Ameliorating Effect of Gemigliptin on Renal Injury in Murine Adriamycin-Induced Nephropathy

Abstract

Background. Previous studies have shown the antiapoptotic and anti-inflammatory potential of DPP-IV inhibitor in experimental models of renal injury. We tested whether DPP-IV inhibitor (gemigliptin) ameliorates renal injury by suppressing apoptosis, inflammation, and oxidative stress in mice with adriamycin nephropathy. Methods. Mice were treated with normal saline (control), gemigliptin (GM), adriamycin (ADR), or adriamycin combined with gemigliptin (ADR+GM). Apoptosis, inflammation, and oxidative stress were analyzed via western blotting, real-time PCR, light microscopy, and immunofluorescence. Results. In the ADR+GM group, urine albumin creatinine ratio decreased significantly compared with that in the ADR group on day 15. Glomerulosclerosis index and tubulointerstitial injury index in mice with adriamycin-induced nephropathy decreased after gemigliptin treatment. ADR group showed higher levels of apoptosis, inflammation, and oxidative stress-related molecules compared with the control group. The upregulation of these molecules was significantly reduced by gemigliptin. In the ADR group, the staining intensities of WT-1 and nephrin reduced, but these changes were ameliorated in the ADR+GM group. Conclusion. We demonstrated that gemigliptin ameliorates nephropathy by suppressing apoptosis, inflammation, and oxidative stress in mice administered adriamycin. Our data demonstrate that gemigliptin has renoprotective effects on adriamycin-induced nephropathy.

Figure 1

Effects of gemigliptin on DPP-IV activity and GLP-1 levels. ^∗p < 0.05 compared with (A), ^†p < 0.05 compared with (B), and ^#p < 0.05 compared with (C). p values were obtained using the one-way analysis of variance test followed by Tukey's post hoc test. GM, gemigliptin; ADR, adriamycin; DPP-IV, dipeptidyl peptidase 4; GLP-1, glucagon-like peptide-1.

Figure 2

Glomerulosclerotic index and tubulointerstitial index (%). ^∗p < 0.05 compared with (A), ^†p < 0.05 compared with (B), and ^#p < 0.05 compared with (C). p values were obtained using the one-way analysis of variance test followed by Tukey's post hoc test. Kidney samples (day 30) were sectioned and stained using periodic-acid Schiff (PAS). (A) Control group, (B) GM group, (C) global glomerular sclerosis and tubular injury in ADR group, and (D) focal segmental glomerular sclerosis in ADR+GM group. GSI, glomerular sclerotic index; GM, gemigliptin; ADR, adriamycin.

Figure 3

Results of western blot analysis of renal nitrotyrosine, iNOS, Bax/Bcl-2 ratio, and actin level (a, b, c, and d) and real-time PCR of NOX4 level of kidney tissue (e). ^∗p < 0.05 compared with (A), ^†p < 0.05 compared with (B), and ^#p < 0.05 compared with (C). GM, gemigliptin; ADR, adriamycin; iNOS, inducible nitric oxide synthase; Bcl-2, B cell lymphoma 2; Bax, Bcl-2 associated X protein.

Figure 4

Real-time PCR of inflammation-related molecules (MCP-1, PAI-1, and TNF-α) and fibrotic cytokine (TGF-β1). TNF-α was not significantly different between the groups (p = 0.091). p values were obtained using the one-way analysis of variance test followed by Tukey's post hoc test. ^∗p < 0.05 compared with (A), ^†p < 0.05 compared with (B), and ^#p < 0.05 compared with (C).

Figure 5

Effects of gemigliptin on adriamycin-induced podocyte loss (a); immunofluorescence stain for WT-1 (red) and DAPI (blue) and double-positive cells (pink) (b); mean podocyte number per glomerulus in each group is presented and shown for DAPI-positive and WT-1 positive cells; the asterisk indicates that the difference in mean podocyte number per glomerulus between groups is significant. p values are obtained using the one-way analysis of variance test followed by Tukey's post hoc test. ^∗p < 0.05 compared with (A), ^†p < 0.05 compared with (B), and ^#p < 0.05 compared with (C). GM, gemigliptin; ADR, adriamycin; WT-1, Wilms tumor-1; DAPI, 4′,6-diamidino-2-phenylindole.

Figure 6

Effects of gemigliptin on adriamycin-induced downregulation of nephrin. (a) Immunofluorescence examination of nephrin expression. (b) Nephrin scores by semiquantitative analysis of immunofluorescence staining of nephrin (p < 0.0001). p values were obtained using the one-way analysis of variance test, followed by Tukey's post hoc test. ^∗p < 0.05 compared with (A), ^†p < 0.05 compared with (B), and ^#p < 0.05 compared with (C). GM, gemigliptin; ADR, adriamycin; DAPI, 4′,6-diamidino-2-phenylindole.