Angiotensin II type 2 receptor antagonist reduces bleomycin-induced pulmonary fibrosis in mice.
BACKGROUND
The role of angiotensin II type 2 receptor (AT2) in pulmonary fibrosis is unknown. To evaluate the influence of angiotensin II type 1 receptor (AT1) and AT2 antagonists in a mouse model of bleomycin (BLM)-induced pulmonary fibrosis.


METHODS
We examined effects of the AT1 antagonist (AT1A) olmesartan medoxomil (olmesartan) and the AT2 antagonist (AT2A) PD-123319 on BLM-induced pulmonary fibrosis, which was evaluated by Ashcroft's pathological scoring and hydroxyproline content of lungs. We also analyzed the cellular composition and cytokine levels in bronchoalveolar lavage fluid (BALF).


RESULTS
With olmesartan, the lung fibrosis score and hydroxyproline level were significantly reduced, and lymphocyte and neutrophil counts and tumor necrosis factor (TNF)-alpha levels in BALF were reduced on day 7. On day 14, macrophage and lymphocyte counts in BALF were reduced, accompanied by a reduction in the level of transforming growth factor (TGF)-beta1. With PD-123319, the lung fibrosis score and hydroxyproline level were reduced. On day 7, macrophage, lymphocyte, and neutrophil counts in BALF were reduced, accompanied by reductions in TNF-alpha and monocyte chemoattractant protein (MCP)-1 levels. On day 14, macrophage, lymphocyte, and neutrophil counts in BALF were also reduced, accompanied by a reduction in the level of macrophage inflammatory protein (MIP)-2 level but not TGF-beta1.


CONCLUSIONS
Both AT1 and AT2 are involved in promoting interstitial pneumonia and pulmonary fibrosis via different mechanisms of action.
Waseda
Yuko
Y
Respiratory Medicine, Cellular Transplantation Biology, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa 920-8641, Japan. yuko_m@med3.m.kanazawa-u.ac.jp
Yasui
Masahide
M
Nishizawa
Yoriko
Y
Inuzuka
Kanako
K
Takato
Hazuki
H
Ichikawa
Yukari
Y
Tagami
Atsuro
A
Fujimura
Masaki
M
Nakao
Shinji
S
D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D057912:Angiotensin II Type 2 Receptor Blockers; D000818:Animals; D001761:Bleomycin; D001772:Blood Cell Count; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D004195:Disease Models, Animal; D006909:Hydroxyproline / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology*; D019402:Macrophage Inflammatory Proteins; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology*; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000378:metabolism*; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism*; D013777:Tetrazoles / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; D007093:Imidazoles; D019402:Macrophage Inflammatory Proteins; D011725:Pyridines; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles; D014409:Tumor Necrosis Factor-alpha; D014662:Vasoconstrictor Agents; D001761:Bleomycin; C073402:PD 123319; C437965:olmesartan; D006909:Hydroxyproline