Showing papers by "Diego Albani published in 2020"

Organ-On-A-Chip in vitro Models of the Brain and the Blood-Brain Barrier and Their Value to Study the Microbiota-Gut-Brain Axis in Neurodegeneration.

Abstract: We are accumulating evidence that intestinal microflora, collectively named gut microbiota, can alter brain pathophysiology, but researchers have just begun to discover the mechanisms of this bidirectional connection (often referred to as microbiota-gut-brain axis, MGBA). The most noticeable hypothesis for a pathological action of gut microbiota on the brain is based on microbial release of soluble neurotransmitters, hormones, immune molecules and neuroactive metabolites, but this complex scenario requires reliable and controllable tools for its causal demonstration. Thanks to three-dimensional (3D) cultures and microfluidics, engineered in vitro models could improve the scientific knowledge in this field, also from a therapeutic perspective. This review briefly retraces the main discoveries linking the activity of gut microbiota to prevalent brain neurodegenerative disorders, and then provides a deep insight into the state-of-the-art for in vitro modeling of the brain and the blood-brain barrier (BBB), two key players of the MGBA. Several brain and BBB microfluidic devices have already been developed to implement organ-on-a-chip solutions, but some limitations still exist. Future developments of organ-on-a-chip tools to model the MGBA will require an interdisciplinary approach and the synergy with cutting-edge technologies (for instance, bioprinting) to achieve multi-organ platforms and support basic research, also for the development of new therapies against neurodegenerative diseases.

Genome-wide association study of over 40,000 bipolar disorder cases provides novel biological insights

Abstract: Bipolar disorder (BD) is a heritable mental illness with complex etiology. We performed a genome-wide association study (GWAS) of 41,917 BD cases and 371,549 controls of European ancestry, which identified 64 associated genomic loci. BD risk alleles were enriched in genes in synaptic signaling pathways and brain-expressed genes, particularly those with high specificity of expression in neurons of the prefrontal cortex and hippocampus. Significant signal enrichment was found in genes encoding targets of antipsychotics, calcium channel blockers, antiepileptics and anesthetics. Integrating eQTL data implicated 15 genes robustly linked to BD via gene expression, including druggable genes such as HTR6, MCHR1, DCLK3 and FURIN. This GWAS provides the best-powered BD polygenic scores to date, when applied in both European and diverse ancestry samples. Analyses of BD subtypes indicated high but imperfect genetic correlation between BD type I and II and identified additional associated loci. Together, these results advance our understanding of the biological etiology of BD, identify novel therapeutic leads and prioritize genes for functional follow-up studies.

Human Gut-Microbiota Interaction in Neurodegenerative Disorders and Current Engineered Tools for Its Modeling.

Abstract: The steady increase in life-expectancy of world population, coupled to many genetic and environmental factors (for instance, pre- and post-natal exposures to environmental neurotoxins), predispose to the onset of neurodegenerative diseases, whose prevalence is expected to increase dramatically in the next years. Recent studies have proposed links between the gut microbiota and neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Human body is a complex structure where bacterial and human cells are almost equal in numbers, and most microbes are metabolically active in the gut, where they potentially influence other target organs, including the brain. The role of gut microbiota in the development and pathophysiology of the human brain is an area of growing interest for the scientific community. Several microbial-derived neurochemicals involved in the gut-microbiota-brain crosstalk seem implicated in the biological and physiological basis of neurodevelopment and neurodegeneration. Evidence supporting these connections has come from model systems, but there are still unsolved issues due to several limitations of available research tools. New technologies are recently born to help understanding the causative role of gut microbes in neurodegeneration. This review aims to make an overview of recent advances in the study of the microbiota-gut-brain axis in the field of neurodegenerative disorders by: (a) identifying specific microbial pathological signaling pathways; (b) characterizing new, advanced engineered tools to study the interactions between human cells and gut bacteria.

A polygenic predictor of treatment-resistant depression using whole exome sequencing and genome-wide genotyping

Abstract: Treatment-resistant depression (TRD) occurs in ~30% of patients with major depressive disorder (MDD) but the genetics of TRD was previously poorly investigated. Whole exome sequencing and genome-wide genotyping were available in 1209 MDD patients after quality control. Antidepressant response was compared to non-response to one treatment and non-response to two or more treatments (TRD). Differences in the risk of carrying damaging variants were tested. A score expressing the burden of variants in genes and pathways was calculated weighting each variant for its functional (Eigen) score and frequency. Gene-based and pathway-based scores were used to develop predictive models of TRD and non-response using gradient boosting in 70% of the sample (training) which were tested in the remaining 30% (testing), evaluating also the addition of clinical predictors. Independent replication was tested in STAR*D and GENDEP using exome array-based data. TRD and non-responders did not show higher risk to carry damaging variants compared to responders. Genes/pathways associated with TRD included those modulating cell survival and proliferation, neurodegeneration, and immune response. Genetic models showed significant prediction of TRD vs. response and they were improved by the addition of clinical predictors, but they were not significantly better than clinical predictors alone. Replication results were driven by clinical factors, except for a model developed in subjects treated with serotonergic antidepressants, which showed a clear improvement in prediction at the extremes of the genetic score distribution in STAR*D. These results suggested relevant biological mechanisms implicated in TRD and a new methodological approach to the prediction of TRD.

A miniaturized hydrogel-based in vitro model for dynamic culturing of human cells overexpressing beta-amyloid precursor protein.

Abstract: Recent findings have highlighted an interconnection between intestinal microbiota and the brain, referred to as microbiota-gut-brain axis, and suggested that alterations in microbiota composition might affect brain functioning, also in Alzheimer's disease. To investigate microbiota-gut-brain axis biochemical pathways, in this work we developed an innovative device to be used as modular unit in an engineered multi-organ-on-a-chip platform recapitulating in vitro the main players of the microbiota-gut-brain axis, and an innovative three-dimensional model of brain cells based on collagen/hyaluronic acid or collagen/poly(ethylene glycol) semi-interpenetrating polymer networks and β-amyloid precursor protein-Swedish mutant-expressing H4 cells, to simulate the pathological scenario of Alzheimer's disease. We set up the culturing conditions, assessed cell response, scaled down the three-dimensional models to be hosted in the organ-on-a-chip device, and cultured them both in static and in dynamic conditions. The results suggest that the device and three-dimensional models are exploitable for advanced engineered models representing brain features also in Alzheimer's disease scenario.

A Conformation Variant of p53 Combined with Machine Learning Identifies Alzheimer Disease in Preclinical and Prodromal Stages.

Abstract: Early diagnosis of Alzheimer's disease (AD) is a crucial starting point in disease management. Blood-based biomarkers could represent a considerable advantage in providing AD-risk information in primary care settings. Here, we report new data for a relatively unknown blood-based biomarker that holds promise for AD diagnosis. We evaluate a p53-misfolding conformation recognized by the antibody 2D3A8, also named Unfolded p53 (U-p532D3A8+), in 375 plasma samples derived from InveCe.Ab and PharmaCog/E-ADNI longitudinal studies. A machine learning approach is used to combine U-p532D3A8+ plasma levels with Mini-Mental State Examination (MMSE) and apolipoprotein E epsilon-4 (APOEe4) and is able to predict AD likelihood risk in InveCe.Ab with an overall 86.67% agreement with clinical diagnosis. These algorithms also accurately classify (AUC = 0.92) Aβ+-amnestic Mild Cognitive Impairment (aMCI) patients who will develop AD in PharmaCog/E-ADNI, where subjects were stratified according to Cerebrospinal fluid (CSF) AD markers (Aβ42 and p-Tau). Results support U-p532D3A8+ plasma level as a promising additional candidate blood-based biomarker for AD.

3D brain tissue physiological model with co-cultured primary neurons and glial cells in hydrogels.

Abstract: Recently, researchers have focused on the role of gut microbiota on human health and reported the existence of a bidirectional relationship between intestinal microbiota and the brain, referred to ...

Higher polygenic risk scores for schizophrenia may be suggestive of treatment non-response in major depressive disorder

Abstract: Background Up to 60% of patients with major depressive disorder (MDD) do not respond to the first treatment with antidepressants. Response to antidepressants is a polygenic trait, although its underpinning genetics has not been fully clarified. This study aimed to investigate if Polygenic Risk Scores (PRSs) for major psychiatric disorders and neuroticism were associated with non-response or resistance to antidepressants in MDD. Methods PRSs for bipolar disorder, MDD, neuroticism, and schizophrenia (SCZ) were computed in 1148 MDD patients recruited by the European Group for the Study of Resistant Depression. Summary statistics from largest meta-analyses of genome-wide association studies were used as base data. Patients were classified as responders, non-responders to one treatment, non-responders to two or more treatments (treatment-resistant depression or TRD). Regression analyses were adjusted for population stratification and recruitment sites. Results PRSs did not predict either non-response or TRD after Bonferroni correction. However, SCZ-PRS was nominally associated with non-response (p=0.003). Patients in the highest SCZ-PRS quintile were more likely to be non-responders than those in the lowest quintile (OR=2.23, 95% CI=1.21-4.10, p=0.02). Patients in the lowest SCZ-PRS quintile showed higher response rates when they did not receive augmentation with second-generation antipsychotics (SGAs), while those in the highest SCZ-PRS quintile had a poor response independently from the treatment strategy (p=0.009). Conclusions A higher genetic liability to SCZ may reduce responsiveness to pharmacological treatment in MDD. From a clinical point of view, our results suggest that MDD patients with low SCZ-PRS do not benefit from augmentation with SGAs.

Mendelian randomization implies no direct causal association between leukocyte telomere length and amyotrophic lateral sclerosis

Abstract: We employed Mendelian randomization (MR) to evaluate the causal relationship between leukocyte telomere length (LTL) and amyotrophic lateral sclerosis (ALS) with summary statistics from genome-wide association studies (n = ~ 38,000 for LTL and ~ 81,000 for ALS in the European population; n = ~ 23,000 for LTL and ~ 4,100 for ALS in the Asian population). We further evaluated mediation roles of lipids in the pathway from LTL to ALS. The odds ratio per standard deviation decrease of LTL on ALS was 1.10 (95% CI 0.93-1.31, p = 0.274) in the European population and 0.75 (95% CI 0.53-1.07, p = 0.116) in the Asian population. This null association was also detected between LTL and frontotemporal dementia in the European population. However, we found that an indirect effect of LTL on ALS might be mediated by low density lipoprotein (LDL) or total cholesterol (TC) in the European population. These results were robust against extensive sensitivity analyses. Overall, our MR study did not support the direct causal association between LTL and the ALS risk in neither population, but provided suggestive evidence for the mediation role of LDL or TC on the influence of LTL and ALS in the European population.

Psychiatric disorders and SLC6A4 gene variants: possible effects on alcohol dependence and alzheimer’s disease

Abstract: Serotoninergic system is one of the most important neurotransmission systems investigated in the field of psychiatry. Extensive evidence reveals how alterations of this system, and especially of the SLC6A4 gene, may be associated with psychiatric disorders. In this study we aimed to evaluate the pleiotropic nature of SLC6A4 alterations and their association with the overall risk of brain diseases rather than disorder-specific. SLC6A4 variants, namely 5HTTLPR, STin2, rs2066713, rs25531, rs4251417, rs6354 and rs7224199 were investigated in 4 independent cohorts of subjects with specific psychiatric disorders, including Alcohol dependence disorder (ALC), Alzheimer disease (ALZ), Schizophrenia (SCZ) and Bipolar disorder (BPD). Other variables (biochemical parameters and Psychiatric scales scores) were also tested for association. SLC6A4 polymorphisms are not associated with the risk of developing major psychiatric disorders (SCZ and BPD); however some signals were detected in ALC (HTTLPR pd = 9.25 × 10−03, pr = 7.24 × 10−03; rs2066713 pd = 6.35 × 10−08; rs25531 pd = 2.95 × 10−02; rs4251417 pd = 2.46 × 10−03), and ALZ (rs6354 pr = 1.22 × 10−02; rs7224199 pd = 1.00 × 10−08, pr = 2.65 × 10−02) cohorts. Some associations were also observed on exploratory analyses. Our findings did not reveal any major influence on SCZ and BPD development; On the other hand, some alteration of the SLC6A4 sequence were associated with an increased risk of ALC and ALZ disorders, suggesting common pathways. The results of this study should be carefully interpreted since it suffers of some inherent limitations (e.g. cohort size, slight ethnic heterogeneity). Further analyses may provide better detail on the molecular processes behind SLC6A4 alterations.

Advantages and limitations of a supernegative GFP in facilitating MyoD intracellular tracking.

Abstract: Despite intracellular molecular dynamics being fundamental to understand pathological, biomechanical or biochemical events, several processes are still not clear because of the difficulty of monitoring and measuring these phenomena. To engineer an effective fluorescent tool useful to improve protein intracellular tracking studies, we fused a supernegative green fluorescent protein, (-30)GFP, to a myogenic transcription factor, MyoD. The (-30)GFP-MyoD was able to pass the plasma membrane when complexed with cationic lipids. Fluorescence confocal microscopy showed the protein delivery in just 3 hours with high levels of protein transduction efficiency. Confocal acquisitions also confirmed the maintenance of the MyoD nuclear localization. To examine how the supernegative GFP influenced MyoD activity, we did gene expression analyses, which showed an inhibitory effect of (-30)GFP on transcription factor function. This negative effect was possibly due to a charge-driven interference mechanism, as suggested by further investigations by molecular dynamics simulations. Summarizing these results, despite the functional limitations related to the charge structural characteristics that specifically affected MyoD function, we found (-30)GFP is a suitable fluorescent label for improving protein intracellular tracking studies, such as nucleocytoplasmic transport in mechanotransduction.

Cost-effectiveness of genetic and clinical predictors for choosing combined psychotherapy and pharmacotherapy in major depression

Abstract: Background Predictors of treatment outcome in major depressive disorder (MDD) could contribute to evidence-based therapeutic choices. This study tested the cost-effectiveness of a pharmacogenetic and clinical predictive model (PGx-CL-R) vs a clinical risk (CL-R) predictive model in guiding the assignment of combined pharmacotherapy and psychotherapy vs pharmacotherapy in MDD. Methods We hypothesized that the prescription of combined treatment, a strategy with evidence of increased efficacy vs pharmacotherapy, may be optimized based on the baseline risk of pharmacotherapy resistance, estimated through PGx-CL-R or CL-R predictive models. Both strategies were compared to standard care (ST, pharmacotherapy to all subjects). Treatment effects, costs and utilities (quality adjusted life years, QALYs) were based on the literature and included in a three-years Markov model. Results CL-R was cost-effective compared to PGx-CL-R, with ICER (incremental cost effect ratio) of £2341 (CL-R) and £3937 (PGx-CL-R) per QALY compared to ST. PGx-CL-R had similar or better ICER compared to ST only when 1) the cost of genotyping was £100 per subject or less or 2) the sensitivity of the PGx-CL-R test was at least 0.90 and the specificity at least 0.85. CL-R had ICER of £3664 and of £4110 when the CL-R model was tested in two independent samples. Limitations lack of validation in clinical trial. Conclusions Prediction of pharmacotherapy resistance according to clinical risk might be a cost-effective strategy if confirmed on large samples from the general population. Combined treatment with drugs having a very good tolerability profile could be a cheaper alternative to psychotherapy.

Current perspectives on the microbiota-gut-brain axis in chronic neurodegenerative disorders

Abstract: – Chronic neurodegenerative disorders are mostly due to population aging. These invalidating conditions include dementia (as Alzheimer’s disease AD) and movement disorders (as Parkinson’s disease PD). In the past decades, we have been accumulating experimental evidence on the molecular triggers of AD/PD and few approved drugs are available, unfortunately with no real disease-modifying action. As AD/PD cases constantly rise in the world, new hypothesis on their pathogenesis are actively under investigation. One of this is based on the microbiota-gut-brain axis, that postulates a direct or indirect influence of the microbial host community of human gut on the nervous system and its functions. This bidirectional interaction may play a role also in neurodegenerative disorders, even though research in this field requires models and tools for growing to a clinical translational perspective. To this respect, innovative in vitro engineered disease models are gaining attention, particularly because they feature desirable characteristics as tridimensional (3D) growing conditions and interstitial fluids movement recapitulation thanks to microfluidics. Here we summarize current data on the impact of gut microbiota on AD/PD models and patients, with a focus on ongoing research projects on the topic that are trying to unravel clinical questions or elaborate technical solutions for research and industry applications in the field. 1. THE MICROBIOTA-GUT-BRAIN AXIS AND NEURODEGENERATIVE