Aliskiren Ameliorates Renal Inflammation and Fibrosis Induced by Unilateral Ureteral Obstruction in Mice

Purpose: Renin-angiotensin system activation is involved in inflammation and fibrosis in the kidney. Aliskiren, a direct renin inhibitor, decreases renin-angiotensin system activation, including plasma renin activity and angiotensin II, but increases the prorenin level, which may promote inflammation and fibrosis in renal tissue. Thus, we evaluated whether inhibiting the renin-angiotensin system by aliskiren would decrease renal inflammation and fibrosis in a mouse model of unilateral ureteral obstruction. Materials and Methods: Ten-week-old male C57BL/6 mice (Samtako, Kyoung Gi-Do, Korea) weighing 30 to 33 gm were divided into 4 groups, including vehicle or aliskiren treated sham operated and vehicle or aliskiren treated unilateral ureteral obstruction groups. We evaluated plasma renin activity, and plasma renin and renal mRNA expression levels of renin and (pro) renin receptor. To evaluate inflammation and fibrosis renal mRNA expression of monocyte chemotactic protein-1, osteopontin and transforming growth factor-beta was measured. Hematoxylin and eosin, Masson's trichrome staining, and immunohistochemical staining for CD68, transforming growth factor-beta and alpha-smooth muscle actin were performed. Results: Plasma renin activity was significantly lower in the aliskiren treated obstruction group than in the vehicle treated obstruction group. Aliskiren treatment increased renal mRNA expression of renin. The number of CD68 positive cells, and renal monocyte chemotactic protein-1 and osteopontin mRNA levels were significantly higher in mice with unilateral ureteral obstruction than in sham operated mice. Aliskiren decreased the increased levels of these inflammation markers. Aliskiren also decreased renal transforming growth factor-beta mRNA expression, transforming growth factor-beta and alpha-smooth muscle actin immuno-staining, and Masson's trichrome stained areas of unilateral ureteral obstruction kidneys. Conclusions: Aliskiren has anti-inflammatory and antifibrotic effects in an experimental unilateral ureteral obstruction mouse model.