Fig 1. Interleukin (IL)-10 is upregulated in the nasal cavity during S. aureus colonisation.
Wild-type mice were colonised with S. aureus Newman SmR (2 × 108 colony-forming units/nose) or administered with PBS only. At 3h, 6h, 12h, 24h, and 72h mice were culled, tissue was homogenized and RNA extracted from nasopharyngeal tissue (NT) and nose homogenates. IL-10 gene expression in the NT (A) and nose (B) were established using qRT-PCR. The messenger RNA values were expressed as mean relative expression ± s.e.m. and was compared with baseline IL-10 expression from PBS-treated mice after normalizing to 18S RNA expression (Experimental unit = 1 mouse, n = 5 for each time-point, total # of animals used; 50, data generated from 2 independent experiments). At 6h, 12h, 24h, 72h and 168h noses and NT were homogenized in PBS and protein levels of IL-10 (C & D) were determined by ELISA. Values are expressed as mean protein concentration ± s.e.m. (Experimental unit = 1 mouse, n = 5–10 per group, total # animals used 80, data generated from 2 independent experiments). At 6h post-colonisation noses and NT were excised, tissue digested and CD45+ and CD45- cells isolated by MACs sorting prior to assessment of IL-10 mRNA expression (E) (Experimental unit = Tissue was pooled from n = 10 mice and the experiment was repeated twice, total # animals used 20). The CD45+ fraction was also sorted into CD3+ T cells, CD19+B cells, CD11b+ F480+Ly6G- macrophages and CD11b+ Ly6G+ F480- neutrophils/MDSCs using flow cytometry cell sorting (F). IL-10 mRNA expression was determined by RT-PCR for each fraction (Experimental unit = Tissue was pooled from n = 15 mice and the experiment was repeated twice, total # animals used 30). Statistical analysis was performed using two-way analysis of variance or student t test. *P≤0.05; **P≤0.01; ***P≤0.001.