The mechanisms of up-regulation of dendritic cell activity by oxidative stress

Abstract

Whereas DC have increasingly been recognized for their role in activating the inflammatory cascades during IRIs, the mechanisms by which oxidative stress enhances DC activation remain to be explored. We examined the role of oxidative stress on two important features of DC: T cell activation and trafficking. Bone marrow-derived OS-DC were compared with untreated DC. DC exposed to oxidative stress augmented allogeneic T cell proliferation and showed increased migration in a chemotaxis chamber. These results were confirmed by using hypoxanthine and xanthine oxidase as another inducer of oxidative stress. We used OT-II and OT-I mice to assess the effect of oxidative stress on DC activation of OVA-specific CD4(+) and CD8(+) T cells, respectively. Oxidative stress increased DC capacity to promote OVA-specific CD4(+) T cell activity, demonstrated by an increase in their proliferation and production of IFN-γ, IL-6, and IL-2 proinflammatory cytokines. Whereas oxidative stress increased the DC ability to stimulate IFN-γ production by OVA-specific CD8(+) T cells, cellular proliferation and cytotoxicity were not affected. Compared with untreated DC, oxidative stress significantly reduced the capacity of DC to generate T(regs), which were restored by using anti-IL-6. With regard to DC trafficking, whereas oxidative stress increased DC expression of p-Akt and p-NF-κB, targeting PI3Kγ and NF-κB pathways abrogated the observed increase in DC migration. Our data propose novel insights on the activation of DC by oxidative stress and provide rationales for targeted therapies, which can potentially attenuate IRI.

CD8+ T cells produce a dialyzable antigen-specific activator of dendritic cells

“…Subsequent to DC binding, DC activation may be achieved by the presence of associated immune stimulators, such as S100a9 or the identified S100-derived peptides. Our preliminary data and previous reports suggest that other nonspecific immune stimulators, such as inosine and hypoxanthine, may contribute to this DC activation [45][46][47]. Secretion of cytokines by the activated DC results in induction of IL-17 and related cytokines from bystander memory CD8 + T cells in a manner that does not require TCR engagement or direct contact with the DC.…”

Novel Application of Localized Nanodelivery of Anti–Interleukin-6 Protects Organ Transplant From Ischemia–Reperfusion Injuries

“…We first examined the effect of oxidative stress on DC mitochondria in vitro by using H 2 O 2 exposure as a model of DC ischemia as described previously . Control and oxidatively stressed DCs (OS‐DCs) were stained with mitotracker red, which stains mitochondrial membrane potential.…”

“…Splenic DCs were isolated by using CD11c magnetic beads (Miltenyi Biotec, Cambridge, MA). Bone marrow–derived DCs were generated as described previously . Briefly, femurs and tibiae of C57BL/6 mice were flushed with RPMI‐1640 and washed twice with PBS.…”

The role of dendritic cells regulated by HMGB1/TLR4 signalling pathway in myocardial ischaemia reperfusion injury

“…Comparison of 24, 48, and 72 h protein and mRNA levels of MyD88, NF-κB of mDCs from different groups. G, 24, 48, and 72 h Western blot analysis of MyD88 protein expression; (H)24,48, and 72 h Comparison of cardiac myocyte apoptosis rate and cTnI concentration from different groups in the co-culture of dendritic cells (DCs) and cardiac myocytes (CMs). Flow cytometry were performed.…”