Disturbance of Hepatic and Intestinal UDP-glucuronosyltransferase in Rats with Trinitrobenzene Sulfonic Acid-induced Colitis

Dysregulated hepatic UDP-glucuronosyltransferases and flavonoids glucuronidation in experimental colitis

Glucuronidation catalyzed by UDP-glucuronosyltransferases (UGTs) is one of the most important phase II mechanisms, facilitating drug clearance via conjugation of glucuronic acid with polar groups of xenobiotics. Accumulating evidence suggests that IBDs impact drug disposition, but whether and how IBDs regulate UGTs and drug glucuronidation remains undefined. In this study, we aim to investigate the expression of UGTs and drug glucuronidation in experimental colitis. Given that glucuronidation occurs primarily in the liver, we analyzed the mRNA changes in hepatic UGTs with a DSS-induced mouse colitis model. Twelve UGTs were downregulated in the liver of colitis mice including UGT1A1 and UGT1A9 (two representative UGTs). Colitis in mice downregulated UGT1A1 and UGT1A9 in the liver but not in small intestine, colon, and kidney. We also established that the downregulation of UGTs was attributed to the disease itself rather than the DSS compound. Moreover, colitis-reduced UGT1A1 and UGT1A9 lead to dampened baicalein and puerarin glucuronidation. PXR was the only UGT regulator significantly downregulated in colitis mice, suggesting dysregulation of PXR is associated with the downregulation of UGT1A1 and UGT1A9, thereby potentially resulting in dysfunction of baicalein and puerarin glucuronidation. Collectively, we establish that UGTs and glucuronidation are dysregulated in colitis, and this effect may cause variation in drug responsiveness in IBDs.

The Complex Relationship Between Microbiota, Immune Response and Creeping Fat in Crohn's Disease

In the last decade, there has been growing interest in the pathological involvement of hypertrophic mesenteric fat attached to the serosa of the inflamed intestinal segments involved in Crohn's disease [CD], known as creeping fat. In spite of its protective nature, creeping fat harbours an aberrant inflammatory activity which, in an already inflamed intestine, may explain why creeping fat is associated with a greater severity of CD. The transmural inflammation of CD facilitates the interaction of mesenteric fat with translocated intestinal microorganisms, contributing to activation of the immune response. This may be not the only way in which microorganisms alter the homeostasis of this fatty tissue: intestinal dysbiosis may also impair xenobiotic metabolism. All these CD-related alterations have a functional impact on nuclear receptors such as the farnesoid X receptor or the peroxisome proliferator-activated receptor γ, which are implicated in regulation of the immune response, adipogenesis and the maintenance of barrier function, as well as on creeping fat production of inflammatory-associated cells such as adipokines. The dysfunction of creeping fat worsens the inflammatory course of CD and may favour intestinal fibrosis and fistulizing complications. However, our current knowledge of the pathophysiology and pathogenic role of creeping fat is controversial and a better understanding might provide new therapeutic targets for CD. Here we aim to review and update the key cellular and molecular alterations involved in this inflammatory process that link the pathological components of CD with the development of creeping fat.

Hepatoenteric recycling is a new disposition mechanism for orally administered phenolic drugs and phytochemicals in rats

Many orally administered phenolic drugs undergo enterohepatic recycling (EHR), presumably mediated by the hepatic phase II enzymes. However, the disposition of extrahepatically generated phase II metabolites is unclear. This paper aims to determine the new roles of liver and intestine in the disposition of oral phenolics. Sixteen representative phenolics were tested using direct portal vein infusion and/or intestinal perfusion. The results showed that certain glucuronides were efficiently recycled by liver. OATP1B1/1B3/2B1 were the responsible uptake transporters. Hepatic uptake is the rate-limiting step in hepatic recycling. Our findings showed that the disposition of many oral phenolics is mediated by intestinal glucuronidation and hepatic recycling. A new disposition mechanism 'Hepatoenteric Recycling (HER)", where intestine is the metabolic organ and liver is the recycling organ, was revealed. Further investigations focusing on HER should help interpret how intestinal aliments or co-administered drugs that alter gut enzymes (e.g. UGTs) expression/activities will impact the disposition of phenolics.

Comparison of the drug-drug interactions potential of ibrutinib and acalabrutinib via inhibition of UDP-glucuronosyltransferase

Ibrutinib and acalabrutinib are two Bruton's tyrosine kinase (BTK) inhibitors which have gained Food and Drug Administration (FDA) approval for the treatment of various B cell malignancies. Herein, we investigated the effects of the two drugs on UDP-glucuronosyltransferase (UGT) activities to evaluate their potential risk for drug-drug interactions (DDIs) via UGT inhibition. Our data indicated that ibrutinib exerted broad inhibition on most of UGTs, including a potent competitive inhibition against UGT1A1 with a K_i value of 0.90 ± 0.03 μM, a noncompetitive inhibition against UGT1A3 and UGT1A7 with K_i values of 0.88 ± 0.03 μM and 2.52 ± 0.23 μM, respectively, while acalabrutinib only exhibited weak UGT inhibition towards all tested UGT isoforms. DDI risk prediction suggested that the inhibition against UGT1A1 and UGT1A3 by ibrutinib might bring a potential DDIs risk, while acalabrutinib was unlikely to trigger clinically significant UGT-mediated DDIs due to its weak effects. Our study raises an alarm bell about potential DDI risk associated with ibrutinib, however, the extrapolation from in vitro data to in vivo drug interactions should be taken with caution, and additional systemic study is needed.

Connecting the Dots Between Inflammatory Bowel Disease and Metabolic Syndrome: A Focus on Gut-Derived Metabolites

The role of the microbiome in health and disease has gained considerable attention and shed light on the etiology of complex diseases like inflammatory bowel disease (IBD) and metabolic syndrome (MetS). Since the microorganisms inhabiting the gut can confer either protective or harmful signals, understanding the functional network between the gut microbes and the host provides a comprehensive picture of health and disease status. In IBD, disruption of the gut barrier enhances microbe infiltration into the submucosae, which enhances the probability that gut-derived metabolites are translocated from the gut to the liver and pancreas. Considering inflammation and the gut microbiome can trigger intestinal barrier dysfunction, risk factors of metabolic diseases such as insulin resistance may have common roots with IBD. In this review, we focus on the overlap between IBD and MetS, and we explore the role of common metabolites in each disease in an attempt to connect a common origin, the gut microbiome and derived metabolites that affect the gut, liver and pancreas.

Patchouli alcohol activates PXR and suppresses the NF-κB-mediated intestinal inflammatory

ETHNOPHARMACOLOGICAL RELEVANCE

The pregnane-X-receptor (PXR) is involved in inflammatory bowel disease (IBD). Patchouli alcohol (PA) has anti-inflammatory effects; however, the effect of PA on IBD pathogenesis remains largely unknown.

AIM OF THE STUDY

The aim of the present study was to investigate the anti-inflammatory effect of PA, primarily focused on crosstalk between PA-mediated PXR activation and NF-κB inhibition.

MATERIALS AND METHODS

We evaluated the anti-inflammatory effect of PA with respect to PXR/NF-κB signalling using in vitro and in vivo models. In vitro, PA, identified as a PXR agonist, was evaluated by hPXR transactivation assays and through assessing for CYP3A4 expression and activity. NF-κB inhibition was analysed based on NF-κB luciferase assays, NF-κB-mediated pro-inflammatory gene expression, and NF-κB nuclear translocation after activation of PXR by PA. In vivo, colonic mPXR and NF-κB signalling were analysed to assess PA-mediated the protective effect against dextran sulphate sodium (DSS)-induced colitis. Furthermore, pharmacological inhibition of PXR was further evaluated by examining PA protection against DSS-induced colitis.

RESULTS

PA induced CYP3A4 expression and activity via an hPXR-dependent mechanism. PA-mediated PXR activation attenuated inflammation by inhibiting NF-κB activity and nuclear translocation. The anti-inflammatory effect of PA on NF-κB was abolished by PXR knockdown. PA prevented DSS-induced inflammation by regulating PXR/NF-κB signalling, whereas pharmacological PXR inhibition abated PA-mediated suppressive effects on NF-κB inflammation signalling.

CONCLUSIONS

PA activates PXR signalling and suppresses NF-κB signalling, consequently causing amelioration of inflammation. Our results highlight the importance of PXR-NF-κB crosstalk in colitis and suggest a novel therapeutic reagent.

Inhibitory Effects of Endogenous Linoleic Acid and Glutaric Acid on the Renal Glucuronidation of Berberrubine in Mice and on Recombinant Human UGT1A7, 1A8, and 1A9

Berberrubine (BRB) has a strong lipid-lowering effect and can be extensively metabolized into berberrubine-9-O-β-d-glucuronide (BRBG) in vivo. Recently, pharmacokinetics studies showed that the production of BRBG was significantly decreased in the urine of mice fed with a high-fat diet (HFD), indicating a decreased glucuronidation capacity. Based on the UDP-glucuronosyltransferase (UGT) isoform identification, hepatic and renal microsomal incubation, glucuronidation was examined to suggest the metabolism of BRB in liver and kidneys. The results showed that the renal UGT activity for metabolizing BRB markedly decreased, which may be highly related to the decreased expression and activity of renal Ugt1a7c. Surprisingly, in vitro studies revealed neither BRB nor BRBG inhibited the renal UGT activity. By employing an integrated strategy of metabolomics and pharmacokinetics, we identified and confirmed for the first time the inhibitory effect of some potential endogenous molecules on the renal glucuronidation of C57BL/6J mice, such as glutaric acid (GA) and linoleic acid (LA). By employing recombinant human UGTs, we found that GA and LA efficiently affect the activity of recombinant human UGT1A7, 1A9, and 1A8 at their normal or abnormal physiologic levels in vivo. GA (2 mM) markedly inhibited the activity of UGT1A7 by 89.4% and UGT1A9 by 32.8%. The inhibition rates reached 99.3% for UGT1A9, 48.3% for UGT1A7, and 46.8% for UGT1A8 with LA at 200 μM. It has been suggested that the endogenous molecules have the potential to affect the efficiency of glucuronidation, which might be a key factor contributing to individual differences in drug metabolism.

Bacterial Outer Membrane Vesicles from Dextran Sulfate Sodium-Induced Colitis Differentially Regulate Intestinal UDP-Glucuronosyltransferase 1A1 Partially Through Toll-Like Receptor 4/Mitogen-Activated Protein Kinase/Phosphatidylinositol 3-Kinase Pathway

UDP-glucuronosyltransferase 1A1 (UGT1A1) constitutes an important part of intestinal epithelial barrier and catalyzes glucuronidation of many endogenous compounds and drugs. Downregulation of UGT1A1 in inflammation has been reported, whereas the association with gut dysbiosis is poorly defined. This study verified the involvement of gut microbiota in intestinal UGT1A1 regulation using dextran sulfate sodium (DSS)-induced rat colitis model plus fecal microbiota transplantation (FMT). Generally, both DSS induction and colitis-to-normal FMT suppressed mRNA and protein expressions of UGT1A1 and nuclear xenobiotic receptors (NRs) in colon, but enhanced mRNA and decreased protein of rat UGT1A1/rat NRs in small intestine. Normal-to-colitis FMT alleviated DSS-induced changes. Bacterial outer membrane vesicles (OMVs) from colitis rats and rats receiving colitis feces reduced both mRNA and protein of human UGT1A1 (hUGT1A1)/human NRs (hNRs) in Caco-2 cells. Interestingly, using deoxycholate to reduce lipopolysaccharide, normal OMVs upregulated hUGT1A1/hNRs, whereas colitis OMVs decreased, indicating the involvement of other OMVs components in UGT1A1 regulation. The 10- to 50-kDa fractions from both normal and colitis OMVs downregulated hUGT1A1, human PXR, and human PPAR-γ, whereas >50-kDa fractions from normal rats upregulated hUGT1A1 and human CAR. Additionally, the conditioned medium from OMVs-stimulated rat primary macrophages also reduced hUGT1A1/hNRs expression. Both Toll-like receptor (TLR)2 and TLR4 were activated by DSS, colitis-to-normal FMT, and the opposite, whereas only TLR4 was increased in OMVs-treated cells. TLR4 small interfering RNA blocked hUGT1A1/hNRs downregulation and phosphatidylinositol 3-kinase/Akt, extracellular signal-regulated kinase, and nuclear factor κB phosphorylation evoked by bacterial OMVs. Taken together, this study demonstrated that gut microbiota regulate intestinal UGT1A1 partially through secreting OMVs, which interact with intestinal epithelial cells directly or via activating macrophage.

Disturbance of Mammary UDP-Glucuronosyltransferase Represses Estrogen Metabolism and Exacerbates Experimental Breast Cancer

The progression of breast cancer is closely related to the levels of estrogens within the body. UDP-glucuronosyltransferase (UGT) is an important class of phase II metabolizing enzymes, playing a pivotal role in detoxifying steroid hormone. In the present study, we aim at uncovering the potential dysregulation pattern of UGT and its role in estrogen metabolism and in the pathogenesis of breast cancer. Female Sprague-Dawley rats were treated with 100 mg/kg dimethylbenz(a)anthracene (DMBA) to induce breast cancer. Our results showed that the expression and activity of UGT in mammary tissues were downregulated significantly in DMBA rats. Consistent with this, levels of estradiol, 4-hydroxylated estradiol, and 2-hydroxylated estradiol were increased in both mammary tissues and serum, supporting a notable accumulation of toxic estrogen species in the target tissue of breast cancer. In addition, we also observed the decreased cell migration, cell proliferation, and DNA damage in UGT-transfected MCF-7 cells, suggesting a protective role of UGT against estrogen-induced mammary carcinogenesis. Taken together, these results indicated that accumulation of estrogens induced by UGT deficiency is a critical factor to induce the development of breast cancer. UGT contributes to estrogen elimination, and its glucuronidation capacity influences the estrogen signaling pathway and the pathogenesis of breast cancer.

UDP-glucuronosyltransferases (UGTs) and their related metabolic cross-talk with internal homeostasis: A systematic review of UGT isoforms for precision medicine

UDP-glucuronosyltransferases (UGTs) are the primary phase II enzymes catalyzing the conjugation of glucuronic acid to the xenobiotics with polar groups for facilitating their clearance. The UGTs belong to a superfamily that consists of diverse isoforms possessing distinct but overlapping metabolic activity. The abnormality or deficiency of UGTs in vivo is highly associated with some diseases, efficacy and toxicity of drugs, and precisely therapeutic personality. Despite the great effects and fruitful results achieved, to date, the expression and functions of individual UGTs have not been well clarified, the inconsistency of UGTs is often observed in human and experimental animals, and the complex regulation factors affecting UGTs have not been systematically summarized. This article gives an overview of updated reports on UGTs involving the various regulatory factors in terms of the genetic, environmental, pathological, and physiological effects on the functioning of individual UGTs, in turn, the dysfunction of UGTs induced disease risk and endo- or xenobiotic metabolism-related toxicity. The complex cross-talk effect of UGTs with internal homeostasis is systematically summarized and discussed in detail, which would be of great importance for personalized precision medicine.

Constitutive androstane receptor regulates the intestinal mucosal response to injury

BACKGROUND AND PURPOSE

The pathogenesis of the inflammatory bowel diseases (IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), involves aberrant interactions between a genetically susceptible individual, their microbiota and environmental factors. Alterations in xenobiotic receptor expression and function are associated with increased risk for IBD. Here, we have assessed the role of the constitutive androstane receptor (CAR), a xenobiotic receptor closely related to the pregnane X receptor, in the regulation of intestinal mucosal homeostasis.

EXPERIMENTAL APPROACH

CAR expression was assessed in intestinal mucosal biopsies obtained from CD and UC patients, and in C57/Bl6 mice exposed to dextran sulphate sodium (DSS; 3.5% w/v in drinking water) to evoke intestinal inflammation and tissue damage. CAR-deficient mice were exposed to DSS and mucosal healing assessed. Modulation of wound healing by CAR was assessed in vitro. The therapeutic potential of CAR activation was evaluated, using 3,3',5,5'-tetrachloro-1,4-bis(pyridyloxy)benzene (TCPOBOP), a selective rodent CAR agonist.

KEY RESULTS

CAR expression was reduced in CD and UC samples, compared with expression in healthy controls. This was reproduced in our DSS studies, where CAR expression was reduced in colitic mice. CAR-deficient mice exhibited reduced healing following DSS exposure. In vitro, CAR activation accelerated intestinal epithelial wound healing by enhancing cell migration. Lastly, treating mice with TCPOBOP, following induction of colitis, enhanced mucosal healing.

CONCLUSION AND IMPLICATIONS

Our results support the notion that xenobiotic sensing is altered during intestinal inflammation, and suggest that CAR activation may prove effective in enhancing mucosal healing in patients with IBD.

Pharmacokinetic alterations of rhubarb anthraquinones in experimental colitis induced by dextran sulfate sodium in the rat

ETHNOPHARMACOLOGICAL RELEVANCE

Rhubarb (Rhei Rhizoma et Radix) is used for the treatment of digestive diseases in traditional medicinal practice in China. Recent studies also support its beneficial activities in alleviating ulcerative colitis (UC).

AIM OF THE STUDY

This study aimed to characterize the oral pharmacokinetics of rhubarb anthraquinones, the main bioactive components of this herb, in the experimental chronic colitis rat model induced by dextran sulfate sodium (DSS) and to identify the factors causing the pharmacokinetic alterations.

MATERIALS AND METHODS

Rats received drinking water (normal group) or 5% DSS for the first 7 days and 3% DSS for additional 14 days (UC group). On day 21 both groups received an oral dose of the rhubarb extract (equivalent to 5.0g crude drug/kg body weight). Plasma anthraquinone aglycones levels were determined directly by an LC-MS/MS method and the total of each anthraquinone (aglycone+conjugates) was quantified after β-glucuronidases hydrolysis.

RESULTS

Rhubarb anthraquinones predominantly existed as conjugates in plasma samples from both groups and only free aloe-emodin, rhein and emodin were detected. Compared to the normal rats, both C_max and AUC of the three free anthraquinones were increased, while the systemic exposure (AUC) of the total (aglycone+conjugates) of most anthraquinones decreased by UC accompanied by the disappearance of multiple-peak phenomenon in the plasma concentration-time profiles. Gut bacteria from UC rats exhibited a decreased activity in hydrolyzing anthraquinone glycosides to form respective aglycone and there were significant decreases in microbial β-glucosidases and β-glucuronidases activities. Moreover, the intestinal microsomes from UC rats catalyzed glucuronidation of free anthraquinones with higher activities, while the activities of hepatic microsomes were comparable to normal rats.

CONCLUSIONS

The decreases of β-glucuronidases activity in DSS-induced chronic rat colitis should mainly account for the decreases in systemic exposure and abrogation of enterohepatic recirculation of most rhubarb anthraquinones after oral intake.

Insight into the pharmacokinetic behavior of tanshinone IIA in the treatment of Crohn's disease: comparative data for tanshinone IIA and its two glucuronidated metabolites in normal and recurrent colitis models after oral administration

1. Previous reports implied that tanshinone IIA (TSA) may offer potential benefits for Crohn's disease (CD). However, the detailed pharmacokinetic behavior of TSA in the treatment of colitis remain unclear. Herein, a recurrent trinitrobenzene sulfonic acid (TNBS)-colitis mouse model was used to investigate whether TSA possesses favorable pharmacokinetic and colonic distribution profiles to serve as a candidate drug. 2. Although the systemic TSA exposures were low (AUC_0-t approximately 330 ng*h/ml) in both the normal and colitis models after oral administration TSA 20 mg/kg, high levels of TSA were found in the gastrointestinal tract (GI). Such a GI exposure of TSA in colitis mice is adequate to exert anti-inflammatory effects as observed in various in vitro studies. 3. Interestingly, colonic TSA exposure in the colitis mouse model was much lower than that in the normal mice, which may be explained by a significant upregulation of colonic UDP-glucuronosyltransferase (Ugt)1a9 expression and a higher plasma concentration of TSA glucuronides in the model mice at 0.5, 1 and 2 h after TSA administration. 4. Together, these results reveal high accumulation at the site of inflammation and minimal systemic concentration of TSA, which are favorable pharmacokinetic behaviors to meet the requirements for CD treatment.

Chronic inflammation up-regulates P-gp in peripheral mononuclear blood cells via the STAT3/Nf-κb pathway in 2,4,6-trinitrobenzene sulfonic acid-induced colitis mice

Patients with inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis, often suffer drug intolerance. This resistance can be divided into intrinsic resistance and acquired resistance. Although there is agreement on acquired resistance, studies regarding intrinsic resistance have demonstrated inconsistencies, especially for Crohn’s disease. For this reason, an animal model of Crohn’s disease was induced with 2,4,6-trinitrobenzene sulfonic acid solution (TNBS), and intrinsic resistance was analyzed by measuring the function and expression of P-glycoprotein (P-gp) in peripheral mononuclear blood cells (PMBC), followed by mechanistic studies. The results revealed reduced retention of cyclosporine A in PMBC over-expressing P-gp in a TNBS-treated group and enhanced secretion of the cytokines IL-1β, IL-6, IL-17, and TNF-α as well as LPS in plasma. These cytokines and LPS can induce P-gp expression through the STAT3/Nf-κb pathway, contributing to a decrease of cyclosporine A retention, which can be reversed by the application of a P-gp inhibitor. Our results demonstrated that the sustained chronic inflammation could induce the intrinsic resistance presented as P-gp over-expression in PBMC in Crohn’s disease through STAT3/Nf-κb pathway and this resistance might be reversed by combinational usage of P-gp inhibitors.

PPARα-UGT axis activation represses intestinal FXR-FGF15 feedback signalling and exacerbates experimental colitis

Bile acids play a pivotal role in the pathological development of inflammatory bowel disease (IBD). However, the mechanism of bile acid dysregulation in IBD remains unanswered. Here we show that intestinal peroxisome proliferator-activated receptor α (PPARα)-UDP-glucuronosyltransferases (UGTs) signalling is an important determinant of bile acid homeostasis. Dextran sulphate sodium (DSS)-induced colitis leads to accumulation of bile acids in inflamed colon tissues via activation of the intestinal peroxisome PPARα-UGTs pathway. UGTs accelerate the metabolic elimination of bile acids, and thereby decrease their intracellular levels in the small intestine. Reduced intracellular bile acids results in repressed farnesoid X receptor (FXR)-FGF15 signalling, leading to upregulation of hepatic CYP7A1, thus promoting the de novo bile acid synthesis. Both knockout of PPARα and treatment with recombinant FGF19 markedly attenuate DSS-induced colitis. Thus, we propose that intestinal PPARα-UGTs and downstream FXR-FGF15 signalling play vital roles in control of bile acid homeostasis and the pathological development of colitis.

Bile acids have been linked to the development of inflammatory bowel diseases, such as colitis. Here the authors show that bile acid levels in mice are controlled by a circular feedback system involving the nuclear receptors PPARα and FXR, and that this system is dysregulated in colitis.