Suppression of ocular inflammation in endotoxin-induced uveitis by inhibiting nonproteolytic activation of prorenin.
OBJECTIVE
A recent study revealed that angiotensin receptor signaling mediates ocular inflammation and neovascularization. It was also found that prorenin undergoes nonproteolytic activation leading to upregulation of the renin-angiotensin system (RAS) when prorenin receptor interacts specifically with the handle region of prorenin. The purpose of the present study was to elucidate the role of the receptor-dependent nonproteolytic activation of prorenin in ocular inflammation in endotoxin-induced uveitis (EIU).


METHODS
EIU was induced in Long-Evans rats by a single intraperitoneal injection of 100 microg lipopolysaccharide (LPS). Tissue localization of total prorenin, prorenin receptor, and activated prorenin in the EIU retina was examined by immunohistochemistry. To inhibit the prorenin receptor-mediated upregulation of the RAS, a decoy handle-region peptide (HRP) was intraperitoneally administered 24 hours before and immediately after the injection of LPS. Twenty-four hours after LPS injection, leukocyte adhesion to the retinal vasculature was evaluated with a concanavalin A lectin perfusion-labeling technique. In addition, leukocyte infiltration into the vitreous cavity and protein concentration in the anterior chamber were also measured. Retinal mRNA and protein levels of intercellular adhesion molecule (ICAM)-1, interleukin (IL)-6, and C-C chemokine ligand (CCL) 2/monocyte chemotactic protein (MCP)-1 were examined by RT-PCR and ELISA.


RESULTS
Retinal vessels in rats with EIU were strongly positive for total prorenin, prorenin receptor, and activated prorenin. Systemic treatment with HRP resulted in dose- and time-dependent inhibition of the leukocyte adhesion and infiltration and the protein leakage, all of which were increased by the induction of EIU. Retinal mRNA expression and protein levels of ICAM-1, CCL2/MCP-1 and IL-6, induced in rats with EIU, were also significantly suppressed with application of HRP.


CONCLUSIONS
These findings demonstrate for the first time that nonproteolytically activated prorenin plays a significant role in the development of ocular inflammation in the EIU model. The present study suggests the potential use of HRP, a decoy peptide binding to the prorenin receptor, as a therapeutic agent to reduce ocular inflammation.
Satofuka
Shingo
S
Laboratory of Retinal Cell Biology, Department of Ophthalmology, Keio University School of Medicine, Tokyo, and Department of Ophthalmology, Kobe City General Hospital, Japan.
Ichihara
Atsuhiro
A
Nagai
Norihiro
N
Yamashiro
Kenji
K
Koto
Takashi
T
Shinoda
Hajime
H
Noda
Kousuke
K
Ozawa
Yoko
Y
Inoue
Makoto
M
Tsubota
Kazuo
K
Suzuki
Fumiaki
F
Oike
Yuichi
Y
Ishida
Susumu
S
D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology*; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli; D007124:Immunoenzyme Techniques; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D007962:Leukocytes / Q000502:physiology; D008070:Lipopolysaccharides / Q000633:toxicity; D010446:Peptide Fragments / Q000276:immunology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans; D011956:Receptors, Cell Surface / Q000378:metabolism; D012083:Renin / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology; D012160:Retina / Q000378:metabolism; D012171:Retinal Vessels / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014605:Uveitis / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D000093342:Prorenin Receptor; D000092502:Renin Inhibitors
D019138:Antibodies, Blocking; D018932:Chemokine CCL2; D018799:Intercellular Adhesion Molecule-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D012083:Renin; D000093342:Prorenin Receptor; D000092502:Renin Inhibitors; C491766:Ccl2 protein, rat