Does a condition like human pityriasis rosea occur in pigs?

Animal models of psoriasis

Research into the pathogenesis of psoriasis has been severely hampered by the lack of a naturally occurring disorder in laboratory animals that mimics the complex phenotype and pathogenesis of the human disease. A large variety of spontaneous mutations, genetically engineered rodents, immunological reconstitution approaches, and xenotransplantation models have been used to study specific aspects of the pathophysiology of psoriasis, however. Several manipulations of resident cutaneous cell types or immigrating immunocytes appear to result in remarkably similar hyperproliferative inflammatory phenotypes in mice, thus suggesting that interfering with cutaneous homeostasis in general may ultimately result in a rather uniform reaction pattern that mirrors some features of psoriasis. Fully animal models of psoriasis have nonetheless not only shed light on the biological functions of given inflammatory mediators or other molecules but also tremendously contributed to the discussion on central pathogenic questions, such as the roles of innate and adaptive immune mechanisms, keratinocytes, and endothelial cells in psoriasis. Psoriasis research has also been greatly nourished by xenotransplantation of diseased or unaffected human skin onto immunocompromised recipients, an approach that has in many variations been used to study the role of T lymphocytes and other cells and that has been used for preclinical therapeutic studies. General approaches to generate animal models of psoriasis, features of some specific models, their value for psoriasis research, and their use for drug development are discussed in this article.

Therapeutic potential of selectin antagonists in psoriasis

Psoriasis is a systemic chronic inflammatory disorder. One of the major characteristics is an excess of infiltration of inflammatory cells, mainly lymphocytes, into the skin. Because the adhesion family of selectins is suggested to play a relevant role in this process, selectins have emerged as an interesting target for drug discovery and development in psoriasis. Different strategies targeting selectins have been described. This review discusses these approaches and summarises the current development of selectin antagonists for the treatment of psoriasis. An expert opinion will give the authors' personal opinion about selectin antagonism in psoriasis and which approach might be preferable.

Clinical and Histopathological Findings in Pustular Psoriaform Dermatitis (Pityriasis Rosea) in Pigs

Three cases of pustular psoriaform dermatitis (pityriasis rosea) in pigs were clinically and histopathologically examined. Grossly, the affected skin was characterized by multiple, circumscribed lesions. Three pigs were the descendants derived from the same Landrace boar. Skin lesions expanded centrifugally to became ring-shaped plaques. There were no abnormal values in hematological and serum biochemical profiles. Histopathologically, the epidermis showed remarkable thickening. The dermal lesions were characterized by a prominent component of superficial and deep perivascular infiltration of eosinophils. Dilatation of microvasculature was accompanied with congested vessels. These results revealed that the etiology of pustular psoriaform dermatitis in pigs was associated with a hereditary predisposition derived from the specific boars. This dermatosis is histopathologically characterized by microcirculatory disturbances with infiltration of abundant eosinophils.

Cutaneous ultrastructural features of the flaky skin (fsn) mouse mutation

An autosomal recessive genetic disease with clinical and histopathological skin features resembling human psoriasis vulgaris occurs naturally in flaky skin mice (fsn/fsn). Affected mice are normal at birth, except for a hypochromic anemia. Subsequently, they develop hyperkeratotic plaques and acanthosis with elongation of rete ridges. Scanning electron microscopic examination revealed a greatly thickened epidermis, a sparsity of hairs and scale accumulations on the epidermal surface. Hair shafts had conspicuous pits, striations, and exophytic protrusions. Nails were bent at a 90 degrees angle with surface irregularities and accumulations of scale at the nail base. Transmission electron microscopic examination showed increased epidermal thickness, mitochondrial aberrations, and intraepidermal invasion by neutrophils. Keratohyalin abnormalities were detected using immunocytochemical staining for profilaggrin. At the dermal-epidermal junction, numerous macrophages and mast cells were seen in close proximity to focal dissolutions of the basement membrane. A high density of collagen fibers and cellular infiltrates were evident in the papillary dermis. This constellation of ultrastructural aberrations is typically found in psoriasis vulgaris and supports the theory that the flaky skin mouse mutation is a naturally occurring analog to one variety of human psoriasis vulgaris.

Full-thickness skin grafts from flaky skin mice to nude mice: maintenance of the psoriasiform phenotype

Flaky skin (fsn) is an autosomal recessive mouse mutation with papulosquamous disease features similar to human psoriasis. In fsn/fsn skin, one sees marked acanthosis and hyperkeratosis with focal parakeratosis, subcorneal pustules, dermal capillary dilation, and a marked diffuse dermal infiltration of mixed inflammatory cells, predominantly lymphocytes. To determine if these pathologic features are a characteristic of the skin or a chronic autoimmune attack, we placed full-thickness skin grafts from affected homozygous (fsn/fsn) and normal littermate control (+/?) mice on the dorsal skin of genetically athymic nude (nu/nu) mice. After 10 weeks of observation, the grafts maintained the histologic phenotype of the donor animal. In the fsn/fsn grafts, there was persistence of both epidermal proliferation and dermal inflammation, characteristics of the mutation. The fsn/fsn phenotype was also confirmed by immunohistochemical evaluation for specific mouse keratinocyte marker expression. Based on tritiated thymidine uptake, we found DNA synthesis rates elevated threefold or more in fsn/fsn epidermis compared to littermate control mouse skin. Elevated rates of DNA synthesis remained a feature of the fsn/fsn grafts but not that of littermate control skin grafts. This study demonstrates that the psoriasiform phenotype of this mouse mutation can persist independent of the host thymic-derived immune system.

Inherited Mouse Mutations as Models of Human Adnexal, Cornification, and Papulosquamous Dermatoses

Nearly 100 mouse mutations have been described as causing some type of abnormality of the skin or hair. As only a few of these mutations have been studied in detail, they remain an untapped resource for furthering knowledge of basic cutaneous physiology and understanding the pathophysiology of analogous diseases in humans. Several diverse murine mutations are discussed. These include "asebia," a mildly hyperkeratotic disorder with sebaceous gland hypoplasia; "ichthyosis," an example of abnormal hair growth associated with hyperkeratosis; "rhino" and "hairless," two related examples of congenital follicular malformations; and "flaky skin", a potential animal model of eruptive psoriasis.