Extracellular signal–regulated protein kinase signaling pathway negatively regulates the phenotypic and functional maturation of monocyte-derived human dendritic cells (original) (raw)
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Journal of leukocyte biology, 2002
Functional roles of extracellular signal-related kinase (ERK) activation in dendritic-cell (DC) maturation have been unclear. In the present study, we investigated the ERK pathway in tumor necrosis factor (TNF)-alpha-induced maturation of murine spleen-derived DC. TNF-alpha increased surface expressions of major histocompatibility (MHC) and costimulatory molecules on DC in a dose-dependent manner. High (40 ng/ml) and low (0.4 ng/ml) concentrations of TNF-alpha markedly enhanced ERK1/2 activation in DC, and this activation was blocked completely by PD98059, a selective inhibitor of the ERK pathway. When DC were treated with TNF-alpha at a low but not a high concentration, PD98059 notably enhanced surface expressions of the MHC and costimulatory molecules and allostimulatory capability of the DC. Interleukin (IL)-12 production was enhanced significantly by PD98059 in DC treated with low or high concentration of TNF-alpha. These findings suggest that TNF-alpha-induced ERK activation ne...
Molecular Immunology, 2009
Dendritic cells (DC) are professional antigen-presenting cells with a unique capacity to initiate and modulate immune responses by their ability to prime naïve T-cells. Upon stimuli, DC experience several morphologic, phenotypic and functional changes in a process referred to as maturation. This process is crucial to the biological functions of DC since their maturation status confer them the ability to polarize distinct T-cell subsets. In this work we explored the relevance of PI3-Kinase, Mitogen-Activated Protein Kinases (MAPKs) and NF-kappaB on cytokines/chemokines and co-stimulatory molecules expression. As experimental model, we used a fetal skin-derived dendritic cell line (FSDC) induced to mature by treatment with lipopolysaccharide (LPS). Morphology and ultrastructure were analyzed by confocal and electron microscopies, respectively. Levels of phosphorylated proteins were evaluated by Western blot, production of cytokines/chemokines was analyzed by protein arrays and the expression of surface molecules was evaluated by flow cytometry. The effect of specific inhibitors of the studied signaling pathways on the transcription of cytokines/chemokines and co-stimulatory molecules was accessed by Quantitative Real-Time RT-PCR. The results showed that LPS induces significant morphological and ultrastructural changes in FSDC. Western blot analysis revealed that LPS challenge promotes an early and transient activation of NF-B, ERK1/2, p38 MAPK, along with a more sustained PI3 kinase/AKT activation. The co-stimulatory CD40, CD80, CD86 and antigen-presenting MHC class I and II molecules were increased and among secreted molecules, interleukin IL-6, CCL5, G-CSF, CCL2, CXCL2 were strongly up-regulated. Using a pharmacological approach we observed that LPS-induced increase of these molecules was differentially regulated by the distinct signaling pathways. Moreover, the polarizing T h 2 cytokines/chemokines induced by LPS in FSDC were found to be positively regulated by NF-B and ERK and negatively modulated by p38 MAPK. Altogether these results suggest that the use of pharmacological inhibitors to manipulate DC maturation, namely the polarizing T h 1/T h 2 cytokine/chemokine profile, may be useful in the development of more specific immunotherapeutic protocols.
Journal of immunology (Baltimore, Md. : 1950), 1999
We investigated whether human monocyte-derived dendritic cells (DCs) differed from tonsillar B cells in the set of cell fate genes they express constitutively and in the way these genes are affected after CD40 ligation. In particular, Bcl-2, TNF receptor-associated factor-2 (TRAF2), and TRAF4 were clearly inducible via CD40 in B cells but not in DCs. DCs, unlike B cells, were induced to increase expression of IL-1beta, IL-1Ra, IL-8, IL-12 p40, RANTES, macrophage inflammatory protein-1alpha, and monocyte chemoattractant protein-1 after CD40 ligation. We next tested whether CD40-induced signaling pathways were different in DCs vs B cells. In DCs, as in B cells, CD40 ligation activated p38 mitogen-activated protein kinase (MAPK), its downstream target, MAPKAPK-2, and the c-Jun N-terminal kinase. The p38 MAPK-specific inhibitor, SB203580, blocked CD40-induced MAPKAPK-2 activation, but did not affect activation of c-Jun N-terminal kinase. Furthermore, unlike in B cells, extracellular sig...
European Journal of Immunology, 2004
Dendritic cell (DC) maturation is characterized by the gain or loss of immunological functions and by expression of distinctive surface receptors. CD38 is an ectoenzyme that catalyzes the synthesis of cyclic ADP ribose (a potent second messenger for Ca 2+ release), as well as a receptor that initiates transmembrane signaling upon engagement with its counterreceptor CD31 or with agonistic monoclonal antibodies. Since CD38 is expressed by resting monocytes, we aimed to monitor CD38 expression during the differentiation of human monocyte-derived DC (MDDC) and to investigate the possibility that CD38 plays a functional role during DC maturation. CD38 is down-modulated during differentiation into immature MDDC and expressed again upon maturation. The extent of CD38 expression is dependent on the stimulus adopted (LPS G IFN-+ G CD40 cross-linking). Although weak, IFN-+ consistently induces DC maturation. De novo-synthesized CD38 is enzymatically active, and its expression in mature (m) MDDC is dependent on NF-‹ B activity. However, CD38 is not merely a maturation marker but also mediates signaling in mMDDC, where it maintains its functions as a receptor. Activation via agonistic anti-CD38 mAb induces up-regulation of CD83 expression and IL-12 secretion, whereas disruption of CD38/CD31 interaction inhibits CD83 expression, IL-12 secretion and MDDC-induced allogeneic T cell proliferation. Abbreviations: MDDC: Monocyte-derived DC i: Immature m: Mature h: Human MFI: Median fluorescence intensity NAC N-Acetyl-l-cysteine sCD38: Soluble hrCD38 NGD + : Nicotinamide guanine dinucleotide GDP: Guanosine diphosphate MR: Mannose receptor 1342 G. Fedele et al.
International Journal of Immunopathology and Pharmacology, 2010
To better understand the molecular mechanisms underlying the dendritic cell (DC) defects in cancer, we analyzed which signaling pathway is implicated in the abnormal monocyte differentiation into DC determined by the presence of Primary effusion lymphoma (PEL) released factors. Our results indicate that the DC, obtained in this condition, together with phenotypic abnormalities and reduced allostimulatory function, showed hyperphosphorylation of signal transducer and activator of transcription 3 (STAT3) and p38 mitogen-activated protein kinase (MAPK) molecules, in comparison to the DC differentiated in the absence of PEL-released factors. The inhibition of p38 MAPK but not of STAT3 phosphorylation, with specific inhibitors, was able to revert the effect of the PEL-released factors on the DC phenotype. This study suggests that p38 MAPK signaling pathway is an important contributor to the abnormal differentiation of DC in PEL.
Maturation by Hybrid-Type Control of TNF-Induced Dendritic Cell
2011
The activity of a-1,2-mannosidase I is required for the conversion of high-mannose to hybrid-type (ConA reactive) and complextype N-glycans (Phaseolus vulgaris-leukoagglutinin [PHA-L] reactive) during posttranslational protein N-glycosylation. We recently demonstrated that a-1,2-mannosidase I mRNA decreases in graft-infiltrating CD11c + dendritic cells (DCs) prior to allograft rejection. Although highly expressed in immature DCs, little is known about its role in DC functions. In this study, analysis of surface complex-type N-glycan expression by lectin staining revealed the existence of PHA-L low and PHA-L high subpopulations in murine splenic conventional DCs, as well as in bone marrow-derived DC (BMDCs), whereas plasmacytoid DCs are nearly exclusively PHA-L high. Interestingly, all PHA-L high DCs displayed a strongly reduced responsiveness to TNF-a-induced p38-MAPK activation compared with PHA-L low DCs, indicating differences in PHA-L-binding capacities between DCs with different inflammatory properties. However, p38 phosphorylation levels were increased in BMDCs overexpressing a-1,2-mannosidase I mRNA. Moreover, hybrid-type, but not complex-type, N-glycans are required for TNF-a-induced p38-MAPK activation and subsequent phenotypic maturation of BMDCs (MHC-II, CD86, CCR7 upregulation). a-1,2-mannosidase I inhibitor-treated DCs displayed diminished transendothelial migration in response to CCL19, homing to regional lymph nodes, and priming of IFN-gproducing T cells in vivo. In contrast, the activity of a-1,2-mannosidase I is dispensable for LPS-induced signaling, as well as the DCs' general capability for phenotypic and functional maturation. Systemic application of an a-1,2-mannosidase I inhibitor was able to significantly prolong allograft survival in a murine high-responder corneal transplantation model, further highlighting the importance of N-glycan processing by a-1,2-mannosidase I for alloantigen presentation and T cell priming.
Mitogen-Activated Protein Kinase Pathway Activation by the CD6 Lymphocyte Surface Receptor
The Journal of Immunology, 2006
CD6 is a cell surface receptor primarily expressed on immature thymocytes and mature T and B1a lymphocytes. Through its binding to activated leukocyte cell adhesion molecule (ALCAM/CD166), CD6 is considered to play an important role in lymphocyte development and activation. Accordingly, CD6 associates with the TCR/CD3 complex and colocalizes with it at the center of the mature immunological synapse on T lymphocytes. Moreover, the CD6-ALCAM interaction has been shown to be critical for proper immunological synapse maturation and T cell proliferative responses. However, the precise biological effects of CD6 ligation and its signaling pathway are still not well understood. The present study shows that CD6 ligation with three different specific mAbs (161.8, SPV-L14.2, and MAE1-C10) induces time-and dose-dependent activation of ERK1/2 on normal and leukemic human T cells. This effect was also observed upon CD6 ligation with a chimerical ALCAM protein (ALCAM-Fc). The C-terminal cytoplasmic region of CD6, as well as Src tyrosine kinases, was critical for CD6-induced ERK1/2 activation. Synergistic effects were observed upon coligation of the TCR/CD3 complex with CD6. The ligation of CD6 induced the transcriptional activation of reporter genes under the control of the c-Fos serum responsive element and AP-1. Accordingly, CD6-mediated activation of p38 and JNK was also observed. These findings indicate that the CD6-ALCAM interaction results in activation of the three MAPK cascades, likely influencing the dynamic balance that determines whether resting or activated lymphocytes survive or undergo apoptosis.