Biology subjects

Bozzi, Y.

Publications and source records attributed to Bozzi, Y..

12 recordsLinked to original sources

bioRxiv2025

Developmental excitation-inhibition imbalance permanently reprograms autism-relevant social brain circuits

An influential theory proposes that an imbalance between excitation and inhibition (E:I) plays a central role in the etiology of autism and related developmental disorders. However, controversy exists as to whether this imbalance is a direct causal mechanism for autism, or a compensatory response to other primary etiological factors. Using chemogenetic manipulations in neonatal mice, we show that a transient E:I imbalance during development is sufficient to permanently reprogram autism-relevant social brain circuits. Chemogenetically manipulated mice exhibit lifelong impairments in sociability, persistent dysregulation of multiple autism-risk synaptic genes, and sustained cortical hyperexcitability in adulthood. Importantly, these social impairments are robustly rescued by pharmacological inhibition of neuronal excitability. Developmental E:I imbalance also disrupts functional connectivity in social brain regions enriched for transcriptionally dysregulated genes, suggesting a convergence of transcriptional and circuit-level pathology. Finally, multivariate modelling shows that behavioral dysfunction in chemogenetically manipulated animals closely associates with disrupted connectivity between prefrontal and mesolimbic dopaminergic regions. Collectively, our findings reconcile conflicting theories in the field and point to activity-dependent transcriptional remodeling as a foundational mechanism by which transient E:I imbalance during development can cause lasting, autism-relevant circuit dysfunction.

neuroscience↗

bioRxiv2025

Biological subtyping of autism via cross-species fMRI

It is frequently assumed that the phenotypic heterogeneity in autism spectrum disorder reflects underlying pathobiological variation. However, direct evidence in support of this hypothesis is lacking. Here, we leverage cross-species functional neuroimaging to examine whether variability in brain functional connectivity reflects distinct biological mechanisms. We find that fMRI connectivity alterations in 20 distinct mouse models of autism (n=549 individual mice) can be clustered into two prominent hypo- and hyperconnectivity subtypes. We show that these connectivity profiles are linked to distinct signaling pathways, with hypoconnectivity being associated with synaptic dysfunction, and hyperconnectivity reflecting transcriptional and immune-related alterations. Extending these findings to humans, we identify analogous hypo- and hyperconnectivity subtypes in a large, multicenter resting state fMRI dataset of n=940 autistic and n=1036 neurotypical individuals. Remarkably, hypo- and hyperconnectivity autism subtypes are replicable across independent cohorts (accounting for 25.1% of all autism data), exhibit distinct functional network architecture, are behaviorally dissociable, and recapitulate synaptic and immune mechanisms identified in corresponding mouse subtypes. Our cross-species investigation, thus, decodes the heterogeneity of fMRI connectivity in autism into distinct pathway-specific etiologies, offering a new empirical framework for targeted subtyping of autism.

neuroscience↗

bioRxiv2025

Automated assessment of the mouse body-language reveals pervasive behavioral disruption in a two-hit model of psychiatric vulnerability

The influence of early-life experiences is widely acknowledged as a crafting tool that sculpts complex behavioral patterns and well-being of living organisms. The use of preclinical models can provide invaluable insight into how a negative environmental push interplays with genetic make-up in shaping psychiatric vulnerability. However, the assessment of psychiatric traits in cross-species studies often relies on the use of surrogate metrics as a proxy for the internal state, limiting the interpretation to context-dependent outcomes. In this work, we exploited a validated computational tool for digitalized ethological screening to identify spontaneous hallmarks of altered behavioral functioning in a dual-hit mouse model of psychiatric vulnerability. To do so, mice carrying heterozygous deletion of the gene coding for Contactin-associated protein-like 2 (Cntnap2+/-) and their wild-type (WT) littermates were raised with limited bedding and nesting (LBN). These animals were compared to both WT and Cntnap2+/- mice raised in standard conditions, mapping their spontaneous behavior during freely-moving exploration. Our data show that descriptors of motility state or surrogate anxiety indicators largely failed in detecting subtle diversion from control conditions. By contrast, automated segmentation of the body-language revealed a significant impact of both genotype and early-life experience in shaping the spontaneous behavioral programming. Thus, using unsupervised clustering, we unveiled two alternative neurobehavioral profiles within our dataset. We found that one of the identified profiles largely overlapped with Cntnap2+/- mice raised with LBN, while the other was equally shared among controls. We conclude that the coincidence of early-life adversity and Cntnap2 haploinsufficiency drastically reshapes behavioral structure in rodents. SIGNIFICANCE STATEMENTEnhancing the predictive and face validity of preclinical models in psychiatric research remains a significant challenge due to the inherent heterogeneity and complexity of these conditions. While animal models are crucial for understanding the risk factors involved, replicating the full complexity of these conditions continues to pose difficulties. In this study, we use a tool for digitalized behavioral screening to investigate emotional hallmarks in a double-hit (environmental and genetic) mouse model of vulnerability for psychiatric disorder, glimpsing subliminal behavioral disturbances not captured with traditional assessments. Our findings highlight the effectiveness of novel computational tools in identifying subtle behavioral deviations and support the hypothesis that gene-environment interaction contributes to shape alternative behavioral structure in mice.

neuroscience↗

bioRxiv2024

Early-life scarcity adversity biases behavioral development toward a bipolar-like phenotype in mice heterozygous for CNTNAP2

The etiological complexity of psychiatric disorders arises from the dynamic interplay between genetic and environmental vulnerabilities. Among the environmental components, early-life adversities (ELA) are a major risk-factors for developing a psychiatric disorder. Yet, the mechanistic interaction between ELA and genetic vulnerability contributing to psychopathology is poorly understood. To fill this gap, we took advantage of the ideally controlled conditions of a pre-clinical approach. In this study we raised a mouse model with genetic predisposition to multiple psychiatric disorders (autism spectrum, schizophrenia, bipolar disorder), the Cntnap2+/- mouse, with limited bedding and nesting (LBN), a well-established paradigm to induce early-life stress in rodents. These mice were compared to LBN-raised Cntnap2+/+ littermates, as well as parallel groups of Cntnap2+/+ and Cntnap2+/- raised in standard conditions. Using a battery for behavioral phenotyping we show that ELA shapes non-overlapping phenotypic landscapes based on genetic predisposition. Specifically, we found that LBN-raised Cntnap2+/- mice develop a perseverative risk-taking behavior in the elevated plus maze and that this behavior is highly predictive of their success in the social interaction, assessed with the 3-chamber test. This finding suggests that the intrusion of anxiety into the social behavioral domain contributes to extreme gain- or loss-of function in social interaction, resembling a bipolar-like phenotype. Finally, we show that LBN promotes synaptic hypertrophy in the basolateral nucleus of the amygdala, but only in Cntnap2+/- raised in LBN this condition was found in combination with microglia abnormalities. We conclude that the interplay between ELA and Cntnap2 haploinsufficiency exacerbates bipolar-like behaviors in mice, and that this may be consequence of deficient synaptic homeostasis in the basolateral amygdala.

neuroscience↗

bioRxiv2024

N-acetylcysteine counteracts immune dysfunction and autistic-related behaviors in the Shank3b mouse model of Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) includes a range of neurodevelopmental disabilities characterized by social interaction deficits, communication impairments, and repetitive behaviors. Previous studies have shown that pro-inflammatory conditions play a key role in ASD. Here we reported that increased levels of molecules related to inflammation are present in the cerebellum and peripheral blood (PB) of mice lacking Shank3b, established model of syndromic ASD. In parallel, immune dysfunction was documented in the bone marrow (BM) and spleen of mutant mice. N-acetylcysteine (NAC) treatment rescued inflammation in the cerebellum and PB, as well as impaired production of pro-inflammatory molecules in the BM and spleen. In addition, social impairment was counteracted in NAC-treated Shank3b-/- animals. Taken together, our study further confirms the key role of cerebellar inflammation in the establishment of ASD-related behaviors. Furthermore, our findings underscore the importance of considering ASD as a systemic disorder. Our findings therefore suggest that the interplay between oxidative stress and inflammation may support ASD-related behaviors in mice.

immunology↗

bioRxiv2023

The interplay between oxidative stress and inflammation supports autistic-related behaviors in mice

Autism Spectrum Disorder (ASD) is a highly prevalent neurodevelopmental condition characterized by social communication deficits and repetitive/restricted behaviors. Several studies showed that inflammation may contribute to ASD. Here we used RT-qPCR, RNA sequencing, immunohistochemistry, and flow cytometry to show that pro-inflammatory molecules were increased in the cerebellum and periphery of mice lacking Cntnap2 (Cntnap2-/-), a robust model of ASD. In parallel, oxidative stress was present in the cerebellum of mutant animals. Systemic treatment with N-acetyl-cysteine (NAC) rescued cerebellar oxidative stress and inflammation as well as motor and social impairments in Cntnap2-/- mice. This was accompanied by improved function of microglia cells in NAC-treated mutant animals. Intriguingly, social deficits, cerebellar inflammation and microglia dysfunction were induced by NAC in Cntnap2+/+animals. Our findings therefore suggest that the interplay between oxidative stress and inflammation may support ASD-related behaviors in mice.

immunology↗

bioRxiv2022

Automated decoding the mouse body-postures in a whisker nuisance test

Abnormal response to sensory stimuli characterizes multiple neuropsychiatric conditions. However, not many tools are currently available to assess somatosensory abnormalities in rodent models of brain disorders, limiting the possibilities to study cellular and molecular correlates of this phenotypic trait. To this goal, previous studies relied on the whisker nuisance test (WNt), in which freely moving mice are constantly stimulated on their whiskers using a wood stick for a set time. The whisker-guided response is then deconstructed in behavioral categories indicative of either anxiety or curiosity. Thus far, WNt was shown to be a valuable tool to investigate sensory-driven abnormalities in mouse models of autism spectrum disorders (ASD), demonstrating a solid translational validity. Nevertheless, assessment of behavioral response in the WNt is currently limited by the lack of an objective quantification method. To overcome this limitation, we developed WNt3R (Whisker Nuisance Test in 3D for Rodents), a MATLAB toolbox that uses the output of the open-source software DeepLabCut to determine discrete body postures associated with multiple ethologically-relevant behaviors. Our results show that behavioral modules identified using WNt3R reliably decode mouse body postures, outperforming the manual user, thus offering a novel and unbiased approach to study altered somatosensory function in rodents.

animal behavior and cognition↗

bioRxiv2022

Sex-biasing influence of autism-associated Ube3a gene overdosage at connectomic, behavioral and transcriptomic levels

Many neurodevelopmental conditions, including autism, affect males more than females. Genomic mechanisms enhancing risk in males may contribute to this sex-bias. The ubiquitin protein ligase E3A gene (Ube3a) exerts pleiotropic effects on cellular homeostasis via control of protein turnover and by acting as transcriptional coactivator with steroid hormone receptors. Overdosage of Ube3a via duplication or triplication of chromosomal region 15q11-13 causes 1-2% of autistic cases. Here, we test the hypothesis that increased dosage of Ube3a may influence autism-relevant phenotypes in a sex-biased manner. We report robust sex-biasing effects on brain connectomics and repetitive behaviors in mice with extra copies of Ube3a. These effects were associated with a profound transcriptional dysregulation of several known autism-associated genes (e.g., FMR1, SCN2A, PTEN, MEF2C, SHANK3, TSC2) as well as differentially-expressed genes identified in human 15q duplication and in autistic patients. Notably, increased Ube3a dosage also affects multiple sex-relevant mechanisms, including genes on the X chromosome, genes influenced by sex steroid hormones, downstream targets of the androgen and estrogen receptors, or genes that are sex-differentially regulated by transcription factors. These results suggest that Ube3a overdosage can critically contribute to sex-bias in neurodevelopmental conditions via influence on sex-differential mechanisms.

neuroscience↗

bioRxiv2022

Gene expression profiling in trigeminal ganglia from Cntnap2-/- and Shank3b-/- mouse models of autism spectrum disorder

Sensory difficulties represent a crucial issue in the life of autistic individuals. The diagnostic and statistical manual of mental disorders describes both hyper- and hypo-responsiveness to sensory stimulation as a criterion for the diagnosis autism spectrum disorders (ASD). Among the sensory domain affected in ASD, altered responses to tactile stimulation represent the most commonly reported sensory deficits. Although tactile abnormalities have been reported in monogenic cohorts of patients and genetic mouse models of ASD, the underlying mechanisms are still unknown. Traditionally, autism research has focused on the central nervous system as the target to infer the neurobiological bases of such tactile abnormalities. Nonetheless, the peripheral nervous system represents the initial site of processing of sensory information and a potential site of dysfunction in the sensory cascade. Here we investigated the gene expression deregulation in the trigeminal ganglion (which directly receives tactile information from whiskers) in two genetic models of syndromic autism (Shank3b and Cntnap2 mutant mice) at both adult and juvenile ages. We found several neuronal and non-neuronal markers involved in inhibitory, excitatory, neuroinflammatory and sensory neurotransmission to be differentially regulated within the trigeminal ganglia of both adult and juvenile Shank3b and Cntnap2 mutant mice. These results may help in entangling the multifaced complexity of sensory abnormalities in autism and open avenues for the development of peripherally targeted treatments for tactile sensory deficits exhibited in ASD.

neuroscience↗

bioRxiv2021

Proteoglycan Clusters as a Site of Coordinated, Multi-Dendritic Plasticity

Experience-dependent learning depends on synaptic plasticity. While plasticity in individual synapses has been extensively investigated, the mechanisms underlying coordinated changes across sets of synapses on multiple dendrites, likely needed to encode effective adaptations to a salient stimulus, are not well understood. The extracellular matrix is uniquely well suited to fulfill this function, as rapid glia-driven remodeling of its local composition powerfully impact synaptic plasticity. We show that extracellular matrix microenvironments, named CS6 clusters, dynamically form around several dendrites in response to sensory stimuli in coincidence to stimulus-driven synaptic plasticity. CS6 clusters, formed by glia-dependent secretion of extracellular matrix components surrounding sets of adjacent dendrites, may represent a novel structure supporting coordinated synaptic plasticity. One Sentence SummaryExtracellular matrix clusters form microenvironments for coordinated multi-dendrite synaptic plasticity.

neuroscience↗

bioRxiv2021

Somatosensory processing deficits and altered cortico-hippocampal connectivity in Shank3b-/- mice

Abnormal tactile response is considered an integral feature of Autism Spectrum Disorders (ASDs), and hypo-responsiveness to tactile stimuli is often associated with the severity of ASDs core symptoms. Patients with Phelan-McDermid syndrome (PMS), caused by mutations in the SHANK3 gene, show ASD-like symptoms associated with aberrant tactile responses. However, the neural underpinnings of these somatosensory abnormalities are still poorly understood. Here we investigated, in Shank3b-/- adult mice, the neural substrates of whisker-guided behaviors, a key component of rodents interaction with the surrounding environment. To this aim, we assessed whisker-dependent behaviors in Shank3b-/- adult mice and age-matched controls, using the textured novel object recognition (tNORT) and whisker nuisance (WN) test. Shank3b-/- mice showed deficits in whisker-dependent texture discrimination in tNORT and behavioral hypo-responsiveness to repetitive whisker stimulation in WN. Notably, sensory hypo-responsiveness was accompanied by a significantly reduced activation of the primary somatosensory cortex (S1) and hippocampus, as measured by c-fos mRNA in situ hybridization, a proxy of neuronal activity following whisker stimulation. Moreover, resting-state fMRI showed a significantly reduced S1-hippocampal connectivity in Shank3b mutant mice. Together, these findings suggest that impaired crosstalk between hippocampus and S1 might underlie Shank3b-/- hypo-reactivity to whisker-dependent cues, highlighting a potentially generalizable form of dysfunctional somatosensory processing in ASD. Significance StatementPatients with Phelan-McDermid syndrome, a syndromic form of ASD caused by mutation of the SHANK3 gene, often show aberrant responses to touch. However, the neural basis of atypical sensory responses in ASD remains undetermined. Here we used Shank3 deficient mice to investigate the neural substrates of behavioral responses to repetitive stimulation of the whiskers, a highly developed sensory organ in mice. We found that mice lacking the Shank3 gene are hypo-responsive to repetitive whisker stimulation. This trait was associated with reduced engagement and connectivity between the primary somatosensory cortex and hippocampus. These results suggest that dysfunctional cortico-hippocampal coupling may underlie somatosensory processing deficits in SHANK3 mutation carriers and related syndromic forms of ASD.

neuroscience↗

bioRxiv2020

Brain mapping across 16 autism mouse models reveals a spectrum of functional connectivity subtypes

Autism Spectrum Disorder (ASD) is characterized by substantial, yet highly heterogeneous abnormalities in functional brain connectivity. However, the origin and significance of this phenomenon remain unclear. To unravel ASD connectopathy and relate it to underlying etiological heterogeneity, we carried out a bi-center cross-etiological investigation of fMRI-based connectivity in the mouse, in which specific ASD-relevant mutations can be isolated and modelled minimizing environmental contributions. By performing brain-wide connectivity mapping across 16 mouse mutants, we show that different ASD-associated etiologies cause a broad spectrum of connectional abnormalities in which diverse, often diverging, connectivity signatures are recognizable. Despite this heterogeneity, the identified connectivity alterations could be classified into four subtypes characterized by discrete signatures of network dysfunction. Our findings show that etiological variability is a key determinant of connectivity heterogeneity in ASD, hence reconciling conflicting findings in clinical populations. The identification of etiologically-relevant connectivity subtypes could improve diagnostic label accuracy in the non-syndromic ASD population and paves the way for personalized treatment approaches.

neuroscience↗