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Novel insights in the regulation of CCL18 secretion by monocytes and dendritic cells via cytokines, toll-like receptors and rheumatoid synovial fluid.

van Lieshout AW, van der Voort R, le Blanc LM, Roelofs MF, Schreurs BW, van Riel PL, Adema GJ, Radstake TR - BMC Immunol. (2006)

Bottom Line: A high CCL18 expression was detected in RA synovial tissue and incubation of monocytes with synovial fluid from RA patients clearly enhanced the effects of IL-4, IL-13 and IL-10.Surprisingly, the effect of synovial fluid was not driven by IL-10 of IL-13, suggesting the presence of another CCL18 inducing factor in synovial fluid.The effects of IL-14, IL-13 and IL-10 are strongly enhanced by synovial fluid.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Rheumatology, Radboud University Nijmegen Medical Centre, The Netherlands. a.vanlieshout@reuma.umcn.nl

ABSTRACT

Background: The T cell attracting chemokine CCL18 is produced by antigen presenting cells and a role for CCL18 has been suggested in the pathogenesis of a variety of diseases. Rheumatoid arthritis (RA) is one of these conditions, in which abundant CCL18 production is present. Although Th2 cytokines and IL-10 are known to have an effect on CCL18 production, there are several gaps in our knowledge regarding the exact regulation of CCL18 secretion, both in general and in RA. In this study we provide new insights in the regulation of CCL18 secretion by monocytes and dendritic cells.

Results: In contrast to a large panel of pro-inflammatory stimuli (IL-1beta, TNF-alpha, IL-10, IL-13, IL-15, IL-17, IL-18, IFN-gamma), T cell mimicking molecules (RANKL, CD40L) or TLR driven maturation, the anti-inflammatory IL-10 strongly stimulated DC to secrete CCL18. On freshly isolated monocytes, CCL18 secretion was induced by IL-4 and IL-13, in strong synergy with IL-10. This synergistic effect could already be observed after only 24 hours, indicating that not only macrophages and dendritic cells, but also monocytes secrete CCL18 under these stimulatory conditions. A high CCL18 expression was detected in RA synovial tissue and incubation of monocytes with synovial fluid from RA patients clearly enhanced the effects of IL-4, IL-13 and IL-10. Surprisingly, the effect of synovial fluid was not driven by IL-10 of IL-13, suggesting the presence of another CCL18 inducing factor in synovial fluid.

Conclusion: In summary, IL-10 synergistically induces CCL18 secretion in combination with IL-4 of IL-13 on monocytes and monocyte derived cells. The effects of IL-14, IL-13 and IL-10 are strongly enhanced by synovial fluid. This synergy may contribute to the high CCL18 expression in RA.

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Similar pattern of CCL18 production by IL-4 vs. IL-13 cultured monocyte derived dendritic cells. Immature MoDC were initially cultured with either IL-4 or IL-13, in combination with GM-CSF. On day 6, these immature DC were stimulated for 48 hours with IL-10 (20 ng/ml), LPS (2 μg/ml) or both. The bars represent the mean (± SEM) CCL18 (pg/ml) production/ml of 6 individual experiments. * represents a p-value of <0,05 (Wilcoxon Signed Rank test)
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Figure 2: Similar pattern of CCL18 production by IL-4 vs. IL-13 cultured monocyte derived dendritic cells. Immature MoDC were initially cultured with either IL-4 or IL-13, in combination with GM-CSF. On day 6, these immature DC were stimulated for 48 hours with IL-10 (20 ng/ml), LPS (2 μg/ml) or both. The bars represent the mean (± SEM) CCL18 (pg/ml) production/ml of 6 individual experiments. * represents a p-value of <0,05 (Wilcoxon Signed Rank test)

Mentions: First we investigated whether several mediators that are known to be important in RA were able to enhance CCL18 production by MoDC. In line with previous studies, unstimulated immature DC (iDC) produced significant amounts of CCL18 [19]. Interestingly, incubation with TNF-α, IL-1β, IL-13, IL-15, IL-17, IL-18 and IFN-γ did not stimulate CCL18 secretion when added to day 6 iDC (n = 6). In contrast, the anti-inflammatory IL-10 strongly induced CCL18 production by iDC (p = 0.03) (figure 1a). Next we tested whether factors well known to induce maturation or T cell mimicking could induce CCL18 production. These experiments demonstrated that LPS, CD40L and RANKL did not enhance CCL18 production (n = 3) (figure 1b). Recent studies demonstrated that other TLR pathways than TLR4 are all capable of inducing DC maturation, but have different effects on cytokine production [29-31]. However, stimulation of TLR2 (pam3cys), TLR3 (poly (i:c)), TLR4 (LPS) or TLR7/8 (R848) did not sort any effect on CCL18 secretion (n = 6) (figure 1c), whereas they did elicit a potent cytokine response [31]. Since IL-13 is more abundantly present in RA than IL-4 and since some conflicting results have been published on CCL18 production induced by LPS when DC were cultured with IL-13 vs. IL-4, we compared these culture methods (n = 6). In both the IL-4 and IL-13 cultures, IL-10 strongly induced CCL18 (p = 0.03 for both IL-4 and IL-13 culture), while LPS again did not (figure 2). In addition, IL-10 in combination with LPS was not significantly different from IL-10 alone (figure 2). Also co-stimulation with LPS and the cytokines tested (as in figure 1) did not sort any effect on CCL18 secretion (data not shown).


Novel insights in the regulation of CCL18 secretion by monocytes and dendritic cells via cytokines, toll-like receptors and rheumatoid synovial fluid.

van Lieshout AW, van der Voort R, le Blanc LM, Roelofs MF, Schreurs BW, van Riel PL, Adema GJ, Radstake TR - BMC Immunol. (2006)

Similar pattern of CCL18 production by IL-4 vs. IL-13 cultured monocyte derived dendritic cells. Immature MoDC were initially cultured with either IL-4 or IL-13, in combination with GM-CSF. On day 6, these immature DC were stimulated for 48 hours with IL-10 (20 ng/ml), LPS (2 μg/ml) or both. The bars represent the mean (± SEM) CCL18 (pg/ml) production/ml of 6 individual experiments. * represents a p-value of <0,05 (Wilcoxon Signed Rank test)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1590050&req=5

Figure 2: Similar pattern of CCL18 production by IL-4 vs. IL-13 cultured monocyte derived dendritic cells. Immature MoDC were initially cultured with either IL-4 or IL-13, in combination with GM-CSF. On day 6, these immature DC were stimulated for 48 hours with IL-10 (20 ng/ml), LPS (2 μg/ml) or both. The bars represent the mean (± SEM) CCL18 (pg/ml) production/ml of 6 individual experiments. * represents a p-value of <0,05 (Wilcoxon Signed Rank test)
Mentions: First we investigated whether several mediators that are known to be important in RA were able to enhance CCL18 production by MoDC. In line with previous studies, unstimulated immature DC (iDC) produced significant amounts of CCL18 [19]. Interestingly, incubation with TNF-α, IL-1β, IL-13, IL-15, IL-17, IL-18 and IFN-γ did not stimulate CCL18 secretion when added to day 6 iDC (n = 6). In contrast, the anti-inflammatory IL-10 strongly induced CCL18 production by iDC (p = 0.03) (figure 1a). Next we tested whether factors well known to induce maturation or T cell mimicking could induce CCL18 production. These experiments demonstrated that LPS, CD40L and RANKL did not enhance CCL18 production (n = 3) (figure 1b). Recent studies demonstrated that other TLR pathways than TLR4 are all capable of inducing DC maturation, but have different effects on cytokine production [29-31]. However, stimulation of TLR2 (pam3cys), TLR3 (poly (i:c)), TLR4 (LPS) or TLR7/8 (R848) did not sort any effect on CCL18 secretion (n = 6) (figure 1c), whereas they did elicit a potent cytokine response [31]. Since IL-13 is more abundantly present in RA than IL-4 and since some conflicting results have been published on CCL18 production induced by LPS when DC were cultured with IL-13 vs. IL-4, we compared these culture methods (n = 6). In both the IL-4 and IL-13 cultures, IL-10 strongly induced CCL18 (p = 0.03 for both IL-4 and IL-13 culture), while LPS again did not (figure 2). In addition, IL-10 in combination with LPS was not significantly different from IL-10 alone (figure 2). Also co-stimulation with LPS and the cytokines tested (as in figure 1) did not sort any effect on CCL18 secretion (data not shown).

Bottom Line: A high CCL18 expression was detected in RA synovial tissue and incubation of monocytes with synovial fluid from RA patients clearly enhanced the effects of IL-4, IL-13 and IL-10.Surprisingly, the effect of synovial fluid was not driven by IL-10 of IL-13, suggesting the presence of another CCL18 inducing factor in synovial fluid.The effects of IL-14, IL-13 and IL-10 are strongly enhanced by synovial fluid.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Rheumatology, Radboud University Nijmegen Medical Centre, The Netherlands. a.vanlieshout@reuma.umcn.nl

ABSTRACT

Background: The T cell attracting chemokine CCL18 is produced by antigen presenting cells and a role for CCL18 has been suggested in the pathogenesis of a variety of diseases. Rheumatoid arthritis (RA) is one of these conditions, in which abundant CCL18 production is present. Although Th2 cytokines and IL-10 are known to have an effect on CCL18 production, there are several gaps in our knowledge regarding the exact regulation of CCL18 secretion, both in general and in RA. In this study we provide new insights in the regulation of CCL18 secretion by monocytes and dendritic cells.

Results: In contrast to a large panel of pro-inflammatory stimuli (IL-1beta, TNF-alpha, IL-10, IL-13, IL-15, IL-17, IL-18, IFN-gamma), T cell mimicking molecules (RANKL, CD40L) or TLR driven maturation, the anti-inflammatory IL-10 strongly stimulated DC to secrete CCL18. On freshly isolated monocytes, CCL18 secretion was induced by IL-4 and IL-13, in strong synergy with IL-10. This synergistic effect could already be observed after only 24 hours, indicating that not only macrophages and dendritic cells, but also monocytes secrete CCL18 under these stimulatory conditions. A high CCL18 expression was detected in RA synovial tissue and incubation of monocytes with synovial fluid from RA patients clearly enhanced the effects of IL-4, IL-13 and IL-10. Surprisingly, the effect of synovial fluid was not driven by IL-10 of IL-13, suggesting the presence of another CCL18 inducing factor in synovial fluid.

Conclusion: In summary, IL-10 synergistically induces CCL18 secretion in combination with IL-4 of IL-13 on monocytes and monocyte derived cells. The effects of IL-14, IL-13 and IL-10 are strongly enhanced by synovial fluid. This synergy may contribute to the high CCL18 expression in RA.

Show MeSH
Related in: MedlinePlus