Mouse Abdominal Fat Depots Reduced by Butyric Acid-Producing Leuconostoc mesenteroides

Neurotransmitter metabolites in milk ferments of Leuconostoc mesenteroides regulate temperature-sensitive heartbeats in an ex ovo model

Accumulated evidence has supported the probiotic activity of Leuconostoc mesenteroides (L. mesenteroides) which can yield beneficial metabolites via fermentation. Here, bovine milk rich in phenylalanine（PHE) was used as a source for fermentation of L. mesenteroides. The complexes of PHE with bacterial phenylalanine hydroxylase (PheH) at two temperatures were revealed via molecular dynamics simulation. Two carbon hydrogen bonds and a Pi-Alkyl T-shaped interaction were newly formed at an active site of the PheH-PHE complex. The PheH interacted with two different hydrogen atoms in an amine of PHE via conventional hydrogen bonds at 37 °C, a temperature that accelerated the milk fermentation of L. mesenteroides. Twenty-eight metabolites including various neurotransmitters in fermented milk were identified and quantified by liquid chromatography coupled to quadrupole ion trap (Q-Trap) tandem mass spectrometry. Ex ovo injection of milk ferments into the yolk sac of chicken embryos enhanced a rising temperature-induced increase in heartbeats towards the normal resting level. The neurotransmitter-rich milk ferments hold potential for using to adjust energy metabolism, referred from heart rates, during fluctuating temperature conditions.

Fecal microbiota transplantation revealed the function of folic acid on reducing abdominal fat deposition in broiler chickens mediated by gut microbiota

Excess abdominal fat reduces carcass yield and feed conversion ratio, thereby resulting in significant economic losses in the poultry industry. Our previous study demonstrated that dietary addition of folic acid reduced fat deposition and changed gut microbiota and short-chain fatty acid. However, whether folic acid regulating abdominal fat deposition was mediated by gut microbiota was unclear. A total of 210 one-day-old broiler chickens were divided into 3 groups including the control (CON), folic acid (FA), and fecal microbiota transplantation (FMT) groups. From 14th day, broiler chickens in CON and FA groups were given perfusion administration with 1 mL diluent daily, while 1 mL fecal microbiota transplantation suspension from FA group prepared before was perfusion in FMT group receiving control diets. The result showed that abdominal fat percentage was significantly lower in FA and FMT groups when compared with CON group (P < 0.05). Morphology analysis revealed that the villus height of jejunum and ileum were significantly higher in FMT group (P < 0.05), and the villus height of jejunum was also significantly higher in FA group (P < 0.05), while the diameter and cross-sectional area (CSA) of adipocytes were significantly decreased in FA and FMT groups when compared with CON group (P < 0.05). Western blot results indicated that the expression levels of FOXO1 and PLIN1 in FMT group were significantly increased (P < 0.05), whereas the expression levels of PPARγ, C/EBPα, and FABP4 were significantly decreased (P < 0.05). Additionally, the Chao1, Observed-species, Shannon and Simpson indexes in FA and FMT groups were significantly higher (P < 0.05), but the microbiota were similar between FMT and FA groups (P < 0.05). LEfSe analysis determined that Lactobacillus, Clostridium and Dehalobacterium were found to be predominant in FA group, while Oscillospira, Shigella, and Streptococcus were the dominant microflora in FMT group. Furthermore, these cecal microbiota were mostly involved in infectious disease, cellular community prokaryotes, cell motility and signal transduction in FA group (P < 0.05), whereas functional capacities involved in signal transduction, cell motility, infectious disease and environment adaptation were enriched significantly of cecal microbiota in FMT group (P < 0.05). In summary, both fecal microbiota transplantation from the broiler chickens of dietary added folic acid and dietary folic acid addition effectively reduced abdominal fat deposition, indicating that the regulatory effect of folic acid on abdominal fat deposition was mediated partly by gut microbiota in broiler chickens.

Protective effect of microbiota-derived short chain fatty acids on vascular dysfunction in mice with systemic lupus erythematosus induced by toll like receptor 7 activation

Our objective was to investigate whether short-chain fatty acids (SCFAs), specifically acetate and butyrate, could prevent vascular dysfunction and elevated blood pressure (BP) in mice with systemic lupus erythematosus (SLE) induced by TLR7 activation using imiquimod (IMQ). Treatment with both SCFAs and dietary fibers rich in resistant starch (RS) or inulin-type fructans (ITF) effectively prevented the development of hypertension and cardiac hypertrophy. Additionally, these treatments improved aortic relaxation induced by acetylcholine and mitigated vascular oxidative stress. Acetate and butyrate treatments also contributed to the maintenance of colonic integrity, reduced endotoxemia, and decreased the proportion of helper T (Th)17 cells in mesenteric lymph nodes (MLNs), blood, and aorta in TLR7-induced SLE mice. The observed changes in MLNs were correlated with increased levels of GPR43 mRNA in mice treated with acetate and increased GPR41 levels along with decreased histone deacetylase (HDAC)- 3 levels in mice treated with butyrate. Notably, the effects attributed to acetate, but not butyrate, were nullified when co-administered with the GPR43 antagonist GLPG-0974. T cell priming and differentiation into Th17 cells in MLNs, as well as increased Th17 cell infiltration, were linked to aortic endothelial dysfunction and hypertension subsequent to the transfer of faecal microbiota from IMQ-treated mice to germ-free (GF) mice. These effects were counteracted in GF mice through treatment with either acetate or butyrate. To conclude, these findings underscore the potential of SCFA consumption in averting hypertension by restoring balance to the interplay between the gut, immune system, and vascular wall in SLE induced by TLR7 activation.

Short Chain Fatty Acids Protect the Cognitive Function of Sepsis Associated Encephalopathy Mice via GPR43

Objective

This study aims to analyze the changes of fecal short chain fatty acids (SCFAs) content and gut microbiota composition in sepsis associated encephalopathy (SAE) mice, further evaluating the effect of SCFAs on cognitive function and the underlying mechanism in SAE mice.

Methods

A total of 55 male adult C57BL/6 mice (2–3 months of age, 20–25 g) were divided into four groups randomly: sham group (n = 10), cecal ligation and puncture group (CLP group, n = 15), CLP+SCFAs group (n = 15), and CLP+SCFAs+GLPG0974 group (n = 15). Seven days after surgery, fecal samples were collected for microbiota composition and SCFA analysis from 6 mice in each group randomly. Behavioral test was applied to assess cognitive impairment at the same time. After that, mice were sacrificed and brain tissue was harvested for inflammatory cytokines analysis.

Results

The levels of acetic acid (.57 ± 0.09 vs 2.00 ± 0.24, p < 0.001) and propionic acid (.32 ± 0.06 vs .66 ± 0.12, p = 0.002) were significantly decreased in the CLP group compared with the sham group. The administration of SCFAs significantly increased the levels of acetic acid (1.51 ± 0.12 vs. 0.57 ± 0.09, p < 0.001) and propionic acid (0.54 ± 0.03 vs. 0.32 ± 0.06, p = 0.033) in CLP+SCFAs group compared with CLP group. Relative abundance of SCFAs-producing bacteria, including Allobaculum (0.16 ± 0.14 vs. 15.21 ± 8.12, p = 0.037), Bacteroides (1.82 ± 0.38 vs. 15.21 ± 5.95, p = 0.002) and Bifidobacterium (0.16 ± 0.06 vs. 2.24 ± 0.48, p = 0.002), significantly decreased in the CLP group compared with the sham group. The behavioral tests suggested that cognitive function was impaired in SAE mice, which could be alleviated by SCFAs pretreatment. ELISA tests indicated that the levels of IL-1β, IL-6, and TNF-α were elevated in SAE mice and SCFAs could lower them. However, the GPR43 antagonist, GLPG0974, could reverse the cognitive protective effect and anti-neuroinflammation effect of SCFAs.

Conclusion

Our study suggested that in SAE, the levels of acetate and propionate decreased significantly, accompanied by gut microbiota dysbiosis, particularly a decrease in SCFAs-producing bacteria. GPR43 was essential for the anti-neuroinflammation and cognitive protective effect of SCFAs in SAE.

Chemogenetic Approaches to Explore the Functions of Free Fatty Acid Receptor 2

Short-chain fatty acids are generated in large amounts by the intestinal microbiota. They activate both the closely related G protein-coupled receptors free fatty acid receptor 2 (FFA2) and free fatty acid receptor 3 (FFA3) that are considered therapeutic targets in diseases of immuno-metabolism. Limited and species-selective small-molecule pharmacology has restricted our understanding of the distinct roles of these receptors. Replacement of mouse FFA2 with a designer receptor exclusively activated by designer drug form of human FFA2 (hFFA2-DREADD) has allowed definition of specific roles of FFA2 in pharmacological and physiological studies conducted both ex vivo and in vivo, whilst overlay of murine disease models offers opportunities for therapeutic validation prior to human studies. Similar approaches can potentially be used to define roles of other poorly characterised receptors.

Production of electricity and reduction of high-fat diet-induced IL-6 by glucose fermentation of Leuconostoc mesenteroides

Electrogenic bacteria can mediate electron transfer to conserve energy and promote growth. To examine bacterial electrogenicity, an L. mesenteroides EH-1 strain was cultured in rich media in the presence and absence of 2% glucose. After 12 h incubation, glucose triggered fermentation of L. mesenteroides EH-1 to produce >10 mmol/l acetate and elicit electricity measured by voltage changes. The electricity production was mediated by glucose fermentation since pre-treatment of L. mesenteroides EH-1 with furfural, a fermentation inhibitor, completely diminished the voltage increases. The deficiency of furfural pre-treated L. mesenteroides EH-1 in electricity production can be restored by the external addition of acetate into the bacterial culture, suggesting the function of acetate as an electron donor. Oral administration of HFD-fed mice with L. mesenteroides EH-1 in the presence or absence of glucose significantly attenuated the high level of pro-inflammatory IL-6 cytokine in blood. Bacterial electricity can be elicited by fermentation. Supplementation of fermenting and electrogenic L. mesenteroides EH-1 may provide a novel approach for the reduction of pro-inflammatory IL-6 cytokine that increased in chronic inflammation, autoimmune diseases, cancers, and infections.