Microbiome Depletion Research Articles

Quinazolinone Derivative MR2938 Protects DSS-Induced Barrier Dysfunction in Mice Through Regulating Gut Microbiota.

Background/Objectives: Ulcerative colitis (UC), a chronic inflammatory bowel disease (IBD), is characterized by colorectal immune infiltration and significant microbiota compositional changes. Gut microbiota homeostasis is necessary to maintain the healthy state of humans. MR2938, a quinazolin-4(3H)-one derivative derived from the marine natural product penipanoid C, alleviated DSS-induced colitis in a dose-dependent manner. Herein, we aimed to investigate the impact of MR2938 on the gut microbiota in dextran sodium sulfate (DSS)-induced colitis in mice and to elucidate the role of the gut microbiota in the therapeutic mechanism of MR2938 for alleviating colitis. Methods: Acute colitis was induced with DSS in mice. Mice were administered with 100 mg/kg or 50 mg/kg of MR2938. Cecal content was also preserved in liquid nitrogen and subsequently analyzed following 16S RNA sequencing. Antibiotic cocktail-induced microbiome depletion was performed to further investigate the relationship between MR2938 and gut microbiota. The inflammatory factor levels were performed by quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA). Alcian blue staining and immunofluorescence were used to estimate the intestinal barrier. Results: The 16S rRNA sequencing revealed microbiota modulation by MR2938. Compared with the model group, the 100 mg/kg MR2938 group was associated with higher abundances of Entercoccus and a lower abundance of Staphylococcus, while the 50 mg/kg MR2938 group was associated with higher abundances of Lactobacillus and a lower abundance of Staphylococcus. The antibiotic-mediated microbiota depletion experiments demonstrated that the gut microbiota primarily contributed to barrier function protection, with little impact on inflammatory factor levels during the MR2938 treatment. Conclusions: These findings suggest that intestinal flora play a crucial role in MR2938's therapeutic mechanism for alleviating colitis.

The Gut Microbiome Regulates the Psychomotor Effects and Context-Dependent Rewarding Responses to Cocaine in Germ-Free and Antibiotic-Treated Animal Models.

Cocaine use disorder remains a major global health concern, with growing evidence that the gut microbiome modulates drug-related behaviors. This study examines the microbiome's role in cocaine-induced psychomotor activation and context-dependent reward responses using germ-free (GF) and antibiotic-treated (ABX) models. In GF mice, the absence of a microbiome blunted cocaine-induced psychomotor activation (p = 0.013), which was restored after conventionalization. GF mice also showed reduced cocaine-conditioned place preference (CPP) (p = 0.002), which normalized after conventionalization. Dopaminergic function, critical for psychomotor responses and reward, was microbiome-dependent, with increased dopamine levels (p = 0.009) and normalized turnover ratios after conventionalization. In the ABX model, microbiome depletion reduced both cocaine-induced locomotion and CPP responses (p ≤ 0.009), further supporting the role of gut microbes in modulating psychomotor and reward behaviors. ABX-treated mice also showed significant declines in microbial diversity, shifts in bacterial structure, and dysregulation in metabolic, immune, and neurotransmitter pathways (p ≤ 0.0001), including alterations in short-chain fatty acids and gamma-aminobutyric acid metabolism. These findings highlight the gut microbiome's critical role in regulating cocaine's psychomotor and rewarding effects, offering insights into potential therapeutic strategies for cocaine use disorder.

Metabolic Profile of Gut Microbiota and Levels of Trefoil Factors in Adults with Different Metabolic Phenotypes of Obesity

Obesity is associated with changes in the gut microbiota, as well as increased permeability of the intestinal wall. In 130 non-obese volunteers, 57 patients with metabolically healthy obesity (MHO), and 76 patients with metabolically unhealthy obesity (MUHO), bacterial DNA was isolated from stool samples, and the 16S rRNA gene was sequenced. The metabolic profile of the microbiota predicted by PICRUSt2 (https://huttenhower.sph.harvard.edu/picrust/) was more altered in patients with MUHO than MHO. Obesity, especially MUHO, was accompanied by an increase in the ability of the gut microbiota to degrade energy substrates, produce energy through oxidative phosphorylation, synthesize water-soluble vitamins (B1, B6, B7), nucleotides, heme, aromatic amino acids, and protective structural components of cells. Such changes may be a consequence of the microbiota adaptation to the MUHO-specific conditions. Thus, a vicious circle is formed, when MUHO promotes the depletion of gut microbiome, and further degeneration of the latter contributes to the pathogenesis of metabolic disorders. The concentration of the trefoil factor family (TFF) in the serum of the participants was also determined. In MHO and MUHO patients, TFF2 and TFF3 levels were increased, but we did not find significant associations of these changes with the metabolic profile of the gut microbiota.

Microbiome depletion by broad-spectrum antibiotics does not influence demyelination and remyelination in cuprizone-treated mice.

Demyelination in the central nervous system (CNS) is a feature of various psychiatric and neurological disorders. Emerging evidence suggests that the gut-brain axis may play a crucial role in CNS demyelination. The cuprizone (CPZ) model, which involves the administration of CPZ-containing food pellets, is commonly used to study the effects of different compounds on CNS demyelination and subsequent remyelination. This study aimed to evaluate the impact of microbiome depletion, induced by an antibiotic cocktail (ABX), on demyelination in CPZ-treated mice and the subsequent remyelination following CPZ withdrawal. Our findings indicate that a chronic 4-week oral ABX regimen, administered both during and after a 6-week CPZ exposure, does not affect demyelination or remyelination in the brains of CPZ-treated mice. Specifically, ABX treatment for 2 weeks before and 2 weeks after CPZ exposure, in the final 4 weeks before sacrifice, and for 4 weeks post-CPZ withdrawal, did not significantly alter these processes compared to control mice receiving water instead of ABX. These results indicate that despite effective microbiome depletion, a 4-week oral ABX regimen does not influence demyelination or remyelination in the CPZ model. Thus, it is unlikely that gut microbiota depletion by ABX plays a significant role in these processes. However, further research is needed to fully understand the role of the host microbiome on CPZ-induced demyelination.

The depletion of gut microbiome impairs the beneficial effect of Gui-Shen-Wan in restoring mice ovarian function and associated protein expression of ovarian tissues.

Traditional Chinese Medicine (TCM), specifically Gui-Shen-Wan, has shown promise in restoring ovarian function among reproductive-age women who had impaired ovarian functions, yet the underlying mechanisms remain elusive. Recent studies highlight the pivotal role of the gut microbiome (GM) in mediating the therapeutic effects of TCM. However, it is unclear whetherthe GM contributes to Gui-Shen-Wan's therapeutic restoration of ovarian functions. This study employed a mouse model with cyclophosphamide-induced decreased ovarian function (P_T and P_AT groups) and a control group without modeling. The P_AT group received a 7-day course of oral antibiotics to deplete the GM prior to a 20-day Gui-Shen-Wan treatment regimen. Both P_T and P_AT mice exhibited prolonged metestrus/diestrus phases compared to controls (p<0.05), indicating menstrual disruption post-modeling. Following 20 days of Gui-Shen-Wan treatment, P_T mice showed a shorter metestrus/diestrus phase (4 days) compared to P_AT mice (5 days) (p<0.05). Notably, P_T mice had a higher number of normal follicles(primitive/primary/secondary/antral follicles) in their ovaries post-treatment (median 15) compared to P_AT mice (median 8.5). Proteome analysis revealed that ovarian proteins enriched in P_T mice were primarily associated with oxidative phosphorylation and DNA replication pathways, suggesting GM-mediated enhancement of these processes. This study underscores the pivotal role of the GM in the therapeutic benefits of Gui-Shen-Wan, highlighting the potential for microbiome-targeted interventions in promoting beneficial effects of Gui-Shen-Wan on the restoration of decreased ovarian functions.

The intestinal microbiome and Cetobacterium somerae inhibit viral infection through TLR2-type I IFN signaling axis in zebrafish

BackgroundEvidence has accumulated to demonstrate that intestinal microbiome can inhibit viral infection. However, our knowledge of the signaling pathways and identity of specific commensal microbes that mediate the antiviral response is limited. Zebrafish have emerged as a powerful animal model for study of vertebrate-microbiota interactions. Here, a rhabdoviral infection model in zebrafish allows us to investigate the modes of action of microbiome-mediated antiviral effect.ResultsWe observed that oral antibiotics-treated and germ-free zebrafish exhibited greater spring viremia of carp virus (SVCV) infection. Mechanistically, depletion of the intestinal microbiome alters TLR2-Myd88 signaling and blunts neutrophil response and type I interferon (IFN) antiviral innate immunity. Through 16S rRNA sequencing of the intestinal contents from control and antibiotic(s)-treated fish, we identified a single commensal bacterial species, Cetobacterium somerae, that can restore the TLR2- and neutrophil-dependent type I IFN response to restrict SVCV infection in gnotobiotic zebrafish. Furthermore, we found that C. somerae exopolysaccharides (CsEPS) was the effector molecule that engaged TLR2 to mediate the type I IFN-dependent antiviral function.ConclusionsTogether, our results suggest a conserved role of intestinal microbiome in regulating type I IFN antiviral response among vertebrates and reveal that the intestinal microbiome inhibits viral infection through a CsEPS-TLR2-type I IFN signaling axis in zebrafish.7E-apxbKV4cu6qTqgWcuKAVideo

Depletion of core microbiome forms the shared background against diverging dysbiosis patterns in Crohn’s disease and intestinal tuberculosis: insights from an integrated multi-cohort analysis

Background/aimsCrohn’s disease (CD) and intestinal tuberculosis (ITB) are gastrointestinal (GI) inflammatory disorders with overlapping clinical presentations but diverging etiologies. The study aims to decipher CD and ITB-associated gut dysbiosis signatures and identify disease-associated co-occurring modules to evaluate whether this dysbiosis signature is a disease-specific trait or is a shared feature across diseases of diverging etiologies.MethodsDisease-associated gut microbial modules were identified using statistical machine learning and co-abundance network analysis in controls, CD and ITB patients recruited as part of this study. Module reproducibility was reinvestigated through meta-network analysis encompassing >5400 bacteriomes and ~900 mycobiomes. Subsequently, >1600 Indian gut microbiomes were analyzed to identify a central-core gut microbiome of 46 taxa, whose abundances aided in the formulation of an India-specific Core Gut Microbiome Score (CGMS) to measure the degree of core retention.ResultsBoth diseases witness similar patterns of alterations in [alpha]-diversity, characterized by a significant reduction in gut bacterial (i.e., bacterial/archaeal) diversity and a concomitant increase in the fungal [alpha]-diversity. Specific bacterial taxa, along with the diverging mycobiome enabled distinction between the diseases. Co-abundance network analysis of these taxa, validated by integrated meta-network analysis, revealed a ‘disease-depleted’ module, consistent across multiple cohorts, with >75% of this module constituting the central-core Indian gut microbiome. CGMS robustly assessed the core-microbiome loss across different stages of gut inflammatory disorders, in Indian and international cohorts.ConclusionsWhile the disease-specific gain of detrimental bacteria forms an important component of gut dysbiosis, loss of the core microbiome is a shared phenomenon contributing to various GI disorders.

7964 Manipulation of the Gut Microbiome Using Antibiotics Is Associated With Sex-Specific Reductions in Systemic Testosterone Levels in Rats

Abstract Disclosure: G. Parodi: None. G. Leite: None. W. Morales: None. S.R. Weitsman: None. G.M. Barlow: None. M. Sanchez: None. M. Pimentel: None. M. Villanueva-Millan: None. M. Pimentel: None. R. Mathur: None. The gut microbiome has impacts on metabolic endocrine and reproductive functions. It is known that specific bacteria can impact host metabolism by synthesizing, secreting, and/or metabolizing sex-related hormones. However, the impacts of gut bacterial biosynthesis and/or metabolism of steroids on host metabolism and reproduction have not been fully addressed. In this study we challenged the gut microbiome of wild-type male and female rats with broad-spectrum antibiotics and examined the effects on circulating testosterone levels. Methods: Male (M) and female (F) Sprague-Dawley rats (8 weeks old) were housed with phytoestrogen-free bedding and received a phytoestrogen-free diet with water from glass bottles. Rats were given a combination of vancomycin (0.5g/L), ampicillin (1g/L), neomycin (1g/L), and metronidazole (1g/L) in their water for 8 days, and then returned to normal drinking water for another 13 days. Control rats were given normal water throughout the study. Serum and stool samples were collected before the start of antibiotics (baseline), on day 8 of antibiotics (AbxD8), and at 13 days post-removal of antibiotics (PAbxD13). Stool total DNA was extracted with the MagAttract PowerSoil DNA KF kit and quantified on a Qubit. Circulating testosterone levels were analyzed on a Luminex platform. Paired-ANOVA test was used to determine changes in testosterone levels in each group over time. Results: A total of 31 rats (M=16, F=15) received antibiotics, and 28 (M=14, F=14) were controls. Antibiotic exposure resulted in significant decreases in total stool DNA quantity in both male and female exposed rats relative to controls on AbxD8 (P&amp;lt;0.0001), which returned to baseline levels by PAbxD13. Antibiotic exposed male rats had a continuous decrease in testosterone levels throughout the timepoints collected (baseline: 5.78±2.74 ng/mL, AbxD8: 3.11±2.46 ng/mL, PAbxD13: 2.55±1.80 ng/mL, P=0.0027), however, in control male rats, circulating testosterone levels remained stable throughout the timepoints analyzed (baseline: 3.81±1.73 ng/mL, AbxD8: 3.72±1.12 ng/mL, PAbxD13: 3.92±3.38 ng/mL, P=0.49). There was no effect on circulating testosterone levels in female rats, with both groups, control and exposed, following the same cyclical pattern throughout the timepoints analyzed. Conclusions: Antibiotic depletion of the gut microbiome is associated with changes in systemic levels of testosterone in rats. These changes are sex-specific, and only detected in males. These results suggest a potential involvement of the gut microbiome in testosterone metabolism that is sex-specific. Presentation: 6/1/2024

7964 Manipulation of the Gut Microbiome Using Antibiotics Is Associated With Sex-Specific Reductions in Systemic Testosterone Levels in Rats

Abstract Disclosure: G. Parodi: None. G. Leite: None. W. Morales: None. S.R. Weitsman: None. G.M. Barlow: None. M. Sanchez: None. M. Pimentel: None. M. Villanueva-Millan: None. M. Pimentel: None. R. Mathur: None. The gut microbiome has impacts on metabolic endocrine and reproductive functions. It is known that specific bacteria can impact host metabolism by synthesizing, secreting, and/or metabolizing sex-related hormones. However, the impacts of gut bacterial biosynthesis and/or metabolism of steroids on host metabolism and reproduction have not been fully addressed. In this study we challenged the gut microbiome of wild-type male and female rats with broad-spectrum antibiotics and examined the effects on circulating testosterone levels. Methods: Male (M) and female (F) Sprague-Dawley rats (8 weeks old) were housed with phytoestrogen-free bedding and received a phytoestrogen-free diet with water from glass bottles. Rats were given a combination of vancomycin (0.5g/L), ampicillin (1g/L), neomycin (1g/L), and metronidazole (1g/L) in their water for 8 days, and then returned to normal drinking water for another 13 days. Control rats were given normal water throughout the study. Serum and stool samples were collected before the start of antibiotics (baseline), on day 8 of antibiotics (AbxD8), and at 13 days post-removal of antibiotics (PAbxD13). Stool total DNA was extracted with the MagAttract PowerSoil DNA KF kit and quantified on a Qubit. Circulating testosterone levels were analyzed on a Luminex platform. Paired-ANOVA test was used to determine changes in testosterone levels in each group over time. Results: A total of 31 rats (M=16, F=15) received antibiotics, and 28 (M=14, F=14) were controls. Antibiotic exposure resulted in significant decreases in total stool DNA quantity in both male and female exposed rats relative to controls on AbxD8 (P&amp;lt;0.0001), which returned to baseline levels by PAbxD13. Antibiotic exposed male rats had a continuous decrease in testosterone levels throughout the timepoints collected (baseline: 5.78±2.74 ng/mL, AbxD8: 3.11±2.46 ng/mL, PAbxD13: 2.55±1.80 ng/mL, P=0.0027), however, in control male rats, circulating testosterone levels remained stable throughout the timepoints analyzed (baseline: 3.81±1.73 ng/mL, AbxD8: 3.72±1.12 ng/mL, PAbxD13: 3.92±3.38 ng/mL, P=0.49). There was no effect on circulating testosterone levels in female rats, with both groups, control and exposed, following the same cyclical pattern throughout the timepoints analyzed. Conclusions: Antibiotic depletion of the gut microbiome is associated with changes in systemic levels of testosterone in rats. These changes are sex-specific, and only detected in males. These results suggest a potential involvement of the gut microbiome in testosterone metabolism that is sex-specific. Presentation: 6/1/2024

Depletion of the paternal gut microbiome alters sperm small RNAs and impacts offspring physiology and behavior in mice

The paternal environment prior to conception has been demonstrated to influence offspring physiology and behavior, with the sperm epigenome (including noncoding RNAs) proposed as a potential facilitator of non-genetic inheritance. Whilst the maternal gut microbiome has been established as an important influence on offspring development, the impact of the paternal gut microbiome on offspring development, health and behavior is largely unknown. Gut microbiota have major influences on immunity, and thus we hypothesized that they may be relevant to paternal immune activation (PIA) modulating epigenetic inheritance in mice. Therefore, male C57BL/6J mice (F0) were orally administered non-absorbable antibiotics via drinking water in order to substantially deplete their gut microbiome. Four weeks after administration of the antibiotics (gut microbiome depletion), F0 male mice were then mated with naïve female mice. The F1 offspring of the microbiome-depleted males had reduced body weight as well as altered gut morphology (shortened colon length). F1 females showed significant alterations in affective behaviors, including measures of anxiety and depressive-like behaviors, indicating altered development. Analysis of small noncoding RNAs in the sperm of F0 mice revealed that gut microbiome depletion is associated with differential expression of 8 different PIWI-interacting RNAs (piRNAs), each of which has the potential to modulate the expression of multiple downstream gene targets, and thus influence epigenetic inheritance and offspring development. This study demonstrates that the gut-germline axis influences sperm small RNA profiles and offspring physiology, with specific impacts on offspring affective and/or coping behaviors. These findings may have broader implications for other animal species with comparable gut microbiota, intergenerational epigenetics and developmental biology, including humans.

A gut reaction? The role of the microbiome in aggression

Recent research has unveiled conflicting evidence regarding the link between aggression and the gut microbiome. Here, we compared behavior profiles of control, germ-free (GF), and antibiotic-treated mice, as well as re-colonized GF mice to understand the impact of the gut microbiome on aggression using the resident-intruder paradigm. Our findings revealed a link between gut microbiome depletion and higher aggression, accompanied by notable changes in urine metabolite profiles and brain gene expression. This study extends beyond classical murine models to humanized mice to reveal the clinical relevance of early-life antibiotic use on aggression. Fecal microbiome transplant from infants exposed to antibiotics in early life (and sampled one month later) into mice led to increased aggression compared to mice receiving transplants from unexposed infants. This study sheds light on the role of the gut microbiome in modulating aggression and highlights its potential avenues of action, offering insights for development of therapeutic strategies for aggression-related disorders.

Colony-stimulating factor 2 (CSF2) as a gut microbiome dependent immune factor that alters molecular and behavioral responses to cocaine in male mice

Cocaine use disorder is a condition that leads to tremendous morbidity and mortality for which there are currently no FDA-approved pharmacotherapies. Previous research has demonstrated an important role for the resident population of bacteria of the large intestine, collectively dubbed the gut microbiome, in modulating brain and behavior in models of cocaine and other substance use disorders. Importantly, previous work has repeatedly shown that depletion of the gut microbiome leads to increased cocaine taking and seeking behaviors in multiple models. While the precise mechanism of these gut-brain signaling pathways in models of cocaine use is not fully clear, and intriguing possibility is through gut microbiome influences on innate immune system function. In this manuscript we identify the cytokine colony stimulating factor 2 (CSF2) as an immune factor that is increased by cocaine in a gut microbiome dependent manner. Peripherally injected CSF2 crosses the blood–brain barrier into the nucleus accumbens, a brain region central to behavioral responses to cocaine. Treatment with peripheral CSF2 reduces acute and sensitized locomotor responses to cocaine as well as reducing cocaine place preference at high doses. On a molecular level, we find that peripheral injections of CSF2 alter the transcriptional response to both acute and repeated cocaine in the nucleus accumbens. Finally, treatment of microbiome depleted mice with CSF2 reverses the behavioral effects of microbiome depletion on the conditioned place preference assay. Taken together, this work identifies an innate immune factor that represents a novel gut-brain signaling cascade in models of cocaine use and lays the foundations for further translational work targeting this pathway.

The atypical antipsychotics lurasidone and olanzapine exert contrasting effects on the gut microbiome and metabolic function of rats.

Antipsychotics such as olanzapine are associated with significant metabolic dysfunction, attributed to gut microbiome dysbiosis. A recent notion that most psychotropics are detrimental to the gut microbiome has arisen from consistent findings of metabolic adverse effects. However, unlike olanzapine, the metabolic effects of lurasidone are conflicting. Thus, this study investigates the contrasting effects of olanzapine and lurasidone on the gut microbiome to explore the hypothesis of 'gut neutrality' for lurasidone exposure. Using Sprague-Dawley rats, the effects of olanzapine and lurasidone on the gut microbiome were explored. Faecal and blood samples were collected weekly over a 21-day period to analyse changes to the gut microbiome and related metabolic markers. Lurasidone triggered no significant weight gain or metabolic alterations, instead positively modulating the gut microbiome through increases in mean operational taxonomical units (OTUs) and alpha diversity. This novel finding suggests an underlying mechanism for lurasidone's metabolic inertia. In contrast, olanzapine triggered a statistically significant decrease in mean OTUs, substantial compositional variation and a depletion in short-chain fatty acid abundance. Microbiome depletion correlated with metabolic dysfunction, producing a 30% increase in weight gain, increased pro-inflammatory cytokine expression, and increased blood glycaemic and triglyceride levels. Our results challenge the notion that all antipsychotics disrupt the gut microbiome similarly and highlights the potential benefits of gut-neutral antipsychotics, such as lurasidone, in managing metabolic side effects. Further research is warranted to validate these findings in humans to guide personalised pharmacological treatment regimens for schizophrenia.

Microbiome depletion and recovery in the sea anemone, Exaiptasia diaphana, following antibiotic exposure.

Microbial species that comprise host-associated microbiomes play an essential role in maintaining and mediating the health of plants and animals. While defining the role of individual or even complex communities is important toward quantifying the effect of the microbiome on host health, it is often challenging to develop causal studies that link microbial populations to changes in host fitness. Here, we investigated the impacts of reduced microbial load following antibiotic exposure on the fitness of the anemone, Exaiptasia diaphana and subsequent recovery of the host's microbiome. Anemones were exposed to two different types of antibiotic solutions for 3 weeks and subsequently held in sterilized seawater for a 3-week recovery period. Our results revealed that both antibiotic treatments reduced the overall microbial load during and up to 1 week post-treatment. The observed reduction in microbial load was coupled with reduced anemone biomass, halted asexual reproduction rates, and for one of the antibiotic treatments, the partial removal of the anemone's algal symbiont. Finally, our amplicon sequencing results of the 16S rRNA gene revealed that anemone bacterial composition only shifted in treated individuals during the recovery phase of the experiment, where we also observed a significant reduction in the overall diversity of the microbial community. Our work implies that the E. diaphana's microbiome contributes to host fitness and that the recovery of the host's microbiome following disturbance with antibiotics leads to a reduced, but stable microbial state.IMPORTANCEExaiptasia diaphana is an emerging model used to define the cellular and molecular mechanisms of coral-algal symbioses. E. diaphana also houses a diverse microbiome, consisting of hundreds of microbial partners with undefined function. Here, we applied antibiotics to quantify the impact of microbiome removal on host fitness as well as define trajectories in microbiome recovery following disturbance. We showed that reduction of the microbiome leads to negative impacts on host fitness, and that the microbiome does not recover to its original composition while held under aseptic conditions. Rather the microbiome becomes less diverse, but more consistent across individuals. Our work is important because it suggests that anemone microbiomes play a role in maintaining host fitness, that they are susceptible to disturbance events, and that it is possible to generate gnotobiotic individuals that can be leveraged in microbiome manipulation studies to investigate the role of individual species on host health.

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.

Host microbiome depletion attenuates biofluid metabolite responses following radiation exposure.

Development of novel biodosimetry assays and medical countermeasures is needed to obtain a level of radiation preparedness in the event of malicious or accidental mass exposures to ionizing radiation (IR). For biodosimetry, metabolic profiling with mass spectrometry (MS) platforms has identified several small molecules in easily accessible biofluids that are promising for dose reconstruction. As our microbiome has profound effects on biofluid metabolite composition, it is of interest how variation in the host microbiome may affect metabolomics based biodosimetry. Here, we 'knocked out' the microbiome of male and female C57BL/6 mice (Abx mice) using antibiotics and then irradiated (0, 3, or 8 Gy) them to determine the role of the host microbiome on biofluid radiation signatures (1 and 3 d urine, 3 d serum). Biofluid metabolite levels were compared to a sham and irradiated group of mice with a normal microbiome (Abx-con mice). To compare post-irradiation effects in urine, we calculated the Spearman's correlation coefficients of metabolite levels with radiation dose. For selected metabolites of interest, we performed more detailed analyses using linear mixed effect models to determine the effects of radiation dose, time, and microbiome depletion. Serum metabolite levels were compared using an ANOVA. Several metabolites were affected after antibiotic administration in the tryptophan and amino acid pathways, sterol hormone, xenobiotic and bile acid pathways (urine) and lipid metabolism (serum), with a post-irradiation attenuative effect observed for Abx mice. In urine, dose×time interactions were supported for a defined radiation metabolite panel (carnitine, hexosamine-valine-isoleucine [Hex-V-I], creatine, citric acid, and Nε,Nε,Nε-trimethyllysine [TML]) and dose for N1-acetylspermidine, which also provided excellent (AUROC ≥ 0.90) to good (AUROC ≥ 0.80) sensitivity and specificity according to the area under the receiver operator characteristic curve (AUROC) analysis. In serum, a panel consisting of carnitine, citric acid, lysophosphatidylcholine (LysoPC) (14:0), LysoPC (20:3), and LysoPC (22:5) also gave excellent to good sensitivity and specificity for identifying post-irradiated individuals at 3 d. Although the microbiome affected the basal levels and/or post-irradiation levels of these metabolites, their utility in dose reconstruction irrespective of microbiome status is encouraging for the use of metabolomics as a novel biodosimetry assay.

Antibiotic-induced microbiome depletion promotes intestinal colonization by Campylobacter jejuni in mice

BackgroundTo establish a method to induce Campylobacter jejuni colonization in the intestines of C57BL/6 mice through antibiotic-induced microbiome depletion.ResultsFifty-four female C57BL/6 mice were divided into the normal, control, and experimental groups. The experimental group was administered intragastric cefoperazone sodium and sulbactam sodium (50 mg/mL) for 2 days; then, the experimental and control mice were intragastrically administered 200 µL C. jejuni, which was repeated once more after 2 days. Animal feces were collected, and the HipO gene of C. jejuni was detected using TaqMan qPCR from day 1 to day 14 after modeling completion. Immunofluorescence was used to detect intestinal C. jejuni colonization on day 14, and pathological changes were observed using hematoxylin and eosin staining. Additionally, 16S rDNA analyses of the intestinal contents were conducted on day 14. In the experimental group, C. jejuni was detected in the feces from days 1 to 14 on TaqMan qPCR, and immunofluorescence-labeled C. jejuni were visibly discernable in the intestinal lumen. The intestinal mucosa was generally intact and showed no significant inflammatory-cell infiltration. Diversity analysis of the colonic microbiota showed significant inter-group differences. In the experimental group, the composition of the colonic microbiota differed from that in the other 2 groups at the phylum level, and was characterized by a higher proportion of Bacteroidetes and a lower proportion of Firmicutes.ConclusionsMicrobiome depletion induced by cefoperazone sodium and sulbactam sodium could promote long-term colonization of C. jejuni in the intestines of mice.

Rituximab-induced gut microbiota changes in Chinese neuromyelitis optica spectrum disorders

BackgroundRecent evidence shows that immunosuppressive agents can affect the gut microbiota in autoimmune diseases. However, the relationship between the gut microbiome and B-cell depletion immunotherapy in neuromyelitis optica spectrum disorder (NMOSD) remains poorly understood. ObjectivesTo evaluate the distinct intestinal microbial patterns and serum cytokine levels after short-term rituximab treatment (three months) in patients with NMOSD. MethodsFirstly, we conducted a cross-sectional study involving 46 treatment-naïve NMOSD patients and 48 matched healthy controls. We collected fecal specimens, which were then analyzed using next-generation sequencing, and quantified serum cytokines. Subsequently, fecal and serum samples were re-collected and re-evaluated in 31 of the 46 treatment-naïve NMOSD patients after RTX treatment. ResultsComparing the gut microbiome of treatment-naïve NMOSD patients to that of healthy controls revealed low α-diversity and distinct microbial compositions in the former. The microbial composition in NMOSD patients underwent changes following three months of RTX treatment. Specifically, the levels of IL-17F and IL-6 decreased, while those of IL-10 and TNFα increased after RTX treatment. LEfSe analysis identified 27 KEGG categories with significantly differential abundances between NMOSD patients and RTX treatment group. ConclusionsOur study provides a comprehensive understanding of the gut microbiota landscape in the context of B-cell depletion immunotherapy. We observed dysbiosis in the gut microbiome of NMOSD patients, which was partially alleviated by three months of RTX treatment. This suggests that B-cell depletion may play a crucial role in driving changes in the gastrointestinal environment.

Commensal Skin Bacteria Exacerbate Inflammation and Delay Skin Barrier Repair

The skin microbiome can both trigger beneficial immune stimulation and pose a potential infection threat. Previous studies have shown that colonization of mouse skin with the model human skin commensal Staphylococcus epidermidis is protective against subsequent excisional wound or pathogen challenge. However, less is known about concurrent skin damage and exposure to commensal microbes, despite growing interest in interventional probiotic therapy. Here, we address this open question by applying commensal skin bacteria at a high dose to abraded skin. While depletion of the skin microbiome via antibiotics delayed repair from damage, probiotic-like application of commensals-- including the mouse commensal Staphylococcus xylosus, three distinct isolates of S. epidermidis, and all other tested human skin commensals-- also significantly delayed barrier repair. Increased inflammation was observed within four hours of S. epidermidis exposure and persisted through day four, at which point the skin displayed a chronic wound-like inflammatory state with increased neutrophil infiltration, increased fibroblast activity, and decreased monocyte differentiation. Transcriptomic analysis suggested that the prolonged upregulation of early canonical proliferative pathways inhibited the progression of barrier repair. These results highlight the nuanced role of members of the skin microbiome in modulating barrier integrity and indicate the need for caution in their development as probiotics.

Faecal microbial transfer and complex carbohydrates mediate protection against COPD

ObjectiveChronic obstructive pulmonary disease (COPD) is a major cause of global illness and death, most commonly caused by cigarette smoke. The mechanisms of pathogenesis remain poorly understood, limiting the development...