An alopecic phenotype of canine pemphigus vulgaris?

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.

Suspected polymyxin B-induced pemphigus vulgaris in a dog

A case of pemphigus vulgaris (PV), putatively induced by topical application of polymyxin B ear drops, is described. A 3-year-old, female Tosa Inu, presented with acute onset swelling, blistering and ulceration of the pinnae, nostrils, lips and oral mucous membranes. The dog was depressed, febrile and anorexic. For 7 days prior to the onset of the acute ulcerative disease, polymyxin B ear drops had been applied to both ears to treat an ear infection. Skin and mucosal biopsies showed suprabasilar cleft formation and acantholysis, indicative of PV. The polymyxin B ear drops were discontinued and the dog was treated with intravenous fluids, systemic and topical antibacterial therapy, and immunosuppressive therapy comprising prednisone and azathioprine. Complete remission was noted after 2 weeks, and the immunosuppressive therapy was discontinued one month later. No clinical signs of PV recurred over a 1 year follow-up period. As PV does not usually resolve spontaneously, or enter long-term remission, it was considered that the condition was most likely drug induced due to the aural application of polymyxin B.

Atypical pemphigus: discordance between clinicopathological findings and the antigenic profile in four cases

BACKGROUND

The diagnosis of pemphigus vulgaris and pemphigus foliaceus is usually based on clinical, histological, and immunofluorescence (IF) findings. In recent years, the antigenic profile of both diseases has been further defined by immunobiochemical techniques (ELISA, immunoblot, and immunoprecipitation).

METHODS

A retrospective study of 40 pemphigus patients was performed to determine the clinical, histological, and antigenic profile in patients with pemphigus followed at our Department. Charts review, clinical data, histological and IF findings, and antigenic analysis by ELISA were performed in all patients.

RESULTS

In most patients, there was a perfect correlation between the clinical and histological findings and their antigenic profile. In four patients (10%), clinicopathological features and antigenic findings were discordant.

CONCLUSIONS

The antigenic profiles in pemphigus do not always correlate with the clinical diagnosis. Therefore, clinical and histological features should be considered as the mainstay for the diagnosis of pemphigus.

Detection of circulating autoantibodies using living keratinocyte staining on MCA-B1 method in dogs with pemphigus foliaceus

In this study, we compared the sensitivity and specificity of three immunofluorescence techniques used to detect circulating autoantibodies in dogs with pemphigus foliaceus (PF); living keratinocyte staining on a canine keratinocyte cell line, MCA-B1, indirect immunofluorescence (IIF) on canine lip and IIF on bovine esophagus. Sera from canine PF cases were positive in four out of 27 dogs (14.8%) using living keratinocyte staining on MCA-B1 cells method, and five (18.5%) and eight sera (29.6%) using IIF on canine lip and bovine esophagus methods, respectively. By contrast, none of the 31 sera from dogs with non-pemphigus dermatoses reacted with MCA-B1 cells, whereas two (6.5%) as well as five sera (16.1%) obtained from those dogs showed positive reactivity with IIF on canine lip and bovine esophagus, respectively. Our results suggest that, although it exhibits the least sensitivity, the positive reactivity obtained by living keratinocyte staining on MCA-B1 cells can support the diagnosis of canine PF.

Desmoglein-3 is a target autoantigen in spontaneous canine pemphigus vulgaris

Pemphigus vulgaris (PV) is an autoimmune blistering skin disease of humans and companion animals. In human patients, PV is associated with the production of IgG autoantibodies specific for keratinocyte desmosomal glycoproteins of the cadherin family. The purpose of this study was to determine whether antikeratinocyte IgG autoantibodies were present in the skin and serum of dogs with PV, and also to identify the canine PV autoantigen(s) targeted by circulating autoantibodies. Eleven dogs were selected because of the microscopic demonstration of suprabasal epithelial acantholysis. Direct immunofluorescence revealed the presence of IgG autoantibodies bound to the membrane of keratinocytes in skin biopsy specimens of 8/9 dogs (89%). Using indirect immunofluorescence, serum-circulating IgG autoantibodies were found in 10/11 (91%) and 5/11 (45%) dogs, using normal canine gingiva and cultured canine oral keratinocytes, respectively. By immunoblotting using cultured canine oral keratinocyte protein lysates, IgG autoantibodies from 7/9 (78%) tested dogs recognized a 130-kDa antigen that comigrated with that identified by rabbit polyclonal antibodies raised against desmoglein-3. This 130 kDa antigen was confirmed to represent the canine equivalent of human desmoglein-3 by immunoprecipitation-immunoblotting. The results of these studies provide evidence that the canine desmoglein-3 homologue is a major autoantigen in dogs with PV. These observations further establish spontaneous canine PV as a natural model for research on pathogenesis, etiology and novel therapeutic approaches for this disease of humans.