Modelos experimentales aplicados al estudio de la eficacia y la seguridad de los antipsicóticos

[spa] La esquizofrenia es un trastorno psicótico grave con una prevalencia aproximada del 0,75% que se caracteriza por la presencia de síntomas positivos, negativos y déficits cognitivos. La enfermedad se inicia con una fase prodrómica donde los individuos presentan síntomas subclínicos que evidencian el deterioro funcional. El primer episodio psicótico (PEP) generalmente ocurre entre el final de la adolescencia y el principio de la edad adulta. Una vez diagnosticada sigue un curso fluctuante dando lugar a crisis psicóticas. En cuanto al tratamiento, los antipsicóticos son la única clase de fármacos con eficacia comprobada. No obstante, estos fármacos resultan ineficaces en el tratamiento de algunos de los síntomas de la enfermedad, como los síntomas negativos y los déficits cognitivos. Además, el uso de antipsicóticos conduce a la aparición de efectos adversos en algunos pacientes, entre los que destaca el síndrome metabólico. En la actualidad, no conocemos los mecanismos por los cuales algunos antipsicóticos inducen estas alteraciones metabólicas. Dado que el tratamiento actual con antipsicóticos presenta efectos secundarios y su efectividad se reduce al control de síntomas positivos, se están desarrollando nuevos fármacos. En base a la hipótesis glutamatérgica de la esquizofrenia, el JNJ-46356479 (JNJ), un modulador alostérico positivo de los receptores metabotrópicos de glutamato de tipo 2, podría resultar eficaz en el tratamiento de este trastorno. La presente tesis doctoral tiene como objetivo profundizar en los mecanismos moleculares involucrados en la aparición del síndrome metabólico inducido por antipsicóticos con el fin último de identificar marcadores predictivos de este efecto adverso, así como evaluar la eficacia del JNJ en distintos modelos experimentales. En concreto, se pretende identificar los cambios de expresión génica en ratón inducidos por el tratamiento antipsicótico que nos permitan hallar procesos biológicos y potenciales genes candidatos relacionados con el desarrollo de alteraciones metabólicas. En cuanto a la eficacia, se busca valorar el efecto neuroprotector y la actividad antiapoptótica del JNJ, en comparación con clozapina, en una línea celular de neuroblastoma humano, así como, evaluar su capacidad para revertir las alteraciones neuropatológicas y cognitivo-conductuales en un modelo animal de esquizofrenia generado mediante la administración postnatal de ketamina. Los resultados obtenidos indican que los antipsicóticos modifican la expresión de diversos genes involucrados en la regulación de los procesos metabólicos y señalan a EP300 como un gen candidato de las anomalías metabólicas inducidas por estos fármacos. Por otra parte, el tratamiento con JNJ ha demostrado no ser neurotóxico y atenuar la apoptosis, particularmente la activación de caspasa-3 inducida por dopamina y glutamato, en la línea celular de neuroblastoma. Además, el tratamiento con JNJ, administrado en ratones durante la adultez o de forma precoz en etapas correspondientes a la fase prodrómica de la enfermedad, ha mejorado parcialmente los déficits neuropatológicos y los síntomas negativos y cognitivos, mostrando una mayor eficacia que el tratamiento con clozapina. En conclusión, EP300 y los genes implicados en su red de interacción podrían considerarse genes candidatos para futuros estudios farmacogenéticos del síndrome metabólico inducido por antipsicóticos. Por otro lado, el JNJ podría ser un tratamiento eficaz para la esquizofrenia, aunque serían necesarios más estudios.[eng] Schizophrenia is a severe psychotic disorder with an approximate prevalence of 0.75% that is characterized by the presence of positive and negative symptoms and cognitive deficits. The disease begins with a prodromal phase where individuals present subclinical symptoms that show functional deterioration. The first psychotic episode (FPE) usually occurs between the end of adolescence and the beginning of adulthood. Once diagnosed, it follows a fluctuating course giving rise to psychotic crises. Regarding treatment, antipsychotics are the only class of drugs with proven efficacy. However, these drugs are ineffective in treating some of the symptoms of the disease, such as negative symptoms and cognitive deficits. In addition, the use of antipsychotics leads to the appearance of adverse effects in some patients, among which metabolic syndrome stands out. At present, we do not know the mechanisms by which some antipsychotics induce these metabolic alterations. Since current treatment with antipsychotics has side effects and its effectiveness is reduced to the control of positive symptoms, new drugs are being developed. Based on the glutamatergic hypothesis of schizophrenia, JNJ-46356479 (JNJ), a positive allosteric modulator of metabotropic glutamate receptors type 2, could be effective in the treatment of this disorder. This doctoral thesis aims to delve into the molecular mechanisms involved in the appearance of metabolic syndrome induced by antipsychotics with the ultimate goal of identifying predictive markers of this adverse effect, as well as evaluating the efficacy of JNJ in different experimental models. Specifically, the aim is to identify changes in gene expression in mice induced by antipsychotic treatment that allow us to find biological processes and potential candidate genes related to the development of metabolic disorders. Regarding efficacy, the aim is to assess the neuroprotective effect and antiapoptotic activity of JNJ, compared to clozapine, in a human neuroblastoma cell line, as well as to evaluate its ability to reverse neuropathological and cognitive-behavioural alterations in an animal model of schizophrenia generated by postnatal administration of ketamine. The results obtained indicate that antipsychotics modify the expression of various genes involved in the regulation of metabolic processes and point to EP300 as a candidate gene for the metabolic abnormalities induced by these drugs. On the other hand, JNJ treatment has been shown to be non-neurotoxic and to attenuate apoptosis, particularly caspase-3 activation induced by dopamine and glutamate, in the neuroblastoma cell line. In addition, treatment with JNJ, administered to mice during adulthood or in early stages corresponding to the prodromal phase of the disease, has partially improved neuropathological deficits and negative and cognitive symptoms, showing greater efficacy than treatment with clozapine. In conclusion, EP300 and the genes involved in its interaction network could be considered candidate genes for future pharmacogenetic studies of metabolic syndrome induced by antipsychotics. On the other hand, JNJ could be an effective treatment for schizophrenia, although more studies are needed

Early treatment with JNJ-46356479, a mGluR2 modulator, improves behavioral and neuropathological deficits in a postnatal ketamine mouse model of schizophrenia.

Positive allosteric modulators of the metabotropic glutamate receptor 2 (mGluR2), such as JNJ-46356479 (JNJ), may mitigate the glutamate storm during the early stages of schizophrenia (SZ), which could be especially useful in the treatment of cognitive and negative symptoms. We evaluated the efficacy of early treatment with JNJ or clozapine (CLZ) in reversing behavioral and neuropathological deficits induced in a postnatal ketamine (KET) mouse model of SZ. Mice exposed to KET (30 mg/kg) on postnatal days (PND) 7, 9, and 11 received JNJ or CLZ (10 mg/kg) daily in the adolescent period (PND 35-60). Mice exposed to KET did not show the expected preference for a novel object or for social novelty, but they recovered this preference with JNJ treatment. Similarly, KET group did not show the expected dishabituation in the fifth trial, but mice treated with JNJ or CLZ recovered an interest in the novel animal. Neuronal immunoreactivity also differed between treatment groups with mice exposed to KET showing a reduction in parvalbumin positive cells in the prefrontal cortex and decreased c-Fos expression in the hippocampus, which was normalized with the pharmacological treatment. JNJ-46356479 treatment in early stages may help improve the cognitive and negative symptoms, as well as certain neuropathological deficits, and may even obtain a better response than CLZ treatment. This may have relevant clinical translational applications since early treatment with mGluR2 modulators that inhibit glutamate release at the onset of critical phases of SZ may prevent or slow down the clinical deterioration of the disease

Link between cognitive polygenic risk scores and clinical progression after a first-psychotic episode

Background Clinical intervention in early stages of psychotic disorders is crucial for the prevention of severe symptomatology trajectories and poor outcomes. Genetic variability is studied as a promising modulator of prognosis, thus novel approaches considering the polygenic nature of these complex phenotypes are required to unravel the mechanisms underlying the early progression of the disorder. Methods The sample comprised of 233 first-episode psychosis (FEP) subjects with clinical and cognitive data assessed periodically for a 2-year period and 150 matched controls. Polygenic risk scores (PRSs) for schizophrenia, bipolar disorder, depression, education attainment and cognitive performance were used to assess the genetic risk of FEP and to characterize their association with premorbid, baseline and progression of clinical and cognitive status. Results Schizophrenia, bipolar disorder and cognitive performance PRSs were associated with an increased risk of FEP [false discovery rate (FDR) ⩽ 0.027]. In FEP patients, increased cognitive PRSs were found for FEP patients with more cognitive reserve (FDR ⩽ 0.037). PRSs reflecting a genetic liability for improved cognition were associated with a better course of symptoms, functionality and working memory (FDR ⩽ 0.039). Moreover, the PRS of depression was associated with a worse trajectory of the executive function and the general cognitive status (FDR ⩽ 0.001). Conclusions Our study provides novel evidence of the polygenic bases of psychosis and its clinical manifestation in its first stage. The consistent effect of cognitive PRSs on the early clinical progression suggests that the mechanisms underlying the psychotic episode and its severity could be partially independent

Metabolic polygenic risk scores effect on antipsychotic-induced metabolic dysregulation: A longitudinal study in a first episode psychosis cohort

[EN] Objective: Metabolic syndrome is a health-threatening condition suffered by approximately one third of schizophrenia patients and largely attributed to antipsychotic medication. Previous evidence reports a common genetic background of psychotic and metabolic disorders. In this study, we aimed to assess the role of polygenic risk scores (PRSs) on the progression of the metabolic profile in a first-episode psychosis (FEP) cohort. Method: Of the 231 FEP individuals included in the study, 192-220 participants were included in basal analysis and 118-179 in longitudinal 6-month models. Eleven psychopathologic and metabolic PRSs were constructed. Basal and longitudinal PRSs association with metabolic measurements was assessed by statistical analyses.Results: No major association of psychopathological PRSs with the metabolic progression was found. However, high risk individuals for depression and cholesterol-related PRSs reported a higher increase of cholesterol levels during the follow-up (FDR <= 0.023 for all analyses). Their effect was comparable to other well-established pharmacological and environmental risk factors (explaining at least 1.2% of total variance).Conclusion: Our findings provide new evidence of the effects of metabolic genetic risk on the development of metabolic dysregulation. The future establishment of genetic profiling tools in clinical procedures could enable practitioners to better personalize antipsychotic treatment selection and dosage

A longitudinal study of gene expression in first-episode schizophrenia; exploring relapse mechanisms by co-expression analysis in peripheral blood.

Little is known about the pathophysiological mechanisms of relapse in first-episode schizophrenia, which limits the study of potential biomarkers. To explore relapse mechanisms and identify potential biomarkers for relapse prediction, we analyzed gene expression in peripheral blood in a cohort of first-episode schizophrenia patients with less than 5 years of evolution who had been evaluated over a 3-year follow-up period. A total of 91 participants of the 2EPs project formed the sample for baseline gene expression analysis. Of these, 67 provided biological samples at follow-up (36 after 3 years and 31 at relapse). Gene expression was assessed using the Clariom S Human Array. Weighted gene co-expression network analysis was applied to identify modules of co-expressed genes and to analyze their preservation after 3 years of follow-up or at relapse. Among the 25 modules identified, one module was semi-conserved at relapse (DarkTurquoise) and was enriched with risk genes for schizophrenia, showing a dysregulation of the TCF4 gene network in the module. Two modules were semi-conserved both at relapse and after 3 years of follow-up (DarkRed and DarkGrey) and were found to be biologically associated with protein modification and protein location processes. Higher expression of DarkRed genes was associated with higher risk of suffering a relapse and early appearance of relapse (p = 0.045). Our findings suggest that a dysregulation of the TCF4 network could be an important step in the biological process that leads to relapse and suggest that genes related to the ubiquitin proteosome system could be potential biomarkers of relapse

Systematic Review of the Therapeutic Role of Apoptotic Inhibitors in Neurodegeneration and Their Potential Use in Schizophrenia

Schizophrenia (SZ) is a deleterious brain disorder affecting cognition, emotion and reality perception. The most widely accepted neurochemical-hypothesis is the imbalance of neurotransmitter-systems. Depleted GABAergic-inhibitory function might produce a regionally-located dopaminergic and glutamatergic-storm in the brain. The dopaminergic-release may underlie the positive psychotic-symptoms while the glutamatergic-release could prompt the primary negative symptoms/cognitive deficits. This may occur due to excessive synaptic-pruning during the neurodevelopmental stages of adolescence/early adulthood. Thus, although SZ is not a neurodegenerative disease, it has been suggested that exaggerated dendritic-apoptosis could explain the limited neuroprogression around its onset. This apoptotic nature of SZ highlights the potential therapeutic action of anti-apoptotic drugs, especially at prodromal stages. If dysregulation of apoptotic mechanisms underlies the molecular basis of SZ, then anti-apoptotic molecules could be a prodromal therapeutic option to halt or prevent SZ. In fact, risk alleles related in apoptotic genes have been recently associated to SZ and shared molecular apoptotic changes are common in the main neurodegenerative disorders and SZ. PRISMA-guidelines were considered. Anti-apoptotic drugs are commonly applied in classic neurodegenerative disorders with promising results. Despite both the apoptotic-hallmarks of SZ and the widespread use of anti-apoptotic targets in neurodegeneration, there is a strikingly scarce number of studies investigating anti-apoptotic approaches in SZ. We analyzed the anti-apoptotic approaches conducted in neurodegeneration and the potential applications of such anti-apoptotic therapies as a promising novel therapeutic strategy, especially during early stages

The Effect of Clozapine and Novel Glutamate Modulator JNJ-46356479 on Nitrosative Stress in a Postnatal Murine Ketamine Model of Schizophrenia

Schizophrenia (SZ) is a heterogeneous mental disorder, affecting ~1% of the worldwide population. One of the main pathophysiological theories of SZ is the imbalance of excitatory glutamatergic pyramidal neurons and inhibitory GABAergic interneurons, involving N-methyl-D-aspartate receptors (NMDAr). This may lead to local glutamate storms coupled with excessive dendritic pruning and subsequent cellular stress, including nitrosative stress, during a critical period of neurodevelopment, such as adolescence. Nitrosative stress is mediated by nitric oxide (NO), which is released by NO synthases (NOS) and has emerged as a key signaling molecule implicated in SZ. Regarding glutamatergic models of SZ, the administration of NMDAr antagonists has been found to increase NOS levels in the prefrontal cortex (PFC) and ventral hippocampus (HPC). We hypothesized that suboptimal NOS function in adolescence could be a target for early treatments, including clozapine (CLZ) and the novel metabotropic glutamate receptor modulator JNJ-46356479 (JNJ). We analyzed the protein levels of NOS isoforms in adult PFC and HPC of a postnatal ketamine induced murine model of SZ receiving CLZ or JNJ during adolescence by western blot. Endothelial NOS and neuronal NOS increased under ketamine administration in PFC and decreased in CLZ or JNJ treatments. The same trends were found in the HPC in neuronal NOS. In contrast, inducible NOS was increased under JNJ treatment with respect to ketamine induction in the HPC, and the same trends were found in the PFC. Taken together, our findings suggest a misbalance of the NOS system following NMDAr antagonist administration, which was then modulated under early CLZ and JNJ treatments

Metabolic polygenic risk scores effect on antipsychotic-induced metabolic dysregulation: A longitudinal study in a first episode psychosis cohort

Objective: Metabolic syndrome is a health-threatening condition suffered by approximately one third of schizophrenia patients and largely attributed to antipsychotic medication. Previous evidence reports a common genetic background of psychotic and metabolic disorders. In this study, we aimed to assess the role of polygenic risk scores (PRSs) on the progression of the metabolic profile in a first-episode psychosis (FEP) cohort. Method: Of the 231 FEP individuals included in the study, 192-220 participants were included in basal analysis and 118-179 in longitudinal 6-month models. Eleven psychopathologic and metabolic PRSs were constructed. Basal and longitudinal PRSs association with metabolic measurements was assessed by statistical analyses. Results: No major association of psychopathological PRSs with the metabolic progression was found. However, high risk individuals for depression and cholesterol-related PRSs reported a higher increase of cholesterol levels during the follow-up (FDR ≤ 0.023 for all analyses). Their effect was comparable to other well-established pharmacological and environmental risk factors (explaining at least 1.2% of total variance). Conclusion: Our findings provide new evidence of the effects of metabolic genetic risk on the development of metabolic dysregulation. The future establishment of genetic profiling tools in clinical procedures could enable practitioners to better personalize antipsychotic treatment selection and dosage