Gut Microbiome In Mice Research Articles

Longitudinal and Multi-Kingdom Gut Microbiome Alterations in a Mouse Model of Alzheimer’s Disease

Gut microbial dysbiosis, especially bacteriome, has been implicated in Alzheimer’s disease (AD). However, nonbacterial members of the gut microbiome in AD, such as the mycobiome, archaeome, and virome, are unexplored. Here, we perform higher-resolution shotgun metagenomic sequencing on fecal samples collected longitudinally from a mouse model of AD to investigate longitudinal and multi-kingdom gut microbiome profiling. Shotgun metagenomic sequencing of fecal samples from AD mice and healthy mice returns 41,222 bacterial, 414 fungal, 1836 archaeal, and 1916 viral species across all time points. The ecological network pattern of the gut microbiome in AD mice is characterized by more complex bacterial–bacterial interactions and fungal–fungal interactions, as well as simpler archaeal–archaeal interactions and viral–viral interactions. The development of AD is accompanied by multi-kingdom shifts in the gut microbiome composition, as evidenced by the identification of 1177 differential bacterial, 84 differential fungal, 59 differential archaeal, and 10 differential viral species between healthy and AD mice across all time points. In addition, the functional potential of the gut microbiome is partially altered in the development of AD. Collectively, our findings uncover longitudinal and multi-kingdom gut microbiome alterations in AD and provide a motivation for considering microbiome-based therapeutics during the prevention and treatment of AD.

The gut microbiotas with metabolites regulate the protective role of miR-30a-5p in myocardial infarction

IntroductionGut microbial homeostasis is closely associated with myocardial infarction (MI). However, little is known about how gut microbiota influences miRNAs-regulated MI. ObjectivesThis study aims to elucidate the connections between miR-30a-5p, MI, gut microbiota, and gut microbial metabolite-related pathways, to explore potential strategy for preventing and treating MI. MethodsWe evaluated the effects of knocking out (KO) or overexpressing (OE) miR-30a-5p on MI by assessing cardiac structure and function, myocardial enzyme levels, and apoptosis. Then, we applied 16S rDNA sequencing and metabolomics to explore how intestinal microecology and its microorganisms affect miR-30a-5p-regulated MI. ResultsThe results showed that KO exacerbated MI, whereas OE improved MI damage, compared to the wild-type (WT) mice. KO exacerbated intestinal barrier structure deterioration and further downregulated the expression of Cloudin-1, Occludin, and ZO-1 in MI mice. 16S rDNA sequencing-analyzed gut microbiome of KO and WT mice found that KO mainly reduced g_Lactobacillus. Transplanting fecal microorganisms from KO mice aggravated MI damage in WT mice. However, administering probiotics (mainly containing Lactobacillus) helped neutralize these damages. Intriguingly, fecal microbiota transplantation from OE mice reduced MI damage. Analysis of intestinal microbial metabolites in KO and WT mice found that KO may mainly affect ABC transporters. ABCC1 was identified as the target of KO-aggravated MI. Furthermore, fecal transplantation microorganisms of MI patients aggravated MI injury in mice and miR-30a-5p and ABCC1 were involved in the process. ConclusionsOur findings demonstrate that miR-30a-5p regulates MI by affecting intestinal microbiota homeostasis and targeting ABCC1. This highlights the critical importance of maintaining a healthy gut microbiota homeostasis in MI management.

β-galactosidase producing Lactiplantibacillus spp in intestinal microbiome mouse diarrhea model and metagenomic analyses

Probiotics have attained significant interest in recent years as a result of their gut microbiome modulation and gastrointestinal health benefits. Numerous fermented foods contain LAB with GRAS grade and probiotic bacteria. The most promising isolates with high potentiality were selected for 16S rRNA gene sequence analysis and identified as Lactiplantibacillus plantarum, L. fermentum, L. pentosus and Lactiplantibacillus sp. The present study was conducted to determine the gastrointestinal symptoms after the consumption of milk and dairy products, lactose intolerance status using mice model. Post-weaning Balb/c mice were orally administered with probiotic bacteria to assess their efficiency in reducing lactose intolerance symptoms. They exhibited significantly reduced total feces weight and slower intestinal motility and they efficiently alleviated diarrhea symptoms within 6 h of lactose challenge in lactose intolerance-induced mice. Next generation sequence analysis was performed using intestinal content of model treated with L. plantarum GV54 and GV64, the intestinal bacterial diversity was studied using Illumina NGS analysis (16S rRNA hypervariable regions [V3 and V4]). NGS report confirmed the existence of the dominant phyla of the gut microbiome in mice are Bacteroidetes, Firmicutes and Proteobacteria. Due to the influence of the probiotic bacteria in the model group (GV54 and GV64), maximum abundance of phylum Firmicutes were observed when compared to the control group, whereas control group showed more abundance of phylum Bacteriodetes. However, the relative abundance of Bacteroidetes in the model group was decreased and Firmicutes abundance was increased. This indicates the genus abundance of Lactobacillus (Lactiplantibacillus) species or Lactiplantibacillus plantarum GV54 and GV64 bacteria. After treatment with probiotic bacteria Lactobacillus (Lactiplantibacillus) species, the probiotic bacterial abundance was increased consequently genera Helicobacter, Clostridiales unclassified and Desulfovibrio were decreased in the model groups. Probiotic bacteria has a positive impact on the regulation of intestinal microbial diversity in the tested mice system and it reflects that the intestinal microbiota of mice is dynamic and has positive impact on gut health. Considering this point, it is possible to promote Lactiplantibacillus spp. as probiotics and therapeutic food development at industrial scale.

The microbiota-dependent tryptophan metabolite alleviates high-fat diet–induced insulin resistance through the hepatic AhR/TSC2/mTORC1 axis

Type 2 diabetes (T2D) is potentially linked to disordered tryptophan metabolism that attributes to the intricate interplay among diet, gut microbiota, and host physiology. However, underlying mechanisms are substantially unknown. Comparing the gut microbiome and metabolome differences in mice fed a normal diet (ND) and high-fat diet (HFD), we uncover that the gut microbiota-dependent tryptophan metabolite 5-hydroxyindole-3-acetic acid (5-HIAA) is present at lower concentrations in mice with versus without insulin resistance. We further demonstrate that the microbial transformation of tryptophan into 5-HIAA is mediated by Burkholderia spp. Additionally, we show that the administration of 5-HIAA improves glucose intolerance and obesity in HFD-fed mice, while preserving hepatic insulin sensitivity. Mechanistically, 5-HIAA promotes hepatic insulin signaling by directly activating AhR, which stimulates TSC2 transcription and thus inhibits mTORC1 signaling. Moreover, T2D patients exhibit decreased fecal levels of 5-HIAA. Our findings identify a noncanonical pathway of microbially producing 5-HIAA from tryptophan and indicate that 5-HIAA might alleviate the pathogenesis of T2D.

Mechanism of Phyllanthus emblica polyphenols in alleviating DSS-induced ulcerative colitis: Insights from transcriptomics and microbiome analysis

The fruit of Phyllanthus emblica (PE) is a ‘drug homologous food’ that is rich in polyphenols for treating inflammatory diseases. Nevertheless, the ability of PE polyphenols (PEP) to alleviate ulcerative colitis (UC) remains unclear. The aim of this study was to reveal the chemical composition of PEP and its therapeutic potential for treating UC. In this study, PEP was purified with an NKA-2 macroporous resin and identified via liquid chromatography combined with mass spectrometry (LC‒MS). Furthermore, a dextran sulfate sodium salt-induced UC mice model was used to evaluate the ability of PEP to alleviate UC. The symptoms, histopathology, expression of inflammatory cytokines, mucus and tight junction levels, changes in the gut microbiome and colon transcriptomics of UC mice were assessed after PEP intervention. The results suggested that PEP strikingly improved weight loss, disease activity index scores, colon length changes and histopathological damage. Moreover, PEP inhibited the expression of serum proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and sustained intestinal integrity by increasing the expression of Mucin 2, Zonula occludens 1 and Occludin. 16S rRNA sequencing revealed that PEP regulated disorders of the gut microflora related to inflammation and the mucus barrier, including Escherichia_Shigella, Rikenellaceae_RC9_gut_group, Bacteroides, Muribaculaceae, Helicobacter and Anaerostipes. Transcriptome sequencing analysis, western blotting, and immunohistochemistry confirmed that PEP regulated reversed genes as well as effector proteins enriched in the PPAR signaling pathway (PPARγ, MMP1, CYP4A12A, and UCP1) and the Wnt/β-catenin signaling pathway (Wnt8B, FZD9, GSK3β, p-GSK3β, β-catenin, Axin2 and Lgr5). These findings indicate that PEP has therapeutic potential for alleviating UC and could serve as a functional dietary supplement.

Low-frequency Transcranial Magnetic Stimulation Ameliorates Anhedonic Behaviors and Regulates the Gut Microbiome in Mice Exposed to Chronic Unpredictable Mild Stress.

This paper presents a preliminary study on whether low-frequency transcranial magnetic stimulation (LF-TMS) can modulate the gut microbiota in mice with chronic unpredictable mild stress (CUMS). Mice received LF-TMS (1 Hz, 20 mT) for 28 consecutive days under chronic unpredictable mild stress (CUMS). The composition of gut microbiota of stool samples were tested. CUMS caused significant changes in gut microbiotas, specifically in community diversity of gut microbiotas (P < .05). Compared with the stressed group mice, the Chao1 index (P < .05), Observed species index (P < .05), Faith's PD index (P < .05) and Shannon index (P < .05) of the LF-TMS treatment group were significantly increased. Furthermore, 1 Hz LF-TMS-treatment partially recovered chronic stress induced changes of microbiotas, such as the abundance of Chloroflexi, Actinobacteria. These results manifested that LF-TMS treatment can improve the anhedonic behaviors caused by CUMS in mice, which are connected with regulating the related intestinal microbial community disturbance, including species diversity, structure of gut microbiota, and species composition.

Effects of Akkermansia muciniphila on Gut Morphology, Antioxidant Indices, and Gut Microbiome of Mice Under Heat Stress.

Nutritional manipulations can reduce the detrimental effects of heat stress on animal health and production. Akkermansia muciniphila (AM) is an innovative beneficial bacteria and can be used for conventional use as dietary supplements and pharmaceutical application. This study aimed to investigate the effects of administering AM on gut morphology, antioxidant indices, and gut microbiome of mice during heat stress. A total of 24 BALB/c mice were randomly assigned to three groups including the control group (CON), heat stress group (HS), and AM administration under heat stress group (AM). Our results showed heat stress significantly increased the water consumption of mice. Administration of AM did not improve feed intake or weight gain. The serum levels of alanine aminotransferase and aspartate aminotransferase as well as antioxidant parameters were not different among the three groups. Heat stress decreased the jejunal villus height, and AM could reverse this effect. AM administration significantly increased the relative abundance of Verrucomicrobiota at the phylum level. At the genus level, heat stress and AM groups tended to have a lower abundance of Alloprevotella. In addition, AM tended to increase the relative abundance of [Eubacterium]_xylanophilum_group in comparison with the other two groups. In summary, administration of AM can alleviate the damage of heat stress to the jejunum. However, it has no effect on serum antioxidant parameters, and its effect on the cecal microbiota is limited.

The effect of testosterone on the gut microbiome in mice

The role of hormones in gut–brain crosstalk is largely elusive, but recent research supports specific changes in hormone levels correlated with the gut microbiota. An interesting but unstudied area in microbial endocrinology is the interplay between the microbiota and sex hormones. The aim of this study is to investigate the effect of testosterone and sex on the mouse gut microbiome. We use in vitro experiments to test direct effects of testosterone on bacteria in fecal samples collected from male and female mice pre- and post-puberty. Sex-specific microbial and metabolic differences surrounding puberty are also examined in vivo. We then explore effects of testosterone supplementation in vivo, characterizing microbiota and metabolomes of male and female mice. We detect sex-specific differences in microbiota and associated metabolites of mice post-puberty, but in vitro experiments reveal that testosterone only affects microbiota of fecal samples collected before puberty. Testosterone supplementation in vivo affects gut microbiota and metabolomes in both male and female mice. Taking our results from in vitro and in vivo experiments, we conclude that the shift in the microbiome after puberty is at least partially caused by the higher levels of sex hormones, mainly testosterone, in the host.

Regular Consumption of Kombucha Alleviates Depression Symptoms and Modulates the Gut Microbiome in Mice

Regular Consumption of Kombucha Alleviates Depression Symptoms and Modulates the Gut Microbiome in Mice

Resistant Starches From Dietary Pulses Distinctly Modulate the Gut Microbiome, Mycobiome, Metabolome, and Neurocognitive Function in Aging Mice

Resistant Starches From Dietary Pulses Distinctly Modulate the Gut Microbiome, Mycobiome, Metabolome, and Neurocognitive Function in Aging Mice

Effect of Probiotic Bacteria on the Gut Microbiome of Mice with Lipopolysaccharide-Induced Inflammation.

The role of lipopolysaccharide (LPS) in the development of diseases is clear, but the specific mechanisms remain poorly understood. This study aimed to investigate the microbiome aberrations in the guts of mice against the background of LPS, as well as the anti-inflammatory effect of probiotic supplementation with Lactobacillus plantarum from the gut, a mix of commercial probiotic lactic acid bacteria, and Weissella confusa isolated from milk using next-generation sequencing. LPS injections were found to induce inflammatory changes in the intestinal mucosa. These morphological changes were accompanied by a shift in the microbiota. We found no significant changes in the microbiome with probiotic supplementation compared to the LPS group. However, when Lactobacillus plantarum and a mix of commercial probiotic lactic acid bacteria were used, the intestinal mucosa was restored. Weissella confusa did not contribute to the morphological changes of the intestinal wall or the microbiome. Changes in the microbiome were observed with probiotic supplementation of Lactobacillus plantarum and a mix of commercial probiotic lactic acid bacteria compared to the control group. In addition, when Lactobacillus plantarum was used, we observed a decrease in the enrichment of the homocysteine and cysteine interconversion pathways with an increase in the L-histidine degradation pathway.

Sulfated Polysaccharides from Sea Cucumber Cooking Liquid Prevents Obesity by Modulating Gut Microbiome, Transcriptome, and Metabolite Profiles in Mice Fed a High-Fat Diet.

We aimed to explore the anti-obesity mechanism from the microbiome, metabolome, and transcriptome viewpoints, focusing on the sulfated polysaccharides found in the cooking liquid of Apostichopus japonicus (CLSPAJ) to explore the potential mediators of the anti-obesity effects in mice fed a high-fat diet (HFD). The mice treated with CLSPAJ showed a decrease in obesity and blood lipid levels. Gut microbiome dysbiosis caused by the HFD was reversed after CLSPAJ supplementation, along with increased levels of indole-3-ethanol, N-2-succinyl-L-glutamic acid 5-semialdehyde, and urocanic acid. These increases were positively related to the increased Akkermansia, Lactobacillus, Roseburia, and Phascolarctobacterium. Transcriptome analysis showed that B cell receptor signaling and cytochrome P450 xenobiotic metabolism were the main contributors to the improvement in obesity. Metabolome-transcriptome analysis revealed that CLSPAJ reversal of obesity was mainly due to amino acid metabolism. These findings suggest that CLSPAJ could be a valuable prebiotic preparation for preventing obesity-related diseases.

A Novel Antioxidant, Hydrogen-Rich Coral Calcium Alters Gut Microbiome and Bile Acid Synthesis to Improve Methionine-and-Choline-Deficient Diet-Induced Non-Alcoholic Fatty Liver Disease.

The prevalence of non-alcoholic fatty liver disease (NAFLD) has dramatically increased in recent years, and it is highly associated with metabolic diseases, as well as the development of hepatocellular carcinoma. However, effective therapeutic strategies for the treatment of NAFLD are still scarce. Although hydrogen-rich water shows beneficial effects for hepatic steatosis, the inconvenience limits the application of this antioxidant. In light of this, hydrogen-rich coral calcium (HRCC) was developed due to its convenience and quantifiable characteristics. However, the effects of HRCC on NAFLD are still unknown. In the present study, we found that HRCC treatment improved methionine-and-choline-deficient diet (MCD)-induced hepatic steatosis, increased aspartate aminotransferase and alanine aminotransferase levels, and elevated hepatic inflammatory factor expressions in mice. In addition to the increased expressions of antioxidative enzymes, we found that HRCC increased the expressions of bile acid biosynthesis-related genes, including Cyp8b1 and Cyp27a1. Increased hepatic bile acid contents, such as muricholic acids, 23 nor-deoxycholic acid, glycoursodeoxycholic acid, and cholic acids, were also confirmed in MCD mice treated with HRCC. Since the biogenesis of bile acids is associated with the constitution of gut microbiome, the alterations in gut microbiome by HRCC were evaluated. We found that HRCC significantly changed the constitution of gut microbiome in MCD mice and increased the contents of Anaerobacterium, Acutalibacter, Anaerosacchariphilus, and Corynebacterium. Taken together, HRCC improved MCD-induced NAFLD through anti-inflammatory mechanisms and by increasing antioxidative activities. Additionally, HRCC might alter gut microbiome to change hepatic bile acid contents, exerting beneficial effects for the treatment of NAFLD.

D-Pinitol Improves Diabetic Sarcopenia by Regulation of the Gut Microbiome, Metabolome, and Proteome in STZ-Induced SAMP8 Mice.

d-Pinitol (DP) is primarily found in Vigna sinensis, which has been shown to have hypoglycemic and protective effects on target organs. However, the mechanism of DP in treating diabetic sarcopenia (DS) is still unclear. To explore the underlying mechanism of DS and the protective targets of DP by high-throughput analysis of 16S rRNA gene, metabolome, and the proteome. Streptozotocin-induced SAMP8 mice were intragastrically administrated DP (150 mg/kg) for 8 weeks. Fecal 16S rRNA gene sequencing and gastrocnemius muscle metabolomic and proteomic analyses were completed to investigate the gut-muscle axis interactions. DP significantly alleviated the muscle atrophy in diabetic mice. Dysfunction of the gut microbiota was observed in the DS mice. DP significantly reduced the Parabacteroides, Akkermansia, and Enterobacteriaceae, while it increased Lachnospiraceae_NK4A136. Metabolome and proteome revealed that 261 metabolites and 626 proteins were significantly changed in the gastrocnemius muscle of diabetic mice. Among these, DP treatment restored 44 metabolites and 17 proteins to normal levels. Functional signaling pathways of DP-treated diabetic mice included nucleotide metabolism, β-alanine, histidine metabolism, ABC transporters, and the calcium signaling pathway. We systematically explored the molecular mechanism of DS and the protective effect of DP, providing new insights that may advance the treatment of sarcopenia.

The effects of venlafaxine on depressive-like behaviors and gut microbiome in cuprizone-treated mice.

Cuprizone (CPZ)-treated mice show significant demyelination, altered gut microbiome, and depressive-like behaviors. However, the effects of venlafaxine (Ven) on the gut microbiome and depressive-like behavior of CPZ-treated mice are largely unclear. Male C57BL/6J mice were fed a chow containing 0.2% cuprizone (w/w) for 5 weeks to induce a model of demyelination. Meanwhile, the gut microbiota and depressive-like behaviors were assessed after the mice were fed with Ven (20 mg/kg/day) or equal volumes of distilled water for 2 weeks by oral gavage from the third week onward during CPZ treatment. CPZ treatment decreased the sucrose preference rate in the sucrose preference test and increased the immobility time in the tail-suspension test, and it also induced an abnormality in β-diversity and changes in microbial composition. Ven alleviated the depressive-like behavior and regulated the composition of the gut microbiota, such as the increase of Lactobacillus and Bifidobacterium in CPZ-treated mice. The anti-depressant effects of Ven might be related to the regulation of gut microbiota in the CPZ-treated mice.

A Gram-negative-selective antibiotic that spares the gut microbiome.

Infections caused by Gram-negative pathogens are increasingly prevalent and are typically treated with broad-spectrum antibiotics, resulting in disruption of the gut microbiome and susceptibility to secondary infections1-3. There is a critical need for antibiotics that are selective both for Gram-negative bacteria over Gram-positive bacteria, as well as for pathogenic bacteria over commensal bacteria. Here we report the design and discovery of lolamicin, a Gram-negative-specific antibiotic targeting the lipoprotein transport system. Lolamicin has activity against a panel of more than 130 multidrug-resistant clinical isolates, shows efficacy in multiple mouse models of acute pneumonia and septicaemia infection, and spares the gut microbiome in mice, preventing secondary infection with Clostridioides difficile. The selective killing of pathogenic Gram-negative bacteria by lolamicin is a consequence of low sequence homology for the target in pathogenic bacteria versus commensals; this doubly selective strategy can be a blueprint for the development of other microbiome-sparing antibiotics.

The transplantation of the gut microbiome of fat-1 mice protects against colonic mucus layer disruption and endoplasmic reticulum stress induced by high fat diet

ABSTRACT High-fat diets alter gut barrier integrity, leading to endotoxemia by impacting epithelial functions and inducing endoplasmic reticulum (ER) stress in intestinal secretory goblet cells. Indeed, ER stress, which is an important contributor to many chronic diseases such as obesity and obesity-related disorders, leads to altered synthesis and secretion of mucins that form the protective mucus barrier. In the present study, we investigated the relative contribution of omega-3 polyunsaturated fatty acid (PUFAs)-modified microbiota to alleviating alterations in intestinal mucus layer thickness and preserving gut barrier integrity. Male fat-1 transgenic mice (exhibiting endogenous omega-3 PUFAs tissue enrichment) and wild-type (WT) littermates were fed either an obesogenic high-fat diet (HFD) or a control diet. Unlike WT mice, HFD-fed fat-1 mice were protected against mucus layer alterations as well as an ER stress-mediated decrease in mucin expression. Moreover, cecal microbiota transferred from fat-1 to WT mice prevented changes in the colonic mucus layer mainly through colonic ER stress downregulation. These findings highlight a novel feature of the preventive effects of omega-3 fatty acids against intestinal permeability in obesity-related conditions.

Deciphering the therapeutic potential of SheXiangXinTongNing: Interplay between gut microbiota and brain metabolomics in a CUMS mice model, with a focus on tryptophan metabolism

Depression, a prevalent and multifaceted mental disorder, has emerged as a significant public health concern due to its escalating prevalence and heightened risk of severe suicidality. Given its profound impact, the imperative for preventing and intervening in depression is paramount. Substantial evidence underscores intricate connections between depression and cardiovascular health. SheXiangXinTongNing (XTN), a recognized traditional Chinese medicine for treating Coronary Heart Disease (CHD), prompted our exploration into its antidepressant effects and underlying mechanisms. In this investigation, we assessed XTN's antidepressant potential using the chronic unpredictable mild stress (CUMS) mice model and behavioral tests. Employing network pharmacology, we delved into the intricate mechanisms at play. We characterized the microbial composition and function in CUMS mice, both with and without XTN treatment, utilizing 16S rRNA sequencing and metabolomics analysis. The joint analysis of these results via Cytoscape identified pivotal metabolic pathways. In the realm of network pharmacology, XTN administration exhibited antidepressant effects by modulating pathways such as IL-17, neuroactive ligand-receptor interaction, PI3K-Akt, cAMP, calcium, and dopamine synapse signaling pathways. Our findings revealed that XTN significantly mitigated depression-like symptoms and cognitive deficits in CUMS mice by inhibiting neuroinflammation and pyroptosis. Furthermore, 16S rRNA sequencing unveiled that XTN increased the alpha-diversity and beta-diversity of the gut microbiome in CUMS mice. Metabolomics analysis identified brain metabolites crucial for distinguishing between the CUMS and CUMS+XTN groups, with a focus on pathways like Tryptophan metabolism and Linoleic acid metabolism. Notably, specific bacterial families, including Alloprevotella, Helicobacter, Allobaculum, and Clostridia, exhibited robust co-occurring relationships with brain tryptophan metabolomics, hinting at the potential mediating role of gut microbiome alterations and metabolites in the efficacy of XTN treatment. In conclusion, our study unveils modifications in microbial compositions and metabolic functions may be pivotal in understanding the response to XTN treatment, offering novel insights into the mechanisms underpinning the efficacy of antidepressants.

Milk and Lacticaseibacillus paracasei BL23 effects on intestinal responses in a murine model of colitis.

Probiotic-containing fermented dairy foods have the potential to benefit human health, but the importance of the dairy matrix for efficacy remains unclear. We investigated the capacity of Lacticaseibacillus paracasei BL23 in phosphate-buffered saline (BL23-PBS), BL23-fermented milk (BL23-milk), and milk to modify intestinal and behavioral responses in a dextran sodium sulfate (DSS, 3% wt/vol) mouse model of colitis. Significant sex-dependent differences were found such that female mice exhibited more severe colitis, greater weight loss, and higher mortality rates. Sex differences were also found for ion transport ex vivo, colonic cytokine and tight junction gene expression, and fecal microbiota composition. Measurements of milk and BL23 effects showed BL23-PBS consumption improved weight recovery in females, whereas milk resulted in better body weight recovery in males. Occludin and Claudin-2 gene transcript levels indicated barrier function was impaired in males, but BL23-milk was still found to improve colonic ion transport in those mice. Proinflammatory and anti-inflammatory gene expression levels were increased in both male and female mice fed BL23, and to a more variable extent, milk, compared with controls. The female mouse fecal microbiota contained high proportions of Akkermansia (average of 18.1%) at baseline, and females exhibited more changes in gut microbiota composition following BL23 and milk intake. Male fecal microbiota harbored significantly more Parasutterella and less Blautia and Roseburia after DSS treatment, independent of BL23 or milk consumption. These findings show the complex interplay between dietary components and sex-dependent responses in mitigating inflammation in the digestive tract.NEW & NOTEWORTHY Sex-dependent responses to probiotic Lacticaseibacillus paracasei and milk and the potential of the dairy matrix to enhance probiotic protection against colitis in this context have not been previously explored. Female mice were more sensitive than males to colonic injury, and neither treatment effectively alleviated inflammation in both sexes. These sex-dependent responses may result from differences in the higher baseline proportions of Akkermansia in the gut microbiome of female mice.

Rejuvenating fecal microbiota transplant enhances peripheral nerve repair in aged mice by modulating endoneurial inflammation

Peripheral nerve injury (PNI) resulting from trauma or neuropathies can cause significant disability, and its prognosis deteriorates with age. Emerging evidence suggests that gut dysbiosis and reduced fecal short-chain fatty acids (SCFAs) contribute to an age-related systemic hyperinflammation (inflammaging), which hinders nerve recovery after injury. This study thus aimed to evaluate the pro-regenerative effects of a rejuvenating fecal microbiota transplant (FMT) in a preclinical PNI model using aged mice. Aged C57BL/6 mice underwent bilateral crush injuries to their sciatic nerves. Subsequently, they either received FMT from young donors at three and four days after the injury or retained their aged gut microbiota. We analyzed gut microbiome composition and SCFA concentrations in fecal samples. The integrity of the ileac mucosal barrier was assessed by immunofluorescence staining of Claudin-1. Flow cytometry was utilized to examine immune cells and cytokine production in the ileum, spleen, and sciatic nerve. Various assessments, including behavioural tests, electrophysiological studies, and morphometrical analyses, were conducted to evaluate peripheral nerve function and repair following injury. Rejuvenating FMT reversed age-related gut dysbiosis by increasing Actinobacteria, especially Bifidobacteriales genera. This intervention also led to an elevation of gut SCFA levels and mitigated age-related ileac mucosal leakiness in aged recipients. Additionally, it augmented the number of T-helper 2 (Th2) and regulatory T (Treg) cells in the ileum and spleen, with the majority being positive for anti-inflammatory interleukin-10 (IL-10). In sciatic nerves, rejuvenating FMT resulted in increased M2 macrophage counts and a higher IL-10 production by IL-10+TNF-α− M2 macrophage subsets. Ultimately, restoring a youthful gut microbiome in aged mice led to improved nerve repair and enhanced functional recovery after PNI. Considering that FMT is already a clinically available technique, exploring novel translational strategies targeting the gut microbiome to enhance nerve repair in the elderly seems promising and warrants further evaluation.