Antiproteases Attenuate the release of Neutrophil Chemotactic Activity from Bronchial Epithelial Cells Induced by Smoke

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Abstract
The released neutrophil chemotactic activity (NCA) from bronchial epithelial cells (BECs) in response to smoke extract was evaluated by reverse-phase, high-performance liquid chromatography (RP-HPLC) and the involvement of proteolytic activity was assessed for the release of NCA from BECs. Smoke extract stimulated the release of NCA (55.3 ± 5.2 vs. 17.3 ± 4.1 cells per high-power field [HPF], p >.001). The released activity determined by RP-HPLC analysis was 15-hydroxyeicosatetraenoic acid and leukotriene B4. Several structurally and functionally different serine protease inhibitors, including α-1-protease inhibitor (α-1-PI), chloromethyl ketone (CK) derivatives, N-tosyl-L-lysine CK (TLCK), methoxysuccinyl-Ala-Ala-Pro-Val CK (SPCK), N-α-tosyl-L-phenylalanine CK (TPCK), and N-α-p-tosyl-L-arginine methyl ester hydrochloride (TAME), attenuated the release of NCA (p >.01) in a dose-dependent fashion. Leupeptin, a cysteine protease inhibitor, has only a small effect on the release of NCA (p >.05), and phosphoramidon, a neutral endopeptidase inhibitor, had no effect. The measurement of proteolytic enzyme activity using synthetic substrate S-2288 revealed that smoke extract significantly (p >.05) augmented the serine protease activity in BEC layers. Culture supernatant fluids and cell lysates of BECs in response to smoke extract solubilized 14C-labeled casein. These results suggest that BECs may release lipoxygenase-derived NCA in response to smoke extract and that the release of NCA may involve the activation of proteolytic activity of BECs which was inhibited by serine protease inhibitors.