IL-10 Conditioning of Human Skin Affects the Distribution of Migratory Dendritic Cell Subsets and Functional T Cell Differentiation

Abstract

In cancer patients pervasive systemic suppression of Dendritic Cell (DC) differentiation and maturation can hinder vaccination efficacy. In this study we have extensively characterized migratory DC subsets from human skin and studied how their migration and T cell-stimulatory abilities were affected by conditioning of the dermal microenvironment through cancer-related suppressive cytokines. To assess effects in the context of a complex tissue structure, we made use of a near-physiological skin explant model. By 4-color flow cytometry, we identified migrated Langerhans Cells (LC) and five dermis-derived DC populations in differential states of maturation. From a panel of known tumor-associated suppressive cytokines, IL-10 showed a unique ability to induce predominant migration of an immature CD14+CD141+DC-SIGN+ DC subset with low levels of co-stimulatory molecules, up-regulated expression of the co-inhibitory molecule PD-L1 and the M2-associated macrophage marker CD163. A similarly immature subset composition was observed for DC migrating from explants taken from skin overlying breast tumors. Whereas predominant migration of mature CD1a+ subsets was associated with release of IL-12p70, efficient Th cell expansion with a Th1 profile, and expansion of functional MART-1-specific CD8+ T cells, migration of immature CD14+ DDC was accompanied by increased release of IL-10, poor expansion of CD4+ and CD8+ T cells, and skewing of Th responses to favor coordinated FoxP3 and IL-10 expression and regulatory T cell differentiation and outgrowth. Thus, high levels of IL-10 impact the composition of skin-emigrated DC subsets and appear to favor migration of M2-like immature DC with functional qualities conducive to T cell tolerance.

In situloading of skin dendritic cells with apoptotic bleb-derived antigens for the induction of tumor-directed immunity

“…The increased and preferential migration of CD1a C CD14 ¡ DDCs and LCs by i.d. administration of 4/GM, which was consistent with previous observations, 12 was not affected by co-injection of either ACRs or blebs (Fig. 1C).…”

“…Interestingly, and in contrast to the dogma of reduced exogenous antigen uptake after inducing DC maturation, we observed enhanced uptake of blebs by all migratory DC subsets after coadministration of 4/GM, whereas the uptake was unaffected or even decreased by this cytokine cocktail when ACRs were injected. As CD1a C CD14 ¡ DDCs constitute the predominant subset migrating from the skin after administration of 4/GM and have been previously identified as the most potent in terms of effector T-cell activation, 11,12 preferential uptake of blebs by this subset may prove favorable in terms of vaccination efficacy. It has recently been described that CD14 C DDCs are far less potent in effectively priming CD8 C T cells to differentiate into cytotoxic effector cells, as compared to CD1a C DDCs and LCs, and moreover induce regulatory T cells, a process driven by the production of IL-10 and the expression of Ig-like transcript inhibitory receptors.…”

“…[11][12][13] Indeed, under steady state conditions CD1a C LCs and DDCs are the most mature DC subsets displaying a T-cell stimulatory phenotype. 12 From our prior observations, we have concluded that TAAs administered via i.d.…”

“…[11][12][13] Indeed, under steady state conditions CD1a C LCs and DDCs are the most mature DC subsets displaying a T-cell stimulatory phenotype. 12 From our prior observations, we have concluded that TAAs administered via i.d. injection should be selected to preferentially target CD1a C CD14 ¡ DDCs as these represent the most frequent skin DC subset with superior T-cell activation qualities, and as such, are thus likely to be the most potent in inducing tumor-specific T-cell responses.…”

“…injection should be selected to preferentially target CD1a C CD14 ¡ DDCs as these represent the most frequent skin DC subset with superior T-cell activation qualities, and as such, are thus likely to be the most potent in inducing tumor-specific T-cell responses. 1,12,13 Malignant cells have multiple ways of evading immune recognition, one of which is de-differentiation, 14 often accompanied by a loss of TAA expression, suggesting that broadening the tumordirected immune response by increasing the array of presented TAAa is likely to enhance the effectiveness of antitumor vaccination strategies. Most immunotherapeutic strategies that target a single TAA, rely on the characterization of the selected TAA, have limited inter-patient antigenic overlap and are often HLArestricted.…”