Eczéma allergique de contact : Comment ré-induire une tolérance ?

L’eczéma allergique de contact est une dermatose inflammatoire fréquente, due à l’activation de lymphocytes T (LT) CD8+ cytotoxiques spécifiques d’haptènes en contact avec la peau. Les LT CD4+ sont, quant à eux, doués d’une fonction régulatrice et tolérogène, puisqu’ils limitent l’inflammation cutanée chez les patients (régulation) et préviennent le développement des LT effecteurs chez les individus sains (tolérance) : l’eczéma correspond donc à une rupture de la tolérance immunitaire aux haptènes présents dans l’environnement quotidien. Plusieurs sous-populations de LT CD4+ régulateurs (LT reg), parmi lesquelles celle des LT CD4+CD25+ naturels, sont impliquées dans la tolérance et la régulation de l’eczéma, via la production des cytokines immunosuppressives IL-10 (interleukine-10) et TGFβ (transforming growth factor β). Les travaux en cours ont pour objectif de ré-induire une tolérance immunitaire dans l’eczéma, soit en améliorant les méthodes existantes d’induction de tolérance aux haptènes (tolérance orale, tolérance à faibles doses, immunothérapie spécifique, tolérance induite par les rayons ultraviolets), soit en développant de nouvelles molécules capables d’activer les LT reg. Plus généralement, les données issues de ces travaux devraient pouvoir être appliquées au traitement des maladies auto-immunes ou allergiques, caractérisées par un déficit fonctionnel ou quantitatif en Ltreg à l’origine d’une rupture de la tolérance aux auto-antigènes ou aux allergènes de l’environnement.Allergic contact dermatitis (ACD) is a skin inflammatory disease mediated by activation of CD8+ cytotoxic T cells specific for haptens in contact with the skin. CD4+ T cells behave as both regulatory and tolerogenic cells since they down-regulate the skin inflammation in patients with ACD (regulation) and prevent the developement of eczema (tolerance) in normal individuals. Thus, ACD corresponds to a breakdown of immune tolerance to haptens in contact with the skin. Several regulatory CD4+ T cell subsets (Treg), especially CD4+CD25+ natural Treg cells, are involved in immunological tolerance and regulation to haptens through the production of the immunosuppressive cytokines IL-10 and TGF-β. Ongoing strategies to re-induce immune tolerance to haptens in patients with eczema include improvement of existing methods of tolerance induction (oral tolerance, low dose tolerance, allergen-specific immunotherapy, UV-induced tolerance) as well as development of new drugs able to activate IL-10 producing Treg cells in vivo. Ongoing and future progress in this area will open up new avenues for treatment of eczema and more generally autoimmune and allergic diseases resulting from a breakdown of tolerance to autoantigens and allergens, respectively

Additional file 2 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Video 2: Aerotaxis of primary T5 tumour cells. Epithelial cancer cells were extracted from the T5 tumour and fibroblasts and immune cells were removed by magnetic immunopurification on EpCAM+ MACS columns (Myltenii Biotech, Germany). Aerotaxis of cancer cells from this representative tumour was observed for 48h. As can be seen, the cells at the margin of the cell cluster undergo efficient aerotactic migration in a medium supplemented with EGF while the central cluster in the most hypoxic region, but outside the gradient of oxygen, ends up breaking up into different cell clusters

Additional file 6 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Supplementary Material

Additional file 5 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Video 5: Aerotaxis of primary T6 tumour cells in Cultrex: The conditions are identical to those of Video 4, Cultrex-BME being used instead of the usual liquid medium for the migration step which was observed for 60 h. Unlike MCF10A cells, primary cancer cells from the T6 tumour embedded in Cultrex-BME can invade the extracellular matrix (ECM) upon cell confinement, demonstrating that aerotaxis is a strong enough signal to guide cancer cells through ECM. Note the star-like trajectory of cells in the ECM instead of the usual ring-shaped migration seen in videos 2 and 3

Additional file 4 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Video 4: Absence of aerotaxis of MCF10A in Cultrex: Compared to the conditions used in Video 1, Cultrex-BME (extracellular matrix secreted by Engelbreth-Holm-Swarm mouse sarcoma cells polymerizing at 37°C) instead of the conventional liquid medium was used before confining the cell cluster under the glass coverslip. Cells’ migration was observed for 60 h. In contrast to Video 1, we see that MCF10A cells fail to perform aerotactic migration when embedded in Cultrex-BME. The reason is that these untransformed cells are not invasive (see Table 3)

Additional file 7 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Video 6: Magnification of aerotactic invasion of primary T6 tumour cells in Cultrex: This video illustrates how primary cancer cells from the T6 tumour may escape from hypoxia when embedded in Cultrex-BME. Leader cells, probably endowed with high matrix degradation skills, open the way within the extracellular matrix to facilitate invasion of additional cells migrating as cohorts

Additional file 1 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Video 1: Aerotaxis of untransformed MCF10A cells: This video shows the aerotactic migration of non-transformed MCF10A cells confined under a glass coverslip responsible for hypoxia generation for 48h. For this aerotactic assay, four thousand cells were plated as a 1 μL droplet within a well of a 96-well plate, and following adhesion, the cell cluster was confined under a 6 mm glass coverslip. The video is compiled from an Incucyte 48 h time-lapse experiment using a 4X bright-field objective. Cells located at the border of the cluster migrate directionally towards the edge of the coverslip following the steep oxygen gradient generated by cell respiration while the late cells migrated more randomly since they navigated outside of the oxygen gradient

Additional file 3 of EGFR-dependent aerotaxis is a common trait of breast tumour cells

Video 3: Aerotaxis of primary T5 tumour cells. Another example of aerotaxis of cancer cells extracted from another tumour, the T7 tumour. The migration oberved for 48h is very similar to that of video 2