Induction of inflammatory cytokine release from human umbilical vein endothelial cells by agonists of proteinase-activated receptor-2.

1. Human endothelial cells express proteinase-activated receptor-2 (PAR-2), inflammatory cytokines and trypsin (EC 3.4.

Modulation of expression and function of Toll-like receptor 3 in A549 and H292 cells by histamine.

It was reported recently that histamine induced Toll-like receptor (TLR)2 and TLR4 expression in endothelial cells and enhanced their sensitivity to Gram-positive and Gram-negative bacteria; and that TLRs were expressed in airway epithelial cells and that several inflammatory mediators modulated their expression. However, little is known of potential influence of histamine on TLRs in pulmonary epithelial cells. In the present study, effects of histamine on expression of TLRs in both human A549 and NCI-H292 cell lines were examined by using real-time quantitative RT-PCR analysis, flow cytometry and immunofluorescent staining.

Potent histamine-releasing activity of atrahagin, a novel snake venom metalloproteinase.

Poisonous snakebite wound is a popular disease worldwide. However, the pathogenesis remains unclear. In the present study, a novel metalloproteinase atrahagin in Chinese cobra (Naja atra) snake venom was purified, using heparin-sepharose followed by Superdex 75 gel filtration chromatography.

Inhibition of tryptase release from human colon mast cells by histamine receptor antagonists.

The main objective of this study was to investigate the ability of histamine receptor antagonists to modulate tryptase release from human colon mast cells induced by histamine. Enzymatically dispersed cells from human colon were challenged with histamine in the absence or presence of the histamine receptor antagonists, and the tryptase release was determined. It was found that histamine induced tryptase release from colon mast cells was inhibited by up to approximately 61.

[Histamine release properties of human basophils in response to various stimuli].

Aim: To investigate the effects of protease activated receptor-2 (PAR-2) agonist, heparin and other stimuli on histamine release from human basophils.

Methods: Peripheral blood mononuclear cells (PBMCs) were separated by density gradient centrifugation. The PBMCs were then resuspended in complete Hank's balanced salt solution (HBSS) and challenged with various stimulating agents.

Activation of human tonsil and skin mast cells by agonists of proteinase activated receptor-2.

Aim: To investigate the effects of the agonists of proteinase activated receptor (PAR)-2, and histamine on degranulation of human mast cells.

Methods: Human mast cells were enzymatically dispersed from tonsil and skin tissues. The dispersed cells were then cultured with various stimuli, and tryptase and histamine levels in cell supernatants collected from challenge tubes were measured.

[Effect of tryptase inhibitors on histamine release from human colon mast cells].

Aim: To investigate the effect of tryptase inhibitors (TPIs) on histamine release from human colon mast cells.

Methods: Human mast cells were prepared by digestion of colon tissue and with collagenase and hyaluronidase, cultured with four kinds of TPIs, leupeptin, protamine, TLCK, and lactoferrin for 15 min at 37 degrees Celsius respectively. A glass fibre-based fluorometry assay was used to detect histamine in mast cell suspension.