Staphylococcus epidermidis biofilm modulates cytokine production
Abstract number: P696
Spiliopoulou A., Kolonitsiou F., Spiliopoulou I., Krevata M., Dimitracopoulos G., Anastassiou E.
Objectives: To compare the immune response of Staphylococcus epidermidis bacterial cells existing either in planctonic or in biofilm phase.
Methods: A reference slime producing S. epidermidis strain (ATCC35983) was used in the present study. Slime production was confirmed by Christensen's method. Planctonic phase bacteria were obtained after a 6h incubation in proper medium. Biofilm phase bacteria were obtained by incubation in 24-well tissue culture plates for 48h and subsequent rinse; biofilm phase cells remained attached to the bottom of the wells. Peripheral blood mononuclear cells from multiple healthy donors were isolated and co-cultured in 24-well flat bottom tissue culture plates either with live S. epidermidis planctonic cells at a ratio of 25:1 or with biofilm phase cells. Cytokines were measured in triplicate, using the Luminex® xMAPTM technology, in cell-free supernatants collected at 2, 4, 6, 12, 24 and 48 hours. The 8-plex assay kit was used for the simultaneous quantitative determination of the following cytokines: TNFa, IL-1b, IL-6, IL-8, IL-10, IL-12p40, IL-13 and GM-CSF, whereas, the 3-plex high-sensitivity assay kit was used for IL-12p70, IL-2, and INF-g.
Results: Kinetics of cytokine production revealed that TNFa and IL-10 accumulation was higher at 12h, whereas IL-12, IL-2, INF-g, and GM-CSF peaked at 48h. IL-1b, IL-6 and IL-8 levels exhibited a plateau pattern between 6 and 48h. IL-13 was not detectable in most experiments. Biofilm phase bacteria elicited production of lower levels of all cytokines tested as compared to planctonic phase bacteria. This phenomenon was more prominent for IL-12p40, as biofilm phase bacteria led to 35-fold lower IL-12p40 production. Although cytokines' levels showed interdonor variability, the overall pattern was reproducible in all experiments. Differences were statistically significant (p < 0.05). Mean peak value±standard deviation of each cytokine in pg/mL from a typical representative experiment is shown in Table 1.
Conclusion:S. epidermidis cells embedded in biofilm induce low-level production of proinflammatory and adaptive immunity cytokines, especially IL-12p40, which is a key cytokine in development of TH1 responses leading to suppression of immune system, and may explain observed silent, persistent, infections.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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