of mitochondria as well as modulation of cellular ROS levels. Further exploration of these cellular interactions might help to develop MSC-based treatment strategies for human CI deficiency