Emerging evidence shows that disrupted gut microbiota-bile acid (BA) axis is critically involved in the development of neurodegenerative diseases. However, the alterations in spatial distribution of BAs among different brain regions that command important functions during aging and their exact roles in aging-related neurodegenerative diseases are poorly understood. Here, we analyzed the BA profiles in cerebral cortex, hippocampus, and hypothalamus of young and natural aging mice of both sexes. The results showed that aging altered brain BA profiles sex- and region- dependently, in which TβMCA was consistently elevated in aging mice of both sexes, particularly in the hippocampus and hypothalamus. Furthermore, we found that aging accumulated-TβMCA stimulated microglia inflammation in vitro and shortened the lifespan of C. elegans, as well as behavioral impairment and neuroinflammation in mice. In addition, metagenomic analysis suggested that the accumulation of brain TβMCA during aging was partially attributed to reduction in BSH-carrying bacteria. Finally, rejuvenation of gut microbiota by co-housing aged mice with young mice restored brain BA homeostasis and improved neurological dysfunctions in natural aging mice. In conclusion, our current study highlighted the potential of improving aging-related neuro-impairment by targeting gut microbiota-brain BA axis.

BACKGROUND: There have been reports that elobixibat improves bowel movements in patients with chronic constipation. However, no studies have been conducted to date to examine bowel movements after the administration of elobixibat in patients with chronic constipation in terms of the presence or absence of the gallbladder. In this study, we examined the frequency of bowel movements and stool forms in patients with gallbladders and post-cholecystectomy patients before and after the administration of elobixibat for chronic constipation.
METHODS: Elobixibat 10 mg was administered to treat chronic constipation in 40 patients with gallbladders and 18 patients who underwent cholecystectomy. The frequencies of bowel movements one week before and after elobixibat administration were compared between the two groups, using the Bristol Stool Form Scale (BSFS).
RESULTS: No significant difference in patient background with or without cholecystectomy was noted between the groups. In patients with gallbladders, the pre-dosing mean frequency of bowel movements was 2.389 ± 0.502 with BSFS of 2.179 ± 0.721 and the post-dosing mean frequency of bowel movements was 4.308 ± 1.151 with BSFS of 3.718 ± 1.521, indicating significant improvement in bowel movements (p < 0.001). In post-cholecystectomy patients, the pre-dosing mean frequency of bowel movements was 2.389 ± 0.502 with BSFS of 2.222 ± 0.647 and the post-dosing mean frequency of bowel movements was 4.222 ± 1.734 with BSFS of 3.333±1.237, indicating significant improvement in bowel movements (p < 0.001). No significant difference in bowel movements was noted between patients with or without the gallbladder.
CONCLUSIONS: Elobixibat is useful in improving the bowel movements of patients with chronic constipation. No significant difference was noted in the improvement of bowel movements due to cholecystectomy. It was suggested that even post-cholecystectomy patients could obtain therapeutic effects similar to patients with gallbladders.

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UNASSIGNED: Organic anion-transporting polypeptides (OATPs) play a crucial role in the transport of bile acids and bilirubin. In our previous study, interleukin 6 (IL-6) reduced OATP1B3 levels in cholestatic disease. However, it remains unclear whether IL-6 inhibits OATP1B1 expression in cholestatic diseases. This study aimed to investigate whether IL-6 can inhibit OATP1B1 expression and explore the underlying mechanisms.
UNASSIGNED: The effect of stimulator of interferon genes (STING) signaling on inflammatory factors was investigated in a cholestatic mouse model using RT-qPCR and enzyme-linked immunosorbent assay. To assess the impact of inflammatory factors on OATP1B1 expression in hepatocellular carcinoma, we analyzed OATP1B1 expression by RT-qPCR and Western Blot after treating PLC/PRF/5 cells with TNF-α, IL-1β, and IL-6. To elucidate the mechanism by which IL-6 inhibits OATP1B1 expression, we examined the expression of the OATP1B1 regulator TCF4 in PLC/PRF/5 and HepG2 cells using RT-qPCR and Western Blot. The interaction mechanism between β-catenin/TCF4 and OATP1B1 was investigated by knocking down β-catenin/TCF4 through siRNA transfection.
UNASSIGNED: The STING inhibitor decreased inflammatory factor levels in the cholestatic mouse model, with IL-6 exhibiting the most potent inhibitory effect on OATP1B1. IL-6 downregulated β-catenin/TCF4, leading to decreased OATP1B1 expression. Knocking-down β-catenin/TCF4 counteracted the β-catenin/TCF4-mediated repression of OATP1B1.
UNASSIGNED: STING-mediated IL-6 up-regulation may inhibit OATP1B1, leading to reduced transport of bile acids and bilirubin by OATP1B1. This may contribute to altered pharmacokinetics in patients with diseases associated with increased IL-6 production.

BACKGROUND: Prior researches have highlighted inverse associations between levels of circulating very-long chain saturated fatty acids (VLCSFAs) and coronary heart disease (CHD). However, the intricate links involving VLCSFAs, gut microbiota, and bile acids remain underexplored.
OBJECTIVE: This study examined the association of erythrocyte VLCSFAs with CHD incidence, focusing on the mediating role of gut microbiota and fecal bile acids.
METHODS: This 10-year prospective study included 2383 participants without CHD at baseline. Erythrocyte VLCSFAs (arachidic acid [C20:0], behenic acid [C22:0], and lignoceric acid [C24:0]) were measured using gas chromatography at baseline and 274 CHD incidents were documented in triennial follow-ups. Gut microbiota in 1744 participants and fecal bile acid metabolites in 945 participants were analyzed using 16S rRNA sequencing and UPLC-MS/MS at middle-term.
RESULTS: The multivariable-adjusted HRs (95%CI) for CHD incidence in highest vs. lowest quartiles were 0.87 (0.61, 1.25) for C20:0, 0.63 (0.42,0.96) for C22:0, 0.59 (0.41,0.85) for C24:0, and 0.57 (0.39, 0.83) for total VLCSFAs. Participants with higher total VLCSFA levels exhibited increased abundances of Holdemanella, Coriobacteriales Incertae Sedis spp., Ruminococcaceae UCG-005 and UCG-010, and Lachnospiraceae ND3007 group. These five genera generated microbial score (ODMS) that accounted for 11.52% of the total VLCSFAs-CHD association (Pmediation =0.018). Bile acids tauro_α_ and tauro_β_muricholic acid (T_α_ and T_β_MCA) were inversely associated with ODMS and positively associated with incident CHD. Opposite associations were found for glycolithocholic acid (GLCA), glycodeoxycholic acid (GDCA). Mediation analyses indicated that GLCA, GDCA, and T_α_ and T_β_MCA explained 56.40%, 35.19%, and 26.17% of the ODMS-CHD association, respectively (Pmediation =0.002, 0.008, and 0.020).
CONCLUSIONS: Elevated erythrocyte VLCSFAs are inversely associated with CHD risk in the Chinese population, with gut microbiota and fecal bile acid profiles potentially mediating this association. The identified microbiota and bile acid metabolites may serve as potential intervention targets in future studies.
BACKGROUND: NCT03179657.

Cordyceps guangdongensis, a novel edible mushroom in China, has shown many positive health effects. In this study, we extracted the C. guangdongensis polysaccharides (CGP) from the fruiting bodies, and investigated the mechanism for CGP improved high-fat diet-induced (HFDI) metabolic diseases. We found that CGP notably reduced fat mass, improved blood lipid levels and hepatic damage, and restored the gut microbiota dysbiosis induced by high-fat diet (HFD). Metabolome analyses showed that CGP changed the composition of bile acids, and regulated HFDI metabolic disorder in hepatic tissue. Transcriptome comparison showed that the improvement of hepatic steatosis for CGP was mainly related to lipid and carbohydrate metabolism. Association analysis result revealed that Odoribacter, Bifidobacterium and Bi. pseudolongum were negatively correlated to fat and blood lipid indicators, and were significantly associated with genes and metabolites related to carbohydrate and lipid metabolism. Collectively, these results indicate that CGP may be a promising supplement for the treatment of obesity and related metabolic diseases.

Inflammatory bowel disease (IBD) is a refractory disease with immune abnormalities and pathological changes. Intestinal macrophages are considered to be the main factor in establishing and maintaining intestinal homeostasis. The immunoregulatory and anti-inflammatory activity of fibrinogen-like protein 2 (FGL2) can regulate macrophage polarization. However, its function in IBD is unclear. In this study, we explored the effect of FGL2 on macrophage polarization, autophagy, and apoptosis in bone marrow-derived macrophages (BMDMs) treated with lipopolysaccharide (LPS) and further investigated changes in the intestinal barrier, flora, and bile acid in dextran sodium sulfate (DSS)-treated mice. Our results demonstrated that FGL2-/- weakened ERK signaling to promote M1 polarization and upregulate inflammation, autophagy, and apoptosis in LPS-stimulated BMDMs. rFGL2 treatment reversed these effects. FGL2-/- mice exhibited higher sensitivity to DSS exposure, with faster body weight loss, shorter colon lengths, and higher disease activity index (DAI) values. rFGL2 treatment protected against experimental ulcerative colitis (UC), restrained excessive autophagy, apoptosis, and improved gut barrier impairment. Gut microbiota structure and bile acid homeostasis were more unbalanced in FGL2-/- DSS mice than in wild-type (WT) DSS mice. rFGL2 treatment improved gut microbiota structure and bile acid homeostasis. Altogether, our results established that FGL2 is a potential therapeutic target for IBD.

METHODS: This study aims to identify the gut enterotypes that explain differential responses to intervention with whole grain rye by proposing an \"enterotype - metabolic\" model.
RESULTS: A 12-week randomized controlled trial is conducted in Chinese adults, with 79 subjects consuming whole grain products with fermented rye bran (FRB) and 77 consuming refined wheat products in this exploratory post-hoc analysis. Responders or non-responders are identified according to whether blood glucose decreased by more than 10% after rye intervention. Compared to non-responders, responders in FRB have higher baseline Bacteroides (p < 0.001), associated with reduced blood glucose (p < 0.001), increased Faecalibacterium (p = 0.020) and Erysipelotrichaceae_UCG.003 (p = 0.022), as well as deceased 7β-hydroxysteroid dehydrogenase (p = 0.033) after intervention. The differentiated gut microbiota and metabolites between responders and non-responders after intervention are enriched in aminoacyl-tRNA biosynthesis.
CONCLUSIONS: The work confirms the previously suggested importance of microbial enterotypes in differential responses to whole grain interventions and supports taking enterotypes into consideration for improved efficacy of whole grain intervention for preventing type 2 diabetes. Altered short-chain fatty acids and bile acid metabolism might be a potential mediator for the beneficial effects of whole grain rye on glucose metabolism.

Shigella spp. are highly pathogenic members of the Enterobacteriaceae family, causing ∼269 million cases of bacillary dysentery and >200,000 deaths each year. Like many Gram-negative pathogens, Shigella rely on their type three secretion system (T3SS) to inject effector proteins into eukaryotic host cells, driving both cellular invasion and evasion of host immune responses. Exposure to the bile salt deoxycholate (DOC) significantly enhances Shigella virulence and is proposed to serve as a critical environmental signal present in the small intestine that prepares Shigella\'s T3SS for efficient infection of the colonic epithelium. Here, we uncover critical mechanistic details of the Shigella-specific DOC signaling process by describing the role of a π-helix secondary structure element within the T3SS tip protein IpaD. Biophysical characterization and high-resolution structures of IpaD mutants lacking the π-helix show that it is not required for global protein structure, but that it defines the native DOC binding site and prevents off target interactions. Additionally, Shigella strains expressing the π-helix deletion mutants illustrate the pathogenic importance of its role in guiding DOC interaction as flow cytometry and gentamycin protection assays show that the IpaD π-helix is essential for DOC-mediated apparatus maturation and enhanced invasion of eukaryotic cells. Together, these findings add to our understanding of the complex Shigella pathogenesis pathway and its evolution to respond to environmental bile salts by identifying the π-helix in IpaD as a critical structural element required for translating DOC exposure to virulence enhancement.

UNASSIGNED: Bile acids (BAs), products of gut microbiota metabolism, have long been implicated in atherosclerotic disease pathogenesis. Characterizing the serum bile acid profile and exploring its potential role in carotid atherosclerosis (CAS) development are crucial tasks.
UNASSIGNED: In this study, we recruited 73 patients with CAS as the disease group and 77 healthy individuals as the control group. We systematically measured the serum concentrations of 15 bile acids using ultrahigh-performance liquid chromatography-mass spectrometry (UPLC-MS/MS). Multivariate logistic regression and least absolute shrinkage and selection operator (LASSO) regression were applied to analyze the impact of bile acids on the disease and select the key BAs. The possible molecular mechanism was elucidated by network pharmacology.
UNASSIGNED: (1) The BA profile of patients with CAS significantly differed. (2) Multifactorial logistic regression analysis identified elevated levels of GCDCA (OR: 1.01, P < 0.001), DCA (OR: 1.01, P = 0.005), and TDCA (OR: 1.05, P = 0.002) as independent risk factors for CAS development. Conversely, GCA (OR: 0.99, P = 0.020), LCA (OR: 0.83, P = 0.002), and GUDCA (OR: 0.99, P = 0.003) were associated with protective effects against the disease. GCA, DCA, LCA, and TDCA were identified as the four key BAs. (3) TNF, FXR, GPBAR1, ESR1 and ACE were predicted to be targets of BAs against AS. These four BAs potentially impact AS progression by triggering signaling pathways, including cAMP, PPAR, and PI3K-AKT pathways, via their targets.
UNASSIGNED: This study offers valuable insights into potential therapeutic strategies for atherosclerosis that target bile acids.