Mitogenic effect of lysosomal hydrolases on bovine tracheal myocytes in culture.
Studies were conducted to assess the mitogenic effect of lysosomal hydrolases, enzymes known to have an association with allergen- or ozone-induced airway hyperreactivity, on bovine tracheal myocytes in culture. Addition of purified human placental beta-hexosaminidase and partially purified bovine liver beta-glucuronidase resulted in the doubling of cell count after 4 d of incubation in medium M199 with 0.4% FBS. Unstimulated cells remained quiescent without a significant increase of cell count. Lysosomal hydrolases also selectively enhanced 3H-thymidine incorporation four to seven times more than that in vehicle-treated cells or cells treated with endotoxin, a common contaminant of purified enzymes. Ovalbumin (glycoprotein control), pronase, and lysozyme caused a modest but statistically insignificant increase (up to twofold) in 3H-thymidine incorporation. Elastase, collagenase and dialyzed E. coli beta-glucuronidase had no effect. The mitogenic effect of hydrolases was equally seen in quiescent, serum-depleted cells as well as in those maintained in medium with 10% FBS, suggesting that it was independent of serum factors. The effect of lysosomal hydrolases was inhibited by exposure to yeast mannan, and mannosylated human serum albumin had a mitogenic effect, suggesting the involvement of a mannose receptor. We conclude that lysosomal hydrolases may play a role in the development of the hyperplasia/hypertrophy of respiratory smooth muscle.
Lew
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DB
Department of Pediatrics, University of Tennessee, Memphis 38163.
Rattazzi
M C
MC
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001790:Blood Physiological Phenomena; D002417:Cattle; D002478:Cells, Cultured; D006867:Hydrolases / Q000494:pharmacology*; D037181:Lectins, C-Type; D008247:Lysosomes / Q000201:enzymology*; D008358:Mannose / Q000494:pharmacology; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008934:Mitogens / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects*; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic / Q000502:physiology; D014132:Trachea / Q000187:drug effects*; D001619:beta-N-Acetylhexosaminidases / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008934:Mitogens; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D006867:Hydrolases; D001619:beta-N-Acetylhexosaminidases; D008358:Mannose