Upstream eventCovalent Binding, Protein
Activation, Dendritic Cells
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding|
|Covalent Protein binding leading to Skin Sensitisation||adjacent||High|
Life Stage Applicability
Key Event Relationship Description
As noted in the AOP during allergen contact with the skin, immature epidermal dendritic cells, known as Langerhans cells, and dermal dendritic cells serve as antigen-presenting cells;;. In this role, they recognize and internalize the hapten-protein complex formed during covalent binding. Subsequently, the dendritic cell loses its ability to seize new hapten-protein complexes and gains the potential to display the allergen-MHC-complex to naive T-cells; this process is often referred to as dendritic cell maturation.
This KER description is based only on the OECD document 2012 and needs updating.
Evidence Supporting this KER
It is accepted and experimentally proved that during skin sensitisation process, immature epidermal and dermal dendritic cells recognize and internalize the hapten-protein complex formed during covalent binding and subsequently mature and migrate to the local lymph nodes;;.
Using a flow-cytometric assay, the influence of contact sensitisers on endocytic mechanisms in murine Langerhans cells was measured. Epidermal cell suspensions were labelled with a monoclonal antibody directed to MHC class II molecules and pH-sensitive fluorochrome-coupled second step reagents. Study reported that stimulation with well-known sensitising compounds resulted in a partial conservation of the fluorescence intensity due to the internalisation of the labelled complexes into less acidic compartments. For untreated Langerhans cells or in the presence of irritants a significant quenching of fluorescence intensity due to the internalization of the MHC-antibody complexes into acidic compartments was noticed. In the h-CLAT assay measuring the expression of CD86 and CD54 protein markers on the surface of the human monocytic leukemia cell line THP-1, the cell exposure to known non sensitisers does not increase cell biomarker expression. On the contrary, exposure to well-known sensitisers leads to an increase of the CD86 and CD54 expression;.
Uncertainties and Inconsistencies
The expression of other cytokines linked to skin sensitisers include IL-1 α, IL-1β, IL-18, and TNF-α form the basis for other dendritic cell assays. In general, an increase in cytokine/chemokine secretion or receptor expression is observed when sensitisers were tested but not when non-sensitisers were tested. However, there is currently only a limited number of chemicals evaluated in more than one assay and results are sometimes contradictory.
Quantitative Understanding of the Linkage
It is not known how much change in the first event is needed to impact the second.
Known modulating factors
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
- Ryan CA, Gerberick GF, Gildea LA, Hulette BC, Bettis CJ, Cumberbatch M, Dearman RJ and Kimber I. 2005. Interactions of contact allergens with dendritic cells: opportunities and challenges for the development of novel approaches to hazard assessment. Toxicol. Sci. 88: 4-11.
- Ryan CA, Kimber I, Basketter DA, Pallardy M, Gildea LA, Gerberick GF. 2007. Dendritic cells and skin sensitisation. Biological roles and uses in hazard identification. Toxicol. Appl. Pharmacol. 221: 384-394.
- Kimber I, Basketter DA, Gerberick GF, Ryan CA and Dearman RJ. 2011. Chemical allergy: Translating biology into hazard characterization. Toxicol. Sci. 120(S1): S238-S268.
- Gerberick F, Aleksic M, Basketter D, Casati S, Karlberg AT, Kern P, Kimber I, Lepoittevin JP, Natsch A, Ovigne JM, Rovida C, Sakaguchi H and Schultz T. 2008. Chemical reactivity measurement and the predictive identification of skin sensitisers. Altern. Lab. Anim.36: 215-242.
- Karlberg AT, Bergström MA, Börje A, Luthman, K, Nilsson JL. 2008. Allergic contact dermatitis- formation, structural requirements, and reactivity of skin sensitizers. Chem. Res. Toxicol. 21: 53-69.
- Vocanson M, Hennino A, Rozieres A, Poyet G, Nicolas JF. 2009. Effector and regulatory mechanisms in allergic contact dermatitis. Allergy 64: 1699-1714.
- Aeby P, Ashikaga T, Bessou-Touya S, Schapky A, Geberick F, Kern P, Marrec-Fairley M, Maxwell G, Ovigne J-M, Sakaguchi H, Reisinger K, Tailhardat M, Martinozzi-Teisser S, Winkler P. 2010. Identifying and characterizing chemical skin sensitizers without animal testing; Colipa’s research and methods development program. Toxicol. In Vitro 24: 1465-1473.
- Basketter DA and Kimber I. 2010. Contact hypersensitivity. In: McQueen, CA (ed) Comparative Toxicology Vol. 5, 2nd Ed. Elsevier, Kidlington, UK, pp. 397-411.
- Adler S, Basketter D, Creton S, Pelkonen O, van Benthem J, Zuang V, Ejner-Andersen K, Angers- Loustau A, Aptula A, Bal-Price A, Benfenati E, Bernauer U, Bessems J, Bois FY, Boobis A, Brandon E, Bremer S, Broschard T, Casati S Coecke S Corvi R, Cronin M, Daston G, Dekant W, Felter S, Grignard E, Gundert-Remy U, Heinonen T, Kimber I, Kleinjans J, Komulainen H, Kreiling R, Kreysa J, Batista Leite S, Loizou G, Maxwell G, Mazzatorta P, Munn S, Pfuhler S, Phrakonkham P, Piersma A, Poth A, Prieto P, Repetto G, Rogiers V, Schoeters G, Schwarz M, Serafimova R, Tahti H, Testai E, van Delft J, van Loveren H, Vinken M, Worth A, Zaldivar JM. 2011. Alternative (non-animal) methods for cosmetics testing: current status and future prospects-2010. Arch. Toxicol. 85: 367-485.
- Lempertz U, Kühn U, Knop J and Becker D. 1996. An approach to predictive testing of contact sensitizers in vitro by monitoring their influence on endocytic mechanisms. Internat. Arch. Allergy Immunol. 111: 64-70.
- Sakaguchi H, Ashikaga T, Miyazawa M, Kosaka N, Ito Y, Yoneyama K, Sono S, Itagaki H, Toyoda H, Suzuki H. 2009. The relationship between CD86/CD54 expression and THP-1 cell viability in an in vitro skin sensitisation test-human cell line activation test (h-CLAT). Cell Biol. Toxicol. 25: 109-126.
- Ashikaga T, Sakaguchi H, Sono S, Kosaka N, Ishikawa M, Nukada Y, Miyazawa M, Ito Y, Nishiyama N, Itagaki H. 2010. A comparative evaluation of in vitro skin sensitisation tests: the human cell-line activation test (h-CLAT) versus the local lymph node assay (LLNA). Altern. Lab. Anim. 38:275-84.