Inhibitors of the renin-angiotensin system ameliorates clinical and pathological aspects of experimentally induced nephrotoxic serum nephritis

Abstract

Introduction: Chronic kidney disease (CKD) is a global health concern, but the current treatments only slow down the progression. Thus an improved understanding of the pathogenesis and novel treatments of CKD are needed. The nephrotoxic nephritis (NTN) model has the potential to study the pathogenesis of CKD as it resembles human CKD. The classical treatments with angiotensin II receptor blocker (ARB) or the angiotensin-converting enzyme inhibitor (ACE I) have shown a clinical effect in CKD.

Methods: We characterized the disease development in the NTN model over 11 weeks by investigating functional and histopathological changes. We tested doses of 15 and 30 mg/kg/day enalapril and losartan in the NTN model in order to investigate the effect of inhibiting the renin-angiotensin-system (RAS).

Results: The NTN model displayed albuminuria peaking on days 6-7, mesangial expansion (ME), renal fibrosis, inflammation and iron accumulation peaking on day 42. However, albuminuria, ME, renal fibrosis and inflammation were still significantly present on day 77, suggesting that the NTN model is useful for studying both the acute and chronic disease phases. Enalapril and losartan significantly enhanced the glomerular filtration rate (GFR) and decreased albuminuria, ME, renal fibrosis and inflammation of NTN-induced kidney disease in mice.

Conclusions: This is the first study showing a comprehensive pathological description of the chronic features of the murine NTN model and that inhibiting the RAS pathway show a significant effect on functional and morphological parameters.

Keywords: Nephrotoxic serum nephritis; angiotensin II receptor blocker; angiotensin-converting enzyme inhibitor; pathology.

Figure 1.

A time course evaluation of clinical measurements of the passive NTN model. (A) XY plot showing body weight (BW) over time. (B) XY plot showing the urinary albumin excretion rate (UAER). Data are shown as mean ± SD. ***p < .001, ****p < .0001, NTN group vs. healthy control group by one-way ANOVA.

Figure 2.

A time course evaluation of morphological changes in the passive NTN model. (A) Scatter plot is showing semi-quantification of Perl positive area in the cortex area. (B) Scatter plot is showing semi-quantification of Collagen III positive area in the cortex area. (C) Scatter plot is showing semi-quantification of the Ki-67 positive area in the cortex area. (D) Representative images are showing the Ki-67 positive area in the cortex area. Data are shown as mean ± SD. **p < .01, ****p < .0001 NTN groups vs. healthy control groups and, #p < .05, ##p < .01, ###p < .001 ####p < .0001 NTN group vs. NTN group by one-way ANOVA using Tukey’s multiple comparisons test (n = 10).

Figure 3.

Time course of renal inflammatory response. (A) Scatter plot is showing semi-quantification of the CD45 positive area of the cortex area. (B) Scatter plot is showing semi-quantification of the CD3 positive area of the cortex area. (C) Scatter plot is showing semi-quantification of F4/80 positive area of the cortex area. (D) Scatter plot is showing semi-quantification of the C3d positive area of the cortex area. (E) Representative histopathological images of the disease change over time. Data are shown as mean ± SD. **p < .01, ***p < .001, ****p < .0001 NTN groups vs. healthy control groups and, ##p < .01, ###p < .001 ####p < .0001 NTN group vs. NTN group by one-way ANOVA using Tukey’s multiple comparisons test (n = 10).

Figure 4.

Inhibitors of the renin-angiotensin system improves the kidney function. Scatter plot showing the glomerular filtration rate (GFR) measured on day 38–40. Data are shown as mean ± SD. *p < .05, ****p < .0001 groups vs. vehicle group by one-way ANOVA.

Figure 5.

Effect of inhibitors of the renin-angiotensin system on histopathology. (A) Scatter plot is showing the mean glomerular mesangial expansion (ME) score. (B) Scatter plot is showing semi-quantification of collagen III positive area of the cortex area. (C) Scatter plot is showing semi-quantification of the CD45 positive area of the cortex area. (D) Scatter plot is showing semi-quantification of the C3d positive area of the cortex area. (E) Representative histopathological images. Data are shown as mean ± SD. *p < .05, **p < .01, ***p < .001, ****p < .0001 groups vs. vehicle group by one-way ANOVA using Tukey’s multiple comparisons test or Kruskal–Wallis multiple testing (n = 10).