Biology subjects

Mattei, D.

Publications and source records attributed to Mattei, D..

6 recordsLinked to original sources

bioRxiv2024

A microglia-containing cerebral organoid model to study early life immune challenges

Prenatal infections and activation of the maternal immune system have been proposed to contribute to causing neurodevelopmental disorders (NDDs), chronic conditions often linked to brain abnormalities. Microglia are the resident immune cells of the brain and play a key role in neurodevelopment. Disruption of microglial functions can lead to brain abnormalities and increase the risk of developing NDDs. How the maternal as well as the fetal immune system affect human neurodevelopment and contribute to NDDs remains unclear. An important reason for this knowledge gap is the fact that the impact of exposure to prenatal risk factors has been challenging to study in the human context. Here, we characterized a model of cerebral organoids (CO) with integrated microglia (COiMg). These organoids express typical microglial markers and respond to inflammatory stimuli. The presence of microglia influences cerebral organoid development, including cell density and neural differentiation, and regulates the expression of several ciliated mesenchymal cell markers. Moreover, COiMg and organoids without microglia show similar but also distinct responses to inflammatory stimuli. Additionally, IFN-{gamma} induced significant transcriptional and structural changes in the cerebral organoids, that appear to be regulated by the presence of microglia. Specifically, interferon-gamma (IFN-{gamma}) was found to alter the expression of genes linked to autism. This model provides a valuable tool to study how inflammatory perturbations and microglial presence affect neurodevelopmental processes.

neuroscience↗

bioRxiv2023

Microglia undergo transcriptional, translational and functional adaptations to dark and light phases in laboratory mice

Microglia cells are increasingly recognized to contribute to brain health and disease. Preclinical studies using laboratory rodents are essential to advance our understanding of the physiological and pathophysiological functions of these cells in the central nervous system. Rodents are nocturnal animals, and they are mostly maintained in a defined light-dark cycle within animal facilities, with many laboratories investigating microglial molecular and functional profiles during the animals light (sleep) phase. However, only a few studies have considered possible differences in microglial functions between the active and sleep phases. Based on initial evidence suggesting that microglial intrinsic clock genes can affect their phenotype, we sought to investigate differences in transcriptional, proteotype and functional profiles of microglia between light (sleep) and dark (active) phases, and how these changes are affected in pathological models. We found marked transcriptional and proteotype differences between microglia harvested during the light or dark phase. Amongst others, these differences related to genes and proteins associated with immune responses, motility, and phagocytosis, which were reflected by functional alterations in microglial synaptic pruning and response to bacterial stimuli. Possibly accounting for such circadian changes, we found RNA and protein regulation in SWI/SNF and NuRD chromatin remodeling complexes between light and dark phases. Importantly, we show that microglial circadian transcriptional changes are impaired in a model of immune-mediated neurodevelopmental disorders. Our findings emphasize the importance of considering circadian factors in studying microglial cells and indicate that implementing a circadian perspective is pivotal for advancing our understanding of their physiological and pathophysiological roles in brain health and disease. This may also open novel avenues towards therapeutic strategies for modulating microglial functions during specific windows of the active or sleep phase.

neuroscience↗

bioRxiv2022

Analyses of circRNA expression throughout circadian rhythm reveal a strong link between Cdr1as and light-induced phase shifts in the SCN

Cdr1as is a conserved circular RNA (circRNA) enriched in the CNS and important for maintaining brain homeostasis. The loss of Cdr1as results in aberrant synaptic transmission and deregulation of stress response and circadian clock genes. However, it is not known whether the expression of Cdr1as or circRNAs, in general, follows a circadian pattern in different tissues. Here, using newly generated and public RNA-Seq data, we monitor circRNA expression throughout circadian rhythm in various mouse brain regions. We demonstrate that Cdr1as, despite its stable character, has a highly dynamic expression during the circadian cycle in the mouse suprachiasmatic nucleus (SCN). Cdr1as is one of the highest expressed RNAs in a cluster associated with light-induced synaptic transmission and phase shift in the SCN. Further, we identified that another brain enriched circRNA, mbl, is also substantially deregulated upon light induction in the fly head. Our study highlights the potential impact of abundant and conserved circRNAs on maintaining a healthy circadian cycle across species.

systems biology↗

bioRxiv2022

Deletion of the microglial transmembrane immune signaling adaptor TYROBP ameliorates Huntington's disease mouse phenotype

BACKGROUNDHuntingtons disease (HD) is a fatal neurodegenerative disorder caused by an expansion of the CAG trinucleotide repeat in the huntingtin gene. Immune activation is abundant in the striatum of HD patients. Detection of active microglia at presymptomatic stages suggests that microgliosis is a key early driver of neuronal dysfunction and degeneration. Recent studies showed that deletion of Tyrobp, a microglial-enriched protein, ameliorates neuronal function in Alzheimers disease amyloid and tauopathy mouse models while decreasing components of the complement subnetwork, thus raising the possibility that Tyrobp deletion can be beneficial for HD. METHODSTo test the hypothesis that Tyrobp deficiency would be beneficial in a HD model, we placed the Q175 HD mouse model on a Tyrobp-null background. We characterized these mice with a combination of behavioral testing, immunohistochemistry, transcriptomic and proteomic profiling. Further, we evaluated the Q175 microglia-specific gene signature, with and without Tyrobp, by purifying microglia from these mice for transcriptomics. RESULTSComprehensive analysis of publicly available transcriptomic HD human data revealed that TYROBP network is overactivated in HD putamen. The Q175 mice showed morphologic microglial activation, reduced levels of post-synaptic density-95 protein and motor deficits at 6 and 9 months of age, all of which were ameliorated on the Tyrobp-null background. Gene expression analysis revealed that lack of Tyrobp in the Q175 model does not prevent the decrease in the expression of striatal neuronal genes but reduces pro-inflammatory pathways that are specifically active in HD human brain. Integration of transcriptomic and proteomic data identified that astrogliosis and complement system pathway were reduced after Tyrobp deletion. Results were further validated by immunofluorescence analysis. Microglia-specific HD gene dysregulation, characterized by overexpression of neuronal genes, was also not corrected by Tyrobp deletion. CONCLUSIONSOur data provide molecular and functional support demonstrating that Tyrobp deletion prevents many of the abnormalities in the Q175 HD mouse model, in the absence of correction of striatal neuronal gene expression, suggesting that the Tyrobp pathway is a potential therapeutic candidate for Huntingtons disease.

neuroscience↗

bioRxiv2020

Enzymatic dissociation induces transcriptional and proteotype bias in brain cell populations

Different cell isolation techniques exist for transcriptomic and proteotype profiling of brain cells. Here, we provide a systematic investigation of the influence of different cell isolation protocols on transcriptional and proteotype profiles in mouse brain tissue by taking into account single-cell transcriptomics of brain cells, proteotypes of microglia and astrocytes, and flow cytometric analysis of microglia. We show that standard enzymatic digestion of brain tissue at 37{degrees}C induces profound and consistent alterations in the transcriptome and proteotype of neuronal and glial cells, as compared to an optimized mechanical dissociation protocol at 4{degrees}C. These findings emphasize the risk of introducing technical biases and biological artefacts when implementing enzymatic digestion-based isolation methods for brain cell analyses.

neuroscience↗

bioRxiv2020

A CRISPR-Cas9-engineered mouse model for GPI anchor deficiency mirrors human phenotype and shows hippocampal synaptic dysfunctions.

Pathogenic germline mutations in PIGV lead to glycosylphosphatidylinositol biosynthesis deficiency (GPIBD). Individuals with pathogenic biallelic mutations in genes of the glycosylphosphatidylinositol (GPI) anchor pathway exhibit cognitive impairments, motor delay, and often epilepsy. Thus far, the pathophysiology underlying the disease remains unclear, and suitable rodent models that mirror all symptoms observed in human patients have not been available. Therefore, we used CRISPR-Cas9 to introduce the most prevalent hypomorphic missense mutation in European patients, Pigv:c.1022C>A (p.A341E), at a site that is conserved in mice. Mirroring the human pathology, mutant Pigv341E mice exhibited deficits in motor coordination, cognitive impairments, and alterations in sociability and sleep patterns, as well as increased seizure susceptibility. Furthermore, immunohistochemistry revealed reduced synaptophysin immunoreactivity in Pigv341E mice, and electrophysiology recordings showed decreased hippocampal synaptic transmission that could underlie impaired memory formation. In single-cell RNA sequencing, Pigv341E-hippocampal cells exhibited changes in gene expression, most prominently in a subtype of microglia and subicular neurons. A significant reduction in Abl1 transcript levels in several cell clusters suggested a link to the signaling pathway of GPI-anchored ephrins. We also observed elevated levels of Hdc transcripts, which might affect histamine metabolism with consequences for circadian rhythm. This new mouse model will not only open the doors to further investigation into the pathophysiology of GPIBD, but will also deepen our understanding of the role of GPI-anchor-related pathways in brain development. Significance statementInherited GPI-anchor biosynthesis deficiencies (IGDs) explain many cases of syndromic intellectual disability. Although diagnostic methods are improving, the pathophysiology underlying the disease remains unclear. Furthermore, we lack rodent models suitable for characterizing cognitive and social disabilities. To address this issue, we generated the first viable mouse model for an IGD that mirrors the condition in human patients with a behavioral phenotype and susceptibility to epilepsy. Using the new model, we obtained neurological insights such as deficits in synaptic transmission that will facilitate understanding of the pathophysiology of IGDs.

neuroscience↗