Unique factors in the space environment can cause dysbiosis of astronauts' gut microbiota and its metabolites, which may exert systematic physiological effects on human body. Recent progress regarding the effect of space flight/simulated space environment (SF/SPE) on the composition of gut microbiota and its metabolites was reviewed in this paper. SF/SPE may cause the increase of invasive pathogenic bacteria and the decrease of beneficial bacteria, aggravating intestinal inflammation and increasing intestinal permeability. SF/SPE may also cause the decrease of beneficial metabolites or the increase of harmful metabolites of gut microbiota, leading to metabolism disorder in vivo, or inducing damage of other systems, thus not beneficial to the health and working efficiency of astronauts. Summarizing the effects of SF/SPE on gut microbiota may provide scientific basis for further researches in this field and the on-orbit health protection of astronauts.
Humans ; Gastrointestinal Microbiome/physiology* ; Dysbiosis/microbiology* ; Bacteria/metabolism*

The aim of this study was to identify whether periodontitis induces gut microbiota dysbiosis via invasion by salivary microbes. First, faecal and salivary samples were collected from periodontally healthy participants (PH group, n = 16) and patients with severe periodontitis (SP group, n = 21) and analysed by 16S ribosomal RNA sequencing. Significant differences were observed in both the faecal and salivary microbiota between the PH and SP groups. Notably, more saliva-sourced microbes were observed in the faecal samples of the SP group. Then, the remaining salivary microbes were transplanted into C57BL6/J mice (the C-PH group and the C-SP group), and it was found that the composition of the gut microbiota of the C-SP group was significantly different from that of the C-PH group, with Porphyromonadaceae and Fusobacterium being significantly enriched in the C-SP group. In the colon, the C-SP group showed significantly reduced crypt depth and zonula occludens-1 expression. The mRNA expression levels of pro-inflammatory cytokines, chemokines and tight junction proteins were significantly higher in the C-SP group. To further investigate whether salivary bacteria could persist in the intestine, the salivary microbiota was stained with carboxyfluorescein diacetate succinimidyl ester and transplanted into mice. We found that salivary microbes from both the PH group and the SP group could persist in the gut for at least 24 h. Thus, our data demonstrate that periodontitis may induce gut microbiota dysbiosis through the influx of salivary microbes.
Animals ; Dysbiosis ; Gastrointestinal Microbiome ; Humans ; Mice ; Mice, Inbred C57BL ; Microbiota ; Periodontitis ; RNA, Ribosomal, 16S/metabolism*

Animals ; Cadmium/toxicity* ; Dysbiosis/metabolism* ; Gastrointestinal Microbiome ; Glutamine/pharmacology* ; Methionine ; Mice ; Mice, Inbred C57BL ; Ostreidae ; Protein Hydrolysates ; Tyrosine

Gut microbiota have been known to play an essential role in host immunity and metabolism. Dysbiosis is associated with various gastrointestinal (GI) and other diseases such as cancers, metabolic diseases, allergies, and immunological disorders. So far, the role of gut microbiota has been studied mainly in lower GI disease but has recently been reported in upper GI diseases other than Helicobacter pylori infection, including Barrett's esophagus, esophageal carcinoma, gastric cancer, functional dyspepsia, and non-steroidal anti-inflammatory drug-induced small intestinal mucosal injury. Probiotics have some beneficial effect on these diseases, but the effects are strain specific.
Anti-Inflammatory Agents, Non-Steroidal ; Barrett Esophagus ; Dysbiosis ; Dyspepsia ; Gastrointestinal Diseases ; Gastrointestinal Microbiome ; Helicobacter Infections ; Helicobacter pylori ; Hypersensitivity ; Metabolic Diseases ; Metabolism ; Microbiota ; Probiotics ; Stomach Neoplasms ; Upper Gastrointestinal Tract

Antibiotic exposure-induced dysbiosis of the intestinal flora increases the risk of developing allergic rhinitis. Hence, regulating the balance of intestinal flora may be useful for preventing and treating allergic rhinitis. However, the underlying mechanism is unclear. Dendrobium nobile (Shihu) exhibits anti-inflammatory and immune activities. Hence, in this study, we investigated the mechanism via which Shihu may improve allergic rhinitis. Mouse models of allergic rhinitis with intestinal flora dysbiosis (Model-D, antibiotics induce intestinal flora dysbiosis with ovalbumin-induced allergy) and normal intestinal flora with allergic rhinitis (Model-N, ovalbumin-induced allergy) were established. The effect of Shihu on intestinal flora and inflammation caused during allergic rhinitis were analyzed. Allergic symptoms, infiltration of hematoxylin and eosin in the lungs and nose, and the release of various factors [interleukin (IL)-2, IL-4, IFN-γ, IL-6, IL-10, and IL-17] in the lungs were evaluated. The results indicate that intestinal flora dysbiosis exacerbated lung and nose inflammation in allergic rhinitis. However, treatment with the Shihu extract effectively reversed these symptoms. Besides, the Shihu extract inhibited the PI3K/AKT/mTOR pathway and increased the level of Forkhead box protein in the lungs. Additionally, the Shihu extract reversed intestinal flora dysbiosis at the phylum and genus levels and improved regulator T cell differentiation. Furthermore, in the Model-D group, the Shihu extract inhibited the decrease in the diversity and abundance of the intestinal flora. Screening was performed to determine which intestinal flora was positively correlated with Treg differentiation using Spearman's correlation analysis. In conclusion, we showed that Shihu extract restored the balance in intestinal flora and ameliorated inflammation in the lungs of allergic rhinitis mice and predicted a therapeutic new approach using Traditional Chinese Medicine to improve allergic rhinitis.
Animals ; Cytokines/metabolism* ; Dendrobium ; Disease Models, Animal ; Drugs, Chinese Herbal/pharmacology* ; Dysbiosis/drug therapy* ; Gastrointestinal Microbiome ; Inflammation/drug therapy* ; Mice ; Mice, Inbred BALB C ; Ovalbumin ; Phosphatidylinositol 3-Kinases ; Pneumonia ; Rhinitis, Allergic/metabolism*