Quantitative analysis of infiltrating immune cells and bovine papillomavirus type 1 E2-positive cells in equine sarcoids.
Sarcoids are the most frequently observed skin tumours in equids and consist of cutaneous accumulations of transformed fibroblasts. Their aetiopathogenesis is closely linked to a presumably abortive infection by bovine papillomavirus (BPV) types 1 and 2. In cattle, dermal fibropapillomas induced by BPV1/2 usually regress spontaneously due to a local, cell-mediated, immune response; however, equids appear to lack an effective immune response to BPV1/2 and mechanisms of immune evasion have been postulated. As a consequence, equine sarcoids tend to persist and are prone to recur. In this study, cryosections were analysed by immunofluorescent staining and a high content analysis system to determine the presence and distribution of CD4(+), CD8(+), FoxP3(+), RORγt(-), CD206(+) and CD14(+) cells, along with expression of the BPV1 early regulatory protein E2. A higher density of cells was positive for BPV1 E2(+) within the transformed tissue than in perilesional tissue or normal skin of horses with sarcoids and control horses. The proportion of CD8(+) cytotoxic T cells was significantly increased in perilesional and lesional tissues, whereas CD4(+) T helper cells were present in higher density only in lesional tissue compared to normal skin from horses with and without sarcoids. The proportion of pro-inflammatory CD4(+)FoxP3(+)RORγt(+) regulatory T cells was decreased in sarcoid tissue compared to perilesional, distant and control tissue. There were no significant differences in densities of CD4(+)FoxP3(+) RORγt(-) regulatory T cells between sarcoids and control tissues. Equine sarcoids are characterised by infiltrations of CD8(+) and CD4(+) T cells, with decreased representation by pro-inflammatory CD4(+)FoxP3(+)RORγt(+) regulatory T cells.
Swiss Institute of Equine Medicine, ALP-Haras, Länggassstrasse 124, Postfach 8466, Berne CH-3001, Switzerland. Electronic address: helena.geisshuesler@vetsuisse.unibe.ch.
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Geisshüsler
Division of Experimental Clinical Research, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, Berne CH-3012, Switzerland.
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Marti
Division of Veterinary Anatomy, Vetsuisse Faculty, University of Berne, Postfach 8466, Länggassstrasse 120, Berne CH-3001, Switzerland.
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Stoffel
Division of Veterinary Anatomy, Vetsuisse Faculty, University of Berne, Postfach 8466, Länggassstrasse 120, Berne CH-3001, Switzerland.
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Kühni
Division of Veterinary Anatomy, Vetsuisse Faculty, University of Berne, Postfach 8466, Länggassstrasse 120, Berne CH-3001, Switzerland.
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Stojiljkovic
Institute of Animal Pathology, Vetsuisse Faculty, University of Berne, Länggassstrasse 122, Postfach 8466, Berne CH-3001, Switzerland.
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von Tscharner
Veterinary Public Health Institute, Vetsuisse Faculty, University of Berne, Schwarzenburgenstrasse 155, Berne CH-3097, Switzerland.
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Vidondo
Swiss Institute of Equine Medicine, ALP-Haras, Länggassstrasse 124, Postfach 8466, Berne CH-3001, Switzerland.
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Gerber
Swiss Institute of Equine Medicine, ALP-Haras, Länggassstrasse 124, Postfach 8466, Berne CH-3001, Switzerland.
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Koch
D000818:Animals; D052688:Bovine papillomavirus 1 / Q000502:physiology*; D016616:Cryoultramicrotomy / Q000662:veterinary; D005455:Fluorescent Antibody Technique / Q000662:veterinary; D006734:Horse Diseases / Q000473:pathology* / Q000821:virology; D006736:Horses; D018655:Lymphocyte Count / Q000662:veterinary; D030361:Papillomavirus Infections / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D012507:Sarcoidosis; D012878:Skin Neoplasms / Q000473:pathology / Q000662:veterinary* / Q000821:virology
Equine sarcoid; FoxP3; Immune response; Immunofluorescence; Regulatory T cell