Human neutrophil elastase induces hypersecretion of mucin from well-differentiated human bronchial epithelial cells in vitro via a protein kinase C{delta}-mediated mechanism.
The presence of mucus obstruction and neutrophil-predominant inflammation in several lung disorders, such as cystic fibrosis, suggests a relationship between neutrophils and excess mucus production. Mechanisms of human neutrophil elastase (HNE)-induced mucin secretion by well-differentiated normal human bronchial epithelial (NHBE) cells maintained in air/liquid interface culture were investigated. HNE increased mucin secretion in a concentration-dependent manner, with maximal stimulation (more than twofold) occurring within a short (15 minutes) time period. Mucins MUC 5 AC and MUC 5 B, but not MUC 2, were released in response to HNE. Stimulation of mucin secretion required partial elastase enzymatic activity and did not appear to involve a soluble product released by the cells. HNE-stimulated secretion involved activation of protein kinase C (PKC), as HNE exposure rapidly provoked PKC enzymatic activity that was attenuated by the general PKC inhibitors calphostin C and bisindoylmaleimide I. Of the different isoforms, PKCalpha, delta, zeta, lambda, iota, and epsilon were constitutively expressed in NHBE cells while PKCbeta, eta, and mu were PMA-inducible. PKCdelta was the only isoform to translocate from cytoplasm to membrane in response to HNE. Inhibition of PKCdelta attenuated HNE-mediated mucin secretion. The results suggest HNE stimulation of mucin release by human airway epithelial cells involves intracellular activation of PKC, specifically the delta isoform.
Park
Jin-Ah
JA
Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606.
He
Fang
F
Martin
Linda D
LD
Li
Yuehua
Y
Chorley
Brian N
BN
Adler
Kenneth B
KB
D001980:Bronchi / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D019272:Leukocyte Elastase / Q000494:pharmacology*; D009077:Mucins / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology*; D051745:Protein Kinase C-delta; D047428:Protein Kinase Inhibitors / Q000494:pharmacology
D007527:Isoenzymes; D009077:Mucins; D047428:Protein Kinase Inhibitors; C497258:PRKCD protein, human; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D019272:Leukocyte Elastase