Abstract
BACKGROUND: We have previously shown that incubation of human endothelial cells with mast cell granules results in potentiation of lipopolysaccharide-induced production of interleukin-6 and interleukin-8. AIMS: The objective of the present study was to identify candidate molecules and signal transduction pathways involved in the synergy between mast cell granules and lipopolysaccharide on endothelial cell activation. METHODS: Human umbilical vein endothelial cells were incubated with rat mast cell granules in the presence and absence of lipopolysaccharide, and IL-6 production was quantified. The status of c-Jun amino-terminal kinase and extracellular signal-regulated kinase 1/2 activation, nuclear factor-kappaB translocation and intracellular calcium levels were determined to identify the mechanism of synergy between mast cell granules and lipopolysaccaride. RESULTS: Mast cell granules induced low levels of interleukin-6 production by endothelial cells, and this effect was markedly enhanced by lipopolysaccharide. The results revealed that both serine proteases and histamine present in mast cell granules were involved in this activation process. Mast cell granules increased intracellular calcium, and activated c-Jun amino-terminal kinase and extracellular signal-regulated kinase 1/2. The combination of lipopolysaccharide and mast cell granules prolonged c-Jun amino-terminal kinase activity beyond the duration of induction by either stimulant alone and was entirely due to active proteases. However, both proteases and histamine contributed to calcium mobilization and extracellular signal-regulated kinase 1/2 activation. The nuclear translocation of nuclear factor-kappaB proteins was of greater magnitude in endothelial cells treated with the combination of mast cell granules and lipopolysaccharide. CONCLUSIONS:Mast cell granule serine proteases and histamine can amplify lipopolysaccharide-induced endothelial cell activation, which involves calcium mobilization, mitogen-activated protein kinase activation and nuclear factor-kappaB translocation.
Highlights
Vascular endothelium functions as a selective barrier between blood and tissues, and regulates many aspects of the inflammatory and immune responses
The results presented in this report demonstrate that mast cell granules (MCG) are capable of inducing intracellular Ca2' mobilization, activation of mitogen-activated protein (MAP) kinases, and translocation of NFkB, and that both serine proteases and histamine present in MCG participate in the potentiation of LPSinduced endothelial cell activation
The results presented here reveal that MCG directly activate human endothelial cells to release low levels of IL-6
Summary
Vascular endothelium functions as a selective barrier between blood and tissues, and regulates many aspects of the inflammatory and immune responses. The status of c-Jun aminoterminal kinase and extracellular signal-regulated kinase 1/2 activation, nuclear factor-kB translocation and intracellular calcium levels were determined to identify the mechanism of synergy between mast cell granules and lipopolysaccaride. The combination of lipopolysaccharide and mast cell granules prolonged c-Jun amino-terminal kinase activity beyond the duration of induction by either stimulant alone and was entirely due to active proteases. Both proteases and histamine contributed to calcium mobilization and extracellular signal-regulated kinase 1/2 activation. Conclusions : Mast cell granule serine proteases and histamine can amplify lipopolysaccharide-induced endothelial cell activation, which involves calcium mobilization, mitogen-activated protein kinase activation and nuclear factor-kB translocation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
