Antiproteases attenuate the release of neutrophil chemotactic activity from bronchial epithelial cells induced by smoke

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), methylsuccinyl-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.