(W1030-11-75) Systemic Coadministration of Selective PDE4B Inhibitor A-33 and the Pan-PPAR Agonist Lanifibranor Ameliorates Chronic Liver Disease

Purpose: Chronic liver diseases (CLDs) are a significant worldwide health challenge and are responsible for approximately two million annual mortalities. Currently, more than seventy-five million people have been clinically diagnosed with alcohol use disorder, over two billion people around the world are obese, and more than four-hundred million have been diagnosed with diabetes, all of which significantly potentiate the risk of developing CLD.¹ Currently, there are no approved pharmacological therapies for CLD, and the only curative option is liver transplantation. Previous work has shown that the expression of phosphodiesterase 4B (PDE4B) and all peroxisome proliferator-activating receptor (PPAR) isoforms are dysregulated in CLD, which are attractive druggable targets.² We hypothesize that the systemic administration of a PDE4B inhibitor will inhibit inflammation by decreasing the production of pro-inflammatory cytokines and mediators in macrophages, the restoration of fatty acid β-oxidation in hepatocytes, inhibiting of de novo lipogenesis, and decreasing the expression of pro-fibrotic genes in hepatic stellate cells. Similarly, we hypothesize that the systemic administration of a pan-PPAR agonist will inhibit inflammation, restore β-oxidation, and inhibit fibrosis.

Methods: Twelve-week-old C57BL/6J mice were purchased and groups of five animals (n=5) were fed a methionine and choline-deficient (MCD) diet for a total of six weeks (42 days) to generate non-alcoholic steatohepatitis. At the beginning of the fourth week of being fed the diet, the mice were treated either with A-33, Lanifibranor, or their combination for the remaining two weeks of the study. Free A-33 was prepared in an emulsion consisting of 65% propylene glycol (PG) and 35% isotonic saline prior to being administered at a dose of 0.3 mg/kg daily via intraperitoneal injection. Free Lanifibranor was prepared in a solution of 75% PG, 25% isotonic saline, and less than 1% Kolliphor EL prior to being administered at a dose of 25 mg/kg thrice weekly. For the combination treatment, emulsions were prepared as described above, and a half-dose of each compound (A-33 = 150 µg/kg, Lanifibranor = 12.5 mg/kg) was administered along the same dosing schedules. At the end of the study, mice were anesthetized via isoflurane inhalation, blood was collected through a cardiac puncture, and death was ensured by cervical dislocation. Organs were then collected and either placed immediately on dry ice or fixed in 10% buffered formalin for 48 hr. Serum injury markers were measured using the Abaxis Vetscan Vs2 platform using the Preventative Care Profile Plus test rotors according to the manufacturer’s instructions.

Results: Six weeks of MCD diet feeding induced severe liver damage, fat accumulation, pericellular fibrosis, and statistically significant increases in the levels of serum markers of liver injury. Systemic administration of A-33, Lanifibranor, and their combination significantly ameliorated disease burden in experimental animals. Systemic administration of A-33 significantly inhibited PDE4B expression in experimental mice. We demonstrated that A-33, Lanifibranor, and their combination were effective in ameliorating the gross histopathological signs and symptoms of NASH, additionally resulting in significant decreases in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), and alkaline phosphatase (ALP) levels. Systemic administration of these compounds and their combination decreased overall fat and collagen deposition in the liver as quantified from Sirius red and Oil red O staining.

Conclusion: In conclusion, A-33, Lanifibranor, and their combination proved efficacious in the treatment of CLD in mice. We believe that there is a potential synergism between these pathways that could prove to be a productive avenue for future exploration. In the future, we plan on examining the effect of these therapeutics in white adipose tissue and developing a targeted delivery platform to decrease the dose and prolong the circulation time of these drugs.

References: 1. Asrani, S.K., Devarbhavi, H., Eaton, J., and P.S. Kamath Burden of liver diseases in the world. Journal of Hepatology, 70, 151-171 (2019).
2. Wahlang, B., McClain, C., Barve, S., and L. Gobejishivili. Role of cAMP and phosphodiesterase signaling in liver health and disease. Cellular Signaling 49, 105-115 (2018).

Acknowledgements: The University of Nebraska Medical Center Faculty Startup fund to Ram Mahato is acknowledged for providing financial support for this work. Virender Kumar is supported by the National Institute of Health (NIH) Grant (1K01AA029763-01). Ram Mahato is funded by the NIH (R01CA266759).