Direct AMPK activation corrects NASH in rodents through metabolic effects and direct action on inflammation and fibrogenesis

No approved therapies are available for nonalcoholic steatohepatitis (NASH). Adenosine monophosphate–activated protein kinase (AMPK) is a central regulator of cell metabolism; its activation has been suggested as a therapeutic approach to NASH. Here we aimed to fully characterize the potential for direct AMPK activation in preclinical models and to determine mechanisms that could contribute to efficacy for this disease. A novel small-molecule direct AMPK activator, PXL770, was used. Enzyme activity was measured with recombinant complexes. De novo lipogenesis (DNL) was quantitated in vivo and in mouse and human primary hepatocytes. Metabolic efficacy was assessed in ob/ob and high-fat diet–fed mice. Liver histology, biochemical measures, and immune cell profiling were assessed in diet-induced NASH mice. Direct effects on inflammation and fibrogenesis were assessed using primary mouse and human hepatic stellate cells, mouse adipose tissue explants, and human immune cells. PXL770 directly activated AMPK in vitro and reduced DNL in primary hepatocytes. In rodent models with metabolic syndrome, PXL770 improved glycemia, dyslipidemia, and insulin resistance. In mice with NASH, PXL770 reduced hepatic steatosis, ballooning, inflammation, and fibrogenesis. PXL770 exhibited direct inhibitory effects on pro-inflammatory cytokine production and activation of primary hepatic stellate cells. Conclusion: In rodent models, direct activation of AMPK is sufficient to produce improvements in all core components of NASH and to ameliorate related hyperglycemia, dyslipidemia, and systemic inflammation. Novel properties of direct AMPK activation were also unveiled: improved insulin resistance and direct suppression of inflammation and fibrogenesis. Given effects also documented in human cells (reduced DNL, suppression of inflammation and stellate cell activation), these studies support the potential for direct AMPK activation to effectively treat patients with NASH

Validation of direct AMP kinase (AMPK) activation for treatment of X-linked Adrenoleukodystrophy

Background and aims: X-linked Adrenoleukodystrophy (ALD and adrenomyeloneuropathy - AMN) is a neurologic peroxisomal disorder, caused by ABCD1-gene mutations, leading to Very Long Chain Fatty Acid (VLCFA; C26:0) accumulation, AMPK downregulation, inflammation, mitochondrial impairment and demyelination. We investigated PXL770, a clinical-stage new direct AMPK activator, in AMN/ALD models. Methods: AMN/ALD patient-derived fibroblasts/lymphocytes and ABCD1-KO mouse glial cells were exposed to PXL770 for 7 days. Phospho-AMPK was measured by Western-blot, VLCFA content by LC-MS, selected gene expression by RT-qPCR and oxygen consumption with a Seahorse Analyzer. PXL770 (oral 75 mg/kg, BID, 12 weeks) was administered to ABCD1-KO mice. VLCFA content was measured by LC-MS, sciatic nerve axonal morphology by electronic microscopy, and locomotor function by beam balance test. Results: In AMN fibroblasts PXL770 reduced C26:0 levels (−90%, p = 0.0001), increased compensatory ABCD2 mRNA levels (9-fold), and improved mitochondrial function by increasing basal and ATP-linked respiration (14% and 112%, respectively) and decreasing proton leak (−25%). Similar profile was achieved in ALD fibroblasts, ALD/AMN lymphocytes and ABCD1-KO mice glial cells. In ALD lymphocytes, PXL770 decreased mRNAs encoding pro-inflammatory proteins including NF-κB, iNOS and CCR3 (2.9-fold, 8.2-fold, 5.9-fold, respectively). In ABCD1-KO mice treated with PXL770, C26:0 levels were decreased in the spinal cord by 29% (greater VLCFA decrease was also observed in brain/plasma). Sciatic nerve axons showed less myelin invaginations (−61%) and neurologic function was improved compared to untreated mice. Conclusions: We established preclinical validation for the potential utility of direct AMPK activators as a treatment for X-ALD, supporting further development of PXL770 for this debilitating neurometabolic disease

Fibroblast growth factor 19 regulates skeletal muscle mass and ameliorates muscle wasting in mice

International audienceThe endocrine-derived hormone fibroblast growth factor (FGF) 19 has recently emerged as a potential target for treating metabolic disease(1). Given that skeletal muscle is a key metabolic organ, we explored the role of FGF19 in that tissue. Here we report a novel function of FGF19 in regulating skeletal muscle mass through enlargement of muscle fiber size, and in protecting muscle from atrophy. Treatment with FGF19 causes skeletal muscle hypertrophy in mice, while physiological and pharmacological doses of FGF19 substantially increase the size of human myotubes in vitro. These effects were not elicited by FGF21, a closely related endocrine FGF member. Both in vitro and in vivo, FGF19 stimulates the phosphorylation of the extracellular-signal-regulated protein kinase 1/2 (ERK1/2) and the ribosomal protein S6 kinase (S6K1), an mTOR-dependent master regulator of muscle cell growth. Moreover, mice with a skeletal-muscle-specific genetic deficiency of beta-Klotho (KLB), an obligate co-receptor for FGF15/19 (refs. 2,3), were unresponsive to the hypertrophic effect of FGF19. Finally, in mice, FGF19 ameliorates skeletal muscle atrophy induced by glucocorticoid treatment or obesity, as well as sarcopenia. Taken together, these findings provide evidence that the enterokine FGF19 is a novel factor in the regulation of skeletal muscle mass, and that it has therapeutic potential for the treatment of muscle wasting