Proinflammatory chemokine induction in keratocytes and inflammatory cell infiltration into the cornea.
OBJECTIVE
To determine the effect of interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha on cytokine, chemokine, and receptor expression in corneal stromal cells; the effect of corneal scrape injury on monocyte chemotactic and activating factor (MCAF) expression and monocyte-macrophage influx into the stroma; and the effect of MCAF and granulocyte colony-stimulating factor (G-CSF) microinjection on inflammatory cell infiltration into the stroma.


METHODS
Gene array technology was used to evaluate changes in cytokine, chemokine, and receptor gene expression in stromal fibroblasts in response to IL-1alpha and TNFalpha. Expression of MCAF mRNA and protein was monitored with an RNase protection assay and Western blot analysis, respectively. Keratocyte MCAF protein expression in the rabbit cornea was detected with immunocytochemistry. After epithelial scrape injury, monocytes-macrophages were detected in rabbit corneas, by immunocytochemistry for monocyte-macrophage antigen. Inflammatory cell infiltration after MCAF and G-CSF microinjection into the stroma of mouse corneas was monitored with hematoxylin and eosin staining.


RESULTS
IL-1alpha or TNFalpha upregulated the expression of several proinflammatory chemokines in stromal fibroblasts in culture. These included G-CSF, MCAF, neutrophil-activating peptide (ENA-78), and monocyte-derived neutrophil chemotactic factor (MDNCF). MCAF mRNA upregulation was confirmed by RNase protection assay, and MCAF protein was detected by Western blot analysis. MCAF protein was detected in keratocytes at 4 hours and 24 hours after epithelial injury, but not in keratocytes in the unwounded cornea. Corneal epithelial injury triggered the influx of monocytes-macrophages into the corneal stroma in the rabbit. Microinjection of MCAF and G-CSF into mouse cornea resulted in the influx of monocytes-macrophages and granulocytes, respectively, into the stroma.


CONCLUSIONS
Proinflammatory chemokine induction in keratocytes is mediated by IL-1alpha and TNFalpha. The proinflammatory chemokines produced by the keratocytes probably trigger the influx of inflammatory cells into the stroma after epithelial injury associated with corneal surgery, contact lenses, or trauma.
Hong
J W
JW
Department of Ophthalmology, University of Washington School of Medicine, Seattle 98195-6485, USA.
Liu
J J
JJ
Lee
J S
JS
Mohan
R R
RR
Mohan
R R
RR
Woods
D J
DJ
He
Y G
YG
Wilson
S E
SE
D015153:Blotting, Western; D002465:Cell Movement / Q000502:physiology*; D018932:Chemokine CCL2 / Q000494:pharmacology; D018925:Chemokines / Q000096:biosynthesis* / Q000235:genetics; D003319:Corneal Stroma / Q000187:drug effects* / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D020869:Gene Expression Profiling; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D008264:Macrophages / Q000502:physiology*; D009000:Monocytes / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000096:biosynthesis; D054390:Receptors, CCR2; D019707:Receptors, Chemokine / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
D018932:Chemokine CCL2; D018925:Chemokines; D007375:Interleukin-1; D012333:RNA, Messenger; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; D014409:Tumor Necrosis Factor-alpha; D016179:Granulocyte Colony-Stimulating Factor