Renal interstitial fibrosis is reduced in angiotensin II type 1a receptor-deficient mice.
Unilateral ureteral obstruction (UUO) results in tubulointerstitial fibrosis of the affected kidney by stimulating the renin-angiotensin system. This study established a UUO model in angiotensin type 1a receptor (AT1a) deficient (mutant) mice to elucidate the role of angiotensin II through AT1a on the fibrosis of the obstructed kidney (OBK). The relative volume of the tubulointerstitium was measured by an image analyzer; deposition of collagen types III and IV and monocyte/macrophage infiltration were histologically examined using specific antibodies. Also determined were the mRNA levels of transforming growth factor-beta by Northern blot analysis. Nuclear factor-kappaB activity was assessed by gel shift assay. UUO in wild mice resulted in a marked expansion of relative volume of the tubulointerstitium, together with increased deposition of collagen types III and IV and number of infiltrated monocytes/macrophages in the interstitium, relative to sham-operated mice. In comparison, these changes were significantly lower in mutant mice with UUO. The mRNA level of transforming growth factor-beta was significantly higher in the OBK of wild mice with UUO compared with sham-operated mice. In contrast, the increase in mRNA level in the OBK of mutant mice was significantly less than in wild mice. Finally, UUO resulted in activation of nuclear factor-kappaB in wild mice but was inhibited in the OBK of mutant mice. The results provide direct evidence that angiotensin II acting via the AT1a plays a pivotal role in the development of tubulointerstitial fibrosis in UUO.
Satoh
Minoru
M
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Kashihara
Naoki
N
Division of Nephrology, Department of Internal Medicine, Kawasaki Medical School, Kurashiki, Japan.
Yamasaki
Yasushi
Y
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Maruyama
Keisuke
K
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Okamoto
Kazunori
K
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Maeshima
Youhei
Y
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Sugiyama
Hitoshi
H
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
Sugaya
Takeshi
T
Discovery Research Laboratory, Tanabe Seiyaku Co., Ltd., Osaka, Japan.
Murakami
Kazuo
K
Institute of Applied Biochemistry, Tsukuba Advanced Research Alliance, University of Tsukuba, Ibaragi, Japan.
Makino
Hirofumi
H
Department of Medicine III, Okayama University Medical School, Okayama, Japan.
D000818:Animals; D003094:Collagen / Q000032:analysis; D005260:Female; D005355:Fibrosis; D007150:Immunohistochemistry; D007668:Kidney / Q000473:pathology*; D008264:Macrophages / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000235:genetics; D014517:Ureteral Obstruction / Q000473:pathology*
D016328:NF-kappa B; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D016212:Transforming Growth Factor beta; D003094:Collagen