Dexamethasone inhibition of IL-1-induced collagen degradation by corneal fibroblasts in three-dimensional culture.
OBJECTIVE
Corticosteroids regulate the functions of inflammatory cells. The purpose of the present study was to investigate the effect of dexamethasone on collagen degradation by corneal fibroblasts, an underlying cause of corneal ulceration.


METHODS
Rabbit corneal fibroblasts were cultured in three-dimensional gels of type I collagen and in the absence or presence of IL-1beta or dexamethasone. The extent of collagen degradation was determined by measurement of the amount of hydroxyproline generated by acid-heat hydrolysis of culture supernatants. The expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) was evaluated by immunoblot analysis, gelatin zymography, and reverse transcription and real-time polymerase chain reaction. The phosphorylation of mitogen-activated protein kinases (MAPKs) in corneal fibroblasts was assessed by immunoblot analysis.


RESULTS
Dexamethasone inhibited IL-1beta-induced collagen degradation by corneal fibroblasts in a dose-dependent manner. Both the synthesis and activation of MMPs and the expression of TIMPs were inhibited by dexamethasone, as was the activity of plasmin in culture supernatants. Dexamethasone also inhibited the IL-1beta-induced phosphorylation of the MAPKs extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK), but not that of p38.


CONCLUSIONS
Dexamethasone exerted multiple effects on the MMP-TIMP system in corneal fibroblasts and thereby inhibited IL-1beta-induced collagen degradation by these cells. Inhibition of the IL-1beta-induced activation of ERK and JNK may contribute to these effects of dexamethasone.
Lu
Ying
Y
Department of Biomolecular Recognition and Ophthalmology, Yamaguchi University School of Medicine, Japan.
Fukuda
Ken
K
Liu
Yang
Y
Kumagai
Naoki
N
Nishida
Teruo
T
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D003094:Collagen / Q000037:antagonists & inhibitors* / Q000378:metabolism; D003315:Cornea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D003584:Cytological Techniques; D003907:Dexamethasone / Q000494:pharmacology*; D005341:Fibrinolysin / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D020782:Matrix Metalloproteinases / Q000096:biosynthesis / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011817:Rabbits; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D007375:Interleukin-1; D019714:Tissue Inhibitor of Metalloproteinases; D003907:Dexamethasone; D003094:Collagen; D020928:Mitogen-Activated Protein Kinases; D005341:Fibrinolysin; D020782:Matrix Metalloproteinases