Specific Strains of Faecalibacterium prausnitzii Ameliorate Nonalcoholic Fatty Liver Disease in Mice in Association with Gut Microbiota Regulation

Faecalibacterium prausnitzii regulates carbohydrate metabolic functions of the gut microbiome in C57BL/6 mice

The probiotic impact of microbes on host metabolism and health depends on both host genetics and bacterial genomic variation. Faecalibacterium prausnitzii is the predominant human gut commensal emerging as a next-generation probiotic. Although this bacterium exhibits substantial intraspecies diversity, it is unclear whether genetically distinct F. prausnitzii strains might lead to functional differences in the gut microbiome. Here, we isolated and characterized a novel F. prausnitzii strain (UT1) that belongs to the most prevalent but underappreciated phylogenetic clade in the global human population. Genome analysis showed that this butyrate-producing isolate carries multiple putative mobile genetic elements, a clade-specific defense system, and a range of carbohydrate catabolic enzymes. Multiomic approaches were used to profile the impact of UT1 on the gut microbiome and associated metabolic activity of C57BL/6 mice at homeostasis. Both 16S rRNA and metagenomic sequencing demonstrated that oral administration of UT1 resulted in profound microbial compositional changes including a significant enrichment of Lactobacillus, Bifidobacterium, and Turicibacter. Functional profiling of the fecal metagenomes revealed a markedly higher abundance of carbohydrate-active enzymes (CAZymes) in UT1-gavaged mice. Accordingly, UT1-conditioned microbiota possessed the elevated capability of utilizing starch in vitro and exhibited a lower availability of microbiota-accessible carbohydrates in the gut. Further analysis uncovered a functional network wherein UT1 reduced the abundance of mucin-degrading CAZymes and microbes, which correlated with a concomitant reduction of fecal mucin glycans. Collectively, our results reveal a crucial role of UT1 in facilitating the carbohydrate metabolism of the gut microbiome and expand our understanding of the genetic and phenotypic diversity of F. prausnitzii.

Aerobic exercise regulates gut microbiota profiles and metabolite in the early stage of Alzheimer's disease

Aerobic exercise (AE) has been shown to offer significant benefits for Alzheimer's disease (AD), potentially influencing the gut microbiota. However, the impact of changes in intestinal flora in early Alzheimer's disease induced by aerobic exercise on metabolic pathways and metabolites is not well understood. In this study, 3-month-old APP/PS1 and C57BL/6 mice were divided into two groups each: a control group (ADC for APP/PS1 and WTC for C57BL/6) and an aerobic exercise group (ADE for APP/PS1 and WTE for C57BL/6). The exercise groups underwent a 20-week aerobic training program on a motorized treadmill before the behavioral test (both the Morris water maze experiment (MWM) and the eight-arm maze test). Fecal samples were collected to analyze gut microbiota profiles via 16S rRNA gene sequencing. At the same time, the metabolic pathway analysis and the detection of metabolites were carried out. At the phylum level, the ADE group exhibited a significant reduced in the relative abundance of Bacteroidetes compared to the ADC group. At the genus level, both Ileibacterium and Faecalibaculum were found to be more abundant in the ADE group than in the ADC group. Additionally, PICRUSt analysis revealed that lipid metabolism and bile acid metabolism pathways were significantly enriched in the cecal microbiota of mice in the ADE group. The metabolites detected further confirmed the changes in the metabolic pathways mentioned above. Aerobic exercise may modify gut microbiota profiles and metabolites in APP/PS1 mice, thereby potentially playing a beneficial role in delaying cognitive impairment associated with early-stage Alzheimer's disease.

Effects of a paternal diet high in animal protein (casein) versus plant protein (pea protein with added methionine) on offspring metabolic and gut microbiota outcomes in rats

Evidence suggests that paternal diet can influence offspring metabolic health intergenerationally but whether dietary animal and plant proteins differ in their impact on fathers and their offspring is not known. Our objective was to examine the effects of a paternal diet high in casein versus pea protein on fathers and their offspring. Five-week-old male rats were fed: (1) control, (2) high animal protein (AP, 36.1% of energy as casein), or (3) high plant protein (PP, 36.1% of energy as pea protein with added methionine) diets for 8-11 weeks before being mated. Offspring were challenged with a high fat/sucrose diet (HFD) from 10 to 16 weeks of age. Metabolic and microbial outcomes were assessed in both generations. In fathers fed PP diet, enhanced insulin sensitivity and lower liver triglycerides were seen alongside altered hepatic microRNA expression and gut microbial profiles. Few changes were seen in their offspring. In contrast, the paternal AP diet influenced adult offspring hepatic microRNA expression and programmed a latent increase in adiposity, dysregulated satiety hormones, and modified gut microbial composition in their adult offspring that occurred following the HFD. Overall, a diet high in pea protein with added methionine demonstrated protective effects on biomarkers of metabolic health in the fathers but led to minimal effects on the offspring while a paternal diet high in casein led to evidence of an increase in characteristics of metabolic dysfunction in their adult offspring when unmasked by exposure to a HFD for 6 weeks.

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.

Interplay of Oxidative Stress, Gut Microbiota, and Nicotine in Metabolic-Associated Steatotic Liver Disease (MASLD)

Oxidative stress has been described as one of the main drivers of intracellular damage and metabolic disorders leading to metabolic syndrome, a major health problem worldwide. In particular, free radicals alter lipid metabolism and promote lipid accumulation in the liver, existing in the hepatic facet of metabolic syndrome, the metabolic dysfunction-associated steatotic liver disease (MASLD). Recent literature has highlighted how nicotine, especially if associated with a high-fat diet, exerts a negative effect on the induction and progression of MASLD by upregulating inflammation and increasing oxidative stress, abdominal fat lipolysis, and hepatic lipogenesis. Moreover, considerable evidence shows the central role of intestinal dysbiosis in the pathogenesis of MASLD and the impact of nicotine-induced oxidative stress on the gut microbiome. This results in an intricate network in which oxidative stress stands at the intersection point between gut microbiome, nicotine, and MASLD. The aim of this review is to delve into the molecular mechanisms linking tobacco smoking and MASLD, focusing on nicotine-induced microbiota modifications and their impact on MASLD development.

Phosphatidylcholine ameliorates lipid accumulation and liver injury in high-fat diet mice by modulating bile acid metabolism and gut microbiota

Phosphatidylcholine (PC) has garnered considerable attention due to its involvement in a wide array of crucial biological functions. However, there is still much to active explore regarding the precise mechanisms that underlie PC's actions in the context of high-fat diet. In this study, we found that both PC intervention and treatment significantly mitigated lipid accumulation, liver damage, and body weight gaining triggered by the high-fat diet. Untargeted and targeted metabolomic analyses uncovered substantial effects of PC on bile acid metabolism, especially led to a substantial reduction in elevated levels of free bile acids. 16S rRNA gene sequencing revealed that PC modulated the gut microbiota structures and compositions in high-fat diet mice, particularly exhibiting a positive association with Pseudoflavonifractor abundance, and a negative correlation with Olsenella, Parasutterella, and Allobaculum abundance. Our study suggested that PC held promise as a potential candidate for alleviating lipid metabolism injury, liver disease or obesity.

Distinct alterations of gut microbiota between viral- and non-viral-related hepatocellular carcinoma

Altered gut microbiota has been connected to hepatocellular carcinoma (HCC) occurrence and advancement. This study was conducted to identify a gut microbiota signature in differentiating between viral-related HCC (Viral-HCC) and non-hepatitis B-, non-hepatitis C-related HCC (NBNC-HCC). Fecal specimens were obtained from 16 healthy controls, 33 patients with viral-HCC (17 and 16 cases with hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, respectively), and 18 patients with NBNC-HCC. Compositions of fecal microbiota were assessed by 16S rRNA sequencing. Bioinformatic analysis was performed by the DADA2 pipeline in the R program. Significantly different genera from the top 50 relative abundance were used to classify between subgroups of HCC by the Random Forest algorithm. Our data demonstrated that the HCC group had a significantly decreased alpha-diversity and changed microbial composition in comparison with healthy controls. Within the top 50 relative abundance, there were 11 genera including Faecalibacterium, Agathobacter, and Coprococcus that were significantly enhanced in Viral-HCC, while 5 genera such as Bacteroides, Streptococcus, Ruminococcus gnavus group, Parabacteroides, and Erysipelatoclostridium were enhanced in NBNC-HCC. Compared to Viral-HCC, the NBNC-HCC subgroup significantly reduced various short-chain fatty acid-producing bacteria, as well as declined fecal butyrate but elevated plasma surrogate markers of microbial translocation. Based on the machine learning algorithm, a high diagnostic accuracy to classify HCC subgroups was achieved with an area under the receiver-operating characteristic (ROC) curve (AUC) of 0.94. Collectively, these data revealed that gut dysbiosis was distinct according to etiological factors of HCC, which might play an essential role in hepatocarcinogenesis. These findings underscore the possible use of a gut microbiota signature for the diagnosis and therapeutic approaches regarding different subgroups of HCC. KEY POINTS: • Gut dysbiosis is connected to hepatocarcinogenesis and can be used as a novel biomarker. • Gut microbiota composition is significantly altered in different etiological factors of HCC. • Microbiota-based signature can accurately distinguish between Viral-HCC and NBNC-HCC.

Ampelopsis grossedentata tea alleviating liver fibrosis in BDL-induced mice via gut microbiota and metabolite modulation

Liver fibrosis (LF) is a common sequela to diverse chronic liver injuries, leading to rising rates of cirrhosis and hepatocellular carcinoma (HCC). As the medicinal and edible homologous material, traditional teas have exhibited promising applications in the clinical management of liver fibrosis. Here, we generated a liver fibrosis mouse model to explore the potent therapeutic ability of Ampelopsis grossedentata (AG) tea on this condition by multi-omics analysis. The biochemistry results pointed towards mitigated increases of ALT, AST, TBIL, and ALP triggered by BDL in the AG-treated group. Examination using H&E and Sirius Red staining revealed severe liver injuries, inflammation infiltration, amplified fibrosed regions, and the creation of bile ducts, all of which were fallout from BDL. Immunohistochemistry findings also implicated a noteworthy upregulation of the HSC activation marker α-smooth muscle actin (α-SMA) and the fibrosis marker collagen I in the BDL group. However, these symptoms demonstrated a significant improvement in the group treated with 100 mg/kg AG. Findings from the Western Blot test corroborated the prominent elevation of TNF-α, col1a1, α-SMA, and TGF-β, instigated by BDL, while AG treatment meaningfully modulated these proteins. Furthermore, our study underscored the potential involvement of several microbiota, such as Ruminococcaceae UCG-014, Eubacterium Ruminantium, Ruminococcus 1, Christensenellaceae R-7, Acetatifactor, Dubosiella, Parasutterella, Faecalibaculum, and Defluviitaleaceae UCG-011, in the progression of liver fibrosis and the therapeutic efficacy of AG. This investigation shows that during the process of AG ameliorating BDL-induced liver fibrosis, bile acid derivatives such as CDCA, TCDCA, 3-DHC, UCA, DCA, among others, play significant roles. In this study, we identified that several non-bile acid metabolites, such as Deltarasin, Thr-Ile-Arg, etc., are entailed in the process of AG improving liver fibrosis.

Microbiota-derived succinic acid mediates attenuating effect of dietary tomato juice supplementation on steatohepatitis through enhancing intestinal barrier

The hepatoprotective potential of tomato juice (TJ) has been reported in chronic liver models, and its potential prebiotic properties may be key to its preventative effects. However, the mechanistic role of the gut microbiota and its derived metabolites in ameliorating nonalcoholic steatohepatitis (NASH) via TJ remains unclear. In this study, we explored how TJ regulates gut microbiota and succinic acid (SA) to restore intestinal barrier function and thus suppress NASH progression. TJ supplementation effectively reduced serum lipid concentrations, alleviated endotoxin levels, and suppressed activation of the endotoxin-TLR4-NF-κB pathway in methionine-choline-deficient (MCD) diet-induced NASH mice. TJ restored the MCD diet-induced gut microbiota dysbiosis, increased the abundance of short-chain fatty acid and SA-producing bacteria (Bifidobacterium, Ileibacterium, Odoribacter, and Parasutterella) and enhanced the expression of intestinal barrier-associated proteins (E-cadherin, Claudin-1, MUC-2, and ZO-1). The hepatoprotective and enteroprotective effects of TJ were abolished in an antibiotic-treated mouse model, underscoring the pivotal role of the gut microbiota in the beneficial effects of TJ on NASH. Fecal metabolomics demonstrated that TJ significantly upregulated the tricarboxylic acid cycle, pyruvate metabolism, and butanoate metabolism pathways, increasing levels of butyric acid (BA) and SA-metabolites associated with reduced hepatic steatosis and intestinal damage. We further found that the physiological concentration of SA, rather than BA, could reduce pro-inflammatory cytokines (TNF-α and IL-6) levels and enhance mucin proteins and tight junction markers in the LPS-induced colon cell line LS174T. This study uncovers new mechanisms by which TJ prevents NASH, highlighting the potential of TJ and SA as effective dietary supplements for patients with chronic liver diseases.

Vitamin K2 alleviates dextran sulfate sodium-induced colitis via inflammatory responses, gut barrier integrity, and the gut microbiota in mice

Vitamin K2 (VK2) has been shown to have potential benefits in improving intestinal integrity, but its potential and mechanisms for alleviating intestinal inflammation are still unclear. The present results showed that VK2 supplementation significantly alleviated the symptoms of colitis and maintained the intestinal barrier integrity. In addition, VK2 significantly down-regulated the mRNA expression levels of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α, while up-regulated the mRNA expression level of anti-inflammatory cytokines such as IL-10. Moreover, VK2 significantly alleviated DSS-induced intestinal epithelial barrier dysfunction by maintaining the tight junction function. Furthermore, VK2 also regulated DSS-induced gut microbiota dysbiosis by reshaping the structure of gut microbiota, such as increasing the relative abundance of Firmicutes, Euryarchaeota, Prevotellaceae, and Prevotella and reducing the relative abundance of Proteobacteria, Rikenellaceae, Enterobacteriaceae, Acetatifactor, and Alistioes. In conclusion, these results indicated that VK2 effectively alleviates DSS-induced colitis in mice by modulating the gut microbiota.

Combination of Metabolomics, Lipidomics, and Molecular Biology for the Investigation of the Metabolic Disturbance of Short-Term Administration of Emodin

Emodin, a natural anthraquinone derivative, is an active ingredient in many Chinese traditional herbs. Interestingly, although it is generally considered to possess hepatoprotective activity, some studies have also reported that it has a certain degree of hepatotoxicity. Additionally, the underlying metabolic regulation of emodin remains uncertain. Therefore, we conducted a nontargeted metabolomic study based on UHPLC/Q-Orbitrap-MS and NMR. Data are available via ProteomeXchange with the identifier PXD055000. The results indicated a close association between the short-term administration of emodin and lipid metabolism. Moreover, a lipidomics investigation utilizing QTRAP 6500+ UHPLC-MS/MS was conducted, with a focus on determining the position of C═C double bonds in unsaturated lipids based on Paternò-Büchi (PB) reaction to discover the metabolic disturbance more precisely. Specifically, lipidomics revealed elevated levels of free fatty acids (FFA) alongside notable reductions in sphingomyelin (SM) and triacylglycerol (TAG) levels. Furthermore, the combination of PB reaction and molecular biology results indicated that short-term administration of emodin may lead to the accumulation of n-6 polyunsaturated fatty acids by up-regulating the expression of FASN, stearyl CoA desaturase 1 (SCD1), and cytosolic phospholipase A 2 (cPLA2). Simultaneously, up-regulation of cyclooxygenase-2 (Cox-2) expression was observed, potentially fostering the production of prostaglandin E2 (PGE2) and subsequent inflammation.

Polysaccharide-mediated modulation of gut microbiota in the treatment of liver diseases: Promising approach with significant challenges

Liver disease represents a significant global health burden, with an increasing prevalence and a lack of efficient treatment options. The microbiota-gut-liver axis involves bidirectional communication between liver function and intestinal microorganisms. A balanced gut flora protects intestinal homeostasis, while imbalances contribute to the development of liver diseases. Distinct alterations in the structure of gut flora during illness are crucial in the management of various liver diseases. Polysaccharides derived from herbal products, fungi, and other sources have been identified to possess diverse biological activities and are well-tolerated in the treatment of liver diseases. This review provides updates on the therapeutic effects of polysaccharides on liver diseases, including fatty liver diseases, acute liver injuries and liver cancers. It also summarizes advancements in understanding the mechanisms involved, particularly from the perspective of gut microbiota and metabolites, by highlighting the changes in the composition of potentially beneficial and harmful bacteria and their correlation with the therapeutic effects of polysaccharides. Additionally, by exploring the structure-activity relationship, our review provides valuable insights for the structural modification of polysaccharides and expanding their applications. In conclusion, this review offers theoretical support and novel perspectives on developing polysaccharides-based therapeutic approaches for the treatment of liver diseases.

Gan-jiang-ling-zhu decoction improves steatohepatitis by regulating gut microbiota-mediated 12-tridecenoic acid inhibition

Introduction: Gan-jiang-ling-zhu (GJLZ) decoction is a classical traditional Chinese medicine prescription. Through invigorating yang, activating qi and dissipating dampness, GJLZ decoction is widely applied for the treatment of chronic digestive disease, including nonalcoholic fatty liver disease. However, efficacy and mechanism of GJLZ decoction behind nonalcoholic steatohepatitis (NASH) treatment remains unelucidated. Methods: NASH was induced in mice, followed by treatment with GJLZ decoction. Various methods including hematoxylin-eosin, oil red O staining, and triglyceride analysis were employed to evaluate the treatment effects of GJLZ decoction on NASH. Gut microbiota, metabolomics, cell viability assays, immunofluorescence and Western blotting were performed to unveil the mechanism behind GJLZ decoction. Results: GJLZ decoction treatment significantly improved hepatic steatosis in mice with NASH. It led to remodeling of gut flora and metabolite structures, including the 12-tridecenoic acid level. 12-Tridecenoic acid aggravated hepatic steatosis by promoting acetyl-coenzyme A carboxylase alpha (ACC) expression and inhibiting carnitine palmitoyltransferase 1A (CPT1A) expression. GJLZ decoction treatment reduced the 12-tridecenoic acid level, inhibited ACC activity and promoted CPT1A expression. Conclusion: Our results demonstrated that 12-tridecenoic acid aggravated hepatic steatosis by affecting the ACC-CPT1A axis and GJLZ decoction treatment effectively reduced the 12-tridecenoic acid level and improved steatosis.

Gut microbiota dysbiosis is associated with altered tryptophan metabolism and dysregulated inflammatory response in COVID-19

The clinical course of COVID-19 is variable and often unpredictable. To test the hypothesis that disease progression and inflammatory responses associate with alterations in the microbiome and metabolome, we analyzed metagenome, metabolome, cytokine, and transcriptome profiles of repeated samples from hospitalized COVID-19 patients and uninfected controls, and leveraged clinical information and post-hoc confounder analysis. Severe COVID-19 was associated with a depletion of beneficial intestinal microbes, whereas oropharyngeal microbiota disturbance was mainly linked to antibiotic use. COVID-19 severity was also associated with enhanced plasma concentrations of kynurenine and reduced levels of several other tryptophan metabolites, lysophosphatidylcholines, and secondary bile acids. Moreover, reduced concentrations of various tryptophan metabolites were associated with depletion of Faecalibacterium, and tryptophan decrease and kynurenine increase were linked to enhanced production of inflammatory cytokines. Collectively, our study identifies correlated microbiome and metabolome alterations as a potential contributor to inflammatory dysregulation in severe COVID-19.

NAFLD/MASLD and the Gut-Liver Axis: From Pathogenesis to Treatment Options

Nonalcoholic fatty liver disease (NAFLD) poses an emerging threat topublic health. Nonalcoholic steatohepatitis (NASH) is reported to be the most rapidly rising cause of hepatocellular carcinoma in the western world. Recently, a new term has been proposed: metabolic dysfunction-associated steatotic liver disease (MASLD). The introduction of this new terminology has sparked a debate about the interchangeability of these terms. The pathogenesis of NAFLD/MASLD is thought to be multifactorial, involving both genetic and environmental factors. Among these factors, alterations in gut microbiota and gut dysbiosis have recently garnered significant attention. In this context, this review will further discuss the gut-liver axis, which refers to the bidirectional interaction between the human gut microbiota and the liver. Additionally, the therapeutic potential of probiotics, particularly next-generation probiotics and genetically engineered bacteria, will be explored. Moreover, the role of prebiotics, synbiotics, postbiotics, and phages as well as fecal microbiota transplantation will be analyzed. Particularly for lean patients with NAFLD/MASLD, who have limited treatment options, approaches that modify the diversity and composition of the gut microbiota may hold promise. However, due to ongoing safety concerns with approaches that modulate gut microbiota, further large-scale studies are necessary to better assess their efficacy and safety in treating NAFLD/MASLD.

Shenling Baizhu San ameliorates non-alcoholic fatty liver disease in mice by modulating gut microbiota and metabolites

Purpose: The prevalence of non-alcoholic fatty liver disease (NAFLD) and its related mortality is increasing at an unprecedented rate. Traditional Chinese medicine (TCM) has been shown to offer potential for early prevention and treatment of NAFLD. The new mechanism of "Shenling Baizhu San" (SLBZS) is examined in this study for the prevention and treatment of NAFLD at the preclinical level. Methods: Male C57BL/6J mice were randomly divided into three groups: normal diet (ND), western diet + CCl4 injection (WDC), and SLBZS intervention (WDC + SLBZS). Body weights, energy intake, liver enzymes, pro-inflammatory factors, and steatosis were recorded in detail. Meanwhile, TPH1, 5-HT, HTR2A, and HTR2B were tested using qRT-PCR or ELISA. Dynamic changes in the gut microbiota and metabolites were further detected through the 16S rRNA gene and untargeted metabolomics. Results: SLBZS intervention for 6 weeks could reduce the serum and liver lipid profiles, glucose, and pro-inflammatory factors while improving insulin resistance and liver function indexes in the mice, thus alleviating NAFLD in mice. More importantly, significant changes were found in the intestinal TPH-1, 5-HT, liver 5-HT, and related receptors HTR2A and HTR2B. The 16S rRNA gene analysis suggested that SLBZS was able to modulate the disturbance of gut microbiota, remarkably increasing the relative abundance of probiotics (Bifidobacterium and Parvibacter) and inhibiting the growth of pro-inflammatory bacteria (Erysipelatoclostridium and Lachnoclostridium) in mice with NAFLD. Combined with metabolomics in positive- and negative-ion-mode analyses, approximately 50 common differential metabolites were selected via non-targeted metabolomics detection, which indicated that the targeting effect of SLBZS included lipid metabolites, bile acids (BAs), amino acids (AAs), and tryptophan metabolites. In particular, the lipid metabolites 15-OxEDE, vitamin D3, desoxycortone, and oleoyl ethanol amide were restored by SLBZS. Conclusion: Integrating the above results of multiple omics suggests that SLBZS ameliorates NAFLD via specific gut microbiota, gut-derived 5-HT, and related metabolites to decrease fat accumulation in the liver and inflammatory responses.

NAFLD in the 21st Century: Current Knowledge Regarding Its Pathogenesis, Diagnosis and Therapeutics

Non-alcoholic fatty liver disease (NAFLD) is a major public health issue worldwide. It is the most common liver disease in Western countries, andits global prevalence is estimated to be up to 35%. However, its diagnosis may be elusive, because liver biopsy is relatively rarely performed and usually only in advanced stages of the disease. Therefore, several non-invasive scores may be applied to more easily diagnose and monitor NAFLD. In this review, we discuss the various biomarkers and imaging scores that could be useful in diagnosing and managing NAFLD. Despite the fact that general measures, such as abstinence from alcohol and modulation of other cardiovascular disease risk factors, should be applied, the mainstay of prevention and management is weight loss. Bariatric surgery may be suggested as a means to confront NAFLD. In addition, pharmacological treatment with GLP-1 analogues or the GIP agonist tirzepatide may be advisable. In this review, we focus on the utility of GLP-1 analogues and GIP agonists in lowering body weight, their pharmaceutical potential, and their safety profile, as already evidenced inanimal and human studies. We also elaborate on other options, such as the use of vitamin E, probiotics, especially next-generation probiotics, and prebiotics in this context. Finally, we explore future perspectives regarding the administration of GLP-1 analogues, GIP agonists, and probiotics/prebiotics as a means to prevent and combat NAFLD. The newest drugs pegozafermin and resmetiron, which seem to be very promising, arealso discussed.

The potential of short-chain fatty acid epigenetic regulation in chronic low-grade inflammation and obesity

Obesity and chronic low-grade inflammation, often occurring together, significantly contribute to severe metabolic and inflammatory conditions like type 2 diabetes (T2D), cardiovascular disease (CVD), and cancer. A key player is elevated levels of gut dysbiosis-associated lipopolysaccharide (LPS), which disrupts metabolic and immune signaling leading to metabolic endotoxemia, while short-chain fatty acids (SCFAs) beneficially regulate these processes during homeostasis. SCFAs not only safeguard the gut barrier but also exert metabolic and immunomodulatory effects via G protein-coupled receptor binding and epigenetic regulation. SCFAs are emerging as potential agents to counteract dysbiosis-induced epigenetic changes, specifically targeting metabolic and inflammatory genes through DNA methylation, histone acetylation, microRNAs (miRNAs), and long non-coding RNAs (lncRNAs). To assess whether SCFAs can effectively interrupt the detrimental cascade of obesity and inflammation, this review aims to provide a comprehensive overview of the current evidence for their clinical application. The review emphasizes factors influencing SCFA production, the intricate connections between metabolism, the immune system, and the gut microbiome, and the epigenetic mechanisms regulated by SCFAs that impact metabolism and the immune system.

Influence of microbiota-associated metabolic reprogramming on clinical outcome in patients with melanoma from the randomized adjuvant dendritic cell-based MIND-DC trial

Tumor immunosurveillance plays a major role in melanoma, prompting the development of immunotherapy strategies. The gut microbiota composition, influencing peripheral and tumoral immune tonus, earned its credentials among predictors of survival in melanoma. The MIND-DC phase III trial (NCT02993315) randomized (2:1 ratio) 148 patients with stage IIIB/C melanoma to adjuvant treatment with autologous natural dendritic cell (nDC) or placebo (PL). Overall, 144 patients collected serum and stool samples before and after 2 bimonthly injections to perform metabolomics (MB) and metagenomics (MG) as prespecified exploratory analysis. Clinical outcomes are reported separately. Here we show that different microbes were associated with prognosis, with the health-related Faecalibacterium prausnitzii standing out as the main beneficial taxon for no recurrence at 2 years (p = 0.008 at baseline, nDC arm). Therapy coincided with major MB perturbations (acylcarnitines, carboxylic and fatty acids). Despite randomization, nDC arm exhibited MG and MB bias at baseline: relative under-representation of F. prausnitzii, and perturbations of primary biliary acids (BA). F. prausnitzii anticorrelated with BA, medium- and long-chain acylcarnitines. Combined, these MG and MB biomarkers markedly determined prognosis. Altogether, the host-microbial interaction may play a role in localized melanoma. We value systematic MG and MB profiling in randomized trials to avoid baseline differences attributed to host-microbe interactions.

N-nitrosamines induced gender-dimorphic effects on infant rats at environmental levels

The safety of drinking water has always been a concern for people all over the world. N-nitrosamines (NAs), a kind of nitrogenous disinfection by-products (N-DBPs), are generally detected as a mixture in drinking water at home and abroad. Studies have shown that individual NAs posed strong carcinogenicity at high concentrations. However, health risks of NAs at environmental levels (concentrations in drinking water) are still unclear. Therefore, the potential health risks of environmentally relevant NAs exposure in drinking water needs to be conducted. In this study, blood biochemical analysis and metabolomics based on nuclear magnetic resonance (NMR) were performed to comprehensively investigate NAs induced metabolic disturbance in infant rats at environmental levels. Results of blood biochemical indices analysis indicated that AST in the serum of male rats in NAs-treated group exhibited a significant gender-specific difference. Multivariate statistics showed that two and eight significantly disturbed metabolic pathways were identified in the serum samples of NAs-treated male and female rats, respectively. In the urine samples of NAs-treated female rats, glycine, serine, and threonine metabolism pathway was significantly disturbed; while three significantly disturbed metabolic pathways were found in the urine of NAs-treated male rats. Finally, results of spearman correlation coefficients suggested that the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota (data derived from our published paper). Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management. ENVIRONMENTAL IMPLICATION: N-nitrosamines (NAs) are a kind of nitrogenous disinfection by-products (N-DBPs) generated during drinking water disinfection processes. Herein, health risks of NAs at environmental levels (concentrations in drinking water) are investigated using blood biochemical analysis and nuclear magnetic resonance (NMR)-based metabolomics. Results confirmed NAs induced gender-specific on the metabolism in rat and the disturbances of metabolism profile in serum and urine were correlated with changes in the gut microbiota. Data presented here aimed to generate new health risk data of NAs mixture exposure at environmental levels and provide theoretical support for drinking water safety management.

Bacteroides thetaiotaomicron ameliorates mouse hepatic steatosis through regulating gut microbial composition, gut-liver folate and unsaturated fatty acids metabolism

Gut microbiota plays an essential role in the progression of nonalcoholic fatty liver disease (NAFLD), making the gut-liver axis a potential therapeutic strategy. Bacteroides genus, the enriched gut symbionts, has shown promise in treating fatty liver. However, further investigation is needed to identify specific beneficial Bacteroides strains for metabolic disorders in NAFLD and elucidate their underlying mechanisms. In this study, we observed a positive correlation between the abundance of Bacteroides thetaiotaomicron (B. theta) and the alleviation of metabolic syndrome in the early and end stages of NAFLD. Administration of B. theta to HFD-fed mice for 12 weeks reduced body weight and fat accumulation, decreased hyperlipidemia and insulin resistance, and prevented hepatic steatohepatitis and liver injury. Notably, B. theta did not affect these indicators in low-fat diet (LFD)-fed mice and exhibited good safety. Mechanistically, B. theta regulated gut microbial composition, characterized by a decreased Firmicutes/Bacteroidetes ratio in HFD-Fed mice. It also increased gut-liver folate levels and hepatic metabolites, alleviating metabolic dysfunction. Additionally, treatment with B. theta increased the proportion of polyunsaturated fatty acid in the mouse liver, offering a widely reported benefit for NAFLD improvement. In conclusion, this study provides evidence that B. theta ameliorates NAFLD by regulating gut microbial composition, enhancing gut-liver folate and unsaturated fatty acid metabolism, highlighting the therapeutic role of B. theta as a potential probiotic for NAFLD.

Frontiers and hotspots of adipose tissue and NAFLD: a bibliometric analysis from 2002 to 2022

Background: The annual incidence of non-alcoholic fatty liver disease (NAFLD) continues to rise steadily. In recent years, adipose tissue (AT) has gained recognition as a pivotal contributor to the pathogenesis of NAFLD. Employing bibliometric analysis, we examined literature concerning AT and NAFLD. Methods: Relevant literature on AT in NAFLD from 1980 to 2022 was extracted from the Web of Science Core Collection. These records were visualized using CiteSpace and VOSviewer regarding publications, countries/regions, institutions, authors, journals, references, and keywords. Results: Since 2002, a total of 3,330 papers have been included, exhibiting an annual surge in publications. Notably, the quality of publications is superior in the USA and Europe. Kenneth Cusi stands out as the author with the highest number of publications and H-index. Hepatology is the journal boasting the highest citation and H-index. The University of California System holds the highest centrality among institutions. References specifically delve into physiological processes associated with AT in NAFLD. Currently, lipid metabolism and inflammation constitute the principal research mechanisms in the AT-based regulation of NAFLD, with pertinent keywords including microRNA, T cell, hypoxia, sarcopenia, hepatokine, gut microbiota, and autophagy. The Mediterranean diet is among the most widely recommended dietary approaches for potential NAFLD treatment. Conclusion: This paper represents the inaugural bibliometric study on the effects of AT on NAFLD, offering valuable insights and directions for future research.

The Role of Bifidobacterium in Liver Diseases: A Systematic Review of Next-Generation Sequencing Studies

The physiopathology of liver diseases is complex and can be caused by various factors. Bifidobacterium is a bacterial genus commonly found in the human gut microbiome and has been shown to influence the development of different stages of liver diseases significantly. This study investigated the relationship between the Bifidobacterium genus and liver injury. In this work, we performed a systematic review in major databases using the key terms "Bifidobacterium", "ALD", "NAFLD", "NASH", "cirrhosis", and "HCC" to achieve our purpose. In total, 31 articles were selected for analysis. In particular, we focused on studies that used next-generation sequencing (NGS) technologies. The studies focused on assessing Bifidobacterium levels in the diseases and interventional aimed at examining the therapeutic potential of Bifidobacterium in the mentioned conditions. Overall, the abundance of Bifidobacterium was reduced in hepatic pathologies. Low levels of Bifidobacterium were associated with harmful biochemical and physiological parameters, as well as an adverse clinical outcome. However, interventional studies using different drugs and treatments were able to increase the abundance of the genus and improve clinical outcomes. These results strongly support the hypothesis that changes in the abundance of Bifidobacterium significantly influence both the pathophysiology of hepatic diseases and the related clinical outcomes. In addition, our critical assessment of the NGS methods and related statistical analyses employed in each study highlights concerns with the methods used to define the differential abundance of Bifidobacterium, including potential biases and the omission of relevant information.

Frequentmers - a novel way to look at metagenomic next generation sequencing data and an application in detecting liver cirrhosis

Early detection of human disease is associated with improved clinical outcomes. However, many diseases are often detected at an advanced, symptomatic stage where patients are past efficacious treatment periods and can result in less favorable outcomes. Therefore, methods that can accurately detect human disease at a presymptomatic stage are urgently needed. Here, we introduce "frequentmers"; short sequences that are specific and recurrently observed in either patient or healthy control samples, but not in both. We showcase the utility of frequentmers for the detection of liver cirrhosis using metagenomic Next Generation Sequencing data from stool samples of patients and controls. We develop classification models for the detection of liver cirrhosis and achieve an AUC score of 0.91 using ten-fold cross-validation. A small subset of 200 frequentmers can achieve comparable results in detecting liver cirrhosis. Finally, we identify the microbial organisms in liver cirrhosis samples, which are associated with the most predictive frequentmer biomarkers.

Non-alcoholic fatty liver disease and gut microbial dysbiosis- underlying mechanisms and gut microbiota mediated treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is by far the most prevalent form of liver disease worldwide. It's also the leading cause of liver-related hospitalizations and deaths. Furthermore, there is a link between obesity and NAFLD risk. A projected 25% of the world's population grieves from NAFLD, making it the most common chronic liver disorder. Several factors, such as obesity, oxidative stress, and insulin resistance, typically accompany NAFLD. Weight loss, lipid-lowering agents, thiazolidinediones, and metformin help prominently control NAFLD. Interestingly, pre-clinical studies demonstrate gut microbiota's potential causal role in NAFLD. Increased intestinal permeability and unhindered transport of microbial metabolites into the liver are the major disruptions due to gut microbiome dysbiosis, contributing to the development of NAFLD by dysregulating the gut-liver axis. Hence, altering the pathogenic bacterial population using probiotics, prebiotics, synbiotics, and fecal microbiota transplantation (FMT) could benefit patients with NAFLD. Therefore, it is crucial to acknowledge the importance of microbiota-mediated therapeutic approaches for NAFLD and comprehend the underlying mechanisms that establish a connection between NAFLD and gut microbiota. This review provides a comprehensive overview of the affiliation between dysbiosis of gut microbiota and the progress of NAFLD, as well as the potential benefits of prebiotic, probiotic, synbiotic supplementation, and FMT in obese individuals with NAFLD.

Gut microbiota, immunity, and bile acid metabolism: decoding metabolic disease interactions

In recent decades, the global prevalence of metabolic syndrome has surged, posing a significant public health challenge. Metabolic disorders, encompassing diabetes, obesity, nonalcoholic fatty liver disease, and polycystic ovarian syndrome, have been linked to alterations in the gut microbiota. Nonetheless, the connection between gut microbiota and host metabolic diseases warrants further investigation. In this review, we delve into the associations between various metabolic disorders and the gut microbiota, focusing on immune responses and bile acid (BA) metabolism. Notably, T helper cells, innate lymphoid cells, macrophages, and dendritic cells have been shown to modulate host metabolism through interactions with intestinal microorganisms and the release of cytokines. Furthermore, secondary BA metabolites, derived from the microbiota, are involved in the pathogenesis of metabolic diseases via the farnesoid X receptor and Takeda G protein-coupled receptor 5. By covering both aspects of this immune system-microorganism axis, we present a comprehensive overview of the roles played by the gut microbiota, microbiota-derived BA metabolites, and immune responses in metabolic diseases, as well as the interplay between these systems.

Roles of gut microbes in metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is the most common chronic liver disease. Gut dysbiosis is considered a significant contributing factor in disease development. Increased intestinal permeability can be induced by gut dysbiosis, followed by the entry of lipopolysaccharide into circulation to reach peripheral tissue and result in chronic inflammation. We reviewed how microbial metabolites push host physiology toward MAFLD, including short-chain fatty acids (SCFAs), bile acids, and tryptophan metabolites. The effects of SCFAs are generally reported as anti-inflammatory and can improve intestinal barrier function and restore gut microbiota. Gut microbes can influence intestinal barrier function through SCFAs produced by fermentative bacteria, especially butyrate and propionate producers. This is achieved through the activation of free fatty acid sensing receptors. Bile is directly involved in lipid absorption. Gut microbes can alter bile acid composition by bile salt hydrolase-producing bacteria and bacterial hydroxysteroid dehydrogenase-producing bacteria. These bile acids can affect host physiology by activating farnesoid X receptor Takeda G protein-coupled receptor 5. Gut microbes can also induce MAFLD-associated symptoms by producing tryptophan metabolites kynurenine, serotonin, and indole-3-propionate. A summary of bacterial genera involved in SCFAs production, bile acid transformation, and tryptophan metabolism is provided. Many bacteria have demonstrated efficacy in alleviating MAFLD in animal models and are potential therapeutic candidates for MAFLD.

Protein kinases: The key contributors in pathogenesis and treatment of nonalcoholic fatty liver disease-derived hepatocellular carcinoma

Protein kinases (PKs), one of the largest protein families, can be further divided into different groups based on their substrate or structure and function. PKs are important signaling messengers in numerous life activities, including cell metabolism, proliferation, division, differentiation, senescence, death, and disease. Among PK-related diseases, nonalcoholic fatty liver disease (NAFLD) has been recognized as a major contributor to hepatocellular carcinoma (HCC) and liver transplantation. Unfortunately, NAFLD-derived HCC (NAFLD-HCC) has poor prognosis because it is typically accompanied by older age, multiple metabolic syndromes, obstacles in early-stage diagnosis, and limited licensed drugs for treatment. Accumulating evidence suggests that PKs are implicated in the pathogenic process of NAFLD-HCC, via aberrant metabolism, hypoxia, autophagy, hypoxia, gut microbiota dysbiosis, and/or immune cell rearrangement. The present review aims to summarize the latest research advances and emphasize the feasibility and effectiveness of therapeutic strategies that regulate the expression and activities of PKs. This might yield clinically significant effects and lead to the design of novel PK-targeting therapies. Furthermore, we discuss emerging PK-based strategies for the treatment of other malignant diseases similar to NAFLD-HCC.

Pharmaceutical efficacy of novel human-origin Faecalibacterium prausnitzii strains on high-fat-diet-induced obesity and associated metabolic disorders in mice

Introduction

Obesity and related metabolic issues are a growing global health concern. Recently, the discovery of new probiotics with anti-obesity properties has gained interest.

Methods

In this study, four Faecalibacte-rium prausnitzii strains were isolated from healthy human feces and evaluated on a high-fat diet-induced mouse model for 12 weeks.

Results

The F. prausnitzii strains reduced body weight gain, liver and fat weights, and calorie intake while improving lipid and glucose metabolism in the liver and adipose tissue, as evidenced by regulating lipid metabolism-associated gene expression, including ACC1, FAS, SREBP1c, leptin, and adiponectin. Moreover, the F. prausnitzii strains inhibited low-grade inflammation, restored gut integrity, and ameliorated hepatic function and insulin resistance. Interestingly, the F. prausnitzii strains modulated gut and neural hormone secretion and reduced appetite by affecting the gut-brain axis. Supplementation with F. prausnitzii strains noticeably changed the gut microbiota composition.

Discussion

In summary, the novel isolated F. prausnitzii strains have therapeutic effects on obesity and associated metabolic disorders through modulation of the gut-brain axis. Additionally, the effectiveness of different strains might not be achieved through identical mechanisms. Therefore, the present findings provide a reliable clue for developing novel therapeutic probiotics against obesity and associated metabolic disorders.

Strains of Faecalibacterium prausnitzii and its extracts reduce blood glucose levels, percent HbA1c, and improve glucose tolerance without causing hypoglycemic side effects in diabetic and prediabetic mice

INTRODUCTION

The commensal bacterium Faecalibacterium prausnitzii is a prominent member of the microbiome of animals and humans, and it plays an important role in several physiological processes. Numerous studies have correlated the reduction of F. prausnitzii abundance with many disease states, including irritable bowel syndrome, Crohn's disease, obesity, asthma, major depressive disorder, and metabolic diseases in humans. Studies have also correlated F. prausnitzii with diseases in humans involved in altered glucose metabolism, including diabetes.

RESEARCH DESIGN AND METHODS

The aim of this study was to investigate the effects of compositions derived from three strains of F. prausnitzii (coined FPZ) on glucose metabolism in diet-induced obese male C57BL/6J prediabetic and type 2 diabetic mice. The primary endpoints of these studies were measuring changes in fasting blood glucose, glucose tolerance (as measured by a glucose tolerance test), and percent hemoglobin A1c (HbA1c) with longer term treatment. Two placebo-controlled trials were carried out using both live cell FPZ and killed cell FPZ and extracts. Two additional placebo-controlled trials were carried out in non-diabetic mice and mice that previously had type 2 diabetes (T2D).

RESULTS

Both trials in prediabetic and diabetic mice revealed that peroral administration of live FPZ or extracts from FPZ lowered fasting blood glucose levels and improved glucose tolerance compared with control mice. A trial administering longer FPZ treatment also resulted in lowered percent HbA1c compared with control mice. Additionally, trials in non-diabetic mice treated with FPZ demonstrated that FPZ treatment does not lead to hypoglycemia.

CONCLUSIONS

The trial results have shown that treatment with different formulations of FPZ result in lower blood glucose levels, lower percent HbA1c, and improved glucose response in mice compared with control prediabetic/diabetic mice. FPZ is a promising candidate as an orally administered probiotic or postbiotic to manage and improve pre-diabetes and T2D.

SIRT2 Deficiency Aggravates Diet-Induced Nonalcoholic Fatty Liver Disease through Modulating Gut Microbiota and Metabolites

Non-alcoholic fatty liver disease (NAFLD), characterized by excessive lipid accumulation in hepatocytes, is an increasing global healthcare burden. Sirtuin 2 (SIRT2) functions as a preventive molecule for NAFLD with incompletely clarified regulatory mechanisms. Metabolic changes and gut microbiota imbalance are critical to the pathogenesis of NAFLD. However, their association with SIRT2 in NAFLD progression is still unknown. Here, we report that SIRT2 knockout (KO) mice are susceptible to HFCS (high-fat/high-cholesterol/high-sucrose)-induced obesity and hepatic steatosis accompanied with an aggravated metabolic profile, which indicates SIRT2 deficiency promotes NAFLD-NASH (nonalcoholic steatohepatitis) progression. Under palmitic acid (PA), cholesterol (CHO), and high glucose (Glu) conditions, SIRT2 deficiency promotes lipid deposition and inflammation in cultured cells. Mechanically, SIRT2 deficiency induces serum metabolites alteration including upregulation of L-proline and downregulation of phosphatidylcholines (PC), lysophosphatidylcholine (LPC), and epinephrine. Furthermore, SIRT2 deficiency promotes gut microbiota dysbiosis. The microbiota composition clustered distinctly in SIRT2 KO mice with decreased Bacteroides and Eubacterium, and increased Acetatifactor. In clinical patients, SIRT2 is downregulated in the NALFD patients compared with healthy controls, and is associated with exacerbated progression of normal liver status to NAFLD to NASH in clinical patients. In conclusion, SIRT2 deficiency accelerates HFCS-induced NAFLD-NASH progression by inducing alteration of gut microbiota and changes of metabolites.

Supplementation of Lactobacillus plantarum ATCC14917 mitigates non-alcoholic fatty liver disease in high-fat-diet-fed rats

Atherosclerosis and non-alcoholic fatty liver disease (NAFLD) have been increasing at an alarming rate worldwide. Many clinical studies have underlined the link between NAFLD and atherosclerosis. Our previous experiments have discovered that Lactobacillus (L.) plantarum ATCC14917 supplementation could decrease the progression of atherosclerotic lesion formation. In this study, we aimed to investigate the role of supplementation of L. plantarum ATCC14917 mitigates liver injury in rats fed with a high-fat diet (HFD, 45% kcal from fat). A total of 32 rats were randomly divided into four groups, including two intervention groups, who fed with HFD and administering either 1 × 10⁷ or 1 × 10⁹ colony forming units (CFU) of L. plantarum ATCC14917, the normal control group, and the HFD control group. The results showed that supplementation with low-dose and high-dose of L. plantarum ATCC14917 for 8 weeks could alleviate the body weight gain (p < 0.05), hepatic steatosis, and serum lipid metabolism (p < 0.05) in HFD-fed rats. Moreover, supplementation of L. plantarum ATCC 14917 decreased total cholesterol (TC), triglyceride (TG), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels (p < 0.05) in serum, and improved HFD-associated inflammation (p < 0.05). Furthermore, cecal contents were analyzed by high-throughput 16S ribosomal RNA sequencing. The results indicated that supplementation of L. plantarum ATCC 14917 could ameliorate HFD-induced gut dysbiosis. In summary, our findings suggest that supplementation of L. plantarum ATCC 14917 could mitigate NAFLD in rats, suggesting it may be considered as a probiotic agent for preventing HFD-induced obesity.

The Influence of Gut Microbiota on Oxidative Stress and the Immune System

The human gastrointestinal tract is home to a complex microbial community that plays an important role in the general well-being of the entire organism. The gut microbiota generates a variety of metabolites and thereby regulates many biological processes, such as the regulation of the immune system. In the gut, bacteria are in direct contact with the host. The major challenge here is to prevent unwanted inflammatory reactions on one hand and on the other hand to ensure that the immune system can be activated when pathogens invade. Here the REDOX equilibrium is of utmost importance. This REDOX equilibrium is controlled by the microbiota either directly or indirectly via bacterial-derived metabolites. A balanced microbiome sorts for a stable REDOX balance, whereas dysbiosis destabilizes this equilibrium. An imbalanced REDOX status directly affects the immune system by disrupting intracellular signaling and promoting inflammatory responses. Here we (i) focus on the most common reactive oxygen species (ROS) and (ii) define the transition from a balanced REDOX state to oxidative stress. Further, we (iii) describe the role of ROS in regulating the immune system and inflammatory responses. Thereafter, we (iv) examine the influence of microbiota on REDOX homeostasis and how shifts in pro- and anti-oxidative cellular conditions can suppress or promote immune responses or inflammation.

Probiotics as Potential Therapy in the Management of Non-Alcoholic Fatty Liver Disease (NAFLD)

Background: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, the prevalence of which has increased over the years. The management of this pathology is not clear, and a specific pharmacological drug that can treat NAFLD is not available. In this sense, efforts are focused on the potential use of compounds with a natural origin that can contribute to reversing hepatic steatosis. Supplementation with probiotics, live microorganisms, is a potential strategy for the management of NAFLD. Methods: In the present review, the available information on the potential therapeutic effects of probiotics in NAFLD, mainly in animal models and in some clinical trials, is summarized. Results: Studies carried out using animal models of NAFLD induced by a high-fat diet have shown the beneficial effects of probiotic supplementation in reducing liver steatosis and normalizing the blood lipid profile and liver enzyme activities. In addition, a decrease in lipogenesis and an increase in lipolysis have been observed, together with a reduction in the pro-oxidative and pro-inflammatory state and a normalization of intestinal dysbiosis. Clinical trials have reported a decrease in the serum transaminases and an improved lipid profile, as well as a reduction in inflammatory markers. Conclusions: In conclusion, probiotic supplementation can be used as a potential therapy for the management of NAFLD.

The Role of Next-Generation Probiotics in Obesity and Obesity-Associated Disorders: Current Knowledge and Future Perspectives

Obesity and obesity-associated disorders pose a major public health issue worldwide. Apart from conventional weight loss drugs, next-generation probiotics (NGPs) seem to be very promising as potential preventive and therapeutic agents against obesity. Candidate NGPs such as Akkermansia muciniphila, Faecalibacterium prausnitzii, Anaerobutyricum hallii, Bacteroides uniformis, Bacteroides coprocola, Parabacteroides distasonis, Parabacteroides goldsteinii, Hafnia alvei, Odoribacter laneus and Christensenella minuta have shown promise in preclinical models of obesity and obesity-associated disorders. Proposed mechanisms include the modulation of gut flora and amelioration of intestinal dysbiosis, improvement of intestinal barrier function, reduction in chronic low-grade inflammation and modulation of gut peptide secretion. Akkermansia muciniphila and Hafnia alvei have already been administered in overweight/obese patients with encouraging results. However, safety issues and strict regulations should be constantly implemented and updated. In this review, we aim to explore (1) current knowledge regarding NGPs; (2) their utility in obesity and obesity-associated disorders; (3) their safety profile; and (4) their therapeutic potential in individuals with overweight/obesity. More large-scale, multicentric and longitudinal studies are mandatory to explore their preventive and therapeutic potential against obesity and its related disorders.

Faecalibacterium prausnitzii prevents hepatic damage in a mouse model of NASH induced by a high-fructose high-fat diet

Introduction

Nonalcoholic steatohepatitis (NASH) is an advanced nonalcoholic fatty liver disease characterized by chronic inflammation and fibrosis. A dysbiosis of the gut microbiota has been associated with the pathophysiology of NASH, and probiotics have proven helpful in its treatment and prevention. Although both traditional and next-generation probiotics have the potential to alleviate various diseases, studies that observe the therapeutic effect of next-generation probiotics on NASH are lacking. Therefore, we investigated whether a next-generation probiotic candidate, Faecalibacterium prausnitzii, contributed to the mitigation of NASH.

Methods

In this study, we conducted 16S rRNA sequencing analyses in patients with NASH and healthy controls. To test F. prausnitzii could alleviate NASH symptoms, we isolated four F. prausnitzii strains (EB-FPDK3, EB-FPDK9, EB-FPDK11, and EB-FPYYK1) from fecal samples collected from four healthy individuals. Mice were maintained on a high-fructose high-fat diet for 16 weeks to induce a NASH model and received oral administration of the bacterial strains. Changes in characteristic NASH phenotypes were assessed via oral glucose tolerance tests, biochemical assays, and histological analyses.

Results

16S rRNA sequencing analyses confirmed that the relative abundance of F. prausnitzii reduced significantly in patients with NASH compared to healthy controls (p &lt; 0.05). In the NASH mice, F. prausnitzii supplementation improved glucose homeostasis, prevented hepatic lipid accumulation, curbed liver damage and fibrosis, restored damaged gut barrier functions, and alleviated hepatic steatosis and liver inflammation. Furthermore, real-time PCR assays documented that the four F. prausnitzii strains regulated the expression of genes related to hepatic steatosis in these mice.

Discussion

Our study, therefore, confirms that the administration of F. prausnitzii bacteria can alleviate NASH symptoms. We propose that F. prausnitzii has the potential to contribute to the next-generation probiotic treatment of NASH.

Short chain fatty acids: key regulators of the local and systemic immune response in inflammatory diseases and infections

The human intestinal microbiome substantially affects human health and resistance to infections in its dynamic composition and varying release of microbial-derived metabolites. Short-chain fatty acids (SCFA) produced by commensal bacteria through fermentation of indigestible fibres are considered key regulators in orchestrating the host immune response to microbial colonization by regulating phagocytosis, chemokine and central signalling pathways of cell growth and apoptosis, thereby shaping the composition and functionality of the intestinal epithelial barrier. Although research of the last decades provided valuable insight into the pleiotropic functions of SCFAs and their capability to maintain human health, mechanistic details on how SCFAs act across different cell types and other organs are not fully understood. In this review, we provide an overview of the various functions of SCFAs in regulating cellular metabolism, emphasizing the orchestration of the immune response along the gut-brain, the gut-lung and the gut-liver axes. We discuss their potential pharmacological use in inflammatory diseases and infections and highlight new options of relevant human three-dimensional organ models to investigate and validate their biological functions in more detail.

Protective Effects of Hydroxyphenyl Propionic Acids on Lipid Metabolism and Gut Microbiota in Mice Fed a High-Fat Diet

Gut microbiota imbalances lead to the pathogenesis of non-alcoholic fatty liver disease (NAFLD), which is primarily accompanied by hepatic steatosis. Hydroxyphenyl propionic acids (HPP) have shown great potential in inhibiting lipid accumulation but their protective effects concerning NAFLD and intestinal microbiota have remained unclear. In this paper, we investigated the efficacies of 3-HPP and 4-HPP on hepatic steatosis and gut flora in mice fed a high-fat diet (HFD). We found that 3-HPP and 4-HPP administration decreased body weight and liver index, ameliorated dyslipidemia, and alleviated hepatic steatosis. Furthermore, 3-HPP and 4-HPP enhanced the multiformity of gut microbiota; improved the relative abundance of GCA-900066575, unidentified_Lachnospiraceae, and Lachnospiraceae_UCG-006 at genus level; increased concentration of acetic acid, propionic acid and butanoic acid in faeces; and reduced systemic endotoxin levels in NAFLD mice. Moreover, 4-HPP upregulated the relative abundance of genera Rikenella and downregulated the relative abundance of Faecalibaculum. Furthermore, 3-HPP and 4-HPP regulated lipid metabolism and ameliorated gut dysbiosis in NAFLD mice and 4-HPP was more effective than 3-HPP.

Lingguizhugan decoction improves non-alcoholic steatohepatitis partially by modulating gut microbiota and correlated metabolites

Background

Lingguizhugan decoction is a traditional Chinese medicine prescription that has been used to improve non-alcoholic fatty liver disease and its progressive form, non-alcoholic steatohepatitis (NASH). However, the anti-NASH effects and underlying mechanisms of Lingguizhugan decoction remain unclear.

Methods

Male Sprague-Dawley rats were fed a methionine- and choline-deficient (MCD) diet to induce NASH, and then given Lingguizhugan decoction orally for four weeks. NASH indexes were evaluated by histopathological analysis and biochemical parameters including serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), liver triglycerides (TG), etc. Fecal samples of rats were subjected to profile the changes of gut microbiota and metabolites using 16S rRNA sequencing and ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS). Bioinformatics was used to identify Lingguizhugan decoction reversed candidates, and Spearman's correlation analysis was performed to uncover the relationship among gut microbiota, fecal metabolites, and NASH indexes.

Results

Four-week Lingguizhugan decoction treatment ameliorated MCD diet-induced NASH features, as evidenced by improved hepatic steatosis and inflammation, as well as decreased serum AST and ALT levels. Besides, Lingguizhugan decoction partially restored the changes in gut microbial community composition in NASH rats. Meanwhile, the relative abundance of 26 genera was significantly changed in NASH rats, and 11 genera (such as odoribacter, Ruminococcus_1, Ruminococcaceae_UCG-004, etc.) were identified as significantly reversed by Lingguizhugan decoction. Additionally, a total of 99 metabolites were significantly altered in NASH rats, and 57 metabolites (such as TDCA, Glutamic acid, Isocaproic acid, etc.) enriched in different pathways were reversed by Lingguizhugan decoction. Furthermore, Spearman's correlation analyses revealed that most of the 57 metabolites were significantly correlated with 11 genera and NASH indexes.

Conclusion

Lingguizhugan decoction may exert protective effects on NASH partially by modulating gut microbiota and correlated metabolites.

Endogenous n-3 PUFAs Improve Non-Alcoholic Fatty Liver Disease through FFAR4-Mediated Gut-Liver Crosstalk

The gut-liver axis plays a key role in the development and progression of non-alcoholic fatty liver disease (NAFLD). Due to the complexity and incomplete understanding of the cross-talk between the gut and liver, effective therapeutic targets are largely unknown. Free fatty acid receptors (FFARs) may bridge the cross-talk between the gut and liver. FFAR4 has received considerable attention due to its important role in lipid metabolism. However, the role of FFAR4 in this cross talk in NAFLD remains unclear. In this study, mice with high endogenous n-3 PUFAs but FFAR4 deficiency were generated by crossbreeding Fat-1 and FFAR4 knockout mice. FFAR4 deficiency blocked the protective effects of high endogenous n-3 PUFAs on intestinal barrier dysfunction and hepatic steatosis. In addition, FFAR4 deficiency decreased gut microbiota diversity and enriched Rikenella, Anaerotruncus, and Enterococcus, and reduced Dubosiella, Ruminococcaceae UCG-010, Ruminococcaceae UCG-014, Coriobacteriaceae UCG-002, Faecalibaculum, Ruminococcaceae UCG-009, and Akkermansia. Notably, FFAR4 deficiency co-regulated pantothenic acid and CoA biosynthesis, β-alanine metabolism, and sphingolipid metabolism pathways in the gut and liver, potentially associated with the aggravation of NAFLD. Together, the beneficial effects of n-3 PUFAs on the gut and liver were mediated by FFAR4, providing insights on the role of FFAR4 in the treatment of NAFLD through the gut-liver axis.

Enterococcus faecium R-026 combined with Bacillus subtilis R-179 alleviate hypercholesterolemia and modulate the gut microbiota in C57BL/6 mice

Probiotics have been demonstrated to lower total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in individuals with mild hypercholesterolemia. Our previous study found that intervention with Bacillus subtilis R-179 and Enterococcus faecium R-026, well-known probiotics, improved obesity-associated dyslipidemia through ameliorating the gut microbiota, but similar studies on hypercholesterolemia have not been reported to date. Here, we investigated the therapeutic effect of live combined B. subtilis R-179 and E. faecium R-026 (LCBE) in a C57BL/6 mouse model of hypercholesterolemia. A total of 40 mice were administered with a high-cholesterol diet (containing 1.2% cholesterol) to establish a state of hypercholesterolemia for 4 weeks. Then, mice were divided into one model group (group M) and three treatment groups (n = 10 per group), which were administered with LCBE at 0.023 g/mouse/day (group L) or 0.230 g/mouse/day (group H), or atorvastatin 0.010 g/kg/day (group A), for 5 weeks while on a high-cholesterol diet. LCBE at high doses significantly alleviated the symptoms of group M and reduced serum TC, LDL-C, and lipopolysaccharide (LPS). LCBE improved liver steatosis and adipocyte enlargement caused by a high-cholesterol diet. In addition, the administration of LCBE regulated the change in gut microbiota and diversity (Shannon index). Compared with group M, the relative abundance of Actinobacteriota, Colidextribacter, and Dubosiella dramatically decreased in the treatment groups, which were positively correlated with serum TC and LPS. These findings indicated that the mechanism of action of LCBE in treating hypercholesterolemia may be modulation of the gut microbiota. In conclusion, LCBE ameliorated lipid accumulation, reduced inflammation, and alleviated the gut microbiota imbalance in hypercholesterolemic mice. These findings support the probiotic role of LCBE as a clinical candidate for the treatment of hypercholesterolemia.

Vitamin D improves hepatic steatosis in NAFLD via regulation of fatty acid uptake and β-oxidation

INTRODUCTION

The study aimed to explore the association of serum 25(OH)D₃ and hepatic steatosis in non-alcoholic fatty liver disease (NAFLD) patients and to determine whether the effect of vitamin D (VD) is mediated by activation of the peroxisome proliferator-activated receptor α (PPARα) pathway.

METHODS

The study contained a case-control study, in vivo and in vitro experiments. A case-control study was conducted to compare serum parameters between NAFLD patients and controls and to evaluate the association of 25(OH)D₃ and NAFLD. In vivo study, male Wistar rats were randomly divided into control and model groups, fed a standard chow diet and a high-fat diet (HFD), respectively, for 7 weeks to generate an NAFLD model. Then, the rats were treated with VD and a PPARα antagonist (MK886) for 7 weeks. Tissue and serum were collected and assessed by biochemical assays, morphological analysis, histological analysis, and western blot analysis. In vitro, HepG2 cells were incubated with oleic acid (OA) to induce steatosis, which was evaluated by staining. HepG2 cells were pretreated with MK886 followed by calcitriol treatment, and differences in lipid metabolism-related proteins were detected by western blot.

RESULTS

NAFLD patients were characterized by impaired liver function, dyslipidemia, and insulin resistance. Serum 25(OH)D₃ was negatively associated with alanine aminotransferase (ALT) in NAFLD. VD deficiency was a risk factor for patients with no advanced fibrosis. Adequate VD status (25(OH)D₃ >20 ng/mL) had a protective effect in patients after adjustment for confounding variables. NAFLD rats showed hyperlipidemia with severe hepatic steatosis, systematic inflammation, and lower serum 25(OH)D₃. VD treatment ameliorated hepatic steatosis both in NAFLD rats and OA-induced HepG2 cells. Further, MK886 inhibited the anti-steatosis effect of VD.

CONCLUSION

The study revealed that an adequate VD level may act as a protective factor in NAFLD and that VD may alleviate hepatic steatosis via the PPARα signaling pathway.

Assessing the in vivo ameliorative effects of Lactobacillus acidophilus KLDS1.0901 for induced non-alcoholic fatty liver disease treatment

Reputed as a significant metabolic disorder, non-alcoholic fatty liver disease (NAFLD) is characterized by high-fat deposits in the liver and causes substantial economic challenges to any country's workforce. Previous studies have indicated that some lactic acid bacteria may effectively prevent or treat NAFLD. Overall, L. acidophilus KLDS1.0901 protected against HFD-induced NAFLD by improving liver characteristics and modulating microbiota composition, and thus could be a candidate for improving NAFLD. This study aimed to assess the protective effects of L. acidophilus KLDS1.0901 on a high-fat diet(HFD)-induced NAFLD. First, hepatic lipid profile and histological alterations were determined to study whether L. acidophilus KLDS1.0901 could ameliorate NAFLD. Then, the intestinal permeability and gut barrier were explored. Finally, gut microbiota was analyzed to elucidate the mechanism from the insights of the gut-liver axis. The results showed that Lactobacillus KLDS1.0901 administration significantly decreased body weight, Lee's index body, fat rate, and liver index. L. acidophilus KLDS1.0901 administration significantly improved lipid profiles by decreasing the hepatic levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) and by increasing the high-density lipoprotein cholesterol (HDL-C) levels. A conspicuous decrease of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum was observed after L. acidophilus KLDS1.0901 administration. Meanwhile, the H&E and Oil Red O-stained staining showed that L. acidophilus KLDS1.0901 significantly reduced liver lipid accumulation of HFD-fed mice by decreasing the NAS score and lipid area per total area. Our results showed that L. acidophilus KLDS1.0901 administration decreased the interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-alpha (TNF-α) concentrations accompanied by the increase of interleukin-10 (IL-10). L. acidophilus KLDS1.0901 administration could improve the intestinal barrier function by upregulating the mRNA levels of occludin, claudin-1, ZO-1, and Muc-2, which were coupled to the decreases of the concentration of LPS and D-lactic acid. Notably, L. acidophilus KLDS1.0901 administration modulated the gut microbiota to a near-normal pattern. Hence, our results suggested that L. acidophilus KLDS1.0901 can be used as a candidate to ameliorate NAFLD.