Borger P, Vellenga E, Gringhuis S I, Timmerman J A, Lummen C, Postma D S, Kauffman H F
Department of Internal Medicine, University of Groningen, The Netherlands.
J Allergy Clin Immunol. 1998 Feb;101(2 Pt 1):231-40. doi: 10.1016/s0091-6749(98)70388-4.
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.
已有文献证明蛋白激酶A（PKA）激活对辅助性T细胞（Th1）样细胞因子（白细胞介素-2、干扰素-γ）具有抑制作用，而Th2样细胞因子（白细胞介素-4、白细胞介素-5）不受影响或上调。我们最近发现白细胞介素-4基因表达可被PKA激活抑制，但这取决于T细胞激活方式。对于白细胞介素-5基因表达，我们推测T细胞激活方式也决定了同时激活PKA的最终效果。
本研究的目的是检测在用二丁酰环磷腺苷（dbcAMP）或前列腺素E2（PGE2）同时激活PKA后，经各种促有丝分裂刺激激活的健康T细胞中白细胞介素-5基因的表达情况。
采用半定量逆转录聚合酶链反应或Northern印迹分析检测白细胞介素-5 mRNA。用酶联免疫吸附测定法检测白细胞介素-5蛋白。通过核转录实验和电泳迁移率变动分析确定参与白细胞介素-5基因表达的转录机制。通过放线菌素D追踪研究确定转录后机制。
二丁酰环磷腺苷（10[-3]mol/L）和PGE2（10[-5]mol/L）可完全抑制抗CD2、抗CD3以及抗CD3加抗CD28诱导的白细胞介素-5 mRNA表达，而伴刀豆球蛋白A诱导的白细胞介素-5 mRNA表达仅部分降低。PGE2的作用是在转录水平实现的，可能是抑制核因子κB与DNA结合的结果。PGE2可显著降低抗CD3加抗CD28诱导的白细胞介素-5蛋白（504±56 pg/ml）水平（122±42 pg/ml，p<0.001）。添加使用白细胞介素-2受体γ链（白细胞介素-2、白细胞介素-7、白细胞介素-15）的细胞因子可消除PGE2诱导的白细胞介素-5蛋白抑制作用。相反，伴刀豆球蛋白A加佛波酯诱导的白细胞介素-5蛋白（75±8 pg/ml）在同时添加PGE2后显著上调（128±17 pg/ml，p<0.03）。
PKA激活对白细胞介素-5基因表达具有不同的调节作用，且取决于T细胞激活方式。
