Ethyl pyruvate ameliorates endotoxin-induced corneal inflammation.
OBJECTIVE
The purpose of this study was to evaluate the anti-inflammatory effect of ethyl pyruvate (EP) in a mouse model of lipopolysaccharide (LPS)-induced corneal inflammation.


METHODS
LPS was injected intrastromally into the corneas of C57BL/6 mice followed by treatment with a solution of 2.5% EP in 0.2% hydroxypropyl methylcellulose (HPMC) every 90 minutes during the course of 12 hours. Prednisolone acetate 1% solution (PRED FORTE) was used as a positive control. Mice were sacrificed after 3 days, and corneas were examined by in vivo confocal microscopy and analyzed for infiltrated cells by flow cytometry. Gr-1, TNF-α, and pNF-κB-p65 were detected immunohistochemically, and TNF-α, IL-6, and IL-1β levels were quantified by ELISA.


RESULTS
LPS-induced haze in mice corneas was decreased by 2-fold upon EP treatment; however, it was not changed upon PRED FORTE treatment. Flow cytometry and immunohistochemistry showed infiltration of leukocytes in the LPS-treated corneas; among the infiltrated cells, neutrophils (Gr-1+ and CD11b+) and macrophages (F4/80+ and CD11b+) were 3403.4- and 4.5-fold higher in number, respectively, than in vehicle-treated control corneas. EP or PRED FORTE treatment of LPS-injected corneas decreased the number of neutrophils 7.5- and 7.2-fold and macrophages by 5.6- and 3.5-fold, respectively. Both EP and PRED FORTE decreased TNF-α and IL-6 expression considerably, and to a lesser extent IL-1β expression, in the LPS-treated corneas.


CONCLUSIONS
The present study demonstrated that EP reduces LPS-induced inflammation in the cornea and thus may have a potential therapeutic application in the inhibition of corneal inflammation.
Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA.
Divya
D
Gupta
Yiqin
Y
Du
Jordan
J
Piluek
Adam M
AM
Jakub
Kristine Ann
KA
Buela
Akshar
A
Abbott
Joel S
JS
Schuman
Nirmala
N
SundarRaj
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D054441:Cell Migration Assays, Leukocyte; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D007634:Keratitis / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D007962:Leukocytes / Q000502:physiology; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D009883:Ophthalmic Solutions / Q000627:therapeutic use; D011773:Pyruvates / Q000627:therapeutic use*; D019707:Receptors, Chemokine / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000893:Anti-Inflammatory Agents; C503133:Gr-1 protein, mouse; D008070:Lipopolysaccharides; D009883:Ophthalmic Solutions; D011773:Pyruvates; D019707:Receptors, Chemokine; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; C046522:ethyl pyruvate