Neurobiological bases of autism and cellular models for its experimental study

Autism Spectrum Disorders (ASD) are a functional alteration of the cerebral cortex, which presents structural neurodevelopmental anomalies that affect synaptic function and the pattern of connections within and between cortical columns. From its etiological aspect, ASD has an important genetic load, considering a polygenic disorder, derived from a combination of "de novo" genetic mutations, associated to a predisposition derived from common inherited variations. The main genetic anomalies associated with ASD involve genes that encode proteins of the synapse. Thus, in patients with ASD, alterations in the initial development of the synapses have been described in the connection circuits between complex processing cortical areas. The molecular complexity observed in the predisposition to develop an ASD, together with the diversity of structural phenotypes, has made animal models reproduce only partially the ASD. To advance in the experimental study it is therefore necessary to develop representative models, such as cellular models derived from human cells. In recent decades, the advances in stem cell biology give us a way to apply experimental paradigms in cells derived from individuals with ASD. Currently, induced pluripotent cells (IPs) derived from human adult cells allow deepening the study of molecular and cellular bases of the neuronal development in humans, as well as the anomalies in this development, which give rise to disorders such as ASD. However, they present inherent problems derived from the experimental manipulation that involves the reprogramming of gene expression, therefore other models are also been explored

Neurobiological bases of autism and cellular models for its experimental study

[ES]: Los trastornos del espectro autista (TEA) son una alteración funcional de la corteza cerebral, que presenta anomalías estructurales del neurodesarrollo que afectan fundamentalmente a la función sináptica y el patrón de conexiones dentro y entre columnas corticales. Desde su aspecto etiológico, el TEA tiene una importante carga genética, considerándose un desorden derivado de una combinación de mutaciones “de novo”, asociadas a una predisposición derivada de variaciones comunes heredadas. Las principales anomalías genéticas asociadas a TEA implican genes que codifican proteínas de la sinapsis. Así, en pacientes con TEA se han descrito alteraciones del desarrollo inicial de las sinapsis en los circuitos de conexión entre áreas corticales de procesamiento complejo. La complejidad molecular observada en la predisposición a desarrollar un TEA, junto con la diversidad de fenotipos estructurales neuronales, ha hecho que los modelos animales reproduzcan solo parcialmente el TEA. Para avanzar en el estudio experimental se hace pues necesario desarrollar modelos más representativos, como son los modelos celulares derivados de células humanas. En las últimas décadas, el desa- rrollo de la biología de las células madre nos da medios para acceder a paradigmas experimentales sobre células derivadas de individuos con TEA. Actualmente, los modelos de células plutipotentes inducidas (IPs) derivadas de células humanas permiten profundizar en el estudio de las bases moleculares y celulares del TEA. Sin embargo, presentan problemas inherentes derivados de la manipulación experimental que conlleva la reprogramación de la expresión génica, por lo que otros modelos celulares se están también postulando como válidos.[EN]: Autism Spectrum Disorders (ASD) are a functional alteration of the cerebral cortex, which presents structural neuro- developmental anomalies that affect synaptic function and the pattern of connections within and between corti- cal columns. From its etiological aspect, ASD has an important genetic load, considering a polygenic disorder, derived from a combination of “de novo” genetic mutations, associated to a predisposition derived from common inherited variations. The main genetic anomalies associated with ASD involve genes that encode proteins of the synapse. Thus, in patients with ASD, alterations in the initial development of the synapses have been described in the connection circuits between complex processing cortical areas. The molecular complexity observed in the predisposition to develop an ASD, together with the diversity of structural phenotypes, has made animal models reproduce only partially the ASD. To advance in the experimental study it is therefore necessary to develop rep- resentative models, such as cellular models derived from human cells. In recent decades, the advances in stem cell biology give us a way to apply experimental paradigms in cells derived from individuals with ASD. Currently, induced pluripotent cells (IPs) derived from human adult cells allow deepening the study of molecular and cellular bases of the neuronal development in humans, as well as the anomalies in this development, which give rise to disorders such as ASD. However, they present inherent problems derived from the experimental manipulation that involves the reprogramming of gene expression, therefore other models are also been explored.Este trabajo ha sido financiado por los siguientes proyectos de investigación: FEDER BFU2011-27326, SAF2014-59347-C2-1-R and Severo Ochoa Excellence Project SEV-2013-0317; Instituto de Salud Carlos III: Red TERCEL RD12/0019/0024, Generalitat Valenciana: PROMETEO II/2014/014.Peer reviewe

Neurobiological bases of autistic spectrum disorder and attention deficit hyperactivity disorder: neural differentiation and synaptogenesis

[Objetivo] Conocer los procesos neurales ligados a la formación de sinapsis y circuitos cerebrales para entender su papel en las enfermedades del neurodesarrollo, como el trastorno del espectro autista (TEA) y el trastorno por déficit de atención/hiperactividad (TDAH).[Desarrollo] La actividad de los circuitos neuronales es la base neurobiológica de la conducta y la actividad mental (emociones, memoria y pensamientos). Los procesos de diferenciación de las células neurales y la formación de circuitos por contactos sinápticos entre neuronas (sinaptogénesis) ocurren en el sistema nervioso central durante las últimas fases del desarrollo prenatal y los primeros meses después del nacimiento. Los TEA y el TDAH comparten rasgos biológicos, relacionados con alteraciones en los circuitos cerebrales y la función sináptica, que permiten tratarlos científicamente de forma conjunta. Desde el aspecto neurobiológico, el TEA y el TDAH son manifestaciones de anomalías en la formación de circuitos y contactos sinápticos en regiones cerebrales implicadas en la conducta social, especialmente en la corteza cerebral prefrontal. Estas anomalías son causadas por mutaciones en genes involucrados en la formación de sinapsis y plasticidad sináptica, la regulación de la morfología de las espinas dendríticas, la organización del citoesqueleto y el control del equilibrio excitador e inhibidor en la sinapsis.[Conclusiones] El TEA y el TDAH son alteraciones funcionales de la corteza cerebral, que presenta anomalías estructurales en la disposición de las neuronas, en el patrón de conexiones de las columnas corticales y en la estructura de las espinas dendríticas. Estas alteraciones afectan fundamentalmente a la corteza prefrontal y sus conexiones.Peer reviewe

Novel aberrant genetic and epigenetic events in Friedreich's ataxia

It is generally accepted that Friedreich׳s ataxia (FRDA) is caused by a deficiency in frataxin expression, a mitochondrial protein involved in iron homeostasis, which mainly affects the brain, dorsal root ganglia of the spinal cord, heart and in certain cases the pancreas. However, there is little knowledge as to other possible genes that may be affected in this disorder, and which can contribute to its complexity. In the current study we compared human periodontal ligament cells gene expression of healthy individuals and FRDA patients. The expression of active-caspase 3, as well as other apoptosis-related genes, was increased in the FRDA cells. Furthermore, iron–sulphur cluster genes, as well as oxidative stress-related genes were overexpressed in FRDA. Moreover, brain-derived neurotrophic factor, neuregulin 1 and miR-132 were all upregulated. These three genes are capable of regulating the expression of each other. Interestingly, when the cells from FRDA patients were co-cultured in the presence of idebenone and deferiprone, caspase expression decreased while antioxidant gene expression, as well as frataxin expression, increased. Regarding epigenetic mechanisms, the frataxin gene was hypermethylated, compared to the healthy counterparts, in the upstream GAA repetitive region. Of the three DNA methyltransferases, DNMT1 but not DNMT3׳s gene expression was higher in FRDA cells. In conclusion, our data show that FRDA cells present altered expression of genes related to cell cycle, oxidative stress and iron homeostasis which may be implicated in the increased apoptotic levels. Also, the altered expression is in a certain degree normalized in the presence of idebenone and deferiprone.This work was supported by Ministerio de Sanidad y Asuntos Sociales, Plan Nacional de Drogras (2013I052), Spain; Friedreich Ataxia Research Alliance (FARA, BJ1/2012), Friedreich ataxia of Granadian Association (ASOGAF, JE61/2011) and (F5p-JE71/2012; WOPJE66/2013).Peer reviewe

Safety and biodistribution of human bone marrow-derived mesenchymal stromal cells injected intrathecally in non-obese diabetic severe combined immunodeficiency mice: Preclinical study

[Background]: Mesenchymal stromal cells (MSCs) have potent immunomodulatory and neuroprotective properties, and have been tested in neurodegenerative diseases resulting in meaningful clinical improvements. Regulatory guidelines specify the need to perform preclinical studies prior any clinical trial, including biodistribution assays and tumourigenesis exclusion. We conducted a preclinical study of human bone marrow MSCs (hBM-MSCs) injected by intrathecal route in Non-Obese Diabetic Severe Combined Immunodeficiency mice, to explore cellular biodistribution and toxicity as a privileged administration method for cell therapy in Friedreich’s Ataxia.[Methods]: For this purpose, 3 × 105 cells were injected by intrathecal route in 12 animals (experimental group) and the same volume of culture media in 6 animals (control group). Blood samples were collected at 24 h (n = 9) or 4 months (n = 9) to assess toxicity, and nine organs were harvested for histology and safety studies. Genomic DNA was isolated from all tissues, and mouse GAPDH and human β2M and β-actin genes were amplified by qPCR to analyze hBM-MSCs biodistribution.[Results]: There were no deaths nor acute or chronic toxicity. Hematology, biochemistry and body weight were in the range of normal values in all groups. At 24 h hBM-MSCs were detected in 4/6 spinal cords and 1/6 hearts, and at 4 months in 3/6 hearts and 1/6 brains of transplanted mice. No tumours were found.[Conclusion]: This study demonstrated that intrathecal injection of hBM-MSCs is safe, non toxic and do not produce tumors. These results provide further evidence that hBM-MSCs might be used in a clinical trial in patients with FRDA.This work was supported by the Fundación Mutua Madrileña (AP162842016), Asociación Granadina de Ataxia de Friederich (ASOGAF), Instituto de Salud Carlos III (ISCIII) Spanish Net of Cell Therapy (TerCel), RETICS subprogram of the I + D + I 2013–2016 Spanish National Plan, Projects “RD12/0019/0001”, “RD12/0019/0023”, “RD16/0011/0001” and “RD16/0011/0010” funded by ISCIII and co-founded by European Regional Development Funds.Peer reviewe

Modification of the risk of post-traumatic stress disorder (PTSD) by the 5-HTTLPR polymorphisms after Lorca's earthquakes (Murcia, Spain)

Preliminary results of this study were presented as a poster at the XVI World Congress of the World Psychiatry in Madrid, Spain, in September 2014; at XIX National Congress of Psychiatry in Palma de Mallorca, in October 2016; and at XVII SESPAS Congress (“Ciencia para la Acción”) in Barcelona, Septembre 2017.Information of the modulation effect of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) on post-traumatic stress disorder (PTSD) after earthquakes is scarce and contradictory. A cross-sectional face-to-face interview survey of a representative sample of the adults was carried out after the Lorca (Spain) earthquakes (May 11, 2011). Socio-demographic variables, DSM-IV diagnostic assessment and earthquake-related stressors were obtained from the Composite International Diagnostic Interview (CIDI). The triallelic and biallelic classification of the 5-HTTLPR polymorphism were genotyped from buccal swabs. Multivariate logistic regression models were used to predict PTSD, including interaction terms to explore gene-environment (G x E) interactions. The vast majority (83%, n = 341) of the Lorca survey respondents (n = 412, 71% response rate) were genotyped. Both classifications of the 5-HTTLPR genotype were in Hardy-Weinberg equilibrium. Prior lifetime PTSD was the only variable that remained a significant predictor after adjustments. There were no significant main effects of earthquake related stressors or 5-HTTLPR. However, G x E interactions of 5-HTTLPR with high emotional impact and prior lifetime anxiety disorders were statistically significant. These results provide new evidence of the modulation effect of the 5-HTTLPR polymorphisms on PTSD risk. This information might characterize people at higher risk of developing PTSD after an earthquake exposure.The PEGASUS-Murcia (Psychiatric Enquiry to General Population in Southeast Spain-Murcia) Project was supported by the Regional Health Authorities of Murcia (“Servicio Murciano de Salud and Consejería de Salud”) (Decreto n°: 455/2009, the “Fundación para la Formación e Investigación Sanitarias (FFIS) de la Región de Murcia” (N° Expedientes: CM0829 I and FFIDS/EMER09/14) and the “Ayudas para proyectos de Investigación en Salud ISCIII- del Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica” (PI12/00809). The PEGASUS-Murcia project was carried out in conjunction with the WHO-World Mental Health (WMH) Survey Initiative. WMH Coordinating Center staff at Harvard and Michigan Universities provided assistance with the instrumentation, fieldwork and data analysis. These activities were supported by the United States National Institute of Mental Health (R01MH070884), the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, the U.S. Public Health Service (R13-MH066849, R01- MH069864, and R01 DA016558), the Fogarty International Center (FIRCA R03- TW006481), the Pan American Health Organization, the Eli Lilly & Company Foundation, Ortho-McNeil Pharmaceutical, Inc., GlaxoSmithKline, Bristol- Myers Squibb and Shire.Peer reviewe

Childhood adversities and 5-HTTLPR polymorphism as risk factors of substance use disorders: retrospective case-control study in Murcia (Spain)

Objective To explore the separate and joint associations of childhood adversities and 5-HTTLPR polymorphism as risk factors for substance use disorders among adults. Design Retrospective case-control study. Setting Cases from the substance unit and controls from a representative sample of the adult general population in the metropolitan area of Murcia (Spain). Participants Cases were defined as outpatients 18 years old or older currently in the treatment for alcohol, opioids or cocaine use disorders in the clinical unit. Controls were randomly selected among individuals without substance use disorders who participated in the Psychiatric Enquiry to General Population in Southeast Spain-Murcia (PEGASUS-Murcia) project, a cross-sectional study of a representative sample of the adult general population. In all, 142 cases and 531 controls were interviewed and a subsample of 114 cases (80.3%) and 329 controls (62%) provided a biological sample. Exposure A history of 12 childhood adversities, lifetime mental disorders and sociodemographic variables was assessed with the Composite International Diagnostic Interview (CIDI)version 3.0). Buccal swabs were obtained to genotype the 5-HTTLPR polymorphism with the biallelic and the triallelic classification. Main outcome and measure Multivariable logistic regression models were performed to estimate adjusted ORs and 95% CI. Results Childhood adversities were associated with an elevated risk of substance use disorders (OR=5.77, 95% CI 3.46 to 9.61). Homozygotes for the short allele of the 5-HTTLPR polymorphism also showed the elevated risk of substance use disorders for the biallelic and triallelic classification: (1.97 (1.10 to 3.55) and 2.01 (1.11 to 3.64), respectively). No evidence for gene × environment interactions was found. Conclusions Childhood adversities and the 5-HTTLPR polymorphism are involved in the aetiology of substance use disorders though findings exploring the existence of a gene–environment interaction were inconclusive