Gastrointestinal issues in autism spectrum disorder

The Role of Lipidomics in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome commonly diagnosed in early childhood; it is usually characterized by impairment in reciprocal communication and speech, repetitive behaviors, and social withdrawal with loss in communication skills. Its development may be affected by a variety of environmental and genetic factors. Trained physicians diagnose and evaluate the severity of ASD based on clinical evaluations of observed behaviors. As such, this approach is inevitably dependent on the expertise and subjective assessment of those administering the clinical evaluations. There is a need to identify objective biological markers associated with diagnosis or clinical severity of the disorder. Several important issues and concerns exist regarding the diagnostic competence of the many abnormal plasma metabolites produced in the different biochemical pathways evaluated in individuals with ASD. The search for high-performing bio-analytes to diagnose and follow-up ASD development is still a major target in medicine. Dysregulation in the oxidative stress response and proinflammatory processes are major etiological causes of ASD pathogenesis. Furthermore, dicarboxylic acid metabolites, cholesterol-related metabolites, phospholipid-related metabolites, and lipid transporters and mediators are impaired in different pathological conditions that have a role in the ASD etiology. A mechanism may exist by which pro-oxidant environmental stressors and abnormal metabolites regulate clinical manifestations and development of ASD.

Autism Spectrum Disorder from the Womb to Adulthood: Suggestions for a Paradigm Shift

The wide spectrum of unique needs and strengths of Autism Spectrum Disorders (ASD) is a challenge for the worldwide healthcare system. With the plethora of information from research, a common thread is required to conceptualize an exhaustive pathogenetic paradigm. The epidemiological and clinical findings in ASD cannot be explained by the traditional linear genetic model, hence the need to move towards a more fluid conception, integrating genetics, environment, and epigenetics as a whole. The embryo-fetal period and the first two years of life (the so-called 'First 1000 Days') are the crucial time window for neurodevelopment. In particular, the interplay and the vicious loop between immune activation, gut dysbiosis, and mitochondrial impairment/oxidative stress significantly affects neurodevelopment during pregnancy and undermines the health of ASD people throughout life. Consequently, the most effective intervention in ASD is expected by primary prevention aimed at pregnancy and at early control of the main effector molecular pathways. We will reason here on a comprehensive and exhaustive pathogenetic paradigm in ASD, viewed not just as a theoretical issue, but as a tool to provide suggestions for effective preventive strategies and personalized, dynamic (from womb to adulthood), systemic, and interdisciplinary healthcare approach.

Cannabidiol and Neurodevelopmental Disorders in Children

Neurodevelopmental and neuropsychiatric disorders (such as autism spectrum disorder) have broad health implications for children, with no definitive cure for the vast majority of them. However, recently medicinal cannabis has been successfully trialled as a treatment to manage many of the patients' symptoms and improve quality of life. The cannabinoid cannabidiol, in particular, has been reported to be safe and well-tolerated with a plethora of anticonvulsant, anxiolytic and anti-inflammatory properties. Lately, the current consensus is that the endocannabinoid system is a crucial factor in neural development and health; research has found evidence that there are a multitude of signalling pathways involving neurotransmitters and the endocannabinoid system by which cannabinoids could potentially exert their therapeutic effects. A better understanding of the cannabinoids' mechanisms of action should lead to improved treatments for neurodevelopmental disorders.

Multivariate Analysis of Fecal Metabolites from Children with Autism Spectrum Disorder and Gastrointestinal Symptoms before and after Microbiota Transfer Therapy

Fecal microbiota transplant (FMT) holds significant promise for patients with Autism Spectrum Disorder (ASD) and gastrointestinal (GI) symptoms. Prior work has demonstrated that plasma metabolite profiles of children with ASD become more similar to those of their typically developing (TD) peers following this treatment. This work measures the concentration of 669 biochemical compounds in feces of a cohort of 18 ASD and 20 TD children using ultrahigh performance liquid chromatography-tandem mass spectroscopy. Subsequent measurements were taken from the ASD cohort over the course of 10-week Microbiota Transfer Therapy (MTT) and 8 weeks after completion of this treatment. Univariate and multivariate statistical analysis techniques were used to characterize differences in metabolites before, during, and after treatment. Using Fisher Discriminant Analysis (FDA), it was possible to attain multivariate metabolite models capable of achieving a sensitivity of 94% and a specificity of 95% after cross-validation. Observations made following MTT indicate that the fecal metabolite profiles become more like those of the TD cohort. There was an 82-88% decrease in the median difference of the ASD and TD group for the panel metabolites, and among the top fifty most discriminating individual metabolites, 96% report more comparable values following treatment. Thus, these findings are similar, although less pronounced, as those determined using plasma metabolites.

Immune Modulatory Treatments for Autism Spectrum Disorder

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

Evaluation of antibiotic-induced behavioral changes in mice

Gut microbiota (GM) plays a critical role in health maintenance. Previous reports connected GM with metabolic, immunologic and neurologic pathways. The main purpose of the current investigation was to study whether antibiotic-induced disturbances of GM affects psychological or behavioral conditions on mice as animal model. Mice were exposed to clindamycin or amoxicillin, and their behaviors were evaluated. Antibiotic-treated groups displayed reduced recognition memory and increased depression. No significant changes in the locomotor activity and anxiety were observed. Our data suggested that changes in GM composition by antibiotics may lead to the cognitive and behavioral deficit.

Polifenollerin Bağırsak Mikrobiyota Kompozisyonunu Düzenleyici ve Nöroprotektif Etkileri

Trilyonlarca mikroorganizmadan oluşan ve doğumdan yaşlılığa kadar konakçı ile etkileşim halinde bulunan bağırsak mikrobiyotası; doğum şekli, beslenme alışkanlıkları, yaş, hastalık durumu, antibiyotik kullanımı, çevresel ve kültürel faktörlere bağlı olarak değişiklik göstermektedir. Böğürtlen, üzüm, elma, portakal, baklagiller, çay, kakao, bal ve şarap gibi polifenol açısından zengin gıdalar bağırsak mikrobiyota kompozisyonunu düzenleyebilmektedir. Bu durum polifenollerin bağırsak bakterileri üzerinde prebiyotik etki göstermeleri ile açıklanmaktadır. Bağırsak ve nörolojik hastalıkların gelişiminde, beyin ve bağırsak arasında çift yönlü ilişki ön plana çıkmaktadır. Bu ilişkiye beyin-bağırsak hattı denilmektedir. Mikrobiyota kompozisyonundaki olumsuz yöndeki değişiklikler sonucu görülen disbiyozis, beyin-bağırsak hattı dengesi için önemli sorun teşkil etmektedir. Polifenoller, beyin-bağırsak hattının modülasyonu yoluyla, bağırsak ve nörolojik hastalıkların tedavisinde yararlı etkiler sunmaktadır. Polifenollerin yararlı etkileri sadece bağırsak mikrobiyotasını düzenleyebilme yetenekleri ile değil, aynı zamanda beyin nöroenflamasyonunu azaltma, hafıza ve bilişsel işlevi geliştirme yetenekleriyle de açıklanabilmektedir. Bu özellikleri polifenolleri nörodejeneratif bozukluklar ve kardiyovasküler rahatsızlıklar başta olmak üzere birçok hastalıkla mücadele etmek için umut verici nutrasötikler konumuna getirmektedir. Bu makalenin amacı mikrobiyata çeşitliliğinde azalması ya da mikrobiyota kompozisyonunun arzu edilmeyen şekilde değişmesi ile ilişkilendirilen çeşitli bağırsak ve nörolojik hastalıklara karşı önemli işlevleri bulunan polifenollerin, insan sağlığına yararlı etkileri hakkında güncel bilgileri derlemektir.

Primary care of children with autism spectrum disorder: Applying evidence-based interventions

Pediatric autism spectrum disorder (ASD) consists of multisystem components that primary care providers (PCPs) must address. PCPs improve health outcomes associated with ASD when they administer developmental screening tools and thoroughly assess identified concerns. Pursuing specialty health services early in childhood combined with managing comorbid conditions curtails symptom escalation and disease progression.

Oxytocin Differentiated Effects According to the Administration Route in a Prenatal Valproic Acid-Induced Rat Model of Autism

Background and objectives: The hormone oxytocin (OXT) has already been reported in both human and animal studies for its promising therapeutic potential in autism spectrum disorder (ASD), but the comparative effectiveness of various administration routes, whether central or peripheral has been insufficiently studied. In the present study, we examined the effects of intranasal (IN) vs. intraperitoneal (IP) oxytocin in a valproic-acid (VPA) autistic rat model, focusing on cognitive and mood behavioral disturbances, gastrointestinal transit and central oxidative stress status. Materials and Methods: VPA prenatally-exposed rats (500 mg/kg; age 90 days) in small groups of 5 (n = 20 total) were given OXT by IP injection (10 mg/kg) for 8 days consecutively or by an adapted IN pipetting protocol (12 IU/kg, 20 μL/day) for 4 consecutive days. Behavioral tests were performed during the last three days of OXT treatment, and OXT was administrated 20 minutes before each behavioral testing for each rat. Biochemical determination of oxidative stress markers in the temporal area included superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA). A brief quantitative assessment of fecal discharge over a period of 24 hours was performed at the end of the OXT treatment to determine differences in intestinal transit. Results: OXT improved behavioral and oxidative stress status in both routes of administration, but IN treatment had significantly better outcome in improving short-term memory, alleviating depressive manifestations and mitigating lipid peroxidation in the temporal lobes. Significant correlations were also found between behavioral parameters and oxidative stress status in rats after OXT administration. The quantitative evaluation of the gastrointestinal (GI) transit indicated lower fecal pellet counts in the VPA group and homogenous average values for the control and both OXT treated groups. Conclusions: The data from the present study suggest OXT IN administration to be more efficient than IP injections in alleviating autistic cognitive and mood dysfunctions in a VPA-induced rat model. OXT effects on the cognitive and mood behavior of autistic rats may be associated with its effects on oxidative stress. Additionally, present results provide preliminary evidence that OXT may have a balancing effect on gastrointestinal motility.

Assessment of haptoglobin alleles in autism spectrum disorders

Gene-environment interactions, by means of abnormal macromolecular intestinal adsorption, is one of the possible causes of autism spectrum disorders (ASD) predominantly in patients with gastrointestinal disorders. Pre-haptoglobin-2 (zonulin), encoded by the Haptoglobin (HP) allele-2 gene, enhances the intestinal permeability by modulation of intercellular tight junctions. The two alleles of HP, HP1 and HP2, differ for 2 extra exons in HP2 that result in exon duplication undetectable by classic genome-wide association studies. To evaluate the role of HP2 in ASD pathogenesis and to set up a method to discriminate HP alleles, Italian subjects with ASD (n = 398) and healthy controls (n = 379) were genotyped by PCR analysis; subsequently, the PCR results were integrated with microarray genotypes (Illumina Human Omni 1S-8), obtained using a subset from the same subjects, and then we developed a computational method to predict HP alleles. On the contrary to our expectations, there was no association between HP2 and ASD (P > 0.05), and there was no significant allele association in subjects with ASD with or without gastrointestinal disorders (P > 0.05). With the aid of bioinformatics analysis, from a window frame of ~2 Mb containing 314 SNPs, we obtain imputation accuracy (r²) between 0.4 and 0.9 (median 0.7) and correct predictions were between 70% and 100% (median 90%). The conclusions endorse that enhanced intestinal permeability in subjects with ASD should not be imputed to HP2 but to other members of the zonulin family and/or to environmental factors.

A large population-based investigation into the genetics of susceptibility to gastrointestinal infections and the link between gastrointestinal infections and mental illness

Gastrointestinal infections can be life threatening, but not much is known about the host's genetic contribution to susceptibility to gastrointestinal infections or the latter's association with psychiatric disorders. We utilized iPSYCH, a genotyped population-based sample of individuals born between 1981 and 2005 comprising 65,534 unrelated Danish individuals (45,889 diagnosed with mental disorders and 19,645 controls from a random population sample) in which all individuals were linked utilizing nationwide population-based registers to estimate the genetic contribution to susceptibility to gastrointestinal infections, identify genetic variants associated with gastrointestinal infections, and examine the link between gastrointestinal infections and psychiatric and neurodevelopmental disorders. The SNP heritability of susceptibility to gastrointestinal infections ranged from 3.7% to 6.4% on the liability scale. Significant correlations were found between gastrointestinal infections and the combined group of mental disorders (OR = 2.09; 95% CI: 1.82-2.4, P = 1.87 × 10-25). Correlations with autism spectrum disorder, attention deficit hyperactivity disorder, and depression were also significant. We identified a genome-wide significant locus associated with susceptibility to gastrointestinal infections (OR = 1.13; 95% CI: 1.08-1.18, P = 2.9 × 10-8), where the top SNP was an eQTL for the ABO gene. The risk allele was associated with reduced ABO expression, providing, for the first time, genetic evidence to support previous studies linking the O blood group to gastrointestinal infections. This study also highlights the importance of integrative work in genetics, psychiatry, infection, and epidemiology on the road to translational medicine.

Gut microbiome composition and diversity are related to human personality traits

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Investigation of gut microbiome composition and diversity with respect to human personality.

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Analyses targeted bacterial genera linked to behaviour in animal and human psychiatric studies.

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Bacterial genera were modelled (using negative binomial regression) with respect to personality.

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Genera linked to autism are also related to social behaviour in the general population.

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Sociability is associated with higher diversity, and anxiety and stress with reduced diversity.

The gut microbiome has a measurable impact on the brain, influencing stress, anxiety, depressive symptoms and social behaviour. This microbiome–gut–brain axis may be mediated by various mechanisms including neural, immune and endocrine signalling. To date, the majority of research has been conducted in animal models, while the limited number of human studies has focused on psychiatric conditions. Here the composition and diversity of the gut microbiome is investigated with respect to human personality. Using regression models to control for possible confounding factors, the abundances of specific bacterial genera are shown to be significantly predicted by personality traits. Diversity analyses of the gut microbiome reveal that people with larger social networks tend to have a more diverse microbiome, suggesting that social interactions may shape the microbial community of the human gut. In contrast, anxiety and stress are linked to reduced diversity and an altered microbiome composition. Together, these results add a new dimension to our understanding of personality and reveal that the microbiome–gut–brain axis may also be relevant to behavioural variation in the general population as well as to cases of psychiatric disorders.

Gastrointestinal tract modeling using organoids engineered with cellular and microbiota niches

The recent emergence of organoid technology has attracted great attention in gastroenterology because the gastrointestinal (GI) tract can be recapitulated in vitro using organoids, enabling disease modeling and mechanistic studies. However, to more precisely emulate the GI microenvironment in vivo, several neighboring cell types and types of microbiota need to be integrated into GI organoids. This article reviews the recent progress made in elucidating the crosstalk between GI organoids and components of their microenvironment. We outline the effects of stromal cells (such as fibroblasts, neural cells, immune cells, and vascular cells) on the gastric and intestinal epithelia of organoids. Because of the important roles that microbiota play in the physiology and function of the GI tract, we also highlight interactions between organoids and commensal, symbiotic, and pathogenic microorganisms and viruses. GI organoid models that contain niche components will provide new insight into gastroenterological pathophysiology and disease mechanisms.

Gut Microbiota Dysbiosis Associated With Altered Production of Short Chain Fatty Acids in Children With Neurodevelopmental Disorders

While gut microbiota dysbiosis has been linked with autism, its role in the etiology of other neurodevelopmental disorders (NDD) is largely underexplored. To our knowledge this is the first study to evaluate gut microbiota diversity and composition in 36 children from the Republic of Serbia diagnosed with NDD and 28 healthy children. The results revealed an increased incidence of potentially harmful bacteria, closely related to Clostridium species, in the NDD patient group compared to the Control group: Desulfotomaculum guttoideum (P < 0.01), Intestinibacter bartlettii (P < 0.05), and Romboutsia ilealis (P < 0.001). On the other hand, significantly lower diversity of common commensal bacteria in the NDD group of patients was noticed. Enterococcus faecalis (P < 0.05), Enterococcus gallinarum (P < 0.01), Streptococcus pasteurianus (P < 0.05), Lactobacillus rhamnosus (P < 0.01) and Bifidobacteria sp. were detected in lower numbers of patients or were even absent in some NDD patients. In addition, butyrate-producing bacteria Faecalibacterium prausnitzii (P < 0.01), Butyricicoccus pullicaecorum (P < 0.05), and Eubacterium rectale (P = 0.07) were less frequent in the NDD patient group. In line with that, the levels of fecal short chain fatty acids (SCFAs) were determined. Although significant differences in SCFA levels were not detected between NDD patients and the Control group, a positive correlation was noted between number of rDNA amplicons obtained with universal primers and level of propionic acid, as well as a trend for levels of total SCFAs and butyric acid in the Control group. This correlation is lost in the NDD patient group, indicating that NDD patients' microbiota differs from the microbiota of healthy children in the presence or number of strong SCFA-producing bacteria. According to a range-weighted richness index it was observed that microbial diversity was significantly lower in the NDD patient group. Our study reveals that the intestinal microbiota from NDD patients differs from the microbiota of healthy children. It is hypothesized that early life microbiome might have an impact on GI disturbances and accompanied behavioral problems frequently observed in patients with a broad spectrum of NDD.

Microbiota and gut-brain axis dysfunction in autism spectrum disorder: Evidence for functional gastrointestinal disorders

INTRODUCTION

The high frequency of functional gastrointestinal disorders (FGIDs) in autism spectrum disorders (ASD) has drawn attention to the composition of gut microbiota as a possible factor in ASD pathogenesis. However, characterization of a distinctive ASD microbial pattern is still unclear.

OBJECTIVE

To conduct a narrative review on ASD microbial profile and diversity changes relative to NT children and FGID comorbidity and ASD pathogenesis.

METHODOLOGY

First, we searched the PubMed database in peer-reviewed journals for evidence regarding the current epidemiological evidence on FGID comorbidity. For the identification of a microbial profile in ASD children, only original studies examining gut bacterial and fungal abundances and diversity in ASD children and adolescents were included. Lastly, research on the role of microbial dysbiosis as an interface between genetic and environmental risk factors in the pathogenesis of neuropsychiatric disorders, and specifically ASD, was examined.

RESULTS

Prevalence and risk of FGIDs is significantly higher in ASD children and correlates with the severity of ASD. Bacterial and fungal diversity differ between ASD and NT children, indicating a difference in taxonomic abundance profiles, which have been reported at all bacterial phylogenetic levels. However, studies analyzing gut microbiota have a heterogeneous methodology and several limitations that could account for the variety of findings for each taxon. Also, covariate analysis reveals influence of demographics, diet, disease severity, GI comorbidity and allergies. Integration of these findings with changes in metabolome and genetic risk factors allowed for a better understanding of microbiota involvement in ASD pathogenesis for future research.

Gastrointestinal Problems in Chinese Children with Autism Spectrum Disorder

PURPOSE

Gastrointestinal symptoms in individuals with autism spectrum disorder may constitute a subgroup with complex gut-brain interactions underlying the pathogenesis. This study examined the prevalence of gastrointestinal symptoms in a sample of Chinese children with autism spectrum disorder, as well as the factors related to them.

PARTICIPANTS AND METHODS

The participants included a clinic sample of 107 children with autism spectrum disorder and 249 gender- and age-matched typically developing community children.

RESULTS

Results found children with autism spectrum disorder to be twice as likely to suffer from gastrointestinal symptoms, reporting increased rates of constipation, abdominal migraine and aerophagia. Autism spectrum disorder diagnosis remained a significant predictor of gastrointestinal symptoms after taking into account the potential confounders that included comorbid psychopathologies, diets, and parental anxiety and depression.

CONCLUSION

Our results suggest that autism spectrum disorder with gastrointestinal symptoms may constitute a subgroup within the autism spectrum disorder population that warrants further investigation.

A Descriptive Review on the Prevalence of Gastrointestinal Disturbances and Their Multiple Associations in Autism Spectrum Disorder

Background and Objectives: Gastrointestinal disturbances have been frequently, but not unanimously, reported in autism spectrum disorder (ASD) individuals. Thus, digestive symptoms, such as constipation, diarrhea, abdominal bloating, and pain have been reported to correlate to the various maladaptive behaviors in ASD children, such as irritability, social withdrawal, stereotypy, hyperactivity, and even language regression. In this context, the present study provides an overview on the prevalence of the gastrointestinal (GI) disorders in ASD and the correlation between these and ASD symptoms and comorbidities and subsequently discusses the metabolic and microbiome factors underlying the effects of GI disorders in ASD. Materials and Methods: For our analysis of GI symptoms in children with ASD, we have searched peer-reviewed journals from 2005 to 2017 in PubMed databases that addressed the specificity of GI symptoms in ASD and included correlations of GI and ASD symptoms. The criteria for inclusion were clear quantitative mentioning of GI modifications, GI symptoms correlation with specific ASD symptoms or comorbidities, an appropriate methodology for defining ASD, and larger size samples. For this topic, only studies on human patients and original research were considered. A subsequent search in PubMed databases in journals from 2000 to 2017 we analyzed 13 articles on the mechanisms underlying the impact of GI dysfunctions in ASD, including gut microbial dysbiosis, immune reactivity, genetics, and altered neurotransmitters on the gut-brain axis. Results: In the 18 original research studies that we selected out of an initial 327 studies, despite the different methodology, a predominant 83% highlighted the increased prevalence of GI symptoms in ASD patients. Constipation was most frequently cited, appearing in 12 of the studies (80%), followed by diarrhea reports in eight studies (53%). The association between cognitive and behavioral deficits and GI disorders was suggested in certain groups of ASD individuals. Conclusion: The evidence presented so far by numerous studies seems to indicate that GI dysfunctions are of particular relevance in ASD, underlined by various abnormalities along the nervous connections between the central nervous system and the gut, such as impaired parasympathetic activity and increased endocrine stress response. Sufficiently large size samples and standardized methodology are required for future studies to clarify the complex interactions between GI disturbances and ASD symptoms.

The Association Between Somatic Health, Autism Spectrum Disorder, and Autistic Traits

This study used a twin cohort to investigate the association of autism spectrum disorder (ASD) and autistic traits with somatic health. A total of 344 twins (172 pairs; mean age 15.56 ± 5.62 years) enriched for ASD and other neurodevelopmental conditions were examined. Medical history and current physical problems were collected with a validated questionnaire to determine twin’s somatic health. The Social Responsiveness Scale (SRS-2) was used to measure the participant’s severity of autistic traits. Identified somatic health issues with significant within-twin pair differences were tested in relation to both ASD diagnosis and autistic traits in a co-twin control model. Twins with ASD exhibited more neurological and immunological health problems compared to those without ASD (p = 0.005 and p = 0.004, respectively). The intra-pair differences of neurological conditions and SRS-2 score were significantly correlated in monozygotic twins differing for autism traits (r = 0.40, p = 0.001), while the correlation was not found for immunological problems. In addition, a conditional model for analysis of within-twin pair effects revealed an association between neurological problems and clinical ASD diagnosis (Odds ratio per neurological problem 3.15, p = 0.02), as well as autistic traits (β = 10.44, p = 0.006), after adjusting for possible effects of co-existing attention deficit hyperactivity disorder and general intellectual abilities. Our findings suggest that neurological problems are associated with autism, and that non-shared environmental factors contribute to the overlap for both clinical ASD and autistic traits. Further population-based twin studies are warranted to validate our results and examine in detailed the shared genetic and environmental contributions of neurological problems and ASD.

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.

Evaluation of Whole Blood Trace Element Levels in Chinese Children with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, which has increased markedly during the last decades. Essential trace elements play an important role in neurological function and their imbalances are common in children with ASD. The objective of the present study was to investigate whole blood levels of trace elements including zinc (Zn), copper (Cu), iron (Fe), and magnesium (Mg) in Chinese children with ASD. In total, 113 children diagnosed with ASD and 141 age-matched and gender-matched neurotypical children, divided into two gender and age groups of preschool age (2-5 years old) and school (6-10 years old) age, were examined. The quantitative analyses of whole blood trace element contents were performed by using flame atomic absorption spectroscopy. In the present study, the children with ASD generally had lower whole blood levels of Zn than the neurotypical controls. No significant differences in the whole blood Cu, Zn/Cu ratio, Fe, or Mg was detected between the ASD group and the control group. It is notable that whole blood Fe level in boys with ASD was significantly higher than in girls with ASD, and was nearly significant when compared with the control level of boys. After stratification for age, a significant 6% decrease in whole blood Zn levels was detected in preschool-aged children with ASD as compared to the control values. However, this significant ASD-related change was not detected in school-aged children. The whole blood Zn level and Zn/Cu ratio were significantly increased in school-aged children than in preschool-aged children in both ASD and control group. In addition, school-aged children with ASD had a significantly higher level of whole blood Fe than preschool-aged children with ASD. The results of the present study suggest an association between whole blood levels of Zn in Chinese children with ASD.

Polyphenols in the management of brain disorders: Modulation of the microbiota-gut-brain axis

The modulation of the microbiota-gut-brain axis with a view to preventing and treating brain disorders became recently a hot topic for the scientific community. Dietary polyphenols are multifaceted compounds that have demonstrated to be highly advantageous to counteract inflammation, oxidative stress, and neurodegeneration, among other pathological conditions, being useful in the prevention and treatment of several chronic disorders. The potential of these compounds to prevent and treat brain disorders has not been only related to their capacity to reach the brain, depending on their chemical structure, and interact directly with brain cells, but also to their ability to modulate the communication between the brain and the gut, interfering with multiple branches of this axis. Preclinical studies have demonstrated the potential of these food bioactive compounds in brain diseases, namely, neurodevelopmental, such as Down's syndrome and Autism spectrum disorder, neurodegenerative, such as Parkinson's disease and Alzheimer's disease, and psychiatric disorders, such as depression and anxiety. Until now, dietary polyphenols have been recognized as promising nutraceuticals to combat brain disorders. However, the impact of these compounds on the gut-brain interconnection remains poorly elucidated. Also, clinical assays are crucial to further support the beneficial effects of these compounds as demonstrated in preclinical research.

Gut-brain axis in the executive function of austism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired communication and social interactions, and repetitive behavioural patterns. These patterns are believed to be dysfunctional symptoms in executive processing, which impact other cognitive functions such as attention or cognitive flexibility. In recent years, several studies have shown that certain intestinal bacteria may play a role in shaping cognitive networks encompassing emotional and social domains. A microbiota-gut-brain axis is known to exist, establishing several mechanisms by which microbiota may modulate brain development, function and behaviour, including immune, endocrine and neural pathways. As the aetiology of ASD is largely unknown, some studies have shown that intestinal bacteria may be involved in its pathogenesis. The aim of this review was to focus on the role of the gut-brain axis in ASD and, specifically, on its role in executive functions. First, we summarize the relationship between the gastrointestinal and cognitive symptoms of ASD patients. In addition, we highlight the evidence that supports and emphasizes the involvement of gut microbiota, and the putative underlying mechanisms in this population. Finally, we present evidence from preclinical and clinical studies on the modulation of microbiota and their effects on cognitive symptoms, specifically in relation to executive function. In conclusion, manipulation of microbiota could be a positive intervention to improve ASD symptoms. However, more research evaluating the role of microbiota in the cognitive symptoms ASD is needed.

Persistent central inflammation and region specific cellular activation accompany depression- and anxiety-like behaviours during the resolution phase of experimental colitis

Depression and anxiety-related psychological symptoms are increasingly recognised as important co-morbidities in patients with inflammatory bowel disease (IBD). Dextran sulfate sodium (DSS) -induced colitis is an animal model of IBD in which afferent activation of the gut-brain axis can be assessed and explored as a source of behavioural change. Exposure of adult male Wistar rats to DSS (5%) in drinking water induced distal colitis. In parallel to local inflammatory responses in the gut wall, increased expression of IL-6 and iNOS was found in the cerebral cortex and an increase in ventricular volume. Immunoreactivity of immediate early gene FosB/ΔFosB activation was measured as an index of cellular activation and was increased in the nucleus accumbens and dorsal raphe nucleus in acutely colitic animals. Following resolution of the acute colitic response, sustained anhedonia in the saccharin preference test, immobility in the forced swim test, reduced burying behaviour in the marble burying test, and mild signs of anxiety in the elevated plus maze and light/dark box were observed. Central increases in iNOS expression persisted during the recovery phase and mapped to reactive microglia, particularly those found in the parenchyma surrounding circumventricular regions. Evidence of associated nitration was also found. Sustained increases in ventricular volume and reduced T2 magnetic resonance relaxometry time in cortical regions were observed during the recovery period. FosB/ΔFosB activation was evident in the dorsal raphe during recovery. Persistent central inflammation and cellular activation may underpin the emergence of symptoms of depression and anxiety in experimental colitis.

Propionic Acid Induces Gliosis and Neuro-inflammation through Modulation of PTEN/AKT Pathway in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by glia over-proliferation, neuro-inflammation, perturbed neural circuitry, and gastrointestinal symptoms. The role of gut dys-biosis in ASD is intriguing and should be elucidated. We investigated the effect of Propionic acid (PPA), a short-chain fatty acid (SCFA) and a product of dys-biotic ASD gut, on human neural stem cells (hNSCs) proliferation, differentiation and inflammation. hNSCs proliferated to 66 neuropsheres when exposed to PPA versus 45 in control. The neurosphere diameter also increased at day 10 post PPA treatment to (Mean: 193.47 um ± SEM: 6.673 um) versus (154.16 um ± 9.95 um) in control, p < 0.001. Pre-treatment with β-HB, SCFA receptor inhibitor, hindered neurosphere expansion (p < 0.001). While hNSCs spontaneously differentiated to (48.38% ± 6.08%) neurons (Tubulin-IIIβ positive) and (46.63% ± 2.5%) glia (GFAP positive), PPA treatment drastically shifted differentiation to 80% GFAP cells (p < 0.05). Following 2 mM PPA exposure, TNF-α transcription increased 4.98 fold and the cytokine increased 3.29 fold compared to control (P < 0.001). Likewise, GPR41 (PPA receptor) and pro-survival p-Akt protein were elevated (p < 0.001). PTEN (Akt inhibitor) level decreased to (0.42 ug/ul ± 0.04 ug/ul) at 2 mM PPA compared to (0.83 ug/ul ± 0.09 ug/ul) in control (p < 0.001). PPA at 2 mM decreased neurite outgrowth to (80.70 um ± 5.5 um) compared to (194.93 um ± 19.7 um) in control. Clearly, the data supports a significant role for PPA in modulating hNSC patterning leading to gliosis, disturbed neuro-circuitry, and inflammatory response as seen in ASD.

Strain differences in the susceptibility to the gut-brain axis and neurobehavioural alterations induced by maternal immune activation in mice

There is a growing realization that the severity of the core symptoms of autism spectrum disorders and schizophrenia is associated with gastrointestinal dysfunction. Nonetheless, the mechanisms underlying such comorbidities remain unknown. Several genetic and environmental factors have been linked to a higher susceptibility to neurodevelopmental abnormalities. The maternal immune activation (MIA) rodent model is a valuable tool for elucidating the basis of this interaction. We induced MIA with polyinosinic-polycytidylic acid (poly I:C) at gestational day 12.5 and assessed behavioural, physiological and molecular aspects relevant to the gut-brain axis in the offspring of an outbred (NIH Swiss) and an inbred (C57BL6/J) mouse strain. Our results showed that the specific MIA protocol employed induces social deficits in both strains. However, alterations in anxiety and depression-like behaviours were more pronounced in NIH Swiss mice. These strain-specific behavioural effects in the NIH Swiss mice were associated with marked changes in important components of gut-brain axis communication: the endocrine response to stress and gut permeability. In addition, MIA-induced changes in vasopressin receptor 1a mRNA expression in the hypothalamus were observed in NIH Swiss mice only. Taken together, these data suggest that genetic background is a critical factor in susceptibility to the gut-brain axis effects induced by MIA.

Polyphenols as food bioactive compounds in the context of Autism Spectrum Disorders: A critical mini-review

Dietary polyphenols are bioactive compounds with potential in preventing and treating several chronic disorders, mainly due to their ability to modulate key pro-inflammatory and pro-oxidant signalling pathways. Although some studies have expressed concern about their efficacy in vivo, accumulating evidence has suggested that these compounds may achieve large concentrations in the gastrointestinal tract, which may be important in the context of intestinal and of neurological disorders, via modulation of the "gut-brain axis". Autism Spectrum disorders (ASD) are a group of lifelong neurodevelopmental disorders in which many patients suffer from gastrointestinal impairments. Thus, in the scope of these disorders, a growing number of studies have been focused on the microbiota-gut-brain axis. In this mini-review, we present gathered data on gut-to-brain communication in the scope of ASD and we address the advantages of polyphenols in the treatment of these disorders, presenting the more recent preclinical and clinical data on this issue. According to most studies, dietary polyphenols can be a promising strategy for the alleviation of ASD symptoms.

Neurodevelopmental heterogeneity and computational approaches for understanding autism

In recent years, the emerging field of computational psychiatry has impelled the use of machine learning models as a means to further understand the pathogenesis of multiple clinical disorders. In this paper, we discuss how autism spectrum disorder (ASD) was and continues to be diagnosed in the context of its complex neurodevelopmental heterogeneity. We review machine learning approaches to streamline ASD's diagnostic methods, to discern similarities and differences from comorbid diagnoses, and to follow developmentally variable outcomes. Both supervised machine learning models for classification outcome and unsupervised approaches to identify new dimensions and subgroups are discussed. We provide an illustrative example of how computational analytic methods and a longitudinal design can improve our inferential ability to detect early dysfunctional behaviors that may or may not reach threshold levels for formal diagnoses. Specifically, an unsupervised machine learning approach of anomaly detection is used to illustrate how community samples may be utilized to investigate early autism risk, multidimensional features, and outcome variables. Because ASD symptoms and challenges are not static within individuals across development, computational approaches present a promising method to elucidate subgroups of etiological contributions to phenotype, alternative developmental courses, interactions with biomedical comorbidities, and to predict potential responses to therapeutic interventions.

Intestinal dysmotility in a zebrafish (Danio rerio) shank3a;shank3b mutant model of autism

Background and aims

Autism spectrum disorder (ASD) is currently estimated to affect more than 1% of the world population. For people with ASD, gastrointestinal (GI) distress is a commonly reported but a poorly understood co-occurring symptom. Here, we investigate the physiological basis for GI distress in ASD by studying gut function in a zebrafish model of Phelan-McDermid syndrome (PMS), a condition caused by mutations in the SHANK3 gene.

Methods

To generate a zebrafish model of PMS, we used CRISPR/Cas9 to introduce clinically related C-terminal frameshift mutations in shank3a and shank3b zebrafish paralogues (shank3abΔC). Because PMS is caused by SHANK3 haploinsufficiency, we assessed the digestive tract (DT) structure and function in zebrafish shank3abΔC^+/− heterozygotes. Human SHANK3 mRNA was then used to rescue DT phenotypes in larval zebrafish.

Results

Significantly slower rates of DT peristaltic contractions (p < 0.001) with correspondingly prolonged passage time (p < 0.004) occurred in shank3abΔC^+/− mutants. Rescue injections of mRNA encoding the longest human SHANK3 isoform into shank3abΔC^+/− mutants produced larvae with intestinal bulb emptying similar to wild type (WT), but still deficits in posterior intestinal motility. Serotonin-positive enteroendocrine cells (EECs) were significantly reduced in both shank3abΔC^+/− and shank3abΔC^−/− mutants (p < 0.05) while enteric neuron counts and overall structure of the DT epithelium, including goblet cell number, were unaffected in shank3abΔC^+/− larvae.

Conclusions

Our data and rescue experiments support mutations in SHANK3 as causal for GI transit and motility abnormalities. Reductions in serotonin-positive EECs and serotonin-filled ENS boutons suggest an endocrine/neural component to this dysmotility. This is the first study to date demonstrating DT dysmotility in a zebrafish single gene mutant model of ASD.

Electronic supplementary material

The online version of this article (10.1186/s13229-018-0250-4) contains supplementary material, which is available to authorized users.

Microbiome-microglia connections via the gut-brain axis

Microglia, the resident immune cells in the brain, are essential for modulating neurogenesis, influencing synaptic remodeling, and regulating neuroinflammation by surveying the brain microenvironment. Microglial dysfunction has been implicated in the onset and progression of several neurodevelopmental and neurodegenerative diseases; however, the multitude of factors and signals influencing microglial activity have not been fully elucidated. Microglia not only respond to local signals within the brain but also receive input from the periphery, including the gastrointestinal (GI) tract. Recent preclinical findings suggest that the gut microbiome plays a pivotal role in regulating microglial maturation and function, and altered microbial community composition has been reported in neurological disorders with known microglial involvement in humans. Collectively, these findings suggest that bidirectional crosstalk between the gut and the brain may influence disease pathogenesis. Herein, we discuss recent studies showing a role for the gut microbiome in modulating microglial development and function in homeostatic and disease conditions and highlight possible future research to develop novel microbial treatments for disorders of the brain.

Making Sense of … the Microbiome in Psychiatry

Microorganisms can be found almost anywhere, including in and on the human body. The collection of microorganisms associated with a certain location is called a microbiota, with its collective genetic material referred to as the microbiome. The largest population of microorganisms on the human body resides in the gastrointestinal tract; thus, it is not surprising that the most investigated human microbiome is the human gut microbiome. On average, the gut hosts microbes from more than 60 genera and contains more cells than the human body. The human gut microbiome has been shown to influence many aspects of host health, including more recently the brain.Several modes of interaction between the gut and the brain have been discovered, including via the synthesis of metabolites and neurotransmitters, activation of the vagus nerve, and activation of the immune system. A growing body of work is implicating the microbiome in a variety of psychological processes and neuropsychiatric disorders. These include mood and anxiety disorders, neurodevelopmental disorders such as autism spectrum disorder and schizophrenia, and even neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Moreover, it is probable that most psychotropic medications have an impact on the microbiome.Here, an overview will be provided for the bidirectional role of the microbiome in brain health, age-associated cognitive decline, and neurological and psychiatric disorders. Furthermore, a primer on the common microbiological and bioinformatics techniques used to interrogate the microbiome will be provided. This review is meant to equip the reader with a primer to this exciting research area that is permeating all areas of biological psychiatry research.

Serotonin and serotonin transporter levels in autistic children

OBJECTIVES

To assess the possible correlation between serotonin and serotonin transporter (SERT) with the autism severity and investigate the association between these parameters in autistic children to assess their possible role for diagnosis of autism severity.

METHODS

A comparative cross-sectional study was carried out in the Chemistry and Biochemistry Department, College of Medicine, Al-Nahrain University, Baghdad, Iraq while the samples were taken from 60 male autistic children recruited to the Department of Pediatrics at Al-Sader Hospital, Baghdad, Iraq between November 2014 amd April 2015. Levels of serotonin and serotonin transporters (SERT) were determined in 60 male autistic Iraqi patients classified into mild, moderate and severe (20 for each). These levels were compared with those of 26 healthy control children. Results: Levels of serotonin and SERT were significantly increased in autistic children than that of gender and age-matched controls. Serotonin levels were 80.63± 21.83 ng/ml in mild, 100.39±23.07 ng/ml moderate, and 188.7±31.72 ng/ml severe autistic patients. Serotonin transporter levels were 10.13±4.51 ng/ml in mild, 13.15±4.71 ng/ml moderate, and 16.32±6.7 ng/ml in  severe autistic patients. The increase of both serotonin and SERT levels were associated with severity of autism. Receiver operating characteristic (ROC) analysis  can be used for diagnostic and prognostic purposes.

CONCLUSIONS

High serotonin and SERT levels may indicate that these biomarkers have a role in the autism pathogenesis and support the possibility of using serotonin and SERT to diagnose autism severity.

Gut-brain actions underlying comorbid anxiety and depression associated with inflammatory bowel disease

IntroductionInflammatory bowel disease (IBD) is a chronic relapsing and remitting disorder characterised by inflammation of the gastrointestinal tract. There is a growing consensus that IBD is associated with anxiety- and depression-related symptoms. Psychological symptoms appear to be more prevalent during active disease states with no difference in prevalence between Crohn's disease and ulcerative colitis. Behavioural disturbances including anxiety- and depression-like symptoms have also been observed in animal models of IBD.

RESULTS

The likely mechanisms underlying the association are discussed with particular reference to communication between the gut and brain. The close bidirectional relationship known as the gut-brain axis includes neural, hormonal and immune communication links. Evidence is provided for a number of interacting factors including activation of the inflammatory response system in the brain, the hypothalamic-pituitary-adrenal axis, and brain areas implicated in altered behaviours, changes in blood brain barrier integrity, and an emerging role for gut microbiota and response to probiotics in IBD.DiscussionThe impact of psychological stress in models of IBD remains somewhat conflicted, however, it is weighted in favour of stress or early stressful life events as risk factors in the development of IBD, stress-induced exacerbation of inflammation and relapse.

CONCLUSION

It is recommended that patients with IBD be screened for psychological disturbance and treated accordingly as intervention can improve quality of life and may reduce relapse rates.

Early Disruption of the Microbiome Leading to Decreased Antioxidant Capacity and Epigenetic Changes: Implications for the Rise in Autism

Currently, 1 out of every 59 children in the United States is diagnosed with autism. While initial research to find the possible causes for autism were mostly focused on the genome, more recent studies indicate a significant role for epigenetic regulation of gene expression and the microbiome. In this review article, we examine the connections between early disruption of the developing microbiome and gastrointestinal tract function, with particular regard to susceptibility to autism. The biological mechanisms that accompany individuals with autism are reviewed in this manuscript including immune system dysregulation, inflammation, oxidative stress, metabolic and methylation abnormalities as well as gastrointestinal distress. We propose that these autism-associated biological mechanisms may be caused and/or sustained by dysbiosis, an alteration to the composition of resident commensal communities relative to the community found in healthy individuals and its redox and epigenetic consequences, changes that in part can be due to early use and over-use of antibiotics across generations. Further studies are warranted to clarify the contribution of oxidative stress and gut microbiome in the pathophysiology of autism. A better understanding of the microbiome and gastrointestinal tract in relation to autism will provide promising new opportunities to develop novel treatment modalities.

A prebiotic intervention study in children with autism spectrum disorders (ASDs)

BACKGROUND

Different dietary approaches, such as gluten and casein free diets, or the use of probiotics and prebiotics have been suggested in autistic spectrum disorders in order to reduce gastrointestinal (GI) disturbances. GI symptoms are of particular interest in this population due to prevalence and correlation with the severity of behavioural traits. Nowadays, there is lack of strong evidence about the effect of dietary interventions on these problems, particularly prebiotics. Therefore, we assessed the impact of exclusion diets and a 6-week Bimuno® galactooligosaccharide (B-GOS®) prebiotic intervention in 30 autistic children.

RESULTS

The results showed that children on exclusion diets reported significantly lower scores of abdominal pain and bowel movement, as well as lower abundance of Bifidobacterium spp. and Veillonellaceae family, but higher presence of Faecalibacterium prausnitzii and Bacteroides spp. In addition, significant correlations were found between bacterial populations and faecal amino acids in this group, compared to children following an unrestricted diet. Following B-GOS® intervention, we observed improvements in anti-social behaviour, significant increase of Lachnospiraceae family, and significant changes in faecal and urine metabolites.

CONCLUSIONS

To our knowledge, this is the first study where the effect of exclusion diets and prebiotics has been evaluated in autism, showing potential beneficial effects. A combined dietary approach resulted in significant changes in gut microbiota composition and metabolism suggesting that multiple interventions might be more relevant for the improvement of these aspects as well as psychological traits.

TRIAL REGISTRATION

NCT02720900 ; registered in November 2015.

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.

Toxin profile of fecal Clostridium perfringens strains isolated from children with autism spectrum disorders

Infectious factors are taken into consideration in pathophysiology of autism spectrum disorders (ASD). ASD patients often suffer from gastrointestinal disorders. The intestinal microbiota of autistic patients significantly differs from that in healthy individuals. The aim of the study was to compare the profile of toxins produced by C. perfringens strains isolated from feces of children with ASD, with healthy individuals and obese subjects. This study included 111 strains of C. perfringens: 49 isolates from 29 children with ASD, 30 - from 17 healthy individuals and 32 - from 24 young obese subjects. Alpha, beta, beta2, epsilon, iota and enterotoxin genes were detected using appropriate PCRs. The alpha toxin gene (cpa) was present in all 111 examined strains (100%). The beta2 gene (cpb2) was detected in 45/49 strains (91.8%) isolated from children with ASD, 17/30 (56.7%) isolates from healthy subjects, and 12 of 32 (37.5%) isolates from obese subjects. C. perfringens strains with cpb2 gene were detected in 27/29 ASD patients (93.1%), 10/17 healthy subjects (58.8%) and 11/24 (45.8%) obese subjects. Beta2 toxin encoding cpb2 gene was significantly more common in strains isolated from ASD patients, with no significant difference between control subjects regardless of diet. Further research to explain observed phenomena and pathomechanism of beta2 toxin is required.

Effects of gut-derived endotoxin on anxiety-like and repetitive behaviors in male and female mice

BACKGROUND

Gut dysbiosis is observed in several neuropsychiatric disorders exhibiting increases in anxiety behavior, and recent work suggests links between gut inflammation and such disorders. One source of this inflammation may be lipopolysaccharide (LPS), a toxic component of gram-negative bacteria. Here, we (1) determine whether oral gavage of LPS, as a model of gut-derived endotoxemia, affects anxiety-like and/or repetitive behaviors; (2) test whether these changes depend on TLR4 signaling; and (3) test the extent to which gut-derived endotoxin and TLR4 antagonism affects males and females differently.

METHODS

In experiment 1, male wild-type (WT) and Tlr4-/- mice were tested for locomotor, anxiety-like, and repetitive behaviors in an automated open field test apparatus, 2 h after oral gavage of LPS or saline. In experiment 2, male and female WT mice received an oral gavage of LPS and an injection of one or two TLR4 antagonists that target different TLR4 signaling pathways ((+)-naloxone and LPS derived from R. sphaeroides (LPS-RS)). Univariate and multivariate analyses were used to identify effects of treatment, sex, and genotype and their interaction.

RESULTS

In experiment 1, oral gavage of LPS increased anxiety-like behavior in male WT mice but not in Tlr4-/- mice. In experiment 2, oral gavage of LPS increased anxiety-like and decreased repetitive behaviors in WT mice of both sexes. Neither antagonist directly blocked the effects of orally administered LPS. However, treatment with (+)-naloxone, which blocks the TRIF pathway of TLR4, had opposing behavioral effects in males and females (independent of LPS treatment). We also identified sex differences in the expression of interleukin-6, a pro-inflammatory cytokine, in the gut both in basal conditions and in response to LPS.

CONCLUSION

In spite of the ubiquitous nature of LPS in the gut lumen, this is the first study to demonstrate that intestinally derived LPS can initiate behavioral aspects of the sickness response. While an increased enteric load of LPS increases anxiety-like behavior in both sexes, it likely does so via sex-specific mechanisms. Similarly, TLR4 signaling may promote baseline expression of repetitive behavior differently in males and females. This study lays the groundwork for future interrogations into connections between gut-derived endotoxin and behavioral pathology in males and females.

The prevalence of gluten free diet use among preschool children with autism spectrum disorder

Our objective was to estimate prevalence of current or ever use of a gluten free diet (GFD) in children aged 30-68 months with autism spectrum disorder (ASD) and population controls (POP); and to identify characteristics associated with ever having used GFD among children with ASD. We used data from the Study to Explore Early Development (SEED), a multi-site, case-control study of children with ASD. Caregivers reported GFD use by their children through structured questionnaires about diet patterns, gastrointestinal (GI) issues, and ASD-specific treatments. Prevalence was estimated and compared using log-Poisson regression, adjusting for confounders. In children with ASD, we examined whether child or mother's GI conditions or child's phenotypic traits were associated with ever trying a GFD. In SEED, 71 children with ASD (11.1% prevalence after adjustment) were on a GFD at time of the study and 130 (20.4%) had ever used a GFD, a greater percentage than in POP children (N = 11, 0.9% current use). Of current users with ASD, 50.7% had a dietary intervention that was prescribed by a medical professional. Among children with ASD, child GI conditions and developmental regression were positively and independently associated with having ever used a GFD. Current use and ever use of a GFD were prevalent in children with ASD identified in SEED. GFD usage was associated with GI issues and child phenotype. Clinicians may consider advising parents on how best to use these diets in the context of the child's GI presentation and current scientific knowledge about effectiveness in relation to ASD symptoms. Autism Res 2018, 11: 185-193. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

Gluten free diets (GFDs) are commonly used as an alternative therapy for autism spectrum disorder (ASD); however, the effectiveness is still uncertain which makes it important to know who tries this type of diet. We found that one in five preschool aged children with ASD had ever used a GFD. Children with gastrointestinal conditions and developmental regression were more likely to have tried a GFD.

Rapid Assessment of Microbiota Changes in Individuals with Autism Spectrum Disorder Using Bacteria-derived Membrane Vesicles in Urine

Individuals with autism spectrum disorder (ASD) have altered gut microbiota, which appears to regulate ASD symptoms via gut microbiota-brain interactions. Rapid assessment of gut microbiota profiles in ASD individuals in varying physiological contexts is important to understanding the role of the microbiota in regulating ASD symptoms. Microbiomes secrete extracellular membrane vesicles (EVs) to communicate with host cells and secreted EVs are widely distributed throughout the body including the blood and urine. In the present study, we investigated whether bacteria-derived EVs in urine are useful for the metagenome analysis of microbiota in ASD individuals. To address this, bacterial DNA was isolated from bacteria-derived EVs in the urine of ASD individuals. Subsequent metagenome analysis indicated markedly altered microbiota profiles at the levels of the phylum, class, order, family, and genus in ASD individuals relative to control subjects. Microbiota identified from urine EVs included gut microbiota reported in previous studies and their up- and down-regulation in ASD individuals were partially consistent with microbiota profiles previously assessed from ASD fecal samples. However, overall microbiota profiles identified in the present study represented a distinctive microbiota landscape for ASD. Particularly, the occupancy of g_Pseudomonas, g_Sphingomonas, g_Agrobacterium, g_Achromobacter, and g_Roseateles decreased in ASD, whereas g_Streptococcus, g_Akkermansia, g_Rhodococcus, and g_Halomonas increased. These results demonstrate distinctively altered gut microbiota profiles in ASD, and validate the utilization of urine EVs for the rapid assessment of microbiota in ASD.

Using Animal Models to Study the Role of the Gut-Brain Axis in Autism

PURPOSE OF REVIEW

Individuals with autism spectrum disorders (ASD) commonly also suffer from gastrointestinal (GI) dysfunction; however, few animal model studies have systematically examined both ASD and GI dysfunction. In this review, we highlight studies investigating GI dysfunction and alterations in gut microbiota in animal models of ASD with the aim of determining if routinely used microbiology and enteric neurophysiology assays could expand our understanding of the link between the two.

RECENT FINDINGS

Gut-brain axis research is expanding, and several ASD models demonstrate GI dysfunction. The integration of well-established assays for detecting GI dysfunction into standard behavioural testing batteries is needed.

SUMMARY

Advances in understanding the role of the gut-brain axis in ASD are emerging; however, we outline standard assays for investigating gut-brain axis function in rodents to strengthen future phenotyping studies. Integrating these findings to the field of animal behaviour is one of the next major challenges in autism research.

Toll-like receptor 4 signaling is associated with upregulated NADPH oxidase expression in peripheral T cells of children with autism

Autism spectrum disorders (ASD) affect millions of children worldwide, and are characterized by impairment in social interaction and communication, and specific repetitive behavioral patterns. Growing evidence highlights a role of toll-like receptors (TLRs) in the pathogenesis of ASD. Specifically, TLR-4 activation has been shown to be associated with increased pro-inflammatory cytokines as well as autistic symptoms in offspring. NADPH oxidase (NOX-2) derived reactive oxygen species (ROS) have also been shown to play pathogenic role under inflammatory conditions. However, the role of TLR-4 in the regulation of NOX-2 derived ROS has not been explored in ASD, particularly in T cells. Therefore, this study explored TLR-4 and NOX-2 related signaling in peripheral T cells of ASD patients (n=35) and age-matched typically developing children (n=30). In this study, we find that ASD individuals have increased TLR-4 expression on T cells which is associated with increased NOX-2 expression and ROS generation as compared to typically developing children. Moreover, activation of TLR-4 on T cells by lipopolysaccharide (LPS) in vitro leads to enhanced generation of NOX-2 derived ROS via nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) pathway. These data support a link between T cell TLR-4 activation and NOX-2/ROS upregulation in ASD patients. Our study has implications in the context of neuroinflammation observed in ASD patients as ROS may lead to amplification and perpetuation of inflammation both in the periphery and central nervous system. Our data also suggest that therapeutic targeting of TLR-4 signaling may lead to reduction in inflammation of ASD patients.

New evidences on the altered gut microbiota in autism spectrum disorders

BACKGROUND

Autism spectrum disorders (ASDs) are neurodevelopmental conditions characterized by social and behavioural impairments. In addition to neurological symptoms, ASD subjects frequently suffer from gastrointestinal abnormalities, thus implying a role of the gut microbiota in ASD gastrointestinal pathophysiology.

RESULTS

Here, we characterized the bacterial and fungal gut microbiota in a cohort of autistic individuals demonstrating the presence of an altered microbial community structure. A fraction of 90% of the autistic subjects were classified as severe ASDs. We found a significant increase in the Firmicutes/Bacteroidetes ratio in autistic subjects due to a reduction of the Bacteroidetes relative abundance. At the genus level, we observed a decrease in the relative abundance of Alistipes, Bilophila, Dialister, Parabacteroides, and Veillonella in the ASD cohort, while Collinsella, Corynebacterium, Dorea, and Lactobacillus were significantly increased. Constipation has been then associated with different bacterial patterns in autistic and neurotypical subjects, with constipated autistic individuals characterized by high levels of bacterial taxa belonging to Escherichia/Shigella and Clostridium cluster XVIII. We also observed that the relative abundance of the fungal genus Candida was more than double in the autistic than neurotypical subjects, yet due to a larger dispersion of values, this difference was only partially significant.

CONCLUSIONS

The finding that, besides the bacterial gut microbiota, also the gut mycobiota contributes to the alteration of the intestinal microbial community structure in ASDs opens the possibility for new potential intervention strategies aimed at the relief of gastrointestinal symptoms in ASDs.

Anaerobic Probiotics: The Key Microbes for Human Health

Human gastrointestinal microbiota (HGIM) incorporate a large number of microbes from different species. Anaerobic bacteria are the dominant organisms in this microbial consortium and play a crucial role in human health. In addition to their functional role as the main source of many essential metabolites for human health, they are considered as biotherapeutic agents in the regulation of different human metabolites. They are also important in the prevention and in the treatment of different physical and mental diseases. Bifidobacteria are the dominant anaerobic bacteria in HGIM and are widely used in the development of probiotic products for infants, children and adults. To develop bifidobacteria-based bioproducts, therefore, it is necessary to develop a large-scale biomass production platform based on a good understanding of the ideal medium and bioprocessing parameters for their growth and viability. In addition, high cell viability should be maintained during downstream processing and storage of probiotic cell powder or the final formulated product. In this work we review the latest information about the biology, therapeutic activities, cultivation and industrial production of bifidobacteria.

Gut Microbiota: A Potential Regulator of Neurodevelopment

During childhood, our brain is exposed to a variety of environmental inputs that can sculpt synaptic connections and neuronal circuits, with subsequent influence on behavior and learning processes. Critical periods of neurodevelopment are windows of opportunity in which the neuronal circuits are extremely plastic and can be easily subjected to remodeling in response to experience. However, the brain is also more susceptible to aberrant stimuli that might lead to altered developmental trajectories. Intriguingly, postnatal brain development is paralleled by the maturation of the gut microbiota: the ecosystem of symbionts populating our gastro-intestinal tract. Recent discoveries have started to unveil an unexpected link between the gut microbiome and neurophysiological processes. Indeed, the commensal bacteria seem to be able to influence host behavioral outcome and neurochemistry through mechanisms which remain poorly understood. Remarkably, the efficacy of the gut flora action appears to be dependent on the timing during postnatal life at which the host gut microbes’ signals reaches the brain, suggesting the fascinating possibility of critical periods for this microbiota-driven shaping of host neuronal functions and behavior. Therefore, to understand the importance of the intestinal ecosystem’s impact on neuronal circuits functions and plasticity during development and the discovery of the involved molecular mechanisms, will pave the way to identify new and, hopefully, powerful microbiota-based therapeutic interventions for the treatment of neurodevelopmental and psychiatric diseases.