Interleukin-8 gene expression by a pulmonary epithelial cell line. A model for cytokine networks in the lung.
Cellular constituents of the alveolar-capillary wall may be key participants in the recruitment of polymorphonuclear leukocytes to the lung through the generation of the novel neutrophil chemotactic peptide interleukin-8 (IL-8). This interaction appears to occur via the ability of human alveolar macrophage (AM)-derived monokines, tumor necrosis factor (TNF), and interleukin-1 (IL-1) to induce gene expression of IL-8 from pulmonary type II-like epithelial cells (A549). Northern blot analysis demonstrated that steady-state IL-8 mRNA expression, by either TNF- or IL-1 beta-treated A549 cells, occurred in both a dose- and time-dependent fashion. Similarly, extracellular antigenic IL-8, as assessed by specific ELISA, was expressed from TNF- or IL-1 beta-stimulated epithelial cells in a time-dependent fashion with maximal IL-8 antigen detected at 24 h poststimulation. Immunohistochemical staining utilizing rabbit anti-human IL-8 antibody identified immunoreactive, cell-associated IL-8 antigen as early as 8 h post-TNF or IL-1 beta stimulation. A549-generated neutrophil chemotactic bioactivity paralleled IL-8 steady-state mRNA levels. Signal specificity was demonstrated in this system as IL-8 mRNA or protein expression by lipopolysaccharide (LPS)-treated A549 cells was not different from unstimulated cells. Although LPS did not serve as a direct stimulus for the production of IL-8 by type II-like epithelial cells, the condition media from LPS-challenged AM induced a significant expression of IL-8 mRNA by the A549 cells. 24-h conditioned media from LPS-treated cells was as potent as either IL-1 beta or TNF in generating steady-state IL-8 mRNA by A549 cells. Preincubation of LPS-treated AM-conditioned media with anti-human TNF or IL-1 beta neutralizing antibodies resulted in significant abrogation of IL-8 gene expression by A549 pulmonary epithelial cells. These findings demonstrate potential cell-to-cell communication circuits that may be important between AMs and pulmonary epithelial cells during the recruitment phase of acute lung inflammation.
Standiford
T J
TJ
University of Michigan Medical School, Department of Pathology, Ann Arbor 48109-0602.
Kunkel
S L
SL
Basha
M A
MA
Chensue
S W
SW
Lynch
J P
JP
Toews
G B
GB
Westwick
J
J
Strieter
R M
RM
D015152:Blotting, Northern; D002450:Cell Communication; D002460:Cell Line; D002634:Chemotaxis, Leukocyte; D016207:Cytokines / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000502:physiology; D015870:Gene Expression; D006801:Humans; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics*; D008168:Lung / Q000502:physiology*; D008264:Macrophages / Q000502:physiology; D011650:Pulmonary Alveoli / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016207:Cytokines; D007375:Interleukin-1; D016209:Interleukin-8; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha