title: Understanding chemical allergen potency: role of NLRP12 and Blimp-1 in the induction of IL-18 in human keratinocytes.
abstract: Keratinocytes (KCs) play a key role in all phases of skin sensitization. We recently identified interleukin-18 (IL-18) production as useful end point for determination of contact sensitization potential of low molecular weight chemicals. The aim of this study was to identify genes involved in skin sensitizer-induced inflammasome activation and to establish their role in IL-18 production. For gene expression analysis, cells were treated for 6 h with p-phenylenediamine (PPD) as reference contact allergen; total RNA was extracted and examined with a commercially available Inflammasome Polymerase Chain Reaction (PCR) array. Among genes induced, NLRP12 (Nod-like receptor P12) was selected for further investigation. NLRP12 promoter region contains Blimp-1 (B-lymphocyte-induced maturation protein-1)/PRDM1 binding site, and from the literature, it is reported that Blimp-1 reduces NLRP12 activity and expression in monocytes/macrophages. Their expression and role in KCs are currently unknown. To confirm NLRP12 expression and to investigate its relationship with Blimp-1, cells were exposed for different times (3, 6 and 24 h) to the extreme sensitizer 2,4-dinitrochlorobenzene (DNCB) and the strong sensitizer PPD. Allergens were able to induce both genes, however, with different kinetic, with DNCB more rapidly upregulating Blimp-1 and inducing IL-18 production, compared to PPD. NLRP12 and Blimp-1 expression appeared to be inversely correlated: Blimp-1 silencing resulted in increased NLRP12 expression and reduced contact allergen-induced IL-18 production. Overall results indicate that contact allergens of different potency differently modulate Blimp-1/NLRP12 expression, with strong allergen more rapidly downregulating NLRP12, thus more rapidly inducing IL-18 production. Data confirm that also in KCs, NLRP12 has an inhibitory effect on inflammasome activation assessed by IL-18 maturation.
authors: University of Milan, Milan, Italy. angela.papale@unimi.it.
authors: Angela
authors: A
authors: Papale
authors: University of Milan, Milan, Italy.
authors: Elena
authors: E
authors: Kummer
authors: University of Milan, Milan, Italy.
authors: Valentina
authors: V
authors: Galbiati
authors: University of Milan, Milan, Italy.
authors: Marina
authors: M
authors: Marinovich
authors: University of Milan, Milan, Italy.
authors: Corrado L
authors: CL
authors: Galli
authors: University of Milan, Milan, Italy.
authors: Emanuela
authors: E
authors: Corsini
mesh_terms: D000485:Allergens / Q000276:immunology*; D002460:Cell Line; D017449:Dermatitis, Allergic Contact / Q000276:immunology; D004137:Dinitrochlorobenzene / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology; D020868:Gene Silencing; D006801:Humans; D058847:Inflammasomes / Q000276:immunology; D020382:Interleukin-18 / Q000276:immunology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000276:immunology*; D015603:Keratinocytes / Q000276:immunology*; D010655:Phenylenediamines / Q000276:immunology; D016133:Polymerase Chain Reaction; D000074462:Positive Regulatory Domain I-Binding Factor 1; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology*; D013997:Time Factors; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000485:Allergens; D004137:Dinitrochlorobenzene; D058847:Inflammasomes; D020382:Interleukin-18; D047908:Intracellular Signaling Peptides and Proteins; C476731:NLRP12 protein, human; D010655:Phenylenediamines; D012097:Repressor Proteins; C087042:PRDM1 protein, human; D000074462:Positive Regulatory Domain I-Binding Factor 1; C029728:4-phenylenediamine
keywords: Allergen potency; Contact allergy; IL-18; In vitro; Inflammasome