Aldose reductase inhibition prevents endotoxin-induced uveitis in rats.
OBJECTIVE
The purpose of the present study was to elucidate the role of the polyol pathway enzyme aldose reductase (AR) in the mediation of ocular inflammation in a rat model of endotoxin-induced uveitis (EIU).


METHODS
EIU was induced by a subcutaneous injection of 200 microg lipopolysaccharide (LPS) in male Lewis rats treated with the AR inhibitor, zopolrestat (25 mg/kg body weight, intraperitoneally) or its carrier. The rats were killed 24 hours after LPS injection, the eyes were enucleated immediately, and aqueous humor (AqH) was collected. The number of infiltrating cells, protein concentration, and levels of nitric oxide (NO), tumor necrosis factor (TNF)-alpha, and prostaglandin E(2) (PGE(2)) in the AqH were determined. Immunohistochemical analysis was performed in paraformaldehyde-fixed eye sections by staining with antibodies against iNOS, COX-2, TNF-alpha, NF-kappaB, and AR. The levels of reactive oxygen species (ROS) in rat eye sections were determined by dihydroethidium (hydroethidine) fluorescence staining.


RESULTS
In the EIU rat eye AqH, both the number of infiltrating cells and protein concentrations of the inflammatory markers, TNF-alpha, NO, and PGE(2) were significantly higher than in the control rats, and inhibition of AR by zopolrestat suppressed the LPS-induced increases. The LPS-induced increased expression of AR, TNF-alpha, iNOS, and COX-2 proteins in the ciliary body, corneal epithelium, and retinal wall was also significantly inhibited by zopolrestat. Furthermore, AR inhibition prevented the LPS-induced increased levels of ROS and activation of NF-kappaB in the ciliary body, corneal epithelium, and retinal wall of the rat eye. AR inhibition also prevented the LPS-induced activation of NF-kappaB and expression of COX-2 and iNOS in the human monocyte cell line U-937.


CONCLUSIONS
The results indicate that AR inhibition suppresses the inflammation in EIU by blocking the expression and release of inflammatory markers in ocular tissues, along with the attenuation of NF-kappaB activation. This finding suggests that AR inhibition could be a novel therapeutic target for the treatment of uveitis and associated ocular inflammation.
Yadav
Umesh C S
UC
Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555-0647, USA.
Srivastava
Satish K
SK
Ramana
Kota V
KV
D000449:Aldehyde Reductase / Q000037:antagonists & inhibitors*; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D052160:Benzothiazoles / Q000494:pharmacology*; D015153:Blotting, Western; D015232:Dinoprostone / Q000378:metabolism; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004926:Escherichia coli; D006801:Humans; D007124:Immunoenzyme Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D010793:Phthalazines / Q000494:pharmacology*; D051381:Rats; D011917:Rats, Inbred Lew; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells; D014605:Uveitis / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*
D052160:Benzothiazoles; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010793:Phthalazines; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C067172:zopolrestat; D000449:Aldehyde Reductase; D052247:Nitric Oxide Synthase Type II; D015232:Dinoprostone