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The adult human skin harbors a variety of leukocytes providing immune surveillance and host defense, but knowledge about their ontogeny is scarce. In this study we investigated the number and phenotype of leukocytes in prenatal human skin (dermal dendritic cells (DDCs), macrophages, T cells (including FoxP3(+) regulatory T cells), and mast cells) to unravel their derivation and to get a clue as to their putative function in utero. By flow cytometry and immunofluorescence, we found a distinction between CD206(+)CD1c(+)CD11c(+) DDCs and CD206(+)CD209(+)CD1c(-) skin macrophages by 9 weeks estimated gestational age (EGA). T cells appear at the end of the first trimester, expressing CD3 intracytoplasmatically. During midgestation, CD3(+)FoxP3(-) and CD3(+)FoxP3(+) cells can exclusively be found in the dermis. Similarly, other leukocytes such as CD117(+) (c-kit) mast cells were not identified before 12-14 weeks EGA and only slowly acquire a mature phenotype during gestation. Our data show at which time point during gestation antigen-presenting cells, T cells, and mast cells populate the human dermis and provide a step forward to a better understanding of the development of the human skin immune system.

Lymphatic vessels transport interstitial fluid, soluble Ag, and immune cells from peripheral tissues to lymph nodes (LNs), yet the contribution of peripheral lymphatic drainage to adaptive immunity remains poorly understood. We examined immune responses to dermal vaccination and contact hypersensitivity (CHS) challenge in K14-VEGFR-3-Ig mice, which lack dermal lymphatic capillaries and experience markedly depressed transport of solutes and dendritic cells from the skin to draining LNs. In response to dermal immunization, K14-VEGFR-3-Ig mice produced lower Ab titers. In contrast, although delayed, T cell responses were robust after 21 d, including high levels of Ag-specific CD8+ T cells and production of IFN-γ, IL-4, and IL-10 upon restimulation. T cell-mediated CHS responses were strong in K14-VEGFR-3-Ig mice, but importantly, their ability to induce CHS tolerance in the skin was impaired. In addition, 1-y-old mice displayed multiple signs of autoimmunity. These data suggest that lymphatic drainage plays more important roles in regulating humoral immunity and peripheral tolerance than in effector T cell immunity.

Effector T cells are critical for clearance of pathogens from sites of infection. Like cytotoxic CD8(+) T cells, CD4(+) helper T cells have been shown to deliver effector molecules directionally toward the immunological synapse, suggesting that infected cells need to be engaged individually to receive effector signals. In contrast, we show here that CD4(+) T cells stably contacted a minority of infected cells, yet these interactions triggered intracellular defense mechanisms in bystander cells in vivo. By using a functional read-out, we provide evidence that this effector bystander activity extends via a gradient of IFN-γ more than 80 μm beyond the site of antigen presentation, promoting pathogen clearance in the absence of immunological synapse formation. Our results thus demonstrate that CD4(+) T cells can exert their protective activity by engaging a minority of infected cells., (Copyright © 2012 Elsevier Inc. All rights reserved.)

S100A8 and S100A9 are members of the S100A8 protein family that exist as homodimers and heterodimers in neutrophils, monocytes, and macrophages. Recent studies have shown the pivotal roles of S100A8 and S100A9 in the propagation of inflammation and keratinocyte proliferation in psoriasis. We found significant up-regulation of S100A8 and S100A9 secretion from keratinocytes in psoriatic lesions. To mimic the in vivo secretory conditions of S100A8 and S100A9 from psoriatic epidermal keratinocytes, we used the culture medium (CM) of S100A8 and S100A8/A9 adenovirus-transduced keratinocytes to investigate the functions of S100A8 and S100A9. We detected increased levels of various pro-inflammatory cytokines in the CM, including IL-8 and TNF-α, which are involved in aggravating psoriatic skin lesions, and IL-6 and members of the CXCL family of pro-angiogenic cytokines. The CM increased immune cell migration and increased angiogenesis in human umbilical vein endothelial cells. In conclusion, we found that the upregulated production of S100A8 and S100A9 by psoriatic epidermal keratinocytes activated adjacent keratinocytes to produce several cytokines. Moreover, S100A8 and S100A9 themselves function as pro-angiogenic and chemotactic factors, generating a psoriatic milieu in skin., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Psoriasis vulgaris is a complex disease characterized by alterations in growth and differentiation of epidermal keratinocytes, as well as a marked increase in leukocyte populations. Lesions are known to contain alterations in messenger RNAs encoding more than 1,000 products, but only a very small number of these transcripts has been localized to specific cell types or skin regions. In this study, we used laser capture microdissection (LCM) and gene array analysis to study the gene expression of cells in lesional epidermis (EPI) and dermis, compared with the corresponding non-lesional regions. Using this approach, we detected >1,800 differentially expressed gene products in the EPI or dermis of psoriasis lesions. These results established sets of genes that are differentially expressed between epidermal and dermal compartments, as well as between non-lesional and lesional psoriasis skin. One of our findings involved the local production of CCL19, a lymphoid-organizing chemokine, and its receptor CCR7 in psoriatic dermal aggregates, along with the presence of gene products LAMP3/DC-LAMP and CD83, which typify mature dendritic cells (DCs). Gene expression patterns obtained with LCM and microarray analysis along with T-cell and DC detection by immune staining suggest a possible mechanism for lymphoid organization via CCL19/CCR7 in diseased skin.

Under homeostatic conditions, skin DCs migrate to regional LNs transporting self-antigens (self-Ags). The transport of self-Ags is considered to be critical for maintaining peripheral tolerance. Although the chemokine receptor CCR7 potently induces the migration of skin DCs to regional LNs, Ccr7(-/-) (Ccr7-KO) mice do not show skin auto-immune diseases. To resolve this inconsistency, we examined Ccr7-KO epidermis- or dermis-hyperpigmented transgenic (Tg) mice, in which the transport of skin self-Ags is traceable by melanin granules (MGs). Under CCR7-deficient conditions, the transport of epidermal MGs to regional LNs was impaired at 7 weeks of age. However, epidermal MGs could be transported when they had accumulated in the dermis. Ccr7-KO-dermis-pigmented Tg mice confirmed the presence of CCR7-independent transport from the dermis. Compared with WT-dermis-pigmented Tg mice, the amount of transported melanin and number of MG-laden CD11c(+) cells were both approximately 40% of the WT levels, while the number of MG-laden CD205(+) or CD207(+) cells decreased to about 10% in skin regional LNs of Ccr7-KO-dermis-pigmented Tg mice. Cell sorting highlighted the involvement of CD11c(+) cells in the CCR7-independent transport. Here, we show that CCR7-independent transport of skin self-Ags occurs in the dermis. This system might contribute to the continuous transport of self-Ags, and maintain peripheral tolerance., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Biologic scaffold materials composed of extracellular matrix (ECM) have been shown to promote the formation of site-specific, functional, host tissue following placement in a number of preclinical and clinical studies. Endotoxin contamination of biomaterials is thought to result in deleterious immune responses that may affect the remodeling outcome when present in significant quantities. However, the exact amount of endotoxin contamination within or upon an ECM-based biologic scaffold that is required to elicit adverse effects in recipients is currently unknown. The present study examined the in vitro and in vivo effects of endotoxin contamination within an ECM scaffold derived from porcine dermis upon the host immune response and the downstream ability of the scaffold material to promote constructive tissue remodeling. Test articles with endotoxin values that exceed the current U.S. Food and Drug Administration (FDA) limit had similar or decreased immune responses both in vitro and in vivo when compared with devices that were below the current FDA limit. Dermal matrices spiked with large doses of endotoxin (100 ng/mL), equivalent to 10-20 times the FDA limit, elicited a robust immune response in vitro. However, by 35 days postimplantation, no difference in tissue remodeling was detected, regardless of the amount of endotoxin present within the material. These results suggest that current endotoxin standards may fall well below levels that induce an adverse acute proinflammatory response and associated long-term deleterious effects upon tissue remodeling outcomes.

Granuloma annulare (GA) is characterized histopathologically by 3 patterns: necrobiotic granuloma, interstitial incomplete form and, rarely, sarcoidal or tuberculoid granuloma. The amount of lymphoid infiltrate in GA is usually limited. We describe 10 cases of GA with prominent "pseudolymphomatous" lymphoid infiltrates mimicking cutaneous lymphoid hyperplasia. Patients were 6 males and 4 females (mean age 49.9 years, median age 47 years, age range 25-70). Lesions were localized to a limited area of the body (n = 6), or involved the entire trunk (n = 3), or were generalized (n = 1). The correct clinical diagnosis of GA was provided only in 30% of the cases. In all cases, histopathologic features were characterized by dense, nodular, superficial, and deep infiltrates of lymphocytes. Immunohistology revealed predominance of T lymphocytes in 7 of 7 tested cases. This "pseudolymphomatous" variant of GA represents a pitfall in the histopathologic diagnosis of the disease and may be misinterpreted as other types of cutaneous lymphoproliferative disorders.

NK cells infiltrate human herpetic lesions, but their role has been underexplored. HSV can stimulate innate immune responses via surface TLR2, which is expressed on monocyte-derived dendritic cells (DCs) and NK cells. In this study, UV-inactivated HSV1/2 and immunodominant HSV2 glycoprotein D peptides conjugated to the TLR2 agonist dipalmitoyl-S-glyceryl cysteine stimulated CD4 T lymphocyte IFN-γ responses within PBMCs or in coculture with monocyte-derived DCs. NK cells contributed markedly to the PBMC responses. Furthermore, NK cells alone were activated directly by both Ags, also upregulating HLA-DR and HLA-DQ and then they activated autologous CD4 T lymphocytes. Using Transwells, Ag-stimulated NK cells and CD4 T lymphocytes were shown to interact through both cell-to-cell contact and cytokines, differing in relative importance in different donors. A distinct immunological synapse between Ag-stimulated NK cells and CD4 T lymphocytes was observed, indicating the significance of their cell-to-cell contact. A large proportion (57%) of NK cells was also in contact with CD4 T lymphocytes in the dermal infiltrate of human recurrent herpetic lesions. Thus, NK cells stimulated by TLR2-activating HSV Ags can present Ag alone or augment the role of DCs in vitro and perhaps in herpetic lesions or draining lymph nodes. In addition to DCs, NK cells should be considered as targets for adjuvants during HSV vaccine development.

Epidermolysis bullosa acquisita (EBA) is a chronic mucocutaneous autoimmune skin blistering disease. Several lines of evidence underscore the contribution of autoantibodies against type VII collagen (COL7) to the pathogenesis of EBA. Furthermore, EBA susceptibility is associated with the MHC haplotype in patients (HLA-DR2) and in immunization-induced EBA in mice (H2s). The latter study indicated an additional contribution of non-MHC genes to disease susceptibility. To identify non-MHC genes controlling EBA susceptibility, we intercrossed EBA-susceptible MRL/MpJ with EBA-resistant NZM2410/J and BXD2/TyJ as well as Cast mice. Mice of the fourth generation of this four-way autoimmune-prone advanced intercross line were immunized with a fragment of murine COL7 to induce EBA. Anti-COL7 autoantibodies were detected in 84% of mice, whereas deposition of complement at the dermal-epidermal junction (DEJ) was observed in 50% of the animals; 33% of immunized mice presented with overt clinical EBA. Onset of clinical disease was associated with several quantitative trait loci (QTLs) located on chromosomes 9, 12, 14, and 19, whereas maximum disease severity was linked to QTLs on chromosomes 1, 15, and 19. This more detailed insight into the pathogenesis of EBA may eventually lead to new treatment strategies for EBA and other autoantibody-mediated diseases.

Aims: This study aims to investigate the mechanisms in the apparent preference for mitogen-activated protein kinase /ERK signaling through interleukin (IL)-6R in dermal fibroblasts., Methods: Dermal fibroblasts isolated from IL-6KO mice were pretreated with specific ERK or STAT3 chemical inhibitors or SOCS3 specific siRNA and treated with rmIL-6. Phosphorylation was monitored via enzyme-linked immunosorbent assay or immunohistology. SOCS3 interaction with p120Ras-Gap was examined by co-immunoprecipitation and Western blot. Expression of MMP2 mRNA was assessed via real-time quantitative polymerase chain reaction., Results: A dose response phosphorylation of ERK1/2 occurred while no STAT3 activation (p-Tyr705) was induced after IL-6 treatment, despite an increase in Ser727 phosphorylation. Inhibition of STAT3 in fibroblasts potentiated IL-6R induced ERK phosphorylation and vice versa. Phosphorylated SOCS3 and p120 RasGAP co-immunoprecipitated in response to IL-6 treatment. SOCS3 siRNA knockdown allowed STAT3 phosphorylation after rmIL-6 treatment. Chemical inhibition of IL-6R signaling altered the IL-6 modulated mRNA expression of MMP-2., Conclusions: SOCS3 interaction with p120 Ras-Gap plays a role in determining the preference for IL-6R signaling through ERK in dermal fibroblasts. This study provides insight into the pleiotropic nature of IL-6 and the selective signaling mechanism elicited by the IL-6R system in dermal fibroblasts. It may further indicate a method for manipulation of IL-6R function.

Atopic dermatitis (AD) skin lesions exhibit epidermal and dermal thickening, eosinophil infiltration, and increased levels of the cysteinyl leukotriene (cys-LT) leukotriene C(4) (LTC(4)). Epicutaneous sensitization with ovalbumin of WT mice but not ΔdblGATA mice, the latter of which lack eosinophils, caused skin thickening, collagen deposition, and increased mRNA expression of the cys-LT generating enzyme LTC(4) synthase (LTC(4)S). Skin thickening and collagen deposition were significantly reduced in ovalbumin-sensitized skin of LTC(4)S-deficient and type 2 cys-LT receptor (CysLT(2)R)-deficient mice but not type 1 cys-LT receptor (CysLT(1)R)-deficient mice. Adoptive transfer of bone marrow-derived eosinophils from WT but not LTC(4)S-deficient mice restored skin thickening and collagen deposition in epicutaneous-sensitized skin of ΔdblGATA recipients. LTC(4) stimulation caused increased collagen synthesis by human skin fibroblasts, which was blocked by CysLT(2)R antagonism but not CysLT(1)R antagonism. Furthermore, LTC(4) stimulated skin fibroblasts to secrete factors that elicit keratinocyte proliferation. These findings establish a role for eosinophil-derived cys-LTs and the CysLT(2)R in the hyperkeratosis and fibrosis of allergic skin inflammation. Strategies that block eosinophil infiltration, cys-LT production, or the CysLT(2)R might be useful in the treatment of AD.

Understanding how pathogens or vaccine antigens are targeted to dendritic cell (DC) subsets is important for disease pathogenesis studies and vaccine design. We characterised the sub-populations of migrating bovine DC with functional and phenotypic diversity present in pseudoafferent lymph draining the skin. These skin draining DC exist as a series of maturation dependent subsets with differential capacities for antigen uptake and cytokine expression, and include both Langerhans' cells (LC) and dermal derived cells. Furthermore, Mycobacterium bovis Bacille Calmette Guerin, a vaccine which is administered by the intradermal route, was only taken up by a small number of the migrating DC, which were SIRPα(+) and expressed the mannose receptor and CD1b. This was evident following in vitro infection and also in vivo following inoculation of green fluorescent BCG over the lymphatic cannulation site. Only the SIRPα(+) DC were able to present antigen to T cells isolated from BCG vaccinated calves. Furthermore, presentation of BCG antigens by DC to T lymphocytes was ineffective compared to mycobacterial proteins. However, mycobacterial antigen 85 was delivered more effectively to DC via an adenoviral vector and the magnitude of the subsequent antigen-specific T cell response was significantly increased. This study further extends our understanding of the biology of migrating DC, identifies potential explanations for the modest success of BCG vaccination and demonstrates that targeted delivery of antigens via adenoviruses to DC can improve antigen presentation., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Vulvar lichen sclerosus and lichen planus are T-cell-mediated chronic skin disorders. Although autoimmunity has been suggested, the exact pathogenesis of these disorders is still unknown. Therefore, the aim of the current study was to investigate the molecular and immunological mechanisms critical to the pathogenesis of vulvar lichen sclerosus and lichen planus. By using gene expression profiling and real-time RT-PCR experiments, we demonstrated a significantly increased expression of the pro-inflammatory cytokines (IFNγ, CXCR3, CXCL9, CXCL10, CXCL11, CCR5, CCL4, and CCL5) specific for a Th1 IFNγ-induced immune response. In addition, BIC/microRNA-155 (miR-155)--a microRNA involved in regulation of the immune response--was significantly upregulated in lichen sclerosus and lichen planus (9.5- and 17.7-fold change, respectively). Immunohistochemistry showed a significant T-cell response, with pronounced dermal infiltrates of CD4(+), CD8(+), and FOXP3(+) cells. In conclusion, these data demonstrate an autoimmune phenotype in vulvar lichen sclerosus and lichen planus, characterized by increased levels of Th1-specific cytokines, a dense T-cell infiltrate, and enhanced BIC/miR-155 expression.

Complete surgical excision at an early stage remains the only curative treatment for cutaneous melanoma with few available adjuvant therapy options. Nevertheless, melanoma is a relatively immunogenic tumor type and particularly amenable to immunotherapeutic approaches. A dense network of cutaneous dendritic cells (DC) may account for the reported efficacy of vaccination through the skin and provide an attractive target for the immunotherapy of melanoma. Several phenotypically distinct DC subsets are discernable in the skin, among others, epidermal Langerhans cells and dermal DC. Upon appropriate activation both subsets can efficiently migrate to melanoma-draining lymph nodes (LN) to prime T cell-mediated responses. Unfortunately, from an early stage, melanoma development is characterized by strong immune suppression, facilitating unchecked tumor growth and spread. Particularly the primary tumor site and the first-line tumor-draining LN, the so-called sentinel LN, bear the brunt of this melanoma-induced immune suppression-and these are exactly the sites where anti-melanoma effector T cell responses should be primed by DC in order to prevent early metastasis. Through local immunopotentiation or through DC-targeted vaccination, the dermis may be utilized as a portal to activate DC and kick-start or boost effective T cell-mediated anti-melanoma immunity, even in the face of this immune suppression.

The presence of one autoimmune disorder helps lead to the discovery of other autoimmune conditions. It is thought that diseases in which autoimmunity is a feature tend to be associated together more often than one can ascribe to chance. A variety of diseases have been implicated in the onset of intraepidermal and subepidermal autoimmune diseases. The presence of one autoimmune disease should alert the physician to watch for a second immunologic disorder. A list of autoimmune bullous diseases associations includes autoimmune bullous diseases, pemphigus, pemphigoid, epidermolysis bullosa acquisita, dermatitis herpetiformis (Duhring), linear immunoglobulin A disease, and multiple autoimmune syndrome., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Dendritic cells (DCs) form a heterogeneous group of antigen presenting cells that play different roles in tissue immunity. Recent studies have revealed the presence of distinct DC populations in murine skin, highlighting the complexity of the cutaneous DC network. In this review, we will define the major DC subsets that populate the different layers of the skin, focusing on their origin and the mechanisms controlling their homeostasis. We will also review recent evidence underlining the functional specialization of dermal DC subsets and its relevance in the design of novel vaccine approaches.

Hyaluronan (HA) is an abundant matrix molecule, the function of which in the skin remains to be fully defined. To explore the roles of HA in cutaneous injury responses, double-knockout mice (abbreviated as Has1/3 null) that lack two HA synthase enzymes (Has1 and Has3), but still express functional Has2, were used in two types of experiments: (i) application of 12-O-tetradecanoylphorbol-13-acetate (TPA) and (ii) full-thickness wounding of the skin. Uninjured Has1/3-null mice were phenotypically normal. However, after TPA, the accumulation of HA that normally occurs in wild-type epidermis was blunted in Has1/3-null epidermis. In excisional wound-healing experiments, wound closure was significantly faster in Has1/3 null than in wild-type mice. Coincident with this abnormal wound healing, a marked decrease in epidermal and dermal HA and a marked increase in neutrophil efflux from cutaneous blood vessels were observed in Has1/3-null skin relative to wild-type skin. Has1/3-null wounds displayed an earlier onset of myofibroblast differentiation. In summary, selective loss of Has1 and Has3 leads to a proinflammatory milieu that favors recruitment of neutrophils and other inflammation-related changes in the dermis.

The viral infections yellow fever and influenza can lead to large epidemics, which may deplete limited vaccine supplies. The intradermal vaccination route of yellow fever and influenza vaccines has received renewed attention, because it allows dose reduction without loss of efficacy. In this chapter, we review these two vaccines, the history of vaccine development, correlates of protection, immune response to vaccination and current knowledge concerning intradermal vaccination, including the immunological background, both in healthy subjects and immunocompromized individuals.

Vaccinations in medicine are typically administered into the muscle beneath the skin or into the subcutaneous fat. As a consequence, the vaccine is immunologically processed by antigen-presenting cells of the skin or the muscle. Recent evidence suggests that the clinically seldom used intradermal route is effective and possibly even superior to the conventional subcutaneous or intramuscular route. Several types of professional antigen-presenting cells inhabit the healthy skin. Epidermal Langerhans cells (CD207/langerin(+)), dermal langerin(neg), and dermal langerin(+) dendritic cells (DC) have been described, the latter subset so far only in mouse skin. In human skin langerin(neg) dermal DC can be further classified based on their reciprocal expression of CD1a and CD14. The relative contributions of these subsets to the generation of immunity or tolerance are still unclear. Yet, specializations of these different populations have become apparent. Langerhans cells in human skin appear to be specialized for induction of cytotoxic T lymphocytes; human CD14(+) dermal DC can promote antibody production by B cells. It is currently attempted to rationally devise and improve vaccines by harnessing such specific properties of skin DC. This could be achieved by specifically targeting functionally diverse skin DC subsets. We discuss here advances in our knowledge on the immunological properties of skin DC and strategies to significantly improve the outcome of vaccinations by applying this knowledge.

Dendritic cells (DCs) have the ability to present antigen and play a critical role in the induction of the acquired immune response. Skin DCs uptake antigen and subsequently migrate to regional draining lymph nodes (LNs), where they activate naive T cells. Here we show that the water/glycerol channel protein aquaporin 7 (AQP7) is expressed on epidermal and dermal DCs and involved in the initiation of primary immune responses. AQP7-deficient DCs showed a decreased cellular uptake of low-molecular-mass compounds (fluorescein isothiocyanate and Lucifer yellow) and high-molecular-mass substances (ovalbumin and dextran), suggesting that AQP7 is involved in antigen uptake. AQP7-deficient DCs also exhibited reduced chemokine-dependent cell migration in comparison to wild-type DCs. Consistent with these in vitro results, AQP7-deficient mice demonstrated a reduced accumulation of antigen-retaining DCs in the LNs after antigen application to the skin, which could be attributed to decreased antigen uptake and migration. Coincidentally, AQP7-deficient mice had impaired antigen-induced sensitization in a contact hypersensitivity model. These observations suggested that AQP7 in skin DCs is primarily involved in antigen uptake and in the subsequent migration of DCs and is responsible for antigen presentation and the promotion of downstream immune responses.

Recently, the C-terminus of laminin γ1 has been identified as target antigen in anti-p200 pemphigoid and the disease was renamed as anti-laminin γ1 pemphigoid. However, the pathogenic relevance of these autoantibodies has not yet been demonstrated. Therefore, we employed an ex vivo model of autoantibody-mediated leukocyte-dependent neutrophil activation and dermal-epidermal separation (DES) using cryosections of human skin. We showed that anti-p200 pemphigoid sera (n = 7) induced DES in a time-dependent manner, in contrast to sera from healthy controls. Furthermore, laminin γ1-specific IgG and serum depleted from anti-laminin γ1 reactivity were generated using the recombinant C-terminus of laminin γ1 (LAMC1-term; amino acids 1364 to 1609). Interestingly, both fractions labeled the dermal-epidermal-junction (DEJ) by indirect immunofluorescence microscopy on human foreskin and recognized a 200 kDa protein by immunoblotting with dermal extract. Human and rabbit IgG against LAMC1-cterm failed to attract neutrophils at the DEJ and to induce DES. In contrast, patient serum depleted from LAMC1-cterm reactivity led to the same extent of DES as non-depleted IgG. Repeated injection of rabbit anti-murine LAMC1-cterm IgG into both neonatal and adult C57BL/6mice as well as repetitive immunization of various mouse strains with murine LAMC1-cterm failed to induce macro- and microscopic lesions. In all mice, circulating anti-LAMC1-cterm antibodies were present, but only in some mice, IgG deposits were seen at the DEJ. We conclude that autoantibodies in anti-p200 pemphigoid sera are pathogenic while pathogenicity is not mediated by autoantibodies against laminin γ1. Further studies are needed to identify the pathogenically relevant autoantigen in anti-p200 pemphigoid.

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., epidermal Langerhans cells (LCs), dermal CD1c(+)CD14(-) and CD14(+) DCs (DDCs). DCs were purified following a 2-day migration from separated epidermal and dermal sheets and co-cultured with allogeneic T cells before cytokine secretion was explored. Results showed that no skin DCs could induce substantial IL-17 production by naïve CD4(+) or CD8(+)T lymphocytes whereas all of them could induce IL-17 production by memory T cells. In contrast, LCs and CD1c(+)CD14(-)DDCs were able to differentiate naïve CD4(+)T lymphocytes into IL-22 and IL-21-secreting cells, LCs being the most efficient in this process. Intracellular cytokine staining showed that the majority of IL-21 or IL-22 secreting CD4(+)T lymphocytes did not co-synthesized IFN-γ, IL-4 or IL-17. IL-21 and IL-22 production were dependent on the B7/CD28 co-stimulatory pathway and ICOS-L expression on skin LCs significantly reduced IL-21 level. Finally, we found that TGF-β strongly down-regulates both IL-21 and IL-22 secretion by allogeneic CD4(+) T cells. These results add new knowledge on the functional specialization of human skin DCs and might suggest new targets in the treatment of inflammatory skin disorders.

Reciprocal communication between hematopoietic cells and their surrounding bone marrow stroma is crucial for normal progression of hematopoiesis. This complex network of cell-to-cell signals in the microenvironment involves both cell contact-mediated and paracrine cues. In hematological malignancies the intricate balance is, however, disrupted to support cancer progression. In order to detect altered microenvironmental reactivity of a hematopoietic cell sample, cellular functional assays can be designed to measure the cells' capacity to modulate stromal stress reactions, such as inflammation.Recently, we showed that human leukemic cell lines of monocytic origin can actively participate in modulation of stromal inflammation. In order to further functionally evaluate the hematopoietic cells' capacity to modulate stromal inflammation, we utilized an in vitro model of nemosis-induced inflammation of fibroblasts in a three-dimensional culture setting. This process of stromal inflammation in fibroblast aggregates is consistent, requires both cell-contact and paracrine signals, and can be produced on a large scale to support dose-dependent analyses. To extend our previous observations, we evaluated the effect of a wide panel of leukemia cell lines on cyclooxygenase- 2 induction in fibroblast aggregates in co-culture. We also assessed the feasibility of the model to support clinical functional testing by utilizing the hematopoietic fraction of leukemia patients' bone marrow aspirates after immunophenotyping. Our results suggest that the stromal inflammation-modulating activity of these samples is differently modulated in cancer and in normal bone marrow. Moreover, differences in the samples' anti-inflammatory activity may reflect disease state.

Over the past two decades, DNA vaccination has been developed as a method for the induction of immune responses. However, in spite of high expectations based on their efficacy in preclinical models, immunogenicity of first generation DNA vaccines in clinical trials was shown to be poor, and no DNA vaccines have yet been licensed for human use. In recent years significant progress has been made in the development of second generation DNA vaccines and DNA vaccine delivery methods. Here we review the key characteristics of DNA vaccines as compared to other vaccine platforms, and recent insights into the prerequisites for induction of immune responses by DNA vaccines will be discussed. We illustrate the development of second generation DNA vaccines with the description of DNA tattooing as a novel DNA delivery method. This technique has shown great promise both in a small animal model and in non-human primates and is currently under clinical evaluation.

Background: Previous reports have shown that indirect immunofluorescence (IIF) performed on sodium chloride-split skin (SSS) is helpful to differentiate epidermolysis bullosa acquisita (EBA) from bullous pemphigoid (BP). Antibodies of BP may bind to the epidermal side of SSS, while antibodies of EBA bind to the dermal side., Aims: To determine the accuracy of IIF-SSS in the differential diagnosis of EBA and BP utilizing immunoblotting (IB) analysis., Methods: Sera from 78 patients, diagnosed with BP by clinical features, histopathology, and direct immunofluorescence (DIF), were assayed using IIF-SSS and IB., Results: Of the 43 serum samples with an epidermal reaction to IIF-SSS assay, 42 were recognized with BP antigens (180 kDa or 230 kDa). Of the 11 serum samples with a dermal reaction pattern, 7 were recognized with the 290 kDa antigen of EBA and 3 with sera bound BP antigens. Seven serum samples with epidermal and dermal combined staining, of which 5 of them reacted with BP antigens, 1 reacted with both BP and EBA antigens. One serum sample from each group showed a negative result by IB. Approximately 9.0% (7/78) of patients diagnosed with BP using regular methods were actually EBA., Conclusions: Epidermal reaction using the IIF-SSS assay highly correlated with the diagnosis of BP. However, dermal reactions correlated poorly with EBA, with some serum samples from BP patients binding to dermal-side antigens. In both epidermal and dermal stained sera using IIF-SSS, there was a possibility of BP and EBA. Differential diagnosis should be confirmed using IB, especially in cases of dermal and double staining patterns assayed using IIF-SSS.

Langerhans cells are identified by the expression of langerin. We detected this molecule in cutaneous and mucosal lesions in paracoccidioidomycosis, an important infection in Latin America. Langerin+ cells were scarcely distributed, with short dendrites in epidermis and epithelium and were frequent in the dermis and corium, in the inflammatory infiltrate and granulomas. Mucosal lesions presented a higher expression of langerin in lesions with loose granulomas. For the first time we presented the expression of langerin in paracoccidioidomycosis. Positive cells in dermis and corium could represent migrating Langerhans cells or a new subset of langerin+ cells with a role in paracoccidioidomycosis., (Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Anetoderma is a rare cutaneous disorder where a localized dermal defect of elastic fibers determines depressed areas and often herniated saclike skin. Primary anetoderma is an idiopathic phenomenon while secondary anetoderma is related to various conditions. The term primary anetoderma implies that the lesions occur in clinically normal skin although they may be associated with another dermatological or systemic disease or condition, without a well established relationship. The term secondary anetoderma implies that anetoderma occurred on the same site as another skin lesion. Familial anetoderma is a very rare condition that can be associated with bony, neurological and ocular anomalies. Recently some families with familial anetoderma have been described, where the disease seems to be limited to the skin. The pathogenesis for familial anetoderma is still unclear. It has been reported in only 10 families and in the first 4 reported families, anetoderma was always associated with extra-cutaneous abnormalities, while in the remaining 6 families, all described in last three decades, anetoderma was limited to the skin. We report here another two families with anetoderma without any associated disease and we review the literature on familial anetoderma.

Background: Melanin and melanophages are commonly seen under the basement membrane zone of the skin in patients affected by a new variant of endemic pemphigus foliaceus in El Bagre, Colombia (El Bagre-EPF)., Objective: Our study was conducted to determine the nature of these pigmentary alterations., Methods: We utilized clinical, histopathologic and immunologic techniques including direct and indirect immunofluorescence, immunohistochemistry, Bielschowsky staining and immunoelectron microscopy studies., Results: In the El Bagre-EPF patients, we detected dermal melanin in melanophages and antigen-presenting cells, in close proximity to neural and vascular markers. The melanophages consisted of a mixed population expressing CD68, myeloid/histoid antigen and S-100 protein. By immunoelectron microscopy, the presence of autoantibodies in proximity to melanin granules was confirmed within the melanocytes utilizing 10-nm gold particles., Conclusion: Dermal antigen-presenting cells, including melanophages, seem to contain a diverse combination of molecules, representative of an immunologic process where these cells are engulfing both autoantigens and/or cellular debris in El Bagre-EPF. Autoantibodies to discrete components of melanocytes were also identified; the clinical and immunologic significance of these findings remains unknown. Our work may provide a possible explanation of a darkened complexion in patients affected by endemic pemphigus foliaceus., (2011 John Wiley & Sons A/S.)

Psoriasis is an autoimmune-related chronic inflammatory skin disease that is strongly associated with IL-23 and T helper-17 (Th17) effector cytokines. In addition, CD4+CD25(high) regulatory T-cell (Treg) function appeared to be impaired in psoriasis. CD4+CD25(high)Foxp3+ Tregs are typically considered inhibitors of autoimmune responses. However, under proinflammatory conditions, Tregs can differentiate into inflammation-associated Th17 cells--a paradigm shift, with as yet largely unknown consequences for human disease initiation or progression. Th17 cells are highly proinflammatory T cells that are characterized by IL-17A and IL-22 production and expression of the transcription factor retinoic acid-related orphan receptor γt (RORγt). We here show that Tregs of patients with severe psoriasis, as compared with those of healthy controls, have an enhanced propensity to differentiate into IL-17A-producing cells on ex vivo stimulation. This enhanced Treg differentiation was linked to unexpectedly high RORγt levels and enhanced loss of Foxp3. Notably, IL-23 boosted this Treg differentiation process particularly in patients with psoriasis but less so in controls. IL-23 further reduced Foxp3 expression while leaving the high RORγt levels unaffected. The histone/protein deacetylase inhibitor, Trichostatin-A, prevented Th17 differentiation of Tregs in psoriasis patients. Importantly, IL-17A+/Foxp3+/CD4+ triple-positive cells were present in skin lesions of patients with severe psoriasis. These data stress the clinical relevance of Treg differentiation for the perpetuation of chronic inflammatory disease and may pave novel ways for immunotherapy.

CCL21 expression by lymphatic endothelial cells (LECs) is essential for migration of CCR7+ immune cells from skin to regional lymph nodes (LNs). We investigated the importance of mitogen-activated protein kinase (MAPK) signaling in CCL21 expression by ECs in vitro and in vivo. Normal human dermal lymphatic microvascular ECs (HMVEC-dLy) stimulated in vitro with oncostatin M (OSM) expressed high amounts of CCL21 mRNA. CCL21 protein expression by HMVEC-dLy was also markedly increased by OSM compared with unstimulated cultures. Marked phosphorylation of MAPK 44/42 was detected in HMVEC-dLy stimulated by OSM. CCL21 expression by HMVEC-dLy was blocked by a JAK inhibitor 1, JAK3 inhibitor, and U0126 (a MAPK kinase inhibitor) in vitro, all of which blocked phosphorylation of MAPK 44/42. In addition, injection of U0126 into murine skin significantly decreased CCL21 mRNA and protein expression. Moreover, injection of U0126 before sensitization decreased migration of dendritic cells to draining LNs and decreased contact hypersensitivity responses. In summary, these results suggest that the MAPK pathway is important for CCL21 expression by LECs in vitro and in vivo. Blocking MAPK signaling within skin may offer a novel approach to treatment of inflammatory skin diseases.

An inverse relation between contact allergy and autoimmune diseases is suggested from epidemiological studies. The aim of this study was to investigate susceptibility and reactivity in patients with psoriasis, patients with diabetes and healthy controls in an experimental sensitization study. We sensitized 68 adult individuals (23 patients with psoriasis, 22 patients with diabetes and 23 healthy controls) with diphenylcyclopropenone (DPCP) and assessed challenge responses with visual scoring and ultrasound. Skin biopsies from challenged skin were investigated for differences in down-regulatory mechanisms with immunohistochemistry and gene-expression profiles using microarray technology. The sensitization ratios were 26%, 36% and 65% for the psoriatic, diabetic and healthy groups, respectively. Logistic regression analysis gave an odds ratio (OR) for a patient with psoriasis or diabetes type I of being sensitized to 0·18 [95% confidence interval (CI): 0·039-0·85], P = 0·031 and 0·74 (95% CI: 0·548-1·008), P = 0·056, respectively. A high degree of forkhead box P3-positive (FoxP3(+) ) cells were found in biopsies of positively challenged reactions, but only limited numbers in negatively challenged reactions, with no difference among the groups. No specific mRNA expression was found in the challenged skin of negative elicitation reactions, also indicating no sign of active down-regulation. The study contibutes strongly to the evidence of a decreased susceptibility to develop contact allergy in individuals with autoimmune diseases such as psoriasis., (© 2011 The Authors. Clinical and Experimental Immunology © 2011 British Society for Immunology.)

Most vaccines are administered by intramuscular (i.m.) or subcutaneous (s.c.) routes, however, intradermal (i.d.) and transcutaneous (t.c.) techniques are regaining popularity. We will discuss in this review several factors that strongly justify the use of the cutaneous tissues and development of alternative methods for vaccination. That includes (1) our improved knowledge of skin physiology and better understanding of the barrier role of the horny layer, (2) the rationalization for targeting the different cutaneous layers, i.e. the epidermis, dermis, or hypodermis, (3) our advances in knowledge of the skin immune system, especially the plasticity of antigen-presenting cells (APCs) (i.e Langerhans cells (LC), dermal dendritic cells (DDC) and dermal macrophages) in the induction of immune responses, (4) the reduction of antigenic dose for some modes of cutaneous administration, (5) the increased need in needlefree vaccination strategies for developing countries to cope with blood contamination issues. Progress in skin immunization methods and better understanding of skin immunity allow proposing innovative and efficient vaccination strategies against infectious diseases.

Background: This study compared histological and immunohistochemical changes of cutaneous leishmaniasis treated with meglumine antimoniate, imiquimod, and the combination of both therapies., Methods: Single blind clinicopathological studies of fifteen patients with old world cutaneous leishmaniasis in Kerman, Iran were included. A total of four patients received a combination of imiquimod (5% cream) and intra-lesional meglumine antimoniate weekly for four weeks. Monotherapy with imiquimod was given to seven patients and four patients were treated with meglumine antimoniate intralesionally. Histological confirmation was performed before and during therapy. Semi-quantitative histological parameters such as numbers of mixed inflammatory cells (cells/mm(2)) and percentages of Langerhans cells (CD1a+), T-cells (CD3+), B-cells (CD20+), and macrophages (CD68+) were calculated immunohistochemically in the dermis and adjacent epidermis., Results: Topical imiquimod significantly reduced mean histiocytic cellular aggregation size (P<0.05). Meglumine antimoniate reduced parasite load and infected activated histiocytes in the dermis (P<0.05). Meglumine antimoniate therapy decreased epidermal CD3+ lymphocytes but increased them in the dermis, within the granulomas (P<0.05). During topical application of imiquimod a depletion of CD1a+ dendritic cells in the epidermis (P<0.05) and slight predominance of dendritic cells in the dermis were observed. Combined therapy and imiquimod monotherapy decreased CD68+ macrophages in the dermis (P<0.05)., Conclusion: Meglumine antimoniate decreases parasite load with considerable effect on up-regulation of T-cells, which demonstrates that meglumine antimoniate works as parasitocidal and immunomodulator, which could be a first line of treatment. Imiquimod accentuates the host immune response and reduces granuloma size which could be effective immunomodulator for combination therapy. Monotherapy of imiquimod is less effective than the two other regimens in decreasing parasite load, inflammation and congestion at the inoculated site.

Blocking heat-shock protein 90 (Hsp90) induces death of malignant plasma cells by activation of the unfolded protein response, a signaling pathway activated by accumulation of misfolded proteins within the endoplasmic reticulum. We hypothesized that nontransformed plasma cells are also hypersensitive to Hsp90 inhibition because of their high amount of protein biosynthesis. To investigate this hypothesis, 2 different Hsp90 inhibitors, the geldanamycin derivative 17-DMAG and the nontoxic peptide derivative TCBL-145, were applied to mice with experimental epidermolysis bullosa acquisita, an autoimmune bullous disease characterized by autoantibodies against type VII collagen of the dermal-epidermal junction. Both inhibitors ameliorated clinical disease of type VII collagen-immunized mice, suppressed auto-antibody production, and reduced dermal neutrophilic infiltrate. Interestingly, total plasma cell numbers, type VII collagen-specific plasma cells, and germinal center B cells were unaffected by anti-Hsp90 treatment in vivo. However, T-cell proliferation was potently inhibited, as evidenced by the reduced response of isolated lymph node cells from immunized mice to in vitro restimulation with anti-CD3/CD28 antibody or autoantigen in the presence of Hsp90 inhibitors. Our results suggest that Hsp90 blockade has no impact on normal or autoreactive plasma cells in vivo and indentify T cells as targets of anti-Hsp90 treatment in autoimmunity to type VII collagen.

Dendritic epidermal T cells (DETCs) are a well-studied population of γδ T cells that play important roles in wound repair. In this study, we characterize a second major population of γδ T cells in the skin that is present in the dermis. In contrast to DETCs, these Vγ5-negative cells are IL-7R(hi)CCR6(hi) retinoic acid-related orphan receptor γt(+) and are precommitted to IL-17 production. Dermal γδ T cells fail to reconstitute following irradiation and bone marrow transplantation unless the mice also receive a transfer of neonatal thymocytes. Real-time intravital imaging of CXCR6(GFP/+) mouse skin reveals dermal γδ T cells migrate at ∼4 μm/min, whereas DETCs are immobile. Like their counterparts in peripheral lymph nodes, dermal γδ T cells rapidly produce IL-17 following exposure to IL-1β plus IL-23. We have characterized a major population of skin γδ T cells and propose that these cells are a key source of IL-17 in the early hours after skin infection.

Background: Vitiligo is a common skin disorder, characterized by progressive skin de-pigmentation due to the loss of cutaneous melanocytes. The exact cause of melanocyte loss remains unclear, but a large number of observations have pointed to the important role of cellular immunity in vitiligo pathogenesis., Methodology/principal Findings: In this study, we characterized T cell and inflammation-related dermal dendritic cell (DC) subsets in pigmented non-lesional, leading edge and depigmented lesional vitiligo skin. By immunohistochemistry staining, we observed enhanced populations of CD11c+ myeloid dermal DCs and CD207+ Langerhans cells in leading edge vitiligo biopsies. DC-LAMP+ and CD1c+ sub-populations of dermal DCs expanded significantly in leading edge and lesional vitiligo skin. We also detected elevated tissue mRNA levels of IL-17A in leading edge skin biopsies of vitiligo patients, as well as IL-17A positive T cells by immunohistochemistry and immunofluorescence. Langerhans cells with activated inflammasomes were also noted in lesional vitiligo skin, along with increased IL-1ß mRNA, which suggest the potential of Langerhans cells to drive Th17 activation in vitiligo., Conclusions/significance: These studies provided direct tissue evidence that implicates active Th17 cells in vitiligo skin lesions. We characterized new cellular immune elements, in the active margins of vitiligo lesions (e.g. populations of epidermal and dermal dendritic cells subsets), which could potentially drive the inflammatory responses.

CD160 is expressed by human and mouse natural killer (NK) cells and other cytotoxic lymphocyte subpopulations. CD160 is mostly expressed as a trimeric 83 kDa glycosylphosphatidylinositol (GPI)-anchored activating NK receptor, cleaved upon IL-15 stimulation in a secreted trimeric soluble form (sCD160) that binds to major histocompatibility complex (MHC) class I molecules, while a transmembrane isoform appears. sCD160 exhibits immunoregulatory function as it inhibits CD8(+) T-lymphocyte cytotoxic activity. We show that human mast cells (MCs) express CD160. In human and mouse skin, resident MCs expressed CD160, whereas in C57BL/6-Kit(W-sh/W-sh) mice, CD160(+) cells were only identified at the site of reconstitution with syngeneic cultured MCs. In the human mast cell line, HMC-1, we only identified the transcripts of the GPI-anchored CD160 isoform. Furthermore, CD160 was identified in HMC-1 and mouse MC supernatants, suggesting that MCs release sCD160. Supporting this hypothesis, HMC-1 express the GPI-specific phospholipase D variant 2 involved in the NK lymphocyte membrane cleavage of CD160, and morphological studies highlighted a relative loss of CD160 expression in inflammatory skin sites, where MC degranulation is expected to occur. We also demonstrated an inhibition of T-cell cytotoxicity by HMC-1 supernatant that was partially reversed by anti-CD160 mAb. In conclusion, sCD160, produced by MCs, may have a role in T-cell-MC interactions in vivo.

Dermatitis herpetiformis (DH) is characterized by deposition of IgA in the papillary dermis. However, indirect immunofluorescence is routinely negative, raising the question of the mechanism of formation of these immune deposits. Sárdy et al. (2002. J. Exp. Med. 195: 747-757) reported that transglutaminase-3 (TG3) colocalizes with the IgA. We sought to create such deposits using passive transfer of Ab to SCID mice bearing human skin grafts. IgG fraction of goat anti-TG3 or control IgG were administered i.p. to 20 mice. Separately, sera from seven DH patients and seven controls were injected intradermally. Biopsies were removed and processed for routine histology as well as direct immunofluorescence. All mice that received goat anti-TG3 produced papillary dermal immune deposits, and these deposits reacted with both rabbit anti-TG3 and DH patient sera. Three DH sera high in IgA anti-TG3 also produced deposits of granular IgA and TG3. We hypothesize that the IgA class anti-TG3 Abs are directly responsible for the immune deposits and that the TG3 is from human epidermis, as this is its only source in our model. These deposits seem to form over weeks in a process similar to an Ouchterlony immunodiffusion precipitate. This process of deposition explains the negative indirect immunofluorescence results with DH serum.

Macrophage migration inhibitory factor (MIF) is a pluripotent cytokine that has an essential role in the pathophysiology of experimental allergic inflammation. Recent findings suggest that MIF is involved in several allergic disorders, including atopic dermatitis (AD). In this study, the role of MIF in allergic skin inflammation was examined using a murine model of AD elicited by epicutaneous sensitization with ovalbumin (OVA). We observed the number of skin-infiltrating eosinophils to significantly increase in OVA-sensitized MIF transgenic (Tg) mice compared with their wild-type (WT) littermates. On the other hand, eosinophils were virtually absent from the skin of MIF knockout (KO) mice and failed to infiltrate their skin after repeated epicutaneous sensitization with OVA. The mRNA expression levels of eotaxin and IL-5 were significantly increased in OVA-sensitized skin sites of MIF Tg mice, but were significantly decreased in MIF KO mice in comparison with the levels in WT littermates. Eotaxin expression was induced by IL-4 stimulation in fibroblasts in MIF Tg mice, but not in MIF KO mice. These findings indicate that MIF can induce eosinophil accumulation in the skin. Therefore, the targeted inhibition of MIF might be a promising new therapeutic strategy for allergic skin diseases.

Allograft inflammatory factor (AIF)-1 has been identified in chronic rejection of rat cardiac allografts and is thought to be involved in the immune response. We previously showed that AIF-1 was strongly expressed in synovial tissues in rheumatoid arthritis and that rAIF-1 increased the IL-6 production of synoviocytes and peripheral blood mononuclear cells. Recently, the expression of AIF-1 has been reported in systemic sclerosis (SSc) tissues, whose clinical features and histopathology are similar to those of chronic graft-vs-host disease (GVHD). To clarify the pathogenic mechanism of fibrosis, we examined the expression and function of AIF in sclerodermatous (Scl) GVHD mice. We demonstrated that immunoreactive AIF-1 and IL-6 were significantly expressed in infiltrating mononuclear cells and fibroblasts in thickened skin of Scl GVHD mice compared with control. The immunohistochemical findings were confirmed by Western blot analysis. Wound healing assay also revealed that rAIF-1 increased the migration of normal human dermal fibroblasts (NHDF) directly, but cell growth assay did not show that rAIF-1 increased the proliferation of them. These findings suggest that AIF-1, which can induce the migration of fibroblasts and the production of IL-6 in affected skin tissues, is an important molecule promoting fibrosis in GVHD. Although the biological function of AIF-1 has not been completely elucidated, AIF-1 can induce IL-6 secretion on mononuclear cells and fibroblast chemotaxis. AIF-1 may accordingly provide an attractive new target for antifibrotic therapy in SSc as well as Scl GVHD., (Copyright © 2010 Elsevier B.V. All rights reserved.)

DC-SIGN is a C-type lectin of recognized importance in immunology and in the pathogenicity human pathogens. Monoclonal antibodies directed against DC-SIGN have been generated, but their systemic characterization for interfering with binding of the HIV-1 glycoprotein 120 has often been omitted. Moreover, so far, no anti-DC-SIGN monoclonal antibody has been described that recognizes its antigen after formalin fixation and paraffin embedding. In this study, we have generated new anti-DC-SIGN monoclonal antibodies using HeLa cells stably expressing DC-SIGN as immunogen. We have obtained 11 hybridoma clones producing antibodies that recognized DC-SIGN on monocyte-derived dendritic cells and on dermal-type macrophages. Seven monoclonal antibodies displayed a capacity to interfere with DC-SIGN binding to HIV-1 gp120. One recognized DC-SIGN on formalin-fixed dendritic cells and macrophages. Using this antibody we have obtained specific labelling of DC-SIGN and colocalisation with the dermal macrophage marker CD163 on human skin. The described monoclonal anti-human DC-SIGN antibodies will be of use to the scientific community to address fundamental immunology issues, in particular concerning macrophages and dendritic cells, and help elucidate infection events of pathogen targeting DC-SIGN as recognition receptor., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Objective: The transcription factor STAT-4 has recently been identified as a genetic susceptibility factor in systemic sclerosis (SSc) and other autoimmune diseases. The aim of this study was to investigate the contribution of STAT-4 in the development of a fibrotic phenotype in 2 different mouse models of experimental dermal fibrosis., Methods: STAT-4-deficient (stat4(-/-) ) mice and their wild-type littermates (stat4(+/+) ) were injected with bleomycin or NaCl. Infiltrating leukocytes, T cells, B cells, and monocytes were quantified in the lesional skin of stat4(-/-) and stat4(+/+) mice. Inflammatory and profibrotic cytokines were measured in sera and lesional skin samples from stat4(-/-) and stat4(+/+) mice. The outcome of mice lacking STAT-4 was also investigated in the tight skin 1 (TSK-1) mouse model., Results: Stat4(-/-) mice were protected against bleomycin-induced dermal fibrosis, with a reduction in dermal thickening (mean ± SEM 65 ± 3% decrease; P = 0.03), hydroxyproline content (68 ± 5% decrease; P = 0.02), and myofibroblast counts (71 ± 6% decrease; P = 0.005). Moreover, the number of infiltrating leukocytes, especially T cells, was significantly decreased in the lesional skin of stat4(-/-) mice (mean ± SEM 63 ± 5% reduction in T cell count; P = 0.02). Stat4(-/-) mice also displayed decreased levels of inflammatory cytokines such as tumor necrosis factor α, interleukin-6 (IL-6), IL-2, and interferon-γ in lesional skin. Consistent with a primary role of STAT-4 in inflammation, STAT-4 deficiency did not ameliorate fibrosis in TSK-1 mice., Conclusion: The results of this study demonstrate that the transcription factor STAT-4 exerts potent profibrotic effects by controlling T cell activation and proliferation and cytokine release. These findings confirm the results of genetics studies on the role of STAT-4 in the development of SSc., (Copyright © 2011 by the American College of Rheumatology.)

Infection of the mammalian host by schistosome larvae occurs via the skin, although nothing is known about the development of immune responses to multiple exposures of schistosome larvae, and/or their excretory/secretory (E/S) products. Here, we show that multiple (4x) exposures, prior to the onset of egg laying by adult worms, modulate the skin immune response and induce CD4(+) cell hypo-responsiveness in the draining lymph node, and even modulate the formation of hepatic egg-induced granulomas. Compared to mice exposed to a single infection (1x), dermal cells from multiply infected mice (4x), were less able to support lymph node cell proliferation. Analysis of dermal cells showed that the most abundant in 4x mice were eosinophils (F4/80(+)MHC-II(-)), but they did not impact the ability of antigen presenting cells (APC) to support lymphocyte proliferation to parasite antigen in vitro. However, two other cell populations from the dermal site of infection appear to have a critical role. The first comprises arginase-1(+), Ym-1(+) alternatively activated macrophage-like cells, and the second are functionally compromised MHC-II(hi) cells. Through the administration of exogenous IL-12 to multiply infected mice, we show that these suppressive myeloid cell phenotypes form as a consequence of events in the skin, most notably an enrichment of IL-4 and IL-13, likely resulting from an influx of RELMα-expressing eosinophils. We further illustrate that the development of these suppressive dermal cells is dependent upon IL-4Rα signalling. The development of immune hypo-responsiveness to schistosome larvae and their effect on the subsequent response to the immunopathogenic egg is important in appreciating how immune responses to helminth infections are modulated by repeated exposure to the infective early stages of development.

Dendritic cells (DCs) subsets differ in precursor cell of origin, functional properties, requirements for growth factors, and dependence on transcription factors. Lymphoid-tissue resident CD8α(+) conventional DCs (cDCs) and CD11b(low/-)CD103(+) non-lymphoid DCs are developmentally related, each being dependent on FMS-like tyrosine kinase 3 ligand (Flt3L), and requiring the transcription factors Batf3, Irf8, and Id2 for development. It was recently suggested that granulocyte/macrophage colony stimulating factor (GM-CSF) was required for the development of dermal CD11b(low/-)Langerin(+)CD103(+) DCs, and that this dermal DC subset was required for priming autoreactive T cells in experimental autoimmune encephalitis (EAE). Here, we compared development of peripheral tissue DCs and susceptibility to EAE in GM-CSF receptor deficient (Csf2rb(-/-)) and Batf3(-/-) mice. We find that Batf3-dependent dermal CD11b(low/-)Langerin(+) DCs do develop in Csf2rb(-/-) mice, but that they express reduced, but not absent, levels of CD103. Further, Batf3(-/-) mice lacking all peripheral CD11b(low/-) DCs show robust Th cell priming after subcutaneous immunization and are susceptible to EAE. Our results suggest that defective T effector priming and resistance to EAE exhibited by Csf2rb(-/-) mice does not result from the absence of dermal CD11b(low/-)Langerin(+)CD103(+) DCs.

Psoriasis affects 2.7% of the world's population. The sequence of these events remains controversial. Because antigen presenting is necessary for T-cell activation, dendritic cells may be involved in the pathogenesis of psoriasis. To investigate their role, we examined immunophenotyping of different dendritic cells and their distribution and numbers in psoriasis patients. Immunohistochemistry of CD1a, CD11c, CD86 and BDCA2 were performed using paraffin-embedded tissue obtained from a total of 45 patients with psoriasis. Samples were taken from the lesion, perilesional and distant skin and normal skin obtained from 10 control cases. There were marked increase in the number of positive CD1a, CD11c, CD86 and BDCA2 cells in perilesional and the psoriatic skin when compared to the distant skin and they were the least in the normal control skin. So different dendritic cells subsets have a very important role in psoriasis pathogenesis especially in initiation of the plaque in the perilesional skin., (Copyright © 2011 Elsevier Inc. All rights reserved.)