Altered cytokine production by cystic fibrosis tracheal gland serous cells

Abstract

Human submucosal tracheal glands are now believed to play a major role in the physiopathology of cystic fibrosis (CF). We successfully developed techniques for culturing human tracheal gland serous cells from normal individuals (HTGS cells) and from CF patients (CF-HTGS cells) and have shown that the cultured cells have retained most of their in vivo epithelial and secretory characteristics. In order to determine to what extent the serous cells may participate in the lung defense against infection, we examined the effects of the lipopolysaccharide (LPS) of Pseudomonas aeruginosa on HTGS and CF-HTGS cells, with special reference to tumor necrosis factor alpha (TNF- α), interleukin-6 (IL-6), and IL-8 secretion. HTGS cells showed a daily basal secretion of IL-6 (1.68 ± 0.14 ng/106 cells) and IL-8 (9.6 ± 1.3 ng/106 cells) and no constitutive secretion of TNF-α. Treatment with P. aeruginosa LPS resulted in a significant increase in the basal production of IL-6 (increase of 200% ± 12%) and IL-8 (525% ± 40%) as well as a rapid production of TNF-α (250 ± 38 pg/106 cells). The LPS-induced secretion of IL-6 and IL-8, but not that of TNF-α, was inhibited by glucocorticoids CF- HTGS cells showed a much higher basal secretion of IL-6 (13.2 ± 0.5 ng/106 cells) and IL-8 (45.6 ± 7.2 ng/106 cells) than normal cells. Treatment with the LPS of P. aeruginosa induced increased production of IL-6 (increase of 100% ± 8%) and IL-8 (55% ± 18%) but did not induce the secretion of TNF- α. Neither intracellular TNF-α nor TNF-α transcripts were found in CF- HTGS cells, whereas they were found in normal HTGS cells. In addition, dexamethasone was found to stimulate IL-6 and IL-8 secretion (in the presence or absence of LPS) but did not induce any secretion of TNF-α. All these data indicate that HTGS cells are responsive to P. aeruginosa LPS, which results in an increased secretion of IL-6, IL-8, and TNF-α, the secretion of which appeared to be impaired in CF-HTGS cells.