Activated Protein C Up-Regulates IL-10 and Inhibits Tissue Factor in Blood Monocytes

Abstract

The protective effect of recombinant activated protein C therapy in patients with severe sepsis likely reflects the ability of recombinant activated protein C to modulate multiple pathways implicated in sepsis pathophysiology. In this study, we examined the effects of recombinant activated protein C on the anti-inflammatory cytokine IL-10 and on the procoagulant molecule tissue factor (TF) in LPS-challenged blood monocytes. Treatment of LPS-stimulated monocytes with recombinant activated protein C resulted in an up-regulation of IL-10 protein production and mRNA synthesis. The up-regulation of IL-10 required the serine protease activity of recombinant activated protein C and was dependent on protease-activated receptor-1, but was independent of the endothelial protein C receptor. At the intracellular level, p38 MAPK activation was required for recombinant activated protein C-mediated up-regulation of IL-10. We further observed that incubation of LPS-stimulated monocytes with recombinant activated protein C down-regulated TF Ag and activity levels. This anticoagulant effect of recombinant activated protein C was dependent on IL-10 since neutralization of endogenously produced IL-10 abrogated the effect. In patients with severe sepsis, plasma IL-10 levels were markedly higher in those treated with recombinant activated protein C than in those who did not receive recombinant activated protein C. This study reveals novel regulatory functions of recombinant activated protein C, specifically the up-regulation of IL-10 and the inhibition of TF activity in monocytes. Our data further suggest that these activities of recombinant activated protein C are directly linked: the recombinant activated protein C-mediated up-regulation of IL-10 reduces TF in circulating monocytes.

The efficacy of activated protein C in murine endotoxemia is dependent on integrin CD11b

“…However, the mechanism underlying its antiinflammatory function is poorly understood, particularly in regard to the involvement of its receptor, EPCR (12,(14)(15)(16)(17)(18). Here, we report our evidence, using LPS-induced lethal endotoxemia as a model of sepsis in mice, that the efficacy of APC as an effective antiinflammatory agent toward activated macrophages is critically dependent on integrin CD11b/CD18.…”

“…In light of the uncertainties surrounding the role of EPCR in the antiinflammatory activity of APC (12,14,15,17), we studied APC-mediated suppression of IL-6 production by macrophages in response to LPS stimulation. We used BM-derived macrophages, as they exhibited a high degree of homogeneity compared with peritoneal lavaged cells.…”

“…APC also suppresses leukocyte production of the proinflammatory cytokines IL-1β, IL-6, and IL-12 (11,12), potentially by inhibiting Wnt5A expression (13); increases the production of antiinflammatory cytokines IL-10 and TGFβ (14); and blocks neutrophil migration in vitro (15). However, the mechanism underlying its antiinflammatory function is poorly understood, particularly in regard to the involvement of its receptor, EPCR (12,(14)(15)(16)(17)(18).…”

Hemostatic Soluble Plasma Proteins During Acute-Phase Response and Chronic Inflammation

“…On the one hand, APC down-regulates the production of such pro-inflammatory cytokines, as TNF-, IL-1ß, IL-6, and IL-8 in monocytes (Stephenson et al, 2006). On the other hand, APC up-regulates anti-inflammatory IL-10 that can reduce the protein concentration and activity of TF, as it was found after treatment of LPS-stimulated monocytes with recombinant APC, rAPC (Toltl et al, 2008). NF-kB-mediated signal transduction events are modulated directly by APC interaction with EPCR on the plasma membrane of endothelial cells and mononuclears.…”

Recombinant Human Soluble Thrombomodulin is Effective for Severe Childhood EBV-HLH

“…It activates S1P1 (sphingosine 1-phosphate receptor 1) and subsequently PAR-1 (protease-activated receptor-1) [10], having a substantial effect on inflammation due to degradation of alarmins [including histones, nucleosomes, and high mobility group box 1 (HMGB1)] mediated by a lectin-like domain [11][12][13]. We have treated four cases of severe childhood EpsteinBarr virus-associated HLH (EBV-HLH) in combination with antiinflammatory therapy and had good clinical responses.…”