Changes in the MHC Class II+ Dendritic Cell Population of Ovine Skin In Response to Orf Virus Infection

Abstract— Class II+ dendritic cells were widely distributed throughout normal ovine skin in two main locations: a) in or immediately adjacent to the epidermis and epidermal appendages and b) in the vicinity of the blood vessels. They are unlikely to represent a homogeneous population particularly since Langerhans cells, which previously have been found throughout the epidermal appendages, were located only in the epidermis using acetylcholinesterase staining. Following infection with orf virus, a dense mass of closely associated class II+ dendritic cells develops in the exposed necrotising dermis, adjacent to infected hair follicles and under infected degenerating epidermis. These cells interact and appear to form a barrier to invasion, a framework for immune defence and a template for subsequent epidermal repair; they seem to provide the basis of a highly integrated local dermal defence system. Résumé— Des cellules dendritiques de classe II+étaient largement réparties dans la peau ovine normale dans deux principales zones a) dans l'épiderme et les annexes épidermiques ou dans leur voisnage immédiat b) au voisinage des vaisseaux sanguins. Il est peu probable qu'elles représentant une population homogène particulièrement parce que les cellules de Langerhaps, qui ont été découvertes précédemment dans l'ensemble des annexes épidermiques, furent localisées seulement dans l'épiderme en utilisant une coloration à l'acétylcholinesterase. Après une infection par le virus de l'ecthyma, il se forme une masse dense de cellules dendritiques de classe II+étroitement associées, dans le derme nécrotique atteint, adjacente aux follicules pileux infectés et sous l'épiderme dégénératif infecté. Ces cellules interagissent et apparaissent former une barrière à l'invasion, un cadre pour les défenses immunitaires et un patron pour la réparation épidermique ultérieure; elles semblent fournir les bases d'un système de défense dermique local hautement intégré. Zusammenfassung— Klasse II+-Dendritenzellen waren in der gesamten Haut von normalen Schafen in vorwiegend zwei Bereichen verbreitet: a) in oder unmittelbar neben der Epidermis und der epidermalen Anhangsgebiete und b) in dor Nähe dar Blutgefäße. Sie stellen wahrscheinlich keine homogène Population dar, da die Langerhanszellen, die früher übarall in den epidermalen Anhangsgebilden nachgewiesen wurden, bei Acetylcholinesterase-Färbung nur in der Epidermis zu finden waren. Nach einer Orf-Virus-Infektion formiert sich eine dichte Masse aus eng verbundenen Klasse II+-Dendritenzellen in der betroffenen nekrotisierenden Dermis unmittelbar neben den infizierten Haarfollikeln und unter der infizierten, degenerierenden Epidermis. Diese Zellen stehen untereinander in Verbindung und bilden anscheinend eine Barrière gegen die Invasion, ein Gorüst für die Immunabwehr und einen Ausgangs punkt für die anschließenden Reparaturvorgänge in der Epidermis. Sie scheinen als Basis eines hochentwickelten lokalen Abwehrsystems der Haut zu fungieren. Resumen Células dendríticas de class II+ se observaron en gran cantidad en la piel de la oveja especialmente en dos localizaciones: a) en la epidermis, en la dermis muy próxima a la epidermis y en anejos cutáneos y b) en las proximidades de los vasos sanguíneos. No parece tratarse de una población homogénea de células puesto que las células de Langerhans, que previamente se habían encontrado en los anejos epidérmicos, se encontraron únicamente en la epidermis utilizando técnicas de detección del acetilcol-inesterasa. Después de la infección con el virus del ectima contagioso ovino se observó una masa de células dendríticas de clase II, dispuestas de forma muy densa, en las proximidades de la dermis necrosada y de los folículos pilosos y de la epidermis infectada. Eatas células interaccionan entre si y parecen formar una barrera contra la invasión, una red inmunitaria de defensa y participar en la reparación de la epidermis; parece ser que esta población de células dendriticas son la base de un sistema de defensa dérmico local altamente integrado.     

Resident Dendritic Cells in the Epidermis: Langerhans Cells, Merkel Cells and Melanocytes

Résumé— En plus des kératinocytes, l'épiderme contient des cellules résidentes de morphologie dendritique. Ce sont principalement la cellule de Langerhans, la cellule de Merkel et le mélanocyte. Ces cellules ont des fonctions diverses dans le tégument. Le mélanocyte assure la pigmentation cutanée et la protection contre les radiations U.V., et pourrait intervenir également dans la modulation de l'inflammation cutanée. La cellule de Langerhans intervient dans la surveillance immunologique des surfaces corporelles ecternes. La cellule de Merkel a des fonctions neuroendocrines. Cet article donne un aperçu de la structure et de la fonction de ces trois importantes populations cellulaires dans la peau. [Resident dentritic cells in the epidermis: Langerhans cells, Merkel cells and melanocytes (Cellules dentritiques résidentes de l'épiderme: cellules de Langerhans, cellules de Merkel et mélanocytes). Resumen— La epidermis contiene, además de los queratinocitos, células résidentes de morfologia dendria dendritica. Estas son principalmente las células de Langerhans, las células de Merkel y los melanocitos. Estas células tienen varias funciones en el integumento. Los melanocitos se encargan de la pigmentación y protección de la piel contra la radiación ultravioleta y tarrtbién participan en la regulación de la inflamación cutánea. Las células de Langerhans ayudan en la regulación inmunológica en la superficie externa. Las células de Merkel tienen funciones neuroendocrinas. Esta revisión da un repaso general a la estructura y función de tres importantes células de la piel. [Resident dendsuitic cells in the epidermis: Langerhans cells, Merkel cells and Melanocytes (Células résidentes en la epidermis: células de Langerhans, células de Merkel y melanocitos). Abstract— In addition to the keratinocytes, the epidermis contains resident cells of dendritic morphology. These are principally the Langerhans cell, Merkel cell and melanocyte. These cells have a number of different functions in the integument. The melanocyte is responsible for skin pigmentation and protection against UV radiation, and may also play a role in the modulation of cutaneous inflammation. The Langerhans cell aids in the immunological monitoring of the body's external surfaces. The Merkel cell has neuroendocrine functions. This review gives an overview of the structure and function of these three important cells of the skin.     

Canine Epidermal Langerhans Cells Express α and γ but not β Chains of High-Affinity IgE Receptor

Epidermal Langerhans cells (LC) express a high-affinity receptor for IgE (FcεRI), consisting of two chains (α and γ chains) in humans that allows LC to perform Fc receptor-mediated uptake of allergens. We found that canine LC express α and γ chains but not β chain of FcεRI, identical to human but not to mouse LC, which do not express functional FcεRI (only γ chain is expressed). This finding indicates that canine LC have FcεRI-mediated function similar to or identical to human LC, raising the possibility that canine species provides a better model than mouse to understand the pathogenesis of human atopic dermatitis and investigate the therapeutic effect of drugs.     

Characterization of langerhans cells in epidermal sheets along the body of Armadillo (Dasypus novemcinctus)

Armadillos are apparently important reservoirs of Mycobacterium leprae and an animal model for human leprosy, whose immune system has been poorly studied. We aimed at characterizing the armadillo's langerhans cells (LC) using epidermal sheets instead of tissue sections, since the latter restrict analysis only to cut-traversed cells. Epidermal sheets by providing an en face view, are particularly convenient to evaluate dendritic morphology (cells are complete), spatial distribution (regular vs. clustered), and frequency (cell number/tissue area). Lack of anti-armadillo antibodies was overcome using LC-restricted ATPase staining, allowing assessment of cell frequency, cell size, and dendrites extension. Average LC frequency in four animals was 528 LC/mm(2), showing a rather uniform non-clustered distribution, which increased towards the animal's head, while cell size increased towards the tail; without overt differences between sexes. The screening of antibodies to human DC (MHC-II, CD 1a, langerin, CD86) in armadillo epidermal sheets, revealed positive cells with prominent dendritic morphology only with MHC-II and CD86. This allowed us to test DC mobilization from epidermis into dermis under topical oxazolone stimulation, a finding that was corroborated using whole skin conventional sections. We hope that the characterization of armadillo's LC will incite studies of leprosy and immunity in this animal model.     

Protection by cAMP and cGMP phosphodiesterase inhibitors of diazinon-induced hyperglycemia and oxidative/nitrosative stress in rat Langerhans islets cells: Molecular evidence for involvement of non-cholinergic mechanisms

The objective of this study was to study the effects of acute administration of diazinon alone or in combination with two phosphodiesterase (PDE) inhibitors with selectivity to cAMP and cGMP (theophylline and sildenafil, respectively) on oxidative/nitrosative stress biomarkers, including nitric oxide (NO), lipid peroxides (TBARS), total antioxidant power (TAP), and concentration of tumor necrosis factor (TNF-α) in isolated Langerhans islets, plasma glucose and insulin levels, and the activity of plasma cholinesterase (ChE). Examination by different doses of diazinon (15, 30, and 60 mg/kg) in single administration lead us to choose diazinon (30 mg/kg) in combination therapies. Theophylline and sildenafil were used at doses of 25 and 5 mg/kg, respectively. In all diazinon-treated groups, plasma ChE activity and plasma insulin level were significantly decreased and plasma glucose concentration and Langerhans islets TNF-α, TBARS, and NO levels were significantly increased in comparison to controls. The TAP did not change in comparison to control. In combination therapy, both theophylline and sildenafil restored diazinon-induced changes in plasma glucose concentration, Langerhans islets TNF-α, NO, and TBARS concentrations but Langerhans islets TAP, plasma insulin, and ChE levels. It is concluded that diazinon stimulates oxidative/nitrosative stress in Langerhans islets that results in hyperglycemia due to insufficiency of insulin. Altered glucagons/insulin ratio, activated hepatic glucose production/release, and insulin resistance are possible mechanisms. The protective effects of cAMP and cGMP PDE inhibitors in restoration of diazinon-induced oxidative/nitrosative stress and hyperglycemia stress back to their antioxidant potentials that seem to be independent of ChE inhibition.     

Immunoreactivity of cytotoxic T-lymphocyte antigen 2 alpha in mouse pancreatic islet cells

Cells of the pancreatic islets produce several molecules including insulin (beta cells), glucagon (alpha cells), somatostatin (delta cells), pancreatic polypeptide (PP cells), ghrelin (epsilon cells), serotonin (enterochromaffin cells), gastrin (G cells) and small granules of unknown content secreted by the P/D1 cells. Secretion mechanism of some of these molecules is still poorly understood. However, Cathepsin L is shown to regulate insulin exocytosis in beta cells and activate the trypsinogen produced by the pancreatic serous acini cells into trypsin. The structure of the propeptide region of Cathepsin L is homologous to Cytotoxic T-lymphocyte antigen-2 alpha (CTLA-2 alpha) which is also shown to exhibit selective inhibitory activities against Cathepsin L. It was thought that if CTLA-2 alpha was expressed in the pancreas; then, it would be an important regulator of protease activation and insulin secretion. The purpose of this study was, therefore, to examine by immunohistochemistry the cellular localization and distribution pattern of CTLA-2 alpha in the pancreas. Results showed that strong immunoreactivity was specifically detected in the pancreatic islets (endocrine pancreas) but not in the exocrine pancreas and pancreatic stroma. Immunostaining was further performed to investigate more on localization of Cathepsin L in the pancreas. Strong immunoreactivity for Cathepsin L was detected in the pancreatic islets, serous cells and the pancreas duct system. These findings suggest that CTLA-2 alpha may be involved in the proteolytic processing and secretion of insulin through regulation of Cathepsin L and that the regulated inhibition of Cathepsin L may have therapeutic potential for type 1 diabetes.     

Pathways of local angiotensin II generation in islets of Langerhans in Syrian golden hamster fed with high-fat diet

AIM: To investigate the diverse pathways of local angiotensin Ⅱ (Ang Ⅱ) generation in islets of Langerhans in Syrian golden hamsters with dyslipidemia. METHODS: The Syrian golden hamsters were fed with high-fat diet to induce dyslipidemia. Purified islet cells from dyslipidemia and normal Syrian hamsters were prepared and divided into control group, captopril group, chymotrypsin endostatin group, aprotinin group, α-antitrypsin group and captopril+chymotrypsin endostatin group by adding respective reagents into the cultured cells after treated with angiotensin I. The Ang Ⅱ levels in the supernatants of each group were examined by ELISA.RESULTS: Compared with the control animals, Ang Ⅱ levels decreased in all groups with interventions. Compared with the normal hamsters islet cells, the Ang Ⅱ levels in captopril group, chymotrypsin endostatin group, α-antitrypsin group, aprotinin group and captopril+chymotrypsin endostatin group were decreased by 39.98%, 50.10% (P<0.01), 23.04%, 20.85% (P<0.05) and 82.78% (P<0.01), respectively. Compared with high-fat group, the corresponding data were 42.12%, 56.96% (P<0.01), 26.11%, 22.68% (P<0.05) and 83.59% (P<0.01), respectively. The levels of Ang Ⅱ in chymotrypsin group between normal and high-fat diet hamsters were significantly different (P<0.05). CONCLUSION: Under the condition of dyslipidemia, the classic angiotensin-converting enzyme-based pathway and chymotrypsin pathway are still the main approaches of producing Ang Ⅱ in male Syrian hamster islet to produce angiotensin. The effect of chymotrypsin endostatin is comparatively stronger in inhibiting the production of local Ang Ⅱ than the effect of angiotensin-converting enzyme inhibitor.     

Contact Dermatitis in Dogs and Cats: Pathogenesis,Histopathology, Experimental Induction and Case Reports*

Résumé— Une revue de la physiopathologie et de Thistopathologie des dermites de contact par allergie et irritation est présentée. Le rôle des lymphocytes, des cellules de Langerhans, des basophiles et des éosinophiles est discuté. Des résultates précédents non-publiés de dermites de contact expérimentales chez le chien sont présentées. Les résumés des cas cliniques de dermites de contact spontannées chez le chien et le chat présentées lors du 9e congrès de l'AAVD sont inclus. Les cas cliniques sont comparés aux cas expérimentaux et aux aspects histopathologiques décrits chez 1'homme. Des lésions avec un infiltrat riche en éosinophiles ont été retrouvées dans trois cas; une discussion sur la possibilité d'existence d'IgE à la surface des cellules de Langerhans entrainant à la fois une réponse de type I et de type IV chez ces patients est développée. [Walder, E. J., Conroy, J. D. Contact dermatitis in dogs and cats: pathogenesis, histopathology, experimental induction and case reports (Dermite de contact chez le chien et le chat: pathogénie, histopathologie, induction expérimentale et cas cliniques). Resumen— Se revisa la fisiopatología e histopatología de la dermatitis por contacto alérgica y por irritación en la especie humana y en los animales. Se discute el papel de los linfocitos, las células de Langerhans, los basófilos y los eosinófilos. Se presentan datos sobre la dermatitis por contacto alérgica y por irritación en el perro no descritos hasta la fecha. Se incluyen los resumenes de los casos clinicos presentados en las das jornadas de la Academia Americana de Dermatología Veterinaria. Se comparan los casos clinicos con los hallazgos expérimentales en el perro y con las caracteristícas histopatológicas recientemente descritas en la especie humana. En tres casos se descubrieron vesiculo-pústulas con abundantes eosinófilos; se especula con la posibilidad de que células de Langerhens cargadas con IgE induzcan reacciones mixtas de hipersensibilidad de tipo I y IV (“atopia por contacto”). [Walder, E. J., Conroy, J. D. Contact dermatitis in dogs and cats: pathogenesis, histopathology, experimental induction and case reports (Dermatitis por contacto en el perro y en el gato: patogénesis, histopatología, reproducción experimental y casos clínicos). Zusammenfassung— Es erfolgt eine übersicht über Pathophysiologie und Histopothologie der irritativen und allergischen Kontakdermatitis das Mensch und Tier. Es werden die Rollen der Lymphozyton, Langerhans Zellen, basne und eosinophilen Granulozyten diskutiert. Es werden unveröffentlichte Daten über experimentelle irritative und allergische Kontaktdermatitis bei Hunden vorgestellt. Die Zusammenfassungen von Fallstudien spontaner Kontaktdermatitis bei Hund und Katze, veröffentlicht beim 9. Jahrestreffen der American Academy of Veterinary Dermatology werden miteingeschlossen. Die Fallstudien werden mit den experimentellen Ergebnissen beim Hund und mit den klassischen und kürzlich beschriebenen histopatholo-gischen Bildern beim Menschen verglichen. In drei Fällen wurden vesikulopustulöse Veränderungen, reich an ensinophilen Granulozyten, festgestellt; es werden Mutmaßungen über die Möglichkeit von IgE-tregenden Langerhans-Zellen angstellt, die überlappende Typ I- und Typ IV-Reaktionen (“Kontaktatopie”) bei diesen Patienten induzieren. [Contact dermatitis in dogs and cats: pathognesis, histopathology, experimental induction, and case reports (Kontaktdermatitis bei Hund und Katze: Pathogenese, Histopathologie, experimentelle Induktion und Fallstudien). Abstract— The pathophysiology and histopathology of irritant and allergic contact dermatitis in man and animals are reviewed. The roles of lymphocytes, Langerhans cells, basophils and eosinophils are discussed. Previously unreported data on experimental irritant and allergic contact dermatitis in dogs are presented. The abstracts of case reports of spontaneous contact dermatitis in dogs and cats presented at the Ninth Annual American Academy of Veterinary Dermatology Meeting are included. The case reports are compared to the experimental findings in dogs and to classical and recently-described histopathologic features in humans. Eosinophil-rich, vesiculopustular lesions were found in three cases; speculation is made regarding the possibility of lgE-bearing Langerhans cells inducing overlap Type I and Type IV hypersensitivity reactions (“contact atopy”) in these patients.     

Feline Langerhans cells migrate from skin and vaginal mucosa to regional lymph nodes during experimental contact sensitization with fluorescein isothiocyanate

Recently, feline Langerhans cells (LC) were immunophenotypically characterized as CD1a+, CD4+, CD18+, CD53+ and MHC II+ cells. In mice, these cells are known to internalize antigens and to migrate to the lymph nodes (LN). In the cat, we have investigated the migration of LC from the skin and vaginal mucosa to regional LN in response to chemical exposure (fluorescein isothiocyanate). Three days after the administration of a FITC solution on the posterior limb of two male cats and in the vagina of one female, a biopsy was carried out on the draining LN of the sensitized zones. Immunostaining with monoclonal antibodies anti-CD79, anti-CD8, and antibodies recognizing LC was performed on cytospins and frozen sections of LN and showed that a majority of FITC+ cells displayed a LC immunophenotype and were localized in T-cell areas, but not in follicular areas. These results are the first evidence of migration of feline LC from skin and vaginal mucosa to the regional LN.