Renoprotective Effect of Gemigliptin, a Dipeptidyl Peptidase-4 Inhibitor, in Streptozotocin-Induced Type 1 Diabetic Mice.
BACKGROUND
Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used in the treatment of patients with type 2 diabetes and have proven protective effects on diabetic kidney disease (DKD). Whether DPP-4 inhibitors have renoprotective effects on insulin-deficient type 1 diabetes has not been comprehensively examined. The aim of this study was to determine whether gemigliptin, a new DPP-4 inhibitor, has renoprotective effects in streptozotocin (STZ)-induced type 1 diabetic mice.


METHODS
Diabetes was induced by intraperitoneal administration of a single dose of STZ. Mice with diabetes were treated without or with gemigliptin (300 mg/kg) for 8 weeks. Morphological changes of the glomerular basement membrane (GBM) were observed by electron microscopy and periodic-acid Schiff staining. In addition, we measured blood glucose and urinary albumin excretion and evaluated fibrotic markers using immunohistochemical staining, quantitative reverse transcription polymerase chain reaction analysis, and Western blot analysis.


RESULTS
Gemigliptin did not reduce the blood glucose levels of STZ-treated mice. In gemigliptin-treated mice with STZ, a significant reduction in urinary albumin excretion and GBM thickness was observed. Immunohistological examination revealed that gemigliptin attenuated renal fibrosis induced by STZ and decreased extracellular matrix protein levels, including those of type I collagen and fibronectin, and Smad3 phosphorylation. In cultured rat renal cells, gemigliptin inhibited transforming growth factor β-stimulated type I collagen and fibronectin mRNA and protein levels via down-regulation of Smad3 phosphorylation.


CONCLUSIONS
Our data demonstrate that gemigliptin has renoprotective effects on DKD, regardless of its glucose-lowering effect, suggesting that it could be used to prevent DKD, including in patients with type 1 diabetes.
Division of Endocrinology and Metabolism, Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
Gwon Soo
GS
Jung
Division of Endocrinology and Metabolism, Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
Jae Han
JH
Jeon
Department of Pathology, Keimyung University School of Medicine, Daegu, Korea.
Mi Sun
MS
Choe
Division of Endocrinology and Metabolism, Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
Sung Woo
SW
Kim
Division of Endocrinology and Metabolism, Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
In Kyu
IK
Lee
Division of Endocrinology and Metabolism, Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Korea. mdkmk@dsmc.or.kr.
Mi Kyung
http://orcid.org/0000-0001-5750-3598
MK
Kim
Division of Endocrinology and Metabolism, Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea. kpark@knu.ac.kr.
Keun Gyu
http://orcid.org/0000-0002-8403-1298
KG
Park
DPP-4 inhibitor; Diabetes mellitus, type 1; Renal fibrosis