Modulation of leukocyte-endothelium interaction by nitric oxide synthase inhibitors: effects on leukocyte adhesion in endotoxin-induced uveitis.
OBJECTIVE
To examine the effects of the nitric oxide synthase (NOS) inhibitors aminoguanidine (AG) and L-NAME on leukocyte adhesion in endotoxin-induced uveitis (EIU).


METHODS
Uveitis was induced in Lewis rats (n = 124) by LPS injection (Salmonella typhimurium).


METHODS
Rats either (1) did not receive any LPS or other treatments (controls), received (2) only subcutaneous saline injections with LPS administration, (3) a single s.c. dose of AG (100 mg/kg body weight) at the time of LPS administration, (4) a single s.c. injection of AG 8 h after LPS injection, (5) s.c. injections of AG at the time of LPS administration and 8 h after LPS injection or (6) received a single dose of L-NAME (75 mg/kg body weight) at the time of LPS administration.


METHODS
Intravital microscopy (IVM) of iris vessels was performed at 2, 4, 8, 16, 24 and 48 h after endotoxin injection. Aqueous humor analysis for protein concentration and cell count was performed after IVM.


RESULTS
At 2 h after the induction of uveitis, significantly more rolling leukocytes were detected in the AG and L-NAME-treated group than in untreated EIU (4.8 +/- 0.31 and 9.83 +/- 0.64 vs. 2.85 +/- 0.37%, mean +/- SEM, p < 0.01). However, at 16 h the percentage of rolling leukocytes was significantly reduced in all groups which had received AG (LPS: 8.08 +/- 0.37%; LPS/AG 0 h: 3.78 +/- 0.25%; LPS/AG 8 h: 5.34 +/- 0.3%; LPS/AG 0+8h: 3.86 +/- 0.31%). L-NAME enhanced leukocyte rolling even at 24 h after LPS (12.38 +/- 0.64%). Early treatment of EIU with AG significantly reduced the number of sticking leukocytes at 4, 8 and 24 h (306 +/- 13 vs. 571 +/- 41, 228 +/- 12 vs. 345 +/- 19 and 240 +/- 14 vs. 469 +/- 23 cells/mm2, respectively). L-NAME inhibited LPS-induced sticking of leukocytes at all observed time points and this effect was most pronounced at 24 h (147 +/- 10 vs. 469 +/- 23 cells/mm2).


CONCLUSIONS
In EIU, administration of AG or L-NAME causes enhanced leukocyte rolling in the early inflammatory response. However, firm adhesion of leukocytes to the vascular endothelium decreases and this effect prevails, ameliorating leukocyte infiltration.
Baatz
H
H
Department of Ophthalmology, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany. holger_baatz@hotmail.com
Pleyer
U
U
D000818:Animals; D001082:Aqueous Humor / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D006146:Guanidines / Q000494:pharmacology*; D007962:Leukocytes / Q000502:physiology*; D008070:Lipopolysaccharides / Q000633:toxicity; D008856:Microscopy, Fluorescence; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D009573:Nitrites / Q000097:blood; D051381:Rats; D011917:Rats, Inbred Lew; D014605:Uveitis / Q000097:blood*
D004791:Enzyme Inhibitors; D006146:Guanidines; D008070:Lipopolysaccharides; D009573:Nitrites; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; C004479:pimagedine; D019331:NG-Nitroarginine Methyl Ester