Bile acid coordinates microbiota homeostasis and systemic immunometabolism in cardiometabolic diseases

Cardiometabolic disease (CMD), characterized with metabolic disorder triggered cardiovascular events, is a leading cause of death and disability. Metabolic disorders trigger chronic low-grade inflammation, and actually, a new concept of metaflammation has been proposed to define the state of metabolism connected with immunological adaptations. Amongst the continuously increased list of systemic metabolites in regulation of immune system, bile acids (BAs) represent a distinct class of metabolites implicated in the whole process of CMD development because of its multifaceted roles in shaping systemic immunometabolism. BAs can directly modulate the immune system by either boosting or inhibiting inflammatory responses via diverse mechanisms. Moreover, BAs are key determinants in maintaining the dynamic communication between the host and microbiota. Importantly, BAs via targeting Farnesoid X receptor (FXR) and diverse other nuclear receptors play key roles in regulating metabolic homeostasis of lipids, glucose, and amino acids. Moreover, BAs axis per se is susceptible to inflammatory and metabolic intervention, and thereby BAs axis may constitute a reciprocal regulatory loop in metaflammation. We thus propose that BAs axis represents a core coordinator in integrating systemic immunometabolism implicated in the process of CMD. We provide an updated summary and an intensive discussion about how BAs shape both the innate and adaptive immune system, and how BAs axis function as a core coordinator in integrating metabolic disorder to chronic inflammation in conditions of CMD.

CRISPR-Cas9: A method for establishing rat models of drug metabolism and pharmacokinetics

The 2020 Nobel Prize in Chemistry recognized CRISPR-Cas9, a super-selective and precise gene editing tool. CRISPR-Cas9 has an obvious advantage in editing multiple genes in the same cell, and presents great potential in disease treatment and animal model construction. In recent years, CRISPR-Cas9 has been used to establish a series of rat models of drug metabolism and pharmacokinetics (DMPK), such as

Combined obeticholic acid and apoptosis inhibitor treatment alleviates liver fibrosis

Obeticholic acid (OCA), the first FXR-targeting drug, has been claimed effective in the therapy of liver fibrosis. However, recent clinical trials indicated that OCA might not be effective against liver fibrosis, possibly due to the lower dosage to reduce the incidence of the side-effect of pruritus. Here we propose a combinatory therapeutic strategy of OCA and apoptosis inhibitor for combating against liver fibrosis. CCl-injured mice, d-galactosamine/LPS (GalN/LPS)-treated mice and cycloheximide/TNF (CHX/TNF)-treated HepG2 cells were employed to assess the effects of OCA, or together with IDN-6556, an apoptosis inhibitor. OCA treatment significantly inhibited hepatic stellate cell (HSC) activation/proliferation and prevented fibrosis. Elevated bile acid (BA) levels and hepatocyte apoptosis triggered the activation and proliferation of HSCs. OCA treatment reduced BA levels but could not inhibit hepatocellular apoptosis. An enhanced anti-fibrotic effect was observed when OCA was co-administrated with IDN-6556. Our study demonstrated that OCA inhibits HSCs activation/proliferation partially by regulating BA homeostasis and thereby inhibiting activation of HSCs. The findings in this study suggest that combined use of apoptosis inhibitor and OCA at lower dosage represents a novel therapeutic strategy for liver fibrosis.

Study of effect of rifampin and tanshinone II A on pravastatin transport via BSEP in sandwich-cultured rat hepatocytes / 中国药理学通报

Aim To elucidate the effect of rifampin and tanshinone II A on BSEP transport capacity using pravastatin as the BSEP substrate in sandwich-cultured rat hepatocytes (SCRH). Methods SCRH model was established. The doses of drugs were determined by MIT. A HPLC-MS/MS method was developed and was conducted method validation to detect the concentration of pravastatin. The effect of rifampin and tanshinone D A on the concentration of pravastatin in the bile duct was investigated. And the biliary excretion index ( BEI) was calculated. Results The SCRH model was successfully developed. The appropriate doses of rifampin, tanshinone DA, glibenclamide and pravastatin were determined. A stable and reliable HPLC-MS/MS method for the determination of pravastatin was established Compared with blank control group, rifampin reduced the concentration of pravastatin in the bile duct and the BEI of pravastatin. The high concentration of rifampin caused the steepest downward trends ( P < 0 . 0 1 ) . Compared with high concentration group of rifampin, the concentration of pravastatin in the bile duct and the BEI of pravastatin gradually increased after the combination of rifampin and tanshinone II A, and the effect of high concentration of tanshinone II A was the most significant ( P < 0. 0 1 ) . Conclusions Rifampin could inhibit the function of BSEP in SCRH. The combination of tanshinone D A and rifampin could reverse the inhibitor)' effect of BSEP transport capacity caused by rifampin.

A Rare BSEP Mutation Associated with a Mild Form of Progressive Familial Intrahepatic Cholestasis Type 2

ABSTRACT Progressive Familial Intrahepatic Cholestasis type 2 (PFIC2) is a rare cholestatic disorder diagnosed in infancy or childhood that can lead to severe hepatic fibrosis and liver failure. Mutations in the ABCB11 gene result in a deficiency of the bile salt export protein (BSEP) and accumulation of bile inside the hepatocytes. Hepatocellular carcinoma is another condition associated with severe forms of deletion mutations in the ABCB11 gene. Treatment options including ursodeoxycholic acid biliary diversion have mixed outcomes and some patients require liver transplantation. Here, we describe two siblings with an extremely mild form of PFIC2 inherited from heterozygous parents. The elder sibling had acute liver failure at the age of six months and both siblings had pruritus, cholestasis, coagulopathy and fat-soluble-vitamin deficiencies in infancy but have been asymptomatic past infancy. Genetic testing of the siblings revealed that each were compound heterozygotes for two missense mutations of the ABCB11 gene: p.C68Y and p.R832H. Medical treatment typical for PFIC2 has not been necessary for either patient. This is the first report of these variants following a mild course in two affected patients.(AU)

The research progress of bile acid efflux pump (BSEP) / 中国药理学通报

Bile acid efflux pump(BSEP)is the major transporter of bile salts secreted by liver cells into the bile,the variation and inhibition of which are connected with cholestasis and drug-induced liver injury.A deep understanding of the physiological and pathological function of BSEP IS achieved by analysis and summary of diseases.The paper briefly illustrates the structure, expression,regulation,substrates,inhibitors and diseases of BSEP,in order to provide further theoretical and experimental basis for the clinical treatment.

Effects of rifampicin on hepatotoxicity and genes related to bile acid metabolism in mice / 中国药理学通报

Aim Toexamineliverdamagebyrifampi-cin and hepatic gene expression related to bile acid me-tabolisminmice.Methods Adultmalemicewere given rifampicin(180 mg·kg-1 ,po)daily for 30 days and(90 mg·kg-1 ,po)daily for 90 days,blood bio-chemistry,histopathology,and gene expression were examined.Results Rifampicinincreasedanimalliver index and serum enzyme activities. Histopathology showed steatosis and spotted feathery-like degenera-tion.Rifampicin increased the expression of CYP7A1 after 30 and 90 days of administration,along with in-creased FXR and SHP.Rifampicin reduced the expres-sion of BSEP after 30 days of high dose administration. Conclusion Repeatedadministrationofrifampicin may cause liver injury and intrahepatic cholestasis in mice,and these effects are associated with the altera-tion of gene expression related to bile acid metabolism.

Metabolic effects of intestinal absorption and enterohepatic cycling of bile acids

The classical functions of bile acids include acting as detergents to facilitate the digestion and absorption of nutrients in the gut. In addition, bile acids also act as signaling molecules to regulate glucose homeostasis, lipid metabolism and energy expenditure. The signaling potential of bile acids in compartments such as the systemic circulation is regulated in part by an efficient enterohepatic circulation that functions to conserve and channel the pool of bile acids within the intestinal and hepatobiliary compartments. Changes in hepatobiliary and intestinal bile acid transport can alter the composition, size, and distribution of the bile acid pool. These alterations in turn can have significant effects on bile acid signaling and their downstream metabolic targets. This review discusses recent advances in our understanding of the inter-relationship between the enterohepatic cycling of bile acids and the metabolic consequences of signaling via bile acid-activated receptors, such as farnesoid X nuclear receptor (FXR) and the G-protein-coupled bile acid receptor (TGR5).

Bile acids and sphingosine-1-phosphate receptor 2 in hepatic lipid metabolism

The liver is the central organ involved in lipid metabolism. Dyslipidemia and its related disorders, including non-alcoholic fatty liver disease (NAFLD), obesity and other metabolic diseases, are of increasing public health concern due to their increasing prevalence in the population. Besides their well-characterized functions in cholesterol homoeostasis and nutrient absorption, bile acids are also important metabolic regulators and function as signaling hormones by activating specific nuclear receptors, G-protein coupled receptors, and multiple signaling pathways. Recent studies identified a new signaling pathway by which conjugated bile acids (CBA) activate the extracellular regulated protein kinases (ERK1/2) and protein kinase B (AKT) signaling pathway via sphingosine-1-phosphate receptor 2 (S1PR2). CBA-induced activation of S1PR2 is a key regulator of sphingosine kinase 2 (SphK2) and hepatic gene expression. This review focuses on recent findings related to the role of bile acids/S1PR2-mediated signaling pathways in regulating hepatic lipid metabolism.