Treatment with pyrrolidine dithiocarbamate improves proteinuria, oxidative stress, and glomerular hypertension in overload proteinuria

Abstract

We evaluated whether the blockade of the proinflammatory transcription factor NF-kappaB would modify the oxidative stress, inflammation, and structural and hemodynamic alterations found in the kidney as a result of massive proteinuria. Twenty male Sprague-Dawley rats were injected with 2 g of BSA intraperitoneally daily for 2 wk. Ten of them received in addition the inhibitor of NF-kappaB activation pyrrolidine dithiocarbamate (PDTC; 200 mg.kg(-1).day(-1) sc) and the rest received vehicle. Seven rats that received intraperitoneal saline were used as controls. Glomerular hemodynamics were studied after 14 days. Markers of oxidative stress (NF-kappaB subunit p65+ cells, 3-nitrotyrosine, and 4-hydroxynonenal), inflammation (cortical CD68+ cells and NOS-II), and afferent arteriole damage were assessed by immunohistochemistry and morphometry. Activity of antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase was evaluated in renal cortex and medulla. Albumin overload induced massive proteinuria, oxidative stress with reduced activity of antioxidant enzymes, NF-kappaB activation, inflammatory cell infiltration, a significant presence of proteinaceous casts, systemic and glomerular hypertension, as well as arteriolar remodeling. Treatment with PDTC prevented or improved all of these findings. In this model of nephrotic syndrome, we demonstrate a key role for oxidative stress and inflammation in causing systemic and glomerular hypertension and proteinuria. Oxidative stress and inflammation may have a key role in accelerating renal injury associated with intense proteinuria.

Fig. 1.

Proteinuria (left) and systolic blood pressure (middle) follow-up. ▵, Saline (n = 9); ▾, albumin overload (AO; n = 10); ○, AO+pyrrolidine dithiocarbamate (PDTC) treatment (n = 10). Right: whole glomerular filtration rate (GFR) at day 14. Data are means ± SE. *P < 0.05 vs. saline. **P < 0.05 vs. AO.

Fig. 2.

Glomerular pressure (left) and afferent arteriole media-to-lumen (right) ratio in saline (n = 9), AO (n = 10), and AO+PDTC (n = 10). Data are means ± SE.

Fig. 3.

Quantification of renal markers of oxidative stress: p65, 3-nitrotyrosine (3-NT), and 4-hydroxynonenal (4-HNE) in renal cortex and medulla. Quantification of markers of inflammation: CD68 and NOS II in renal cortex. Data are means ± SE.

Fig. 4.

Microphotographs of NF-κB activation (hematoxylin and anti-p65 antibody), 3-NT (hematoxylin and anti-3-NT antibody), 4-HNE (hematoxylin and anti-4-HNE antibody), tubulointerstitial monocytes/macrophages infiltration (PAS and anti-CD68 antibody), and afferent arteriole morphology (PAS and anti α-actin smooth muscle antibody).