TL;DR
In vivo results demonstrated that NT supplementation attenuated repetitive behaviors and improved social interactions in the BTBR cohort, revealing pronounced sex-dimorphic responsiveness.
Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with a multifactorial etiology involving both genetic and environmental factors. Although previous studies have identified altered levels of circulating proteins in individuals with ASD, the functional significance of these peripheral biomarkers remains largely unclear. In this study, we recruited a well-characterized cohort of young Arab children with ASD (n = 100) and matched controls (n = 60), aged 2-4 years, in Qatar. We used a multimodal approach, integrating data from proteomics, transcriptomics, induced pluripotent stem cell (iPSC)-derived cortical neurons, cellular imaging, functional assays using microelectrode recordings, and behavioral assays in Drosophila models. High-throughput screening of plasma samples revealed considerable heterogeneity in circulating proteomic profiles across different Arab subpopulations; therefore, we focused our subsequent analyses on Qatari children. We identified elevated levels of several neuronal proteins in the peripheral circulation of individuals with severe, but not mild, ASD symptoms. Furthermore, we found that neurons derived from the severe ASD group showed increased MAP2+/DCX+ cell counts, upregulated expression of genes associated with neuronal activity, and increased neuronal hyperexcitability in functional assays. Moreover, targeted overexpression of these proteins specifically in the blood of Drosophila models was sufficient to induce ASD-relevant behaviors. Together, our findings reveal key links between peripheral protein dysregulation and neuronal function and behavior, offering new insights into systemic contributions to ASD pathophysiology and highlighting potential therapeutic targets for mitigating symptom severity.
Myelination is a fundamental neurobiological process that enables rapid and efficient neural signal transmission, playing a key role in shaping brain connectivity and function-particularly during early development. Given the high energetic cost and tight developmental timing of myelination, disruptions in myelin formation or maintenance can increase vulnerability to genetic and environmental factors during critical periods. As such, impaired myelination and oligodendrocyte dysfunction may contribute to the pathogenesis of various neurodevelopmental disorders (NDDs). This review synthesizes current knowledge on the role of myelin-related changes in the pathophysiology of NDDs-including Autism Spectrum Disorder (ASD), Attention-Deficit/ Hyperactivity Disorder (ADHD), Fetal Alcohol Spectrum Disorders (FASD), intellectual developmental disorders, and communication, motor, and specific learning disorders-integrating findings from both animal models and human research. Taken together, the evidence suggests that myelin-related pathways represent a common point of vulnerability across disorders and may offer a potential target for intervention.
Background/Objectives: Transcription factor 4 (TCF4) is a proneural basic helix–loop–helix transcription factor that plays a critical role in brain development and is associated with a variety of psychiatric disorders, including autism spectrum disorder (ASD), major depressive disorder, and schizophrenia. Autosomal dominant mutations in TCF4 result in a profound neurodevelopmental disorder called Pitt–Hopkins Syndrome (PTHS). Germline TCF4 loss-of-function (LOF) studies using human and mouse models have identified dysregulation in neural cell proliferation, genesis, and specification, which leads to disruption in neuronal, astroglial, and oligodendroglial lineages. In this study, we focused on the role of TCF4 in the genesis of the astrocyte lineage, specifically in the context of modeling PTHS. Methods: We investigated the expression of astrocyte marker genes in primary astrocyte cultures and whole-brain lysates, as well as assessed pan- and subclass-specific astrocyte markers, using immunohistochemical (IHC) analysis in a heterozygous mouse model of PTHS. Lastly, we tracked ventrally derived astrocytes using an Nkx2.1 reporter mouse to investigate misallocation of ventrally derived astrocytes into the dorsal cortex, a phenotype previously observed when both Tcf4 alleles were conditionally deleted in the Nkx2.1 lineage. Results: We show that germline heterozygous mutations in Tcf4 had no effect on the expression of astrocyte markers via qPCR or astrocyte cell density with IHC analysis. Germline heterozygous Tcf4 LOF also did not result in misallocation of ventrally derived astrocytes into the dorsal cortex. Conclusions: These data indicate that germline heterozygous TCF4 LOF, which models PTHS, does not appear to significantly affect the astrocyte lineage at the cell population level.
Chronic unresolved inflammation is a common feature of several Central Nervous System (CNS) disorders, including autism spectrum disorder (ASD). We previously demonstrated that Formyl Peptide Receptor 2 (FPR2) activation by our agonist MR-39 reduced several inflammatory markers and improved social behavior in two validated animal models of ASD. Therefore, we decided to delve deeper into the potential of MR-39 as a drug for treating ASD. We first investigated the molecular mechanisms underlying the beneficial effects of MR-39 in BTBR mice. MR-39 significantly normalized pro-inflammatory cytokine release and NF-κB expression in the hippocampus and cortex, resulting in upregulation of synaptophysin protein levels, which, in turn, promote plasticity and correct abnormalities in dendritic spine morphology. Next, we characterized the safety and pharmacokinetic profile of MR-39 with respect to potential advancement for further pre- and clinical studies. We found that MR-39 was not genotoxic and safe to use since it had limited interaction with the majority of the targets associated with the adverse drug reaction. Consistently, a repeated-dose administration study evidenced no clinical signs attributable to treatment-related toxicity. On the other hand, MR-39 exhibited rapid hepatocyte clearance and interaction with efflux systems in vitro, suggesting possible limitations due to its pharmacokinetic properties. Finally, we explored multiple strategies to overcome MR-39's low aqueous solubility, finding that the cosolvent approach can greatly enhance solubility and wettability. Overall, our study confirmed that promoting inflammation resolution with MR-39 can open new therapeutic options for ASD and that this compound has potential as a drug.
Abstract. Autism spectrum disorder (ASD) is one of the most common neurological disorders, with a ubiquitous in-crease in prevalence. A theoretical rationale is providing for identifying potentially clinically significant diagnostic bi-omarkers and opportunities for targeted pharmacological modulation based on current data on gene signaling path-ways. This systematic review is based on data from systematic reviews and meta-analyses devoted to the basic aspects of autism spectrum disorder. This has made it possible to outline approaches to syndrome-associated diagnosis and treatment strategies. This article explores integrative pathogenetic mechanisms of ASD, encompassing prenatal viral exposure, alterations in serotonin and oxytocin signaling pathways, regulation of N-methyl-D-aspartate receptors, SHANK proteins, and members of the Solute Carrier protein family. Immune, viral, and metabolic factors, neurotrans-mitter systems, synaptic proteins and structural regulation, biomarkers, and therapeutic strategies were detected as di-agnostic and modulation promising in ASD. The potential of combined modulation involving retinoic acid derivatives, folates, antioxidants, neurotrophins, oxytocin preparations, glycine, and magnesium has been demonstrated, depending on the syndromic manifestation of ASD. A possible role of the rubella virus in prenatal disruption of retinoic acid me-tabolism and subsequent impairment of neuronal pathway formation has been demonstrated, as well as the specific in-fluence of the COVID-19 virus on the IGF-1 signaling pathway. An association has been proposed between autoimmune activation during impaired neuronal maturation and ferroptosis processes, resulting in decreased ferritin and transfer-rin levels in children with ASD. Analysis of the literature explores the potential for more selective diagnosis and modu-lation in ASD using specific biomarkers and to indicate directions for future research.
Human cellular models are enabling the in vitro study of the complex molecular and cellular mechanisms underlying autism spectrum disorder (ASD). Human embryonic stem cell (hESC) and induced pluripotent stem cell (hiPSC)- derived models have progressed from investigating single genes to multiplexed approaches that have allowed the study of several ASD risk genes in parallel, which have expanded our understanding of how coding and noncoding genetic variants shape cellular and molecular phenotypes in ASD. Additionally, these models have identified several convergent pathogenic mechanisms in ASD, including dysregulated neurogenesis, altered cell type specification (such as defects in glutamatergic neurons and expansion of GABAergic neurons), and disrupted synaptic activity. Common molecular principles are also emerging, including dysregulation of chromatin, WNT signaling, and mTOR signaling. hiPSC models of ASD have also been used to evaluate the effect of several FDA-approved therapeutic compounds on early human neural development, such as mTOR inhibitors, some of which are currently in clinical trials for ASD-related conditions. Although human cellular models have limitations, their unique strength is the ability to reveal early developmental pathophysiology and the potential to correlate in vitro phenotypes with the clinical features of patient donors. Here, we examine how human cellular models have advanced basic and translational research in ASD and identify key cellular and molecular convergent phenotypes that have emerged.