Angiotensin receptor blocker ameliorates the development of tubulointerstitial injury and fibrosis associated with tubular proteinuria observed in subclinical diabetic kidney disease

Figures

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  FIGURE 1. Glomerular structure and function are preserved in subclinical diabetic kidney disease. Male Wistar rats (10 weeks old) were used to develop streptozotocin-induced type 1 diabetes mellitus, and then, when indicated, daily treated with losartan (30 mg/kg/day) via gavage during 8 consecutive weeks. Four groups were generated (as described in the Methods section): 1) CONT group (n = 9); 2) ARB group (n = 9); 3) subDKD group (n = 9); and 3) subDKD + ARB group (n = 7). (A) Plasma creatinine concentration, (B) creatinine clearance (CCr), (C) Representative images of micrographs from kidney cortex slices stained with Periodic acid-Schiff (PAS) reagent (scale bar = 50 μm). The glomeruli analyzed are shown in the inset presented in the lower panels. Based on these images, the glomerular tuft area (D) the glomerular cellularity (E) and the mesangium area (F) were measured. Open circles represent individual animals. Normally distributed data were expressed as mean ± SD, while non-normally distributed data were expressed as median with interquartile range. Statistical analysis for panels (B,D,F) was performed using a two-way ANOVA test following Tukey’s post-test. Statistical analysis for…

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  FIGURE 2. Losartan treatment attenuated the tubular dysfunction observed in subclinical diabetic kidney disease. Male Wistar rats (10 weeks old) were used to develop streptozotocin-induced type 1 diabetes mellitus, and then, when indicated, daily treated with losartan (30 mg/kg/day) via gavage during 8 consecutive weeks. Four groups were generated (as described in the Methods section): 1) CONT group (n = 9); 2) ARB group (n = 9); 3) subDKD group (n = 9); and 3) subDKD + ARB group (n = 7). (A) Renal clearance of Na+ (CNa+), (B) renal clearance of Cl− (CCl-), (C) fractional excretion of Na+ (FENa+), and (D) fractional excretion of Cl− (FECl-). Open circles represent individual animals. Normally distributed data were expressed as mean ± SD, while non-normally distributed data were expressed as median with interquartile range. Statistical analysis for panels (A,B) was performed using the Kruskal–Wallis test following Dunn’s post-test. Statistical analysis for panels (C,D) was performed using a two-way ANOVA test following Tukey’s post-test. *P < 0.05 versus CONT group. #P < 0.05 versus the subDKD group.

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  FIGURE 3. Losartan treatment ameliorated the development of tubular proteinuria observed in subclinical diabetic kidney disease. Male Wistar rats (10 weeks old) were used to develop streptozotocin-induced type 1 diabetes mellitus, and then, when indicated, daily treated with losartan (30 mg/kg/day) via gavage during 8 consecutive weeks. Four groups were generated (as described in the Methods section): 1) CONT group (n = 9); 2) ARB group (n = 9); 3) subDKD group (n = 9); and 3) subDKD + ARB group (n = 7). (A) Urinary protein mass excretion (mg/24 h), (B) urinary protein:creatinine ratio (UP:Cr), (C) renal clearance of proteins (Cproteins), and (D) fractional excretion of proteins (FEproteins). (E) In vivo BSA-FITC uptake assay (n = 4/group). (F) Ex vivo assay showing the direct effect of high glucose (D (+)-glucose 25 mM) and 10−7 M losartan treatment on the BSA-FITC uptake in renal cortex explants (n = 4). Open circles represent individual animals. Normally distributed data were expressed as mean ± SD, while non-normally distributed data were expressed as median with interquartile range. Statistical analysis for panels (A,C–F) was performed using a two-way ANOVA test following Tukey’s…

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  FIGURE 4. Losartan treatment attenuated the development of tubulointerstitial injury observed in subclinical diabetic kidney disease. Male Wistar rats (10 weeks old) were used to develop streptozotocin-induced type 1 diabetes mellitus, and then, when indicated, daily treated with losartan (30 mg/kg/day) via gavage during 8 consecutive weeks. Four groups were generated (as described in the Methods section): 1) CONT group (n = 9); 2) ARB group (n = 9); 3) subDKD group (n = 9); and 3) subDKD + ARB group (n = 7). Urinary lactate dehydrogenase (LDH, (A) and urinary γ-glutamyltransferase (γ-GT, (B) were measured. Open circles represent individual animals. Normally distributed data were expressed as mean ± SD, while non-normally distributed data were expressed as median with interquartile range. (C) Representative images from kidney slices stained with HE (scale bar = 50 μm). Based on these images, the kidney injury score ((D) n = 5–7) was measured. (E) Positive Spearman correlation between the kidney injury score and proteinuria. (F) Representative images of micrographs from kidney cortex slices stained with Periodic acid-Schiff (PAS) reagent (scale bar = 50 μm). Based on these images, the…

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  FIGURE 5. Losartan treatment attenuated the development of fibrosis observed in subclinical diabetic kidney disease. Male Wistar rats (10 weeks old) were used to develop streptozotocin-induced type 1 diabetes mellitus, and then, when indicated, daily treated with losartan (30 mg/kg/day) via gavage during 8 consecutive weeks. Four groups were generated (as described in the Methods section): 1) CONT group (n = 9); 2) ARB group (n = 9); 3) subDKD group (n = 9); and 3) subDKD + ARB group (n = 7). (A) Representative images of micrographs from kidney cortex slices stained with SiriusRed (scale bar = 50 μm). (B) Quantification of intensity related to red collagen fibers (n = 4–6). Open circles represent individual animals. Normally distributed data were expressed as mean ± SD. (C) Positive Pearson correlation between kidney injury score and proteinuria. (D) Type 1 collagen deposition observed in the polarized light microscopy. Statistical analysis for panel (B) was performed using a two-way ANOVA test following Tukey’s post-test. *P < 0.05 versus CONT group. #P < 0.05 versus the subDKD group.