Role of mitogen-activated protein kinase and PI3K pathways in the regulation of IL-12-family cytokines in dendritic cells and the generation of T H-responses.
Mitogen-activated protein kinases (MAPK) are targets for the immune-modulation of dendritic cells (DC). However, our knowledge of their role in the regulation of IL-12-family cytokines is limited. This study investigated the roles of p38, JNK, p44/42 and PI3K pathways in IL-12/23/27 production by human DC, and their impact on naïve T(H)-responses. We first identified TOP and UBC as robust DC housekeeping genes. Peak transcription of p35 and p40 occurred by 12h, p19 and p28 by 8h and EBI3 by 12-24h. Using selective antagonists, we showed that p38 was a positive regulator of IL-12, 23 and 27, JNK positively regulated IL-12 and IL-27, and inhibition of MEK1/2 had no marked effect. In contrast, the PI3K pathway markedly attenuated IL-23 responses and, to a lesser extent, IL-12, but not IL-27. To identify the role of these soluble factors, we co-stimulated naïve CD4+ T-cells in the presence of DC supernatant. The presence of mature DC supernatant induced not only strong IFNγ responses, but also IL-10 and IL-17A. Inhibition of p38 ablated T(H1), and IL-10 and IL-17A responses, whilst modestly enhancing IL-5 secretion. In contrast, inhibition of MEK1/2 abolished IL-17A production, whilst leaving other responses unaffected, whereas inhibition of JNK or PI3K had no discernable effect. In summary, we describe the expression of IL-12-family cytokines from DC and propose a modified model for their regulation. This study further clarifies the potential for therapeutic modulation through these mediators.
Academic Unit of Clinical Oncology, Respitatory Medicine, University of Nottingham, City Hospital, Hucknall Road, Nottingham, UK. andrew.jackson@nottingham.ac.uk
Andrew M
AM
Jackson
Lori A
LA
Mulcahy
Joanne
J
Porte
Hester A
HA
Franks
Mohamed
M
El Refaee
Qunwei
Q
Wang
Suharsh
S
Shah
Xingwu
X
Zhu
Poulam M
PM
Patel
D002478:Cells, Cultured; D003713:Dendritic Cells / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018664:Interleukin-12 / Q000235:genetics / Q000378:metabolism*; D053759:Interleukin-23 / Q000235:genetics / Q000378:metabolism; D007378:Interleukins / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*
D018664:Interleukin-12; D053759:Interleukin-23; D007378:Interleukins; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D047428:Protein Kinase Inhibitors; C464565:MYDGF protein, human