Langerin-positive Cells Research Articles

Skin antigen-presenting cells and wound healing: New knowledge gained and challenges encountered using mouse depletion models.

The role of antigen-presenting cells in the skin immune system, in particular Langerhans cells and dendritic cells, has not been well defined. We recently published a study in 'Immunology' where we reported that the loss of langerin-positive cells in the skin accelerated wound repair in the Lang-DTR mouse. The study published here by Li, et al. reports delayed wound closure following depletion of CD11c-positive cells in the CD11c-DTR mouse. In this commentary, we attribute the differences between these results to several factors that differ between the studies including the depletion of different cell populations; differences in the age and the sex of mice; differences in antibiotic use between the studies; and differences in the location of the biopsies that were taken. Here, we describe the impact of these differences on wound healing and conclude that further standardization of the wound model, and further characterization of the specific cells that are depleted in these mice, is necessary to better understand how antigen-presenting cells contribute to wound healing.

Langerin (CD207)-positive cells in leprosy: Possible implications for pathogenesis of the disease with special emphasis on dermal immunoreactivity

Leprosy is a disease caused by Mycobacterium leprae, which is characterized by two distinct poles, the tuberculoid pole and the lepromatous pole, depending on the immune response to the bacillus. Langerin-positive cells are dendritic cells that appear to play an essential role in the development of the disease. These cells are specialized in the processing and presentation of antigens, exerting an important function in the activation of the immune system. To evaluate the expression of langerin-positive cells (CD207+) in skin lesion fragments of patients with a diagnosis of M. leprae infection and to associate the expression of these cells with the polar forms of the disease. Langerin-positive cells were detected in larger numbers in lesions of patients with the tuberculoid form compared to those with the lepromatous form. The presence of a larger number of these cells in patients with the tuberculoid form suggests an important participation of langerin-positive cells, capturing antigens and favoring an effective immune response to infection with M. leprae.

CD1c+ blood dendritic cells have Langerhans cell potential

AbstractLangerhans cells (LCs) are self-renewing in the steady state but repopulated by myeloid precursors after injury. Human monocytes give rise to langerin-positive cells in vitro, suggesting a potential precursor role. However, differentiation experiments with human lineage-negative cells and CD34+ progenitors suggest that there is an alternative monocyte-independent pathway of LC differentiation. Recent data in mice also show long-term repopulation of the LC compartment with alternative myeloid precursors. Here we show that, although monocytes are able to express langerin, when cultured with soluble ligands granulocyte macrophage colony-stimulating factor (GM-CSF), transforming growth factor β (TGFβ), and bone morphogenetic protein 7 (BMP7), CD1c+ dendritic cells (DCs) become much more LC-like with high langerin, Birbeck granules, EpCAM, and E-cadherin expression under the same conditions. These data highlight a new potential precursor function of CD1c+ DCs and demonstrate an alternative pathway of LC differentiation that may have relevance in vivo.

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 100ng/ml TNF-alpha or 50ng/ml IL-17 or a combination of both cytokines. Samples were harvested 24 and 48h 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/mm2 of living epidermis after 24 and 48h 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 48h, 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.

Role of langerin-positive and CD83+ cells in the pathogenesis of mycosis fungoides

Dendritic cells regulate the balance between the immune response and immunotolerance; their role in the pathogenesis of skin lymphomas is underexplored. Goal. To study the number of populations of CD83+ and langerin positive cells in the skin of patients suffering from mycosis fungoides and small plaque parapsoriasis. Materials and methods. The authors determined the content of langerin-positive and CD83+ cells by means of immunohistochemistry of skin biopsy samples taken from patients suffering from mycosis fungoides (17 subjects) and small plaque parapsoriasis (6 subjects). The control group comprised 16 healthy people. Results. The study revealed that langerin positive and CD83+ dendritic cells prevailed in patients suffering from mycosis fungoides as compared to patients with small plaque parapsoriasis and healthy subjects. The share of immature dendritic cells grows in patients with parapsoriasis and mycosis fungoides. Conclusion. The statistically reliable difference between the amount of langerin positive and CD83+ dendritic cells as well as immature to mature dendritic cells ratio in case of mycosis fungoides vs. small plaque parapsoriasis can serve as an additional diagnostics criterion for these diseases.

Fascin-expressing Dendritic Cells Dominate in Polymyositis and Dermatomyositis

Dendritic cells (DC) have been reported among inflammatory infiltrating cells in muscle tissue in idiopathic inflammatory myopathies (IIM), but to our knowledge no studies concerning the expression of langerin (CD207) or fascin (markers of immature and mature DC, respectively) in IIM have been published. Immunohistochemical analyses of langerin and fascin expression were performed on specimens from normal muscles, as well as those affected by polymyositis (PM) and dermatomyositis (DM). The results were analyzed by Mann-Whitney U test. In PM and DM, fascin-positive cells were numerous in the majority of the studied samples in perimysial, endomysial, and perivascular cellular infiltrates. Sporadic langerin-positive cells were detected. Fascin-positive DC predominance in inflammatory infiltrates in myositic muscles confirms the prevalence of mature forms and indicates that there are conditions stimulating DC maturation in both PM and DM. The induction of immunological tolerance by inhibiting DC maturation may be a promising direction for studies of myositis treatment.

Ontogeny and disease responses of Langerhans-like cells in lymphoid tissues of salmonid fish

The ontogeny and disease responses of Langerhans-like cells within lymphoid tissues of Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, were investigated. These cells were studied in situ with the use of two markers: the ultrastructural presence of Birbeck-like granules and immunohistochemistry with an antibody against human langerin/CD207 that cross-reacts with salmonid tissues. The appearance of Birbeck-like granules was observed in rainbow trout at 2 weeks post-hatch (PH) in the thymus and anterior kidney prior to the development of the spleen. Spleen first appeared at 3 weeks PH in both Atlantic salmon and rainbow trout, and Birbeck-like granules were observed within cells of the newly developed spleens. The cross-reactivity of langerin as seen by immunohistochemistry was not clearly observed in kidney and spleen until 9 weeks PH, when a strong cytoplasmic reaction was observed. To study langerin-positive cells in spleen and kidney during disease, microsporidial gill disease (MGD) in rainbow trout was used as a known disease model inducing a strong cell-mediated adaptive immune response. Langerin-positive cells in healthy fish were seen predominantly in the spleen, and only low numbers were present in the anterior kidney. During MGD, langerin-positive cell numbers were elevated in the anterior kidney and were significantly higher during 5, 6, and 10 weeks post-exposure (PE) compared with healthy control tissue. During MGD, the distribution of langerin-positive cells in the spleen and anterior kidney shifted from having significantly higher numbers of cells in the spleen than in the kidney in controls and at 1 and 4 weeks PE to having a similar distribution of the cells in the two organs at 2, 3, 5, and 6 weeks PE. By 10 weeks PE, significantly higher numbers of langerin-positive cells occurred in the anterior kidney compared with the spleen.

Integration of Langerhans-like cells into a human skin equivalent

Studies regarding cellular interactions between Langerhans cells and other skin cells are somehow hampered by the difficult cultivation of these cells in vitro. Here, we show that the human MUTZ-3 cell line can be differentiated into Langerhans-like cells in the presence of a cytokine cocktail including GM-CSF, TGF-β1 and TNF-α. We used the expression of langerin, CD1a, CCR6 and the intracellular presence of Birbeck granules to identify the differentiated MUTZ-3 cells (MUTZ-3-LCs). The aim of this study was to integrate MUTZ-3-LCs into a three-dimensional full-thickness skin model. On top of fibroblast-containing collagen matrix a mixture of primary human keratinocytes and MUTZ-3-LCs were seeded and cultured for 24h. Subsequently, the models were lifted up to the air-liquid interface. Histological evaluation featured a fully stratified epidermis with all characteristic epidermal strata. Langerin-positive cells were detected suprabasally within the epidermis indicating that keratinocytes provide environmental conditions for long-time maintenance of MUTZ-3-LCs. These skin models provide a tool to further investigate the interactions between Langerhans-like cells and other skin cells and particularly learn more about the cutaneous immune response.

Compartment specific expression of dendritic cell markers in human glomerulonephritis

Macrophages and dendritic cells are heterogenous and highly plastic bone marrow-derived cells that play major roles in renal diseases. We characterized these cells using immunohistochemistry in 55 renal biopsies from control patients or patients with glomerulonephritis as an initial step towards postulating specific roles for these cells in kidney disease. In proliferative glomerulonephritis numerous CD68 positive (pan monocyte, macrophage and dendritic marker) cells were found in both glomeruli and the tubulointerstitial space, however, a myeloid dendritic cell marker (DC-SIGN) was identified only in the tubulointerstitium. A significant number of plasmacytoid dendritic cells (identified as BDCA-2 positive cells) were seen at sites of interstitial inflammation, including follicular aggregates of inflammatory cells. Langerin positive cells (a marker of Langerhans' cells) were detectable but rare. The area of either CD68 or DC-SIGN positive interstitial cells correlated with serum creatinine. Low levels of DC-SIGN, DC-LAMP and MHC class II mRNA were present in the tubulointerstitial space in controls and increased only in that region in proliferative glomerulonephritis. We demonstrate that the CD68 positive cells infiltrating the glomerulus lack dendritic cell markers (reflecting macrophages), whereas in the tubulointerstitial space the majority of CD68 positive cells are also DC-SIGN positive (reflecting myeloid dendritic cells). Their number correlated with serum creatinine, which further emphasizes the significance of interstitial DCs in progressive glomerular diseases.

Homeostasis of Human Langerhans Cells after Allogeneic Hematopoietic Stem Cell Transplantation.

Langerhans cells (LCs) are bone marrow (BM) derived epidermal dendritic cells that represent a critical immunological barrier to the external environment, but little is known about their life cycle. We have recently discovered that in mice, LCs are maintained by local radio-resistant LC precursors that self-renew in quiescent skin throughout life but are replaced by circulating precursors upon inflammation (Merad et al. 2002). We have also shown that host radio-resistant LCs that persist after allogeneic HSCT play a major role in initiating skin GVHD (Merad et al. 2004). To explore the turnover of human LCs, we first asked whether human LCs are maintained by local LC precursors in quiescent skin of patients that have undergone HSCT. We assessed LC turnover from skin biopsies of recipients of sex-mismatched grafts and used X and Y chromosomes as a marker of host or donor origin. Patients skin samples were subjected to fluorescence in situ hybridization using X and Y specific DNA probes followed by immunofluorescence staining of Langerin (a LC specific marker) and nuclei staining. X and Y chromosomes were simultaneously visualized within the nuclei of Langerin-positive cells with high-resolution four-color microscopy. In a preliminary study, we found that in 7 patients with histological signs of skin GVHD, 98+3.4% of LCs were of donor origin. In contrast, in 2 patients that had no histological signs of GVHD, 100% LCs remained of host origin at 9 months and 4 years after myeloablative conditioning and HSCT despite 100% BM chimerism. These data suggest that in the absence of skin inflammation host LCs can persist in the skin for a long time despite complete donor hematopoietic engraftment. Next, we hypothesized that host LCs can persist in the skin because they are radio-resistant and able to proliferate in situ. Indeed, cell cycle analysis of purified LCs and co-staining of skin sections with Ki-67 and Langerin antibodies revealed that 2% of epidermal LCs present in quiescent human skin proliferate in situ, a percentage similar to that found in mice. To follow the behavior of human LCs experimentally, we reconstituted γ-irradiated Rag2 −/−γc−/− newborns mice with human CD34+ cord blood cells to engraft human hemato-lymphopoiesis. Engrafted animals developed functional human B cells, T cells and dendritic cells in the blood and spleen together with structured primary and secondary lymphoid organs. Consistent with our findings in patients, no human LCs were detected in the skin in steady state conditions, despite high levels of human hematopoietic cell engraftment. These results suggest that human LCs are maintained by a local pool of radio-resistant LC precursors that self-renew in situ. Since local LC precursors are eliminated during severe skin injuries, this xeno-transplantation model will be useful to dissect the homing molecules that govern the recruitment of LCs from the blood to the skin and may help develop new therapeutic strategies for the prevention and treatment of clinical GVHD.