A high-fat diet leads to metabolic disturbances, which are important factors in the development of obesity. Gut microbial composition and diversity are altered by a high-fat diet. In general, a high-fat diet resulted in increased Firmicutes abundance and decreased alpha diversity. Bile acids (BAs) are involved in the digestion and absorption of fats in the small intestine and are also the metabolic substrates of microorganisms with bile salt hydrolase (BSH) activity. High-fat diets (HFDs) have been shown to alter gut microbiota composition and BA profiles in murine models. Similarly, probiotic supplementation reverses HFD-induced adverse effects. This review focuses on the energy composition characteristics of a high-fat diet and its effects on body weight, plasma lipid-related biochemical markers, changes in gut microbiome characteristics, and the important role of BAs. The regular mechanism by which a high-fat diet affects the intestinal microenvironment was attempted to be found.

Growth stage is a key factor influencing the composition and richness of the porcine gut microbiota. The stage-specific alterations in gut microbiota of indigenous Chinese pig breeds and cultivated breeds remain to be elucidated. This study conducted 16S rRNA sequencing analysis on fecal microbiota from Dahe black pigs across distinct growth stages. Samples included lactating sows, suckling piglets, weaned piglets, pigs weighing 50–100 kg, pigs weighing 120–150 kg, and pigs weighing > 200 kg. The results indicated that Escherichia shigella (12.4% vs. 16.2%), Lactobacillus (5.9% vs. 6.3%), and Rikenellaceae RC9 gut group (3.9% vs. 4.2%) were dominant genera shared between lactating sows and suckling piglets. The relative abundance of Eubacterium brachy group was significantly higher in lactating sows, whereas Flavonifractor was significantly lower compared to suckling piglets (p < 0.05). Compared to pigs weighing > 120 kg, lactating sows exhibited 22 differentially abundant genera, including Escherichia shigella, Cloacibacillus, Fusobacterium, Faecalibacterium, and Prevotella (p < 0.05). In suckling piglets, Firmicutes and Bacteroidota constituted 47.4% and 27.3% of the microbiota, respectively. Their relative abundance increased with body weight, reaching 52.6% and 33.3% in pigs weighing > 200 kg. Proteobacteria decreased from 17.3% in suckling piglets to 2.0% in >200 kg pigs. Spirochaetota declined from 2.5% in suckling piglets to 0.9% in weaned piglets and then increased to 6.9% in >200 kg pigs. Lactobacillus peaked at 15.7% in weaned piglets, while Escherichia shigella reached its maximum (16.2%) in suckling piglets, both gradually declining thereafter. Streptococcus abundance remained relatively stable (1.1% in suckling piglets; 4.5% in weaned piglets). Prevotellaceae NK3B31 group registered 2.9% in suckling piglets, increased to 7.1% in weaned piglets, and then declined to 2.6% in >200 kg pigs. Mitsuokella, Bilophila, Succinivibrio, Romboutsia, and Desulfovibrio were identified as the top five genera discriminating suckling and weaned piglets. Similarly, Lachnospiraceae XPB1014 group, Clostridium sensu stricto 1, Turicibacter, Quinella, and p 1088 a5 gut group were key discriminators between weaned piglets and 50–100 kg pigs. These identified microbial taxa represent potential candidate targets for modulating the developmental timing of growth phases in pigs, offering possibilities for either advancing or delaying specific physiological timepoints.

The intestinal immune barrier is a developed and complex immune system, and there is a fine synergy between it and the induced immune response. Short-chain fatty acids (SCFAs) are the main metabolites of intestinal microbial fermentation. In the cecum of pigs, SCFAs not only provide energy for the host but also participate in regulating the function of the intestinal immune system. The purpose of this study was to explore the mechanism of SCFAs in the regulation of immune gene expression in porcine cecum. SCFAs content and mRNA expression levels of immune genes in cecum were detected, and Gene Ontology (GO) function annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, Protein-Protein Interaction Networks (PPI) network construction, key gene identification, and correlation analysis were performed. The results showed that the content of SCFAs in the cecum of Dahe black pigs (DHB) was lower than that of Dahe pigs (DH). There were significant differences in mRNA expression of some immune genes between the two groups. GO functional annotation found terms related to cytokine activity and protein heterodimerization activity; the KEGG pathway was enriched in several pathways related to intestinal immunity. The PPI network identified Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Interleukin-17A (IL-17A), and Interleukin-18 (IL-18) as key proteins. The correlation analysis showed that acetic acid and valerate were closely related to the immune response. In this study, the differences in cecal short-chain fatty acids and the immune barrier between Dahe pigs and Dahe black pigs were compared, which provided a theoretical basis for improving the intestinal immunity of pigs.

Sepsis is associated with dysregulated bile acid profiles, gut microbiota dysbiosis, and impaired intestinal barrier function. This study investigated the preventive effects and underlying mechanisms of taurocholic acid (TCA) against lipopolysaccharide (LPS)-induced systemic acute inflammation in mice using hematoxylin-eosin (HE), periodic acid-Schiff (PAS), qPCR, ELISA kits, 16S rRNA sequencing and GC-MS. TCA pretreatment (20 mg/kg TCA, TL20; 40 mg/kg TCA, TL40; 60 mg/kg TCA, TL60) mitigated the exacerbation of LPS-induced damage to physical, chemical, and immune barrier functions in the ileum and colon. The TL60 group showed significantly increased mRNA expression of ileal and colonic ZO-1, ZO-2, Claudin-1, Occludin, SC, J chain, CD40, PIgR, and IgA and protein expression of IgA, SIgA, IgG, and IgM in comparison with LCG group (p < 0.05). Notably, TCA upregulated mRNA expression of FXR and TGR5, while suppressing the NF-κB pathway, suggesting a potential anti-inflammatory mechanism. Hepatic concentrations of TCA and taurohyocholic acid (THCA) were significantly lower in the LCG group than in the CG group but elevated in the colon; TCA pretreatment effectively prevented the abnormal accumulation of TCA and THCA in the colon (p < 0.05). Furthermore, TCA pretreatment significantly increased the relative abundance of bile acid-metabolizing genera in the colonic microbiota, including Desulfovibrio, Lactobacillus, Faecalibaculum, Bifidobacterium, Turicibacter, and Anaerostipes. These findings demonstrated that TCA pretreatment alleviates LPS-induced intestinal barrier injury and inflammatory responses by preventing intestinal barrier dysfunction, reducing bile acid retention, and modulating colonic microbial composition.

Background: Ulcerative colitis (UC) is a chronic inflammatory disease of the colon with a rising global incidence. Natural conjugated taurocholic acid (TCA) possesses anti-inflammatory properties and shows potential therapeutic effects against UC, although the underlying mechanisms remain unclear. Methods: This study employed an integrative approach—combining network pharmacology, bioinformatics, machine learning, immune infiltration analysis, and molecular docking—to investigate the therapeutic mechanisms of TCA in UC. UC-related gene expression datasets were obtained from the Gene Expression Omnibus (GEO) database, and potential TCA targets were predicted using the Comparative Toxicogenomics Database (CTD) and TargetNet platforms. Differentially expressed genes (DEGs) were identified and analyzed via GO and KEGG enrichment analyses. Results: Four machine learning algorithms (XGBoost, RF, SVM, and NNet) were used to identify six hub genes (TGM2, MMP9, ABCB1, NOS2, ABCG2, CASP1), which were further validated using an artificial neural network. Immune infiltration analysis with CIBERSORT revealed significant alterations in immune cell populations in UC tissues. Further validation through an artificial neural network model confirmed their predictive ability. The enrichment analysis of the hub genes highlighted their roles in immune-related pathways, while the immune infiltration analysis indicated significant differences in immune cell populations between ulcerative colitis tissues and control tissues. The molecular docking results showed that the binding energies of these six proteins to TCA were lower than −5 kcal/mol, with TGM2 having the strongest binding affinity (−10 kcal/mol). The intervention of TCA on colitis mice could improve the inflammatory response by regulating the expression of the TGM2 gene. Conclusions: In conclusion, this study suggests that taurocholate alleviates ulcerative colitis by targeting key genes such as TGM2 and modulating immune-related pathways, providing a novel basis for future therapeutic exploration.

Intramuscular fat (IMF) is a crucial determinant of pork quality, influencing tenderness, flavor, and consumer preferences, yet selective breeding has reduced its levels in modern pigs. This review explores the molecular and cellular mechanisms of IMF deposition, including progenitor cell differentiation via pathways like Wnt/β-catenin and PPARγ, and advances in non-invasive detection methods such as hyperspectral imaging and Raman spectroscopy. It highlights correlations and causal links between the gut microbiota composition and IMF, established through omics analyses, fecal microbiota transplantation, and germ-free models. Key microbial metabolites, including short-chain fatty acids (SCFAs) and bile acids, modulate lipid metabolism bidirectionally via signaling receptors like GPR43, FXR, and TGR5. Future research should integrate multi-omics and develop probiotics to enhance IMF efficiency for sustainable pork production.