Hyperlipidemia is a leading risk of cardiovascular and cerebrovascular disease. Dietary supplementation with probiotics has been suggested as an alternative intervention to lower cholesterol. In the current study, we isolated a strain of Lactobacillus gasseri RW2014 (LGA) from the feces of a healthy infant fed with breast milk, and it displayed bile salt hydrolase (BSH) activity. Using this strain we determined its cholesterol-lowering and fatty liver-improving functions. SD rats were randomly divided into four groups. The control rats were fed a commercial chow diet and the other three groups were fed a high-fat diet (HFD) for a 7-week experiment period. After two weeks of feeding, the rats in PBS, simvastin, and LGA group were daily administered through oral gavage with 2 mL PBS, simvastin (1 mg/mL), and 2 × 10⁹ CFU/mouse live LGA in PBS, respectively. After five weeks of such treatment, the rats were euthanized and tissue samples were collected. Blood lipid and inflammatory factors were measured by ELISA, gut microbiota was determined by 16S rRNA sequencing, and bile acids profiles were detected by metabolomics. We found that LGA group had lower levels of blood cholesterol and liver steatosis compared to the simvastin group. LGA also significantly reducedthe levels of inflammatory factors in the serum, including TNFα, IL-1β, MCP-1, IL-6, and exotoxin (ET), and increased the levels of short-chain fatty acids in feces, including isobutyric acid, butyric acid, isovaleric acid, valeric acid, and hexanoic acid. In addition, LGA altered the compositions of gut microbiota as manifested by the increased ratio of Firmicutes/Bacteroides and the relative abundance of Blautia genus. Targeted metabolomics results showed that bile acids, especially free bile acids and secondary bile acids in feces, were increased in LGA rats compared with the control rats. Accordingly, the rats administrated with LGA also had a higher abundance of serum bile acids, including 23-norcholic acid, 7-ketolithocholic acid, β-muricholic acid, cholic acid, and deoxycholic acid. Together, this study suggests that LGA may exert a cholesterol-lowering effect by modulating the metabolism of bile acids and the composition of gut microbiota.

Vibrio fluvialis causes human diarrhea, but the pathogenesis is not well-studied. We hypothesized that V. fluvialis-secreted hemolysin (VFH) may induce IL-1β secretion through the activation of the NLRP3 inflammasome and contribute to the pathogenicity of V. fluvialis. To examine this possibility, we constructed VFH mutant and complement strains and demonstrated that V. fluvialis-induced IL-1β production and cytotoxicity in human monocytic THP-1 cells and mouse macrophages is attributed to VFH. To evaluate the role of VFH in vivo, we infected adult C57BL/6 mice intraperitoneally and suckling C57/B6 mice orally with various strains. The mice treated with 10⁸ CFU wild-type V. fluvialis or cell-free supernatant containing VFH induced significantly higher IL-1β production in peritoneal lavage fluid or in colon compared with those infected with the mutant strain, while no effect on TNF and IL-6 production was observed at day 5 or 24 h post-infection. VFH contributed to pathological changes and IL-1β release independent of colonization of V. fluvialis in the colon. VFH has no effect on the synthesis of pro-IL-1β, but rather it triggers the processing of pro-IL-1β into IL-1β. Furthermore, using deficient mouse strains, we verified that V. fluvialis-induced IL-1β is mediated through activation of Caspase-1 and the NLRP3 inflammasome ex vivo. Confocal microscopy suggests that VFH contributes to cathepsin B release. Furthermore, V. fluvialis-induced IL-1β secretion requires potassium (K⁺) efflux and reactive oxygen species production. Our results provide new evidence for the role of VFH in the activation of the NLRP3 inflammasome and pathogenesis in response to V. fluvialis infection. Summary Sentence: Vibrio fluvialis-secreted hemolysin induces IL-1β secretion through the activation of the NLRP3 inflammasome and contributes to the pathogenicity of V. fluvialis.

Slow transit constipation (STC) is a prevalent gastrointestinal condition with slow transit, and some probiotics can effectively relieve constipation, but the exact mechanisms have not been fully understood. In this study, we evaluate the impact of Lactiplantibacillus plantarum GUANKE (GUANKE) on diphenoxylate-induced slow transit constipation and speculate on the underlying mechanisms in a mouse model. Administration of L. plantarum GUANKE alleviated constipation indexes, including defecation time, fecal output and water content, and gastrointestinal transit ratio. In addition, GUANKE restored the protein expression of constipation-related intestinal factors (aquaporins (AQPs) and interstitial Cajal cells (ICCs)) in colon tissues measured using immunofluorescence staining; regulated the neurotransmitters and hormones, such as increased levels of 5-hydroxytryptamine, substance P, and motilin; and decreased levels of vasoactive intestinal peptide and nitric oxide in serum, as measured by an ELISA. 16S rRNA and correlation analysis of feces indicated that GUANKE administration effectively reduced constipation-induced Prevotella enrichment and suggested a potential contribution of Prevotella to diphenoxylate-induced STC in mice. GUANKE had no effect on short-chain fatty acids (SCFAs) in cecum content. This study revealed that GUANKE may alleviate constipation in mice through regulating intestinal neurotransmitter and hormone release and altering specific bacterial taxa, rather than by affecting SCFAs and the diversity of microbiota in the gut. Further research is needed to confirm if the findings observed in this study will be consistent in other animal studies or clinical trials.

Influenza, a severe respiratory disease caused by the influenza virus, has long been a prominent threat to human health. An increasing number of studies have demonstrated that oral administration with probiotics may increase the immune response to lung infection via the gut-lung axis leading to the alleviation of the pulmonary disease. In this study, we evaluated the effects of oral administration of Pediococcus pentosaceus MIANGUAN2 (MIANGUAN2) on influenza infection in a mouse model. Our results showed that oral administration of MIANGUAN2 significantly improved weight loss, lung index, and lung pathology, and decreased lung viral load of influenza-infected mice. Additionally, MIANGUAN2-treated mice showed significantly lower levels of TNF-α, IL-1β, IFN-γ, and IL-12p70 and higher production of IL-4 in the lung. In accordance with this, the transcriptome analysis of the lung indicated that MIANGUAN2-treated mice had reduced expression of inflammation markers, such as TNF, apoptosis, and the NF-Kappa B pathway. Furthermore, the administration of MIANGUAN2 restored the SCFAs profiles through regulating the gut microbiota. SCFA-producing bacteria, such as p_Firmicutes, f_Lachnospiraceae, and f_Ruminococcaceae, were enriched in the MIANGUAN2-treated group compared with PBS-treated group. Consistently, the concentrations of SCFAs in the MIANGUAN2 group were significantly higher than those in the PBS-treated group. In addition, the concentrations of SCFAs were positively correlated with SCFA-producing bacteria, such as Ruminococcus, while being negatively correlated with the virial titers and proinflammatory cytokines. In conclusion, this animal study suggests that Pediococcus pentosaceus MIANGUAN2 may alleviate the influenza infection by altering the gut microbiota composition and increasing the levels of gut microbiota-derived SCFAs.

Ulcerative colitis (UC) is a chronic relapsing intestinal disease with complex pathogenesis. The increasing morbidity and mortality of UC become a global public health threat. Baitouweng decoction (BD), a formulated prescription of Traditional Chinese Medicine, has been applied to cure UC for many centuries. However, the therapeutic efficacy and working mechanisms of this medicine are not well studied. In this study we determined whether Pulsatillae radix, one of four ingredients in BD, had a therapeutic effect on colitis. And explore the underlying mechanism of Pulsatilla chinensis (Bunge) Regel radix in the improvement of DSS-induced colitis in mice model. The active compounds of Pulsatilla chinensis was identified by UPLC. The composition of the mice's cecum microbiota was determined by 16S rRNA sequencing. And gene expression profile of colon was detected by transcriptome. The results showed that Pulsatillae radix significantly improved the clinical symptom, prevented the shorten of colon length, and decreased the diseased activity index (DAI) in an 3 % DSS-induced ulcerative colitis mouse model. We found that Pulsatillae radix reversed the dysbiosis of gut microbiota as evidenced by increase in the relative abundance of Bacteroidetes, Deferribacteres, and Proteobacteria phyla and decrease in Firmicutes, as well as by decrease in the genera levels of Bacteroides, Parabacteroides, Prevotella, Mucispirillum, Coprococcus, Oscillospira, and Escherichia. The results of transcriptome showed Pulsatillae radix administration led to 128 genes up-regulation, and 122 genes down-regulation, up-regulate NOD-like receptor signaling pathway, down-regulate Cytokine-cytokine receptor interaction, and TNF and IL-17 signaling pathways. in this study, we demonstrate Pulsatillae radix alleviates DSS-induced colitis probably via modulating gut microbiota and inflammatory signaling pathway in DSS-induced colitis mouse model.