Inflammatory profiles in the BTBR mouse: how relevant are they to autism spectrum disorders?

Activation of endogenous retroviruses characterizes the maternal-fetal interface in the BTBR mouse model of autism spectrum disorder

Endogenous retroviruses (ERVs) are genetic elements derived from a process of germline infection by exogenous retroviruses. Some ERVs have been co-opted for physiological functions, and their activation has been associated with complex diseases, including Autism Spectrum Disorder (ASD). We have already demonstrated an abnormal expression of ERVs in the BTBR T + tf/J (BTBR) mouse model of ASD during intrauterine life till adulthood. Thus, starting from the assumptions that ERVs may contribute to the derailment of neurodevelopment and that ASD has fetal origins as a consequence of adverse intrauterine conditions, the present study aims to characterize the transcriptional activity of selected ERVs (MusD, IAP, Syn-A, Syn-B, ARC and GLN), LINE-1, inflammatory mediators (IL-6, IL-10, IL-11 CXCL-1) at the maternal-fetal interface and in dissected embryos from BTBR mice. Our results highlight the deregulation of ERVs and inflammatory mediators at the maternal-fetal interface, and in cephalic and non-cephalic embryonic tissues from BTBR compared to C57BL/6 J. Several correlations among ERV expression levels emerged in different tissues from C57BL/6 J mice while, in BTBR mice, no correlations were found, suggesting that in this model, the acquisition of autistic-like traits might be linked to the dysregulation of ERV activity occurring during intra-uterine life.

Targeting S100A9 attenuates social dysfunction by modulating neuroinflammation and myelination in a mouse model of autism

Growing evidence supports a role for dysregulated neuroinflammation in autism. However, the underlying mechanisms of microglia-evoked neuroinflammation in the development of autistic phenotypes have not been elucidated. This study aimed to investigate the role and underlying mechanisms of microglial S100 calcium-binding protein A9 (S100A9) in autistic phenotypes. We utilized the BTBR T + tf/J (BTBR) mouse, a reliable preclinical model for autism that displays core behavioral features of autism as well as persistent immune dysregulation. A combination of behavioral, pharmacological, immunological, genetic, molecular, and transcriptomics approaches were used to uncover the potential role of S100A9 in autism. Significant overexpression of microglial S100A9 was observed in the hippocampus of BTBR mice. BTBR mice displayed decreased social communication and increased repetitive behaviors compared to C57BL/6 mice. Interestingly, the above social dysfunction was attenuated by a pharmacological inhibitor of S100A9, accompanied by a significant reduction in the activated microglia morphological phenotype, inflammatory receptors, and proinflammatory cytokines. Notably, S100A9 inhibition decreased c-Fos+ cells and promoted myelination in the cornu ammonis 3 of BTBR mice. Furthermore, the promyelinating compound administration ameliorated the autism-relevant behaviors in BTBR mice. Our findings indicate that microglia-derived S100A9 triggers the neuroinflammation cascade, myelination deficits, and social dysfunction. Targeting S100A9 could, therefore, be a promising therapeutic strategy for neuroinflammation-related neurodevelopmental disorders.

Involvement of sphingosine-1-phosphate receptor 1 in pain insensitivity in a BTBR mouse model of autism spectrum disorder

BACKGROUND

Abnormal sensory perception, particularly pain insensitivity (PAI), is a typical symptom of autism spectrum disorder (ASD). Despite the role of myelin metabolism in the regulation of pain perception, the mechanisms underlying ASD-related PAI remain unclear.

METHODS

The pain-associated gene sphingosine-1-phosphate receptor 1 (S1PR1) was identified in ASD samples through bioinformatics analysis. Its expression in the dorsal root ganglion (DRG) tissues of BTBR ASD model mice was validated using RNA-seq, western blot, RT-qPCR, and immunofluorescence. Pain thresholds were assessed using the von Frey and Hargreaves tests. Patch-clamp techniques measured KCNQ/M channel activity and neuronal action potentials. The expression of S1PR1, KCNQ/M, mitogen-activated protein kinase (MAPK), and cyclic AMP/protein kinase A (cAMP/PKA) signaling proteins was analyzed before and after inhibiting the S1P-S1PR1-KCNQ/M pathway via western blot and RT-qPCR.

RESULTS

Through integrated transcriptomic analysis of ASD samples, we identified the upregulated gene S1PR1, which is associated with sphingolipid metabolism and linked to pain perception, and confirmed its role in the BTBR mouse model of ASD. This mechanism involves the regulation of KCNQ/M channels in DRG neurons. The enhanced activity of KCNQ/M channels and the decreased action potentials in small and medium DRG neurons were correlated with PAI in a BTBR mouse model of ASD. Inhibition of the S1P/S1PR1 pathway rescued baseline insensitivity to pain by suppressing KCNQ/M channels in DRG neurons, mediated through the MAPK and cAMP/PKA pathways. Investigating the modulation and underlying mechanisms of the non-opioid pathway involving S1PR1 will provide new insights into clinical targeted interventions for PAI in ASD.

CONCLUSIONS

S1PR1 may contribute to PAI in the PNS in ASD. The mechanism involves KCNQ/M channels and the MAPK and cAMP/PKA signaling pathways. Targeting S1PR1 in the PNS could offer novel therapeutic strategies for the intervention of pain dysesthesias in individuals with ASD.

Resolving neuroinflammatory and social deficits in ASD model mice: Dexmedetomidine downregulates NF-κB/IL-6 pathway via α2AR

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that severely affects individuals' daily life and social development. Unfortunately, there are currently no effective treatments for ASD. Dexmedetomidine (DEX) is a selective agonist of α2 adrenergic receptor (α2AR) and is widely used as a first-line medication for sedation and hypnosis in clinical practice. In recent years, there have been reports suggesting its potential positive effects on improving emotional and cognitive functions. However, whether dexmedetomidine has therapeutic effects on the core symptoms of ASD, namely social deficits and repetitive behaviors, remains to be investigated. In the present study, we employed various behavioral tests to assess the phenotypes of animals, including the three-chamber, self-grooming, marble burying, open field, and elevated plus maze. Additionally, electrophysiological recordings, western blotting, qPCR were mainly used to investigate and validate the potential mechanisms underlying the role of dexmedetomidine. We found that intraperitoneal injection of dexmedetomidine in ASD model mice-BTBR T+ Itpr3tf/J (BTBR) mice could adaptively improve their social deficits. Further, we observed a significant reduction in c-Fos positive signals and interleukin-6 (IL-6) expression level in the prelimbic cortex (PrL) of the BTBR mice treated with dexmedetomidine. Enhancing or inhibiting the action of IL-6 directly affects the social behavior of BTBR mice. Mechanistically, we have found that NF-κB p65 is a key pathway regulating IL-6 expression in the PrL region. In addition, we have confirmed that the α2AR acts as a receptor switch mediating the beneficial effects of dexmedetomidine in improving social deficits. This study provides the first evidence of the beneficial effects of dexmedetomidine on core symptoms of ASD and offers a theoretical basis and potential therapeutic approach for the clinical treatment of ASD.

Effects of different types of induced neonatal inflammation on development and behavior of C57BL/6 and BTBR mice

Neuroinflammation in the early postnatal period can disturb trajectories of the completion of normal brain development and can lead to mental illnesses, such as depression, anxiety disorders, and personality disorders later in life. In our study, we focused on evaluating short- and long-term effects of neonatal inflammation induced by lipopolysaccharide, poly(I:C), or their combination in female and male C57BL/6 and BTBR mice. We chose the BTBR strain as potentially more susceptible to neonatal inflammation because these mice have behavioral, neuroanatomical, and physiological features of autism spectrum disorders, an abnormal immune response, and several structural aberrations in the brain. Our results indicated that BTBR mice are more sensitive to the influence of the neonatal immune activation (NIA) on the formation of neonatal reflexes than C57BL/6 mice are. In these experiments, the injection of lipopolysaccharide had an effect on the formation of the cliff aversion reflex in female BTBR mice. Nonetheless, NIA had no delayed effects on either social behavior or anxiety-like behavior in juvenile and adolescent BTBR and C57BL/6 mice. Altogether, our data show that NIA has mimetic-, age-, and strain-dependent effects on the development of neonatal reflexes and on exploratory activity in BTBR and C57BL/6 mice.

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

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

Molecular insights into enriched environments and behavioral improvements in autism: a systematic review and meta-analysis

Aims

Autism is a multifaceted developmental disorder of the nervous system, that necessitates novel therapeutic approaches beyond traditional medications and psychosomatic therapy, such as appropriate sensory integration training. This systematic mapping review aims to synthesize existing knowledge on enriching environmental interventions as an alternative avenue for improving autism, guiding future research and practice.

Method

A comprehensive search using the terms ASD and Enriched Environment was conducted across PubMed, EMBASE, ISI, Cochrane, and OVID databases. Most of the literature included in this review was derived from animal model experiments, with a particular focus on assessing the effect of EE on autism-like behavior, along with related pathways and molecular mechanisms. Following extensive group discussion and screening, a total of 19 studies were included for analysis.

Results

Enriched environmental interventions exhibited the potential to induce both behavioral and biochemical changes, ameliorating autism-like behaviors in animal models. These improvements were attributed to the targeting of BDNF-related pathways, enhanced neurogenesis, and the regulation of glial inflammation.

Conclusion

This paper underscores the positive impact of enriched environmental interventions on autism through a review of existing literature. The findings contribute to a deeper understanding of the underlying brain mechanisms associated with this intervention.

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.

Minocycline improves autism-related behaviors by modulating microglia polarization in a mouse model of autism

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder with few pharmacological treatments. Minocycline, a tetracycline derivative that inhibits microglial activation, has been well-identified with anti-inflammatory properties and neuroprotective effects. A growing body of research suggests that ASD is associated with neuroinflammation, abnormal neurotransmitter levels, and neurogenesis. Thus, we hypothesized that minocycline could improve autism-related behaviors by inhibiting microglia activation and altering neuroinflammation. To verify our hypothesis, we used a mouse model of autism, BTBR T + Itpr3tf/J (BTBR). As expected, minocycline administration rescued the sociability and repetitive, stereotyped behaviors of BTBR mice while having no effect in C57BL/6J mice. We also found that minocycline improved neurogenesis and inhibited microglia activation in the hippocampus of BTBR mice. In addition, minocycline treatment inhibited Erk1/2 phosphorylation in the hippocampus of BTBR mice. Our findings show that minocycline administration alleviates ASD-like behaviors in BTBR mice and improves neurogenesis, suggesting that minocycline supplementation might be a potential strategy for improving ASD symptoms.

Exposure to Methylmercury at Juvenile Stage Worsens Autism-like Symptoms in Adult BTBR T+tf/J Mice Due to Lack of Nuclear Factor Erythroid 2-Related Factor 2 Signaling Upregulation in Periphery and Brain

Autism spectrum disorder (ASD) is a multifaceted developmental condition that first appears in infancy. The condition is characterized by recurrent patterns in behavior and impairments in social and vocalization abilities. Methylmercury is a toxic environmental pollutant, and its derivatives are the major source of organic mercury to human beings. Inorganic mercury, which is released from a variety of pollutants into oceans, rivers, and streams, is transformed into methylmercury by bacteria and plankton in the water, which later builds up in fish and shellfish, and then enters humans through the consumption of fish and shellfish and increases the risk of developing ASD by disturbing the oxidant-antioxidant balance. However, there has been no prior research to determine the effect of juvenile exposure of methylmercury chloride on adult BTBR mice. Therefore, the current study evaluated the effect of methylmercury chloride administered during the juvenile stage on autism-like behavior (three-chambered sociability, marble burying, self-grooming tests) and oxidant-antioxidant balance (specifically Nrf2, HO-1, SOD-1, NF-kB, iNOS, MPO, and 3-nitrotyrosine) in the peripheral neutrophils and cortex of adult BTBR and C57BL/6 (B6) mice. Our results show that exposure to methylmercury chloride at a juvenile stage results in autism-like symptoms in adult BTBR mice which are related to a lack of upregulation of the Nrf2 signaling pathway as demonstrated by no significant changes in the expression of Nrf2, HO-1, and SOD-1 in the periphery and cortex. On the other hand, methylmercury chloride administration at a juvenile stage increased oxidative inflammation as depicted by a significant increase in the levels of NF-kB, iNOS, MPO, and 3-nitrotyrosine in the periphery and cortex of adult BTBR mice. This study suggests that juvenile exposure to methylmercury chloride contributes to the worsening of autism-like behavior in adult BTBR mice through the disruption of the oxidant-antioxidant balance in the peripheral compartment and CNS. Strategies that elevate Nrf2 signaling may be useful to counteract toxicant-mediated worsening of ASD and may improve quality of life.

Upregulation of Inflammatory Mediators in Peripheral Blood CD40+ Cells in Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a common and severe neurodevelopmental disorder in early childhood, defined as social and communication deficits and repetitive and stereotypic behaviours. The aetiology is unknown in most cases. However, several studies have identified immune dysregulation as potentially promoting ASD. Among the numerous immunological findings in ASD, reports of increased pro-inflammatory markers remain the most consistently observed. C-C chemokine receptor type 1 (CCR1) activation is pro-inflammatory in several neurological disorders. Previous evidence has implied that the expression of chemokine receptors, inflammatory mediators, and transcription factors play a pivotal role in several neuroinflammatory disorders. There have also been reports on the association between increased levels of proinflammatory cytokines and ASD. In this study, we aimed to investigate the possible involvement of CCR1, inflammatory mediators, and transcription factor expression in CD40⁺ cells in ASD compared to typically developing controls (TDC). Flow cytometry analysis was used to determine the levels of CCR1-, IFN-γ-, T-box transcription factor (T-bet-), IL-17A-, retinoid-related orphan receptor gamma t (RORγt-), IL-22- and TNF-α-expressing CD40 cells in PBMCs in children with ASD and the TDC group. We further examined the mRNA and protein expression levels of CCR1 using real-time PCR and western blot analysis. Our results revealed that children with ASD had significantly increased numbers of CD40⁺CCR1⁺, CD40⁺IFN-γ⁺, CD40⁺T-bet⁺, CD40⁺IL-17A⁺, CD40⁺RORγt⁺, CD4⁺IL-22⁺, and CD40⁺TNF-α⁺ cells compared with the TDC group. Furthermore, children with ASD had higher CCR1 mRNA and protein expression levels than those in the TDC group. These results indicate that CCR1, inflammatory mediators, and transcription factors expressed in CD40 cells play vital roles in disease progression.

Cadmium Exposure Is Associated with Behavioral Deficits and Neuroimmune Dysfunction in BTBR T+ Itpr3tf/J Mice

Autism spectrum disorders (ASD) are neurobehavioral disabilities characterized by impaired social interactions, poor communication skills, and restrictive/repetitive behaviors. Cadmium is a common heavy metal implicated in ASD. In this study, we investigated the effects of Cd exposure on BTBR T+ Itpr3tf/J (BTBR) mice, an ASD model. We looked for changes in repetitive behaviors and sociability through experiments. We also explored the molecular mechanisms underlying the effects of Cd exposure, focusing on proinflammatory cytokines and pathways. Flow cytometry measured IL-17A-, IL-17F-, IL-21-, TNF-α-, STAT3-, and RORγt-expressing CD4+ T cells from the spleens of experimental mice. We then used RT-PCR to analyze IL-17A, IL-17F, IL-21, TNF-α, STAT3, and RORγ mRNA expression in the brain. The results of behavioral experiments showed that Cd exposure significantly increased self-grooming and marble-burying in BTBR mice while decreasing social interactions. Cd exposure also significantly increased the number of CD4+IL-17A+, CD4+IL-17F+, CD4+IL-21+, CD4+TNF-α+, CD4+STAT3+, and CD4+RORγt+ cells, while upregulating the mRNA expression of the six molecules in the brain. Overall, our results suggest that oral exposure to Cd aggravates behavioral and immune abnormalities in an ASD animal model. These findings have important implications for ASD etiology and provide further evidence of heavy metals contributing to neurodevelopmental disorders through proinflammatory effects.

DNA Hypomethylation Is Associated with Increased Inflammation in Peripheral Blood Neutrophils of Children with Autism Spectrum Disorder: Understanding the Role of Ubiquitous Pollutant Di(2-ethylhexyl) Phthalate

Autism spectrum disorder (ASD) is a multidimensional disorder in which environmental, immune, and genetic factors act in concert to play a crucial role. ASD is characterized by social interaction/communication impairments and stereotypical behavioral patterns. Epigenetic modifications are known to regulate genetic expression through various mechanisms. One such mechanism is DNA methylation, which is regulated by DNA methyltransferases (DNMTs). DNMT transfers methyl groups onto the fifth carbon atom of the cytosine nucleotide, thus converting it into 5-methylcytosine (5mC) in the promoter region of the DNA. Disruptions in methylation patterns of DNA are usually associated with modulation of genetic expression. Environmental pollutants such as the plasticizer Di(2-ethylhexyl) phthalate (DEHP) have been reported to affect epigenetic mechanisms; however, whether DEHP modulates DNMT1 expression, DNA methylation, and inflammatory mediators in the neutrophils of ASD subjects has not previously been investigated. Hence, this investigation focused on the role of DNMT1 and overall DNA methylation in relation to inflammatory mediators (CCR2, MCP-1) in the neutrophils of children with ASD and typically developing healthy children (TDC). Further, the effect of DEHP on overall DNA methylation, DNMT1, CCR2, and MCP-1 in the neutrophils was explored. Our results show that the neutrophils of ASD subjects have diminished DNMT1 expression, which is associated with hypomethylation of DNA and increased inflammatory mediators such as CCR2 and MCP-1. DEHP further causes downregulation of DNMT1 expression in the neutrophils of ASD subjects, probably through oxidative inflammation, as antioxidant treatment led to reversal of a DEHP-induced reduction in DNMT1. These data highlight the importance of the environmental pollutant DEHP in the modification of epigenetic machinery such as DNA methylation in the neutrophils of ASD subjects.

Oxidative stress and neuroimmune proteins in a mouse model of autism

Oxidative stress including decreased antioxidant enzyme activities, elevated lipid peroxidation, and accumulation of advanced glycation end products in the blood from children with autism spectrum disorders (ASD) has been reported. The mechanisms affecting the development of ASD remain unclear; however, toxic environmental exposures leading to oxidative stress have been proposed to play a significant role. The BTBRT+Itpr3tf/J (BTBR) strain provides a model to investigate the markers of oxidation in a mouse strain exhibiting ASD-like behavioral phenotypes. In the present study, we investigated the level of oxidative stress and its effects on immune cell populations, specifically oxidative stress affecting surface thiols (R-SH), intracellular glutathione (iGSH), and expression of brain biomarkers that may contribute to the development of the ASD-like phenotypes that have been observed and reported in BTBR mice. Lower levels of cell surface R-SH were detected on multiple immune cell subpopulations from blood, spleens, and lymph nodes and for sera R-SH levels of BTBR mice compared to C57BL/6 J (B6) mice. The iGSH levels of immune cell populations were also lower in the BTBR mice. Elevated protein expression of GATA3, TGM2, AhR, EPHX2, TSLP, PTEN, IRE1α, GDF15, and metallothionein in BTBR mice is supportive of an increased level of oxidative stress in BTBR mice and may underpin the pro-inflammatory immune state that has been reported in the BTBR strain. Results of a decreased antioxidant system suggest an important oxidative stress role in the development of the BTBR ASD-like phenotype.

Molecular Abnormalities in BTBR Mice and Their Relevance to Schizophrenia and Autism Spectrum Disorders: An Overview of Transcriptomic and Proteomic Studies

Animal models of psychopathologies are of exceptional interest for neurobiologists because these models allow us to clarify molecular mechanisms underlying the pathologies. One such model is the inbred BTBR strain of mice, which is characterized by behavioral, neuroanatomical, and physiological hallmarks of schizophrenia (SCZ) and autism spectrum disorders (ASDs). Despite the active use of BTBR mice as a model object, the understanding of the molecular features of this strain that cause the observed behavioral phenotype remains insufficient. Here, we analyzed recently published data from independent transcriptomic and proteomic studies on hippocampal and corticostriatal samples from BTBR mice to search for the most consistent aberrations in gene or protein expression. Next, we compared reproducible molecular signatures of BTBR mice with data on postmortem samples from ASD and SCZ patients. Taken together, these data helped us to elucidate brain-region-specific molecular abnormalities in BTBR mice as well as their relevance to the anomalies seen in ASDs or SCZ in humans.

Unique Features of the Immune Response in BTBR Mice

Inflammation plays a considerable role in the pathogenesis of many diseases, including neurodegenerative and psychiatric ones. Elucidation of the specific features of an immune response in various model organisms, and studying the relation of these features with the behavioral phenotype, can improve the understanding of the molecular mechanisms of many psychopathologies. In this work, we focused on BTBR mice, which have a pronounced autism-like behavioral phenotype, elevated levels of oxidative-stress markers, an abnormal immune response, several structural aberrations in the brain, and other unique traits. Although some studies have already shown an abnormal immune response in BTBR mice, the existing literature data are still fragmentary. Here, we used inflammation induced by low-dose lipopolysaccharide, polyinosinic:polycytidylic acid, or their combinations, in mice of strains BTBR T+Itpr3tf/J (BTBR) and C57BL6/J. Peripheral inflammation was assessed by means of a complete blood count, lymphocyte immunophenotyping, and expression levels of cytokines in the spleen. Neuroinflammation was evaluated in the hypothalamus and prefrontal cortex by analysis of mRNA levels of proinflammatory cytokines (tumor necrosis factor, Tnf), (interleukin-1 beta, Il-1β), and (interleukin-6, Il-6) and of markers of microglia activation (allograft inflammatory factor 1, Aif1) and astroglia activation (glial fibrillary acidic protein, Gfap). We found that in both strains of mice, the most severe inflammatory response was caused by the administration of polyinosinic:polycytidylic acid, whereas the combined administration of the two toll-like receptor (TLR) agonists did not enhance this response. Nonetheless, BTBR mice showed a more pronounced response to low-dose lipopolysaccharide, an altered lymphocytosis ratio due to an increase in the number of CD4+ lymphocytes, and high expression of markers of activated microglia (Aif1) and astroglia (Gfap) in various brain regions as compared to C57BL6/J mice. Thus, in addition to research into mechanisms of autism-like behavior, BTBR mice can be used as a model of TLR3/TLR4-induced neuroinflammation and a unique model for finding and evaluating the effectiveness of various TLR antagonists aimed at reducing neuroinflammation.

The live biotherapeutic Blautia stercoris MRx0006 attenuates social deficits, repetitive behaviour, and anxiety-like behaviour in a mouse model relevant to autism

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterised by deficits in social behaviour, increased repetitive behaviour, anxiety and gastrointestinal symptoms. The aetiology of ASD is complex and involves an interplay of genetic and environmental factors. Emerging pre-clinical and clinical studies have documented a potential role for the gut microbiome in ASD, and consequently, the microbiota represents a potential target in the development of novel therapeutics for this neurodevelopmental disorder. In this study, we investigate the efficacy of the live biotherapeutic strain, Blautia stercoris MRx0006, in attenuating some of the behavioural deficits in the autism-relevant, genetic mouse model, BTBR T+ Itpr3tf/J (BTBR). We demonstrate that daily oral administration with MRx0006 attenuates social deficits while also decreasing repetitive and anxiety-like behaviour. MRx0006 administration increases the gene expression of oxytocin and its receptor in hypothalamic cells in vitro and increases the expression of hypothalamic arginine vasopressin and oxytocin mRNA in BTBR mice. Additionally at the microbiome level, we observed that MRx0006 administration decreases the abundance of Alistipes putredinis, and modulates the faecal microbial metabolite profile. This alteration in the metabolite profile possibly underlies the observed increase in expression of oxytocin, arginine vasopressin and its receptors, and the consequent improvements in behavioural outcomes. Taken together, these findings suggest that the live biotherapeutic MRx0006 may represent a viable and efficacious treatment option for the management of physiological and behavioural deficits associated with ASD.

Impairment in the Intestinal Morphology and in the Immunopositivity of Toll-like Receptor-4 and Other Proteins in an Autistic Mouse Model

Autism spectrum disorder (ASD) identifies a neurodevelopmental disease defined by social impairments and repetitive or stereotyped behaviors. The etiology of ASD remains unclear; it primarily affects the brain, but a link between gastrointestinal (GI) diseases, inflammatory mucosal pathology and this disorder has been suggested. In particular, a central role seems to be played by an imbalance in pro-and anti-inflammatory cytokines, oxidative stress, and apoptosis. Toll-like receptor 4 (TLR4) is a protein of innate immunity responsible for the regulation and maintenance of intestinal homeostasis. Through histochemical and immunohistochemical evaluations we analyzed the intestinal morphology and the immunopositivity of TLR4 and of other pro-inflammatory and apoptotic proteins in BTBR T+Itpr3tf/J mice. Morphological data showed that the mucosal tunica presented longer intestinal villi. The length of the villi and the epithelial surface determine the exchanges of the intestinal mucosa with luminal contents, modifying the microbiota composition. The biochemical and immunohistochemical results indicated a close relationship among the increase of TLR4 and the activation of NF-kB subunits (p65 and p50) and pro-inflammatory and apoptotic proteins, such as cyclooxygenase-2, interleukin-1β, inducible nitric oxide synthase, tumor nuclear factor—alpha, caspase-3, caspase-8. These preliminary results require more in-depth study but they suggest the TLR4 signaling pathway as a possible target for therapeutic approaches to reduce GI disorders in ASD.

Potential Cross Talk between Autism Risk Genes and Neurovascular Molecules: A Pilot Study on Impact of Blood Brain Barrier Integrity

Autism Spectrum Disorder (ASD) is a common pediatric neurobiological disorder with up to 80% of genetic etiologies. Systems biology approaches may make it possible to test novel therapeutic strategies targeting molecular pathways to alleviate ASD symptoms. A clinical database of autism subjects was queried for individuals with a copy number variation (CNV) on microarray, Vineland, and Parent Concern Questionnaire scores. Pathway analyses of genes from pathogenic CNVs yielded 659 genes whose protein-protein interactions and mRNA expression mapped 121 genes with maximal antenatal expression in 12 brain regions. A Research Domain Criteria (RDoC)-derived neural circuits map revealed significant differences in anxiety, motor, and activities of daily living skills scores between altered CNV genes and normal microarrays subjects, involving Positive Valence (reward), Cognition (IQ), and Social Processes. Vascular signaling was identified as a biological process that may influence these neural circuits. Neuroinflammation, microglial activation, iNOS and 3-nitrotyrosine increase in the brain of Semaphorin 3F- Neuropilin 2 (Sema 3F-NRP2) KO, an ASD mouse model, agree with previous reports in the brain of ASD individuals. Signs of platelet deposition, activation, release of serotonin, and albumin leakage in ASD-relevant brain regions suggest possible blood brain barrier (BBB) deficits. Disruption of neurovascular signaling and BBB with neuroinflammation may mediate causative pathophysiology in some ASD subgroups. Although preliminary, these data demonstrate the potential for developing novel therapeutic strategies based on clinically derived data, genomics, cognitive neuroscience, and basic neuroscience methods.

Lead (Pb) exposure exacerbates behavioral and immune abnormalities by upregulating Th17 and NF-κB-related signaling in BTBR T+ Itpr3tf/J autistic mouse model

Autism spectrum disorder (ASD) is a highly prevalent neurodevelopmental disorder that are characterized by abnormal social interaction impairments in communication and repetitive and restricted activities or interests. Even though the exact etiology of ASD remains unknown. Lead (Pb) is a toxin known to harm many organs in the body, it is one of the most ubiquitous metal exposures which is associated with neurological deficits. Previous studies have shown that the exposure to Pb may play a role in ASD. BTBR T⁺ Itpr3^tf/J (BTBR) mouse model is commonly used as a preclinical model for ASD. In this study, we investigated the effects of Pb exposure on sociability, self-grooming and marble burying behaviors tests in BTBR mice. We further examined the effects of Pb on IL-17A- RORγT-, STAT3-, NF-κB p65-, iNOS-, TLR-2- and TLR-4-producing CD45⁺ cells in spleen using flow cytometry. We also explored the effects of Pb on IL-17A, RORγT, STAT3, NF-κB p65, and TLR-2 mRNA expression in the brain tissue using RT-PCR analysis. Our results demonstrated that Pb exposure substantially increased repetitive behavior, marble burying and decrease social interactions in BTBR mice. In addition, in spleen cells, Pb exposure exaggerated CD45⁺IL-17A⁺, CD45⁺RORγT⁺, CD45⁺STAT3⁺, CD45⁺NF-κB p65⁺, CD45⁺iNOS⁺, CD45⁺TLR-2⁺ and CD45⁺TLR-4⁺ in BTBR mice. We also found that Pb significantly increased IL-17A, RORγT, STAT3, NF-κB p65, and TLR-2 mRNA in the brain tissue. Therefore, Pb exposure exacerbates behavioral and neuroimmune function in BTBR mice, suggesting a potentially strong role for Pb in ASD.

GW4064 Alters Gut Microbiota Composition and Counteracts Autism-Associated Behaviors in BTBR T+tf/J Mice

Autism spectrum disorder (ASD) is considered a heterogeneous neurodevelopmental disorder characterized by significant social, communication, and behavioral impairments. The gut microbiota is increasingly considered a promising therapeutic target in ASD. Farnesoid X receptor (FXR) has recently been shown to modulate the gut microbiota. We hypothesized that FXR agonist GW4064 could ameliorate behavioral deficits in an animal model for autism: BTBR T+Itpr3tf/J (BTBR) mouse. As expected, administration of GW4064 rescued the sociability of BTBR mice in the three-chamber sociability test and male-female social reciprocal interaction test, while no effects were observed in C57BL/6J mice. We also found that GW4064 administration increased fecal microbial abundance and counteracted the common ASD phenotype of a high Firmicutes to Bacteroidetes ratio in BTBR mice. In addition, GW4064 administration reversed elevated Lactobacillus and decreased Allobaculum content in the fecal matter of BTBR animals. Our findings show that GW4064 administration alleviates social deficits in BTBR mice and modulates selective aspects of the composition of the gut microbiota, suggesting that GW4064 supplementation might prove a potential strategy for improving ASD symptoms.

Social deficits in BTBR T+ Itpr3tf/J mice vary with ecological validity of the test

Translational value of mouse models of neuropsychiatric disorders depends heavily on the accuracy with which they replicate symptoms observed in the human population. In mouse models of autism spectrum disorder (ASD) these include, among others, social affiliation, and communication deficits as well as impairments in understanding and perception of others. Most studies addressing these issues in the BTBR T+ Itpr3tf/J mouse, an idiopathic model of ASD, were based on short dyadic interactions of often non-familiar partners placed in a novel environment. In such stressful and variable conditions, the reproducibility of the phenotype was low. Here, we compared physical conditions and the degree of habituation of mice at the time of testing in the three chambered social affiliation task, as well as parameters used to measure social deficits and found that both the level of stress and human bias profoundly affect the results of the test. To minimize these effects, we tested social preference and network dynamics in mice group-housed in the Eco-HAB system. This automated recording allowed for long-lasting monitoring of differences in social repertoire (including interest in social stimuli) in BTBR T+ Itpr3tf/J and normosocial c57BL/6J mice. With these observations we further validate the BTBR T+ Itpr3tf/J mouse as a model for ASD, but at the same time emphasize the need for more ecological testing of social behavior within all constructs of the Systems for Social Processes domain (as defined by the Research Domain Criteria framework).

Kefir ameliorates specific microbiota-gut-brain axis impairments in a mouse model relevant to autism spectrum disorder

Autism spectrum disorder (ASD) is one of the most severe developmental disorders, affecting on average 1 in 150 children worldwide. There is a great need for more effective strategies to improve quality of life in ASD subjects. The gut microbiome has emerged as a potential therapeutic target in ASD. A novel modulator of the gut microbiome, the traditionally fermented milk drink kefir, has recently been shown to modulate the microbiota and decrease repetitive behaviour, one of the hallmarks of ASD, in mice. As such, we hypothesized that kefir could ameliorate behavioural deficits in a mouse model relevant to ASD; the BTBR T⁺ Itpr3^tf/J mouse strain. To this end, adult mice were administered either kefir (UK4) or a milk control for three weeks as treatment lead-in, after which they were assessed for their behavioural phenotype using a battery of tests. In addition, we assessed systemic immunity by flow cytometry and the gut microbiome using shotgun metagenomic sequencing. We found that indeed kefir decreased repetitive behaviour in this mouse model. Furthermore, kefir prolonged stress-induced increases in corticosterone 60 min post-stress, which was accompanied by an ameliorated innate immune response as measured by LY6C^hi monocyte levels. In addition, kefir increased the levels of anti-inflammatory Treg cells in mesenteric lymph nodes (MLNs). Kefir also increased the relative abundance of Lachnospiraceae bacterium A2, which correlated with reduced repetitive behaviour and increased Treg cells in MLNs. Functionally, kefir modulated various predicted gut microbial pathways, including the gut-brain module S-Adenosylmethionine (SAM) synthesis, as well as L-valine biosynthesis and pyruvate fermentation to isobutanol, which all correlated with repetitive behaviour. Taken together our data show that kefir modulates peripheral immunoregulation, can ameliorate specific ASD behavioural dysfunctions and modulates selective aspects of the composition and function of the gut microbiome, indicating that kefir supplementation might prove a viable strategy in improving quality of life in ASD subjects.

Effects of the L-tyrosine-derived bacterial metabolite p-cresol on colonic and peripheral cells

Specific families of bacteria present within the intestinal luminal content produce p-cresol from L-tyrosine. Although the hosts do not synthesize p-cresol, they can metabolize this compound within their colonic mucosa and liver leading to the production of co-metabolites including p-cresyl sulfate (p-CS) and p-cresyl glucuronide (p-CG). p-Cresol and its co-metabolites are recovered in the circulation mainly conjugated to albumin, but also in their free forms that are excreted in the urine. An increased dietary protein intake raises the amount of p-cresol recovered in the feces and urine, while fecal excretion of p-cresol is diminished by a diet containing undigestible polysaccharides. p-Cresol in excess is genotoxic for colonocytes. In addition, in these cells, this bacterial metabolite decreases mitochondrial oxygen consumption, while increasing the anion superoxide production. In chronic kidney disease (CKD), marked accumulation of p-cresol and p-CS in plasma is measured, and in renal tubular cells, p-cresol and p-CS increase oxidative stress, affect mitochondrial function, and lead to cell death, strongly suggesting that these 2 compounds act as uremic toxins that aggravate CKD progression. p-Cresol and p-CS are also suspected to play a role in the CKD-associated adverse cardiovascular events, since they affect endothelial cell proliferation and migration, decrease the capacity of endothelial wound repair, and increase the senescence of endothelial cells. Finally, the fact that concentration of p-cresol is transiently increased in young autistic children biological fluids, and that intraperitoneal injection of p-cresol in animal models induces some behavioral characteristics observed in the autism spectrum disorders (ASD), raise the view that p-cresol may possibly represent one of the components involved in ASD etiology. Further pre-clinical and clinical studies are obviously needed to determine if the lowering of p-cresol and/or p-CS circulating concentrations, by dietary and/or pharmacological means, would allow, by itself or in combination with other interventions, to improve CKD progression and associated cardiovascular outcomes, as well as some neurological outcomes in children with an early diagnosis of autism.

Exposure to the plasticizer, Di-(2-ethylhexyl) phthalate during juvenile period exacerbates autism-like behavior in adult BTBR T + tf/J mice due to DNA hypomethylation and enhanced inflammation in brain and systemic immune cells

Epigenetic modifications are known to play a crucial role in the behavioral modifications through regulation of gene expression. Environmental factors are known to regulate genetic transcription through DNA methylation which is one of the mechanisms of epigenetic modification. Di-2-ethylhexyl phthalate (DEHP) is one of the most abundant phthalate plasticizers in day-to-day products. Prenatal/postnatal DEHP administration has been reported to cause inflammation as well as behavioral dysregulation, however it is not known if exposure to DEHP during juvenile stage affects peripheral/neuronal inflammation and autism-like symptoms in BTBR mice at adulthood. This study investigated effect of DEHP exposure during juvenile period on DNA methylation (global DNA methylation/DNMT1 expression) and inflammation (IL-17A, IL-6, MCP-1, TNF-α) in CD4 + T cells/CD11c + DCs and cortex, and autism-like symptoms (three-chambered sociability test, self-grooming and marble burying test) in asocial BTBR and social C57 mice at adulthood. Our data reveal that BTBR mice exposed to DEHP during juvenile period have hypomethylated DNA/DNMT1 expression in CD11c + DCs and cortex as compared to vehicle-exposed BTBR mice. It was associated with upregulated inflammation in periphery [plasma IL-6/IL-17A, CD11c + DCs (IL-6/MCP-1/TNF-α), and CD4+ T cells (IL-17A)] and cortex (IL-6, MCP-1, TNF-α), and aggravation in autism-like symptoms in DEHP-treated BTBR mice. These data propose that exposure of DEHP during juvenile period may affect autism-like behavior and inflammation in BTBR mice at adulthood through epigenetic regulation. Therefore, underlying genetic predisposition may play a crucial role in worsening of autistic symptoms in ASD subjects in adulthood if they are exposed to environmental pollutants such as DEHP during juvenile period.

Curcumin Potentiates α7 Nicotinic Acetylcholine Receptors and Alleviates Autistic-Like Social Deficits and Brain Oxidative Stress Status in Mice

Autistic spectrum disorder (ASD) refers to a group of neurodevelopmental disorders characterized by impaired social interaction and cognitive deficit, restricted repetitive behaviors, altered immune responses, and imbalanced oxidative stress status. In recent years, there has been a growing interest in studying the role of nicotinic acetylcholine receptors (nAChRs), specifically α7-nAChRs, in the CNS. Influence of agonists for α7-nAChRs on the cognitive behavior, learning, and memory formation has been demonstrated in neuro-pathological condition such as ASD and attention-deficit hyperactivity disorder (ADHD). Curcumin (CUR), the active compound of the spice turmeric, has been shown to act as a positive allosteric modulator of α7-nAChRs. Here we hypothesize that CUR, acting through α7-nAChRs, influences the neuropathology of ASD. In patch clamp studies, fast inward currents activated by choline, a selective agonist of α7-nAChRs, were significantly potentiated by CUR. Moreover, choline induced enhancement of spontaneous inhibitory postsynaptic currents was markedly increased in the presence of CUR. Furthermore, CUR (25, 50, and 100 mg/kg, i.p.) ameliorated dose-dependent social deficits without affecting locomotor activity or anxiety-like behaviors of tested male Black and Tan BRachyury (BTBR) mice. In addition, CUR (50 and 100 mg/kg, i.p.) mitigated oxidative stress status by restoring the decreased levels of superoxide dismutase (SOD) and catalase (CAT) in the hippocampus and the cerebellum of treated mice. Collectively, the observed results indicate that CUR potentiates α7-nAChRs in native central nervous system neurons, mitigates disturbed oxidative stress, and alleviates ASD-like features in BTBR mice used as an idiopathic rodent model of ASD, and may represent a promising novel pharmacological strategy for ASD treatment.

Potential crosstalk between sonic hedgehog-WNT signaling and neurovascular molecules: Implications for blood-brain barrier integrity in autism spectrum disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disease originating from combined genetic and environmental factors. Post-mortem human studies and some animal ASD models have shown brain neuroinflammation, oxidative stress, and changes in blood-brain barrier (BBB) integrity. However, the signaling pathways leading to these inflammatory findings and vascular alterations are currently unclear. The BBB plays a critical role in controlling brain homeostasis and immune response. Its dysfunction can result from developmental genetic abnormalities or neuroinflammatory processes. In this review, we explore the role of the Sonic Hedgehog/Wingless-related integration site (Shh/Wnt) pathways in neurodevelopment, neuroinflammation, and BBB development. The balance between Wnt-β-catenin and Shh pathways controls angiogenesis, barriergenesis, neurodevelopment, central nervous system (CNS) morphogenesis, and neuronal guidance. These interactions are critical to maintain BBB function in the mature CNS to prevent the influx of pathogens and inflammatory cells. Genetic mutations of key components of these pathways have been identified in ASD patients and animal models, which correlate with the severity of ASD symptoms. Disruption of the Shh/Wnt crosstalk may therefore compromise BBB development and function. In turn, impaired Shh signaling and glial activation may cause neuroinflammation that could disrupt the BBB. Elucidating how ASD-related mutations of Shh/Wnt signaling could cause BBB leaks and neuroinflammation will contribute to our understanding of the role of their interactions in ASD pathophysiology. These observations may provide novel targeted therapeutic strategies to prevent or alleviate ASD symptoms while preserving normal developmental processes. Cover Image for this issue: https://doi.org/10.1111/jnc.15081.

Potential crosstalk between sonic hedgehog-WNT signaling and neurovascular molecules: Implications for blood-brain barrier integrity in autism spectrum disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental disease originating from combined genetic and environmental factors. Post-mortem human studies and some animal ASD models have shown brain neuroinflammation, oxidative stress, and changes in blood-brain barrier (BBB) integrity. However, the signaling pathways leading to these inflammatory findings and vascular alterations are currently unclear. The BBB plays a critical role in controlling brain homeostasis and immune response. Its dysfunction can result from developmental genetic abnormalities or neuroinflammatory processes. In this review, we explore the role of the Sonic Hedgehog/Wingless-related integration site (Shh/Wnt) pathways in neurodevelopment, neuroinflammation, and BBB development. The balance between Wnt-β-catenin and Shh pathways controls angiogenesis, barriergenesis, neurodevelopment, central nervous system (CNS) morphogenesis, and neuronal guidance. These interactions are critical to maintain BBB function in the mature CNS to prevent the influx of pathogens and inflammatory cells. Genetic mutations of key components of these pathways have been identified in ASD patients and animal models, which correlate with the severity of ASD symptoms. Disruption of the Shh/Wnt crosstalk may therefore compromise BBB development and function. In turn, impaired Shh signaling and glial activation may cause neuroinflammation that could disrupt the BBB. Elucidating how ASD-related mutations of Shh/Wnt signaling could cause BBB leaks and neuroinflammation will contribute to our understanding of the role of their interactions in ASD pathophysiology. These observations may provide novel targeted therapeutic strategies to prevent or alleviate ASD symptoms while preserving normal developmental processes.

Microbiota and Microglia Interactions in ASD

Autism spectrum disorders (ASD) are serious, highly variable neurodevelopmental disorders, commonly characterized by the manifestation of specific behavioral abnormalities, such as stereotypic behaviors and deficits in social skills, including communication. Although the neurobiological basis for ASD has attracted attention in recent decades, the role of microglial cells, which are the main resident myeloid cell population in the brain, is still controversial and underexplored. Microglia play several fundamental roles in orchestrating brain development and homeostasis. As such, alterations in the intrinsic functions of these cells could be one of the driving forces responsible for the development of various neurodevelopmental disorders, including ASD. Microglia are highly sensitive to environmental cues. Amongst the environmental factors known to influence their intrinsic functions, the gut microbiota has emerged as a central player, controlling both microglial maturation and activation. Strikingly, there is now compelling data suggesting that the intestinal microbiota can play a causative role in driving the behavioural changes associated with ASD. Not only is intestinal dysbiosis commonly reported in ASD patients, but therapies targeting the microbiome can markedly alleviate behavioral symptoms. Here we explore the emerging mechanisms by which altered microglial functions could contribute to several major etiological factors of ASD. We then demonstrate how pre- and postnatal environmental stimuli can modulate microglial cell phenotype and function, underpinning the notion that reciprocal interactions between microglia and intestinal microbes could play a crucial role in ASD aetiology.

The histamine H3R and dopamine D2R/D3R antagonist ST-713 ameliorates autism-like behavioral features in BTBR T+tf/J mice by multiple actions

Several brain neurotransmitters, including histamine (HA), acetylcholine (ACh), and dopamine (DA) are suggested to be involved in several brain disorders including cognitive deficits, depression, schizophrenia, anxiety, and narcolepsy, all of which are comorbid with Autism spectrum disorder (ASD). Therefore, the ameliorative effects of the novel multiple-active compound ST-713 with high binding affinities at histamine H3 receptor (H3R), dopamine D2sR and D3R on ASD-like behaviors in male BTBR T+tf/J mice model were assessed. ST-713 (3-(2-chloro-10H-phenothiazin-10-yl)-N-methyl-N-(4-(3-(piperidin-1-yl)propoxy)benzyl)propan-1-amine; 2.5, 5, and 10 mg/kg, i.p.) ameliorated dose-dependently social deficits, and significantly alleviated the repetitive/compulsive behaviors of BTBR mice (all P < 0.05). Moreover, ST-713 modulated disturbed anxiety levels, but failed to obliterate increased hyperactivity of tested mice. Furthermore, ST-713 (5 mg/kg) attenuated the increased levels of hippocampal and cerebellar protein expressions of NF-κB p65, COX-2, and iNOS in BTBR mice (all P < 0.05). The ameliorative effects of ST-713 on social parameters were entirely reversed by co-administration of the H3R agonist (R)-α-methylhistamine or the anticholinergic drug scopolamine. The obtained results demonstrate the potential of multiple-active compounds for the therapeutic management of neuropsychiatric disorders, e.g. ASD.

Neonatal curcumin treatment restores hippocampal neurogenesis and improves autism-related behaviors in a mouse model of autism

RATIONALE

Autism spectrum disorders (ASDs) are highly prevalent neurodevelopmental disorders characterized by deficits in social communication and interaction, repetitive stereotyped behaviors, and cognitive impairments. Curcumin has been indicated to be neuroprotective against neurological and psychological disorders. However, the role of curcumin in autistic phenotypes remains unclear.

OBJECTIVES

In the current study, we evaluated the effects of neonatal curcumin treatment on behavior and hippocampal neurogenesis in BTBRT⁺ltpr3^tf/J (BTBR) mice, a model of autism.

METHODS

C57BL/6J (C57) and BTBR mouse pups were treated with 0.1% dimethyl sulfoxide (DMSO) or curcumin (20 mg/kg) from postnatal day 6 (P6) to P8. Neural progenitor cells (NPCs) in the hippocampal dentate gyrus (DG) were evaluated on P8, and neurogenesis was measured on P24 by immunofluorescence. A battery of behavioral tests was carried out when the mice were 8 weeks of age.

RESULTS

Neonatal curcumin treatment improved autism-related symptoms in BTBR mice, enhancing sociability, reducing repetitive behaviors, and ameliorating cognitive impairments. Furthermore, the suppression of hippocampal neurogenesis in BTBR mice was greatly rescued after neonatal curcumin treatment, leading to an increase in neurogenic processes and an increase in NPC proliferation concomitant with an expansion of the NPC pool on P8, and NPC differentiation towards the neuronal lineage was promoted in the DG of BTBR mice on P24.

CONCLUSIONS

Our findings suggest that neonatal curcumin treatment elicits a therapeutic response through the restoration of hippocampal neurogenesis in BTBR mice and thus may represent a promising novel pharmacological strategy for ASD treatment.

Cyclooxygenase Inhibition Safety and Efficacy in Inflammation-Based Psychiatric Disorders

According to the World Health Organization, the major psychiatric and neurodevelopmental disorders include major depression, bipolar disorder, schizophrenia, and autism spectrum disorder. The potential role of inflammation in the onset and progression of these disorders is increasingly being studied. The use of non-steroidal anti-inflammatory drugs (NSAIDs), well-known cyclooxygenase (COX) inhibitors, combined with first-choice specific drugs have been long investigated. The adjunctive administration of COX inhibitors to classic clinical treatments seems to improve the prognosis of people who suffer from psychiatric disorders. In this review, a broad overview of the use of COX inhibitors in the treatment of inflammation-based psychiatric disorders is provided. For this purpose, a critical analysis of the use of COX inhibitors in the last ten years of clinical trials of the major psychiatric disorders was carried out.

Methylmercury chloride exposure aggravates proinflammatory mediators and Notch-1 signaling in CD14+ and CD40+ cells and is associated with imbalance of neuroimmune function in BTBR T+ Itpr3tf/J mice

Autism spectrum disorder (ASD) is a severe neurodevelopmental disorder characterized by deficits in social interaction, communication, and repetitive behaviors. A key role for immune dysfunction has been suggested in ASD. Recent studies have indicated that inflammatory mediators and Notch-1 signaling may contribute to the development of ASD. Methylmercury chloride (MeHgCl) is an environmental pollutant that primarily affects the central nervous system, causing neurological alterations. Its effects on immunological responses have not been fully investigated in ASD. In this study, we examined the influence of MeHgCl exposure on inflammatory mediators and Notch-1 signaling in BTBR T⁺ Itpr3tf/J (BTBR) mice, a model of ASD. We examined the effects of MeHgCl on the IL-6-, GM-CSF-, NF-κB p65-, Notch-1-, and IL-27-producing CD14⁺ and CD40⁺ cells in the spleen. We assessed the effect of MeHgCl on IL-6, GM-CSF, NF-κB p65, Notch-1, and IL-27 mRNA levels in brain tissue. We also measured IL-6, GM-CSF, and NF-κB p65 protein expression levels in brain tissue. MeHgCl exposure of BTBR mice significantly increased IL-6-, GM-CSF-, NF-κB p65-, and Notch-1-, and decreased IL-27-producing CD14⁺, and CD40⁺ cells in the spleen. MeHgCl exposure of BTBR mice upregulated IL-6, GM-CSF, NF-κB p65, and Notch-1, and decreased IL-27 mRNA expression levels in brain tissue. Moreover, MeHgCl resulted in elevated expression of the IL-6, GM-CSF, and NF-κB p65 proteins in brain tissue. Taken together, these results indicate that MeHgCl exposure aggravates proinflammatory mediators and Notch-1 signaling which are associated with imbalance of neuroimmune function in BTBR mice.

Association between peripheral blood levels of C-reactive protein and Autism Spectrum Disorder in children: A systematic review and meta-analysis

INTRODUCTION

In the past five years, a growing number of studies have tried to illustrate the association between the peripheral blood level of C-reactive protein (CRP) and Autism Spectrum Disorders (ASD). However, the results have been inconsistent. To assess whether abnormal CRP in peripheral blood was associated with ASD, we conducted a systematic review and meta-analysis.

METHODS

A systematic literature search was performed using the Embase, PubMed, Web of Knowledge, PsycINFO, and Cochrane databases through August 27, 2019. Reference lists were also checked by hand-searching. Clinical studies exploring CRP concentration in the peripheral blood of autistic children and healthy controls were included in our meta-analysis. Overlapping samples were excluded. We pooled obtained data using a fixed- or random-effect model based on a heterogeneity test with Comprehensive Meta-Analysis software and STATA software. Standardized mean differences were converted to Hedges' g statistic in order to obtain the effect size adjusted for sample size. Subgroup analyses, sensitivity analyses, meta-regression, and publication bias tests were also undertaken.

RESULTS

Nine studies with 592 ASD children and 604 healthy children were included in our meta-analysis. Significantly elevated CRP levels in peripheral blood were found in ASD children compared with healthy controls (Hedges' g = 0.527, 95% CI: 0.224-0.830, p = 0.001). Subgroup analyses based on sample types and ethnicity also showed similar results, except for the plasma subgroup. There was also a significant association between peripheral CRP concentration and ASD after removing the studies identified by Galbraith plots. The results of the sensitivity analysis revealed that no single study could reverse our results. Meta-regression analyses revealed that the gender of autistic children had a moderating effect on the outcome of the meta-analysis. In addition, no obvious publication bias was found in the meta-analysis.

CONCLUSIONS AND RELEVANCE

In our study, peripheral CRP levels were significantly elevated in autistic children compared with healthy children. These results may provide us some new insights about ASD.

Beneficial Effects of Fingolimod on Social Interaction, CNS and Peripheral Immune Response in the BTBR Mouse Model of Autism

Autism Spectrum Disorders (ASD) are neurodevelopmental disorders characterized by social communication deficits and repetitive/stereotyped behaviours. We evaluated the effects of a chronic treatment with the immunomodulator drug Fingolimod (FTY720 - a non-selective Sphingosine 1-Phosphate Receptor ligand) in an ASD model, the BTBR T⁺tf/J (BTBR) mouse strain. In adult BTBR males, chronic FTY720 treatment (4 weeks) increased social and vocal response during a male-female interaction and hippocampal expression of BDNF and Neuregulin 1, two trophic factors reduced in BTBR when compared to control C57 mice. FTY720 also re-established the expression of IL-1β and MnSOD in the hippocampus, whereas it did not modify IL-6 mRNA content. In addition to its central effect, FTY720 modulated the activation state of peripheral macrophages in the BTBR model, both in basal conditions and after stimulation with an immune challenge. Furthermore, IL-6 mRNA colonic content of BTBR mice, reduced when compared with C57 mice, was normalized by chronic treatment with FTY720. Our study, while indicating FTY720 as a tool to attenuate relevant alterations of the BTBR neurobehavioural phenotype, emphasizes the importance of gut mucosal immune evaluation as an additional target that deserve to be investigated in preclinical studies of anti-inflammatory therapeutic approaches in ASD.

Oxidative Stress and Immune System Dysfunction in Autism Spectrum Disorders

Autism Spectrum Disorders (ASDs) represent a group of neurodevelopmental disorders associated with social and behavioral impairments. Although dysfunctions in several signaling pathways have been associated with ASDs, very few molecules have been identified as potentially effective drug targets in the clinic. Classically, research in the ASD field has focused on the characterization of pathways involved in neural development and synaptic plasticity, which support the pathogenesis of this group of diseases. More recently, immune system dysfunctions have been observed in ASD. In addition, high levels of reactive oxygen species (ROS), which cause oxidative stress, are present in ASD patients. In this review, we will describe the major alterations in the expression of genes coding for enzymes involved in the ROS scavenging system, in both ASD patients and ASD mouse models. In addition, we will discuss, in the context of the most recent literature, the possibility that oxidative stress, inflammation and immune system dysfunction may be connected to, and altogether support, the pathogenesis and/or severity of ASD. Finally, we will discuss the possibility of novel treatments aimed at counteracting the interplay between ROS and inflammation in people with ASD.

Chromatin Dynamics and Genetic Variation Combine to Regulate Innate Immune Memory

Recent work by Ciernia et al. (2020) identified how genetic and epigenetic mechanisms interact to regulate innate immune memory in bone marrow derived macrophages. The authors examined the BTBR strain, a naturally occurring mouse model of Autism Spectrum Disorder (ASD) that captures the complex genetics, behavioral and immune dysregulation found in the human disorder. Immune cell cultures from the BTBR strain compared to the standard C57 showed hyper-responsive immune gene expression that was linked to altered chromatin accessibility at sites with genetic differences between the strains. Together, findings from this work demonstrated that multiple levels of gene regulation likely dictate the formation of innate immune memory and are likely disrupted in immune cells in ASD. Future work will be needed to extend these findings to immune gene regulation in the brain and how changes in immune function are related to abnormal behaviors in brain disorders.

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.

Increased oxidative stress in the cerebellum and peripheral immune cells leads to exaggerated autism-like repetitive behavior due to deficiency of antioxidant response in BTBR T + tf/J mice

Autism is a neurodevelopmental disorder that affects social cognitive abilities resulting in communication or sensory deficits, and stereotyped behaviors in millions of people worldwide. Oxidant-antioxidant imbalance contributes significantly to the neurobehavioral dysregulations and severity of symptoms in patients with autism, however it has not been explored earlier whether it affects autism-like behavior directly. Therefore, we investigated oxidant-antioxidant balance in peripheral immune cells (neutrophils and CD3+ T cells) and cerebellum of BTBR T + tf/J (BTBR) mice which show autism-like behavior and the social C57BL/6 J (C57) mice. Further, we utilized buthionine sulfoximine (BSO), a glutathione depleting agent to assess the impact of oxidant-antioxidant dysregulation on autism-like behavior. Our study shows that BTBR mice have increased lipid/protein oxidation products in cerebellum and neutrophils/CD3+ T cells along with increased NADPH oxidase (NOX2) and inducible nitric oxide synthase (iNOS) expression. This was concurrent with lower levels of glutathione and enzymatic antioxidants such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the cerebellum and peripheral immune cells. BSO administration led to further lowering of glutathione with a concurrent upregulation of iNOS, and NOX2 in cerebellum and peripheral immune cells. However, there was deficiency of an adaptive antioxidant response which was associated with exaggerated repetitive behaviors in BTBR mice. On the other hand, C57 mice also had increased oxidative stress after BSO treatment, however there was an enzymatic antioxidant response both in cerebellum and periphery. Overall, this study suggests that BTBR mice have increased oxidative stress with a deficient enzymatic antioxidant response that is associated with autism-like repetitive behaviors.

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

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

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.

Neurobiology and Therapeutic Potential of Cyclooxygenase-2 (COX-2) Inhibitors for Inflammation in Neuropsychiatric Disorders

Neuropsychiatric disorders, such as depression, bipolar disorder, schizophrenia, obsessive-compulsive disorder, and neurodevelopmental disorders such as autism spectrum disorder, are associated with significant illness burden. Accumulating evidence supports an association between these disorders and inflammation. Consequently, anti-inflammatory agents, such as the cyclooxygenase-2 inhibitors, represent a novel avenue to prevent and treat neuropsychiatric illness. In this paper, we first review the role of inflammation in psychiatric pathophysiology including inflammatory cytokines' influence on neurotransmitters, the hypothalamic-pituitary-adrenal axis, and microglial mechanisms. We then discuss how cyclooxygenase-2-inhibitors influence these pathways with potential therapeutic benefit, with a focus on celecoxib, due to its superior safety profile. A search was conducted in PubMed, Embase, and PsychINFO databases, in addition to Clinicaltrials.gov and the Stanley Medical Research Institute trial registries. The results were presented as a narrative review. Currently available outcomes for randomized controlled trials up to November 2017 are also discussed. The evidence reviewed here suggests cyclooxygenase-2 inhibitors, and in particular celecoxib, may indeed assist in treating the symptoms of neuropsychiatric disorders; however, further studies are required to assess appropriate illness stage-related indication.

A systematic review of gut-immune-brain mechanisms in Autism Spectrum Disorder

Despite decades of research, the etiological origins of Autism Spectrum Disorder (ASD) remain elusive. Recently, the mechanisms of ASD have encompassed emerging theories involving the gastrointestinal, immune, and nervous systems. While each of these perspectives presents its own set of supporting evidence, the field requires an integration of these modular concepts and an overarching view of how these subsystems intersect. In this systematic review, we have synthesized relevant evidences from the existing literature, evaluating them in an interdependent manner and in doing so, outlining their possible connections. Specifically, we first discussed gastrointestinal and immuno-inflammation pathways in-depth, exploring the relationships between microbial composition, bacterial metabolites, gut mucosa, and immune system constituents. Accounting for temporal differences in the mechanisms involved in neurodevelopment, prenatal and postnatal phases were further elucidated, where the former focused on maternal immune activation (MIA) and fetal development, while the latter addressed the role of immune dysregulation in contributing to atypical neurodevelopment. As autism remains, foremost, a neurodevelopmental disorder, this review presents an integration of disparate modules into a "Gut-Immune-Brain" paradigm. Existing gaps in the literature have been highlighted, and possible avenues for future research with an integrated physiological perspective underlying ASD have also been suggested.

From bedside to bench and back: Translating ASD models

Autism spectrum disorders (ASD) represent a heterogeneous group of disorders defined by deficits in social interaction/communication and restricted interests, behaviors, or activities. Models of ASD, developed based on clinical data and observations, are used in basic science, the "bench," to better understand the pathophysiology of ASD and provide therapeutic options for patients in the clinic, the "bedside." Translational medicine creates a bridge between the bench and bedside that allows for clinical and basic science discoveries to challenge one another to improve the opportunities to bring novel therapies to patients. From the clinical side, biomarker work is expanding our understanding of possible mechanisms of ASD through measures of behavior, genetics, imaging modalities, and serum markers. These biomarkers could help to subclassify patients with ASD in order to better target treatments to a more homogeneous groups of patients most likely to respond to a candidate therapy. In turn, basic science has been responding to developments in clinical evaluation by improving bench models to mechanistically and phenotypically recapitulate the ASD phenotypes observed in clinic. While genetic models are identifying novel therapeutics targets at the bench, the clinical efforts are making progress by defining better outcome measures that are most representative of meaningful patient responses. In this review, we discuss some of these challenges in translational research in ASD and strategies for the bench and bedside to bridge the gap to achieve better benefits to patients.

BTBR ob/ob mouse model of type 2 diabetes exhibits early loss of retinal function and retinal inflammation followed by late vascular changes

AIMS/HYPOTHESIS

Diabetic retinopathy is increasing in prevalence worldwide and is fast becoming a global epidemic and a leading cause of visual loss. Current therapies are limited, and the development of effective treatments for diabetic retinopathy requires a greater in-depth knowledge of disease progression and suitable modelling of diabetic retinopathy in animals. The aim of this study was to assess the early pathological changes in retinal morphology and neuronal, inflammatory and vascular features consistent with diabetic retinopathy in the ob/ob mouse model of type 2 diabetes, to investigate whether features similar to those in human diabetic retinopathy were present.

METHODS

Male and female wild-type (+/+), heterozygous (+/-) and homozygous (-/-) BTBR ob/ob mice were examined at 6, 10, 15 and 20 weeks of age. Animals were weighed and blood glucose was measured. TUNEL and brain-specific homeobox/POU domain protein 3A (BRN3A) markers were used to examine retinal ganglion cells. We used immunostaining (collagen IV and platelet endothelial cell adhesion molecule [PECAM]/CD31) to reveal retinal vessel degeneration. Spectral domain optical coherence tomography was used to reveal changes in the thickness and structure of the retinal layer. Vitreous fluorophotometry was used to investigate vascular permeability. A-waves, b-waves and oscillatory potentials were measured under photopic and scotopic conditions. Concanavalin A leucostasis and immunostaining with glial fibrillary acidic protein (GFAP) and ionised calcium-binding adapter molecule 1 (IBA-1) identified differences in inflammatory status. Paraffin sections and transmission electron microscopy were used to reveal changes in the thickness and structure of the retinal layer.

RESULTS

Following the development of obesity and hyperglycaemia in 2-week-old and 3-week-old ob^-/ob^- mice, respectively (p < 0.001), early functional deficits (p < 0.001) and thinning of the inner retina (p < 0.001) were identified. Glial activation, leucostasis (p < 0.05) and a shift in microglia/macrophage phenotype were observed before microvascular degeneration (p < 0.05) and elevated vascular permeability occurred (p < 0.05).

CONCLUSIONS/INTERPRETATION

The present characterisation of the development of diabetic retinopathy in the ob/ob mouse represents a platform that will enable the development of new therapies, particularly for the early stages of disease.

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.