Microarray analysis of cytokine and chemokine gene expression after prednisolone treatment in murine experimental...

The purpose of this study was to investigate changes in gene expression of cytokines and chemokines and their receptors after systemic prednisolone treatment in experimental autoimmune uveoretinitis (EAU).

EAU mice received one intravenous injection of 7.5 mg/kg prednisolone (PDS) sodium phosphate at the peak of inflammation. EAU mice treated with only solvent served as the control. Total RNA was extracted from the whole eyes 1, 2, and 3 days after treatment. Gene expression analysis was conducted with a cDNA microarray, which contains 117 individual transcripts encoding the genes of the cytokines and chemokines and their receptors (29 cytokines and 34 cytokine receptors; 33 chemokines and 21 chemokine receptors). Comparisons of expression between PDS-treated and placebo-treated EAU mice at each time point were performed. The genes were sorted into clusters based on expression profiles, to clarify the gene regulation pattern after treatment.

Forty-seven genes had a significant decrease in expression 1 day after treatment, 10 genes on day 2, and 46 genes on day 3. Ten genes were upregulated on day 1, but no gene was upregulated thereafter. Hierarchical cluster analysis of the microarray demonstrated that gene expression changes in EAU after treatment with PDS showed four patterns: flat, mountain, steep downhill, and less steep downhill.

The implications of the clusters after treatment with PDS remain unclear. The results showed that hierarchical cluster analysis based on comprehensive gene expression profiles may provide a powerful tool for identifying genes not previously associated with the therapeutic targets in ocular inflammation.