Role of ROS and HMGB1 in contact allergen-induced IL-18 production in human keratinocytes.
Keratinocytes have a key role in all phases of allergic contact dermatitis. We have recently identified the possibility to use IL-18 production for the in vitro identification of contact allergens. The purpose of this study was to characterize the molecular mechanisms underlying allergen-induced IL-18 production, in order to identify the cellular source of reactive oxygen species (ROS) and the danger signals involved. The NCTC2544 cell line was exposed to three contact allergens, namely p-phenylenediamine (PPD), 2,4-dinitrochlorobenzene (DNCB), and citral, in the presence or absence of diphenylene iodonium (DPI), allopurinol, and rotenone to identify the source of ROS, and to anti-Toll-like receptor 4 antibody and glycirrizic acid to characterize the danger-associated molecular pattern molecules. In the case of PPD, the induction of IL-18 can be modulated by rotenone, allopurinol, and DPI. In the case of DNCB, rotenone completely prevents the induction of IL-18, whereas for citral, DPI completely prevents the induction of IL-18. We demonstrated the ability of all allergens tested to induce the release of high-mobility group protein B1 (HMGB1). Its sequester by glycirrizic acid significantly modulates PPD-induced IL-18 production and completely prevents DNCB- and citral-induced IL-18. We found that different intracellular sources of ROS are triggered by contact allergens, and an important role for HMGB1 in chemical allergen-induced IL-18 production was demonstrated.
Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy. Electronic address: valentina.galbiati@unimi.it.
Valentina
V
Galbiati
Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy.
Angela
A
Papale
Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy.
Corrado L
CL
Galli
Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy.
Marina
M
Marinovich
Laboratory of Toxicology, DiSFeB, Università degli Studi di Milano, Milan, Italy.
Emanuela
E
Corsini
D000080462:Acyclic Monoterpenes; D000485:Allergens / Q000737:chemistry*; D020170:Caspase 1 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D016207:Cytokines / Q000378:metabolism; D017449:Dermatitis, Allergic Contact / Q000378:metabolism; D004137:Dinitrochlorobenzene / Q000737:chemistry; D004817:Epidermis / Q000378:metabolism; D019695:Glycyrrhizic Acid / Q000737:chemistry; D024243:HMGB1 Protein / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D020382:Interleukin-18 / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism*; D039821:Monoterpenes / Q000737:chemistry; D009861:Onium Compounds / Q000737:chemistry; D010655:Phenylenediamines / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism
D000080462:Acyclic Monoterpenes; D000485:Allergens; D016207:Cytokines; D004137:Dinitrochlorobenzene; D024243:HMGB1 Protein; C585491:HMGB1 protein, human; D020382:Interleukin-18; D039821:Monoterpenes; D009861:Onium Compounds; D010655:Phenylenediamines; D017382:Reactive Oxygen Species; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D019695:Glycyrrhizic Acid; C007517:diphenyleneiodonium; D020170:Caspase 1; C007076:citral; C029728:4-phenylenediamine