Synergistic effect of TNF-alpha and either IL-4 or IL-13 on VCAM-1 expression by cultured human corneal fibroblasts.
OBJECTIVE
To examine the role of corneal fibroblasts in the pathogenesis of vernal keratoconjunctivitis, we investigated the effects of tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, and IL-13 on the expression of vascular cell adhesion molecule (VCAM)-1 by cultured human corneal fibroblasts.


METHODS
Cultured human corneal fibroblasts were incubated with various combinations and concentrations of TNF-alpha, IL-4, and IL-13. The cell surface expression of VCAM-1 was subsequently evaluated by whole-cell enzyme-linked immunosorbent assay and immunocytochemistry, and the abundance of VCAM-1 mRNA in cell lysates was determined by quantitative reverse transcription and polymerase chain reaction analysis.


RESULTS
Corneal fibroblasts incubated in the absence of cytokines exhibited minimal expression of VCAM-1. Whereas incubation of the cells with TNF-alpha, IL-4, or IL-13 alone, or with the combination of IL-4 and IL-13, induced only a small increase in VCAM-1 expression, exposure of the cells to TNF-alpha in combination with either IL-4 or IL-13 resulted in a marked synergistic increase in expression of this adhesion molecule that was both time and dose dependent. The abundance of VCAM-1 mRNA in corneal fibroblasts was also increased in a synergistic manner by incubation of the cells with TNF-alpha together with either IL-4 or IL-13.


CONCLUSIONS
Stimulation of human corneal fibroblasts with the combination of TNF-alpha and either IL-4 or IL-13 resulted in synergistic increases in both the abundance of VCAM-1 mRNA and the cell surface expression of VCAM-1 protein. This cytokine-induced increase in VCAM-1 expression by corneal fibroblasts may contribute to eosinophil infiltration in corneal lesions associated with vernal keratoconjunctivitis.
Kumagai
Naoki
N
Department of Biomolecular Recognition and Ophthalmology, Yamaguchi University School of Medicine, 1-1-1 Minami-Kogushi, Ube City, Yamaguchi 755-8505, Japan. kgnaoki@yamaguchi-u.ac.jp
Fukuda
Ken
K
Fujitsu
Youichiro
Y
Nishida
Teruo
T
D002478:Cells, Cultured; D003315:Cornea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D018793:Interleukin-13 / Q000008:administration & dosage / Q000494:pharmacology*; D015847:Interleukin-4 / Q000008:administration & dosage / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000494:pharmacology*; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*
D018793:Interleukin-13; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D015847:Interleukin-4