Two eosinophil granule proteins, eosinophil peroxidase and major basic protein, inhibit mucin release from hamster tracheal surface epithelial cells in primary culture

Abstract

Objectives and Design: Effects of eosinophil proteins on airway goblet cell mucin release were investigated using primary hamster tracheal surface epithelial (HTSE) cell cultures.¶Materials and Methods: HTSE cells were metabolically labeled using ³H-glucosamine and chased in the presence of varying concentrations of eosinophil proteins. The amount of ³H-mucin in the spent media was measured by Sepharose CL-4B gel-filtration column chromatography. Possible cytotoxicity by the eosinophil proteins was assessed by measurements of both lactic dehydrogenase and mucin release during as well as after the treatment period.¶Results: (1) Neither eosinophil cationic protein nor eosinophil-derived neurotoxin affected mucin release at concentrations up to 10^-6M; (2) both major basic protein (MBP) and eosinophil peroxidase (EPO) inhibited mucin release in a dose-dependent fashion, and the inhibitory effect by these proteins appeared to be reversible; (3) neither MBP nor EPO caused any apparent cytotoxicity at concentrations up to 10^-6M.¶Conclusion: Eosinophil proteins such as MBP and EPO inhibit mucin release from primary HTSE cells without causing any apparent cytotoxicity.