Gut-liver axis: barriers and functional circuits

Gut Microbiota and Liver Regeneration: A Synthesis of Evidence on Structural Changes and Physiological Mechanisms

Liver regeneration (LR) is a unique biological process with the ability to restore up to 70% of the organ. This allows for the preservation of liver resections for various liver tumors and for living donor liver transplantation (LDLT). However, in some cases, LR is insufficient and interventions that can improve LR are urgently needed. Gut microbiota (GM) is one of the factors influencing LR, as the liver and intestine are intimately connected through the gut-liver axis. Thus, healthy GM facilitates normal LR, whereas dysbiosis leads to impaired LR due to imbalance of bile acids, inflammatory cytokines, microbial metabolites, signaling pathways, etc. Therefore, GM can be considered as a new possible therapeutic target to improve LR. In this review, we critically observe the current knowledge about the influence of gut microbiota (GM) on liver regeneration (LR) and the possibility to improve this process, which may reduce complication and mortality rates after liver surgery. Although much research has been done on this topic, more clinical trials and systemic reviews are urgently needed to move this type of intervention from the experimental phase to the clinical field.

Protective effects and mechanism of Sangyu granule on acetaminophen-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The Sang Yu granule (SY), a traditional Chinese medicine prescription of Xijing Hospital, was developed based on the Guanyin powder in the classical prescription "Hong's Collection of Proven Prescriptions" and the new theory of modern Chinese medicine. It has been proved to have a certain therapeutic effect on drug-induced liver injury (DILI), but the specific mechanism of action is still unclear.

AIM OF STUDY

Aim of the study was to explore the effect of SangYu granule on treating drug-induced liver injury induced by acetaminophen in mice.

MATERIALS AND METHODS

The chemical composition of SY, serum, and liver tissue was analyzed using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry. To assess hepatic function, measurements were taken using kits for total bile acids, as well as serum AST, ALT, and ALP activity. Concentrations of IL-1β and TNF-α in serum were quantified using ELISA kits. Transcriptome Sequencing Analysis and 2bRAD-M microbial diversity analysis were employed to evaluate gene expression variance in liver tissue and fecal microbiota diversity among different groups, respectively. Western blotting was performed to observe differences in the activation levels of FXR, SHP, CYP7A1 and PPARα in the liver, and the levels of FXR and FGF-15 genes and proteins in the ileum of mice. Additionally, fecal microbiota transplantation (FMT) experiments were conducted to investigate the potential therapeutic effect of administering the intestinal microbial suspension from mice treated with SY on drug-induced liver injury.

RESULTS

SY treatment exhibited significant hepatoprotective effects in mice, effectively ameliorating drug-induced liver injury while concurrently restoring intestinal microbial dysbiosis. Furthermore, SY administration demonstrated a reduction in the concentration of total bile acids, the expression of FXR and SHP proteins in the liver was up-regulated, CYP7A1 protein was down-regulated, and the expressions of FXR and FGF-15 proteins in the ileum were up-regulated. However, no notable impact on PPARα was observed. Furthermore, results from FMT experiments indicated that the administration of fecal suspensions derived from mice treated with SY did not yield any therapeutic benefits in the context of drug-induced liver injury.

CONCLUSION

The aforementioned findings strongly suggest that SY exerts a pronounced ameliorative effect on drug-induced liver injury through its ability to modulate the expression of key proteins involved in bile acid secretion, thereby preserving hepato-enteric circulation homeostasis.

Short-term dietary teprenone improved thermal tolerance and mitigated liver damage caused by heat stress in juvenile largemouth bass (Micropterus salmoides)

Heat stress seriously threatens fish survival and health, demanding immediate attention. Teprenone is a gastric mucosal protective agent that can induce heat shock protein expression. This research investigated the effects of teprenone on largemouth bass (Micropterus salmoides) subjected to heat stress. Juvenile fish were assigned to different groups: group C (control group, 0 mg teprenone/kg diet), T0, T200, T400, and T800 (0, 200, 400, and 800 mg teprenone/kg diet, respectively), which were fed for 3 days, followed by a day without the diet. All groups except group C were subjected to acute heat stress (from 24 °C to 35 °C at 1 °C per hour and then maintained at 35 °C for 3 h). The results were as follows: The critical thermal maxima were significantly higher in the T200, T400, and T800 groups compared with the T0 group (P < 0.05). Heat stress caused severe damage to the tissue morphology of the liver, while teprenone significantly reduced this injury (P < 0.05). Serum cortisol concentration decreased gradually as teprenone concentration increased, and the lowest concentration was observed in the T800 group (P < 0.05). Compared with the T0 group, the serum activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase were significantly lower in the T200, T400, and T800 groups (P < 0.05). The liver activities of catalase, total superoxide dismutase, and peroxidase were significantly higher in the T200 group than in the T0 group (P < 0.05). Transcript levels of the heat shock proteins (hsp90, hsp70, hspa5, and hsf1) and caspase family (caspase3 and caspase9) in the liver of the T200 group were significantly higher than those of the T0 group (P < 0.05). Western blot results showed that HSP70 and HSPA5 in the liver were significantly upregulated in the T200 group compared with the T0 group (P < 0.05). In summary, dietary teprenone improved thermal tolerance, alleviated heat stress damage in the liver, enhanced antioxidant capacity, and upregulated heat shock proteins in juvenile largemouth bass. This study offers theoretical support for applying teprenone in aquaculture to reduce financial losses caused by abiotic factors.

Polystyrene nanoplastics exacerbate aflatoxin B1-induced hepatic injuries by modulating the gut-liver axis

Dietary pollution of Aflatoxin B1 (AFB1) poses a great threat to global food safety, which can result in serious hepatic injuries. Following the widespread use of plastic tableware, co-exposure to microplastics and AFB1 has dramatically increased. However, whether microplastics could exert synergistic effects with AFB1 and amplify its hepatotoxicity, and the underlying mechanisms are still unelucidated. Here, mice were orally exposed to 100 nm polystyrene nanoplastics (NPs) and AFB1 to investigate the influences of NPs on AFB1-induced hepatic injuries. We found that exposure to only NPs or AFB1 resulted in colonic inflammation and the impairment of the intestinal barrier, which was exacerbated by combined exposure to NPs and AFB1. Meanwhile, co-exposure to NPs exacerbated AFB1-induced dysbiosis of gut microbiota and remodeling of the fecal metabolome. Moreover, NPs and AFB1 co-exposure exhibited higher levels of systemic inflammatory factors compared to AFB1 exposure. Additionally, NPs co-exposure further exacerbated AFB1-induced hepatic fibrosis and inflammation, which could be associated with the overactivation of the TLR4/MyD88/NF-κB pathway. Notably, Spearman's correlation analysis revealed that the exacerbation of NPs co-exposure was closely associated with microbial dysbiosis. Furthermore, microbiota from NPs-exposed mice (NPsFMT) partly reproduced the exacerbation of NPs on AFB1-induced systemic and hepatic inflammation, but not fibrosis. In summary, our findings indicate that gut microbiota could be involved in the exacerbation of NPs on AFB1-induced hepatic injuries, highlighting the health risks of NPs.

Role of gut microbiota and immune cells in metabolic-associated fatty liver disease: clinical impact

In 2020, a revised definition of fatty liver disease associated with metabolic dysfunction (MAFLD) was proposed to replace non-alcoholic fatty liver (NAFLD). Liver steatosis and at least one of the three metabolic risk factors, including type 2 diabetes, obesity, or signs of metabolic dysregulation, are used to diagnose MAFLD. MAFLD, similarly to NAFLD, is characterized by a spectrum of disease ranging from simple steatosis to advanced metabolic steatohepatitis with or without fibrosis, and may progress to cirrhosis and liver cancer, including increased risk of other critical extrahepatic diseases. Even though the pathophysiology of MAFLD and potential therapeutic targets have been explored in great detail, there is yet no Food and Drug Administration approved treatment. Recently, gut microbiome-derived products (e.g., endotoxins and metabolites) involved in intestinal barrier disruption, systemic inflammation, and modification of intrahepatic immunity have been associated with MAFLD development and progression. Therefore, different strategies could be adopted to modify the gut microbiome to improve outcomes in early and progressive MAFLD. Here, we provide an overview of mechanisms that may link the gut microbiome and immune response during the onset of liver steatosis and progression to steatohepatitis and fibrosis in patients with MAFLD. Finally, gut microbiota-based approaches are discussed as potential personalized treatments against MAFLD.

Synergistic risk in the gut and liver: Insights into the toxic mechanisms and molecular interactions of combined exposure to triazophos and fenvalerate in zebrafish

The simultaneous or sequential application of pesticides such as triazophos (TRI) and fenvalerate (FEN) in agriculture results in their residues co-existing in the environments. However, the impact of co-exposure to TRI and FEN on the gut-liver axis, along with the underlying mechanisms, remains unclear. Our results showed that exposure to FEN (96 h-LC50 value of 0.096 mg a.i. L-1) was more toxic to adult zebrafish compared to TRI (96 h-LC50 value of 6.75 mg a.i. L-1). Furthermore, the study aimed to reveal the toxic potencies of individual and combined exposure to TRI and FEN on the liver-gut axis in zebrafish (Danio rerio). Our results also indicated that pesticide exposure decreased tight junction molecule expression and increased intestinal inflammatory molecule expression in D. rerio, with co-exposure demonstrating enhanced toxicity. Co-exposure altered gut flora structure and species abundance. RNA-Seq sequencing revealed changes in liver gene expressions, particularly enrichment of P53 signaling. Molecular docking demonstrated FEN's stronger binding to P53 and Caspase3, correlating with its higher toxicity. Liver pathology confirmed exacerbated liver damage by individual and co-exposures, with co-exposure inducing more severe liver injury. qPCR results showed increased pro-apoptotic gene expression and decreased anti-apoptotic gene expression, with co-exposure exhibiting an interactive effect. Overall, this study identifies specific targets and pathways influenced by these pesticides, revealing toxicity mechanisms involving the gut-liver axis, which is crucial for environmental risk assessment of pesticide mixtures.

Dissecting causal relationships between gut microbiota, blood metabolites, and glioblastoma multiforme: a two-sample Mendelian randomization study

Background

Given the increasing interest in the role of gut microbiota in glioblastoma multiforme (GBM), our objective was to examine the potential causal relationship between gut microbiota and GBM, as well as the mediating effects of specific metabolites.

Methods

A bidirectional two-sample Mendelian randomization (MR) analysis was conducted to investigate the associations between 196 microbial taxa and GBM. A two-step MR technique was used to identify significant mediators in this relationship. Subsequently, a mediation analysis was performed to explore and quantify the mediating effects of specific metabolites on the causal relationship between gut microbiota and GBM.

Results

Five taxa showed significant associations with GBM. Among them, family Victivallaceae [odds ratio (OR): 1.95; 95% confidence interval (CI): 1.21, 3.13; p = 0.005] and genus Lactococcus (OR: 1.81; 95% CI: 1.04, 3.15; p = 0.036) were positively correlated with the risk of GBM, while phylum Cyanobacteria had a protective effect against GBM (OR: 0.45; 95% CI: 0.22, 0.89; p = 0.021). The mediation analysis revealed that the connections among family Victivallaceae, genus Lactococcus, phylum Cyanobacteria and GBM were mediated by Methyl-4-hydroxybenzoate sulfate, phosphoethanolamine and dehydroepiandrosterone sulfate. Each of these accounted for 7.27, 7.98, and 8.65%, respectively.

Conclusion

Our study provides evidence supporting a potential causal association between certain gut microbiota taxa and GBM. The study highlights the central role of gut microbiota in GBM pathogenesis and their interactions with vital serum metabolites. This paves the way for potential novel therapeutic interventions in GBM management.

Altered gut microbiota is associated with the formation of occult hepatitis B virus infection

Hepatitis B virus (HBV), a common blood transmission pathogen worldwide, can lead to viral hepatitis, cirrhosis, liver cancer, and other liver diseases. In particular, occult hepatitis B virus infection (OBI) may be caused by an immune response leading to suppressed virus replication. Gut microbiota can change the immunity status of the human body and, therefore, affect the replication of HBV. Thus, to identify whether there are differences in gut microbiota between HBV carriers and OBI carriers, we collected fecal samples from 18 HBV carriers, 24 OBI blood donors, and also 20 healthy blood donors as negative control. After 16S sequencing, we found that the abundance of Faecalibacterium was significantly reduced in samples from OBI blood donors compared with those from healthy blood donors. Compared with samples from HBV carriers, the samples from OBI blood donors had a significantly increased abundance of Subdoligranulum, which might stimulate immune activation, thus inhibiting HBV replication and contributing to the formation of occult infection. Our findings revealed the potential role of gut microbiota in the formation of OBI and further provided a novel strategy for the treatment of HBV infection.IMPORTANCEOccult hepatitis B virus infection (OBI) is a special form of hepatitis B virus infection with hepatitis B surface antigen (HBsAg) positive and hepatitis B virus (HBV) DNA negative. Gut microbiota may contribute to the immune response leading to suppressed virus replication and, thus, participates in the development of OBI. The study on gut microbiota of OBI blood donors provides novel data considerably advancing our understanding of the immune mechanism for the determination of occult hepatitis B virus infection, which is helpful for improving the strategy of the treatment of HBV infection.

Taurine-conjugated bile acids and their link to hepatic S1PR2 play a significant role in hepatitis C-related liver disease

BACKGROUND

Bile acids mediate gut-liver cross-talk through bile acid receptors. Serum, hepatic, and microbial bile acid metabolism was evaluated in HCV-compensated chronic liver disease.

METHODS

Patients underwent liver biopsy; portal and peripheral blood were obtained before (HCVi), and 6 months after sustained virologic response (SVR), splenic blood was obtained only after SVR. The fecal microbiome and liver transcriptome were evaluated using RNA-Seq. Twenty-four bile acids were measured in serum, summed as free, taurine-conjugated bile acids (Tau-BAs), and glycine-conjugated bile acids.

RESULTS

Compared to SVR, HCVi showed elevated conjugated bile acids, predominantly Tau-BA, compounded in HCVi cirrhosis. In the liver, transcription of bile acids uptake, synthesis, and conjugation was decreased with increased hepatic spillover into systemic circulation in HCVi. There was no difference in the transcription of microbial bile acid metabolizing genes in HCVi. Despite an overall decrease, Tau-BA remained elevated in SVR cirrhosis, mainly in splenic circulation. Only conjugated bile acids, predominantly Tau-BA, correlated with serum proinflammatory markers and hepatic proinflammatory pathways, including NLRP3 and NFKB. Among hepatic bile acid receptors, disease-associated conjugated bile acids showed the strongest association with hepatic spingosine-1-phosphate receptor 2 (S1PR2).

CONCLUSIONS

Enhanced expression of hepatic S1PR2 in HCVi and HCVi-cirrhosis and strong associations of S1PR2 with Tau-BAs suggest pathological relevance of Tau-BA-hepatic S1PR2 signaling in chronic liver disease. These findings have therapeutic implications in chronic liver diseases.

Microfluidic-based multifunctional microspheres for enhanced oral co-delivery of probiotics and postbiotics

Probiotic-based therapies have shown great potential in the prevention and treatment of many diseases by positively regulating intestinal flora homeostasis. However, the efficacy of oral probiotics is severely limited due to the loss of bioactivity, short intestinal retention time, and insufficient therapeutic effect. Here, based on droplet microfluidics, we developed a hydrogel microsphere with colonic targeting and mucoadhesive capabilities as a multifunctional delivery platform, which can be used for co-delivery of probiotics (Escherichia coli Nissle 1917, EcN) and auxiliary molecules (indole-3-propionic acid, IPA), achieving synergistic therapeutic effects. In vivo studies shown that the integrated multifunctional microspheres can significantly reduce intestinal inflammation, repair intestinal barrier function, enhance probiotic colonization in the intestine, and modulate disordered intestinal flora, demonstrating enhanced therapeutic effects in a mouse model of colitis. This work reveals that microfluidic-based smart droplet microspheres can provide a versatile platform for advanced microbial therapies.

Recent progress in Porphyra haitanensis polysaccharides: Extraction, purification, structural insights, and their impact on gastrointestinal health and oxidative stress management

Porphyra haitanensis, a red seaweed species, represents a bountiful and sustainable marine resource. P. haitanensis polysaccharide (PHP), has garnered considerable attention for its numerous health benefits. However, the comprehensive utilization of PHP on an industrial scale has been limited by the lack of comprehensive information. In this review, we endeavor to discuss and summarize recent advancements in PHP extraction, purification, and characterization. We emphasize the multifaceted mechanisms through which PHP promotes gastrointestinal health. Furthermore, we present a summary of compelling evidence supporting PHP's protective role against oxidative stress. This includes its demonstrated potent antioxidant properties, its ability to neutralize free radicals, and its capacity to enhance the activity of antioxidant enzymes. The information presented here also lays the theoretical groundwork for future research into the structural and functional aspects of PHP, as well as its potential applications in functional foods.

Role of liver sinusoidal endothelial cell in metabolic dysfunction-associated fatty liver disease

Liver sinusoidal endothelial cells (LSECs) are highly specialized endothelial cells that represent the interface between blood cells on one side and hepatocytes on the other side. LSECs not only form a barrier within the hepatic sinus, but also play important physiological functions such as regulating hepatic vascular pressure, anti-inflammatory and anti-fibrotic. Pathologically, pathogenic factors can induce LSECs capillarization, that is, loss of fenestra and dysfunction, which are conducive to early steatosis, lay the foundation for the progression of metabolic dysfunction-associated fatty liver disease (MAFLD), and accelerate metabolic dysfunction-associated steatohepatitis (MASH) and liver fibrosis. The unique localization, phenotype, and function of LSECs make them potential candidates for reducing liver injury, inflammation, and preventing or reversing fibrosis in the future.

3-O-acylated bile acids: disrupters or harmonizers of metabolism?

Unveiling a metabolic mystery, this article explores how 3-O-acylated bile acids, specifically 3-O-succinylated cholic acid (3-sucCA) and 3-acetylated cholic acid (3-acetyCA), modified by gut microbes Bacteroides uniformis and Christensenella minuta, respectively, may either disrupt or harmonize our metabolic processes, offering novel therapeutic avenues for conditions such as metabolic dysfunction-associated steatohepatitis (MASH) and type 2 diabetes mellitus (T2D).

Type-I interferon shapes peritoneal immunity in cirrhosis and drives caspase-5-mediated progranulin release upon infection

BACKGROUND & AIMS

Gut bacterial translocation contributes to immune dysfunction and spontaneous bacterial peritonitis (SBP) in cirrhosis. We hypothesized that exposure of peritoneal macrophages (PMs) to bacterial DNA results in type-I interferon (IFN) production, shaping subsequent immune responses, inflammasome activation, and the release of damage-associated molecular patterns (DAMPs).

METHODS

PMs from patients with cirrhosis were stimulated with E. coli single-stranded DNA (ssDNA), lipopolysaccharide LPS, and IFN or infected with E. coli, S. aureus, and Group B streptococcus in vitro. Cytokine release, inflammasome activation, and DAMP release were quantified by quantitative-PCR, ELISA, western blots, and reporter cells employing primary PMs, monocytes, and caspase-deficient THP-1 macrophages. Serum progranulin concentration was correlated with transplant-free survival in 77 patients with SBP.

RESULTS

E. coli ssDNA induced strong type-I IFN activity in PMs and monocytes, priming them for enhanced LPS-mediated tumor necrosis factor production without toll-like receptor 4 tolerance induction. During in vitro macrophage bacterial infection, type-I IFN release aligned with upregulated expression of IFN-regulatory factors (IRF)1/2 and guanylate binding proteins (GBP)2/5. PMs upregulated inflammasome-associated proteins and type-I IFN upon E. coli ssDNA exposure and released interleukin-1β upon bacterial infection. Proteomic screen in mouse macrophages revealed progranulin as being caspase-11-dependent during E. coli infection. PMs and THP-1 macrophages released significant amounts of progranulin when infected with S. aureus or E. coli via gasdermin-D in a type-I IFN and caspase-5-dependent manner. During SBP, PMs upregulated IRF1, GBP2/5 and caspase-5 and higher serum progranulin concentrations were indicative of lower 90-day transplant-free survival after SBP.

CONCLUSIONS

Type-I IFN shapes peritoneal immune responses and regulates caspase-5-mediated progranulin release during SBP.

IMPACT AND IMPLICATIONS

Patients with cirrhosis exhibit impaired immune responses and increased susceptibility to bacterial infections. This study reveals that type-I interferon responses, triggered by pathogen-associated molecular patterns, are crucial in regulating macrophage activation and priming them for inflammatory responses. Additionally, we elucidate the mechanisms by which type-I interferons promote the release of progranulin from macrophages during spontaneous bacterial peritonitis. Our findings enhance understanding of how bacterial translocation affects immune responses, identify novel biomarkers for inflammasome activation during infections, and point to potential therapeutic targets.

Ferroptosis: An important mechanism of disease mediated by the gut-liver-brain axis

AIMS

As a unique iron-dependent non-apoptotic cell death, Ferroptosis is involved in the pathogenesis and development of many human diseases and has become a research hotspot in recent years. However, the regulatory role of ferroptosis in the gut-liver-brain axis has not been elucidated. This paper summarizes the regulatory role of ferroptosis and provides theoretical basis for related research.

MATERIALS AND METHODS

We searched PubMed, CNKI and Wed of Science databases on ferroptosis mediated gut-liver-brain axis diseases, summarized the regulatory role of ferroptosis on organ axis, and explained the adverse effects of related regulatory effects on various diseases.

KEY FINDINGS

According to our summary, the main way in which ferroptosis mediates the gut-liver-brain axis is oxidative stress, and the key cross-talk of ferroptosis affecting signaling pathway network is Nrf2/HO-1. However, there were no specific marker between different organ axes mediate by ferroptosis.

SIGNIFICANCE

Our study illustrates the main ways and key cross-talk of ferroptosis mediating the gut-liver-brain axis, providing a basis for future research.

Endogenous ethanol production in health and disease

The gut microbiome exerts metabolic actions on distal tissues and organs outside the intestine, partly through microbial metabolites that diffuse into the circulation. The disruption of gut homeostasis results in changes to microbial metabolites, and more than half of the variance in the plasma metabolome can be explained by the gut microbiome. Ethanol is a major microbial metabolite that is produced in the intestine of nearly all individuals; however, elevated ethanol production is associated with pathological conditions such as metabolic dysfunction-associated steatotic liver disease and auto-brewery syndrome, in which the liver's capacity to metabolize ethanol is surpassed. In this Review, we describe the mechanisms underlying excessive ethanol production in the gut and the role of ethanol catabolism in mediating pathogenic effects of ethanol on the liver and host metabolism. We conclude by discussing approaches to target excessive ethanol production by gut bacteria.

Targeted delivery strategies: The interactions and applications of nanoparticles in liver diseases

In recent years, nanoparticles have been broadly utilized in various drugs delivery formulations. Nanodelivery systems have shown promise in solving problems associated with the distribution of hydrophobic drugs and have promoted the accumulation of nanomedicines in the circulation or in organs. However, the injection dose of nanoparticles (NPs) is much greater than that needed by diseased tissues or organs. In other words, most of the NPs are localized off-target and do not reach the desired tissue or organs. With the rapid development of biodegradable and biosafety nanomaterials, the nanovectors represent assurance of safety. However, the off-target effects also induce concerns about the application of NPs, especially in the delivery of gene editing tools. Therefore, a complete understanding of the biological responses to NPs in the body will clearly guide the design of targeted delivery of NPs. The different properties of various nanodelivery systems may induce diverse interactions between carriers and organs. In this review, we describe the relationship between the liver, the most influenced organ of systemic administration of NPs, and targeted delivery nanoplatforms. Various transport vehicles have adopted multiple delivery strategies for the targeted delivery to the cells in the homeostasis liver and in diseased liver. Additionally, nanodelivery systems provide a novel strategy for treating incurable diseases. The appearance of a targeted delivery has profoundly improved the application of NPs to liver diseases.

Lung-Gut Microbiota and Tryptophan Metabolites Changes in Neonatal Acute Respiratory Distress Syndrome

Purpose

Neonatal Acute Respiratory Distress Syndrome (NARDS) is a severe respiratory crisis threatening neonatal life. We aim to identify changes in the lung-gut microbiota and lung-plasma tryptophan metabolites in NARDS neonates to provide a differentiated tool and aid in finding potential therapeutic targets.

Patients and Methods

Lower respiratory secretions, faeces and plasma were collected from 50 neonates including 25 NARDS patients (10 patients with mild NARDS in the NARDS_M group and 15 patients with moderate-to-severe NARDS in the NARDS_S group) and 25 control patients screened based on gestational age, postnatal age and birth weight. Lower airway secretions and feces underwent 16S rRNA gene sequencing to understand the microbial communities in the lung and gut, while lower airway secretions and plasma underwent LC-MS analysis to understand tryptophan metabolites in the lung and blood. Correlation analyses were performed by comparing differences in microbiota and tryptophan metabolites between NARDS and control, NARDS_S and NARDS_M groups.

Results

Significant changes in lung and gut microbiota as well as lung and plasma tryptophan metabolites were observed in NARDS neonates compared to controls. Proteobacteria and Bacteroidota were increased in the lungs of NARDS neonates, whereas Firmicutes, Streptococcus, and Rothia were reduced. Lactobacillus in the lungs decreased in NARDS_S neonates. Indole-3-carboxaldehyde decreased in the lungs of NARDS neonates, whereas levels of 3-hydroxykynurenine, indoleacetic acid, indolelactic acid, 3-indole propionic acid, indoxyl sulfate, kynurenine, and tryptophan decreased in the lungs of the NARDS_S neonates. Altered microbiota was significantly related to tryptophan metabolites, with changes in lung microbiota and tryptophan metabolites having better differentiated ability for NARDS diagnosis and grading compared to gut and plasma.

Conclusion

Significant changes occurred in the lung-gut microbiota and lung-plasma tryptophan metabolites of NARDS neonates. Alterations in lung microbiota and tryptophan metabolites were better discriminatory for the diagnosis and grading of NARDS.

Metabolic flux and catabolic kinetics of prebiotic-like dietary polyphenol phlorizin in association with gut microbiota in vitro

As ubiquitous components among fruits, polyphenols, including flavonoids and phenolic acids, are somewhat embarrassed on their health benefits but low bioavailability, triggering a hotspot on their interaction with microbiota. Due to its structural characteristics similar to flavonoids and phenolic acids, dihydrochalcone phlorizin (PHZ) was selected as a reference, to illustrate its step-by-step metabolic fate associated with microbiota. The results confirmed that the metabolic flux of PHZ starts with its conversion to phloretin (PHT), sequentially followed by the formation of 3-(4-hydroxyphenyl) propionic acid (PHA), and 4-hydroxyphenylacetic acid (4-HPAA). Catabolic characteristics was comparatively elucidated by introducing apparent and potential kinetics. Besides, coupling catabolic processes with microbial changes suggested several potential bacteria involving in PHZ metabolism, as well as those regulated by PHZ and its metabolites. In particular, seven strains from Lactobacillus were selectively isolated and confirmed to be essential for deglycosylation of PHZ, implying a potential synergistic effect between PHZ and Lactobacillus.

Ascitic microbiota alteration is associated with portal vein tumor thrombosis occurrence and prognosis in hepatocellular carcinoma

Portal vein tumor thrombosis (PVTT) frequently leads to malignant ascites (MA) in individuals with hepatocellular carcinoma (HCC), remaining a bottleneck in the treatment. This study aimed to explore the differences in microbes in paired groups and provide novel insights into PVTT and MA-related treatments. Formalin-fixed paraffin embedding ascite samples were collected from MA secondary to HCC and benign ascites (BA) secondary to liver cirrhosis (LC). Ascitic microbiota profiles were determined in the HCC and LC groups by 16S rRNA sequencing. Prognostic risk factors were screened using survival analysis. The correlation between the significantly different microbial signatures in the groups with PVTT (WVT) and non-PVTT (NVT) and clinical characteristics was explored. The expression of different immune cells was determined by labeling four markers in the MA tissue chips using multiplex immunohistochemistry. A total of 240 patients (196 with HCC with MA and 44 with LC with BA) were included in this study. Microbial profiles differed between the HCC and LC groups. PVTT and Barcelona Clinic Liver Cancer stage were shown to be prognostic risk factors. Significant differences in the alpha and beta diversities were observed between the WVT and NVT groups. Gammaproteobacteria and Acinetobacter were the most abundant in the HCC MA. Differences in microbial signatures between the WVT and NVT groups were correlated with the level of C-reactive protein and apolipoprotein A1. This study revealed the microbial differences in the tumor microenvironment of MA secondary to HCC and BA secondary to LC.IMPORTANCEFirst, we explored the alteration of the ascites ecosystem through the microbiota in patients with hepatocellular carcinoma (HCC) and liver cirrhosis. Second, this is the first clinical study to investigate the differences between patients with HCC with and without portal vein tumor thrombosis via 16S rRNA sequencing. These results revealed a decreased microbial diversity and metabolic dysregulation in individuals with HCC and portal vein tumor thrombosis. Gammaproteobacteria and Acinetobacter were the most abundant in the HCC malignant ascitic fluid. Our study provides a new perspective on treating malignant ascites secondary to HCC.

The Potential Mechanism of the Anti-Liver Fibrotic Effect of Curcumin in the Gut-Liver Axis

This study aimed to explore the curative effect of curcumin on liver fibrosis and its correlation with the gut-liver axis in animal models. Histological staining was utilized to conduct histological analysis of the liver and intestine. An automatic biochemical analyzer or enzyme-linked immunosorbent assay system was utilized for analyzing the biochemical indexes in mice. Western blotting was employed to examine the level of relevant proteins. Furthermore, 16S rRNA high-throughput sequencing was performed to explore the impact of curcumin on intestinal microorganisms in rats with liver fibrosis. Ultrahigh-performance liquid chromatography with quadrupole-orbitrap mass spectrometry was utilized to analyze the effect of curcumin on rat feces metabolites. Our results showed that curcumin reduced the formation of collagen fibers caused by carbon tetrachloride in a dose-dependent manner. In addition, curcumin was able to restore intestinal permeability in rats with liver fibrosis. By adopting α diversity analysis (Chao 1 index, Shannon index, and Simpson index), we observed that both the diversity and the abundance of intestinal flora in rats with liver fibrosis were increased. The principal component analysis diagram demonstrated that curcumin could enhance the abundance and diversity of intestinal flora, and also restore the composition of model rat flora, which was similar to that in normal rats, thereby correcting the imbalance of flora in rats with liver fibrosis. In addition, curcumin regulated feces metabolites and their signaling pathways, including glycerophospholipid metabolism, pantothenate and CoA biosynthesis. Our findings suggest that curcumin exhibits antiliver fibrosis effects, and its antiliver fibrosis effects might correlate with gut-liver axis.

The regional disparities in liver disease comorbidity among elderly Chinese based on a health ecological model: the China Health and Retirement Longitudinal Study

PURPOSE

This study aimed to investigate the risk factors for liver disease comorbidity among older adults in eastern, central, and western China, and explored binary, ternary and quaternary co-morbid co-causal patterns of liver disease within a health ecological model.

METHOD

Basic information from 9,763 older adults was analyzed using data from the China Health and Retirement Longitudinal Study (CHARLS). LASSO regression was employed to identify significant predictors in eastern, central, and western China. Patterns of liver disease comorbidity were studied using association rules, and spatial distribution was analyzed using a geographic information system. Furthermore, binary, ternary, and quaternary network diagrams were constructed to illustrate the relationships between liver disease comorbidity and co-causes.

RESULTS

Among the 9,763 elderly adults studied, 536 were found to have liver disease comorbidity, with binary or ternary comorbidity being the most prevalent. Provinces with a high prevalence of liver disease comorbidity were primarily concentrated in Inner Mongolia, Sichuan, and Henan. The most common comorbidity patterns identified were "liver-heart-metabolic", "liver-kidney", "liver-lung", and "liver-stomach-arthritic". In the eastern region, important combination patterns included "liver disease-metabolic disease", "liver disease-stomach disease", and "liver disease-arthritis", with the main influencing factors being sleep duration of less than 6 h, frequent drinking, female, and daily activity capability. In the central region, common combination patterns included "liver disease-heart disease", "liver disease-metabolic disease", and "liver disease-kidney disease", with the main influencing factors being an education level of primary school or below, marriage, having medical insurance, exercise, and no disabilities. In the western region, the main comorbidity patterns were "liver disease-chronic lung disease", "liver disease-stomach disease", "liver disease-heart disease", and "liver disease-arthritis", with the main influencing factors being general or poor health satisfaction, general or poor health condition, severe pain, and no disabilities.

CONCLUSION

The comorbidities associated with liver disease exhibit specific clustering patterns at both the overall and local levels. By analyzing the comorbidity patterns of liver diseases in different regions and establishing co-morbid co-causal patterns, this study offers a new perspective and scientific basis for the prevention and treatment of liver diseases.

Exploration of the core pathway of inflammatory bowel disease complicated with metabolic fatty liver and two-sample Mendelian randomization study of the causal relationships behind the disease

Background

Inflammatory bowel disease (IBD) is often associated with complex extraintestinal manifestations. The incidence of nonalcoholic fatty liver disease (NAFLD) in IBD populations is increasing yearly. However, the mechanism of interaction between NAFLD and IBD is not clear. Consequently, this study aimed to explore the common genetic characteristics of IBD and NAFLD and identify potential therapeutic targets.

Materials and methods

Gene chip datasets for IBD and NAFLD were obtained from the Gene Expression Omnibus (GEO) database. Weighted gene co-expression network analysis (WGCNA) was performed to identify modules in those datasets related to IBD and NAFLD. ClueGO was used for biological analysis of the shared genes between IBD and NAFLD. Based on the Human MicroRNA Disease Database (HMDD), microRNAs (miRNAs) common to NAFLD and IBD were obtained. Potential target genes for the miRNAs were predicted using the miRTarbase, miRDB, and TargetScan databases. Two-sample Mendelian randomization (MR) and two-way MR were used to explore the causal relationship between Interleukin-17 (IL-17) and the risk of IBD and NAFLD using data from GWAS retrieved from an open database.

Results

Through WGCNA, gene modules of interest were identified. GO enrichment analysis using ClueGO suggested that the abnormal secretion of chemokines may be a common pathophysiological feature of IBD and NAFLD, and that the IL-17-related pathway may be a common key pathway for the pathological changes that occur in IBD and NAFLD. The core differentially expressed genes (DEGs) in IBD and NAFLD were identified and included COL1A1, LUM, CCL22, CCL2, THBS2, COL1A2, MMP9, and CXCL8. Another cohort was used for validation. Finally, analysis of the miRNAs identified potential therapeutic targets. The MR results suggested that although there was no causal relationship between IBD and NAFLD, there were causal relationships between IL-17 and IBD and NAFLD.

Conclusion

We established a comorbid model to explain the potential mechanism of IBD with NAFLD and identified the chemokine-related pathway mediated by cytokine IL-17 as the core pathway in IBD with NAFLD, in which miRNA also plays a role and thus provides potential therapeutic targets.

Exploring Advanced Therapies for Primary Biliary Cholangitis: Insights from the Gut Microbiota-Bile Acid-Immunity Network

Primary biliary cholangitis (PBC) is a cholestatic liver disease characterized by immune-mediated injury to small bile ducts. Although PBC is an autoimmune disease, the effectiveness of conventional immunosuppressive therapy is disappointing. Nearly 40% of PBC patients do not respond to the first-line drug UDCA. Without appropriate intervention, PBC patients eventually progress to liver cirrhosis and even death. There is an urgent need to develop new therapies. The gut-liver axis emphasizes the interconnection between the gut and the liver, and evidence is increasing that gut microbiota and bile acids play an important role in the pathogenesis of cholestatic diseases. Dysbiosis of gut microbiota, imbalance of bile acids, and immune-mediated bile duct injury constitute the triad of pathophysiology in PBC. Autoimmune cholangitis has the potential to be improved through immune system modulation. Considering the failure of conventional immunotherapies and the involvement of gut microbiota and bile acids in the pathogenesis, targeting immune factors associated with them, such as bile acid receptors, microbial-derived molecules, and related specific immune cells, may offer breakthroughs. Understanding the gut microbiota-bile acid network and related immune dysfunctions in PBC provides a new perspective on therapeutic strategies. Therefore, we summarize the latest advances in research of gut microbiota and bile acids in PBC and, for the first time, explore the possibility of related immune factors as novel immunotherapy targets. This article discusses potential therapeutic approaches focusing on regulating gut microbiota, maintaining bile acid homeostasis, their interactions, and related immune factors.

Succinic Acid Ameliorates Concanavalin A-Induced Hepatitis by Altering the Inflammatory Microenvironment and Expression of BCL-2 Family Proteins

Autoimmune hepatitis (AIH) is a severe immune-mediated inflammatory liver disease that currently lacks feasible drug treatment methods. Our study aimed to evaluate the protective effect of succinic acid against AIH and provide a reliable method for the clinical treatment of AIH. We performed an in vivo study of the effects of succinic acid on concanavalin A (ConA)-induced liver injury in mice. We examined liver transaminase levels, performed hematoxylin and eosin (HE) staining, and observed apoptotic phenotypes in mice. We performed flow cytometry to detect changes in the number of neutrophils and monocytes, and used liposomes to eliminate the liver Kupffer cells and evaluate their role. We performed bioinformatics analysis, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blotting to detect mitochondrial apoptosis-induced changes in proteins from the B-cell lymphoma 2(Bcl-2) family. Succinic acid ameliorated ConA-induced AIH in a concentration-dependent manner, as reflected in the survival curve. HE and TUNEL staining and terminal deoxynucleotidyl transferase dUTP nick end labeling revealed decreased alanine transaminase and aspartate aminotransferase levels, and reduced liver inflammation and apoptosis. RT-qPCR and enzyme-linked immunosorbent assay revealed that succinic acid significantly reduced liver pro-inflammatory cytokine levels. Flow cytometry revealed significantly decreased levels of liver neutrophils. Moreover, the protective effect of succinic acid disappeared after the Kupffer cells were eliminated, confirming their important role in the effect. Bioinformatics analysis, RT-qPCR, and western blotting showed that succinic acid-induced changes in proteins from the Bcl-2 family involved mitochondrial apoptosis, indicating the molecular mechanism underlying the protective effect of succinic acid. Succinic acid ameliorated ConA-induced liver injury by regulating immune balance, inhibiting pro-inflammatory factors, and promoting anti-apoptotic proteins in the liver. This study provides novel insights into the biological functions and therapeutic potential of succinic acid in the treatment of autoimmune liver injury.

Probiotic Pediococcus pentosaceus restored gossypol-induced intestinal barrier injury by increasing propionate content in Nile tilapia

BACKGROUND

Intestinal barrier is a dynamic interface between the body and the ingested food components, however, dietary components or xenobiotics could compromise intestinal integrity, causing health risks to the host. Gossypol, a toxic component in cottonseed meal (CSM), caused intestinal injury in fish or other monogastric animals. It has been demonstrated that probiotics administration benefits the intestinal barrier integrity, but the efficacy of probiotics in maintaining intestinal health when the host is exposed to gossypol remains unclear. Here, a strain (YC) affiliated to Pediococcus pentosaceus was isolated from the gut of Nile tilapia (Oreochromis niloticus) and its potential to repair gossypol-induced intestinal damage was evaluated.

RESULTS

A total of 270 Nile tilapia (2.20 ± 0.02 g) were allotted in 3 groups with 3 tanks each and fed with 3 diets including CON (control diet), GOS (control diet containing 300 mg/kg gossypol) and GP (control diet containing 300 mg/kg gossypol and 108 colony-forming unit (CFU)/g P. pentosaceus YC), respectively. After 10 weeks, addition of P. pentosaceus YC restored growth retardation and intestinal injury induced by gossypol in Nile tilapia. Transcriptome analysis and siRNA interference experiments demonstrated that NOD-like receptors (NLR) family caspase recruitment domain (CARD) domain containing 3 (Nlrc3) inhibition might promote intestinal stem cell (ISC) proliferation, as well as maintaining gut barrier integrity. 16S rRNA sequencing and gas chromatography-mass spectrometry (GC-MS) revealed that addition of P. pentosaceus YC altered the composition of gut microbiota and increased the content of propionate in fish gut. In vitro studies on propionate's function demonstrated that it suppressed nlrc3 expression and promoted wound healing in Caco-2 cell model.

CONCLUSIONS

The present study reveals that P. pentosaceus YC has the capacity to ameliorate intestinal barrier injury by modulating gut microbiota composition and elevating propionate level. This finding offers a promising strategy for the feed industry to incorporate cottonseed meal into fish feed formulations.

Microbially conjugated bile salts found in human bile activate the bile salt receptors TGR5 and FXR

BACKGROUND

Bile salts of hepatic and microbial origin mediate interorgan cross talk in the gut-liver axis. Here, we assessed whether the newly discovered class of microbial bile salt conjugates (MBSCs) activate the main host bile salt receptors (Takeda G protein-coupled receptor 5 [TGR5] and farnesoid X receptor [FXR]) and enter the human systemic and enterohepatic circulation.

METHODS

N-amidates of (chenodeoxy) cholic acid and leucine, tyrosine, and phenylalanine were synthesized. Receptor activation was studied in cell-free and cell-based assays. MBSCs were quantified in mesenteric and portal blood and bile of patients undergoing pancreatic surgery.

RESULTS

MBSCs were activating ligands of TGR5 as evidenced by recruitment of Gsα protein, activation of a cAMP-driven reporter, and diminution of lipopolysaccharide-induced cytokine release from macrophages. Intestine-enriched and liver-enriched FXR isoforms were both activated by MBSCs, provided that a bile salt importer was present. The affinity of MBSCs for TGR5 and FXR was not superior to host-derived bile salt conjugates. Individual MBSCs were generally not detected (ie, < 2.5 nmol/L) in human mesenteric or portal blood, but Leu-variant and Phe-variant were readily measurable in bile, where MBSCs comprised up to 213 ppm of biliary bile salts.

CONCLUSIONS

MBSCs activate the cell surface receptor TGR5 and the transcription factor FXR and are substrates for intestinal (apical sodium-dependent bile acid transporter) and hepatic (Na+ taurocholate co-transporting protein) transporters. Their entry into the human circulation is, however, nonsubstantial. Given low systemic levels and a surplus of other equipotent bile salt species, the studied MBSCs are unlikely to have an impact on enterohepatic TGR5/FXR signaling in humans. The origin and function of biliary MBSCs remain to be determined.

The pathophysiology of MASLD: an immunometabolic perspective

INTRODUCTION

Metabolic-associated liver diseases have emerged pandemically across the globe and are clinically related to metabolic disorders such as obesity and type 2 diabetes. The new nomenclature and definition (i.e. metabolic dysfunction-associated steatotic liver disease - MASLD; metabolic dysfunction-associated steatohepatitis - MASH) reflect the nature of these complex systemic disorders, which are characterized by inflammation, gut dysbiosis and metabolic dysregulation. In this review, we summarize recent advantages in understanding the pathophysiology of MASLD, which we parallel to emerging therapeutic concepts.

AREAS COVERED

We summarize the pathophysiologic concepts of MASLD and its transition to MASH and subsequent advanced sequelae of diseases. Furthermore, we highlight how dietary constituents, microbes and associated metabolites, metabolic perturbations, and immune dysregulation fuel lipotoxicity, hepatic inflammation, liver injury, insulin resistance, and systemic inflammation. Deciphering the intricate pathophysiologic processes that contribute to the development and progression of MASLD is essential to develop targeted therapeutic approaches to combat this escalating burden for health-care systems.

EXPERT OPINION

The rapidly increasing prevalence of metabolic dysfunction-associated steatotic liver disease challenges health-care systems worldwide. Understanding pathophysiologic traits is crucial to improve the prevention and treatment of this disorder and to slow progression into advanced sequelae such as cirrhosis and hepatocellular carcinoma.

Reducing the harms of alcohol: nutritional interventions and functional alcohol alternatives

The health risks and harm associated with regular alcohol consumption are well documented. In a recent WHO statement published in The Lancet Public Health alcohol consumption has been estimated to contribute worldwide to 3 million deaths in 2016 while also being responsible for 5·1% of the global burden of disease and injury. The total elimination of alcohol consumption, which has been long imbedded in human culture and society, is not practical and prohibition policies have proved historically ineffective. However, valuable strategies to reduce alcohol harms are already available and improved alternative approaches are currently being developed. Here, we will review and discuss recent advances on two main types of approaches, that is nutritional interventions and functional alcohol alternatives.

Short-chain fatty acids in nonalcoholic fatty liver disease: New prospects for short-chain fatty acids as therapeutic targets

Nonalcoholic fatty liver disease (NAFLD) is a stress-induced liver injury related to heredity, environmental exposure and the gut microbiome metabolism. Short-chain fatty acids (SCFAs), the metabolites of gut microbiota (GM), participate in the regulation of hepatic steatosis and inflammation through the gut-liver axis, which play an important role in the alleviation of NAFLD. However, little progress has been made in systematically elucidating the mechanism of how SCFAs improve NAFLD, especially the epigenetic mechanisms and the potential therapeutic application as clinical treatment for NAFLD. Herein, we adopted PubMed and Medline to search relevant keywords such as 'SCFAs', 'NAFLD', 'gut microbiota', 'Epigenetic', 'diet', and 'prebiotic effect' to review the latest research on SCFAs in NAFLD up to November 2023. In this review, firstly, we specifically discussed the production and function of SCFAs, as well as their crosstalk coordination in the gut liver axis. Secondly, we provided an updated summary and intensive discussion of how SCFAs affect hepatic steatosis to alleviate NAFLD from the perspective of genetic and epigenetic. Thirdly, we paid attention to the pharmacological and physiological characteristics of SCFAs, and proposed a promising future direction to adopt SCFAs alone or in combination with prebiotics and related clinical drugs to prevent and treat NAFLD. Together, this review aimed to elucidate the function of SCFAs and provide new insights to the prospects of SCFAs as a therapeutic target for NAFLD.

Altered metabolome and microbiome associated with compromised intestinal barrier induced hepatic lipid metabolic disorder in mice after subacute and subchronic ozone exposure

Exposure to ozone has been associated with metabolic disorders in humans, but the underlying mechanism remains unclear. In this study, the role of the gut-liver axis and the potential mechanism behind the metabolic disorder were investigated by histological examination, microbiome and metabolome approaches in mice during the subacute (4-week) and subchronic (12-week) exposure to 0.5 ppm and 2.5 ppm ozone. Ozone exposure resulted in slowed weight gain and reduced hepatic lipid contents in a dose-dependent manner. After exposure to ozone, the number of intestinal goblet cells decreased, while the number of tuft cells increased. Tight junction protein zonula occludens-1 (ZO-1) was significantly downregulated, and the apoptosis of epithelial cells increased with compensatory proliferation, indicating a compromised chemical and physical layer of the intestinal barrier. The hepatic and cecal metabolic profiles were altered, primarily related to lipid metabolism and oxidative stress. The abundance of Muribaculaceae increased dose-dependently in both colon and cecum, and was associated with the decrease of metabolites such as bile acids, betaine, and L-carnitine, which subsequently disrupted the intestinal barrier and lipid metabolism. Overall, this study found that subacute and subchronic exposure to ozone induced metabolic disorder via disturbing the gut-liver axis, especially the intestinal barrier. These findings provide new mechanistic understanding of the health risks associated with environmental ozone exposure and other oxidative stressors.

Empagliflozin attenuates liver fibrosis in high-fat diet/streptozotocin-induced mice by modulating gut microbiota

The effects of SGLT2 inhibitors on hepatic fibrosis in diabetes remain unclear. This study aimed to investigate the effects of empagliflozin on liver fibrosis in high-fat diet/streptozotocin-induced mice and the correlation with gut microbiota. After the application of empagliflozin for 6 weeks, we performed oral glucose tolerance and intraperitoneal insulin tolerance tests to assess glucose tolerance and insulin resistance, and stained liver sections to evaluate histochemical and hepatic pathological markers of liver fibrosis. Moreover, 16S rRNA amplicon sequencing was performed on stool samples to explore changes in the composition of intestinal bacteria. We finally analysed the correlation between gut microbiome and liver fibrosis scores or indicators of glucose metabolism. The results showed that empagliflozin intervention improved glucose metabolism and liver function with reduced liver fibrosis, which might be related to changes in intestinal microbiota. In addition, the abundance of intestinal probiotic Lactobacillus increased, while Ruminococcus and Adlercreutzia decreased after empagliflozin treatment, and correlation analysis showed that the changes in microbiota were positively correlated with liver fibrosis and glucose metabolism. Overall, considering the contribution of the gut microbiota in metabolism, empagliflozin might have improved the beneficial balance of intestinal bacteria composition. The present study provides evidence and indicates the involvement of the gut-liver axis by SGLT2 inhibitors in T2DM with liver fibrosis.

Fecal microbiota transplantation for treatment of non-alcoholic fatty liver disease: Mechanism, clinical evidence, and prospect

The population of non-alcoholic fatty liver disease (NAFLD) patients along with relevant advanced liver disease is projected to continue growing, because currently no medications are approved for treatment. Fecal microbiota transplantation (FMT) is believed a novel and promising therapeutic approach based on the concept of the gut-liver axis in liver disease. There has been an increase in the number of pre-clinical and clinical studies evaluating FMT in NAFLD treatment, however, existing findings diverge on its effects. Herein, we briefly summarized the mechanism of FMT for NAFLD treatment, reviewed randomized controlled trials for evaluating its efficacy in NAFLD, and proposed the prospect of future trials on FMT.

In Vitro Lactic Acid Bacteria Anti-Hepatitis B Virus (HBV) Effect and Modulation of the Intestinal Microbiota in Fecal Cultures from HBV-Associated Hepatocellular Carcinoma Patients

Hepatocellular carcinoma (HCC), being ranked as the top fifth most prevalent cancer globally, poses a significant health challenge, with a considerable mortality rate. Hepatitis B virus (HBV) infection stands as the primary factor contributing to HCC, presenting substantial challenges in its treatment. This study aimed to identify lactic acid bacteria (LAB) with anti-HBV properties and evaluate their impact on the intestinal flora in HBV-associated HCC. Initially, two LAB strains, Levilactobacillus brevis SR52-2 (L. brevis SR52-2) and LeviLactobacillus delbrueckii subsp. bulgaicus Q80 (L. delbrueckii Q80), exhibiting anti-HBV effects, were screened in vitro from a pool of 498 LAB strains through cell experiments, with extracellular expression levels of 0.58 ± 0.05 and 0.65 ± 0.03, respectively. These strains exhibited the capability of inhibiting the expression of HBeAg and HBsAg. Subsequent in vitro fermentation, conducted under simulated anaerobic conditions mimicking the colon environment, revealed a decrease in pH levels in both the health control (HC) and HCC groups influenced by LAB, with a more pronounced effect observed in the HC group. Additionally, the density of total short-chain fatty acids (SCFAs) significantly increased (p < 0.05) in the HCC group. Analysis of 16S rRNA highlighted differences in the gut microbiota (GM) community structure in cultures treated with L. brevis SR52-2 and L. delbrueckii Q80. Fecal microflora in normal samples exhibited greater diversity compared to HBV-HCC samples. The HCC group treated with LAB showed a significant increase in the abundance of the phyla Firmicutes, Bacteroidetes and Actinobacteria, while Proteobacteria significantly decreased compared to the untreated HCC group after 48 h. In conclusion, the findings indicate that LAB, specifically L. brevis SR52-2 and L. delbrueckii Q80, possessing antiviral properties, contribute to an improvement in gastrointestinal health.

Serum/Plasma Proteome in Non-Malignant Liver Disease

The liver is the central metabolic organ and produces 85-90% of the proteins found in plasma. Accordingly, the plasma proteome is an attractive source of liver disease biomarkers that reflects the different cell types present in this organ, as well as the processes such as responses to acute and chronic injury or the formation of an extracellular matrix. In the first part, we summarize the biomarkers routinely used in clinical evaluations and their biological relevance in the different stages of non-malignant liver disease. Later, we describe the current proteomic approaches, including mass spectrometry and affinity-based techniques, that allow a more comprehensive assessment of the liver function but also require complex data processing. The many approaches of analysis and interpretation and their potential caveats are delineated. While these advances hold the promise to transform our understanding of liver diseases and support the development and validation of new liver-related drugs, an interdisciplinary collaboration is needed.

Bacteria-based drug delivery for treating non-oncological diseases

Bacteria inhabit all over the human body, especially the skin, gastrointestinal tract, respiratory tract, urogenital tract, as well as specific lesion sites, such as wound and tumor. By leveraging their distinctive attributes including rapid proliferation, inherent abilities to colonize various biointerfaces in vivo and produce diverse biomolecules, and the flexibility to be functionalized via genetic engineering or surface modification, bacteria have been widely developed as living therapeutic agents, showing promising potential to make a great impact on the exploration of advanced drug delivery systems. In this review, we present an overview of bacteria-based drug delivery and its applications in treating non-oncological diseases. We systematically summarize the physiological positions where living bacterial therapeutic agents can be delivered to, including the skin, gastrointestinal tract, respiratory tract, and female genital tract. We discuss the success of using bacteria-based drug delivery systems in the treatment of diseases that occur in specific locations, such as skin wound healing/infection, inflammatory bowel disease, respiratory diseases, and vaginitis. We also discuss the advantages as well as the limitations of these living therapeutics and bacteria-based drug delivery, highlighting the key points that need to be considered for further translation. This review article may provide unique insights for designing next-generation bacteria-based therapeutics and developing advanced drug delivery systems.

Microbiota-gut-liver-brain axis and hepatic encephalopathy

Hepatic encephalopathy (HE) is a clinical manifestation of neurological and psychiatric abnormalities that are caused by complications of liver dysfunction including hyperammonemia, hyperuricemia, and portal hypertension. Accumulating evidence suggests that HE could be reversed through therapeutic modifications of gut microbiota. Multiple preclinical and clinical studies have indicated that gut microbiome affects the physiological function of the liver, such as the regulation of metabolism, secretion, and immunity, through the gut-liver crosstalk. In addition, gut microbiota also influences the brain through the gut-brain crosstalk, altering its physiological functions including the regulation of the immune, neuroendocrine, and vagal pathways. Thus, key molecules that are involved in the microbiota-gut-liver-brain axis might be able to serve as clinical biomarkers for early diagnosis of HE, and could be effective therapeutic targets for clinical interventions. In this review, we summarize the pathophysiology of HE and further propose approaches modulating the microbiota-gut-liver-brain axis in order to provide a comprehensive understanding of the prevention and potential clinical treatment for HE with a microbiota-targeted therapy.

The supplementation of the multi-strain probiotics WHHPRO™ alleviates high-fat diet-induced metabolic symptoms in rats via gut-liver axis

Metabolic syndrome (MS) has emerged as one of the major global health concerns, accompanied by a series of related complications, such as obesity and type-2 diabetes. The gut-liver axis (GLA) is a bidirectional communication between the gut and the liver. The GLA alterations have been revealed to be closely associated with the development of MS. Probiotics within Lactobacillus and Bifidobacterium confer beneficial effects on improving MS symptoms. WHHPRO™ is a mixture of four probiotic strains, with potential MS-improving abilities. This study aimed to investigate the effects of WHHPRO™ on MS symptoms using a high-fat diet (HFD) rat model. Oral administration of WHHPRO™ for 12 weeks improved glucose tolerance, blood lipid, body weight, and liver index in HFD rats. WHHPRO™ shaped the gut microbiome composition by increasing the abundance of Lactobacillus and Akkermansia and normalized the reduced SCFA levels in HFD rats. Besides, WHHPRO™ modulated the fecal bile acids (BAs) profile, with decreased levels of T-b-MCA and 12-KDCA and increased levels of LCA and ILCA. Meanwhile, WHHPRO™ increased total unconjugated BAs in feces and liver and reduced the accumulation of total hepatic BA pool size in HFD rats. Moreover, WHHPRO™ reversed the expression of genes associated with impaired BA metabolism signaling in the ileum and liver. Our findings suggest that WHHPRO™ exerted beneficial effects on improving MS symptoms, involving the modulation of the gut microbiome composition, SCFAs, and the FXR-FGF15 signaling along the GLA. Supplementation of WHHPRO™ may serve as a novel strategy for improving MS symptoms.

Mechanisms and functions of intestinal vascular specialization

The intestinal vasculature has been studied for the last 100 years, and its essential role in absorbing and distributing ingested nutrients is well known. Recently, fascinating new insights into the organization, molecular mechanisms, and functions of intestinal vessels have emerged. These include maintenance of intestinal epithelial cell function, coping with microbiota-induced inflammatory pressure, recruiting gut-specific immune cells, and crosstalk with other organs. Intestinal function is also regulated at the systemic and cellular levels, such that the postprandial hyperemic response can direct up to 30% of systemic blood to gut vessels, while micron-sized endothelial cell fenestrations are necessary for nutrient uptake. In this review, we will highlight past discoveries made about intestinal vasculature in the context of new findings of molecular mechanisms underpinning gut function. Such comprehensive understanding of the system will pave the way to breakthroughs in nutrient uptake optimization, drug delivery efficiency, and treatment of human diseases.

Ileal inflammation is reduced due to treatment with a metalloprotease from BmooMP-α-I snake venom in an experimental model of Toxoplasma gondii infection

The selection process for advanced therapies in patients with inflammatory bowel diseases (IBDs) must prioritize safety, especially when considering new biologic agents or oral molecule modulators. In C57BL/6 mice, oral infection with Toxoplasma gondii induces intestinal inflammation through excessive tumor necrosis factor (TNF) production, making TNF neutralization a potential therapeutic intervention. Considering this, the present study aimed to evaluate the therapeutic effects of BmooMP-α-I, a snake venom metalloprotease isolated from Bothrops moojeni, which could promote TNF hydrolysis, in treating T. gondii-induced ileitis. The results showed that C57BL/6 mice orally infected with 50 cysts of T. gondii from the Me49 strain and treated with BmooMP-α-I exhibited prolonged survival and improved morbidity scores. Additionally, the treatment ameliorated both the macroscopic and microscopic aspects of the intestine, reduced macrophage influx, and decreased the production of inflammatory mediators by mesenteric lymph node cells. These findings provide compelling experimental evidence supporting the ability of BmooMP-α-I to alleviate ileal inflammation. Considering that the currently available therapeutic protocols are not completely effective and often result in side effects, the exploration of alternative strategies involving novel therapeutic agents, as demonstrated in this study, has the potential to significantly enhance the quality of life for patients suffering from inflammatory bowel diseases.

Polysaccharide from walnut green husk alleviates liver inflammation and gluconeogenesis dysfunction by altering gut microbiota in ochratoxin A-induced mice

Walnut green husk polysaccharides (WGP) are isolated from the walnut green husk with a mean molecular weight of 12.77 kDa. The structural characterization revealed by methylation and NMR analysis indicated that WGP might consist of →4-α-D-Galp-(1→, α-D-Galp (1→, and →2)-α-L-Rhap-(1→. Previous studies have been demonstrated that WGP effectively prevented liver injury and modulated gut microbiota in high fructose-treated mice and high fat diet-treated rats. In this study, we found for the first time that WGP presenting outstanding protective effects on liver inflammation and gluconeogenesis dysfunction induced by ochratoxin A (OTA) in mice. Firstly, WGP decreased oxidative stress, down-regulated the expression of inflammatory factors and inhibited the TLR4/p65/IκBα pathway in the liver. Then, WGP reversed OTA-induced lower phosphoenolpyruvate carboxyl kinase (PEPCK), and glucose 6-phosphatase (G6PC) activities in the liver. Furthermore, WGP increased the diversity of gut microbiota and the abundance of beneficial bacteria, especially Lactobacillus and Akkermansia. Importantly, the results of fecal microbiota transplantation (FMT) experiment further confirmed that gut microbiota involved in the protective effects of WGP on liver damage induced by OTA. Our results indicated that the protective effect of WGP on liver inflammation and gluconeogenesis dysfunction caused by OTA may be due to the regulation of gut microbiota.

Akkermansia muciniphila and its outer membrane protein Amuc_1100 prevent high-fat diet-induced nonalcoholic fatty liver disease in mice

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. A. muciniphila and its outer membrane protein Amuc_1100 ameliorate metabolic disorders, enteritis, depression, and other diseases in mice. The NAFLD mouse model was established by feeding a high-fat diet (HFD) for 10 weeks. To assess the effect of A. muciniphila and Amuc_1100 on NAFLD, we used atorvastatin, a common lipid-lowering drug, as a positive control. A. muciniphila and Amuc_1100 significantly reduced body weight and serum ALT and AST levels, and improved serum lipid levels in NAFLD mice, which had similar effects to Ator. In addition, A. muciniphila and Amuc_1100 decreased the concentration of LPS in the serum and upregulated the mRNA expression of the colonic tight junction proteins. In the liver, A. muciniphila and Amuc_1100 significantly reduced the mRNA expression levels of nodular receptor protein 3 (NLRP3) and Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB), and the protein and mRNA expression levels inflammatory cytokines. At the genus level, Amuc_1100 treatment significantly reduced the abundance of Coriobacteriaceae_UCG-002 produced by the HFD. The abundances of Blautia, norank_f__Ruminococcaceae, Lachnoclostridium, GCA-900066575 and Lachnospiraceae_UCG-006 increased dramatically. Together, A. muciniphila and Amuc_1100 alleviate HFD-induced NAFLD by acting on the gut-liver axis and regulating gut microbes.

Gut Microbiota and Bacterial Translocation in the Pathogenesis of Liver Fibrosis

Cirrhosis is the end result of liver fibrosis in chronic liver diseases. Studying the mechanisms of its development and developing measures to slow down and regress it based on this knowledge seem to be important tasks for medicine. Currently, disorders of the gut-liver axis have great importance in the pathogenesis of cirrhosis. However, gut dysbiosis, which manifests as increased proportions in the gut microbiota of Bacilli and Proteobacteria that are capable of bacterial translocation and a decreased proportion of Clostridia that strengthen the intestinal barrier, occurs even at the pre-cirrhotic stage of chronic liver disease. This leads to the development of bacterial translocation, a process by which those microbes enter the blood of the portal vein and then the liver tissue, where they activate Kupffer cells through Toll-like receptor 4. In response, the Kupffer cells produce profibrogenic cytokines, which activate hepatic stellate cells, stimulating their transformation into myofibroblasts that produce collagen and other elements of the extracellular matrix. Blocking bacterial translocation with antibiotics, probiotics, synbiotics, and other methods could slow down the progression of liver fibrosis. This was shown in a number of animal models but requires further verification in long-term randomized controlled trials with humans.

Genetic predisposition of the gastrointestinal microbiome and primary biliary cholangitis: a bi-directional, two-sample Mendelian randomization analysis

Background

The gut-liver axis indicates a close relationship between the gastrointestinal microbiome (GM) and primary biliary cholangitis (PBC). However, the causality of this relationship remains unknown. This study investigates the causal relationship between the GM and PBC using a bidirectional, two-sample Mendelian randomization (MR) analysis.

Methods

Genome-wide association data for GM and PBC were obtained from public databases. The inverse-variance weighted method was the primary method used for MR analysis. Sensitivity analyses were conducted to assess the stability of the MR results. A reverse MR analysis was performed to investigate the possibility of reverse causality.

Results

Three bacterial taxa were found to be causally related to PBC. Class Coriobacteriia (odds ratio (OR) = 2.18, 95% confidence interval (CI): 1.295-3.661, P< 0.05) and order Coriobacteriales (OR = 2.18, 95% CI: 1.295-3.661, P<0.05) were associated with a higher risk of PBC. Class Deltaproteobacteria (OR = 0.52, 95% CI: 0.362-0.742, P< 0.05) had a protective effect on PBC. There was no evidence of reverse causality between PBC and the identified bacterial taxa.

Conclusion

Previously unrecognized taxa that may be involved in the pathogenesis of PBC were identified in this study, confirming the causality between the GM and PBC. These results provide novel microbial targets for the prevention and treatment of PBC.

Tissue-resident and innate-like T cells in patients with advanced chronic liver disease

Chronic liver disease results from the orchestrated interplay of components of innate and adaptive immunity in response to liver tissue damage. Recruitment, positioning, and activation of immune cells can contribute to hepatic cell death, inflammation, and fibrogenesis. With disease progression and increasing portal pressure, repeated translocation of bacterial components from the intestinal lumen through the epithelial and vascular barriers leads to persistent mucosal, hepatic, and systemic inflammation which contributes to tissue damage, immune dysfunction, and microbial infection. It is increasingly recognised that innate-like and adaptive T-cell subsets located in the liver, mucosal surfaces, and body cavities play a critical role in the progression of advanced liver disease and inflammatory complications of cirrhosis. Mucosal-associated invariant T cells, natural killer T cells, γδ T cells, and tissue-resident memory T cells in the gut, liver, and ascitic fluid share certain characteristic features, which include that they recognise microbial products, tissue alarmins, cytokines, and stress ligands in tissues, and perform effector functions in chronic liver disease. This review highlights recent advances in the comprehension of human tissue-resident and unconventional T-cell populations and discusses the mechanisms by which they contribute to inflammation, fibrosis, immunosuppression, and antimicrobial surveillance in patients with cirrhosis. Understanding the complex interactions of immune cells in different compartments and their contribution to disease progression will provide further insights for effective diagnostic interventions and novel immunomodulatory strategies in patients with advanced chronic liver disease.

Advances in Endohepatology

Over the past decade, the number of endoscopic procedures relevant to patients with liver disease not only increased but also altered and expanded in terms of indications and applications. "Endohepatology" refers to the integration of advanced endoscopy within the practice of hepatology with endoscopic ultrasound as one of the main pillars. Current applications under the umbrella of endohepatology focus on advanced diagnostics and oncological, vascular, and metabolic interventions. These involve, among others, endoscopic ultrasound (EUS)-guided liver biopsy, EUS-guided portal pressure gradient measurement, and EUS-guided coil and glue embolization of gastric varices. In addition to its conceptually attractive technical and innovative characteristics, endohepatology is also an appealing practical option for daily practice because it can be offered as a "one-stop clinic" intervention where comprehensive endoscopic diagnostic and/or therapeutic testing is performed in a single outpatient visit. In this review, we will discuss current trends and future developments within endohepatology and the remaining hurdles to overcome.

A Pectic Polysaccharide from Codonopsis pilosula Alleviates Inflammatory Response and Oxidative Stress of Aging Mice via Modulating Intestinal Microbiota-Related Gut-Liver Axis

Aging is a biological process that leads to the progressive deterioration and loss of physiological functions in the human body and results in an increase in morbidity and mortality, and aging-related disease is a major global problem that poses a serious threat to public health. Polysaccharides have been shown to delay aging by reducing oxidative damage, suppressing inflammatory responses, and modulating intestinal microbiota. Our previous studies have shown that polysaccharide CPP-1 extracted from the root of Codonopsis pilosula possesses noticeable anti-oxidant activity in vitro. Thus, in our study, we tested the anti-aging effect of CPP-1 in naturally aging mice (in vivo). Eighteen C57/BL mice (48-week-old, male) were divided into a control group, high-dose CPP-1 group (20 mg/mL), and low-dose CPP-1 group (10 mg/mL). We discovered that CPP-1 can exert a reparative effect on aging stress in the intestine and liver, including alleviating inflammation and oxidative damage. We revealed that CPP-1 supplementation improved the intestinal microbiota composition and repaired the intestinal barrier in the gut. Furthermore, CPP-1 was proved to modulate lipid metabolism and repair hepatocyte injury in the liver by influencing the enterohepatic axis associated with the intestinal microbiota. Therefore, we concluded that CPP-1 prevents and alleviates oxidative stress and inflammatory responses in the intestine and liver of aging mice by modulating the intestinal microbiota-related gut-liver axis to delay aging.

Gut microbiota metabolite TMAO promoted lipid deposition and fibrosis process via KRT17 in fatty liver cells in vitro

Non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide but still lacks specific treatment modalities. The gut microbiota and its metabolites have been shown to be intimately involved in NAFLD development, participating in and regulating disease progression. Trimethylamine N-oxide (TMAO), a metabolite highly dependent on the gut microbiota, has been shown to play deleterious regulatory roles in cardiovascular disease, but the relationship between it and NAFLD lacks validation from basic experiments. This research applied TMAO intervention by constructing fatty liver cell models in vitro to observe its effect on fatty liver cells and potential key genes and performed siRNA interference on the gene to verify the action. The results showed that TMAO intervention promoted the appearance of more red-stained lipid droplets in Oil-red O staining results, increased triglyceride (TG) levels and increased mRNA levels of liver fibrosis-related genes, and also identified one of the key genes, keratin17 (KRT17) via transcriptomics. Following the reduction in its expression level, under the same treatment, there were decreased red-stained lipid droplets, decreased TG levels, decreased indicators of impaired liver function as well as decreased mRNA levels of liver fibrosis-related genes. In conclusion, the gut microbiota metabolite TMAO could promote lipid deposition and fibrosis process via the KRT17 gene in fatty liver cells in vitro.