Indolent course of tubulointerstitial disease in a mouse model of subpressor, low-dose nitric oxide synthase inhibition

Abstract

Deficiency of nitric oxide (NO) represents a consistent manifestation of endothelial dysfunction (ECD), and the accumulation of asymmetric dimethylarginine occurs early in renal disease. Here, we confirmed in vitro and in vivo the previous finding that a fragment of collagen XVIII, endostatin, was upregulated by chronic inhibition of NO production and sought to support a hypothesis that primary ECD contributes to nephrosclerosis in the absence of other profibrotic factors. To emulate more closely the indolent course of ECD, the study was expanded to an in vivo model with N(G)-monomethyl-L-arginine (L-NMMA; mimics effects of asymmetric dimethylarginine) administered to mice in the drinking water at subpressor doses of 0.3 and 0.8 mg/ml for 3-6 mo. This resulted in subtle but significant morphological alterations detected in kidneys of mice chronically treated with L-NMMA: 1) consistent perivascular expansion of interstitial matrix components at the inner stripe of the outer medulla and 2) collagen XVIII/endostatin abundance. Ultrastructural abnormalities were detected in L-NMMA-treated mice: 1) increased activity of the interstitial fibroblasts; 2) occasional detachment of endothelial cells from the basement membrane; 3) splitting of the vascular basement membrane; 4) focal fibrosis; and 5) accumulation of lipofuscin by interstitial fibroblasts. Preembedding labeling of microvasculature with anti-CD31 antibodies showed infiltrating leukocytes and agglomerating platelets attaching to the visibly intact or denuded capillaries. Collectively, the data indicate that the mouse model of subpressor chronic administration of L-NMMA is not a robust one (endothelial pathology visible only ultrastructurally), and yet it closely resembles the natural progression of endothelial dysfunction, microvascular abnormalities, and associated tubulointerstitial scarring.

Postobstructive regeneration of kidney is derailed when surge in renal stem cells during course of unilateral ureteral obstruction is halted

“…Therefore, we addressed the next question: Does inhibition of NOS with nonhypertensinogenic doses of L-NMMA affect stem cell recruitment by the obstructed kidney? To avoid any contribution of elevation in blood pressure to the results of UUO, we employed subpressor doses of L-NMMA that have been shown to induce a mild endothelial dysfunction but no proteinuria or other functional changes in the kidney (19). UUO kidneys from L-NMMAtreated mice showed a similar reduction of KW/BW compared with CK or RUUO kidney of nontreated mice.…”

The Krebs Cycle and Mitochondrial Mass Are Early Victims of Endothelial Dysfunction

“…25 Hence, the observed switch to glycolytic metabolism in the face of normoxia is reminiscent of the Warburg effect, the phenomenon of preferential glycolysis in tumor cells. 26 Most likely, selective depletion of aconitase-2 and ECHS-1 are responsible for the inhibition of Krebs cycle in our model, making it phenomenologically similar to the Warburg effect in cancer cells.…”

Curtailing Endothelial TGF-β Signaling Is Sufficient to Reduce Endothelial-Mesenchymal Transition and Fibrosis in CKD

“…Pimonidazole immunostaining was performed using a Hypoxyprobe-1 Plus Kit (Hypoxyprobe, Inc.) on 4-mm thick paraffin sections. 43 …”