Enhancement of gut barrier integrity by a Bacillus subtilis secreted metabolite through the GADD45A-Wnt/β-catenin pathway

Isobutyrate Confers Resistance to Inflammatory Bowel Disease through Host-Microbiota Interactions in Pigs

Supplementation with short-chain fatty acids (SCFAs) is a potential therapeutic approach for inflammatory bowel disease (IBD). However, the therapeutic effects and mechanisms of action of isobutyrate in IBD remain unclear. Clinical data indicate that the fecal levels of isobutyrate are markedly lower in patients with Crohn's disease than in healthy controls. Compared with healthy mice and healthy pigs, mice and pigs with colitis presented significantly lower isobutyrate levels. Furthermore, the level of isobutyrate in pigs was significantly negatively correlated with the disease activity index. We speculate that isobutyrate may play a crucial role in regulating host gut homeostasis. We established a model of dextran sulfate sodium-induced colitis in pigs, which have gastrointestinal structure and function similar to those of humans; we performed multiomic analysis to investigate the therapeutic effects and potential mechanisms of isobutyrate on IBD at both the animal and cellular levels and validated the results. Phenotypically, isobutyrate can significantly alleviate diarrhea, bloody stools, weight loss, and colon shortening caused by colitis in pigs. Mechanistically, isobutyrate can increase the relative abundance of Lactobacillus reuteri, thereby increasing the production of indole-3-lactic acid, regulating aryl hydrocarbon receptor expression and downstream signaling pathways, and regulating Foxp3+ CD4+ T cell recruitment to alleviate colitis. Isobutyrate can directly activate G protein-coupled receptor 109A, promote the expression of Claudin-1, and improve intestinal barrier function. In addition, isobutyrate can increase the production of intestinal SCFAs and 3-hydroxybutyric acid and inhibit the TLR4/MyD88/NF-κB signaling pathway to suppress intestinal inflammation. In conclusion, our findings demonstrate that isobutyrate confers resistance to IBD through host-microbiota interactions, providing a theoretical basis for the use of isobutyrate in alleviating colitis.

Loss of diurnal oscillatory rhythms in gut microbiota correlates with progression of atherosclerosis

Circadian rhythms in gut microbiota composition are crucial for metabolic function and disease progression, yet the diurnal oscillation patterns of gut microbiota in atherosclerotic cardiovascular disease (ASCVD) and their role in disease progression remain unknown. Here, we investigated gut bacterial dynamics in Apoe-/- mice over 24 hours and elucidated dynamic changes in fecal microbiota composition and function among C57BL/6 and Apoe-/- mice with standard chow diet or high-fat/high-cholesterol diet under ad libitum conditions. Compared with C57BL/6 mice, Apoe-/- mice exhibited significant differences in fecal microbial composition. Rhythmicity analysis revealed that the temporal dynamics of fecal microbiota composition and function in Apoe-/- mice differed significantly from those in C57BL/6 mice, particularly in B. coccoides-dominated oscillatory modules. Functional annotation showed that rhythmic B. coccoides strains inhibited ASCVD progression by enhancing intestinal and endothelial barrier functions. These findings demonstrate that diurnal oscillations in gut microbiota are closely associated with ASCVD progression and provide new insights for microbiota-targeted precision therapies.

Lactobacillus reuteri alleviates diquat induced hepatic impairment and mitochondrial dysfunction via activation of the Nrf2 antioxidant system and suppression of NF-κB inflammatory response

Accumulating evidence has shown that elevated oxidative stress and inflammatory response leads to hepatic impairment and dysfunction of hens during the aging process. This study was conducted to investigate the potential regulatory mechanisms of Lactobacillus reuteri (L. reuteri) in alleviating hepatic oxidative stress and dysfunction induced by diquat (DQ) exposure. A total of 480 48-wk-old Jingbai hens were randomly assigned to 4 groups: control group (Con), L. reuteri group (L.R), diquat-challenged group (DQ), and L. reuteri protective group (L.R+DQ). The results demonstrated that DQ exposure induced oxidative damages and lipid metabolism disorders manifested as the elevated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, triglyceride (TC) contents in serum and lipid accumulation in liver. L. reuteri supplementation alleviated DQ-induced liver oxidative injury, reflected by repairing the morphology of liver and decreasing the AST and ALT activities in serum. L. reuteri decreased the hepatic malonaldehyde (MDA) accumulation and enhanced the total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) activities in liver through regulating the nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1) mediated antioxidant system. In addition, L. reuteri curtailed reactive oxygen species (ROS) production and mitigated the depletion of membrane potential and thus recovering mitochondrial function disturbed by DQ challenge. Moreover, L. reuteri inhibited hepatic toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-kappa B (NF-κB) pathway activation, downregulated the pro-inflammatory-response-related gene expressions (IL-1β, TNF-α, and IL-6) and the phosphorylation levels of IκBα, and p65 in liver and thus reducing hepatic inflammatory response and apoptosis. Overall, the findings indicate that L. reuteri provides significant protection against oxidative stress, mitochondrial impairment, inflammatory response and apoptosis caused by DQ in laying hens, and highlight its potential as a therapeutic probiotic for alleviating oxidative stress and mitochondrial dysfunction to prolong the health of aging poultry.

GADD45A suppression contributes to cardiac remodeling by promoting inflammation, fibrosis and hypertrophy

The growth arrest and DNA damage inducible 45A (GADD45A) is a multifaceted protein associated with stress signaling and cellular injury. Aside its well-established tumor suppressor activity, recent studies point to additional roles for GADD45A, including the regulation of catabolic and anabolic pathways, or the prevention of inflammation, fibrosis, and oxidative stress in some tissues and organs. However, little is known about its function in cardiac disease. In this study, we aimed to evaluate the role of GADD45A in the heart by using mice with constitutive and systemic deletion of Gadd45a, and cardiac cells of human origin. Gadd45a suppression in knockout mice triggered cardiac fibrosis, inflammation, and apoptosis, and these changes correlated with an hyperactivation of the pro-inflammatory and pro-fibrotic transcription factors activator protein-1 (AP-1), nuclear factor-κB (NF-κB), and signal transducer and activator of transcription 3 (STAT3). Deletion of Gadd45a also resulted in substantial cardiac hypertrophy, which negatively impacted cardiac morphology and function in knockout mice. Consistent with this, GADD45A overexpression in human AC16 cardiomyocytes partially prevented the inflammatory and fibrotic responses induced by tumor necrosis factor-α (TNF-α). Overall, data presented in this study highlight an important role for GADD45A in the heart, since it may prevent inflammation, fibrosis, and apoptosis, and, by this means, preserve cardiac function and performance. Since fibrosis and inflammation are crucial in the progression of cardiac hypertrophy and subsequent heart failure, these results suggest that promoting the activity of this protein might be a promising therapeutic strategy to slow down the progression of these deleterious diseases.

Comparative Analysis of Short-Chain Fatty Acids and the Immune Barrier in Cecum of Dahe Pigs and Dahe Black Pigs

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.