Caracterização clínica e histopatológica das dermatites alérgicas em cães / Clinical and histopathological characterization of allergic dermatitis in dogs

Descrevem-se as características clínicas e histopatológicas da dermatite alérgica diagnosticada em cães da região metropolitana de João Pessoa, Paraíba. Durante o período de setembro de 2014 a setembro de 2015, um total de 90 cães com lesões cutâneas. Desses 24 apresentaram alterações compatíveis com dermatite alérgica, sendo 12 machos e 12 fêmeas. A dermatite atópica (DA) foi a mais frequente, afetando 58,33% (14/24) dos cães, seguido por dermatite por hipersensibilidade alimentar (HA) 25% (6/24), dermatite de contato alérgica (DAC) com 8,33% (2/24) dos casos, dermatite alérgica por picada de pulgas (DAPP) com um caso e a hipersensibilidade a medicamento (farmacodermia) também um caso, que representou 4,17% respectivamente. As lesões macroscópicas incluíram hipotricose, hiperpigmentação, comedões, eritema, alopecia, xerose, erosões, úlceras e exsudato, anatomicamente distribuídas na face, cabeça, pescoço, toracolombar, lombossacra, flanco, membros e abdome. As lesões microscópicas mais frequentes foram hiperceratose, acantose, espongiose e exocitose de linfócitos na epiderme. Na derme superficial foi observada perivasculite, perianexite e em alguns casos de incontinência pigmentar, edema, dilatação de vasos sanguíneos, linfáticos e glândulas sudoríparas. O exame histopatológico associado com a história clínica, exame clínico e pele são ferramentas importantes para o diagnóstico de dermatite alérgica em cães, bem como medidas terapêuticas associadas.(AU)

This paper describes the clinical and histopathological features of allergic dermatitis in dogs diagnosed the metropolitan region of João Pessoa, Paraíba. From September 2014 to September 2015 a total of 90 dogs with skin lesions was studied. Twenty-four cases showed changes consistent with allergic dermatitis, in 12 males and 12 females. The age of dogs ranged from 3 months to 15 years. Atopic dermatitis was the most common, affecting 58.33% (14/24) of the dogs, followed by food hypersensitivity dermatitis at 25% (6/24), allergic contact dermatitis at 8.33% (2/24), a case of allergic dermatitis flea and one case of drug hypersensitivity, which represented 4.17% respectively. Gross lesions included hypotrichosis, hyperpigmentation, comedones, erythema, alopecia, xerosis, erosions, ulcers, and exudates. Anatomically distributed was on face, head, neck, thoracolumbar, lumbosacral, flank, limbs and abdomen. The most common microscopic lesions were hyperkeratosis, acanthosis, spongiosis and exocytosis of lymphocytes in the epidermis. In the superficial dermis was observed perivasculitis, perianexite and in some cases pigmentary incontinence, edema, dilated lymphatic vessels and sweat glands. Histopathological examination associated with medical history, clinical examination and skin examen are important tools for the diagnosis of allergic dermatitis in dogs, as well as for associated therapeutic measures.(AU)

Skin-infiltrating T cells and cytokine expression in Icelandic horses affected with insect bite hypersensitivity: a possible role for regulatory T cells.

Equine insect bite hypersensitivity (IBH) is a seasonally recurrent, pruritic skin disorder caused by an IgE-mediated reaction to salivary proteins of biting flies, predominantly of the genus Culicoides. The aim of this study was to define T cell subsets and cytokine profile in the skin of IBH-affected Icelandic horses with particular focus on the balance between T helper (Th) 1, Th2 and T regulatory (Treg) cells. Distribution and number of CD4+, CD8+ and Forkhead box P3 (FoxP3)+ T cells were characterized by immunohistochemical staining in lesional and non-lesional skin of moderately and severely IBH-affected horses (n=14) and in the skin of healthy control horses (n=10). Using real-time quantitative reverse transcription-polymerase chain reaction, mRNA expression levels of Th2 cytokines (Interleukin (IL)-4, IL-5, IL-13), Th1 cytokines (Interferon-γ), regulatory cytokines (Transforming Growth Factor ß1, IL-10) and the Treg transcription factor FoxP3 were measured in skin and blood samples. Furthermore, Culicoides nubeculosus specific serum IgE levels were assessed. Lesions of IBH-affected horses contained significantly higher numbers of CD4+ cells than skin of healthy control horses. Furthermore, the total number of T cells (CD4+ and CD8+) was significantly increased in lesional compared to non-lesional skin and there was a tendency (p=0.07) for higher numbers of CD4+ cells in lesional compared to non-lesional skin. While the number of FoxP3+ T cells did not differ significantly between the groups, the ratio of Foxp3 to CD4+ cells was significantly lower in lesions of severely IBH-affected horses than in moderately affected or control horses. Interestingly, differences in FoxP3 expression were more striking at the mRNA level. FoxP3 mRNA levels were significantly reduced in lesional skin, compared both to non-lesional and to healthy skin and were also significantly lower in non-lesional compared to healthy skin. Expression levels of IL-13, but not IL-4 or IL-5, were significantly elevated in lesional and non-lesional skin of IBH-affected horses. IL-10 levels were lower in lesional compared to non-lesional skin (p=0.06) and also lower (p=0.06) in the blood of IBH-affected than of healthy horses. No significant changes were observed regarding blood expression levels of Th1 and Th2 cytokines or FoxP3. Finally, IBH-affected horses had significantly higher Culicoides nubeculosus specific serum IgE levels than control horses. The presented data suggest that an imbalance between Th2 and Treg cells is a characteristic feature in IBH. Treatment strategies for IBH should thus aim at restoring the balance between Th2 and Treg cells.

Cellular response in the dermis of common wombats (Vombatus ursinus) infected with Sarcoptes scabiei var. wombati.

The cellular response in the dermis of common wombats (Vombatus ursinus) with sarcoptic mange exhibited some typical aspects of an immune response to Sarcoptes scabiei. There was an induction phase for wombats experimentally infected with S. scabiei represented by absence of a dermal inflammatory infiltrate for at least 12 days after infection. T lymphocytes, plasma cells, mast cells, and neutrophils then entered the dermis, consistent with a type IV (delayed) hypersensitivity response. In free-living wombats with severe parakeratotic sarcoptic mange eosinophils were also present in the dermis suggesting that a type I (immediate) hypersensitivity response may develop after a type IV hypersensitivity response. Absence of plasma cells and B lymphocytes in free-living wombats with severe parakeratotic sarcoptic mange compared with their presence in wombats experimentally infected with S. scabiei suggested that some immune tolerance may develop with severe infections. A large proportion of cells in the dermal response were not identified but were possibly cells of connective tissue. The thickness of the epidermis increased within 4 days in response to S. scabiei infection. Some antibodies raised against human leucocyte antigens CD3, CD5, HLA-DP, DQ, DR, and CD79b cross-reacted with leucocyte antigens of common wombats and were used to identify cell types in inflammatory infiltrates using immunohistochemistry.

Inflammatory mediators induce endothelium-dependent adherence of equine eosinophils to cultured endothelial cells.

Accumulation of equine eosinophils at sites of parasite infestation or allergic inflammation depends upon their adherence to vascular endothelial cells and subsequent migration through the endothelium and extracellular matrix. This study has examined whether cytokines, which cause endothelial cell-dependent eosinophil adherence in other species, and histamine and substance P, which increase adherence of equine eosinophils to protein coated plastic, induce equine eosinophil adherence to cultured equine digital vein endothelial cell (EDVEC) monolayers. The EDVEC monolayers were stimulated with recombinant human (rh) interleukin (IL)-1beta, rhTNFalpha, substance P or histamine for different times and with a range of concentrations of mediators and the adherence of blood eosinophils from normal horses examined. All four mediators caused time- and concentration-dependent increases in adherence. However, neither the response to substance P, nor that to histamine, reached a maximum at the highest concentration tested (10-3 M: 10.6 +/- 2.6% and 4.5 +/- 0.6% adherent cells vs. background adherence of 1.9 +/- 0.4% and 1.1 +/- 0.2%; values for substance P and histamine, respectively, expressed as a percentage of total cells added initially; n=4). These data suggest that, as in other species, cytokines induce endothelial cell-dependent eosinophil adherence and mediators released during allergic inflammation may play a role in eosinophil recruitment by this mechanism.

Immunoglobulin-E-bearing cells in skin biopsies of horses with insect bite hypersensitivity.

The aim of the present study was to investigate, with immunohistochemistry and in situ hybridisation, if immunoglobulin-E (IgE) and mast cells are involved in the pathogenesis of insect bite hypersensitivity (IBH), an allergic dermatitis of horses. In tissue sections fixed in paraformaldehyde (PFA) for <24 h, significantly more IgE protein-bearing cells were found in the dermis and epidermis of acute and chronic IBH lesions than in skin biopsies from healthy horses (medians = 466, 236 and 110 cells/mm2, respectively; P < or = 0.01). More IgE-mRNA positive (+) cells were observed in the dermis of acute IBH lesions than in the dermis of healthy skin (median = 2.8 vs. 0.0 cells/mm2; P < or = 0.01). Significantly, more mast cells were detected with metachromatic (median = 160 vs. 62 cells/mm2; P < or = 0.001) and tryptase-specific stainings (median = 120 vs. 69 cells/mm2; P < or = 0.001) in the dermis of acute IBH biopsies compared to healthy skin. No chymase+ mast cells were found in any skin biopsy. IBH lesions fixed in PFA for >24 h were compared to dermatomycosis (DM) lesions; IBH biopsies contained a similar number of IgE-protein+ cells to DM biopsies (median = 249 vs. 192 cells/mm2; P = 0.08) but had significantly more IgE-mRNA+, metachromatic and tryptase+ mast cells than DM biopsies. This study suggests an involvement of IgE-mediated immune reactions in the pathogenesis of IBH as well as, sometimes, in dermatomycosis. Using double labelling, cells which expressed IgE protein and contained mast cell enzymes were detected.

Differential activation of platelets from normal and allergic ponies by PAF and ADP.

OBJECTIVE AND DESIGN: Altered platelet responsiveness has been demonstrated in human atopic dermatitis. This study has compared the in vitro function of platelets from normal ponies and those with the allergic skin disease, sweet itch. SUBJECTS: Ponies with a clinical history of sweet itch and normal ponies were used as blood donors. METHODS: PAF and ADP-induced platelet aggregation was measured and TxB2 production quantitated at the time of maximal aggregation; 12-HETE was additionally measured in some samples. Agonist-induced release of 3[H]5-HT was also studied. RESULTS: Although both PAF and ADP caused equine platelet aggregation, only PAF stimulated eicosanoid and 5-HT release. There were no differences between the responses of platelets from allergic and normal ponies to PAF or ADP (analysis of variance). CONCLUSIONS: There is no evidence of altered platelet responsiveness in ponies with sweet itch. The profile of responses to PAF and ADP suggest differential activation of intracellular signalling pathways in equine platelets.

Immunology of helminth infections, with special reference to immunopathology.

Immune responses resulting in immunity to infection or disease, share the same basic humoral and cellular mechanisms. While immunity to helminth infection has evolved to mediate rapid elimination of the parasite, the strategies evolved by the parasites themselves aim to delay this rejection process and ensure the survival and distribution of their progeny. Ineffective or incomplete immunity results in persistence of parasites or their products within the host tissues, inappropriate or chronic stimulation by parasite antigens, hyper-reactivity and tissue damage or immunopathology. A long standing classification by Gell and Coombs identifies four major types of hypersensitivity responses accounting for most of the immunopathogenesis, three of which are mediated by antibody and one, delayed type hypersensitivity (DTH), by T cells. This paper aims to give a short review of these four classical hypersensitivity reactions with particular reference to infections of large animals with helminth parasites. In addition, in view of the functionally different helper T cell subsets now identified, the existing DTH response is redefined as DTH Type 1 (Th-1 mediated) and two new classes of T cell-dependent DTH responses are proposed; DTH Type II, associated with the Th-2 type cytokines IL-4 and IL-5 and eosinophilic granuloma formation, and DTH Type III, associated with IL-4 and TGF-beta and fibrosis. Finally, some implications of immunopathology on parasite control strategies are discussed.

Responses of red foxes to first and second infection with Sarcoptes scabiei.

The clinical response of red foxes (Vulpes vulpes) to the mange mite, Sarcoptes scabiei, was characterized by infection of five, 4-mo-old red foxes with S. scabiei originally isolated from a wild red fox. The infected foxes and three uninfected control foxes were monitored with weekly complete blood counts and biweekly serum chemistry profiles, hypersensitivity tests, and evaluation of skin biopsies. After 7 wk, the foxes were treated and held free of infection for 2 mo. Six foxes, three previously infected and three with no history of exposure, were then infected with the same isolate of S. scabiei and followed for another 7 wk; two additional previously infected foxes were held as treatment controls, and two foxes with no history of exposure as naive controls. All infected foxes developed significant immediate (Type I) hypersensitivity reactions to a S. scabiei mite extract within 2 wk of exposure and maintained this reaction as long as 4 mo after clearance of mites. Pronounced mast cell hyperplasia and infiltration with eosinophils were the earliest inflammatory cell responses noted in biopsy samples from infected foxes and were maintained throughout infection. Infected foxes also showed significant increases in white blood cell counts, due primarily to increases in numbers of circulating neutrophils and eosinophils. Clinical response, severity of disease, and relative numbers of mites per cm2 of skin of previously infected foxes and foxes undergoing their first infection did not differ. These results show that red foxes develop strong immediate hypersensitivity reactions to S. scabiei but, under our experimental conditions, did not exhibit resistance to reinfection.

Failure of terfenadine as an antipruritic agent in atopic dogs: results of a double-blinded, placebo-controlled study.

Terfenadine (5 mg/kg body weight, q12h) and placebo (0.5 grain/dog q12h) were both administered orally as individual agents to 18 dogs with atopy in a double-blinded study. No dog improved. Hyperactivity, polyphagia, lethargy, anorexia, increased pruritus, or ocular discharge were seen in three dogs treated with terfenadine. Under the conditions of the study, terfenadine was not a useful antipruritic agent for the atopic dog.

Immunopathological study on equine insect hypersensitivity ("kasen") in Japan.

Equine "kasen" is a chronic dermatitis that occurs especially during the summer months. In the present study, skin lesions of kasen that were collected by biopsy from May to October were classified histopathologically into three stages: initial (Group I, 30 cases), developing (Group II, 48 cases) and regressing (Group III, 13 cases). The characteristic lesions were hyperkeratosis, an increase in the number of T-lymphocytes and Langerhans cells (positive for class II MHC) at the epidermo-dermal junction, oedema of the dermis and perivascular infiltration of eosinophils and mast cells. Ultrastructurally, numerous Birbeck granules were observed in the cytoplasm of Langerhans cells. These lesions were striking in Group II and less so in Group III. Kasen is therefore considered to be similar to Queensland itch and sweet itch as described in Australia and Britain, respectively. The histological features were characteristic of a type I and type IV allergic dermatitis.

A double-blind comparison of olive oil and a combination of evening primrose oil and fish oil in the management of canine atopy.

A randomised double-blind parallel study lasting eight weeks was used to assess the effects of olive oil in a group of atopic dogs whose clinical signs were well controlled by dietary supplementation with a combination of evening primrose oil and fish oil. Nine of the 11 dogs which continued to receive this combination were considered unchanged at the conclusion of the study, whereas eight of the 10 dogs switched to olive oil had deteriorated. The mean plasma concentration of dihomogammalinolenic acid, a precursor of potentially antiinflammatory mediators, was significantly reduced (P < 0.05) in the olive oil-treated group at the end of the study. There were no significant differences between the mean plasma linoleic, eicosapentaenoic and arachidonic acid concentrations in the two groups. These findings suggest that olive oil is not an effective therapeutic agent in the control of canine atopy.

Lesions of experimental flea bite hypersensitivity in the dog.

Hypersensitivity to fleas was induced in flea-naive dogs by controlled challenge exposure to virgin fleas. By week 10 of the investigation, immediate (15 minute) and delayed (24-48 hours) responses could be elicited in the skin by flea bites. Histologically, the immediate response consisted of edema and eosinophils which sometimes overlapped with a delayed inflammatory response comprised of perivascular lymphocytes and fewer histiocytes. These inflammatory patterns correlated with type I or immediate, and type IV or cellular, allergic reactions. The combined immediate and delayed responses to fleas in the dog are as observed by other investigators in man and guinea pigs.

Immunoglobulin E antibodies to pollens augmented in dogs by virus vaccines.

An inbred "atopic dog colony" was established to study the effect of viruses on immunoregulation of immunoglobulin (Ig) E antibodies. Dogs were selected for high skin reactivity to grass and weed pollens. Their offspring were inoculated with pollen extracts in alum immediately after routine vaccinations (attenuated live-virus vaccines for canine distemper and infectious canine hepatitis, and a killed bacterin for Leptospira). Heat labile antipollen IgE antibodies were measured by passive cutaneous anaphylaxis. Pups vaccinated for canine distemper before being given pollen extracts had many more IgE antibodies than did their control littermates who were not vaccinated until after the last pollen extract injection. This may be a natural example of the "allergic break-through phenomenon."

Bovine nasal granuloma (atopic rhinitis) in Victoria. Experimental reproduction by the production of immediate type hypersensitivity in the nasal mucosa.

The Australian type of bovine nasal granuloma (bovine atopic rhinitis) was reproduced clinically, grossly and histopathologically in 7 of 9 experimental cattle by subjecting them to repeated acute episodes of immediate-type hypersensitivity on their nasal mucosa over periods of several months.

Bovine nasal granuloma in Victoria -- a search for the causative allergens.

Cows with nasal granuloma showed skin sensitivity to a range of environmental allergens while clinically normal control animals showed little sensitivity. The allergens producing the greatest number of positive reactions included the pollens of dock, capeweed, clover, paspalum, sorrel, rye grass, pepper tree and wattle, the spores of penicillium, cladosporium, botrytis and rye grass rust and extracts of sheep's wool and mite. It is likely that different allergens are important in different animals and in different regions and their importance in the aetiology of nasal granuloma probably depends on their presence in the inhaled air in high concentration for long periods.