pf-05231023 and Disease-Models--Animal

Fibroblast growth factor 21 (FGF21) plays a key role in hepatic lipid metabolism and long-acting FGF21 analogs have emerged as promising drug candidates for the treatment of nonalcoholic steatohepatitis (NASH). It remains to characterize this drug class in translational animal models that recapitulate the etiology and hallmarks of human disease. To this end, we evaluated the long-acting FGF21 analog PF-05231023 in the GAN (Gubra Amylin NASH) diet-induced obese (DIO) and biopsy-confirmed mouse model of NASH. Male C57BL/6J mice were fed the GAN diet high in fat, fructose, and cholesterol for 34 wk before the start of the study. GAN DIO-NASH mice with biopsy-confirmed NAFLD Activity Score (NAS ≥5) and fibrosis (stage ≥F1) were biweekly administered with PF-05231023 (10 mg/kg sc) or vehicle (sc) for 12 wk. Vehicle-dosed chow-fed C57BL/6J mice served as healthy controls. Pre-to-post liver biopsy histopathological scoring was performed for within-subject evaluation of NAFLD Activity Score (NAS) and fibrosis stage. Terminal endpoints included quantitative liver histology and transcriptome signatures as well as blood and liver biochemistry. PF-05231023 significantly reduced body weight, hepatomegaly, plasma transaminases, and plasma/liver lipids in GAN DIO-NASH mice. Notably, PF-05231023 reduced both NAS (≥2-point improvement) and fibrosis stage (1-point improvement). Improvements in NASH and fibrosis severity were supported by reduced quantitative histological markers of steatosis, inflammation, and fibrogenesis as well as improvements in disease-associated liver transcriptome signatures. In conclusion, PF-05231023 reduces NASH and fibrosis severity in a translational biopsy-confirmed mouse model of NASH, supporting development of FGF21 analogs for the treatment of NASH.

Topics: Animals; Biopsy; Diet; Diet, High-Fat; Disease Models, Animal; Humans; Liver; Liver Cirrhosis; Male; Mice; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Obesity

Fibroblast growth factor 21 (FGF21) is known as a potent metabolic regulator but its protective mechanisms against lipotoxicity-induced β-cell dysfunction and apoptosis remain elusive. Here, we aimed to examine the regulatory pathways whereby FGF21 mediates islet lipid metabolism in lipotoxicity-treated cells and animal models. Rat β-cell line (INS-1E cells) and islets isolated from C57/BL6J mice were exposed to palmitic acid (PA) with/without FGF21, mimicking lipotoxic conditions. Resultant insulin secretion and intracellular signaling were analyzed with Western blotting and RNA-seq. C57/BL6J and global FGF21 knockout (KO) mice were fed with a high-fat diet (HFD) to induce lipotoxicity and given with a long-acting mimetic of FGF21. Insulin resistance and β-cell function were then assessed using homeostasis model assessment of insulin resistance (HOMA-IR) and insulinogenic index. FGF21 ameliorated PA-induced lipid accumulation, reversed cell apoptosis, and enhanced glucose-stimulated insulin secretion (GSIS) as impaired by lipotoxicity in islet β-cells. Mechanistically, FGF21 exerted its beneficial effects through activation of AMPK-ACC (acetyl-CoA carboxylase) pathway and peroxisome proliferation-activated receptors (PPARs) δ/γ signaling, thus increasing the levels of carnitine palmitoyltransferase-1A (CPT1A) and leading to increased fatty acid (FA) oxidation and reduced lipid deposition in β-cells. Interestingly, FGF21 reduced PA-induced cell death via restoration of the expression of apoptosis inhibitor Birc3. In vivo studies further showed that FGF21 is critical for islet insulinogenic capacity and normal function in the context of HFD-treated animals. FGF21 down-regulates islet cell lipid accumulation, probably via activation of AMPK-ACC and PPARδ/γ signaling, and reduces cell death under lipotoxicity, indicating that FGF21 is protective against lipotoxicity-induced β-cell dysfunction and apoptosis.

Topics: Acetyl-CoA Carboxylase; AMP-Activated Protein Kinases; Animals; Antibodies, Monoclonal, Humanized; Apoptosis; Cell Line, Tumor; Diabetes Mellitus, Type 2; Diet, High-Fat; Disease Models, Animal; Fibroblast Growth Factors; Insulin; Insulin Resistance; Insulin-Secreting Cells; Male; Mice, Inbred C57BL; Mice, Knockout; Obesity; Palmitic Acid; PPAR gamma; Rats; Receptors, Cytoplasmic and Nuclear; Signal Transduction

Retinal neuronal abnormalities occur before vascular changes in diabetic retinopathy. Accumulating experimental evidence suggests that neurons control vascular pathology in diabetic and other neovascular retinal diseases. Therefore, normalizing neuronal activity in diabetes may prevent vascular pathology. We investigated whether fibroblast growth factor 21 (FGF21) prevented retinal neuronal dysfunction in insulin-deficient diabetic mice. We found that in diabetic neural retina, photoreceptor rather than inner retinal function was most affected and administration of the long-acting FGF21 analog PF-05231023 restored the retinal neuronal functional deficits detected by electroretinography. PF-05231023 administration protected against diabetes-induced disorganization of photoreceptor segments seen in retinal cross section with immunohistochemistry and attenuated the reduction in the thickness of photoreceptor segments measured by optical coherence tomography. PF-05231023, independent of its downstream metabolic modulator adiponectin, reduced inflammatory marker interleukin-1β (IL-1β) mRNA levels. PF-05231023 activated the AKT-nuclear factor erythroid 2-related factor 2 pathway and reduced IL-1β expression in stressed photoreceptors. PF-05231023 administration did not change retinal expression of vascular endothelial growth factor A, suggesting a novel therapeutic approach for the prevention of early diabetic retinopathy by protecting photoreceptor function in diabetes.

Topics: Animals; Antibodies, Monoclonal, Humanized; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Retinopathy; Disease Models, Animal; Electroretinography; Fibroblast Growth Factors; Interleukin-1beta; Male; Mice; NF-E2-Related Factor 2; Photoreceptor Cells, Vertebrate; Proto-Oncogene Proteins c-akt; Retinal Neurons; Tomography, Optical Coherence; Vascular Endothelial Growth Factor A

FGF21 is a key metabolic regulator modulating physiological processes and its pharmacological administration improves metabolic profile in preclinical species and humans. We used native-FGF21 and a long-acting FGF21 (PF-05231023), to determine the contribution of liver and brown adipose tissue (BAT) towards metabolic improvements in Zucker rats and DIO mice (DIOs). FGF21 improved glucose tolerance and liver insulin sensitivity in Zuckers without affecting BW and improved liver function by decreased lipogenesis, increased fatty acid oxidation and improved insulin signaling. Through detailed lipidomic analyses of liver metabolites in DIOs, we demonstrate that FGF21 favorably alters liver metabolism. We observed a dose-dependent increase of [(18)F]-FDG-glucose uptake in interscapular BAT (iBAT) of DIOs upon FGF21 administration. Upon excision of iBAT (X-BAT) and administration of FGF21 to mice housed at 80 °F or 72 °F, the favorable effects of FGF21 on BW and glucose excursion were fully retained in both sham and X-BAT animals. Taken together, we demonstrate the liver as an organ that integrates the actions of FGF21 and provide metabolic benefits of FGF21 in Zucker rats and DIOs. Finally, our data demonstrates iBAT does not play a role in mediating favorable metabolic effects of FGF21 administration in DIOs housed at 80 °F or 72 °F.

Topics: Adipose Tissue, Brown; Animals; Antibodies, Monoclonal, Humanized; Disease Models, Animal; Fatty Acids; Fibroblast Growth Factors; Glucose; Homeostasis; Insulin Resistance; Liver; Mice; Obesity; Rats; Rats, Zucker