ABSTRACT
BACKGROUND: Staphylococcus aureus (S. aureus) is frequently detected in the skin of patients with atopic dermatitis (AD), and involved in the flare of AD. There are some evidence-specific strains of S. aureus affect the severity of AD. However, the mechanism of predominant colonization and the aggravation of dermatitis by certain strains of S. aureus in the patients with AD are still unknown. OBJECTIVE: To reveal the characteristics of S. aureus from patients with AD (S. aureus-AD), we analyzed the interaction of S. aureus-AD and keratinocytes in comparison with those of S. aureus laboratory strains (S. aureus-stand.). METHODS: We stimulated HaCaT cells, keratinocyte cell line, and human epidermal keratinocytes by heat-killed S. aureus strains, then evaluated immune response of keratinocytes by ELISA, immunofluorescence staining, and flow cytometry. RESULTS: Upon incubation with keratinocytes, three out of four strains of heat-killed S. aureus-AD were strongly agglutinated inside the cytoplasm. In the cells, they are located in lysosomes and promoted the secretion of interleukin-1α (IL-1α). These reactions were not observed by any of four strains of S. aureus-stand. and S. epidermidis and were abolished by the treatment of S. aureus with proteinase K. Moreover, the IL-1α secretion was diminished by the inhibition of Toll-like receptor 9 (TLR9). CONCLUSION: S. aureus-AD accumulates in lysosome of keratinocytes by means of bacterial cell wall proteins and induces IL-1α via TLR9.
Subject(s)
Dermatitis, Atopic/etiology , Dermatitis, Atopic/metabolism , Interleukin-1alpha/metabolism , Keratinocytes/metabolism , Lysosomes/metabolism , Staphylococcal Infections/microbiology , Staphylococcus aureus , Toll-Like Receptor 9/metabolism , Biomarkers , Cell Line , Cytokines/metabolism , Dermatitis, Atopic/diagnosis , Humans , Keratinocytes/immunology , Phagocytosis/immunology , Signal Transduction , Staphylococcal Infections/complications , Staphylococcus aureus/immunology , Staphylococcus aureus/isolation & purification , Toll-Like Receptor 9/geneticsABSTRACT
BACKGROUND: Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases. The skin of patients with AD presents as a disbalance of the microbiome with a strong colonization by Staphylococcus aureus, which positively correlates with the severity of the disease. However, the effect of colonized S. aureus on the skin immune system has not been fully elucidated. OBJECTIVE: The aim of this study is to explore whether S. aureus isolated from AD skin is able to skew T cell responses via Langerhans cells (LC) as compared to a standard strain of S. aureus and S. epidermidis. METHODS: We prepared monocyte-derived LC (MoLC) from healthy controls and patients with AD, and stimulated MoLC with a standard strain of S. aureus NCTC8325, S. aureus TF3378 isolated from AD skin, or S. epidermidis. Stimulated MoLC were co-cultured with autologous CD4pos T cells and then T cell responses were analyzed by T cell polarization assays, cytokine analysis and real-time PCR. RESULTS: MoLC stimulated by S. aureus TF3378 induced significantly high and rapid proliferation of T cells as compared to those by S. aureus NCTC8325 and S. epidermidis. Cytokine productions from T cells cultured with S. aureus TF3378-stimulated MoLC showed significantly high amounts of IL-2 and less IFN-γ production with imbalanced Th1/Th2 (decreased TBX21/GATA3 ratio) mRNA expression. The T cell proliferation with increased IL-2 production via S. aureus TF3378-stimulated MoLC was diminished by treatment of proteinase K. CONCLUSION: S. aureus TF3378 on AD skin can skew T cell responses via LC toward imbalanced Th1/Th2 skin immunity.
