Modulation of Gut Microbiome and Autism Symptoms of ASD Children Supplemented with Biological Response Modifier: A Randomized, Double-Blinded, Placebo-Controlled Pilot Study.

The etiology and mechanisms of autism and autism spectrum disorder (ASD) are not yet fully understood. There is currently no treatment for ASD for providing significant improvement in core symptoms. Recent studies suggest, however, that ASD is associated with gut dysbiosis, indicating that modulation of gut microbiota in children with ASD may thus reduce the manifestation of ASD symptoms. The aim of this pilot study (prospective randomized, double-blinded, placebo-controlled) was to evaluate efficacy of the biological response modifier Juvenil in modulating the microbiome of children with ASD and, in particular, whether Juvenil is able to alleviate the symptoms of ASD. In total, 20 children with ASD and 12 neurotypical children were included in our study. Supplementation of ASD children lasted for three months. To confirm Juvenil's impact on the gut microbiome, stool samples were collected from all children and the microbiome's composition was analyzed. This pilot study demonstrated that the gut microbiome of ASD children differed significantly from that of healthy controls and was converted by Juvenil supplementation toward a more neurotypical microbiome that positively modulated children's autism symptoms.

Human-derived fecal microbiota transplantation alleviates social deficits of the BTBR mouse model of autism through a potential mechanism involving vitamin B6 metabolism.

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by social communication deficiencies and stereotypic behaviors influenced by hereditary and/or environmental risk factors. There are currently no approved medications for treating the core symptoms of ASD. Human fecal microbiota transplantation (FMT) has emerged as a potential intervention to improve autistic symptoms, but the underlying mechanisms are not fully understood. In this study, we evaluated the effects of human-derived FMT on behavioral and multi-omics profiles of the BTBR mice, an established model for ASD. FMT effectively alleviated the social deficits in the BTBR mice and normalized their distinct plasma metabolic profile, notably reducing the elevated long-chain acylcarnitines. Integrative analysis linked these phenotypic changes to specific Bacteroides species and vitamin B6 metabolism. Indeed, vitamin B6 supplementation improved the social behaviors in BTBR mice. Collectively, these findings shed new light on the interplay between FMT and vitamin B6 metabolism and revealed a potential mechanism underlying the therapeutic role of FMT in ASD.IMPORTANCEAccumulating evidence supports the beneficial effects of human fecal microbiota transplantation (FMT) on symptoms associated with autism spectrum disorder (ASD). However, the precise mechanism by which FMT induces a shift in the microbiota and leads to symptom improvement remains incompletely understood. This study integrated data from colon-content metagenomics, colon-content metabolomics, and plasma metabolomics to investigate the effects of FMT treatment on the BTBR mouse model for ASD. The analysis linked the amelioration of social deficits following FMT treatment to the restoration of mitochondrial function and the modulation of vitamin B6 metabolism. Bacterial species and compounds with beneficial roles in vitamin B6 metabolism and mitochondrial function may further contribute to improving FMT products and designing novel therapies for ASD treatment.

Induction of autism-related behavior in male mice by early-life vitamin D deficiency: association with disruption of the gut microbial composition and homeostasis.

Vitamin D deficiency (VDD) during early life emerges as a potential risk factor for autism spectrum disorder (ASD). Individuals with autism commonly exhibit lower vitamin D (VD) levels compared to the general population, and VD deficiency is prevalent during pregnancy and lactation. Moreover, gastrointestinal comorbidity, prevalent in ASD patients, correlates closely with disruptions in the gut microbiota and altered intestinal permeability. Therefore, it is fascinating and significant to explore the effects of maternal VD deficiency during pregnancy and lactation on the maturation of the gut microbiota of the offspring and its relevance to autism spectrum disorders. In this study, we established maternal pregnancy and lactation VD-deficient mouse models, employed shotgun macrogenomic sequencing to unveil alterations in the gut microbiome of offspring mice, and observed autism-related behaviours. Furthermore, fecal microbial transplantation (FMT) reversed repetitive and anxious behaviours and alleviated social deficits in offspring mice by modulating the gut microbiota and increasing short-chain fatty acid levels in the cecum, along with influencing the concentrations of claudin-1 and occludin in the colon. Our findings confirm that VDD during pregnancy and lactation is a risk factor for autism in the offspring, with disturbances in the structure and function of the offspring's gut microbiota contributing at least part of the effect. The study emphasises the importance of nutrition and gut health early in life. Simultaneously, this study further demonstrates the effect of VDD on ASD and provides potential ideas for early prevention and intervention of ASD.

Prenatal caffeine exposure induces autism-like behaviors in offspring under a high-fat diet via the gut microbiota-IL-17A-brain axis.

Prenatal caffeine exposure (PCE) is a significant contributor to intrauterine growth retardation (IUGR) in offspring, which has been linked to an increased susceptibility to autism spectrum disorder (ASD) later in life. Additionally, a high-fat diet (HFD) has been shown to exacerbate ASD-like behaviors, but the underlying mechanisms remain unclear. In this study, we first noted in the rat model of IUGR induced by PCE that male PCE offspring exhibited typical ASD-like behaviors post-birth, in contrast to their female counterparts. The female PCE offspring demonstrated only reduced abilities in free exploration and spatial memory. Importantly, both male and female PCE offspring displayed ASD-like behaviors when exposed to HFD. We further observed that PCE + HFD offspring exhibited damaged intestinal mucus barriers and disturbed gut microbiota, resulting in an increased abundance of Escherichia coli (E. coli). The induced differentiation of colonic Th17 cells by E. coli led to an increased secretion of IL-17A, which entered the hippocampus through peripheral circulation and caused synaptic damage in hippocampal neurons, ultimately resulting in ASD development. Our strain transplantation experiment suggested that E. coli-mediated increase of IL-17A may be the core mechanism of ASD with a fetal origin. In conclusion, PCE and HFD are potential risk factors for ASD, and E. coli-mediated IL-17A may play a crucial role in fetal-originated ASD through the gut-brain axis.

Structure and synthesis of a vaccine and diagnostic target for Enterocloster bolteae, an autism-associated gut pathogen - Part II.

Enterocloster bolteae (formerly known as Clostridium bolteae) is a gastro-intestinal pathogenic bacterium often detected in the fecal microbiome of children in the autism spectrum. E. bolteae excretes metabolites that are thought to act as neurotoxins. This study is an update of our first E. bolteae investigation that discovered an immunogenic polysaccharide. Through a combination of chemical derivatizations/degradations, spectrometry and spectroscopy techniques, a polysaccharide composed of disaccharide repeating blocks comprised of 3-linked ß-d-ribofuranose and 4-linked α-l-rhamnopyranose, [→3)-ß-D-Ribf-(1 â†’ 4)-α-L-Rhap-(1→]n, was identified. To confirm the structure, and to provide material for subsequent investigations, the chemical synthesis of a corresponding linker-equipped tetrasaccharide, ß-D-Ribf-(1 â†’ 4)-α-L-Rhap-(1 â†’ 3)-ß-D-Ribf-(1 â†’ 4)-α-L-Rhap-(1→O(CH2)8N3, is also described. Research tools based on this immunogenic glycan structure can form the foundation for serotype classification, diagnostic/vaccine targets and clinical studies into the hypothesized role of E. bolteae in the onset/augmentation of autism related conditions in children.

Might the fungus candida albicans a risk factor for autism? A meta-analysis study.

Objective: Due to the high increase in rate of autism, it has gained great importance to determine the etiology of autism spectrum disorder. The purpose of our study was to assess the role of Candida albicans as a risk factor to cause autism behavior. Methods: We searched Scopus, PubMed, Web of Science and PsycINFO for articles up to December, 2021. The studies involving children diagnosed with autism spectrum disorder were included. Children' outcomes were selected as Candida albicans (positive) and Candida albicans (negative). Odds ratios were reported using fixed-effect and random-effect meta-analysis. The heterogeneity was assessed by the Chi-square test and Higgins' I2 test. The publication bias was examined via funnel plot and Hegger's test. Results: Our meta-analysis was conducted based on 254 diagnosed with Autism Spectrum Disease cases and 161 healthy cases from 4 studies. Compared to the healthy cases, the odds of presence of Candida albicans (OR=7.21; 95% CI: 3.75-13.85; p<0.001) were higher in those diagnosed with autism spectrum disorder. Conclusion: This study as a whole showed that children diagnosed with autism spectrum disorder have higher frequency of the presence of the fungus Candida albicans. Therefore, Candida albicans may be an etiological factor for the autistic behavior in children.

Autism-related dietary preferences mediate autism-gut microbiome associations.

There is increasing interest in the potential contribution of the gut microbiome to autism spectrum disorder (ASD). However, previous studies have been underpowered and have not been designed to address potential confounding factors in a comprehensive way. We performed a large autism stool metagenomics study (n = 247) based on participants from the Australian Autism Biobank and the Queensland Twin Adolescent Brain project. We found negligible direct associations between ASD diagnosis and the gut microbiome. Instead, our data support a model whereby ASD-related restricted interests are associated with less-diverse diet, and in turn reduced microbial taxonomic diversity and looser stool consistency. In contrast to ASD diagnosis, our dataset was well powered to detect microbiome associations with traits such as age, dietary intake, and stool consistency. Overall, microbiome differences in ASD may reflect dietary preferences that relate to diagnostic features, and we caution against claims that the microbiome has a driving role in ASD.

Studying Autism Using Untargeted Metabolomics in Newborn Screening Samples.

Main risk factors of autism spectrum disorder (ASD) include both genetic and non-genetic factors, especially prenatal and perinatal events. Newborn screening dried blood spot (DBS) samples have great potential for the study of early biochemical markers of disease. To study DBS strengths and limitations in the context of ASD research, we analyzed the metabolomic profiles of newborns later diagnosed with ASD. We performed LC-MS/MS-based untargeted metabolomics on DBS from 37 case-control pairs randomly selected from the iPSYCH sample. After preprocessing using MZmine 2.41, metabolites were putatively annotated using mzCloud, GNPS feature-based molecular networking, and MolNetEnhancer. A total of 4360 mass spectral features were detected, of which 150 (113 unique) could be putatively annotated at a high confidence level. Chemical structure information at a broad level could be retrieved for 1009 metabolites, covering 31 chemical classes. Although no clear distinction between cases and controls was revealed, our method covered many metabolites previously associated with ASD, suggesting that biochemical markers of ASD are present at birth and may be monitored during newborn screening. Additionally, we observed that gestational age, age at sampling, and month of birth influence the metabolomic profiles of newborn DBS, which informs us on the important confounders to address in future studies.

The effect of fecal microbiota transplantation on autistic-like behaviors in Fmr1 KO mice.

The importance of alterations in bidirectional communication between gut and brain has become obvious in neuropsychiatric disorders. Gastrointestinal (GI) disturbances are very common in autism spectrum disorders (ASD), and the GI microbiota profiles in children with ASD are significantly different from those in the general population. Fragile X syndrome (FXS) is an inheritable developmental disability in humans, and patients with FXS exhibit autistic behaviors such as mental retardation and impaired social communication or interaction. We hypothesized that an increase in specific gut microbiota by fecal microbiota transplantation (FMT) would mitigate autistic-like behaviors. To test this hypothesis, we measured the effects of FMT from normal mice to Fmr1 KO mice on autistic-like behaviors using several behavioral tests. Because the amounts of A. muciniphila in Fmr1 KO mice was very low, we assessed A. muciniphila population, tested the expression of MUC2, and analyzed goblet cells in the gut after the FMT. We found that FMT ameliorated autistic-like behaviors, especially memory deficits and social withdrawal, and we observed that the levels of A. muciniphila were normalized to wild-type levels. In addition, FMT attenuated the increased levels of TNFα and Iba1 in the brains of Fmr1 KO mice. These results suggest that FMT could be a useful tool for the treatments of cognitive deficits and social withdrawal symptoms observed in FXS or ASD because it increases the population of A. muciniphila and decreases TNFα and Iba1 levels.

The gut microbiota regulates autism-like behavior by mediating vitamin B6 homeostasis in EphB6-deficient mice.

BACKGROUND: Autism spectrum disorder (ASD) is a developmental disorder, and the effective pharmacological treatments for the core autistic symptoms are currently limited. Increasing evidence, particularly that from clinical studies on ASD patients, suggests a functional link between the gut microbiota and the development of ASD. However, the mechanisms linking the gut microbiota with brain dysfunctions (gut-brain axis) in ASD have not yet been full elucidated. Due to its genetic mutations and downregulated expression in patients with ASD, EPHB6, which also plays important roles in gut homeostasis, is generally considered a candidate gene for ASD. Nonetheless, the role and mechanism of EPHB6 in regulating the gut microbiota and the development of ASD are unclear. RESULTS: Here, we found that the deletion of EphB6 induced autism-like behavior and disturbed the gut microbiota in mice. More importantly, transplantation of the fecal microbiota from EphB6-deficient mice resulted in autism-like behavior in antibiotic-treated C57BL/6J mice, and transplantation of the fecal microbiota from wild-type mice ameliorated the autism-like behavior in EphB6-deficient mice. At the metabolic level, the disturbed gut microbiota in EphB6-deficient mice led to vitamin B6 and dopamine defects. At the cellular level, the excitation/inhibition (E/I) balance in the medial prefrontal cortex was regulated by gut microbiota-mediated vitamin B6 in EphB6-deficient mice. CONCLUSIONS: Our study uncovers a key role for the gut microbiota in the regulation of autism-like social behavior by vitamin B6, dopamine, and the E/I balance in EphB6-deficient mice, and these findings suggest new strategies for understanding and treating ASD. Video abstract.

Chemical Synthesis Elucidates the Key Antigenic Epitope of the Autism-Related Bacterium Clostridium bolteae Capsular Octadecasaccharide.

The gut pathogen Clostridium bolteae has been associated with the onset of autism spectrum disorder (ASD). To create vaccines against C. bolteae, it is important to identify exact protective epitopes of the immunologically active capsular polysaccharide (CPS). Here, a series of C. bolteae CPS glycans, up to an octadecasaccharide, was prepared. Key to achieving the total syntheses is a [2+2] coupling strategy based on a ß-d-Rhap-(1→3)-α-d-Manp repeating unit that in turn was accessed by a stereoselective ß-d-rhamnosylation. The 4,6-O-benzylidene-induced conformational locking is a powerful strategy for forming a ß-d-mannose-type glycoside. An indirect strategy based on C2 epimerization of ß-d-quinovoside was efficiently achieved by Swern oxidation and borohydride reduction. Sequential glycosylation, and regioselective and global deprotection produced the disaccharide and tetrasaccharide, up to the octadecasaccharide. Glycan microarray analysis of sera from rabbits immunized with inactivated C. bolteae bacteria revealed a humoral immune response to the di- and tetrasaccharide, but none of the longer sequences. The tetrasaccharide may be a key motif for designing glycoconjugate vaccines against C. bolteae.

Undigested Food and Gut Microbiota May Cooperate in the Pathogenesis of Neuroinflammatory Diseases: A Matter of Barriers and a Proposal on the Origin of Organ Specificity.

As food is an active subject and may have anti-inflammatory or pro-inflammatory effects, dietary habits may modulate the low-grade neuroinflammation associated with chronic neurodegenerative diseases. Food is living matter different from us, but made of our own nature. Therefore, it is at the same time foreign to us (non-self), if not yet digested, and like us (self), after its complete digestion. To avoid the efflux of undigested food from the lumen, the intestinal barrier must remain intact. What and how much we eat shape the composition of gut microbiota. Gut dysbiosis, as a consequence of Western diets, leads to intestinal inflammation and a leaky intestinal barrier. The efflux of undigested food, microbes, endotoxins, as well as immune-competent cells and molecules, causes chronic systemic inflammation. Opening of the blood-brain barrier may trigger microglia and astrocytes and set up neuroinflammation. We suggest that what determines the organ specificity of the autoimmune-inflammatory process may depend on food antigens resembling proteins of the organ being attacked. This applies to the brain and neuroinflammatory diseases, as to other organs and other diseases, including cancer. Understanding the cooperation between microbiota and undigested food in inflammatory diseases may clarify organ specificity, allow the setting up of adequate experimental models of disease and develop targeted dietary interventions.

Carbohydrate Scaffolds for the Study of the Autism-associated Bacterium, Clostridium bolteae.

A large number of children in the autism spectrum disorder suffer from gastrointestinal (GI) conditions, such as constipation and diarrhea. Clostridium bolteae is a part of a set of pathogens being regularly detected in the stool samples of hosts affected by GI and autism symptoms. Accompanying studies have pointed out the possibility that such microbes affect behaviour through the production of neurotoxic metabolites in a so-called, gut-brain connection. As an extension of our Clostridium difficile polysaccharide (PS)-based vaccine research, we engaged in the discovery of C. bolteae surface carbohydrates. So far, studies revealed that C. bolteae produces a specific immunogenic PS capsule comprised of disaccharide repeating blocks of mannose (Manp) and rhamnose (Rhap) units: α-D-Manp-(1→[-4)-ß-D-Rhap- (1→3)-α-D-Manp-(1→]n. For vaccinology and further immunogenic experiments, a method to produce C. bolteae PS conjugates has been developed, along with the chemical syntheses of the PS non-reducing end linkage, with D-Rha or L-Rha, α-D-Manp-(1→4)-α-D-Rhap- (1→O(CH2)5NH2 and α-D-Manp-(1→4)-α-L-Rhap-(1→O(CH2)5NH2, equipped with an aminopentyl linker at the reducing end for conjugation purposes. The discovery of C. bolteae PS immunogen opens the door to the creation of non-evasive diagnostic tools to evaluate the frequency and role of this microbe in autistic subjects and to a vaccine to reduce colonization levels in the GI tract, thus impeding the concentration of neurotoxins.

Ameliorative effect of probiotics (Lactobacillus paracaseii and Protexin®) and prebiotics (propolis and bee pollen) on clindamycin and propionic acid-induced oxidative stress and altered gut microbiota in a rodent model of autism.

Colonization by toxin-producing bacteria in the gut plays a major role in bowel problems in autistic patients. Prebiotics can inhibit the growth of these pathogenic microbes by nourishing beneficial bacteria, while probiotics--live microorganisms--can balance the gut bacteria; thus, both together can maintain healthy bacteria in the gut. The present study was conducted to find the effect of probiotics and prebiotics in balancing the gut flora in a rodent model of autism linked with a clindamycin-induced altered gut. The effects of probiotics and prebiotics on oxidative stress markers in the brain were also evaluated. Eight groups of hamsters were assigned, with Group I serving as the control; Group II, as the autistic model, was treated with 250 mg propionic acid/kg BW/day for 3 days; Group III was treated with clindamycin 30 mg/kg BW for 3 days; Groups IV and V were treated with bee pollen and propolis (supposed prebiotics) at a dose of 250 mg/kg BW/day for 28 days; Group VI and Group VII were treated with Lactobacillus paracaseii and Protexin® (supposed probiotics) for 28 days; and finally, Group VIII was anorectally transplanted with stool from normal animals for 5 days. Remarkable changes were measured in oxidative stress markers, primarily glutathione and vitamin C, in the brains of hamsters in the propionic acid- and clindamycin-treated group. All probiotic/prebiotic treatments showed ameliorative effects; however, lactobacillus had the strongest effect. We conclude that pro-and prebiotic supplements may be effective to revive healthy digestive system function in autistic patients. The disappointing results of the fecal transplants suggest that further study is needed to develop an appropriate technique.

Candida spp. en la microbiota intestinal de las personas con autismo: revisión sistemática / Candida spp. in the gut microbiota of people with autism: a systematic review

Introducción. Existe gran interés en los estudios sobre las implicaciones que la microbiota intestinal ejerce en el comportamiento de personas con trastornos del espectro autista (TEA) a través del eje microbiota-intestino-cerebro. La mayoría de los estudios sobre microbiota están enfocados en la posible implicación de las bacterias sobre personas con TEA, pero pocos versan sobre el efecto de los microorganismos del reino Fungi. Sujetos y métodos. Se realiza una revisión sistemática mediante el protocolo PRISMA de la presencia de Candida spp. en las personas con TEA. Resultados. Se encontró un total de tres artículos tras aplicar los criterios de exclusión e inclusión de la revisión sistemática. Dos estudios coincidieron en mostrar diferencias significativas en el aumento de la frecuencia del género Candida spp. en personas con TEA, mientras que en otro no se hallaron diferencias. Conclusiones. Pese a que existe una clara falta de investigación tanto del género Candida ssp. como de todo el reino Fungi en las personas con TEA, los estudios apuntan a una importante presencia de dicho género en este colectivo. Concretamente, en los resultados encontrados se destaca la mayor prevalencia del género C. albicans en los niños con TEA. Sin embargo, aún se sabe poco sobre la implicación de Candida spp. y otros tipos de hongos sobre los síntomas gastrointestinales y la sintomatología del autismo en niños con TEA

Introduction. There is great interest in studies on the implications that gut microbiota exerts on the behavior of people with autism spectrum disorders (ASD), through the microbiota-gut-brain axis. Most studies on microbiota are focused on the possible involvement of bacteria on people with ASD, but few of them are focussed on the effect of microorganisms in the Fungi kingdom. Subjects and methods. The present study performs a systematic review of the presence of Candida spp. in people with ASD using the PRISMA method. Results. A total of three articles were found after applying the exclusion and inclusion criteria of the systematic review. Two studies coincided in reporting significant differences in the increase in the frequency of the Candida spp. genus in people with ASD. while the third study did not report significant differences of Candida spp. genus between people with ASD. Conclusions. Although there is a clear lack of investigation of both the Candida ssp. genus and the whole Fungi kingdom in people with ASD, the studies point to an important presence of this genre in this group. Specifically, in the results found in this review, the highest prevalence of the C. albicans in children with ASD stands out. However, little is still known about the involvement of Candida spp., and other types of fungi, on gastrointestinal symptoms and ASD symptoms, in children with ASD

[Candida spp. in the gut microbiota of people with autism: a systematic review]. / Candida spp. en la microbiota intestinal de las personas con autismo: revision sistematica.

INTRODUCTION: There is great interest in studies on the implications that gut microbiota exerts on the behavior of people with autism spectrum disorders (ASD), through the microbiota-gut-brain axis. Most studies on microbiota are focused on the possible involvement of bacteria on people with ASD, but few of them are focussed on the effect of microorganisms in the Fungi kingdom. SUBJECTS AND METHODS: The present study performs a systematic review of the presence of Candida spp. in people with ASD using the PRISMA method. RESULTS: A total of three articles were found after applying the exclusion and inclusion criteria of the systematic review. Two studies coincided in reporting significant differences in the increase in the frequency of the Candida spp. genus in people with ASD. while the third study did not report significant differences of Candida spp. genus between people with ASD. CONCLUSIONS: Although there is a clear lack of investigation of both the Candida ssp. genus and the whole Fungi kingdom in people with ASD, the studies point to an important presence of this genre in this group. Specifically, in the results found in this review, the highest prevalence of the C. albicans in children with ASD stands out. However, little is still known about the involvement of Candida spp., and other types of fungi, on gastrointestinal symptoms and ASD symptoms, in children with ASD.

TITLE: Candida spp. en la microbiota intestinal de las personas con autismo: revision sistematica.Introduccion. Existe gran interes en los estudios sobre las implicaciones que la microbiota intestinal ejerce en el comportamiento de personas con trastornos del espectro autista (TEA) a traves del eje microbiota-intestino-cerebro. La mayoria de los estudios sobre microbiota estan enfocados en la posible implicacion de las bacterias sobre personas con TEA, pero pocos versan sobre el efecto de los microorganismos del reino Fungi. Sujetos y metodos. Se realiza una revision sistematica mediante el protocolo PRISMA de la presencia de Candida spp. en las personas con TEA. Resultados. Se encontro un total de tres articulos tras aplicar los criterios de exclusion e inclusion de la revision sistematica. Dos estudios coincidieron en mostrar diferencias significativas en el aumento de la frecuencia del genero Candida spp. en personas con TEA, mientras que en otro no se hallaron diferencias. Conclusiones. Pese a que existe una clara falta de investigacion tanto del genero Candida ssp. como de todo el reino Fungi en las personas con TEA, los estudios apuntan a una importante presencia de dicho genero en este colectivo. Concretamente, en los resultados encontrados se destaca la mayor prevalencia del genero C. albicans en los niños con TEA. Sin embargo, aun se sabe poco sobre la implicacion de Candida spp. y otros tipos de hongos sobre los sintomas gastrointestinales y la sintomatologia del autismo en niños con TEA.

The valproic acid rat model of autism presents with gut bacterial dysbiosis similar to that in human autism.

Background: Gut microbiota has the capacity to impact the regular function of the brain, which can in turn affect the composition of microbiota. Autism spectrum disorder (ASD) patients suffer from gastrointestinal problems and experience changes in gut microbiota; however, it is not yet clear whether the change in the microbiota associated with ASD is a cause or a consequence of the disease. Methods: We have investigated the species richness and microbial composition in a valproic acid (VPA)-induced rat model autism. Fecal samples from the rectum were collected at necropsy, microbial total DNA was extracted, 16 rRNA genes sequenced using Illumina, and the global microbial co-occurrence network was constructed using a random matrix theory-based pipeline. Collected rat microbiome data were compared to available data derived from cases of autism. Results: We found that VPA administration during pregnancy reduced fecal microbial richness, changed the gut microbial composition, and altered the metabolite potential of the fecal microbial community in a pattern similar to that seen in patients with ASD. However, the global network property and network composition as well as microbial co-occurrence patterns were largely preserved in the offspring of rats exposed to prenatal administration of VPA. Conclusions: Our data on the microbiota of the VPA rat model of autism indicate that this model, in addition to behaviorally and anatomically mimicking the autistic brain as previously shown, also mimics the microbiome features of autism, making it one of the best-suited rodent models for the study of autism and ASD.

Diurnal oscillations in human salivary microRNA and microbial transcription: Implications for human health and disease.

The microbiome plays a vital role in human health and disease. Interaction between human hosts and the microbiome occurs through a number of mechanisms, including transcriptomic regulation by microRNA (miRNA). In animal models, circadian variations in miRNA and microbiome elements have been described, but patterns of co-expression and potential diurnal interaction in humans have not. We investigated daily oscillations in salivary miRNA and microbial RNA to explore relationships between these components of the gut-brain-axis and their implications in human health. Nine subjects provided 120 saliva samples at designated times, on repeated days. Samples were divided into three sets for exploration and cross-validation. Identification and quantification of host miRNA and microbial RNA was performed using next generation sequencing. Three stages of statistical analyses were used to identify circadian oscillators: 1) a two-way analysis of variance in the first two sample sets identified host miRNAs and microbial RNAs whose abundance varied with collection time (but not day); 2) multivariate modeling identified subsets of these miRNAs and microbial RNAs strongly-associated with collection time, and evaluated their predictive ability in an independent hold-out sample set; 3) regulation of circadian miRNAs and microbial RNAs was explored in data from autistic children with disordered sleep (n = 77), relative to autistic peers with typical sleep (n = 63). Eleven miRNAs and 11 microbial RNAs demonstrated consistent diurnal oscillation across sample sets and accurately predicted collection time in the hold-out set. Associations among five circadian miRNAs and four circadian microbial RNAs were observed. We termed the 11 miRNAs CircaMiRs. These CircaMiRs had 1,127 predicted gene targets, with enrichment for both circadian gene targets and metabolic signaling processes. Four CircaMiRs had "altered" expression patterns among children with disordered sleep. Thus, novel and correlated circadian oscillations in human miRNA and microbial RNA exist and may have distinct implications in human health and disease.

Cutting Edge: Critical Roles for Microbiota-Mediated Regulation of the Immune System in a Prenatal Immune Activation Model of Autism.

Recent studies suggest that autism is often associated with dysregulated immune responses and altered microbiota composition. This has led to growing speculation about potential roles for hyperactive immune responses and the microbiome in autism. Yet how microbiome-immune cross-talk contributes to neurodevelopmental disorders currently remains poorly understood. In this study, we report critical roles for prenatal microbiota composition in the development of behavioral abnormalities in a murine maternal immune activation (MIA) model of autism that is driven by the viral mimetic polyinosinic-polycytidylic acid. We show that preconception microbiota transplantation can transfer susceptibility to MIA-associated neurodevelopmental disease and that this is associated with modulation of the maternal immune response. Furthermore, we find that ablation of IL-17a signaling provides protection against the development of neurodevelopmental abnormalities in MIA offspring. Our findings suggest that microbiota landscape can influence MIA-induced neurodevelopmental disease pathogenesis and that this occurs as a result of microflora-associated calibration of gestational IL-17a responses.