Proteinases Release Mucin from Airways Goblet Cells

The mucin-release effect of proteinases on airways epithelium was assessed in vitro. Using expiants of rabbit tracheal mucosa-submucosa we determined that elastase and alkaline proteinase from Pseudomonas aeruginosa, pancreatic trypsin and elastase, and the microbial proteinases subtilisin, thermolysin and pronase. all stimulate mucin release from goblet cells. On the other hand Streptomyces caespitosus proteinase, pancreatic chymotrypsin and collagenasc fail to trigger mucin release. Bovine trachea and human nasal polyp epithelium also release mucins in response to proteinases. Mucin release activity is dependent on proteolytic activity of enzymes which have a fairly broad, but generally similar, substrate specificity. The cellular mechanism of action is not known. We propose that mucin secretion in response to proteinases represents a useful defence mechanism but also forms the basis for hypersecretory states and airways obstruction in chronic endobronchial inflammatory states.