Bradykinin- and lipopolysaccharide-induced bradykinin B2 receptor expression, interleukin 8 release and “nitrosative stress” in bronchial epithelial cells BEAS-2B: Role for neutrophils

Abstract

Bradykinin-induced interleukin (IL)-8 release should potentially activate neutrophils releasing myeloperoxidase (MPO) and subsequently generating “nitrosative stress”.We studied bradykinin-induced expression of bradykinin B2 receptor and bradykinin- and lipopolysaccharide (LPS)-induced IL-8 release, MPO (marker of neutrophil activation) and 3-nitrotyrosine (3-NT; marker of “nitrosative stress”) production in human bronchial epithelial cells BEAS-2B alone or in co-culture with human neutrophils.We evaluated B2 receptor protein expression in BEAS-2B cells by immunostainings and Western blot analysis, and measured respectively bradykinin- or LPS-induced IL-8 release in BEAS-2B cells and bradykinin- and/or LPS-induced MPO and 3-NT production in BEAS-2B cells co-cultured with human neutrophils by ELISA. In addition, we evaluated bradykinin- and/or LPS-induced 3-NT formation in BEAS-2B cells co-cultured with human neutrophils by immunocytochemistry.Bradykinin up-regulates B2 receptor expression (P<0.05) and stimulate IL-8 release (P<0.001) in BEAS-2B cells. Either the selective bradykinin B2 receptor antagonist HOE 140 or the selective bradykinin B1 receptor antagonist Lys-(des-Arg9, Leu8)-bradykinin alone halved IL-8 release and the combination of both drugs suppressed this effect. In BEAS-2B cells co-cultured with human neutrophils bradykinin increased MPO release and 3-NT production compared to BEAS-2B cells with human neutrophils (P<0.001), and the addition of LPS in BEAS-2B cells with human neutrophils and bradykinin induced a further dramatically increase of MPO release and 3-NT formation (P<0.001).Bradykinin and LPS provoked “nitrosative stress”, potentially mediated by IL-8, in bronchial epithelium co-cultured with neutrophils suggesting a role for bradykinin in the amplification of chronic airway inflammation via production of “nitrosative stress”.