Unfractionated heparin inhibits lipopolysaccharide-induced inflammatory response through blocking p38 MAPK and NF-κB activation on endothelial cell

Heparins, including unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH), are glycosaminoglycans that are largely used as anti-thrombotic drugs. While the mechanisms of their anticoagulant actions in blood have been extensively studied, their effects on the inflammation of the endothelium are still under investigation since the endothelium plays a central role in sepsis. Furthermore, UFH is much cheaper than LMWH. The aim of this study was to determine how UFH regulates lipopolysaccharide (LPS)-induced inflammatory response on endothelial cells in vitro, and define the role of p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in mediating this effect. Human pulmonary microvascular endothelial cells (HPMECs) were pretreated with UFH (0.01 U/ml-10 U/ml), prior to stimulation with LPS (10 μg/ml). Markers of systemic inflammation and endothelial activation were assessed. Interleukin (IL)-1β, IL-6, E-selectin, intercellular adhesion molecule (ICAM)-1 release were subsequently measured at 2 h, 6 h and 12 h. Phosphorylation of p38 MAPK at 2 h, 6 h and nuclear translocation of the proinflammatory NF-κB at 2 h were assessed. In HPMEC, UFH significantly attenuated LPS-induced production of IL-1β, IL-6, E-selectin and ICAM-1, as well as phosphorylation of p38 MAPK and NF-κB translocation, especially in 10 U/ml. In conclusion, UFH at high dose significantly protects against endothelial-cell-mediated immune response. The inhibition of p38 MAPK and NF-κB activation certainly represents one of the mechanisms by which UFH exerts its anti-inflammatory effect.

Graphical abstractDownload full-size image.Highlights► UFH underlies 10 U/ml does not show any detrimental effect on cells. ► UFH suppresses LPS-induced IL-1β, IL-6, E-selectin and ICAM-1 mRNA expressions. ► UFH significantly attenuated LPS-induced production of IL-6 and ICAM-1 protein. ► UFH inhibits LPS-induced p38 MAPK phosphorylation. ► UFH blocks LPS induced nuclear translocation of the NF-κB p65.