Fibroblasts isolated after fibrotic lung injury induce apoptosis of
alveolar epithelial cells in vitro.
Uhal, Bruce D., Iravati Joshi, Andrea L. True, Suneel Mundle, Azra
Raza, Annie Pardo, and Moises Selman.
Department of Pharmacology and The Cancer Research Institute, Rush
-Presbyterian St. Luke's Medical Center, Chicago, Illinois; Facultad
de Ciencias, Universidad Nacional Autonoma de Mexico, Mexico D.F.,
Mexico; Instituto Nacional de Enfermedades Respiratorias, Mexico,
D.F., Mexico
APStracts 2:0151L, 1995.
Primary lung fibroblasts were isolated from patients with idiopathic
pulmonary fibrosis (HIPF) and from normal lung tissue adjacent to
resected tumors (NH). In addition, rat lung fibroblasts were isolated
from normal adult rats (NR) and from rats treated with 75% oxygen and
paraquat (PA) to induce experimental fibrotic lung injury. Serum-free
media conditioned by each fibroblast strain were applied to the type
II cell-derived A549 human lung carcinoma cell line (A549) and to
primary type II pneumocytes (AEC) isolated from normal adult rats.
Upon application to A549 or AEC, respectively, HIPF or PA media
stimulated the production of DNA fragments of 200-800 base pairs in
length. The fragmentation was 2.3-fold and 3.5-fold greater than that
induced by NH and NR media, respectively, both of which were no more
potent than was unconditioned serum-free medium alone. Exposure of
confluent cultures of A549 or AEC to HIPF or PA media for 20 hours
resulted in decreases of 25% and 52%, respectively, in total
recoverable DNA and 26% and 72% respectively, in total cell number;
no decreases were observed in response to NH or NR media. Apoptosis
of A549 and AEC was detected by fluorescence microscopy of ethanol
-fixed cells stained with propidium iodide, and was confirmed by
terminal deoxynucleotidyl transferase-mediated bio-dUTP nick end
labeling (TUNEL). The endonuclease inhibitors 10uM aurintricarboxylic
acid and 50uM zinc inhibited HIPF-induced apoptosis of A549 cells by
68% and 71%, respectively. Both apoptosis and necrosis were induced
by HIPF and PA media in a concentration-dependent manner; significant
effects were observed beginning at a 1:10 dilution of either medium.
These results suggest that altered fibroblasts emerging during
fibrotic lung injury release a soluble factor(s) capable of inducing
cell death and net loss of alveolar epithelial cells.
Received 10 September 1995; accepted in final form 4 August 1995.
APS Manuscript Number L110-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 15 September 1995.