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The effect of Psoroptes ovis infestation on ovine epidermal barrier function

Miriam R Stoeckli2, Tom N McNeilly1, David Frew1, Edward J Marr1, Alasdair J Nisbet1, Adri HM van den Broek23 and Stewart TG Burgess1*

Author Affiliations

1 Moredun Research Institute, Pentlands Science Park, Bush Loan, Edinburgh, Midlothian, Scotland, EH26 0PZ, United Kingdom

2 The Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Midlothian, Scotland, EH25 9RG, United Kingdom

3 The Roslin Institute, The University of Edinburgh, Division of Veterinary Clinical Sciences, Hospital for Small Animals, Easter Bush Veterinary Centre, Roslin, Midlothian, Scotland, EH25 9RG, United Kingdom

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Veterinary Research 2013, 44:11  doi:10.1186/1297-9716-44-11

Published: 11 February 2013


Sheep scab is an intensively pruritic, exudative and allergic dermatitis of sheep caused by the ectoparasitic mite Psoroptes ovis. The purpose of the present study was to investigate the effect of P. ovis infestation on different components of the ovine epidermal barrier within the first 24 hours post-infestation (hpi). To achieve this, the expression of epidermal differentiation complex (EDC) genes and epidermal barrier proteins, the nature and severity of epidermal pathology and transepidermal water loss (TEWL) were evaluated.

By 1 hpi a significant dermal polymorphonuclear infiltrate and a significant increase in TEWL with maximal mean TEWL (598.67 g/m2h) were observed. Epidermal pathology involving intra-epidermal pustulation, loss of epidermal architecture and damage to the basement membrane was seen by 3 hpi. Filaggrin and loricrin protein levels in the stratum corneum declined significantly in the first 24 hpi and qPCR validation confirmed the decrease in expression of the key EDC genes involucrin, filaggrin and loricrin observed by microarray analysis, with 5.8-fold, 4.5-fold and 80-fold decreases, respectively by 24 hpi.

The present study has demonstrated that early P. ovis infestation disrupts the ovine epidermal barrier causing significant alterations in the expression of critical barrier components, epidermal pathology, and TEWL. Many of these features have also been documented in human and canine atopic dermatitis suggesting that sheep scab may provide a model for the elucidation of events occurring in the early phases of atopic sensitisation.