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A B S T R A C TSqualene is a natural triterpene consumed as an integral part of the human diet. Increasing evidence demonstrates that squalene has antioxidant, cardioprotective and anticarcinogenic activities. Nevertheless, its anti-inflammatory properties remain unclear. The effects of squalene on lipopolysaccharide (LPS)-mediated inflammatory response in murine macrophages and human monocytes and neutrophils were investigated. Squalene reduced intracellular levels of ROS, nitrites, cytokines (TNF-α, IL-1β, IL-6 and IFN-γ) and proinflammatory enzymes (iNOS, COX-2 and MPO), including a decreased expression of TLR4and key proteins for signalling pathways mediated by NF-κB (IκBα), MAPKs (JNK) and MMPs (1, 3 and 9). In addition, squalene enhanced expression levels of anti-inflammatory enzymes (HO-1) and transcription factors (Nrf2 and PPARγ). This study establishes that squalene has significant potential for management of inflammatory conditions characterized by an overactivation of neutrophils/monocytes/macrophages and thereby for the efficient termination of the inflammatory response.

Background: Nickel is the most frequent cause of T cell-mediated allergic contact dermatitis worldwide. In vitro, CD4+ T cells from all donors respond to nickel but the involved αβ T cell receptor (TCR) repertoire has not been comprehensively analyzed. Methods: We introduce CD154 (CD40L) upregulation as a fast, unbiased, and quantitative method to detect nickel-specific CD4+ T cells ex vivo in blood of clinically characterized allergic and non allergic donors. Naïve (CCR7+ CD45RA+) and memory (not naïve) CD154+ CD4+ T cells were analyzed by flow cytometry after 5 hours of stimulation with 200 µmol/L NiSO 4 ., TCR α-and β-chains of sorted nickel-specific and control cells were studied by high-throughput sequencing. Results: Stimulation of PBMCs with NiSO 4 induced CD154 expression on ~0.1% (mean) of naïve and memory CD4+ T cells. In allergic donors with recent positive patch test, memory frequencies further increased ~13-fold and were associated with markers of in vivo activation. CD154 expression was TCR-mediated since single clones could be This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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