Human umbilical vein endothelial cells (HUVEC) were infected for 24 h with 18 well-characterized, noninvasive Staphylococcus aureus isolates and the supernatants were analyzed for IL-1ß, TNF-α, IL-6, IL-8, IL-10, IL-12p70, GRO-α, GM-CSF and RANTES by immuno assay. All isolates induced expression of IL-6, IL-8, GRO-α, GM-CSF, and RANTES. The highest concentrations were observed for IL-6, IL-8 and GRO-α, which reached levels close to that of HUVEC stimulated with LPS (0.1µg ml-1). The magnitude of cytokine expression varied between isolates. S. aureus inducing high expression of one of these cytokines also showed simultaneous high expression of the other four, indicating a common ability of individual S. aureus to induce high or low expression of these cytokines. IL-1ß, TNF-α, IL-10 and IL-12p70 were not upregulated by any of the S. aureus isolates. No correlation between cytokine profile and S. aureus production of enterotoxin A-D, TSST-1, cytotoxicity, PFGE and phage pattem or susceptibility to methicillin was observed. The ability of individual S. aureus to induce expression of cytokines correlated with their ability to upregulate ICAM-1, but not E-selectin, in HUVEC. Similarly, a heat-stable, high molecular weight component(s) from sterile culture filtrate of S. aureus upregulated expression of IL-8 and ICAM-1 in HUVEC.
Our results show that individual clinical isolates of S. aureus vary in ability to directly stimulate human endothelial cells to upregulate cytoldnes that promote leukocyte recruitment and inflammation.