Synergistic induction of eotaxin expression in human keratocytes by TNF-alpha and IL-4 or IL-13.
OBJECTIVE
To investigate the effects of tumor necrosis factor (TNF)-alpha, interleukin (IL)4, and IL-13 on expression of the chemokine eotaxin by cultured human keratocytes.


METHODS
Cultured human keratocytes were incubated with various combinations and concentrations of TNF-alpha, IL-4, and IL-13. The concentration of eotaxin in the culture supernatant was subsequently measured by enzyme-linked immunosorbent assay, and the amount of eotaxin mRNA in cell lysates was determined by reverse transcription-polymerase chain reaction analysis.


RESULTS
Keratocytes incubated in the absence of cytokines did not release detectable amounts of eotaxin into the culture medium. Whereas incubation of keratocytes with TNF-alpha, IL-4, or IL-13 alone or with the combination of IL-4 and IL-13 had only a small effect on eotaxin release, exposure of the cells to TNF-alpha in combination with either IL-4 or IL-13 resulted in a marked increase in eotaxin production that was both time and dose dependent. The abundance of eotaxin mRNA in keratocytes was also increased in a synergistic manner by incubation of cells with TNF-alpha together with either IL-4 or IL-13.


CONCLUSIONS
Stimulation of human keratocytes with the combination of TNF-alpha and either IL-4 or IL-13 resulted in synergistic increases in both the abundance of eotaxin mRNA and the release of eotaxin protein. This cytokine-induced increase in eotaxin production by keratocytes may contribute to eosinophil infiltration in inflammatory ocular diseases such as vernal keratoconjunctivitis.
Kumagai
N
N
Department of Ophthalmology, Yamaguchi University School of Medicine, Japan. kgnaoki@po.cc.yamaguchi-u.ac.jp
Fukuda
K
K
Ishimura
Y
Y
Nishida
T
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D002478:Cells, Cultured; D054413:Chemokine CCL11; D019742:Chemokines, CC; D002631:Chemotactic Factors, Eosinophil / Q000096:biosynthesis / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D003315:Cornea / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004357:Drug Synergism; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D018793:Interleukin-13 / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
C515456:CCL11 protein, human; D054413:Chemokine CCL11; D019742:Chemokines, CC; D002631:Chemotactic Factors, Eosinophil; D016207:Cytokines; D004338:Drug Combinations; D018793:Interleukin-13; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4