Myeloid dendritic cells frequencies are increased in children with autism spectrum disorder and associated with amygdala volume and repetitive behaviors

Innate Immune Dysfunction and Neuroinflammation in Autism Spectrum Disorder (ASD)

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder characterized by communication and social behavior deficits. The presence of restricted and repetitive behaviors often accompanies these deficits, and these characteristics can range from mild to severe. The past several decades have seen a significant rise in the prevalence of ASD. The etiology of ASD remains unknown; however, genetic and environmental risk factors play a role. Multiple hypotheses converge to suggest that neuroinflammation, or at least the interaction between immune and neural systems, may be involved in the etiology of some ASD cases or groups. Repeated evidence of innate immune dysfunction has been seen in ASD, often associated with worsening behaviors. This evidence includes data from circulating myeloid cells and brain resident macrophages/microglia in both human and animal models. This comprehensive review presents recent findings of innate immune dysfunction in ASD, including aberrant innate cellular function, evidence of neuroinflammation, and microglia activation. Appeared originally in Brain Behav Immun 2023; 108:245-254.

Ex vivo exposure to polybrominated diphenyl ether (PBDE) selectively affects the immune response in autistic children

Children on the autism spectrum have been shown to have immune dysregulation that often correlates with behavioral deficits. The role of the post-natal environment in this dysregulation is an area of active investigation. We examined the association between plasma levels of polybrominated diphenyl ether (PBDE) and immune cell function in age-matched autistic children and non-autistic controls. Plasma from children on the autism spectrum (n = 38) and typically developing controls (TD; n = 60) were analyzed for 14 major PBDE congeners. Cytokine/chemokine production was measured in peripheral blood mononuclear cell (PBMC) supernatants with and without ex vivo BDE-49 exposure. Total plasma concentration (∑PBDE14) and individual congener levels were also correlated with T cell function. ∑PBDE14 did not differ between diagnostic groups but correlated with reduced immune function in children on the autism spectrum. In autistic children, IL-2 and IFN-γ production was reduced in association with several individual BDE congeners, especially BDE-49 (p = 0.001). Furthermore, when PBMCs were exposed ex vivo to BDE-49, cells from autistic children produced elevated levels of IL-6, TNF-α, IL-1β, MIP-1α and MCP-1 (p < 0.05). Therefore, despite similar plasma levels of PBDE, these data suggest that PBMC function was differentially impacted in the context of several PBDE congeners in autistic children relative to TD children where increased body burden of PBDE significantly correlated with a suppressed immune response in autistic children but not TD controls. Further, acute ex vivo exposure of PBMCs to BDE-49 stimulates an elevated cytokine response in AU cases versus a depressed response in TD controls. These data suggest that exposure to the toxicant BDE-49 differentially impacts immune cell function in autistic children relative to TD children providing evidence for an underlying association between susceptibility to PBDE exposure and immune anomalies in children on the autism spectrum.

Autistic spectrum disorder (ASD) - Gene, molecular and pathway signatures linking systemic inflammation, mitochondrial dysfunction, transsynaptic signalling, and neurodevelopment

Background

Despite advances in autism spectrum disorder (ASD) research and the vast genomic, transcriptomic, and proteomic data available, there are still controversies regarding the pathways and molecular signatures underlying the neurodevelopmental disorders leading to ASD.

Purpose

To delineate these underpinning signatures, we examined the two largest gene expression meta-analysis datasets obtained from the brain and peripheral blood mononuclear cells (PBMCs) of 1355 ASD patients and 1110 controls.

Methods

We performed network, enrichment, and annotation analyses using the differentially expressed genes, transcripts, and proteins identified in ASD patients.

Results

Transcription factor network analyses in up- and down-regulated genes in brain tissue and PBMCs in ASD showed eight main transcription factors, namely: BCL3, CEBPB, IRF1, IRF8, KAT2A, NELFE, RELA, and TRIM28. The upregulated gene networks in PBMCs of ASD patients are strongly associated with activated immune-inflammatory pathways, including interferon-α signaling, and cellular responses to DNA repair. Enrichment analyses of the upregulated CNS gene networks indicate involvement of immune-inflammatory pathways, cytokine production, Toll-Like Receptor signalling, with a major involvement of the PI3K-Akt pathway. Analyses of the downregulated CNS genes suggest electron transport chain dysfunctions at multiple levels. Network topological analyses revealed that the consequent aberrations in axonogenesis, neurogenesis, synaptic transmission, and regulation of transsynaptic signalling affect neurodevelopment with subsequent impairments in social behaviours and neurocognition. The results suggest a defense response against viral infection.

Conclusions

Peripheral activation of immune-inflammatory pathways, most likely induced by viral infections, may result in CNS neuroinflammation and mitochondrial dysfunction, leading to abnormalities in transsynaptic transmission, and brain neurodevelopment.

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.

Innate immune dysfunction and neuroinflammation in autism spectrum disorder (ASD)

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder characterized by communication and social behavior deficits. The presence of restricted and repetitive behaviors often accompanies these deficits, and these characteristics can range from mild to severe. The past several decades have seen a significant rise in the prevalence of ASD. The etiology of ASD remains unknown; however, genetic and environmental risk factors play a role. Multiple hypotheses converge to suggest that neuroinflammation, or at least the interaction between immune and neural systems, may be involved in the etiology of some ASD cases or groups. Repeated evidence of innate immune dysfunction has been seen in ASD, often associated with worsening behaviors. This evidence includes data from circulating myeloid cells and brain resident macrophages/microglia in both human and animal models. This comprehensive review presents recent findings of innate immune dysfunction in ASD, including aberrant innate cellular function, evidence of neuroinflammation, and microglia activation.

Novel insights into the immune cell landscape and gene signatures in autism spectrum disorder by bioinformatics and clinical analysis

The pathogenesis of autism spectrum disorder (ASD) is not well understood, especially in terms of immunity and inflammation, and there are currently no early diagnostic or treatment methods. In this study, we obtained six existing Gene Expression Omnibus transcriptome datasets from the blood of ASD patients. We performed functional enrichment analysis, PPI analysis, CIBERSORT algorithm, and Spearman correlation analysis, with a focus on expression profiling in hub genes and immune cells. We validated that monocytes and nonclassical monocytes were upregulated in the ASD group using peripheral blood (30 children with ASD and 30 age and sex-matched typically developing children) using flow cytometry. The receiver operating characteristic curves (PSMC4 and ALAS2) and analysis stratified by ASD severity (LIlRB1 and CD69) showed that they had predictive value using the "training" and verification groups. Three immune cell types - monocytes, M2 macrophages, and activated dendritic cells - had different degrees of correlation with 15 identified hub genes. In addition, we analyzed the miRNA-mRNA network and agents-gene interactions using miRNA databases (starBase and miRDB) and the DSigDB database. Two miRNAs (miR-342-3p and miR-1321) and 23 agents were linked with ASD. These findings suggest that dysregulation of the immune system may contribute to ASD development, especially dysregulation of monocytes and monocyte-derived cells. ASD-related hub genes may serve as potential predictors for ASD, and the potential ASD-related miRNAs and agents identified here may open up new strategies for the prevention and treatment of ASD.

The Autism Phenome Project: Toward Identifying Clinically Meaningful Subgroups of Autism

One of the most universally accepted facts about autism is that it is heterogenous. Individuals diagnosed with autism spectrum disorder have a wide range of behavioral presentations and a variety of co-occurring medical and mental health conditions. The identification of more homogenous subgroups is likely to lead to a better understanding of etiologies as well as more targeted interventions and treatments. In 2006, we initiated the UC Davis MIND Institute Autism Phenome Project (APP) with the overarching goal of identifying clinically meaningful subtypes of autism. This ongoing longitudinal multidisciplinary study now includes over 400 children and involves comprehensive medical, behavioral, and neuroimaging assessments from early childhood through adolescence (2-19 years of age). We have employed several strategies to identify sub-populations within autistic individuals: subgrouping by neural, biological, behavioral or clinical characteristics as well as by developmental trajectories. In this Mini Review, we summarize findings to date from the APP cohort and describe progress made toward identifying meaningful subgroups of autism.

B and T Immunoregulation: A New Insight of B Regulatory Lymphocytes in Autism Spectrum Disorder

Introduction: Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by a complex pathogenesis, by impairment social communication and interaction, and may also manifest repetitive patterns of behavior. Many studies have recognized an alteration of the immune response as a major etiological component in ASDs. Despite this, it is still unclear the variation of the function of the immune response.

Aim: Our aim is to investigate the levels of immunological markers in peripheral blood of children with ASD such as: regulatory B and T cells, memory B and natural killer (NK) cells.

Materials and Methods: We assessed various subsets of immune cells in peripheral blood (regulatory B and T cells, B-cell memory and natural killer cells) by multi-parametric flow cytometric analysis in 26 ASD children compared to 16 healthy controls (HCs) who matched age and gender.

Results: No significant difference was observed between B-cell memory and NK cells in ASDs and HCs. Instead, regulatory B cells and T cells were decreased (p < 0.05) in ASD subjects when compared to HCs.

Discussion: Regulatory B and T cells have a strategic role in maintaining the immune homeostasis. Their functions have been associated with the development of multiple pathologies especially in autoimmune diseases. According to our study, the immunological imbalance of regulatory B and T cells may play a pivotal role in the evolution of the disease, as immune deficiencies could be related to the severity of the ongoing disorder.

Amygdala subnuclei development in adolescents with autism spectrum disorder: Association with social communication and repetitive behaviors

INTRODUCTION

The amygdala subnuclei regulate emotional processing and are widely implicated in social cognitive impairments often seen in children with autism spectrum disorder (ASD). Dysregulated amygdala development has been reported in young children with ASD; less is known about amygdala maturation in later adolescence, a sensitive window for social skill development.

METHODS

The macrostructural development of the amygdala subnuclei was assessed at two time points in a longitudinal magnetic resonance imaging (MRI) study of adolescents with ASD (n = 23) and typically-developing adolescents (n = 15) . In adolescents with ASD, amygdala subnuclei growth was assessed in relation to ASD symptomatology based on standardized diagnostic assessments. Participants were scanned with MRI at median age of 12 years and returned for a second scan at a median age of 15 years. The volumes of nine amygdala subnuclei were extracted using an automatic segmentation algorithm.

RESULTS

When examining the longitudinal data acquired across two time points, adolescents with ASD had larger basolateral amygdala (BLA) nuclei volumes compared to typically developing adolescents (B = 46.8, p = 0.04). When examining ASD symptomatology in relation to the growth of the amygdala subnuclei, reciprocal social interaction scores on the ADI-R were positively associated with increased growth of the BLA nuclei (B = 8.3, p < 0.001). Growth in the medial nucleus negatively predicted the communication (B = -46.9, p = 0.02) and social (B = -47.7, p < 0.001) domains on the ADOS-G. Growth in the right cortical nucleus (B = 26.14, p = 0.02) positively predicted ADOS-G social scores. Central nucleus maturation (B = 29.9, p = 0.02) was associated with the repetitive behaviors domain on the ADOS-G.

CONCLUSIONS

Larger BLA volumes in adolescents with ASD may reflect underlying alterations in cellular density previously reported in post-mortem studies. Furthermore, findings demonstrate an association between regional growth in amygdala subnuclei volumes and ASD symptomatology. Improved understanding of the developmental trajectories of the amygdala subnuclei may aid in identifying key windows for interventions, particularly for social communication, in adolescents with ASD.

Intestinal permeability correlates with behavioural severity in very young children with ASD: A preliminary study

Systemic inflammation is known to alter behaviour, and since it has been reported that individuals with autism spectrum disorder (ASD) have higher levels of circulating cytokines, it has been hypothesized that systemic inflammation may exacerbate behaviours characteristic of ASD. The acute phase proteins α-2-macroglobulin, C-reactive protein, haptoglobin, serum amyloid P, serum amyloid A, ferritin and tissue plasminogen activator, as well as markers of intestinal permeability (intestinal fatty acid binding protein and lipopolysaccharide) were quantitated in the plasma of very young children with ASD. Behaviour severity was measured using the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observation Schedule (ADOS) and the Vineland Adaptive Behaviour Scale (VABS). An increase in circulating I-FABP correlated with more severe deficits in communication, communication + social interaction as well as maladaptive behaviour. The acute phase protein haptoglobin was associated with more severe social interaction and communication + social interaction. In summary, I-FABP, a marker of intestinal epithelial damage, was associated with more severe behavioural phenotypes in very young children with ASD. In addition, the acute phase protein, haptoglobin, was associated with behaviour.

Analyses of peripheral blood dendritic cells and magnetic resonance spectroscopy support dysfunctional neuro-immune crosstalk in Tourette syndrome

BACKGROUND

Evidence supports that neurodevelopmental diseases, such as Tourette syndrome (TS), may involve dysfunctional neural-immune crosstalk. This could lead to altered brain maturation and differences in immune and stress responses. Dendritic cells (DCs) play a major role in immunity as professional antigen-presenting cells; changes in their frequency have been observed in several autoimmune conditions.

METHODS

In 18 TS patients (15 on stable pharmacological treatment, three unmedicated) and 18 age-matched healthy volunteers (HVs), we explored circulating blood-derived DCs and their relationship with clinical variables and brain metabolites, measured via proton magnetic resonance spectroscopy (1H-MRS). DC subsets, including plasmacytoid and myeloid type 1 and 2 dendritic cells (MDC1, MDC2), were studied with flow cytometry. 1H-MRS was used to measure total choline, glutamate plus glutamine, total creatine (tCr), and total N-acetylaspartate and N-acetylaspartyl-glutamate levels in frontal white matter (FWM) and the putamen.

RESULTS

We did not observe differences in absolute concentrations of DC subsets or brain inflammatory metabolites between patients and HVs. However, TS patients manifesting anxiety showed a significant increase in MDC1s compared to TS patients without anxiety (p = 0.01). We also found a strong negative correlation between MDC1 frequency and tCr in the FWM of patients with TS (p = 0.0015), but not of HVs.

CONCLUSION

Elevated frequencies of the MDC1 subset in TS patients manifesting anxiety may reflect a proinflammatory status, potentially facilitating altered neuro-immune crosstalk. Furthermore, the strong inverse correlation between brain tCr levels and MDC1 subset frequency in TS patients suggests a potential association between proinflammatory status and metabolic changes in sensitive brain regions.

Prevalence and Age of Onset of Regression in Children with Autism Spectrum Disorder: A Systematic Review and Meta-analytical Update

A systematic review published in 2013 reported 32% of children on the autism spectrum experience skill loss, known as autistic regression. However, the frequency varied depending on definition and measures used to capture skills. Retrospective parent report and prospective observation indicate loss of language and/or social skills, with motor skills typically unaffected. Our aim was to update the prevalence and age of onset of autistic regression through a meta-analysis of the literature to understand if there have been changes to the reported onset and prevalence since 2010. A systematic literature search was conducted using Medline, Embase, PsycINFO, and the Cochrane Library databases and included studies published from 2010 onward. Risk of bias assessment was performed on included studies. A random effects model was used to calculate the pooled prevalence and age of onset of autistic regression. Ninety-seven studies were included in the systematic review, of which 75 studies involving 33,014 participants had sufficient data for meta-analytic syntheses. The pooled proportion of autistic regression was 30% (95% confidence interval [CI]: 27-32%) but heterogeneity was high (I² = 96.91) and did not reduce with sensitivity or subgroup analyses based on study design or clinical differences, respectively. Prevalence varied according to risk of bias (low: 27%) and definition of regression (language: 20%, language/social: 40%, mixed: 30%, and unspecified: 27%). Weighted average age of onset was 19.8 months. Findings from this meta-analysis highlight the importance of developing a standardized definition of autistic regression, and tools to measure this at multiple time points during early childhood development. LAY SUMMARY: About a third of children with Autism Spectrum Disorder experience loss of skills, which is also known as autistic regression. This paper provides an update of the rate of autistic regression in children and the age when they first experience loss of skills, based on current studies. The findings from this review contribute to our understanding of the onset patterns of autistic regression. Unfortunately, studies are not sufficiently similar, making it difficult to provide clear answers on the exact timing or type of regression seen in different children.

Strain differences in behaviour and immunity in aged mice: Relevance to Autism

The BTBR mouse model has been shown to be associated with deficits in social interaction and a pronounced engagement in repetitive behaviours. Autism spectrum disorder (ASD) is the most prevalent neurodevelopmental condition globally. Despite its ubiquity, most research into the disorder remains focused on childhood, with studies in adulthood and old age relatively rare. To this end, we explored the differences in behaviour and immune function in an aged BTBR T + Itpr3tf/J mouse model of the disease compared to a similarly aged C57bl/6 control. We show that while many of the alterations in behaviour that are observed in young animals are maintained (repetitive behaviours, antidepressant-sensitive behaviours, social deficits & cognition) there are more nuanced effects in terms of anxiety in older animals of the BTBR strain compared to C57bl/6 controls. Furthermore, BTBR animals also exhibit an activated T-cell system. As such, these results represent confirmation that ASD-associated behavioural deficits are maintained in ageing, and that that there may be need for differential interventional approaches to counter these impairments, potentially through targeting the immune system.

Immune regulation of neurodevelopment at the mother-foetus interface: the case of autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder defined by deficits in social communication and stereotypical behaviours. ASD’s aetiology remains mostly unclear, because of a complex interaction between genetic and environmental factors. Recently, a strong consensus has developed around ASD’s immune‐mediated pathophysiology, which is the subject of this review. For many years, neuroimmunological studies tried to understand ASD as a prototypical antibody‐ or cell‐mediated disease. Other findings indicated the importance of autoimmune mechanisms such as familial and individual autoimmunity, adaptive immune abnormalities and the influence of infections during gestation. However, recent studies have challenged the idea that autism may be a classical autoimmune disease. Modern neurodevelopmental immunology shows the double‐edged nature of many immune effectors, which can be either beneficial or detrimental depending on tissue homeostasis, stressors, neurodevelopmental stage, inherited and de novo gene mutations and other variables. Nowadays, mother–child interactions in the prenatal environment appear to be crucial for the occurrence of ASD. Studies of animal maternal–foetal immune interaction are being fruitfully carried out using different combinations of type and timing of infection, of maternal immune response and foetal vulnerability and of resilience factors to hostile events. The derailed neuroimmune crosstalk through the placenta initiates and maintains a chronic foetal neuroglial activation, eventually causing the alteration of neurogenesis, migration, synapse formation and pruning. The importance of pregnancy can also allow early immune interventions, which can significantly reduce the increasing risk of ASD and its heavy social burden.

Study on Aberrant Eating Behaviors, Food Intolerance, and Stereotyped Behaviors in Autism Spectrum Disorder

Objective: To investigate the aberrant eating behaviors (EBs), gastrointestinal (GI) symptoms, and food intolerance in children with autism spectrum disorder (ASD) and their association with clinical core symptoms of ASD. Method: A total of 94 preschool children with ASD treated at the Child Mental Health Research Center of Nanjing Brain Hospital between October 2016 and April 2018 were enrolled. In addition, 90 children with typical development (TD) in the community during the same period were recruited. The conditions of aberrant EBs and GI symptoms in children were investigated using questionnaire surveys. Serum specific IgG antibodies against 14 kinds of food were detected using enzyme-linked immunosorbent assays (ELISAs). Results: The detection rate of aberrant EBs in the ASD group was significantly higher than that in the TD group (67.39 vs. 34.94%), and the rate of GI symptoms was also higher in the ASD group than that in the TD group (80.22 vs. 42.11%). Detection of food intolerance in children with ASD showed that the positive rate was 89.89% and that the majority of children had multiple food intolerances. The correlation analysis results showed that the severity of aberrant EBs positively correlated with stereotyped behavior of children with ASD (r = 0.21, P = 0.04) and that food-specific IgG antibodies concentrations positively correlated with high-level stereotyped behavior in children with ASD (r = 0.23, P = 0.03). Conclusion: ASD with aberrant EBs or high food-specific IgG antibodies concentrations had more severe stereotyped behavior, which may have implications for exploring the immune mechanism of ASD. Clinical Trial Registration: ChiCTR-RPC-16008139.

Inflammatory Biomarkers are Correlated with Some Forms of Regressive Autism Spectrum Disorder

Background: Several studies have tried to investigate the role of inflammatory biomarkers in Autism Spectrum Disorder (ASD), and their correlations with clinical phenotypes. Despite the growing research in this topic, existing data are mostly contradictory. Methods: Eighty-five ASD preschoolers were assessed for developmental level, adaptive functioning, gastrointestinal (GI), socio-communicative and psychopathological symptoms. Plasma levels of leptin, resistin, plasminogen activator inhibitor-1 (PAI-1), macrophage chemoattractant protein-1 (CCL2), tumor necrosis factor-alfa (TNF-α), and interleukin-6 (IL-6) were correlated with clinical scores and were compared among different ASD subgroups according to the presence or absence of: (i) GI symptoms, (ii) regressive onset of autism. Results: Proinflammatory cytokines (TNF-α, IL-6 and CCL2) were lower than those reported in previous studies in children with systemic inflammatory conditions. GI symptoms were not correlated with levels of inflammatory biomarkers except for resistin that was lower in ASD-GI children (p = 0.032). Resistin and PAI-1 levels were significantly higher in the group with “regression plus a developmental delay” onset (Reg+DD group) compared to groups without regression or with regression without a developmental delay (p < 0.01 for all). Conclusions: Our results did not highlight the presence of any systemic inflammatory state in ASD subjects neither disentangling children with/without GI symptoms. The Reg + DD group significantly differed from others in some plasmatic values, but these differences failed to discriminate the subgroups as possible distinct ASD endo-phenotypes.

The histamine-4 receptor antagonist JNJ7777120 prevents immune abnormalities by inhibiting RORγt/T-bet transcription factor signaling pathways in BTBR T+ Itpr3tf/J mice exposed to gamma rays

Autism is a neurodevelopmental disorder characterized by deficits and qualitative impairments in communication and implicit skill learning. Its prevalence is higher than previous estimates, and treatments have limited efficacy and are costly. Here, we assessed the therapeutic potential of JNJ77777120 (JNJ), a histamine-4 receptor (H4R) antagonist, using BTBR T⁺ Itpr3^tf/J (BTBR) mice, a confirmed model of autism, and C57BL/6J (C57) mice, a commonly chosen reference strain. We first examined the effects of JNJ treatment on BTBR mice exposed to gamma-rays (irradiation-exposed) using a three-chambered apparatus. We further investigated the possible molecular mechanisms through which JNJ administration modulates IL-17A-, RORγT-, IL-22-, T-bet-, STAT3-, ICOS-, and Foxp3-producing CD8⁺ T cells in the spleens of irradiation-exposed BTBR mice. The effects of JNJ administration on the mRNA and protein expression of IL-17A, RORγT, IL-22, T-bet, STAT-3, pSTAT3, IL-10, and Foxp3 in brain tissue were also explored. Results showed that JNJ treatment with irradiation exposure increased social interactions in BTBR mice compared to that in irradiation-exposed BTBR mice. Additionally, JNJ-treated and irradiation-exposed BTBR mice exhibited decreases in IL-17A-, RORγT-, IL-22-, T-bet-, and STAT3-producing CD8⁺ T cells and increases in ICOS- and Foxp3-producing CD8⁺ T cells. Moreover, JNJ treatment and irradiation exposure in BTBR mice regulated the mRNA and protein expression levels of IL-17A, RORγT, IL-22, T-bet, STAT3, pSTAT-3, IL-10, and Foxp3 in the brain tissue. These results suggest that JNJ is useful for the treatment of autism, as this H4R antagonist could block inflammatory cytokine production and transcription factor signaling.

Proteomics Study of Peripheral Blood Mononuclear Cells (PBMCs) in Autistic Children

Autism is one of the most common neurological developmental disorder associated with social isolation and restricted interests in children. The etiology of this disorder is still unknown. There is neither any confirmed laboratory test nor any effective therapeutic strategy to diagnose or cure it. To search for biomarkers for early detection and exploration of the disease mechanisms, here, we investigated the protein expression signatures of peripheral blood mononuclear cells (PBMCs) in autistic children compared with healthy controls by using isobaric tags for relative and absolute quantitation (iTRAQ) proteomics approach. The results showed a total of 41 proteins as differentially expressed in autistic group as compared to control. These proteins are found associated with metabolic pathways, endoplasmic reticulum (ER) stress and protein folding, endocytosis, immune and inflammatory response, plasma lipoprotein particle organization, and cell adhesion. Among these, 17 proteins (13 up-regulated and four down-regulated) are found to be linked with mitochondria. Eight proteins including three already reported proteins in our previous studies were selected to be verified. Five already reported autism associated pro-inflammatory cytokines [interferon-γ (IFN-γ), interleukin-1β (IL-1β), IL-6, IL-12, and tumor necrosis factor-α (TNF-α)] were detected in plasma by enzyme-linked immunosorbent assay (ELISA) analysis. The results were consistent with proteomic results and reports from previous literature. These results proposed that PBMCs from autistic children might be activated, and ER stress, unfolded protein response (UPR), acute-phase response (APR), inflammatory response, and endocytosis may be involved in autism occurrence. These reported proteins may serve as potential biomarkers for early diagnosis of autism. More specifically, simultaneous detection of three proteins [complement C3 (C3), calreticulin (CALR), and SERPINA1] in the plasma and PBMCs could increase the authenticity of detection.

Immune Dysfunction and Autoimmunity as Pathological Mechanisms in Autism Spectrum Disorders

Autism spectrum disorders (ASD) are a group of heterogeneous neurological disorders that are highly variable and are clinically characterized by deficits in social interactions, communication, and stereotypical behaviors. Prevalence has risen from 1 in 10,000 in 1972 to 1 in 59 children in the United States in 2014. This rise in prevalence could be due in part to better diagnoses and awareness, however, these together cannot solely account for such a significant rise. While causative connections have not been proven in the majority of cases, many current studies focus on the combined effects of genetics and environment. Strikingly, a distinct picture of immune dysfunction has emerged and been supported by many independent studies over the past decade. Many players in the immune-ASD puzzle may be mechanistically contributing to pathogenesis of these disorders, including skewed cytokine responses, differences in total numbers and frequencies of immune cells and their subsets, neuroinflammation, and adaptive and innate immune dysfunction, as well as altered levels of immunoglobulin and the presence of autoantibodies which have been found in a substantial number of individuals with ASD. This review summarizes the latest research linking ASD, autoimmunity and immune dysfunction, and discusses evidence of a potential autoimmune component of ASD.

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.

Parents' impaired emotion recognition abilities are related to children's autistic symptoms in autism spectrum disorder

OBJECTIVE

We aimed to explore whether parents of children with autism spectrum disorder (ASD) had impaired emotion recognition abilities and whether this deficit was related to their children's autistic symptoms.

METHODS

The autistic symptoms of 31 ASD children were assessed using the Autism Diagnostic Interview-Revised (ADI-R). Fifty parents of ASD children and 34 parents of typically developing (TD) children completed an emotion recognition task (ERT).

RESULTS

The numbers of correct ERT responses were lower for parents of ASD children than for parents of TD children with respect to recognizing sadness, disgust, fear, and all emotions (P=0.01, 0.04, 0.02, and 0.00, respectively). Controlled for parental age, gender, and the intelligence quotients of both the parents and children, a negative correlation was found between the total number of correct ERT responses for parents of ASD children and these children's "restricted, repetitive, and stereotyped patterns of behavior" scores on the ADI-R (r=-0.32; P=0.03).

CONCLUSION

Parents of ASD children showed impaired emotion recognition abilities compared with parents of TD children. This parental deficit in emotion recognition ability was related to the autistic symptoms of ASD children.

Differential T Cell Levels of Tumor Necrosis Factor Receptor-II in Children With Autism

Autism spectrum disorders (ASD) are characterized by impairments in verbal and non-verbal communication, in social interactions, and often accompanied by stereotypical interests and behaviors. A role for immune dysfunction has long been implicated in ASD pathophysiology, behavioral severity, and co-morbidities. The pro-inflammatory cytokine tumor necrosis factor alpha (TNFα) has been associated with ASD in some studies but little is known about its receptors. There are two receptors for TNFα, with TNFRI relaying many of the signals from TNFα, especially those that are rapid, whilst TNFRII relays later more long-term effects of TNFα. Proteolytic cleavage can lead to the soluble versions of these receptors which can neutralize the effects of TNFα. Here, we determined levels of TNFα and its receptors in 36 children with a confirmed diagnosis of ASD and 27 confirmed typically developing (TD) controls, 2-5 years-of-age. Children with ASD had higher levels of TNFRII on T cells compared to controls following cell stimulation. Levels of sTNFRII were decreased in cell supernatants following stimulation in ASD. Overall these data corroborate the role of inflammatory events in ASD and align with previous studies that have shown differential changes in cellular adaptive immunity in children with ASD. Future longitudinal analyzes of cellular immune function and downstream signaling from immune receptors will help further delineate the role of inflammation in ASD.

Frequency of Dendritic Cells and Their Expression of Costimulatory Molecules in Children with Autism Spectrum Disorders

The aim of our study was to evaluate the frequencies of myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) in children with ASD. Subjects were 32 children with ASD and 30 healthy children as controls. The numbers of mDCs and pDCs and the expression of CD86 and CD80 on the entire DCs were detected by flow cytometry. ASD children had significantly higher percentages of mDCs and pDCs when compared to controls. We found significant inverse relationships between serum 25-hydroxyvitamin D levels and the frequencies of mDCs and pDCs in autistic children. Our data suggested that DCs could play a role in the clinical course of ASD. The relationship of DCs to immune disorders in ASD remains to be determined.

Annual Research Review: Understudied populations within the autism spectrum - current trends and future directions in neuroimaging research

BACKGROUND

Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental conditions that vary in both etiology and phenotypic expression. Expressions of ASD characterized by a more severe phenotype, including autism with intellectual disability (ASD + ID), autism with a history of developmental regression (ASD + R), and minimally verbal autism (ASD + MV) are understudied generally, and especially in the domain of neuroimaging. However, neuroimaging methods are a potentially powerful tool for understanding the etiology of these ASD subtypes.

SCOPE AND METHODOLOGY

This review evaluates existing neuroimaging research on ASD + MV, ASD + ID, and ASD + R, identified by a search of the literature using the PubMed database, and discusses methodological, theoretical, and practical considerations for future research involving neuroimaging assessment of these populations.

FINDINGS

There is a paucity of neuroimaging research on ASD + ID, ASD + MV, and ASD + R, and what findings do exist are often contradictory, or so sparse as to be ungeneralizable. We suggest that while greater sample sizes and more studies are necessary, more important would be a paradigm shift toward multimodal (e.g. imaging genetics) approaches that allow for the characterization of heterogeneity within etiologically diverse samples.

Dynamic Akt/mTOR Signaling in Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a behaviorally defined disorder affecting 1 in 68 children. Currently, there is no known cause for the majority of ASD cases nor are there physiological diagnostic tools or biomarkers to aid behavioral diagnosis. Whole-genome linkage studies, genome-wide association studies, copy number variation screening, and SNP analyses have identified several ASD candidate genes, but which vary greatly among individuals and family clusters, suggesting that a variety of genetic mutations may result in a common pathology or alter a common mechanistic pathway. The Akt/mammalian target of rapamycin (mTOR) pathway is involved in many cellular processes including synaptic plasticity and immune function that can alter neurodevelopment. In this study, we examined the activity of the Akt/mTOR pathway in cells isolated from children with ASD and typically developing controls. We observed higher activity of mTOR, extracellular receptor kinase, and p70S6 kinase and lower activity of glycogen synthase kinase 3 (GSK3)α and tuberin (TSC2) in cells from children with ASD. These data suggest a phosphorylation pattern indicative of higher activity in the Akt/mTOR pathway in children with general/idiopathic ASD and may suggest a common pathological pathway of interest for ASD.

Identification of Biomarkers of Impaired Sensory Profiles among Autistic Patients

Background

Autism is a neurodevelopmental disorder that displays significant heterogeneity. Comparison of subgroups within autism, and analyses of selected biomarkers as measure of the variation of the severity of autistic features such as cognitive dysfunction, social interaction impairment, and sensory abnormalities might help in understanding the pathophysiology of autism.

Methods and Participants

In this study, two sets of biomarkers were selected. The first included 7, while the second included 6 biomarkers. For set 1, data were collected from 35 autistic and 38 healthy control participants, while for set 2, data were collected from 29 out of the same 35 autistic and 16 additional healthy subjects. These markers were subjected to a principal components analysis using either covariance or correlation matrices. Moreover, libraries composed of participants categorized into units were constructed. The biomarkers used include, PE (phosphatidyl ethanolamine), PS (phosphatidyl serine), PC (phosphatidyl choline), MAP2K1 (Dual specificity mitogen-activated protein kinase kinase 1), IL-10 (interleukin-10), IL-12, NFκB (nuclear factor-κappa B); PGE2 (prostaglandin E2), PGE2-EP2, mPGES-1 (microsomal prostaglandin synthase E-1), cPLA2 (cytosolic phospholipase A2), 8-isoprostane, and COX-2 (cyclo-oxygenase-2).

Results

While none of the studied markers correlated with CARS and SRS as measure of cognitive and social impairments, six markers significantly correlated with sensory profiles of autistic patients. Multiple regression analysis identifies a combination of PGES, mPGES-1, and PE as best predictors of the degree of sensory profile impairment. Library identification resulted in 100% correct assignments of both autistic and control participants based on either set 1 or 2 biomarkers together with a satisfactory rate of assignments in case of sensory profile impairment using different sets of biomarkers.

Conclusion

The two selected sets of biomarkers were effective to separate autistic from healthy control subjects, demonstarting the possibility to accurately predict the severity of autism using the selected biomarkers. The effectiveness of the identified libraries lied in the fact that they were helpful in correctly assigning the study population as control or autistic patients and in classifying autistic patients with different degree of sensory profile impairment.

Associations between cytokines, endocrine stress response, and gastrointestinal symptoms in autism spectrum disorder

Many children and adolescents with autism spectrum disorder (ASD) have significant gastrointestinal (GI) symptoms, but the etiology is currently unknown. Some individuals with ASD show altered reactivity to stress and altered immune markers relative to typically-developing individuals, particularly stress-responsive cytokines including tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). Acute and chronic stress is associated with the onset and exacerbation of GI symptoms in those without ASD. The present study examined whether GI symptoms in ASD were associated with increases in cortisol, a stress-associated endocrine marker, and TNF-α and IL-6 in response to stress. As hypothesized, a greater amount of lower GI tract symptoms were significantly associated with post-stress cortisol concentration. The relationship between cortisol response to stress and GI functioning was greater for children who had a history of regressive autism. Exploratory analyses revealed significant correlations between cortisol response, intelligence, and inappropriate speech. In contrast, symptoms of the lower GI tract were not associated with levels of TNF-α or IL-6. Significant correlations were found, however, between TNF-α and IL-6 and irritability, socialization, and intelligence. These findings suggest that individuals with ASD and symptoms of the lower GI tract may have an increased response to stress, but this effect is not associated with concomitant changes in TNF-α and IL-6. The relationship between cortisol stress response and lower GI tract symptoms in children with regressive autism, as well as the relationships between cortisol, IL-6, and intelligence in ASD, warrant further investigation.

Functional Connectivity of the Amygdala Is Disrupted in Preschool-Aged Children With Autism Spectrum Disorder

OBJECTIVE

The objective of this study was to determine whether functional connectivity of the amygdala is altered in preschool-age children with autism spectrum disorder (ASD) and to assess the clinical relevance of observed alterations in amygdala connectivity.

METHOD

A resting-state functional connectivity magnetic resonance imaging study of the amygdala (and a parallel study of primary visual cortex) was conducted in 72 boys (mean age 3.5 years; n = 43 with ASD; n = 29 age-matched controls).

RESULTS

The ASD group showed significantly weaker connectivity between the amygdala and several brain regions involved in social communication and repetitive behaviors, including bilateral medial prefrontal cortex, temporal lobes, and striatum (p < .05, corrected). Weaker connectivity between the amygdala and frontal and temporal lobes was significantly correlated with increased autism severity in the ASD group (p < .05). In a parallel analysis examining the functional connectivity of primary visual cortex, the ASD group showed significantly weaker connectivity between visual cortex and sensorimotor regions (p < .05, corrected). Weaker connectivity between visual cortex and sensorimotor regions was not correlated with core autism symptoms, but instead was correlated with increased sensory hypersensitivity in the visual/auditory domain (p < .05).

CONCLUSION

These findings indicate that preschool-age children with ASD have disrupted functional connectivity between the amygdala and regions of the brain important for social communication and language, which might be clinically relevant because weaker connectivity was associated with increased autism severity. Moreover, although amygdala connectivity was associated with behavioral domains that are diagnostic of ASD, altered connectivity of primary visual cortex was related to sensory hypersensitivity.

Risk factors in autism: Thinking outside the brain

Autism spectrum disorders (ASD) are complex neurodevelopmental conditions that have been rising markedly in prevalence for the past 30 years, now thought to affect 1 in 68 in the United States. This has prompted the search for possible explanations, and has even resulted in some controversy regarding the "true" prevalence of autism. ASD are influenced by a variety of genetic, environmental, and possibly immunological factors that act during critical periods to alter key developmental processes. This can affect multiple systems and manifests as the social and behavioral deficits that define these disorders. The interaction of environmental exposures in the context of an individual's genetic susceptibilities manifests differently in each case, leading to heterogeneous phenotypes and varied comorbid symptoms within the disorder. This has also made it very difficult to elucidate underlying genes and exposure profiles, but progress is being made in this area. Some pharmaceutical drugs, toxicants, and metabolic and nutritional factors have been identified in epidemiological studies as increasing autism risk, especially during the prenatal period. Immunologic risk factors, including maternal infection during pregnancy, autoantibodies to fetal brain proteins, and familial autoimmune disease, have consistently been observed across multiple studies, as have immune abnormalities in individuals with ASD. Mechanistic research using animal models and patient-derived stem cells will help researchers to understand the complex etiology of these neurodevelopmental disorders, which will lead to more effective therapies and preventative strategies. Proposed therapies that need more investigation include special diets, probiotics, immune modulation, oxytocin, and personalized pharmacogenomic targets. The ongoing search for biomarkers and better treatments will result in earlier identification of ASD and provide much needed help and relief for afflicted families.

The role of inflammation and microglial activation in the pathophysiology of psychiatric disorders

Psychiatric disorders, including major depressive disorder (MDD), bipolar disorder (BD) and schizophrenia, affect a significant percentage of the world population. These disorders are associated with educational difficulties, decreased productivity and reduced quality of life, but their underlying pathophysiological mechanisms are not fully elucidated. Recently, studies have suggested that psychiatric disorders could be considered as inflammatory disorders, even though the exact mechanisms underlying this association are not known. An increase in inflammatory response and oxidative stress may lead to inflammation, which in turn can stimulate microglia in the brain. Microglial activation is roused by the M1 phenotype, which is associated with an increase in interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). On the contrary, M2 phenotype is associated with a release of anti-inflammatory cytokines. Thus, it is possible that the inflammatory response from microglial activation can contribute to brain pathology, as well as influence treatment responses. This review will highlight the role of inflammation in the pathophysiology of psychiatric disorders, such as MDD, BD, schizophrenia, and autism. More specifically, the role of microglial activation and associated molecular cascades will also be discussed as a means by which these neuroinflammatory mechanisms take place, when appropriate.

Therapeutic properties of mesenchymal stem cells for autism spectrum disorders

Recent studies of autism spectrum disorders (ASD) highlight hyperactivity of the immune system, irregular neuronal growth and increased size and number of microglia. Though the small sample size in many of these studies limits extrapolation to all individuals with ASD, there is mounting evidence of both immune and nervous system related pathogenesis in at least a subset of patients with ASD. Given the disturbing rise in incidence rates for ASD, and the fact that no pharmacological therapy for ASD has been approved by the Food and Drug Administration (FDA), there is an urgent need for new therapeutic options. Research in the therapeutic effects of mesenchymal stem cells (MSC) for other immunological and neurological conditions has shown promising results in preclinical and even clinical studies. MSC have demonstrated the ability to suppress the immune system and to promote neurogenesis with a promising safety profile. The working hypothesis of this paper is that the potentially synergistic ability of MSC to modulate a hyperactive immune system and its ability to promote neurogenesis make it an attractive potential therapeutic option specifically for ASD. Theoretical mechanisms of action will be suggested, but further research is necessary to support these hypothetical pathways. The choice of tissue source, type of cell, and most appropriate ages for therapeutic intervention remain open questions for further consideration. Concern over poor regulatory control of stem cell studies or treatment, and the unique ethical challenges that each child with ASD presents, demands that future research be conducted with particular caution before widespread use of the proposed therapeutic intervention is implemented.

Dendritic cells during Staphylococcus aureus infection: subsets and roles

Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that play a crucial role in both innate and adaptive immune responses. DCs orient the immune responses by modulating the balance between protective immunity to pathogens and tolerance to self-antigens. Staphylococcus aureus (S. aureus) is a common member of human skin microbiota and can cause severe infections with significant morbidity and mortality. Protective immunity to pathogens by DCs is required for clearance of S. aureus. DCs sense the presence of the staphylococcal components using pattern recognition receptors (PRRs) and then orchestrate immune systems to resolve infections. This review summarizes the possible roles of DCs, in particular their Toll-like receptors (TLRs) involved in S. aureus infection and strategies by which the pathogen affects activation and function of DCs.

Evidence supporting an altered immune response in ASD

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by deficits in social interactions, communication, and increased stereotypical repetitive behaviors. The immune system plays an important role in neurodevelopment, regulating neuronal proliferation, synapse formation and plasticity, as well as removing apoptotic neurons. Immune dysfunction in ASD has been repeatedly described by many research groups across the globe. Symptoms of immune dysfunction in ASD include neuroinflammation, presence of autoantibodies, increased T cell responses, and enhanced innate NK cell and monocyte immune responses. Moreover these responses are frequently associated with more impairment in core ASD features including impaired social interactions, repetitive behaviors and communication. In mouse models replacing immune components in animals that exhibit autistic relevant features leads to improvement in behavior in these animals. Taken together this research suggests that the immune dysfunction often seen in ASD directly affects aspects of neurodevelopment and neurological processes leading to changes in behavior. Discussion of immune abnormalities in ASD will be the focus of this review.

Maternal stress, nutrition and physical activity: Impact on immune function, CNS development and psychopathology

Evidence suggests that maternal and fetal immune dysfunction may impact fetal brain development and could play a role in neurodevelopmental disorders, although the definitive pathophysiological mechanisms are still not completely understood. Stress, malnutrition and physical inactivity are three maternal behavioral lifestyle factors that can influence immune and central nervous system (CNS) functions in both the mother and fetus, and may therefore, increase risk for neurodevelopmental/psychiatric disorders. First, we will briefly review some aspects of maternal-fetal immune system interactions and development of immune tolerance. Second, we will discuss the bidirectional communication between the immune system and CNS and the pathways by which immune dysfunction could contribute to neurodevelopmental disorders. Third, we will discuss the effects of prenatal stress and malnutrition (over and undernutrition) on perinatal programming of the CNS and immune system, and how this might influence neurodevelopment. Finally, we will discuss the beneficial impact of physical fitness during pregnancy on the maternal-fetal unit and infant and how regular physical activity and exercise can be an effective buffer against stress- and inflammatory-related disorders. Although regular physical activity has been shown to promote neuroplasticity and an anti-inflammatory state in the adult, there is a paucity of studies evaluating its impact on CNS and immune function during pregnancy. Implementing stress reduction, proper nutrition and ample physical activity during pregnancy and the childbearing period may be an efficient strategy to counteract the impact of maternal stress and malnutrition/obesity on the developing fetus. Such behavioral interventions could have an impact on early development of the CNS and immune system and contribute to the prevention of neurodevelopmental and psychiatric disorders. Further research is needed to elucidate this relationship and the underlying mechanisms of protection. This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.

Intestinal inflammation in a murine model of autism spectrum disorders

Autism spectrum disorder (ASD) is a cluster of neurodevelopmental disorders characterized by impairments in communication, social interest and stereotypical behaviour. Dysfunction of the intestinal tract is reported in patients with ASD and implicated in the development and severity of ASD symptoms. However, more research is required to investigate the association of intestinal problems with ASD and the potential underlying mechanisms. The purpose of this study was to investigate comorbid symptoms of intestinal inflammation in a murine model of ASD induced by prenatal exposure to valproic acid (VPA). Pregnant BALB/c females were treated subcutaneously with 600 mg/kg VPA or phosphate buffered saline on gestational day 11. Offspring were housed with their mother until weaning on postnatal day 21 (P21). All pups were exposed to a social behaviour test on P28. Inflammatory correlates and activity of the serotonergic system were measured in brain and intestinal tissue. Here we demonstrate, in addition to reduced social behaviour and increased expression of neuroinflammatory markers in the brain, that VPA in utero- exposed male offspring showed epithelial cell loss and neutrophil infiltration in the intestinal tract. Furthermore, reduced levels of serotonin were not only observed the prefrontal cortex and amygdala of VPA in utero- exposed males, but also in the small intestine. Overall, we demonstrate that gender-specific inflammatory conditions are present in the small intestines of VPA in utero- exposed mice and are accompanied by a disturbed serotonergic system in the brain as well as in the intestinal tract.

Redox Regulation and the Autistic Spectrum: Role of Tryptophan Catabolites, Immuno-inflammation, Autoimmunity and the Amygdala

The autistic spectrum disorders (ASD) form a set of multi-faceted disorders with significant genetic, epigenetic and environmental determinants. Oxidative and nitrosative stress (O&NS), immuno-inflammatory pathways, mitochondrial dysfunction and dysregulation of the tryptophan catabolite (TRYCATs) pathway play significant interactive roles in driving the early developmental etiology and course of ASD. O&NS interactions with immuno-inflammatory pathways mediate their effects centrally via the regulation of astrocyte and microglia responses, including regional variations in TRYCATs produced. Here we review the nature of these interactions and propose an early developmental model whereby different ASD genetic susceptibilities interact with environmental and epigenetic processes, resulting in glia biasing the patterning of central interarea interactions. A role for decreased local melatonin and N-acetylserotonin production by immune and glia cells may be a significant treatment target.

Inflammatory macrophage phenotype in BTBR T+tf/J mice

Although autism is a behaviorally defined disorder, many studies report an association with increased pro-inflammatory cytokine production. Recent characterization of the BTBR T+tf/J (BTBR) inbred mouse strain has revealed several behavioral characteristics including social deficits, repetitive behavior, and atypical vocalizations which may be relevant to autism. We therefore hypothesized that, asocial BTBR mice, which exhibit autism-like behaviors, may have an inflammatory immune profile similar to that observed in children with autism. The objectives of this study were to characterize the myeloid immune profile of BTBR mice and to explore their associations with autism-relevant behaviors. C57BL/6J (C57) mice and BTBR mice were tested for social interest and repetitive self-grooming behavior. Cytokine production was measured in bone-marrow derived macrophages incubated for 24 h in either growth media alone, LPS, IL-4/LPS, or IFNγ/LPS to ascertain any M1/M2 skewing. After LPS stimulation, BTBR macrophages produced higher levels of IL-6, MCP-1, and MIP-1α and lower IL-10 (p < 0.01) than C57 mice, suggesting an exaggerated inflammatory profile. After exposure to IL-4/LPS BTBR macrophages produced less IL-10 (p < 0.01) than C57 macrophages and more IL-12p40 (p < 0.01) suggesting poor M2 polarization. Levels of IL-12(p70) (p < 0.05) were higher in BTBR macrophages after IFNγ/LPS stimulation, suggesting enhanced M1 polarization. We further observed a positive correlation between grooming frequency, and production of IL-12(p40), IL-12p70, IL-6, and TNFα (p < 0.05) after treatment with IFNγ/LPS across both strains. Collectively, these data suggest that the asocial BTBR mouse strain exhibits a more inflammatory, or M1, macrophage profile in comparison to the social C57 strain. We have further demonstrated a relationship between this relative increase in inflammation and repetitive grooming behavior, which may have relevance to repetitive and stereotyped behavior of autism.

Autism: the micro-movement perspective

The current assessment of behaviors in the inventories to diagnose autism spectrum disorders (ASD) focus on observation and discrete categorizations. Behaviors require movements, yet measurements of physical movements are seldom included. Their inclusion however, could provide an objective characterization of behavior to help unveil interactions between the peripheral and the central nervous systems (CNSs). Such interactions are critical for the development and maintenance of spontaneous autonomy, self-regulation, and voluntary control. At present, current approaches cannot deal with the heterogeneous, dynamic and stochastic nature of development. Accordingly, they leave no avenues for real time or longitudinal assessments of change in a coping system continuously adapting and developing compensatory mechanisms. We offer a new unifying statistical framework to reveal re-afferent kinesthetic features of the individual with ASD. The new methodology is based on the non-stationary stochastic patterns of minute fluctuations (micro-movements) inherent to our natural actions. Such patterns of behavioral variability provide re-entrant sensory feedback contributing to the autonomous regulation and coordination of the motor output. From an early age, this feedback supports centrally driven volitional control and fluid, flexible transitions between intentional and spontaneous behaviors. We show that in ASD there is a disruption in the maturation of this form of proprioception. Despite this disturbance, each individual has unique adaptive compensatory capabilities that we can unveil and exploit to evoke faster and more accurate decisions. Measuring the kinesthetic re-afference in tandem with stimuli variations we can detect changes in their micro-movements indicative of a more predictive and reliable kinesthetic percept. Our methods address the heterogeneity of ASD with a personalized approach grounded in the inherent sensory-motor abilities that the individual has already developed.

Strategies to develop putative biomarkers to characterize the female phenotype with autism spectrum disorders

Current observational inventories used to diagnose autism spectrum disorders (ASD) apply similar criteria to females and males alike, despite developmental differences between the sexes. Recent work investigating the chronology of diagnosis in ASD has raised the concern that females run the risk of receiving a delayed diagnosis, potentially missing a window of opportunity for early intervention. Here, we retake this issue in the context of the objective measurements of natural behaviors that involve decision-making processes. Within this context, we quantified movement variability in typically developing (TD) individuals and those diagnosed with ASD across different ages. We extracted the latencies of the decision movements and velocity-dependent parameters as the hand movements unfolded for two movement segments within the reach: movements intended toward the target and withdrawing movements that spontaneously, without instruction, occurred incidentally. The stochastic signatures of the movement decision latencies and the percent of time to maximum speed differed between males and females with ASD. This feature was also observed in the empirically estimated probability distributions of the maximum speed values, independent of limb size. Females with ASD showed different dispersion than males with ASD. The distinctions found for females with ASD were better appreciated compared with those of TD females. In light of these results, behavioral assessment of autistic traits in females should be performed relative to TD females to increase the chance of detection.

Malaise, melancholia and madness: the evolutionary legacy of an inflammatory bias

Evolutionary imperatives bred a vigorous and highly orchestrated behavioral and immune response to the microbial world that served to promote species survival and propagation. The resultant legacy is an inflammatory bias which goes largely unchecked in the modern world and is provoked not only by pathogens but also now by people. In this commentary, the authors' contributions to the special issue on Inflammation and Mental Health are described, beginning with the origins of the inflammatory bias, its roots in genetic predispositions to behavioral adaptations and ultimately maladaptations, and its consequences on the developing brain. In addition, the mechanisms by which the immune system engages behavior are described including a central role for the inflammasome which may serve to link psychological stress with inflammatory and behavioral responses. Neurotransmitter systems that mediate effects of the immune system on behavior are also described along with interactions of the inflammatory bias with depression and their convergent impact on the response to stress and medical illness. Finally, translational implications are discussed including data from a clinical trial using a cytokine antagonist in depressed patients, which suggests an interaction of the inflammatory bias with other evolutionary legacies including those related to food consumption and their modern consequences of obesity and the metabolic syndrome. Taken together, the articles offer a sampling of the rich literature that has evolved regarding the role of the immune system in behavioral disorders. The grounding of this relationship in our evolutionary past may serve to inform future research both theoretically and therapeutically.

Immune dysregulation in autism spectrum disorder

Autism spectrum disorder (ASD) is a highly heterogeneous disorder diagnosed based on the presence and severity of core abnormalities in social communication and repetitive behavior, yet several studies converge on immune dysregulation as a feature of ASD. Widespread alterations in immune molecules and responses are seen in the brains and periphery of ASD individuals, and early life immune disruptions are associated with ASD. This chapter discusses immune-related environmental and genetic risk factors for ASD, emphasizing population-wide studies and animal research that reveal potential mechanistic pathways involved in the development of ASD-related symptoms. It further reviews immunologic pathologies seen in ASD individuals and how such abnormalities can impact neurodevelopment and behavior. Finally, it evaluates emerging evidence for an immune contribution to the pathogenesis of ASD and a potential role for immunomodulatory effects in current treatments for ASD.