Not only anti-inflammation, etanercept abrogates collagen-induced arthritis by inhibiting dendritic cell migration and maturation

The application of tumor necrosis factor inhibitors (TNFi) is a major breakthrough in the treatment of rheumatoid arthritis (RA). While the anti-inflammatory nature of TNFi is thought to contribute to the therapeutic effects, recent data show that the pharmacology of TNF-α blockade is probably more complex than previously thought. This study investigates whether etanercept (ETN), one of the TNF antagonists, suppresses arthritis development through modulation of dendritic cell (DC) functions. Bone marrow-derived DCs (BMDCs) were stimulated with lipopolysaccharide (LPS) and treated with ETN for 24 hrs. DC functions, including maturation and migration, were determined. DCs from the lymph nodes (LNs) of ETN-treated collagen-induced arthritis (CIA) mice were analyzed for phenotypes and subsets. ETN efficiently inhibited the phenotypic maturation both in vitro and in vivo. ETN treatment delayed the onset and reduced the severity of arthritis in CIA mice. Moreover, ETN treatment strongly down regulated the number of both myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in LNs, possibly due to the depressive effect on the expression of CXCR4 on DCs in peripheral blood. The impaired DC migration to local LNs by ETN down regulated the number of T cells and B cells, and changed the LN cellular composition. The data show that TNF-α blockade has profound effects on DC maturation and migration, which may contribute to its immune regulatory effects in RA patients.

Tumor necrosis factor-alpha and interleukin-17 differently affects Langerhans cell distribution and activation in an innovative three-dimensional model of normal human skin

Among the several cytokines involved in the psoriasis pathogenesis, tumor necrosis factor (TNF)-alpha and interleukin (IL)-17 play a central role. Many biomolecular steps remain unknown due to difficulty to obtain psoriatic models. To investigate the effect of TNF-alpha and IL-17 on the ultrastructure, immunophenotype, and number of epidermal Langerhans cells (LCs), human skin explants (n=7) were cultured air-liquid interface in a Transwell system. Four different conditions were used: medium alone (control), medium added with 100 ng/ml TNF-alpha or 50 ng/ml IL-17 or a combination of both cytokines. Samples were harvested 24 and 48 h after cytokine addition and were frozen. Samples harvested at 24h were also processed for transmission electron microscopy (TEM). By immunofluorescence analysis with anti-human Langerin antibody (three experiments/sample) we calculated the percentage of LCs/mm(2) of living epidermis after 24 and 48 h of incubation (considering control as 100%). At 24h LC number was significantly higher in samples treated with both cytokines (216.71+15.10%; p<0.001) and in TNF-alpha (125.74+26.24%; p<0.05). No differences were observed in IL-17-treated samples (100.14+38.42%). After 48 h, the number of epidermal Langerin-positive cells in IL-17- and TNF-alpha treated samples slightly decreased (94.99+36.79% and 101.37+23% vs. their controls, respectively). With the combination of both cytokines epidermal LCs strongly decreased (120+13.36%). By TEM, upon TNF-alpha stimulus LCs appeared with few organelles, mostly mitochondria, lysosomes, and scattered peripherical BGs. Upon IL-17 stimulus, LCs showed a cytoplasm with many mitochondria and numerous BGs close to the perinuclear space and Golgi apparatus, but also at the periphery, at the beginning of the dendrites. The addition of both cytokines did not affect LC ultrastructure. Our study showed that IL-17 induced significant changes in LC ultrastructure, while the combination of both cytokines seems to have a strong chemo-attractant effect on epidermal LCs, supporting the relevance of investigating the interplay between LCs and pro-inflammatory cytokines in the ongoing of the disease.

Effects of TNF-alpha inhibitors on the number of epidermal Langerhans cells in uninvolved skin of psoriatic patients: a pilot study

Only limited data are available on the effects of TNF-alpha inhibitors on dendritic cells. However, TNF-alpha plays a central role in the biology of dendritic cells, both with regard to their maturity process and mobilization to secondary lymphoid organs. In particular, the effects of TNF-alpha inhibitors on Langerhans cells in healthy skin have never been investigated. In this pilot study, we aimed to assess the change of the density of Langerhans cells within the normal, not photo-exposed, skin of 17 psoriatic patients, before and after 16 weeks of treatment with TNF-alpha inhibitors. Most of the patients (88%) showed an increase or a similar density of Langerhans cells after 16 weeks of therapy with TNF-alpha inhibitors compared with baseline values. Only 2 patients (12%) showed a reduction of these cells following therapy with TNF-alpha inhibitors.

Dendritic cells: ultrastructural and immunophenotypical changes upon nb-UVB in vitiligo skin

The role of dendritic cells in vitiligo is still unclear. Few studies have provided contradictory results about their quantitative variation and no data exist concerning their immunophenotypical distribution in diseased skin. The purpose of our study was to analyze the presence, the distribution, the immunophenotypical markers and the effects of nb-UVB therapy on dendritic cells in non-lesional, perilesional, and lesional vitiligo skin. Punch-biopsies of 6 mm were taken from lesional, perilesional, and non-lesional skin of 12 patients affected by non-segmental vitiligo, treated with nb-UVB. An immunohistochemical and an ultrastructural analysis were performed. Immunohistochemical and ultrastructural analysis showed both quantitative and qualitative modifications of Langerhans cells. Nb-UVB therapy, one of the most effective treatments for the disease, was able to reduce the Langerhans cells number and to redistribute main dendritic subsets. This study underlines the importance of dendritic cells, Langerhans cells in particular, in non-segmental vitiligo, in its pathogenesis and in its better therapeutical approach.

Quantitative study of Langerhans cells in basal cell carcinoma with higher or lower potential of local aggressiveness

BACKGROUNDS

Basal cell carcinoma affects areas of the body that have been exposed to the sun, and this disorder has different clinical and histopathologic presentations. Some of these forms have a higher potential of local aggressiveness, while others have a lower potential. Langerhans cells actively participate in the skin immune system.

OBJECTIVES

To quantitatively evaluate the number of Langerhans cells on the epidermis of basal cell carcinoma with lower and higher potential of local aggressiveness and on adjacent normal epidermis.

METHODOLOGY

The authors divided the sample into two groups with 14 histological slides each: one with basal cell carcinoma with lower potential of local aggressiveness and the other with basal cell carcinoma with higher potential of local aggressiveness. Immunohistochemistry with S-100 protein was used in the identification of Langerhans Cells. Langerhans cells present in 7 microscopic fields were counted using optical microscopy (400X magnification) and Weibel's morphometric grade. The mean for each lamina was obtained. Wilcoxon's statistical test was employed.

RESULTS

In the group with lower potential of local aggressiveness, there was a significant increase in the number of Langerhans cells in the adjacent normal epidermis, as compared with the number of cells in the epidermis superposed to the basal cell carcinoma (pd 0.05). There was no significant statistical difference in the group with higher potential of local aggressiveness (p >0.05).

CONCLUSION

The higher number of Langerhans cells in the normal epidermis adjacent to the tumoral lesion with lower potential of local aggressiveness could indicate greater immunological resistance of the epidermis, thus limiting the aggressiveness of the neoplasm.