title: Cross talk between keratinocytes and dendritic cells: impact on the prediction of sensitization.
abstract: Understanding the mechanistic aspects involved in sensitization by chemicals will help to develop relevant preventive strategies. Many potential sensitizers are not directly immunogenic but require activation outside or inside the skin by nonenzymatic oxidation (prehaptens) or metabolic transformation (prohaptens) prior to being able to induce an immune response. This necessary activation step has not yet been actively integrated into a cell line-based prediction approach. We cocultured HaCaT keratinocytes with THP-1 as dendritic cell-like cells allowing intercellular interactions. The sensitizing potential was determined by analyzing differences in the expression of CD86, CD40, and CD54 on cocultured THP-1 cells. This new assay setup allowed (1) to distinguish irritants from allergens without influencing cell viability and (2) to discriminate pre/prohaptens from haptens. Under coculture conditions, the prohaptens eugenol, 2-methoxy-4-methylphenol, and benzo[a]pyrene induced a significantly higher upregulation of CD86 expression on THP-1. In agreement with the hapten concept, responses to 2,4-dinitrochlorobenzene, Bandrowski's base, and the prehapten isoeugenol were not significantly modified. Inhibition of cytochrome P450 or NAD(P)H:quinone oxidoreductase (NQO1) activity reduced the prohapten-mediated upregulation of CD86 on cocultured THP-1 cells. This coculture assay allowing cross talk between HaCaT and THP-1 cells appears to be suitable for the detection of prohaptens, is reproducible, easy to perform, and avoids donor variations. In addition, this assay is a promising approach to understand the impact of cross talk on the prediction of sensitization and once established may be integrated in a future in vitro toolbox to detect potential skin sensitizers and may thus contribute to reduce animal testing.
authors: Department of Environmental Toxicology, University Trier, 54286 Trier, Germany.
authors: Jenny
authors: J
authors: Hennen
authors: Pierre
authors: P
authors: Aeby
authors: Carsten
authors: C
authors: Goebel
authors: Thomas
authors: T
authors: Schettgen
authors: Aurelia
authors: A
authors: Oberli
authors: Michaela
authors: M
authors: Kalmes
authors: Brunhilde
authors: B
authors: Blömeke
mesh_terms: D000485:Allergens / Q000633:toxicity; D000826:Animal Testing Alternatives / Q000379:methods*; D015703:Antigens, CD / Q000378:metabolism; D051940:B7-2 Antigen / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006241:Haptens / Q000276:immunology / Q000494:pharmacology; D006801:Humans; D007114:Immunization; D007509:Irritants / Q000633:toxicity; D015603:Keratinocytes / Q000276:immunology / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D011237:Predictive Value of Tests; D020239:Receptor Cross-Talk / Q000502:physiology*; D015203:Reproducibility of Results; D023422:Skin Irritancy Tests / Q000379:methods; D015854:Up-Regulation
chemical_list: D000485:Allergens; D015703:Antigens, CD; D051940:B7-2 Antigen; D004791:Enzyme Inhibitors; D006241:Haptens; D007509:Irritants