Effect of a Kinin B2 Receptor Antagonist on LPS- and Cytokine-induced Neutrophil Migration in Rats

1 This study examines the involvement of kinins in neutrophil migration into rat subcutaneous air pouches triggered by lipopolysaccharide (LPS), as well as the putative roles played by kinin B(1) and B(2) receptors, tumour necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1beta) and selectins in this response. 2 LPS (5 ng to 10 micro g cavity(-1)) injected into the 6-day-old pouch induced a dose- and time-dependent neutrophil migration which peaked between 4 and 6 h, and was maximal following the dose of 100 ng cavity(-1) (saline: 0.46+/-0.1; LPS: 43+/-3.70 x 10(6) cells cavity(-1) at 6 h). 3 Bradykinin (BK) (600 nmol) injected into the pouch of saline-treated rats induced only modest neutrophil migration (0.73+/-0.16 x 10(6) cells cavity(-1)). A more robust response to BK (3.2+/-0.25 x 10(6) cells cavity(-1)) was seen in animals pretreated with captopril, but this was still smaller than the responses to IL-1beta or TNF-alpha (15 pmol: 23+/-2.2 x 10(6) and 75 pmol: 29.5+/-2 x 10(6) cells cavity(-1), respectively). Nevertheless, the B(1) agonist des-Arg(9)-BK (600 nmol) failed to induce neutrophil migration. 4 HOE-140 (1 and 2 mg kg(-1)), a B(2) receptor antagonist, reduced LPS-induced neutrophil migration. HOE-140 also reduced the neutrophil migration induced by BK, but had no effect on the migration promoted by IL-1beta or TNF-alpha. des-Arg(9)-[Leu(8)]-BK, B(1) receptor antagonist was ineffective in changing neutrophil migration caused by any of these stimuli. 5 Neutrophil migration induced by LPS or BK was reduced by interleukin-1 receptor antagonist (IL-1ra) (1 mg kg(-1)), sheep anti-rat TNF serum (anti-TNF serum) (0.3 ml cavity(-1)), and the nonspecific selectin inhibitor fucoidin (10 mg kg(-1)). 6 TNF-alpha levels in the pouch fluid were increased by LPS or BK injection, peaking at 0.5-1 h and gradually declining thereafter up to 6 h. IL-1beta levels increased steadily throughout the 6 h period. HOE-140 markedly inhibited the rise in IL-1beta and TNF-alpha levels in pouch fluid triggered by both stimuli. 7 These results indicate that BK participates importantly in selectin-dependent neutrophil migration into the air pouch triggered by LPS in the rat, by stimulating B(2) receptors coupled to synthesis/release of TNF-alpha and IL-1beta.