Modulation of albumin‐like protein and lysozyme production by bovine tracheal gland serous cells

Abstract

Bovine tracheal submucosal gland serous cells were cultured in medium supplemented with either 10% fetal calf serum or 2% Ultroser G, a commercial serum substitute for cell culture. The proteins synthesized and secreted into the culture medium during PsS]methionine pulse, chase and isoproterenol-stimulated periods were analyzed. Marked differences in the patterns of secretory radiolabeled proteins with M, values ranging from 15080 to 95000 were observed between pulse and chase media of cells cultured in fetal calf serum and Ultroser G. In the presence of Ultroser G, albumin-like protein production was inhibited 9596 as compared to cultures incubated with fetal calf serum. A bovine lysoxyme-type enzymatic activity was detected only in medium from stimulated cells cultured in Ultroser G. The results suggest that bovine tracheal serous cells synthesize different proteins according to the composition of culture medium and release certain proteins when adrenergically stimulated.

Functions of proteins and lipids in airway secretions

“…JoHNSON et al [31] have also shown that albumin may be actively absorbed from the lumen to interstitium by canine bronchial epithelium, probably involving specialized vesicular transport mechani.sms. Using in vitro culture techniques, we have also demonstrated that an albumin-like protein can be synthesized de novo by bovine tracheal gland serous cells [32], and that the amounts of albumin-like protein released by these cells were dependent on the compo• sition of culture medium [33]. Thus, the discovery that albumin can be actively transported bidirectionally through airways, and also synthesized by airway gland cells, suggests that the albumin protein may contribute to the regulation of lung fluid balance and, consequently, may be an important component in the control of mucus hydration.…”

Airway secretions: new concepts and functions

“…Serum proteins and ions are normally present at the surface of airway epithelial mucosa, but their concentration can undergo marked changes with parallel alterations in mucus hydration and rheology, particularly in chronic inflammatory diseases of the airways, such as cystic fibrosis, acute and chronic bronchitis and asthma. Albumin, normally found on the surface of the mucosa, plays a critical role in mucin hydration and mucus rheology because of its size and polyionic properties [11,12). Nevertheless, during inflammatory processes, its marked increase is responsible for the hyperviscous and adhesive properties of the mucus found in the airways of these patients [4).…”