Effect of Retinoic Acid on the Differentiation and Lysozyme Expression in Human Airway Epithelial Cells

Bakground and Objectives:Retinoic acid (RA-deprived cultures of normal human tracheobronchial epithelial (NHTBE cells became squamous metaplastic, failed to produce mucin and instead secreted or released large amounts of lysozyme (LZ. The purpose of this study was to elucidate the relationship between RA-deficiency induced squamous metaplasia and increased LZ as a function of time. Materials and Method:The change of lysozyme protein and lysozyme mRNA was investigated over time in cultures using passage-2 normal human tracheobronchial epithelial (NHTBEcells and passage-2 normal human keratinocytes (NHK. The amount of lysozyme and mucin was measured with dot blot, message of lysozyme with RT-PCR, and cornifin mRNA with Northern blot. Results:Lysozyme message levels were consistently higher in RA- sufficient than RA-deficient cultures. Intracellular and extracellular LZ increased to a peak on the day 16 and thereafter decreased in the RA-deficient cultures. LZ gene expression in the RA-deficient cultures was barely detectable on the day 7 but was clearly expressed between days 10 and 14 , but thereafter message levels decreased markedly. On day 12, large numbers of cells began to exfoliate in the RA-deficient cultures. Extracellular LZ appeared simultaneously at the apical surface, presumably released from the exfoliated cells, which contained high concentrations of LZ. Intracellular LZ levels were more than 11 fold less in NHK cells compared to NHTBE cells. Conclusion:This study suggests that cellular accumulation of lysozyme protein is a unique feature of metaplastic squamous differentiation. Further studies are needed to find out what mechanisms are involved. (Korean J Otolaryngol 1998;42(12 : 39-46

[1]  J. Koo,et al.  Regulation of the secretory phenotype of human airway epithelium by retinoic acid, triiodothyronine, and extracellular matrix. , 1997, American journal of respiratory cell and molecular biology.

[2]  J. Nickel,et al.  Lysozyme gene expression and regulation. , 1996, EXS.

[3]  P. Nettesheim,et al.  Regulation of mucociliary differentiation of rat tracheal epithelial cells by type I collagen gel substratum. , 1996, American journal of respiratory cell and molecular biology.

[4]  L. Abdullah,et al.  Mucociliary differentiation of serially passaged normal human tracheobronchial epithelial cells. , 1996, American journal of respiratory cell and molecular biology.

[5]  J. Yon-Kahn.  Lysozymes, model enzymes in biochemistry and biology , 1996 .

[6]  S. Randell,et al.  Epidermal growth factor regulates expression of the mucous phenotype of rat tracheal epithelial cells. , 1995, Biochemical and biophysical research communications.

[7]  A. E. Sippel,et al.  Evolution of gene regulation as revealed by differential regulation of the chicken lysozyme transgene and the endogenous mouse lysozyme gene in mouse macrophages. , 1994, European journal of biochemistry.

[8]  C. Dodia,et al.  Synthesis of type II cell lamellar body lysozyme-15 kD protein (lbl-15) by perfused rat lung. , 1994, American journal of respiratory cell and molecular biology.

[9]  W. Fujimoto,et al.  Cornifin, a cross-linked envelope precursor in keratinocytes that is down-regulated by retinoids. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[10]  J. Nadel,et al.  Role of neutrophil elastase in allergen-induced lysozyme secretion in the dog trachea. , 1992, Journal of applied physiology.

[11]  Xin-min Zhang,et al.  Vitamin A deficiency and inflammation: the pivotal role of secretory cells in the development of atrophic, hyperplastic and metaplastic change in the tracheal epithelium in vivo , 1992, Virchows Archiv. B, Cell pathology including molecular pathology.

[12]  S. Gordon,et al.  Cloning the human lysozyme cDNA: inverted Alu repeat in the mRNA and in situ hybridization for macrophages and Paneth cells. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[13]  D. France,et al.  De novo synthesis of lysozyme by human epidermal cells. , 1986, The Journal of investigative dermatology.

[14]  J. S. St. George,et al.  An immunohistochemical characterization of rhesus monkey respiratory secretions using monoclonal antibodies. , 1985, The American review of respiratory disease.

[15]  E. Mcdowell,et al.  Restoration of mucociliary tracheal epithelium following deprivation of vitamin A , 1984, Virchows Archiv. B, Cell pathology including molecular pathology.

[16]  T. Boat,et al.  A comparative study of lysozyme and its secretion by tracheal epithelium. , 1982, Experimental lung research.

[17]  S. Wolbach,et al.  TISSUE CHANGES FOLLOWING DEPRIVATION OF FAT-SOLUBLE A VITAMIN , 1925, The Journal of experimental medicine.