Short-chain fatty acids in control of body weight and insulin sensitivity

The gut-skin axis: a bi-directional, microbiota-driven relationship with therapeutic potential

This review explores the emerging term "gut-skin axis" (GSA), describing the bidirectional signaling that occurs between the skin and the gastrointestinal tract under both homeostatic and disease conditions. Central to GSA communication are the gut and skin microbiota, the microbial communities that colonize these barrier surfaces. By influencing diverse host pathways, including innate immune, vitamin D receptor, and Aryl hydrocarbon receptor signaling, a balanced microbiota contributes to both tissue homeostasis and host defense. In contrast, microbiota imbalance, or dysbiosis at one site, can lead to local barrier dysfunction, resulting in the activation of signaling pathways that can disrupt tissue homeostasis at the other site, potentially leading to inflammatory skin conditions such as atopic dermatitis and psoriasis, or gut diseases like Inflammatory Bowel Disease. To date, most research on the GSA has examined the impact of the gut microbiota and diet on skin health, but recent studies show that exposing the skin to ultraviolet B-light can beneficially modulate both the gut microbiome and intestinal health. Thus, despite the traditional focus of clinicians and researchers on these organ systems as distinct, the GSA offers new opportunities to better understand the pathogenesis of cutaneous and gastrointestinal diseases and promote health at both sites.

Soybean protein isolate versus sheep whey protein: A detailed comparison of their chemical composition, gastrointestinal digestion and fermentation properties

Plant proteins are emerging as alternatives to animal proteins. This study compared the physicochemical properties and nutritional characteristics of soybean protein isolate (SPI) and sheep whey protein (SWP), which is gaining recognition for its nutritional benefits. SWP exhibited higher amino acid content, larger particle size, increased turbidity, and superior foaming and emulsification capacities compared to SPI (p < 0.05). In contrast, SPI demonstrated better emulsification stability. In vitro, gastrointestinal digestion showed that SPI achieved a higher degree of hydrolysis in both gastric and intestinal phases, although SWP had a faster initial hydrolysis rate. During gut microbiota fermentation, SWP produced significantly higher levels of short-chain fatty acids (SCFAs) than SPI (p < 0.05). Non-targeted metabolomics revealed distinct metabolic differences, particularly in amino acid metabolism, bile acid synthesis, and hormone biosynthesis. These findings suggest SWP is suitable for nutritional supplementation, while SPI is better for dairy-based alternatives.

Clostridium butyricum ameliorates post-gastrectomy insulin resistance by regulating the mTORC1 signaling pathway through the gut-liver axis

Postoperative insulin resistance (IR) is a metabolic disorder characterized by decreased insulin sensitivity and elevated blood glucose levels following major surgery. Our previous clinical study identified a notable correlation between postoperative IR and gut microbiota, particularly butyrate-producing bacteria, yet the mechanisms remain unclear. In this study, we established gastric resection SD rat models to evaluate the impact of Clostridium butyricum NCU-27 (butyrate-producing bacteria) on postoperative IR. The results demonstrated significant reductions in fasting blood glucose (FBG), fasting insulin (FIns) levels, and HOMA-IR (6.64 ± 0.76 vs. 11.47 ± 1.32; 4.27 ± 0.59 vs. 7.40 ± 0.54) in the postoperative period compared to the control group (P < 0.05). Additionally, glucose tolerance and hepatic glycogen content were markedly improved (P < 0.001). Further exploration of butyrate demonstrated effects similar to C. butyricum NCU-27, potentially mediated through the gut-liver axis by inhibiting mTORC1 expression in liver cells, activating the IRS1/AKT pathway, enhancing glucose uptake and glycogen synthesis, suppressing gluconeogenesis, increasing insulin sensitivity, and improving IR. Finally, the use of mTORC1 agonists and inhibitors further confirmed the critical role of the mTORC1 pathway in mediating the beneficial effects of C. butyricum NCU-27 and butyrate on postoperative IR. In conclusion, this study elucidated that C. butyricum NCU-27 improves postoperative IR by regulating butyrate metabolism and inhibiting the mTORC1 pathway, offering new insights for preventing and treating post-gastrectomy IR.

Fueling the fire: colonocyte metabolism and its effect on the colonic epithelia

Colonic permeability is a major consequence of dysbiosis and diseases affecting the colon, further contributing to inflammation and extraintestinal diseases. Recent advances have shed light on the association between colonocyte energy utilization and the mechanisms that support epithelial function and homeostasis. One unifying theme is the induction of colonocyte hypoxia, driven by the aerobic oxidation of microbial-derived butyrate, as a critical factor promoting multiple cellular processes that support intestinal barrier function, mucus secretion, and the maintenance of synergistic luminal microbes. Particular attention will be focused on experimental evidence supporting beta-oxidation via activation of peroxisome proliferators-activated receptor-γ (PPAR) and upregulation and activation of processes that promote barrier function by hypoxia-inducible factor (HIF) signaling. Growing evidence suggests that colonocyte energy utilization is tightly regulated and switches between beta-oxidation of butyrate and anaerobic glycolysis, the latter being associated with several disease states. As most of the primary literature associated with colonocyte energy utilization has focused on adult models, evidence supporting butyrate oxidation in the neonatal gut is lacking. Thus, this review details the current state of knowledge linking colonocyte substrate utilization to mechanisms supporting gut health, but also highlights the counterindications of colonic butyrate availability and utilization in developmental periods.

Unraveling the gut microbiota's role in obesity: key metabolites, microbial species, and therapeutic insights

Obesity, characterized by excessive fat accumulation, stems from an imbalance between energy intake and expenditure, with the gut microbiota playing a crucial role. This review highlights how gut microbiota influences metabolic pathways, inflammation, and adipose tissue regulation in obesity. Specific bacteria and metabolites, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs), modulate gut permeability, inflammation, and energy harvest, impacting obesity development. Certain gut bacteria, including Clostridium XIVb, Dorea spp., Enterobacter cloacae, and Collinsella aerofaciens, promote obesity by increasing energy harvest, gut permeability, and inflammatory response through LPS translocation into the bloodstream. Conversely, beneficial bacteria like Akkermansia muciniphila, Lactobacillus spp., and Bifidobacterium spp. enhance gut barrier integrity, regulate SCFA production, and modulate fasting-induced adipose factor, which collectively support metabolic health by reducing fat storage and inflammation. Metabolites such as SCFAs (acetate, propionate, and butyrate) interact with G-protein coupled receptors to regulate lipid metabolism and promote the browning of white adipose tissue (WAT), thus enhancing thermogenesis and energy expenditure. However, LPS contributes to insulin resistance and fat accumulation, highlighting the dual roles of these microbial metabolites in both supporting and disrupting metabolic function. Therapeutic interventions targeting gut microbiota, such as promoting WAT browning and activating brown adipose tissue (BAT), hold promise for obesity management. However, personalized approaches are necessary due to individual microbiome variability. Further research is essential to translate these insights into microbiota-based clinical therapies.

Açaí seed extract mitigates intestinal and hypothalamic alterations in obese mice

Obesity is a significant health concern, significantly contributing to increased morbidity and mortality by disrupting multiple physiological systems. It is strongly associated with metabolic dysfunctions, including impaired glycemic homeostasis, compromised intestinal barrier integrity, and gut microbiota imbalances, all exacerbating the risk of chronic diseases. The hydroalcoholic extract of açaí seeds (ASE), rich in phenolic compounds, has demonstrated beneficial effects on obesity and hyperglycemia; however, its impacts on gut health and gut-hypothalamus communication remain unclear. This study aimed to investigate the therapeutic effect of ASE in intestinal and hypothalamic alterations associated with obesity and compare it with Metformin. Male C57BL/6 mice were fed a high-fat or standard diet for 14 weeks. The ASE (300 mg/kg/day) and Metformin (300 mg/kg/day) treatments started in the tenth week until the fourteenth week, totaling four weeks of treatment. Our data show that the treatment with ASE and Metformin reduced body weight, ameliorated lipid profile, hyperglycemia, and plasma hyperleptinemia, and decreased the oxidative damage in the gut by reducing immunostaining of 8-isoprostane and NOX-4 expression, and improved the intestinal parameters and hypothalamic gene expression. Obesity-induced dysbiosis in the HF group was marked by reduced Proteobacteria and elevated LPS plasma levels, which were improved by treatments with ASE and Metformin. These findings suggest that ASE and Metformin are promising strategies to counteract the adverse effects of obesity on intestinal health and gut-hypothalamus communication, though they act through distinct mechanisms. Therefore, we can suggest that ASE is a promising natural product for treating the intestinal alterations associated with obesity.

Impact of a water-soluble soy extract on inflammation and gut microbiota in physiologically aged mice

Soy isoflavones are involved deeply in our diet as beneficial to health. It is known to have anti-inflammatory and antioxidant effects and also to be effective in alleviating various lifestyle diseases, as well as the maintenance of endocrine function, especially with age-related diseases such as osteoporosis. Here we investigated the impact of age-dependent changes with the intestinal microbiota in physiologically aged C57BL/6 N by free drinking water with soluble soybean-derived isoflavone glycosides (SIFs) for 4 weeks. Consequently, Akkermansia muciniphila (A. muciniphila) species represented an age-dependent increase with SIF treatment, subsequently, generally age-dependent decreased goblet cells are retained in the large intestine. These results invoke that SIF plays a beneficial role in intestinal barrier function to maintain large intestine homeostasis. Interestingly, we also revealed that SIF had an alleviating effect on age-dependent bone loss. Taken together, SIF has a fruitful effect on the intestinal environment and the maintenance of homeostasis in physiological aging.

Abdominal Massage Decreases Food Intake and Body Weight in High-Fat Diet-Induced Obese Rats Through Upregulating GPR41/GPR43-PYY/GLP-1 Axis

Background

Abdominal massage has been found to exert an important role in helping people in overcoming obesity. However, the mechanism by which abdominal massage induces weight loss remains largely unclear.

Methods

Healthy male Sprague-Dawley (SD) rats were randomly grouped into standard diet control (15% fat content) group and high-fat diet (HFD, 40% fat content) group. After 6 weeks of high-fat feeding, rats in the HFD group were successfully modeled, and then separated into the HFD group and HFD plus abdominal massage group. Rats in the HFD plus abdominal massage group were then subjected to abdominal massage for 12 continuous days.

Results

Compared to the HFD group, abdominal massage could decrease body weight, food intake and abdominal fat index (AFI) of HFD-fed rats. Meanwhile, compared to the HFD group, abdominal massage obviously attenuated mucosal epithelial damage and reduced inflammatory cell infiltration in colon mucosal tissues of HFD-fed rats. Furthermore, compared to the HFD group, abdominal massage significantly increased GPR42 and GPR43 levels in the colon tissues of HFD-fed rats, and upregulated the production of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in colon mucosal tissues of HFD-fed rats.

Conclusion

Collectively, abdominal massage could decrease food intake and body weight in HFD-induced obese rats through upregulating GPR41/GPR43-PYY/GLP-1 axis.

Links between short-chain fatty acids and osteoarthritis from pathology to clinic via gut-joint axis

Short-chain fatty acids (SCFAs), the primary metabolites produced by the microbial fermentation of dietary fibers in the gut, have a key role in protecting gut health. Increasing evidence indicates SCFAs can exert effects on distant tissues and organs beyond the gut via blood circulation. Osteoarthritis (OA) is a chronic inflammatory joint disease that severely diminishes the physical function and quality of life. However, effective clinical treatments for OA remain elusive. Recent studies have shown that SCFAs can exert beneficial effects on damaged joints in OA. SCFAs can mitigate OA progression by preserving intestinal barrier function and maintaining the integrity of cartilage and subchondral bone, suggesting that they have substantial potential to be the adjunctive treatment strategy for OA. This review described the SCFAs in the human body and their cellular signaling mechanism, and summarized the multiple effects of SCFAs (especially butyrate, propionate, and acetate) on the prevention and treatment of OA by regulating the gut-joint axis, providing novel insights into their promising clinical applications.

Effect of dietary approaches to stop hypertension diet on insulin resistance and lipid accumulation product in subjects with metabolic syndrome

It has been suggested that the dietary approaches to stop hypertension (DASH) diet as a plant-based dietary pattern can be useful in improvement of risk factors of metabolic syndrome (MetS). We designed a study to evaluate the effect of the DASH diet on insulin resistance and lipid accumulation product (LAP) in subjects with MetS. 60 subjects with MetS were assigned into two groups including the intervention group and the control group. The intervention group received DASH diet and the control group received a common healthy diet for 12 weeks. We measured fasting plasma glucose (FPG), triglyceride and glucose (TyG) index, metabolic score for insulin resistance (METS-IR) and LAP before and after intervention. We utilized SPSS software version 24 and an intention-to-treat method for data analysis. A total of 59 subjects completed the trial. After intervention a significant difference was observed between groups in FPG (P < 0.001), TyG index (P < 0.001) and LAP (P = 0.01). However, there was no significant difference between groups in values of METS-IR (P = 0.27). There was a significant reduction in the intervention group compared to the control group in FPG (-7.86 ± 10.08 vs. 0.97 ± 15.51; P = 0.01), TyG index (-0.20 ± 0.14 vs. 0.02 ± 0.11; P < 0.001), METS-IR (-2.50 ± 1.99 vs. -0.53 ± 2.21; P = 0.001) and LAP (-20.06 ± 12.02 vs. -5.87 ± 15.17; P < 0.001). Adherence to DASH diet can reduce some cardiovascular risk factors in subjects with MetS. Further clinical trials are required to reach a firm conclusion.

Advancements in the study of short-chain fatty acids and their therapeutic effects on atherosclerosis

Atherosclerosis (AS) remains a leading cause of cardiovascular disease and mortality globally. This chronic condition is characterized by inflammation, lipid accumulation, and the deposition of cellular components within arterial walls. Emerging evidence has highlighted the multifaceted therapeutic potential of short-chain fatty acids (SCFAs) in mitigating AS progression. SCFAs have demonstrated anti-inflammatory properties and the ability to regulate immune responses, metabolic pathways, vascular integrity, and intestinal barrier function in animal models of AS. Consequently, SCFAs have garnered significant attention as a promising approach for the prevention and treatment of AS. However, further clinical trials and studies are necessary to fully elucidate the underlying mechanisms and effects of SCFAs. Additionally, different types of SCFAs may exert distinct impacts, necessitating more in-depth investigation into their specific roles and mechanisms. This review provides an overview of the diverse cellular mechanisms contributing to AS formation, as well as a discussion of the significance of SCFAs in AS pathogenesis and their multifaceted therapeutic potential. Nonetheless, additional research is warranted to comprehensively understand and harness the potential of various SCFAs in the context of AS.

Systematic review of gut microbiota composition, metabolic alterations, and the effects of treatments on PCOS and gut microbiota across human and animal studies

Introduction

Polycystic ovary syndrome (PCOS) is an endocrine disorder affecting around 12% of women globally, associated with infertility and various comorbidities. Emerging evidence suggests a crucial role of gut microbiota in PCOS pathophysiology, prompting research to investigate alterations in gut microbial composition in patients with PCOS.

Methods

This systematic review aims to analyze human and animal studies that compare gut microbiota composition, gut-derived metabolites, and treatment interventions in PCOS patients versus healthy controls. A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science, yielding studies examining gut microbiota, metabolomic shifts, and treatment responses in PCOS models and human populations.

Results

Our analysis revealed decreases in alpha diversity in PCOS patients, with more pronounced changes in beta diversity in animal models. Specific bacterial taxa, such as Bacteroides vulgatus, Escherichia-Shigella and Lactobacillus, showed implication in PCOS pathogenesis, suggesting potential microbial markers. Furthermore, discrepancies between human and animal studies show the need for humanized mouse models to bridge this gap. Interventions like probiotics and fecal microbiota transplantation (FMT) showed varying levels of efficacy, with FMT emerging as a more promising but invasive option, offering live bacteriotherapy as a potential therapeutic alternative. Alterations in gut-derived metabolites, including short-chain fatty acids and bile acids, highlighted the multifaceted nature of PCOS, with implications extending to metabolic, hormonal, and gut-brain axis disruptions.

Discussion

In conclusion, PCOS exhibits complex interactions between gut microbiota and metabolic pathways, necessitating further research with standardized methods and larger sample sizes to elucidate the microbiome's role in PCOS.

Incorporation of polylactic acid microplastics into the carbon cycle as a carbon source to remodel the endogenous metabolism of the gut

Biodegradable polylactic acid (PLA) plastics have been praised as an effective solution to the global pollution caused by petroleum-based plastics, and their widespread use in food packaging and disposable tableware has resulted in increased oral exposure to PLA microplastics (PLA-MPs). Despite their eco-friendly and biodegradable reputation, the in vivo behaviors of PLA-MPs concerning fermentation, carbon cycle, and adverse effects remain unknown. Here, we showed that gut microbiota from the colon can effectively degrade the PLA-MPs by secreting esterase FrsA, whereas esterase FrsA-producing bacteria were identified to dominate this behavior in male C57BL/6 mice. Using isotope tracing and multiomics techniques, we uncovered that 13C-labeled PLA-MPs were incorporated into the carbon cycle of gut microbiota as a carbon source. Meanwhile, these degraded PLA-MPs fragments entered the succinate pathway of the tricarboxylic acid cycle within gut epithelial cells. These processes altered the metabolic phenotype of the gut, resulting in the decreased linear short-chain fatty acids that are primary energy sources of the gut epithelium. Furthermore, we found that exposure of PLA-MPs significantly reduced the appetite and body weight of mice. Our findings present an overall process of biodegradable plastics within hosts, with the focus on the entire double carbon cycle of PLA-MPs in the gut, which offers indispensable insights into the potential impact of exposure to PLA-MPs.

Patients with periodontitis exhibit persistent dysbiosis of the gut microbiota and distinct serum metabolome

Objectives

Animal studies suggest that periodontopathic bacteria induce gut dysbiosis and related pathology, possibly connecting periodontitis to non-oral diseases. However, the effects on the gut ecosystem in periodontitis patients are not fully understood.

Methods

We conducted a comprehensive analysis of the salivary and gut microbiota using 16S rRNA sequencing in periodontitis patients before and after treatment, comparing them to healthy participants. Serum metabolites were also analyzed.

Results

Periodontitis patients showed high alpha diversity in both salivary and gut microbiota with a strong correlation. Significant differences were also observed in the gut microbiota composition between patients before treatment and healthy participants, irrespective of the ectopic colonization of periodontitis-associated bacteria in the gut. Co-abundance group analysis demonstrated that the gut microbiota of healthy participants was enriched with short-chain fatty acid producers. Changes in the gut microbiota coincided with alterations in the serum metabolite profile. While periodontal therapy improved salivary microbiota, it did not significantly affect gut microbiota.

Conclusions

Gut dysbiosis of periodontitis patients may impact systemic metabolite profiles. Given that periodontal therapy alone did not substantially improve the gut microbiota, adjunctive strategies targeting the gut microbiome may be effective in reducing the risk of periodontitis-associated diseases.

Polyphenol metabolism, short-chain fatty acids production, and microbiota changes during in vitro digestion and fermentation of Chilean beans (Phaseolus vulgaris L.)

This study examines the effects of three Chilean boiled bean (Phaseolus vulgaris L.) landraces 'Negro', 'Peumo', and 'Tórtola' and their polyphenol-enriched extracts (PEE) on polyphenol release, gut microbiota, and short-chain fatty acid (SCFA) production after simulated digestion and colonic fermentation. Negro beans exhibited greater phenolic acid diversity post-digestion, while catechin bio accessibility increased in all landraces. PEE showed significant transformation, with oligomers degrading into flavan-3-ol monomers during digestion. Colonic fermentation of boiled beans produced SCFAs, confirming their prebiotic potential. Negro beans promoted beneficial bacteria, including Catenibacterium, Lachnospira, and Bifidobacterium, associated with fiber and polyphenol metabolism, while Tórtola beans favored Roseburia, an SCFA producer. These findings highlight the potential of Chilean beans and their bioactive compounds to enhance gut health.

Specific dietary fibers steer toward distal colonic saccharolytic fermentation using the microbiota of individuals with overweight/obesity

BACKGROUND

Evidence suggests that increased distal short-chain fatty acid (SCFA) production beneficially impacts metabolic health. However, indigestible carbohydrate availability is limited in the distal colon; consequently, microbes shift toward protein fermentation, often linked to adverse metabolic health effects. We aimed to identify specific fiber(s) that promote saccharolytic fermentation in the distal colon and thereby may (partially) inhibit proteolytic fermentation.

METHODS

Potato-fiber, pectin, and inulin were studied individually and in combination against a high (predigested) protein background using an in vitro model of the colon (TIM-2) inoculated with pooled, standardized fecal microbiota from individuals with overweight/obesity. Microbiota composition and activity were assessed at different timepoints to simulate the travel throughout the colon (proximal: 0-8 h, distal: 8-24 h) and compared to a high protein (HP)_control, receiving only proteins.

RESULTS

Fiber addition increased total SCFA production compared to HP_control (52.11 ± 1.49 vs 27.07 ± 0.26 mmol) whereas total branched-chain fatty acids (BCFA; a marker for protein fermentation) production only slightly decreased (3.31 ± 0.10 vs 4.18 ± 0.40 mmol). Combining potato-fiber and pectin led to the highest total and distal SCFA production and distal SCFA:BCFA. Fiber addition attenuated HP-induced increases in several bacterial taxa including Mogibacterium and Coprococcus, independent of fiber type. Additionally, time- and fiber-specific microbial signatures were identified: inulin increased Bifidobacterium (proximal) relative abundance and pectin and/or potato-fiber increased Prevotella 9 (distal) relative abundance.

CONCLUSION

The most marked increase in distal colonic SCFA production was induced by combining potato-fiber and pectin. Further research should elucidate whether this switch toward saccharolytic fermentation translates into beneficial metabolic health effects in humans.

Alterations in fatty acid metabolism in patients with schizophrenia in a multi-omics perspective

BACKGROUND

Recent research has extensively explored the involvement of gut microbes in various fatty acid metabolic processes, elucidating their crucial roles in host energy homeostasis and metabolism. Nevertheless, there remains a dearth of studies examining the comprehensive profile of fatty acid metabolites in schizophrenia and their potential connection to gut microbes.

METHOD

Conducting a thorough investigation, this study scrutinized the gut microbiome composition of 63 individuals, consisting of 35 schizophrenia (SZ) patients and 28 demographically matched healthy control (HC) subjects. Feces and serum samples were meticulously collected, with stool samples subjected to 16S rRNA sequencing targeting region V4 and untargeted metabolomics analysis, while serum samples underwent untargeted metabolomics assessment.

RESULTS

A total of 21 different genus-level species were identified in the SZ and HC groups. Predictive analysis of gut flora pathways revealed abnormal fatty acid degradation in schizophrenia. Notably, 17 differential fatty acid metabolites were found in feces, whereas 43 were found in serum fatty acid metabolites. A higher proportion of differential fatty acid metabolites were found in serum compared to those in feces. The predominant pathways enriched in fatty acid metabolites included biosynthesis of unsaturated fatty acids, arachidonic acid metabolism, and linoleic acid metabolism. Additionally, a significant correlation was noted between intestinal flora and fatty acids, as well as potential interactions between intestinal flora, fecal fatty acids and serum fatty acids.

CONCLUSIONS

Our multi-omics study provides new insights into the pathogenesis of schizophrenia, which may inform the treatment of neurodevelopmental disorders by modifying fatty acid metabolism through modulation of the gut microbiota.

Lactucin and lactucopicrin ameliorate obesity in high-fat diet fed mice by promoting white adipose tissue browning through the activation of the AMPK/SIRT1/PGC-1α pathway

Lactucin and lactucopicrin are the characteristic lipid-lowering active components found in Cichorium glandulosum. However, their effects and underlying mechanisms in obesity remain unclear. In the present study, C57BL/6J mice were simultaneously subjected to a high-fat diet (HFD) and treated with drugs to investigate the impacts of lactucin and lactucopicrin on HFD-induced obese mice. The results demonstrated that in HFD obese mice, lactucin and lactucopicrin significantly decreased body weight and the weights of adipose tissues, improved serum metabolic parameters, and increased the content of irisin. Regarding the intermediate metabolites of intestinal flora, which are closely associated with white adipose tissue (WAT) browning, lactucin and lactucopicrin treatment led to a reduction in the levels of 12-α-OH/non-12-α-OH bile acids (BAs) and also tended to enhance the levels of short-chain fatty acids (SCFAs). qRT-PCR results indicated that lactucin and lactucopicrin treatment elevated the expression levels of genes related to beige fat markers, thermogenesis, mitochondrial biogenesis, and lipolysis in WAT, as well as those of thermogenesis and lipolysis genes in brown adipose tissue (BAT). Western blot analysis revealed that lactucin and lactucopicrin up-regulated the expression of uncoupling protein 1 (UCP1), the core protein in thermogenesis, in both WAT and BAT. Moreover, they also up-regulated the expression levels of AMP-activated kinase (AMPK), sirtuin 1 (SIRT1), and PPARγ coactivator 1-alpha (PGC-1α), which are key pathway proteins involved in WAT browning. Furthermore, 16S rRNA sequencing results showed that in HFD obese mice, lactucin and lactucopicrin improved the composition and function of the intestinal microbiota. In conclusion, lactucin and lactucopicrin may promote WAT browning by activating the AMPK/SIRT1/PGC-1α pathway, thereby ameliorating obesity in HFD mice.

Gut Microbiota Disorders and Metabolic Syndrome: Tales of a Crosstalk Process

The microbiota in humans consists of trillions of microorganisms that are involved in the regulation of the gastrointestinal tract and immune and metabolic homeostasis. The gut microbiota (GM) has a prominent impact on the pathogenesis of metabolic syndrome (MetS). This process is reciprocal, constituting a crosstalk process between the GM and MetS. In this review, GM directly or indirectly inducing MetS via the host-microbial metabolic axis has been systematically reviewed. Additionally, the specifically altered GM in MetS are detailed in this review. Moreover, short-chain fatty acids (SCFAs), as unique gut microbial metabolites, have a remarkable effect on MetS, and the role of SCFAs in MetS-related diseases is highlighted to supplement the gaps in this area. Finally, the existing therapeutics are outlined, and the superiority and shortcomings of different therapeutic approaches are discussed, in hopes that this review can contribute to the development of potential treatment strategies.

Fermentation-enriched quinoa β-glucan ameliorates disturbed gut microbiota and metabolism in type 2 diabetes mellitus mice

Quinoa β-glucan (QBG) has shown potential benefits in treating type 2 diabetes mellitus (T2DM); however, comprehensive evaluations of its effects remain limited. This study investigates the impact of QBG-derived from hot water extraction (Q-) and microbial fermentation enrichment (Q+)-on serum glucose levels, lipid profiles, appetite-regulating hormones, fecal short-chain fatty acids (SCFAs), and gut microbiota composition and function in streptozotocin/high-fat diet (STZ/HFD)-induced T2DM mice. The results indicate that QBG treatment significantly reduced fasting blood glucose, insulin levels, triglycerides (TG) and total cholesterol (TC), while concurrently increasing high-density lipoprotein cholesterol (HDLC) levels. Additionally, liver and pancreatic function improved, as evidenced by decreased levels of malondialdehyde (MDA), aspartate transaminase (AST), and alanine transaminase (ALT). SCFA levels were significantly higher in QBG-treated groups compared to MC group. QBG treatment also reduced the abundance of Firmicutes and Patescibacteria, along with the Firmicutes/Bacteroidota ratio, while increasing levels of Bacteroidota and Actinobacteria. These findings suggest that QBG can regulate the dysbiosis of SCFAs production in T2DM mice and may indirectly modulate the secretion of appetite-regulating hormones by influencing gut microbiota composition. Furthermore, PICRUSt analysis revealed that QBG treatment, particularly Q + _H, could enhance disrupted metabolism and improve gut microbiota functions, helping restore normal physiological function.

Effect of Fatty Acids on Glucose Metabolism and Type 2 Diabetes

Type 2 diabetes is an inflammatory, non-infectious disease characterized by dysfunctional pancreatic β-cells and insulin resistance. Although lifestyle, genetic, and environmental factors are associated with a high risk of type 2 diabetes, nutrition remains one of the most significant factors. Specific types and increased amounts of dietary fatty acids are associated with type 2 diabetes and its complications. Dietary recommendations for the prevention of type 2 diabetes advocate for a diet that is characterized by reduced saturated fatty acids and trans fatty acids alongside an increased consumption of monounsaturated fatty acids, polyunsaturated fatty acids, and omega-3 fatty acids. Although following the recommendations for dietary fatty acid intake is important for reducing type 2 diabetes and its related complications, the underlying mechanisms remain unclear. This review will provide an update on the mechanisms of action of fatty acids on glucose metabolism and type 2 diabetes, as well as dietary recommendations for the prevention of type 2 diabetes.

Decoding Blastocystis-Driven Mechanisms in Gut Microbiota and Host Metabolism

Blastocystis, a prevalent eukaryotic microorganism in the gut microbiota, has emerged as a potential link between healthy diets and improved cardiometabolic health. Despite its genetic diversity and varied host interactions, Blastocystis is consistently associated with healthier dietary patterns and reduced risk of cardiometabolic diseases. Current evidence suggests that Blastocystis may influence host metabolism by modulating gut microbial composition, short-chain fatty acids (SCFAs) production, and immune cell differentiation. Moreover, its role in tryptophan metabolism provides intriguing insights into its potential impact on host signaling pathways. However, mechanistic evidence connecting Blastocystis to improved metabolic health remains limited. This perspective explores plausible pathways, including SCFAs-mediated signaling, tryptophan metabolism, and immune modulation, through which Blastocystis may exert its effects. A systematic research framework integrating axenic cultivation, in vitro co-culture systems, animal models, and multi-omics approaches is proposed to further elucidate these mechanisms and expand the understanding of Blastocystis in gut health and disease.

An integrated fecal microbiome and metabolomics in type 2 diabetes mellitus rats reveal mechanism of action of Moringa oleifera Lamarck seeds polysaccharides to alleviate diabetes

Moringa oleifera Lamarck seeds (MOS) have been traditionally used in folk medicine and documented for their potential to alleviate type 2 diabetes symptoms, but the potential mechanisms are still unknown. The purpose of this article is to investigate the effects of MSAP (alkali-extracted polysaccharide from MOS) on diabetic rats by assessing its impact on the gut microbiome, diabetes-related biochemical markers, and fecal metabolomics. The results demonstrated that the fasting blood glucose, glucose tolerance, insulin resistance, insulin level and lipopolysaccharides (LPS) level in the rats treated with MSAP were all improved. Specifically, MSAP was found to modulate the composition and diversity of the gut microbiota, increasing the ratio of Firmicutes/Bacteroidetes, which enhanced the quantity of probiotic Lactobacillus and butyrate-producing bacteria, such as Roseburia, thereby reinforcing the intestinal epithelial barrier. Furthermore, fecal metabolomics indicates that MSAP actively regulates pathways closely associated with diabetes, including sphingolipid metabolism, amino acid synthesis and catabolism, retrograde endogenous cannabinoid signaling, and the modulation of TRP channels by inflammatory mediators. By integrating microbiome and metabolomics data, this study elucidated the mechanisms through which MSAP alleviates diabetes. In conclusion, the findings suggest that polysaccharides from MOS hold potential as a medicinal and edible homologous food for diabetes management.

Association between dietary index for gut microbiota and metabolic syndrome risk: a cross-sectional analysis of NHANES 2007-2018

Metabolic syndrome (MetS) poses a significant global health challenge, closely associated with cardiovascular diseases, diabetes, and other conditions. With the global prevalence of MetS steadily rising, the potential role of gut microbiota in its development has garnered increasing attention. Against this backdrop, the present study aims to explore the association between the dietary index for gut microbiota (DI-GM) score and MetS. This cross-sectional study utilized data from the 2007-2018 U.S. National Health and Nutrition Examination Survey (NHANES), including 339,242 adults aged ≥ 18 years. The DI-GM score, constructed based on 14 food or nutrient components, served as the exposure variable. MetS was defined according to the Adult Treatment Panel III (ATP III) criteria, including abdominal obesity (waist circumference ≥ 102 cm in men and ≥ 88 cm in women), elevated triglycerides (≥ 150 mg/dL), reduced HDL cholesterol (< 40 mg/dL in men and < 50 mg/dL in women), elevated blood pressure (≥ 130/85 mmHg), and elevated fasting glucose (≥ 100 mg/dL). Multivariable logistic regression analyses were performed to adjust for demographic characteristics, lifestyle factors, and other potential confounders. Higher DI-GM scores were significantly associated with a reduced risk of MetS. After adjusting for all confounders, individuals in the highest quartile (Q4) of DI-GM scores had a 16% lower risk of MetS compared to those in the lowest quartile (Q1) (OR: 0.84; 95%CI: 0.70-1.01). Mediation analyses revealed that systemic immune-inflammation index (SII) and neutrophil-to-lymphocyte ratio (NLR) mediated 4.63% and 3.83% of the association between DI-GM and MetS, respectively. There is an inverse association between DI-GM scores and the risk of MetS, potentially mediated in part by inflammatory markers. These findings provide new evidence supporting dietary interventions aimed at improving gut microbiota to prevent MetS.

Macronutrients and cardiovascular diseases: A narrative review of recent scientific literature

BACKGROUND & AIMS

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide. This narrative review explores the relationship between macronutrient intake and CVD risk, focusing on carbohydrates, proteins, and fats. The goal is to examine how specific types of macronutrients influence cardiovascular health and how dietary guidelines, such as those from the World Health Organization (WHO), can reduce the incidence of both fatal and non-fatal cardiovascular events.

METHODS

This narrative review draws upon existing research and WHO dietary guidelines to assess the impact of various macronutrients on cardiovascular outcomes. We searched the relevant literature up to December 2024 using Pubmed and Google Scholar. Key macronutrient groups-carbohydrates (with a focus on glycemic index and glycemic load), proteins (plant-based vs. animal-based), and fats (saturated, trans, polyunsaturated, and monounsaturated)-were analyzed to understand their roles in CVD prevention.

RESULTS

Low glycemic index (GI) and glycemic load (GL) were found to be associated with reduced CVD risk. Protein intake showed no significant direct association with CVD risk, but higher consumption of plant-based proteins was correlated with a reduced risk. Replacing animal proteins with plant-based alternatives led to improved lipid profiles, including reductions in total and low-density lipoprotein (LDL) cholesterol levels. Fats, particularly saturated and trans fats, were strongly linked to increased CVD risk. WHO guidelines recommend limiting these fats and replacing them with healthier alternatives, such as polyunsaturated and monounsaturated fats or slow-digesting carbohydrates, to lower CVD risk.

CONCLUSIONS

Macronutrients play a critical role in cardiovascular health, with specific types of carbohydrates, proteins, and fats having varying impacts on CVD risk. Future research should explore the complex interactions between these macronutrients, dietary patterns, and cultural factors to optimize global dietary guidelines for CVD prevention. Replacing high-GI carbohydrates, saturated fats, and trans fats with healthier alternatives is crucial for reducing cardiovascular risk globally.

Role and Mechanism of Short-Chain Fatty Acids in Skeletal Muscle Homeostasis and Exercise Performance

Acetate, propionate, and butyrate are major short-chain fatty acids (SCFAs) produced by the gut microbiota as key metabolic byproducts. These SCFAs influence skeletal muscle homeostasis and exercise performance through various mechanisms. This review explores the current knowledge on the mechanisms by which SCFAs influence muscle mass, strength, metabolism, and inflammation. Acetate enhances mitochondrial function and glucose metabolism, while butyrate supports muscle mass preservation by suppressing inflammation and autophagy. Propionate plays complex roles, aiding metabolic regulation, but potentially impairing myogenic differentiation at high concentrations. These SCFAs modulate insulin sensitivity and oxidative stress; their interactions with host energy systems and immunity significantly influence muscle health. Although their therapeutic potential is evident, further studies, especially human clinical trials, are necessary to validate their effective applications. This review synthesizes emerging evidence and outlines specific future research priorities.

Unlocking the gut-liver axis: microbial contributions to the pathogenesis of metabolic-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a complex metabolic disorder characterized by hepatic lipid accumulation and subsequent inflammation. This condition is closely linked to metabolic syndrome and obesity, with its prevalence rising due to sedentary lifestyles and high-calorie diets. The pathogenesis of MAFLD involves multiple factors, including insulin resistance, lipotoxicity, oxidative stress, and inflammatory responses. The gut microbiota plays a crucial role in MAFLD development, with dysbiosis contributing to liver inflammation through various mechanisms, such as enhanced intestinal permeability and the translocation of bacterial products like lipopolysaccharide (LPS). Microbial metabolites, including short-chain fatty acids (SCFAs) and bile acids, influence hepatic function and immune responses, with potential implications for disease progression. Specific gut microbiome signatures have been identified in MAFLD patients, offering potential diagnostic and therapeutic targets. Moreover, gut-derived toxins, such as endotoxins, lipopolysaccharides, trimethylamine-N-oxide and bacterial metabolites, significantly influence liver damage and inflammation, highlighting the complex interplay between the gut microbiome and hepatic health. This review comprehensively examines the complex interplay between the gut microbiota and MAFLD, focusing on underlying pathogenic mechanisms, potential biomarkers, and emerging microbiome-targeted therapeutic strategies for disease management.

Coculture of Bifidobacterium bifidum G9-1 With Butyrate-Producing Bacteria Promotes Butyrate Production

Supplementation with Bifidobacterium bifidum G9-1 (BBG9-1) has been established to enhance the production of butyrate, a short-chain fatty acid (SCFA) known for its beneficial effects in alleviating constipation. We hypothesized that BBG9-1 alters gut microbiota such that bacteria that produce butyric acid from lactate and acetate become more abundant. In this study, we sought to determine whether BBG9-1 promotes the growth of butyrate-producing bacteria and thereby enhances butyrate production. BBG9-1 was cocultured with different butyrate-producing bacteria to compare differences in the SCFA production of cocultures and monocultures. We indeed detected significant increases in the production of SCFAs in cocultures compared to monocultures. Moreover, lactate and butyrate production increased in a time-dependent manner in the BBG9-1 and Faecalibacterium prausnitzii ID 6052 coculture. In addition, acetate production in cocultures initially increased until 16 h, followed by a decline between 20 and 24 h, and a subsequent significant increase at 48 h. Comparatively, lactate and acetate production in the BBG9-1 and Anaerostipes caccae JCM 13470T coculture peaked at 16 h and declined thereafter, and butyrate production increased in a time-dependent manner. In contrast, lactate, acetate, and butyrate production in the BBG9-1 and Roseburia hominis JCM 17582T coculture increased in a time-dependent manner. These findings indicate that butyrate-producing bacteria increase butyrate production by utilizing BBG9-1-produced lactate and acetate. Thus, the butyrate-mediated physiological activity of BBG9-1 could be attributed to an indirect enhancement of butyrate production.

Rumen microbiota regulates IMF deposition in Xizang sheep by activating the PPARγ transcription factor: a rumen-muscle axis perspective

The interaction between microbiota and muscle by the rumen-muscle axis and its impact on sheep meat flavor has received little attention. This study selected Xizang sheep under summer and autumn grazing conditions as models for different rumen bacteria and intramuscular fat (IMF) to attempt to address the current research gap. Specifically, the deposition characteristics of IMF and the expression of lipid metabolism genes in Xizang sheep were determined; 16S rDNA sequencing technology and gas chromatography were used to study the rumen microbiota and its metabolic products, short-chain fatty acids (SCFAs); RNA sequencing was used to identify the transcriptome of the rumen epithelium. Based on the above results, we proposed the hypothesis that the flavor of Xizang sheep meat is regulated by the microbiota-rumen-muscle axis. SCFAs produced in the rumen of Xizang sheep are absorbed by the rumen epithelium under the regulation of the solute carrier family genes (SLC). SCFAs can directly reach muscle tissue through the circulatory system and then activate the expression of the peroxisome proliferator-activated receptor Gamma (PPARγ) gene through the rumen-muscle axis. The expression of fat synthesis genes carnitine palmitoyltransferase II (CPT2), fatty acid synthase (FAS), patatin-like phospholipase domain-containing 2 (PNPLA2), and stearoyl-CoA desaturase 1 (SCD1) is correspondingly upregulated, promoting the deposition of IMF in Xizang sheep and thus affecting its flavor. This study introduces the theory of the microbiota-rumen-muscle axis into the research of the flavor of ruminant animal food, comprehensively elucidating the regulatory mechanism of the flavor of Xizang sheep meat.IMPORTANCEOur study employed a multi-omics approach to reveal how the rumen microbiota regulate muscle lipid metabolism in Xizang sheep through the activation of the PPARγ transcription factor. Importantly, by developing models of Xizang sheep with varying rumen microbial communities and muscle fatty acid profiles, we established the critical role of the microbiota-rumen-muscle axis in determining the flavor of Xizang sheep meat. This finding suggests that modulating the composition of the microbial community could serve as a strategy to improve the flavor of ruminant-derived food products. These insights provide valuable understanding of the complex interactions between rumen bacteria and mutton flavor, offering new approaches for research in this field.

Endogenous Metabolites in Metabolic Diseases: Pathophysiologic Roles and Therapeutic Implications

Breakthroughs in metabolomics technology have revealed the direct regulatory role of metabolites in physiology and disease. Recent data have highlighted the bioactive metabolites involved in the etiology and prevention and treatment of metabolic diseases such as obesity, nonalcoholic fatty liver disease, type 2 diabetes mellitus, and atherosclerosis. Numerous studies reveal that endogenous metabolites biosynthesized by host organisms or gut microflora regulate metabolic responses and disorders. Lipids, amino acids, and bile acids, as endogenous metabolic modulators, regulate energy metabolism, insulin sensitivity, and immune response through multiple pathways, such as insulin signaling cascade, chemical modifications, and metabolite-macromolecule interactions. Furthermore, the gut microbial metabolites short-chain fatty acids, as signaling regulators have a variety of beneficial impacts in regulating energy metabolic homeostasis. In this review, we will summarize information about the roles of bioactive metabolites in the pathogenesis of many metabolic diseases. Furthermore, we discuss the potential value of metabolites in the promising preventive and therapeutic perspectives of human metabolic diseases.

Beyond the Gut: Unveiling Butyrate's Global Health Impact Through Gut Health and Dysbiosis-Related Conditions: A Narrative Review

Short-chain fatty acids (SCFAs), mainly produced by gut microbiota through the fermentation process of dietary fibers and proteins, are crucial to human health, with butyrate, a famous four-carbon SCFA, standing out for its inevitably regulatory impact on both gut and immune functions. Within this narrative review, the vital physiological functions of SCFAs were examined, with emphasis on butyrate's role as an energy source for colonocytes and its ability to enhance the gut barrier while exhibiting anti-inflammatory effects. Knowledge of butyrate synthesis, primarily generated by Firmicutes bacteria, can be influenced by diets with specifically high contents of resistant starches and fiber. Butyrate can inhibit histone deacetylase, modulate gene expression, influence immune functionality, and regulate tight junction integrity, supporting the idea of its role in gut barrier preservation. Butyrate possesses systemic anti-inflammatory properties, particularly, its capacity to reduce pro-inflammatory cytokines and maintain immune homeostasis, highlighting its therapeutic potential in managing dysbiosis and inflammatory diseases. Although butyrate absorption into circulation is typically minimal, its broader health implications are substantial, especially regarding obesity and type 2 diabetes through its influence on metabolic regulation and inflammation. Furthermore, this narrative review thoroughly examines butyrate's growing recognition as a modulator of neurological health via its interaction with the gut-brain axis. Additionally, butyrate's neuroprotective effects are mediated through activation of specific G-protein-coupled receptors, such as FFAR3 and GPR109a, and inhibition of histone deacetylases (HDACs). Research indicates that butyrate can alleviate neurological disorders, including Alzheimer's, Parkinson's, autism spectrum disorder, and Huntington's disease, by reducing neuroinflammation, enhancing neurotransmitter modulation, and improving histone acetylation. This focus will help unlock its full therapeutic potential for metabolic and neurological health, rather than exclusively on its well-known benefits for gut health, as these are often interconnected.

Changes in gut microbiota following supplementation with chitosan in adolescents with overweight or obesity: a randomized, double-blind clinical trial

BACKGROUND

Overweight and obesity have been associated with an altered intestinal microbiome. Recent investigations have demonstrated that fiber supplementation, including chitosan, can exert beneficial and protective effects on the composition of gut microbiota in humans diagnosed with overweight/obesity. However, there is still a great deal of heated debate regarding the impact of chitosan supplementation in overweight and obese adolescents. Therefore, the aim of this study is to clarify the effects of chitosan administration on the composition of the gut microbiome in overweight and obese adolescents.

METHODS AND ANALYSIS

Sixty-four overweight and obese adolescents were subjected to supplementation with 3 g of chitosan for 12 weeks. Anthropometric indices and physical activity were measured at the beginning and at the end of the intervention. After DNA extraction and purification, the quantity of bacteria in the patients' stool samples was determined by real-time polymerase chain reaction (PCR). The RCT was registered on the Iranian Registry of Clinical Trials ( www.irct.ir ) website (IRCT20091114002709 N57; registration date: 2021 - 06 - 20).

RESULTS

Individuals who received chitosan supplementation experienced a significant decrease in the BMI z-score (P < 0.001). Administration of chitosan led to notable significant decrease in the Firmicutes (P < 0.001) populations and the ratio of Firmicutes to Bacteroidetes (P < 0.001) as well as a notable increase in the Bacteroidetes (P = 0.008) and Akkermansia (P < 0.001) populations, respectively compare to control group. Mean changes in Lactobacillus populations were marginally significant (P = 0.05). Chitosan administration did not alter the composition in Bifidobacterium populations (P = 0.97).

CONCLUSION

The present study demonstrates beneficial effects of chitosan administration on some bacterial species associated with overweight and obesity in adolescents. Further research is needed to confirm our findings and clarify the impact of this intervention on the Lactobacillus population in the gut.

Role of short-chain fatty acids in non-alcoholic fatty liver disease and potential therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) is increasing worldwide and has become the greatest potential risk for cirrhosis and hepatocellular carcinoma. The metabolites produced by the gut microbiota act as signal molecules that mediate the interaction between microorganisms and the host and have biphasic effects on human health. The gut microbiota and its metabolites, short-chain fatty acids (SCFAs), have been discovered to ameliorate many prevalent liver diseases, including NAFLD. Currently, SCFAs have attracted widespread attention as potential therapeutic targets for NAFLD, but the mechanism of action has not been fully elucidated. This article summarizes the mechanisms of short-chain fatty acids of gut microbiota metabolites to regulate the metabolism of glucose and lipid, maintain the intestinal barrier, alleviate the inflammatory response, and improve the oxidative stress to improve NAFLD, in order to provide a reference for clinical application.

Acidipropionibacterium acidipropionici, a propionate-producing bacterium, contributes to GPR41 signaling and metabolic regulation in high-fat diet-induced obesity in mice

Obesity is a major healthcare problem worldwide and is induced by excess energy intake, resulting in gut microbial composition and microbial diversity changes. Through fermentation of dietary fibers, short-chain fatty acids (SCFAs) act as host energy sources and signaling molecules via G protein-coupled receptors such as GPR41. Acidipropionibacterium acidipropionici is widely used in many applications; however, in vivo studies on the beneficial effect of A. acidipropionici via propionate production and host energy homeostasis are unclear. Therefore, this study aimed to investigate the beneficial metabolic effects of A. acidipropionici by focusing on GPR41 signaling in a high-fat diet (HFD)-induced obesity mouse model. Here, we demonstrated that A. acidipropionici OB7439 improved host metabolism in HFD-induced obesity in mice. The intake of A. acidipropionici OB7439 improved metabolism in HFD-induced obese mice by increasing propionate production, regulating glucose tolerance, and inhibiting hepatic inflammation via GPR41 signaling. Our findings shed light on the potential of using A. acidipropionici OB7439 as an SCFA producer for the prevention and treatment of metabolic disorders. Based on these results, we suggest that A. acidipropionici may be a potential therapeutic bacterium that inhibits obesity and modulates the gut microbial community.

Insights into Autophagy in Microbiome Therapeutic Approaches for Drug-Resistant Tuberculosis

Tuberculosis, primarily caused by Mycobacterium tuberculosis, is an airborne lung disease and continues to pose a significant global health threat, resulting in millions of deaths annually. The current treatment for tuberculosis involves a prolonged regimen of antibiotics, which leads to complications such as recurrence, drug resistance, reinfection, and a range of side effects. This scenario underscores the urgent need for novel therapeutic strategies to combat this lethal pathogen. Over the last two decades, microbiome therapeutics have emerged as promising next-generation drug candidates, offering advantages over traditional medications. In 2022, the Food and Drug Administration approved the first microbiome therapeutic for recurrent Clostridium infections, and extensive research is underway on microbiome treatments for various challenging diseases, including metabolic disorders and cancer. Research on microbiomes concerning tuberculosis commenced roughly a decade ago, and the scope of this research has broadened considerably over the last five years, with microbiome therapeutics now viewed as viable options for managing drug-resistant tuberculosis. Nevertheless, the understanding of their mechanisms is still in its infancy. Although autophagy has been extensively studied in other diseases, research into its role in tuberculosis is just beginning, with preliminary developments in progress. Against this backdrop, this comprehensive review begins by succinctly outlining tuberculosis' characteristics and assessing existing treatments' strengths and weaknesses, followed by a detailed examination of microbiome-based therapeutic approaches for drug-resistant tuberculosis. Additionally, this review focuses on establishing a basic understanding of microbiome treatments for tuberculosis, mainly through the lens of autophagy as a mechanism of action. Ultimately, this review aims to contribute to the foundational comprehension of microbiome-based therapies for tuberculosis, thereby setting the stage for the further advancement of microbiome therapeutics for drug-resistant tuberculosis.

The gut microbiome and dietary fibres: implications in obesity, cardiometabolic diseases and cancer

Dietary fibres constitute a heterogeneous class of nutrients that are key in the prevention of various chronic diseases. Most dietary fibres are fermented by the gut microbiome and may, thereby, modulate the gut microbial ecology and metabolism, impacting human health. Dietary fibres may influence the occurrence of specific bacterial taxa, with this effect varying between individuals. The effect of dietary fibres on microbial diversity is a matter of debate. Most intervention studies with dietary fibres in the context of obesity and related metabolic disorders reveal the need for an accurate assessment of the microbiome to better understand the variable response to dietary fibres. Epidemiological studies confirm that a high dietary fibre intake is strongly associated with a reduced occurrence of many types of cancer. However, there is a need to determine the impact of intervention with specific dietary fibres on cancer risk, therapy efficacy and toxicity, as well as in cancer cachexia. In this Review, we summarize the mechanisms by which the gut microbiome can mediate the physiological benefits of dietary fibres in the contexts of obesity, cardiometabolic diseases and cancer, their incidence being clearly linked to low dietary fibre intake.

Multi-Effects of Natural Plant Bioactive Components on Intestinal Health in Pigs: Promising Feed-Antibiotic Alternatives?

The poor intestinal health induced by management, stress, or infection remains a substantial challenge restricting the rapid development of the pig industry. Some natural plant bioactive components (NPBCs) have garnered considerable interest owing to their multifarious benefits, including enhancing intestinal morphology, digestion and absorption, barrier function, immune function, and regulating the gut microbiota. However, there are critical factors, such as the lack of standardized production technologies, lower stability and bioavailability, and unclear mechanisms of NPBCs, severely limiting their feeding efficacy and their application in animal production. Here, we conducted a comprehensive review of the recent advances regarding the impacts of NPBCs on pig gut health. Additionally, we highlighted the key areas that warrant further in-depth investigation. Taken together, NPBCs could be green, safe, and effective feed additives by constructively overcoming their limitations, and they are expected to have broader applications in animal husbandry.

Subcutaneous adipose tissue and skeletal muscle mitochondria following weight loss

Obesity is a major global health issue with various metabolic complications. Both bariatric surgery and dieting achieve weight loss and improve whole-body metabolism, but vary in their ability to maintain these improvements over time. Adipose tissue and skeletal muscle metabolism are crucial in weight regulation, and obesity is linked to mitochondrial dysfunction in both tissues. The impact of bariatric surgery versus dieting on adipose tissue and skeletal muscle mitochondrial metabolism remains to be elucidated. Understanding the molecular pathways that modulate tissue metabolism following weight loss holds potential for identifying novel therapeutic targets in obesity management. This narrative review summarizes current knowledge on mitochondrial metabolism following bariatric surgery and diet-induced weight loss in adipose tissue and skeletal muscle, and sheds light on their respective effects.

Exploring receptors for pro-resolving and non-pro-resolving mediators as therapeutic targets for sarcopenia

Sarcopenia is defined by a reduction in both muscle strength and mass. Sarcopenia may be an inevitable component of the aging process, but it may also be accelerated by comorbidities and metabolic derangements. The underlying mechanisms contributing to these pathological changes remain poorly understood. We propose that chronic inflammation-mediated networks and metabolic defects that exacerbate muscle dysfunction are critical factors in sarcopenia and related diseases. Consequently, utilizing specialized pro-resolving mediators (SPMs) that function through specific G-protein coupled receptors (GPCRs) may offer effective therapeutic options for these disorders. However, challenges such as a limited understanding of SPM/receptor signaling pathways, rapid inactivation of SPMs, and the complexities of SPM synthesis impede their practical application. In this context, stable small-molecule SPM mimetics and receptor agonists present promising alternatives. Moreover, the aged adipose-skeletal axis may contribute to this process. Activating non-SPM GPCRs on adipocytes, immune cells, and muscle cells under conditions of systemic, chronic, low-grade inflammation (SCLGI) could help alleviate inflammation and metabolic dysfunction. Recent preclinical studies indicate that both SPM GPCRs and non-SPM GPCRs can mitigate symptoms of aging-related diseases such as obesity and diabetes, which are driven by chronic inflammation and metabolic disturbances. These findings suggest that targeting these receptors could provide a novel strategy for addressing various chronic inflammatory conditions, including sarcopenia.

Unraveling the link between metabolic dysfunction-associated steatotic liver disease and osteoporosis: a bridging function of gut microbiota

This review examines the strong association between metabolic dysfunction-associated steatotic liver disease (MASLD) and osteoporosis (OP), with a particular focus on the role of gut microbiota in linking these two disorders. Both MASLD and OP are closely linked to metabolic syndrome, and their pathogenesis involves multiple factors, such as inflammatory response, insulin resistance, altered intestinal permeability, and estrogen deficiency. Dysregulation of gut microbiota not only affects hepatic fat accumulation and bone metabolism disorders through metabolites, such as short-chain fatty acids, but also exacerbates systemic chronic inflammation by impairing the intestinal barrier function, thus accelerating the progression of both diseases. This article summarizes recent studies that highlight the central role of gut microbiota as a co-morbid factor in MASLD and OP, offering new perspectives for future diagnostic and therapeutic strategies.

Effects of drinking water fructo-oligosaccharide supplementation on broiler chicken growth performance, blood glucose level, white blood cell count, carcass yield, meat quality, and cecal microbiota

This study investigated the effects of fructo-oligosaccharides (FOS) supplementation on the growth performance, blood glucose level, white blood cell count, carcass yield, meat quality, and cecal microbiota of Ross 308 broiler chickens. A completely randomized design was employed; FOS was supplemented in the drinking water at concentrations of 0 %, 0.25 %, and 0.50 %. From 11 to 24 d of age, 0.25 % FOS supplementation significantly increased feed intake (FI), while feed cost per gain (FCG) was significantly reduced at 0.50 % FOS (P < 0.05). During the overall period (1-36 d of age), FOS supplementation significantly improved the European Production Efficiency Factor (EPEF) (P < 0.01), and slowed down the reduction in blood glucose levels after the re-feeding period (2, 3, 4, and 5 h) (P < 0.01). Furthermore, FOS supplementation decreased the heterophil/lymphocyte (H:L) ratio (P < 0.05). However, it had no significant effect on breast meat yield or abdominal fat, but 0.50 % FOS supplementation tended to increase the percentage of cecal weight (P = 0.08). Supplementation with FOS (0.25 % and 0.50 %) significantly reduced breast meat cooking loss (P < 0.05). Regarding cecal microbiota, the FOS-supplemented groups showed increased abundances of Lactobacillaceae and Acidaminococcaceae, whereas the abundances of Lachnospiraceae and Barnesiellaceae were reduced (P < 0.05). In conclusion, drinking water FOS supplementation had a beneficial effect on the overall productive performance and cooking loss of broiler chickens via stress reduction, which may involve an improvement in the gut microbiota.

Lactiplantibacillus plantarum FRT4 protects against fatty liver hemorrhage syndrome: regulating gut microbiota and FoxO/TLR-4/NF-κB signaling pathway in laying hens

BACKGROUND

Fatty liver hemorrhage syndrome (FLHS) has become one of the major factors leading to the death of laying hen in caged egg production. FLHS is commonly associated with lipid peroxidation, hepatocyte injury, decreased antioxidant capacity, and inflammation. However, there are limited evidences regarding the preventive effect of Lactiplantibacillus plantarum on FLHS in laying hens and its mechanisms. Our previous results showed that Lp. plantarum FRT4 alleviated FLHS by regulating lipid metabolism, but did not focus on its antioxidant and anti-inflammatory functions and mechanisms. Therefore, this study aimed to investigate the preventive mechanisms of Lp. plantarum FRT4 in alleviating FLHS, with a focus on its role in antioxidant activity and inflammation regulation.

RESULTS

Supplementation with Lp. plantarum FRT4 enhanced the levels of T-AOC, T-SOD, and GSH-Px, while reducing the levels of TNF-α, IL-1β, IL-8, and NLRP3 in the liver and ovary of laying hens. Additionally, Lp. plantarum FRT4 upregulated the mRNA expressions of SOD1, SOD2, CAT, and GPX1, downregulated the mRNA expressions of pro-inflammatory factors IL-1β, IL-6, and NLRP3, and upregulated the mRNA expressions of anti-inflammatory factors IL-4 and IL-10. Lp. plantarum FRT4 improved the structure and metabolic functions of gut microbiota, and regulated the relative abundances of dominant phyla (Bacteroidetes, Firmicute, and Proteobacteria) and genera (Prevotella and Alistipes). Additionally, it influenced key KEGG pathways, including tryptophan metabolism, amino sugar and nucleotide sugar metabolism, insulin signaling pathway, FoxO signaling pathway. Spearman analysis revealed that the abundance of microbiota at different taxonomic levels was closely related to antioxidant enzymes and inflammatory factors. Furthermore, Lp. plantarum FRT4 modulated the mRNA expressions of related factors in the FoxO/TLR-4/NF-κB signaling pathway by regulating gut microbiota. Moreover, the levels of E2, FSH, and VTG were significantly increased in the ovary after Lp. plantarum FRT4 intervention.

CONCLUSIONS

Lp. plantarum FRT4 effectively ameliorates FLHS in laying hens. This efficacy is attributed to its antioxidant and anti-inflammatory properties, which are mediated by modulating the structure and function of gut microbiota, and further intervening in the FoxO/TLR-4/NF-κB signaling pathway. These actions enhance hepatic and ovarian function and increase estrogen levels. Video Abstract.

Physiological and Microbial Community Dynamics in Does During Mid-Gestation to Lactation and Their Impact on the Growth, Immune Function, and Microbiome Transmission of Offspring Kids

This study investigated changes in physiological processes and rumen microbial communities in does from mid-gestation to lactation and identified potential associations between these physiological changes and the rumen microbiome. Additionally, we studied the transmission mechanisms of microorganisms between the dam and offspring. Our study demonstrates significant changes in maternal physiological metabolism, immune status, and rumen microbiota from mid-pregnancy through lactation. We identified potential associations between these physiological changes and the rumen microbiome. Moreover, the findings highlight that alterations in maternal physiological metabolism and immune status significantly influence the growth and immune development of offspring kids. Additionally, we observed that the maternal microbiota serves as a key source of gastrointestinal microbial communities in young animals, with early colonization of maternally derived microbes in the offspring's gastrointestinal tract playing a role in shaping their immune system development. The results for primary outcomes are as follows: The serum levels of estrogen and progesterone in pregnant does were greater than those observed during lactation, while the concentration of growth hormone, triiodothyronine, and glucose exhibited an upward trend during lactation. During late gestation, the serum IL-10 concentration in does decreased, while the TNF-α concentration increased. Additionally, on day 140 of gestation, does showed a significant decrease in IgG, total protein, and globulin levels. From mid-gestation to lactation, the abundance of dominant phyla and genera, including Firmicutes, Bacteroidetes, Patescibacteria, Bacteroidales_RF16_group, Clostridia_UCG-014, RF39, and Eubacterium_ventriosum_group, in the rumen of does underwent significant changes. LEfSe analysis identified a series of marker microorganisms in the rumen of does at different physiological stages. A correlation was observed between these dominant bacteria and the serum physiological indicators of the does. Notably, rumen volatile fatty acids also exhibited a correlation with serum physiological indicators. In addition, serum physiological indicators of does were significantly correlated with the growth and immune indicators of their kids. Microbiological origin analysis revealed that the gastrointestinal microbiome of kids primarily originated from the rumen, birth canal, and milk of does. Further analysis identified a correlation between the kids' serum immunometric indicators and certain gastrointestinal microorganisms. In particular, the jejunum microbiota of 28-day-old lactating kids, including Alysiella, Neisseria, and Muribaculaceae, showed a significant positive correlation with serum IL-6 and IL-10 levels. Meanwhile, these genera were dominant in the saliva and milk of does, suggesting a direct microbial transfer from dam to offspring. These microbial communities may play a significant role in modulating the metabolism and immune responses of the offspring, thereby influencing their immune system development.

Causal associations between gut microbiota and type 2 diabetes mellitus subtypes: a mendelian randomization analysis

PURPOSE

To investigate the causal relationships between gut microbiota and novel adult-onset type 2 diabetes mellitus(T2DM) subtypes.

METHODS

We conducted Mendelian randomization (MR) analyses using genome-wide association data from European populations. Initial MR analyses examined associations between gut microbiota and four T2DM subtypes, followed by validation analyses using type 1 diabetes mellitus(T1DM) and T2DM GWAS data. We also performed bidirectional MR analyses and tested for heterogeneity and pleiotropy across all analyses.

RESULTS

Our MR analyses revealed distinctive associations between gut microbiota and T2DM subtypes: six bacterial taxa with severe insulin-deficient diabetes (SIDD), four with severe insulin-resistant diabetes (SIRD), eight with mild obesity-related diabetes (MOD), and eight with mild age-related diabetes (MARD). These associations were distinct from T1DM findings. Six bacterial taxa were validated in T2DM analyses, with four showing directionally consistent effects: Class Clostridia (OR = 0.57, P = 0.045) and Order Clostridiales (OR = 0.57, P = 0.045) were associated with reduced MOD risk, while species Catus (OR = 1.80, P = 0.007) was associated with increased MOD risk, and genus Holdemania (OR = 2.51, P = 0.004) was associated with increased SIRD risk. No significant heterogeneity or pleiotropy was observed across analyses.

CONCLUSIONS

Our MR analyses reveal novel causal relationships between gut microbiota and adult-onset T2DM subtypes, though further validation studies are warranted.

Dietary emulsifier carboxymethylcellulose-induced gut dysbiosis and SCFA reduction aggravate acute pancreatitis through classical monocyte activation

OBJECTIVE

Carboxymethylcellulose (CMC), one of the most common emulsifiers used in the food industry, has been reported to promote chronic inflammatory diseases, but its impact on acute inflammatory diseases, e.g., acute pancreatitis (AP), remains unclear. This study investigates the detrimental effects of CMC on AP and the potential for mitigation through Akkermansia muciniphila or butyrate supplementation.

DESIGN

C57BL/6 mice were given pure water or CMC solution (1%) for 4 weeks and then subjected to caerulein-induced AP. The pancreas, colon, and blood were sampled for molecular and immune parameters associated with AP severity. Gut microbiota composition was assessed using 16S rRNA gene amplicon sequencing. Fecal microbiota transplantation (FMT) was used to illustrate gut microbiota's role in mediating the effects of CMC on host mice. Additional investigations included single-cell RNA sequencing, monocytes-specific C/EBPδ knockdown, LPS blocking, fecal short-chain fatty acids (SCFAs) quantification, and Akkermansia muciniphila or butyrate supplementation. Finally, the gut microbiota of AP patients with different severity was analyzed.

RESULTS

CMC exacerbated AP with gut dysbiosis. FMT from CMC-fed mice transferred such adverse effects to recipient mice, while single-cell analysis showed an increase in classical monocytes in blood. LPS-stimulated C/EBPδ, caused by an impaired gut barrier, drives monocytes towards classical phenotype. LPS antagonist (eritoran), Akkermansia muciniphila or butyrate supplementation ameliorates CMC-induced AP exacerbation. Fecal Akkermansia muciniphila abundance was negatively correlated with AP severity in patients.

CONCLUSIONS

This study reveals the detrimental impact of CMC on AP due to gut dysbiosis, with Akkermansia muciniphila or butyrate offering potential therapeutic avenues for counteracting CMC-induced AP exacerbation. Video Abstract.

Sex-specific associations of serum short-chain fatty acids with glycaemic control: an Italian cross-sectional study in adults with type 1 diabetes

OBJECTIVE

Short-chain fatty acids (SCFA) play a role in modulating glucose metabolism and are influenced by diet. Alterations in the SCFA-producing microbial ecosystem in individuals with type 1 diabetes (T1D) may contribute to impaired glycaemic control. This study investigated the relationships between serum SCFA levels, blood glucose control, and dietary habits in adults with T1D.

DESIGN

Observational study.

SETTING

The study was conducted at the diabetes outpatient clinic of Federico II University Teaching Hospital, Naples, Italy.

POPULATION

The study included 198 adults with T1D (100 men and 98 women), aged 18-79 years.

MAIN OUTCOME MEASURES

Serum SCFA levels, blood glucose control, assessed by glycated haemoglobin (HbA1c) and continuous glucose monitoring (CGM) metrics, and dietary intake from a 7-day food record.

RESULTS

SCFA levels showed significant sex-specific differences (p<0.05). Therefore, to evaluate relationships between SCFA levels, glycaemic control and dietary habits, SCFA levels were categorised into sex-specific tertiles, and results were adjusted for age and body mass index. HbA1c and CGM metrics did not vary significantly across tertiles of acetate and butyrate. However, in women, higher propionate levels were associated with better glycaemic control, reflected by a greater percentage of glucose time-in-range (70-180 mg/dL) (66.2±12.3% vs 56.9±16.7%, low tertile; p=0.014), lower time-above-range (>180 mg/dL) (32.2±12.6% vs 41.2±17.2%, low tertile; p=0.011) and improved glucose management indicator (7.1±0.6% vs 7.5±0.6%, low tertile; p=0.027). Regarding eating habits, higher acetate tertiles were associated with higher intakes of total fat (p=0.041), polyunsaturated fatty acids (p=0.049) and monounsaturated fatty acids (p=0.021) in men only.

CONCLUSION

These findings reveal a sex-specific association between serum propionate levels and blood glucose control in women with T1D. Importantly, this relationship appears independent of dietary factors.

TRIAL REGISTRATION NUMBER

NCT05936242.

Gut microbiota and its metabolites regulate insulin resistance: traditional Chinese medicine insights for T2DM

The gut microbiota is closely associated with the onset and development of type 2 diabetes mellitus (T2DM), characterized by insulin resistance (IR) and chronic low-grade inflammation. However, despite the widespread use of first-line antidiabetic drugs, IR in diabetes and its complications continue to rise. The gut microbiota and its metabolic products may promote the development of T2DM by exacerbating IR. Therefore, regulating the gut microbiota has become a promising therapeutic strategy, with particular attention given to probiotics, prebiotics, synbiotics, and fecal microbiota transplantation. This review first examines the relationship between gut microbiota and IR in T2DM, summarizing the research progress of microbiota-based therapies in modulating IR. We then delve into how gut microbiota-related metabolic products contribute to IR. Finally, we summarize the research findings on the role of traditional Chinese medicine in regulating the gut microbiota and its metabolic products to improve IR. In conclusion, the gut microbiota and its metabolic products play a crucial role in the pathophysiological process of T2DM by modulating IR, offering new insights into potential therapeutic strategies for T2DM.

Ruminococcus bromii-generated acetate alleviated Clonorchis sinensis-induced liver fibrosis in mice

Introduction

Infection with Clonorchis sinensis (C. sinensis) has the potential to induce liver fibrosis and significantly alter the gut microbiota. However, it remains unclear how these changes in the gut microbiota, through the gut-liver axis, influence the progression of liver fibrosis. Furthermore, it is uncertain whether targeting the gut microbiota, based on the concept of the gut-liver axis, could be a potential therapeutic strategy for alleviating liver fibrosis.

Methods

The gut microbiota alterations in C. sinensis-infected mice at multiple time points were analyzed through 16S rDNA high-throughput sequencing. Ruminococcus bromii (R.bromii) therapeutic effect on C. sinensis infected mice was evaluated. Metabolic changes following produced by R. bromii were analyzed using short-chain fatty acids (SCFAs) metabolomics. Additionally, R. bromii conditioned medium (R.b CM) or its metabolites were co-cultured with two hepatic stellate cell lines (LX2 and JS1) in vitro to assess their anti-fibrotic effects. Finally, RNA sequencing was employed to investigate the specific mechanism by which acetate inhibits hepatic stellate cells (HSCs) activation.

Results

The abundance of R. bromii increased during the inflammatory stage of C. sinensis infection and decreased significantly during the fibrosis stage. Oral gavage of R. bromii significantly inhibited C. sinensis-induced liver fibrosis while restoring the intestinal barrier. The activation of HSCs was significantly inhibited in vitro upon incubation with R.b CM. Acetate was identified as a key metabolite generated from R. bromii in R.b CM, and acetate attenuated C. sinensis-induced liver fibrosis in vitro and in vivo. Mechanistically, acetate inhibited the activation of HSCs by activating the PI3K/AKT signaling pathway to prevent the progression of liver fibrosis in mice infected with C. sinensis.

Discussion

R. bromii exerted a protective effect on hepatic fibrosis by delivering acetate via the gut-liver axis to active the PI3K/AKT signaling pathway in HSCs. Furthermore, R. bromii can be used as a probiotic therapy to alleviate hepatic fibrosis.

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