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Tilg H, Adolph TE, Trauner M. Gut-liver axis: Pathophysiological concepts and clinical implications. Cell Metab 2022; 34:1700-1718. [PMID: 36208625 DOI: 10.1016/j.cmet.2022.09.017] [Citation(s) in RCA: 152] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/17/2022] [Accepted: 09/16/2022] [Indexed: 02/07/2023]
Abstract
Bidirectional crosstalk along the gut-liver axis controls gastrointestinal health and disease and exploits environmental and host mediators. Nutrients, microbial antigens, metabolites, and bile acids regulate metabolism and immune responses in the gut and liver, which reciprocally shape microbial community structure and function. Perturbation of such host-microbe interactions is observed in a variety of experimental liver diseases and is facilitated by an impaired intestinal barrier, which is fueling hepatic inflammation and disease progression. Clinical evidence describes perturbation of the gut-liver crosstalk in non-alcoholic fatty liver disease, alcoholic liver disease, and primary sclerosing cholangitis. In liver cirrhosis, a common sequela of these diseases, the intestinal microbiota and microbial pathogen-associated molecular patterns constitute liver inflammation and clinical complications, such as hepatic encephalopathy. Understanding the intricate metabolic interplay between the gut and liver in health and disease opens an avenue for targeted therapies in the future, which is probed in controlled clinical trials.
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Affiliation(s)
- Herbert Tilg
- Department of Internal Medicine I, Gastroenterology, Hepatology, Endocrinology & Metabolism, Medical University, Innsbruck, Austria.
| | - Timon E Adolph
- Department of Internal Medicine I, Gastroenterology, Hepatology, Endocrinology & Metabolism, Medical University, Innsbruck, Austria
| | - Michael Trauner
- Division of Gastroenterology & Hepatology, Department of Internal Medicine III, Medical University, Vienna, Austria
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2
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Duan S, Li X, Fan G, Liu R. Targeting bile acid signaling for the treatment of liver diseases: From bench to bed. Biomed Pharmacother 2022; 152:113154. [PMID: 35653887 DOI: 10.1016/j.biopha.2022.113154] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/13/2022] [Accepted: 05/15/2022] [Indexed: 11/02/2022] Open
Abstract
Liver diseases and related complications have become one of the leading causes of morbidity and mortality worldwide, yet effective medicine or approved treatment approach is still limited. Thus, novel therapy is urgently required to prevent or at least slow down the growing burden of liver transplantation or even death caused by malignant liver diseases. As the irreplaceable modulator of hepatic and intestinal signaling cascades, bile acids (BAs) play complex physiological as well as pathological roles in regulating energy and immune homeostasis in various liver diseases, including but not limited to metabolic diseases and cholangiopathies, making them highly attractive therapeutic targets. In the current review, recent progress in the research of enterohepatic circulation of BAs and potential therapeutic targets of BAs signaling, especially the development of currently available treatments, including agonizts of FXR and TGR5, analogs of FGF19, inhibitors of ASBT, and the regulation of gut microbiome through fecal microbiota transplantation were extensively summarized. Their protective effects, molecular mechanisms, and outcomes of clinical trials were highlighted. The structural features of these candidates and perspectives for their future development were further discussed. In conclusion, we believe that pharmacological therapies targeting BAs signaling represent promising and efficient strategies for the treatment of complex and multifactorial liver disorders.
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Affiliation(s)
- Shuni Duan
- School of Materia Medica, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing 100029, China
| | - Xiaojiaoyang Li
- School of Life Sciences, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing 100029, China
| | - Guifang Fan
- School of Materia Medica, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing 100029, China
| | - Runping Liu
- School of Materia Medica, Beijing University of Chinese Medicine, 11 Bei San Huan Dong Lu, Beijing 100029, China.
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3
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Guthrie G, Vonderohe C, Burrin D. Fibroblast growth factor 15/19 expression, regulation, and function: An overview. Mol Cell Endocrinol 2022; 548:111617. [PMID: 35301051 PMCID: PMC9038700 DOI: 10.1016/j.mce.2022.111617] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 01/18/2022] [Indexed: 12/12/2022]
Abstract
Since the discovery of fibroblast growth factor (FGF)-19 over 20 years ago, our understanding of the peptide and its role in human biology has moved forward significantly. A member of a superfamily of paracrine growth factors regulating embryonic development, FGF19 is unique in that it is a dietary-responsive endocrine hormone linked with bile acid homeostasis, glucose and lipid metabolism, energy expenditure, and protein synthesis during the fed to fasted state. FGF19 achieves this through targeting multiple tissues and signaling pathways within those tissues. The diverse functional capabilities of FGF19 is due to the unique structural characteristics of the protein and its receptor binding in various cell types. This review will cover the current literature on the protein FGF19, its target receptors, and the biological pathways they target through unique signaling cascades.
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Affiliation(s)
- Greg Guthrie
- USDA-ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, United States
| | - Caitlin Vonderohe
- USDA-ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, United States
| | - Douglas Burrin
- USDA-ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, United States.
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4
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Nguyen PTTT, Pagé-Larivière F, Williams K, O'Brien J, Crump D. Developmental and Hepatic Gene Expression Changes in Chicken Embryos Exposed to p-Tert-Butylphenyl Diphenyl Phosphate and Isopropylphenyl Phosphate via Egg Injection. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:739-747. [PMID: 34913512 DOI: 10.1002/etc.5274] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
Organophosphate flame retardants (OPFRs) are used in a variety of products such as clear coats, resins, and plastics; however, research into their toxicological effects is limited. p-Tert-butylphenyl diphenyl phosphate (BPDP) and isopropylphenyl phosphate (IPPP) are two OPFRs that were prioritized for whole-animal toxicological studies based on observed effects in cultured avian hepatocytes in a previous study. The present study investigates the toxicity of BPDP and IPPP in chicken embryos at different developmental stages by evaluating morphological and gene expression endpoints. Chicken eggs were exposed via air cell injection to 0-250 μg/g (nominal) of either compound and then artificially incubated. At day 11 (midincubation), liver samples were collected for mRNA expression analysis; and at day 20 (1 day prehatch), morphological measurements and liver samples for transcriptomic evaluation were collected. At 250 μg/g, gallbladder size was significantly reduced for both compounds, head/bill length and tarsus length were significantly decreased, and liver somatic index was significantly increased following IPPP exposure only. No effects on mortality were observed up to the highest administered concentration for either chemical. Using a ToxChip polymerase chain reaction array, we report significant differences in hepatic gene expression for both compounds and time points; the most pronounced transcriptomic effects occurred at midincubation. Genes related to xenobiotic metabolism, bile acid/cholesterol regulation, and oxidative stress were significantly dysregulated. Given these changes observed throughout avian embryonic development, further research into the long-term effects of BPDP and IPPP are warranted, especially as they pertain to liver cholestasis. Environ Toxicol Chem 2022;41:739-747. © 2021 Her Majesty the Queen in Right of Canada. Environmental Toxicology and Chemistry © 2021 SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.
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Affiliation(s)
- Phuoc Tyler T-T Nguyen
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada
- Carleton University, Ottawa, Ontario, Canada
| | - Florence Pagé-Larivière
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada
| | - Kim Williams
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada
| | - Jason O'Brien
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada
- Carleton University, Ottawa, Ontario, Canada
| | - Doug Crump
- National Wildlife Research Centre, Environment and Climate Change Canada, Ottawa, Ontario, Canada
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5
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Bhat N, Esteghamat F, Chaube BK, Gunawardhana K, Mani M, Thames C, Jain D, Ginsberg HN, Fernandes-Hernando C, Mani A. TCF7L2 transcriptionally regulates Fgf15 to maintain bile acid and lipid homeostasis through gut-liver crosstalk. FASEB J 2022; 36:e22185. [PMID: 35133032 PMCID: PMC9624374 DOI: 10.1096/fj.202101607r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/10/2022] [Accepted: 01/18/2022] [Indexed: 12/13/2022]
Abstract
FGF19/FGF15 is an endocrine regulator of hepatic bile salt and lipid metabolism, which has shown promising effects in the treatment of NASH in clinical trials. FGF19/15 is transcribed and released from enterocytes of the small intestine into enterohepatic circulation in response to bile-induced FXR activation. Previously, the TSS of FGF19 was identified to bind Wnt-regulated TCF7L2/encoded transcription factor TCF4 in colorectal cancer cells. Impaired Wnt signaling and specifical loss of function of its coreceptor LRP6 have been associated with NASH. We, therefore, examined if TCF7L2/TCF4 upregulates Fgf19 in the small intestine and restrains NASH through gut-liver crosstalk. We examined the mice globally overexpressing, haploinsufficient, and conditional knockout models of TCF7L2 in the intestinal epithelium. The TCF7L2+/- mice exhibited increased plasma bile salts and lipids and developed diet-induced fatty liver disease while mice globally overexpressing TCF7L2 were protected against these traits. Comprehensive in vivo analysis revealed that TCF7L2 transcriptionally upregulates FGF15 in the gut, leading to reduced bile synthesis and diminished intestinal lipid uptake. Accordingly, VilinCreert2 ; Tcf7L2fl/fl mice showed reduced Fgf19 in the ileum, and increased plasma bile. The global overexpression of TCF7L2 in mice with metabolic syndrome-linked LRP6R611C substitution rescued the fatty liver and fibrosis in the latter. Strikingly, the hepatic levels of TCF4 were reduced and CYP7a1 was increased in human NASH, indicating the relevance of TCF4-dependent regulation of bile synthesis to human disease. These studies identify the critical role of TCF4 as an upstream regulator of the FGF15-mediated gut-liver crosstalk that maintains bile and liver triglyceride homeostasis.
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Affiliation(s)
- Neha Bhat
- Department of Internal Medicine, Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Fatemehsadat Esteghamat
- Department of Internal Medicine, Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Bal Krishna Chaube
- Department of Comparative Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Kushan Gunawardhana
- Department of Internal Medicine, Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Mitra Mani
- New York Medical College, Valhalla, New York, USA,Department of Internal Medicine, Columbia University College of Physicians and Surgeon, New York, New York, USA
| | - Clay Thames
- Department of Internal Medicine, Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Dhanpat Jain
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Henry N. Ginsberg
- Department of Internal Medicine, Columbia University College of Physicians and Surgeon, New York, New York, USA
| | | | - Arya Mani
- Department of Internal Medicine, Cardiovascular Research Center, Yale University School of Medicine, New Haven, Connecticut, USA,Department of Genetics, Yale School of Medicine, New Haven, Connecticut, USA
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The Role of Fibroblast Growth Factor 19 in Hepatocellular Carcinoma. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1180-1192. [PMID: 34000282 DOI: 10.1016/j.ajpath.2021.04.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 04/09/2021] [Accepted: 04/22/2021] [Indexed: 12/12/2022]
Abstract
Hepatocellular carcinoma (HCC) is the fifth most common type of cancer and the third leading cause of cancer-related deaths worldwide. Liver resection or liver transplantation is the most effective therapy for HCC because drugs approved by the US Food and Drug Administration to treat patients with unresectable HCC have an unfavorable overall survival rate. Therefore, the development of biomarkers for early diagnosis and effective therapy strategies are still necessary to improve patient outcomes. Fibroblast growth factor (FGF) 19 was amplified in patients with HCC from various studies, including patients from The Cancer Genome Atlas. FGF19 plays a syngeneic function with other signaling pathways in primary liver cancer development, such as epidermal growth factor receptor, Wnt/β-catenin, the endoplasmic reticulum-related signaling pathway, STAT3/IL-6, RAS, and extracellular signal-regulated protein kinase, among others. The current review presents a comprehensive description of the FGF19 signaling pathway involved in liver cancer development. The use of big data and bioinformatic analysis can provide useful clues for further studies of the FGF19 pathway in HCC, including its application as a biomarker, targeted therapy, and combination therapy strategies.
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Lang L, Shull AY, Teng Y. Interrupting the FGF19-FGFR4 Axis to Therapeutically Disrupt Cancer Progression. Curr Cancer Drug Targets 2020; 19:17-25. [PMID: 29557750 DOI: 10.2174/1568009618666180319091731] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 09/01/2017] [Accepted: 10/10/2017] [Indexed: 02/07/2023]
Abstract
Coordination between the amplification of the fibroblast growth factor FGF19, overexpression of its corresponding receptor FGFR4, and hyperactivation of the downstream transmembrane enzyme β-klotho has been found to play pivotal roles in mediating tumor development and progression. Aberrant FGF19-FGFR4 signaling has been implicated in driving specific tumorigenic events including cancer cell proliferation, apoptosis resistance, and metastasis by activating a myriad of downstream signaling cascades. As an attractive target, several strategies implemented to disrupt the FGF19-FGFR4 axis have been developed in recent years, and FGF19-FGFR4 binding inhibitors are being intensely evaluated for their clinical use in treating FGF19-FGFR4 implicated cancers. Based on the established work, this review aims to detail how the FGF19-FGFR4 signaling pathway plays a vital role in cancer progression and why disrupting communication between FGF19 and FGFR4 serves as a promising therapeutic strategy for disrupting cancer progression.
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Affiliation(s)
- Liwei Lang
- Department of Oral Biology, Augusta University, Augusta, GA 30912, United States
| | - Austin Y Shull
- Department of Biology, Presbyterian College, Clinton, SC 29325, United States
| | - Yong Teng
- Department of Oral Biology, Augusta University, Augusta, GA 30912, United States.,Georgia Cancer Center, Augusta University, Augusta, GA 30912, United States.,Department of Biochemistry & Molecular Biology, Augusta University, Augusta, GA 30912, United States
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8
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Gadaleta RM, Moschetta A. Metabolic Messengers: fibroblast growth factor 15/19. Nat Metab 2019; 1:588-594. [PMID: 32694803 DOI: 10.1038/s42255-019-0074-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 05/07/2019] [Indexed: 12/13/2022]
Abstract
Fibroblast growth factor (FGF) 15 in mice and its human orthologue FGF19 (together denoted FGF15/19) are gut hormones that control homeostasis of bile acids and glucose during the transition from the fed to the fasted state. Apart from its central role in the regulation of bile acid homeostasis, FGF15/19 is now recognized as a transversal metabolic coordinator at the crossroads of the gut, liver, brain and white adipose tissue. Dysregulation of FGF15/19 signalling may contribute to the pathogenesis of several diseases affecting the gut-liver axis and to metabolic diseases. Here, we provide an overview of current knowledge of the physiological roles of the enterokine FGF15/19 and highlight commonalities and differences between the two orthologues. We also discuss the putative therapeutic potential in areas of unmet medical need-such has cholestatic liver diseases and non-alcoholic steatohepatitis, for which FGF19 is being tested in ongoing clinical trials-as well as the possibility of using FGF19 for the treatment of obesity and type II diabetes.
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Affiliation(s)
| | - Antonio Moschetta
- Department of Interdisciplinary Medicine, University of Bari 'Aldo Moro', Bari, Italy.
- National Cancer Center, IRCCS IstitutoTumori 'Giovanni Paolo II', Bari, Italy.
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9
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Khan TJ, Hasan MN, Azhar EI, Yasir M. Association of gut dysbiosis with intestinal metabolites in response to antibiotic treatment. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.humic.2018.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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10
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Somm E, Jornayvaz FR. Fibroblast Growth Factor 15/19: From Basic Functions to Therapeutic Perspectives. Endocr Rev 2018; 39:960-989. [PMID: 30124818 DOI: 10.1210/er.2018-00134] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/10/2018] [Indexed: 12/11/2022]
Abstract
Discovered 20 years ago, fibroblast growth factor (FGF)19, and its mouse ortholog FGF15, were the first members of a new subfamily of FGFs able to act as hormones. During fetal life, FGF15/19 is involved in organogenesis, affecting the development of the ear, eye, heart, and brain. At adulthood, FGF15/19 is mainly produced by the ileum, acting on the liver to repress hepatic bile acid synthesis and promote postprandial nutrient partitioning. In rodents, pharmacologic doses of FGF19 induce the same antiobesity and antidiabetic actions as FGF21, with these metabolic effects being partly mediated by the brain. However, activation of hepatocyte proliferation by FGF19 has long been a challenge to its therapeutic use. Recently, genetic reengineering of the molecule has resolved this issue. Despite a global overlap in expression pattern and function, murine FGF15 and human FGF19 exhibit several differences in terms of regulation, molecular structure, signaling, and biological properties. As most of the knowledge originates from the use of FGF19 in murine models, differences between mice and humans in the biology of FGF15/19 have to be considered for a successful translation from bench to bedside. This review summarizes the basic knowledge concerning FGF15/19 in mice and humans, with a special focus on regulation of production, morphogenic properties, hepatocyte growth, bile acid homeostasis, as well as actions on glucose, lipid, and energy homeostasis. Moreover, implications and therapeutic perspectives concerning FGF19 in human diseases (including obesity, type 2 diabetes, hepatic steatosis, biliary disorders, and cancer) are also discussed.
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Affiliation(s)
- Emmanuel Somm
- Service of Endocrinology, Diabetes, Hypertension, and Nutrition, Geneva University Hospitals, University of Geneva Medical School, Geneva, Switzerland
| | - François R Jornayvaz
- Service of Endocrinology, Diabetes, Hypertension, and Nutrition, Geneva University Hospitals, University of Geneva Medical School, Geneva, Switzerland
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Shan Z, Alvarez-Sola G, Uriarte I, Arechederra M, Fernández-Barrena MG, Berasain C, Ju C, Avila MA. Fibroblast growth factors 19 and 21 in acute liver damage. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:257. [PMID: 30069459 DOI: 10.21037/atm.2018.05.26] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Currently there are very few pharmacological options available to treat acute liver injury. Because its natural exposure to noxious stimuli the liver has developed a strong endogenous hepatoprotective capacity. Indeed, experimental evidence exposed a variety of endogenous hepatic and systemic responses naturally activated to protect the hepatic parenchyma and to foster liver regeneration, therefore preserving individual's survival. The fibroblast growth factor (FGF) family encompasses a range of polypeptides with important effects on cellular differentiation, growth survival and metabolic regulation in adult organisms. Among these FGFs, FGF19 and FGF21 are endocrine hormones that profoundly influence systemic metabolism but also exert important hepatoprotective activities. In this review, we revisit the biology of these factors and highlight their potential application for the clinical management of acute liver injury.
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Affiliation(s)
- Zhao Shan
- Department of Anesthesiology, McGovern Medical School, University of Texas Health Science Center at Houston, TX, USA
| | - Gloria Alvarez-Sola
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,CIBERehd, Carlos III Institute of Health, Pamplona, Spain
| | - Iker Uriarte
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,CIBERehd, Carlos III Institute of Health, Pamplona, Spain
| | - María Arechederra
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,CIBERehd, Carlos III Institute of Health, Pamplona, Spain
| | - Maite G Fernández-Barrena
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,CIBERehd, Carlos III Institute of Health, Pamplona, Spain
| | - Carmen Berasain
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,CIBERehd, Carlos III Institute of Health, Pamplona, Spain.,Instituto de Investigaciones Sanitarias de Navarra (IDISNA), Pamplona, Spain
| | - Cynthia Ju
- Department of Anesthesiology, McGovern Medical School, University of Texas Health Science Center at Houston, TX, USA
| | - Matías A Avila
- Hepatology Program, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.,CIBERehd, Carlos III Institute of Health, Pamplona, Spain.,Instituto de Investigaciones Sanitarias de Navarra (IDISNA), Pamplona, Spain
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12
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Liu S, Marcelin G, Blouet C, Jeong JH, Jo YH, Schwartz GJ, Chua S. A gut-brain axis regulating glucose metabolism mediated by bile acids and competitive fibroblast growth factor actions at the hypothalamus. Mol Metab 2017; 8:37-50. [PMID: 29290621 PMCID: PMC5985052 DOI: 10.1016/j.molmet.2017.12.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/27/2017] [Accepted: 12/05/2017] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE Bile acids have been implicated as important regulators of glucose metabolism via activation of FXR and GPBAR1. We have previously shown that FGF19 can modulate glucose handling by suppressing the activity of hypothalamic AGRP/NPY neurons. As bile acids stimulate the release of FGF19/FGF15 into the circulation, we pursued the potential of bile acids to improve glucose tolerance via a gut-brain axis involving FXR and FGF15/FGF19 within enterocytes and FGF receptors on hypothalamic AGRP/NPY neurons. METHODS A 5-day gavage of taurocholic acid, mirroring our previous protocol of a 5-day FGF19 treatment, was performed. Oral glucose tolerance tests in mice with genetic manipulations of FGF signaling and melanocortin signaling were used to define a gut-brain axis responsive to bile acids. RESULTS The taurocholic acid gavage led to increased serum concentrations of taurocholic acid as well as increases of FGF15 mRNA in the ileum and improved oral glucose tolerance in obese (ob/ob) mice. In contrast, lithocholic acid, an FXR antagonist but a potent agonist for GPBAR1, did not improve glucose tolerance. The positive response to taurocholic acid is dependent upon an intact melanocortinergic system as obese MC4R-null mice or ob/ob mice without AGRP did not show improvements in glucose tolerance after taurocholate gavage. We also tested the FGF receptor isoform necessary for the bile acid response, using AGRP:Fgfr1-/- and AGRP:Fgfr2-/- mice. While the absence of FGFR1 in AGRP/NPY neurons did not alter glucose tolerance after taurocholate gavage, manipulations of Fgfr2 caused bidirectional changes depending upon the experimental model. We hypothesized the existence of an endogenous hypothalamic FGF, most likely FGF17, that acted as a chronic activator of AGRP/NPY neurons. We developed two short peptides based on FGF8 and FGF17 that should antagonize FGF17 action. Both of these peptides improved glucose homeostasis after a 4-day course of central and peripheral injections. Significantly, daily average blood glucose from continuous glucose monitoring was reduced in all tested animals but glucose concentrations remained in the euglycemia range. CONCLUSIONS We have defined a gut-brain axis that regulates glucose metabolism mediated by antagonistic fibroblast growth factors. From the intestine, bile acids stimulate FGF15 secretion, leading to activation of the FGF receptors in hypothalamic AGRP/NPY neurons. FGF receptor intracellular signaling subsequently silences AGRP/NPY neurons, leading to improvements of glucose tolerance that are likely mediated by the autonomic nervous system. Finally, short peptides that antagonize homodimeric FGF receptor signaling within the hypothalamus have beneficial effects on glucose homeostasis without inducing hypoglycemia. These peptides could provide a new mode of regulating glucose metabolism.
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Affiliation(s)
- Shunmei Liu
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Genevieve Marcelin
- INSERM UMR S 1166, ICAN Institute, Faculte de Medecine Pitie-Salpetriere, 91 Boulevard de l'Hopital, 75013 Paris, France
| | - Clemence Blouet
- MRC Metabolic Diseases Unit, Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom
| | - Jae Hoon Jeong
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Young-Hwan Jo
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Gary J Schwartz
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Streamson Chua
- Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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13
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Lowered fasting chenodeoxycholic acid correlated with the decrease of fibroblast growth factor 19 in Chinese subjects with impaired fasting glucose. Sci Rep 2017; 7:6042. [PMID: 28729691 PMCID: PMC5519593 DOI: 10.1038/s41598-017-06252-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 06/12/2017] [Indexed: 12/17/2022] Open
Abstract
The gut-derived hormone Fibroblast growth factor 19 (FGF19) could regulate glucose metabolism and is induced by bile acids (BAs) through activating Farnesoid X Receptor (FXR). FGF19 was found to decrease in subjects with isolated-impaired fasting glucose (I-IFG) and type 2 diabetes mellitus (T2DM). However, the reason for the change of FGF19 in subjects with different glucometabolic status remained unclear. Here we measured six BAs including chenodeoxycholic acid (CDCA), cholic acid, deoxycholic acid, their glycine conjugates and FGF19 levels during oral glucose tolerance test (OGTT) in normal glucose tolerance (NGT), isolated-impaired glucose tolerance, I-IFG, combined glucose intolerance (CGI) and T2DM subjects. After OGTT, serum FGF19 peaked at 120 min in all subjects. Glycine conjugated BAs peaked at 30 min, while free BAs did not elevated significantly. Consistent with the decrease trend in FGF19 levels, fasting serum CDCA levels in subjects with I-IFG, CGI and T2DM were significantly lower than NGT subjects (P < 0.05). Fasting serum CDCA was independently associated with FGF19. CDCA strongly upregulated FGF19 mRNA levels in LS174T cells in a dose- and time-dependent manner. These results suggest that the decrease of FGF19 in subjects with I-IFG was at least partially due to their decrease of CDCA acting via FXR.
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14
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Jahn D, Sutor D, Dorbath D, Weiß J, Götze O, Schmitt J, Hermanns HM, Geier A. Farnesoid X receptor-dependent and -independent pathways mediate the transcriptional control of human fibroblast growth factor 19 by vitamin A. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:381-92. [DOI: 10.1016/j.bbagrm.2015.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 11/27/2015] [Accepted: 12/21/2015] [Indexed: 12/11/2022]
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15
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Mechanisms of enterohepatic fibroblast growth factor 15/19 signaling in health and disease. Cytokine Growth Factor Rev 2015; 26:625-35. [DOI: 10.1016/j.cytogfr.2015.07.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 07/17/2015] [Indexed: 01/07/2023]
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16
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Therapeutic potential of the endocrine fibroblast growth factors FGF19, FGF21 and FGF23. Nat Rev Drug Discov 2015; 15:51-69. [PMID: 26567701 DOI: 10.1038/nrd.2015.9] [Citation(s) in RCA: 317] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The endocrine fibroblast growth factors (FGFs), FGF19, FGF21 and FGF23, are critical for maintaining whole-body homeostasis, with roles in bile acid, glucose and lipid metabolism, modulation of vitamin D and phosphate homeostasis and metabolic adaptation during fasting. Given these functions, the endocrine FGFs have therapeutic potential in a wide array of chronic human diseases, including obesity, type 2 diabetes, cancer, and kidney and cardiovascular disease. However, the safety and feasibility of chronic endocrine FGF administration has been challenged, and FGF analogues and mimetics are now being investigated. Here, we discuss current knowledge of the complex biology of the endocrine FGFs and assess how this may be harnessed therapeutically.
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17
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The Bile Acid Chenodeoxycholic Acid Increases Human Brown Adipose Tissue Activity. Cell Metab 2015; 22:418-26. [PMID: 26235421 DOI: 10.1016/j.cmet.2015.07.002] [Citation(s) in RCA: 308] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 04/01/2015] [Accepted: 07/01/2015] [Indexed: 12/17/2022]
Abstract
The interest in brown adipose tissue (BAT) as a target to combat metabolic disease has recently been renewed with the discovery of functional BAT in humans. In rodents, BAT can be activated by bile acids, which activate type 2 iodothyronine deiodinase (D2) in BAT via the G-coupled protein receptor TGR5, resulting in increased oxygen consumption and energy expenditure. Here we examined the effects of oral supplementation of the bile acid chenodeoxycholic acid (CDCA) on human BAT activity. Treatment of 12 healthy female subjects with CDCA for 2 days resulted in increased BAT activity. Whole-body energy expenditure was also increased upon CDCA treatment. In vitro treatment of primary human brown adipocytes derived with CDCA or specific TGR5 agonists increased mitochondrial uncoupling and D2 expression, an effect that was absent in human primary white adipocytes. These findings identify bile acids as a target to activate BAT in humans.
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18
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Abstract
Nonalcoholic fatty liver disease is a common cause of liver related morbidity and mortality. It is closely linked to underlying insulin resistance. It has recently been shown that bile acids modulate insulin signaling and can improve insulin resistance in cell based and animal studies. These effects are mediated in part by activation of farnesoid x receptors by bile acids. In human studies, FXR agonists improve insulin resistance and have recently been shown to improve NAFLD. The basis for the use of FXR agonists for the treatment of NAFLD and early human experience with such agents is reviewed in this paper.
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Affiliation(s)
- Arun J Sanyal
- Virgnia Commonwealth University School of Medicine, Richmond, Va., USA
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19
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Abstract
Obesity is the result of disequilibrium between energy intake and energy expenditure (EE). Successful long-term weight loss is difficult to achieve with current strategies for the correction of this caloric imbalance. Non-shivering thermogenesis (NST) in brown adipose tissue (BAT) is a possible therapeutic target for the prevention and treatment of obesity and associated metabolic diseases. In recent years, more knowledge about the function and stimulation of bat has been obtained. The sympathetic nervous system (SNS) is currently seen as the main effector for brown fat function. Also, interplay between the thyroid axis and SNS plays an important role in BAT thermogenesis. Almost daily new pathways for the induction of BAT thermogenesis and 'browning' of white adipose tissue (WAT) are identified. Especially the activation of BAT via endogenous pathways has received strong scientific attention. Here we will discuss the relevance of several pathways in activating BAT and their implications for the treatment of obesity. In this review we will focus on the discussion of the most promising endocrine and paracrine pathways to stimulate BAT, by factors and pathways that naturally occur in the human body.
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Affiliation(s)
- Evie Broeders
- Department of Human Biology, NUTRIM - School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre , Maastricht , the Netherlands
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20
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Abstract
Chronic diarrhoea induced by bile acids is common and the underlying mechanisms are linked to homeostatic regulation of hepatic bile acid synthesis by fibroblast growth factor 19 (FGF19). Increasing evidence, including that from several large case series using SeHCAT (selenium homocholic acid taurine) tests for diagnosis, indicates that bile acid diarrhoea (BAD) accounts for a sizeable proportion of patients who would otherwise be diagnosed with IBS. Studies of other approaches for diagnosis of BAD have shown increased bile acid synthesis, increased faecal levels of primary bile acids, dysbiosis and different urinary volatile organic compounds when compared with healthy controls or with other diseases. The role of the ileal hormone FGF19 in BAD has been strengthened: a prospective clinical study has confirmed low FGF19 levels in BAD, and so a test to measure these levels could be developed for diagnosis. In animal models, FGF19 depletion by antibodies produces severe diarrhoea. Bile acids affect colonic function through farnesoid X receptor (FXR) and TGR5 receptors. As well as these effects in the colon, FXR-dependent stimulation of ileal FGF19 production could be a logical mechanism to provide therapeutic benefit in BAD. Further studies of FGF19 in humans hold promise in providing novel treatments for this cause of chronic diarrhoea.
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21
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Abstract
PURPOSE OF REVIEW Hepatic bile acid synthesis is controlled, in part, by a complex enterohepatic feedback regulatory mechanism. In this review, we focus on the role of the intestinal FGF15/19 hormone in modulating bile acid levels, and additional metabolic effects on glucose metabolism, nonalcoholic liver disease (NAFLD), and liver regeneration. We also highlight the newly identified intestinal protein, Diet1, which is a modulator of FGF15/19 levels. RECENT FINDINGS Low FGF19 levels are associated with bile acid diarrhea and NAFLD. In contrast, high FGF19 levels are associated with diabetes remission following Roux-en-Y gastric bypass surgery, suggesting new therapeutic approaches against type 2 diabetes. The effect of FGF15/19 on liver plasticity is a double-edged sword: whereas elevated FGF15/19 levels improve survival of mice after partial hepatectomy, FGF19 mitogenic activity is associated with liver carcinoma. Finally, a recent study has identified Diet1, an intestinal factor that influences FGF15/19 levels in mouse intestine and human enterocytes. Diet1 represents the first factor shown to influence FGF15/19 levels at a post-transcriptional level. SUMMARY The biological effects of FGF15/19 make it an attractive target for treating metabolic dysregulation underlying conditions such as fatty liver and type 2 diabetes. Further elucidation of the role of Diet1 in FGF15/19 secretion may provide a control point for the pharmacological modulation of FGF15/19 levels.
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Affiliation(s)
- Karen Reue
- David Geffen School of Medicine at UCLA, Department of Human Genetics, Los Angeles, CA 90095
- David Geffen School of Medicine at UCLA, Department of Medicine, Los Angeles, CA 90095
- Molecular Biology Institute, University of California, Los Angeles, CA 90095
- To whom correspondence should be addressed: Department of Human Genetics, Gonda 6506A, 695 Charles E. Young Drive South, Los Angeles, CA 90095. Tel: (310) 794-5631; Fax: (310) 794-5446;
| | - Jessica M. Lee
- David Geffen School of Medicine at UCLA, Department of Human Genetics, Los Angeles, CA 90095
| | - Laurent Vergnes
- David Geffen School of Medicine at UCLA, Department of Human Genetics, Los Angeles, CA 90095
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22
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Styer AM, Roesch SL, Argyropoulos G. Modulation of fibroblast growth factor 19 expression by bile acids, meal replacement and energy drinks, milk, and coffee. PLoS One 2014; 9:e85558. [PMID: 24465600 PMCID: PMC3896408 DOI: 10.1371/journal.pone.0085558] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 11/29/2013] [Indexed: 12/31/2022] Open
Abstract
Background The enterohepatic pathway involving the fibroblast growth factor 19 (FGF19) and bile acids (BA) has been linked with the etiology and remission of type 2 diabetes (T2D) following Roux-en-Y gastric bypass (RYGB) surgery. Specifically, diabetic patients had lower FGF19 circulating levels but postoperative FGF19 and BA levels were higher in diabetic patients that experience remission of T2D, as compared to non-diabetic patients and diabetic patients that do not experience remission. It has been proposed that this may be due to the direct flow of digestate-free bile acids into the ileum benefiting mostly T2D patients without severe diabetes. Methods/Results We used a human colorectal cell line (LS174T) that endogenously expresses FGF19, real time PCR, and Elisas for precise quantitation of FGF19 mRNA and secreted protein levels. We report here that BA and fractions of BA stimulated FGF19 in vitro but this effect was partially blocked when BA were pre-incubated with a lipoprotein mix which emulates digested food. In addition, we show that FGF19 mRNA was stimulated by meal replacement drinks (Ensure, Glucerna, SlimFast), non-fat milk, and coffee which has been linked with reduced risk for developing diabetes. Pure caffeine and the 5-hour Energy drink, on the other hand, decreased FGF19 mRNA. Conclusions In summary, FGF19 expression in vitro is modifiable by popular drinks suggesting that such approaches could potentially be used for modulating FGF19 expression in humans.
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Affiliation(s)
- Amanda M. Styer
- Weis Center for Research, Geisinger Health System, Danville, Pennsylvania, United States of America
| | - Stephen L. Roesch
- Weis Center for Research, Geisinger Health System, Danville, Pennsylvania, United States of America
| | - George Argyropoulos
- Weis Center for Research, Geisinger Health System, Danville, Pennsylvania, United States of America
- Institute of Obesity, Geisinger Health System, Danville, Pennsylvania, United States of America
- * E-mail:
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23
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Miyata M, Hata T, Yamazoe Y, Yoshinari K. SREBP-2 negatively regulates FXR-dependent transcription of FGF19 in human intestinal cells. Biochem Biophys Res Commun 2013; 443:477-82. [PMID: 24321096 DOI: 10.1016/j.bbrc.2013.11.126] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 11/27/2013] [Indexed: 01/19/2023]
Abstract
Sterol regulatory element-binding protein-2 (SREBP-2) is a basic helix-loop-helix-leucine zipper transcription factor that positively regulates transcription of target genes involved in cholesterol metabolism. In the present study, we have investigated a possible involvement of SREBP-2 in human intestinal expression of fibroblast growth factor (FGF)19, which is an endocrine hormone involved in the regulation of lipid and glucose metabolism. Overexpression of constitutively active SREBP-2 decreased FGF19 mRNA levels in human colon-derived LS174T cells. In reporter assays, active SREBP-2 overexpression suppressed GW4064/FXR-mediated increase in reporter activities in regions containing the IR-1 motif (+848 to +5200) in the FGF19 gene. The suppressive effect disappeared in reporter activities in the region containing the IR-1 motif when the mutation was introduced into the IR-1 motif. In electrophoretic mobility shift assays, binding of the FXR/retinoid X receptor α heterodimer to the IR-1 motif was attenuated by adding active SREBP-2, but SREBP-2 binding to the IR-1 motif was not observed. In chromatin immunoprecipitation assays, specific binding of FXR to the IR-1-containing region of the FGF19 gene (+3214 to +3404) was increased in LS174T cells by treatment with cholesterol and 25-hydroxycholesterol. Specific binding of SREBP-2 to FXR was observed in glutathione-S-transferase (GST) pull-down assays. These results suggest that SREBP-2 negatively regulates the FXR-mediated transcriptional activation of the FGF19 gene in human intestinal cells.
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Affiliation(s)
- Masaaki Miyata
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan; Department of Food Science and Technology, National Fisheries University, 2-7-1, Nagatahonmatch, Shimonoseki 759-6595, Japan.
| | - Tatsuya Hata
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Yasushi Yamazoe
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
| | - Kouichi Yoshinari
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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24
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Zhang JH, Nolan JD, Kennie SL, Johnston IM, Dew T, Dixon PH, Williamson C, Walters JRF. Potent stimulation of fibroblast growth factor 19 expression in the human ileum by bile acids. Am J Physiol Gastrointest Liver Physiol 2013; 304:G940-8. [PMID: 23518683 PMCID: PMC3652069 DOI: 10.1152/ajpgi.00398.2012] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fibroblast growth factor 19 (FGF19) is proposed to be a negative feedback regulator of hepatic bile acid (BA) synthesis. We aimed to clarify the distribution of FGF19 expression in human intestine and to investigate induction in a novel explant system. Ileal and colonic mucosal biopsies were obtained at endoscopy and analyzed for FGF19 transcript expression. Primary explants were incubated with physiological concentrations of various BA for up to 6 h, and expression of FGF19 and other genes was determined. FGF19 transcripts were detected in ileum but were unquantifiable in colon. No loss of FGF19 mRNA occurred as a consequence of the explant system. Ileal FGF19 transcript expression was induced 350-fold by 50 μM chenodeoxycholate (CDCA, n = 24, P < 0.0001) and 161-fold by 50 μM glycochenodeoxycholate (GCDCA, n = 12, P = 0.0005). The responses of other genes to CDCA or GCDCA (50 μM) were smaller: median increases of ileal bile acid binding protein, organic solute transporter-α and -β, and short heterodimer partner were 2.4- to 4.0-fold; apical membrane sodium bile acid transporter and farnesoid X receptor (FXR) showed little change. The EC50 for FGF19 transcript induction by CDCA was 20 μM. FGF19 protein concentrations were significantly higher in the culture fluid from BA-stimulated explants. FGF19 induction with cholate was 81% of that found with CDCA, but deoxycholate (40%) and lithocholate (4%) were significantly less potent. The synthetic FXR agonist obeticholic acid was much more potent than CDCA with a 70-fold FGF19 stimulation at 1 μM. We concluded that FGF19 expression in human ileum is very highly responsive to BA. Changes in FGF19 induction are a potential mechanism involved in disorders of BA homeostasis.
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Affiliation(s)
- Justine H. Zhang
- 1Section of Hepatology and Gastroenterology, Department of Medicine,
| | - Jonathan D. Nolan
- 1Section of Hepatology and Gastroenterology, Department of Medicine,
| | - Sarah L. Kennie
- 1Section of Hepatology and Gastroenterology, Department of Medicine,
| | - Ian M. Johnston
- 1Section of Hepatology and Gastroenterology, Department of Medicine,
| | - Tracy Dew
- 3Clinical Biochemistry, King's College Hospital, London, United Kingdom
| | - Peter H. Dixon
- 2Obstetric Medicine, Imperial College London and Imperial College Healthcare, London;
| | - Catherine Williamson
- 2Obstetric Medicine, Imperial College London and Imperial College Healthcare, London;
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25
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Enterobacteria-mediated deconjugation of taurocholic acid enhances ileal farnesoid X receptor signaling. Eur J Pharmacol 2012; 697:132-8. [PMID: 23051670 DOI: 10.1016/j.ejphar.2012.09.048] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/18/2012] [Accepted: 09/21/2012] [Indexed: 12/22/2022]
Abstract
Enterobacteria are known to deconjugate amino acid-conjugated bile acids in the intestine. Administration of ampicillin (ABPC; 3 days, 100mg/kg) decreased the expression of ileal farnesoid X receptor (Fxr) target genes, and increased the levels of total bile acids in the intestinal lumen. The primary tauro-conjugates of cholic acid (TCA) and beta-muricholic acid (TβMCA) levels were increased, whereas the primary unconjugates, cholic acid (CA) and beta-muricholic acid (βMCA), levels decreased to below detectable levels (<0.01μmol) in ABPC-treated mice. The effects of individual bile acid on expression of the ileal farnesoid X receptor target genes were examined in ABPC-treated mice. The expression of ileal farnesoid X receptor target genes in ABPC-treated mice was clearly enhanced after CA (500mg/kg), but not TCA (500mg/kg) cotreatment. Their levels in control mice were enhanced after either CA or TCA-cotreatment. Unconjugated CA levels in the intestinal lumen and portal vein were increased in both ABPC-treated and control mice. Reduced ileal Fgf15 and Shp mRNA levels in ABPC-treated mice were also increased after CA (100mg/kg) cotreatment at which luminal CA levels was restored to the level in controls, but was unaffected by βMCA (100mg/kg) cotreatment. In addition, no increase in ileal Shp, Ibabp or Ostα mRNA levels was observed even after CA (500mg/kg) cotreatment in ABPC-treated farnesoid X receptor-null mice despite increased CA levels in the intestinal lumen. These results suggest the role of enterobacteria in bile acid-mediated enhancement of ileal farnesoid X receptor signaling by TCA deconjugation.
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