Bile acid receptor TGR5 overexpression is associated with decreased intestinal mucosal injury and epithelial cell proliferation in obstructive jaundice

Non-12α-Hydroxylated Bile Acids Improve Piglet Growth Performance by Improving Intestinal Flora, Promoting Intestinal Development and Bile Acid Synthesis

As an emulsifier and bioactive substance, bile acids (BAs) participate in the absorption of nutrients and in various physiological processes. The objective of this experiment was to investigate the effects of non-12α-hydroxylated BAs (including hyocholic acid, hyodeoxycholic acid and chenodeoxycholic acid, from now on referred to as NBAs) on growth performance, BAs metabolism and the intestinal flora of piglets. The experiment included four groups, with eight piglets per group. The four groups of pigs were fed 0, 60, 120 and 180 mg/kg of NBAs, respectively. The results show that adding NBAs significantly increased the final weight (FW), average daily feed intake (ADFI), average daily gain (ADG), and digestibility of crude fat (EE) and organic matter (OM) in piglets (p < 0.05). Adding NBAs significantly increased the villus height (VH) of the jejunum and ileum (p < 0.05). In addition, NBAs supplementation increased the content of urea nitrogen (BUN) and creatinine (CREA) as well as the ratio of urea nitrogen to creatinine (BUN/CREA) in serum (p < 0.05). Adding NBAs can affect the genes related to BAs enterohepatic circulation. Specifically, adding NBAs significantly decreased the relative mRNA abundance of FXR in the liver (p < 0.05), significantly increased the relative mRNA abundance of CYP27A1 (p < 0.05), and significantly increased the relative mRNA abundance of NTCP (p < 0.05). Adding NBAs also significantly decreased the relative mRNA abundance of FXR in the ileum (p < 0.05). In the full-length 16S rDNA sequencing analysis, ten biomarkers were found from the gate to the species level. NBAs mainly enriched Lactobacillus_Johnsonii and decreased the abundance of Streptococcus_alactolyticus. Short-chain fatty acids (SCFAs) content in the colon was significantly increased (p < 0.05). These results indicate that NBAs supplementation can improve the growth performance of piglets, promote the development of the bile acid replacement pathway and improve intestinal flora.

Interactions between gut microbiota and polyphenols: A mechanistic and metabolomic review

BACKGROUND

Polyphenols are a class of naturally sourced compounds with widespread distribution and an extensive array of bioactivities. However, due to their complex constituents and weak absorption, a convincing explanation for their remarkable bioactivity remains elusive for a long time. In recent years, interaction with gut microbiota is hypothesized to be a reasonable explanation of the potential mechanisms for natural compounds especially polyphenols.

OBJECTIVES

This review aims to present a persuasive explanation for the contradiction between the limited bioavailability and the remarkable bioactivities of polyphenols by examining their interactions with gut microbiota.

METHODS

We assessed literatures published before April 10, 2023, from several databases, including Scopus, PubMed, Google Scholar, and Web of Science. The keywords used include "polyphenols", "gut microbiota", "short-chain fatty acids", "bile acids", "trimethylamine N-oxide", "lipopolysaccharides" "tryptophan", "dopamine", "intestinal barrier", "central nervous system", "lung", "anthocyanin", "proanthocyanidin", "baicalein", "caffeic acid", "curcumin", "epigallocatechin-3-gallate", "ferulic acid", "genistein", "kaempferol", "luteolin", "myricetin", "naringenin", "procyanidins", "protocatechuic acid", "pterostilbene", "quercetin", "resveratrol", etc. RESULTS: The review first demonstrates that polyphenols significantly alter gut microbiota diversity (α- and β-diversity) and the abundance of specific microorganisms. Polyphenols either promote or inhibit microorganisms, with various factors influencing their effects, such as dosage, treatment duration, and chemical structure of polyphenols. Furthermore, the review reveals that polyphenols regulate several gut microbiota metabolites, including short-chain fatty acids, dopamine, trimethylamine N-oxide, bile acids, and lipopolysaccharides. Polyphenols affect these metabolites by altering gut microbiota composition, modifying microbial enzyme activity, and other potential mechanisms. The changed microbial metabolites induced by polyphenols subsequently trigger host responses in various ways, such as acting as intestinal acid-base homeostasis regulators and activating on specific target receptors. Additionally, polyphenols are transformed into microbial derivatives by gut microbiota and these polyphenols' microbial derivatives have many potential advantages (e.g., increased bioactivity, improved absorption). Lastly, the review shows polyphenols maintain intestinal barrier, central nervous system, and lung function homeostasis by regulating gut microbiota.

CONCLUSION

The interaction between polyphenols and gut microbiota provides a credible explanation for the exceptional bioactivities of polyphenols. This review aids our understanding of the underlying mechanisms behind the bioactivity of polyphenols.

A novel ameliorated rat model of reversible obstructive jaundice

Obstructive jaundice is a common clinical symptom generally caused by bile duct stones, inflammatory hyperplasia, and tumors. It is characterized by hyperbilirubinemia and may trigger a variety of complications such as hypotension, kidney injury, endotoxemia, multiple organ dysfunction syndrome, and even death (Pavlidis and Pavlidis, 2018; Liu et al., 2021). Relieving bile duct obstruction and providing adequate drainage have been considered as the most effective therapies for obstructive jaundice. However, it has not yet been established whether it is beneficial to treat affected patients by pre-operative biliary drainage (Blacker et al., 2021). Moreover, the pathophysiological changes or mechanisms associated with the reversal of organ function following the relief of bile-duct obstruction are unclear (Huang et al., 2004). Therefore, it is necessary to establish an experimental model of reversible obstructive jaundice to simulate biliary drainage in clinical practice.

The gut microbiome and hypertension

A large body of evidence has emerged in the past decade supporting a role for the gut microbiome in the regulation of blood pressure. The field has moved from association to causation in the last 5 years, with studies that have used germ-free animals, antibiotic treatments and direct supplementation with microbial metabolites. The gut microbiome can regulate blood pressure through several mechanisms, including through gut dysbiosis-induced changes in microbiome-associated gene pathways in the host. Microbiota-derived metabolites are either beneficial (for example, short-chain fatty acids and indole-3-lactic acid) or detrimental (for example, trimethylamine N-oxide), and can activate several downstream signalling pathways via G protein-coupled receptors or through direct immune cell activation. Moreover, dysbiosis-associated breakdown of the gut epithelial barrier can elicit systemic inflammation and disrupt intestinal mechanotransduction. These alterations activate mechanisms that are traditionally associated with blood pressure regulation, such as the renin-angiotensin-aldosterone system, the autonomic nervous system, and the immune system. Several methodological and technological challenges remain in gut microbiome research, and the solutions involve minimizing confounding factors, establishing causality and acting globally to improve sample diversity. New clinical trials, precision microbiome medicine and computational methods such as Mendelian randomization have the potential to enable leveraging of the microbiome for translational applications to lower blood pressure.

Preventive Effects of l-Glutamine on High-Fat Diet-Induced Metabolic Disorders Linking with Regulation of Intestinal Barrier Integrity, Hepatic Lipid Metabolism, and Gut Microbiota in Rats

The present study was conducted to investigate the effects of l-glutamine (Gln) on a high-fat diet (HFD)-induced lipid metabolic abnormality and explore its possible mechanisms. The results demonstrated that Gln administration reduced body weight, improved serum lipids, and decreased glucose tolerance in HFD-fed rats. Meanwhile, Gln administration alleviated liver injury, reduced the hepatic inflammatory response by inhibiting NLRP3 inflammasome activation, and decreased hepatic lipid accumulation by promoting VLDL secretion and fatty acid β-oxidation, as well as reduced bile acid synthesis by activating hepatic and ileal FXR in HFD-fed rats. Moreover, Gln administration restored HFD-induced intestinal barrier dysfunction, promoted intestinal fat absorption, suppressed intestinal inflammation, and also reshaped the gut microbiota composition in HFD-fed rats by downregulating the abundance of potential pathogens Escherichia-Shigella and upregulating the abundance of beneficial bacteria such as Akkermansia. To conclude, the present results showed that Gln may be a potential option for preventing HFD-induced metabolic disorders via the gut-liver axis.

Bile acids and salt-sensitive hypertension: a role of the gut-liver axis

Salt-sensitivity of blood pressure (SSBP) affects 50% of the hypertensive and 25% of the normotensive populations. Importantly, SSBP is associated with increased risk for mortality in both populations independent of blood pressure. Despite its deleterious effects, the pathogenesis of SSBP is not fully understood. Emerging evidence suggests a novel role of bile acids in salt-sensitive hypertension and that they may play a crucial role in regulating inflammation and fluid volume homeostasis. Mechanistic evidence implicates alterations in the gut microbiome, the epithelial sodium channel (ENaC), the farnesoid X receptor, and the G protein-coupled bile acid receptor TGR5 in bile acid-mediated effects on cardiovascular function. The mechanistic interplay between excess dietary sodium-induced alterations in the gut microbiome and immune cell activation, bile acid signaling, and whether such interplay may contribute to the etiology of SSBP is still yet to be defined. The main goal of this review is to discuss the potential role of bile acids in the pathogenesis of cardiovascular disease with a focus on salt-sensitive hypertension.

Overview of the microbiota in the gut-liver axis in viral B and C hepatitis

Viral B and C hepatitis are a major current health issue, both diseases having a chronic damaging effect on the liver and its functions. Chronic liver disease can lead to even more severe and life-threatening conditions, such as liver cirrhosis and hepatocellular carcinoma. Recent years have uncovered an important interplay between the liver and the gut microbiome: the gut-liver axis. Hepatitis B and C infections often cause alterations in the gut microbiota by lowering the levels of ‘protective’ gut microorganisms and, by doing so, hinder the microbiota ability to boost the immune response. Treatments aimed at restoring the gut microbiota balance may provide a valuable addition to current practice therapies and may help limit the chronic changes observed in the liver of hepatitis B and C patients. This review aims to summarize the current knowledge on the anato-functional axis between the gut and liver and to highlight the influence that hepatitis B and C viruses have on the microbiota balance, as well as the influence of treatments aimed at restoring the gut microbiota on infected livers and disease progression.

Flaxseed Powder Attenuates Non-Alcoholic Steatohepatitis via Modulation of Gut Microbiota and Bile Acid Metabolism through Gut-Liver Axis

Non-alcoholic steatohepatitis (NASH) is gradually becoming one of the most common and health-endangering diseases; therefore, it is very important to prevent the occurrence of NASH and prevent simple non-alcoholic fatty liver (NAFL) from further developing into NASH. We fed mice a high-fat diet (HFD, 60% fat) for 14 weeks to induce NAFL and then fed different doses of flaxseed powder (low (10%), middle (20%), and high (30%)) to the mice for 28 weeks. After the animal experiment, we analyzed fecal bile acid (BA) profiles of the HFD mice, flaxseed-fed (FLA-fed) mice, and control mice with a normal diet (10% fat) using a targeted metabolomics approach, and we analyzed the gut microbiota at the same time. We also investigated the mechanistic role of BAs in NASH and identified whether the altered BAs strongly bind to colonic FXR or TGR5. In the present study, we found that 28-week FLA treatment notably alleviated NASH development in NAFL model mice fed with an HFD, and the beneficial effects may be attributed to the regulation of and improvement in the gut flora- and microbiota-related BAs, which then activate the intestinal FXR-FGF15 and TGR5-NF-κB pathways. Our data indicate that FLA might be a promising functional food for preventing NASH through regulating microbiomes and BAs.

Deep Insight Into Long Non-coding RNA and mRNA Transcriptome Profiling in HepG2 Cells Expressing Genotype IV Swine Hepatitis E Virus ORF3

Swine hepatitis E (swine HE) is a new type of zoonotic infectious disease caused by the swine hepatitis E virus (swine HEV). Open reading frame 3 (ORF3) is an important virulent protein of swine HEV, but its function still is mainly unclear. In this study, we generated adenoviruses ADV4-ORF3 and ADV4 negative control (ADV4-NC), which successfully mediated overexpression of enhanced green fluorescent protein (EGFP)-ORF3 and EGFP, respectively, in HepG2 cells. High-throughput sequencing was used to screen for differentially expressed long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs). The cis-target genes of lncRNAs were predicted, functional enrichment (Gene Ontology [GO] and Kyoto Encyclopedia of Genes and Genomes [KEGG]) was performed, and 12 lncRNAs with statistically significant different expressions (p ≤ 0.05 and q ≤ 1) were selected for further quantitative real-time reverse transcription (qRT-PCR) validation. In HepG2 cells, we identified 62 significantly differentially expressed genes (DEGs) (6,564 transcripts) and 319 lncRNAs (124 known lncRNAs and 195 novel lncRNAs) that were affected by ORF3, which were involved in systemic lupus erythematosus, Staphylococcus aureus infection, signaling pathways pluripotency regulation of stem cells, the peroxisome proliferator-activated receptor (PPAR) signaling pathway, and platinum drug resistance pathways. Cis-target gene prediction identified 45 lncRNAs corresponding to candidate mRNAs, among which eight were validated by qRT-PCR: LINC02476 (two transcripts), RAP2C-AS1, AC016526, AL139099, and ZNF337-AS1 (3 transcripts). Our results revealed that the lncRNA profile in host cells affected by ORF3, swine HEV ORF3, might affect the pentose and glucuronate interconversions and mediate the formation of obstructive jaundice by influencing bile secretion, which will help to determine the function of ORF3 and the infection mechanism and treatment of swine HE.

Role and significance of bile acid membrane receptor GPBAR1 in pathogenesis of obstructive jaundice

GPBAR1 is the first confirmed G protein coupled bile acid membrane receptor, which is widely expressed in the liver, gallbladder, kidney, intestine, and the nervous and cardiovascular systems. During the development of obstructive jaundice (OJ), GPBAR1 is activated by bile acid signal and mediates different signal transduction pathways, thus playing a corresponding role in the pathogenesis of OJ. GPBAR1 may be a potential therapeutic target for the treatment of OJ by controlling inflammation, regulating the function of bile duct epithelial barrier, inhibiting renal oxidative stress, and regulating intestinal mucosal barrier and intestinal flora, pruritus and sensory disturbance, and cardiovascular function. This article reviews the role and signficance of GPBAR1 in the pathogenesis of OJ.

The Protective Effect of Rosavin from Rhodiola rosea on Radiation-Induced Intestinal Injury

Bioactive constituents from Rhodiola rosea L. (RRL) exhibit multiple pharmacological effects on diverse diseases. However, whether they are suitable for the treatment of radiation-induced intestinal injury (RIII) remains unclear. This study aims to investigate their roles and mechanisms in the RIII rat model. The radioprotective effects of the four bioactive constituents of RRL (salidroside, herbacetin, rosavin and arbutin) were evaluated by the cell viability of irradiated IEC-6 cells. Intestinal tissues were collected for histological analysis, localized inflammation and oxidative stress assessments. Our work showed that salidroside, rosavin and arbutin improved the cell viability of the irradiated IEC-6 cells, with the highest improvement in 12.5 μM rosavin group. The rosavin treatment significantly improved survival rate and intestinal damage in irradiated rats by modulating the inflammatory response and oxidative stress. Our work indicated that rosavin may be the optimal constituent of RRL for RIII treatment, providing an attractive candidate for radioprotection.

Fushen Granule, A Traditional Chinese Medicine, ameliorates intestinal mucosal dysfunction in peritoneal dialysis rat model by regulating p38MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Fushen Granule (FSG) is a Chinese medicinal formular prepared in hospital to treat intestinal mucosal dysfunction induced by peritoneal dialysis (PD). However, the mechanisms of this formular has not been studied yet.

AIM OF THE STUDY

The present study was designed to investigate the effect of FSG against intestinal dysfunction during PD treatment and explore the potential mechanisms using a rat PD model.

METHODS AND METHODS

In the present study, the effect of FSG on improving intestinal mucosal architecture injury was intuitively shown by hematoxylin-eosin staining, the serum levels of DAO and D-lactate were measured to evaluate the intestinal permeability by the DAO Assay Kit and D-Lactic Acid ELISA Kit. The expression of the intestinal mucosal barrier related inflammation factor by real-time PCR. The main effective constituents of FSG were characterized by UPLC/Q-TOF analysis, and the targets and pathways of the constituents were predicted via TCMSP database and IPA. the activation of p38MAPK signaling pathway by western blotting.

RESULTS

HE staining results showed that FSG protected against intestinal mucosal injury in pathology in PD rats. FSG decreased the intestinal mucosal permeability by increasing the transepithelial electrical resistance (TER) level and decreasing the intestinal clearance of fluorescein-isothiocyanate dextran (FD4) and the level of D-lactate and diamine oxidase (DAO). FSG significantly decreased the expression of ICAM-1, IL-1β, iNOS and TNF-α, and further inhibited the activation of p38MAPK signaling pathway via down-regulating the expression of P-p38MAPK and up-regulating the expression of DUSP1, occludin, and ZO-1.

CONCLUSION

This study demonstrates that FSG ameliorated intestinal mucosal dysfunction in PD by decreasing expression of pro-inflammatory cytokines and inhibiting the activation of p38MAPK signaling pathway. The results provide a promising basis for the alternative medicine treatment of intestinal mucosal dysfunction in PD.

Hyodeoxycholic acid (HDCA) suppresses intestinal epithelial cell proliferation through FXR-PI3K/AKT pathway, accompanied by alteration of bile acids metabolism profiles induced by gut bacteria

Bile acids (BAs) have been implicated in regulation of intestinal epithelial signaling and function. This study aimed to investigate the effects of hyodeoxycholic acid (HDCA) on intestinal epithelial cell proliferation and explore the underlying mechanisms. IPEC-J2 cells and weaned piglets were treated with HDCA and the contributions of cellular signaling pathways, BAs metabolism profiles and gut bacteria were assessed. In vitro, HDCA suppressed IPEC-J2 proliferation via the BAs receptor FXR but not TGR5. In addition, HDCA inhibited the PI3K/AKT pathway, while knockdown of FXR or constitutive activation of AKT eliminated the inhibitory effects of HDCA, suggesting that FXR-dependent inhibition of PI3K/AKT pathway was involved in HDCA-suppressed IPEC-J2 proliferation. In vivo, dietary HDCA inhibited intestinal expression of proliferative markers and PI3K/AKT pathway in weaned piglets. Meanwhile, HDCA altered the BAs metabolism profiles, with decrease in primary BA and increase in total and secondary BAs in feces, and reduction of conjugated BAs in serum. Furthermore, HDCA increased abundance of the gut bacteria associated with BAs metabolism, and thereby induced BAs profiles alternation, which might indirectly contribute to HDCA-suppressed cell proliferation. Together, HDCA suppressed intestinal epithelial cell proliferation through FXR-PI3K/AKT signaling pathway, accompanied by alteration of BAs metabolism profiles induced by gut bacteria.

Increased hydrophilic plasma bile acids are correlated with protection from adiposity in skin-specific stearoyl-CoA desaturase-1 deficient mice

Stearoyl-CoA desaturase 1 (SCD1) catalyzes the rate limiting step in monounsaturated fatty acid synthesis by inserting a double bond at the delta-9 position of long-chain fatty acids. SCD1 converts stearate (18:0) to oleate (18:1n9) and palmitate (16:0) to palmitoleate (16:1n7), respectively. Mice with global and skin-specific deletion (SKO) of SCD1 exhibit increased whole body energy expenditure and protection against diet-induced adiposity, hepatic steatosis, insulin sensitivity and glucose intolerance. The mechanisms that link cutaneous lipid homeostasis with whole body energy balance are presently unknown. In this study, we reveal that SKO mice demonstrate increased skin surface free cholesterol, decreased circulating total cholesterol and increased taurine-conjugated and hydrophilic bile acids. Tauro-β-muricholic acid, which is a marker of extrahepatic bile acid synthesis, is significantly elevated in SKO plasma. Bile acid signaling through the bile acid-specific receptor TGR5 is known to be protective against obesity and metabolic disease; a phenotype that is similar to SKO mice. We therefore examined TGR5 expression and its downstream mediator, DIO2, in various tissues and found that both TGR5 and DIO2 expression were significantly increased in brown adipose tissue. In sum, we suggest that skin-derived bile acids are involved in the lean and metabolically healthy phenotype of SKO mice.

Update on Bile Acid Malabsorption: Finally Ready for Prime Time?

PURPOSE OF REVIEW

To provide an update on the prevalence, pathophysiology, disease associations, and treatment options for bile acid malabsorption (BAM).

RECENT FINDINGS

•Molecular mechanisms-BAs prevent water reabsorption and increase water secretion by intracellular mediators, increasing aquaporin channels and intracellular permeability. •Inflammatory bowel disease-new molecular mechanisms of BAM are identified in patients without ileal disease, including changes in expression of ileal BA transporter and nuclear receptors involved in BA homeostasis. •Microscopic colitis-BAM is one of the mechanisms leading to microscopic colitis. •Diagnostic testing-new diagnostic tests have been launched in the USA (serum C4 and fecal 48-h BA excretion); stimulated FGF19 has higher detection of BAM compared to fasting sample alone. •Treatment-investigational FXR agonists may provide a daily, oral option for treatment of BAM instead of BA sequestrants. There is a greater appreciation of the biological role of bile acids across multiple fields of medicine, including gastrointestinal indications.

Impact of edaphic factors and nutrient management on the hepatoprotective efficiency of Carlinoside purified from pigeon pea leaves: An evaluation of UGT1A1 activity in hepatitis induced organelles

Carlinoside is a unique compound well-known for its excellent curative potential in hepatitis. There is a substantial research gap regarding the medicinal use of carlinoside, as its concentrations are greatly variable (depending on locality). We cultivated Cajanus cajan using vermicompost as a major organic amendment at two locations (Sonitpur and Birbhum) with different soil types, but identical climate conditions. Sonitpur soils were richer in soil organic C (SOC), enzyme activation, and N/P content than Birbhum. However, vermi-treatment improved many soil properties (bulk density, water retention, pH, N/P/K, and enzyme activity) to narrow the locational gap in soil quality by 15-28%. We also recorded a many-fold increment in SOC storage capacities in both locations, which was significantly correlated with carlinoside, total phenol, and flavonoid contents in Cajanus leaves. This significantly up-regulated the carlinoside induced expression of the bilirubin-solubilizing UGT1A1enzyme in HepG2 cell and rat liver. Leaf extracts of vermicompost-aided plants could cure hepatitis in affected rat livers and in the HepG2 cell line. Accordingly, vermi-treatment is an effective route for the growth of Cajanus as a cash crop for biomedical applications and can produce a concurrent improvement in soil quality.

The "Gut Feeling": Breaking Down the Role of Gut Microbiome in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system with unknown etiology. Recently, the gut microbiota has emerged as a potential factor in the development of MS, with a number of studies having shown that patients with MS exhibit gut dysbiosis. The gut microbiota helps the host remain healthy by regulating various functions, including food metabolism, energy homeostasis, maintenance of the intestinal barrier, inhibition of colonization by pathogenic organisms, and shaping of both mucosal and systemic immune responses. Alteration of the gut microbiota, and subsequent changes in its metabolic network that perturb this homeostasis, may lead to intestinal and systemic disorders such as MS. Here we discuss the findings of recent MS microbiome studies and potential mechanisms through which gut microbiota can predispose to, or protect against, MS. These findings highlight the need of an improved understanding of the interactions between the microbiota and host for developing therapies based on gut commensals with which to treat MS.