Frequency of CD4+CD25high regulatory T cells in the peripheral blood of Egyptian children with autism

Examining the association between autism spectrum disorder and atopic eczema: meta-analysis of current evidence

OBJECTIVES

This study aims to investigate the association between autism spectrum disorder (ASD) and atopic eczema (AE), shedding light on potential associations and underlying mechanisms.

METHODS

A comprehensive review of literature was conducted to identify relevant studies published up to August 2023. Various electronic databases, including PubMed, Embase, Scopus, Web of Science, and Cochrane, were searched using specific keywords related to ASD and AE.

RESULTS

The meta-analysis covered a total of 30 studies. The first analysis included 23 studies with a combined total of 147430 eczema patients in the ASD group and 8895446 eczema patients in non-ASD group. We calculated the risk ratio of eczema in ASD and non-ASD groups, which revealed a significantly higher risk of eczema in patients with ASD (RR 1.34; 95% CI 1.03, 1.76). The second analysis included seven studies with a combined total of 3570449 ASD patients in the AE group and 3253973 in the non-Eczema group. The risk ratio of ASD in the Eczema and Non-Eczema groups showed an insignificantly increased risk of ASD in patients with eczema (RR 1.67; 95% CI 0.91, 3.06).

CONCLUSION

This study underscores the possible link between ASD and atopic eczema, shedding light on their potential association.

IMPACT

Our study conducted a meta-analysis on the association between autism spectrum disorder (ASD) and atopic eczema (AE), shedding light on potential associations and underlying mechanisms. The review we conducted covered a total of 30 studies. This study underscores the possible link between ASD and atopic eczema, shedding light on their potential association.

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

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

The relationship of immune cells with autism spectrum disorder: a bidirectional Mendelian randomization study

BACKGROUND

Observational studies have indicated a correlation between immunological inflammation and the risk of autism spectrum disorder (ASD). However, the causal relationship between immunological inflammation and ASD remains uncertain.

METHODS

Immunity-wide data sources were retrieved from the GWAS catalog. Genetic summary data on ASD were retrieved from two independent GWAS. We performed two independent bi-directional, two-sample Mendelian randomization (MR) analyses and a meta-analysis based on the two independent MR estimates to assess the causal relationship between ASD and immune cell signatures.

RESULTS

We have discovered 26 potential correlations between genetic predisposition in the immunophenotypes and ASD. The meta-analysis of the two inverse variance weighted (IVW)-produced estimates provided further evidence supporting the potential causal relationship between immunophenotypes and ASD. Based on the findings of the reverse MR analysis, it was determined that there are two potential negative causal relationships between ASD and immunophenotypes. However, the meta-analysis of the two IVW-derived MR estimates indicated that immunophenotypes were not significantly influenced by ASD (OR = 0.87, 95% CI = 0.73 -1.03, P = 0.09; OR = 0.91, 95% CI = 0.81-1.01, P = 0.08).

CONCLUSIONS

This study expanded immune cell subtypes that were potentially causally associated with ASD risk as well as identified ASD-specific immune cell subtypes. The discovery has the potential to lead to earlier detection and more effective treatment techniques.

Prenatal and postnatal neuroimmune interactions in neurodevelopmental disorders

The intricate relationship between immune dysregulation and neurodevelopmental disorders (NDDs) has been observed across the stages of both prenatal and postnatal development. In this Review, we provide a comprehensive overview of various maternal immune conditions, ranging from infections to chronic inflammatory conditions, that impact the neurodevelopment of the fetus during pregnancy. Furthermore, we examine the presence of immunological phenotypes, such as immune-related markers and coexisting immunological disorders, in individuals with NDDs. By delving into these findings, we shed light on the potential underlying mechanisms responsible for the high occurrence of immune dysregulation alongside NDDs. We also discuss current mouse models of NDDs and their contributions to our understanding of the immune mechanisms underlying these diseases. Additionally, we discuss how neuroimmune interactions contribute to shaping the manifestation of neurological phenotypes in individuals with NDDs while also exploring potential avenues for mitigating these effects.

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

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

Aflatoxin B1 Exposure Aggravates Neurobehavioral Deficits and Immune Dysfunctions of Th1, Th9, Th17, Th22, and T Regulatory Cell-Related Transcription Factor Signaling in the BTBR T+Itpr3tf/J Mouse Model of Autism

Autism spectrum disorder (ASD) is a neurodevelopmental disease characterized by impaired communication, reciprocal social interactions, restricted sociability deficits, and stereotyped behavioral patterns. Environmental factors and genetic susceptibility have been implicated in an increased risk of ASD. Aflatoxin B1 (AFB1) is a typical contaminant of food and feed that causes severe immune dysfunction in humans and animals. Nevertheless, the impact of ASD on behavioral and immunological responses has not been thoroughly examined. To investigate this phenomenon, we subjected BTBR T+Itpr3tf/J (BTBR) mice to AFB1 and evaluated their marble-burying and self-grooming behaviors and their sociability. The exposure to AFB1 resulted in a notable escalation in marble-burying and self-grooming activities while concurrently leading to a decline in social contacts. In addition, we investigated the potential molecular mechanisms that underlie the impact of AFB1 on the production of Th1 (IFN-γ, STAT1, and T-bet), Th9 (IL-9 and IRF4), Th17 (IL-17A, IL-21, RORγT, and STAT3), Th22 (IL-22, AhR, and TNF-α), and T regulatory (Treg) (IL-10, TGF-β1, and FoxP3) cells in the spleen. This was achieved using RT-PCR and Western blot analyses to assess mRNA and protein expression in brain tissue. The exposure to AFB1 resulted in a significant upregulation of various immune-related factors, including IFN-γ, STAT1, T-bet, IL-9, IRF4, IL-17A, IL-21, RORγ, STAT3, IL-22, AhR, and TNF-α in BTBR mice. Conversely, the production of IL-10, TGF-β1, and FoxP3 by CD4+ T cells was observed to be downregulated. Exposure to AFB1 demonstrated a notable rise in Th1/Th9/Th22/Th17 levels and a decrease in mRNA and protein expression of Treg. The results above underscore the significance of AFB1 exposure in intensifying neurobehavioral and immunological abnormalities in BTBR mice, hence indicating the necessity for a more comprehensive investigation into the contribution of AFB1 to the development of ASD.

Link between the skin and autism spectrum disorder

Autism spectrum disorder (ASD) is a common neurological disorder. Although the etiologies of ASD have been widely speculated, evidence also supports the pathogenic role of cutaneous inflammation in autism. The prevalence of ASD is higher in individuals with inflammatory dermatoses than in those without inflammatory diseases. Anti-inflammation therapy alleviates symptoms of ASD. Recent studies suggest a link between epidermal dysfunction and ASD. In the murine model, mice with ASD display epidermal dysfunction, accompanied by increased expression levels of proinflammatory cytokines in both the skin and the brain. Children with ASD, which develops in their early lifetime, also exhibit altered epidermal function. Interestingly, improvement in epidermal function alleviates some symptoms of ASD. This line of evidence suggests a pathogenic role of cutaneous dysfunction in ASD. Either an improvement in epidermal function or effective treatment of inflammatory dermatoses can be an alternative approach to the management of ASD. We summarize here the current evidence of the association between the skin and ASD.

Exploring potential impacts of pregnancy-related maternal immune activation and extracellular vesicles on immune alterations observed in autism spectrum disorder

Autism Spectrum Disorder (ASD) is a set of neurodevelopmental disorders usually observed in early life, with impacts on behavioral and social skills. Incidence of ASD has been dramatically increasing worldwide, possibly due to increase in awareness/diagnosis as well as to genetic and environmental triggers. Currently, it is estimated that ∼1% of the world population presents ASD symptoms. In addition to its genetic background, environmental and immune-related factors also influence the ASD etiology. In this context, maternal immune activation (MIA) has recently been suggested as a component potentially involved in ASD development. In addition, extracellular vesicles (EVs) are abundant at the maternal-fetal interface and are actively involved in the immunoregulation required for a healthy pregnancy. Considering that alterations in concentration and content of EVs have also been associated with ASD, this article raises a debate about the potential roles of EVs in the processes surrounding MIA. This represents the major differential of the present review compared to other ASD studies. To support the suggested correlations and hypotheses, findings regarding the roles of EVs during pregnancy and potential influences on ASD are discussed, along with a review and update concerning the participation of infections, cytokine unbalances, overweight and obesity, maternal anti-fetal brain antibodies, maternal fever, gestational diabetes, preeclampsia, labor type and microbiota unbalances in MIA and ASD.

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.

Activation of the Monocyte/Macrophage System and Abnormal Blood Levels of Lymphocyte Subpopulations in Individuals with Autism Spectrum Disorder: A Systematic Review and Meta-Analysis

Autism spectrum disorder (ASD) is a neurodevelopmental condition with a so far unknown etiology. Increasing evidence suggests that a state of systemic low-grade inflammation may be involved in the pathophysiology of this condition. However, studies investigating peripheral blood levels of immune cells, and/or of immune cell activation markers such as neopterin are lacking and have provided mixed findings. We performed a systematic review and meta-analysis of studies comparing total and differential white blood cell (WBC) counts, blood levels of lymphocyte subpopulations and of neopterin between individuals with ASD and typically developing (TD) controls (PROSPERO registration number: CRD CRD42019146472). Online searches covered publications from 1 January 1994 until 1 March 2022. Out of 1170 publication records identified, 25 studies were finally included. Random-effects meta-analyses were carried out, and sensitivity analyses were performed to control for potential moderators. Results: Individuals with ASD showed a significantly higher WBC count (k = 10, g = 0.29, p = 0.001, I2 = 34%), significantly higher levels of neutrophils (k = 6, g = 0.29, p = 0.005, I2 = 31%), monocytes (k = 11, g = 0.35, p < 0.001, I2 = 54%), NK cells (k = 7, g = 0.36, p = 0.037, I2 = 67%), Tc cells (k = 4, g = 0.73, p = 0.021, I2 = 82%), and a significantly lower Th/Tc cells ratio (k = 3, g = −0.42, p = 0.008, I2 = 0%), compared to TD controls. Subjects with ASD were also characterized by a significantly higher neutrophil-to-lymphocyte ratio (NLR) (k = 4, g = 0.69, p = 0.040, I2 = 90%), and significantly higher neopterin levels (k = 3, g = 1.16, p = 0.001, I2 = 97%) compared to TD controls. No significant differences were found with respect to the levels of lymphocytes, B cells, Th cells, Treg cells, and Th17 cells. Sensitivity analysis suggested that the findings for monocyte and neutrophil levels were robust, and independent of other factors, such as medication status, diagnostic criteria applied, and/or the difference in age or sex between subjects with ASD and TD controls. Taken together, our findings suggest the existence of a chronically (and systemically) activated inflammatory response system in, at least, a subgroup of individuals with ASD. This might have not only diagnostic, but also, therapeutic implications. However, larger longitudinal studies including more homogeneous samples and laboratory assessment methods and recording potential confounding factors such as body mass index, or the presence of comorbid psychiatric and/or medical conditions are urgently needed to confirm the findings.

Construction of an immune-related ceRNA network to screen for potential diagnostic markers for autism spectrum disorder

Purpose: The diagnosis of autism spectrum disorder (ASD) is reliant on evaluation of patients' behavior. We screened the potential diagnostic and therapeutic targets of ASD through bioinformatics analysis. Methods: Four ASD-related datasets were downloaded from the Gene Expression Omnibus database. The "limma" package was employed to analyze differentially expressed messenger (m)RNAs, long non-coding (lnc)RNAs, and micro (mi)RNAs between ASD patients and healthy volunteers (HVs). We constructed a competing endogenous-RNA (ceRNA) network. Enrichment analyses of key genes were undertaken using the Gene Ontology database and Kyoto Encyclopedia of Genes and Genomes database. The ImmucellAI database was used to analyze differences in immune-cell infiltration (ICI) in ASD and HV samples. Synthetic analyses of the ceRNA network and ICI was done to obtain a diagnostic model using LASSO regression analysis. Analyses of receiver operating characteristic (ROC) curves were done for model verification. Results: The ceRNA network comprised 49 lncRNAs, 30 miRNAs, and 236 mRNAs. mRNAs were associated with 41 cellular components, 208 biological processes, 39 molecular functions, and 35 regulatory signaling pathways. Significant differences in the abundance of 10 immune-cell species between ASD patients and HVs were noted. Using the ceRNA network and ICI results, we constructed a diagnostic model comprising five immune cell-associated genes: adenosine triphosphate-binding cassette transporter A1 (ABCA1), DiGeorge syndrome critical region 2 (DGCR2), glucose-fructose oxidoreductase structural domain gene 1 (GFOD1), glutaredoxin (GLRX), and SEC16 homolog A (SEC16A). The diagnostic performance of our model was revealed by an area under the ROC curve of 0.923. Model verification was done using the validation dataset and serum samples of patients. Conclusion: ABCA1, DGCR2, GFOD1, GLRX, and SEC16A could be diagnostic biomarkers and therapeutic targets for ASD.

Assessment of Expression of Regulatory T Cell Differentiation Genes in Autism Spectrum Disorder

Dysfunction of regulatory T cells (Tregs) has been shown to affect the etiology of autism spectrum disorder (ASD). Differentiation of this group of T cells has been found to be regulated by a group of long non-coding RNAs (lncRNAs). In this study, we have examined the expression of five lncRNAs that regulate this process in the blood samples of ASD cases compared with controls. These lncRNAs were FOXP3 regulating long intergenic non-coding RNA (FLICR), MAF transcriptional regulator RNA (MAFTRR), NEST (IFNG-AS1), RNA component of mitochondrial RNA processing endoribonuclease (RMRP), and Th2 cytokine locus control region (TH2-LCR). Expression of RMRP was significantly lower in total ASD cases compared to controls [expression ratio (95% CI) = 0.11 (0.08-0.18), adjusted P-value < 0.0001]. This pattern was also detected in both men and women cases compared with corresponding controls [expression ratio (95% CI) = 0.15 (0.08-0.29) and 0.08 (0.03-0.2), respectively]. Likewise, expression of NEST was reduced in total cases and cases among men and women compared with corresponding controls [expression ratio (95% CI) = 0.2 (0.14-0.28); 0.22 (0.12-0.37); and 0.19 (0.09-0.43), respectively; adjusted P-value < 0.0001]. Lastly, FLICR was downregulated in total cases and cases among both boys and girls compared with matched controls [expression ratio (95% CI) = 0.1 (0.06-0.19); 0.19 (0.08-0.46); and 0.06 (0.01-0.21), respectively; adjusted P-value < 0.0001]. These three lncRNAs had appropriate diagnostic power for differentiation of ASD cases from controls. Cumulatively, our study supports dysregulation of Treg-related lncRNAs in patients with ASD and suggests these lncRNAs as proper peripheral markers for ASD.

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.

Regulatory T lymphocytes/Th17 lymphocytes imbalance in autism spectrum disorders: evidence from a meta-analysis

Background

Immune system dysfunction has been proposed to play a critical role in the pathophysiology of autism spectrum disorders (ASD). Conflicting reports of lymphocyte subpopulation abnormalities have been described in numerous studies of patients with ASD. To better define lymphocytes abnormalities in ASD, we performed a meta-analysis of the lymphocyte profiles from subjects with ASD.

Methods

We used the PRISMA recommendations to query PubMed, Embase, PsychoINFO, BIOSIS, Science Direct, Cochrane CENTRAL, and Clinicaltrials.gov for terms related to clinical diagnosis of ASD and to lymphocytes’ populations. We selected studies exploring lymphocyte subpopulations in children with ASD. The search protocol has been registered in the international Prospective Register of Systematic Reviews (CRD42019121473).

Results

We selected 13 studies gathering 388 ASD patients and 326 healthy controls. A significant decrease in the CD4+ lymphocyte was found in ASD patients compared to controls [− 1.51 (95% CI − 2.99; − 0.04) p = 0.04] (I² = 96% [95% CI 94.6, 97.7], p < 0.01). No significant difference was found for the CD8+ T, B and natural killer lymphocytes. Considering the CD4+ subpopulation, there was a significant decrease in regulatory T lymphocytes (Tregs) in ASD patients (n = 114) compared to controls (n = 107) [− 3.09 (95% CI − 4.41; − 1.76) p = 0.0001]; (I² = 90.9%, [95% CI 76.2, 96.5], p < 0.0001) associated with an increase oin the Th17 lymphocytes (ASD; n = 147 controls; n = 128) [2.23 (95% CI 0.79; 3.66) p = 0,002] (I² = 95.1% [95% CI 90.4, 97.5], p < 0.0001).

Limitations

Several factors inducing heterogeneity should be considered. First, differences in the staining method may be responsible for a part in the heterogeneity of results. Second, ASD population is also by itself heterogeneous, underlying the need of studying sub-groups that are more homogeneous.

Conclusion

Our meta-analysis indicates defects in CD4+ lymphocytes, specifically decrease oin Tregs and increase in Th17 in ASD patients and supports the development of targeted immunotherapies in the field of ASD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13229-021-00472-4.

Rescue of maternal immune activation-induced behavioral abnormalities in adult mouse offspring by pathogen-activated maternal Treg cells

Maternal immune activation (MIA) induced by lipopolysaccharides or polyinosinic:polycytidylic acid injections can induce behavioral abnormalities in adult mouse offspring. Here, we used the soluble tachyzoite antigen from Toxoplasma gondii, a parasite that infects approximately two billion people, to induce MIA in mice. The adult male offspring showed autism-relevant behaviors and abnormal brain microstructure, along with a pro-inflammatory T-cell immune profile in the periphery and upregulation of interleukin-6 in brain astrocytes. We show that adoptive transfer of regulatory T (T_reg) cells largely reversed these MIA-induced phenotypes. Notably, pathogen-activated maternal T_reg cells showed greater rescue efficacy than those from control donors. Single-cell RNA sequencing identified and characterized a unique group of pathogen-activated T_reg cells that constitute 32.6% of the pathogen-activated maternal T_reg population. Our study establishes a new preclinical parasite-mimicking MIA model and suggests therapeutic potential of adoptive T_reg cell transfer in neuropsychiatric disorders associated with immune alterations.

5-Aminoisoquinolinone, a PARP-1 Inhibitor, Ameliorates Immune Abnormalities through Upregulation of Anti-Inflammatory and Downregulation of Inflammatory Parameters in T Cells of BTBR Mouse Model of Autism

Autism spectrum disorder (ASD) covers a range of neurodevelopmental disorders involving impairments in communication and repetitive and stereotyped patterns of behavior and reciprocal social interaction. 5-Aminoisoquinolinone (5-AIQ), a PARP-1 inhibitor, has neuroprotective and anti-inflammatory effects. We investigated the influence of 5-AIQ-treatment in BTBR T+ Itpr3tf/J (BTBR) mice as an autism model and used flow cytometry to assess the effect of 5-AIQ on FOXP3, Helios, GATA3, IL-9, IL-10 and IL-17A production by CXCR6+ and CD4+ T cells in the spleen. We also confirmed the effect of 5-AIQ treatment on expression of FOXP3, Helios, GATA3, IL-17A, IL-10, and IL-9 mRNA and protein expression levels in the brain tissue by quantitative PCR and western blotting. Our results demonstrated that 5-AIQ-treated BTBR mice had significantly increased numbers of CXCR6+FOXP3+, CXCR6+IL-10+, and CXCR6+Helios+ cells and decreased numbers of CD4+GATA3+, CD4+IL-9+, and CD4+IL-17A+ cells as compared with those in untreated BTBR mice. Our results further demonstrated that treatment with 5-AIQ in BTBR mice increased expression for FOXP3, IL-10, and Helios, and decreased expression for GATA3, IL-17A, and IL-9 mRNA. Our findings support the hypotheses that 5-AIQ has promising novel therapeutic effects on neuroimmune dysfunction in autism and is associated with modulation of Treg and Th17 cells.

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.

Autism Spectrum Disorders: Role of Pre- and Post-Natal GammaDelta (γδ) T Cells and Immune Regulation

BACKGROUND

It is widely accepted that alterations in immune functioning are an important aspect of the pathoetiology and pathophysiology of autism spectrum disorders (ASD). A relatively under-explored aspect of these alterations is the role of gammaDelta (γδ) T cells, prenatally and in the postnatal gut, which seem important hubs in driving the course of ASD.

METHODS

The present article describes the role of γδ T cells in ASD, including their interactions with other immune cells shown to be altered in this spectrum of conditions, including natural killer cells and mast cells.

RESULTS

Other risk factors in ASD, such as decreased vitamins A & D, as well as toxin-associated activation of the aryl hydrocarbon receptor, may also be intimately linked to γδ T cells, and alterations in the regulation of these cells. A growing body of data has highlighted an important role for alterations in mitochondria functioning in the regulation of immune cells, including natural killer cells and mast cells. This is an area that requires investigation in γδ T cells and their putative subtypes.

CONCLUSION

It is also proposed that maternal stress may act through alterations in the maternal microbiome, leading to changes in how the balance of short-chain fatty acids, such as butyrate, which may act to regulate the placenta and foetal development. Following an overview of previous research on immune, especially γδ T cells, effects in ASD, the future research implications are discussed in detail.

T cell populations in children with autism spectrum disorder and co-morbid gastrointestinal symptoms

Children with ASD are more likely to experience gastrointestinal (GI) symptoms than typically-developed children. Numerous studies have reported immune abnormalities and inflammatory profiles in the majority of individuals with ASD. Immune dysfunction is often hypothesized as a driving factor in many GI diseases and it has been suggested that it is more apparent in children with ASD that exhibit GI symptoms. In this study we sought to characterize peripheral T cell subsets in children with and without GI symptoms, compared to healthy typically-developing children. Peripheral blood mononuclear cells were isolated from participants, who were categorized into three groups: children with ASD who experience GI symptoms (n ​= ​14), children with ASD who do not experience GI symptoms (n ​= ​10) and typically-developing children who do not experience GI symptoms (n ​= ​15). In order to be included in the GI group, GI symptoms such as diarrhea, constipation, and/or pain while defecating, had to be present in the child regularly for the past 6 months; likewise, in order to be placed in the no GI groups, bowel movements could not include the above symptoms present throughout development. Cells were assessed for surface markers and intracellular cytokines to identify T cell populations. Children with ASD and GI symptoms displayed elevated TH17 populations (0.757% ​± ​0.313% compared to 0.297% ​± ​0.197), while children with ASD who did not experience GI symptoms showed increased frequency of TH2 populations (2.02% ​± ​1.08% compared to 1.01% ​± ​0.58%). Both ASD groups showed evidence of reduced gut homing regulatory T cell populations compared to typically developing children (ASDGI:1.93% ​± ​0.75% and ASDNoGI:1.85% ​± ​0.89 compared to 2.93% ​± ​1.16%). Children with ASD may have deficits in immune regulation that lead to differential inflammatory T cell subsets that could be linked to associated co-morbidities.

Inhibition of tyrosine kinase signaling by tyrphostin AG126 downregulates the IL-21/IL-21R and JAK/STAT pathway in the BTBR mouse model of autism

Autism spectrum disorder (ASD) comprises a broad range of neurodevelopmental disorders that are associated with deficits in social interaction and communication. The tyrosine kinase inhibitor tyrphostin AG126 represents a promising therapeutic agent for several neuroinflammatory disorders. There are currently no treatments available that can improve ASD and we previously showed that AG126 treatment exerts beneficial effects on BTBR T⁺ Itpr3^tf/J (BTBR) mice, a model for autism that shows the core features of ASD; however, the immunological mechanisms and molecular targets associated with this effect were previously unclear. This study was undertaken to delineate the neuroprotective effect of AG126 on BTBR mice. Here, using this mouse model, we investigated the effects of AG126 administration on IL-21R, IL-21, IL-22, TNF-α, NOS2, STAT3, IL-27, and Foxp3 production by CD8⁺ T cells in the spleen by flow cytometry. We further explored the mRNA and protein expression of IL-21, IL-22, IL-1β, TNF-α, NOS2, JAK1, STAT3, IL-27, and Foxp3 in brain tissue by RT-PCR, and western blotting. We found that BTBR mice treated with AG126 exhibited significant decreases in IL-21R-, IL-21-, IL-22-, TNF-α-, NOS2-, STAT3-producing, and increases in IL-27- and Foxp3-producing, CD8⁺ T cells. Our results further demonstrated that AG126 treatment effectively decreased IL-21, IL-22, IL-1β, TNF-α, NOS2, JAK1, and STAT3, and increased IL-27 and Foxp3 mRNA and protein expression in brain tissues. Our findings suggest that AG126 elicits a neuroprotective response through downregulation of the IL-21/IL-21R and JAK/STAT pathway in BTBR mice, which could represent a promising novel therapeutic target for ASD treatment.

Altered frequencies of Th17 and Treg cells in children and adolescents with obsessive-compulsive disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is a debilitating neuropsychiatric disorder with an etiopathophysiology that seems to include immune alterations. Previous studies have suggested that variations in the levels of circulating T cell subpopulations may be involved in psychiatric diseases. However, the role of these cells in OCD remains unexplored. Hence, the present study aimed to examine the levels of T helper 1 (Th1), Th2, Th17 and regulatory T (Treg) cells in patients with early-onset OCD and healthy controls.

METHODS

The assessment was performed in 99 children and adolescents with OCD and 46 control subjects. The percentages of circulating Th1, Th2, Th17 and Treg cells were evaluated using flow cytometry.

RESULTS

OCD patients had significantly higher levels of Th17 cells and lower percentages of Treg cells than healthy controls (p = 0.001 and p = 0.005, respectively). Furthermore, levels of Th17 cells progressively increased with the duration (p = 0.005) and severity of OCD (p = 0.008), whereas the percentages of Treg cells significantly declined with the duration of the disorder (p = 1.8 × 10^-5).

CONCLUSIONS

These results provide more evidence of the involvement of immune dysregulation, specifically an imbalance in the levels of circulating T helper and regulatory T cells, in the pathophysiology of early-onset OCD.

Rapid Communication: Plasma Interleukin-35 in Children with Autism

In autism spectrum disorders (ASD) many individuals have co-morbid immune dysregulation that can lead to inflammation in the brain and periphery. The novel cytokine interleukin (IL)-35 has described anti-inflammatory properties; however, the plasma levels of IL-35 in children with ASD have never been investigated. The plasma levels of IL-35 were measured by an enzyme-linked immunosorbent assay in 30 children with ASD and 39 typically developing (TD) controls. In the current study, we found that plasma IL-35 levels were significantly decreased in children with ASD compared with TD children. Furthermore, lower IL-35 levels were associated with worse behaviors as assessed using the aberrant behavior checklist. These findings are in line with other observations of decreased regulatory cytokines such as transforming growth factor beta and IL-10 in ASD, and associations with severity of behaviors. In conclusion, regulating the expression of IL-35 may provide a new possible target for the treatment of immune issues in ASD to address an imbalance between pro- and anti-inflammatory signals that alter the behavioral phenotype.

DAPTA, a C-C chemokine receptor 5 (CCR5) antagonist attenuates immune aberrations by downregulating Th9/Th17 immune responses in BTBR T+ Itpr3tf/J mice

Autism spectrum disorder (ASD) is a prevalent neurodevelopmental disorder characterized by deficits in social interaction, communication, and repetitive behaviors. BTBR T⁺ Itpr3tf/J (BTBR) mice, a preclinical autistic model featuring ASD symptoms as defined by social relations, was used in this study. We evaluated the potentially protective effect of D-Ala-peptide T-amide (DAPTA), a selective C-C chemokine receptor 5 (CCR5) antagonist, in BTBR mice. CCR5 is considered a potential therapeutic target in different neurodegenerative disorders. BTBR and C57 mice were intraperitoneally (i.p) treated with the DAPTA (0.01 mg/kg, i.p, once daily) for 7 days. We examined the effect of DAPTA by evaluating marble burying and administering repetitive behavior tests. We employed flow cytometry to assess the effect of DAPTA on CCR5⁺, CD4⁺CCR5⁺, CCR5⁺IL-6⁺, CCR5⁺IL-9⁺, CCR5⁺IL-17A⁺, CCR5⁺RORγT⁺, CCR5⁺IL-10⁺, and CCR5⁺Foxp3⁺ in spleen cells. We further explored the effects of DAPTA on IL-6, IL-9, IL-17A, RORγT, IL-10, and Foxp3 protein and mRNA expression levels in the brain tissues. DAPTA administration significantly decreased marble burying and repetitive behavior in BTBR mice. Additionally, DAPTA treatment inhibited CCR5⁺, CD4⁺CCR5⁺, CCR5⁺IL-6⁺, CCR5⁺IL-9⁺, CCR5⁺IL-17A⁺, CCR5⁺RORγT⁺, and upregulated CCR5⁺IL-10⁺, and CCR5⁺Foxp3⁺ production. We further observed that DAPTA downregulated IL-6, IL-9, IL-17A, and RORγT, and increased IL-10 and Foxp3 protein and mRNA expression. Therefore, our results suggest that DAPTA administration represents a potential treatment strategy for patients with ASD.

The Gut-Immune-Brain Axis in Autism Spectrum Disorders; A Focus on Amino Acids

Autism spectrum disorder (ASD) is a range of neurodevelopmental conditions that affect communication and social behavior. Besides social deficits, systemic inflammation, gastrointestinal immune-related problems, and changes in the gut microbiota composition are characteristic for people with ASD. Animal models showed that these characteristics can induce ASD-associated behavior, suggesting an intimate relationship between the microbiota, gut, immune system and the brain in ASD. Multiple factors can contribute to the development of ASD, but mutations leading to enhanced activation of the mammalian target of rapamycin (mTOR) are reported frequently. Hyperactivation of mTOR leads to deficits in the communication between neurons in the brain and to immune impairments. Hence, mTOR might be a critical factor linking the gut-brain-immune axis in ASD. Pharmacological inhibition of mTOR is shown to improve ASD-associated behavior and immune functions, however, the clinical use is limited due to severe side reactions. Interestingly, studies have shown that mTOR activation can also be modified by nutritional stimuli, in particular by amino acids. Moreover, specific amino acids are demonstrated to inhibit inflammation, improve gut barrier function and to modify the microbiota composition. In this review we will discuss the gut-brain-immune axis in ASD and explore the potential of amino acids as a treatment option for ASD, either via modification of mTOR activity, the immune system or the gut microbiota composition.

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 Abnormalities in Autism Spectrum Disorder-Could They Hold Promise for Causative Treatment?

Autism spectrum disorders (ASD) are characterized by impairments in language and communication development, social behavior, and the occurrence of stereotypic patterns of behavior and interests. Despite substantial speculation about causes of ASD, its exact etiology remains unknown. Recent studies highlight a link between immune dysfunction and behavioral traits. Various immune anomalies, including humoral and cellular immunity along with abnormalities at the molecular level, have been reported. There is evidence of altered immune function both in cerebrospinal fluid and peripheral blood. Several studies hypothesize a role for neuroinflammation in ASD and are supported by brain tissue and cerebrospinal fluid analysis, as well as evidence of microglial activation. It has been shown that immune abnormalities occur in a substantial number of individuals with ASD. Identifying subgroups with immune system dysregulation and linking specific cellular immunophenotypes to different symptoms would be key to defining a group of patients with immune abnormalities as a major etiology underlying behavioral symptoms. These determinations would provide the opportunity to investigate causative treatments for a defined patient group that may specifically benefit from such an approach. This review summarizes recent insights into immune system dysfunction in individuals with ASD and discusses the potential implications for future therapies.

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.

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.

Neuroinflammation in Autism Spectrum Disorders: Role of High Mobility Group Box 1 Protein

The pathogenesis of autism spectrum disorder (ASD) likely involves genetic and environmental factors, impacting the complex neurodevelopmental and behavioral abnormalities of the disorder. Scientific research studies emerging within the past two decades suggest that immune dysfunction and inflammation have pathogenic influences through different mechanisms, all leading to both a chronic state of low grade inflammation, and alterations in the central nervous system and immune response, respectively. The high mobility group box-1 protein (HMGB1) is an inflammatory marker which has been shown to play a role in inducing and influencing neuroinflammation. Current evidences suggest a possible role in the multiple pathogenic mechanisms of ASD. The aim of this manuscript is to review the major hypothesis for ASD pathogenesis, with specific regards to the immunological ones, and to provide a comprehensive review of the current data about the association between HMGB1 and ASD. A systematic search has been carried out through Medline via Pubmed to identify all original articles published in English, on the basis of the following keywords: "HMGB1", "autism", "autism spectrum disorder", "neuroinflammation", and "child".

High monocyte level and low lymphocyte to monocyte ratio in autism spectrum disorders

Objective: This study aims to investigate the level of peripheral blood mononuclear cells and their ratios which may point to the immunological mechanisms involved in the etiopathogenesis of ASD. Method: The complete blood count parameters of the 45 ASD cases were compared with those of healthy controls.Childhood Autism Rating Scale (CARS) was performed to measure the disease severity. Results: The monocytes of ASD group were significantly higher; and the lymphocyte-to-monocyte ratio (LMR) was lower than the controls'. LMR and neutrophil-to-lymphocyte ratio were found to be predictors of ASD. The decrease in LMR (B: -0.744; P=0.035; CI: -1.431 to -0.056) and the increase in age (B: 0.432; P=0.045; CI: 0.011-0.853) were related to high CARS scores in linear regression analyses. Conclusions: The results of this study support the role of altered immune cell counts and ratios in ASD. A high monocyte level and low LMR may have diagnostic values in autism.

Serum and cerebrospinal fluid immune mediators in children with autistic disorder: a longitudinal study

BACKGROUND

The causes of autism likely involve genetic and environmental factors that influence neurobiological changes and the neurological and behavioral features of the disorder. Immune factors and inflammation are hypothesized pathogenic influences, but have not been examined longitudinally.

METHODS

In a cohort of 104 participants with autism, we performed an assessment of immune mediators such as cytokines, chemokines, or growth factors in serum and cerebrospinal fluid (n = 67) to determine potential influences of such mediators in autism.

RESULTS

As compared with 54 typically developing controls, we found no evidence of differences in the blood profile of immune mediators supportive of active systemic inflammation mechanisms in participants with autism. Some modulators of immune function (e.g., EGF and soluble CD40 ligand) were increased in the autism group; however, no evidence of group differences in traditional markers of active inflammation (e.g., IL-6, TNFα, IL-1β) were observed in the serum. Further, within-subject stability (measured by estimated intraclass correlations) of most analytes was low, indicating that a single measurement is not a reliable prospective indicator of concentration for most analytes. Additionally, in participants with autism, there was little correspondence between the blood and CSF profiles of cytokines, chemokines, and growth factors, suggesting that peripheral markers may not optimally reflect the immune status of the central nervous system. Although the relatively high fraction of intrathecal production of selected chemokines involved in monocyte/microglia function may suggest a possible relationship with the homeostatic role of microglia, control data are needed for further interpretation of its relevance in autism.

CONCLUSIONS

These longitudinal observations fail to provide support for the hypothesized role of disturbances in the expression of circulating cytokines and chemokines as an indicator of systemic inflammation in autism. ClinicalTrials.gov, NCT00298246.

The Role of the Immune System in Autism Spectrum Disorder

Autism is a neurodevelopmental disorder characterized by deficits in communication and social skills as well as repetitive and stereotypical behaviors. While much effort has focused on the identification of genes associated with autism, research emerging within the past two decades suggests that immune dysfunction is a viable risk factor contributing to the neurodevelopmental deficits observed in autism spectrum disorders (ASD). Further, it is the heterogeneity within this disorder that has brought to light much of the current thinking regarding the subphenotypes within ASD and how the immune system is associated with these distinctions. This review will focus on the two main axes of immune involvement in ASD, namely dysfunction in the prenatal and postnatal periods. During gestation, prenatal insults including maternal infection and subsequent immunological activation may increase the risk of autism in the child. Similarly, the presence of maternally derived anti-brain autoantibodies found in ~20% of mothers whose children are at risk for developing autism has defined an additional subphenotype of ASD. The postnatal environment, on the other hand, is characterized by related but distinct profiles of immune dysregulation, inflammation, and endogenous autoantibodies that all persist within the affected individual. Further definition of the role of immune dysregulation in ASD thus necessitates a deeper understanding of the interaction between both maternal and child immune systems, and the role they have in diagnosis and treatment.

FOXP3 gene variations and susceptibility to autism: A case-control study

Autism Spectrum Disorders (ASD) are a group of heterogeneous neurodevelopmental disorders associated with immune system dysregulation. There are supporting evidences for the role of Forkhead Box P3 (FOXP3) gene as a lineage specification factor of regulatory T cells in the pathogenesis of ASD. The aim of this study was to explore possible relationship between genetic variants rs2232365 and rs3761548 of FOXP3 and ASD in 523 ASD patients versus 472 control individuals. Allele frequency analyses showed significant overpresentation of rs2232365-G allele in cases versus controls. In addition, rs2232365 GG genotype was associated with ASD in dominant inheritance model. Haplotype analysis revealed no significant association of any estimated block of rs2232365/rs3761548 with ASD. Our study indicated that rs2232365 is associated with ASD.

The Microbiota, Immunoregulation, and Mental Health: Implications for Public Health

The hygiene or "Old Friends" hypothesis proposes that the epidemic of inflammatory disease in modern urban societies stems at least in part from reduced exposure to microbes that normally prime mammalian immunoregulatory circuits and suppress inappropriate inflammation. Such diseases include but are not limited to allergies and asthma; we and others have proposed that the markedly reduced exposure to these Old Friends in modern urban societies may also increase vulnerability to neurodevelopmental disorders and stress-related psychiatric disorders, such as anxiety and affective disorders, where data are emerging in support of inflammation as a risk factor. Here, we review recent advances in our understanding of the potential for Old Friends, including environmental microbial inputs, to modify risk for inflammatory disease, with a focus on neurodevelopmental and psychiatric conditions. We highlight potential mechanisms, involving bacterially derived metabolites, bacterial antigens, and helminthic antigens, through which these inputs promote immunoregulation. Though findings are encouraging, significant human subjects' research is required to evaluate the potential impact of Old Friends, including environmental microbial inputs, on biological signatures and clinically meaningful mental health prevention and intervention outcomes.

Gastrointestinal symptoms and autism spectrum disorder: links and risks - a possible new overlap syndrome

Autism spectrum disorder (ASD) is a genetically determined neurodevelopmental brain disorder presenting with restricted, repetitive patterns of behaviors, interests, and activities, or persistent deficits in social communication and social interaction. ASD is characterized by many different clinical endophenotypes and is potentially linked with certain comorbidities. According to current recommendations, children with ASD are at risk of having alimentary tract disorders - mainly, they are at a greater risk of general gastrointestinal (GI) concerns, constipation, diarrhea, and abdominal pain. GI symptoms may overlap with ASD core symptoms through different mechanisms. These mechanisms include multilevel pathways in the gut-brain axis contributing to alterations in behavior and cognition. Shared pathogenetic factors and pathophysiological mechanisms possibly linking ASD and GI disturbances, as shown by most recent studies, include intestinal inflammation with or without autoimmunity, immunoglobulin E-mediated and/or cell-mediated GI food allergies as well as gluten-related disorders (celiac disease, wheat allergy, non-celiac gluten sensitivity), visceral hypersensitivity linked with functional abdominal pain, and dysautonomia linked with GI dysmotility and gastroesophageal reflux. Dysregulation of the gut microbiome has also been shown to be involved in modulating GI functions with the ability to affect intestinal permeability, mucosal immune function, and intestinal motility and sensitivity. Metabolic activity of the microbiome and dietary components are currently suspected to be associated with alterations in behavior and cognition also in patients with other neurodegenerative diseases. All the above-listed GI factors may contribute to brain dysfunction and neuroinflammation depending upon an individual patient's genetic vulnerability. Due to a possible clinical endophenotype presenting as comorbidity of ASD and GI disorders, we propose treating this situation as an "overlap syndrome". Practical use of the concept of an overlap syndrome of ASD and GI disorders may help in identifying those children with ASD who suffer from an alimentary tract disease. Unexplained worsening of nonverbal behaviors (agitation, anxiety, aggression, self-injury, sleep deprivation) should alert professionals about this possibility. This may shorten the time to diagnosis and treatment commencement, and thereby alleviate both GI and ASD symptoms through reducing pain, stress, or discomfort. Furthermore, this may also protect children against unnecessary dietary experiments and restrictions that have no medical indications. A personalized approach to each patient is necessary. Our understanding of ASDs has come a long way, but further studies and more systematic research are warranted.

Case report: cytokine and CD4+ T-cell profiles of monozygotic twins with autism and divergent comorbidities and drug treatment

Autism spectrum disorders are neurodevelopmental disorders that are thought to be caused by a gene-by-environment interaction and in which various immune alterations are reported. We investigate CD4(+) T-cell cytokine profiles and subpopulations in 19-year-old monozygotic twins with autism and different comorbidities. CD4(+) T cells from the twin with epilepsy produce more interferon-gamma, less interleukin-17, and have an increased interferon-γ/interleukin-4 ratio. CD4(+) T cells from the twin with multiple sclerosis exhibit a cytokine profile similar to an age and gender-matched control and a higher percentage of T regulatory (Treg) cells. The twins' mother's T cells produce very high levels of both interleukin-17 and interferon-γ. Cytokine and CD4(+) T-cell abnormalities in the twins could contribute to or be a result of the manifestation of their divergent comorbidities. A proinflammatory, autoimmune-polarized cytokine profile is observed in this unique family with autism.

A possible association between elevated serum levels of brain-specific auto-antibodies and reduced plasma levels of docosahexaenoic acid in autistic children

Polyunsaturated fatty acids (PUFAs) are not only essential for energy production, but they also exhibit a range of immunomodulatory properties that progress through T cell mediated events. Autoimmunity may have a pathogenic role in a subgroup of autistic children. This study is the first to investigate the relationship between serum levels of anti-myelin basic protein (anti-MBP) brain-specific auto-antibodies and reduced plasma levels of PUFAs in autistic children. Plasma levels of PUFAs (including linoleic, alphalinolenic, arachidonic "AA" and docosahexaenoic "DHA" acids) and serum anti-MBP were measured in 80 autistic children, aged between 4 and 12 years, and 80 healthy-matched children. Autistic patients had significantly lower plasma levels of PUFAs than healthy children. On the other hand, ω6/ω3 ratio (AA/DHA) was significantly higher in autistic patients than healthy children. Low plasma DHA, AA, linolenic and linoleic acids were found in 67.5%, 50%, 40% and 35%, respectively of autistic children. On the other hand, 70% of autistic patients had elevated ω6/ω3 ratio. Autistic patients with increased serum levels of anti-MBP auto-antibodies (75%) had significantly lower plasma DHA (P<0.5) and significantly higher ω6/ω3 ratio (P<0.5) than patients who were seronegative for these antibodies. In conclusions, some autistic children have a significant positive association between reduced levels of plasma DHA and increased serum levels of anti-MBP brain-specific auto-antibodies. However, replication studies of larger samples are recommended to validate whether reduced levels of plasma PUFAs are a mere association or have a role in the induction of the production of anti-MBP in some autistic children.

Systemic auto-antibodies in children with autism

Autoimmunity to central nervous system may have a role in the pathogenesis of autism. A subset of anti-ds-DNA antibodies has been recently proved to be pathogenic to the brain as well as to the kidney. Due to the paucity of studies investigating the frequency of systemic auto-antibodies in autism, we are the first to investigate the frequency of anti-ds-DNA antibodies in a group of autistic children. The seropositivity of anti-nuclear antibodies (ANA) was also investigated. Serum anti-ds-DNA antibodies and ANA were measured in 100 autistic children, aged between 4 and 11 years, in comparison to 100 healthy-matched children. The seropositivity of anti-ds-DNA antibodies and ANA in autistic children was 34% and 25%, respectively. In addition, 42% of autistic children were seropositive for anti-ds-DNA antibodies and/or ANA. The frequencies of anti-ds-DNA antibodies and ANA in autistic children were significantly higher than that in healthy children (4% and 2%, respectively), (P<0.001 and P<0.001, respectively). Autistic children with a family history of autoimmunity (45%) had significantly higher frequency of serum anti-ds-DNA antibodies (48.9%) than patients without such a history (21.8%), P=0.008. There was a significant positive association between the seropositivity of anti-ds-DNA antibodies and ANA (P<0.001). In conclusion, anti-ds-DNA antibodies and ANA were found in the sera of a subgroup of autistic children. However, replication studies of larger samples are warranted to validate whether these antibodies are a mere association or have a pathogenic role in some autistic children.

Serum antinucleosome-specific antibody as a marker of autoimmunity in children with autism

Background

Increasing evidence of autoimmune phenomena in some individuals with autism could represent the presence of altered or inappropriate immune responses in this disorder. The role of the nucleosome in the induction of antibody response in some autoimmune-mediated tissue damage may provide novel targets for treatment. Due to the paucity of studies investigating the frequency of systemic auto-antibodies in autism, we are the first to investigate the frequency of antinucleosome-specific antibodies in a group of autistic children.

Methods

Serum antinucleosome-specific antibodies were measured by ELISA in 60 autistic children, between the ages of 3 and 12 years, in comparison to 60 healthy children. Autistic severity was assessed using the Childhood Autism Rating Scale (CARS).

Results

Autistic children had significantly higher serum antinucleosome-specific antibodies than healthy children (P <0.001). The seropositivity of antinucleosome-specific antibodies was found in 46.7% of autistic children. Autistic children with a family history of autoimmunity (40%) had a significantly higher frequency of serum antinucleosome-specific antibodies (83.3%) than patients without such a history (22.2%, P <0.001).

Conclusions

Serum levels of antinucleosome-specific antibodies were increased in some autistic children. However, these data should be treated with caution until further investigations are performed with a larger subject population to determine whether these antibodies have a role in the induction of autoimmunity in a subgroup of autistic children. The role of immunotherapy in children with autism should be also studied.

Decreased glutathione and elevated hair mercury levels are associated with nutritional deficiency-based autism in Oman

Genetic, nutrition, and environmental factors have each been implicated as sources of risk for autism. Oxidative stress, including low plasma levels of the antioxidant glutathione, has been reported by numerous autism studies, which can disrupt methylation-dependent epigenetic regulation of gene expression with neurodevelopmental consequences. We investigated the status of redox and methylation metabolites, as well as the level of protein homocysteinylation and hair mercury levels, in autistic and neurotypical control Omani children, who were previously shown to exhibit significant nutritional deficiencies in serum folate and vitamin B12. The serum level of glutathione in autistic subjects was significantly below control levels, while levels of homocysteine and S-adenosylhomocysteine were elevated, indicative of oxidative stress and decreased methionine synthase activity. Autistic males had lower glutathione and higher homocysteine levels than females, while homocysteinylation of serum proteins was increased in autistic males but not females. Mercury levels were markedly elevated in the hair of autistic subjects vs. control subjects, consistent with the importance of glutathione for its elimination. Thus, autism in Oman is associated with decreased antioxidant resources and decreased methylation capacity, in conjunction with elevated hair levels of mercury.

What is the role of vitamin D in autism?

A growing body of literature suggests that higher serum 25-hydroxyvitamin D [25(OH)D] concentrations, either in utero or in early life, may reduce the risk of autism. For example, an ecological study in the companion paper inversely correlated solar UV-B doses in the United States with prevalence of autism among those aged 6–17 y. That study proposed that vitamin D deficiency during pregnancy could account for this finding, although the findings are also consistent with childhood vitamin D deficiency contributing to the condition. Also, in a recent study, children with autism had lower serum 25(OH)D concentrations than did control subjects (19 vs. 33 ng/ml), despite parents of each group reporting the same amount of sun exposure. The same study found highly significant inverse correlations between 25(OH)D and autism rating scales and between 25(OH)D and levels of an antineuronal antibody. This finding indicates that higher serum 25(OH)D concentrations may reduce the symptoms of established autism. Because activated vitamin D, a secosteroid, upregulates DNA-repair genes, vitamin D deficiency during development may inhibit the repair of de novo DNA mutations in fetuses and infants and thus contribute to risk of autism. Vitamin D might also reduce the risk or severity of autism through its anti-inflammatory actions, antiautoimmune effects, increasing seizure threshold, increasing T-regulatory cells, protecting the mitochondria, and upregulating glutathione, which scavenges oxidative by-products and chelates (captures and excretes) heavy metals. Vitamin D deficiency during pregnancy and childhood is a widespread and growing epidemic.