Peripheral and central inflammation in autism spectrum disorders

The Inflammation-Induced Dysregulation of Reelin Homeostasis Hypothesis of Alzheimer's Disease

Alzheimer's disease (AD) accounts for most dementia cases, but we lack a complete understanding of the mechanisms responsible for the core pathology associated with the disease (e.g., amyloid plaque and neurofibrillary tangles). Inflammation has been identified as a key contributor of AD pathology, with recent evidence pointing towards Reelin dysregulation as being associated with inflammation. Here we describe Reelin signaling and outline existing research involving Reelin signaling in AD and inflammation. Research is described pertaining to the inflammatory and immunological functions of Reelin before we propose a mechanism through which inflammation renders Reelin susceptible to dysregulation resulting in the induction and exacerbation of AD pathology. Based on this hypothesis, it is predicted that disorders of both inflammation (including peripheral inflammation and neuroinflammation) and Reelin dysregulation (including disorders associated with upregulated Reelin expression and disorders of Reelin downregulation) have elevated risk of developing AD. We conclude with a description of AD risk in various disorders involving Reelin dysregulation and inflammation.

Juvenile peripheral LPS exposure overrides female resilience to prenatal VPA effects on adult sociability in mice

Autism spectrum disorder (ASD) exhibits a gender bias, with boys more frequently affected than girls. Similarly, in mouse models induced by prenatal exposure to valproic acid (VPA), males typically display reduced sociability, while females are less affected. Although both males and females exhibit VPA effects on neuroinflammatory parameters, these effects are sex-specific. Notably, females exposed to VPA show increased microglia and astrocyte density during the juvenile period. We hypothesized that these distinct neuroinflammatory patterns contribute to the resilience of females to VPA. To investigate this hypothesis, we treated juvenile animals with intraperitoneal bacterial lipopolysaccharides (LPS), a treatment known to elicit brain neuroinflammation. We thus evaluated the impact of juvenile LPS-induced inflammation on adult sociability and neuroinflammation in female mice prenatally exposed to VPA. Our results demonstrate that VPA-LPS females exhibit social deficits in adulthood, overriding the resilience observed in VPA-saline littermates. Repetitive behavior and anxiety levels were not affected by either treatment. We also evaluated whether the effect on sociability was accompanied by heightened neuroinflammation in the cerebellum and hippocampus. Surprisingly, we observed reduced astrocyte and microglia density in the cerebellum of VPA-LPS animals. These findings shed light on the complex interactions between prenatal insults, juvenile inflammatory stimuli, and sex-specific vulnerability in ASD-related social deficits, providing insights into potential therapeutic interventions for ASD.

Increased monocytes are associated with overweight in children and adolescents with autism spectrum disorder

Introduction

Objective: to investigate the monocyte count and its association with nutritional status in children and adolescents with autism spectrum disorder (ASD). Methods: a cross-sectional study carried out at a Neurodevelopmental Center in the south of Brazil, with 68 ASD patients aged 3 to 18 years. The number of monocytes (per mm3) was determined in blood samples. Nutritional status was defined as BMI-for-age according to WHO standards. The Children's Eating Behaviour Questionnaire and a standard questionnaire to collect sociodemographic and clinical characteristics were administered to caregivers. Comparisons between sociodemographic, clinical, and eating behavior variables were performed with parametric tests. Linear regression was used to test the association between nutritional status and monocyte count. Results: mean age was 8.6 ± 3.3 years, 79 % were males and 66 % were overweight. In the unadjusted regression overweight was associated with higher monocyte counts compared to those non-overweight (B: 64.0; 95 % CI, 13.9 to 114.1; β: 0.30, p = 0.01). This association remained significant after adjustment for the subscale of "emotional overeating" (B: 37.0; 95 % CI, 17.1 to 91.3; β: 0.29; p = 0.02). The variability in monocyte count attributed to overweight was 14 %. Conclusions: overweight is associated with a higher monocyte count in children and adolescents with ASD. Nutritional intervention to control overweight is essential to mitigate the negative impact on inflammatory activity and immune dysfunction in these patients.

Mitochondrial DNA Haplogroup K Is Protective Against Autism Spectrum Disorder Risk in Populations of European Ancestry

OBJECTIVE

Accumulative evidence indicates a critical role of mitochondrial function in autism spectrum disorders (ASD), implying that ASD risk may be linked to mitochondrial dysfunction due to DNA (mtDNA) variations. Although a few studies have explored the association between mtDNA variations and ASD, the role of mtDNA in ASD is still unclear. Here, we aimed to investigate whether mitochondrial DNA haplogroups are associated with the risk of ASD.

METHOD

Two European cohorts and an Ashkenazi Jewish (AJ) cohort were analyzed, including 2,062 ASD patients in comparison with 4,632 healthy controls. DNA samples were genotyped using Illumina HumanHap550/610 and Illumina 1M arrays, inclusive of mitochondrial markers. Mitochondrial DNA (mtDNA) haplogroups were identified from genotyping data using HaploGrep2. A mitochondrial genome imputation pipeline was established to detect mtDNA variants. We conducted a case-control study to investigate potential associations of mtDNA haplogroups and variants with the susceptibility to ASD.

RESULTS

We observed that the ancient adaptive mtDNA haplogroup K was significantly associated with decreased risk of ASD by the investigation of 2 European cohorts including a total of 2,006 cases and 4,435 controls (odds ratio = 0.64, P=1.79 × 10-5), and we replicated this association in an Ashkenazi Jewish (AJ) cohort including 56 cases and 197 controls (odds ratio = 0.35, P = 9.46 × 10-3). Moreover, we demonstrate that the mtDNA variants rs28358571, rs28358584, and rs28358280 are significantly associated with ASD risk. Further expression quantitative trait loci (eQTLs) analysis indicated that the rs28358584 and rs28358280 genotypes are associated with expression levels of nearby genes in brain tissues, suggesting those mtDNA variants may confer risk for ASD via regulation of expression levels of genes encoded by the mitochondrial genome.

CONCLUSION

This study helps to shed light on the contribution of mitochondria in ASD and provides new insights into the genetic mechanism underlying ASD, suggesting the potential involvement of mtDNA-encoded proteins in the development of ASD.

Altered motor learning and coordination in mouse models of autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with increasing prevalence. Over 1,000 risk genes have now been implicated in ASD, suggesting diverse etiology. However, the diagnostic criteria for the disorder still comprise two major behavioral domains - deficits in social communication and interaction, and the presence of restricted and repetitive patterns of behavior (RRBs). The RRBs associated with ASD include both stereotyped repetitive movements and other motor manifestations including changes in gait, balance, coordination, and motor skill learning. In recent years, the striatum, the primary input center of the basal ganglia, has been implicated in these ASD-associated motor behaviors, due to the striatum's role in action selection, motor learning, and habit formation. Numerous mouse models with mutations in ASD risk genes have been developed and shown to have alterations in ASD-relevant behaviors. One commonly used assay, the accelerating rotarod, allows for assessment of both basic motor coordination and motor skill learning. In this corticostriatal-dependent task, mice walk on a rotating rod that gradually increases in speed. In the extended version of this task, mice engage striatal-dependent learning mechanisms to optimize their motor routine and stay on the rod for longer periods. This review summarizes the findings of studies examining rotarod performance across a range of ASD mouse models, and the resulting implications for the involvement of striatal circuits in ASD-related motor behaviors. While performance in this task is not uniform across mouse models, there is a cohort of models that show increased rotarod performance. A growing number of studies suggest that this increased propensity to learn a fixed motor routine may reflect a common enhancement of corticostriatal drive across a subset of mice with mutations in ASD-risk genes.

Adolescent swimming exercise following maternal valproic acid treatment improves cognition and reduces stress-related symptoms in offspring mice: Role of sex and brain cytokines

Valproic acid (VPA) treatment during pregnancy is a risk factor for developing autism spectrum disorder, cognitive deficits, and stress-related disorders in children. No effective therapeutic strategies are currently approved to treat or manage core symptoms of autism. Active lifestyles and physical activity are closely associated with health and quality of life during childhood and adulthood. This study aimed to evaluate whether swimming exercise during adolescence can prevent the development of cognitive dysfunction and stress-related disorders in prenatally VPA-exposed mice offspring. Pregnant mice received VPA, afterwards, offspring were subjected to swimming exercise. We assessed neurobehavioral performances and inflammatory cytokines (interleukin-(IL)6, tumor-necrosis-factor-(TNF)α, interferon-(IFN)γ, and IL-17A) in the hippocampus and prefrontal cortex of offspring. Prenatal VPA treatment increased anxiety-and anhedonia-like behavior and decreased social behavior in male and female offspring. Prenatal VPA exposure also increased behavioral despair and reduced working and recognition memory in male offspring. Although prenatal VPA increased hippocampal IL-6 and IFN-γ, and prefrontal IFN-γ and IL-17 in males, it only increased hippocampal TNF-α and IFN-γ in female offspring. Adolescent exercise made VPA-treated male and female offspring resistant to anxiety-and anhedonia-like behavior in adulthood, whereas it only made VPA-exposed male offspring resistant to behavioral despair, social and cognitive deficits in adulthood. Exercise reduced hippocampal IL-6, TNF-α, IFN-γ, and IL-17, and prefrontal IFN-γ and IL-17 in VPA-treated male offspring, whereas it reduced hippocampal TNF-α and IFN-γ in VPA-treated female offspring. This study suggests that adolescent exercise may prevents the development of stress-related symptoms, cognitive deficits, and neuroinflammation in prenatally VPA-exposed offspring mice.

Analysis of potential biomarkers and immune infiltration in autism based on bioinformatics analysis

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder caused by both environmental and genetic factors. However, its etiology and pathogenesis remain unclear. The purpose of this study was to establish an immune-related diagnostic model for ASD using bioinformatics methods and to identify ASD biomarkers. Two ASD datasets, GSE18123 and GSE29691, were integrated into the gene expression Database to eliminate batch effects. 41 differentially expressed genes were identified by microarray data linear model (limma package). Based on the results of the immune infiltration analysis, we speculated that neutrophils, B cells naive, CD8+ T cells, and Tregs are potential core immune cells in ASD and participate in the occurrence of ASD. Finally, the differential genes and immune infiltration in ASD and non-ASD patients were compared, and the most relevant genes were selected to construct the first immune correlation prediction model of ASD. After the calculation, the model exhibited better accuracy. The calculations show that the model has good accuracy.

Autism Spectrum Disorders: A Recent Update on Targeting Inflammatory Pathways with Natural Anti-Inflammatory Agents

Autism spectrum disorder (ASD) is a heterogeneous category of developmental psychiatric disorders which is characterized by inadequate social interaction, less communication, and repetitive phenotype behavior. ASD is comorbid with various types of disorders. The reported prevalence is 1% in the United Kingdom, 1.5% in the United States, and ~0.2% in India at present. The natural anti-inflammatory agents on brain development are linked to interaction with many types of inflammatory pathways affected by genetic, epigenetic, and environmental variables. Inflammatory targeting pathways have already been linked to ASD. However, these routes are diluted, and new strategies are being developed in natural anti-inflammatory medicines to treat ASD. This review summarizes the numerous preclinical and clinical studies having potential protective effects and natural anti-inflammatory agents on the developing brain during pregnancy. Inflammation during pregnancy activates the maternal infection that likely leads to the development of neuropsychiatric disorders in the offspring. The inflammatory pathways have been an effective target for the subject of translational research studies on ASD.

Simultaneous Antagonism at H3R/D2R/D3R Reduces Autism-like Self-Grooming and Aggressive Behaviors by Mitigating MAPK Activation in Mice

Dysregulation in brain neurotransmitters underlies several neuropsychiatric disorders, e.g., autism spectrum disorder (ASD). Also, abnormalities in the extracellular-signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) pathway pave the way for neuroinflammation, neurodegeneration, and altered learning phenotype in ASD. Therefore, the effects of chronic systemic administration of the multiple-targeting antagonist ST-713 at the histamine H3 receptor (H3R) and dopamine D2/D3 receptors (D2/D3R) on repetitive self-grooming, aggressive behaviors, and abnormalities in the MAPK pathway in BTBR T + Itpr3tf/J (BTBR) mice were assessed. The results showed that ST-713 (2.5, 5, and 10 mg/kg, i.p.) mitigated repetitive self-grooming and aggression in BTBR mice (all p < 0.05), and the ameliorative effects of the most promising dose of ST-713 (5 mg/kg, i.p.) on behaviors were completely abrogated by co-administration of the H3R agonist (R)-α-methylhistamine or the anticholinergic drug scopolamine. Moreover, the elevated levels of several MAPK pathway proteins and induced proinflammatory markers such as tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), and IL-6 were significantly suppressed following chronic administration of ST-713 (5 mg/kg, i.p.) (all p < 0.01). Furthermore, ST-713 significantly increased the levels of histamine and dopamine in hippocampal tissue of treated BTBR mice (all p < 0.01). The current observations signify the potential role of such multiple-targeting compounds, e.g., ST-713, in multifactorial neurodevelopmental disorders such as ASD.

Photobiomodulation Attenuated Cognitive Dysfunction and Neuroinflammation in a Prenatal Valproic Acid-Induced Autism Spectrum Disorder Mouse Model

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by social communication and interaction disorders, as well as repetitive and restrictive behaviors. To date, no effective treatment strategies have been identified. However, photobiomodulation (PBM) is emerging as a promising treatment for neurological and neuropsychiatric disorders. We used mice exposed to valproic acid (VPA) as a model of ASD and found that pathological behavioral and histological changes that may have been induced by VPA were attenuated by PBM treatment. Pregnant mice that had been exposed to VPA were treated with PBM three times. Thereafter, we evaluated the offspring for developmental disorders, motor function, hyperactivity, repetitive behaviors, and cognitive impairment. PBM attenuated many of the pathological behaviors observed in the VPA-induced ASD mouse model. In addition, pathophysiological analyses confirmed that the increase in activated microglia and astrocytes observed in the VPA-induced ASD mouse model was attenuated by PBM treatment. This suggests that PBM can counteract the behavioral changes caused by neuroinflammation in ASD. Therefore, our data show that PBM has therapeutic potential and may reduce the prevalence of neurodevelopmental disorders such as ASD.

At the crux of maternal immune activation: Viruses, microglia, microbes, and IL-17A

Inflammation during prenatal development can be detrimental to neurodevelopmental processes, increasing the risk of neuropsychiatric disorders. Prenatal exposure to maternal viral infection during pregnancy is a leading environmental risk factor for manifestation of these disorders. Preclinical animal models of maternal immune activation (MIA), established to investigate this link, have revealed common immune and microbial signaling pathways that link mother and fetus and set the tone for prenatal neurodevelopment. In particular, maternal intestinal T helper 17 cells, educated by endogenous microbes, appear to be key drivers of effector IL-17A signals capable of reaching the fetal brain and causing neuropathologies. Fetal microglial cells are particularly sensitive to maternally derived inflammatory and microbial signals, and they shift their functional phenotype in response to MIA. Resulting cortical malformations and miswired interneuron circuits cause aberrant offspring behaviors that recapitulate core symptoms of human neurodevelopmental disorders. Still, the popular use of "sterile" immunostimulants to initiate MIA has limited translation to the clinic, as these stimulants fail to capture biologically relevant innate and adaptive inflammatory sequelae induced by live pathogen infection. Thus, there is a need for more translatable MIA models, with a focus on relevant pathogens like seasonal influenza viruses.

Aberrant IL-17 Levels in Rodent Models of Autism Spectrum Disorder: A Systematic Review

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterised by stereotyped behaviours, specific interests, and impaired communication skills. Elevated levels of pro-inflammatory cytokines, such as interleukin-17A (IL-17A or IL-17), have been implicated as part of immune alterations that may contribute to this outcome. In this context, rodent models have helped elucidate the role of T-cell activation and IL-17 secretion in the pathogenesis of ASD. Regarding the preclinical findings, the data available is contradictory in offspring but not in the pregnant dams, pointing to IL-17 as one of the main drivers of altered behaviour in some models ASD, whilst there are no alterations described in IL-17 levels in others. To address this gap in the literature, a systematic review of altered IL-17 levels in rodent models of ASD was conducted. In total, 28 studies that explored IL-17 levels were included and observed that this cytokine was generally increased among the different models of ASD. The data compiled in this review can help the choice of animal models to study the role of cytokines in the development of ASD, seeking a parallel with immune alterations observed in individuals with this condition.

TNFAIP3 Reduction-of-Function Drives Female Infertility and CNS Inflammation

Women with autoimmune and inflammatory aetiologies can exhibit reduced fecundity. TNFAIP3 is a master negative regulator of inflammation, and has been linked to many inflammatory conditions by genome wide associations studies, however its role in fertility remains unknown. Here we show that mice harbouring a mild Tnfaip3 reduction-of-function coding variant (Tnfaip3^I325N) that reduces the threshold for inflammatory NF-κB activation, exhibit reduced fecundity. Sub-fertility in Tnfaip3^I325N mice is associated with irregular estrous cycling, low numbers of ovarian secondary follicles, impaired mammary gland development and insulin resistance. These pathological features are associated with infertility in human subjects. Transplantation of Tnfaip3^I325N ovaries, mammary glands or pancreatic islets into wild-type recipients rescued estrous cycling, mammary branching and hyperinsulinemia respectively, pointing towards a cell-extrinsic hormonal mechanism. Examination of hypothalamic brain sections revealed increased levels of microglial activation with reduced levels of luteinizing hormone. TNFAIP3 coding variants may offer one contributing mechanism for the cause of sub-fertility observed across otherwise healthy populations as well as for the wide variety of auto-inflammatory conditions to which TNFAIP3 is associated. Further, TNFAIP3 represents a molecular mechanism that links heightened immunity with neuronal inflammatory homeostasis. These data also highlight that tuning-up immunity with TNFAIP3 comes with the potentially evolutionary significant trade-off of reduced fertility.

Behavioral, Anti-Inflammatory, and Neuroprotective Effects of a Novel FPR2 Agonist in Two Mouse Models of Autism

Autism spectrum disorders (ASD) are a group of heterogeneous neurodevelopmental conditions characterized by social deficits, repetitive stereotyped behaviors, and altered inflammatory responses. Accordingly, children with ASD show decreased plasma levels of lipoxin A4 (LXA4), a mediator involved in the resolution of inflammation, which is the endogenous ligand of the formyl peptide receptor 2 (FPR2). To investigate the role of FPR2 in ASDs, we have used a new ureidopropanamide derivative able to activate the receptor, named MR-39. The effects of MR-39 (10 mg/kg, for 8 days) on hippocampal pro-inflammatory profile, neuronal plasticity, and social behavior were evaluated in two validated animal models of ASD: BTBR mouse strain and mice prenatally exposed to valproic acid (VPA). Primary cultures of hippocampal neurons from BTBR mice were also used to evaluate the effect of MR-39 on neurite elongation. Our results show that MR-39 treatment reduced several inflammatory markers, restored the low expression of LXA4, and modulated FPR2 expression in hippocampal tissues of both ASD animal models. These findings were accompanied by a significant positive effect of MR-39 on social behavioral tests of ASD mice. Finally, MR-39 stimulates neurite elongation in isolated hippocampal neurons of BTBR mice. In conclusion, these data indicate FPR2 as a potential target for an innovative therapeutical approach for the cure of ASD.

Neuronal Cell Adhesion Molecules May Mediate Neuroinflammation in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by restrictive and repetitive behaviors, alongside deficits in social interaction and communication. The etiology of ASD is largely unknown but is strongly linked to genetic variants in neuronal cell adhesion molecules (CAMs), cell-surface proteins that have important roles in neurodevelopment. A combination of environmental and genetic factors are believed to contribute to ASD pathogenesis. Inflammation in ASD has been identified as one of these factors, demonstrated through the presence of proinflammatory cytokines, maternal immune activation, and activation of glial cells in ASD brains. Glial cells are the main source of cytokines within the brain and, therefore, their activity is vital in mediating inflammation in the central nervous system. However, it is unclear whether the aforementioned neuronal CAMs are involved in modulating neuroimmune signaling or glial behavior. This review aims to address the largely unexplored role that neuronal CAMs may play in mediating inflammatory cascades that underpin neuroinflammation in ASD, primarily focusing on the Notch, nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPK) cascades. We will also evaluate the available evidence on how neuronal CAMs may influence glial activity associated with inflammation. This is important when considering the impact of environmental factors and inflammatory responses on ASD development. In particular, neural CAM1 (NCAM1) can regulate NF-κB transcription in neurons, directly altering proinflammatory signaling. Additionally, NCAM1 and contactin-1 appear to mediate astrocyte and oligodendrocyte precursor proliferation which can alter the neuroimmune response. Importantly, although this review highlights the limited information available, there is evidence of a neuronal CAM regulatory role in inflammatory signaling. This warrants further investigation into the role other neuronal CAM family members may have in mediating inflammatory cascades and would advance our understanding of how neuroinflammation can contribute to ASD pathology.

Oxidative Stress in Autism Spectrum Disorder-Current Progress of Mechanisms and Biomarkers

Autism spectrum disorder (ASD) is a type of neurodevelopmental disorder that has been diagnosed in an increasing number of children around the world. Existing data suggest that early diagnosis and intervention can improve ASD outcomes. However, the causes of ASD remain complex and unclear, and there are currently no clinical biomarkers for autism spectrum disorder. More mechanisms and biomarkers of autism have been found with the development of advanced technology such as mass spectrometry. Many recent studies have found a link between ASD and elevated oxidative stress, which may play a role in its development. ASD is caused by oxidative stress in several ways, including protein post-translational changes (e.g., carbonylation), abnormal metabolism (e.g., lipid peroxidation), and toxic buildup [e.g., reactive oxygen species (ROS)]. To detect elevated oxidative stress in ASD, various biomarkers have been developed and employed. This article summarizes recent studies about the mechanisms and biomarkers of oxidative stress. Potential biomarkers identified in this study could be used for early diagnosis and evaluation of ASD intervention, as well as to inform and target ASD pharmacological or nutritional treatment interventions.

Neuroinflammation in Autism and Supplementation Based on Omega-3 Polyunsaturated Fatty Acids: A Narrative Review

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder characterized by persistent deficits in social communication and social interaction across multiple contexts and restricted, repetitive patterns of behavior, interests and activities. The maternal status of polyunsaturated fatty acids (PUFA) regulates microglial activity and neuroinflammatory pathways during a child's brain development. In children with ASD, the metabolism of PUFA is thought to be deficient or abnormal, leading to increased production of proinflammatory cytokines, increased oxidative stress and an imbalance in the formation and action of neurotransmitters. In addition, nutritional deficits in omega-3 PUFA may affect gut microbiota and contribute to ASD by the gut-brain axis. The aim of this study was to review the possible role of neuroinflammation in ASD development and the effect of omega-3 PUFA supplementation in children with ASD. Due to a wide heterogeneity across RCTs, no definitive conclusion about omega-3 PUFA effects in ASD can be drawn. Supplementation with PUFA could be considered as one of the aspects in regulating the biological status of the organism and could provide added value to standard medical and psychological interventions for reducing behavioral deficits.

The Role of Preclinical Models in Creatine Transporter Deficiency: Neurobiological Mechanisms, Biomarkers and Therapeutic Development

Creatine (Cr) Transporter Deficiency (CTD) is an X-linked metabolic disorder, mostly caused by missense mutations in the SLC6A8 gene and presenting with intellectual disability, autistic behavior, and epilepsy. There is no effective treatment for CTD and patients need lifelong assistance. Thus, the research of novel intervention strategies is a major scientific challenge. Animal models are an excellent tool to dissect the disease pathogenetic mechanisms and drive the preclinical development of therapeutics. This review illustrates the current knowledge about Cr metabolism and CTD clinical aspects, with a focus on mainstay diagnostic and therapeutic options. Then, we discuss the rodent models of CTD characterized in the last decade, comparing the phenotypes expressed within clinically relevant domains and the timeline of symptom development. This analysis highlights that animals with the ubiquitous deletion/mutation of SLC6A8 genes well recapitulate the early onset and the complex pathological phenotype of the human condition. Thus, they should represent the preferred model for preclinical efficacy studies. On the other hand, brain- and cell-specific conditional mutants are ideal for understanding the basis of CTD at a cellular and molecular level. Finally, we explain how CTD models might provide novel insight about the pathogenesis of other disorders, including cancer.

An Epigenetically Distinct Subset of Children With Autism Spectrum Disorder Resulting From Differences in Blood Cell Composition

Background: Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that often involves impaired cognition, communication difficulties and restrictive, repetitive behaviors. ASD is extremely heterogeneous both clinically and etiologically, which represents one of the greatest challenges in studying the molecular underpinnings of ASD. While hundreds of ASD-associated genes have been identified that confer varying degrees of risk, no single gene variant accounts for >1% of ASD cases. Notably, a large number of ASD-risk genes function as epigenetic regulators, indicating potential epigenetic dysregulation in ASD. As such, we compared genome-wide DNA methylation (DNAm) in the blood of children with ASD (n = 265) to samples from age- and sex-matched, neurotypical controls (n = 122) using the Illumina Infinium HumanMethylation450 arrays. Results: While DNAm patterns did not distinctly separate ASD cases from controls, our analysis identified an epigenetically unique subset of ASD cases (n = 32); these individuals exhibited significant differential methylation from both controls than the remaining ASD cases. The CpG sites at which this subset was differentially methylated mapped to known ASD risk genes that encode proteins of the nervous and immune systems. Moreover, the observed DNAm differences were attributable to altered blood cell composition, i.e., lower granulocyte proportion and granulocyte-to-lymphocyte ratio in the ASD subset, as compared to the remaining ASD cases and controls. This ASD subset did not differ from the rest of the ASD cases in the frequency or type of high-risk genomic variants. Conclusion: Within our ASD cohort, we identified a subset of individuals that exhibit differential methylation from both controls and the remaining ASD group tightly associated with shifts in immune cell type proportions. This is an important feature that should be assessed in all epigenetic studies of blood cells in ASD. This finding also builds on past reports of changes in the immune systems of children with ASD, supporting the potential role of altered immunological mechanisms in the complex pathophysiology of ASD. The discovery of significant molecular and immunological features in subgroups of individuals with ASD may allow clinicians to better stratify patients, facilitating personalized interventions and improved outcomes.

Association between Viral Infections and Risk of Autistic Disorder: An Overview

Autism spectrum disorder (ASD) is a neurodevelopmental condition of the central nervous system (CNS) that presents with severe communication problems, impairment of social interactions, and stereotypic behaviours. Emerging studies indicate possible associations between viral infections and neurodegenerative and neurobehavioural conditions including autism. Viral infection during critical periods of early in utero neurodevelopment may lead to increased risk of autism in the offspring. This review is aimed at highlighting the association between viral infections, including viruses similar to COVID-19, and the aetiology of autism. A literature search was conducted using Pubmed, Ovid/Medline, and Google Scholar database. Relevant search terms included "rubella and autism", "cytomegalovirus and autism", "influenza virus and autism", "Zika virus and autism", "COVID-19 and autism". Based on the search terms, a total of 141 articles were obtained and studies on infants or children with congenital or perinatal viral infection and autistic behaviour were evaluated. The possible mechanisms by which viral infections could lead to autism include direct teratogenic effects and indirect effects of inflammation or maternal immune activation on the developing brain. Brain imaging studies have shown that the ensuing immune response from these viral infections could lead to disruption of the development of brain regions and structures. Hence, long-term follow up is necessary for infants whose mothers report an inflammatory event due to viral infection at any time during pregnancy to monitor for signs of autism. Research into the role of viral infection in the development of ASD may be one avenue of improving ASD outcomes in the future. Early screening and diagnosis to detect, and maybe even prevent ASD are essential to reduce the burden of this condition.

Assessment of autism-relevant behaviors in C57BKS/J leptin receptor deficient mice

Gestational diabetes mellitus (GDM) was associated with greater autism risk in epidemiological studies. Disrupted leptin signaling may contribute to their coincidence, as it is found in both disorders. Given this we examined leptin receptor (Lepr) deficient (BKS.Cg-Dock7^m +/+ Lepr^db/J diabetic (db)) heterozygous (db/+) mice for autism-relevant behaviors. BKS db/+ females are lean with normal blood glucose, but they develop GDM while pregnant. We hypothesized BKS db/+ offspring might exhibit physiological and behavior traits consistent with autism. Adolescent body weight, fasting blood glucose, serum corticosterone, social preferences, self-grooming, marble burying, social dominance and cognitive flexibility of BKS db/+ mice was compared to C57BLKS/J (BKS) and C57BL/6J (BL6) mice. Male db/+ weighed more and had higher blood glucose and corticosterone relative to BL6, but not BKS mice. Also, male db/+ lacked social interaction preference, explored arenas less, and buried more marbles than BL6, but not BKS males. Male and female db/+ were more dominant and made more mistakes in water T-mazes locating a sunken platform after its position was reversed than BL6, but not BKS mice. Overall BKS db/+, particularly males, exhibited some autism-like social deficits and restrictive-repetitive behaviors relative to BL6, but BKS strain contributions to BKS db/+ behaviors were evident. Since BKS db/+ and BKS behavioral and physiological phenotypes are already so similar, it will be difficult to use these models in studies designed to detect contributions of fetal GDM exposures to offspring behaviors.

Dysregulation of Ki-67 Expression in T Cells of Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by behavioral abnormalities such as impairments in social function and deficits in communication. The etiology of autism is unknown in most cases, but many studies have pointed towards the immune system as a causative agent in autism. Specific studies implicated lymphocytes, natural killer (NK) cells, monocytes, cytokines, and specific transcription factors in the development of ASD. The protein Ki-67 is n expressed in the proliferating cells and is used as a tool in several disorders. Ki-67 plays a crucial role in many neurological diseases. However, Ki-67 role in ASD is not fully understood. In this study, we investigated the possible role of Ki-67 expression in autistic children. We compared Ki-67 production in CD3+, CD4+, CD8+, CXCR4+, CXCR7+, CD45R+, HLA-DR+, GATA3+, Helios+, and FOXP3+ peripheral blood mononuclear cells (PBMCs) in autistic children to typically developing (TD) controls using immunofluorescence staining. We also determined Ki-67 mRNA levels in PBMCs using RT–PCR. The results revealed that autistic children had significantly increased numbers of CD3+Ki-67+, CD4+Ki-67+, CD8+Ki-67+, CXCR4+Ki-67+, CXCR7+Ki-67+, CD45R+Ki-67+, HLA-DR+Ki-67+, CXCR4+GATA3+, GATA3+Ki-67+ cells and decreased Helios+Ki-67+ and FOXP3+Ki-67+ cells compared with TD controls. In addition, the autistic children showed upregulation of Ki-67 mRNA levels compared with TD controls. Further studies need to be carried out to assess the exact role of Ki-67 and its therapeutic potential in ASD.

Early estradiol exposure masculinizes disease-relevant behaviors in female mice

Most psychiatric disorders show a sex bias in incidence, symptomatology, and/or response to treatment. Males are more susceptible to neurodevelopmental disorders including autism spectrum disorder and attention-deficit activity disorder, while women are more prone to major depressive disorder and anxiety disorders after puberty. A striking difference between males and females in humans and other mammals is that males undergo a process of brain masculinization due to the early exposure to gonadal hormones. In rodents, this developmental organization of the brain is essential for adult males to express the appropriate sexual behaviors in the presence of a receptive female. Our goal was to determine whether this process of brain masculinization influences behaviors relevant to psychiatric disorders. To this aim, we studied sex differences and the effect of neonatal 17β-estradiol benzoate treatment of female mice on different disease-relevant behaviors. Our analysis includes postnatal behavior, juvenile play, and adult tests for sociability, repetitive behaviors, anxiety, and depression. Our results show that the sex differences observed in exploration, repetitive behaviors, and depression-related behaviors are largely reduced when females are neonatally treated with 17β-estradiol benzoate. These results suggest a role of neonatal sex steroids in the development of disease-relevant behaviors and provide evidence supporting a role for perinatal exposure to estrogens and androgens on the development and manifestation of psychiatric disorders.

Sex Differences in the Gut-Brain Axis: Implications for Mental Health

PURPOSE OF REVIEW

The purpose of this article is to highlight how sex differences in the gut-brain axis may contribute to the discrepancies in incidence of neurodevelopmental, psychiatric, and neurodegenerative disorders between females and males. We focus on autism spectrum disorder, psychotic disorders, stress and anxiety disorders, depression, Alzheimer's disease, and Parkinson's disease and additionally discuss the comorbidity between inflammatory bowel disorder and mental health disorders.

RECENT FINDINGS

Human and animal studies show that sex may modify the relationship between the gut or immune system and brain and behavior. Sex also appears to modify the effect of microbial treatments such as probiotics and antibiotics on brain and behavior. There is emerging evidence that assessing the role of sex in the gut-brain axis may help elucidate the etiology of and identify effective treatments for neurodevelopmental, psychiatric, and neurodegenerative disorders.

Could autism spectrum disorders be a risk factor for COVID-19?

The coronavirus SARS-CoV-2 pandemia is infecting millions of people and some studies relate conditions that might increase the risk of developing a fatal course for the disease, such as diabetes, cardiovascular diseases and obesity. In COVID-19 physiopathology, one of the main inflammation mechanisms is the "cytokine storm", causing a pro-inflammatory state, related to cardiac and pulmonary damage. There is also a less effective role of lymphocyte B and T in the humoral immunity due to the reduction of their proliferative response. The physiopathology of ASD (Autism Spectrum Disorder) involves several modifications at the genetic and at the immune level, such as the increase of inflammatory cytokines and abnormal immune response in several levels. We hypothesize that ASD could be a risk-factor as the other conditions are.

Immune Modulatory Treatments for Autism Spectrum Disorder

Several lines of evidence from family history studies, immunogenetics, maternal immune activation, neuroinflammation, and systemic inflammation support an immune subtype of autism spectrum disorder (ASD). Current Food and Drug Administration-approved medications for ASD do not address the underlying pathophysiology of ASD, have not consistently been shown to address the core symptoms of ASD, and are currently only approved for treating irritability in children and adolescents. In this article, we review the immune modulatory effects of the 2 currently Food and Drug Administration-approved treatments for ASD. We then provide an overview of current data on emerging treatments for ASD from multiple fields of medicine with immune modulatory effects. Although further research is needed to more clearly establish the efficacy and safety of immune modulatory treatments, early data on repurposing medications used to treat systemic inflammation for ASD demonstrate potential benefit and further research is warranted.

Endocrine Insights into the Pathophysiology of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a class of neurodevelopmental disorders that affects males more frequently than females. Numerous genetic and environmental risk factors have been suggested to contribute to the development of ASD. However, no one factor can adequately explain either the frequency of the disorder or the male bias in its prevalence. Gonadal, thyroid, and glucocorticoid hormones all contribute to normal development of the brain, hence perturbations in either their patterns of secretion or their actions may constitute risk factors for ASD. Environmental factors may contribute to ASD etiology by influencing the development of neuroendocrine and neuroimmune systems during early life. Emerging evidence suggests that the placenta may be particularly important as a mediator of the actions of environmental and endocrine risk factors on the developing brain, with the male being particularly sensitive to these effects. Understanding how various risk factors integrate to influence neural development may facilitate a clearer understanding of the etiology of ASD.

Effects of immunization with heat-killed Mycobacterium vaccae on autism spectrum disorder-like behavior and epileptogenesis in a rat model of comorbid autism and epilepsy

Autism spectrum disorders (ASDs) and epilepsy are often comorbid. The basis for this co-occurrence remains unknown; however, inflammatory stressors during development are a shared risk factor. To explore this association, we tested the effect of repeated immunizations using a heat-killed preparation of the stress-protective immunoregulatory microbe Mycobacterium vaccae NCTC 11,659 (M. vaccae) on the behavioral and epileptogenic consequences of the combined stress-terbutaline (ST) rat model of ASD-like behavior/epilepsy. Repeated immunization of the dam with M. vaccae during pregnancy, followed by immunization of the pups after terbutaline injections, prevented the expression of ASD-like behavior but did not appear to protect against, and may have even enhanced, the spontaneous epileptogenic effects of ST. Maternal M. vaccae injections transferred an anti-inflammatory immunophenotype to offspring, and repeated injections across development prevented ST-induced increases in microglial density at early developmental time points in a region-specific manner. Despite epidemiological comorbidity between ASD/epileptic conditions and shared environmental risk factors, our results suggest that the expression of ASD-like behaviors, but perhaps not epileptogenesis, is sensitive to early anti-inflammatory intervention. These data provide support for the exploration of immunoregulatory strategies to prevent the negative neurodevelopmental behavioral effects of stressors during early critical periods.

Elevated serum neurofilament light chain in children autism spectrum disorder: A case control study

OBJECTIVE

We aimed to assess serum neurofilament light chain (sNfL) levels in autism spectrum disorder (ASD) and to investigate whether they are related to the severity of disease.

METHODS

The cohorts consisted of 166 children aged 3-8 (83 children diagnosed with ASD and 83 children with typically-developing). sNfL were analyzed using Single Molecule Array (Simoa) technology. ASD symptom severity was assessed according to the Chinese version of the Childhood Autism Rating Scale (CARS) score.

RESULTS

The mean age of those included ASD was 5.1 years (standard deviations [S.D.]: 1.7) and 78.3 % were boys. The mean (SD) sNfL concentrations were significantly (P < 0.001) higher in ASD than in TP children (10.2[5.0] pg/mL and 7.1[3.2]pg/mL). For each 1 pg/mL increase of sNfL, the risk of ASD would increase by 19 % (with the OR _unadjusted of 1.19 [95 % CI 1.10-1.29], P < 0.001) and 11 % (with the OR _adjusted of 1.11 [1.03-1.23], P < 0.001), respectively. sNfL concentrations in children with severe ASD were higher than in those children with mild-to-moderate ASD (12.4[5.1] pg/mL vs. 8.3[4.2]pg/mL; P < 0.001). Among ASD cases, each 1 pg/mL increase of sNfL is associated with 20 % higher unadjusted or 11 % higher adjusted odds, respectively, of severe (vs. mild-to-moderate) ASD.

CONCLUSIONS

The data showed that sNfL was elevated in ASD and related to symptom severity, suggesting that sNfL may play a role in ASD progression.

Role of Neuroinflammation in Autism Spectrum Disorder and the Emergence of Brain Histaminergic System. Lessons Also for BPSD?

Many behavioral and psychological symptoms of dementia (BPSD) share similarities in executive functioning and communication deficits with those described in several neuropsychiatric disorders, including Alzheimer's disease (AD), epilepsy, schizophrenia (SCH), and autism spectrum disorder (ASD). Numerous studies over the last four decades have documented altered neuroinflammation among individuals diagnosed with ASD. The purpose of this review is to examine the hypothesis that central histamine (HA) plays a significant role in the regulation of neuroinflammatory processes of microglia functions in numerous neuropsychiatric diseases, i.e., ASD, AD, SCH, and BPSD. In addition, this review summarizes the latest preclinical and clinical results that support the relevance of histamine H1-, H2-, and H3-receptor antagonists for the potential clinical use in ASD, SCH, AD, epilepsy, and BPSD, based on the substantial symptomatic overlap between these disorders with regards to cognitive dysfunction. The review focuses on the histaminergic neurotransmission as relevant in these brain disorders, as well as the effects of a variety of H3R antagonists in animal models and in clinical studies.

Effects of air pollution on the nervous system and its possible role in neurodevelopmental and neurodegenerative disorders

Recent extensive evidence indicates that air pollution, in addition to causing respiratory and cardiovascular diseases, may also negatively affect the brain and contribute to central nervous system diseases. Air pollution is comprised of ambient particulate matter (PM) of different sizes, gases, organic compounds, and metals. An important contributor to PM is represented by traffic-related air pollution, mostly ascribed to diesel exhaust (DE). Epidemiological and animal studies have shown that exposure to air pollution may be associated with multiple adverse effects on the central nervous system. In addition to a variety of behavioral abnormalities, the most prominent effects caused by air pollution are oxidative stress and neuro-inflammation, which are seen in both humans and animals, and are supported by in vitro studies. Among factors which can affect neurotoxic outcomes, age is considered most relevant. Human and animal studies suggest that air pollution may cause developmental neurotoxicity, and may contribute to the etiology of neurodevelopmental disorders, including autism spectrum disorder. In addition, air pollution exposure has been associated with increased expression of markers of neurodegenerative disease pathologies, such as alpha-synuclein or beta-amyloid, and may thus contribute to the etiopathogenesis of neurodegenerative diseases, particularly Alzheimer's disease and Parkinson's disease.

Biomarker Exploration in Human Peripheral Blood Mononuclear Cells for Monitoring Sulforaphane Treatment Responses in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is one of the most common neurodevelopmental disorders with no drugs treating the core symptoms and no validated biomarkers for clinical use. The multi-functional phytochemical sulforaphane affects many of the biochemical abnormalities associated with ASD. We investigated potential molecular markers from three ASD-associated physiological pathways that can be affected by sulforaphane: redox metabolism/oxidative stress; heat shock response; and immune dysregulation/inflammation, in peripheral blood mononuclear cells (PBMCs) from healthy donors and patients with ASD. We first analyzed the mRNA levels of selected molecular markers in response to sulforaphane ex vivo treatment in PBMCs from healthy donors by real-time quantitative PCR. All of the tested markers showed quantifiability, accuracy and reproducibility. We then compared the expression levels of those markers in PBMCs taken from ASD patients in response to orally-delivered sulforaphane. The mRNA levels of cytoprotective enzymes (NQO1, HO-1, AKR1C1), and heat shock proteins (HSP27 and HSP70), increased. Conversely, mRNA levels of pro-inflammatory markers (IL-6, IL-1β, COX-2 and TNF-α) decreased. Individually none is sufficiently specific or sensitive, but when grouped by function as two panels, these biomarkers show promise for monitoring pharmacodynamic responses to sulforaphane in both healthy and autistic humans, and providing guidance for biomedical interventions.

Upregulation of enzymatic antioxidants in CD4+ T cells of autistic children

Autism spectrum disorder (ASD) is a neurodevelopmental disorder which begins in early childhood and presents itself with characteristic symptoms such as repetitive behavioral patterns and problems in speech/social interactions. Adaptive immune system is thought to be involved in the etiology of ASD. T cells orchestrate amplification of inflammation through release of inflammatory mediators; however, antioxidant defenses have not been evaluated in CD4⁺ T cells of ASD subjects. In this study we evaluated intracellular enzymatic antioxidant potential through measurement of major antioxidant enzymes (SOD, GPx, and GR) in ASD subjects and typically developing control (TDC) children and further assessed its role in modulation of inflammation. Our data reveal that there is an increase in antioxidant potential (SOD, GPx, GR) in CD4⁺ T cells of ASD subjects as compared to TDC children at both protein and activity level. Further, this antioxidant increase was associated with upregulated IL-17A levels in CD4⁺ T cells. This was corroborated by oxidant treatment in vitro. Pretreatment with oxidant, H₂O₂ led to attenuation of IL-17A levels along with increased oxidative stress in stimulated CD4⁺ T cells from ASD subjects. These data reveal that antioxidant play an essential role in modulation of inflammatory potential in CD4⁺ T cells of ASD subjects.

Dysregulation in IL-6 receptors is associated with upregulated IL-17A related signaling in CD4+ T cells of children with autism

Autism spectrum disorder (ASD) is a heterogeneous syndrome characterized by dysregulations in speech and social interactions as well as repetitive and stereotypical behavioral patterns in which immune system plays a significant role. IL-6, an essential cytokine for polarization of Th0 cells into Th17 cells has been demonstrated to be crucial in the etiology of ASD in past studies both in humans and mice. Th17 cells are also believed to be central players in the pathogenesis of ASD through release of IL-17A. However, there is still insufficient data regarding identification of Th17 cells with respect to IL-6 signaling in ASD subjects. Therefore, this study explored IL-6 receptors (IL-6R/sIL-6R) and Th17 (p-STAT3/IL-17A/IL-23R) related markers comprehensively in the blood of typically-developing control (TDC, n = 35) and ASD children (n = 45). Our data show that there is enhanced sIL-6R levels in plasma and CD4+ T cells of ASD subjects as compared to TDC group. Increased sIL-6R signaling is associated with upregulated Th17 development in ASD subjects. Further, severe ASD subjects have higher inflammation in terms of IL-6/IL-17A related signaling as compared to moderate ASD patients. Furthermore, treatment of CD4 + T cells in vitro with IL-6 leads to much greater upregulation of p-STAT3, and IL-17A in ASD subjects than similarly treated CD4+ T cells in TDC group. Antagonism of IL-6 signaling by SC144 in vitro led to blockade of IL-6 mediated effects on CD4+ T cells. These data display unequivocally that IL-6 signaling components are dysregulated which play a crucial in enhancement of Th17 development in ASD subjects.

Propionic acid induced behavioural effects of relevance to autism spectrum disorder evaluated in the hole board test with rats

Autism spectrum disorders (ASD) are a set of neurodevelopmental disorders characterized by abnormal social interactions, impaired language, and stereotypic and repetitive behaviours. Among genetically susceptible subpopulations, gut and dietary influences may play a role in etiology. Propionic acid (PPA), produced by enteric gut bacteria, crosses both the gut-blood and the blood-brain barrier. Previous research has demonstrated that repeated intracerebroventricular (ICV) infusions of PPA in adult rats produce behavioural and neuropathological changes similar to those seen in ASD patients, including hyperactivity, stereotypy, and repetitive movements. The current study examined dose and time related changes of exploratory and repetitive behaviours with the use of the hole-board task. Adult male Long-Evans rats received ICV infusions twice a day, 4 h apart, of either buffered PPA (low dose 0.052 M or high dose 0.26 M, pH 7.5, 4 μL/infusion) or phosphate buffered saline (PBS, 0.1 M) for 7 consecutive days. Locomotor activity and hole-poke behaviour were recorded daily in an automated open field apparatus (Versamax), equipped with 16 open wells, for 30 min immediately after the second infusion. In a dose dependent manner PPA infused rats displayed significantly more locomotor activity, stereotypic behaviour and nose-pokes than PBS infused rats. Low-dose PPA animals showed locomotor activity levels similar to those of PBS animals at the start of the infusion schedule, but gradually increased to levels comparable to those of high-dose PPA animals by the end of the infusion schedule, demonstrating a dose and time dependent effect of the PPA treatments.

Developmental impact of air pollution on brain function

Air pollution is an important contributor to the global burden of disease, particularly to respiratory and cardiovascular diseases. In recent years, evidence is accumulating that air pollution may adversely affect the nervous system as shown by human epidemiological studies and by animal models. Age appears to play a relevant role in air pollution-induced neurotoxicity, with growing evidence suggesting that air pollution may contribute to neurodevelopmental and neurodegenerative diseases. Traffic-related air pollution (e.g. diesel exhaust) is an important contributor to urban air pollution, and fine and ultrafine particulate matter (PM) may possibly be its more relevant component. Air pollution is associated with increased oxidative stress and inflammation both in the periphery and in the nervous system, and fine and ultrafine PM can directly access the central nervous system. This short review focuses on the adverse effects of air pollution on the developing brain; it discusses some characteristics that make the developing brain more susceptible to toxic effects, and summarizes the animal and human evidence suggesting that exposure to elevated air pollution is associated with a number of behavioral and biochemical adverse effects. It also discusses more in detail the emerging evidence of an association between perinatal exposure to air pollution and increased risk of autism spectrum disorder. Some of the common mechanisms that may underlie the neurotoxicity and developmental neurotoxicity of air pollution are also discussed. Considering the evidence presented in this review, any policy and legislative effort aimed at reducing air pollution would be protective of children's well-being.

Beyond the brain: A multi-system inflammatory subtype of autism spectrum disorder

An immune-mediated subtype of autism spectrum disorder (ASD) has long been hypothesized. This article reviews evidence from family history studies of autoimmunity, immunogenetics, maternal immune activation, neuroinflammation, and systemic inflammation, which suggests immune dysfunction in ASD. Individuals with ASD have higher rates of co-morbid medical illness than the general population. Major medical co-morbidities associated with ASD are discussed by body system. Mechanisms by which FDA-approved and emerging treatments for ASD act upon the immune system are then reviewed. We conclude by proposing the hypothesis of an immune-mediated subtype of ASD which is characterized by systemic, multi-organ inflammation or immune dysregulation with shared mechanisms that drive both the behavioral and physical illnesses associated with ASD. Although gaps in evidence supporting this hypothesis remain, benefits of this conceptualization include framing future research questions that will help define a clinically meaningful subset of patients and focusing clinical interactions on early detection and treatment of high-risk medical illnesses as well as interfering behavioral signs and symptoms across the lifespan.

Oxidative and inflammatory mediators are upregulated in neutrophils of autistic children: Role of IL-17A receptor signaling

Autism spectrum disorder (ASD) is characterized by repetitive behaviors, impaired social communication and stereotyped interests, and often associated with dysregulations in innate/adaptive immune cells. IL-17A has been linked with abnormal behavioral patterns observed in autistic children and animal models of autism. However, it is yet to be investigated if IL-17A and its receptors are implicated in regulation of oxidative and inflammatory mediators in neutrophils of ASD patients. Therefore, we pursued to identify the effect of IL-17 receptor (IL-17R), and its inflammatory potential in neutrophils from ASD (n = 45) and typically developing control (TDC; n = 40) subjects. IL-17A, its receptor (IL-17R), associated signaling pathways [nuclear transcription factor nuclear factor-kappa B (NF-κB), IL-6 and oxidative stress parameters such as NADPH oxidase (NOX2), inducible nitric oxide synthase (iNOS), reactive oxygen species (ROS), and nitrotyrosine] were determined in the neutrophils from TDC and ASD subjects. Our data show that IL-17A expression, and IL-17R are increased in neutrophils of ASD patients. Further, inflammatory signaling pathways such as such as phospho-NFκB, and ROS generating enzymes, i.e. NOX2/iNOS are increased in neutrophils of ASD patients as compared TDC subjects. Furthermore, activation of IL-17A/IL-17R signaling in neutrophils of ASD subjects leads to upregulation of phospho-NFκB, IL-6 and NOX2/ROS, thus suggesting a compelling role of IL-17A in modulation of inflammation. Our study displays for the first time that IL-17A/IL-17R signaling in neutrophils could play a pivotal role in autism through upregulation of oxidative and inflammatory mediators.

A Nervous System-Specific Model of Creatine Transporter Deficiency Recapitulates the Cognitive Endophenotype of the Disease: a Longitudinal Study

Mutations in creatine (Cr) transporter (CrT) gene lead to cerebral creatine deficiency syndrome-1 (CTD), an orphan neurodevelopmental disorder presenting with brain Cr deficiency, intellectual disability, seizures, movement and autistic-like behavioral disturbances, language and speech impairment. We have recently generated a murine model of CTD obtained by ubiquitous deletion of 5-7 exons in the CrT gene. These mice showed a marked Cr depletion, associated to early and progressive cognitive impairment, and autistic-like defects, thus resembling the key features of human CTD. Given the importance of extraneural dysfunctions in neurodevelopmental disorders, here we analyzed the specific role of neural Cr in the CTD phenotype. We induced the conditional deletion of Slc6a8 gene in neuronal and glial cells by crossing CrT floxed mice with the Nestin::Cre recombinase Tg (Nes-cre) 1Kln mouse. We report that nervous system-specific Cr depletion leads to a progressive cognitive regression starting in the adult age. No autistic-like features, including repetitive and stereotyped movements, routines and rituals, are present in this model. These results indicate that Cr depletion in the nervous system is a pivotal cause of the CTD pathological phenotype, in particular with regard to the cognitive domain, but extraneural actors also play a role.

The Contribution of Inflammation to Autism Spectrum Disorders: Recent Clinical Evidence

Autism comprises a complex and heterogeneous spectrum of neurodevelopmental disorders, usually termed autism spectrum disorders (ASD). It is more prevalent in males than females, and genetic and environmental factors are believed to account in similar percentages to the development of ASD. In recent years, the contribution of inflammation and inflammatory mediators to disease aetiology and perpetuation has been the object of intense research. In this chapter, inflammatory aspects that contribute to ASD are discussed, including abnormal microglia activation and polarization phenotypes, increased systemic levels of pro-inflammatory mediators, and altered patterns of immune cell response to activation stimuli. Also, inflammation in the context of gut microbiome and the impact of inflammation on gender prevalence of ASD are considered. Finally, treatment impact on inflammatory parameters and the potential for use of anti-inflammatory drugs, alone or in combination with antipsychotics, to manage ASD are examined.

Gut Microbiota Features in Young Children With Autism Spectrum Disorders

Proliferation and/or depletion of clusters of specific bacteria regulate intestinal functions and may interfere with neuro-immune communication and behavior in patients with autism spectrum disorder (ASD). Consistently, qualitative and quantitative alteration of bacterial metabolites may functionally affect ASD pathophysiology. Up to date, age-restricted cohort studies, that may potentially help to identify specific microbial signatures in ASD, are lacking. We investigated the gut microbiota (GM) structure and fecal short chain fatty acids (SCFAs) levels in a cohort of young children (2-4 years of age) with ASD, with respect to age-matched neurotypical healthy controls. Strong increase of Bacteroidetes and Proteobacteria and decrease of Actinobacteria was observed in these patients. Among the 91 OTUs whose relative abundance was altered in ASD patients, we observed a striking depletion of Bifidobacterium longum, one of the dominant bacteria in infant GM and, conversely, an increase of Faecalibacterium prausnitzii, a late colonizer of healthy human gut and a major butyrate producer. High levels of F. prausnitzii were associated to increase of fecal butyrate levels within normal range, and over representation of KEGG functions related to butyrate production in ASD patients. Here we report unbalance of GM structure with a shift in colonization by gut beneficial bacterial species in ASD patients as off early childhood.

Neurobiology and treatment of social cognition in schizophrenia: Bridging the bed-bench gap

Social cognition refers to the psychological processes involved in the perception, encoding, storage, retrieval, and regulation of information about others and ourselves. This process is essential for survival and reproduction in complex social environments. Recent evidence suggests that impairments in social cognition frequently occur in schizophrenia, mainly contributing to poor functional outcomes, including the inability to engage in meaningful work and maintain satisfying interpersonal relationships. With the ambiguous definition of social cognition, the neurobiology underlying impaired social cognition remains unknown, and the effectiveness of currently available intervention strategies in schizophrenia remain limited. Considering the advances and challenges of translational research for schizophrenia, social cognition has been considered a high-priority domain for treatment development. Here, we describe the current state of the framework, clinical concerns, and intervention approaches for social cognition in schizophrenia. Next, we introduce translatable rodent models associated with schizophrenia that allow the evaluation of different components of social behaviors, providing deeper insights into the neural substrates of social cognition in schizophrenia. Our review presents a valuable perspective that indicates the necessity of building bridges between basic and clinical science researchers for the development of novel therapeutic approaches in impaired social cognition in schizophrenia.

Prenatal inflammation and risk for schizophrenia: A role for immune proteins in neurodevelopment

Prenatal inflammation is an established risk factor for schizophrenia. However, the specific inflammatory pathways that mediate this association remain unclear. Potential candidate systems include inflammatory markers produced by microglia, such as cytokines and complement. Accumulating evidence suggests that these markers play a role in typical neurodevelopmental processes, such as synapse formation and interneuron migration. Rodent models demonstrate that altered marker levels during the prenatal period can cause lasting deficits in these systems, leading to cognitive deficits that resemble schizophrenia. This review assesses the potential role of prenatal cytokine and complement elevations on the etiology of schizophrenia. The current neurobiological understanding of the development of schizophrenia is reviewed to identify candidate cellular mechanisms that may be influenced by prenatal inflammation. We discuss the functions that cytokines and complement may play in prenatal neurodevelopment, review evidence that links exposure to these factors with risk for schizophrenia, and consider how these markers may interact with genetic vulnerabilities to influence the neurodevelopment of schizophrenia. We consider how prenatal inflammatory exposure may influence childhood and adolescent developmental risk trajectories for schizophrenia. Finally, we identify areas of further research needed to support the development of anti-inflammatory treatments to prevent the development of schizophrenia in at-risk neonates.

Immune aberrations in children with Autism Spectrum Disorder: a case-control study from a tertiary care neuropsychiatric hospital in India

Multiple studies have identified the presence of peripheral immune aberrations in subjects with Autism Spectrum Disorder (ASD). However, comprehensive assessment of these peripheral immune aberrations, in the cellular and systemic compartments, in a single group of subjects with ASD is lacking. We assessed proportions of various subsets of immune cells in peripheral blood (T helper cells, T regulatory cells, B cells, monocytes, Natural Killer cells, dendritic cells) by multi-parametric flow cytometry in 50 children with ASD and compared it with thirty healthy controls matched for age, gender, socio-economic status and body mass index. There were no significant differences noted in the proportion of T regulatory cells, B cells, monocytes and Natural Killer cells, between ASD subjects and controls. On the contrary, the proportion of activated Th17 and myeloid dendritic cells were significantly higher in children with ASD. Based on these findings, group comparison of serum levels of Th17 cytokines (interleukin-6, interleukin-17A) was performed. Elevated serum levels of interleukin-6 and interleukin-17A in children with ASD corroborated our immunophenotyping findings. We did not find any significant differences among the pro-inflammatory (interleukin-1β), Th1 (interferon-γ) and Th2 (interleukin-4) cytokines. This is the first evidence with concurrent findings from immunophenotyping and cytokine data demonstrating activation of the Th17 pathway in subjects with ASD. This finding assumes significance in the light of recent maternal immune activation mouse model study that has highlighted the role of Th17 pathway in the pathophysiology of ASD. Future longitudinal studies are needed to clarify the role of this dysregulated immune pathway in the development of ASD.