Prostaglandin E2 differentially modulates IL-5 gene expression in activated human T lymphocytes depending on the costimulatory signal.

Abstract

Protein kinase A (PKA) activation is documented to be inhibitory for T helper cell (T[H1])-like cytokines (IL-2, IFN-gamma), whereas T(H2)-like cytokines (IL-4, IL-5) are not affected or upregulated. We have recently shown that IL-4 gene expression can be inhibited by PKA activation but depends on the mode of T-cell activation. For IL-5 gene expression, we hypothesized that the mode of T-cell activation also determines the ultimate effect of simultaneous PKA activation. The objective of this study was the examination of IL-5 gene expression in healthy T cells activated with various mitogenic stimuli after simultaneous activation of PKA by dibutyryl-cAMP or prostaglandin E2 (PGE2). IL-5 mRNA was measured by semiquantitative reverse transcription-polymerase chain reaction or Northern analysis. IL-5 protein was measured by ELISA. Transcriptional mechanisms involved in IL-5 gene expression were determined by nuclear run-on experiments and electrophoretic mobility shift assays. Posttranscriptional mechanisms were determined by actinomycin D chase studies. Anti-CD2-, anti-CD3-, and anti-CD3 plus anti-CD28-induced IL-5 mRNA were completely inhibited by dibutyryl cyclic AMP (10[-3] mol/L) and PGE2 (10[-5] mol/L), whereas concanavalin A-induced IL-5 mRNA was partially reduced. The effect of PGE2 was accomplished at the transcriptional level, probably as the result of inhibition of DNA binding of nuclear factor-kappaB. Anti-CD3 plus anti-CD28-induced IL-5 protein (504 +/- 56 pg/ml) was significantly reduced by PGE2 (122 +/- 42 pg/ml, p < 0.001). Addition of cytokines that use the IL-2 receptor gamma(C) chain (IL-2, IL-7, IL-15) abrogated the PGE2-induced inhibition of IL-5 protein. In contrast, concanavalin A plus PMA-induced IL-5 protein (75 +/- 8 pg/ml) was significantly upregulated by the simultaneous addition of PGE2 (128 +/- 17 pg/ml, p < 0.03). PKA activation differentially modulates IL-5 gene expression and depends on the mode of T-cell activation.