Digestive Diseases and Sciences https://doi.org/10.1007/s10620-018-5395-7 ORIGINAL ARTICLE Disease Progression and Pharmacological Intervention in a Nutrient‑Defcient Rat Model of Nonalcoholic Steatohepatitis Kirstine S. Tølbøl1,3,4 · Birgit Stierstorfer2 · Jörg F. Rippmann2 · Sanne S. Veidal1 · Kristofer T. G. Rigbolt1 · Tanja Schönberger2 · Matthew P. Gillum4 · Henrik H. Hansen1 · Niels Vrang1 · Jacob Jelsing1 · Michael Feigh1 · Andre Broermann2 Received: 14 June 2018 / Accepted: 22 November 2018 © The Author(s) 2018 Abstract Background There is a marked need for improved animal models of nonalcoholic steatohepatitis (NASH) to facilitate the development of more efcacious drug therapies for the disease. Methods Here, we investigated the development of fbrotic NASH in male Wistar rats fed a choline-defcient L-amino acid- defned (CDAA) diet with or without cholesterol supplementation for subsequent assessment of drug treatment efcacy in NASH biopsy-confrmed rats. The metabolic profle and liver histopathology were evaluated after 4, 8, and 12 weeks of dieting. Subsequently, rats with biopsy-confrmed NASH were selected for pharmacological intervention with vehicle, elafbranor (30 mg/kg/day) or obeticholic acid (OCA, 30 mg/kg/day) for 5 weeks. Results The CDAA diet led to marked hepatomegaly and fbrosis already after 4 weeks of feeding, with further progression of collagen deposition and fbrogenesis-associated gene expression during the 12-week feeding period. Cholesterol supple- mentation enhanced the stimulatory efect of CDAA on gene transcripts associated with fbrogenesis without signifcantly increasing collagen deposition. Pharmacological intervention with elafbranor, but not OCA, signifcantly reduced stea- tohepatitis scores, and fbrosis-associated gene expression, however, was unable to prevent progression in fbrosis scores. Conclusion CDAA-fed rats develop early-onset progressive NASH, which ofers the opportunity to probe anti-NASH com- pounds with potential disease-modifying properties. Keywords NASH · CDAA · Cholesterol · Elafbranor · OCA · Fibrosis * Andre Broermann Niels Vrang andre.broermann@boehringer‑ingelheim.com [email protected] Kirstine S. Tølbøl Jacob Jelsing [email protected] [email protected] Birgit Stierstorfer Michael Feigh birgit.stierstorfer@boehringer‑ingelheim.com [email protected] Jörg F. Rippmann 1 Gubra Aps, Hørsholm Kongevej 11b, 2970 Hørsholm, joerg.rippmann@boehringer‑ingelheim.com Denmark Sanne S. Veidal 2 Boehringer-Ingelheim Pharma GmbH & Co. KG, [email protected] Birkendorfer Str. 65, 88397 Biberach an der Riss, Germany Kristofer T. G. Rigbolt 3 Department of Biomedical Sciences, University [email protected] of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark Tanja Schönberger 4 Novo Nordisk Foundation for Basic Metabolic tanja.schoenberger@boehringer‑ingelheim.com Research, University of Copenhagen, Blegdamsvej 3, Matthew P. Gillum 2200 Copenhagen, Denmark [email protected] Henrik H. Hansen [email protected] Vol.:(0123456789)1 3 Digestive Diseases and Sciences Introduction regimens, CDAA diets are weight neutral [20, 23], which makes the CDAA model attractive for also assessing efects Nonalcoholic fatty liver disease (NAFLD) is the most com- on gross metabolic parameters of potential anti-NASH com- mon liver disease infuencing approximately 25% of the pounds. Although the CDAA model has been extensively general population of the Western countries [1, 2]. NAFLD characterized in the context of hepatopathology, relatively ranges from benign, steatosis to its most aggressive mani- few pharmacological studies have so far been reported in festation, nonalcoholic steatohepatitis (NASH), which is rodent CDAA models of NASH [19, 22, 24–27], and there characterized by steatosis, infammation, and hepatocyte is a marked lack of knowledge on the responsiveness of the degeneration (ballooning) [3]. Patients with NASH are at CDAA model to drugs that are in current clinical develop- increased risk of developing liver fbrosis which is the main ment for NASH [9]. prognostic factor for cirrhosis, primary liver cancer, and Hepatic cholesterol homeostasis is dysregulated in end-stage liver disease [4, 5]. With the increasing NASH NAFLD, and there is an increasing appreciation that the burden, it is therefore projected that advanced fibrotic lipotoxic properties of elevated free cholesterol can contrib- NASH will be the leading indication for liver transplanta- ute to the development and progression of NASH by stimu- tion in developing countries by 2020 [6]. Although consid- lation of detrimental immune cell responses with resulting erable progress has been made in the understanding of the hepatocyte necroinfammation and enhanced fbrogenesis cellular and molecular mechanisms in NASH, no evidence- [28, 29]. We therefore investigated whether cholesterol sup- based drug treatments approved for NASH management plementation could enhance the hepatotoxic properties of exist. NASH is therefore classifed as a medical condition CDAA dieting in rats, as compared to CDAA dieting alone. with high unmet therapeutic need. Several drug treatment In addition, we characterized the effects of obeticholic concepts are in various stages of clinical development for acid (OCA) and elafbranor in this novel cholesterol-sup- NASH [7, 8]. plemented CDAA rat model of NASH. Both compounds The primary driver of NASH is overnutrition and obesity. are in late-stage clinical development for NASH [30, 31]. Several diet-induced obese (DIO) models of NASH have OCA is a frst-in-class semisynthetic bile acid exerting its been developed in an attempt to mimic the etiology of the efect by binding to the nuclear farnesoid X receptor (FXR), disease [9]. Animals fed a diet high in fat and carbohydrates thereby activating several regulators in bile acid synthesis develop adiposity, insulin resistance, dyslipidemia, and fatty and transport, hepatic lipid, and carbohydrate metabolism as liver. Depending on the macronutrient composition, the DIO well as immune function [32–35]. OCA attenuates hepatic models may also exhibit features of liver infammation and, infammation and reduces low-grade hepatocyte ballooning to some degree, hepatocyte ballooning [10–16]. A major and has recently been reported to reduce liver pathology in challenge with the high-fat/carbohydrate dieting paradigms obese mouse models of NASH [13, 36–38]. Elafbranor is a is that very long dieting periods (typically > 20 weeks) high-afnity agonist for the nuclear peroxisome proliferator- are required for the steatohepatitis condition to progress activated alpha/delta receptor (PPAR-α/δ) and ameliorates to hepatic fbrosis. Furthermore, the DIO models do not NASH mainly by increasing the disposal of hepatic fatty consistently exhibit histopathological features of advanced acid as well as inhibiting pathways involved in infammation fbrotic (pre-cirrhotic) NASH making these animal models and fbrosis [13, 39, 40]. most applicable for probing drug efects on less severe stages of the disease [9, 17, 18]. The insufcient fbrotic response to hypercaloric diets has led to the development of nutrient- Materials and Methods defcient dietary concepts that promote faster onset of NASH and severe fbrosis reminiscent of severe fbrotic NASH in Animals humans [9]. Nutrient-defcient dietary models are either low or devoid of methionine and/or choline. Choline-defcient Male Wistar rats (RjHan:WI, 6 weeks of age, 200–250 g) diets with low methionine levels can be made even less lipo- were obtained from Janvier Labs (Le Genest-Saint-Isle, trope by replacing nutrient proteins with L-amino acids, i.e., France) and housed pairwise in a controlled environment choline-defcient amino acid-defned (CDAA) diet, which (21 °C ± 2 °C, humidity 50% ± 10%) with a 12-h light/ further impedes hepatic lipid clearance that enhances hepa- dark cycle. After acclimatizing, animals were fed either tomegaly, steatosis, and lipotoxic hepatocyte damage. In rats a choline-supplemented L-amino acid-defned (CSAA; and mice, CDAA diet regimens promote severe fbrosis with E15668-04, kcal %; protein 12%, fat 16%, carbohy- the development of frank cirrhosis after extended dieting drates 72%) control diet or a choline-defcient L-amino periods [19–22]. In contrast to the pronounced weight loss acid-defned (CDAA, kcal %; protein 11%, fat 31%, car- attained by methionine–choline-defcient (MCD) dieting bohydrates 58%) diet without cholesterol (E15667-94), 1 3 Digestive Diseases and Sciences or supplemented with 1% cholesterol (CDAA + 1%chol, Tissue Collection E15666-94) or 2% cholesterol (CDAA + 2%chol, E15665- 94) for 4, 8, or 12 weeks. CDAA diets were all low in Upon completion, animals were killed by cardiac puncture methionine (0.17%) compared to the CSAA diet (0.4%). under pentobarbital (Narcoren, Merial GmbH, Germany) or All diets were obtained from ssnif Spezialdiäten GmbH isofurane (Vetfurane, Virbac, Kolding, Denmark) anesthe- (Soest, Germany). sia, whereupon blood and liver were sampled. The blood In a subsequent study, the efect of pharmacological sample was centrifuged (2000 g, 10 min, 4 °C), and plasma intervention was evaluated in rats fed either CSAA or was collected and stored at − 80 °C. The liver was snap fro- CDAA + 1%chol for 9 weeks followed by 5 weeks of com- zen in liquid nitrogen and stored at − 80 °C until process- pound treatment. Three weeks prior to treatment start, a ing for biochemistry triglycerides (TG) and hydroxyproline liver biopsy was collected for treatment stratifcation and (HP), see below), or fxated in 4% paraformaldehyde and within-subject