Addition of the Antioxidant Probucol to Angiotensin II Type I Receptor Antagonist Arrests Progressive Mesangioproliferative Glomerulonephritis in the Rat

Abstract

Angiotensin II (Ang II) and reactive oxidative species (ROS) that are produced by NADPH oxidase have been implicated in the progression of glomerulonephritis (GN). This study examined the effect of simultaneously interrupting Ang II and ROS with an Ang II receptor blocker (ARB), candesartan, and a free radical scavenger, probucol, in a model of progressive mesangioproliferative GN induced by the injection of anti-Thy-1 antibody into uninephrectomized rats. Nephritic rats were divided into four groups and given daily oral doses of the following: Vehicle, 1% probucol diet, 70 mg/L candesartan in drinking water, and probucol plus candesartan. These treatments lasted until day 56. Vehicle-treated nephritic rats developed progressively elevated proteinuria and glomerulosclerosis. Candesartan kept proteinuria significantly lower than vehicle or probucol. The addition of probucol to candesartan normalized urinary protein excretion. Increases in BP in nephritic rats were lowered by these treatments, except with probucol. It is interesting that both glomerular cell number and glomerulosclerosis were significantly decreased by candesartan and normalized by the addition of probucol. Immunohistochemical studies for TGF-␤1, collagen type I, and fibronectin revealed that the combined treatment abolished glomerular fibrotic findings compared with candesartan. In addition, glomerular expression of NADPH oxidase components and superoxide production suggested that the combined treatment completely eliminated NADPH oxidase-associated ROS production. In conclusion, our study provides the first evidence that the antioxidant probucol, when added to an Ang II receptor blockade, fully arrests proteinuria and disease progression in GN. Furthermore, the data suggest that NADPH oxidase-associated ROS production may play a pivotal role in the progression of GN. The combination of probucol and candesartan may represent a novel route of therapy for patients with progressive GN.

Probucol Inhibited Nox2 Expression and Attenuated Podocyte Injury in Type 2 Diabetic Nephropathy of db/db Mice

“…This result was consistent with the previous study that probucol inhibited Nox2 but not Nox4 in progressive mesangioliferative glomerulonephritis. 9) Upregulation of Nox2 or subunits have also been reported in other several studies about diabetic nephropathy. [44][45][46][47] However, increased expression of Nox4 mRNA and protein in diabetic nephropathy has also been implicated, 46,48) and treatment of diabetic animals with Nox4 antisense RNA decreases kidney pathology.…”

“…7,8) The addition of probucol to candesartan normalized urinary protein excretion, glomerular cell number and glomerulosclerosis, and completely eliminated reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-associated reactive oxygen species (ROS) production in rat progressive mesangioproliferative glomerulonephritisin. 9) Probucol suppressed oxidative stress and improve glomerulosclerosis in the kidneys of streptozotocin (STZ) induced type 1 diabetic rats. 10) Moreover, interestingly, recent clinical trial indicates that probucol reduce urinary protein, prevent the progression of DN, and extend the interval to initiation of hemodialysis therapy in type 2 diabetic patients with clinical albuminuria.…”

Nox enzymes, ROS, and chronic disease: An example of antagonistic pleiotropy

“…Likewise, glomerular mesangial injury in rats treated chronically with aldosterone and salt is associated with induction of Nox2, Nox4 and p22 phox [114], increased p47 phox and p67 phox in the membrane fraction (indicating activation of the Nox2 system), and increased renal ROS and [102]. In an Angiotensin II-induced mesangioproliferative model of glomerulonephritis, Nox2 and Nox4 induction were associated with disease progression, and treatment with the antioxidant probucol in combination with Angiotensin II receptor blockade fully arrested disease progression and proteinuria [115].…”

Effect of angiotensin II on iron-transporting protein expression and subsequent intracellular labile iron concentration in human glomerular endothelial cells

“…13,44 The results presented in Figures 1 and 2 show that Ang II-stimulated iron uptake into HGECs. In addition, it was expected that ferrous iron would be increased because Ang II facilitates O 2 À production by the activation of NOX [14][15][16][17][18][19][20][21] and O 2 À participates to a certain extent in the reduction and release of ferrous iron from iron storage proteins within cells. [25][26][27] Therefore, it is worth analyzing whether the Ang II increases the total amount of ferrous Effect of Ang II on iron-transporting protein S Tajima et al iron in HGECs.…”

“…14,15 Once activated, NOX uses intracellular nicotinamide adenine dinucleotide phosphate and nicotinamide adenine dinucleotide as electron donors to catalyze the single electron reduction of extracellular molecular oxygen to superoxide anion (O 2 À ). This radical in turn is rapidly converted by superoxide dismutase to hydrogen peroxide (H 2 O 2 ), a more stable, membranepermeant ROS that widely participates in signaling 14,15 and is a mediator of tissue injury 16,17 not only in phagocytes but also in nonphagocytic cells including mesangial cells, 18,19 vascular smooth muscle cells 20 and vascular endothelial cells. 21 In 22 Iron-dependent generation of oxygen-derived free radicals is known to induce oxidation of proteins, lipids and lipoproteins, nucleic acids, carbohydrates and other cellular components.…”