Beneficial effects of combination therapy with olmesartan and azelnidipine in murine polycystic kidneys.

BACKGROUND: Some reports have discussed the synergic effects of angiotensin II receptor blockers and calcium channel blockers on vascular injury or microalbuminuria. The present study examined the effects of combination treatment with olmesartan and azelnidipine on polycystic kidney disease in a mouse model (DBA/2-FG pcy mouse) and its mechanisms. METHODS: The mice were divided into the following groups: combination treatment (n = 21), olmesartan treatment alone (n = 23), azelnidipine treatment alone (n = 29) or untreated (n = 26). Mean blood pressure and kidney weight were measured at 4 and 8 weeks after the treatment. Renal expression of angiotensin II, gp91, nitrotyrosine and endothelial NO synthase (eNOS) were examined by immunostaining. In addition, extracellular signal-regulated kinase activation was evaluated by Western blotting. RESULTS: Olmesartan decreased the numbers of angiotensin II and gp91-positive cells, mainly macrophages, and cyst size at 4 weeks. However, only combination treatment suppressed cell infiltration, extracellular signal-regulated kinase activation and interstitial fibrosis with a significant change in the kidney weight/body weight ratio. The azelnidipine and combination treatment increased the numbers of interstitial eNOS-positive cells. CONCLUSION: The combination treatment protects against cyst enlargement in polycystic kidney disease by suppressing interstitial inflammation, fibrosis and oxidative stress by upregulating eNOS expression during disease course.

Reactive oxygen species-mediated signaling pathways in angiotensin II-induced MCP-1 expression of proximal tubular cells.

Angiotensin II (AngII) has pleiotropic effects, the most well known of which is the generation of reactive oxygen species (ROS) and chemokines in inflammatory lesions. Monocyte chemoattractant protein-1 (MCP-1) is considered a major chemokine in the pathogenesis of kidney diseases. We examined signaling pathways of AngII-induced MCP-1 expression and the role of ROS in the murine proximal tubular cells (mProx) using various inhibitors. Furthermore, we compared the signaling pathways between mProx and mesangial cells (MC). AngII-induced MCP-1 protein expression in mProx at 6 h was largely blocked by ROS (N-acetylcysteine; 82 +/- 14%), Ras (N-acetyl-S-trans,trans-farnesyl-L-cysteine; 82 +/- 13%), and nuclear factor-kappaB (NF-kappaB) (parthenolide; 89 +/- 7.9%) inhibitors. Both AT1 receptor (AT1R) (Olmesartan; 41 +/- 12%) and the AT2R (PD123319; 24 +/- 11%) antagonists partially blocked the MCP-1 expression. Furthermore, mitogen-activated protein kinase (MAPK) pathways were also implicated in this protein expression, but it is less dependent on ROS/Ras pathways. In MC, protein kinase (calphostin C; 84 +/- 2.8%) and NF-kappaB (89 +/- 1.4%) inhibitors attenuated acute AngII-induced MCP-1 expression stronger than ROS/Ras inhibitors (1.0 +/- 0.9/29 +/- 9.5%). MAPK pathways, especially p38 MAPK, were involved in MC more than in mProx. AT1R (69 +/- 8.6%) and AT2R (57 +/- 21%) antagonists also were blocked. We suggested that, although NF-kappaB activation has a critical role, signaling pathways are different between mProx and MC. ROS-mediated signaling in mProx may have more contribution to AngII-induced inflammatory responses than to those in MC.