Fibroblasts from Idiopathic Pulmonary Fibrosis and Normal Lungs Differ in Growth Rate, Apoptosis, and Tissue Inhibitor of Metalloproteinases Expression

Abstract

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disorder characterized by fibroblast proliferation and extracellular matrix accumulation. However, studies on fibroblast growth rate and collagen synthesis have given contradictory results. Here we analyzed fibroblast growth rate by a formazan-based chromogenic assay; fibroblast apoptosis by in situ end labeling (ISEL) and propidium iodide staining; percent of alpha-smooth muscle actin (alpha-SMA) positive cells by fluorescence-activated cell sorter; and alpha1-(I) collagen, transforming growth factor (TGF)-beta1, collagenase-1, gelatinases A and B, and tissue inhibitor of metalloproteinase (TIMP)-1, -2, -3, and -4 expression by reverse transcriptase/polymerase chain reaction in fibroblasts derived from IPF and control lungs. Growth rate was significantly lower in IPF fibroblasts compared with controls (13.3 +/- 38.5% versus 294.6 +/- 57%, P < 0.0001 at 13 d). Conversely, a significantly higher percentage of apoptotic cells was observed in IPF-derived fibroblasts (ISEL: 31.9 +/- 7.0% versus 15.5 +/- 7.6% from controls; P < 0.008). alpha-SMA analysis revealed a significantly higher percentage of myofibroblasts in IPF samples (62.8 +/- 25.2% versus 14.8 +/- 11.7% from controls; P < 0.01). IPF fibroblasts were characterized by an increase in pro-alpha1-(I) collagen, TGF-beta1, gelatinase B, and all TIMPs' gene expression, whereas collagenase-1 and gelatinase A expression showed no differences. These results suggest that fibroblasts from IPF exhibit a profibrotic secretory phenotype, with lower growth rate and increased spontaneous apoptosis.

Role of α1 and α2 chains of type IV collagen in early fibrotic lesions of idiopathic interstitial pneumonias and migration of lung fibroblasts

“…It is known that the majority of fibrosis progression of UIP demonstrates a slow progression over many years. 44 This is in accord with the studies which show that cultured fibroblasts from patients with IPF/UIP have low growth rate compared with that of normal controls 49,50 and the proliferative activity of fibroblasts in fibroblastic foci of UIP tends to be lower than those in intraluminal buds of OP by Ki-67 immunoreactivity. 51 We also previously reported that deposition of tissue inhibitors of metalloproteinase-2, which inhibits cell migration, 52 is greater in fibroblastic foci of UIP than in intraluminal buds of OP.…”

Pin1 Protein Regulates Smad Protein Signaling and Pulmonary Fibrosis

“…S14). In patients with IPF and asthma, collagens, TIMPs, and profibrogenic cytokines are increased (32,33) whereas the levels of MMPs vary, depending on the stage of the disease (16). Therefore, Pin1 inhibitors, several of which show nanomolar K i and favorable cell permeability (34), may be effective to treat fibrotic diseases of the lung.…”

Profibrotic Phenotype of Conjunctival Fibroblasts from Mucous Membrane Pemphigoid

“…Profibrotic phenotypes are observed and maintained in vitro in fibroblasts from patients with scleroderma, pulmonary, renal, and colonic fibrosis. [13][14][15] There is some evidence of phenotypic changes in fibroblasts isolated from mucous membrane pemphigoid patients, 16 -18 but whether there are pathological alterations in key aspects of fibroblast behavior, such as motility, contractile function, matrix synthesis, and development of myofibroblast characteristics, has not been investigated. Moreover, whether there are differences in fibroblasts isolated from actively inflamed tissue compared with fibroblasts isolated from clinically uninflamed tissue is unknown.…”