ABSTRACT
Non-alcoholic steatohepatitis (NASH) is a primary cause of cirrhosis and hepatocellular carcinoma. Dipeptidyl peptidase (DPP)-4 inhibitors are established therapies for type 2 diabetes and although DPP-4 inhibitors can reduce hepatic steatosis, their impact on local inflammation and fibrosis in NASH remains unknown. Using two different experimental treatment regimens (4- and 2-week treatments) in streptozotocin-treated neonatal mice on a high-fat diet, we show that the DPP-4 inhibitor linagliptin (10 and 30 mg/kg) significantly attenuated the NAS score from 4.9 ± 0.6 to 3.7 ± 0.4 and 3.6 ± 0.3, respectively, in the 4-week study. In the 2-week study, linagliptin 10 mg/kg significantly reduced NAS score from 4.1 ± 0.4 to 2.4 ± 0.4. Telmisartan was used as a positive control in both studies and lowered NAS score to 1.9 ± 0.7 and 1.4 ± 0.3, respectively. Due to streptozotocin treatment, elevated glucose levels were unchanged by either drug treatment. Further, linagliptin 10 mg/kg significantly reduced mRNA levels of SOCS-3 (from 1.68 ± 0.2 to 0.83 ± 0.08), IFN-γ (from 4.0 ± 0.5 to 2.3 ± 0.3), and TNF-α (from 5.7 ± 0.5 to 2.13 ± 0.3). The latter observation was confirmed by immunohistochemistry of TNF-α in liver specimens. In addition, using microautoradiography, we showed that the distribution of radiolabeled linagliptin was heterogeneous with the highest density associated with interlobular bile ducts and portal tracts (acini). In conclusion, these studies confirm that linagliptin has high exposure in hepatic tissue and has both anti-inflammatory and anti-steatotic activity in NASH.
Subject(s)
Dipeptidyl-Peptidase IV Inhibitors/pharmacology , Non-alcoholic Fatty Liver Disease/drug therapy , Purines/pharmacology , Quinazolines/pharmacology , Animals , Animals, Newborn , Autoradiography , DNA Primers/genetics , Diet, High-Fat , Dipeptidyl Peptidase 4/metabolism , Dipeptidyl-Peptidase IV Inhibitors/therapeutic use , Immunohistochemistry , Interferon-gamma/metabolism , Linagliptin , Mice , Purines/therapeutic use , Quinazolines/therapeutic use , RNA, Messenger/metabolism , Real-Time Polymerase Chain Reaction , Streptozocin , Suppressor of Cytokine Signaling 3 Protein , Suppressor of Cytokine Signaling Proteins/metabolism , Time Factors , Tumor Necrosis Factor-alpha/metabolismABSTRACT
This article describes the combination of whole-body autoradiography with liquid extraction surface analysis (LESA) and mass spectrometry (MS) to study the distribution of the tachykinin neurokinin-1 antagonist figopitant and its metabolites in tissue sections of rats after intravenous administration of 5.0 mg/kg figopitant. An overview of autoradiography results is presented together with mass spectrometry identification and semiquantification of parent drug and its metabolites based on LESA-MS. The quality and accuracy of data generated by LESA-MS were assessed in comparison with classic tissue extraction, sample cleanup, and high-performance liquid chromatography analysis. The parent drug and the N-dealkylated metabolite M474(1) (BIIF 1148) in varying ratios were the predominant compounds in all tissues investigated. In addition, several metabolites formed by oxygenation, dealkylation, and a combination of oxygenation and dealkylation were identified. In summary, the LESA-MS technique was shown to be a powerful tool for identification and semiquantification of figopitant and its metabolites in different tissues and was complementary to quantitative whole-body autoradiography for studying the distribution.
