Microbiota transplant therapy and autism: lessons for the clinic

The role of secondary genomes in neurodevelopment and co-evolutionary dynamics

This chapter examines how human biology and microbial "secondary genomes" have co-evolved to shape neurodevelopment through the gut-brain axis. Microbial communities generate metabolites that cross blood-brain and placental barriers, influencing synaptogenesis, immune responses, and neural circuit formation. Simultaneously, Human Accelerated Regions (HARs) and Endogenous Retroviruses (ERVs) modulate gene expression and immune pathways, determining which microbes thrive in the gut and impacting brain maturation. These factors converge to form a dynamic host-microbe dialogue with significant consequences for neurodevelopmental disorders (NDD), including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and schizophrenia. Building on evolutionary perspectives, the chapter elucidates how genetic and immune mechanisms orchestrate beneficial and pathological host-microbe interactions in early brain development. It then explores therapeutic strategies, such as probiotics, prebiotics, fecal microbiota transplantation, and CRISPR-driven microbial engineering, targeting gut dysbiosis to mitigate or prevent neurodevelopmental dysfunctions. Furthermore, innovative organ-on-chip models reveal mechanistic insights under physiologically relevant conditions, offering a translational bridge between in vitro experiments and clinical applications. As the field continues to evolve, this work underscores the translational potential of manipulating the microbiome to optimize neurological outcomes. It enriches our understanding of the intricate evolutionary interplay between host genomes and the microbial world.

Fecal microbiota transplantation modulates jejunal host-microbiota interface in weanling piglets

BACKGROUND

Weaning-associated enteric diseases are a major concern in the swine industry. This study investigates the effects of fecal microbiota transplantation (FMT) on the jejunum of weanling piglets, a segment of bowel less studied in terms of microbiomic changes despite its primary involvement in major post-weaning enteric diseases, including postweaning diarrhea (PWD). Thirty-two 3-week-old piglets were divided equally into two groups: Control and FMT. The FMT group received fecal microbiota preparation from 3-month-old healthy pigs on the 1st and 3rd day after weaning. Half of each group was inoculated with an enterotoxigenic E. coli (ETEC) isolate 10 days post-FMT. Piglets were euthanized in the third week (14th and 18th days post-FMT) after weaning to collect intestinal tissues and contents for microbiomic, metabolomic, and transcriptomic analyses.

RESULTS

The jejunal microbiota showed a significant increase in alpha diversity in the third week post-FMT compared with the ileum and colon. FMT significantly enriched the jejunal microbiota composition, while multiple bacterial genera were specifically lacking in control weanling piglets. FMT was strongly associated with the enrichment of the genus Pseudoscardovia of the Bifidobacteriaceae family, which was found lacking in the jejunum of weanling control piglets and inversely associated with the abundance of the genus Bifidobacterium within the same family. Other genera associated with FMT included Solobacterium, Shuttleworthia, and Pseudoraminibacter, whereas bacteria such as Erysipelotrichaceae and Acidaminococcus were identified as most abundant in the control piglets. Metabolomic analysis revealed a significant modulatory effect of FMT on carbohydrate, amino acid, nucleotide, vitamin, and xenobiotic metabolisms, suggesting improved nutrient utilization. Transcriptomic analyses further confirmed the regulatory effects of FMT on gene expression associated with immune, metabolic, barrier, and neuroendocrine functions. Prior FMT treatment in the context of ETEC infection indicated a potential protective role, as evidenced by a significant shift in microbial diversity and metabolomic compositions and decreased diarrhea severity even though no effect on pathogen shedding was evident.

CONCLUSIONS

This study underscores the promise of FMT in enhancing jejunal health. In addition, the results suggest that FMT could be considered a potential strategy to address conditions associated with small intestinal dysbiosis in swine and other monogastric species with similar gut anatomy and physiology, such as humans. Video Abstract.

IUPHAR review: Targeted therapies of signaling pathways based on the gut microbiome in autism spectrum disorders: Mechanistic and therapeutic applications

Autism spectrum disorders (ASD) are complex neurodevelopmental disorders characterized by impairments in social interaction, communication and repetitive activities. Gut microbiota significantly influences behavior and neurodevelopment by regulating the gut-brain axis. This review explores gut microbiota-influenced treatments for ASD, focusing on their therapeutic applications and mechanistic insights. In addition, this review discusses the interactions between gut microbiota and the immune, metabolic and neuroendocrine systems, focusing on crucial microbial metabolites including short-chain fatty acids (SCFAs) and several neurotransmitters. Furthermore, the review explores various therapy methods including fecal microbiota transplantation, dietary modifications, probiotics and prebiotics and evaluates their safety and efficacy in reducing ASD symptoms. The discussion shows the potential of customized microbiome-based therapeutics and the integration of multi-omics methods to understand the underlying mechanisms. Moreover, the review explores the intricate relationship between gut microbiota and ASD, aiming to develop innovative therapies that utilize the gut microbiome to improve the clinical outcomes of ASD patients. Microbial metabolites such as neurotransmitter precursors, tryptophan metabolites and SCFAs affect brain development and behavior. Symptoms of ASD are linked to changes in these metabolites. Dysbiosis in the gut microbiome may impact neuroinflammatory processes linked to autism, negatively affecting immune signaling pathways. Research indicates that probiotics and prebiotics can improve gut microbiota and alleviate symptoms in ASD patients. Fecal microbiota transplantation may also improve behavioral symptoms and restore gut microbiota balance. The review emphasizes the need for further research on gut microbiota modification as a potential therapeutic approach for ASD, highlighting its potential in clinical settings.

Synapse and primary cilia dysfunctions in Autism Spectrum Disorders. Avenues to normalize these functions

AIM

An update on the plasticity of the brain networks involved in autism (autism spectrum disorders [ASD]), and the increasing role of their synapses and primary non-motile cilia.

METHODS

Data from PubMed and Google on this subject, published until February 2024, were analyzed.

RESULTS

Structural and functional brain characteristics and genetic particularities involving synapses and cilia that modify neuronal circuits are observed in ASD, such as reduced pruning of dendrites, minicolumnar pathology, or persistence of connections usually doomed to disappear. Proteins involved in synapse functions (such as neuroligins and neurexins), in the postsynaptic architectural scaffolding (such as Shank proteins) or in cilia functions (such as IFT-independent kinesins) are often abnormal. There is an increase in glutaminergic transmission and a decrease in GABA inhibition. ASD may occur in genetic ciliopathies. The means of modulating these specificities, when deemed useful, are described.

INTERPRETATION

The wide range of clinical manifestations of ASD is strongly associated with abnormalities in the morphology, functions, and plasticity of brain networks, involving their synapses and non-motile cilia. Their modulation offers important research perspectives on treatments when needed, especially since brain plasticity persists much later than previously thought. Improved early detection of ASD and additional studies on synapses and primary cilia are needed.

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.

Protocol for the Gut Bugs in Autism Trial: a double-blind randomised placebo-controlled trial of faecal microbiome transfer for the treatment of gastrointestinal symptoms in autistic adolescents and adults

INTRODUCTION

Autism (formally autism spectrum disorder) encompasses a group of complex neurodevelopmental conditions, characterised by differences in communication and social interactions. Co-occurring chronic gastrointestinal symptoms are common among autistic individuals and can adversely affect their quality of life. This study aims to evaluate the efficacy of oral encapsulated faecal microbiome transfer (FMT) in improving gastrointestinal symptoms and well-being among autistic adolescents and adults.

METHODS AND ANALYSIS

This double-blind, randomised, placebo-controlled trial will recruit 100 autistic adolescents and adults aged 16-45 years, who have mild to severe gastrointestinal symptoms (Gastrointestinal Symptoms Rating Scale (GSRS) score ≥2.0). We will also recruit eight healthy donors aged 18-32 years, who will undergo extensive clinical screening. Recipients will be randomised 1:1 to receive FMT or placebo, stratified by biological sex. Capsules will be administered over two consecutive days following an overnight bowel cleanse with follow-up assessments at 6, 12 and 26 weeks post-treatment. The primary outcome is GSRS score at 6 weeks. Other assessments include anthropometry, body composition, hair cortisol concentration, gut microbiome profile, urine/plasma gut-derived metabolites, plasma markers of gut inflammation/permeability and questionnaires on general well-being, sleep quality, physical activity, food diversity and treatment tolerability. Adverse events will be recorded and reviewed by an independent data monitoring committee.

ETHICS AND DISSEMINATION

Ethics approval for the study was granted by the Central Health and Disability Ethics Committee on 24 August 2021 (reference number: 21/CEN/211). Results will be published in peer-reviewed journals and presented to both scientific and consumer group audiences.

TRIAL REGISTRATION NUMBER

ACTRN12622000015741.

Fecal microbiota transplantation in a child with severe ASD comorbidities of gastrointestinal dysfunctions-a case report

Autism spectrum disorder (ASD) is a neurodevelopmental disorder defined by social communication impairments and restricted, repetitive behaviors. In addition to behavioral interventions and psychotherapies, and pharmacological interventions, in-depth studies of intestinal microbiota in ASD has obvious abnormalities which may effectively influenced in ASD. Several attempts have been made to indicate that microbiota can reduce the occurrence of ASD effectively. Fecal microbiota transplantation (FMT) is a type of biological therapy that involves the transplant of intestinal microbiota from healthy donors into the patient's gastrointestinal tract to improve the gut microenvironment. In this case report, we describe a case of child ASD treated by FMT. The patient have poor response to long-term behavioral interventions. After five rounds of FMT, clinical core symptoms of ASD and gastrointestinal(GI) symptoms were significantly altered. Moreover, the multiple levels of functional development of child were also significantly ameliorated. We found that FMT changed the composition of the intestinal microbiota as well as the metabolites, intestinal inflammatory manifestations, and these changes were consistent with the patient's symptoms. This report suggests further FMT studies in ASD could be worth pursuing, and more studies are needed to validate the effectiveness of FMT in ASD and its mechanisms.

Fecal Microbiota Transplantation for Acute Graft-versus-Host Disease After Allogeneic Hematopoietic Cell Transplantation: Expanding the Horizon into Pediatrics

The microbiome plays a vital role in maintaining homeostasis of the intestinal microenvironment and immune response in allogeneic hematopoietic cell transplantation (HCT) recipients. Disruption of the intestinal microbiome has been associated with the development of acute graft-versus-host disease (GVHD) of the lower GI tract and worse survival. Fecal microbiota transplantation (FMT) can achieve clinical responses in refractory GVHD, establishing the promise of microbiome-directed interventions in this population. While most data about microbial changes in HCT recipients have been generated from the adult population, children with refractory GVHD represent an important group that may benefit from FMT. In this review, we first highlight characteristics that distinguish the pediatric intestinal microbiome from adults. Subsequently, we explore multiple clinical factors that warrant careful consideration to optimize the application of FMT and other microbiome-directed therapeutics to children.

Physical Activity, Gut Microbiota, and Genetic Background for Children and Adolescents with Autism Spectrum Disorder

It is estimated that one in 100 children worldwide has been diagnosed with autism spectrum disorder (ASD). Children with ASD frequently suffer from gut dysbiosis and gastrointestinal issues, findings which possibly play a role in the pathogenesis and/or severity of their condition. Physical activity may have a positive effect on the composition of the intestinal microbiota of healthy adults. However, the effect of exercise both on the gastrointestinal problems and intestinal microbiota (and thus possibly on ASD) itself in affected children is unknown. In terms of understanding the physiopathology and manifestations of ASD, analysis of the gut-brain axis holds some promise. Here, we discuss the physiopathology of ASD in terms of genetics and microbiota composition, and how physical activity may be a promising non-pharmaceutical approach to improve ASD-related symptoms.

Role of Gut Microbiome in Autism Spectrum Disorder and Its Therapeutic Regulation

Autism spectrum disorder (ASD) is a neurological disorder that affects normal brain development. The recent finding of the microbiota-gut-brain axis indicates the bidirectional connection between our gut and brain, demonstrating that gut microbiota can influence many neurological disorders such as autism. Most autistic patients suffer from gastrointestinal (GI) symptoms. Many studies have shown that early colonization, mode of delivery, and antibiotic usage significantly affect the gut microbiome and the onset of autism. Microbial fermentation of plant-based fiber can produce different types of short-chain fatty acid (SCFA) that may have a beneficial or detrimental effect on the gut and neurological development of autistic patients. Several comprehensive studies of the gut microbiome and microbiota-gut-brain axis help to understand the mechanism that leads to the onset of neurological disorders and find possible treatments for autism. This review integrates the findings of recent years on the gut microbiota and ASD association, mainly focusing on the characterization of specific microbiota that leads to ASD and addressing potential therapeutic interventions to restore a healthy balance of gut microbiome composition that can treat autism-associated symptoms.

An anxious relationship between Autism Spectrum Disorder and Gut Microbiota: A tangled chemistry?

Autism spectrum disorder (ASD) is a serious multifactorial neurodevelopmental disorder often accompanied by strained social communication, repetitive behaviour, immune dysregulation, and gastrointestinal (GI) issues. Recent studies have recorded a link between dysbiosis in the gut microbiota (gm) and the primary stages of ASD. A bidirectional connection (also called microbiota-gut-brain-axis) exchanges information between the gut bacteria and central nervous system. When the homeostasis of the microenvironment of the gut is dysregulated, it causes oxidative stress, affecting neuronal cells and neurotransmitters, thereby causing neurodevelopmental disorders. Studies have confirmed a difference in the constitution of gut bacteria among ASD cases and their controls. Numerous studies on animal models of ASD have shown altered gm and its association with abnormal metabolite profile and altered behaviour phenotype. This process happens due to an abnormal metabolite production in gm, leading to changes in the immune system, especially in ASD. Hence, this review aims to question the current knowledge on gm dysbiosis and its related GI discomforts and ASD behavioural symptoms and shed light on the possible therapeutic approaches available to deal with this situation. Thereby, though it is understood that more research might be needed to prove an association or causal relationship between gm and ASD, therapy with the microbiome may also be considered as an effective strategy to combat this issue.

Gastrointestinal disorders in children with autism: Could artificial intelligence help?

Autism is one of the pervasive neurodevelopmental disorders usually associated with many medical comorbidities. Gastrointestinal (GI) disorders are pervasive in children, with a 46%-84% prevalence rate. Children with Autism have an increased frequency of diarrhea, nausea and/or vomiting, gastroesophageal reflux and/or disease, abdominal pain, chronic flatulence due to various factors as food allergies, gastrointestinal dysmotility, irritable bowel syndrome (IBS), and inflammatory bowel diseases (IBD). These GI disorders have a significant negative impact on both the child and his/her family. Artificial intelligence (AI) could help diagnose and manage Autism by improving children's communication, social, and emotional skills for a long time. AI is an effective method to enhance early detection of GI disorders, including GI bleeding, gastroesophageal reflux disease, Coeliac disease, food allergies, IBS, IBD, and rectal polyps. AI can also help personalize the diet for children with Autism by microbiome modification. It can help to provide modified gluten without initiating an immune response. However, AI has many obstacles in treating digestive diseases, especially in children with Autism. We need to do more studies and adopt specific algorithms for children with Autism. In this article, we will highlight the role of AI in helping children with gastrointestinal disorders, with particular emphasis on children with Autism.

Mild Hypophagia and Associated Changes in Feeding-Related Gene Expression and c-Fos Immunoreactivity in Adult Male Rats with Sodium Valproate-Induced Autism

A core yet understudied symptom of autism is aberrant eating behaviour, including extremely narrow food preferences. Autistic individuals often refuse to eat despite hunger unless preferred food is given. We hypothesised that, apart from aberrant preference, underfeeding stems from abnormal hunger processing. Utilising an adult male VPA rat, a model of autism, we examined intake of ‘bland’ chow in animals maintained on this diet continuously, eating this food after fasting and after both food and water deprivation. We assessed body weight in adulthood to determine whether lower feeding led to slower growth. Since food intake is highly regulated by brain processes, we looked into the activation (c-Fos immunoreactivity) of central sites controlling appetite in animals subjected to food deprivation vs. fed ad libitum. Expression of genes involved in food intake in the hypothalamus and brain stem, regions responsible for energy balance, was measured in deprived vs. sated animals. We performed our analyses on VPAs and age-matched healthy controls. We found that VPAs ate less of the ‘bland’ chow when fed ad libitum and after deprivation than controls did. Their body weight increased more slowly than that of controls when maintained on the ‘bland’ food. While hungry controls had lower c-Fos IR in key feeding-related areas than their ad libitum-fed counterparts, in hungry VPAs c-Fos was unchanged or elevated compared to the fed ones. The lack of changes in expression of feeding-related genes upon deprivation in VPAs was in contrast to several transcripts affected by fasting in healthy controls. We conclude that hunger processing is dysregulated in the VPA rat.

Autonomic Nervous System Neuroanatomical Alterations Could Provoke and Maintain Gastrointestinal Dysbiosis in Autism Spectrum Disorder (ASD): A Novel Microbiome-Host Interaction Mechanistic Hypothesis

Dysbiosis secondary to environmental factors, including dietary patterns, antibiotics use, pollution exposure, and other lifestyle factors, has been associated to many non-infective chronic inflammatory diseases. Autism spectrum disorder (ASD) is related to maternal inflammation, although there is no conclusive evidence that affected individuals suffer from systemic low-grade inflammation as in many psychological and psychiatric diseases. However, neuro-inflammation and neuro-immune abnormalities are observed within ASD-affected individuals. Rebalancing human gut microbiota to treat disease has been widely investigated with inconclusive and contradictory findings. These observations strongly suggest that the forms of dysbiosis encountered in ASD-affected individuals could also originate from autonomic nervous system (ANS) functioning abnormalities, a common neuro-anatomical alteration underlying ASD. According to this hypothesis, overactivation of the sympathetic branch of the ANS, due to the fact of an ASD-specific parasympathetic activity deficit, induces deregulation of the gut-brain axis, attenuating intestinal immune and osmotic homeostasis. This sets-up a dysbiotic state, that gives rise to immune and osmotic dysregulation, maintaining dysbiosis in a vicious cycle. Here, we explore the mechanisms whereby ANS imbalances could lead to alterations in intestinal microbiome-host interactions that may contribute to the severity of ASD by maintaining the brain-gut axis pathways in a dysregulated state.

Effect of probiotics combined with applied behavior analysis in the treatment of children with autism spectrum disorder: a prospective randomized controlled trial

OBJECTIVES

To study the effect of probiotics combined with applied behavior analysis (ABA) in the treatment of children with autism spectrum disorder (ASD).

METHODS

A total of 41 children with ASD who attended the Affiliated Hospital of Jiangsu University from May 2019 to December 2020 were enrolled and randomly divided into an observation group with 21 children and a control group with 20 children. The children in the observation group were given oral probiotics combined with ABA intervention, while those in the control group were given ABA intervention alone. The treatment outcomes were compared between the two groups. Autism Treatment Evaluation Checklist (ATEC) was used to evaluate the severity of behavioral symptoms in both groups before intervention and at 3 months after intervention. The fecal samples were collected to analyze the difference in intestinal flora between the two groups based on 16s rRNA high-throughput sequencing.

RESULTS

Before intervention, there was no significant difference in the ATEC score between the observation and control groups (P>0.05). At 3 months after intervention, both groups had a significant reduction in the ATEC score, and the observation group had a significantly lower ATEC score than the control group (P<0.05). Before intervention, there was no significant difference in the composition of intestinal flora between the observation and control groups. At 3 months after intervention, there was a significant difference in the composition of intestinal flora between the observation and control groups. Compared with the control group, the observation group had significantly higher relative abundances of Bifidobacterium, Lactobacillus, Coprobacillus, Ruminococcus, Prevotella, and Blautia (P<0.05) and significantly lower relative abundances of Shigella and Clostridium (P<0.05).

CONCLUSIONS

Probiotics may improve the effect of conventional ABA intervention in children with ASD by regulating intestinal flora.

Microbiome First Medicine in Health and Safety

Microbiome First Medicine is a suggested 21st century healthcare paradigm that prioritizes the entire human, the human superorganism, beginning with the microbiome. To date, much of medicine has protected and treated patients as if they were a single species. This has resulted in unintended damage to the microbiome and an epidemic of chronic disorders [e.g., noncommunicable diseases and conditions (NCDs)]. Along with NCDs came loss of colonization resistance, increased susceptibility to infectious diseases, and increasing multimorbidity and polypharmacy over the life course. To move toward sustainable healthcare, the human microbiome needs to be front and center. This paper presents microbiome-human physiology from the view of systems biology regulation. It also details the ongoing NCD epidemic including the role of existing drugs and other factors that damage the human microbiome. Examples are provided for two entryway NCDs, asthma and obesity, regarding their extensive network of comorbid NCDs. Finally, the challenges of ensuring safety for the microbiome are detailed. Under Microbiome-First Medicine and considering the importance of keystone bacteria and critical windows of development, changes in even a few microbiota-prioritized medical decisions could make a significant difference in health across the life course.

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 self-serving benefits of being a good host: A role for our micro-inhabitants in shaping opioids' function

Opioids are highly efficacious in their ability to relieve pain, but they are liable for abuse, dependence, and addiction. Risk factors to develop opioid use disorders (OUD) include chronic stress, socio-environment, and preexisting major depressive disorders (MDD) and posttraumatic stress disorders (PTSD). Additionally, opioids reduce gut motility, induce loss of gut barrier function, and alter the composition of the trillions of microbes hosted in the gastrointestinal tract, known as the gut microbiota. The microbiota are significant contributors to the reciprocal communication between the central nervous system (CNS) and the gut, termed the gut-brain axis. They have strong influences on their host behaviors, including the ability to cope with stress, sociability, affect, mood, and anxiety. Thus, they are implicated in the etiology of MDD and PTSD. Here we review the latest studies demonstrating that intestinal flora can, directly and indirectly, by affecting sociability levels, responses to stress, and mental state, alter the responses to opioids. It suggests that microbiota can potentially be used to increase the resilience to develop analgesic tolerance and OUD.

Unravelling the potential of gut microbiota in sustaining brain health and their current prospective towards development of neurotherapeutics

Increasing incidences of neurological disorders, such as Parkinson's disease (PD), multiple sclerosis (MS), Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) are being reported, but an insight into their pathology remains elusive. Findings have suggested that gut microbiota play a major role in regulating brain functions through the gut-brain axis. A unique bidirectional communication between gut microbiota and maintenance of brain health could play a pivotal role in regulating incidences of neurodegenerative diseases. Contrarily, the present life style with changing food habits and disturbed circadian rhythm may contribute to gut homeostatic imbalance and dysbiosis leading to progression of several neurological disorders. Therefore, dysbiosis, as a primary factor behind intestinal disorders, may also augment inflammation, intestinal and blood-brain barrier permeability through microbiota-gut-brain axis. This review primarily focuses on the gut-brain axis functions, specific gut microbial population, metabolites produced by gut microbiota, their role in regulating various metabolic processes and role of gut microbiota towards development of neurodegenerative diseases. However, several studies have reported a decrease in abundance of a specific gut microbial population and a corresponding increase in other microbial family, with few findings revealing some contradictions. Reports also showed that colonization of gut microbiota isolated from patients suffering from neurodegenerative disease leads to the development of enhance pathological outcomes in animal models. Hence, a systematic understanding of the dominant role of specific gut microbiome towards development of different neurodegenerative diseases could possibly provide novel insight into the use of probiotics and microbial transplantation as a substitute approach for treating/preventing such health maladies.

Faecal microbiota transplantation for Clostridioides difficile: mechanisms and pharmacology

Faecal microbiota transplantation (FMT) has emerged as a remarkably successful treatment for recurrent Clostridioides difficile infection that cannot be cured with antibiotics alone. Understanding the complex biology and pathogenesis of C. difficile infection, which we discuss in this Perspective, is essential for understanding the potential mechanisms by which FMT cures this disease. Although FMT has already entered clinical practice, different microbiota-based products are currently in clinical trials and are vying for regulatory approval. However, all these therapeutics belong to an entirely new class of agents that require the development of a new branch of pharmacology. Characterization of microbiota therapeutics uses novel and rapidly evolving technologies and requires incorporation of microbial ecology concepts. Here, we consider FMT within a pharmacological framework, including its essential elements: formulation, pharmacokinetics and pharmacodynamics. From this viewpoint, multiple gaps in knowledge become apparent, identifying areas that require systematic research. This knowledge is needed to help clinical providers use microbiota therapeutics appropriately and to facilitate development of next-generation microbiota products with improved safety and efficacy. The discussion here is limited to FMT as a representative of microbiota therapeutics and recurrent C. difficile as the indication; however, consideration of the intrinsic basic principles is relevant to this entire class of microbiota-based therapeutics.

Gut microbiota on gender bias in autism spectrum disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Its three core symptoms are social communication disorder, communication disorder, narrow interest and stereotyped repetitive behavior. The proportion of male and female autistic patients is 4:1. Many researchers have studied this phenomenon, but the mechanism is still unclear. This review mainly discusses the related mechanism from the perspective of gut microbiota and introduces the influence of gut microbiota on the difference of ASD between men and women, as well as how gut microbiota may affect the gender dimorphism of ASD through metabolite of microbiota, immunity, and genetics, which provide some useful information for those who are interested in this research and find more gender-specific treatment for autistic men and women.

Specialized Diet Therapies: Exploration for Improving Behavior in Autism Spectrum Disorder (ASD)

As a major neurodevelopmental disorder, Autism Spectrum Disorder (ASD) encompasses deficits in communication and repetitive and restricted interests or behaviors in childhood and adolescence. Its etiology may come from either a genetic, epigenetic, neurological, hormonal, or an environmental cause, generating pathways that often altogether play a synergistic role in the development of ASD pathogenesis. Furthermore, the metabolic origin of ASD should be important as well. A balanced diet consisting of the essential and special nutrients, alongside the recommended caloric intake, is highly recommended to promote growth and development that withstand the physiologic and behavioral challenges experienced by ASD children. In this review paper, we evaluated many studies that show a relationship between ASD and diet to develop a better understanding of the specific effects of the overall diet and the individual nutrients required for this population. This review will add a comprehensive update of knowledge in the field and shed light on the possible nutritional deficiencies, metabolic impairments (particularly in the gut microbiome), and malnutrition in individuals with ASD, which should be recognized in order to maintain the improved socio-behavioral habit and physical health.