Immune responses in scabies: insights from a porcine model

Mounsey K

School of Health & Sport Sciences, University of the Sunshine Coast, Maroochydore QLD.

Scabies is a skin disease caused by the parasitic mite Sarcoptes scabiei. Critical biological questions surrounding scabies remained unanswered due to the inability to undertake longitudinal study of infestation in humans. The recent development of a porcine model has facilitated in vivo studies on scabies immunopathology. Our research aims to identify factors leading to a dysregulated immune response in crusted scabies, a poorly understood clinical manifestation characterised by an extreme proliferation of mites. We have undertaken several experimental trials, focusing on defining cellular infiltrates and transcription of key cytokines in the skin over the course of infestation. Recent gene expression studies show that scabies is characterised by early immune suppression, followed by dramatic upregulation of pro-inflammatory genes in later weeks of infestation, consistent with the delayed appearance of clinical manifestations. Crusted scabies was associated with a higher number of down regulated genes at all time points, and differential expression of Th17 associated pathways. Transcriptional profiles cluster strongly according to clinical phenotype even prior to the introduction of infection, providing insights into markers of individual susceptibility and resistance to scabies. Outcomes from this research may lead to strategies to protect vulnerable subjects from contracting recurrent crusted scabies, and result in improved skin health for disadvantaged communities where this parasite is endemic.