New evidences on the altered gut microbiota in autism spectrum disorders

Probiotics in autism spectrum disorder: Recent insights from animal models

LAY ABSTRACT

Autism spectrum disorder is a neurodevelopmental disorder characterized by a wide range of behavioral alterations, including impaired social interaction and repetitive behaviors. Numerous pharmacological interventions have been developed for autism spectrum disorder, often proving ineffective and accompanied by a multitude of side effects. The gut microbiota is the reservoir of bacteria inhabiting our gastrointestinal tract. The gut microbial alterations observed in individuals with autism spectrum disorder, including elevated levels of Bacteroidetes, Firmicutes, and Proteobacteria, as well as reduced levels of Bifidobacterium, provide a basis for further investigation into the role of the gut microbiota in autism spectrum disorder. Recent preclinical studies have shown favorable outcomes with probiotic therapy, including improvements in oxidative stress, anti-inflammatory effects, regulation of neurotransmitters, and restoration of microbial balance. The aim of this review is to explore the potential of probiotics for the management and treatment of autism spectrum disorder, by investigating insights from recent studies in animals.

Yeast Extract Peptides Alleviate Depression in Chronic Restraint Stress Rats by Alleviating Hippocampal Neuronal Apoptosis and Dysbiosis of the Gut Microbiota

SCOPE

Depression as a global neurological disorder, and hippocampal neuronal apoptosis and disorders of the gut microbiota are closely related to it. This study aims to expose the ameliorative effect of enzyme peptides (AP) from brewer's yeast on depressive behavior caused by chronic restraint stress (CRS) in rats.

METHODS AND RESULTS

After 4 weeks of AP intervention, a significant alleviation of depressive behavior in the sucrose preference test (SPT), forced swim test (FST), and light-dark test (LDT) is observed in depressed rats. AP ameliorates neuronal damage with increased the expression of the key CREB/BDNF/TrkB/Akt signaling pathway, which increases the levels of the monoamine neurotransmitters 5-hydroxytryptamine (5-HT) and norepinephrine (NE) in the hippocampus, buffering hyperactivity of the hypothalamo-pituitary-adrenal axis (HPA), and decreasing the serum cortisol (CORT) and adrenocorticotropic hormone (ACTH) levels in rats. In addition, AP modulates the disruption of the rat gut microbiota by chronic restraint stress (CRS), and the changes in the abundance of Lactobacillus animalis and Lactobacillus johnsonii are probably the key for AP performing antidepressant benefits. A strong correlation is found between gut microbiota and biochemical markers of depression.

CONCLUSION

AP, as a natural and safe active substance, has a positive effect in the treatment of depression.

Unraveling the relative abundance of psychobiotic bacteria in children with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder characterized by social deficits. Accumulated evidence has shown a link between alterations in the composition of gut microbiota and both neurobehavioural and gastrointestinal symptoms in children with ASD which are related to the genera Lactobacillus and Bifidobacterium. These genera have been recently categorized as "psychobiotics". Moreover, this study aimed to compare the relative abundance of psychobiotics (L. plantarum, L. reuteri, and B. longum) to the total gut microbiome in typically developing (TD) children and those with ASD in order to correlate the distribution of psychobiotic with the severity and sensory impairments in autism. The ASD children were assessed using the Childhood Autism Rating Scale (CARS), while sensory impairments were evaluated using the Short Sensory Profile (SSP). Furthermore, the gut microbiome was analyzed using the quantitative real-time PCR. The study revealed a statistically significant increase in the relative abundance of L. reuteri and L. plantarum in the TD group in comparison to ASD children. Regarding the SSP total score of ASD children, a statistically significant negative correlation was found between both Lactobacillus and L. plantarum with the under-responsive subscale. For the Autism Treatment Evaluation Checklist (ATEC) score, B. longum and Lactobacillus showed a significant positive correlation with Health/Physical/Behaviour.

Alterations in microbiota-metabolism-circRNA crosstalk in autism spectrum disorder-like behaviours caused by maternal exposure to glyphosate-based herbicides in mice

Epidemiological evidence indicates exposure to glyphosate-based herbicides (GBHs) increases the risk for autism spectrum disorder (ASD). The gut microbiota has been found to influence ASD behaviours through the microbiota-gut-brain axis. However, the underlying links between early life GBH exposure and ASD-like phenotypes through the microbiota-gut-brain axis remain unclear. Therefore, we exposed mice to low-dose GBH (0.10, 0.25, 0.50, and 1.00 %) and determined the effects on ASD-like behaviours. Furthermore, three kinds of omics (gut microbiomics, metabolomics, and transcriptomics) were conducted to investigate the effects of GBH exposure on gut microbiota, gut metabolites, and circular RNAs (circRNAs) in the prefrontal cortex (PFC) using a cross-generational mouse model. Behavioural analyses suggested social impairment and repetitive/stereotypic behaviours in the GBH-exposed offspring. Furthermore, maternal exposure to glyphosate significantly altered the ASD-associated gut microbiota of offspring, and ASD-associated gut metabolites were identified. Specifically, we found that alterations in the gut microenvironment may contribute to changes in gut permeability and the blood-brain barrier, which are related to changes in the levels of circRNAs in the PFC. Our results suggest a potential effect of circRNAs through the disruption of the gut-brain interaction, which is an important factor in the pathogenesis of ASD in offspring induced by maternal exposure to GBH.

Correction of Batch Effect in Gut Microbiota Profiling of ASD Cohorts from Different Geographical Origins

BACKGROUND

To date, there have been numerous metataxonomic studies on gut microbiota (GM) profiling based on the analyses of data from public repositories. However, differences in study population and wet and dry pipelines have produced discordant results. Herein, we propose a biostatistical approach to remove these batch effects for the GM characterization in the case of autism spectrum disorders (ASDs).

METHODS

An original dataset of GM profiles from patients with ASD was ecologically characterized and compared with GM public digital profiles of age-matched neurotypical controls (NCs). Also, GM data from seven case-control studies on ASD were retrieved from the NCBI platform and exploited for analysis. Hence, on each dataset, conditional quantile regression (CQR) was performed to reduce the batch effects originating from both technical and geographical confounders affecting the GM-related data. This method was further applied to the whole dataset matrix, obtained by merging all datasets. The ASD GM markers were identified by the random forest (RF) model.

RESULTS

We observed a different GM profile in patients with ASD compared with NC subjects. Moreover, a significant reduction of technical- and geographical-dependent batch effects in all datasets was achieved. We identified Bacteroides_H, Faecalibacterium, Gemmiger_A_73129, Blautia_A_141781, Bifidobacterium_388775, and Phocaeicola_A_858004 as robust GM bacterial biomarkers of ASD. Finally, our validation approach provided evidence of the validity of the QCR method, showing high values of accuracy, specificity, sensitivity, and AUC-ROC.

CONCLUSIONS

Herein, we proposed an updated biostatistical approach to reduce the technical and geographical batch effects that may negatively affect the description of bacterial composition in microbiota studies.

Systemic toxicity of biodegradable polyglycolic acid microplastics on the gut-liver-brain axis in zebrafish

Polyglycolic acid (PGA), a novel type of hazardous biodegradable plastic, is gradually being widely used in the biomedical and food packaging industries. However, the long-term ecological effects of PGA degradation to microplastics (MPs) in aquatic organisms remain unknown. The gut-liver-brain axis regulates the exchange of information between the gut, liver, and brain, and is a key target for tissue damage caused by pollutants. Adult zebrafish were exposed to 1 or 100 mg/L PGA MP suspension for 28 d. PGA affects the intestinal vascular barrier through gene expression downstream of the Wnt/β-catenin pathway, increasing intestinal permeability and disrupting the environment of intestinal microbial diversity. This, in turn, promoted the accumulation of lipopolysaccharide (LPS). Disturbance of the intestinal microbiota balance and its metabolites are transferred to the liver and brain through the gut-liver-brain axis, causing disorders in hepatic lipid metabolism and synthesis. Behavioural experiments showed that long-term exposure to PGA MP caused anxiety-like behaviour and cognitive impairment, which may be related to the disruption of the gut-liver-brain axis, thus inducing inflammation and disrupting the normal functioning of the body. In summary, this study evaluated the safety of the new degradable plastic, PGA, but its ecological risks still require attention.

Integrated serum pharmacochemistry, 16S rDNA sequencing, and metabolomics to reveal the material basis and mechanism of Shouhui Tongbian capsule against diphenoxylate-induced slow transit constipation in rats

BACKGROUND

Slow transit constipation (STC) is highly prevalent and has rising incidence. Shouhui Tongbian capsule (SHTB) is a traditional Chinese Medicine formula with extensive and highly efficacious usage in STC treatment, however, its mechanism of action, especially the regulation of microbiome and lipid metabolites, remains unclear.

METHODS

After quality control of SHTB using LC‒MS to obtain its material basis, we tried to elucidate the cohesive modulatory network of SHTB against STC using hyphenated methods from microbiomics, lipidomics, mass spectrometry imaging (MSI) and molecular methods.

RESULTS

SHTB could repair intestinal barrier damage, reduce systemic inflammation and increase intestinal motility in a diphenoxylate-induced STC rat model. Based on 16S rDNA sequencing results, SHTB rehabilitated the abnormal changes in Alloprevotella, Coprococcus, Marvinbryantia, etc., which were associated with STC symptoms. Meanwhile, microbial functional prediction showed that lipid metabolism was improved with SHTB administration. The differential lipids, including fatty acids, lysophosphatidylcholine, phosphatidylcholine, sphingomyelin triglyceride and ceramide, that are closely related to STC disease and SHTB efficacy. Furthermore, SHTB significantly reversed the abnormal expression of these key target enzymes in colon samples, including CTP-phosphocholine cytidylyltransferase, CTP-phosphoethanolamine cytidylyltransferase, phosphatidic acid phosphatase, acid sphingomyelinase etc. CONCLUSIONS: Combined analysis demonstrated that SHTB reducing lipid accumulation and recovery of intestinal microbial homeostasis was the critical mechanism by which SHTB treats STC.

Impact of cooperative or competitive dynamics between the yeast Saccharomyces cerevisiae and lactobacilli on the immune response of the host

Fungi and bacteria can be found coexisting in a wide variety of environments. The combination of their physical and molecular interactions can result in a broad range of outcomes for each partner, from competition to cooperative relationships. Most of these interactions can also be found in the human gastrointestinal tract. The gut microbiota is essential for humans, helping the assimilation of food components as well as the prevention of pathogen invasions through host immune system modulation and the production of beneficial metabolites such as short-chain fatty acids (SCFAs). Several factors, including changes in diet habits due to the progressive Westernization of the lifestyle, are linked to the onset of dysbiosis statuses that impair the correct balance of the gut environment. It is therefore crucial to explore the interactions between commensal and diet-derived microorganisms and their influence on host health. Investigating these interactions through co-cultures between human- and fermented food-derived lactobacilli and yeasts led us to understand how the strains' growth yield and their metabolic products rely on the nature and concentration of the species involved, producing either cooperative or competitive dynamics. Moreover, single cultures of yeasts and lactobacilli proved to be ideal candidates for developing immune-enhancing products, given their ability to induce trained immunity in blood-derived human monocytes in vitro. Conversely, co-cultures as well as mixtures of yeasts and lactobacilli have been shown to induce an anti-inflammatory response on the same immune cells in terms of cytokine profiles and activation surface markers, opening new possibilities in the design of probiotic and dietary therapies.

Gut bacteria: an etiological agent in human pathological conditions

Through complex interactions with the host's immune and physiological systems, gut bacteria play a critical role as etiological agents in a variety of human diseases, having an impact that extends beyond their mere presence and affects the onset, progression, and severity of the disease. Gaining a comprehensive understanding of these microbial interactions is crucial to improving our understanding of disease pathogenesis and creating tailored treatment methods. Correcting microbial imbalances may open new avenues for disease prevention and treatment approaches, according to preliminary data. The gut microbiota exerts an integral part in the pathogenesis of numerous health conditions, including metabolic, neurological, renal, cardiovascular, and gastrointestinal problems as well as COVID-19, according to recent studies. The crucial significance of the microbiome in disease pathogenesis is highlighted by this role, which is comparable to that of hereditary variables. This review investigates the etiological contributions of the gut microbiome to human diseases, its interactions with the host, and the development of prospective therapeutic approaches. To fully harness the benefits of gut microbiome dynamics for improving human health, future research should address existing methodological challenges and deepen our knowledge of microbial interactions.

Turicibacter and Catenibacterium as potential biomarkers in autism spectrum disorders

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by social, behavioral, and cognitive impairments. Several comorbidities, including gastrointestinal (GI) dysregulations, are frequently reported in ASD children. Although studies in animals have shown the crucial role of the microbiota in key aspects of neurodevelopment, there is currently no consensus on how the alteration of microbial composition affects the pathogenesis of ASD. Moreover, disruption of the gut-brain axis (GBA) has been reported in ASD although with limited studies conducted on the Mediterranean population. In our study, we aimed to investigate gut microbiota composition in Lebanese ASD subjects, their unaffected siblings, and a control group from various regions in Lebanon using the 16 S-rRNA sequencing (NGS). Our study revealed a lower abundance of Turicibacter and a significant enrichment on Proteobacteria in the ASD and siblings' groups compared to the controls, indicating that gut microbiota is probably affected by dietary habits, living conditions together with host genetic factors. The study also showed evidence of changes in the gut microbiome of ASD children compared to their siblings and the unrelated control. Bacteroidetes revealed a lower abundance in the ASD group compared to controls and siblings, conversely, Catenibacterium and Tenericutes revealed an increased abundance in the ASD group. Notably, our study identifies alterations in the abundance of Turicibacter and Catenibacterium in ASD children suggesting a possible link between these bacterial taxa and ASD and contributing to the growing body of evidence linking the microbiome to ASD.

Metataxonomic and Immunological Analysis of Feces from Children with or without Phelan-McDermid Syndrome

Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder characterized by a developmental delay and autism spectrum disorder (ASD)-like behaviors. Emerging research suggests a link between gut microbiota and neuropsychiatric conditions, including PMS. This study aimed to investigate the fecal microbiota and immune profiles of children with PMS compared to healthy controls. Fecal samples were collected from children diagnosed with PMS and age-matched healthy controls. The bacterial composition was analyzed using 16S rRNA gene sequencing, while short-chain fatty acids (SCFAs) were quantified through gas chromatography. Immunological profiling was conducted using a multiplex cytokine assay. Significant differences were observed in the gut microbiota composition between PMS patients and controls, including a lower abundance of key bacterial genera such as Faecalibacterium and Agathobacter in PMS patients. SCFA levels were also reduced in PMS patients. Immunological analysis revealed higher levels of several pro-inflammatory cytokines in the PMS group, although these differences were not statistically significant. The findings indicate that children with PMS have distinct gut microbiota and SCFA profiles, which may contribute to the gastrointestinal and neurodevelopmental symptoms observed in this syndrome. These results suggest potential avenues for microbiota-targeted therapies in PMS.

Exposure to polystyrene microplastics reduces sociality and brain oxytocin levels through the gut-brain axis in mice

The rising global prevalence of microplastics (MPs) has highlighted their diverse toxicological effects. The oxytocin (OT) system in mammals, deeply intertwined with social behaviors, is recognized to be vulnerable to environmental stressors. We hypothesized that MP exposure might disrupt this system, a topic not extensively studied. We investigated the effects of MPs on behavioral neuroendocrinology via the gut-brain axis by exposing adolescent male C57BL/6 mice to varied sizes (5 μm and 50 μm) and concentrations (100 μg/L and 1000 μg/L) of polystyrene MPs over 10 weeks. The results demonstrated that exposure to 50 μm MPs significantly reduced colonic mucin production and induced substantial alterations in gut microbiota. Notably, the 50 μm-100 μg/L group showed a significant reduction in OT content within the medial prefrontal cortex and associated deficits in sociality, along with damage to the blood-brain barrier. Importantly, blocking the vagal pathway ameliorated these behavioral impairments, emphasizing the pivotal role of the gut-brain axis in mediating neurobehavioral outcomes. Our findings confirm the toxicity of MPs on sociality and the corresponding neuroendocrine systems, shedding light on the potential hazards and adverse effects of environmental MPs exposure on social behavior and neuroendocrine frameworks in social mammals, including humans.

Brain-gut-brain axis, nutrition, and autism spectrum disorders: a review

Autism is a neurological disorder that affects social skills and behavior. A significant number of children with autism spectrum disorders (ASDs) may not display noticeable symptoms until they reach the age of three or older. Several factors, including genetic and environmental issues, could affect the progression of ASD in children. Dietary behavior or administration may have a crucial role in the development of autism. Epidemiological investigations have demonstrated that environmental influences play a significant role in how changes in diet can affect behavior and physiology. However, exclusion diets have not been thoroughly studied in relation to this effect. Atypical food behaviors, altered nutritional profiles, and being overweight, obese, or underweight are all associated with autism in children. Overweight or underweight was common in children with autism, but it was not necessarily uncommon in children with normal growth. Moreover, deficiencies in certain vitamins (B12, B9, and D), minerals (calcium and iron), fatty acids (omega-3 and -6), energy, and protein have been documented in children with ASD. The deficiency of these nutrients may lead to gastrointestinal (GI) symptoms and change the microbiota in children with ASD. Some nutritional interventions could help individuals with ASD to improve their mental health. Recognizing dietary habits and nutrient requirements can help in planning the best overall treatment for autism. This review discusses GI symptoms and disorders related to nutrition and nutrient-dense diets for ASD.

The Immunomodulatory Effects of Selenium: A Journey from the Environment to the Human Immune System

Selenium (Se) is an essential nutrient that has gained attention for its impact on the human immune system. The purpose of this review is to explore Se's immunomodulatory properties and to make up-to-date information available so novel therapeutic applications may emerge. People acquire Se through dietary ingestion, supplementation, or nanoparticle applications. These forms of Se can beneficially modulate the immune system by enhancing antioxidant activity, optimizing the innate immune response, improving the adaptive immune response, and promoting healthy gut microbiota. Because of these many actions, Se supplementation can help prevent and treat pathogenic diseases, autoimmune diseases, and cancers. This review will discuss Se as a key micronutrient with versatile applications that supports disease management due to its beneficial immunomodulatory effects. Further research is warranted to determine safe dosing guidelines to avoid toxicity and refine the application of Se in medical treatments.

Intestinal permeability disturbances: causes, diseases and therapy

Nowadays, a pathological increase in the permeability of the intestinal barrier (the so-called leaky gut) is increasingly being diagnosed. This condition can be caused by various factors, mainly from the external environment. Damage to the intestinal barrier entails a number of adverse phenomena: dysbiosis, translocation of microorganisms deep into the intestinal tissue, immune response, development of chronic inflammation. These phenomena can ultimately lead to a vicious cycle that promotes the development of inflammation and further damage to the barrier. Activated immune cells in mucosal tissues with broken barriers can migrate to other organs and negatively affect their functioning. Damaged intestinal barrier can facilitate the development of local diseases such as irritable bowel disease, inflammatory bowel disease or celiac disease, but also the development of systemic inflammatory diseases such as rheumatoid arthritis, ankylosing spondylitis, hepatitis, and lupus erythematosus, neurodegenerative or psychiatric conditions, or metabolic diseases such as diabetes or obesity. However, it must be emphasized that the causal links between a leaky gut barrier and the onset of certain diseases often remain unclear and require in-depth research. In light of recent research, it becomes crucial to prevent damage to the intestinal barrier, as well as to develop therapies for the barrier when it is damaged. This paper presents the current state of knowledge on the causes, health consequences and attempts to treat excessive permeability of the intestinal barrier.

Effect of Group Mixing and Available Space on Performance, Feeding Behavior, and Fecal Microbiota Composition during the Growth Period of Pigs

Stress significantly affects the health, welfare, and productivity of farm animals. We performed a longitudinal study to evaluate stress's effects on pig performance, feeding behavior, and fecal microbiota composition. This study involved 64 Duroc pigs during the fattening period, divided into two experimental groups: a stress group (n = 32) and a control group (n = 32). Stressed groups had less space and were mixed twice during the experiment. We monitored body weight, feed efficiency, feeding behavior, and fecal microbiota composition. Compared to the control group, the stressed pigs exhibited reduced body weight, feed efficiency, fewer feeder visits, and longer meal durations. In the fecal microbiota, resilience was observed, with greater differences between groups when sampling was closer to the stressful stimulus. Stressed pigs showed an increase in opportunistic bacteria, such as Streptococcus, Treponema and members of the Erysipelotrichaceae family, while control pigs had more butyrate- and propionate-producing genera like Anaerobutyricum, Coprococcus and HUN007. Our findings confirm that prolonged stress negatively impacts porcine welfare, behavior, and performance, and alters their gut microbiota. Specific microorganisms identified could serve as non-invasive biomarkers for stress, potentially informing both animal welfare and similar gut-brain axis mechanisms relevant to human research.

Supplementation with Lactobacillus helveticus NS8 alleviated behavioral, neural, endocrine, and microbiota abnormalities in an endogenous rat model of depression

Introduction

Major depressive disorder is a condition involving microbiota-gut-brain axis dysfunction. Increasing research aims to improve depression through gut microbiota regulation, including interventions such as probiotics, prebiotics, and fecal microbiota transplants. However, most research focuses on exogenous depression induced by chronic stress or drugs, with less attention given to endogenous depression. Additionally, research on gut mycobiota in depression is significantly less than that on gut bacteria.

Methods

In the present study, Wistar-Kyoto rats were used as an endogenous depression and treatment-resistant depression model, while Wistar rats served as controls. Differences between the two rat strains in behavior, gut bacteria, gut mycobiota, nervous system, endocrine system, immune system, and gut barrier were evaluated. Additionally, the effects of Lactobacillus helveticus NS8 supplementation were investigated.

Results

Wistar-Kyoto rats demonstrated increased depressive-like behaviors in the forced swimming test, reduced sucrose preference in the sucrose preference test, and decreased locomotor activity in the open field test. They also exhibited abnormal gut bacteria and mycobiota, characterized by higher bacterial α-diversity but lower fungal α-diversity, along with increased butyrate, L-tyrosine, and L-phenylalanine biosynthesis from bacteria. Furthermore, these rats showed dysfunction in the microbiota-gut-brain axis, evidenced by a hypo-serotonergic system, hyper-noradrenergic system, defective hypothalamic-pituitary-adrenal axis, compromised gut barrier integrity, heightened serum inflammation, and diminished gut immunity. A 1-month L. helveticus NS8 intervention increased the fecal abundance of L. helveticus; reduced the abundance of Bilophila and Debaryomycetaceae; decreased immobility time but increased climbing time in the forced swimming test; reduced hippocampal corticotropin-releasing hormone levels; decreased hypothalamic norepinephrine levels; increased hippocampal glucocorticoid receptor, brain-derived neurotrophic factor dopamine, and 5-hydroxyindoleacetic acid content; and improved the gut microbiota, serotonergic, and noradrenergic system.

Conclusion

The depressive phenotype of Wistar-Kyoto rats is not only attributed to their genetic context but also closely related to their gut microbiota. Abnormal gut microbiota and a dysfunctional microbiota-gut-brain axis play important roles in endogenous depression, just as they do in exogenous depression. Supplementing with probiotics such as L. helveticus NS8 is likely a promising approach to improve endogenous depression and treatment-resistant depression.

The complex interplay between autism spectrum disorder and gut microbiota in children: A comprehensive review

Autism spectrum disorder (ASD) is characterized by defects in social communication and interaction along with restricted interests and/or repetitive behavior. Children with ASD often also experience gastrointestinal (GI) problems in fact incidence of GI problems in ASD is estimated up to 80 percent. Intestinal microbiota, which is a collection of trillions of microorganisms both beneficial and potentially harmful bacteria living inside the gut, has been considered one of the key elements of gut disorders. The goal of this review is to explore potential link between gut microbiota and ASD in children, based on the recently available data. This review discusses recent advances in this rapidly expanding area of neurodevelopmental disorders, which focuses on what is known about the changes in composition of gut bacteria in children with ASD, exploration of possible mechanisms via which gut microbiota might influence the brain and thus lead to appearance of ASD symptoms, as well as potential treatments that involve modulation of gut flora to improve symptoms in children with ASD, i.e., probiotics, postbiotics or changes in the diet. Of course, it's important to keep in mind inherent difficulties in proving of existence of causal relationships between gut bacteria and ASD. There are significant gaps in understanding of the mechanism of gut-brain axis and the mechanisms that underlie ASD. Standardized approaches for research in this area are needed. This review would provide an overview of this exciting emerging field of research.

Predicting superagers: a machine learning approach utilizing gut microbiome features

Objective

Cognitive decline is often considered an inevitable aspect of aging; however, recent research has identified a subset of older adults known as "superagers" who maintain cognitive abilities comparable to those of younger individuals. Investigating the neurobiological characteristics associated with superior cognitive function in superagers is essential for understanding "successful aging." Evidence suggests that the gut microbiome plays a key role in brain function, forming a bidirectional communication network known as the microbiome-gut-brain axis. Alterations in the gut microbiome have been linked to cognitive aging markers such as oxidative stress and inflammation. This study aims to investigate the unique patterns of the gut microbiome in superagers and to develop machine learning-based predictive models to differentiate superagers from typical agers.

Methods

We recruited 161 cognitively unimpaired, community-dwelling volunteers aged 60 years or from dementia prevention centers in Seoul, South Korea. After applying inclusion and exclusion criteria, 115 participants were included in the study. Following the removal of microbiome data outliers, 102 participants, comprising 57 superagers and 45 typical agers, were finally analyzed. Superagers were defined based on memory performance at or above average normative values of middle-aged adults. Gut microbiome data were collected from stool samples, and microbial DNA was extracted and sequenced. Relative abundances of bacterial genera were used as features for model development. We employed the LightGBM algorithm to build predictive models and utilized SHAP analysis for feature importance and interpretability.

Results

The predictive model achieved an AUC of 0.832 and accuracy of 0.764 in the training dataset, and an AUC of 0.861 and accuracy of 0.762 in the test dataset. Significant microbiome features for distinguishing superagers included Alistipes, PAC001137_g, PAC001138_g, Leuconostoc, and PAC001115_g. SHAP analysis revealed that higher abundances of certain genera, such as PAC001138_g and PAC001115_g, positively influenced the likelihood of being classified as superagers.

Conclusion

Our findings demonstrate the machine learning-based predictive models using gut-microbiome features can differentiate superagers from typical agers with a reasonable performance.

Efficacy and safety of Bacteroides fragilis BF839 for pediatric autism spectrum disorder: a randomized clinical trial

Background

The clinical utility of Bacteroides fragilis in treating autism spectrum disorder (ASD) remains unclear. Therefore, this randomized, double-blind, placebo-controlled study aimed to explore the therapeutic effects and safety of B. fragilis BF839 in the treatment of pediatric ASD.

Methods

We examined 60 children aged 2-10 years diagnosed with ASD, and participants received either BF839 powder (10 g/bar with ≥106 CFU/bar of viable bacteria, two bars/day) or placebo for 16 weeks. The primary outcomes was Autism Behavior Checklist (ABC) score. The secondary outcomes were Childhood Autism Rating Scale (CARS), Social Responsiveness Scale (SRS), Normal Development of Social Skills from Infants to Junior High School Children (S-M), Gastrointestinal Symptom Rating Scale (GSRS) scores, and fecal microbiome composition. Assessments were performed on day 0 and at weeks 8 and 16.

Results

Compared with the placebo group, the BF839 group showed significant improvement in the ABC body and object use scores at week 16, which was more pronounced in children with ASD aged <4 years. Among children with a baseline CARS score ≥30, the BF839 group showed significant improvements at week 16 in the ABC total score, ABC body and object use score, CARS score, and GSRS score compared to the placebo group. Only two patients (6.67%) in the BF839 group experienced mild diarrhea. Compared with baseline and placebo group levels, the BF839 group showed a significant post-intervention increase in abundance of bifidobacteria and change in the metabolic function of neuroactive compounds encoded by intestinal microorganisms.

Conclusion

BF839 significantly and safely improved abnormal behavior and gastrointestinal symptoms in children with ASD.

Protective effects of oyster polypeptide on cyclophosphamide-induced immunosuppressed rats

BACKGROUND

Oyster polypeptide (OP) is a mixture of oligopeptides extracted from oysters through enzyme lysis, separation, and purification. It is associated with immunomodulatory effects, but the underlying mechanisms are not known. This study therefore combined proton nuclear magnetic resonance (1H-NMR) urinary metabolomics and 16S rRNA gene sequencing of the gut microbiome to determine the immunoprotective mechanisms of OP in rats subjected to cyclophosphamide-induced immunosuppression.

RESULTS

Oyster polypeptide restored the body weight and the structure of spleen and thymus in rats with cyclophosphamide-induced immunosuppression. It upregulated the levels of white blood cells (WBCs), hemoglobin (HGB), platelets (PLT), red blood cells (RBCs), immunoglobulin G (IgG), immunoglobulin M (IgM), cytokines such as interleukin‑6 (IL-6) and tumor necrosis factor-α (TNF-α), and increased the numbers of CD3+ and CD4+ T cells in the immunosuppressed rats. The 1H-NMR metabolomics results showed that OP significantly reversed the levels of ten metabolites in urine, including 2-oxoglutarate, citrate, dimethylamine, taurine, N-phenylacetylglycine, alanine, betaine, creatinine, uracil, and benzoate. The 16S rRNA gene sequencing results showed that OP restored the gut microbiome homeostasis by increasing the abundance of beneficial bacteria and reducing the abundance of pathogenic bacteria. Finally, a combination of metabolomics and microbiomics found that the metabolism of taurine and hypotaurine, and the metabolism of alanine, aspartate, and glutamate were disturbed, but these metabolic pathways were restored by OP.

CONCLUSION

This study demonstrated that OP had immunoprotective effects in rats with cyclophosphamide-induced immunosuppression by restoring key metabolic pathways and the gut microbiome homeostasis. Our findings provide a framework for further research into the immunoregulatory mechanisms of OP and its potential use in drugs and nutritional supplements. © 2024 Society of Chemical Industry.

Neurodevelopmental implications of COVID-19-induced gut microbiome dysbiosis in pregnant women

The global public health emergency of COVID-19 in January 2020 prompted a surge in research focusing on the pathogenesis and clinical manifestations of the virus. While numerous reports have been published on the acute effects of COVID-19 infection, the review explores the multifaceted long-term implications of COVID-19, with a particular focus on severe maternal COVID-19 infection, gut microbiome dysbiosis, and neurodevelopmental disorders in offspring. Severe COVID-19 infection has been associated with heightened immune system activation and gastrointestinal symptoms. Severe COVID-19 may also result in gut microbiome dysbiosis and a compromised intestinal mucosal barrier, often referred to as 'leaky gut'. Increased gut permeability facilitates the passage of inflammatory cytokines, originating from the inflamed intestinal mucosa and gut, into the bloodstream, thereby influencing fetal development during pregnancy and potentially elevating the risk of neurodevelopmental disorders such as autism and schizophrenia. The current review discusses the role of cytokine signaling molecules, microglia, and synaptic pruning, highlighting their potential involvement in the pathogenesis of neurodevelopmental disorders following maternal COVID-19 infection. Additionally, this review addresses the potential of probiotic interventions to mitigate gut dysbiosis and inflammatory responses associated with COVID-19, offering avenues for future research in optimizing maternal and fetal health outcomes.

A comparative study on dietary diversity and gut microbial diversity in children with autism spectrum disorder, attention-deficit hyperactivity disorder, their neurotypical siblings, and non-related neurotypical volunteers: a cross-sectional study

BACKGROUND

Previous research has shown a significant link between gut microbiota in children with autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). However, much remains unknown because of the heterogeneity of disorders and the potential confounders such as dietary patterns and control group variations.

METHODS

Children aged 6-12 years who had been clinically diagnosed with ASD and/or ADHD, their unaffected neurotypical siblings, and non-related neurotypical volunteers were recruited cross-sectionally. The ASD diagnosis was confirmed using the Autism Diagnostic Observation Schedule-2 (ADOS-2) in all patients, including those with ADHD. Standardized DNA extraction and sequencing methods were used to compare gut microbial alpha-diversity among the groups. Dietary diversity was calculated from a standardized dietary questionnaire form. We compared the difference in gut microbiome between patients with ASD and/or ADHD with neurotypical siblings and non-related neurotypical controls.

RESULTS

Ninety-eight subjects were included in the study (18 with ASD, 19 with ADHD, 20 with both ASD and ADHD, 13 neurotypical siblings, and 28 non-related neurotypical controls). The alpha-diversity indices, such as Chao 1 and Shannon index, showed a significant difference between the groups in a Linear mixed-effect model (F(4, 93) = 4.539, p = .02), (F(4, 93) = 3.185, p = .017), respectively. In a post-hoc pairwise comparison, patients with ASD had lower alpha-diversity compared with non-related controls after Bonferroni correction. Dietary diversity shown in Shannon index did not differ among the groups (F(4, 84) = 1.494, p = .211).

CONCLUSIONS

Our study indicates disorder-specific microbiome differences in patients with ASD. In future research on gut microbiota in neurodevelopmental disorders, it is necessary to consider the impact of ASD and ADHD co-occurrence, and strictly control for background information such as diet, to elucidate the gut-microbiota interaction in ASD and ADHD for exploring the potential of therapeutic interventions.

Psychobiotic Properties of Lactiplantibacillus plantarum in Neurodegenerative Diseases

Neurodegenerative disorders are the main cause of cognitive and physical disabilities, affect millions of people worldwide, and their incidence is on the rise. Emerging evidence pinpoints a disturbance of the communication of the gut-brain axis, and in particular to gut microbial dysbiosis, as one of the contributors to the pathogenesis of these diseases. In fact, dysbiosis has been associated with neuro-inflammatory processes, hyperactivation of the neuronal immune system, impaired cognitive functions, aging, depression, sleeping disorders, and anxiety. With the rapid advance in metagenomics, metabolomics, and big data analysis, together with a multidisciplinary approach, a new horizon has just emerged in the fields of translational neurodegenerative disease. In fact, recent studies focusing on taxonomic profiling and leaky gut in the pathogenesis of neurodegenerative disorders are not only shedding light on an overlooked field but are also creating opportunities for biomarker discovery and development of new therapeutic and adjuvant strategies to treat these disorders. Lactiplantibacillus plantarum (LBP) strains are emerging as promising psychobiotics for the treatment of these diseases. In fact, LBP strains are able to promote eubiosis, increase the enrichment of bacteria producing beneficial metabolites such as short-chain fatty acids, boost the production of neurotransmitters, and support the homeostasis of the gut-brain axis. In this review, we summarize the current knowledge on the role of the gut microbiota in the pathogenesis of neurodegenerative disorders with a particular focus on the benefits of LBP strains in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, autism, anxiety, and depression.

The brain-gut axis: communication mechanisms and the role of the microbiome as a neuroprotective factor in the development of neurodegenerative diseases: A literature overview

The study of the brain-gut axis and its impact on cognitive function and in the development of neurodegenerative diseases is a very timely topic of interest to researchers. This review summarizes information on the basic mechanisms of gut-brain communication. We then discuss the roles of the gut microbiome as a neuroprotective factor in neurodegeneration. The gut microbiota is extremely important in maintaining the body's homeostasis, shaping the human immune system and the proper functioning of the brain. The intestinal microflora affects the processes of neuroplasticity, synaptogenesis, and neuronal regeneration. This review aims to explain changes in the composition of the bacterial population of the intestinal microflora among patients with Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Abnormalities in gut microflora composition are also noted in stress, depression, or autism spectrum development. New observations on psychobiotic supplementation in alleviating the symptoms of neurodegenerative diseases are also presented.

Gut Microbiota and Autism Spectrum Disorder: A Neuroinflammatory Mediated Mechanism of Pathogenesis?

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social communication and behavior, frequently accompanied by restricted and repetitive patterns of interests or activities. The gut microbiota has been implicated in the etiology of ASD due to its impact on the bidirectional communication pathway known as the gut-brain axis. However, the precise involvement of the gut microbiota in the causation of ASD is unclear. This study critically examines recent evidence to rationalize a probable mechanism in which gut microbiota symbiosis can induce neuroinflammation through intermediator cytokines and metabolites. To develop ASD, loss of the integrity of the intestinal barrier, activation of microglia, and dysregulation of neurotransmitters are caused by neural inflammatory factors. It has emphasized the potential role of neuroinflammatory intermediates linked to gut microbiota alterations in individuals with ASD. Specifically, cytokines like brain-derived neurotrophic factor, calprotectin, eotaxin, and some metabolites and microRNAs have been considered etiological biomarkers. We have also overviewed how probiotic trials may be used as a therapeutic strategy in ASD to reestablish a healthy balance in the gut microbiota. Evidence indicates neuroinflammation induced by dysregulated gut microbiota in ASD, yet there is little clarity based on analysis of the circulating immune profile. It deems the repair of microbiota load would lower inflammatory chaos in the GI tract, correct neuroinflammatory mediators, and modulate the neurotransmitters to attenuate autism. The interaction between the gut and the brain, along with alterations in microbiota and neuroinflammatory biomarkers, serves as a foundational background for understanding the etiology, diagnosis, prognosis, and treatment of autism spectrum disorder.

Contributions of Artificial Intelligence to Analysis of Gut Microbiota in Autism Spectrum Disorder: A Systematic Review

BACKGROUND

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder whose etiology is not known today, but everything indicates that it is multifactorial. For example, genetic and epigenetic factors seem to be involved in the etiology of ASD. In recent years, there has been an increase in studies on the implications of gut microbiota (GM) on the behavior of children with ASD given that dysbiosis in GM may trigger the onset, development and progression of ASD through the microbiota-gut-brain axis. At the same time, significant progress has occurred in the development of artificial intelligence (AI).

METHODS

The aim of the present study was to perform a systematic review of articles using AI to analyze GM in individuals with ASD. In line with the PRISMA model, 12 articles using AI to analyze GM in ASD were selected.

RESULTS

Outcomes reveal that the majority of relevant studies on this topic have been conducted in China (33.3%) and Italy (25%), followed by the Netherlands (16.6%), Mexico (16.6%) and South Korea (8.3%).

CONCLUSIONS

The bacteria Bifidobacterium is the most relevant biomarker with regard to ASD. Although AI provides a very promising approach to data analysis, caution is needed to avoid the over-interpretation of preliminary findings. A first step must be taken to analyze GM in a representative general population and ASD samples in order to obtain a GM standard according to age, sex and country. Thus, more work is required to bridge the gap between AI in mental health research and clinical care in ASD.

An In Vivo Model of Propionic Acid-Rich Diet-Induced Gliosis and Neuro-Inflammation in Mice (FVB/N-Tg(GFAPGFP)14Mes/J): A Potential Link to Autism Spectrum Disorder

Evidence shows that Autism Spectrum Disorder (ASD) stems from an interplay of genetic and environmental factors, which may include propionic acid (PPA), a microbial byproduct and food preservative. We previously reported that in vitro treatment of neural stem cells with PPA leads to gliosis and neuroinflammation. In this study, mice were exposed ad libitum to a PPA-rich diet for four weeks before mating. The same diet was maintained through pregnancy and administered to the offspring after weaning. The brains of the offspring were studied at 1 and 5 months postpartum. Glial fibrillary acidic protein (astrocytic marker) was significantly increased (1.53 ± 0.56-fold at 1 M and 1.63 ± 0.49-fold at 5 M) in the PPA group brains. Tubulin IIIβ (neuronal marker) was significantly decreased in the 5 M group. IL-6 and TNF-α expression were increased in the brain of the PPA group (IL-6: 2.48 ± 1.25-fold at 5 M; TNF-α: 2.84 ± 1.16-fold at 1 M and 2.64 ± 1.42-fold, at 5 M), while IL-10 was decreased. GPR41 and p-Akt were increased, while PTEN (p-Akt inhibitor) was decreased in the PPA group. The data support the role of a PPA-rich diet in glia over-proliferation and neuro-inflammation mediated by the GPR41 receptor and PTEN/Akt pathway. These findings strongly support our earlier study on the role of PPA in ASD.

Harnessing the Gut Microbiome: To What Extent Can Pre-/Probiotics Alleviate Immune Activation in Autism Spectrum Disorder?

Children diagnosed with autism spectrum disorder (ASD) are at an increased risk of experiencing gastrointestinal (GI) discomfort, which has been linked to dysfunctions in the microbiome-gut-brain axis. The bidirectional communication between gut and brain plays a crucial role in the overall health of individuals, and alterations in the gut microbiome can contribute to immune activation and gut-brain dysfunction in ASD. Despite the limited and controversial results of pre-/probiotic applications in ASD, this review comprehensively maps the association between ASD clinical symptoms and specific bacterial taxa and evaluates the efficacy of pre-/probiotics in modulating microbiota composition, reducing inflammatory biomarkers, alleviating difficulties in GI distress, sleep problems, core and other ASD-associated symptoms, as well as relieving parental concerns, separately, in individuals with ASD. Beyond simply targeting core ASD symptoms, this review highlights the potential of pre-/probiotic supplementations as a strategy to modulate gut homeostasis and immune response, and to delineate the potential mechanisms by which its direct or mediating effects can alleviate gut-brain dysfunction and poor nutritional status in ASD management. Further well-designed randomized controlled trials are needed to strengthen the existing evidence and establish optimal protocols for the use of pre-/probiotics in the context of ASD.

Clostridium butyricum regulates intestinal barrier function via trek1 to improve behavioral abnormalities in mice with autism spectrum disorder

BACKGROUND

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder that has been found to be associated with dysregulation of gastrointestinal functions and gut microbial homeostasis (the so-called "gut-brain axis"). ASD is often accompanied by poor performances in social interaction and repetitive behaviors. Studies on the gut-brain axis provide novel insights and candidate targets for ASD therapeutics and diagnosis. Based on the ASD mice model, this work aims to reveal the mechanisms behind the interaction of intestinal barrier function and probiotics in ASD mouse models.

RESULTS

We found an altered intestinal barrier in both BTBR T+ Itpr3tf/J (BTBR) and valproic acid (VPA) mice, including increased intestinal permeability, decreased expression of intestinal tight junction proteins (claudin1, claudin3, and occludin), and increased levels of IL-6, TNF-α, and IFN-γ. Based on intestinal microbial alternation, C. butyricum can drive reduced expression of histone deacetylases 1 (HDAC1) and enhanced intestinal barrier function, significantly promoting behavioral abnormalities of ASD in BTBR mice. In parallel, we confirmed that C. butyricum was involved in the regulation of intestinal function by the Trek1 channel, indicating that it is a target of C. butyricum/butyric acid to improve intestinal barrier function in ASD mice.

CONCLUSIONS

Our finding provides solid evidence for the gut microbiota involved in ASD through the brain-gut axis. In addition, the probiotics C. butyricum hold promise to improve gut health and ameliorate behavioral abnormalities associated with ASD.

Unraveling the metabolomic architecture of autism in a large Danish population-based cohort

BACKGROUND

The prevalence of autism in Denmark has been increasing, reaching 1.65% among 10-year-old children, and similar trends are seen elsewhere. Although there are several factors associated with autism, including genetic, environmental, and prenatal factors, the molecular etiology of autism is largely unknown. Here, we use untargeted metabolomics to characterize the neonatal metabolome from dried blood spots collected shortly after birth.

METHODS

We analyze the metabolomic profiles of a subset of a large Danish population-based cohort (iPSYCH2015) consisting of over 1400 newborns, who later are diagnosed with autism and matching controls and in two Swedish population-based cohorts comprising over 7000 adult participants. Mass spectrometry analysis was performed by a timsTOF Pro operated in QTOF mode, using data-dependent acquisition. By applying an untargeted metabolomics approach, we could reproducibly measure over 800 metabolite features.

RESULTS

We detected underlying molecular perturbations across several metabolite classes that precede autism. In particular, the cyclic dipeptide cyclo-leucine-proline (FDR-adjusted p = 0.003) and the carnitine-related 5-aminovaleric acid betaine (5-AVAB) (FDR-adjusted p = 0.03), were associated with an increased probability for autism, independently of known prenatal and genetic risk factors. Analysis of genetic and dietary data in adults revealed that 5-AVAB was associated with increased habitual dietary intake of dairy (FDR-adjusted p < 0.05) and with variants near SLC22A4 and SLC22A5 (p < 5.0e - 8), coding for a transmembrane carnitine transporter protein involved in controlling intracellular carnitine levels.

CONCLUSIONS

Cyclo-leucine-proline and 5-AVAB are associated with future diagnosis of autism in Danish neonates, both representing novel early biomarkers for autism. 5-AVAB is potentially modifiable and may influence carnitine homeostasis.

Revealing the gut microbiome mystery: A meta-analysis revealing differences between individuals with autism spectrum disorder and neurotypical children

The brain-gut axis intricately links gut microbiota (GM) dysbiosis to the development or worsening of autism spectrum disorder (ASD). However, the precise GM composition in ASD and the effectiveness of probiotics are unclear. To address this, we performed a thorough meta-analysis of 28 studies spanning PubMed, PsycINFO, Web of Science, Scopus, and MEDLINE, involving 1,256 children with ASD and 1042 neurotypical children, up to February 2024. Using Revman 5.3, we analyzed the relative abundance of 8 phyla and 64 genera. While individuals with ASD did not exhibit significant differences in included phyla, they exhibited elevated levels of Parabacteroides, Anaerostipes, Faecalibacterium, Clostridium, Dorea, Phascolarctobacterium, Lachnoclostridium, Catenibacterium, and Collinsella along with reduced percentages of Barnesiella, Odoribacter, Paraprevotella, Blautia, Turicibacter, Lachnospira, Pseudomonas, Parasutterella, Haemophilus, and Bifidobacterium. Notably, discrepancies in Faecalibacterium, Clostridium, Dorea, Phascolarctobacterium, Catenibacterium, Odoribacter, and Bifidobacterium persisted even upon systematic exclusion of individual studies. Consequently, the GM of individuals with ASD demonstrates an imbalance, with potential increases or decreases in both beneficial and harmful bacteria. Therefore, personalized probiotic interventions tailored to ASD specifics are imperative, rather than a one-size-fits-all approach.

The Microbiome in Child and Adolescent Psychiatry

Recent research has increasingly emphasized the function of the microbiome in human health. The gut microbiome is essential for digesting food and seems to play a vital role in mental health as well. This review briefly overviews the gut microbiome and its interplay with the central nervous system. We then summarize some of the latest findings on the possible role of the microbiome in psychiatric disorders in children and adolescents. In particular, we focus on autism spectrum disorder, attention-deficit/hyperactivity disorder, anorexia nervosa, bipolar disorder, and major depressive disorder. Although the role of microbiota in mental development and health still needs to be researched intensively, it has become increasingly apparent that the impact of microbiota must be considered to better understand psychiatric disorders.

Neurodevelopmental Disorders Associated with Gut Microbiome Dysbiosis in Children

The formation of the human gut microbiome initiates in utero, and its maturation is established during the first 2-3 years of life. Numerous factors alter the composition of the gut microbiome and its functions, including mode of delivery, early onset of breastfeeding, exposure to antibiotics and chemicals, and maternal stress, among others. The gut microbiome-brain axis refers to the interconnection of biological networks that allow bidirectional communication between the gut microbiome and the brain, involving the nervous, endocrine, and immune systems. Evidence suggests that the gut microbiome and its metabolic byproducts are actively implicated in the regulation of the early brain development. Any disturbance during this stage may adversely affect brain functions, resulting in a variety of neurodevelopmental disorders (NDDs). In the present study, we reviewed recent evidence regarding the impact of the gut microbiome on early brain development, alongside its correlation with significant NDDs, such as autism spectrum disorder, attention-deficit/hyperactivity disorder, Tourette syndrome, cerebral palsy, fetal alcohol spectrum disorders, and genetic NDDs (Rett, Down, Angelman, and Turner syndromes). Understanding changes in the gut microbiome in NDDs may provide new chances for their treatment in the future.

Are Infants and Children at Risk of Adverse Health Effects from Dietary Deoxynivalenol Exposure? An Integrative Review

Deoxynivalenol (DON) is a foodborne mycotoxin produced by Fusarium molds that commonly infect cereal grains. It is a potent protein synthesis inhibitor that can significantly impact humans' gastrointestinal, immune, and nervous systems and can alter the microbiome landscape. Low-dose, chronic exposure to DON has been found to stimulate the immune system, inhibit protein synthesis, and cause appetite suppression, potentially leading to growth failure in children. At higher doses, DON has been shown to cause immune suppression, nausea, vomiting, abdominal pain, headache, diarrhea, gastroenteritis, the malabsorption of nutrients, intestinal hemorrhaging, dizziness, and fever. A provisional maximum tolerable daily intake (PMTDI) limit of 1 µg/kg/body weight has been established to protect humans, underscoring the potential health risks associated with DON intake. While the adverse effects of dietary DON exposure have been established, healthcare communities have not adequately investigated or addressed this threat to child health, possibly due to the assumption that current regulatory exposure limits protect the public appropriately. This integrative review investigated whether current dietary DON exposure rates in infants and children regularly exceed PMTDI limits, placing them at risk of negative health effects. On a global scale, the routine contamination of cereal grains, bakery products, pasta, and human milk with DON could lead to intake levels above PMTDI limits. Furthermore, evidence suggests that other food commodities, such as soy, coffee, tea, dried spices, nuts, certain seed oils, animal milk, and various water reservoirs, can be intermittently contaminated, further amplifying the scope of the issue. Better mitigation strategies and global measures are needed to safeguard vulnerable youth from this harmful toxicant.

Kismet/CHD7/CHD8 affects gut microbiota, mechanics, and the gut-brain axis in Drosophila melanogaster

The gut microbiome affects brain and neuronal development and may contribute to the pathophysiology of neurodevelopmental disorders. However, it is unclear how risk genes associated with such disorders affect gut physiology in a manner that could impact microbial colonization and how the mechanical properties of the gut tissue might play a role in gut-brain bidirectional communication. To address this, we used Drosophila melanogaster with a null mutation in the gene kismet, an ortholog of chromodomain helicase DNA-binding protein (CHD) family members CHD7 and CHD8. In humans, these are risk genes for neurodevelopmental disorders with co-occurring gastrointestinal symptoms. We found that kismet mutant flies have a significant increase in gastrointestinal transit time, indicating the functional homology of kismet with CHD7/CHD8 in vertebrates. Rheological characterization of dissected gut tissue revealed significant changes in the mechanics of kismet mutant gut elasticity, strain stiffening behavior, and tensile strength. Using 16S rRNA metagenomic sequencing, we also found that kismet mutants have reduced diversity and abundance of gut microbiota at every taxonomic level. To investigate the connection between the gut microbiome and behavior, we depleted gut microbiota in kismet mutant and control flies and quantified the flies' courtship behavior. Depletion of gut microbiota rescued courtship defects of kismet mutant flies, indicating a connection between gut microbiota and behavior. In striking contrast, depletion of the gut microbiome in the control strain reduced courtship activity, demonstrating that antibiotic treatment can have differential impacts on behavior and may depend on the status of microbial dysbiosis in the gut prior to depletion. We propose that Kismet influences multiple gastrointestinal phenotypes that contribute to the gut-microbiome-brain axis to influence behavior. We also suggest that gut tissue mechanics should be considered as an element in the gut-brain communication loop, both influenced by and potentially influencing the gut microbiome and neurodevelopment.

Comprehensive Analysis of Gut Microbiota Composition and Functional Metabolism in Children with Autism Spectrum Disorder and Neurotypical Children: Implications for Sex-Based Differences and Metabolic Dysregulation

This study aimed to investigate the gut microbiota composition in children with autism spectrum disorder (ASD) compared to neurotypical (NT) children, with a focus on identifying potential differences in gut bacteria between these groups. The microbiota was analyzed through the massive sequencing of region V3-V4 of the 16S RNA gene, utilizing DNA extracted from stool samples of participants. Our findings revealed no significant differences in the dominant bacterial phyla (Firmicutes, Bacteroidota, Actinobacteria, Proteobacteria, Verrucomicrobiota) between the ASD and NT groups. However, at the genus level, notable disparities were observed in the abundance of Blautia, Prevotella, Clostridium XI, and Clostridium XVIII, all of which have been previously associated with ASD. Furthermore, a sex-based analysis unveiled additional discrepancies in gut microbiota composition. Specifically, three genera (Megamonas, Oscilibacter, Acidaminococcus) exhibited variations between male and female groups in both ASD and NT cohorts. Particularly noteworthy was the exclusive presence of Megamonas in females with ASD. Analysis of predicted metabolic pathways suggested an enrichment of pathways related to amine and polyamine degradation, as well as amino acid degradation in the ASD group. Conversely, pathways implicated in carbohydrate biosynthesis, degradation, and fermentation were found to be underrepresented. Despite the limitations of our study, including a relatively small sample size (30 ASD and 31 NT children) and the utilization of predicted metabolic pathways derived from 16S RNA gene analysis rather than metagenome sequencing, our findings contribute to the growing body of evidence suggesting a potential association between gut microbiota composition and ASD. Future research endeavors should focus on validating these findings with larger sample sizes and exploring the functional significance of these microbial differences in ASD. Additionally, there is a critical need for further investigations to elucidate sex differences in gut microbiota composition and their potential implications for ASD pathology and treatment.

Periodontal Inflammation and Dysbiosis Relate to Microbial Changes in the Gut

Periodontal disease (PerioD) is a chronic inflammatory disease of dysbiotic etiology. Animal models and few human data showed a relationship between oral bacteria and gut dysbiosis. However, the effect of periodontal inflammation and subgingival dysbiosis on the gut is unknown. We hypothesized that periodontal inflammation and its associated subgingival dysbiosis contribute to gut dysbiosis even in subjects free of known gut disorders. We evaluated and compared elderly subjects with Low and High periodontal inflammation (assessed by Periodontal Inflamed Surface Area (PISA)) for stool and subgingival derived bacteria (assayed by 16S rRNA sequencing). The associations between PISA/subgingival dysbiosis and gut dysbiosis and bacteria known to produce short-chain fatty acid (SCFA) were assessed. LEfSe analysis showed that, in Low PISA, species belonging to Lactobacillus, Roseburia, and Ruminococcus taxa and Lactobacillus zeae were enriched, while species belonging to Coprococcus, Clostridiales, and Atopobium were enriched in High PISA. Regression analyses showed that PISA associated with indicators of dysbiosis in the gut mainly reduced abundance of SCFA producing bacteria (Radj = -0.38, p = 0.03). Subgingival bacterial dysbiosis also associated with reduced levels of gut SCFA producing bacteria (Radj = -0.58, p = 0.002). These results suggest that periodontal inflammation and subgingival microbiota contribute to gut bacterial changes.

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.

Dietary flavonoids modulate the gut microbiota: A new perspective on improving autism spectrum disorder through the gut-brain axis

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with an unknown etiology. It is associated with various factors and causes great inconvenience to the patient's life. The gut-brain axis (GBA), which serves as a bidirectional information channel for exchanging information between the gut microbiota and the brain, is vital in studying many neurodegenerative diseases. Dietary flavonoids provide anti-inflammatory and antioxidant benefits, as well as regulating the structure and function of the gut microbiota. The occurrence and development of ASD are associated with dysbiosis of the gut microbiota. Modulation of gut microbiota can effectively improve the severity of ASD. This paper reviews the links between gut microbiota, flavonoids, and ASD, focusing on the mechanism of dietary flavonoids in regulating ASD through the GBA.

Gut microbiome in the Graves' disease: Comparison before and after anti-thyroid drug treatment

While several studies have proposed a connection between the gut microbiome and the pathogenesis of Graves's disease (GD), there has been a lack of reports on alteration in microbiome following using anti-thyroid drug treatment (ATD) to treat GD. Stool samples were collected from newly diagnosed GD patients provided at baseline and after 6 months of ATD treatment. The analysis focused on investigating the association between the changes in the gut microbiome and parameter including thyroid function, thyroid-related antibodies, and the symptom used to assess hyperthyroidism before and after treatment. A healthy control (HC) group consisting of data from 230 healthy subjects (110 males and 120 females) sourced from the open EMBL Nucleotide Sequence Database was included. Twenty-nine GD patients (14 males and 15 females) were enrolled. The analysis revealed a significant reduction of alpha diversity in GD patients. However, after ATD treatment, alpha diversity exhibited a significant increase, restored to levels comparable to the HC levels. Additionally, GD patients displayed lower levels of Firmicutes and higher levels of Bacteroidota. Following treatment, there was an increased in Firmicutes and a decrease in Bacteroidota, resembling levels found in the HC levels. The symptoms of hyperthyroidism were negatively associated with Firmicutes and positively associated with Bacteroidota. GD had significantly lower levels of Roseburia, Lachnospiraceaea, Sutterella, Escherichia-shigella, Parasuterella, Akkermansia, and Phascolarctobacterium compared to HC (all p < 0.05). Post-treatment, Subdoligranulum increased (p = 0.010), while Veillonella and Christensenellaceaea R-7 group decreased (p = 0.023, p = 0.029, respectively). Anaerostipes showed a significant association with both higher smoking pack years and TSHR-Ab levels, with greater abundantce observed in smokers among GD (p = 0.16). Although reduced ratio of Firmicutes/Bacteroidetes was evident in GD, this ratio recovered after treatment. This study postulates the involvement of the gut microbiome in the pathogenesis of GD, suggesting potential restoration after treatment.

Deciphering Microbial Shifts in the Gut and Lung Microbiomes of COVID-19 Patients

COVID-19, caused by SARS-CoV-2, results in respiratory and cardiopulmonary infections. There is an urgent need to understand not just the pathogenic mechanisms of this disease but also its impact on the physiology of different organs and microbiomes. Multiple studies have reported the effects of COVID-19 on the gastrointestinal microbiota, such as promoting dysbiosis (imbalances in the microbiome) following the disease's progression. Deconstructing the dynamic changes in microbiome composition that are specifically correlated with COVID-19 patients remains a challenge. Motivated by this problem, we implemented a biomarker discovery pipeline to identify candidate microbes specific to COVID-19. This involved a meta-analysis of large-scale COVID-19 metagenomic data to decipher the impact of COVID-19 on the human gut and respiratory microbiomes. Metagenomic studies of the gut and respiratory microbiomes of COVID-19 patients and of microbiomes from other respiratory diseases with symptoms similar to or overlapping with COVID-19 revealed 1169 and 131 differentially abundant microbes in the human gut and respiratory microbiomes, respectively, that uniquely associate with COVID-19. Furthermore, by utilizing machine learning models (LASSO and XGBoost), we demonstrated the power of microbial features in separating COVID-19 samples from metagenomic samples representing other respiratory diseases and controls (healthy individuals), achieving an overall accuracy of over 80%. Overall, our study provides insights into the microbiome shifts occurring in COVID-19 patients, shining a new light on the compositional changes.

Exploring the gut microbiota-hippocampus-metabolites axis dysregulation in sepsis mice

Background

Sepsis is commonly associated with a sudden impairment of brain function, thus leading to significant rates of illness and mortality. The objective of this research was to integrate microbiome and metabolome to reveal the mechanism of microbiota-hippocampus-metabolites axis dysfunction in a mouse model of sepsis.

Methods

A mouse model of sepsis was established via cecal ligation and puncture. The potential associations between the composition of the gut microbiota and metabolites in the hippocampus of mice with sepsis were investigated by combining 16S ribosomal RNA gene sequencing and ultra-high-performance liquid chromatography tandem mass spectrometry.

Results

A total of 140 differential metabolites were identified in the hippocampal tissues of mice with sepsis when compared to those of control mice. These differential metabolites in mice with sepsis were not only associated with autophagy and serotonergic synapse, but also involved in the metabolism and synthesis of numerous amino acids. At the phylum level, the abundance of Bacteroidota was increased, while that of Firmicutes (Bacillota) was decreased in mice with sepsis. At the genus level, the abundance of Alistipes was increased, while that of Lachnospiraceae_NK4A136_group was decreased in mice with sepsis. The Firmicutes (Bacillota)/Bacteroidota (F/B) ratio was decreased in mice with sepsis when compared to that of control mice. Furthermore, the F/B ratio was positively correlated with 5'-methylthioadenosine, PC (18:3(9Z,12Z,15Z)/18:0) and curdione, and negatively correlated with indoxylsulfuric acid, corticosterone, kynurenine and ornithine.

Conclusion

Analysis revealed a reduction in the F/B ratio in mice with sepsis, thus contributing to the disturbance of 5'-methylthioadenosine, curdione, PC (18:3(9Z,12Z,15Z)/18:0), corticosterone, ornithine, indoxylsulfuric acid and kynurenine; eventually, these changes led to hippocampus dysfunction. Our findings provide a new direction for the management of sepsis-induced hippocampus dysfunction.

The gut-brain-axis: A positive relationship between gut microbial dysbiosis and glioblastoma brain tumour

The glioblastoma brain tumour (GBM) stands out as the most aggressive and resistant-to-treatment malignancy. Nevertheless, the gut-brain connection plays a pivotal role in influencing the growth and activation of the central nervous system. In this particular investigation, we aimed to assess and characterize the gut microbial ecosystem in GBM patients, both quantitatively and qualitatively. We collected faecal samples from 15 healthy volunteers and 25 GBM patients. To delve into the microbial content, we employed PCR-DGGE, targeting the V3 region of the 16S rRNA gene, and conducted qPCR to measure the levels of crucial intestinal bacteria. For a more in-depth analysis, high-throughput sequencing was performed on a selection of 20 random faecal samples (10 from healthy individuals and 10 from GBM patients), targeting the V3+V4 region of the 16S rRNA gene. Our findings from examining the richness and diversity of the gut microbiota unveiled that GBM patients exhibited significantly higher microbial diversity compared to healthy individuals. At the phylum level, Proteobacteria saw a significant increase, while Firmicutes experienced a noteworthy decrease in the GBM group. Moving down to the family level, we observed significantly elevated levels of Enterobacteriaceae, Bacteroidaceae, and Lachnospiraceae in GBM patients, while levels of Veillonellaceae, Rikenellaceae, and Prevotellaceae were notably lower. Delving into genera statistics, we noted a substantial increase in the abundance of Parasutterella, Escherichia-Shigella, and Bacteroides, alongside significantly lower levels of Ruminococcus 2, Faecalibacterium, and Prevotella_9 in the GBM group compared to the control group. Furthermore, when examining specific species, we found a significant increase in Bacteroides vulgatus and Escherichia coli in the GBM group. These observations collectively indicate a marked dysbiosis in the gut microbial composition of GBM patients. Additionally, the GBM group exhibited notably higher levels of alpha diversity when compared to the control group. This increase in diversity suggests a significant bacterial overgrowth in the gut of GBM patients in contrast to the controls. As a result, this research opens up potential avenues to gain a better understanding of the underlying mechanisms, pathways, and potential treatments for GBM, stemming from the significant implications of gut microbial dysbiosis in these patients.

Effects and microbiota changes following oral lyophilized fecal microbiota transplantation in children with autism spectrum disorder

Background and purpose

Autism spectrum disorder (ASD) is a group of heterogeneous neurodevelopmental disorders that is characterized by core features in social communication impairment and restricted, repetitive sensory-motor behaviors. This study aimed to further investigate the utilization of fecal microbiota transplantation (FMT) in children with ASD, both with and without gastrointestinal (GI) symptoms, evaluate the effect of FMT and analyze the alterations in bacterial and fungal composition within the gut microbiota.

Methods

A total of 38 children diagnosed with ASD participated in the study and underwent oral lyophilized FMT treatment. The dosage of the FMT treatment was determined based on a ratio of 1 g of donor stool per 1 kg of recipient body weight, with a frequency of once every 4 weeks for a total of 12 weeks. In addition, 30 healthy controls (HC) were included in the analysis. The clinical efficacy of FMT was evaluated, while the composition of fecal bacteria and fungi was determined using 16S rRNA and ITS gene sequencing methods.

Results

Median age of the 38 children with ASD was 7 years. Among these children, 84.2% (32 of 38) were boys and 81.6% (31 of 38) exhibited GI symptoms, with indigestion, constipation and diarrhea being the most common symptoms. Sample collections and assessments were conducted at baseline (week 0), post-treatment (week 12) and follow-up (week 20). At the end of the follow-up phase after FMT treatment, the autism behavior checklist (ABC) scores decreased by 23% from baseline, and there was a 10% reduction in scores on the childhood autism rating scale (CARS), a 6% reduction in scores on the social responsiveness scale (SRS) and a 10% reduction in scores on the sleep disturbance scale for children (SDSC). In addition, short-term adverse events observed included vomiting and fever in 2 participants, which were self-limiting and resolved within 24 h, and no long-term adverse events were observed. Although there was no significant difference in alpha and beta diversity in children with ASD before and after FMT therapy, the FMT treatment resulted in alterations in the relative abundances of various bacterial and fungal genera in the samples of ASD patients. Comparisons between children with ASD and healthy controls (HC) revealed statistically significant differences in microbial abundance before and after FMT. Blautia, Sellimonas, Saccharomycopsis and Cystobasidium were more abundant in children with ASD than in HC, while Dorea were less abundant. After FMT treatment, levels of Blautia, Sellimonas, Saccharomycopsis and Cystobasidium decreased, while levels of Dorea increased. Moreover, the increased abundances of Fusicatenibacter, Erysipelotrichaceae_UCG-003, Saccharomyces, Rhodotorula, Cutaneotrichosporon and Zygosaccharomyces were negatively correlated with the scores of ASD core symptoms.

Conclusions

Oral lyophilized FMT could improve GI and ASD related symptoms, as well as sleep disturbances, and alter the gut bacterial and fungal microbiota composition in children with ASD.

Clinical Trial Registration

Chinese Clinical Trial Registry, ChiCTR2200055943. Registered 28 January 2022, www.chictr.org.cn.

Gut Mycobiome in Atopic Dermatitis and in Overweight Young Children: A Prospective Cohort Study in Finland

Gut bacterial alterations have been previously linked to several non-communicable diseases in adults, while the association of mycobiome is not well understood in these diseases, especially in infants and children. Few studies have been conducted on the association between gut mycobiome and non-communicable diseases in children. We investigated gut mycobiome composition using 194 faecal samples collected at birth, 6 months after birth, and 18 months after birth in relation to atopic dermatitis (AD) and overweight diagnoses at the age of 18 or 36 months. The mycobiome exhibited distinct patterns, with Truncatella prevalent in the meconium samples of both overweight and non-overweight groups. Saccharomyces took precedence in overweight cases at 6 and 18 months, while Malassezia dominated non-overweight samples at 6 months. Saccharomyces emerged as a consistent high-abundance taxon across groups that had dermatitis and were overweight. We found a weak association between gut mycobiome and AD at birth and overweight at 18 months when using machine learning (ML) analyses. In ML, unidentified fungi, Alternaria, Rhodotorula, and Saccharomyces, were important for classifying AD, while Saccharomyces, Thelebolus, and Dothideomycetes were important for classifying overweight. Gut mycobiome might be associated with the development of AD and overweight in children.

A universal plasma metabolites-derived signature predicts cardiovascular disease risk in MAFLD

BACKGROUND

Metabolic associated fatty liver disease (MAFLD) is a novel concept proposed in 2020, which is more practical for identifying patients with fatty liver disease with high risk of disease progression. Fatty liver is a driver for extrahepatic complications, particularly cardiovascular diseases (CVD). Although the risk of CVD in MAFLD could be predicted by carotid ultrasound test, a very early stage prediction method before the formation of pathological damage is still lacking.

METHODS

Stool microbiomes and plasma metabolites were compared across 196 well-characterized participants encompassing normal controls, simple MAFLD patients, MAFLD patients with carotid artery pathological changes, and MAFLD patients with diagnosed coronary artery disease (CAD). 16S rDNA sequencing data and untargeted metabolomic profiles were interrogatively analyzed using differential abundance analysis and random forest (RF) machine learning algorithm to identify discriminatory gut microbiomes and metabolomic.

RESULTS

Characteristic microbial changes in MAFLD patients with CVD risk were represented by the increase of Clostridia and Firmicutes-to-Bacteroidetes ratios. Faecalibacterium was negatively correlated with mean-intima-media thickness (IMT), TC, and TG. Megamonas, Bacteroides, Parabacteroides, and Escherichia were positively correlated with the exacerbation of pathological indexes. MAFLD patients with CVD risk were characterized by the decrease of lithocholic acid taurine conjugate, and the increase of ethylvanillin propylene glycol acetal, both of which had close relationship with Ruminococcus and Gemmiger. Biotin l-sulfoxide had positive correlation with mean-IMT, TG, and weight. The general auxin pesticide beta-naphthoxyacetic acid and the food additive glucosyl steviol were both positively correlated with the increase of mean-IMT. The model combining the metabolite signatures with 9 clinical parameters accurately distinguished MAFLD with CVD risk in the proband and validation cohort. It was found that citral was the most important discriminative metabolite marker, which was validated by both in vitro and in vivo experiments.

CONCLUSIONS

Simple MAFLD patients and MAFLD patients with CVD risk had divergent gut microbes and plasma metabolites. The predictive model based on metabolites and 9 clinical parameters could effectively discriminate MAFLD patients with CVD risk at a very early stage.

Ascomycetes yeasts: The hidden part of human microbiome

The fungal component of the microbiota, the mycobiota, has been neglected for a long time due to its poor richness compared to bacteria. Limitations in fungal detection and taxonomic identification arise from using metagenomic approaches, often borrowed from bacteriome analyses. However, the relatively recent discoveries of the ability of fungi to modulate the host immune response and their involvement in human diseases have made mycobiota a fundamental component of the microbial communities inhabiting the human host, deserving some consideration in host-microbe interaction studies and in metagenomics. Here, we reviewed recent data on the identification of yeasts of the Ascomycota phylum across human body districts, focusing on the most representative genera, that is, Saccharomyces and Candida. Then, we explored the key factors involved in shaping the human mycobiota across the lifespan, ranging from host genetics to environment, diet, and lifestyle habits. Finally, we discussed the strengths and weaknesses of culture-dependent and independent methods for mycobiota characterization. Overall, there is still room for some improvements, especially regarding fungal-specific methodological approaches and bioinformatics challenges, which are still critical steps in mycobiota analysis, and to advance our knowledge on the role of the gut mycobiota in human health and disease. This article is categorized under: Immune System Diseases > Genetics/Genomics/Epigenetics Immune System Diseases > Environmental Factors Infectious Diseases > Environmental Factors.

Mutualistic interactions of lactate-producing lactobacilli and lactate-utilizing Veillonella dispar: Lactate and glutamate cross-feeding for the enhanced growth and short-chain fatty acid production

The human gut hosts numerous ecological niches for microbe-microbe and host-microbe interactions. Gut lactate homeostasis in humans is crucial and relies on various bacteria. Veillonella spp., gut lactate-utilizing bacteria, and lactate-producing bacteria were frequently co-isolated. A recent clinical trial has revealed that lactate-producing bacteria in humans cross-feed lactate to Veillonella spp.; however, their interspecies interaction mechanisms remain unclear. Veillonella dispar, an obligate anaerobe commonly found in the human gut and oral cavity, ferments lactate into acetate and propionate. In our study, we investigated the interaction between V. dispar ATCC 17748T and three representative phylogenetically distant strains of lactic acid bacteria, Lactobacillus acidophilus ATCC 4356T, Lacticaseibacillus paracasei subsp. paracasei ATCC 27216T, and Lactiplantibacillus plantarum ATCC 10241. Bacterial growth, viability, metabolism and gene level adaptations during bacterial interaction were examined. V. dispar exhibited the highest degree of mutualism with L. acidophilus. During co-culture of V. dispar with L. acidophilus, both bacteria exhibited enhanced growth and increased viability. V. dispar demonstrated an upregulation of amino acid biosynthesis pathways and the aspartate catabolic pathway. L. acidophilus also showed a considerable number of upregulated genes related to growth and lactate fermentation. Our results support that V. dispar is able to enhance the fermentative capability of L. acidophilus by presumably consuming the produced lactate, and that L. acidophilus cross-feed not only lactate, but also glutamate, to V. dispar during co-culture. The cross-fed glutamate enters the central carbon metabolism in V. dispar. These findings highlight an intricate metabolic relationship characterized by cross-feeding of lactate and glutamate in parallel with considerable gene regulation within both L. acidophilus (lactate-producing) and V. dispar (lactate-utilizing). The mechanisms of mutualistic interactions between a traditional probiotic bacterium and a potential next-generation probiotic bacterium were elucidated in the production of short-chain fatty acids.