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That Stimulates Prostaglandin E2 Production by Fibroblasts*
* From the Department of Medicine (Drs. Pan, Westcott, and Mason), National Jewish Medical and Research Center, Denver, CO; and Division of Pulmonary Biology (Dr. Shannon), Childrens Hospital Medical Center, Cincinnati, OH.
Correspondence to: Tianli Pan, PhD, National Jewish Medical and Research Center, 1400 Jackson St, Denver, CO 80206
Alveolar type
II cells inhibit lung
fibroblast proliferation by secreting a factor(s) that stimulates
prostaglandin E2 (PGE2) production by
fibroblasts. In the present study, we further defined this factor(s)
secreted by alveolar type II cells. Human lung fibroblasts were
suspended in rat tail collagen and co-cultured with rat type II cells.
Media were collected and antagonists added during days 9 to 12 in
culture when fibroblast growth inhibition was maximal. Interleukin
(IL)-1 receptor antagonist strongly reduced PGE2
concentration in the media. IL-1ß was present in the conditioned
media (CM), but exogenous rat IL-1ß did not stimulate
PGE2 production by human fibroblasts. IL-1
was below
level of detection in all CM except CM without serum collected from day
9 to 13 (IL-1
= 40.3 ± 12.4 pg/mL), which was also the
condition for highest PGE2 levels. Exogenous rat
IL-1
stimulated PGE2 production by human fibroblasts,
and on antibody to IL-1
decreased PGE2 levels.
Transforming growth factor-ß1 was present in CM but did
not increase on days 9 to 13. Exogenous human transforming growth
factor-ß1 did not stimulate PGE2 production
by these fibroblasts. Cyclooxygenase-2 and connective tissue growth
factor messenger RNA were expressed at higher levels in fibroblasts
from the co-cultures, but there were no changes in collagenase 1 and
fibronectin. In separate experiments, we could not find stimulation of
fibroblast growth by performing to co-cultures under serum-free
conditions or with 0.4% serum instead of 10% serum. In our co-culture
system, alveolar type II cells inhibit proliferation by secreting
IL-1
, and IL-1
stimulates PGE2 production by human
lung fibroblasts.
Footnotes
Abbreviations: CM = conditioned media; IL = interleukin; PGE2 = prostaglandin E2
Supported by National Institutes of Health grant HL56556.
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