UV Radiation Induces the Epidermal Recruitment of Dendritic Cells that Compensate for the Depletion of Langerhans Cells in Human Skin.

UVR causes skin injury and inflammation, resulting in impaired immune function and increased skin cancer risk. Langerhans cells (LCs), the immune sentinels of the epidermis, are depleted for several days following a single UVR exposure and can be reconstituted from circulating monocytes. However, the differentiation pathways leading to the recovery of a normal pool of LCs is still unclear.

Differential capacity of human skin dendritic cells to polarize CD4+ T cells into IL-17, IL-21 and IL-22 producing cells.

Accumulating evidence suggests a contribution of T cell-derived IL-17, IL-21 and IL-22 cytokines in skin immune homeostasis as well as inflammatory disorders. Here, we analyzed whether the cytokine-producing T lymphocytes could be induced by the different subsets of human skin dendritic cells (DCs), i.e.

Human langerhans cells are more efficient than CD14(-)CD1c(+) dermal dendritic cells at priming naive CD4(+) T cells.

Few data are available regarding the role of human skin dendritic cells (DCs) in driving T-cell responses. In this study we analyzed the relative capacity of Langerhans cells (LCs) and dermal CD14(-)CD1c(+) DCs (DDCs) to trigger naive CD4(+) T-cell proliferation and differentiation. DC subsets were purified after a 2-day migration from epidermis and dermis of the same skin sample.

Poly(I:C)-Treated human langerhans cells promote the differentiation of CD4+ T cells producing IFN-gamma and IL-10.

Epidermal Langerhans cells (LCs) are the first dendritic cells to encounter skin pathogens. However, their function has recently been challenged, especially in the initiation of T-cell responses to viral antigens. We have previously reported that fresh immature human LCs express mRNA encoding TLR3.

Different mechanisms are involved in apoptosis induced by melanoma gangliosides on human monocyte-derived dendritic cells.

Tumor escape is linked to multiple mechanisms, notably the liberation, by tumor cells, of soluble factors that inhibit the function of dendritic cells (DC). We have shown that melanoma gangliosides impair DC differentiation and induce their apoptosis. The present study was aimed to give insight into the mechanisms involved.

Human C3 deficiency associated with impairments in dendritic cell differentiation, memory B cells, and regulatory T cells.

Primary C3 deficiency, a rare autosomal inherited disease (OMIM 120700), was identified in a 2-year-old male suffering from recurrent pyogenic infections from early infancy with undetectable total complement hemolytic activity (CH50) and C3 values. The nonconsanguineous parents and the two patients' two siblings had 50% normal serum C3 concentration. The molecular abnormality associated a paternal allele coding C3 with the missense mutation p.

Supplementation with oral probiotic bacteria protects human cutaneous immune homeostasis after UV exposure-double blind, randomized, placebo controlled clinical trial.

There is now strong evidence that probiotic bacteria can regulate inflammatory immune responses. Here, we analyzed whether oral supplementation with the probiotic bacterial strain Lactobacillus johnsonii (La1) could interfere with skin immune status following UV exposure. A randomized, double-blind, placebo controlled clinical trial was conducted with 54 healthy volunteers receiving either La1 or placebo, during six weeks prior to solar-simulated UV irradiation.

Differential effects of allergens and irritants on early differentiating monocyte-derived dendritic cells.

Phenotypic modifications induced by contact allergens on monocyte-derived dendritic cells (MoDC) have been proposed as an in vitro alternative method to discriminate potential sensitizers from irritants. However, the sensitivity of the assay remains controversial. In all the studies reported so far, DC treatment with chemicals was carried out after 5 to 6 days of monocyte culture.

Melanoma-derived gangliosides impair migratory and antigen-presenting function of human epidermal Langerhans cells and induce their apoptosis.

Gangliosides are ubiquitous, membrane-associated, glycosphingolipids, the composition and production of which is altered in many tumour cells. They have been shown to inhibit the in vitro generation and differentiation of dendritic cells (DCs) from progenitors, but their effect on human tissue-residing DCs is yet to be investigated. In the present study, we analysed the effect of GM3 and GD3 gangliosides purified from human melanoma tumours on the phenotypic and functional maturation of human epidermal Langerhans cells (LCs), the first immune barrier against the tumour cells.

UVA radiation impairs phenotypic and functional maturation of human dermal dendritic cells.

There is now strong evidence that the ultraviolet A (UVA) part of the solar spectrum contributes to the development of skin cancers. Its effect on the skin immune system, however, has not been fully investigated. Here, we analyzed the effects of UVA radiation on dermal dendritic cells (DDC), which, in addition, provided further characterization of these cells.

TNF-alpha enhances phenotypic and functional maturation of human epidermal Langerhans cells and induces IL-12 p40 and IP-10/CXCL-10 production.

Dendritic cells (DC) play a central role in immunity/tolerance decision, depending on their activation/maturation state. TNF-alpha is largely produced in the skin under inflammatory conditions. However, it still remains to be defined how TNF-alpha modulates the activation status of human LC, the most specialized DC controlling skin immunity.

Gangliosides from human melanoma tumors impair dendritic cell differentiation from monocytes and induce their apoptosis.

Gangliosides are ubiquitous membrane-associated glycosphingolipids, which are involved in cell growth and differentiation. Most tumor cells synthesize and shed large amounts of gangliosides into their microenvironment, and many studies have unraveled their immunosuppressive properties. In the present study we analyzed the effects of GM3 and GD3 gangliosides, purified from human melanoma tumors, on the differentiation of monocyte-derived dendritic cells (MoDC).