Ectosomes from neutrophil-like cells down-regulate nickel-induced dendritic cell maturation and promote Th2 polarization

Abstract

DCs are the first immune cells to be exposed to allergens, including chemical sensitizers, such as nickel, a human TLR4 agonist that induces DC maturation. In ACD, DCs can interact with PMNs that are recruited and activated, leading, in particular, to ectosome release. The objective of this work was to characterize the effects of PMN-Ect on DC functions in an ACD context. We first developed a standardized protocol to produce, characterize, and quantify ectosomes by use of human PLB-985 cells, differentiated into mature PMN (PLB-Ect). We then studied the in vitro effects of these purified ectosomes on human moDC functions in response to NiSO4 and to LPS, another TLR4 agonist. Confocal fluorescence microscopy showed that PLB-Ect was internalized by moDCs and localized in the lysosomal compartment. We then showed that PLB-Ect down-regulated NiSO4-induced moDC maturation, as witnessed by decreased expression of CD40, CD80, CD83, CD86, PDL-1, and HLA-DR and by decreased levels of IL-1β, IL-6, TNF-α, and IL-12p40 mRNAs. These effects were related to p38MAPK and NF-κB down-regulation. However, no increase in pan-regulatory DC marker genes (GILZ, CATC, C1QA) was observed; rather, levels of effector DC markers (Mx1, NMES1) were increased. Finally, when these PLB-Ect + NiSO4-treated moDCs were cocultured with CD4(+) T cells, a Th2 cytokine profile seemed to be induced, as shown, in particular, by enhanced IL-13 production. Together, these results suggest that the PMN-Ect can modulate DC maturation in response to nickel, a common chemical sensitizer responsible for ADC.

Nickel Sulfate Promotes IL-17A Producing CD4+ T Cells by an IL-23-Dependent Mechanism Regulated by TLR4 and Jak-STAT Pathways

“…Our results suggested that the production of these cytokines was dependent on the TLR4 pathway. Moreover, we have previously shown that NiSO 4 can activate MAPK and NF-kB pathways in human DCs (Antonios et al, 2009;Turbica et al, 2015). Here we showed that IL-23/IL-12 production in NiSO 4 -activated MoDCs was also dependent on p38MAPK and NF-kB pathways at both the protein and the transcriptional levels.…”

Nrf2 downregulates zymosan-induced neutrophil activation and modulates migration

“…Several studies have led to the consensus that PMNs are able to finely regulate both innate and adaptive immune responses, engaging with T lymphocytes or antigen-presenting cells, releasing anti-inflammatory mediators or expressing regulatory receptors; this broader role in immunity also led to the definition of several functional PMN subpopulations [4,39–41]. In particular, our group evidenced that isolated NETs or neutrophil-derived ectosomes were able to downregulate LPS-induced DC maturation and their capacity to induce T lymphocyte proliferation [7,42]. We also evidenced that GILZ, a potent anti-inflammatory mediator implicated in cell survival, was present in human neutrophils, promoted apoptosis via Mcl-1 downregulation, and was upregulated in patients with the acute respiratory distress syndrome in relation to severity [11,43].…”

Human blood monocytes are able to form extracellular traps

“…Protein preparation, separation, and transfer to a polyvinylidene difluoride membrane were done, as described previously [19], before probing overnight with anti-H3cit antibody (1:100, ab5103; Abcam, Cambridge, MA, USA). Proteins were visualized on a chemiluminescence membrane reader (Chem-iDoc; Bio-Rad Laboratories) with Image Lab software (Bio-Rad Laboratories).…”