Modulation of the Microbiome-Fat-Liver Axis by Lactic Acid Bacteria: A Potential Alleviated Role in High-Fat-Diet-Induced Obese Mice

Structural characteristics and nonvolatile metabolites of theabrownins and their impact on intestinal microbiota in high-fat-diet-fed mice

This study prepared enzymatic theabrownins (TBs-e), alkaline theabrownins (TBs-a), and Pu-erh tea theabrownins (TBs-f), and investigated whether different preparation processes affected the structures, nonvolatile metabolites, and biofunctional activities of TBs. Structural characterization revealed that TBs were polymeric phenolic compounds rich in hydroxyl and carboxyl groups. Nontargeted metabolomics revealed that amino acids were the primary nonvolatile metabolites in TBs-e and TBs-a, accounting for over 70 % of the total nonvolatile content. TBs-f contained more polyphenols, caffeine, and flavonoids, accounting for 14.2 %, 3.9 %, and 0.8 % of total nonvolatile content, respectively. In vivo, at 560 mg/kg body weight, TBs-f were associated with regulation of blood glucose and lipid concentrations in mice. Moreover, 16S rRNA indicated that at 1120 mg/kg body weight, TBs-a were associated with increased numbers of microbiota linked with hypolipidemic activity. This study explores the impacts of different preparation processes on TBs and provides a theoretical foundation for the understanding of TBs.

Pediococcus acidilactici Y01 reduces HFD-induced obesity via altering gut microbiota and metabolomic profiles and modulating adipose tissue macrophage M1/M2 polarization

Obesity-related metabolic syndrome is intimately associated with infiltrated adipose tissue macrophages (ATMs), gut microbiota, and metabolic disorders. Pediococcus acidilactici holds the potential to mitigate obesity; however, there exist strain-specific functionalities and diverse mechanisms, which deserve extensive exploration. This study aims to explore the potential of P. acidilactici Y01, isolated from traditional sour whey, in alleviating HFD-induced metabolic syndrome in mice and elucidating its underlying mechanism. The results showed that P. acidilactici Y01 could inhibit the increase of body weight gain, the deposition of fat, lipid disorders and chronic low-grade inflammation, improve glucose tolerance and insulin resistance, and could reduce adipose tissue inflammation by decreasing M1-type ATMs and increasing M2-type ATMs. Meanwhile, P. acidilactici Y01 significantly increased the abundance of potentially beneficial intestinal bacteria, such as Akkermansia, Alistipes, Bifidobacterium, Lachnospiraceae_NK4A136_group, Lactobacillus, norank_f__Muribaculaceae, and Parabacteroides, and partially restored the levels of metabolites, such as phosphatidylcholines, glycerophosphocholines, sphingolipids and unsaturated fatty acids. The fecal microbiota transplantation experiment demonstrated that P. acidilactici Y01 ameliorated obesity-related metabolic syndrome by modulating the polarization of M1/M2 ATMs mediated by gut microbiota. Overall, as a dietary supplement, P. acidilactici Y01 has good potential in the prevention and treatment of obesity.

Rumen microbiome and fat deposition in sheep: insights from a bidirectional mendelian randomization study

Rumen microbiotas are known to influence the fat deposition (FD) in sheep, but controversy over causality remains unresolved. Here, we performed microbiome-wide association studies (MWAS), microbiome genome-wide association analysis (mbGWAS) and bidirectional mendelian randomization (MR) analyses on 1,150 sheep with genotype data from whole-genome resequencing, 16S rRNA sequencing and multilevel FD-traits data. We quantified the proportion of individual variation in FD-traits explained by host genetics, rumen microbiota, and their interaction effects. We identified 32 rumen microbiota biomarkers including Bifidobacterium that were associated with FD-traits (Padj <0.05). Further, utilizing five MR methods, we identified eight causal associations between marker genera and FD-traits (Padj <0.05), including Butyrivibrio, Olsenella, p-2534-18B5 gut group, Prevotellaceae UCG-003, and Pseudobutyrivibrio causing forward causal effects on FD, and changes in Flexilinea and Suttonella induced by FD. To our knowledge, this is the inaugural attempt to employ MR in sheep to investigate the causal relationships between gastrointestinal microbiota and complex phenotypes, underscoring the potential for developing interventions related to adipose deposition in sheep from the perspective of the rumen microbiome.

Lactobacillus plantarum alleviates high-fat diet-induced obesity by altering the structure of mice intestinal microbial communities and serum metabolic profiles

Obesity, which is always accompanied by disorders of lipid metabolism and dysbiosis of the gut microbiota, has become a global epidemic recognised by the World Health Organisation, necessitating innovative strategies and a globally accepted agreement on treating obesity and its related complications. Probiotics, as major active ingredients in many foods, offer potential as biological treatments for obesity prevention and management. Lactobacillus plantarum (L. plantarum) possesses a wide range of biological activities and is widely used to alleviate and ameliorate various diseases. This research demonstrated that Lactobacillus plantarum reduces the weight increase and fat build-up caused by a high-fat diet (HFD) in mice, while also improving glucose tolerance and insulin sensitivity in obese mice. Results indicated that L. plantarum effectively controlled the intestinal microbial community's structure, counteracted disruptions in gut flora caused by HFD, normalized the Firmicutes to Bacteroidota ratio (F/B), and decreased the prevalence of detrimental bacteria Desulfovibrio and Clostridia. Serum metabolomics findings indicate notable alterations in serum metabolites across various groups, notably the increased levels of Isoprothiolane and Inosine, key regulators of lipid metabolism disorders and enhancers of fat burning. These differential metabolites were mainly enriched in unsaturated fatty acid biosynthesis, sulfur metabolism, fatty acid biosynthesis, and purine metabolism. Consequently, we propose that L. plantarum has the potential to alter the gut microbial community's composition, positioning it as a promising option for obesity therapy.

(-)-Epicatechin ameliorates type 2 diabetes mellitus by reshaping the gut microbiota and Gut-Liver axis in GK rats

As one of the most abundant plant polyphenols in the human diet, (-)-epicatechin (EC) can improve insulin sensitivity and regulate glucose homeostasis. However, the primary mechanisms involved in EC anti-T2DM benefits remain unclear. The present study explored the effects of EC on the gut microbiota and liver transcriptome in type 2 diabetes mellitus (T2DM) Goto-Kakizaki rats for the first time. The findings showed that EC protected glucose homeostasis, alleviated systemic oxidative stress, relieved liver damage, and increased serum insulin. Further investigation showed that EC reshaped gut microbiota structure, including inhibiting the proliferation of lipopolysaccharide (LPS)-producing bacteria and reducing serum LPS. In addition, transcriptome analysis revealed that the insulin signaling pathway may be the core pathway of the EC anti-T2DM effect. Therefore, EC may modulate the gut microbiota and liver insulin signaling pathways by the gut-liver axis to alleviate T2DM. As a diet supplement, EC has promising potential in T2DM prevention and treatment.

Probiotic-fermented tomato with hepatic lipid metabolism modulation effects: analysis of physicochemical properties, bioactivities, and potential bioactive compounds

Lactiplantibacillus plantarum NCUH001046 (LP)-fermented tomatoes exhibited the potential to alleviate obesity in our previous study. This subsequent study further delves deeper into the effects of LP fermentation on the physicochemical properties, bioactivities, and hepatic lipid metabolism modulation of tomatoes, as well as the analysis of potential bioactive compounds exerting obesity-alleviating effects. Results showed that after LP fermentation, viable bacterial counts peaked at 9.11 log CFU mL-1 and sugar decreased, while organic acids, umami amino acids, total phenols, and total flavonoids increased. LP fermentation also improved the inhibition capacities of three digestive enzyme activities and Enterobacter cloacae growth, as well as antioxidant activities. Western blot results indicated that fermented tomatoes, especially live probiotic-fermented tomatoes (LFT), showed improved effects compared to unfermented tomatoes in reducing hepatic lipid accumulation by activating the AMPK signal pathway. UHPLC-Q-TOF/MS-based untargeted metabolomics analysis showed that chlorogenic acid, capsiate, tiliroside, irisflorentin, and homoeriodictyol levels increased after fermentation. Subsequent cell culture assays demonstrated that irisflorentin and homoeriodictyol reduced lipid accumulation via enhancing AMPK expression in oleic acid-induced hyperlipidemic HepG2 cells. Furthermore, Spearman's correlation analysis indicated that the five phenols were positively associated with hepatic AMPK pathway activation. Consequently, it could be inferred that the five phenols may be potential bioactive compounds in LFT to alleviate obesity and lipid metabolism disorders. In summary, these findings underscored the transformative potential of LP fermentation in enhancing the bioactive profile of tomatoes and augmenting its capacity to alleviate obesity and lipid metabolism disorders. This study furnished theoretical underpinnings for the functional investigation of probiotic-fermented plant-based foods.

Probiotic-fermented tomato alleviates high-fat diet-induced obesity in mice: Insights from microbiome and metabolomics

Probiotic-fermented plant-based foods are associated with weight loss. Here, we hypothesized probiotic-fermented tomato (FT) as a functional food with potential to alleviate obesity, thus the obesity-alleviating effects and mechanisms of FT on high-fat diet-induced obese mice were explored via biochemical, gut microbiome, and serum metabolomics analysis. The results showed that FT performed better than unfermented tomato in reducing body weight gain and fat accumulation, improving dyslipidemia and glucose homeostasis, and relieving inflammation and adipocytokine dysregulation. Particularly, live probiotic-fermented tomato (LFT) was associated with improved diversity, composition, and structure of gut microbiota, suppressed obesity-related genera growth (e.g., Clostridium, Olsenella, and Mucispirillum), and promoted beneficial genera growth (e.g., Roseburia, Coprococcus, and Oscillospira), which were associated negatively with body weight, TC, TG, and TNF-α levels. Additionally, LFT was associated with positive changes in glycerophospholipids, sphingolipids, unsaturated fatty acids, and amino acids levels. Collectively, as a functional food, LFT possessed potential for obesity alleviation.

Gut microbiota and metabolite interface-mediated hepatic inflammation

Immunologic and metabolic signals regulated by gut microbiota and relevant metabolites mediate bidirectional interaction between the gut and liver. Gut microbiota dysbiosis, due to diet, lifestyle, bile acids, and genetic and environmental factors, can advance the progression of chronic liver disease. Commensal gut bacteria have both pro- and anti-inflammatory effects depending on their species and relative abundance in the intestine. Components and metabolites derived from gut microbiota-diet interaction can regulate hepatic innate and adaptive immune cells, as well as liver parenchymal cells, significantly impacting liver inflammation. In this mini review, recent findings of specific bacterial species and metabolites with functions in regulating liver inflammation are first reviewed. In addition, socioeconomic and environmental factors, hormones, and genetics that shape the profile of gut microbiota and microbial metabolites and components with the function of priming or dampening liver inflammation are discussed. Finally, current clinical trials evaluating the factors that manipulate gut microbiota to treat liver inflammation and chronic liver disease are reviewed. Overall, the discussion of microbial and metabolic mediators contributing to liver inflammation will help direct our future studies on liver disease.