The PI3 kinase, p38 SAP kinase, and NF-kappaB signal transduction pathways are involved in the survival and maturation of lipopolysaccharide-stimulated human monocyte-derived dendritic cells.
As a dendritic cell (DC) matures, it becomes more potent as an antigen-presenting cell. This functional change is accompanied by a change in DC immunophenotype. The signal transduction events underlying this process are poorly characterized. In this study, we have investigated the signal transduction pathways involved in the lipopolysaccharide (LPS)-induced maturation of human monocyte-derived DCs (MoDCs) in vitro. We show that exposure of immature MoDCs to LPS activates the p38 stress-activated protein kinase (p38SAPK), extracellular signal-regulated protein kinase (ERK), phosphoinositide 3-OH kinase (PI3 kinase)/Akt, and nuclear factor (NF)-kappaB pathways. Studies using inhibitors demonstrate that PI3 kinase/Akt but not the other pathways are important in maintaining survival of LPS-stimulated MoDCs. Inhibiting p38SAPK prevented activation of the transcription factors ATF-2 and CREB and significantly reduced the LPS-induced up-regulation of CD80, CD83, and CD86, but did not have any significant effect on the LPS-induced changes in macropinocytosis or HLA-DR, CD40, and CD1a expression. Inhibiting the NF-kappaB pathway significantly reduced the LPS-induced up-regulation of HLA-DR as well as CD80, CD83, and CD86. Inhibiting the p38SAPK and NF-kappaB pathways simultaneously had variable effects depending on the cell surface marker studied. It thus appears that different aspects of LPS-induced MoDC maturation are regulated by different and sometimes overlapping pathways.
Ardeshna
K M
KM
Department of Haematology, Royal Free and University College Medical School, London, United Kingdom. k.ardeshna@ucl.ac.uk
Pizzey
A R
AR
Devereux
S
S
Khwaja
A
A
D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects; D016328:NF-kappa B / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases
D008070:Lipopolysaccharides; D016328:NF-kappa B; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases