Intestinal mucosal microbiota mediate amino acid metabolism involved in the gastrointestinal adaptability to cold and humid environmental stress in mice

Growing evidence has demonstrated that cold and humid environmental stress triggers gastrointestinal (GI) disorders. In this study, we explored the effects of intestinal microbiota homeostasis on the intestinal mucus barrier and GI disorders by cold and humid environmental stress. Moreover, the inner link between the intestinal mucosal microbiota and metabolites in mice with cold and humid environmental stress was interpreted by integrative analysis of PacBio HiFi sequencing microbial genomics and targeted metabolomics. In the current study, we found (1) after the cold and wet cold and humid environmental stress intervened in the intestinal microbiota disorder and homeostasis mice respectively, the bacterial culturing and fluorescein diacetate (FDA) microbial activity detection of intestinal microbiota including feces, intestinal contents, and intestinal mucosa suggested that the cold and humid environmental stress decreased the colony of culturable bacteria and microbial activity, in which intestinal microbiota disorder aggravated the injury of the intestinal mucus barrier and the GI symptoms related to cold and humid environmental stress; (2) the serum amino acid transferases such as glutamate pyruvic transa (GPT), and glutamic oxaloacetic transaminase (GOT) in cold and humid environmental stressed mice increased significantly, indicating that the intestinal microbiota adapted to cold and humid environmental stress by regulating the host's amino acid metabolism; (3) the integrative analysis of multi-omics illustrated a prediction model based on the microbiota Lactobacillus reuteri abundance and host amino acid level that can predict intestinal mucoprotein Muc2 with an adjusted R2 of 75.0%. In conclusion, the cold and humid environmental stress regulates the neurotransmitter amino acids metabolic function both in intestinal mucosal microbiota and host serum by adjusting the composition of the dominant bacterial population Lactobacillus reuteri, which contributes to the intestinal mucus barrier injury and GI disorders caused by cold and humid environmental stress.

Brain-bacteria-gut axis and oxidative stress mediated by intestinal mucosal microbiota might be an important mechanism for constipation in mice

Intestinal microbiota disorder was associated with constipation. This study investigated the microbiota-gut-brain axis and oxidative stress mediated by intestinal mucosal microbiota in mice with spleen deficiency constipation. The Kunming mice were randomly divided into the control (MC) group and the constipation (MM) group. The spleen deficiency constipation model was established by gavage with Folium sennae decoction and controlled diet and water intake. The body weight, spleen and thymus index, 5-Hydroxytryptamine (5-HT) and Superoxide Dismutase (SOD) content were significantly lower in the MM group than the MC group, the content of vasoactive intestinal peptide (VIP) and malondialdehyde (MDA) content were significantly higher than the MC group. The Alpha diversity of intestinal mucosal bacteria was not changed but beta diversity was changed in mice with spleen deficiency constipation. Compared to the MC group, the relative abundance of Proteobacteria was an upward trend and the Firmicutes/Bacteroidota (F/B) value was a downward trend in the MM group. There was a significant difference in the characteristic microbiota between the two groups. In the MM group, Brevinema, Akkermansia, Parasutterella, Faecalibaculum, Aeromonas, Sphingobium, Actinobacillus, and other pathogenic bacteria were enriched. Meanwhile, there was a certain relationship between the microbiota and gastrointestinal neuropeptide and oxidative stress indicators. The community structure of intestinal mucosal bacteria in mice with spleen deficiency constipation was changed, which was characterized by the reduction of F/B value and enrichment of Proteobacteria. Microbiota-gut-brain axis may be important for spleen deficiency constipation.

The diarrheal mechanism of mice with a high-fat diet in a fatigued state is associated with intestinal mucosa microbiota

Growing evidence has demonstrated that fatigue and a high-fat diet trigger diarrhea, and intestinal microbiota disorder interact with diarrhea. However, the association of intestinal mucosal microbiota with fatigue and high-fat diet trigger diarrhea remains unclear. The specific pathogen-free Kunming male mice were randomly divided into the normal group (MCN), standing group (MSD), lard group (MLD), and standing united lard group (MSLD). Mice in the MSD and MSLD groups stood on the multiple-platform apparatus for four h/d for fourteen consecutive days. From the eighth day, mice in the MLD and MSLD groups were intragastric lard, 0.4 mL/each, twice a day for seven days. Subsequently, we analyzed the characteristics and interaction relationship of intestinal mucosal microbiota, interleukin-6 (IL-6), interleukin-17 (IL-17), malondialdehyde (MDA), superoxide dismutase (SOD), and secretory immunoglobulin A (sIgA). Results showed that mice in the MSLD group had an increased number of bowel movements. Compared with the MCN group, the contents of IL-17, and IL-6 were higher (p > 0.05), and the content of sIgA was lower in the MSLD group (p > 0.05). MDA and SOD increased in MLD and MSLD groups. Thermoactinomyces and Staphyloccus were the characteristic bacteria of the MSLD group. And Staphyloccus were positively correlated with IL-6, IL-17, and SOD. In conclusion, the interactions between Thermoactinomyces, Staphyloccus and intestinal inflammation, and immunity might be involved in fatigue and high-fat diet-induced diarrhea.

Distinctions Between Fecal and Intestinal Mucosal Microbiota in Subgroups of Irritable Bowel Syndrome

BACKGROUND AND AIMS

Recent studies have shown that changes in the intestinal microbiota contribute to the pathogenesis of irritable bowel syndrome (IBS). This study aimed to investigate the characteristics of the fecal and intestinal mucosal microbiota in IBS patients, and the correlation between microbiota and clinical manifestations.

METHODS

Fecal and intestinal mucosal samples were collected from 14 constipation-predominant IBS (IBS-C) patients, 20 diarrhea-predominant IBS (IBS-D) patients, and 20 healthy controls (HCs). 16S rRNA gene sequencing and fluorescence in situ hybridization were used for the analysis of samples.

RESULTS

Community richness and diversity of the fecal microbiota in IBS patients were significantly reduced compared with the HCs. The mucosal samples in IBS patients showed decreased Bifidobacterium and increased Bacteroides caccae compared with HCs; Eubacterium and Roseburia were decreased in IBS-C patients and increased in IBS-D patients. A comparison of the fecal and mucosal microbiota in IBS patients showed significantly increased Bifidobacterium in fecal samples and a decrease in mucosal samples in IBS-C patients; Bacteroides caccae and Roseburia were significantly reduced in fecal samples and increased in mucosal samples of IBS patients. A correlation between microbiota and clinical manifestations in IBS patients showed that Bacteroides caccae and Roseburia in fecal samples and Bifidobacterium and Eubacterium in mucosal samples were associated with abdominal pain and distention.

CONCLUSIONS

Distinct differences exist between the fecal and intestinal mucosal microbiota in IBS patients, with the changes in the latter appearing more consistent with the pathophysiology of IBS. Changes in intestinal microbiota were associated with the clinical manifestations in IBS.