Unfractionated Heparin Modulates Lipopolysaccharide-Induced Cytokine Production by Different Signaling Pathways in THP-1 Cells.

Sepsis is a complex syndrome resulting from the innate host response to infection. Apart from the well-known anticoagulant effects of heparin, it also possesses various immunomodulatory properties. Thus heparin seems to be a therapeutic drug in sepsis. We have demonstrated that unfractionated heparin (UFH) can inhibit lipopolysaccharide (LPS)-induced inflammatory responses in endothelial cells. The monocyte/macrophage system is a major contributor to host immunity and immune surveillance against infection. The aim of the study is to determine the inhibitory effect of UFH on cytokine production in THP-1 monocytes induced by LPS and to define the possible signaling pathways. The THP-1 cells were treated with UFH (0.1-10 U/mL) for 15 min before exposure to LPS (100 ng/mL). After 1 h, nuclear factor-κB (NF-κB) and phosphorylated inhibitor κB-α (IκB-α), c-Jun, c-fos, ERK1/2, JNK, and p38 mitogen-activated protein kinase (MAPK) expression levels were evaluated by Western blot. After 6 h, interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), IL-6, IL-8, and IL-18 protein concentrations were measured by enzyme-linked immunosorbent assay. Cell viability was determined by methyl thiazoyltetrazolium (MTT) assay. UFH inhibited LPS-induced phosphorylation of IκB-α, c-Jun, ERK1/2, JNK, and p38 MAPK but not c-fos. UFH also suppressed LPS-induced nuclear translocation of NF-κB. As expected, UFH decreased LPS-induced IL-1β, TNF-α, IL-6, IL-8, and IL-18 protein levels, suggesting that UFH has an anti-inflammatory effect on THP-1 cells by interrupting the MAPK, NF-κB, and c-Jun signaling pathways. UFH could potentially contribute to treatments for sepsis.