Enterohepatic Research Articles

Bile Acid Nanoparticles - An Emerging Approach for Site Specific Drug Targeting

Abstract: Bile acids, a group of steroidal acids present in the bile act as biological surfactants and ligands for bile acid transporter proteins for signalling molecules to perform various paracrine and endocrine functions. The enterohepatic circulation of bile acids can be exploited to develop at-tractive drug delivery approaches with improved targetability of facial amphiphiles and enhanced drug bioavailability by improving absorption and metabolic stability. The effectiveness, safety and targetability of nanoparticles conjugated with bile acids and salts have been discussed in the present review. Various modifications of bile acids promoting absorption and oral bioavailability of drugs for treatment of various disease conditions such as cancer, diabetes and psychosis has al-so been discussed. Additionally, neuroprotective effect of bile acids and salts has demonstrated utility in various neurodegenerative disorders. Nanoparticles based on bile acids and salts repre-sent an area of emergent interest due to their unique and modifiable properties for improving ef-fectiveness of drugs.

Metformin: Diverse molecular mechanisms, gastrointestinal effects and overcoming intolerance in type 2 Diabetes Mellitus: A review.

Metformin, the first line treatment for patients with type 2 diabetes mellitus, has alternative novel roles, including cancer and diabetes prevention. This narrative review aims to explore its diverse mechanisms, effects and intolerance, using sources obtained by searching Scopus, PubMed and Web of Science databases, and following Scale for the Assessment of Narrative Review Articles reporting guidelines. Metformin exerts it actions through duration influenced, and organ specific, diverse mechanisms. Its use is associated with inhibition of hepatic gluconeogenesis targeted by mitochondria and lysosomes, reduction of cholesterol levels involving brown adipose tissue, weight reduction influenced by growth differentiation factor 15 and novel commensal bacteria, in addition to counteraction of meta-inflammation alongside immuno-modulation. Interactions with the gastrointestinal tract include alteration of gut microbiota, enhancement of glucose uptake and glucagon like peptide 1 and reduction of bile acid absorption. Though beneficial, they may be linked to intolerance. Metformin related gastrointestinal adverse effects are associated with dose escalation, immediate release formulations, gut microbiota alteration, epigenetic predisposition, inhibition of organic cation transporters in addition to interactions with serotonin, histamine and the enterohepatic circulation. Potentially effective measures to overcome intolerance encompasses carefully objective targeted dose escalation, prescription of fixed dose combination, microbiome modulators and prebiotics, in addition to use of extended release formulations.

Sensory-Motor Neuropathy in Mfn2 T105M Knock-in Mice and Its Reversal by a Novel Piperine-Derived Mitofusin Activator.

Mitochondrial dysfunction is a hallmark of many genetic neurodegenerative diseases, but therapeutic options to reverse mitochondrial dysfunction are limited. While recent studies support the possibility of improving mitochondrial fusion/fission dynamics and motility to correct mitochondrial dysfunction and resulting neurodegeneration in Charcot-Marie-Tooth disease (CMT) and other neuropathies, the clinical utility of reported compounds and relevance of preclinical models are uncertain. Here, we describe motor and sensory neuron dysfunction characteristic of clinical CMT type 2 A in a CRISPR/Casp-engineered Mfn2 Thr105Met (T105M) mutant knock-in mouse. We further demonstrate that daily oral treatment with a novel mitofusin activator derived from the natural product piperine can reverse these neurologic phenotypes. Piperine derivative 8015 promoted mitochondrial fusion and motility in Mfn2-deficient cells in a mitofusin-dependent manner and reversed mitochondrial dysfunction in cultured fibroblasts and reprogrammed motor neurons from a human CMT2A patient carrying the MFN2 T105M mutation. Like previous mitofusin activators, 8015 exhibited stereospecific functionality, but the more active stereoisomer, 8015-P2, is unique in that it has subnanomolar potency and undergoes entero-hepatic recirculation which extends its in vivo half-life. Daily administration of 8015-P2 to Mfn2 T105M knock-in mice for 6 weeks normalized neuromuscular and sensory dysfunction and corrected histological/ultrastructural neurodegeneration and neurogenic myoatrophy. These studies describe a more clinically relevant mouse model of CMT2A and an improved mitofusin activator derived from piperine. We posit that 8015-P2 and other piperine derivatives may benefit CMT2A or other neurodegenerative conditions wherein mitochondrial dysdynamism plays a contributory role. SIGNIFICANCE STATEMENT: Mitochondrial dysfunction is widespread and broadly contributory in neurodegeneration, but difficult to target therapeutically. Here, we describe 8015-P2, a new small molecule mitofusin activator with ∼10-fold greater potency and improved in vivo pharmacokinetics versus comparators, and demonstrate its rapid reversal of sensory and motor neuron dysfunction in an Mfn2 T105M knock-in mouse model of Charcot-Marie-Tooth disease type 2 A. These findings further support the therapeutic approach of targeting mitochondrial dysdynamism in neurodegeneration.

Reduction of the risk of biliary lithiasis caused by various weight reduction options in obesity

At present obesity is a major public health challenge globally, which accounts for a significant portion of all healthcare costs. Obesity and its complications, insulin resistance and dyslipidemia, have been identified as independent risk factors for cholelithiasis. Cholelithiasis is mainly caused by four factors: bile cholesterol overload caused by excess cholesterol made in the liver due to genetic factors; systolic dysfunction of the gallbladder wall; bowel dysfunction with excess absorption of cholesterol or cholesterol overload caused by impaired hepatic bile circulation; and accelerated growth of cholesterol crystals and solid cholesterol crystals. Rapid weight loss (≥1.5 kg/week) due to low-calorie diets as the main treatment method, or after bariatric surgery is one of the risk factors for gallstone formation. Bariatric surgery is effective for the treatment of obesity and its complications, but bariatric surgery does not reduce the incidence of cholelithiasis. On the contrary, many studies showed that bariatric surgery may increase the incidence of cholelithiasis. The rapid weight loss causes fat mobilization and then increases serum cholesterol and triglyceride levels. On the other hand, bowel dysfunction due to bariatric surgery is accompanied by decreased cholecystokinin levels, causing impaired gallbladder contractility. Cholelithiasis requires close attention after bariatric surgery, with 10% of patients undergoing bariatric surgery having to undergo cholecystectomy postoperatively due to a high risk of cholelithiasis. UDCA is a natural bile acid that is prescribed to be taken orally (by mouth). UDCA inhibits the absorption of cholesterol in the bowel, enhances the biosynthesis of bile acids, and reduces biliary cholesterol secretion. UDCA is a choleretic agent, as all bile acids, but differs from other dihydroxy bile acids in being non-cytotoxic. The use of UDCA while following a low-calorie diet and after bariatric surgery significantly reduces the risk of gallstone formation and cholecystectomy with associated complications.

Hinokiflavone from Platycladi cacumen as a potent broad-spectrum inhibitor of gut microbial Loop-1 β-glucuronidases: Inhibition kinetics and molecular simulation

Gut microbial Loop-1 β-glucuronidases (gmGUS) played an important role in irinotecan-induced gastrointestinal toxicity by regulating the level of its active metabolite SN38 through enterohepatic recirculation. gmGUS inhibition has emerged as a promising approach to relieve its dose-limiting intestinal toxicity and improve its medication efficacy. This study aims to investigate the inhibitory effects and mechanisms of Platycladi cacumen and its main constituent hinokiflavone against four different types of Loop-1 gmGUS (EeGUS, SaGUS, CpGUS and EcGUS). Our results showed that the ethanol extract of Platycladi cacumen displayed strong broad-spectrum inhibition against four gmGUS, and hinokiflavone could potently inhibit EeGUS, SaGUS, CpGUS and EcGUS with IC50 values of 0.09 ± 0.01 μM, 0.44 ± 0.01 μM, 0.20 ± 0.01 μM and 0.69 ± 0.10 μM, respectively. Inhibition kinetic analyses demonstrated that hinokiflavone acted as a strong competitive inhibitor of EeGUS with Ki value of 0.13 μM, while it displayed non-competitive inhibition against SaGUS, CpGUS and EcGUS, with the Ki values of 0.43 μM, 0.33 μM and 0.76 μM, respectively. Docking simulations revealed that hinokiflavone could tightly bind with Tyr-485 and Glu-516 in catalytic sites of EeGUS, as well it created strong interactions with amino acids in loop structures of SaGUS (Asn-362), CpGUS (Phe-363, Met-364, Ala-365 and Arg-375) and EcGUS (Leu-361) to interfere the substrate entry into the catalytic pocket. Collectively, these results confirmed that hinokiflavone from Platycladi cacumen is a potent naturally occurring inhibitor of gmGUS with broad efficiency, suggesting hinokiflavone will be helpful for alleviating intestinal toxicity in irinotecan therapy.

8232 Therapeutic Plasma Exchange as a Bridge to Total Thyroidectomy in a Patient with Refractory Thyroid Storm

Abstract Disclosure: A. Sridhar: None. T. Chaudhary: None. S. Patil: None. A. Prabha Kumar: None. K. Djekidel: None. B.C. Jameson: None. Background: Thyroid storm is a rare life-threatening complication of hyperthyroidism with a mortality rate of 10-30%. Therapeutic plasma exchange (TPE) could be a bridge to definitive total thyroidectomy in patients with refractory disease who fail conventional therapy. Clinical case: Patient is a 31-year-old male with a past medical history of untreated hypertension, anxiety, alcohol use, substance abuse and a family history of Graves’ disease. He presented with complaints of breathing difficulty, back and shoulder pain for the past 1 day. In the ED he was found to be in respiratory distress with a rate of 40/min. He was started on a non-rebreather mask and was eventually intubated due to worsening distress. He was tachycardic with a heart rate of 130/min and had elevated blood pressure at 170/105 mm Hg. Physical examination was significant for diaphoresis, accessory respiratory muscle use, and diffuse swelling on the front of the neck. His blood work was significant for hemoglobin 11.1g/dL, TSH <0.01 uIU/mL, FT3 >32.6 pg/ml, FT4>7.8 ng/dL and urine drug screen was negative. Chest X-ray showed mild perihilar vascular congestion due to pulmonary edema. CT neck showed nonspecific diffuse enlargement of the thyroid gland without dominant thyroid nodule. The patient was admitted to the ICU for management of thyroid storm likely from Graves’ disease. Burch-Wartofsky Point Scale score on admission was 60. Endocrinology was consulted and the patient was started on IV hydrocortisone 100 mg and IV Methimazole 20 mg every 8 hours, propranolol 60 mg every 6 hours, and iodine drops 300 mg every 6 hours after the first dose of methimazole. Since repeat FT4 after 48 hours showed no improvement, he was switched to Propylthiouracil (PTU) with a loading dose of 500mg every 4 hours for 2 doses followed by 250 mg every 6 hours and cholestyramine 4 g orally 4 times daily to reduce enterohepatic circulation of thyroid hormone. After 3 days of PTU, the patient’s FT3 was improving but FT4 continued to be elevated. ENT was consulted for total thyroidectomy, but the patient required preparation to improve FT4 levels prior to surgery. He was transferred to a tertiary care center on Day 6 of admission to undergo TPE. After 3 sessions of TPE serum FT3 and FT4 decreased, patient’s mentation improved, and he was extubated on Day 10 of admission. He received a total of 5 sessions of TPE and underwent total thyroidectomy on Day 15 of admission without complications. Postoperatively he was started on oral Levothyroxine 125 mcg once daily and calcitriol 0.25 mcg twice daily. Patient continues to follow up with Endocrinology clinic for thyroid function monitoring and medication adjustment. Conclusion: Given the high mortality rate associated with thyroid storm, early recognition of refractory disease is imperative. Bridging with TPE while awaiting total thyroidectomy improved clinical outcomes in our patient and should be considered in such cases. Presentation: 6/3/2024

Evaluation of efficacy of oral calcium phosphate as an adjunct to standard-of-care regular phototherapy in cases of neonatal jaundice: a hospital-based double-blind, randomised, placebo-controlled trial

ObjectiveNeonatal jaundice is the most common cause of neonatal morbidity and rehospitalisation in the first week of life, affecting approximately 60% of term and 80% of preterm neonates, with 10%...

Caffeoylquinic acids from Silphium perfoliatum L. show hepatoprotective effects on cholestatic mice by regulating enterohepatic circulation of bile acids

Ethnopharmacological relevanceThe incidence of cholestatic liver disease (CLD), which is primarily marked by abnormal bile acids (BAs) metabolism and can result in significant hepatic injury, is rising. Nevertheless, there remains a lack of effective treatments and drugs in clinical practice. Silphium perfoliatum L. (SP) is rich in various structural types of caffeoylquinic acid (CQA) compounds, and it is a traditional herb of North American Indians with hepatobiliary therapy effects. However, its therapeutic effect and mechanism of action on CLD have never been studied. Aim of the studyTo determine if SP-8, an extract rich in CQAs from SP, protects against cholestatic liver injury induced by alpha-naphthylisothiocyanate (ANIT) and to clarify its mechanism based on the farnesoid x receptor (FXR) signaling pathway and enterohepatic circulation of BAs. Materials and methodsThe therapeutic efficacy of SP-8 was evaluated by assessing the serum biochemical indices, inflammatory factors, and liver histopathology. Targeted metabolomics of the BAs was studied in the feces, liver, serum, and bile using UPLC-MS/MS. Additionally, a Western blot analysis was used to examine the expression levels of the peroxisome proliferator-activated receptor γ (PPARγ), the FXR, and proteins related to the synthesis and transport of BAs. 16S rRNA gene sequencing was performed to evaluate the gut microbiota (GM). Finally, molecular docking simulations were conducted to assess the interaction between seven types of CQAs from SP-8 with FXR and PPARγ. ResultsSP-8 significantly enhanced the health status of cholestatic mice induced by ANIT as evidenced by a notable reduction in the liver function indices and pro-inflammatory factors, restoration of liver pathological damage, and acceleration of BAs excretion through the feces. In addition, the levels of harmful secondary BAs in the liver and blood were significantly reduced by SP-8. Furthermore, the results of the study on the mechanism of action confirmed that SP-8 not only regulated FXR and PPARγ but also significantly ameliorated the GM structure, thereby promoting the enterohepatic circulation of BAs and achieving the homeostasis of the BAs in the blood and liver. In addition, SP-8 successfully reduced the inflammatory response by strongly suppressing the nuclear translocation of NF-κBp65. According to the molecular docking results, the extract's primary active ingredients could be the seven CQAs in SP-8, as they exhibited a strong affinity for both FXR and PPARγ. Finally, the Mantel test analysis revealed a significant correlation among cholestatic-associated parameters, the GM, and BAs. ConclusionIt was confirmed for the first time that the SP-8 extract of Silphium perfoliatum L. that is rich in seven CQAs had a strong therapeutic effect on ANIT-induced CLD. Its mechanism may involve the regulation of the FXR signaling pathway and the amelioration of the GM structure to promote the homeostasis of BAs enterohepatic circulation. This study provides a potential candidate medicinal herb and its components for the development of CLD therapeutic drugs.

Gly-β-MCA is a potent anti-cholestasis agent against “human-like” hydrophobic bile acid-induced biliary injury in mice

Cholestasis is a chronic liver disease with limited therapeutic options. Hydrophobic bile acid-induced hepatobiliary injury is a major pathological driver of cholestasis progression. This study investigates the anti-cholestasis efficacy and mechanisms of action of glycine-conjugated β-muricholic acid (Gly-β-MCA). We use female Cyp2c70 KO mice, a rodent cholestasis model that does not produce endogenous muricholic acid (MCA) and exhibits a “human-like” hydrophobic bile acid pool and female-dominant progressive hepatobiliary injury and portal fibrosis. The efficacy of Gly-β-MCA and ursodeoxycholic acid (UDCA), the first line drug for cholestasis, on cholangiopathy and portal fibrosis are compared. At a clinically relevant dose, Gly-β-MCA shows comparable efficacy as UDCA in reducing serum transaminase, portal inflammation and ductular reaction, and better efficacy than UDCA against portal fibrosis. Unlike endogenous bile acids, orally administered Gly-β-MCA is absorbed at low efficiency in the gut and enters the enterohepatic circulation mainly after microbiome-mediated deconjugation, which leads to taurine-conjugated MCA enrichment in bile that alters enterohepatic bile acid pool composition and reduces bile acid pool hydrophobicity. Gly-β-MCA also promotes fecal excretion of endogenous hydrophobic bile acids and decreases total bile acid pool size, while UDCA treatment does not alter total bile acid pool. Furthermore, Gly-β-MCA treatment leads to gut unconjugated MCA enrichment and reduces gut hydrophobic lithocholic acid (LCA) exposure. In contrast, UDCA treatment drives a marked increase of LCA flux through the large intestine. In conclusion, Gly-β-MCA is a potent anti-cholestasis agent with potential clinical application in treating human cholestasis.

146 The effects of antimicrobials and antimicrobial associated diarrhea on the fecal microbiome of the horse

Abstract Antibiotics are commonly given to horses to treat known bacterial infections or as prophylaxis against the development of infection. Diarrhea is a recognized adverse effect of antimicrobial administration in horses (antimicrobial associated diarrhea, AAD). In veterinary referral centers, AAD has a reported incidence of 22 to 94% (McGorum, 2010), while horses with AAD are 4.5 times more likely to die compared with horses with other types of colitis (Woods and Cohen, 1999). Although all antibiotics have potential to induce diarrhea, some have increased risk due to low oral absorption, biliary excretion, or enterohepatic recycling. The role of dysbiosis in the gut microbiota is a key feature in the pathogenesis of AAD. Disruption of commensal bacteria of the hindgut allows for pathogen overgrowth and alteration in microbial metabolic function. To date, 16S rRNA sequencing has been used to characterize the effects of penicillin, trimethoprim sulfa, doxycycline, erythromycin, ceftiofur, enrofloxacin, oxytetracycline and metronidazole on the fecal microbiome in healthy horses (Costa et al., 2015; Arnold et al., 2020; Liepman, 2022). Regardless of mechanism of action, antibiotics typically reduce diversity (species richness and evenness) and alter the bacterial community structure of the fecal microbiome, even when animals maintain normal health status and fecal character (Arnold et al., 2021). These effects typically require at least 30 days before the microbiome returns to baseline (Gomez et al, 2023). In horses with colitis, changes in the microbiome are often significant. Horses with AAD demonstrate the most severe disruption of the fecal microbiome compared with horses with Salmonella or undifferentiated colitis. These changes are evident from the phylum to species level, and include important phyla such as Bacteroidetes, Firmicutes, Fibrobacter and Verrucomicrobia (Arnold et al., 2020; Liepman, 2022; Costa et al., 2015). Alterations in the microbiota result in functional metabolic changes that are clinically manifested by diarrhea. Potential changes include alterations in the metabolism of bile acids, carbohydrates including short chain fatty acids, amino acids, lipids and proteins. There is also evidence that antimicrobials increase intestinal permeability via effects on tight junction proteins and by compromising the barrier function provided by the mucus layer between the enterocytes and gut lumen. Recent work comparing horses on antimicrobials that did and did not develop diarrhea confirm that horses with diarrhea have depletion of Verrocomicrobia and metabolites related to gastrointestinal barrier function (Arnold et al., 2021).

P05-29 Refining toxicokinetic models for enterohepatic recirculation of toxins undergoing hepatic glucuronidation

P05-29 Refining toxicokinetic models for enterohepatic recirculation of toxins undergoing hepatic glucuronidation

Simultaneous determination of Obeticholic acid and its two major metabolites in human plasma after administration of Obeticholic acid tablets using ultra-high performance liquid chromatography tandem mass spectrometry

Obeticholic acid (OCA), a semisynthetic bile acid derivative, was approved for its therapeutic use in primary biliary cirrhosis. OCA has a enterohepatic circulation and host-gut microbiota metabolic interaction, which produce various metabolites. Such metabolites, especially structural isomers of OCA, together with the need to achieve idea lower limit of quantitation (LLOQ) with minimum matrix interference, bring about significant difficulties to the bioanalysis of OCA. Herein, by applying a combination of solid-phase extraction (SPE) and ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS), we introduced an approach for the bioanalysis of OCA along with its two major metabolites—glyco-OCA (GOA) and tauro-OCA (TOA) in human plasma, the full validation results of which showed excellent performance. The quantitative range is 0.2506 ∼ 100.2 ng/mL for OCA, 0.2500 ∼ 100.0 ng/mL for GOA, as well as 0.1250 ∼ 50.00 ng/mL for TOA, respectively. This method was successfully applied to the pharmacokinetic studies in healthy subjects following administration of OCA tablets.

Bile Acids and Liver Cancer: Molecular Mechanism and Therapeutic Prospects.

Hepatocellular carcinoma (HCC) is a highly aggressive liver malignancy and one of the most lethal cancers globally, with limited effective therapeutic options. Bile acids (BAs), as primary metabolites of hepatic cholesterol, undergo enterohepatic circulation involving secretion into the intestine and reabsorption into the liver, and their composition is modulated in this process. Recent clinical observations have revealed a correlation between alteration in the BAs profile and HCC incidence, and the effect of various species of BAs on HCC development has been investigated. The regulatory effect of different BA species on cell proliferation, migration, and apoptosis in tumor cells, as well as their interaction with gut microbiota, inflammation, and immunity have been identified to be involved in HCC progression. In this review, we summarize the current understanding of the diverse functions of BAs in HCC pathogenesis and therapy, from elucidating the fundamental mechanisms underlying both tumor-promoting and tumor-suppressive consequences of various BA species to exploring potential strategies for leveraging BAs for HCC therapy. We also discuss ongoing efforts to target specific BA species in HCC treatment while highlighting new frontiers in BA biology that may inspire further exploration regarding their connection to HCC.

Disposition of Oral Nalbuphine and Its Metabolites in Healthy Subjects and Subjects with Hepatic Impairment: Preliminary Modeling Results Using a Continuous Intestinal Absorption Model with Enterohepatic Recirculation.

Nalbuphine (NAL) is a mixed κ-agonist/μ-antagonist opioid with extensive first-pass metabolism. A phase 1 open-label study was conducted to characterize the pharmacokinetics (PKs) of NAL and select metabolites following single oral doses of NAL extended-release tablets in subjects with mild, moderate, and severe hepatic impairment (Child-Pugh A, B, and C, respectively) compared to healthy matched subjects. NAL exposures were similar for subjects with mild hepatic impairment as compared to healthy subjects and nearly three-fold and eight-fold higher in subjects with moderate and severe hepatic impairment, respectively. Datasets obtained for healthy, moderate, and severe hepatic impaired groups were modeled with a mechanistic model that incorporated NAL hepatic metabolism and enterohepatic recycling of NAL and its glucuronidated metabolites. The mechanistic model includes a continuous intestinal absorption model linked to semi-physiological liver-gallbladder-compartmental PK models based on partial differential equations (termed the PDE-EHR model). In vitro studies indicated that cytochromes P450 CYP2C9 and CYP2C19 are the major CYPs involved in NAL oxidation, with glucuronidation mainly catalyzed by UGT1A8 and UGT2B7 isozymes. Complex formation and elimination kinetics of NAL and four main metabolites was well predicted by PDE-EHR. The model is expected to improve predictions of drug interactions and complex drug disposition.

Bile acid diarrhoea and metabolic changes after cholecystectomy: a prospective case-control study

IntroductionBile acid diarrhoea (BAD) can occur due to disruption to the enterohepatic circulation such as following cholecystectomy. However, the mechanism behind this is as yet unknown. The aim of this study was to determine the rate of post-cholecystectomy diarrhoea and to assess whether FGF19 within the gallbladder was associated with the development of BAD.MethodsThis was a prospective case-control study in which patients were assessed pre- and post- cholecystectomy (study group) and compared with patients also having laparoscopic surgery but not cholecystectomy (control group). Their bowel habits and a GIQLI questionnaire was performed to compare the pre- and post-operative condition of the two groups. Gallbladder tissue sample was tested for FGF19 and PPARα in the study group patients. A subset had serum lipid levels, FGF19 and C4 measurements.ResultsGallbladder PPAR α was found to have a significant correlation with stool consistency, with the lower the PPARα concentration the higher the Bristol stool chart number (i.e. looser stool). There were no significant correlation when assessing the effect of gallbladder FGF19 concentration on bowel habit, stool consistency, lipid levels, BMI or smoking. The study group showed a significant increase in triglycerides post-operatively, however there were no changes in cholesterol, HDL and LDL levels. Correlation of the increased triglyceride levels with stool consistency and frequency showed no significant resultsDiscussion and conclusionWe did not find any direct evidence that FGF19 levels within the gallbladder impact the development of post-cholecystectomy diarrhoea. There was however a significant increase in triglycerides postoperatively. There was also no correlation of bowel habits with PPARα suggesting the observed rise is independent of this pathway. Further work is required particularly relating to the gut microbiome to further investigate this condition.

Lipopolysaccharide, arbiter of the gut-liver axis, modulates hepatic cell pathophysiology in alcoholism.

Over the last four decades, clinical research and experimental studies have established that lipopolysaccharide (LPS)-a component of the outer membrane of gram-negative bacteria-is a potent hepatotoxic molecule in humans and animals. Alcohol abuse is commonly associated with LPS endotoxemia. This review highlights LPS molecular structures and modes of release from bacteria, plasma LPS concentrations, induction of microbiota dysbiosis, disruption of gut epithelial barrier, and translocation of LPS into the portal circulation impacting the pathophysiology of hepatic cells via the gut-liver axis. We describe and illustrate the portal vein circulation and its distributaries draining the gastrointestinal tract. We also elaborate on the gut-liver axis coupled with enterohepatic circulation that represents a bidirectional communication between the gut and liver. The review also updates the data on how circulating LPS is cleared in a coordinated effort between Kupffer cells, hepatocytes, and liver sinusoidal endothelial cells. Significantly, the article reviews and updates the modes/mechanisms of action by which LPS mediates the diverse pathophysiology of Kupffer cells, hepatocytes, sinusoidal endothelial cells, and hepatic stellate cells primarily in association with alcohol consumption. Specifically, we review the intricate linkages between ethanol, microbiota dysbiosis, LPS production, gut-liver axis, and pathophysiology of various hepatic cells. The maintenance of the gut barrier structural and functional integrity and microbiome homeostasis is essential in mitigating alcoholic liver disease and improving liver health.

Lactucin reverses liver fibrosis by inhibiting TGF-β1/STAT3 signaling pathway and regulating short-chain fatty acids metabolism

TGF-β1 activation of hepatic stellate cells (HSCs), transcriptional activator 3 (Stat3) activation and short chain fatty acids (SCFAs), metabolite of intestinal bacteria, is closely associated with hepatic fibrosis. Previous studies have shown that Lactucin has significant anti-inflammatory and hepatoprotective effects; however, the mechanism of Lactucin's role in liver fibrosis associated with SCFAs remains unknown. This study was intended to investigate whether effect of Lactucin on liver fibrosis was mediated by TGF-β1/Stat3 and SCFAs. We found that Lactucin induced apoptosis in HSC-T6 cells, and inhibition of nuclear translocation of Stat3 and p-Stat3. And Smad3 and TGF-β1 protein expression was significantly inhibited, while TLR4 and Smad7 protein expression was significantly enhanced. For in vivo experiments, we demonstrated that Lactucin alleviated liver fibrosis in mice, as evidenced by a reduction in inflammatory factors, collagen deposition, liver injury and fibrosis-related factors expression, especially the expression of Smad3 and TGF-β1 proteins was significantly suppressed and Smad7 protein expression was significantly increased in the liver. In addition, the levels of acetic acid, butyric acid and valeric acid in the intestine of Lactucin-treated mice were significantly higher than those in the intestine of liver fibrosis mice. In conclusion, based on the results of in vivo and in vitro experiments, preventive mechanism of Lactucin against liver fibrosis in mice may be to improve the enterohepatic circulation by regulating the metabolites of intestinal microorganisms, acetic acid and butyric acid, and to further regulate the Stat3 and TGF-β1 signaling pathway through the "gut-liver axis" to combat liver fibrosis.

Developmental Expression of Drug Transporters and Conjugating Enzymes Involved in Enterohepatic Recycling: Implication for Pediatric Drug Dosing.

Around 50% of the drugs used in children have never been tested for safety and efficacy in this vulnerable population. Immature drug elimination pathways can lead to drug toxicity when pediatric doses are determined using empirical methods such as body-surface area or body-weight-normalized adult dosing. In the absence of clinical data, physiologically-based pharmacokinetic (PBPK) modeling has emerged as a useful tool to predict drug pharmacokinetics in children. These models utilize developmental physiological data, including age-dependent differences in the abundance of drug-metabolizing enzymes and transporters (DMET), to mechanistically extrapolate adult pharmacokinetic data to children. The reported abundance data of hepatic DMET proteins in subcellular fractions isolated from frozen tissue are prone to high technical variability. Therefore, we carried out the proteomics-based quantification of hepatic drug transporters and conjugating enzymes in 50 pediatric and 8 adult human hepatocyte samples. Out of the 34 studied proteins, 28 showed a significant increase or decrease with age. While MRP6, OAT7, and SULT1E1 were highest in < 1-year-old samples, the abundance of P-gp and UGT1A4 was negligible in < 1-year-old samples and increased significantly after 1 year of age. Incorporation of the age-dependent abundance data in PBPK models can help improve pediatric dose prediction, leading to safer drug pharmacotherapy in children.

Candida tropicalis ZD-3 prevents excessive fat deposition by regulating ileal microbiota and bile acids enterohepatic circulation in broilers.

Evidence suggests that the dietary intake of Candida tropicalisZD-3 (ZD-3) has various health benefits, but the treatment mechanisms and effects remain unclear. The aim of this study investigates the effect of ZD-3 on reducing fat deposition in broilers and the underlying mechanism. 180 one-day-old, yellow-feathered broilers were randomly divided into three groups: control (CON) group fed a basal diet, an active Candida tropicalis ZD-3 (ZD) group supplemented with ZD, and a heat-inactivated Candida tropicalis ZD-3 (HZD) group supplemented with HZD. The experiment lasted for 28 d. The ZD and HZD treatments significantly reduced the abdominal fat index (p < 0.05), decreased TG levels in serum and liver (p < 0.05), altered the ileal microbial composition by reducing the Firmicutes to Bacteroidetes (F/B) ratio. Additionally, the ZD and HZD treatments reduced liver cholesterol by decreasing ileal FXR-FGF19 signaling and increasing liver FXR-SHP signaling (p < 0.05). The ZD and HZD treatments also changed liver PC and TG classes lipid composition, regulating liver lipid metabolism by promoting TG degradation and modulating the signal transduction of the cell membrane. Overall, ZD-3 was effective in improving lipid metabolism in broilers by regulating the ileal microbial composition and BAs enterohepatic circulation. This study provides a theoretical basis for the development and application of ZD-3 for the regulation of lipid metabolism in broilers.

Multiple-dose pharmacokinetics of cenerimod and the effect of charcoal on its elimination.

Cenerimod is a sphingosine-1-phosphate receptor 1 modulator that reduces tissue availability of circulating lymphocytes. The compound is in Phase3 development for the treatment of systemic lupus erythematosus. Its pharmacokinetic properties are characterized by slow absorption and multiphasic elimination with a long terminal half-life (t½), potentially caused by enterohepatic circulation (EHC). In this trial in healthy participants, oral cenerimod 0.5 and 4mg once daily was administered for 50 days, followed by oral administration of activated charcoal (ie, 50 mg every 12 h for 11 days, starting 24 h after the last cenerimod dose), to investigate the potential EHC of cenerimod and assess whether elimination of cenerimod can be accelerated. The multiple-dose pharmacokinetics, pharmacodynamics, safety, and tolerability of cenerimod were also evaluated. For both doses, peak plasma concentrations were reached 6 and 7h after dosing. Cenerimod accumulated approximately eightfold and (near) steady-state conditions were reached after 50 doses, resembling clinically meaningful exposure to cenerimod. The t½ following 0.5 and 4 mg of cenerimod was 767and 799 h (ie, 32 and 33 days) and 720 and 780h (ie, 30 and 33 days) with or without administration of charcoal, respectively, indicating no statistically significant difference. Therefore, charcoal did not accelerate cenerimod elimination suggesting that there is no EHC of cenerimod. A reversible, dose-dependent decrease in total lymphocyte count was observed. No safety concerns were identified; administration of charcoal was well tolerated.