Staphylococcal glycocalyx activates macrophage prostaglandin E2 and interleukin 1 production and modulates tumor necrosis factor alpha and nitric oxide production

Abstract

We have examined the effect of staphylococcal glycocalyces on the ability of murine peritoneal macrophages to produce prostaglandin E2 (PGE2) and the inflammatory cytokines interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) and to generate nitric oxide. Glycocalyx partially purified under endotoxin-free conditions from defined liquid medium cultures of Staphylococcus lugdunensis or Staphylococcus epidermidis was a strong stimulator of PGE2 and IL-1 production. The addition of 10 to 100 micrograms of glycocalyx per ml induced levels of IL-1 and PGE2 production similar to that induced by 0.1 to 1 micrograms of Escherichia coli lipopolysaccharide (LPS) per ml. In contrast, glycocalyx induced ninefold less TNF-alpha and three- to fourfold less nitrite than LPS. A modulatory effect was suggested by the observation that the amount of TNF-alpha and nitrite generated remained constant whether the macrophages were stimulated with 10 or 100 micrograms of glycocalyx per ml. A selective modulation of macrophage activation was confirmed by the demonstration that costimulation of macrophages with both glycocalyx and LPS resulted in a reduction in TNF-alpha and nitrite generation relative to stimulation with LPS alone even though costimulation had no effect on PGE2 production and increased IL-1 production. Involvement of PGE2 in this modulatory effect was suggested by the ability of indomethacin to augment glycocalyx-stimulated TNF-alpha production and to reverse the inhibitory effect of glycocalyx on LPS induction of TNF-alpha production. However, the inability of indomethacin to reverse the inhibitory effect of glycocalyx on LPS-induced nitric oxide generation suggests that the selective modulation of macrophage function by glycocalyx may be more complex than increased sensitivity to PGE2 feedback inhibition.