BACKGROUND:Primary biliary cholangitis (PBC) is a chronic, immune-mediated liver disease characterised by cholestasis, progressive fibrosis and symptoms of pruritus and fatigue. Ursodeoxycholic acid (UDCA) is first-line therapy; however, many patients respond inadequately or are intolerant. Peroxisome proliferator-activated receptor (PPAR) agonists have emerged as second-line options. AIMS:This review examines PPAR isoform (PPAR-α, PPAR-δ and PPAR-γ) mediated pathways relevant to PBC, and structural, biochemical and clinical efficacy and safety features of PPAR agonists for PBC. METHODS:Preclinical studies on therapeutic PPAR agonism and clinical literature on PPAR agonists in PBC were identified through targeted PubMed searches and manual reference screening. RESULTS:PPAR-α and PPAR-δ agonism improve cholestasis by reducing bile acid synthesis and inflammation. PPAR-α agonism also enhances bile acid detoxification and transport, while PPAR-δ agonism improves cholestatic pruritus by reducing pruritogenic signals. Individual PPAR isoforms are also associated with different safety profiles, with PPAR-α agonism linked to hepatic and muscle signals, and PPAR-γ agonism associated with fluid retention/weight gain. PPAR agonists differ in isoform selectivity. Although all agonists used in PBC reduce alkaline phosphatase levels, their impact on pruritus varies; PPAR-α predominant agonists (off-label fibrates, elafibranor) have a potential anti-pruritic effect, while selective PPAR-δ agonist, seladelpar, has demonstrated statistically significant improvements in pruritus. Fatigue is likely multifactorial, mediated through central nervous system effects and sleep disturbance; PPAR-α and PPAR-δ agents offer possible benefit. CONCLUSIONS:Isoform selectivity contributes to the efficacy and safety profiles of PPAR agonists. Future research should investigate isoform-specific mechanisms, particularly regarding symptom relief and agent- and class-related toxicities.

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors involved in transcriptional regulation and play an important role in many physiological and metabolic processes. Unlike PPAR-alpha and PPAR-gamma, PPAR-delta is ubiquitously expressed, and its activity is key to maintaining proper metabolic homeostasis within the liver. PPAR-delta not only regulates physiologic processes of lipid, glucose, and bile acid metabolism but also attenuates pathologic responses to alcohol metabolism, inflammation, fibrosis, and carcinogenesis, and is considered an important therapeutic target in liver diseases. Promising results have been reported in clinical trials for PPAR-delta agonists in liver disease, and the selective agonist seladelpar was recently conditionally approved in the United States as a new treatment option for primary biliary cholangitis. This review provides an overview of PPAR-delta’s function and biology in the liver, examines its kinetics and therapeutic potential across different liver diseases, and discusses the current status of clinical trials involving its agonists.

Peroxisome proliferator-activated receptors (PPARs) modulate bile metabolism and are important therapeutic options in cholestatic diseases. This study was aimed at understanding the effects of single and multiple doses of seladelpar, a PPARδ (peroxisome proliferator-activated receptor delta) agonist, on plasma C4 (a freely diffusible metabolite accepted as a proxy for de novo bile acid biosynthesis), Fibroblast Growth Factor 21 (Fgf21), and gene expression changes in the liver of male and female mice. C57BL/6 mice were treated with seladelpar 10 mg/kg/day or vehicle through oral gavage before lights out on Day 1 (single dose) or from Day 1 to Day 7 (multiple doses). Liver samples were obtained at 0, 1, 2, 4, 8, 12, 16, and 24 h postdosing, and plasma C4 and Fgf21 levels were measured. In vehicle-treated mice, C4 levels were higher in the dark cycle compared to the light cycle, with higher levels in females than in males. Plasma Fgf21 did not vary substantially over the dark-light cycle or show a sex-specific expression pattern. Seladelpar treatment significantly reduced plasma C4 and increased Fgf21 levels in both sexes, which coincided with a decrease in cholesterol 7α-hydroxylase mRNA and an increase in Fgf21 mRNA in the livers. Untargeted RNA sequencing revealed a strong correlation between the genes differentially expressed after single- and multiple-dose seladelpar treatment. PPAR-responsive genes, including pyruvate dehydrogenase kinase 4, acyl-CoA thioesterase 2, and angiopoietin-like 4, were upregulated. No changes in nuclear receptors, clock genes, and sex-specific genes were observed. Overall, these results are consistent with a model where seladelpar treatment reduces bile acid synthesis by upregulating Fgf21 and modulating other PPAR-responsive genes.

Background and Aims:The selective peroxisome proliferator-activated receptor delta (PPARD) agonist seladelpar reduces liver injury and modulates bile acid metabolism in preclinical models. Seladelpar was recently approved for the secondary treatment of primary biliary cholangitis (PBC). Despite its beneficial effects for liver diseases, the target cells of seladelpar on a single-cell level remain unknown. This study is aimed at investigating the effect of seladelpar on single liver cells. Methods and Results:CD-1 mice were gavaged with vehicle or seladelpar (10 mg/kg body weight), and the liver was harvested 6 h later. Single-nuclei RNA sequencing (snRNA-seq) analysis showed the engagement of PPARD target genes primarily in hepatocytes and cholangiocytes by seladelpar. The top two upregulated genes, Ehhadh and Cyp4a14, are related to fatty acid metabolism and were increased in hepatocytes, cholangiocytes, and Kupffer cells. Abcb4, an important canalicular transporter with hepatoprotective effects, was significantly upregulated in hepatocytes. We confirmed upregulated Abcb4 gene expression in seladelpar-treated primary mouse hepatocytes isolated from C57BL/6 mice. We further incubated nonparenchymal liver cells with seladelpar. Although there was a significant increase in the PPARD-responsive genes Pdk4 and Angptl4 in cholangiocytes, Kupffer cells, and hepatic stellate cells, seladelpar did not exert specific liver-protective effects in these cell types. Conclusion:The selective PPARD agonist seladelpar induced PPARD-responsive genes primarily in hepatocytes and cholangiocytes. Seladelpar upregulated Abcb4 in hepatocytes, which might contribute to its beneficial effects in cholestatic liver disorders.

The vasopressin system has emerged as a therapeutic focus for lowering portal hypertension and reducing splanchnic vasodilation in patients with refractory ascites. Clinically available vasopressin agonists are limited by preferential selectivity for V1 receptors that also have steep concentration–response curves with potential risks of excess vasoconstriction and/or complete antidiuretic effects. OCE-205 is a novel, selective, partial V1a receptor agonist with mixed agonist/antagonist activity and no V2 receptor activation at therapeutic doses. We carried out two studies assessing the in vivo effects of OCE-205 in different rat models of cirrhosis and ascites. In a carbon tetrachloride rat cirrhosis model, OCE-205 administration produced a marked reduction in portal hypertension and hyperaldosteronism, along with robust diuretic and natriuretic effects. These effects were accompanied by marked decreases in ascites volume, with three of five animals experiencing total mobilization of ascites. There was no evidence of fluid overload or sodium or water retention, confirming OCE-205′s lack of V2 receptor activity. In a second, corroborative study using a bile duct ligation rat model of ascites, OCE-205 produced significant decreases in ascites volume and body weight and a significant increase in urine volume versus vehicle. Urine sodium excretion increased significantly after the first administration of OCE-205 relative to vehicle; however, repeat administration over 5 days did not lead to hyponatremia. Thus, in separate in vivo models, the mixed agonist/antagonist OCE-205 demonstrated relevant and expected endpoint findings consistent with its known mechanism of action and in vitro pharmacology without apparent unwanted effects or nonspecific toxicities.

Treatment for complications associated with the hemodynamic consequences of decompensated cirrhosis remains suboptimal. Terlipressin, the latest pharmacological management of hepatorenal syndrome–acute kidney injury (HRS-AKI), targets the vasopressin system but has serious side effects. OCE-205 is a novel peptide designed to target the vasopressin receptor system as a mixed V1a agonist/antagonist, resulting in effective partial agonism without V2 agonism. We examined the in vivo pharmacokinetic/pharmacodynamic properties of OCE-205 in healthy rats and cynomolgus monkeys. OCE-205 was administered by IV or SC bolus injection; arginine vasopressin (AVP) or terlipressin were comparators. After IV OCE-205 administration in rats, mean plasma concentration decreased in a mostly linear manner to 2 mg/mL after 120 min, and for SC administration, slowly decreased to ∼50 ng/mL after 300 min. Compared with pre-test values, arterial blood pressure values significantly increased after all OCE-205 doses tested. For monkeys, the concentration after IV OCE-205 administration was mostly linear to 5 ng/mL after 180 min, and for SC administration, ∼3 ng/mL after 480 min. Subcutaneous OCE-205 administration increased mean arterial pressure (MAP) versus baseline, with ΔMAP in OCE-205–treated animals marked and long-lasting while terlipressin induced an increase from baseline in MAP, with negligible ΔMAP, on average, by 150 min after administration in all groups. AVP, but not OCE-205, significantly increased blood lactate concentrations. OCE-205 was well tolerated in adult male rats and cynomolgus monkeys following single-dose bolus administration. The preclinical results of OCE-205, with its demonstrated V1a selective partial agonist activity and potentially tolerable safety profile, suggest its potential utility for treatment of the cardiovascular complications of cirrhosis.

Objective To test the selectivity and degree of functional agonism of Ocelot Bio’s dual agonist/antagonist molecule, OCE-205, at the vasopressin 1a receptor (V1aR). Methods Cells expressing human (h) or rat V1a, V1b, V2, or oxytocin receptors (OTR) were incubated with varying concentrations of OCE-205 or with arginine vasopressin (AVP), and responses were measured with fluorescence or reporter gene assays. In addition, human resistance arteries were exposed to increasing concentrations of OCE-205, and the resulting contractility was measured. Results The mean efficacy of OCE-205 at hV1aR was 39% of the maximal possible effect (MPE), with a mean EC 50 of 0.71 nM. Above 1 nM OCE-205, the percent maximal possible effect (%MPE) plateaued. The EC 50 was much higher at hV1bR (134 nM), hV2R (420 nM), and OTR (6.9 nM), indicating selectivity for hV1aR. Results at rat receptors were similar. OCE-205 produced 40.0% of maximal depolarization-induced contraction, demonstrating functional partial agonism. Conclusion The dual agonist/antagonist structure of OCE-205 thus allows it to act as a highly selective partial agonist at vasopressin V1aR at therapeutically relevant concentrations. Keywords Cirrhosis , hepatorenal syndrome , vasopressin , partial agonism , vasopressin V1a receptor

Purpose Management of decompensated cirrhosis may include the use of vasoconstrictors that can lead to serious adverse events. OCE-205 was designed as a highly selective V1a receptor partial agonist, intended to have a wider therapeutic window than full vasopressin agonists. Methods We aimed to characterize the activity of OCE-205 treatment in two rat models of portal hypertension (PHT). For both models, OCE-205 was administered as a subcutaneous bolus injection. Thirty male Wistar rats were fed a methionine/choline-deficient (MCD) diet to model PHT. Animals received OCE-205 (10, 25, 100, or 500 µg/kg) or intra-arterial terlipressin (100 µg/kg). In a more severe model of PHT, 11 male Sprague Dawley rats had the common bile duct surgically ligated (BDL) and received OCE-205. Portal pressure (PP) and mean arterial pressure (MAP) were measured. Results For PP in the MCD model, MAP increased while PP decreased in rats treated with OCE-205 or terlipressin; the peak changes to MAP were 14.7 and 33.5 mmHg, respectively. Changes in MAP began to plateau after 10 min in the OCE-205 groups, whereas in the terlipressin group, MAP rapidly increased and peaked after 20 min. Across all treatment groups in the BDL model, a dose-related decrease from baseline in PP was observed following OCE-205, plateauing as the dose increased. In all treatment groups, PP change remained negative throughout the 30-min testing period. In both PHT rat models, a reduction in PP was coupled to an increase in MAP, with both plateauing in dose–response curves. Conclusion Data support OCE-205 as a promising candidate for further development. Institutional Protocol Number Procedures were approved by the Ferring Research Institute (FRI) Institutional Animal Care and Use Committee on July 13, 2011, under protocol FRI-07-0002.

ObjectiveTo test the selectivity and degree of functional agonism of Ocelot Bio's dual agonist/antagonist molecule, OCE-205, at the vasopressin 1a receptor (V1aR). MethodsCells expressing human (h) or rat V1a, V1b, V2, or oxytocin receptors (OTR) were incubated with varying concentrations of OCE-205 or with arginine vasopressin (AVP), and responses were measured with fluorescence or reporter gene assays. In addition, human resistance arteries were exposed to increasing concentrations of OCE-205, and the resulting contractility was measured. ResultsThe mean efficacy of OCE-205 at hV1aR was 39% of the maximal possible effect (MPE), with a mean EC50 of 0.71 nM. Above 1 nM OCE-205, the percent maximal possible effect (%MPE) plateaued. The EC50 was much higher at hV1bR (134 nM), hV2R (420 nM), and OTR (6.9 nM), indicating selectivity for hV1aR. Results at rat receptors were similar. OCE-205 produced 40.0% of maximal depolarization-induced contraction, demonstrating functional partial agonism. ConclusionThe dual agonist/antagonist structure of OCE-205 thus allows it to act as a highly selective partial agonist at vasopressin V1aR at therapeutically relevant concentrations.

Peroxisome proliferator-activated receptor delta (PPARδ) agonists have been shown to exert beneficial effects in liver disease and reduce total bile acid levels. The mechanism(s) whereby PPARδ agonism reduces bile acid levels are, however, unknown, and therefore the aim of the present study was to investigate the molecular pathways responsible for reducing bile acid synthesis in hepatocytes, following treatment with the selective PPARδ agonist, seladelpar. We show that administration of seladelpar to WT mice repressed the liver expression of cholesterol 7 alpha-hydroxylase (Cyp7a1), the rate-limiting enzyme for bile acid synthesis, and decreased plasma 7α-hydroxy-4-cholesten-3-one (C4), a freely diffusible metabolite downstream of Cyp7a1. In primary mouse hepatocytes, seladelpar significantly reduced the expression of Cyp7a1 independent of the nuclear bile acid receptor, Farnesoid X receptor. In addition, seladelpar upregulated fibroblast growth factor 21 (Fgf21) in mouse liver, serum, and in cultured hepatocytes. We demonstrate that recombinant Fgf21 protein activated the c-Jun N-terminal kinase (JNK) signaling pathway and repressed Cyp7a1 gene expression in primary hepatocytes. The suppressive effect of seladelpar on Cyp7a1 expression was blocked by a JNK inhibitor as well as in the absence of Fgf21, indicating that Fgf21 plays an indispensable role in PPARδ-mediated downregulation of Cyp7a1. Finally, reduction of CYP7A1 expression by seladelpar was confirmed in primary human hepatocytes. In conclusion, we show that seladelpar reduces bile acid synthesis via an FGF21-dependent mechanism that signals at least partially through JNK to repress CYP7A1.

with Thioacetamide (TAA), using immunoblot, RT-PCR and immunohistochemistry. Liver tissues from vehicle and TAA treated NFATc1 wt , NFATC1 c.a. and NFATc1 fl/fl mice were examined for NFATc1 dependent morphological changes by analyzing inflammation, and fibrosis.RNA-seq analysis in AML12 cells was performed to identify NFATc1 regulated gene signatures and signaling mechanisms.We further highlighted the therapeutic potential of NFATc1 dependent signaling mechanisms by their inhibition, both in-vivo and in-vitro.Results: Liver biopsies from patients with inflammation/fiborsis revealed increased NFATc1 expression and nuclear localization in hepatocytes.Moreover, TAA induced NFATc1 activation resulted in progressive inflammation, fibrosis and cirrhosis whereas hepatocytespecific depletion of the transcription factor prevented mice from liver damage.Mechanistically, hepatocyte specific NFATc1 activation drives chronic ER stress-responses and promotes apoptosis (cleaved Caspase-3) and pro-inflammatory signaling cascades through PERK-CHOP-mediated NLRP3 inflammasome activation.Finally, TUDCA mediated inhibition of NFATc1-driven signaling prevented hepatocyte damage and subsequent inflammation/fibrosis.Conclusion: Together, our study successfully established the role of NFATc1 in liver inflammation and fibrosis through terminal ER-stress signalling and subsequent NLRP3 inflammasome activation in hepatocytes.This study also highlighted the therapeutic potential of ER-stress inhibition by TUDCA.In fact, TUDCA application resulted in strikingly lower liver damage and fibrosis in mice.