Intraepidermal Langerhans Cells Research Articles

Potential Treatment of Psoriasis with Oral Spironolactone as TNF-Alpha Inhibitor – A Future Prospective Review

Psoriasis is a chronic dermatological condition that cause scaly red patches on the different parts of body. It always tends in cycles of months wherein winter aggravation is most common then it subsides for a while then again relapse or remission. The exact identity of the factors causing psoriasis is not established but the fact that T cell activates the release of proinflammatory cytokines such as TNF-α, interferon-γ and IL-2 has been identified. Cytokine, TNF- α plays a key role in keratinocyte proliferation and other vascular changes in psoriasis. TNF-α protein levels has been found on higher side in psoriasis lesions, intraepidermal Langerhans cells and dermal dendrocytes. The available treatment options for suppressing TNF-α are given only by IV/SC route like adalimumab, infliximab and etanercept also costlier and give only symptomatic relief for a shorter period of time. Hence, we need a pharmacologically active, therapeutically safe and cost-effective agent for long term use. Against all the available data, Spironolactone an aldosterone antagonist has been found to fulfill all the necessary conditions to be used as TNF- α antagonist, a noticeable suppressive effect on TNF- α receptor along with several pro-inflammatory cytokines. Such findings encouraged beginning of clinical studies of spironolactone as TNF- 𝛼 antagonist in patients with psoriasis.

Langerhans Cells as Morphologic Mimickers of Atypical Melanocytes on Reflectance Confocal Microscopy: A Case Report and Review of the Literature.

Pagetoid spread of melanocytes in the epidermis is a common indicator of melanocytic atypia, both histopathologically and with reflectance confocal microscopy (RCM). Specifically on RCM, large, bright, atypical dendritic and/or roundish cells are characteristic of melanoma. However, intraepidermal Langerhans cells (ILC) create the potential for diagnostic ambiguity on RCM. We describe one case of a pigmented facial lesion that was initially diagnosed as lentigo maligna (LM) due to numerous atypical perifollicular dendritic cells on RCM. Additionally, we present the findings of a literature review for similar reported cases conducted by searching the following terms on PubMed: reflectance confocal microscopy, RCM, lentigo maligna, melanoma, Langerhans cells, dendritic cells, and atypical cells. In our case, the lesion was determined to be a solar lentigo on histopathology. Immunohistochemistry (IHC) with CD1a identified the atypical-appearing cells as ILC, as it did in 54 reported cases of benign lesions (benign melanocytic nevus, Sutton/halo nevus, labial melanotic macule, and solar lentigo) misdiagnosed as malignant on RCM (melanoma, lip melanoma, lentigo maligna, and LM melanoma). According to our case and the literature, both ILC and atypical melanocytes can present with atypical-appearing dendritic and/or roundish cells under RCM. Currently, there is no method to distinguish the two without IHC. Therefore, the presence of pagetoid cells should continue to alert the confocalist of a potential neoplastic process, prompting biopsy, histopathologic diagnosis, and IHC differentiation.

Histopathologic and Immunohistochemical Correlates of Confocal Descriptors in Pigmented Facial Macules on Photodamaged Skin

Pigmented facial macules on photodamaged skin are a clinical, dermoscopic, and histopathologic challenge. To clinically and dermoscopically characterize, by means of reflectance confocal microscopy (RCM), ambiguous pigmented facial macules and establish a correlation between RCM, histopathologic, and immunohistochemical findings. A prospective study of ambiguous pigmented facial macules on photodamaged skin was conducted in a tertiary referral center for dermatology between January 1, 2009, and December 31, 2015. Sixty-one patients with 63 ambiguous pigmented facial macules and 12 control photodamaged facial areas were included in the study. Melanocyte density in 1-mm basal layers was determined in skin biopsy specimens from all lesions stained with hematoxylin-eosin and immunohistochemical markers (melan-A, microphthalmia-associated transcription factor, and SRY-related HMG-box gene 10). Dermoscopic, RCM images, and histopathologic preparations were systematically evaluated for the presence of lentigo maligna (LM) criteria. Confocal evaluation was blinded to clinical and dermoscopic diagnosis. Sensitivity and specificity of RCM for LM diagnosis and κ value to establish correlations between dermoscopy, RCM, and histopathology were performed. Sensitivity and specificity of RCM for LM diagnosis. Of the 61 patients included in the study, 31 (51%) were women; mean (SD) age was 71.8 (13.1) years. Twenty-four of the 63 (38%) lesions were diagnosed as LM or LM melanoma (LMM) and 39 (62%) as benign pigmented lesions. Reflectance confocal microscopy enhanced the diagnosis of pigmented facial macules with 91.7% sensitivity and 86.8% specificity. Multivariate analysis showed 2 dermoscopic and 2 confocal features associated with LM or LMM: (1) asymmetric follicular pigmentation and targetlike structures, and (2) round, large pagetoid cells and follicular localization of atypical cells, respectively. Continuous proliferation of atypical melanocytes was found in 21 (88%) LM or LMM and in 3 (77%) benign lesions. Asymmetric pigmented follicular openings by dermoscopy correlated with follicular localization of pagetoid cells by RCM (κ = 0.499, P < .001). The presence of 3 or more atypical cells at the dermal-epidermal junction (DEJ) by RCM correlated with hyperplasia of melanocytes in hematoxylin-eosin sections (κ = 0.422, P < .001). Reflectance confocal microscopy improves LM diagnosis in photodamaged skin with good histopathologic correlation although false-positive and false-negative cases exist. False-positives obtained with RCM in photodamaged skin are due to the presence of basal melanocyte hyperplasia and intraepidermal Langerhans cells. Histopathologic features of these lesions sometimes are not enough for a definite diagnosis and immunohistochemical studies may be required.

Langerhans cells and melanocytes share similar morphologic features under in vivo reflectance confocal microscopy: A challenge for melanoma diagnosis

Intraepidermal Langerhans cells (ILC) are difficult to differentiate from melanocytes under reflectance confocal microscopy (RCM) and their presence may simulate pagetoid spread of melanocytes on RCM images. We sought to correlate bright round and dendritic cells in a pagetoid pattern identified on RCM with findings of conventional histopathology and immunohistochemistry for lesions that were falsely diagnosed as melanoma by RCM. This retrospective study included histopathologically proven nevi, imaged by RCM, which displayed bright cells in a pagetoid pattern (BCPP) under RCM, resulting in the incorrect RCM diagnosis of melanoma. Morphological comparisons were made between RCM images of nevi showing BCPP, histopathologically proven melanomas displaying BCPP, and biopsy-proven nevi without BCPP. We identified 24 nevi that were falsely diagnosed as melanoma by RCM because of the presence of BCPP. These pagetoid cells on RCM corresponded on histopathology to ILC with a high density in 23 of the 24 nevi (95%) and to melanocytes in 7 of the 24 nevi (29%). Among 6 melanomas displaying BCPP on RCM, ILC with high density were observed histopathologically in 5 of the 6 cases (83%) and pagetoid melanocytes were seen in all 6 cases (100%). The results cannot be generalized to clinically banal-appearing nevi. Although the finding of BCPP is a useful RCM feature for the diagnosis of melanoma, it does not always imply the presence of pagetoid melanocytes but may at times represent ILC.

Research Highlights: Immunotherapy

Research Highlights: Immunotherapy

Immunohistochemical tracking of an immune response in mammary Paget’s disease

Dendritic cells (DC) are the most potent antigen-presenting cells of the organism. They are specialized to capture, process, and present antigen via the MHC class II as well as the MHC class I pathways to CD4 + and CD8 + T cells, respectively. This results in T cell-mediated immune responses that are likely to counteract the generation and propagation of tumors in vivo. Therefore, we studied the distribution of dendritic cells in mammary Paget’s disease. Paraffin-embedded samples of Paget’s disease of the breast ( n = 27) and of disease-free epidermis of the nipple ( n = 10) were investigated immunohistochemically for the presence of dendritic cells, in particular of Langerhans cells, using antibodies against S-100, CD1a, and HLA-DR, as well as novel reagents against Langerin/CD207, DC-LAMP/CD208 and p55 (Fascin), the latter two being specific for mature dendritic cells. Paget samples presented a decrease of CD1a +, S-100 +, and Langerin + intraepidermal Langerhans cells in almost all cases. This was paralleled by a concentration of immature dendritic cells in the tumor-infiltrated tissue itself. Similar to infiltrating breast carcinoma we observed a marked increase of DC-LAMP + and p55 + mature dendritic cells in the corial tissue beneath the tumor. These cells were almost always found in ribbon-like or nodular lymphocytic infiltrates. Moreover, rare mature dendritic cells were also found in the Paget cell-infiltrated epidermis of the nipple, i.e. in the tumorous lesion itself. These findings may indicate an effective ongoing anti-tumor immune response in this part of spreading breast cancer.

Expression of haptoglobin in human keratinocytes and Langerhans cells

Epidermal Langerhans cells (LCs) play an important role in cutaneous immunological reactions. Freshly obtained or intraepidermal LCs are incapable of activating autologous naive T cells. However, when they are cultured for 2-3 days, LCs are able to activate autologous T cells. It has been proposed that haptoglobin (Hp) is the inhibitor that prevents LC functional transformation in the skin. Abundant Hp has been found in the cytoplasm of epidermal LCs. However, the source of Hp in LCs has not been addressed. To determine the expression of Hp in epidermal cells, and to provide evidence that there is a functional relationship between LCs and keratinocytes (KCs) through Hp. Normal human epidermal cells and HaCaT cells were used for detection of Hp mRNA by in situ hybridization and reverse transcription-polymerase chain reaction, and Hp protein by immunohistochemical staining, immunofluorescence counterstaining and Western blotting. Hp mRNA was expressed in normal human KCs and HaCaT cells, but not in normal human epidermal LCs. Hp protein was detected by immunohistochemical staining and immunofluorescence counterstaining in CD1a+ epidermal dendritic cells (LCs), but not in KCs. Hp protein was weakly expressed by HaCaT cells. Hp mRNA is present in normal human KCs and HaCaT cells, suggesting that they have the potential to synthesize Hp protein. Normal human epidermal LCs are unable to synthesize Hp protein by themselves, although they have abundant Hp protein in their cytoplasm. It is likely that LCs acquire Hp through an exogenous pathway.

CD1A Rich Inflammatory Stage of Lichen Sclerosus Et Atrophicans Mimicking Mycosis Fungoides and Extramammary Paget’S Disease

We report a case of inflammatory stage vulvar lichen sclerosus et atrophicans (LSA) with histopathologic features simulating both patch stage mycosis fungoides (MF) and extramammary Paget’s disease. The patient is a 79‐year‐old woman with an erythematous plaque on her vulva. A punch biopsy was performed that revealed mild psoriasiform hyperplasia of the epidermis with spongiosis, marked interface vacuolar alteration, scattered individual necrotic keratinocytes and Civatte bodies. A band‐like mixed inflammatory infiltrate was present in the papillary/upper dermis with prominent intraepidermal lymphocytes. Some intraepidermal lymphocytes showed atypical nuclear contours simulating the cells seen in MF. The presence of numerous intraepidermal epithelioid cells with a pagetoid distribution raised the possibility of extramammary Paget’s disease. A panel of immunohistochemical (IHC) stains showed a reactive lichenoid mixed population of lymphocytes with numerous intraepidermal Langerhans cells. This confirmed the diagnosis of the inflammatory stage of lichen sclerosus. The presence of prominent epithelioid Langerhans cells with activated small lymphocytes represents an immune response in LSA and could cause diagnostic confusion with neoplastic conditions. IHC staining can confirm cell type and rule out MF and extramammary Paget’s disease.

Cutaneous Dendritic Cells Are Main Targets in Acute HIV-1-Infection

Acute human immunodeficiency virus (HIV) infection is a transient illness that typically presents with mucocutaneous and constitutional symptoms. It is soon followed by seroconversion with the detection of anti-HIV antibodies in the peripheral blood. To better understand the pathogenetic events leading to this clinical picture, we sought to investigate the (immuno)histologic features of the skin rash occurring in an acutely infected person. A skin biopsy of an acutely infected person was investigated histologically and immunohistologically using paraffin-embedded tissue sections. Interface dermatitis with pronounced vacuolization of the basal keratinocytes was a prominent histological finding. The inflammatory infiltrate was composed of CD3+/CD8+ T cells with coexpression of Granzyme B7 and TIA-1, and CD68+ histiocytes/dendritic cells. CD1a+ intraepidermal Langerhans cells (LC) were significantly decreased and individual LC co-expressed HIV-p24 antigens as evidenced in double labeling experiments. HIV-infected LC were demonstrated in close apposition to cytotoxic T cells.This study provides the first definitive evidence for infection of LC at extramucosal sites in this very early stage of disease. Our findings emphasize the critical role of dendritic cells as a virus reservoir and the skin as a major site of HIV replication during the course of the disease.

High-Dose Ultraviolet A1 (UVA1), but Not UVA/UVB Therapy, Decreases IgE-Binding Cells in Lesional Skin of Patients with Atopic Eczema

In order to further elucidate the mechanisms by which high-dose ultraviolet A1 (UVA1) therapy leads to improvement in patients with atopic eczema, we assessed skin sections from patients before and after high-dose UVA1 therapy (n = 5) or conventional UVA/UVB therapy (n = 4) for changes in Langerhans cells and mast cells expressing the high-affinity IgE receptor Fc epsilon RI and in surface-bound IgE by histochemical and immunohistochemical techniques. The two treatment groups exhibited different patterns of changes in the number of Fc epsilon RI+, CD1a+, and mast cells within the dermis: The density of both Langerhans cells and mast cells was decreased after high-dose UVA1 therapy, but not after UVA/UVB therapy. High-dose UVA1 and UVA/UVB therapy significantly increased the number of CD1a+ cells within the epidermis, but only high-dose UVA1 reduced the relative number of IgE+ intraepidermal Langerhans cells typically found in atopic eczema. Reduction of numbers of dermal Langerhans cells and mast cells, as well as relative numbers of intraepidermal IgE+ Langerhans cells, was closely linked to significant clinical improvement by high-dose UVA1, but not UVA/UVB therapy. These studies support the notion that IgE-binding cutaneous cells are involved in the pathogenesis of atopic eczema. We propose that UVA1 radiation exerts its effects in atopic eczema, at least in part, by inhibiting Langerhans cell migration out of the epidermis and, in particular, by reducing the number of IgE-bearing Langerhans cells and mast cells in the dermis.

Hair Cycle-Dependent Changes in Skin Immune Functions: Anagen-Associated Depression of Sensitization for Contact Hypersensitivity in Mice

To assess whether hair follicle cycling influences skin immunity, we examined the association between highly synchronized hair follicle cycling and experimental contact hypersensitivity in C57BL/6 mice. Hair cycle synchronization was performed by depilation of hair shafts on the back with telogen skin. Mice were sensitized on the lower back skin with picryl chloride between 0 and 25 d, after anagen induction by depilation, and challenged on the earlobes with picryl chloride 5 d later. The magnitude of contact hypersensitivity was significantly decreased in mice sensitized on day 1, was minimal on day 3 (early anagen), and slowly increased thereafter, reaching level comparable to day 0 on day 25 (telogen). The significantly depressed contact hypersensitivity response in anagen skin was confirmed in mice with spontaneously developed follicles. Lymph node cells taken from mice sensitized with picryl chloride on days 0, 1, and 3 after depilation were cultured in vitro in the presence of syngeneic, haptenized, Langerhans cell-enriched epidermal cells. Marked proliferative responses of lymph node cells to haptenized cells were found in mice not only of day 0, but also of days 1 and 3, suggesting that immune T cells exist even lymph node cells of the low-responsive mice. Flow cytometric analyses demonstrated that the number of intraepidermal Langerhans cells and their functions, including the expression of major histocompatibility complex class II, CD54, and CD86, and mixed epidermal cell lymphocyte reactions, were not changed in skin on days 0,1, and 3. These findings demonstrated that contact hypersensitivity is induced most effectively via skin with telogen hair follicles and that the depressed response in early anagen skin is not simply due to failure in Langerhans cell function or sensitization of T cells.

Antigen-Bearing Langerhans Cells in Skin Draining Lymph Nodes: Phenotype and Kinetics of Migration

Application of the fluorescent contact sensitizer Rhodamin B on mouse epidermis was used to study the migration kinetics of Langerhans cells into the draining lymph nodes. The expression of the dendritic cell markers NLDC-145 and MIDC-8 was followed over time to determine the correlation between these markers and Langerhans cell migration. In contrast with its high expression on intraepidermal Langerhans cells, the expression of NLDC-145 on dendritic cells in the draining lymph node was low at 24 h but increased at later times; in contrast, MIDC-8 expression on dendritic cells decreased. Ten days after Rhodamin B application, antigen-bearing Langerhans cells were still present in the epidermis; application of another unrelated contact sensitizer to the epidermis at this time did not lead to migration of these residual Langerhans cells. These results indicate that not all antigen-bearing Langerhans cells migrate from the skin after application of a contact sensitizer, indicating that signals in addition to simple antigen binding are necessary for migration. During this migration from epidermis to lymph nodes Langerhans cells undergo phenotypic changes. The decreased expression of the endosomal antigens MIDC-8 and MOMA-2 correlates with differentiation from predominantly antigen-processing cells to predominantly antigen-presenting cells. The reduced expression of NLDC-145 is discussed in light of a Langerhans cell-independent pathway of antigen transportation from skin to lymph node.

Cyclosporin in psoriasis: pathophysiology and experimental data.

Cyclosporin has been used efficaciously in recent years for the management of severe psoriasis. The remarkable efficacy of this drug and its known immunosuppressive properties have indicated even more strongly the involvement of the immune system in the induction and maintenance of psoriasis. The present review summarizes the role of cellular immunity in the pathogenesis of psoriasis and possible mechanisms of action of cyclosporin in psoriasis, and describes the laboratory studies performed in our Department under two headings, changes in lesional immune infiltrate (evaluated immunohistologically) and changes in neutrophil chemotaxis during cyclosporin treatment. Our immunohistological study showed that the psoriatic plaques contained an infiltrate composed mainly of activated CD4+ T cells. Cyclosporin treatment significantly decreased T cells and normalized the distribution and antigen expression of intraepidermal Langerhans cells, increasing the number of CD1+ dendritic cells. Our studies on neutrophil chemotaxis showed that cyclosporin reduced the chemotactic activity of neutrophilic polymorphonuclear leukocytes (in vivo but not in vitro), seemingly as a consequence of blocking the production of chemoattracting cytokines by psoriatic monocytes.

Speculations on the Immunopathogenesis of Psoriasis: T-Cell Violation of a Keratinocyte Sphere of Influence

The thesis is advanced that the differences in antigen processing and presentation described for "fresh" and "cultured" Langerhans cells in vitro reflect similar differences between intraepidermal and intranodal Langerhans cells in vivo. The functional properties of Langerhans cells are dependent upon the microenvironment in which they reside; thus, intraepidermal Langerhans cells are under the influence of cytokines secreted by keratinocytes, whereas intranodal Langerhans cells come under the influence of lymphokines from T lymphocytes. It is speculated that a genetic lesion in psoriasis robs keratinocytes of their capacity to create an "appropriate" epidermal microenvironment. As a consequence, intraepidermal Langerhans cells adopt the functional program of intranodal cells. When "uninvolved" psoriatic skin receives a cutaneous challenge with antigen, Langerhans cells, by activating naive T cells in situ, unwittingly engender a microenvironment that is more appropriate to a lymph node. This skin becomes "involved" as it gradually acquires features associated with lymph nodes (such as high endothelial venules). And the derangement is further complicated by abnormalities of proliferation and differentiation among keratinocytes and dermal fibroblasts as they respond to the inappropriate T-cell-derived lymphokines, giving rising to the typical, active psoriatic lesion.

Functional Dichotomy between Langerhans Cells that Present Antigen to Naive and to Memory/Effector T Lymphocytes

The general thrust of this volume is to review the roles of accessory cells in regulating T and B lymphocytes. To that end, we have summarized the evidence that indicates the crucial role that Langerhans cells play in the induction and expression of immunity to antigens that gain access to, or arise within, skin. Langerhans cells accomplish this important goal by their abilities to (a) activate naive T cells to antigens not previously encountered by the host, and (b) activate memory/effector T cells specific for previously encountered antigens. Arguments have been advanced to support the view that the functional properties of Langerhans cells used to present antigens to naive T cells differ substantially from the properties that equip Langerhans cells to activate effector T cells. The arguments are based in part on the fact that Langerhans cells carry out these functions in two very different environments: in the epidermis, and in the draining lymph node. The arguments are also based on results of in vitro experiments that reveal distinct differences in antigen processing and presenting properties of Langerhans cells freshly obtained from mouse and human skin as compared to Langerhans cells that have been cultured in vitro for 2-3 days. We propose that freshly explanted Langerhans cells faithfully reflect the functional program of intraepidermal Langerhans cells, and are able to present antigen to memory/effector T cells that enter the epidermal compartment. To accomplish this task, epidermal LC pick up environmental antigens, process them with great efficiency, and then present them in situ, without further upregulation of "accessory" signals (cell-adhesion molecules, secretion of additional cytokines). They can carry out this function, even in the presence of TGFB--a a cytokine which is constitutively made by keratinocytes, and which we have found to profoundly inhibit antigen presentation by most other types of "professional" antigen-presenting cells. Intraepidermal Langerhans cells are also capable of carrying cutaneous antigens through the dermal epidermal junction and migrating to the draining lymph node. We further propose that cultured Langerhans cells are fated to present antigens to unprimed/naive T cells, and thereby to initiate immune responses to new cutaneous antigens. Cultured LC process antigens less efficiently than fresh cells, but their unique capacity to present antigen effectively to unprimed T cells rests chiefly on the fact that they have significantly upregulated cell surface adhesion molecules, expression of MHC molecules, and secretion of activating cytokines--the "accessory" signals that are required for arousing naive T cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunopathological Aspects of Etretinate Therapy in Lichen Planus

Biopsy specimens of involved and uninvolved skin were studied in 8 patients suffering from generalized lichen planus (LP) before and after successful etretinate treatment using murine monoclonal antibodies against several cell surface markers of effector and/or accessory cells of the immune system. In contrast to untreated LP-lesions, in biopsies obtained after etretinate therapy from healed involved skin a markedly disintegrated HLA-DR expression on keratinocytes and intraepidermal Langerhans cells and a nearly total loss of suppressor/cytotoxic T lymphocytes at the dermo-epidermal interface were found. Our data emphasize the key position of the class II antigen expression on various immunocompetent cells, as a marker for a cell-mediated immune reaction, on the other hand, stress the involvement of keratinocytes, Langerhans cells and suppressor/cytotoxic T lymphocytes in the pathogenesis of LP.