Aberrantly activated TAK1 links neuroinflammation and neuronal loss in Alzheimer's disease mouse models.

Neuroinflammation is causally associated with Alzheimer's disease (AD) pathology. Reactive glia cells secrete various neurotoxic factors that impair neuronal homeostasis eventually leading to neuronal loss. Although the glial activation mechanism in AD has been relatively well studied, how it perturbs intraneuronal signaling, which ultimately leads to neuronal cell death, remains poorly understood. Here, we report that compound stimulation with the neurotoxic factors TNF and glutamate aberrantly activates neuronal TAK1 (also known as MAP3K7), which promotes the pathogenesis of AD in mouse models. Glutamate-induced Ca2+ influx shifts TNF signaling to hyper-activate TAK1 enzymatic activity through Ca2+/calmodulin-dependent protein kinase II, which leads to necroptotic cellular damage. Genetic ablation and pharmacological inhibition of TAK1 ameliorated AD-associated neuronal loss and cognitive impairment in the AD model mice. Our findings provide a molecular mechanism linking cytokines, Ca2+ signaling and neuronal necroptosis in AD.

Comparison of selected cytomorphological features of canine pemphigus foliaceus and superficial pyoderma.

BACKGROUND: Cytological detection of acantholytic keratinocytes (acantholytic cells [AC]) helps to identify canine pemphigus foliaceus (cPF) yet AC also occurs in superficial pyoderma (SP), the main differential diagnosis. HYPOTHESIS/OBJECTIVES: To compare selected cytomorphological features of cPF and SP and to establish cytological diagnostic criteria that could differentiate cPF from SP. ANIMALS: 40 and 51 client-owned dogs with PF and SP, respectively. MATERIALS AND METHODS: Impression smears from cPF (64), impetigo (40) and exfoliative superficial pyoderma (ESP) (17) samples were stained with Romanowsky stain, randomised, blinded and evaluated by two investigators independently. The entire sample was screened (×500 or ×1000 magnification) for round (AC1), boat (AC2) and raft AC, eosinophils and bacteria. Interobserver agreements were calculated. RESULTS: The average number of the 10 highest ×500 fields for AC1 and AC2 was significantly higher in PF than SP (p < 0.0001; Kruskal-Wallis test). Rafts and eosinophils were more common in PF than SP (p < 0.0001; chi-square test), while bacteria were rare in PF (5%; p < 0.0001; chi-square test). Observations between the experienced and novice investigators were highly correlated. An ROC analysis identified five AC1/×500-magnification field as a suitable cut-off value for predicting PF diagnosis. This cut-off value was tested by two additional investigators, who identified sensitivity of 84%-100%, specificity of 95%-97% and accuracy of 95%-96% for the diagnosis of cPF. CONCLUSIONS AND CLINICAL RELEVANCE: Criterion-based impression smear cytological evaluation can provide strong evidence to support the clinical diagnosis. Acantholytic cell morphology varies in cPF and SP, and experience can improve accuracy in cytological differentiation.

Spontaneous autoimmune subepidermal blistering diseases in animals: a comprehensive review.

Autoimmune subepidermal blistering diseases (AISBDs) are rare skin disorders of animals that were first identified in dogs but several AISBDs are now recognised in other companion animal species. Most AISBDs in animals are homologues of the human diseases and are thought to share similar pathomechanisms of epidermal and/or mucosal blister formation caused by autoantibodies targeting structural proteins of the basement membrane zone (BMZ). Disruption of their structural function by the autoantibodies and/or recruited inflammation leads to BMZ fragility, which presents clinically as vesicles, bullae and, later, deep erosions and ulcers. Canine AISBDs are the best characterised, particularly the more common variants such as mucous membrane pemphigoid (48%), epidermolysis bullosa acquisita (EBA) (26%), and bullous pemphigoid (10%). Exceedingly rare AISBDs in the dog are junctional EBA, mixed AISBD, type-1 bullous systemic lupus erythematosus, linear IgA dermatosis, and pemphigus gestationis. The diagnosis of a specific AISBD is made by combining the clinical features (breed, age, lesion distribution) with histological evidence of subepithelial clefting, but not all AISBDs can be differentiated in this manner and specialised immunological testing is required. This latter, unfortunately, is not readily available and, therefore, the specific AISBD diagnosis often remains unconfirmed. While this limits further understanding of these diseases, it does not prevent clinicians from treating their patients, as the treatment approaches are similar for the different AISBDs in dogs. This review primarily focuses on canine AISBDs, the species for which these diseases have been best characterised, and shorter descriptions of variants in other species are also provided.

Retrospective analysis of histologic lesions in captive arachnids.

Invertebrates, including arachnids, are a common taxon in zoological collections. Invertebrate medicine and pathology are emerging subspecialties, but there is limited reference material or published resources describing histologic lesions in arachnids. Histopathology of 26 captive arachnids (20 spiders and 6 scorpions) from institutional collections was reviewed. Most animals were found dead with limited clinical signs. Tissues evaluated included body wall (cuticle and epidermis), skeletal muscle, book lungs, digestive tract (pharynx, esophagus, sucking stomach, midgut tube, midgut diverticula, and stercoral pocket), central and peripheral nervous system, heart, hemolymph vessels and sinuses, Malpighian tubules, coxal glands, and gonads. Inflammation was frequent (24/26, 92%), and seen in multiple organs (18/24, 75%) with the midgut diverticulum most commonly affected (14/24, 58%) followed by the book lungs (13/24 arachnids, 54%), and body wall (8/24 arachnids, 33%). Inflammation comprised hemocyte accumulation, hemocytic coagula, melanization, and nodulation. Infectious agents, including bacteria (11/26, 42%), fungi (10/26, 38%), and parasites (2/26, 8%), were seen within inflammatory aggregates. Coinfection with multiple infectious agents was common (6/24, 25%). No etiologic agent was identified in 7/24 (29%) cases with inflammatory lesions. Lesions suggestive of decreased nutritional status or increased metabolic rate included midgut diverticula atrophy in 11/26 (42%) animals and skeletal muscle atrophy in 6/26 (23%) animals. Atrophic lesions were seen in combination with infection (8/11, 73%), pregnancy (2/11, 18%), male sex (2/11, 18%), or without other lesions (1/11, 9%). Other suspected contributors to death included dysecdysis-associated trauma (2/26, 8%) and uterine intussusception (1/26, 4%). No animals had neoplasia.

Histopathological characterisation of trunk-dominant canine pemphigus foliaceus, and comparison with classic facial and insecticide-triggered forms.

BACKGROUND: While the clinical features were described recently, the histopathological characterisation of trunk-dominant canine pemphigus foliaceus (PF) is lacking, and whether it differs from classic facial or insecticide-triggered PF is unknown. HYPOTHESIS/OBJECTIVES: This study describes the histopathological findings of trunk-dominant PF, and compares the results to classic facial and insecticide-triggered PF. ANIMALS: Skin biopsies from 103 dogs with clinically characterised trunk-dominant (n = 33), classic facial (n = 26) and insecticide-triggered PF (n = 44) were included. MATERIALS AND METHODS: Histological sections, randomised and blinded, were scored for over 50 morphological parameters of pustules, epidermis, dermis, adnexa and crusts. Intact pustule area and width were measured by digital microscopy. RESULTS: In trunk-dominant PF, 77 intact pustules were predominantly subcorneal (0.0019-1.940 mm2 area, 0.0470-4.2532 mm wide), and contained from one to over 100 acantholytic keratinocytes. Pustules had boat acantholytic cells, corneocytes, perinuclear eosinophilic rings, neutrophil rosettes, acantholytic cell necrosis, rafts, cling-ons and/or eosinophils. Peripustular epidermal spongiosis, necrosis and lymphocyte exocytosis occurred, as did follicular pustules. Mixed dermal inflammation often contained eosinophils. Trunk-dominant PF did not differ from the other PF groups except for few parameters, such as having fewer rafts (p = 0.003). Additional autoimmune inflammatory patterns occurred in all PF groups. CONCLUSIONS AND CLINICAL RELEVANCE: Trunk-dominant PF and other canine PF variants are histologically similar, which indicates shared pathomechanisms. The identification of common boat acantholytic cells and corneocyte separation has implications for the mechanisms of acantholysis. The diversity of histopathological and polyautoimmunity features support complicated immune mechanisms. Finally, results indicate that diagnostic biopsies cannot differentiate between these PF variants in dogs.

Hyperkeratotic erythema multiforme variant in 17 dogs.

BACKGROUND: A new canine subgroup defined as 'old-dog' or 'hyperkeratotic' erythema multiforme (HKEM) with marked hyperkeratosis and parakeratosis has been proposed without any detailed description of larger case series. OBJECTIVES: We report herein the signalment, clinical signs, treatment outcome, and histopathological and immunological findings in 17 dogs with HKEM. ANIMALS: Inclusion criteria were the presence of (i) scaly skin lesions with or without crusting; and (ii) microscopic lesions typical of EM (i.e. a panepidermal cytotoxic lymphocytic dermatitis with or without basal keratinocyte apoptosis); and (iii) microscopic ortho- and/or parakeratotic hyperkeratosis affecting the interfollicular epidermis. MATERIALS AND METHODS: Clinical questionnaires and skin biopsies were reviewed. Polymerase chain reactions for epidermotropic viruses and direct immunofluorescence were performed. RESULTS: Various breeds were affected with an over-representation of males in their mid-to-late adulthood (median age 9 years). Generalised skin lesions included multifocal-to-coalescing, linear and annular macules and plaques with erythema and adherent firm crusting. Microscopic lesions were specific for EM and featured prominent superficial epidermal apoptosis with lymphocytic satellitosis and parakeratosis. No drug triggers were identified. Polymerase chain reactions for canine herpesvirus polymerase gene, canine parvovirus and canine distemper virus were negative in all HKEM and canine erosive EM (15 dogs) biopsies. Lesions failed to respond to oral and/or topical antimicrobials. Complete remission of signs was achieved in 9 of 17 dogs (53%) using immunosuppressive regimens. CONCLUSIONS AND CLINICAL RELEVANCE: Hyperkeratotic erythema multiforme (HKEM) is a chronic, persistent and clinically distinctive erythema multiforme (EM) variant that differs from 'classic' vesiculobullous erosive-to-ulcerative EM in dogs.

Pulmonary exposure of mice to ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX) suppresses the innate immune response to carbon black nanoparticles and stimulates lung cell proliferation.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) have been associated with respiratory diseases in humans, yet the mechanisms through which PFAS cause susceptibility to inhaled agents is unknown. Herein, we investigated the effects of ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), an emerging PFAS, on the pulmonary immune response of mice to carbon black nanoparticles (CBNP). We hypothesized that pulmonary exposure to GenX would increase susceptibility to CBNP through suppression of innate immunity. METHODS: Male C57BL/6 mice were exposed to vehicle, 4 mg/kg CBNP, 10 mg/kg GenX, or CBNP and GenX by oropharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) was collected at 1 and 14 days postexposure for cytokines and total protein. Lung tissue was harvested for histopathology, immunohistochemistry (Ki67 and phosphorylated (p)-STAT3), western blotting (p-STAT3 and p-NF-κB), and qRT-PCR for cytokine mRNAs. RESULTS: CBNP increased CXCL-1 and neutrophils in BALF at both time points evaluated. However, GenX/CBNP co-exposure reduced CBNP-induced CXCL-1 and neutrophils in BALF. Moreover, CXCL-1, CXCL-2 and IL-1ß mRNAs were increased by CBNP in lung tissue but reduced by GenX. Western blotting showed that CBNP induced p-NF-κB in lung tissue, while the GenX/CBNP co-exposed group displayed decreased p-NF-κB. Furthermore, mice exposed to GenX or GenX/CBNP displayed increased numbers of BALF macrophages undergoing mitosis and increased Ki67 immunostaining. This was correlated with increased p-STAT3 by western blotting and immunohistochemistry in lung tissue from mice co-exposed to GenX/CBNP. CONCLUSIONS: Pulmonary exposure to GenX suppressed CBNP-induced innate immune response in the lungs of mice yet promoted the proliferation of macrophages and lung epithelial cells.

Cutaneous epitheliotropic lymphosarcoma in a captive white catfish (Ameiurus catus Linnaeus).

A wild caught white catfish (Ameiurus catus Linnaeus) developed multiple cutaneous masses. Cytology revealed neoplastic lymphocytes and microscopy confirmed dermal infiltration with epitheliotropism in the epidermis, oral mucosa, and cornea, without internal organ involvement. Transmission electron microscopy did not identify viral particles. Histopathology supported cutaneous epitheliotropic lymphosarcoma, a condition most commonly reported in mammals. This is the first reported case of cutaneous epitheliotropic lymphosarcoma in an ictalurid and one of the few published cases of this condition in any fish species.

Trunk-dominant and classic facial pemphigus foliaceus in dogs - comparison of anti-desmocollin-1 and anti-desmoglein-1 autoantibodies and clinical presentations.

BACKGROUND: Canine trunk-dominant pemphigus foliaceus (PF) is mentioned rarely in the literature. HYPOTHESIS/OBJECTIVES: The goal of this study was to provide clinical description of trunk-dominant PF and to demonstrate the prevalence of serum antikeratinocyte, anti-desmocollin-1 (DSC1) and anti-desmoglein-1 (DSG1) antibodies, and determine their diagnostic value in this particular PF phenotype. MATERIALS AND METHODS: Clinically relevant information was collected from 31, 25 and 34 dogs with trunk-dominant and facial PF and superficial pyoderma (SP), respectively. Sera from these dogs were tested for antikeratinocyte, anti-DSC1 and anti-DSG1 antibodies using indirect immunofluorescence on canine tissues and DSC1- and DSG1-transfected cells. Sera from healthy dogs and dogs with clinically irrelevant diseases served as controls. RESULTS: Footpad involvement and grouped/polycyclic lesion organisation were identified as features of both PF phenotypes, and not of SP. Antikeratinocyte immunoglobulin (Ig)G was not specific for canine PF. By contrast, antigen-specific IgG was detected only in PF sera; anti-DSC1 IgG in 100% and 58% of dogs with facial and trunk-dominant PF, respectively, and anti-DSG1 IgG in 7% of dogs with trunk-dominant PF only. CONCLUSIONS: Trunk-dominant PF shares DSC1 as a major autoantigen with facial PF. The ability to detect anti-DSC1 IgG is lower in trunk-dominant PF, yet despite the lower sensitivity, the positive predictive value and accuracy of this particular anti-DSC1 IgG test are high. A negative test result, however, cannot exclude the diagnosis, and characteristic clinical features such as footpad involvement and/or grouped/polycyclic lesions must be considered when distinguishing trunk-dominant PF from its most relevant differential diagnosis: SP.

Contexte - Le pemphigus foliacé (PF) dominant le tronc chez le chien est rarement mentionné dans la littérature. Hypothèse/Objectifs - Le but de cette étude était de fournir une description clinique du PF dominant le tronc et de démontrer la prévalence des anticorps sériques anti-kératinocytes, anti-desmocolline-1 (DSC1) et anti-desmogléine-1 (DSG1), et de déterminer leur valeur diagnostique dans ce phénotype particulier de PF. Matériels et méthodes - Des informations cliniquement pertinentes ont été recueillies auprès de 31, 25 et 34 chiens atteints respectivement de PF à dominante tronculaire et faciale et de pyodermite superficielle (SP). Les sera de ces chiens ont été testés pour les anticorps anti-kératinocytes, anti-DSC1 et anti-DSG1 en utilisant l'immunofluorescence indirecte sur des tissus canins et des cellules transfectées avec DSC1 et DSG1. Des sera de chiens sains et de chiens atteints de maladies cliniquement non pertinentes ont servi de témoins. Résultats - L'implication du coussinet plantaire et l'organisation des lésions groupées / polycycliques ont été identifiées comme des caractéristiques des deux phénotypes PF, et non de SP. L'immunoglobuline antikératinocytaire (Ig)G n'était pas spécifique du PF canin. En revanche, l'IgG spécifique de l'antigène n'a été détectée que dans les sera de PF ; IgG anti-DSC1 chez 100 % et 58 % des chiens atteints de PF faciale et tronc-dominante, respectivement, et anti-DSG1 IgG chez 7 % des chiens avec PF tronc-dominant uniquement. Conclusions - Le PF à dominante tronculaire partage DSC1 comme auto-antigène majeur avec le PF facial. La capacité à détecter les IgG anti-DSC1 est plus faible chez les PF à dominante tronculaire, mais malgré la sensibilité plus faible, la valeur prédictive positive et la précision de ce test IgG anti-DSC1 particulier sont élevées. Cependant, un résultat de test négatif ne peut pas exclure le diagnostic, et les caractéristiques cliniques caractéristiques telles que l'atteinte du coussinet plantaire et/ou les lésions groupées/polycycliques doivent être prises en compte lors de la distinction entre la PF à dominante tronculaire et son diagnostic différentiel le plus pertinent : la SP.

Introducción- el pénfigo foliáceo (PF) de distribución truncal predominante se describe raramente n la literatura. Hipótesis/Objetivos- el objetivo de este estudio fue proporcionar una descripción clínica del PF truncal y demostrar la prevalencia de anticuerpos séricos antiqueratinocitos, antidesmocolina-1 (DSC1) y antidesmogleína-1 (DSG1), y determinar su valor diagnóstico en este fenotipo PF particular. Materiales y métodos- se recopiló información clínicamente relevante de 31, 25 y 34 perros con PF dominante truncal, PF dominante facial y pioderma superficial (PS), respectivamente. Los sueros de estos perros se analizaron en busca de anticuerpos antiqueratinocitos, anti-DSC1 y anti-DSG1 mediante inmunofluorescencia indirecta en tejidos caninos y células transfectadas con DSC1 y DSG1. Sueros de perros sanos y perros con enfermedades clínicamente irrelevantes sirvieron como controles. Resultados- la afectación de la almohadilla plantar y la organización de lesiones agrupadas/policíclicas se identificaron como características de ambos fenotipos de PF y no de SP. La inmunoglobulina (Ig)G antiqueratinocitos no fue específica para la PF canina. Por el contrario, la IgG específica de antígeno se detectó solo en sueros PF; IgG anti-DSC1 en el 100 % y el 58 % de los perros con PF predominante en la cara y el tronco, respectivamente, y IgG anti-DSG1 en el 7 % de los perros con PF predominante en el tronco solamente. Conclusiones- el PF dominante truncal comparte DSC1 como un autoantígeno importante con el PF facial. La capacidad para detectar IgG anti-DSC1 es menor en la PF dominante truncal; sin embargo, a pesar de la menor sensibilidad, el valor predictivo positivo y la precisión de esta prueba de IgG anti-DSC1 en particular son altos. Sin embargo, un resultado negativo de la prueba no puede excluir el diagnóstico, y deben tenerse en cuenta las características clínicas, como la afectación de las almohadillas plantares y/o las lesiones agrupadas/policíclicas, al distinguir la PF dominante truncal de su diagnóstico diferencial más relevante: SP.

Contexto - O pênfigo foliáceo (PF) canino predominante no tronco é raramente relatado na literatura. Hipótese/Objetivos - O objetivo deste estudo foi apresentar a descrição clínica do PF predominante no tronco e demonstrar a prevalência de anticorpos anti-queratinócitos, anti-desmocolina-1 (DSC1) e anti-desmogleína-1 (DSG1), e determinar o seu potencial diagnóstico neste tipo particular de PF. Materiais e métodos - Informações clinicamente relevantes foram coletadas de 31, 25 e 34 cães com PF predominante no tronco, PF facial e piodermite superficial (PS), respectivamente. Os soros destes cães foram testados para anticorpos anti-queratinócitos, anti-DSC1 e anti-DSG1 utilizando imunofluorescência indireta em tecidos caninos e em células DSC1 e DSG1 transfectadas. Os soros de cães saudáveis e cães com doenças clinicamente irrelevantes serviram de controle. Resultados - O acometimento dos coxins e a organização agrupada/policíclica das lesões foram identificadas como características de ambos os fenótipos de PF, não de PS. A imunoglobulina (Ig)G anti-queratinócitos não foi específica para PF. Em contraste, IgG antígeno-específica foi detectada apenas no soro de PF; IgG anti-DSC1 em 100% e 58% dos cães com PF facial e predominante no tronco, respectivamente, e IgG anti-DSG1 em 7% dos cães somente acometidos pelo PF predominante no tronco. Conclusões - O PF predominante no tronco compartilha DSC1 como um autoantígeno principal com PF facial. A capacidade de detectar IgG anti-DSC1 é menor no PF predominante no tronco, mas apesar da sensibilidade mais baixa, o valor preditivo positivo e a precisão do teste IgG anti-DSC1 específico são altos. Um resultado de teste negativo, no entanto, não pode excluir o diagnóstico, e características clínicas típicas, como envolvimento do coxim plantar e/ou lesões agrupadas/policíclicas, devem ser consideradas ao distinguir PF predominante no tronco de seu diagnóstico diferencial mais relevante: PS.

Localised erythema multiforme-like reaction confined to a region of clipper burn in a dog.

Localised erythema multiforme (LEM) is only reported to occur in humans and not in domestic species. This case report describes the clinical and histopathological features of LEM-like reaction in a dog, confined to a region of clipper burn.

L'érythème polymorphe localisé (LEM) n'est signalé que chez l'homme et non chez les animaux domestiques. Ce cas clinique décrit les caractéristiques cliniques et histopathologiques d'une réaction de type LEM chez un chien, localisé sur une région de brûlure de tondeuse.

El eritema multiforme localizado (LEM) sólo se ha descrito en seres humanos y no en especies domésticas. Este artículo describe un caso de un perro con una lesión confinada a una zona de quemadura por un rasurador cuyas características clínicas e histopatológicas fueron similares a LEM.

O eritema multiforme localizado (EML) é relatado apenas em humanos e não em animais domésticos. Este relato de caso descreve as características clínicas e histopatológicas de uma reação EML-símile em um cão, limitada a uma região de queimadura por lâmina de tosa.

Three-dimensional (3D) imaging of lipids in skin tissues with infrared matrix-assisted laser desorption electrospray ionization (MALDESI) mass spectrometry.

Three-dimensional (3D) mass spectrometry imaging (MSI) has become a growing frontier as it has the potential to provide a 3D representation of analytes in a label-free, untargeted, and chemically specific manner. The most common 3D MSI is accomplished by the reconstruction of 2D MSI from serial cryosections; however, this presents significant challenges in image alignment and registration. An alternative method would be to sequentially image a sample by consecutive ablation events to create a 3D image. In this study, we describe the use of infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) in ablation-based 3D MSI for analyses of lipids within fresh frozen skin tissue. Depth resolution using different laser energy levels was explored with a confocal laser scanning microscope to establish the imaging parameters for skin. The lowest and highest laser energy level resulted in a depth resolution of 7 µm and 18 µm, respectively. A total of 594 lipids were putatively detected and detailed lipid profiles across different skin layers were revealed in a 56-layer 3D imaging experiment. Correlated with histological information, the skin structure was characterized with differential lipid distributions with a lateral resolution of 50 µm and a z resolution of 7 µm.

International Guidelines for Veterinary Tumor Pathology: A Call to Action.

Standardization of tumor assessment lays the foundation for validation of grading systems, permits reproducibility of oncologic studies among investigators, and increases confidence in the significance of study results. Currently, there is minimal methodological standardization for assessing tumors in veterinary medicine, with few attempts to validate published protocols and grading schemes. The current article attempts to address these shortcomings by providing standard guidelines for tumor assessment parameters and protocols for evaluating specific tumor types. More detailed information is available in the Supplemental Files, the intention of which is 2-fold: publication as part of this commentary, but more importantly, these will be available as "living documents" on a website (www.vetcancerprotocols.org), which will be updated as new information is presented in the peer-reviewed literature. Our hope is that veterinary pathologists will agree that this initiative is needed, and will contribute to and utilize this information for routine diagnostic work and oncologic studies. Journal editors and reviewers can utilize checklists to ensure publications include sufficient detail and standardized methods of tumor assessment. To maintain the relevance of the guidelines and protocols, it is critical that the information is periodically updated and revised as new studies are published and validated with the intent of providing a repository of this information. Our hope is that this initiative (a continuation of efforts published in this journal in 2011) will facilitate collaboration and reproducibility between pathologists and institutions, increase case numbers, and strengthen clinical research findings, thus ensuring continued progress in veterinary oncologic pathology and improving patient care.

Bullous amyloidosis in a horse: first description in veterinary medicine.

BACKGROUND: Bullous amyloidosis is a rare disease in humans that has not been described in a veterinary species in the peer-reviewed literature. The human disease is characterised by haemorrhagic vesicles and bullae on the skin and mucosae, which form due to amyloid deposition. HYPOTHESIS/OBJECTIVES: To describe the clinical features, laboratory analysis and histopathological features of an unique presentation of bullous disease in a horse. ANIMALS: A 17-year-old thoroughbred mare presented for weight loss and severe oral cavity ulcers. METHODS AND MATERIALS: Investigations involved haematological evaluation, chemistry profiles, gastroscopy and serum protein electrophoresis, and, postmortem, histopathological evaluation, Congo-red staining and transmission electron microscopy (TEM). RESULTS: Haemorrhagic vesicles and bullae occurred on the mucosa of the oral cavity, lips, oesophagus and stomach, and much less the muzzle, face and mucocutaneous areas of the perineum, where scarring was evident. Histopathological evaluation and Congo-red staining confirmed the presence of amyloid deposits in dermis and submucosa, in association with vesicle and bulla formation, consistent with bullous amyloidosis. TEM confirmed amyloid fibril deposition in the dermis and along the basement membrane zone. Clefts occurred in the superficial dermis and submucosa, which explained haemorrhage and scarring. The presence of a polyclonal gammopathy and the rapid abolishment of Congo-red staining with performate pretreatment supported serum amyloid A and secondary amyloidosis. CONCLUSION AND CLINICAL IMPORTANCE: Bullous amyloidosis is a novel disease of the horse and a newly recognised differential for bullous disease, for which the haemorrhagic nature of bullae, scarring and deep secondary ulcers are considered clinical clues to the condition.

Canine junctional epidermolysis bullosa due to a novel mutation in LAMA3 with severe upper respiratory involvement.

BACKGROUND: Junctional epidermolysis bullosa (JEB) is a group of congenital blistering skin diseases characterized by clefting through the lamina lucida of the basement membrane zone. OBJECTIVES: To characterize the clinical and morphological features of a congenital mechanobullous disease in a litter of puppies with severe upper respiratory involvement, and to identify an associated genetic variant. ANIMALS: Five of eight puppies in an Australian cattle dog cross-bred litter showed signs of skin fragility. Three were stillborn and one died at one month of age. The two surviving puppies were presented with blistering skin disease and severe respiratory distress. Additionally, one unaffected sibling was examined and blood was obtained for genetic testing. METHODS AND MATERIALS: Post-mortem examination, histopathological evaluation and electron microscopy were performed. Whole genome sequencing (WGS) of one affected puppy was compared to a database of 522 dogs of 55 different breeds for variant analysis. Sanger sequencing of one additional affected and one unaffected sibling confirmed the variant. RESULTS: Clinically, severe mucocutaneous ulcers occurred in frictional areas with claw sloughing. Histopathological results revealed subepidermal clefts and electron microscopy confirmed the split in the lamina lucida. Post-mortem examination documented extensive pharyngeal and laryngeal lesions with granulation tissue and fibrinous exudate obscuring the airway. Moderate tracheal hypoplasia contributed. The WGS revealed a novel missense variant in the laminin α3-chain XP_537297.2p(Asp2867Val), with an autosomal recessive mode of inheritance. CONCLUSIONS AND CLINICAL RELEVANCE: A novel variant in LAMA3 caused a generalized and severe phenotype of JEB with an unique clinical presentation of upper airway obstruction.

Deep pemphigus (pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus) in dogs, cats and horses: a comprehensive review.

Pemphigus is the term used to describe a group of rare mucocutaneous autoimmune bullous diseases characterized by flaccid blisters and erosions of the mucous membranes and/or skin. When the autoantibodies target desmosomes in the deep layers of the epidermis, deep pemphigus variants such as pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus develop. In this article, we will review the signalment, clinical signs, histopathology and treatment outcome of pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus in dogs, cats and horses; where pertinent, we compare the animal diseases to their human homologue. Canine, feline and equine pemphigus vulgaris, pemphigus vegetans and paraneoplastic pemphigus have many features similar to the human counterpart. These chronic and often relapsing autoimmune dermatoses require aggressive immunosuppressive therapy. In animals, the partial-to-complete remission of pemphigus vulgaris and pemphigus vegetans has been achieved with high dose glucocorticoid therapy, with or without adjunct immunosuppressants; the prognosis is grave for paraneoplastic pemphigus.

A Subset of Equine Gastric Squamous Cell Carcinomas Is Associated With Equus Caballus Papillomavirus-2 Infection.

Squamous cell carcinoma (SCC) is the most common neoplasm of the equine stomach. However, the mechanisms underlying malignant transformation are unknown. As Equus caballus papillomavirus-2 (EcPV-2) is a likely cause of some genital SCCs, we hypothesized that EcPV-2 is associated with a subset of equine gastric SCCs. To this aim, we performed polymerase chain reaction (PCR) and in situ hybridization (ISH) for EcPV-2 E6/ E7 oncogenes on 11 gastric SCCs and on gastric samples from 15 control horses with no SCC. PCR for EcPV-2 was positive in 7/11 (64%) gastric SCCs; non-SCC gastric samples were all negative. Intense hybridization signals for EcPV-2 E6/E7 nucleic acid were detected by ISH within tumor cells in 5/11 (45%) gastric SCCs, including distant metastases. No hybridization signals were detected within any of the non-SCC gastric cases. This study provides support for a potential association between EcPV-2 infection and a subset of equine gastric SCC.

Rapid response of hyperkeratotic erythema multiforme to oclacitinib in two dogs.

BACKGROUND: Hyperkeratotic erythema multiforme (HKEM) is a clinically distinct dermatosis and poorly characterized syndrome, comprised of hyperkeratotic plaques with variable symmetry and apoptosis similar to "classic" erosive canine EM. Hyperkeratotic EM has a protracted clinical course and, although treatments with glucocorticoids, azathioprine and/or ciclosporin have been tried, rates of remission are low. OBJECTIVES: To describe successful treatment of HKEM in two dogs using oclacitinib. ANIMALS: A 7-year-old, spayed Havanese dog (Case 1) and a 1-year-old, intact cryptorchid Dachshund dog (Case 2). METHODS: Case characterization and clinical diagnoses were based on lesion character, surgical biopsy, cytological evaluation, culture, direct immunofluorescence (DIF) and expected responses to treatments. RESULTS: Both cases exhibited multifocal, often symmetrical hyperkeratotic plaques with adherent scale. Histological findings revealed prominent epidermal hyperplasia, parakeratotic hyperkeratosis, lymphocytic dermatitis and transepidermal apoptosis with lymphocytic satellitosis. DIF revealed fine, patchy IgG, IgM and IgA basement membrane deposits (Case 2). Both dogs exhibited rapid improvement with oral oclacitinib (0.6-0.9 mg/kg twice daily) with a complete remission of clinical signs observed in 12 and seven weeks in cases 1 and 2, respectively. CONCLUSION AND CLINICAL IMPORTANCE: Oclacitinib could be considered as a fast-acting and effective treatment option for HKEM in dogs.

Cutaneous polyautoimmunity in two unrelated dogs: pemphigus foliaceus and generalized discoid lupus erythematosus.

BACKGROUND: Polyautoimmunity, the concurrent expression of two or more distinct autoimmune diseases (ADs) in a single individual, is a known phenomenon in humans and has been rarely reported in dogs. To the best of the authors' knowledge, comorbid pemphigus foliaceus (PF) and generalized discoid lupus erythematosus (GDLE) has not been reported in dogs. HYPOTHESIS/OBJECTIVES: To describe the clinical, histological and immunological features and treatment outcome of two unrelated dogs with comorbid PF and GDLE. ANIMALS: One 10-year-old, spayed German shepherd dog and one 8-year-old, castrated American Staffordshire terrier presented for evaluation of a symmetrical, facial- and/or pedal-dominant pustular dermatitis with concurrent, truncal scaly plaques. METHODS: For each dog, clinicopathological characterization included physical examination, lesion cytological evaluation, bacterial culture and sensitivity testing, skin histopathological investigation and direct and indirect immunofluorescence testing. Additional diagnostic imaging and haematological testing was performed to exclude extracutaneous disease. RESULTS: Both dogs exhibited lesions clinically and histologically compatible with PF and GDLE. Moreover, one dog exhibited generalized leucotrichia and chronic superficial keratitis. Remission was achieved with immunosuppressive dosages of prednisolone [high-dose pulse (Case 1) or standard immunosuppressive dosage (Case 2)] and ciclosporin (5-6 mg/kg/day). Tissue-bound antikeratinocyte immunoglobulin (Ig)G and IgM were detected in both dogs. A weak basement membrane zone deposit of C3 was seen in one dog. Circulating antikeratinocyte and anti-desmocollin-1 IgG were detected in one dog. CONCLUSIONS AND CLINICAL IMPORTANCE: Cutaneous polyautoimmunity can occur in the dog. Depending on the specific disease combinations, overlapping clinical features may present diagnostic and/or therapeutic challenges. Moreover, these cases should be monitored for development of additional cutaneous or extra-cutaneous AD(s).

C/EBPß suppresses keratinocyte autonomous type 1 IFN response and p53 to increase cell survival and susceptibility to UVB-induced skin cancer.

p53 is activated by DNA damage and oncogenic stimuli to regulate senescence, apoptosis and cell-cycle arrest, which are essential to prevent cancer. Here, we utilized UVB radiation, a potent inducer of DNA damage, p53, apoptosis and skin cancer to investigate the mechanism of CCAAT/enhancer binding protein-ß (C/EBPß) in regulating p53-mediated apoptosis in keratinocytes and to test whether the deletion of C/EBPß in epidermis can protect mice from UVB-induced skin cancer. UVB-treatment of C/EBPß skin conditional knockout (CKOß) mice increased p53 protein levels in epidermis and enhanced p53-dependent apoptotic activity 3-fold compared with UVB-treated control mice. UVB increased C/EBPß levels through a p53-dependent pathway and stimulated the formation of a C/EBPß-p53 protein complex; knockdown of C/EBPß increased p53 protein stability in keratinocytes. These results suggest a p53-C/EBPß feedback loop, whereby C/EBPß, a transcriptional target of a p53 pathway, functions as a survival factor by negatively regulating p53 apoptotic activity in response to DNA damage. RNAseq analysis of UVB-treated CKOß epidermis unexpectedly revealed that type 1 interferon (IFN) pathway was the most highly enriched pathway. Numerous pro-apoptotic interferon stimulated genes were upregulated including some known to enhance p53 apoptosis. Our results indicate that p53 and IFN pathways function together in response to DNA damage to result in the activation of extrinsic apoptosis pathways and caspase 8 cleavage. Last, we observed CKOß mice were resistant to UVB-induced skin cancer. Our results suggest that C/EBPß represses apoptosis through keratinocyte autonomous suppression of the type 1 IFN response and p53 to increase cell survival and susceptibility to UVB-induced skin cancer.

Autoimmune diseases affecting skin melanocytes in dogs, cats and horses: vitiligo and the uveodermatological syndrome: a comprehensive review.

Autoimmune dermatoses targeting melanocytes have gained attention in human medicine due to their progressive nature and the social impact suffered by affected individuals. In veterinary medicine, vitiligo and the uveodermatological syndrome are the two autoimmune diseases that are known to affect skin melanocytes.In the first part of this article, we will review the signalment, clinical signs, histopathology and the treatment outcome of vitiligo in dogs, cats and horses; where pertinent, we compare the animal diseases to their human homologue. In a similar fashion, the information on the uveodermatological syndrome in dogs is reviewed and, where relevant, it is compared to the Vogt-Koyanagi-Harada (VKH) syndrome in humans.Canine, feline and equine vitiligo have many features that mirror their human counterparts. The most effective treatment and outcome of vitiligo in animals remain unclear. The canine uveodermatological syndrome resembles the incomplete VKH variant in humans; for affected individuals, an immediate diagnosis and aggressive treatment are crucial to prevent the development of blindness.