Release of soluble tumor necrosis factor receptor 1 from corneal epithelium by TNF-alpha-converting enzyme-dependent ectodomain shedding.
OBJECTIVE
An involvement of tumor necrosis factor-alpha-converting enzyme (TACE)-dependent ectodomain shedding in the release of soluble tumor necrosis factor receptor 1 (sTNFR1) from corneal epithelium was evaluated.


METHODS
In vitro experiments were performed using the human SV40-transformed human corneal epithelial cell (HCEC) line. Ectodomain shedding was stimulated by phorbol myristate acetate (PMA, 3 microM) or peptidoglycan (PGN, 100 microg/mL), with or without TACE inhibition, using TNF-alpha processing inhibitor-1 (TAPI-1, 250 microg/mL) or tissue inhibitor of metalloproteinase-3 (TIMP-3, 2 microg/mL) by addition to the HCEC culture medium. The concentrations of sTNFR1 in culture medium were analyzed by enzyme-linked immunosorbent assay. To induce an inflammatory response in the ocular surface, corneal alkali burn of BALB/c mice was made from a filter paper dipped in 1 N NaOH solution. TNFR1 expression in corneal and conjunctival epithelia was evaluated by immunohistochemistry 28 days after wounding.


RESULTS
In HCEC culture medium, sTNFR1 release was significantly increased by the addition of PMA (t-test, P < 0.01) or PGN (P < 0.01). The increased release of sTNFR1 was significantly inhibited by the addition of TAPI-1 or TIMP-3, indicating the possibility of TACE-dependent ectodomain shedding of TNFR1. In the corneal alkali burn model, TNFR1 was expressed in corneal and conjunctival epithelia.


CONCLUSIONS
TACE-dependent ectodomain shedding of sTNFR1 was recognized in corneal epithelium. In the inflamed ocular surface, TNFR1 was expressed in the corneal and conjunctival epithelia after alkali burn treatment. sTNFR1, released from the ocular surface, may play an anti-inflammatory role in the inflammatory condition.
Sakimoto
Tohru
T
Department of Ophthalmology, Nihon University School of Medicine, Tokyo, Japan. torusaki@gmail.com
Yamada
Ai
A
Sawa
Mitsuru
M
D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000072198:ADAM17 Protein; D000818:Animals; D002057:Burns, Chemical / Q000378:metabolism; D002461:Cell Line, Transformed; D004151:Dipeptides / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000378:metabolism; D005126:Eye Burns / Q000139:chemically induced; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010457:Peptidoglycan / Q000494:pharmacology; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism*; D012972:Sodium Hydroxide / Q000633:toxicity; D012995:Solubility; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000494:pharmacology
D004151:Dipeptides; D006877:Hydroxamic Acids; C092152:N-((2-(hydroxyaminocarbonyl)methyl)-4-methylpentanoyl)-3-(2'-naphthyl)alanylalanine, 2-aminoethylamide; D010457:Peptidoglycan; D047888:Receptors, Tumor Necrosis Factor, Type I; D019717:Tissue Inhibitor of Metalloproteinase-3; C506236:Tnfrsf1a protein, mouse; D012972:Sodium Hydroxide; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C000606463:Adam17 protein, mouse; D013755:Tetradecanoylphorbol Acetate