Gut microbiota dysbiosis in patients with non-alcoholic fatty liver disease

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.

Avocado (Persea americana Mill.) consumption during pregnancy and lactation induces anxiogenic-like behavior, cerebral oxidative stress and compromises fecal microbiota in rat offspring

This study aimed to evaluate the impact of consumption of avocado oil (AO) and pulp (AP) on anxiety-like behavior, cerebral oxidative stress and alteration of the fecal microbiota in the mother and male Wistar rats offspring treated during gestation and lactation. Anxiety-like behavior was measured through the elevated plus maze (EPM) and open field test (OFT) tests. Cerebral malondialdehyde (MDA) and glutathione (GLUT) levels were measured in mothers and offspring. The fatty acid profile was determined for maternal milk and brain. Data showed a shorter time spent on the open arms of EPM in mothers and offspring for those fed AO and AP (P < 0.001). Moreover, the AO offspring adolescent and adult spent less time in the central area (P < 0.05). Furthermore, offspring adults from the AO moved about less and offspring from the AP ambulated more (P < 0.001). MDA was increased in mothers and decreased in the offspring in AO and AP and GLUT was lower in mothers and higher in adolescent and adult offspring in AP (P < 0.05). Polyunsaturated fatty acids in the brain and breast milk in AO and AP were decreased (P < 0.05). Furthermore, there was an increase in the abundance of intestinal bacteria related to the production of inflammatory metabolites that compromised brain function in offspring treated with avocado. These results suggest that avocado induces anxiogenic-like behavior and increases cerebral oxidative stress in mothers and offspring of rats treated during pregnancy and lactation, negatively altering the fecal microbiota of the offspring. So, we report for the first time how the consumption of avocado oil and pulp interferes with a developing organism when consumed in the early stages of life in rats.

Butyrate inhibits histone deacetylase 2 expression to alleviate liver fibrosis in biliary atresia

BACKGROUND

Previous studies have found a reduction in butyrate-producing bacteria in the gut microbiota of infants with biliary atresia (BA). Butyrate is also an important inhibitor of histone deacetylase 2 (HDAC2). This study aims to explore how butyrate alleviates liver fibrosis in BA through HDAC2.

METHODS

Fibrosis-related pathways associated with butyrate were analyzed using the GSE46960 database. BA liver sections were used to validate factor expression. The effects of HDAC2 and butyrate and the pathway were performed in vitro experiments. Butyrate intervention was performed in bile duct ligation (BDL) mice, and alterations in the gut microbiota were analyzed using fecal 16S rRNA sequencing. The impact of butyrate and related pathways on liver fibrosis in BDL mice was further evaluated.

RESULTS

The IL-6/STAT3 pathway showed a clear correlation with butyrate in BA. HDAC2 promoted LX-2 activation via the IL-6/STAT3 pathway, while butyrate inhibited LX-2 activation by suppressing HDAC2. Butyrate not only alleviated liver fibrosis but also improved the gut microbiota structure in BDL mice.

CONCLUSION

Butyrate may improve liver fibrosis in BA by regulating HDAC2 expression and modulating the IL-6/STAT3 pathway. Therefore, butyrate could serve as a promising therapeutic option for mitigating liver fibrosis in BA.

Flammulina velutipes residue Polysaccharide Alleviates Immunosuppression and Intestinal Injury by Modulating Gut Microbiota and Associated Metabolites

This study elucidated the mechanisms underlying the immunoregulatory and gut-microbiota-modulating effects of Flammulina velutipes residue polysaccharide (FVRP) using cyclophosphamide (CTX)-induced mouse models. FVRP supplementation alleviated CTX-induced intestinal damage and boosted antioxidant enzyme activity and cytokine secretion. Additionally, FVRP enhanced the diversity and total species richness of the gut microbiota, promoting the proliferation of beneficial bacteria (e.g., Prevotellaceae), while reducing the abundance of CTX-derived bacteria (Lachnospiraceae and Rikenellaceae). FVRP facilitates the accumulation of short-chain fatty acids. Untargeted metabolomic analyses of cecal content revealed that FVRP treatment notably restored the levels of 32 endogenous metabolites altered by CTX. Based on a pseudosterility mice model, fecal microbiota transplantation (FMT), and fecal filtrate transplantation (FFT), gut microbiota and associated metabolites were demonstrated to play a crucial role in the immunomodulatory and protective effects of FVRP against intestinal injury. In conclusion, FVRP exhibits significant potential as an immune enhancer and natural therapeutic agent for alleviating intestinal inflammatory conditions.

Therapeutic Role of Probiotics Against Environmental-Induced Hepatotoxicity: Mechanisms, Clinical Perspectives, Limitations, and Future

Hepatotoxicity is one of the biggest health challenges, particularly in the context of liver diseases, often aggravated by gut microbiota dysbiosis. The gut-liver axis has been regarded as a key idea in liver health. It indicates that changes in gut flora caused by various hepatotoxicants, including alcoholism, acetaminophen, carbon tetrachloride, and thioacetamide, can affect the balance of the gut's microflora, which may lead to increased dysbiosis and intestinal permeability. As a result, bacterial endotoxins would eventually enter the bloodstream and liver, causing hepatotoxicity and inducing inflammatory reactions. Many treatments, including liver transplantation and modern drugs, can be used to address these issues. However, because of the many side effects of these approaches, scientists and medical experts are still hoping for a therapeutic approach with fewer side effects and more positive results. Thus, probiotics have become well-known as an adjunctive strategy for managing, preventing, or reducing hepatotoxicity in treating liver injury. By altering the gut microbiota, probiotics offer a secure, non-invasive, and economical way to improve liver health in the treatment of hepatotoxicity. Through various mechanisms such as regulation of gut microbiota, reduction of pathogenic overgrowth, suppression of inflammatory mediators, modification of hepatic lipid metabolism, improvement in the performance of the epithelial barrier of the gut, antioxidative effects, and modulation of mucosal immunity, probiotics play their role in the treatment and prevention of hepatotoxicity. This review highlights the mechanistic effects of probiotics in environmental toxicants-induced hepatotoxicity and current findings on this therapeutic approach's experimental and clinical trials.

Early-life exposure to gestational diabetes mellitus predisposes offspring to pediatric nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has emerged as the prevailing chronic liver disease in the pediatric population due to the global obesity pandemic. Evidence shows that prenatal and postnatal exposure to maternal abnormalities leads to a higher risk of pediatric NAFLD through persistent alterations in developmental programming. Gestational diabetes mellitus (GDM) is a hyperglycemic syndrome which has become the most prevalent complication in pregnant women. An increasing number of both epidemiologic investigations and animal model studies have validated adverse and long-term outcomes in offspring following GDM exposure in utero. Similarly, GDM is considered a crucial risk factor for pediatric NAFLD. This review aimed to summarize currently published studies concerning the inductive roles of GDM in offspring NAFLD development during childhood and adolescence. Dysregulations in hepatic lipid metabolism and gut microbiota in offspring, as well as dysfunctions in the placenta are potential factors in the pathogenesis of GDM-associated pediatric NAFLD. In addition, potentially effective interventions for GDM-associated offspring NAFLD are also discussed in this review. However, most of these therapeutic approaches still require further clinical research for validation.

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.

Polygonatum cyrtonema Hua polysaccharides alleviate muscle atrophy and fat lipolysis by regulating the gut microenvironment in chemotherapy-induced cachexia

Introduction: Polygonatum cyrtonema Hua (PC) is an essential herbal medicine in China, known for improving muscle quality and enhancing physical function; its active ingredients are polysaccharides (PCPs). A previous study revealed the anti-atrophy effects of PCPs in cachectic mice. However, whether the effects of PCPs on anti-atrophy are associated with gut microenvironment remain elusive. This research endeavored to assess the medicinal efficacy of PCPs in alleviating muscle atrophy and fat lipolysis and explore the potential mechanisms. Methods: A cancer cachexia model was induced by male C57BL/6 mice bearing Lewis lung tumor cells and chemotherapy. The pharmacodynamics of PCPs (32 and 64 mg/kg/day) was investigated through measurements of tumor-free body weight, gastrocnemius muscle weight, soleus muscle weight, epididymal fat weight, tissue histology analysis, and pro-inflammatory cytokines. Immunohistochemistry and Western blotting assays were further used to confirm the effects of PCPs. 16S rRNA sequencing, LC-MS and GC-MS-based metabolomics were used to analyze the gut microbiota composition and metabolite alterations. Additionally, the agonist of free fatty acid receptor 2 (FFAR2)-a crucial short-chain fatty acid (SCFA) signaling molecule-was used to investigate the role of gut microbiota metabolites, specifically SCFAs, in the treatment of cancer cachexia, with comparisons to PCPs. Results: This study demonstrated that PCPs significantly mitigated body weight loss, restored muscle fiber atrophy and mitochondrial disorder, alleviated adipose tissue wasting, strengthened the intestinal barrier integrity, and decreased the intestinal inflammation in chemotherapy-induced cachexia. Furthermore, the reversal of specific bacterial taxa including Klebsiella, Akkermansia, norank_f__Desulfovibrionaceae, Enterococcus, NK4A214_group, Eubacterium_fissicatena_group, Eubacterium_nodatum_group, Erysipelatoclostridium, Lactobacillus, Monoglobus, Ruminococcus, Odoribacter, and Enterorhabdus, along with alterations in metabolites such as amino acids (AAs), eicosanoids, lactic acid and (SCFAs), contributed to the therapeutic effects of PCPs. Conclusion: Our findings suggest that PCPs can be used as prebiotic drugs targeting the microbiome-metabolomics axis in cancer patients undergoing chemotherapy.

The gut microbiota genus Blautia is associated with skeletal muscle mass reduction in community-dwelling older Japanese adults: the Wakayama Study

PURPOSE

This cross-sectional study examined the gut microbiota species associated with skeletal muscle mass reduction in a community-based sample of older Japanese adults.

METHODS

The study included 744 participants (320 men and 424 women) aged 65-89 years (mean age: 73 years) with no history of treatment for colorectal, chronic kidney, or liver diseases. Bioelectrical impedance analysis was performed to estimate the appendicular skeletal muscle mass (ASM) of each participant. The gut microbiota composition was assessed using next-generation sequencing targeting the V3-V4 regions of the prokaryotic 16S rRNA genes. A self-administered questionnaire was used to evaluate daily living habits, including food intake associated with maintaining the gut microbiota.

RESULTS

Among the participants, those with reduced muscle mass (defined as an ASM index of less than 4.4 kg/m2 for men and 3.7 kg/m2 for women) had significantly higher levels of the genus Blautia when compared with those with normal muscle mass (P = 0.009). Logistic regression analysis revealed that the association between the genus Blautia and skeletal muscle mass remained significant even after adjusting for multiple confounding factors (P = 0.012). Additionally, an increase in the genus Blautia was positively associated with excessive alcohol consumption (≥ 20 g/day, β = 0.125, P = 0.002) and negatively associated with regular yogurt intake (≥ 1 time/week, β = -0.101, P = 0.010), independent of other lifestyle and dietary factors.

CONCLUSION

Elevated levels of the genus Blautia were associated with reduced skeletal muscle mass in older Japanese adults, suggesting that improving the gut microbiota may be a potential approach to preserving muscle mass among this population.

Mitigating Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD): The Role of Bioactive Phytoconstituents in Indian Culinary Spices

PURPOSE OF REVIEW

The term metabolic dysfunction-associated steatotic liver disease (MASLD) refers to a group of progressive steatotic liver conditions that include metabolic dysfunction-associated steatohepatitis (MASH), which has varying degrees of liver fibrosis and may advance to cirrhosis, and independent hepatic steatosis. MASLD has a complex underlying mechanism, with patients exhibiting diverse causes and phases of the disease. India has a pool prevalence of MASLD of 38.6% in adults. In 2023, the term NAFLD has been redefined and changed to MASLD. Currently, there are no drugs approved by the FDA for the treatment of MASLD. This study investigates the potential of bioactive phytoconstituents present in spices as a therapeutic approach for MASLD. Moreover, it offers comprehensive data on several pre-clinical studies of bioactive phytoconstituents derived from spices that primarily focus on treating obesity-associated MASLD.

RECENT FINDINGS

Spices include a high amount of bioactive chemicals and several research have indicated their diverse pharmacological activities. Bioactive phytoconstituents from common Indian spices like cinnamic acid, eugenol, curcumin, allicin, 6-gingerols, capsaicin, piperine, eucalyptol, trigonelline, and linalool have been reported to exhibit anti-MASLD effects both in-vivo and in-vitro. Bioactive phytoconstituents from different culinary species of India have shown promising potential against MASLD in pre-clinical status. Further clinical studies on a large scale would be beneficial for paving the path to the development of a new drug which is the need of time.

The role of intestinal flora in metabolic dysfunction-associated steatotic liver disease and treatment strategies

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common multi-factorial liver disease, and its incidence is gradually increasing worldwide. Many reports have revealed that intestinal flora plays a crucial role for the occurrence and development of MASLD, through mechanisms such as flora translocation, endogenous ethanol production, dysregulation of choline metabolism and bile acid, and endotoxemia. Here, we review the relationship between intestinal flora and MASLD, as well as interventions for MASLD, such as prebiotics, probiotics, synbiotics, and intestinal flora transplantation. Intervention strategies targeting the intestinal flora along with its metabolites may be new targets for preventing and treating MASLD.

The effects of kefir drink on liver aminotransferases and metabolic indicators in patients with nonalcoholic fatty liver disease: a randomized controlled trial

BACKGROUND AND AIM

Probiotics play an important role in the control and treatment of non-alcoholic fatty liver disease (NAFLD). Kefir drink is a fermented beverage and has indicated some beneficial health effects. The aim of this study was to evaluate the effects of kefir drink on liver aminotransferases, anthropometric indices, glycemic index, lipid profile, blood pressure (BP), high sensitivity C-reactive protein, and malondialdehyde in patients with NAFLD.

METHODS

In an 8-week randomized clinical trial, 80 patients with NAFLD were randomized into two groups of 40. After a 2-week run-in period, the groups received a dietary plan and dietary plan plus a cup of kefir drink twice a day (500 cc/d), respectively. Also, demographic, anthropometric, laboratory, BP, dietary intake, and physical activity assessments were analyzed before and after the intervention.

RESULTS

At last, seventy-two participants completed the study. No significant difference in changes in BP, anthropometric indices, and laboratory data (P > 0.05) except HDL-C (P = 0.02) and fat-free mass (P < 0.001) was observed between the two study groups.

CONCLUSION

Based on the results, Drinking 500 cc/d kefir beverage had no significant effect on liver aminotransferases and metabolic indicators, except for HDL-C and fat-free mass in patients with NAFLD.

TRIAL REGISTRATION

IRCT20170916036204N6 (2018/08/03).

Bioactive metabolites: A clue to the link between MASLD and CKD?

Metabolites produced as intermediaries or end-products of microbial metabolism provide crucial signals for health and diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD). These metabolites include products of the bacterial metabolism of dietary substrates, modification of host molecules (such as bile acids [BAs], trimethylamine-N-oxide, and short-chain fatty acids), or products directly derived from bacteria. Recent studies have provided new insights into the association between MASLD and the risk of developing chronic kidney disease (CKD). Furthermore, alterations in microbiota composition and metabolite profiles, notably altered BAs, have been described in studies investigating the association between MASLD and the risk of CKD. This narrative review discusses alterations of specific classes of metabolites, BAs, fructose, vitamin D, and microbiota composition that may be implicated in the link between MASLD and CKD.

Intestinal TM6SF2 protects against metabolic dysfunction-associated steatohepatitis through the gut-liver axis

Transmembrane-6 superfamily member 2 (TM6SF2) regulates hepatic fat metabolism and is associated with metabolic dysfunction-associated steatohepatitis (MASH). TM6SF2 genetic variants are associated with steatotic liver disease. The pathogenesis of MASH involves genetic factors and gut microbiota alteration, yet the role of host-microbe interactions in MASH development remains unclear. Here, we discover that mice with intestinal epithelial cell-specific knockout of Tm6sf2 (Tm6sf2ΔIEC) develop MASH, accompanied by impaired intestinal barrier and microbial dysbiosis. Transplanting stools from Tm6sf2ΔIEC mice induces steatohepatitis in germ-free recipient mice, whereas MASH is alleviated in Tm6sf2ΔIEC mice co-housed with wild-type mice. Mechanistically, Tm6sf2-deficient intestinal cells secrete more free fatty acids by interacting with fatty acid-binding protein 5 to induce intestinal barrier dysfunction, enrichment of pathobionts, and elevation of lysophosphatidic acid (LPA) levels. LPA is translocated from the gut to the liver, contributing to lipid accumulation and inflammation. Pharmacological inhibition of the LPA receptor suppresses MASH in both Tm6sf2ΔIEC and wild-type mice. Hence, modulating microbiota or blocking the LPA receptor is a potential therapeutic strategy in TM6SF2 deficiency-induced MASH.

An updated overview on hepatocellular carcinoma in patients with Metabolic dysfunction-Associated Steatotic Liver Disease: Trends, pathophysiology and risk-based surveillance

Hepatocellular carcinoma (HCC) is a relevant complication occurring in individuals with advanced Metabolic dysfunction-Associated Steatotic Liver Disease (MASLD). Recent epidemiological data suggest an alarming increase in the HCC burden worldwide, with a relevant proportion attributable to MASLD (up to 38 %), either in cirrhotic or non-cirrhotic livers. In view of the changing landscape of metabolic syndrome as "silent pandemic", this narrative review aims to provide an updated picture of the burden of HCC in individuals with MASLD. In the complex pathophysiological pathways linking insulin resistance to MASLD and cardiometabolic syndrome, metabolic inflammation appears a relevant driver of systemic as well as organ-specific complications. Novel insights from the field of immunology, gut-derived liver damage, and association with extra-hepatic cancers will be discussed. Finally, strategies for risk-based HCC surveillance (circulating biomarkers, prognostic models and polygenic risk scores) will be provided and the potential impact of novel drug targeting fibrosing Metabolic dysfunction-Associated Steatohepatitis (MASH) on incident HCC will be discussed.

Dietary Influences on Gut Microbiota and Their Role in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major contributor to liver-related morbidity, cardiovascular disease, and metabolic complications. Lifestyle interventions, including diet and exercise, are first line in treating MASLD. Dietary approaches such as the low-glycemic-index Mediterranean diet, the ketogenic diet, intermittent fasting, and high fiber diets have demonstrated potential in addressing the metabolic dysfunction underlying this condition. The development and progression of MASLD are closely associated with taxonomic shifts in gut microbial communities, a relationship well-documented in the literature. Given the importance of diet as a primary treatment for MASLD, it is important to understand how gut microbiota and their metabolic byproducts mediate favorable outcomes induced by healthy dietary patterns. Conversely, microbiota changes conferred by unhealthy dietary patterns such as the Western diet may induce dysbiosis and influence steatotic liver disease through promoting hepatic inflammation, up-regulating lipogenesis, dysregulating bile acid metabolism, increasing insulin resistance, and causing oxidative damage in hepatocytes. Although emerging evidence has identified links between diet, microbiota, and development of MASLD, significant gaps remain in understanding specific microbial roles, metabolite pathways, host interactions, and causal relationships. Therefore, this review aims to provide mechanistic insights into the role of microbiota-mediated processes through the analysis of both healthy and unhealthy dietary patterns and their contribution to MASLD pathophysiology. By better elucidating the interplay between dietary nutrients, microbiota-mediated processes, and the onset and progression of steatotic liver disease, this work aims to identify new opportunities for targeted dietary interventions to treat MASLD efficiently.

ABL1‒YAP1 axis in intestinal stem cell activated by deoxycholic acid contributes to hepatic steatosis

BACKGROUND

Yes-associated protein 1 (YAP1) regulates the survival, proliferation, and stemness of cells, and contributes to the development of metabolic dysfunction associated fatty liver disease (MAFLD). However, the regulatory role of intestinal YAP1 in MAFLD still remains unclear.

METHODS

Terminal ileal specimens were used to compare intestinal YAP1 activation in patients with and without MAFLD. Mice targeted for knocking out YAP1 in the intestinal epithelium were fed a high-fat diet (HFD) for 8 consecutive weeks. In a separate group, the mice were fed an HFD supplemented with the bile acid binder cholestyramine (CHO) or a low-fat diet with deoxycholic acid (DCA). Immunofluorescence, Immunohistochemistry, Western blot, RT-qPCR, ELISA, 16S rDNA sequencing, tissue and enteroid culture techniques were used to evaluate the effects of an HFD or DCA on the gut‒liver axis in mice or humans.

RESULTS

Intestinal YAP1 was activated in both humans with MAFLD and mice fed an HFD. In in vivo studies, YAP1 knockout in intestinal epithelial cells of mice alleviated the hepatic steatosis induced by an HFD, and mitigated the adverse effects of HFD on the gut‒liver axis, including the upregulation of lipopolysaccharide (LPS) and inflammation levels, enrichment of intestinal Gram-negative bacteria, and inhibition of intestinal stem cell (ISC) differentiation into the goblet and Paneth cells. High-fat feeding (HFF) produced high concentrations of DCA. The consumption of DCA mimics these HFF-induced changes, and is accompanied by the activation of Abelson tyrosine-protein kinase 1 (ABL1) and its direct substrate, YAP1, in the terminal ileum. In vitro studies further confirmed that DCA upregulated the tyrosine phosphorylation of YAP1Y357 in ISC by activating ABL1, which inhibited the differentiation of ISCs into secretory cells.

CONCLUSIONS

Our findings reveal that the activation of the ABL1‒YAP1 axis in ISCs by DCA contributes to hepatic steatosis through the gut‒liver axis, which may provide a potential intestinal therapeutic target for MAFLD.

Analyzing the gut microbiota and microbial-associated metabolites of tomato-based sauces

Red Cooked Sauce (RCS) and Red Raw Sauce (RRS) are a mixture of natural crops that have a promising content of bioactive compounds (BC). The aim was to determine the effect of the indigestible fraction (IF) during the colonic fermentation in RCS and RRS by studying the two-way relationship between gut microbiota composition and microbial metabolites produced from BC fermented in the TNO in vitro dynamic model of the human colon (TIM-2). Total BC in undigested and predigested RRS, 957 and 715 mg/100 g DW, respectively, was significantly higher (p < 0.05) than in the RCS, 571 and 406 mg/100 g DW, respectively. Catenibacterium and Holdemanella increased during RCS fermentation, while 13 genera showed a clear positive correlation with most microbial phenolic metabolites. Our findings suggest that the mechanisms, pathways, and enzymes involved in producing microbial metabolites exhibited uniqueness among bacterial taxa, even within shared genus/family classifications.

Oral exposure to benzalkonium chlorides in male and female mice reveals alteration of the gut microbiome and bile acid profile

Benzalkonium chlorides (BACs) are commonly used disinfectants in a variety of consumer and food-processing settings, and the COVID-19 pandemic has led to increased usage of BACs. The prevalence of BACs raises the concern that BAC exposure could disrupt the gastrointestinal microbiota, thus interfering with the beneficial functions of the microbes. We hypothesize that BAC exposure can alter the gut microbiome diversity and composition, which will disrupt bile acid (BA) homeostasis along the gut-liver axis. In this study, male and female mice were exposed orally to d7-C12- and d7-C16-BACs at 120 µg/g/d for 1 wk. UPLC-MS/MS analysis of liver, blood, and fecal samples of BAC-treated mice demonstrated the absorption and metabolism of BACs. Both parent BACs and their metabolites were detected in all exposed samples. Additionally, 16S rRNA sequencing was carried out on the bacterial DNA isolated from the cecum intestinal content. For female mice, and to a lesser extent in males, we found that treatment with either d7-C12- or d7-C16-BAC led to decreased alpha diversity and differential composition of gut bacteria with notably decreased actinobacteria phylum. Lastly, through a targeted BA quantitation analysis, we observed decreases in secondary BAs in BAC-treated mice, which was more pronounced in the female mice. This finding is supported by decreases in bacteria known to metabolize primary BAs into secondary BAs, such as the families of Ruminococcaceae and Lachnospiraceae. Together, these data signify the potential impact of BACs on human health through disturbance of the gut microbiome and gut-liver interactions.

OM-85 attenuates high-fat diet-induced obesity, insulin resistance, gut dysbiosis and nonalcoholic steatohepatitis in a murine model

BACKGROUND

Obesity is a global epidemic that is tied to a wide range of human disorders. Chronic consumption of a high-fat diet is linked to disruption of the intestinal microbiome, which drives obesity-related pathophysiology. Broncho-Vaxom® (OM-85), a bacterial lysate used for prophylaxis of recurrent respiratory tract infections, has both immunostimulatory and immunomodulatory functions.

METHODS

Male C57Bl/6 mice were maintained on normal control vs. high-fat diets for 8 weeks and treated or untreated with OM-85 or with the probiotic Lactobacillus plantarum, as a positive control. Mice were evaluated for weight gain, glucose tolerance, insulin tolerance, gut microbiome composition and non-alcoholic steatohepatitis (NASH).

RESULTS

High-fat diet mice developed obesity, insulin resistance, NASH and gut dysbiosis with a shift from the Bacteroidetes phylum, such as Bacteroidales order and Muribaculaceae family organisms to Firmicutes groups, such as the Clostridium and Blautia genuses. Treatment with OM-85 led to 1) prevention of obesity, 2) prevention of insulin resistance, 3) attenuation of NASH and 4) attenuation of gut dysbiosis, with decreased levels of the organisms mentioned above and increases in Verrucomicrobiae phylum organisms such as Akkermansia family microbes as well as Muribaculaceae organisms. These shifts in the gut microbiome predict favorable effects on the short chain fatty acid profile in the gut and increased integrity of the intestinal barrier. Pathway analysis showed that OM-85 decreases rates of carbohydrate metabolism, providing an additional mechanism whereby OM-85 prevents obesity.

CONCLUSION

Immune modulators such as OM-85 should be investigated for their potential therapeutic effects on metabolism.

Gut Microbiota and Metabolic Dysfunction-Associated Steatotic Liver Disease

Background: The gut microbiota constitutes a complex microorganism community that harbors bacteria, viruses, fungi, protozoa, and archaea. The human gut bacterial microbiota has been extensively proven to participate in human metabolism, immunity, and nutrient absorption. Its imbalance, namely "dysbiosis", has been linked to disordered metabolism. Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the features of deranged human metabolism and is the leading cause of liver cirrhosis and hepatocellular carcinoma. Thus, there is a pathophysiological link between gut dysbiosis and MASLD. Aims and Methods: We aimed to review the literature data on the composition of the human bacterial gut microbiota and its dysbiosis in MASLD and describe the concept of the "gut-liver axis". Moreover, we reviewed the approaches for gut microbiota modulation in MASLD treatment. Results: There is consolidated evidence of particular gut dysbiosis associated with MASLD and its stages. The model explaining the relationship between gut microbiota and the liver has a bidirectional organization, explaining the physiopathology of MASLD. Oxidative stress is one of the keystones in the pathophysiology of MASLD and fibrosis generation. There is promising and consolidated evidence for the efficacy of pre- and probiotics in reversing gut dysbiosis in MASLD patients, with therapeutic effects. Few yet encouraging data on fecal microbiota transplantation (FMT) in MASLD are available in the literature. Conclusions: The gut dysbiosis characteristic of MASLD is a key target in its reversal and treatment via diet, pre/probiotics, and FMT treatment. Oxidative stress modulation remains a promising target for MASLD treatment, prevention, and reversal.

Causal impact of gut microbiota on five liver diseases: insights from mendelian randomization and single-cell RNA sequencing

Background

Liver disease is among the top ten causes of death globally. With studies suggesting a link between gut microbiota (GM) and liver disease.

Method

We selected summary statistics data from the largest available whole-genome association study (n = 13,266) of GM by the MiBioGen consortium as the exposure, and obtained liver disease-related data from IEU Open GWAS and The NHGRI-EBI GWAS Catalog. A two-sample Mendelian Randomization (MR) analysis employing various methods, to establish the causal relationship between GM and five liver diseases. Meanwhile, single-cell RNA sequencing data were used to examine Prevotella-related genes expression under healthy and disease liver.

Results

The IVW analysis indicate a causal relationship between GM and liver diseases, with Prevotella exhibiting a protective effect in all five liver diseases: Alcoholic liver disease (OR:0.81,95% confidence interval:0.66-1.00,P IVW = 0.0494); Cirrhosis (OR: 0.85,95% confidence interval: 0.73-0.99,P IVW = 0.0397); Hepatic failure, not elsewhere classified (OR:0.60,95% confidence interval:0.37-0.95,P IVW = 0.0305); Benign neoplasm:Liver (OR:0.39,95% confidence interval:0.2-0.75,P IVW = 0.0046); Malignant neoplasm of liver, primary (OR:0.41, 95% confidence interval:0.18-0.93,P IVW = 0.0334). The single-cell results suggest differential expression of Prevotella-related genes between liver disease patients and healthy individuals.

Conclusion

Our MR results show a causal relationship between the GM and liver disease. Prevotella displays a notable protective effect. This finding may enhance the precision of GM-based therapies and offer new insights for clinical research.

Type III Secretion System in Intestinal Pathogens and Metabolic Diseases

Modern lifestyle changes, especially the consumption of a diet high in salt, sugar, and fat, have contributed to the increasing incidence and prevalence of chronic metabolic diseases such as diabetes, obesity, and gout. Changing lifestyles continuously shape the gut microbiota which is closely related to the occurrence and development of metabolic diseases due to its specificity of composition and structural diversity. A large number of pathogenic bacteria such as Yersinia, Salmonella, Shigella, and pathogenic E. coli in the gut utilize the type III secretion system (T3SS) to help them resist host defenses and cause disease. Although the T3SS is critical for the virulence of many important human pathogens, its relationship with metabolic diseases remains unknown. This article reviews the structure and function of the T3SS, the disruption of intestinal barrier integrity by the T3SS, the changes in intestinal flora containing the T3SS in metabolic diseases, the possible mechanisms of the T3SS affecting metabolic diseases, and the application of the T3SS in the treatment of metabolic diseases. The aim is to provide insights into metabolic diseases targeting the T3SS, thereby serving as a valuable reference for future research on disease diagnosis, prevention, and treatment.

Dynamic Hydration and Viscosity Control of Konjac Glucomannan Enhance Long-Term Antiobesity Effects by Reducing Food Intake in High-Fat-Diet-Fed Mice

The purpose of this study was to investigate the necessity and importance of dynamic hydration rate and ultimate viscosity control of konjac glucomannan (KGM) for long-term antiobesity effects in C57BL/6J mice on high-fat (HF) diets. KGM supplementation effectively attenuated HF-diet-induced increases in body and tissue weights. The hydration rate and viscosity changes of KGM in the digestive tract were found to have marked impacts on antiobesity effects. KGM with medium hydration and viscosity slowed gastric emptying and intestinal transit, leading to prolonged presence in the lower ileum, increased satiety-related hormones (GLP-1 and PYY), and an 18.27% reduction in daily food intake over 10 weeks (p < 0.05). This resulted in the greatest reduction in weight gain among HF-fed mice. In contrast, KGM with faster hydration and higher viscosity provided only short-term satiety due to rapid dilution. Furthermore, KGM improved metabolic health and altered glycolipid metabolism gene transcription while enriching beneficial gut bacteria; however, no significant differences were observed among the KGM groups in these effects. These findings highlight that synchronizing KGM's hydration rate and viscosity with digestive processes is crucial for regulating satiety and achieving long-term weight loss.

Compound oolong tea ameliorates lipid accumulation through AMPK-PPAR pathway of hepatic lipid metabolism and modulates gut microbiota in HFD induced mice

Based on the modified traditional Chinese formula, Compound Oolong tea (WLT) is composed of six herbal medicines which have beneficial effects. The present study aimed to assess the effects of WLT on lipid metabolism and gut microbiota in the mouse obesity model.Totally 32 mice were randomized into 4 groups including normal control (NC), high-fat diet model (HFD), positive control (PC) receiving atorvastatin 10 mg/kg/d, and WLT group with WLT water extra 300 mg/kg/d. The HFD, PC, WLT groups were fed a High-fat Diet. The results show that body weight, Lee's index, liver index and fat index were reduced in WLT. Moreover, the accumulation of TC, TG, and LDL-C were lower, and the level of serum HDL-C in WLT was higher than HFD. The activities of ALT and AST were reduced, and the glucose tolerance was improved in WLT. Furthermore, the relative gene expression of hepatic such as Pparγ, Lxr, Srebp-1c, Srebp-2, Scd-1, Acc-1, Fas were upregulated, and Hmgcr was downregulated in WLT compared to HFD. The relative protein expression of PPARγ, SREBP-1, FAS, and SCD-1 were decreased, and p-AMPK/AMPK and p-ACC-1/ACC-1 were increased in WLT compared with HFD. In addition, the diversity of gut microbiota was increased in mice, with an increase in Bacteroidota and a decrease in Firmicutes and Desulfovibrionales were decreased in WLT, compared with HFD. Briefly, WLT improves hepatic lipid metabolism through the AMPK-PPAR pathway and regulates the gut microbiome. These findings suggest that WLT could potentially be used as a functional food ingredients for preventing obesity.

Synergistic Effects of Fructose and Food Preservatives on Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): From Gut Microbiome Alterations to Hepatic Gene Expression

Background/Objectives: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing global health problem closely linked to dietary habits, particularly high fructose consumption. This study investigates the combined effects of fructose and common food preservatives (sodium benzoate, sodium nitrite, and potassium sorbate) on the development and progression of MASLD. Methods: We utilized a human microbiota-associated mouse model, administering 10% fructose with or without preservatives for 11 weeks. Liver histology, hepatic gene expression (microarray analysis), biochemical markers, cytokine profiles, intestinal permeability, and gut microbiome composition (16S rRNA and Internal Transcribed Spacer (ITS) sequencing) were evaluated. Results: Fructose and potassium sorbate synergistically induced liver pathology characterized by increased steatosis, inflammation and fibrosis. These histological changes were associated with elevated liver function markers and altered lipid profiles. The treatments also induced significant changes in both the bacterial and fungal communities and disrupted intestinal barrier function, leading to increased pro-inflammatory responses in the mesenteric lymph nodes. Liver gene expression analysis revealed a wide range of transcriptional changes induced by fructose and modulated by the preservative. Key genes involved in lipid metabolism, oxidative stress, and inflammatory responses were affected. Conclusions: Our findings highlight the complex interactions between dietary components, gut microbiota, and host metabolism in the development of MASLD. The study identifies potential risks associated with the combined consumption of fructose and preservatives, particularly potassium sorbate. Our data reveal new mechanisms that are involved in the development of MASLD and open up a new avenue for the prevention and treatment of MASLD through dietary interventions and the modulation of the microbiome.

Metagenome-based characterization of the gut bacteriome, mycobiome, and virome in patients with chronic hepatitis B-related liver fibrosis

Introduction

The gut microbiota is believed to be directly involved in the etiology and development of chronic liver diseases. However, the holistic characterization of the gut bacteriome, mycobiome, and virome in patients with chronic hepatitis B-related liver fibrosis (CHB-LF) remains unclear.

Methods

In this study, we analyzed the multi-kingdom gut microbiome (i.e., bacteriome, mycobiome, and virome) of 25 CHB-LF patients and 28 healthy individuals through whole-metagenome shotgun sequencing of their stool samples.

Results

We found that the gut bacteriome, mycobiome, and virome of CHB-LF patients were fundamentally altered, characterized by a panel of 110 differentially abundant bacterial species, 16 differential fungal species, and 90 differential viruses. The representative CHB-LF-enriched bacteria included members of Blautia_A (e.g., B. wexlerae, B. massiliensis, and B. obeum), Dorea (e.g., D. longicatena and D. formicigenerans), Streptococcus, Erysipelatoclostridium, while some species of Bacteroides (e.g., B. finegoldii and B. thetaiotaomicron), Faecalibacterium (mainly F. prausnitzii), and Bacteroides_A (e.g., B. plebeius_A and B. coprophilus) were depleted in patients. Fungi such as Malassezia spp. (e.g., M. japonica and M. sympodialis), Candida spp. (e.g., C. parapsilosis), and Mucor circinelloides were more abundant in CHB-LF patients, while Mucor irregularis, Phialophora verrucosa, Hortaea werneckii, and Aspergillus fumigatus were decreases. The CHB-LF-enriched viruses contained 18 Siphoviridae, 12 Myoviridae, and 1 Podoviridae viruses, while the control-enriched viruses included 16 Siphoviridae, 9 Myoviridae, 2 Quimbyviridae, and 1 Podoviridae_crAss-like members. Moreover, we revealed that the CHB-LF-associated gut multi-kingdom signatures were tightly interconnected, suggesting that they may act together on the disease. Finally, we showed that the microbial signatures were effective in discriminating the patients from healthy controls, suggesting the potential of gut microbiota in the prediction of CHB-LF and related diseases.

Discussion

In conclusion, our findings delineated the fecal bacteriome, mycobiome, and virome landscapes of the CHB-LF microbiota and provided biomarkers that will aid in future mechanistic and clinical intervention studies.

Predicting acute lung injury in infants with congenital heart disease after cardiopulmonary bypass by gut microbiota

Background

Acute lung injury (ALI) is a serious and common complication that occurs in children with congenital heart disease after cardiopulmonary bypass (CPB) surgery, leading to higher mortality rates and poorer prognosis. Currently, there is no reliable predictive strategy for CPB-associated lung injury (CPB-ALI) in infants. Certain characteristics of the gut microbiota could potentially serve as biomarkers for predicting the development of CPB-ALI.

Methods

We conducted 16S rRNA sequencing to analyze the characteristics of the intestinal microbiota in healthy controls and infants with CHD admitted to the hospital. The CHD infants were divided into CPB-ALI and non-ALI (CPB-NALI) groups based on postoperative outcomes. Bacterial functional pathway prediction analysis was performed using PIRCUSt2, and the gut microbiota composition associated with immune status was determined with heatmap. Random forest regression models and ROC curves were utilized to predict the occurrence of CPB-ALI.

Results

Our study revealed significantly different microbiota compositions among three groups (CON, CPB-ALI, and CPB-NALI). The microbiota diversity was low in the CPB-ALI group with high pathogen abundance and significant decrease in Bacteroides, while the opposite was observed in the CPB-NALI group. The microbiota dysbiosis index was high in the CPB-ALI group, with its dominant microbiota significantly associated with multiple metabolic pathways. Additionally, CPB-ALI patients showed high levels of inflammatory cytokines IL-8 and HMGB1 in their serum, with high expression of IL-8 being associated with Enterobacteriaceae. Further correlation analysis showed that the differences in gut bacterial taxonomy were related to the occurrence of ALI, length of stay in the cardiac care unit, and ventilation time. It is noteworthy that Escherichia Shigella performed best in distinguishing CPB-ALI patients from non-ALI patients.

Conclusions

Our study suggests that postoperative ALI patients have distinct gut microbiota upon admission compared to non-ALI patients after surgery. Dysbiosis of the gut microbiota may potentially impact the progression of ALI through metabolic pathways, quorum sensing, and the levels of inflammatory factors expressed in the serum. Escherichia Shigella represents a potential predictive factor for the occurrence of ALI in CHD infants after surgery. Acute lung injury, congenital heart disease, cardiopulmonary bypass surgery, gut microbiota, biomarker.

The impact of traditional Chinese medicine and dietary compounds on modulating gut microbiota in hepatic fibrosis: A review

Traditional Chinese medicine (TCM) and dietary compounds have a profound influence on the regulation of gut microbiota (GM) in hepatic fibrosis (HF). Certain substances found in both food and herbs that are edible and medicinal, such as dietary fiber, polyphenols, and polysaccharides, can generate beneficial metabolites like short-chain fatty acids (SCFAs), bile acids (BAs), and tryptophan (Trp). These compounds contribute to regulate the GM, reduce levels of endotoxins in the liver, and alleviate fibrosis and inflammation in the liver. Furthermore, they enhance the composition and functionality of GM, promoting the growth of beneficial bacteria while inhibiting the proliferation of harmful bacteria. These mechanisms mitigate the inflammatory response in the intestines and maintain the integrity of the intestinal barrier. The purpose of this review is to analyze how the GM regulates the pathogenesis of HF, evaluate the regulatory effect of TCM and dietary compounds on the intestinal microflora, with a particular emphasis on modulating flora structure, enhancing gut barrier function, and addressing associated pathogenic factors, thereby provide new insights for the treatment of HF.

Epidemiological Study on the Interaction between the PNPLA3 (rs738409) and Gut Microbiota in Metabolic Dysfunction-Associated Steatotic Liver Disease

Many factors are associated with the development and progression of metabolic dysfunction-associated steatotic liver disease (MASLD); however, genetics and gut microbiota are representative factors. Recent studies have highlighted the link between host genes and the gut microbiota. Although there have been many studies on the separate effects of single nucleotide polymorphisms (SNPs) and gut bacteria on MASLD, few epidemiological studies have examined how SNPs and gut bacteria interact in the development and progression of MASLD. This study aimed to investigate the association between PNPLA3 rs738409, a representative MASLD-related SNP, and gut bacteria in MASLD using a cross-sectional study of the general population. The 526 participants (318 normal and 208 MASLD groups) were grouped into the PNPLA3 rs738409 SNP, CC, CG, and GG genotypes, and the differences in the gut microbiota were investigated in each group. The PNPLA3 rs738409 CC and CG genotypes were associated with decreased Blautia and Ruminococcaceae in the MASLD group. They were negatively correlated with controlled attenuation parameter levels, body mass index, serum blood glucose, and triglycerides. In contrast, there was no association between the normal and MASLD groups and the gut bacteria in the PNPLA3 rs738409, the GG genotype group. This finding implies that dietary interventions and probiotics may be more effective in preventing and treating MASLD in individuals with the PNPLA3 rs738409 CC and CG genotypes. In contrast, their efficacy may be limited in those with the GG genotype.

Rutin, a natural flavonoid glycoside, ameliorates zearalenone induced liver inflammation via inhibiting lipopolysaccharide gut leakage and NF-κB signaling pathway in mice

Zearalenone (ZEN) poses a potential threat on human and animal health partly through the nuclear factor (NF)-κB signaling pathway. In silico study suggested that rutin effective against TLR4 and NF-κB. A wetting test was designed to evaluate the effect and underlying mechanism of rutin in alleviating ZEN-induced inflammation in animals. Twenty-four female mice were randomly divided into 4 groups: control (basal diet), ZEN group (basal diet + ZEN), rutin group (basic diet + rutin), Z + R group (basal diet + rutin + ZEN). Results showed that rutin effectively alleviated ZEN-induced inflammation and damage of liver and jejunum in mice. Rutin addition reduced the content of lipopolysaccharide (LPS) in serum and liver mainly by improving the intestinal barrier function resulted from the production increase of short-chain fatty acids (SCFA). In sum, this study showed that rutin alleviated ZEN-induced liver inflammation and injury by modulating the gut microbiota, increasing the production of SCFA and improving intestinal barrier function, leading to the decrease of LPS in liver and the inhibition of MyD88 independent NF-κB signaling pathway in mice. Specifically, these findings may provide useful insights into the screening of functional natural compounds and its action mechanism to alleviate ZEN induced liver inflammation.

Causal relationship between gut microbiota and male erectile dysfunction: a Mendelian randomization analysis

Background

Several observational studies have reported an association between gut microbiota and male erectile dysfunction (ED). However, it remains unclear whether there is a causal relationship between gut microbiota and male ED. Thus, we aimed to investigate the potential causal relationship between gut microbiota and male ED through Mendelian randomization (MR) analysis.

Objective

To assess the causal relationship between gut microbiota and male ED, we performed a two-sample MR analysis.

Methods

We obtained gut microbiota genome-wide association studies (GWAS) data from the MiBioGen consortium and publicly available GWAS data on male ED from the OPEN GWAS database. Subsequently, we performed a two-sample MR analysis to evaluate the causal relationship between gut microbiota and male ED. Finally, we performed sensitivity analysis, including Cochran's Q test, MR-Egger intercept analysis, MR-PRESSO, and leave-one-out analysis, to assess the level of heterogeneity and horizontal pleiotropy in the results.

Results

Our MR analysis revealed a negative causal relationship between the genus Ruminococcaceae UCG013 and male ED (OR = 0.761, 95% CI 0.626-0.926), while the family Lachnospiraceae, genus Lachnospiraceae NC2004 group, genus Oscillibacter, and genus Tyzzerella3 may be associated with an increased risk of male ED, with the highest risk observed for family Lachnospiraceae (OR = 1.264, 95% CI 1.063-1.504). Furthermore, sensitivity analysis confirmed the reliability of our positive findings.

Conclusion

Our MR analysis revealed a causal relationship between gut microbiota and male ED. This may contribute to a better understanding of the potential applications of gut microbiota in the occurrence and treatment of male ED.

Beneficial Effects of the Ketogenic Diet on Nonalcoholic Fatty Liver Disease (NAFLD/MAFLD)

The prevalence of nonalcoholic fatty liver disease (NAFLD) is likely to be approaching 38% of the world's population. It is predicted to become worse and is the main cause of morbidity and mortality due to hepatic pathologies. It is particularly worrying that NAFLD is increasingly diagnosed in children and is closely related, among other conditions, to insulin resistance and metabolic syndrome. Against this background is the concern that the awareness of patients with NAFLD is low; in one study, almost 96% of adult patients with NAFLD in the USA were not aware of their disease. Thus, studies on the therapeutic tools used to treat NAFLD are extremely important. One promising treatment is a well-formulated ketogenic diet (KD). The aim of this paper is to present a review of the available publications and the current state of knowledge of the effect of the KD on NAFLD. This paper includes characteristics of the key factors (from the point of view of NAFLD regression), on which ketogenic diet exerts its effects, i.e., reduction in insulin resistance and body weight, elimination of fructose and monosaccharides, limitation of the total carbohydrate intake, anti-inflammatory ketosis state, or modulation of gut microbiome and metabolome. In the context of the evidence for the effectiveness of the KD in the regression of NAFLD, this paper also suggests the important role of taking responsibility for one's own health through increasing self-monitoring and self-education.

Effects of Synbiotic Administration on Gut Microbiome and Fecal Bile Acids in Dogs with Chronic Hepatobiliary Disease: A Randomized Case-Control Study

Alteration in the gut microbiome in human patients with chronic liver disease is a well-known pathophysiological mechanism. Therefore, it represents both a diagnostic and therapeutical target. Intestinal dysbiosis has also been identified in dogs with chronic liver disease, but clinical trials evaluating the effectiveness of synbiotic administration are lacking. Thirty-two dogs with chronic hepatobiliary disease were equally randomized into two groups: one treated with a synbiotic complex for 4-6 weeks (TG) and one untreated control group (CG). All dogs underwent clinical evaluation, complete anamnesis, bloodwork, abdominal ultrasound, fecal bile acids, and gut microbiome evaluation at T0-T1 (after 4-6 weeks). Treated dogs showed a significant reduction in ALT activity (p = 0.007) and clinical resolution of gastrointestinal signs (p = 0.026) compared to control dogs. The synbiotic treatment resulted in a lower increase in Enterobacteriaceae and Lachnospiraceae compared to the control group but did not affect the overall richness and number of bacterial species. No significant changes in fecal bile acids profile were detected with synbiotic administration. Further studies are needed to better evaluate the effectiveness of synbiotic administration in these patients and the metabolic pathways involved in determining the clinical and biochemical improvement.

Vinpocetine and Lactobacillus improve fatty liver in rats: role of adiponectin and gut microbiome

Therapeutics that interfere with the damage/pathogen-associated molecular patterns (DAMPs/PAMPs) have evolved as promising candidates for hepatic inflammation like that occurring in non-alcoholic fatty liver disease (NAFLD). In the current study, we examined the therapeutic impact of the phosphodiesterase-1 inhibitor vinpocetine (Vinpo), alone or when combined with Lactobacillus, on hepatic abnormalities caused by a 13-week high-fat diet (HFD) and diabetes in rats. The results show that Vinpo (10 and 20 mg/kg/day) dose-dependently curbed HFD-induced elevation of liver injury parameters in serum (ALT, AST) and tissue histopathology. These effects were concordant with Vinpo's potential to ameliorate HFD-induced fibrosis (Histological fibrosis score, hydroxyproline, TGF-β1) and oxidative stress (MDA, NOx) alongside restoring the antioxidant-related parameters (GSH, SOD, Nrf-2, HO-1) in the liver. Mechanistically, Vinpo attenuated the hepatocellular release of DAMPs like high mobility group box (HMGB)1 alongside lowering the overactivation of the pattern recognition receptors including, toll-like receptor (TLR)4 and receptor for advanced glycation end-products (RAGE). Consequently, there was less activation of the transcription factor nuclear factor-kappa B that lowered production of the proinflammatory cytokines TNF-α and IL-6 in Vinpo-treated HFD/diabetes rats. Compared to Vinpo treatment alone, Lactobacillus probiotics as adjunctive therapy with Vinpo significantly improved the disease-associated inflammation and oxidative stress injury, as well as the insulin resistance and lipid profile abnormalities via enhancing the restoration of the symbiotic microbiota. In conclusion, combining Vinpo and Lactobacillus probiotics may be a successful approach for limiting NAFLD in humans.

Pemafibrate abrogates SLD in a rat experimental dietary model, inducing a shift in fecal bile acids and microbiota composition

BACKGROUND AND AIMS

Drugs resolving steatotic liver disease (SLD) could prevent the evolution of metabolic dysfunction associated SLD (MASLD) to more aggressive forms but must show not only efficacy, but also a high safety profile. Repurposing of drugs in clinical use, such as pemafibrate and mirabegron, could facilitate the finding of an effective and safe drug-treatment for SLD.

APPROACH AND RESULTS

The SLD High Fat High Fructose (HFHFr) rat model develops steatosis without the influence of other metabolic disturbances, such as obesity, inflammation, or type 2 diabetes. Further, liver fatty acids are provided, as in human pathology, both from dietary origin and de novo lipid synthesis. We used the HFHFr model to evaluate the efficacy of pemafibrate and mirabegron, alone or in combination, in the resolution of SLD, analyzing zoometric, biochemical, histological, transcriptomic, fecal metabolomic and microbiome data. We provide evidence showing that pemafibrate, but not mirabegron, completely reverted liver steatosis, due to a direct effect on liver PPARα-driven fatty acid catabolism, without changes in total energy consumption, subcutaneous, perigonadal and brown fat, blood lipids and body weight. Moreover, pemafibrate treatment showed a neutral effect on whole-body glucose metabolism, but deeply modified fecal bile acid composition and microbiota.

CONCLUSIONS

Pemafibrate administration reverts liver steatosis in the HFHFr dietary rat SLD model without altering parameters related to metabolic or organ toxicity. Our results strongly support further clinical research to reposition pemafibrate for the treatment of SLD/MASLD.

Monascus red pigments alleviate high-fat and high-sugar diet-induced NAFLD in mice by modulating the gut microbiota and metabolites

Monascus red pigments (MRP) may have benefits against NAFLD with an unclear mechanism. This study aimed to explore the protective effect of MRP supplementation against NAFLD through regulation of gut microbiota and metabolites. The C57BL/6 mice animals were randomly allocated into the normal diet (NC), HFHS diet-induced NAFLD model, and MRP intervention group fed with HFHS diet. Serum lipid profiles and liver function parameters were measured. Liver and colon histopathology analysis was conducted to determine the injury in the liver and colon. 16S rRNA gene sequencing was employed to analyze gut microbial composition from fecal samples. Untargeted metabonomics was performed to analyze changes in metabolites in serum and fecal samples. MRP supplementation significantly improved the HFHS-induced alterations in body weight, lipid profiles, and liver function (p < .01). MRP supplementation decreased the abundance of Akkermansia, Candidatus saccharimonas, Dubosiella, and Oscillibacter, while increasing Lactobacillus, Lachnospiraceae NK4A136 group, and Rikenella in mice fed the HFHS diet. Furthermore, MRP supplementation improved the serum and fecal metabolic profiles induced by the HFHS diet, primarily involving the arachidonic acid metabolism, unsaturated fatty acid biosynthesis, and adipocyte lipolysis pathways. Liver function and lipid profiles were closely associated with the abundance of Lactobacillus, Streptococcus, Oscillibacter, Akkemansia, and Desulfovibrio (p < .01). These findings revealed that MRP supplementation may help restore gut microbiota composition and balance its metabolites, thereby improving NAFLD. This study presents a novel outlook on the potential benefits of MRP supplementation in ameliorating NAFLD and supports the application of MRP as a new functional food.

FGL2 improves experimental colitis related to gut microbiota structure and bile acid metabolism by regulating macrophage autophagy and apoptosis

Inflammatory bowel disease (IBD) is a refractory disease with immune abnormalities and pathological changes. Intestinal macrophages are considered to be the main factor in establishing and maintaining intestinal homeostasis. The immunoregulatory and anti-inflammatory activity of fibrinogen-like protein 2 (FGL2) can regulate macrophage polarization. However, its function in IBD is unclear. In this study, we explored the effect of FGL2 on macrophage polarization, autophagy, and apoptosis in bone marrow-derived macrophages (BMDMs) treated with lipopolysaccharide (LPS) and further investigated changes in the intestinal barrier, flora, and bile acid in dextran sodium sulfate (DSS)-treated mice. Our results demonstrated that FGL2-/- weakened ERK signaling to promote M1 polarization and upregulate inflammation, autophagy, and apoptosis in LPS-stimulated BMDMs. rFGL2 treatment reversed these effects. FGL2-/- mice exhibited higher sensitivity to DSS exposure, with faster body weight loss, shorter colon lengths, and higher disease activity index (DAI) values. rFGL2 treatment protected against experimental ulcerative colitis (UC), restrained excessive autophagy, apoptosis, and improved gut barrier impairment. Gut microbiota structure and bile acid homeostasis were more unbalanced in FGL2-/- DSS mice than in wild-type (WT) DSS mice. rFGL2 treatment improved gut microbiota structure and bile acid homeostasis. Altogether, our results established that FGL2 is a potential therapeutic target for IBD.

The effect of gut microbiome and plasma metabolome on systemic sclerosis: a bidirectional two-sample Mendelian randomization study

Background

Cellular and molecular biology, combined with research on the human microbiome and metabolome, have provided new insights into the pathogenesis of systemic sclerosis (SSc). However, most studies on gut microbiota (GM) and metabolome in SSc are observational studies. The impact of confounding factors and reverse causation leads to different insights. To shed light on this matter, we utilized Mendelian randomization (MR) to determine the causal effect of GM/metabolites on SSc.

Methods

Based on summary-level data from genome-wide association studies, bidirectional Two-sample MR was conducted involving 196 GM, 1400 plasma metabolism, and 9,095 SSc. Inverse Variance Weighting (IVW) was mainly used for effect estimation.

Results

Forward MR analysis found that three GM and two plasma metabolites are causally related to SSc. IVW results showed Victivallaceae (family) (OR, 1.469; 95%CI, 1.099-1.963; p = 0.009) and LachnospiraceaeUCG004 (genus) (OR, 1.548; 95%CI, 1.020-2.349; p = 0.04) were risk factor of SSc. Conversely, Prevotella7 (genus) (OR, 0.759; 95%CI, 0.578-0.997; p = 0.048)was a protective factor of SSc. The results on plasma metabolites indicated that Pregnenediol disulfate (C21H34O8S2) levels (OR, 1.164; 95%CI, 1.006-1.347; p = 0.041)was a risk factor of SSc, while Sphingomyelin (d18:1/19:0, d19:1/18:0) levels (OR, 0.821; 95%CI, 0.677-0.996; p = 0.045)was a protective factor of SSc. Reverse MR analysis did not find causally relationship between SSc and the above GM/plasma metabolites.

Conclusion

Our results revealed the causally effect between GM/plasma metabolites and SSc. These findings provided new insights into the mechanism of SSc. In particular, we demonstrated Prevotella7 was a protective factor of SSc despite its controversial role in SSc in previous researches.

Transformation of 6:6 PFPiA in the gut of Xenopus laevis: Synergistic effects of CYP450 enzymes and gut microflora

As a frequently detected per- and polyfluoroalkyl substance in the environment, 6:6 perfluoroalkylhypophosphinic acid (6:6 PFPiA) is vulnerable to transformation in the liver of organisms, but the transformation in gut is still unclear. This study investigates the molecular mechanisms of 6:6 PFPiA transformation in the gut of Xenopus laevis upon a 28-day exposure in water. Before Day 16, a notable correlation (p = 0.03) was observed between the transformation product (PFHxPA) and cytochrome P450 (CYP450) enzyme concentration in gut. This suggests that CYP450 enzymes played an important role in the transformation of 6:6 PFPiA in the gut, which was verified by an in vitro incubation with gut tissues, and supported by the molecular docking results of 6:6 PFPiA binding with CYP450 enzymes. From the day 16, the CYP450 concentration in gut decreased by 31.3 % due to the damage caused by 6:6 PFPiA, leading to a decrease in the transformation capacity in gut, but the transformation rate was stronger than in liver. This was in contrast with the in vitro experiment, where transformation was stronger in liver. In the mean time, the abundance of Bacteroidota in gut increased, which released hydrolytic enzyme and then could participate in the transformation as well. This study reveals the potential of the gut in metabolizing environmental pollutants, and provides profound insights into the potential health risks caused by 6:6 PFPiA in organisms.

An examination of global research trends for exploring the associations between the gut microbiota and nonalcoholic fatty liver disease through bibliometric and visualization analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as a significant health issue. Emerging research has focused on the role of the gut microbiota in NAFLD, emphasizing the gut-liver axis. This study aimed to identify key research trends and guide future investigations in this evolving area.

METHODS

This bibliometric study utilized Scopus to analyze global research on the link between the gut microbiota and NAFLD. The method involved a search strategy focusing on relevant keywords in article titles, refined by including only peer-reviewed journal articles. The data analysis included bibliometric indicators such as publication counts and trends, which were visualized using VOSviewer software version 1.6.20 for network and co-occurrence analysis, highlighting key research clusters and emerging topics.

RESULTS

Among the 479 publications on the gut microbiota and NAFLD, the majority were original articles (n = 338; 70.56%), followed by reviews (n = 119; 24.84%). The annual publication count increased from 1 in 2010 to 118 in 2022, with a significant growth phase starting in 2017 (R2 = 0.9025, p < 0.001). The research was globally distributed and dominated by China (n = 231; 48.23%) and the United States (n = 90; 18.79%). The University of California, San Diego, led institutional contributions (n = 18; 3.76%). Funding was prominent, with 62.8% of the articles supported, especially by the National Natural Science Foundation of China (n = 118; 24.63%). The average citation count was 43.23, with an h-index of 70 and a citation range of 0 to 1058 per article. Research hotspots shifted their focus post-2020 toward the impact of high-fat diets on NAFLD incidence.

CONCLUSIONS

This study has effectively mapped the growing body of research on the gut microbiota-NAFLD relationship, revealing a significant increase in publications since 2017. There is significant interest in gut microbiota and NAFLD research, mainly led by China and the United States, with diverse areas of focus. Recently, the field has moved toward exploring the interconnections among diet, lifestyle, and the gut-liver axis. We hypothesize that with advanced technologies, new opportunities for personalized medicine and a holistic understanding of NAFLD will emerge.

Human Gut Microbiota in Cardiovascular Disease

The gut ecosystem, termed microbiota, is composed of bacteria, archaea, viruses, protozoa, and fungi and is estimated to outnumber human cells. Microbiota can affect the host by multiple mechanisms, including the synthesis of metabolites and toxins, modulating inflammation and interaction with other organisms. Advances in understanding commensal organisms' effect on human conditions have also elucidated the importance of this community for cardiovascular disease (CVD). This effect is driven by both direct CV effects and conditions known to increase CV risk, such as obesity, diabetes mellitus (DM), hypertension, and renal and liver diseases. Cardioactive metabolites, such as trimethylamine N -oxide (TMAO), short-chain fatty acids (SCFA), lipopolysaccharides, bile acids, and uremic toxins, can affect atherosclerosis, platelet activation, and inflammation, resulting in increased CV incidence. Interestingly, this interaction is bidirectional with microbiota affected by multiple host conditions including diet, bile acid secretion, and multiple diseases affecting the gut barrier. This interdependence makes manipulating microbiota an attractive option to reduce CV risk. Indeed, evolving data suggest that the benefits observed from low red meat and Mediterranean diet consumption can be explained, at least partially, by the changes that these diets may have on the gut microbiota. In this article, we depict the current epidemiological and mechanistic understanding of the role of microbiota and CVD. Finally, we discuss the potential therapeutic approaches aimed at manipulating gut microbiota to improve CV outcomes. © 2024 American Physiological Society. Compr Physiol 14:5449-5490, 2024.

A Novel Antioxidant, Hydrogen-Rich Coral Calcium Alters Gut Microbiome and Bile Acid Synthesis to Improve Methionine-and-Choline-Deficient Diet-Induced Non-Alcoholic Fatty Liver Disease

The prevalence of non-alcoholic fatty liver disease (NAFLD) has dramatically increased in recent years, and it is highly associated with metabolic diseases, as well as the development of hepatocellular carcinoma. However, effective therapeutic strategies for the treatment of NAFLD are still scarce. Although hydrogen-rich water shows beneficial effects for hepatic steatosis, the inconvenience limits the application of this antioxidant. In light of this, hydrogen-rich coral calcium (HRCC) was developed due to its convenience and quantifiable characteristics. However, the effects of HRCC on NAFLD are still unknown. In the present study, we found that HRCC treatment improved methionine-and-choline-deficient diet (MCD)-induced hepatic steatosis, increased aspartate aminotransferase and alanine aminotransferase levels, and elevated hepatic inflammatory factor expressions in mice. In addition to the increased expressions of antioxidative enzymes, we found that HRCC increased the expressions of bile acid biosynthesis-related genes, including Cyp8b1 and Cyp27a1. Increased hepatic bile acid contents, such as muricholic acids, 23 nor-deoxycholic acid, glycoursodeoxycholic acid, and cholic acids, were also confirmed in MCD mice treated with HRCC. Since the biogenesis of bile acids is associated with the constitution of gut microbiome, the alterations in gut microbiome by HRCC were evaluated. We found that HRCC significantly changed the constitution of gut microbiome in MCD mice and increased the contents of Anaerobacterium, Acutalibacter, Anaerosacchariphilus, and Corynebacterium. Taken together, HRCC improved MCD-induced NAFLD through anti-inflammatory mechanisms and by increasing antioxidative activities. Additionally, HRCC might alter gut microbiome to change hepatic bile acid contents, exerting beneficial effects for the treatment of NAFLD.

Distinct Gut Microbial Signature and Host Genetic Variants in Association with Liver Fibrosis Severity in Patients with MASLD

Gut microbiota might affect the severity and progression of metabolic dysfunction-associated steatotic liver disease (MASLD). We aimed to characterize gut dysbiosis and clinical parameters regarding fibrosis stages assessed by magnetic resonance elastography. This study included 156 patients with MASLD, stratified into no/mild fibrosis (F0-F1) and moderate/severe fibrosis (F2-F4). Fecal specimens were sequenced targeting the V4 region of the 16S rRNA gene and analyzed using bioinformatics. The genotyping of PNPLA3, TM6SF2, and HSD17B13 was assessed by allelic discrimination assays. Our data showed that gut microbial profiles between groups significantly differed in beta-diversity but not in alpha-diversity indices. Enriched Fusobacterium and Escherichia_Shigella, and depleted Lachnospira were found in the F2-F4 group versus the F0-F1 group. Compared to F0-F1, the F2-F4 group had elevated plasma surrogate markers of gut epithelial permeability and bacterial translocation. The bacterial genera, PNPLA3 polymorphisms, old age, and diabetes were independently associated with advanced fibrosis in multivariable analyses. Using the Random Forest classifier, the gut microbial signature of three genera could differentiate the groups with high diagnostic accuracy (AUC of 0.93). These results indicated that the imbalance of enriched pathogenic genera and decreased beneficial bacteria, in association with several clinical and genetic factors, were potential contributors to the pathogenesis and progression of MASLD.

Pleurotus eryngii polysaccharides alleviate aflatoxin B1-induced liver inflammation in ducks involving in remodeling gut microbiota and regulating SCFAs transport via the gut-liver axis

Aflatoxin B1 (AFB1) is one of the most widespread contaminants in agricultural commodities. Pleurotus eryngii (PE) is widely used as a feed additive for its anti-inflammatory properties, and its major active substance is believed to be polysaccharides. This study aims to explore the underlying mechanism of dietary PE polysaccharides alleviating AFB1-induced toxicity in ducks. The major monosaccharide components of PE polysaccharides were identified as glucose, mannose, galactose, glucuronic acid, and fucose. The results showed that dietary PE polysaccharides could alleviate liver inflammation, alleviate intestinal barrier dysfunction, and change the imbalanced gut microbiota induced by AFB1 in ducks. However, PE polysaccharides failed to exert protective roles on the liver and intestine injury induced by AFB1 in antibiotic-treated ducks. The PE + AFB1-originated microbiota showed a positive effect on intestinal barrier and inflammation, the SCFAs transport via the gut-liver axis, and liver inflammation compared with the AFB1-originated microbiota in ducks. These findings provided a possible mechanism that PE polysaccharides alleviated AFB1-induced liver inflammation in ducks by remodeling gut microbiota, regulating microbiota-derived SCFAs transport via the gut-liver axis, and inhibiting inflammatory gene expressions in the liver, which may provide new insight for therapeutic methods against AFB1 exposure in animals.

Oral Exposure to Benzalkonium Chlorides in Male and Female Mice Reveals Sex-Dependent Alteration of the Gut Microbiome and Bile Acid Profile

Benzalkonium chlorides (BACs) are commonly used disinfectants in a variety of consumer and food-processing settings, and the COVID-19 pandemic has led to increased usage of BACs. The prevalence of BACs raises the concern that BAC exposure could disrupt the gastrointestinal microbiota, thus interfering with the beneficial functions of the microbes. We hypothesize that BAC exposure can alter the gut microbiome diversity and composition, which will disrupt bile acid homeostasis along the gut-liver axis. In this study, male and female mice were exposed orally to d 7 -C12- and d 7 -C16-BACs at 120 µg/g/day for one week. UPLC-MS/MS analysis of liver, blood, and fecal samples of BAC-treated mice demonstrated the absorption and metabolism of BACs. Both parent BACs and their metabolites were detected in all exposed samples. Additionally, 16S rRNA sequencing was carried out on the bacterial DNA isolated from the cecum intestinal content. For female mice, and to a lesser extent in males, we found that treatment with either d 7 -C12- or d 7 -C16-BAC led to decreased alpha diversity and differential composition of gut bacteria with notably decreased actinobacteria phylum. Lastly, through a targeted bile acid quantitation analysis, we observed decreases in secondary bile acids in BAC-treated mice, which was more pronounced in the female mice. This finding is supported by decreases in bacteria known to metabolize primary bile acids into secondary bile acids, such as the families of Ruminococcaceae and Lachnospiraceae. Together, these data signify the potential impact of BACs on human health through disturbance of the gut microbiome and gut-liver interactions.

Gut microbiota induced epigenetic modifications in the non-alcoholic fatty liver disease pathogenesis

Non-alcoholic fatty liver disease (NAFLD) represents a growing global health concern that can lead to liver disease and cancer. It is characterized by an excessive accumulation of fat in the liver, unrelated to excessive alcohol consumption. Studies indicate that the gut microbiota-host crosstalk may play a causal role in NAFLD pathogenesis, with epigenetic modification serving as a key mechanism for regulating this interaction. In this review, we explore how the interplay between gut microbiota and the host epigenome impacts the development of NAFLD. Specifically, we discuss how gut microbiota-derived factors, such as lipopolysaccharides (LPS) and short-chain fatty acids (SCFAs), can modulate the DNA methylation and histone acetylation of genes associated with NAFLD, subsequently affecting lipid metabolism and immune homeostasis. Although the current literature suggests a link between gut microbiota and NAFLD development, our understanding of the molecular mechanisms and signaling pathways underlying this crosstalk remains limited. Therefore, more comprehensive epigenomic and multi-omic studies, including broader clinical and animal experiments, are needed to further explore the mechanisms linking the gut microbiota to NAFLD-associated genes. These studies are anticipated to improve microbial markers based on epigenetic strategies and provide novel insights into the pathogenesis of NAFLD, ultimately addressing a significant unmet clinical need.