Production of IL-1 alpha and IL-1 beta by human skin equivalents parasitized by Sarcoptes scabiei

Human skin equivalents (HSEs) were used as a model to investigate interleukin (IL)-1α and IL-1β secretions by keratinocytes stimulated by Sarcoptes scabiei (SS). SS mites burrowed into the stratum corneum when placed on the surface of cultured HSEs. Mites lived for 14 days. Mites and mite products induced cells in the HSEs to secrete IL-1α and IL-1β within 16 hr. Scabies mites induced production of greater amounts of IL-1α than IL-1β. Hepatocyte growth factor in the culture medium at 3 and 30 ng/ml upregulated the secretions of both IL-1α and IL-1β by mite-infested skin equivalents, whereas 10 ng/ml of IL-6 upregulated production of only IL-1β Therefore, these cytokines were important immunomodulating factors influencing keratinocyte secretion of IL-1α and IL-1β in vitro. The results of this study provide the first evidence that keratinocytes (possibly fibroblasts) in the skin produce these cytokines in response to scabies mites or other ectoparasitic arthropods. Because IL-1α and IL-1β are potent inducers of inflammation and keratinocytes are among the first effector cells to encounter scabies mites and their products, these cells may be key initiators of the inflammatory/immune reaction to scabies.