Abstract
BackgroundUnderstanding of scabies immunopathology has been hampered by the inability to undertake longitudinal studies in humans. Pigs are a useful animal model for scabies, and show clinical and immunologic changes similar to those in humans. Crusted scabies can be readily established in pigs by treatment with the glucocorticoid dexamethasone (Dex).Methodology/ Principal FindingsProspective study of 24 pigs in four groups: a) Scabies+/Dex+, b) Scabies+/Dex-, c) Scabies-/Dex+ and d) Scabies-/Dex-. Clinical symptoms were monitored. Histological profiling and transcriptional analysis of skin biopsies was undertaken to compare changes in cell infiltrates and representative cytokines. A range of clinical responses to Sarcoptes scabiei were observed in Dex treated and non-immunosuppressed pigs. An association was confirmed between disease severity and transcription of the Th2 cytokines IL-4 and IL-13, and up-regulation of the Th17 cytokines IL-17 and IL-23 in pigs with crusted scabies. Immunohistochemistry revealed marked infiltration of lymphocytes and mast cells, and strong staining for IL-17.Conclusions/ SignificanceWhile an allergic Th2 type response to scabies has been previously described, these results suggest that IL-17 related pathways may also contribute to immunopathology of crusted scabies. This may lead to new strategies to protect vulnerable subjects from contracting recurrent crusted scabies.
Highlights
Sarcoptes scabiei infestation is associated with considerable global morbidity [1]
While an allergic Th2 type response to scabies has been previously described, these results suggest that IL-17 related pathways may contribute to immunopathology of crusted
Crusted scabies is a an extremely severe and debilitating clinical form of the disease, but host immune responses leading to the development of crusted or ordinary scabies are poorly understood
Summary
Sarcoptes scabiei infestation is associated with considerable global morbidity [1]. The disease is prevalent in overcrowded living conditions, with the highest disease burdens seen in young children [2]. The link between scabies, secondary bacterial infection and sequleae such as poststreptococcal glomerulonephritis [3] has resulted in efforts to reduce the prevalence of scabies in endemic communities. Ordinary scabies manifests as a localised or general rash with low mite burden (
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