The role of immune dysfunction in the pathophysiology of autism

Crosstalk Between Mitochondrial DNA and Immune Response: Focus on Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by multiple dysfunctions in behavior, the nervous system, and the immune system. Increasing evidence suggests that mitochondrial DNA (mtDNA) plays a crucial role in the pathology of ASD. In clinical practice, altered mtDNA levels have been observed in various tissues of individuals with ASD. Mutation or oxidation of mtDNA is also closely related to the immune response associated with the pathology of autism. With mtDNA identified as a causal factor, much interest has focused on how its production affects neurodevelopment and neurophysiology. Here, we review how mtDNA leads to dysfunction of cellular mitochondria and immune response. We also illustrate the relationship between mtDNA alterations and the pathology of autism. Finally, we discuss the existing evidence on cell-free mtDNA associated with ASD and look forward to its application in clinical diagnosis and treatment.

Emerging autism and Fragile X syndrome treatments

The limitations of current symptom-focused treatments drive the urgent need for effective therapies for autism and Fragile X syndrome (FXS). Currently, no approved pharmacological interventions target the core symptoms of these disorders. Advances in understanding the underlying biology of autism and FXS make this an important time to explore novel options. Indeed, several treatments have recently been tested in clinical trials, with promising results in treating core symptoms of autism and FXS. We focus on emerging interventions, such as gut microbiome therapies, anti-inflammatory approaches, bumetanide, phosphodiesterase 4D inhibitors, and endocannabinoid modulators. We also discuss factors, such as disorder heterogeneity, which may have contributed to poor efficacy in previously failed late-phase trials and impact recent trials, emphasizing the need for personalized treatment approaches.

Metal Dyshomeostasis as a Driver of Gut Pathology in Autism Spectrum Disorders

Despite being classified as neurodevelopmental disorders, in recent years, there has been a growing interest in the association between autism spectrum disorders (ASDs) and gut pathology. This comprehensive and systematic review explores a potential mechanism underlying gut pathology in ASDs, including alterations in gut microbiota, intestinal permeability, immune dysregulation, and gastrointestinal (GI) symptoms. Specifically, it delves into the role of toxic and essential metals and their interplay, affecting the development and function of the GI tract. The review also discusses the potential implications of this gut pathology in the development and management of ASDs. Studies have shown that heavy metal exposure, whether through environmental sources or dietary intake, can disrupt the delicate balance of trace elements in the gut. This disruption can adversely affect zinc homeostasis, potentially exacerbating gut pathology in individuals with ASDs. The impaired zinc absorption resulting from heavy metal exposure may contribute to the immune dysregulation, oxidative stress, and inflammation observed in the gut of individuals with ASDs. By shedding light on the multifaceted nature of gut pathology, including the impact of metal dyshomeostasis as a non-genetic factor in ASD, this review underscores the significance of the gut-brain axis in the etiology and management of ASDs.

Profiling of activated monocyte populations in autism and associations with increased severity and comorbid behaviors

Immune dysfunction in autism spectrum disorder (ASD) has been widely reported and is associated with increased impairments in social interactions, communication, repetitive behaviors, anxiety and gastrointestinal problems. Several lines of evidence point towards increased activation of the innate immune system including activation of microglia, increases in innate inflammatory cytokines/chemokines in blood, brain tissue and CSF, activated dendritic cells and macrophages, and abnormal peripheral monocyte cell function. Monocytes are major players in innate immunity and have important functions in the phagocytosis of pathogens or debris, immune defense and cytokine/chemokine production. However, little is known about the frequencies of different circulating monocytes populations in ASD compared with similarly aged typically developing (TD) controls. In this study, the profile of circulating monocytes exhibiting different markers of activation were assessed in 77 children with ASD, and 49 TD controls who were enrolled as part of the Autism Phenome Project and were of a similar age, 2-4 years old. The frequencies of monocytes expressing the activation marker CD137 (4-1BB) were significantly increased in children with ASD and associated with greater behavioral impairments. In addition, although the frequencies of non-classical monocytes (CD14+CD16+) were not significantly different across groups, they were linked to worse behaviors in both the context of ASD and TD. Conversely classical monocytes were associated with better behavioral outcomes. These data further implicate monocytes and innate immune cells in the complex pathophysiology of ASD. Monocyte cells play key roles in modulating immune responses and differences in the activation profiles of these cells may result in immune dysfunction in children with ASD.

Ontogenetic Neuroimmune Changes Following Prenatal Alcohol Exposure: Implications for Neurobehavioral Function

This chapter reviews the enduring effects of prenatal alcohol exposure (PAE) on neuroimmune function across the lifespan, including discussion of associated neurobehavioral alterations. Alcohol has potent teratogenic effects, with a large body of work linking PAE to perturbations in neuroimmune function. These PAE-related neuroimmune disturbances may have downstream effects on neurobehavioral function given the critical role of the neuroimmune system in central nervous system development. The neuroimmune system matures over time, playing distinct roles depending on the developmental processes occurring within that maturational stage. This chapter thus takes an ontogenetic approach to understanding how PAE induces unique neuroimmune changes across the lifespan, beginning with a review of changes in early life before moving into adolescence and ending in adulthood. The focus will be on work utilizing rodent models, which allow for more tightly controlled conditions than are possible in human research. The chapter concludes with a discussion of possible mechanisms underlying the developmental changes in neuroimmune function following PAE, with a specific focus on the role of the gut microbiota.

tVNS alters inflammatory response in adult VPA-induced mouse model of autism: evidence for sexual dimorphism

Autism is a neurodevelopmental disorder with limited treatment alternatives and which incidence is increasing. Some research suggests that vagus nerve simulation might lead to the reduction of certain symptom. Therefore, we aimed to examine the effect of bilateral transcutaneous auricular vagus nerve stimulation (tVNS) on the inflammatory response in an adult valproic acid (VPA) induced mouse (C57BL6) model of autism for the first time. The autism model was induced by oral VPA administration (600 mg·kg-1) to C57BL/6 pregnant mice on E12.5 days. The study included three groups: the VPA Transcutaneous Auricular Stimulation Group (VPA + tVNS), the VPA Control Group (VPA + sham), and the Healthy Control Group (Control + sham). Each group included 16 mice (8 M/8 F). Our results show that serum IL-1β and IL-6 levels were significantly higher in male VPA-exposed mice than controls. However, IL-1β was significantly lower, and IL-6, TNF- α, and IL-22 were not different in female VPA-exposed mice compared to the control group. Brain NLRP3 levels were significantly higher in both sexes in the VPA autism model (P < 0.05). tVNS application increased brain NLRP3 levels in both sexes and reduced serum IL-1β levels in male mice. We conclude that cytokine dysregulation is associated with the VPA-induced adult autism model, and the inflammatory response is more pronounced in male mice. tVNS application altered the inflammatory response and increased brain NLPR3 levels in both sexes. Further studies are needed to understand the beneficial or detrimental role of the inflammatory response in autism and its sexual dimorphism.

Lipopolysaccharide induces neuroinflammation in a valproic acid male model of autism

BACKGROUND

Autism spectrum disorders (ASD) are characterized by social skill deficits and behavior impairments. Exposure to valproic acid (VPA) has been linked to ASD in humans and ASD-like behaviors in rodents. Clinical evidence suggests that immunological damage can worsen ASD symptoms in humans.

OBJECTIVE

This study aimed to investigate the potential of lipopolysaccharide (LPS) to induce neuroinflammation in a VPA-induced autism male model.

MATERIALS

and methods: Pregnant Sprague Dawley rats were injected with 500 mg/kg of VPA on gestational day 12.5 to create an ASD rat model in their offspring. Male offspring from VPA-injected group received 10 mg/kg of LPS on postnatal day 20. Immunohistochemistry, western blotting, and immunofluorescence were used to assess the expression of NF-κB signaling pathway-related proteins and microglia in the prefrontal cortex and hippocampus. Gene Ontology and pathway enrichment analyses were conducted to predict the function of key synaptic proteins, which were further validated through real-time polymerase chain reaction analysis.

RESULTS

The results showed that VPA exposure led to increased locomotor activity, social impairment, and repetitive behaviors in male rats. NF-κB signaling pathway-related proteins were upregulated, and microglial numbers were elevated in the VPA-induced group. Furthermore, synaptic dysfunction was observed in the brains of offspring exposed to VPA. Importantly, LPS administration exacerbated autism-related behaviors in VPA-exposed male rats by promoting NF-κB signaling pathway activation, increasing microglial numbers, and downregulating key synaptic proteins.

CONCLUSIONS

This study not only contributed to understanding the importance of the NF-κB signaling pathway, microglia, and synaptic proteins in the progression of ASD, but also identified that LPS induces neuroinflammation in a valproic acid-induced male model of autism.

Research Progress on the Correlation Between Atmospheric Particulate Matter and Autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder caused by the interaction of genetic and complex environmental factors. The prevalence of autism has dramatically increased in countries and regions undergoing rapid industrialization and urbanization. Recent studies have shown that particulate matter (PM) in air pollution affects the development of neurons and disrupts the function of the nervous system, leading to behavioral and cognitive problems and increasing the risk of ASD. However, research on the mechanism of environmental factors and ASD is still in its infancy. On this basis, we conducted a literature search and analysis to review epidemiological studies on the correlation between fine particulate matter (PM2.5) and inhalable particulate matter (PM10) and ASD. The signaling pathways and pathogenic mechanisms of PM in synaptic injury and neuroinflammation are presented, and the mechanism of the ASD candidate gene SHANK3 was reviewed. Additionally, the different sites of action of different particles in animal models and humans were highlighted, and the differences of their effects on the pathogenesis of ASD were explained. We summarized the aetiology and mechanisms of PM-induced autism and look forward to future research breakthroughs in improved assessment methods, multidisciplinary alliances and high-tech innovations.

Lipopolysaccharide Effects on Neurotransmission: Understanding Implications for Depression

Immune activation in the body is well studied; however, much less is known about how peripheral inflammation changes brain chemistry. Because depression and inflammation are close comorbidities, investigating how inflammation affects the brain's chemicals will help us to better understand depression. The levels of the monoamines dopamine, serotonin and norepinephrine are thought to be affected by both inflammation and depression. In this Perspective, we review studies that find chemical changes in the brain after administration of the endotoxin LPS, which is a robust method to induce rapid inflammation. From these studies, we interpreted LPS to reduce dopamine and serotonin and increase norepinephrine levels in various regions in the brain. These changes are not a sign of "dysfunction" but serve an important evolutionary purpose that encourages the body to recover from an immune insult by altering mood.

Biospecimens in the HEALthy Brain and Child Development (HBCD) Study: Rationale and protocol

The HEALthy Brain and Child Development (HBCD) Study, a multi-site prospective longitudinal cohort study, will examine human brain, cognitive, behavioral, social, and emotional development beginning prenatally and planned through early childhood. The longitudinal collection of biological samples from over 7000 birthing parents and their children within the HBCD study enables research on pre- and postnatal exposures (e.g., substance use, toxicants, nutrition), and biological processes (e.g., genetics, epigenetic signatures, proteins, metabolites) on neurobehavioral developmental outcomes. The following biosamples are collected from the birthing parent: 1) blood (i.e., whole blood, serum, plasma, buffy coat, and dried blood spots) during pregnancy, 2) nail clippings during pregnancy and one month postpartum, 3) urine during pregnancy, and 4) saliva during pregnancy and at in-person postnatal assessments. The following samples are collected from the child at in-person study assessments: 1) saliva, 2) stool, and 3) urine. Additionally, placenta tissue, cord blood, and cord tissue are collected by a subset of HBCD sites. Here, we describe the rationale for the collection of these biospecimens, their current and potential future uses, the collection protocol, and collection success rates during piloting. This information will assist research teams in the planning of future studies utilizing this collection of biological samples.

Investigating brain-gut microbiota dynamics and inflammatory processes in an autistic-like rat model using MRI biomarkers during childhood and adolescence

Autism spectrum disorder (ASD) is characterized by social interaction deficits and repetitive behaviors. Recent research has linked that gut dysbiosis may contribute to ASD-like behaviors. However, the exact developmental time point at which gut microbiota alterations affect brain function and behavior in patients with ASD remains unclear. We hypothesized that ASD-related brain microstructural changes and gut dysbiosis induce metabolic dysregulation and proinflammatory responses, which collectively contribute to the social behavioral deficits observed in early childhood. We used an autistic-like rat model that was generated via prenatal valproic acid exposure. We analyzed brain microstructural changes using diffusion tensor imaging (DTI) and examined microbiota, blood, and fecal samples for inflammation biomarkers. The ASD model rats exhibited significant brain microstructural changes in the anterior cingulate cortex, hippocampus, striatum, and thalamus; reduced microbiota diversity (Prevotellaceae and Peptostreptococcaceae); and altered metabolic signatures. The shift in microbiota diversity and density observed at postnatal day (PND) 35, which is a critical developmental period, underscored the importance of early ASD interventions. We identified a unique metabolic signature in the ASD model, with elevated formate and reduced acetate and butyrate levels, indicating a dysregulation in short-chain fatty acid (SCFA) metabolism. Furthermore, increased astrocytic and microglial activation and elevated proinflammatory cytokines-interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interferon-gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α)-were observed, indicating immune dysregulation. This study provided insights into the complex interplay between the brain and the gut, and indicated DTI metrics as potential imaging-based biomarkers in ASD, thus emphasizing the need for early childhood interventions.

Cord blood cytokine profiles in children later diagnosed with autism spectrum disorder: Results from the prospective MARBLES study

In studies investigating the etiology and pathophysiology of autism spectrum disorder (ASD), immune dysregulation is commonly observed, with elevated levels of inflammatory cytokines frequently found in gestational tissues. However, studies investigating the relationship between early immune dysregulation within the umbilical cord blood (CB) compartment and neurodevelopmental outcomes remains limited. In this exploratory study, we utilized data from the prospective Markers for Autism Risk in Babies - Learning Early Signs (MARBLES) study to examine cytokine levels in the plasma fraction of CB in infants later diagnosed with ASD (n = 38) compared to infants typically developing (TD) at age 3 years (n = 103), using multiplex cytokine assays. Our findings reveal altered levels of several inflammatory cytokines in children later diagnosed with ASD, including increased granulocyte colony-stimulating factor (G-CSF) and decreased interleukin-1α (IL-1α), IL-1β, and IL-4 in CB. Furthermore, we identified several associations between behaviors and levels of cytokines, chemokines and growth factors. IL-1α, IL-17A, interferon γ-induced protein 10 (IP-10), and epidermal growth factor (EGF) were associated with worse scores on Autism Diagnostic Observation Schedule (ADOS) and the Mullen Scales of Early Learning (MSEL) assessments. In summary, our study demonstrates dysregulated levels of inflammatory cytokine mediators in the CB of children later diagnosed with ASD and that inflammatory mediators were associated with ASD severity, comorbid behaviors, and neurodevelopmental measures. These findings have important implications for the possible predictive value of early cytokine measures in neurodevelopmental outcomes and subsequent behavioral manifestations.

Dysbiosis and fecal microbiota transplant: Contemplating progress in health, neurodegeneration and longevity

The gut-brain axis plays an important role in mental health. The intestinal epithelial surface is colonized by billions of commensal and transitory bacteria, known as the Gut Microbiota (GM). However, potential pathogens continuously stimulate intestinal immunity when they find the place. The last two decades have witnessed several studies revealing intestinal bacteria as a key factor in the health-disease balance of the gut, as well as disease-emergent in other parts of the body. Various neurological processes, such as cognition, learning, and memory, could be affected by dysbiosis in GM. Additionally, the aging process and longevity are related to systemic inflammation caused by dysbiosis. Commensal GM affects brain development, behavior, and healthy aging suggesting that building changes in GM might be a potential therapeutic method. The innovation in GM dysbiosis is intervention by Fecal Microbiota Transplantation (FMT), which has been confirmed as a therapy for recurrent Clostridium difficile infections and is promising for other clinical disorders, such as Parkinson's disease, Multiple Sclerosis (MS), Alzheimer's disease, and depression. Additionally, FMT may be possible to promote healthy aging, and extend longevity. This review aims to connect dysbiosis, neurological disorders, and aging and the potential of FMT as a therapeutic strategy to treat these disorders, and to enhance the quality of life in the elderly.

The relationship between allergic rhinitis and attention deficit hyperactivity disorder: a systematic review and meta-analysis

Background

Numerous investigations have examined the potential link between allergic rhinitis (AR) and attention deficit hyperactivity disorder (ADHD). However, some studies show no association between the two diseases. The connection between these two conditions remains inconclusive. This study aimed to conduct a meta-analysis exploring the correlation between AR and ADHD.

Methods

We conducted systematic searches of the MEDLINE, EMBASE, Cochrane Library, ERIC, PubMed, Web of Science, and CINAHL databases, up to the year 2023. Subsequently, we conducted a meta-analysis using R 4.2.2, where we computed the pooled odds ratio with a 95% confidence interval to assess the relationship between AR and ADHD within studies exhibiting similar characteristics. Statistical heterogeneity was evaluated by computing the value using the Cochrane Intervention Manual's guidelines. Additionally, subgroup analyses were conducted by stratifying the study population according to gender, age, etc. Sensitivity analysis was performed by systematically removing individual studies.

Results

In this systematic review, we incorporated 12 eligible studies, collectively encompassing a sample size of 530,360 participants. Within the included studies, heterogeneity was observed, and the utilization of a random-effects model demonstrated a noteworthy correlation between children with ADHD and the presence of AR. Similarly, children with AR exhibited a significant correlation with the occurrence of ADHD. We also found some relationships in subgroup analyses.

Conclusion

A substantial correlation is evident between AR and ADHD in children and adolescents. AR may potentially contribute as a risk factor for the onset of ADHD, and conversely, ADHD may heighten the likelihood of developing AR.

Therapeutic efficacy of Genistein in activation of neuronal AC/cAMP/CREB/PKA and mitochondrial ETC-Complex pathways in experimental model of autism: Evidence from CSF, blood plasma and brain analysis

Autism is a complex neurodevelopmental condition characterized by repetitive behaviors, impaired social communication, and various associated conditions such as depression and anxiety. Its multifactorial etiology includes genetic, environmental, dietary, and gastrointestinal contributions. Pathologically, Autism is linked to mitochondrial dysfunction, oxidative stress, neuroinflammation, and neurotransmitter imbalances involving GABA, glutamate, dopamine, and oxytocin. Propionic acid (PRPA) is a short-chain fatty acid produced by gut bacteria, influencing central nervous system functions. Elevated PRPA levels can exacerbate Autism-related symptoms by disrupting metabolic processes and crossing the blood-brain barrier. Our research investigates the neuroprotective potential of Genistein (GNT), an isoflavone compound with known benefits in neuropsychiatric and neurodegenerative disorders, through modulation of the AC/cAMP/CREB/PKA signaling pathway and mitochondrial ETC complex (I-IV) function. In silico analyses revealed GNT's high affinity for these targets. Subsequent in vitro and in vivo experiments using a PRPA-induced rat model of autism demonstrated that GNT (40 and 80 mg/kg., orally) significantly improves locomotion, neuromuscular coordination, and cognitive functions in PRPA-treated rodents. Behavioral assessments showed reduced immobility in the forced swim test, enhanced Morris water maze performance, and restored regular locomotor activity. On a molecular level, GNT restored levels of key signaling molecules (AC, cAMP, CREB, PKA) and mitochondrial complexes (I-V), disrupted by PRPA exposure. Additionally, GNT reduced neuroinflammation and apoptosis, normalized neurotransmitter levels, and improved the complete blood count profile. Histopathological analyses confirmed that GNT ameliorated PRPA-induced brain injuries, restored normal brain morphology, reduced demyelination, and promoted neurogenesis. The study supports GNT's potential in autism treatment by modulating neural pathways, reducing inflammation, and restoring neurotransmitter balance.

Immunological Biomarkers in Autism Spectrum Disorder: The Role of TNF-Alpha and Dependent Trends in Serum IL-6 and CXCL8

BACKGROUND

Autism spectrum disorder (ASD) has seen a rise in prevalence, and the immune system's role in brain development is increasingly recognized. This study investigates the relationship between immune dysregulation and ASD by examining serum concentrations of interleukin 6 (IL-6), interleukin 8 (CXCL8), and tumor necrosis factor alpha (TNF-alpha) in children.

METHODS

Serum samples from 45 children with ASD and 30 controls, aged 2 to 12 years, were analyzed using electrochemiluminescence, chemiluminescent microparticle immunoassay, and chemiluminescent immunoassay. ASD symptoms were assessed using the Autism Spectrum Rating Scale (ASRS) and Social Communication Questionnaire (SCQ).

RESULTS

No significant correlation was observed between CXCL8 levels and ASD. IL-6 levels showed a trend toward elevation in boys with ASD. TNF-alpha levels were significantly higher in children with ASD under 5 years compared to older children and controls, though no correlation with symptom severity was found.

CONCLUSIONS

TNF-alpha may be a potential biomarker for early ASD detection, especially in younger children. Further research on larger cohorts is needed to understand the role of immune dysregulation in ASD.

Immune system dysfunction and inflammation in aging Shank3b mutant mice, a model of autism spectrum disorder

Introduction

Autism spectrum disorder (ASD) is a heterogeneous group of neurodevelopmental Q8 conditions characterized by deficits in social interaction/communication and restrictive/repetitive behaviors. Recent studies highlight the role of immune system dysfunction and inflammation in ASD pathophysiology. Indeed, elevated levels of pro-inflammatory cytokines were described in the brain and peripheral blood of ASD individuals. Despite this, how this pro-inflammatory profile evolves with aging and whether it may be associated with behavioral deficits is unknown. In this work, we explored the impact of aging on motor behavior and inflammation using Shank3b mutant mice, a model for syndromic ASD.

Methods

Using RT-qPCR and flow cytometry, we examined the expression of key pro-inflammatory molecules in the cerebellum, bone marrow, spleen, and peripheral blood, comparing adult and old Shank3b +/+, Shank3b +/-, and Shank3b -/- mice.

Results and discussion

Our findings revealed genotype- and age-related differences in inflammation and motor behavior, with Shank3b-/- mice exhibiting accelerated aging and motor impairments. Correlations between pro-inflammatory molecules and behavioral deficits suggest that a link may be present between systemic inflammation and ASD-related behaviors, underscoring the potential role of age-related inflammation ("inflammaging") in exacerbating ASD symptoms.

Genetic Variations and Serum Levels of Leptin and Ghrelin in Autism Spectrum Disorder

Background

This study aims to examine leptin and ghrelin gene polymorphisms and serum levels in children with autism spectrum disorder (ASD).

Methods

The study comprised a case group of 40 children aged 2-7 diagnosed with ASD and a control group of 40 healthy children. The severity of ASD symptoms was assessed using the Childhood Autism Rating Scale and the Autism Behavior Checklist. Leptin and ghrelin gene variants were genotyped using polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) methods. Serum ghrelin and leptin levels were measured using enzyme-linked immunosorbent assay kits.

Results

In this study, gene polymorphisms and allele frequencies were examined, and no significant difference was found (P > .05 for all). Our findings indicated no significant difference in leptin serum levels between the groups (P = .584). However, ghrelin serum levels were significantly lower in the ASD group (P = .027). Receiver operating curve analysis to determine the cutoff value of serum ghrelin level as a diagnostic indicator for ASD resulted in a cutoff value of 885.7 pg/mL with 42.50% sensitivity and 85% specificity (P = .021). No significant relationship was found between leptin and ghrelin serum levels and the severity of ASD (P > .05 for all).

Conclusion

Our study is the first to evaluate leptin and ghrelin gene polymorphisms in ASD. Our findings indicate no association between leptin and ghrelin gene polymorphisms and ASD. However, our study suggests that ghrelin serum levels may potentially contribute to the etiology of ASD. More research is needed to understand the role of leptin and ghrelin in ASD.

The fetal programming effect of maternal immune activation (MIA) on the offspring's immune system

The first 1000 days of life is a critical period of development in which adverse circumstances can have long-term consequences for the child's health. Maternal immune activation is associated with increased risk of neurodevelopmental disorders in the child. Aberrant immune responses have been reported in individuals with neurodevelopmental disorders. Moreover, lasting effects of maternal immune activation on the offspring's immune system have been reported. Taken together, this indicates that the effect of maternal immune activation is not limited to the central nervous system. Here, we explore the impact of maternal immune activation on the immune system of the offspring. We first describe the development of the immune system and provide an overview of reported alterations in the cytokine profiles, immune cell profiles, immune cell function, and immune induction in pre-clinical models. Additionally, we highlight recent research on the impact of maternal COVID-19 exposure on the neonatal immune system and the potential health consequences for the child. Our review shows that maternal immune activation alters the offspring's immune system under certain conditions, but the reported effects are conflicting and inconsistent. In general, epigenetic modifications are considered the mechanism for fetal programming. The available data was insufficient to identify specific pathways that may contribute to immune programming. As a consequence of the COVID-19 pandemic, more research now focuses on the possible health effects of maternal immune activation on the offspring. Future research addressing the offspring's immune response to maternal immune activation can elucidate specific pathways that contribute to fetal immune programming and the long-term health effects for the offspring.

Transcallosal white matter and cortical gray matter variations in autistic adults ages 30-73 years: A bi-tensor free water imaging approach

Background: Autism spectrum disorder (ASD) has long been recognized as a lifelong condition, but brain aging studies in autistic adults aged >30 years are limited. Free water, a novel brain imaging marker derived from diffusion MRI (dMRI), has shown promise in differentiating typical and pathological aging and monitoring brain degeneration. We aimed to examine free water and free water corrected dMRI measures to assess white and gray matter microstructure and their associations with age in autistic adults. Methods: Forty-three autistic adults ages 30-73 years and 43 age, sex, and IQ matched neurotypical controls participated in this cross-sectional study. We quantified fractional anisotropy (FA), free water, and free water-corrected FA (fwcFA) across 32 transcallosal white matter tracts and 94 gray matter areas in autistic adults and neurotypical controls. Follow-up analyses assessed age effect on dMRI metrics of the whole brain for both groups and the relationship between dMRI metrics and clinical measures of ASD in regions that significantly differentiated autistic adults from controls. Results: We found globally elevated free water in 24 transcallosal tracts in autistic adults. We identified negligible differences in dMRI metrics in gray matter between the two groups. Age-associated FA reductions and free water increases were featured in neurotypical controls; however, this brain aging profile was largely absent in autistic adults. Additionally, greater autism quotient (AQ) total raw score was associated with increased free water in the inferior frontal gyrus pars orbitalis and lateral orbital gyrus in autistic adults. Limitations: All autistic adults were cognitively capable individuals, minimizing the generalizability of the research findings across the spectrum. This study also involved a cross-sectional design, which limited inferences about the longitudinal microstructural changes of white and gray matter in ASD. Conclusions: We identified differential microstructural configurations between white and gray matter in autistic adults and that autistic individuals present more heterogeneous brain aging profiles compared to controls. Our clinical correlation analysis offered new evidence that elevated free water in some localized white matter tracts may critically contribute to autistic traits in ASD. Our findings underscored the importance of quantifying free water in dMRI studies of ASD.

Delving into the Complexity of Valproate-Induced Autism Spectrum Disorder: The Use of Zebrafish Models

Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental condition with several identified risk factors, both genetic and non-genetic. Among these, prenatal exposure to valproic acid (VPA) has been extensively associated with the development of the disorder. The zebrafish, a cost- and time-effective model, is useful for studying ASD features. Using validated VPA-induced ASD zebrafish models, we aimed to provide new insights into VPA exposure effects during embryonic development and to identify new potential biomarkers associated with ASD-like features. Dose-response analyses were performed in vivo to study larval phenotypes and mechanisms underlying neuroinflammation, mitochondrial dysfunction, oxidative stress, microglial cell status, and motor behaviour. Wild-type and transgenic Tg(mpeg1:EGFP) zebrafish were water-exposed to VPA doses (5 to 500 µM) from 6 to 120 h post-fertilisation (hpf). Embryos and larvae were monitored daily to assess survival and hatching rates, and numerous analyses and tests were conducted from 24 to 120 hpf. VPA doses higher than 50 µM worsened survival and hatching rates, while doses of 25 µM or more altered morphology, microglial status, and larval behaviours. VPA 50 µM also affected mRNA expression of inflammatory cytokines and neurogenesis-related genes, mitochondrial respiration, and reactive oxygen species accumulation. The study confirmed that VPA alters brain homeostasis, synaptic interconnections, and neurogenesis-related signalling pathways, contributing to ASD aetiopathogenesis. Further studies are essential to identify novel ASD biomarkers for developing new drug targets and tailored therapeutic interventions for ASD.

Increased gene dosage of RFWD2 causes autistic-like behaviors and aberrant synaptic formation and function in mice

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interactions, communication deficits and repetitive behaviors. A study of autistic human subjects has identified RFWD2 as a susceptibility gene for autism, and autistic patients have 3 copies of the RFWD2 gene. The role of RFWD2 as an E3 ligase in neuronal functions, and its contribution to the pathophysiology of ASD, remain unknown. We generated RFWD2 knockin mice to model the human autistic condition of high gene dosage of RFWD2. We found that heterozygous knockin (Rfwd2+/-) male mice exhibited the core symptoms of autism. Rfwd2+/- male mice showed deficits in social interaction and communication, increased repetitive and anxiety-like behavior, and spatial memory deficits, whereas Rfwd2+/- female mice showed subtle deficits in social communication and spatial memory but were normal in anxiety-like, repetitive, and social behaviors. These autistic-like behaviors in males were accompanied by a reduction in dendritic spine density and abnormal synaptic function on layer II/III pyramidal neurons in the prelimbic area of the medial prefrontal cortex (mPFC), as well as decreased expression of synaptic proteins. Impaired social behaviors in Rfwd2+/- male mice were rescued by the expression of ETV5, one of the major substrates of RFWD2, in the mPFC. These findings indicate an important role of RFWD2 in the pathogenesis of autism.

Acute rapamycin treatment reveals novel mechanisms of behavioral, physiological, and functional dysfunction in a maternal inflammation mouse model of autism and sensory over-responsivity

Maternal inflammatory response (MIR) during early gestation in mice induces a cascade of physiological and behavioral changes that have been associated with autism spectrum disorder (ASD). In a prior study and the current one, we find that mild MIR results in chronic systemic and neuro-inflammation, mTOR pathway activation, mild brain overgrowth followed by regionally specific volumetric changes, sensory processing dysregulation, and social and repetitive behavior abnormalities. Prior studies of rapamycin treatment in autism models have focused on chronic treatments that might be expected to alter or prevent physical brain changes. Here, we have focused on the acute effects of rapamycin to uncover novel mechanisms of dysfunction and related to mTOR pathway signaling. We find that within 2 hours, rapamycin treatment could rapidly rescue neuronal hyper-excitability, seizure susceptibility, functional network connectivity and brain community structure, and repetitive behaviors and sensory over-responsivity in adult offspring with persistent brain overgrowth. These CNS-mediated effects are also associated with alteration of the expression of several ASD-,ion channel-, and epilepsy-associated genes, in the same time frame. Our findings suggest that mTOR dysregulation in MIR offspring is a key contributor to various levels of brain dysfunction, including neuronal excitability, altered gene expression in multiple cell types, sensory functional network connectivity, and modulation of information flow. However, we demonstrate that the adult MIR brain is also amenable to rapid normalization of these functional changes which results in the rescue of both core and comorbid ASD behaviors in adult animals without requiring long-term physical alterations to the brain. Thus, restoring excitatory/inhibitory imbalance and sensory functional network modularity may be important targets for therapeutically addressing both primary sensory and social behavior phenotypes, and compensatory repetitive behavior phenotypes.

Understanding the link between different types of maternal diabetes and the onset of autism spectrum disorders

Autism spectrum disorders (ASD) encompass a collection of neurodevelopmental disorders that exhibit impaired social interactions and repetitive stereotypic behaviors. Although the exact cause of these disorders remains unknown, it is widely accepted that both genetic and environmental factors contribute to their onset and progression. Recent studies have highlighted the potential negative impact of maternal diabetes on embryonic neurodevelopment, suggesting that intrauterine hyperglycemia could pose an additional risk to early brain development and contribute to the development of ASD. This paper presents a comprehensive analysis of the current research on the relationship between various forms of maternal diabetes, such as type 1 diabetes mellitus, type 2 diabetes mellitus, and gestational diabetes mellitus, and the likelihood of ASD in offspring. The study elucidates the potential mechanisms through which maternal hyperglycemia affects fetal development, involving metabolic hormones, immune dysregulation, heightened oxidative stress, and epigenetic alterations. The findings of this review offer valuable insights for potential preventive measures and evidence-based interventions targeting ASD.

Aflatoxin B1 exposure deteriorates immune abnormalities in a BTBR T+ Itpr3tf/J mouse model of autism by increasing inflammatory mediators' production in CD19-expressing cells

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by deficiencies in communication, repetitive and stereotyped behavioral patterns, and difficulties in reciprocal social engagement. The presence of immunological dysfunction in ASD has been well established. Aflatoxin B1 (AFB1) is a prevalent mycotoxin found in food and feed, causing immune toxicity and hepatotoxicity. AFB1 is significantly elevated in several regions around the globe. Existing research indicates that prolonged exposure to AFB1 results in neurological problems. The BTBR T+ Itpr3tf/J (BTBR) mice, which were used as an autism model, exhibit the primary behavioral traits that define ASD, such as repeated, stereotyped behaviors and impaired social interactions. The main objective of this work was to assess the toxic impact of AFB1 in BTBR mice. This work aimed to examine the effects of AFB1 on the expression of Notch-1, IL-6, MCP-1, iNOS, GM-CSF, and NF-κB p65 by CD19+ B cells in the spleen of the BTBR using flow cytometry. We also verified the impact of AFB1 exposure on the mRNA expression levels of Notch-1, IL-6, MCP-1, iNOS, GM-CSF, and NF-κB p65 in the brain of BTBR mice using real-time PCR. The findings of our study showed that the mice treated with AFB1 in the BTBR group exhibited a substantial increase in the presence of CD19+Notch-1+, CD19+IL-6+, CD19+MCP-1+, CD19+iNOS+, CD19+GM-CSF+, and CD19+NF-κB p65+ compared to the mice in the BTBR group that were treated with saline. Our findings also confirmed that administering AFB1 to BTBR mice leads to elevated mRNA expression levels of Notch-1, IL-6, MCP-1, iNOS, GM-CSF, and NF-κB p65 in the brain, in comparison to BTBR mice treated with saline. The data highlight that exposure to AFB1 worsens immunological abnormalities by increasing the expression of inflammatory mediators in BTBR mice.

Aflatoxin B1 exposure exacerbates chemokine receptor expression in the BTBR T+ Itpr3tf/J Mouse Model, unveiling insights into autism spectrum disorder: A focus on brain and spleen

OBJECTIVE

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by significant difficulties in social interaction, communication, and repeated stereotypic behaviour. Aflatoxin B1 (AFB1) is the most potent and well-known mycotoxin in various food sources. Despite its propensity to generate significant biochemical and structural changes in human and animal tissues, the influence of AFB1 on ASD has yet to be thoroughly studied. Mounting evidence indicates that chemokine receptors play a crucial function in the central nervous system and are implicated in developing several neuroinflammatory disorders. Chemokine receptors in individuals with ASD were elevated in the anterior cingulate gyrus astrocytes, cerebellum, and brain.

METHODS

The BTBR T+Itpr3tf/J (BTBR) mice are inbred strains that exhibit strong and consistently observed deficits in social interactions, characterized by excessive self-grooming and limited vocalization in social contexts. We examined the impact of AFB1 on CCR3-, CCR7-, CCR9-, CXCR3-, CXCR4-, and CXCR6-expressing I-A/I-E+ cells in the spleen of the BTBR mouse model of autism. We evaluated the mRNA levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 chemokine receptors in the brain.

RESULTS

The exposure to AFB1 in BTBR mice resulted in a significant rise in the number of I-A/I-E+CCR3+, I-A/I-E+CCR7+, I-A/I-E+CCR9+, I-A/I-E+CXCR3+, I-A/I-E+CXCR4+, and I-A/I-E+CXCR6+ cells. Furthermore, exposure to AFB1 increased mRNA expression levels of CCR3, CCR7, CCR9, CXCR3, CXCR4, and CXCR6 in the brain.

CONCLUSIONS

These findings highlight that AFB1 exposure increases the expression of chemokine receptors in BTBR mice, indicating the necessity for further research into AFB1's role in the development of ASD.

Label free quantitative proteomic profiling of serum samples of intellectually disabled young patients revealed dysregulation of complement coagulation and cholesterol cascade systems

Intellectual disability is a heterogeneous disorder, diagnosed using intelligence quotient (IQ) score criteria. Currently, no specific clinical test is available to diagnose the disease and its subgroups due to inadequate understanding of the pathophysiology. Therefore, current study was designed to explore the molecular mechanisms involved in disease perturbation, and to identify potential biomarkers for disease diagnosis and prognosis. A total of 250 participants were enrolled in this study, including 200 intellectually disabled (ID) subjects from the subgroups (mild, moderate, and severe) with age and gender matched healthy controls (n = 50). Initially, IQ testing score and biochemical profile of each subject was generated, followed by label-free quantitative proteomics of subgroups of IQ and healthy control group through nano-LC/MS- mass spectrometry. A total of 310 proteins were identified, among them198 proteins were common among all groups. Statistical analysis (ANOVA) of the subgroups of ID showed 142 differentially expressed proteins, in comparison to healthy control group. From these, 120 proteins were found to be common among all subgroups. The remaining 22 proteins were categorized as exclusive proteins found only in disease subgroups. Furthermore, the hierarchical cluster analysis (HCL) of common significant proteins was also performed, followed by PANTHER protein classification and GO functional enrichment analysis. Results provides that the datasets of differentially expressed proteins, belong to the categories of immune / defense proteins, transfer carrier proteins, apolipoproteins, complement proteins, protease inhibitors, hemoglobin proteins etc., they are known to involvein immune system, and complement and coagulation pathway cascade and cholesterol metabolism pathway. Exclusively expressed 22 proteins were found to be disease stage specific and strong PPI network specifically those that have significant role in platelets activation and degranulation, such as Filamin A (FLNA). Furthermore, to validate the mass spectrometric findings, four highly significant proteins (APOA4, SAP, FLNA, and SERPING) were quantified by ELISA in all the study subjects. AUROC analysis showed a significant association of APOA4 (0.830), FLNA (0.958), SAP (0.754) and SERPING (0.600) with the disease. Apolipoprotein A4 (APOA4) has a significant role in cholesterol transport, and in modulation of glucose and lipid metabolism in the CNS. Similarly, FLNA has a crucial role in the nervous system, especially in the functioning of synaptic network. Therefore, both APOA4, and FLNA proteins represent good potential for candidate biomarkers for the diagnosis and prognosis of the intellectual disability. Overall, serum proteome of ID patients provides valuable information of proteins/pathways that are altered during ID progression.

Social isolation induces intestinal barrier disorder and imbalances gut microbiota in mice

Social isolation, a known stressor, can have detrimental effects on both physical and mental health. Recent scientific attention has been drawn to the gut-brain axis, a bidirectional communication system between the central nervous system and gut microbiota, suggesting that gut microbes may influence brain function. This study aimed to explore the impact of social isolation on the intestinal barrier and gut microbiota. 40 male BALB/c mice were either individually housed or kept in groups for 8 and 15 weeks. Socially isolated mice exhibited increased anxiety-like behavior, with significant differences between the 8-week and 15-week isolation groups (P < 0.05). After 8 weeks of isolation, there was a reduction in tight junction protein expression in the intestinal mechanical barrier. Furthermore, after 15 weeks of isolation, both tight junction protein and mucin expression, key components of the intestinal chemical barrier, decreased. This was accompanied by a substantial increase in inflammatory cytokines (IL-6 mRNA, IL-10, and TNF-α) in colon tissue in the 15-week isolated group (P < 0.05). Additionally, Illumina MiSequencing revealed significant alterations in the gut microbiota of socially isolated mice, including reduced Firmicutes and Bacteroides compared to the control group. Lactobacillus levels also decreased in the socially isolated mice.

A leaky gut dysregulates gene networks in the brain associated with immune activation, oxidative stress, and myelination in a mouse model of colitis

The gut and brain are increasingly linked in human disease, with neuropsychiatric conditions classically attributed to the brain showing an involvement of the intestine and inflammatory bowel diseases (IBDs) displaying an ever-expanding list of neurological comorbidities. To identify molecular systems that underpin this gut-brain connection and thus discover therapeutic targets, experimental models of gut dysfunction must be evaluated for brain effects. In the present study, we examine disturbances along the gut-brain axis in a widely used murine model of colitis, the dextran sodium sulfate (DSS) model, using high-throughput transcriptomics and an unbiased network analysis strategy coupled with standard biochemical outcome measures to achieve a comprehensive approach to identify key disease processes in both colon and brain. We examine the reproducibility of colitis induction with this model and its resulting genetic programs during different phases of disease, finding that DSS-induced colitis is largely reproducible with a few site-specific molecular features. We focus on the circulating immune system as the intermediary between the gut and brain, which exhibits an activation of pro-inflammatory innate immunity during colitis. Our unbiased transcriptomics analysis provides supporting evidence for immune activation in the brain during colitis, suggests that myelination may be a process vulnerable to increased intestinal permeability, and identifies a possible role for oxidative stress and brain oxygenation. Overall, we provide a comprehensive evaluation of multiple systems in a prevalent experimental model of intestinal permeability, which will inform future studies using this model and others, assist in the identification of druggable targets in the gut-brain axis, and contribute to our understanding of the concomitance of intestinal and neuropsychiatric dysfunction.

Causal effects of gut microbiota on autism spectrum disorder: A two-sample mendelian randomization study

There is increasing evidence that alterations in gut microbiota (GM) composition are associated with autism spectrum disorder (ASD), but no reliable causal relationship has been established. Therefore, a 2-sample Mendelian randomization (MR) study was conducted to reveal a potential causal relationship between GM and ASD. Instrumental variables for 211 GM taxa were obtained from genome-wide association studies (GWAS) and Mendelian randomization studies to estimate their impact on ASD risk in the iPSYCH-PGC GWAS dataset (18,382 ASD cases and 27,969 controls). Inverse variance weighted (IVW) is the primary method for causality analysis, and several sensitivity analyses validate MR results. Among 211 GM taxa, IVW results confirmed that Tenericutes (P value = .0369), Mollicutes (P value = .0369), Negativicutes (P value = .0374), Bifidobacteriales (P value = .0389), Selenomonadales (P value = .0374), Bifidobacteriaceae (P value = .0389), Family XIII (P value = .0149), Prevotella7 (P value = .0215), Ruminococcaceae NK4A214 group (P value = .0205) were potential protective factors for ASD. Eisenbergiella (P value = .0159) was a possible risk factor for ASD. No evidence of heterogeneous, pleiotropic, or outlier single-nucleotide polymorphism was detected. Additionally, further sensitivity analysis verified the robustness of the above results. We confirm a potential causal relationship between certain gut microbes and ASD, providing new insights into how gut microbes mediate ASD. The association between them needs to be further explored and will provide new ideas for the prevention and treatment of ASD.

Autism spectrum disorder: pathogenesis, biomarker, and intervention therapy

Autism spectrum disorder (ASD) has become a common neurodevelopmental disorder. The heterogeneity of ASD poses great challenges for its research and clinical translation. On the basis of reviewing the heterogeneity of ASD, this review systematically summarized the current status and progress of pathogenesis, diagnostic markers, and interventions for ASD. We provided an overview of the ASD molecular mechanisms identified by multi-omics studies and convergent mechanism in different genetic backgrounds. The comorbidities, mechanisms associated with important physiological and metabolic abnormalities (i.e., inflammation, immunity, oxidative stress, and mitochondrial dysfunction), and gut microbial disorder in ASD were reviewed. The non-targeted omics and targeting studies of diagnostic markers for ASD were also reviewed. Moreover, we summarized the progress and methods of behavioral and educational interventions, intervention methods related to technological devices, and research on medical interventions and potential drug targets. This review highlighted the application of high-throughput omics methods in ASD research and emphasized the importance of seeking homogeneity from heterogeneity and exploring the convergence of disease mechanisms, biomarkers, and intervention approaches, and proposes that taking into account individuality and commonality may be the key to achieve accurate diagnosis and treatment of ASD.

Approaches of marine compounds and relevant immune mediators in Autism Spectrum Disorder: Opportunities and challenges

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that affects social skills, language, communication, and behavioral skills, significantly impacting the individual's quality of life. Recently, numerous works have centered on the connections between the immune and central nervous systems and the influence of neuroinflammation on autism symptomatology. Marine natural products are considered as important alternative sources of different types of compounds, including polysaccharides, polyphenols, sterols, carotenoids, terpenoids and, alkaloids. These compounds present anti-inflammatory, neuroprotective and immunomodulatory activities, exhibiting a potential for the treatment of many diseases. Although many studies address the marine compounds in the modulation of inflammatory mediators, there is a gap regarding their use in the regulation of the immune system in ASD. Thus, this review aims to provide a better understanding regarding cytokines, chemokines, growth factors and immune responses in ASD, as well as the potential of bioactive marine compounds in the immune regulation in ASD. We expect that this review would contribute to the development of therapeutic alternatives for controlling immune mediators and inflammation in ASD.

Discovery of a novel cytokine signature for the diagnosis of autism spectrum disorder in young Arab children in Qatar

Background

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by impaired social interaction and communication and the occurrence of stereotyped and repetitive behaviors. Several studies have reported altered cytokine profiles in ASD and hence may serve as potential diagnostic biomarkers of the disorder. This study aims to identify diagnostic biomarkers for ASD in a well-defined study cohort in Qatar.

Methods

We measured the protein levels of 45 cytokines in the plasma samples of age- and gender-matched children (2-4 years) with ASD (n = 100) and controls (n = 60) using a Luminex multiplex assay. We compared the differences in the levels of these cytokines between the two study groups and then fitted the significantly altered cytokines into a logistic regression model to examine their diagnostic potential for ASD.

Results

We found elevated levels of IFN-γ, FGF-2, IL-1RA, and IL-13 and reduced levels of eotaxin, HGF, IL-1 alpha, IL-22, IL-9, MCP-1, SCF, SDF-1 alpha, VEGFA, and IP-10 in the plasma of children with ASD compared to controls. Furthermore, we observed that elevated levels of IFN-γ (odds ratio (OR) = 1.823; 95% (confidence interval) CI = 1.206, 2.755; p = 0.004) and FGF-2 (OR = 2.528; 95% CI = 1.457, 4.385; p < 0.001) were significantly associated with increased odds of ASD, whereas reduced levels of eotaxin (OR = 0.350; 95% CI = 0.160, 0.765; p = 0.008) and HGF (OR = 0.220; 95% CI = 0.070, 0.696; p = 0.010) were significantly associated with lower odds of ASD relative to controls. The combination of these four cytokines revealed an area under the curve (ROC-AUC) of 0.829 (95% CI = 0.767, 0.891; p < 0.001), which demonstrates the diagnostic accuracy of the four-cytokine signature.

Conclusions

Our results identified a panel of cytokines that could discriminate between children with ASD and controls in Qatar. In addition, our findings support the predominance of a Th1 immune phenotype in ASD children and emphasize the need to validate these results in larger populations.

Pharmacological and non-pharmacological interventions for irritability in autism spectrum disorder: a systematic review and meta-analysis with the GRADE assessment

BACKGROUND

Numerous interventions for irritability in autism spectrum disorder (ASD) have been investigated. We aimed to appraise the magnitude of pharmacological and non-pharmacological interventions for irritability in ASD without any restrictions in terms of eligible interventions.

METHODS

We systematically searched PubMed/MEDLINE, Scopus, and Web of Science until April 15, 2023. We included randomized controlled trials (RCTs) with a parallel design that examined the efficacy of interventions for the treatment of irritability in patients of any age with ASD without any restrictions in terms of eligible interventions. We performed a random-effects meta-analysis by pooling effect sizes as Hedges' g. We classified assessed interventions as follows: pharmacological monotherapy, risperidone plus adjuvant therapy versus risperidone monotherapy, non-pharmacological intervention, and dietary intervention. We utilized the Cochrane tool to evaluate the risk of bias in each study and the GRADE approach to assess the certainty of evidence for each meta-analyzed intervention.

RESULTS

Out of 5640 references, we identified 60 eligible articles with 45 different kinds of interventions, including 3531 participants, of which 80.9% were males (mean age [SD] = 8.79 [3.85]). For pharmacological monotherapy, risperidone (Hedges' g - 0.857, 95% CI - 1.263 to - 0.451, certainty of evidence: high) and aripiprazole (Hedges' g - 0.559, 95% CI - 0.767 to - 0.351, certainty of evidence: high) outperformed placebo. Among the non-pharmacological interventions, parent training (Hedges' g - 0.893, 95% CI - 1.184 to - 0.602, certainty of evidence: moderate) showed a significant result. None of the meta-analyzed interventions yielded significant effects among risperidone + adjuvant therapy and dietary supplementation. However, several novel molecules in augmentation to risperidone outperformed risperidone monotherapy, yet from one RCT each.

LIMITATIONS

First, various tools have been utilized to measure the irritability in ASD, which may contribute to the heterogeneity of the outcomes. Second, meta-analyses for each intervention included only a small number of studies and participants.

CONCLUSIONS

Only risperidone, aripiprazole among pharmacological interventions, and parent training among non-pharmacological interventions can be recommended for irritability in ASD. As an augmentation to risperidone, several novel treatments show promising effects, but further RCTs are needed to replicate findings. Trial registration PROSPERO, CRD42021243965.

Genetic liability for gastrointestinal inflammation disorders and association with gastrointestinal symptoms in children with and without autism

Children with autism spectrum disorder (ASD) have a greater prevalence of gastrointestinal (GI) symptoms than children without ASD. We tested whether polygenic scores for each of three GI disorders (ulcerative colitis, inflammatory bowel disease, and Crohn's disease) were related to GI symptoms in children with and without ASD. Using genotyping data (564 ASD cases and 715 controls) and external genome-wide association study summary statistics, we computed GI polygenic scores for ulcerative colitis (UC-PGS), inflammatory bowel disease (IDB-PGS), and Crohn's disease (CD-PGS). Multivariable logistic regression models, adjusted for genetic ancestry, were used to estimate associations between each GI-PGS and (1) ASD case-control status, and (2) specific GI symptoms in neurotypical children and separately in ASD children. In children without ASD, polygenic scores for ulcerative colitis were significantly associated with experiencing any GI symptom (adjusted odds ratio (aOR) = 1.36, 95% confidence interval (CI) = 1.03-1.81, p = 0.03) and diarrhea specifically (aOR = 5.35, 95% CI = 1.77-26.20, p = 0.01). Among children without ASD, IBD-PGS, and Crohn's PGS were significantly associated with diarrhea (aOR = 3.55, 95% CI = 1.25-12.34, p = 0.02) and loose stools alternating with constipation (aOR = 2.57, 95% CI = 1.13-6.55, p = 0.03), respectively. However, the three PGS were not associated with GI symptoms in the ASD case group. Furthermore, polygenic scores for ulcerative colitis significantly interacted with ASD status on presentation of any GI symptom within a European ancestry subset (aOR = 0.42, 95% CI = 0.19-0.88, p = 0.02). Genetic risk factors for some GI symptoms differ between children with and without ASD. Furthermore, our finding that increased genetic risks for GI inflammatory disorders are associated with GI symptoms in children without ASD informs future work on the early detection of GI disorders.

The Genetic Architecture of Amygdala Nuclei

BACKGROUND

Whereas genetic variants influencing total amygdala volume have been identified, the genetic architecture of its distinct nuclei has yet to be explored. We aimed to investigate whether increased phenotypic specificity through nuclei segmentation aids genetic discoverability and elucidates the extent of shared genetic architecture and biological pathways with related disorders.

METHODS

T1-weighted brain magnetic resonance imaging scans (N = 36,352, 52% female) from the UK Biobank were segmented into 9 amygdala nuclei with FreeSurfer (version 6.1). Genome-wide association analyses were performed on the entire sample, a European-only subset (n = 31,690), and a generalization (transancestry) subset (n = 4662). We estimated single nucleotide polymorphism-based heritability; derived polygenicity, discoverability, and power estimates; and investigated genetic correlations and shared loci with psychiatric disorders.

RESULTS

The heritability of the nuclei ranged from 0.17 to 0.33. Across the whole amygdala and the nuclei volumes, we identified 28 novel genome-wide significant (padj < 5 × 10-9) loci in the European analysis, with significant en masse replication for the whole amygdala and central nucleus volumes in the generalization analysis, and we identified 10 additional candidate loci in the combined analysis. The central nucleus had the highest statistical power for discovery. The significantly associated genes and pathways showed unique and shared effects across the nuclei, including immune-related pathways. Shared variants were identified between specific nuclei and autism spectrum disorder, Alzheimer's disease, Parkinson's disease, bipolar disorder, and schizophrenia.

CONCLUSIONS

Through investigation of amygdala nuclei volumes, we have identified novel candidate loci in the neurobiology of amygdala volume. These nuclei volumes have unique associations with biological pathways and genetic overlap with psychiatric disorders.

Changes in neuroinflammatory markers and microglial density in the hippocampus and prefrontal cortex of the C58/J mouse model of autism

Autism spectrum disorder (ASD) is a diverse group of neurodevelopmental conditions with complex origins. Individuals with ASD present various neurobiological abnormalities, including an altered immune response in the central nervous system and other tissues. Animal models like the C58/J inbred mouse strain are used to study biological characteristics of ASD. This strain is considered an idiopathic autism model because of its demonstrated reduced social preference and repetitive behaviours. Notably, C58/J mice exhibit alterations in dendritic arbour complexity, density and dendritic spines maturation in the hippocampus and prefrontal cortex (PFC), but inflammatory-related changes have not been explored in these mice. In this study, we investigated proinflammatory markers in the hippocampus and PFC of adult male C58/J mice. We discovered elevated levels of interferon gamma (IFN-γ) and monocyte chemoattractant protein 1 (MCP-1) in the hippocampus, suggesting increased inflammation, alongside a reduction in the anti-inflammatory enzyme arginase 1 (ARG1). Conversely, the PFC displayed reduced levels of TNF-α and MCP-1. Microglial analysis revealed higher levels of transmembrane protein 119 (TMEM119) and increased microglial density in a region-specific manner of the autistic-like mice, particularly in the PFC and hippocampus. Additionally, an augmented expression of the fractalkine receptor CX3CR1 was observed in the hippocampus and PFC of C58/J mice. Microglial morphological analysis shows no evident changes in the hippocampus of mice with autistic-like behaviours versus wild-type strain. These region-specific changes can contribute to modulate processes like inflammation or synaptic pruning in the C58/J mouse model of idiopathic autism.

Endophenotype trait domains for advancing gene discovery in autism spectrum disorder

Autism spectrum disorder (ASD) is associated with a diverse range of etiological processes, including both genetic and non-genetic causes. For a plurality of individuals with ASD, it is likely that the primary causes involve multiple common inherited variants that individually account for only small levels of variation in phenotypic outcomes. This genetic landscape creates a major challenge for detecting small but important pathogenic effects associated with ASD. To address similar challenges, separate fields of medicine have identified endophenotypes, or discrete, quantitative traits that reflect genetic likelihood for a particular clinical condition and leveraged the study of these traits to map polygenic mechanisms and advance more personalized therapeutic strategies for complex diseases. Endophenotypes represent a distinct class of biomarkers useful for understanding genetic contributions to psychiatric and developmental disorders because they are embedded within the causal chain between genotype and clinical phenotype, and they are more proximal to the action of the gene(s) than behavioral traits. Despite their demonstrated power for guiding new understanding of complex genetic structures of clinical conditions, few endophenotypes associated with ASD have been identified and integrated into family genetic studies. In this review, we argue that advancing knowledge of the complex pathogenic processes that contribute to ASD can be accelerated by refocusing attention toward identifying endophenotypic traits reflective of inherited mechanisms. This pivot requires renewed emphasis on study designs with measurement of familial co-variation including infant sibling studies, family trio and quad designs, and analysis of monozygotic and dizygotic twin concordance for select trait dimensions. We also emphasize that clarification of endophenotypic traits necessarily will involve integration of transdiagnostic approaches as candidate traits likely reflect liability for multiple clinical conditions and often are agnostic to diagnostic boundaries. Multiple candidate endophenotypes associated with ASD likelihood are described, and we propose a new focus on the analysis of "endophenotype trait domains" (ETDs), or traits measured across multiple levels (e.g., molecular, cellular, neural system, neuropsychological) along the causal pathway from genes to behavior. To inform our central argument for research efforts toward ETD discovery, we first provide a brief review of the concept of endophenotypes and their application to psychiatry. Next, we highlight key criteria for determining the value of candidate endophenotypes, including unique considerations for the study of ASD. Descriptions of different study designs for assessing endophenotypes in ASD research then are offered, including analysis of how select patterns of results may help prioritize candidate traits in future research. We also present multiple candidate ETDs that collectively cover a breadth of clinical phenomena associated with ASD, including social, language/communication, cognitive control, and sensorimotor processes. These ETDs are described because they represent promising targets for gene discovery related to clinical autistic traits, and they serve as models for analysis of separate candidate domains that may inform understanding of inherited etiological processes associated with ASD as well as overlapping neurodevelopmental disorders.

The Exposure to Lead (Pb) Exacerbates Immunological Abnormalities in BTBR T+ Itpr3tf/J Mice through the Regulation of Signaling Pathways Relevant to T Cells

Autism spectrum disorder (ASD) is a common neurodevelopmental illness characterized by abnormal social interactions, communication difficulties, and repetitive and limited behaviors or interests. The BTBR T+ Itpr3tf/J (BTBR) mice have been used extensively to research the ASD-like phenotype. Lead (Pb) is a hazardous chemical linked to organ damage in the human body. It is regarded as one of the most common metal exposure sources and has been connected to the development of neurological abnormalities. We used flow cytometry to investigate the molecular mechanism behind the effect of Pb exposure on subsets of CD4+ T cells in the spleen expressing IFN-γ, T-bet, STAT1, STAT4, IL-9, IRF4, IL-22, AhR, IL-10, and Foxp3. Furthermore, using RT-PCR, we studied the effect of Pb on the expression of numerous genes in brain tissue, including IFN-γ, T-bet, STAT1, STAT4, IL-9, IRF4, IL-22, AhR, IL-10, and Foxp3. Pb exposure increased the population of CD4+IFN-γ+, CD4+T-bet+, CD4+STAT1+, CD4+STAT4+, CD4+IL-9+, CD4+IRF4+, CD4+IL-22+, and CD4+AhR+ cells in BTBR mice. In contrast, CD4+IL-10+ and CD4+Foxp3+ cells were downregulated in the spleen cells of Pb-exposed BTBR mice compared to those treated with vehicle. Furthermore, Pb exposure led to a significant increase in IFN-γ, T-bet, STAT1, STAT4, IL-9, IRF4, IL-22, and AhR mRNA expression in BTBR mice. In contrast, IL-10 and Foxp3 mRNA expression was significantly lower in those treated with the vehicle. Our data suggest that Pb exposure exacerbates immunological dysfunctions associated with ASD. These data imply that Pb exposure may increase the risk of ASD.

Immunogenetics of autism spectrum disorder: A systematic literature review

The aetiology of autism spectrum disorder (ASD) is complex and, partly, accounted by genetic factors. Nonetheless, the genetic underpinnings of ASD are poorly defined. The presence of immune dysregulations in autistic individuals, and their families, supports a role of the immune system and its genetic regulators. Albeit immune responses belong either to the innate or adaptive arms, the overall immune system genetics is broad, and encompasses a multitude of functionally heterogenous pathways which may have different influences on ASD. Hence, to gain insights on the immunogenetic underpinnings of ASD, we conducted a systematic literature review of previous immune genetic and transcription studies in ASD. We defined a list of immune genes relevant to ASD and explored their neuro-immune function. Our review confirms the presence of immunogenetic variability in ASD, accounted by inherited variations of innate and adaptive immune system genes and genetic expression changes in the blood and post-mortem brain of autistic individuals. Besides their immune function, the identified genes control neurodevelopment processes (neuronal and synaptic plasticity) and are highly expressed in pre/peri-natal periods. Hence, our synthesis bolsters the hypothesis that perturbation in immune genes may contribute to ASD by derailing the typical trajectory of neurodevelopment. Our review also helped identifying some of the limitations of prior immunogenetic research in ASD. Thus, alongside clarifying the neurodevelopment role of immune genes, we outline key considerations for future work into the aetiology of ASD and possible novel intervention targets.

Role of autoimmunity in Neuronal damage in children with Autism spectrum disorder

"Autism spectrum disorder (ASD) is complex neurodevelopmental disorder characterized by impairments in three core behavioral: social deficits, impaired communication, and repetitive behaviors." There is developing indication and emerging data that irregular autoimmune responses to the central nervous system may play a pathogenic role in patients with autism spectrum disorder." The aim of this review was to discuss the updated research carried out at Autism research and treatment center, King Saud University, Riyadh, Kingdom of Saudi Arabia particularly on the role of autoimmunity in Autism spectrum disorder. This review also present state of information available about the role of autoimmunity biomarkers involved in the neuronal damage of central nervous system in autistic children. The systematic literature search was carried out using Google Scholar, Science direct and PubMed databases on the role of autoimmunity in autism and reviewed all relevant articles published in peer reviewed journals by Autism research and treatment center, King Saud University, Riyadh, Kingdom of Saudi Arabia till April, 2022. We searched relevant articles using key words Autism spectrum disorder, Autoimmunity, Neuroinflamation and Central nervous system. This review revealed that plasma levels of autoimmunity related factors/ markers were altered in patients with autism. Significant change in blood markers in subjects with ASD may resulted in several years of decreased neutrotrophic support along with increasing impairment in relationship with down-regulated inflammation that may play a role in the ASD. Overall, the role of autoimmunity in ASD subjects with excess of anti-brain antibodies suggest that in some patients, autoantibodies that target the CNS may be pathological factor in neuronal growth in autistic children. Large cohort studies with well-defined and specially pheno typed autistic groups and matched healthy controls are required to examine the role of autoantibodies in the pathology of subjects with ASD.

[Nature and immune mechanisms of mental illnesses]

The impacts of nature and climate change on mental health are substantial but the underlying mechanisms are still poorly understood. The immune system in particular could play an important role. Therefore, the German Center for Mental Health (DZPG) in Munich will use state of the art model systems to elucidate the role of the immune system in the pathogenesis of mental disorders under altered environmental conditions and to develop preventive treatment strategies.

Unveiling the interplay between NSAID-induced dysbiosis and autoimmune liver disease in children: insights into the hidden gateway to autism spectrum disorders. Evidence from ex vivo, in vivo, and clinical studies

Autism spectrum disorders (ASD) represent a diverse group of neuropsychiatric conditions, and recent evidence has suggested a connection between ASD and microbial dysbiosis. Immune and gastrointestinal dysfunction are associated with dysbiosis, and there are indications that modulating the microbiota could improve ASD-related behaviors. Additionally, recent findings highlighted the significant impact of microbiota on the development of autoimmune liver diseases, and the occurrence of autoimmune liver disease in children with ASD is noteworthy. In the present study, we conducted both an in vivo study and a clinical study to explore the relationship between indomethacin-induced dysbiosis, autoimmune hepatitis (AIH), and the development of ASD. Our results revealed that indomethacin administration induced intestinal dysbiosis and bacterial translocation, confirmed by microbiological analysis showing positive bacterial translocation in blood cultures. Furthermore, indomethacin administration led to disturbed intestinal permeability, evidenced by the activation of the NLRP3 inflammasomes pathway and elevation of downstream biomarkers (TLR4, IL18, caspase 1). The histological analysis supported these findings, showing widened intestinal tight junctions, decreased mucosal thickness, inflammatory cell infiltrates, and collagen deposition. Additionally, the disturbance of intestinal permeability was associated with immune activation in liver tissue and the development of AIH, as indicated by altered liver function, elevated ASMA and ANA in serum, and histological markers of autoimmune hepatitis. These results indicate that NSAID-induced intestinal dysbiosis and AIH are robust triggers for ASD existence. These findings were further confirmed by conducting a clinical study that involved children with ASD, autoimmune hepatitis (AIH), and a history of NSAID intake. Children exposed to NSAIDs in early life and complicated by dysbiosis and AIH exhibited elevated serum levels of NLRP3, IL18, liver enzymes, ASMA, ANA, JAK1, and IL6. Further, the correlation analysis demonstrated a positive relationship between the measured parameters and the severity of ASD. Our findings suggest a potential link between NSAIDs, dysbiosis-induced AIH, and the development of ASD. The identified markers hold promise as indicators for early diagnosis and prognosis of ASD. This research highlights the importance of maintaining healthy gut microbiota and supports the necessity for further investigation into the role of dysbiosis and AIH in the etiology of ASD.

Positive effects of physical activity in autism spectrum disorder: how influences behavior, metabolic disorder and gut microbiota

Autism spectrum disorder is a neurodevelopmental disorder characterized by social interactions and communication skills impairments that include intellectual disabilities, communication delays and self-injurious behaviors; often are present systemic comorbidities such as gastrointestinal disorders, obesity and cardiovascular disease. Moreover, in recent years has emerged a link between alterations in the intestinal microbiota and neurobehavioral symptoms in children with autism spectrum disorder. Recently, physical activity and exercise interventions are known to be beneficial for improving communication and social interaction and the composition of microbiota. In our review we intend to highlight how different types of sports can help to improve communication and social behaviors in children with autism and also show positive effects on gut microbiota composition.

IL-6, homocysteine, and autism spectrum phenotypes: an investigation among adults with autism spectrum disorder and their first-degree relatives

BACKGROUND

The importance of recognizing different kinds of autism spectrum presentations among adults, including subthreshold forms and the broad autism phenotype (BAP), has been increasingly highlighted in recent studies. Meanwhile, the possible involvement of immune system deregulation and altered methylation/trans-sulfuration processes in autism spectrum disorder (ASD) is gaining growing attention, but studies in this field are mainly focused on children. In this framework, the aim of this study was to compare plasmatic concentrations of IL-6 and homocysteine (HCY) among adults with ASD, their first-degree relatives, and healthy controls (CTLs), investigating also possible correlations with specific autism symptoms.

METHODS

Plasma concentrations of IL-6 and HCY were measured in a group of adult subjects with ASD, their first-degree relatives (BAP group), and healthy controls (CTL). All participants were also evaluated with psychometric instruments.

RESULTS

IL-6 and HCY concentrations were significantly higher in the ASD group than in CTLs, while BAP subjects reported intermediate results. Significant correlations were reported between biochemical parameters and psychometric scales, particularly for the dimension of ruminative thinking.

CONCLUSIONS

These findings support the hypothesis of a key involvement of HCY-related metabolism and immune system alteration in autism spectrum pathophysiology. HCY and IL-6 seem to show different associations with specific autism dimensions.

Dual-Hit: Glyphosate exposure at NOAEL level negatively impacts birth and glia-behavioural measures in heterozygous shank3 mutants

The omnipresence of environmental contaminants represents a health danger with ramifications for adverse neurological trajectories. Here, we tested the dual-hit hypothesis that continuous exposure to non-observable adverse effect level (NOAEL) glyphosate from pre-natal to adulthood represents a risk factor for neurological-associated adaptations when in the presence of the heterozygote or homozygote mutation of the Shank3 synaptic gene. Ultrasound analysis of pregnant dams revealed patterns of pre-natal mortality with effects dependent on wild-type, Shank3ΔC/+, or Shank3ΔC/ΔC genotypes exposed to NOAEL glyphosate (GLY) compared to unexposed conditions. The postnatal survival rate was negatively impacted, specifically in Shank3ΔC/+ exposed to GLY. Next, the resulting six groups of pups were tracked into adulthood and analyzed for signs of neuroinflammation and neurological adaptions. Sholl's analysis revealed cortical microgliosis across groups exposed to GLY, with Shank3ΔC/+ mice presenting the most significant modifications. Brain tissues were devoid of astrocytosis, except for the perivascular compartment in the cortex in response to GLY. Distinct behavioral adaptations accompanied these cellular modifications, as locomotion and social preference were decreased in Shank3ΔC/+ mice exposed to GLY. Notably, GLY exposure from weaning did not elicit glial or neurological adaptations across groups, indicating the importance of pre-natal contaminant exposure. These results unveil the intersection between continuous pre-natal to adulthood environmental input and a pre-existing synaptic mutation. In an animal model, NOAEL GLY predominantly impacted Shank3ΔC/+ mice, compounding an otherwise mild phenotype compared to Shank3ΔC/ΔC. The possible relevance of these findings to neurodevelopmental risk is critically discussed, along with avenues for future research.

Prenatal air pollution, maternal immune activation, and autism spectrum disorder

BACKGROUND

Autism Spectrum Disorder (ASD) risk is highly heritable, with potential additional non-genetic factors, such as prenatal exposure to ambient particulate matter with aerodynamic diameter < 2.5 µm (PM2.5) and maternal immune activation (MIA) conditions. Because these exposures may share common biological effect pathways, we hypothesized that synergistic associations of prenatal air pollution and MIA-related conditions would increase ASD risk in children.

OBJECTIVES

This study examined interactions between MIA-related conditions and prenatal PM2.5 or major PM2.5 components on ASD risk.

METHODS

In a population-based pregnancy cohort of children born between 2001 and 2014 in Southern California, 318,751 mother-child pairs were followed through electronic medical records (EMR); 4,559 children were diagnosed with ASD before age 5. Four broad categories of MIA-related conditions were classified, including infection, hypertension, maternal asthma, and autoimmune conditions. Average exposures to PM2.5 and four PM2.5 components, black carbon (BC), organic matter (OM), nitrate (NO3-), and sulfate (SO42-), were estimated at maternal residential addresses during pregnancy. We estimated the ASD risk associated with MIA-related conditions, air pollution, and their interactions, using Cox regression models to adjust for covariates.

RESULTS

ASD risk was associated with MIA-related conditions [infection (hazard ratio 1.11; 95% confidence interval 1.05-1.18), hypertension (1.30; 1.19-1.42), maternal asthma (1.22; 1.08-1.38), autoimmune disease (1.19; 1.09-1.30)], with higher pregnancy PM2.5 [1.07; 1.03-1.12 per interquartile (3.73 μg/m3) increase] and with all four PM2.5 components. However, there were no interactions of each category of MIA-related conditions with PM2.5 or its components on either multiplicative or additive scales.

CONCLUSIONS

MIA-related conditions and pregnancy PM2.5 were independently associations with ASD risk. There were no statistically significant interactions of MIA conditions and prenatal PM2.5 exposure with ASD risk.

Neurovascular crosstalk and cerebrovascular alterations: an underestimated therapeutic target in autism spectrum disorders

Normal brain development, function, and aging critically depend on unique characteristics of the cerebrovascular system. Growing evidence indicated that cerebrovascular defects can have irreversible effects on the brain, and these defects have been implicated in various neurological disorders, including autism spectrum disorder (ASD). ASD is a neurodevelopmental disorder with heterogeneous clinical manifestations and anatomical changes. While extensive research has focused on the neural abnormalities underlying ASD, the role of brain vasculature in this disorder remains poorly understood. Indeed, the significance of cerebrovascular contributions to ASD has been consistently underestimated. In this work, we discuss the neurovascular crosstalk during embryonic development and highlight recent findings on cerebrovascular alterations in individuals with ASD. We also discuss the potential of vascular-based therapy for ASD. Collectively, these investigations demonstrate that ASD can be considered a neurovascular disease.

A leaky gut dysregulates gene networks in the brain associated with immune activation, oxidative stress, and myelination in a mouse model of colitis

The gut and brain are increasingly linked in human disease, with neuropsychiatric conditions classically attributed to the brain showing an involvement of the intestine and inflammatory bowel diseases (IBDs) displaying an ever-expanding list of neurological comorbidities. To identify molecular systems that underpin this gut-brain connection and thus discover therapeutic targets, experimental models of gut dysfunction must be evaluated for brain effects. In the present study, we examine disturbances along the gut-brain axis in a widely used murine model of colitis, the dextran sodium sulfate (DSS) model, using high-throughput transcriptomics and an unbiased network analysis strategy coupled with standard biochemical outcome measures to achieve a comprehensive approach to identify key disease processes in both colon and brain. We examine the reproducibility of colitis induction with this model and its resulting genetic programs during different phases of disease, finding that DSS-induced colitis is largely reproducible with a few site-specific molecular features. We focus on the circulating immune system as the intermediary between the gut and brain, which exhibits an activation of pro-inflammatory innate immunity during colitis. Our unbiased transcriptomics analysis provides supporting evidence for immune activation in the brain during colitis, suggests that myelination may be a process vulnerable to increased intestinal permeability, and identifies a possible role for oxidative stress and brain oxygenation. Overall, we provide a comprehensive evaluation of multiple systems in a prevalent experimental model of intestinal permeability, which will inform future studies using this model and others, assist in the identification of druggable targets in the gut-brain axis, and contribute to our understanding of the concomitance of intestinal and neuropsychiatric dysfunction.

Viruses and autism: A Bi-mutual cause and effect

Autism spectrum disorder (ASD) is a group of heterogeneous, multi-factorial, neurodevelopmental disorders resulting from genetic and environmental factors interplay. Infection is a significant trigger of autism, especially during the critical developmental period. There is a strong interplay between the viral infection as a trigger and a result of ASD. We aim to highlight the mutual relationship between autism and viruses. We performed a thorough literature review and included 158 research in this review. Most of the literature agreed on the possible effects of the viral infection during the critical period of development on the risk of developing autism, especially for specific viral infections such as Rubella, Cytomegalovirus, Herpes Simplex virus, Varicella Zoster Virus, Influenza virus, Zika virus, and severe acute respiratory syndrome coronavirus 2. Viral infection directly infects the brain, triggers immune activation, induces epigenetic changes, and raises the risks of having a child with autism. At the same time, there is some evidence of increased risk of infection, including viral infections in children with autism, due to lots of factors. There is an increased risk of developing autism with a specific viral infection during the early developmental period and an increased risk of viral infections in children with autism. In addition, children with autism are at increased risk of infection, including viruses. Every effort should be made to prevent maternal and early-life infections and reduce the risk of autism. Immune modulation of children with autism should be considered to reduce the risk of infection.