incretins and Hepatitis-C

Dipeptidyl peptidase-4 (DPP-4) is a membrane-associated peptidase, also known as CD26. DPP-4 has widespread organ distribution throughout the body and exerts pleiotropic effects via its peptidase activity. A representative target peptide is glucagon-like peptide-1, and inactivation of glucagon-like peptide-1 results in the development of glucose intolerance/diabetes mellitus and hepatic steatosis. In addition to its peptidase activity, DPP-4 is known to be associated with immune stimulation, binding to and degradation of extracellular matrix, resistance to anti-cancer agents, and lipid accumulation. The liver expresses DPP-4 to a high degree, and recent accumulating data suggest that DPP-4 is involved in the development of various chronic liver diseases such as hepatitis C virus infection, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Furthermore, DPP-4 occurs in hepatic stem cells and plays a crucial role in hepatic regeneration. In this review, we described the tissue distribution and various biological effects of DPP-4. Then, we discussed the impact of DPP-4 in chronic liver disease and the possible therapeutic effects of a DPP-4 inhibitor.

Topics: Carcinoma, Hepatocellular; Dipeptidyl Peptidase 4; End Stage Liver Disease; Extracellular Matrix; Fatty Liver; Gene Expression Regulation, Enzymologic; Hepatitis C; Humans; Incretins; Insulin Resistance; Lipid Metabolism; Liver Neoplasms; Non-alcoholic Fatty Liver Disease

Several well-known risk factors play an important role in the development of new-onset diabetes mellitus after orthotopic liver transplantation (OLT). Immunosuppressant drugs and hepatitis C virus (HCV) infection have a direct effect on pancreatic beta cells resulting insulin hyposecretion. Steroids mainly cause peripheral insulin resistance. Although in type 2 diabetes mellitus the incretin-insulin axis is impaired and incretin hormones are advantageous targets of many antidiabetic drugs, the endocrinologic background of new-onset diabetes mellitus after transplantation (NODAT) is still not completely understood.. During the first postoperative year the oral glucose tolerance test (OGTT) was performed on 21 patients after OLT. Patients' glycemic metabolic status was determined according to the results of OGTT. The level of incretin hormones, namely glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP), were measured with competitive enzyme-linked immunoassay reaction.. Six patients had normal glucose tolerance (NGT), 9 had impaired glucose tolerance (IGT, serum glucose 7.8-11.0 mmol/L), and 6 were diagnosed with NODAT (serum glucose >11.1 mmol/L). Fasting insulin and c-peptide levels were higher if IGT/NODAT was found. Insulin secretion was not further stimulated after OGTT. GIP and GLP-1 levels did not differ significantly, not even after glucose load. HCV infection had not influenced the levels of incretin hormones [GLP-1 (0 min): 1.21 ± 0.27 vs 1.38 ± 0.65; P = ns; GLP-1 (120 min): 1.46 ± 0.61 vs 1.07 ± 0.58; P = ns; GIP (0 min): 2.55 ± 0.95 vs 1.99 ± 0.63; P = ns, GIP (120 min): 2.62 ± 0.6 vs 2.33 ± 0.77; P = ns].. The stimulation of insulin secretion in NODAT is limited. Incretin hormones are present independently from the current glycemic status. The use of dipeptidyl peptidase-4 inhibitors through their positive effect on the incretin-insulin axis can be beneficial in the therapy of NODAT after liver transplantation.

Topics: Adult; Blood Glucose; C-Peptide; Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Fasting; Female; Glucose Tolerance Test; Hepatitis C; Humans; Incretins; Insulin; Insulin Resistance; Insulin Secretion; Liver Transplantation; Male; Middle Aged; Postoperative Period