Effects of activation of polymorphonuclear leukocytes on airway goblet cell mucin release in a co-culture system

Objectives and Design: Effects of activated PMN on airway goblet cell mucin release were investigated using a co-culture system in which both tracheal surface epithelial (TSE) cells and PMN from hamsters were present. Materials and methods: TSE cells were metabolically labeled using H-3-glucosamine and chased in the presence of PMN under various experimental designs. PMN were obtained from the bronchoalveolar lavage fluid of hamsters following intratracheal instillation of E. coli endotoxin. The amount of H-3-mucin was measured by Sepharose CL-4B gel-filtration column chromatography. Results: (i) activation of 10(6) PMN by fMLP (0.1 muM) and cytochalasin B (0.1 muM) resulted in production of both the estrolytic (elastolytic) activity and superoxide, (ii) activation of PMN in the co-culture stimulated mucin release from TSE cells followed by a significant degradation of the released mucins, both of which were blocked in a dose-dependent fashion by pretreatment with alpha1-protease inhibitor, and (iii) generation of varying concentrations of superoxide in the TSE cell culture did not affect mucin release from TSE cells. Conclusion: In the co-culture system, activation of PMN results in release and degradation of mucins, both of which are almost entirely accounted for by serine proteases but not other cellular products such as superoxide.