Differential monocyte responses to TLR ligands in children with autism spectrum disorders

Innate immune system function following systemic RNA-interference of the Fragile X Mental Retardation 1 gene in the cricket Acheta domesticus

Fragile X syndrome (FXS), caused by a mutation in the Fragile X Mental Retardation 1 (FMR1) gene, is a common form of inherited mental retardation. Mutation of the gene leads to a loss of the gene product Fragile X Mental Retardation Protein (FMRP). While a loss of FMRP has been primarily associated with neural and cognitive deficits, it has also been reported to lead to immune system dysfunction in both humans and flies. We used the Acheta domesticus transcriptome to identify a highly conserved cricket ortholog of FMR1 (adfmr1). We cloned a partial cDNA of adfmr1, used systemic RNA interference (RNAi) to knockdown adfmr1 expression, and examined the impact of this knockdown (KD) on the cellular and humoral responses of the insect innate immune system. Following RNAi, both male and female crickets exhibited an increase in the number of circulating hemocytes, a decrease in total hemolymph phenoloxidase (PO) activity, and an increase in fat body lysozyme expression. Despite similar changes in these immune parameters in both sexes, male and female crickets responded differently to an immune challenge. Most KD males failed to survive an intra-abdominal injection of bacterial lipopolysaccharide, while KD females were just as likely as control females to survive this challenge. Our results support that decreased fmr1 expression can alter the cellular and humoral defenses of the insect innate immune system, and may lead to a decrease in male, but not female, immunocompetence.

Ubiquitous plasticizer, Di-(2-ethylhexyl) phthalate enhances existing inflammatory profile in monocytes of children with autism

Genetic as well as environmental factors are believed to play a significant role in the pathogenesis and progression of autism spectrum disorder (ASD). Phthalates are ubiquitous environmental contaminants as they are used plasticizers in several household/industrial products such as vinyl flooring, plastic toys, and cosmetic products. One of the plasticizers that is quite prevalent in these products is di-2-ethylhexyl phthalate (DEHP) which can cause human exposure via dermal/inhalation/ingestion routes. DEHP and its metabolites are associated with behavioral dysregulations and reported to be increased in systemic circulation of ASD children. DEHP is reported to cause upregulation of several inflammatory cytokines in different cells/tissues, however its role in inflammatory signaling of ASD monocytes has not been investigated earlier. Therefore, this study evaluated the effects of DEHP (at 5 μM final concentration for 24 h) on inflammatory profile (NFkB, STAT3, IL-6, TNF-α, IL-1β) in monocytes of ASD subjects and typically developing control (TDC) children. Our data show that DEHP upregulates NFkB/STAT3 expression which is associated with increased inflammatory profile in monocytes of ASD and TDC subjects, however its effect is much greater in magnitude in the former group. This was confirmed by utilization of NFkB inhibitor, PDTC and STAT3 inhibitor, Stattic which caused reduction in inflammatory cytokines from DEHP-treated monocytes in ASD group. In short, DEHP causes further elevation in inflammatory signaling in ASD monocytes which could be due to existing inflammation in this group. These data suggest that use of plasticizers such as DEHP should be minimized in order to avoid their potential effects on immune dysfunction associated with ASD.

Development, phenotypes of immune cells in BTBR T+Itpr3tf/J mice

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is characterized by a lack of social interaction, decreased verbal and non-verbal communication skills, and stereotyped repetitive behavior. There is strong evidence that a dysregulated immune response may influence neurodevelopment and thus may have a role in the development of ASD. This study focuses on the characterization of immune cell phenotypes in the BTBR T⁺Itpr3^tf/J (BTBR) mouse strain, a widely used animal model for autism research. Our study demonstrated that BTBR mice have a different immune profile compared to C57BL/6J (B6) mice, which do not display ASD-like characteristics. Thymic cells of BTBR mice have more single positive (SP) CD4⁺ and CD8⁺ T cells and fewer double positive (DP) T cells than B6 mice. The development of T cells is increased in BTBR mice with regard to the double negative (DN4) population being much higher in BTBR mice. The spleens and blood of BTBR mice also have more T helper type 1 (Th1), T helper type 2 (Th2) and T regulatory (Treg) cells compared to B6 mice. Aire expression in the thymus and spleen of BTBR mice compared to B6 mice was equivalent and lower, respectively. The mature natural killer (NK) innate immune cell population in blood and spleen is lower in BTBR than B6 mice; NK cell development is blocked prior to the double positive (DN) CD11b⁺CD27⁺ stage in BTBR mice. Since BTBR mice have more CD4⁺ T cells and elevated numbers of Th1 (T-bet⁺) and Th2 (GATA3⁺) cells, their low defense against pathogen may be explained by the lower number of NK cells and the significantly lower Th1 to Th2 ratio. The elevated number of plasma cells and autoantibodies of BTBR mice may be due to less presence and function of splenic AIRE.

Salivary Cytokine Profile as a Possible Predictor of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is characterized by neurodevelopmental disorders and alterations in immune function and cytokine levels. The aim of this study is to determine the salivary levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor α (TNFα), monocyte chemoattractant protein-1 (MCP-1), Regulated on Activation, Normal T-cell Expressed and Secreted (RANTES), and Eotaxin in children with ASD and in healthy controlsto assess their predictive potential. We explored correlations between the cytokine levels and the neurodevelopmental disorders related to ASD. The study comprised 19 children with ASD and 19 typically developing (TD) ones. We analyzed salivary levels of IL-1β, IL-6, IL-8, TNFα, MCP-1, RANTES, and eotaxin on Luminex with custom-designed 7-plex kits. The level of RANTES in ASD children was significantly lower than those of TD. In TDs, the salivary levels of IL-1β, MCP-1, and TNFα correlated positively with age. In ASD, the cytokine levels did not correlate with age. There were statistically significant differences between the RANTES level and aggression and gait disturbances, between IL-8 level and fixations/stimulations, and between IL-1β level and no active speech. The levels of the cytokine detected can manifest both systemic and local changes related to ASD. The cytokine pattern cannot be used as a sole ASD predictor, but the salivary levels may be helpful in categorizing the ASD subtype.

Analyzing the Potential Biological Determinants of Autism Spectrum Disorder: From Neuroinflammation to the Kynurenine Pathway

Autism Spectrum Disorder (ASD) etiopathogenesis is still unclear and no effective preventive and treatment measures have been identified. Research has focused on the potential role of neuroinflammation and the Kynurenine pathway; here we review the nature of these interactions. Pre-natal or neonatal infections would induce microglial activation, with secondary consequences on behavior, cognition and neurotransmitter networks. Peripherally, higher levels of pro-inflammatory cytokines and anti-brain antibodies have been identified. Increased frequency of autoimmune diseases, allergies, and recurring infections have been demonstrated both in autistic patients and in their relatives. Genetic studies have also identified some important polymorphisms in chromosome loci related to the human leukocyte antigen (HLA) system. The persistence of immune-inflammatory deregulation would lead to mitochondrial dysfunction and oxidative stress, creating a self-sustaining cytotoxic loop. Chronic inflammation activates the Kynurenine pathway with an increase in neurotoxic metabolites and excitotoxicity, causing long-term changes in the glutamatergic system, trophic support and synaptic function. Furthermore, overactivation of the Kynurenine branch induces depletion of melatonin and serotonin, worsening ASD symptoms. Thus, in genetically predisposed subjects, aberrant neurodevelopment may derive from a complex interplay between inflammatory processes, mitochondrial dysfunction, oxidative stress and Kynurenine pathway overexpression. To validate this hypothesis a new translational research approach is necessary.

Oxidized cell-free DNA as a stress-signaling factor activating the chronic inflammatory process in patients with autism spectrum disorders

BACKGROUND

Autism spectrum disorders (ASD) are known to be associated with an inflammatory process related to immune system dysfunction. This study's aim was to investigate the role of cell-free DNA in chronic inflammatory process in ASD patients.

METHODS

The study included 133 ASD patients and 27 healthy controls. Sixty-two ASD patients were demonstrated to have mild-to-moderate disease severity (group I) and 71 individuals to have severe ASD (group II). Plasma cell-free (cf) DNA characteristics, plasma cytokine concentrations, expression of the genes for NFкB1 transcription factor and pro-inflammatory cytokines TNFα, IL-1β and IL-8 in peripheral blood lymphocytes (PBL) of ASD patients, and unaffected controls were investigated. Additionally, in vitro experiments with oxidized DNA supplementation to PBL cultures derived from ASD patients and healthy controls were performed.

RESULTS

The data indicates that ASD patients have demonstrated increased cfDNA concentration in their circulation. cfDNA of patients with severe ASD has been characterized by a high abundance of oxidative modification. Furthermore, ASD patients of both groups have shown elevated plasma cytokine (IL-1β, IL-8, IL-17A) levels and heightened expression of genes for NFкB1 nuclear factor and pro-inflammatory cytokines TNFα, IL-1β, and IL-8 in PBL. In vitro experiments have shown that NF-κB/cytokine mRNA expression profiles of ASD patient PBL treated with oxidized DNA fragments were significantly different from those of healthy controls.

CONCLUSIONS

It may be proposed that oxidized cfDNA plays a role of stress-signaling factor activating the chronic inflammatory process in patients with ASD.

Adult mouse hippocampal transcriptome changes associated with long-term behavioral and metabolic effects of gestational air pollution toxicity

Gestational exposure to air pollution increases the risk of autism spectrum disorder and cognitive impairments with unresolved molecular mechanisms. This study exposed C57BL/6J mice throughout gestation to urban-derived nanosized particulate matter (nPM). Young adult male and female offspring were studied for behavioral and metabolic changes using forced swim test, fat gain, glucose tolerance, and hippocampal transcriptome. Gestational nPM exposure caused increased depressive behaviors, decreased neurogenesis in the dentate gyrus, and increased glucose tolerance in adult male offspring. Both sexes gained fat and body weight. Gestational nPM exposure induced 29 differentially expressed genes (DEGs) in adult hippocampus related to cytokine production, IL17a signaling, and dopamine degradation in both sexes. Stratification by sex showed twofold more DEGs in males than females (69 vs 37), as well as male-specific enrichment of DEGs mediating serotonin signaling, endocytosis, Gαi, and cAMP signaling. Gene co-expression analysis (WCGNA) identified a module of 43 genes with divergent responses to nPM between the sexes. Chronic changes in 14 DEGs (e.g., microRNA9-1) were associated with depressive behaviors, adiposity and glucose intolerance. These genes enriched neuroimmune pathways such as HMGB1 and TLR4. Based on cerebral cortex transcriptome data of neonates, we traced the initial nPM responses of HMGB1 pathway. In vitro, mixed glia responded to 24 h nPM with lower HMGB1 protein and increased proinflammatory cytokines. This response was ameliorated by TLR4 knockdown. In sum, we identified transcriptional changes that could be associated with air pollution-mediated behavioral and phenotypic changes. These identified genes merit further mechanistic studies for therapeutic intervention development.

Nuclear Factor Kappa B in Autism Spectrum Disorder: A Systematic Review

BACKGROUND

The nuclear factor kappa B (NF-κB) is composed of a series of transcription factors, which are involved in the expression of a plethora of target genes, many of these genes contributing to the regulation of inflammatory responses. Consistent with its central role in inflammatory responses, existing studies of the neurobiological basis for ASD propose the involvement of NF-κB in the etiology of this disorder.

OBJECTIVES

The present review aimed to systematically characterize extant literatures regarding the role of NF-κB in the etiology of ASD through data derived from both human studies and animal models.

METHODS

A systematic electronic search was conducted for records indexed within Pubmed, EMBASE, or Web of Science to identify potentially eligible studies. Study inclusion and data extraction was agreed by two independent authors after reviewing the abstract and full text.

RESULTS

Among the 371 articles identified in the initial screening, 18 articles met the eligibility criteria for this review, including 14 human case-control studies compared the expression or activation of NF-κB between ASD cases and controls as well as 4 animal studies used mouse model of ASD to examine the level of NF-κB and further evaluate its changes after different drug treatments. These included 18 studies, although relatively small in quantity, appear to support the role of NF-κB in the etiology of ASD.

CONCLUSIONS

Evidence generated from both human studies and animal models supported the involvement of NF-κB in the neurobiological basis of ASD, despite some concern about whether it functions as a primary contributor causes ASD onset or rather an ancillary factor regulates ASD pathogenesis. The increased understanding of NF-κB in the neurobiological basis of ASD could aid the emergence of clinically relevant diagnostic biomarkers and novel therapeutic strategies acting on the underlying disease pathogenesis. These results suggested that potential methodological differences between studies need to be accounted for and keep open the discussion over the existence of aberrantly NF-κB signaling in ASD subjects.

Involvement of CD45 cells in the development of autism spectrum disorder through dysregulation of granulocyte-macrophage colony-stimulating factor, key inflammatory cytokines, and transcription factors

Autismspectrum disorder (ASD) is a complex and multifactorial heterogeneous disorder. Previous investigations have revealed the association between the immune system and ASD, which is characterized by impaired communication skills. Inflammatory response through CD45 cells plays a key role in the pathogenesis of several autoimmune disorders; however, the molecular mechanism of CD45 cells in ASD is not clearly defined.In this study, we investigated the role of CD45 signaling in children with ASD. In this study, we aimed to investigate the possible involvement of CD45 cells expressing granulocyte-macrophage colony-stimulating factor and inflammatory transcription factors in ASD. Flow cytometric analysis, using peripheral blood mononuclear cells (PBMC), revealed the numbers of GM-CSF-, IFN-γ-, IL-6-, IL-9-, IL-22-, T-bet-, pStat3-, Helios-, and Stat6-producing CD45⁺ cells in children with ASD and children in the control group. We further evaluated the mRNA and protein expression levels of GM-CSF in PBMC by RT-PCR and western blotting analysis. Our results revealed that the children with ASD exhibited significantly higher numbers of CD45⁺GM-CSF⁺, CD45⁺IFN-γ⁺, CD45⁺IL-6⁺, CD45⁺IL-9⁺, CD45⁺IL-22⁺, CD45⁺T-bet⁺, and CD45⁺pStat3⁺ cells compared with the control group. We also found that the children with ASD showed a lower number of CD45⁺Helios⁺ and CD45⁺Stat6⁺ cells compared with the control group. Furthermore, the children with ASD showed higher GM-CSF mRNA and protein expression levels compared with the control group. These results indicated that CD45 could play an essential role in the immune abnormalities of ASD. Further investigation of the role of CD45 in neurodevelopment in ASD is warranted.

Differential regulation of Nrf2 is linked to elevated inflammation and nitrative stress in monocytes of children with autism

Autism spectrum disorder (ASD) is a very complex neurodevelopmental disorder characterized by deficits in social and communication skills. Innate immune cells like monocytes are believed to play a cardinal role in neuroimmune inflammation and nitrative stress. On the other hand, Nrf2, a basic leucine zipper transcription factor plays a significant role in protecting the immune cells against inflammation and oxidants. However, its role in monocytes of ASD children and typically developing control (TDC) children has not been elucidated in relation with inflammation and nitrative stress. Therefore, this study was undertaken to evaluate Nrf2 expression/activity along with parameters of inflammation (NFkB, IL-6, IL-1β) and nitrative stress (iNOS, nitrotyrosine) in monocytes of ASD/TDC children. Further, sulforaphane (SFN) was utilized as an Nrf2 activator to assess its effect on above said inflammatory and nitrative stress parameters. Our study shows that monocytes of ASD subjects have decreased Nrf2 expression/activity along with increased inflammation and nitrative stress. Further, monocytes from ASD have deficiency in induction of Nrf2 activity upon stimulation with LPS. However, activation of Nrf2 in vitro by SFN reverses LPS-induced effects on inflammation in monocytes by reduction in NFkB signaling. Further, treatment with SFN also reverses LPS-induced effects on nitrative stress (iNOS, nitrotyrosine) in monocytes of ASD subjects. This study propounds the idea that SFN protects against nitrative stress and inflammation by downregulating oxidative stress and inflammation through blockade of NFkB signaling in autistic children. This may be the reason behind reported ameliorative effects of SFN in ASD subjects.

Inflammation (IL-1β) Modifies the Effect of Vitamin D and Omega-3 Long Chain Polyunsaturated Fatty Acids on Core Symptoms of Autism Spectrum Disorder-An Exploratory Pilot Study‡

BACKGROUND

The role of vitamin D and omega-3 long chain polyunsaturated fatty acids (omega-3 LCPUFA) in improving core symptoms of autism spectrum disorder (ASD) in children has been investigated by a few randomised controlled trials and the results are mixed and inconclusive. The response to treatment with these nutrients is heterogenous and may be influenced by inflammatory state. As an exploratory analysis, we investigated whether inflammatory state would modulate the effect of these nutrients on core symptoms of ASD. Methods: Seventy-three New Zealand children with ASD (2.5-8.0 years) completed a 12-month randomised, double-blind, placebo-controlled trial of vitamin D (VID, 2000 IU/day), omega-3 LCPUFA; (OM, 722 mg/day docosahexaenoic acid), or both (VIDOM). Non-fasting baseline plasma interleukin-1β (IL-1β) was available for 67 children (VID = 15, OM = 21, VIDOM = 15, placebo = 16). Children were categorised as having undetectable/normal IL-1β (<3.2 pg/ml, n=15) or elevated IL-1β (≥3.2 pg/mL, n = 52). The Social Responsiveness Scale (SRS) questionnaire was used to assess core symptoms of ASD (baseline, 12-month). Mixed model repeated measure analyses (including all children or only children with elevated IL-1β) were used.

RESULTS

We found evidence for an interaction between baseline IL-1β and treatment response for SRS-total, SRS-social communicative functioning, SRS-awareness and SRS-communication (all P_interaction < 0.10). When all children were included in the analysis, two outcome comparisons (treatments vs. placebo) showed greater improvements: VID, no effect (all P > 0.10); OM and VIDOM (P = 0.01) for SRS-awareness. When only children with elevated IL-1β were included, five outcomes showed greater improvements: OM (P = 0.01) for SRS-total; OM (P = 0.03) for SRS-social communicative functioning; VID (P = 0.01), OM (P = 0.003) and VIDOM (P = 0.01) for SRS-awareness.

CONCLUSION

Inflammatory state may have modulated responses to vitamin D and omega-3 LCPUFA intervention in children with ASD, suggesting children with elevated inflammation may benefit more from daily vitamin D and omega-3 LCPUFA supplementation.

Resveratrol in Autism Spectrum Disorders: Behavioral and Molecular Effects

Resveratrol (RSV) is a polyphenolic stillbenoid with significant anti-oxidative and anti-inflammatory properties recently tested in animal models of several neurological diseases. Altered immune alteration and oxidative stress have also been found in patients with autism spectrum disorders (ASD), and these alterations could add to the pathophysiology associated with ASD. We reviewed the current evidence about the effects of RSV administration in animal models and in patients with ASD. RSV administration improves the core-symptoms (social impairment and stereotyped activity) in animal models and it also displays beneficial effects in other behavioral abnormalities such as hyperactivity, anxiety and cognitive function. The molecular mechanisms by which RSV restores or improves behavioral abnormalities in animal models encompass both normalization of central and peripheral immune alteration and oxidative stress markers and new molecular mechanisms such as expression of cortical gamma-amino butyric acid neurons, certain type of miRNAs that regulate spine growth. One randomized, placebo-controlled clinical trial (RCT) suggested that RSV add-on risperidone therapy improves comorbid hyperactivity/non-compliance, whereas no effects where seen in core symptoms of ASD No RCTs about the effect of RSV as monotherapy have been performed and the results from preclinical studies encourage its feasibility. Further clinical trials should also identify those ASD patients with immune alterations and/or with increased oxidative stress markers that would likely benefit from RSV administration.

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.

Role of Vitamin D in Autism Spectrum Disorder

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Autism spectrum disorder (ASD) is a pervasive developmental disorder with heterogeneous etiology. Vitamin D can function as a fat-soluble vitamin as well as a hormone, and can exert its effect through both genomic and non-genomic mechanisms. In the last decades, several studies have examined the relationship between vitamin D levels and ASD. These studies demonstrated that low vitamin D status in early development has been hypothesized as an environmental risk factor for ASD. Both in vivo and in vitro studies have demonstrated that vitamin D deficiency in early life can alter brain development, dysregulates neurotransmitter balance in the brain, decreases body and brain antioxidant ability, and alters the immune system in ways that resemble pathological features commonly seen in ASD. In this review, we focused on the association between vitamin D and ASD. In addition, the above-mentioned mechanisms of action that link vitamin D deficiency with ASD were also discussed. Finally, clinical trials of vitamin D supplementation treatment of ASD have also been discussed.

Maternal elevated salt consumption and the development of autism spectrum disorder in the offspring

Autism spectrum disorder (ASD) is a prevalent neurodevelopmental condition with no known etiology or cure. Several possible contributing factors, both genetic and environmental, are being actively investigated. Amongst these, maternal immune dysregulation has been identified as potentially involved in promoting ASD in the offspring. Indeed, ASD-like behaviors have been observed in studies using the maternal immune activation mouse model. Furthermore, recent studies have shed light on maternal dietary habits and their impact on the gut microbiome as factors possibly facilitating ASD. However, most of these studies have been limited to the effects of high fat and/or high sugar. More recent data, however, have shown that elevated salt consumption has a significant effect on the immune system and gut microbiome, often resulting in gut dysbiosis and induction of pro-inflammatory pathways. Specifically, high salt alters the gut microbiome and induces the differentiation of T helper-17 cells that produce pro-inflammatory cytokines such as interleukin-17 and interleukin-23. Moreover, elevated salt can also reduce the differentiation of regulatory T cells that help maintaining a balanced immune system. While in the innate immune system, high salt can cause over activation of M1 pro-inflammatory macrophages and downregulation of M2 regulatory macrophages. These changes to the immune system are alarming because excessive consumption of salt is a documented worldwide problem. Thus, in this review, we discuss recent findings on high salt intake, gut microbiome, and immune system dysregulation while proposing a hypothesis to link maternal overconsumption of salt and children’s ASD.

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.

Maternal and early postnatal immune activation produce sex-specific effects on autism-like behaviors and neuroimmune function in mice

Increasing evidence suggests a role for inflammation in neuropsychiatric conditions including autism spectrum disorder (ASD), a neurodevelopmental syndrome with higher prevalence in males than females. Here we examined the effects of early-life immune system activation (EIA)—comprising regimens of prenatal, early postnatal, or combined (“two-hit”) immune activation—on the core behavioral features of ASD (decreased social interaction, increased repetitive behavior, and aberrant communication) in C57BL/6J mice. We treated timed-pregnant mice with polyinosinic:polycytidylic acid (Poly I:C) on gestational day 12.5 to produce maternal immune activation (MIA). Some offspring also received lipopolysaccharide (LPS) on postnatal day 9 to produce postnatal immune activation (PIA). EIA produced disruptions in social behavior and increases in repetitive behaviors that were larger in males than in females. Ultrasonic vocalizations (USVs) were altered in both sexes. Molecular studies revealed that EIA also produced prominent sex-specific changes in inflammation-related gene expression in the brain. Whereas both sexes showed increases in pro-inflammatory factors, as reflected by levels of mRNA and protein, expression of anti-inflammatory factors was decreased in males but increased in females. Our findings demonstrate that EIA can produce sex-specific behavioral effects and immune responses in the brain, and identify molecular processes that may contribute to resilience in females.

Th17/Treg cells imbalance and their related cytokines (IL-17, IL-10 and TGF-β) in children with autism spectrum disorder

We aimed in this study to investigate a possible involvement of Th17/Treg cells imbalance in autism spectrum disorders (ASD). Using flowcytometry to determine circulating Th17 and Treg cells percentages, RT- PCR and ELISA for cytokine expression, we demonstrated that Th17/Treg balance in ASD children was significantly skewed toward a Th17 response compared to their control. Th17 cells and the ratio of Th17/Treg cells had a significantly positive correlation with disease severity whereas Treg cells had a negative correlation. The imbalance of Th17, Treg cells and their related cytokines may play a vital role in the progression of the disease.

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

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

The association between levels of inflammatory markers in autistic children compared to their unaffected siblings and unrelated healthy controls

Background/aim

Autism spectrum disorder (ASD) describes a range of neurodevelopmental disabilities that impair behavior and communication. Although it is relatively prevalent, the pathophysiology is still subject to speculation and debate. The aim of this study is to identify a possible association between interleukin-6, -8, -9, and -10 and tumor necrosis factor alpha (TNF-α) in autism among Jordanian children by comparing the plasma levels of these cytokines in autistic children with those of their unaffected siblings and unrelated healthy controls.

Materials and methods

In this study, 80 Jordanian children under the age of 12 with diagnosed autism were selected. For comparison, 51 unaffected siblings and 86 unrelated healthy controls were also recruited. Venous blood was collected and interleukin levels in all three groups were investigated.

Results

Interleukin-6 was found to be significantly higher in the plasma of both autistic children and their siblings compared with the unrelated healthy control group (P < 0.05). As for interleukin-8 and TNF-α, plasma levels were significantly higher exclusively in autistic children compared to their siblings and unaffected control subjects (P < 0.001, P < 0.001). There was no significant difference between plasma levels of the previously mentioned cytokines in the siblings and the unrelated control group. As for interleukin-9 and interleukin-10, no significant differences were found between all three groups (P = 0.15, P = 0.35).

Conclusion

We found that interleukin-8 and TNF-α were exclusively elevated in autistic Jordanian children, while interleukin-6 was elevated in both autistic children and their siblings, potentially dismissing its significance. These results may lead to a better understanding of the disorder’s pathophysiology, early testing, and diagnosis.

A meta-analysis of pro-inflammatory cytokines in autism spectrum disorders: Effects of age, gender, and latitude

BACKGROUND

Autism spectrum disorders (ASD) occur in 1.5% of the general population worldwide. Studies suggest that ASD might have more costs than diabetes and attention deficit and hyperactivity disorder by 2025. Dysregulation of the cytokine system is well-documented in ASD. We conducted a meta-analysis of studies providing data on circulating concentrations of pro-inflammatory cytokines in people with ASD compared with control subjects without ASD.

METHODS

We identified potentially eligible studies by systematically searching electronic databases from inception to February 2018.

RESULTS

Thirty-eight studies with total of 2487 participants (1393 patients with ASD and 1094 control subjects) were included in the meta-analysis; 13 for interferon (IFN)-γ, 17 for interleukin (IL)-1β, 22 for IL-6, 19 for tumor necrosis factor (TNF)-α, 4 for IL-1α, 6 for IL-2, 4 for IL-7, 8 for IL-8, 14 for IL-12, 3 for IL-15, 12 for IL-17, 3 for IL-18, 3 for IL-2 receptor, 3 for TNF-β, and 3 for IL-23. We found medium increases in levels of plasma IFN-γ (standardized mean difference, SMD = 0.53) and serum IL-1β (SMD = 0.56) and small increases in levels of blood IL-1β (SMD = 0.35), serum IL-6 (SMD = 0.30) and serum TNF-α (SMD = 0.31) for patients with ASD. Meta-regression analyses identified latitude as a negative moderator of the effect size (ES) of difference in mean levels of IFN-γ (R² = 0.26) and TNF-α (R² = 0.74). Also, difference in the mean age between patients and controls had a negative interaction with the ES of difference in mean levels of IL-1β. In contrast, there was a positive effect of the moderator of difference in the proportion of male subjects between patients and controls on the ES of difference in mean levels of IL-1β. We found no significant alterations in peripheral levels of other pro-inflammatory cytokines including IL-1α, IL-2, IL-2R, IL-3, IL-7, IL-8, IL-12, IL-12p40, IL-12p70, IL-15, IL-17, IL-18, IL-23, TBF-β, and TNFRI/II in patients with ASD.

CONCLUSIONS

This meta-analysis provides evidence for higher concentration of pro-inflammatory cytokines IFN-γ, IL-1β, IL-6, and TNF-α in autistic patents compared with control subjects. Also, meta-regression analyses point to the interaction of latitude, age, and gender with peripheral alterations of associated pro-inflammatory cytokines.

The influence of neuroinflammation in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterised by deficits in social communication and restricted or repetitive behaviours. The clinical presentation of ASD is highly variable and diagnosis is based on the presence of impaired social communication and repetitive and/or restricted behaviours. Although the precise pathophysiologies underlying ASD are unclear, growing evidence supports a role for dysregulated neuroinflammation. The potential involvement of microglia and astrocytes reactive to inflammatory stimuli in ASD has generated much interest due to their varied roles including in mounting an immune response and regulating synaptic function. Increased numbers of reactive microglial and astrocytes in both ASD postmortem tissue and animal models have been reported. Whether dysregulation of glial subtypes exacerbates alterations in neural connectivity in the brain of autistic patients is not well explored. A role for the gut-brain axis involving microbial-immune-neuronal cross talk is also a growing area of neuroinflammation research. Greater understanding of these interactions under patho/physiological conditions and the identification of consistent immune profile abnormalities can potentially lead to more reliable diagnostic measures and treatments in ASD.

The use of iPSC technology for modeling Autism Spectrum Disorders

Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders that influence social skills, involving communication, interaction, and behavior, usually with repetitive and restrictive manners. Due to the variety of genes involved in ASDs and several possible environmental factors influence, there is still no answer to what really causes syndromic and non-syndromic types of ASDs, usually affecting each individual in a unique way. However, we know that the mechanism underlying ASDs involves brain functioning. The human brain is a complex structure composed of close to 100 billion cells, which is a big challenge to study counting just with post mortem tissue investigation or genetic approaches. Therefore, human induced pluripotent stem cells (iPSC) technology has been used as a tool to produce viable cells for understanding a working brain. Taking advantage of patient-derived stem cells, researchers are now able to generate neurons, glial cells and brain organoids in vitro to model ASDs. In this review we report data from different studies showing how iPSCs have been a critical tool to study the different phenotypes of ASDs.

Sex-Dependent Effects of Perinatal Inflammation on the Brain: Implication for Neuro-Psychiatric Disorders

Individuals born preterm have higher rates of neurodevelopmental disorders such as schizophrenia, autistic spectrum, and attention deficit/hyperactivity disorders. These conditions are often sexually dimorphic and with different developmental trajectories. The etiology is likely multifactorial, however, infections both during pregnancy and in childhood have emerged as important risk factors. The association between sex- and age-dependent vulnerability to neuropsychiatric disorders has been suggested to relate to immune activation in the brain, including complex interactions between sex hormones, brain transcriptome, activation of glia cells, and cytokine production. Here, we will review sex-dependent effects on brain development, including glia cells, both under normal physiological conditions and following perinatal inflammation. Emphasis will be given to sex-dependent effects on brain regions which play a role in neuropsychiatric disorders and inflammatory reactions that may underlie early-life programming of neurobehavioral disturbances later in life.

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.

Maternal immune activation, central nervous system development and behavioral phenotypes

Maternal immune activation (MIA) refers to a maternal immune system triggered by infectious or infectious-like stimuli. A cascade of cytokines and immunologic alterations are transmitted to the fetus, resulting in adverse phenotypes most notably in the central nervous system. Epidemiologic studies implicate maternal infections in a variety of neuropsychiatric disorders, most commonly autism spectrum disorders and schizophrenia. In animal models, MIA causes neurochemical and anatomic changes in the brain that correspond to those found in humans with the disorders. As our understanding of the interactions between environment, genetics, and immune system grows, the role of alternative, noninfectious risk factors, such as prenatal stress, obesity, and the gut microbiome also becomes clearer. This review considers how infectious and noninfectious etiologies activate the maternal immune system. Their impact on fetal programming and neuropsychiatric disorders in offspring is examined in the context of human and animal studies.

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.

A Prospective Study of Environmental Exposures and Early Biomarkers in Autism Spectrum Disorder: Design, Protocols, and Preliminary Data from the MARBLES Study

BACKGROUND

Until recently, environmental factors in autism spectrum disorder (ASD) were largely ignored. Over the last decade, altered risks from lifestyle, medical, chemical, and other factors have emerged through various study designs: whole population cohorts linked to diagnostic and/or exposure-related databases, large case-control studies, and smaller cohorts of children at elevated risk for ASD.

OBJECTIVES

This study aimed to introduce the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) prospective study and its goals, motivate the enhanced-risk cohort design, describe protocols and main exposures of interest, and present initial descriptive results for the study population.

METHODS

Families having one or more previous child with ASD were contacted before or during a pregnancy, and once the woman became pregnant, were invited to enroll. Data and biological samples were collected throughout pregnancy, at birth, and until the child's third birthday. Neurodevelopment was assessed longitudinally. The study began enrolling in 2006 and is ongoing.

RESULTS

As of 30 June 2018, 463 pregnant mothers have enrolled. Most mothers ([Formula: see text]) were thirty years of age or over, including 7.9% who are fourty years of age or over. The sample includes 22% Hispanic and another 25% nonHispanic Black, Asian, or multiracial participants; 24% were born outside the United States. Retention is high: 84% of participants whose pregnancies did not end in miscarriage completed the study or are still currently active. Among children evaluated at 36 months of age, 24% met criteria for ASD, and another 25% were assessed as nonASD nontypical development.

CONCLUSION

Few environmental studies of ASD prospectively obtain early-life exposure measurements. The MARBLES study fills this gap with extensive data and specimen collection beginning in pregnancy and has achieved excellent retention in an ethnically diverse study population. The 24% familial recurrence risk is consistent with recent reported risks observed in large samples of siblings of children diagnosed with ASD. https://doi.org/10.1289/EHP535.

Dysregulation of the expression of HLA-DR, costimulatory molecule, and chemokine receptors on immune cells in children with autism

Autism spectrum disorder (ASD) is a heterogeneous disorder diagnosed based on the severity of abnormalities in social skills. Several studies have acknowledged the presence of abnormal immune functions among individuals diagnosed with ASD. HLA-DR (human leukocyte antigen-antigen D related) has been shown to play a significant role in several inflammatory and neurological disorders; however, the role of HLA-DR signaling in ASD has not yet been fully clarified. In this study, we investigated the role of HLA-DR signaling in children with ASD. Flow cytometric analysis, using peripheral blood mononuclear cells (PBMCs), revealed the numbers of CD4⁺, CD8⁺, CD28⁺, CXCR4⁺, and CCR7⁺ expressing HLA-DR cells in typically developing (TD) controls and children with ASD. We also determined the numbers of IFN-γ⁺, IL-21⁺, and Foxp3⁺ expressing HLA-DR cells in TD controls and in children with ASD using PBMCs. We observed mRNA and protein expression levels of HLA-DR by RT-PCR and western blotting analysis. Our results revealed that children with ASD had significantly increased numbers of HLA-DR⁺CD4⁺, HLA-DR⁺CD8⁺, CD28⁺HLA-DR⁺, HLA-DR⁺CXCR4⁺, HLA-DR⁺CCR7⁺ cells compared with TD controls. We found that children with ASD showed increased HLA-DR⁺IFN-γ⁺ and HLA-DR⁺IL-21⁺ and decreased HLA-DR⁺Foxp3⁺ expression levels compared with TD controls. Furthermore, children with ASD showed higher HLA-DR mRNA and protein expression levels compared with TD controls. These results indicated that HLA-DR could play an essential role in the immune abnormalities associated with 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.

Downregulation in Helios transcription factor signaling is associated with immune dysfunction in blood leukocytes of autistic children

Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder in which immunological imbalance has been suggested to be a major etiological component. Helios, a transcription factor, has been studied extensively in the context of human T cell regulation in health and disease, yet the role of Helios signaling has not been examined in children with ASD. In the present study, we investigated the production of Helios in CD4⁺, CD8⁺, and TIM-3⁺, CXCR3⁺ cells in typically developing (TD) controls and children with ASD and in peripheral blood mononuclear cells (PBMCs). We assayed the production of IFN-γ⁺Helios⁺, IL-21⁺Helios⁺, T-bet⁺Helios⁺, and Foxp3⁺Helios⁺ cells, and determined Helios mRNA and protein expression levels in PBMCs, in TD controls and children with ASD. Our results revealed that children with ASD had lower numbers of CD4⁺Helios⁺ CD8⁺Helios⁺, TIM-3⁺Helios⁺, and CXCR3⁺Helios⁺ cells as compared to TD controls. Our results also showed that children with ASD had decreased IFN-γ⁺Helios⁺, IL-21⁺Helios⁺, T-bet⁺Helios⁺, and Helios⁺Foxp3⁺ production compared to that in TD controls. Moreover, our results indicated that children with ASD had lower Helios mRNA and protein expression levels compared to those in TD controls. These results suggest that the Helios transcription factor may be critical to immune alterations in children with ASD. Therefore, our results suggest that targeting Helios signaling might offer a strategy for developing ASD therapies.

Prenatal exposure to environmental insults and enhanced risk of developing Schizophrenia and Autism Spectrum Disorder: focus on biological pathways and epigenetic mechanisms

When considering neurodevelopmental disorders (NDDs), Schizophrenia (SZ) and Autism Spectrum Disorder (ASD) are considered to be among the most severe in term of prevalence, morbidity and impact on the society. Similar features and overlapping symptoms have been observed at multiple levels, suggesting common pathophysiological bases. Indeed, recent genome-wide association studies (GWAS) and epidemiological data report shared vulnerability genes and environmental triggers across the two disorders. In this review, we will discuss the possible biological mechanisms, including glutamatergic and GABAergic neurotransmissions, inflammatory signals and oxidative stress related systems, which are targeted by adverse environmental exposures and that have been associated with the development of SZ and ASD. We will also discuss the emerging role of the gut microbiome as possible interplay between environment, immune system and brain development. Finally, we will describe the involvement of epigenetic mechanisms in the maintenance of long-lasting effects of adverse environments early in life. This will allow us to better understand the pathophysiology of these NDDs, and also to identify novel targets for future treatment strategies.

Inflammation and Neuro-Immune Dysregulations in Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) is characterized by persistent deficits in social communication and interaction and restricted-repetitive patterns of behavior, interests, or activities. Strong inflammation states are associated with ASD. This inflammatory condition is often linked to immune system dysfunction. Several cell types are enrolled to trigger and sustain these processes. Neuro-inflammation and neuro-immune abnormalities have now been established in ASD as key factors in its development and maintenance. In this review, we will explore inflammatory conditions, dysfunctions in neuro-immune cross-talk, and immune system treatments in ASD management.

Differential immune responses and microbiota profiles in children with autism spectrum disorders and co-morbid gastrointestinal symptoms

OBJECTIVES

Many studies have reported the increased presence of gastrointestinal (GI) symptoms in children with autism spectrum disorders (ASD). Altered microbiome profiles, pro-inflammatory responses and impaired intestinal permeability have been observed in children with ASD and co-morbid GI symptoms, yet few studies have compared these findings to ASD children without GI issues or similarly aged typical developing children. The aim of this study was to determine whether there are biological signatures in terms of immune dysfunction and microbiota composition in children with ASD with GI symptoms.

METHODS

Children were enrolled in one of four groups: ASD and GI symptoms of irregular bowel habits (ASDGI), children with ASD but without current or previous GI symptoms (ASDNoGI), typically developing children with GI symptoms (TDGI) and typically developing children without current or previous GI symptoms (TDNoGI). Peripheral blood mononuclear cells (PBMC) were isolated from the blood, stimulated and assessed for cytokine production, while stool samples were analyzed for microbial composition.

RESULTS

Following Toll-Like receptor (TLR)-4 stimulation, the ASDGI group produced increased levels of mucosa-relevant cytokines including IL-5, IL-15 and IL-17 compared to ASDNoGI. The production of the regulatory cytokine TGFβ1 was decreased in the ASDGI group compared with both the ASDNoGI and TDNoGI groups. Analysis of the microbiome at the family level revealed differences in microbiome composition between ASD and TD children with GI symptoms; furthermore, a predictive metagenome functional content analysis revealed that pathways were differentially represented between ASD and TD subjects, independently of the presence of GI symptoms. The ASDGI also showed an over-representation of the gene encoding zonulin, a molecule regulating gut permeability, compared to the other groups.

CONCLUSIONS

Overall our findings suggest that children with ASD who experience GI symptoms have an imbalance in their immune response, possibly influenced by or influencing metagenomic changes, and may have a propensity to impaired gut barrier function which may contribute to their symptoms and clinical outcome.

Neuroimmunologic and Neurotrophic Interactions in Autism Spectrum Disorders: Relationship to Neuroinflammation

Autism spectrum disorders (ASD) are the most prevalent set of pediatric neurobiological disorders. The etiology of ASD has both genetic and environmental components including possible dysfunction of the immune system. The relationship of the immune system to aberrant neural circuitry output in the form of altered behaviors and communication characterized by ASD is unknown. Dysregulation of neurotrophins such as BDNF and their signaling pathways have been implicated in ASD. While abnormal cortical formation and autistic behaviors in mouse models of immune activation have been described, no one theory has been described to link activation of the immune system to specific brain signaling pathways aberrant in ASD. In this paper we explore the relationship between neurotrophin signaling, the immune system and ASD. To this effect we hypothesize that an interplay of dysregulated immune system, synaptogenic growth factors and their signaling pathways contribute to the development of ASD phenotypes.

Systemic inflammation in asocial BTBR T+ tf/J mice predisposes them to increased psoriatic inflammation

Autistic Spectrum disorder (ASD) is a neurobehavioral disorder characterized by defects in communication skills leading to restricted sociability. ASD has immense dysregulation in immune responses which is thought to affect neuronal system and thus behavior. ASD patients and BTBR T⁺ tf/J (BTBR) autistic mice have increased systemic inflammation due to dysfunction in innate and adaptive immune responses. Recent studies suggest that ASD patients are associated with several co-morbid autoimmune disorders including psoriasis. However underlying mechanisms for this phenomenon have not been explored. In this study, we used imiquimod (IMQ)-induced psoriatic inflammation in social C57BL/6 (C57) mice and asocial BTBR mice to investigate whether systemic inflammation in BTBR is associated with increased susceptibility to psoriatic inflammation. Our data shows that BTBR mice have increased expression of TLR7/IL-6/IL-23 in systemic DCs but not in skin as compared to C57 mice at baseline. This leads to much greater psoriatic inflammation in BTBR mice upon IMQ application than C57 mice. Consequently, BTBR mice also have higher Th17 related immune responses in the skin and systemic compartment. Overall our study suggests that systemic innate (TLR7/IL-23/IL-6 in DCs) and adaptive (Th17 related signaling) immune responses are heightened in BTBR mice at baseline which predisposes them for greater psoriatic inflammation than C57 mice upon IMQ application. This could be one of the reasons for increased psoriatic inflammation in patients with ASD. Therapies that aim to decrease immune activation may not only benefit ASD-associated neurobehavioral abnormalities but also comorbid disorders such as psoriasis.

Immunity and inflammation in status epilepticus and its sequelae: possibilities for therapeutic application

Status epilepticus (SE) is a life-threatening neurological emergency often refractory to available treatment options. It is a very heterogeneous condition in terms of clinical presentation and causes, which besides genetic, vascular and other structural causes also include CNS or severe systemic infections, sudden withdrawal from benzodiazepines or anticonvulsants and rare autoimmune etiologies. Treatment of SE is essentially based on expert opinions and antiepileptic drug treatment per se seems to have no major impact on prognosis. There is, therefore, urgent need of novel therapies that rely upon a better understanding of the basic mechanisms underlying this clinical condition. Accumulating evidence in animal models highlights that inflammation ensuing in the brain during SE may play a determinant role in ongoing seizures and their long-term detrimental consequences, independent of an infection or auto-immune cause; this evidence encourages reconsideration of the treatment flow in SE patients.

Alterations in plasma cytokine levels in chinese children with autism spectrum disorder

Genetic alterations, together with environmental risk factors during infancy and childhood, contribute significantly to the etiology of autism spectrum disorder (ASD), a heterogeneous neurodevelopmental condition characterized by impairments in social interaction and restricted, repetitive behaviors. Mounting evidence points to a critical contribution of immunological risk factors to the development of ASD. By affecting multiple neurodevelopmental processes, immune system dysfunction could act as a point of convergence between genetics and environmental factors in ASD. Previous studies have shown altered cytokine levels in individuals with ASD, but research in Asian populations are limited. Here, we measured the plasma levels of 11 candidate cytokines in ASD and typically developing (TD) children. The cohort included 41 TD children and 87 children with ASD, aged 1-6 years. We found that as compared to the TD group, children with ASD had higher plasma levels of Eotaxin, TGF-β1 and TNF-α. The increase in TGF-β1 level was most significant in males, while the increase in Eotaxin was most significant in females. Eotaxin level negatively correlated with the social affect score (SA) in ADOS, while TNF-α level positively correlated with total development quotient (DQ), measured using GMDS. These pilot findings suggest potentially important roles of Eotaxin, TGF-β1 and TNF-α in ASD in the Chinese population. Autism Res 2018, 11: 989-999. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

Alteration of immune system function is an important risk factor for autism spectrum disorder (ASD). Here we found that the levels of cytokines, including Eotaxin, TGF-β1 and TNF-α, are elevated in Chinese children with ASD, as compared to typically developing children. The change in TGF-β1 level was most prominent in boys, while that of Eotaxin was more significant in girls. These results provide evidence for changes in cytokine profile in Chinese children with ASD.

Toll-like receptor-4 regulates anxiety-like behavior and DARPP-32 phosphorylation

Toll-like receptors (TLRs) play a crucial role in early innate immune responses to inflammatory agents and pathogens. In the brain, some members of the TLR family are expressed in glial cells and neurons. In particular, TLR4 has been involved in learning and memory processes, stress-induced adaptations, and pathogenesis of neurodegenerative disorders. However, the role of TLR4 in emotional behaviors and their underlying mechanisms are poorly understood. In this study, we investigated the role of TLR4 in emotional and social behavior by using different behavioral approaches, and assessed potential molecular alterations in important brain areas involved in emotional responses. TLR4 knockout (KO) mice displayed increased anxiety-like behavior and reduced social interaction compared to wild type control mice. This behavioral phenotype was associated with an altered expression of genes known to be involved in emotional behavior [e.g., brain-derived neurotrophic factor (BDNF) and metabotropic glutamate receptors (mGluRs)]. Interestingly, the mRNA expression of dopamine- and cAMP-regulated phosphoprotein-32 (DARPP-32) was strongly upregulated in emotion-related regions of the brain in TLR4 KO mice. In addition, the phosphorylation levels at Thr75 and Ser97 in DARPP-32 were increased in the frontal cortex of TLR4 KO male mice. These findings indicate that TLR4 signaling is involved in emotional regulation through modulation of DARPP-32, which is a signaling hub that plays a critical role in the integration of numerous neurotransmitter systems, including dopamine and glutamate.

A pilot study of high-dose intravenous immunoglobulin 5% for autism: Impact on autism spectrum and markers of neuroinflammation

Research has shown that a subset of the autism spectrum disorder (ASD) population presents with immune dysregulation. To explore this topic further, we investigated the efficacy and tolerability of intravenous immunoglobulin (IVIG) infusion in children with ASD. In this study, participants were recruited based on a diagnosis of autistic disorder, Asperger's disorder, or pervasive developmental disorder not otherwise specified. Participants also showed evidence of immune dysfunction based on abnormal levels of specific biomarkers, including CD40 ligand (CD154), lymphocyte stimulation, and T or B cell dysfunction. Of 17 screened patients, 14 completed the trial and received IVIG treatment (1 g/kg dose) for ten 21-day treatment cycles. The primary endpoint was disease improvement assessed using standardized cognitive and behavioral tests (Children's Communication Checklist [CCC-2], Social Responsiveness Scale [SRS], Aberrant Behavior Checklist [ABC], Clinical Global Impressions-Severity [CGI-S] and -Improvement [CGI-I], Autism Diagnostic Observation Schedule [ADOS], and Peabody Picture Vocabulary Test [PPVT]). Secondary endpoints included experimental biomarkers such as CD154, toll-like receptor-4, memory B cells, FOXP3, and lymphocyte stimulation. Significant improvements from baseline to study endpoint were observed in several subscales of the CCC-2, SRS, CGI-I, CGI-S, and ADOS, including Associated Maladaptive Behaviors (P ≤ .043), Reciprocal Social Interaction (P = .015), Communication (P < .001), and Stereotyped Behaviors and Repetitive Interests (P ≤ .013). Statistically significant reductions were also seen in numerous secondary outcomes of immunological biomarkers indicative of neuroinflammation. IVIG was well tolerated; no subjects withdrew due to an adverse event, and clinical data showed no evidence of thromboembolic events. Autism Res 2018, 11: 421-433. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

Since research has demonstrated a link between autism spectrum disorder (ASD) and immune dysfunction, this study investigated the efficacy and tolerability of intravenous immunoglobulin (IVIG) infusion in children with ASD. Fourteen patients received IVIG treatment and were assessed using standardized cognitive and behavioral tests. Following treatment with IVIG, significant improvement was observed across several subscales of the clinical tests and significant reductions were seen in the markers of neuroinflammation. These data suggest that inflammatory etiologies may play a role in select cases of autism, and IVIG treatment may exert a positive impact on behaviors and markers of inflammation in ASD.

Microglia and Neonatal Brain Injury

Microglial cells are now recognized as the "gate-keepers" of healthy brain microenvironment with their disrupted functions adversely affecting neurovascular integrity, neuronal homeostasis, and network connectivity. The perception that these cells are purely toxic under neurodegenerative conditions has been challenged by a continuously increasing understanding of their complexity, the existence of a broad array of microglial phenotypes, and their ability to rapidly change in a context-dependent manner to attenuate or exacerbate injuries of different nature. Recent studies have demonstrated that microglial cells exert crucial physiological functions during embryonic and postnatal brain development, some of these functions being unique to particular stages of development, and extending far beyond sensing dangerous signals and serving as antigen presenting cells. In this focused review we cover the roles of microglial cells in regulating embryonic vasculogenesis, neurogenesis, and establishing network connectivity during postnatal brain development. We further discuss context-dependent microglial contribution to neonatal brain injuries associated with prenatal and postnatal infection and inflammation, in relation to neurodevelopmental disorders, as well as perinatal hypoxia-ischemia and arterial focal stroke. We also emphasize microglial phenotypic diversity, notably at the ultrastructural level, and their sex-dependent influence on the pathophysiology of neurodevelopmental disorders.

High expression of Endogenous Retroviruses from intrauterine life to adulthood in two mouse models of Autism Spectrum Disorders

Retroelements, such as Human Endogenous Retroviruses (HERVs), have been implicated in many complex diseases, including neurological and neuropsychiatric disorders. Previously, we demonstrated a distinctive expression profile of specific HERV families in peripheral blood mononuclear cells from Autistic Spectrum Disorders (ASD) patients, suggesting their involvement in ASD. Here we used two distinct ASD mouse models: inbred BTBR T+tf/J mice and CD-1 outbred mice prenatally exposed to valproic acid. Whole embryos, blood and brain samples from the offspring were collected at different ages and the expression of several ERV families (ETnI, ETnII-α, ETnII-β, ETnII-γ, MusD and IAP), proinflammatory cytokines (IL-1β, IL-6 and TNF-α) and Toll-like receptors (TLR3 and TLR4) was assessed. In the two distinct mouse models analysed, the transcriptional activity of the ERV families was significant higher in comparison with corresponding controls, in whole embryos, blood and brain samples. Also the expression levels of the proinflammatory cytokines and TLRs were significantly higher than controls. Current results are in agreement with our previous findings in ASD children, supporting the hypothesis that ERVs may serve as biomarkers of atypical brain development. Moreover, the changes in ERVs and proinflammatory cytokines expression could be related with the autistic-like traits acquisition in the two mouse models.

Children With Autism Spectrum Disorder With Regression Exhibit a Different Profile in Plasma Cytokines and Adhesion Molecules Compared to Children Without Such Regression

Background: In the etiopathogenesis of autism spectrum disorder (ASD), it has been suggested that a proinflammatory condition, as well as an alteration in adhesion molecules in the early stages of neurodevelopment, may play a role in the pathophysiology of the disorder. This study set out to evaluate the plasma levels of certain inflammatory cytokines, adhesion molecules, and growth factors in a sample of pediatric patients with ASD and compare them to the levels in a control group of healthy children. Methods: Fifty-four children (45 males and nine females) aged 2-6, who were diagnosed with ASD, and a control group of 54 typically-developing children of similar ages were selected. The diagnosis of ASD was carried out in accordance with the DSM-5 criteria and the data obtained from a developmental semi-structured clinical interview and the ADOS evaluation test. Additional testing was carried out to identify the children's developmental level and severity of ASD symptomatology. Patients with ASD were further divided into two subgroups based on developmental parameters: ASD children with neurodevelopmental regression (AMR) and ASD children without neurodevelopmental regression (ANMR). Analyses of plasma molecules, such as cathepsin, IL1β, IL6, IL8, MPO, RANTES, MCP, BDNF, PAI NCAM, sICAM, sVCAM and NGF, were performed. Results: Higher levels of NGF were observed in the ASD group compared with the levels in the control group (p < 0.05). However, in the analysis of the ASD subgroups, lower plasma levels of NCAM and higher levels of NGF were found in the group of ASD children without developmental regression compared to the levels in the group of typically-developing children. Conclusions: These results suggest differences that could be related to different pathophysiological mechanisms in ASD. There is not a specific profile for the expression of relevant plasma cytokines, adhesion molecules or growth factors in children with ASD compared with that in typically-developing children. However, in the ANMR and AMR subgroups, some of the adhesion molecules and neuronal growth factors show differences that may be related to synaptogenesis.

Maternal IL-17A in autism

Although autism spectrum disorder (ASD) has a strong genetic basis, its etiology is complex, with several genetic factors likely to be involved as well as environmental factors. Immune dysregulation has gained significant attention as a causal mechanism in ASD pathogenesis. ASD has been associated with immune abnormalities in the brain and periphery, including inflammatory disorders and autoimmunity in not only the affected individuals but also their mothers. Prenatal exposure to maternal immune activation (MIA) has been implicated as an environmental risk factor for ASD. In support of this notion, animal models have shown that MIA results in offspring with behavioral, neurological, and immunological abnormalities similar to those observed in ASD. This raises the question of how MIA exposure can lead to ASD in susceptible individuals. Recent evidence points to a potential inflammation pathway linking MIA-associated ASD with the activity of T helper 17 (Th17) lymphocytes and their effector cytokine interleukin-17A (IL-17A). IL-17A has been implicated from human studies and elevated IL-17A levels in the blood have been found to correlate with phenotypic severity in a subset of ASD individuals. In MIA model mice, elevated IL-17A levels also have been observed. Additionally, antibody blockade to inhibit IL-17A signaling was found to prevent ASD-like behaviors in offspring exposed to MIA. Therefore, IL-17A dysregulation may play a causal role in the development of ASD. The source of increased IL-17A in the MIA mouse model was attributed to maternal Th17 cells because genetic removal of the transcription factor RORγt to selectively inhibit Th17 differentiation in pregnant mice was able to prevent ASD-like behaviors in the offspring. Similar to ASD individuals, the MIA-exposed offspring also displayed cortical dysplasia which could be prevented by inhibition of IL-17A signaling in pregnant mice. This finding reveals one possible cellular mechanism through which ASD-related cognitive and behavioral deficits may emerge following maternal inflammation. IL-17A can exert strong effects on cell survival and differentiation and the activity of signal transduction cascades, which can have important consequences during cortical development on neural function. This review examines IL-17A signaling pathways in the context of both immunity and neural function that may contribute to the development of ASD associated with MIA.

Activation of IL-17 receptor leads to increased oxidative inflammation in peripheral monocytes of autistic children

Millions of children are affected by different neurodevelopmental disorders, out of which autism spectrum disorder (ASD) poses a major hurdle to normal life style due to associated behavioral abnormalities. Several studies have shown an increased expression/release of Th17 related cytokine, IL-17A in ASD. IL-17A may enhance neuroinflammation via its IL-17A receptor, i.e. IL-17RA expressed in immune cells (such as monocytes) of autistic children. Increased oxidative stress has been implicated in a number of neuropsychiatric disorders including ASD. However, whether IL-17A/IL-17RA signaling contributes to oxidative inflammation in monocytes of autistic children has not been explored previously. With this background, we performed this study in peripheral monocytes of ASD patients and age-matched typically developing children. Our study shows that ASD individuals have increased IL-17RA expression in monocytes which is associated with increased nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) pathway and inducible nitric oxide synthase (iNOS)/nitrotyrosine expression as compared to typically developing children. Moreover, in vitro activation of IL-17 receptor by IL-17A in monocytes isolated from ASD individuals leads to enhanced iNOS expression via NFκB pathway. IL-17RA antibody treatment in vitro reversed IL-17A-induced increase in NFκB and iNOS/nitrotyrosine expression in monocytes isolated from ASD subjects. These data connect increased IL-17A/IL-17RA signaling in ASD patients with enhanced oxidative inflammation in monocytes. Therefore, IL-17 receptor signaling in monocytes may potentiate the effects of IL-17A released by other immune cells and may aggravate neuroinflammation in ASD. Our study further suggests that blockade of IL-17A/IL-17 receptor signaling may be beneficial in the children with 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.

Inflammatory dysregulation of monocytes in pediatric patients with obsessive-compulsive disorder

BACKGROUND

Although the exact etiology of obsessive-compulsive disorder (OCD) is unknown, there is growing evidence of a role for immune dysregulation in the pathophysiology of the disease, especially in the innate immune system including the microglia. To test this hypothesis, we studied inflammatory markers in monocytes from pediatric patients with OCD and from healthy controls.

METHODS

We determined the percentages of total monocytes, CD16+ monocytes, and classical (CD14^highCD16-), intermediate (CD14^highCD16^low), and non-classical (CD14^lowCD16^high) monocyte subsets in 102 patients with early-onset OCD and in 47 healthy controls. Moreover, proinflammatory cytokine production (GM-CSF, IL-1β, IL-6, IL-8, and TNF-α) was measured by multiplex Luminex analysis in isolated monocyte cultures, in basal conditions, after exposure to lipopolysaccharide (LPS) to stimulate immune response or after exposure to LPS and the immunosuppressant dexamethasone.

RESULTS

OCD patients had significantly higher percentages of total monocytes and CD16+ monocytes than healthy controls, mainly due to an increase in the intermediate subset but also in the non-classical monocytes. Monocytes from OCD patients released higher amounts of GM-CSF, IL-1β, IL-6, IL-8, and TNF-α than healthy controls after exposure to LPS. However, there were no significant differences in basal cytokine production or the sensitivity of monocytes to dexamethasone treatment between both groups. Based on monocyte subset distribution and cytokine production after LPS stimulation, patients receiving psychoactive medications seem to have an intermediate inflammatory profile, that is, lower than non-medicated OCD individuals and higher than healthy controls.

CONCLUSIONS

These results strongly support the involvement of an enhanced proinflammatory innate immune response in the etiopathogenesis of early-onset OCD.

Maternal immune activation in neurodevelopmental disorders

Converging lines of evidence from basic science and clinical studies suggest a relationship between maternal immune activation (MIA) and neurodevelopmental disorders such as autism spectrum disorder (ASD) and schizophrenia. The mechanisms through which MIA increases the risk of neurodevelopmental disorders have become a subject of intensive research. This review aims to describe how dysregulation of microglial function and immune mechanisms may link MIA and neurodevelopmental pathologies. We also summarize the current evidence in animal models of MIA. Developmental Dynamics 247:588-619, 2018. © 2017 Wiley Periodicals, Inc.