title: Crusted scabies is associated with increased IL-17 secretion by skin T cells.
abstract: Scabies is an ectoparasitic infestation by the mite Sarcoptes scabiei. Although commonly self-limiting, a fraction of patients develop severely debilitating crusted scabies. The immune mechanisms underlying the development of crusted scabies are unclear, and undertaking longitudinal infection studies in humans is difficult. We utilized a porcine model to compare cellular immune responses in peripheral blood and skin of pigs with different clinical manifestations of scabies (n = 12), and in uninfected controls (n = 6). Although clinical symptoms were not evident until at least 4 weeks post-infestation, the numbers of peripheral IFNγ-secreting CD4(+) T cells and γδ T cells increased in infected pigs from week 1 post-infestation. γδ T cells remained increased in the blood at week 15 post-infestation. At week 15, skin cell infiltrates from pigs with crusted scabies had significantly higher CD8(+) T cell, γδ T cell and IL-17(+) cell numbers than those with ordinary scabies. Peripheral IL-17 levels were not increased, suggesting that localized skin IL-17-secreting T cells may play a critical role in the pathogenesis of crusted scabies development. Given the potential of anti-IL-17 immunotherapy demonstrated for other inflammatory skin diseases, this study may provide a novel therapeutic avenue for patients with recurrent crusted scabies.
authors.affiliation: Inflammation & Healing Research Cluster, School of Health & Sport Sciences, University of the Sunshine Coast, Maroochydore, Qld, Australia.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: S F
authors.initials: SF
authors.lastname: Walton
authors.forename: H C
authors.initials: HC
authors.lastname: Murray
authors.forename: M
authors.initials: M
authors.lastname: King
authors.forename: A
authors.initials: A
authors.lastname: Kelly
authors.forename: D C
authors.initials: DC
authors.lastname: Holt
authors.forename: B J
authors.initials: BJ
authors.lastname: Currie
authors.forename: J S
authors.initials: JS
authors.lastname: McCarthy
authors.forename: K E
authors.initials: KE
authors.lastname: Mounsey
mesh_terms: D000818:Animals; D007111:Immunity, Cellular; D020381:Interleukin-17 / Q000097:blood / Q000276:immunology*; D011897:Random Allocation; D012520:Sarcoptes scabiei / Q000502:physiology*; D012532:Scabies / Q000097:blood / Q000276:immunology* / Q000469:parasitology / Q000473:pathology*; D012867:Skin / Q000276:immunology / Q000473:pathology; D034421:Sus scrofa; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D020381:Interleukin-17
keywords: IL-17; crusted scabies; scabies; γδ T cells