Relevancia del metabolismo del folato en el contexto de enfermedades neurodegenerativas / Relevance of folate metabolism in neurodegenerative disorders

Introducción: Varias enfermedades neurodegenerativas están asociadas a alteraciones en el metabolismo del folato, lo que tiene sustanciales implicaciones fisiopatológicas, clínicas y terapéuticas potenciales. Objetivo: Reflejar la relevancia del metabolismo del folato para enfermedades neurodegenerativas, destacando su significación fisiopatológica y clínica, y sus implicaciones terapéuticas. Material y métodos: Se consultaron las bases de datos especializadas en busca de artículos publicados hasta marzo de 2020. Se emplearon descriptores específicos y operadores booleanos. Se empleó la estrategia de búsqueda avanzada para la selección de los artículos, teniendo en cuenta la calidad metodológica o validez de los estudios. Desarrollo: Fueron identificadas evidencias de asociación entre alteraciones del metabolismo del folato y enfermedades neurodegenerativas. Se han identificado variantes en genes que codifican enzimas involucradas en el metabolismo del folato, y modificaciones en patrones de metilación de ADN, asociadas al riesgo o a la gravedad clínica de las enfermedades de Alzheimer, Parkinson, Huntington, Temblor Esencial y Ataxia Espinocerebelosa tipo 2. Fueron encontradas asociaciones entre enfermedades neurodegenerativas y alteraciones en los niveles de metabolitos del folato, y la frecuencia de micronúcleos. Se han realizado varios estudios observacionales o experimentales que indican que la suplementación con ácido fólico y vitaminas B6 y B12, tiene utilidad terapéutica potencial en el contexto de enfermedades neurodegenerativas. Conclusiones: El metabolismo del folato es de relevancia fisiopatológica, clínica y terapéutica para enfermedades neurodegenerativas. El uso de estrategias dirigidas a restaurar los niveles normales de folatos o de co-factores enzimáticos involucrados en el metabolismo del folato, o a reducir la acumulación de homocisteína, tiene potenciales aplicaciones terapéuticas en el contexto de estas enfermedades(AU)

Introduction: Several neurodegenerative disorders are associated with alterations in folate metabolism, having essential physiopathological, clinical and therapeutic implications. Objective: To assess the relevance of folate metabolism in neurodegenerative disorders, highlighting its physiopathological, clinical and therapeutic significance. Material and Methods: Specialized biomedical databases were searched for studies published up to March 2020. Descriptors and Boolean operators were used. Advanced search strategy was used for the selection of articles, taking into account the methodological quality and validity of the studies. Results: Strong evidence of the association between folate metabolism and neurodegenerative disorders were identified. Enzyme-coding genes involved in folate metabolism and epigenetic DNA modifications associated with increased risk or disease severity in Alzheimer´s, Parkinson´s, and Huntington´s diseases, Essential Tremor, and Spinocerebellar ataxia type 2 were also identified. Associations between neurodegenerative disorders and altered levels of folate metabolites and the frequency of micronuclei were found. A number of observational and experimental studies have demonstrated that the supplementation with folic acid and vitamin B6 and B12 has therapeutic potential in the context of neurodegenerative disorders. Conclusions: Folate metabolism is of physiopathological, clinical and therapeutic relevance for neurodegenerative disorders. The use of strategies to normalize folate levels or enzyme cofactors involved in folate metabolism or to reduce homocysteine levels has potential therapeutic applications for these disorders(AU)

Acortamiento de telómeros en enfermedades neurodegenerativas: implicaciones terapéuticas / Telomere attrition in neurodegenerative disorders: therapeutic implications

Introducción: Varias enfermedades neurodegenerativas están asociadas a la ocurrencia de acortamiento de los telómeros, y los convierten en biomarcadores y dianas terapéuticas potenciales. Objetivo: Reflejar la relevancia del acortamiento de los telómeros para enfermedades neurodegenerativas, y destacar sus implicaciones Material y métodos: Se realizó una revisión bibliográfica durante los meses de septiembre de 2019 a enero de 2020. Fueron consultadas bases de datos de referencia, con el uso de descriptores y operadores booleanos. La estrategia de búsqueda avanzada para la selección de los artículos fue empleada, teniendo en cuenta la calidad metodológica o validez de los estudios. Desarrollo: Fueron identificadas evidencias sólidas de asociación entre el acortamiento de los telómeros y las enfermedades de Alzheimer y Huntington, que sugieren un papel relevante de la biología de los telómeros en la fisiopatología de estas enfermedades. Las evidencias disponibles hasta el momento no permiten establecer la relevancia de la biología de los telómeros en la fisiopatología de la Enfermedad de Parkinson o de la esclerosis lateral amiotrófica. Se obtuvieron evidencias de la utilidad de terapias orientadas a la prevención del acortamiento de los telómeros para el tratamiento de enfermedades neurodegenerativas. Conclusiones: El acortamiento de los telómeros es de relevancia fisiopatológica y clínica para las enfermedades de Alzheimer y Huntington, mientras que existen evidencias insuficientes para establecer su importancia en la Enfermedad de Parkinson y la esclerosis lateral amiotrófica. El uso de estrategias para estimular la actividad de la telomerasa tiene potenciales aplicaciones terapéuticas en el contexto de enfermedades neurodegenerativas(AU)

Introduction: Several neurodegenerative disorders are associated with telomere attrition, turning telomeres into potential biomarkers and potential therapeutic targets. Objective: To assess the relevance of telomere attrition for neurodegenerative disorders, highlighting its therapeutic implications. Material and methods: A literature review was carried out from September 2019 to January 2020. Several databases were searched by using descriptors and Boolean operators. Advanced search strategy was used for the selection of articles, taking into account the methodological quality and validity of the studies. Results: Strong evidence for an association between telomere attrition and Alzheimer and Huntington diseases was obtained, suggesting a potential importance of telomere biology in the physiopathology of these diseases. Current evidence does not allow establishing the relevance of telomere attrition in the physiopathology of Parkinson´s disease or Amyotrophic Lateral Sclerosis. Evidence was obtained for the usefulness of therapies for the prevention of telomere attrition in the treatment of neurodegenerative disorders. Conclusions: Telomere attrition has physiopathological and clinical relevance in Alzheimer´s and Huntington´s diseases, though current evidence is not enough to establish its role in Parkinson's disease and Amyotrophic Lateral Sclerosis. Strategies that enhance telomerase activity have therapeutic potential in the context of neurodegenerative disorders(AU)

Potencial uso terapéutico del ARN de interferencia contra la COVID-19 / Potential therapeutic use of RNA interference against COVID-19

Introducción: El SARS-CoV-2 es el agente causal de la COVID-19, enfermedad respiratoria que ha causado miles de víctimas fatales a escala global, y para la cual no existe ninguna terapia curativa efectiva. Objetivo: Reflejar la relevancia potencial de la tecnología de ARN de interferencia (ARNi), como alternativa terapéutica contra la COVID-19. Material y métodos: Se consultaron las bases de datos especializadas en busca de artículos publicados hasta abril de 2020. Se emplearon descriptores específicos y operadores booleanos. Se empleó la estrategia de búsqueda avanzada para la selección de los artículos, teniendo en cuenta la calidad metodológica o validez de los estudios. Desarrollo: Fueron identificadas evidencias de aplicación a nivel experimental de la tecnología de ARNi contra el SARS-CoV. Se han diseñado y evaluado varios ARNs pequeños interferentes y ARNs pequeños con estructura en lazo, orientados al silenciamiento de genes esenciales del SARS-CoV, incluyendo aquellos que codifican las proteínas S, RdRp, M, E, N, 3a/3b y 7a/7b. Se comprobó la efectividad de los ARNi en el silenciamiento de sus genes diana. Aunque la mayoría de estas investigaciones se han realizado en sistemas in vitro, también se ha comprobado la utilidad terapéutica de la administración intranasal de ARNi en un modelo de SARS-CoV in vivo. Conclusiones: La tecnología de ARNi ha mostrado potencialidades como estrategia terapéutica contra el SARS-CoV en modelos celulares y animales. Dadas las similitudes a nivel genómico y en cuanto al proceso patogénico entre SARS-CoV y SARS-CoV-2, esta tecnología es potencialmente aplicable el tratamiento de la COVID-19(AU)

Introduction: SARS-CoV-2 is the causal agent of COVID-19, a respiratory disease that has caused thousands of deaths globally for which there is no effective curative therapy. Objective: To demonstrate the potential relevance of RNA interference (RNAi) technology as a therapeutic alternative in the treatment of COVID-19. Materials and methods: Specialized biomedical databases were searched looking for studies published until April 2020. The search was carried out using descriptors and Boolean operators. Advanced search strategy was used for the selection of articles, taking into account the methodological quality and validity of the studies. Results: Evidence of experimental application of RNAi technology against SARS-CoV was identified. Several small interfering RNAs and small loop-structured RNAs oriented to the silencing of essential SARS-CoV genes including those encoding the S, RdRp, M, E, N, 3a/3b and 7a/7b proteins have been designed and evaluated. The effectiveness of RNAi for silencing its target genes was proven. Although most of these research studies have been conducted in in vitro systems, the therapeutic effectiveness of the intranasal administration of small RNA interference has also been proven in an in vivo SARS-CoV model. Conclusions: RNAi technology has demonstrated to be a potential therapeutic strategy against SARS-CoV in cellular and animal models. Given the similarities at the genomic level and in terms of the pathogenic process between SARS-CoV and SARS-CoV-2, this technology has a potential applicability for the treatment of COVID-19(AU)

Testosterone Levels Are Decreased and Associated with Disease Duration in Male Spinocerebellar Ataxia Type 2 Patients.

Spinocerebellar ataxia type 2 (SCA2) is a progressive neurodegenerative disorder due to an unstable expansion of a CAG repeat in the ATXN2 gene. Despite clinical and experimental evidence indicating the relevance of the gonadotropic axis to the prognosis and therapeutics for several late-onset neurodegenerative disorders, its functioning and association with disease severity have not been previously explored in SCA2. To assess serum levels of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), and their clinical relevance in SCA2 patients. A case-control study involving 94 Cuban SCA2 patients and 101 gender- and age-matched healthy controls was conducted. Testosterone, LH, and FSH serum levels were determined by radioimmunoassay or immunoradiometric assay systems. Clinical outcomes included age at onset, disease duration, Scale for the Assessment and Rating of Ataxia (SARA) score, and progression rate. Univariate general linear models were generated. Testosterone, LH, and FSH serum levels were significantly reduced in male SCA2 patients relative to control individuals. On average, there was a 35% reduction in testosterone levels in male patients versus male control individuals. Testosterone levels were associated with disease duration (r = 0.383; p = 0.025) and age at onset (r = 0.414; p = 0.011) in male SCA2 patients, but no association was observed between testosterone and CAG expansion size, SARA score, or progression rate. Testosterone levels might be a biomarker of disease progression in male SCA2 patients. Further studies are needed to explore the effects of low testosterone levels on non-motor symptoms, and to assess the potential of testosterone replacement therapy in male SCA2 patients.

One­carbon metabolism factor MTHFR variant is associated with saccade latency in Spinocerebellar Ataxia type 2.

BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder due to a CAG-repeat expansion. This work is intended to identify modifiers of the clinical phenotype in SCA2, following up on recent genome-wide association analyses that demonstrated the prominent role of DNA-damage repair and methylation for the severity and progression of polyglutamine diseases. In particular, we assessed the impact of MTHFR as rate-limiting enzyme in DNA methylation pathways, which modulates cerebellar neurotransmission and motor neuron atrophy. METHODS: A sample of 166 Cuban SCA2 patients and of 130 healthy subjects from the same geographical and ethnic background was selected. The ATXN2 CAG repeat length was determined by PCR followed by polyacrylamide gel electrophoresis. Two amino acid substitutions known to decrease the enzyme activity of MTHFR, encoded by C677T and A1298C polymorphisms, were assessed by PCR/RFLP. RESULTS: No significant differences were observed for C677T or A1298C alleles or genotype frequencies between cases and controls, confirming that disease risk in SCA2 does not depend on MTHFR activity. However, MTHFR A1298C genotypes showed a significant association with saccade latency. CONCLUSIONS: \MTHFR A1298C polymorphism is associated with saccade latency in SCA2 patients, but not with disease risk, age at onset or maximal saccade velocity. These results provide evidence that folate-mediated one­carbon metabolism might be important in the physiopathology of SCA2.

Aplicaciones de terapias de reemplazo celular al tratamiento de enfermedades poliglutamínicas / Applications of cell replacement therapies to the treatment of poly-glutamine diseases

Se realizó una revisión de la literatura especializada con el objetivo de evaluar el estado del arte en cuanto a la aplicación de terapias de reemplazo celular en enfermedades poliglutamínicas. Se consultaron las bases de datos HighWire y PubMed, con el uso de descriptores y operadores booleanos. Se recuperaron 84 artículos sobre la temática, publicados en revistas con un factor de impacto promedio de 5,42. Se discuten los estudios experimentales y pre-clínicos realizados con relación a terapias de reemplazo celular en enfermedades poliglutamínicas. Se demuestra la efectividad del uso de células madre de distintas fuentes en el mejoramiento de la función motora en modelos experimentales de enfermedades poliglutamínicas. Se revela la necesidad de realizar estudios multicéntricos a mediano y largo plazos, para la evaluación de los efectos terapéuticos de las terapias de reemplazo celular en enfermedades poliglutamínicas.

A review of the specialized literature was carried out with the aim of evaluating the state of the art regarding the application of cell replacement therapies in polyglutamine diseases. The HighWire and PubMed databases were consulted, with the use of Boolean descriptors and operators. 84 articles were retrieved on the subject, published in journals with an average impact factor of 5.42. The experimental and pre-clinical studies carried out in relation to cell replacement therapies in polyglutamine diseases are discussed. The effectiveness of the use of stem cells from different sources in the improvement of motor function in experimental models of polyglutamine diseases is demonstrated. The need to perform multicenter studies in the medium and long term is revealed, for the evaluation of the therapeutic effects of cell replacement therapies in polyglutamine diseases.

Buccal Cell Micronucleus Frequency Is Significantly Elevated in Patients with Spinocerebellar Ataxia Type 2.

Spinocerebellar ataxia type 2 (SCA2) is part of a group of at least nine dominantly inherited disorders characterized by progressive degeneration of specific neuronal populations and a shared mutational mechanism involving the expansion of a CAG repeat tract in coding regions of novel genes. Efforts have been made to identify biomarkers of disease progression, which would allow timely preventive therapeutic interventions. In the present study was assessed the influence of several genome instability biomarkers on SCA2 clinical severity. A case-control design was applied on exfoliated epithelial buccal cells to determine micronuclei frequency and others nuclear anomalies, using 5% Giemsa stains. The slides were analyzed under 1000X magnification and nuclei morphological anomalies were identified according to Tolbert PE, et al. (1992) and Bolognesi C, et al. (2013) criteria. It was found a highly significant increase in micronuclei frequency in cases related to age and sex-matched healthy controls (p <0.001). There was a trend for karyolytic, pyknotic and condensed chromatin cells to be increased in SCA2 cases, and a significant association was found between binucleated cells and disease duration (r = 0.46; p = 0.027). Nor the CAG repeat length neither the age at onset correlated significantly with any of the studied markers (p >0.05). Our results are consistent with report previous in similar neurodegenerative diseases, and suggest that micronuclei and binucleated cells constitute potential peripheral biomarkers for SCA2. These results should be validated by other studies.

Spinocerebellar Ataxia Type 2 Is Associated with the Extracellular Loss of Superoxide Dismutase but Not Catalase Activity.

BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) is an inherited and still incurable neurodegenerative disorder. Evidence suggests that pro-oxidant agents as well as factors involved in antioxidant cellular defenses are part of SCA2 physiopathology. AIM: To assess the influence of superoxide dismutase (SOD3) and catalase (CAT) enzymatic activities on the SCA2 syndrome. METHOD: Clinical, molecular, and electrophysiological variables, as well as SOD3 and CAT enzymatic activities were evaluated in 97 SCA2 patients and in 64 age- and sex-matched control individuals. RESULTS: Spinocerebellar ataxia type 2 patients had significantly lower SOD3 enzymatic activity than the control group. However, there were no differences between patients and controls for CAT enzymatic activity. The effect size for the loss of patients' SOD3 enzymatic activity was 0.342, corresponding to a moderate effect. SOD3 and CAT enzymatic activities were not associated with the CAG repeat number at the ATXN2 gene. SOD3 and CAT enzymatic activities did not show significant associations with the age at onset, severity score, or the studied electrophysiological markers. CONCLUSION: There is a reduced SOD3 enzymatic activity in SCA2 patients with no repercussion on the clinical phenotype.

Association of glutathione S-transferase omega polymorphism and spinocerebellar ataxia type 2.

BACKGROUND: Spinocerebellar ataxia type 2 is a neurodegenerative disorder caused by a CAG repeat expansion in ATXN2 gene. There is high clinical variability among affected patients suggesting the occurring of modifier genes influencing the clinical phenotype. OBJECTIVE: The objective is to assess the association of GSTO1 rs4925 and GSTO2 rs2297235 SNPs on the clinical phenotype in SCA2 patients. METHODS: A case-control study was performed in a sample of 120 SCA2 Cuban patients and 100 healthy subjects. Age at onset, 60° Maximal Saccade Velocity and SARA score were used as clinical markers. GSTO1 rs4925 and GSTO2 rs2297235 SNPs were determined by PCR/RFLP. RESULTS: Distribution of the GSTO1 alleles and genotypes was nearly equal between the control group and SCA2 patients. GSTO1 genotypes were not associated to clinical markers in SCA2 patients. Distribution of the GSTO2 "G" allele and "AG" genotype differed significantly between SCA2 patients and controls. Symptomatic SCA2 individuals had a 2.29-fold higher chance of carrying at least one "G" allele at GSTO2 rs2297235 than controls (OR=2.29, 95% CI: 1.29-4.04). GSTO2 genotypes were significantly associated to age at onset (p=0.037) but not to 60° Maximal Saccade Velocity or SARA score in SCA2 patients. CONCLUSION: The GSTO1 rs4925 polymorphism is not associated to SCA2. Meanwhile, the GSTO2 rs2297235 "AG" genotype is associated to SCA2 but failed to show any association with clinical markers, with the exception of a potential association with the age at disease onset.

Epigenetics DNA methylation in the core ataxin-2 gene promoter: novel physiological and pathological implications.

Pathogenic CAG (cytosine-adenine-guanine) expansions beyond certain thresholds in the ataxin-2 (ATXN2) gene cause spinocerebellar ataxia type 2 (SCA2) and were shown to contribute to Parkinson disease, amyotrophic lateral sclerosis and frontotemporal lobar degeneration. Regulation of ATXN2 gene expression and the function of the protein product are not known. SCA2 exhibits an inverse correlation between the size of the CAG repeat and the age at disease onset. However, a wide range of age at onset are typically observed, with CAG repeat number alone explaining only partly this variability. In this study, we explored the hypothesis that ATXN2 levels could be controlled by DNA methylation and that the derangement of this control may lead to escalation of disease severity and influencing the age at onset. We found that CpG methylation in human ATXN2 gene promoter is associated with pathogenic CAG expansions in SCA2 patients. Different levels of methylation in a SCA2 pedigree without an intergenerational CAG repeat instability caused the disease anticipation in a SCA2 family. DNA methylation also influenced the disease onset in SCA2 homozygotes and SCA3 patients. In conclusion, our study points to a novel regulatory mechanism of ATXN2 expression involving an epigenetic event resulting in differential disease course in SCA2 patients.

Efecto de la dosis genética sobre el fenotipo clínico en enfermedades poliglutamínicas / Genetic Dose Effect on Clinical Phenotype in Polyglutamine Diseases

Las enfermedades poliglutamínicas constituyen un grupo de patologías humanas causadas por la expansión de secuencias repetitivas de CAG En las familias afectadas, la edad de inicio de la enfermedad es altamente variable, lo cual se debe en su mayor parte al número de repeticiones de CAG en los alelos patológicos Ha sido sugerida la existencia de otros factores genéticos con efecto modificador sobre la edad inicio, entre los que se encuentra la dosis genética Aquí fue realizada una revisión de toda la evidencia disponible acerca del efecto fenotípico de la homocigosis para alelos patológicos en enfermedades poliglutamínicas A pesar de la muy baja frecuencia de casos homocigóticos para estas enfermedades en la población humana, la evidencia apoya un modelo según el cual en los homocigóticos los alelos patológicos tienen un efecto aditivo que agrava la presentación clínica Los estudios realizados en animales modelos para estas enfermedades corroboran esta afirmación...(AU)

Polyglutamine disorders constitute a group of human diseases caused by the expansion of repetitive sequences of the CAG. In affected families, the age at onset of the disease is highly variable, and most of it is due to the CAG repeat number in the pathological alleles Genetic factors with modifiable effect on the age at onset was suggested one of those is the genetic dose A review of the whole available evidence on the phenotype effect of the homozygosis state for pathologic alleles in polyglutamine disorders was analyzed. In spite of the very low frequency of homozygous cases for these disorders in human population, the results showed that in the homozygous individuals the pathologic alleles have an additive effect that increases the severity of the clinical presentation, these results were obtained through the studies that were carried out in a sample of animals...(AU)

Edad de inicio y riesgo genético en la Ataxia espinocerebelosa tipo 2 / Age at onset and genetic risk for Spinocerebellar ataxia type 2

La Ataxia espinocerebelosa tipo 2 (SCA2) es una enfermedad neurodegenerativa que alcanza las mayores tasas de incidencia y de prevalencia en Holguín, Cuba. Obtener estimados probabilísticos del riesgo dependiente de la edad, de haber heredado la mutación causante de la SCA2. Fueron revisadas las historias clínicas de 748 pacientes afectados pertenecientes a 101 familias con SCA2. El diagnóstico molecular fue realizado por PCR. La edad de inicio promedio fue de 33 años, y el 50(percent) de los pacientes fueron asintomáticos antes de los 31 años de edad. El riesgo empírico fue del 50(per cent) para individuos con 7 años de edad o menos, pero en los casos con 65 años o más, el riesgo disminuyó hasta casi un 0(percent). Existe una disminución progresiva del riesgo genético para la SCA2 a medida que avanza la edad del individuo. Los resultados son presentados como un apoyo para el asesoramiento genético de individuos en riesgo…(AU)

Biología molecular de la enfermedad de Huntington / Huntingtons Disease Molecular Biology

La enfermedad de Huntington es un trastorno neurodegenerativo hereditario que se presenta por lo general en personas de mediana edad. Es progresiva y sus síntomas incluyen movimientos involuntarios de la cara y las extremidades, cambios en el estado de ánimo y una tendencia a perder la memoria. Se debe a la expansión de una secuencia repetitiva de CAG contenida en el gen IT15, que codifica para una proteína poliglutamínica con una manifiesta tendencia a formar agregados intra o peri-nucleares. El descubrimiento de la mutación causal de esta enfermedad ha hecho posible la implementación de programas para el diagnóstico molecular, presintomático y prenatal, así como un significativo avance en la comprensión de los mecanismos moleculares involucrados y la búsqueda de opciones terapéuticas. En el trabajo se realizó una revisión bibliográfica de la biología molecular de este síndrome...(AU)

Huntington´s disease is a hereditary and neurodegenerative syndrome which is frequently presented in middle aged people. It is progressive and its principal symptoms include face and extremities involuntary movements , changes in mood and loss of memory due to a CAG expansion in the IT15 gene for a polyglutamine protein with a trend to aggregation. The discovery of the causal mutation makes possible the implementation of molecular, predictive and prenatal diagnosis programs, as well as a significant improvement on the molecular mechanisms understanding that are involved, and the therapeutic options. A review on the molecular biology of this disease was carried out...(AU)