ABSTRACT
BACKGROUND: The K5 polysaccharide obtained from Escherichia coli strain 010:K5:H4 is a polymer of the disaccharidic unit formed by D-glucuronic acid and N-acetylglucosamine. This structure is akin to N-acetylheparosan, the precursory polymer of heparin and of heparan sulfate. This structural affinity with N-acetylated heparin and with de-sulfated heparin makes the K5 polysaccharide extremely useful for the preparation of sulfated heparin-like semi-synthetic derivatives. It has been demonstrated that heparins are able to inhibit tissue factor and cytokine production and expression by human monocytes. OBJECTIVE: The aim of this study was to evaluate the effects of four different heparin-like semi-synthetic derivatives on inflammatory cytokine production and expression by human mononuclear cells. RESULTS: The simultaneous addition of lipopolysaccharide (LPS; 0.2 and 10 micro g mL(-1)) and the K5 polysaccharide did not inhibit interleukin (IL)-1beta, IL-6 or tumor necrosis factor (TNF)-alpha production by stimulated mononuclear cells. IL-1beta, IL-6 and TNF-alpha concentrations in supernatants of LPS-stimulated mononuclear cells were not influenced by the addition of N,O-sulfated K5 polysaccharide (K5-N, OS) and epimerized N-sulfated K5 polysaccharide (K5 NS epi) at 5 and 10 microg mL(-1), whereas the addition of epimerized N,O-sulfated K5 polysaccharide (K5-N, OS epi) (5 and 10 microg mL(-1)) and O-sulfated K5 polysaccharide (K5-OS) (5 and 10 microg mL(-1)) to LPS-stimulated cells caused a significant dose-dependent inhibition of IL-1beta, IL-6 and TNF-alpha. All sulfated heparin-like semi-synthetic derivatives did not influence the IL-10 production by LPS-stimulated mononuclear cells. In LPS-stimulated cells (0.2 and 10 microg mL(-1)), K5-OS or K5-N, OS epi at 5 and 10 microg mL(-1) markedly decreased TNF-alpha mRNA expression. CONCLUSIONS: These results indicate that the sulfated heparin-like semi-synthetic derivatives K5-OS and K5-N, OS epi are able to inhibit both expression and production of inflammatory cytokines, whereas they do not influence the anti-inflammatory cytokine IL-10, suggesting a potential role for these products as modulators of inflammatory reactions.
