Fibrotic extracellular matrix activates a profibrotic positive feedback loop
Matthew W. Parker, … , Ola Larsson, Peter B. Bitterman
Matthew W. Parker, … , Ola Larsson, Peter B. Bitterman
Published March 3, 2014
Citation Information: J Clin Invest. 2014;124(4):1622-1635. https://doi.org/10.1172/JCI71386.
View: Text | PDF
Research Article Pulmonology

Fibrotic extracellular matrix activates a profibrotic positive feedback loop

Abstract

Pathological remodeling of the extracellular matrix (ECM) by fibroblasts leads to organ failure. Development of idiopathic pulmonary fibrosis (IPF) is characterized by a progressive fibrotic scarring in the lung that ultimately leads to asphyxiation; however, the cascade of events that promote IPF are not well defined. Here, we examined how the interplay between the ECM and fibroblasts affects both the transcriptome and translatome by culturing primary fibroblasts generated from IPF patient lung tissue or nonfibrotic lung tissue on decellularized lung ECM from either IPF or control patients. Surprisingly, the origin of the ECM had a greater impact on gene expression than did cell origin, and differences in translational control were more prominent than alterations in transcriptional regulation. Strikingly, genes that were translationally activated by IPF-derived ECM were enriched for those encoding ECM proteins detected in IPF tissue. We determined that genes encoding IPF-associated ECM proteins are targets for miR-29, which was downregulated in fibroblasts grown on IPF-derived ECM, and baseline expression of ECM targets could be restored by overexpression of miR-29. Our data support a model in which fibroblasts are activated to pathologically remodel the ECM in IPF via a positive feedback loop between fibroblasts and aberrant ECM. Interrupting this loop may be a strategy for IPF treatment.

Authors

Matthew W. Parker, Daniel Rossi, Mark Peterson, Karen Smith, Kristina Sikström, Eric S. White, John E. Connett, Craig A. Henke, Ola Larsson, Peter B. Bitterman

×

Figure 1

Pathological gene expression in fibrotic fibroblasts is primarily governed by diseased ECM.

Options: View larger image (or click on image) Download as PowerPoint
Pathological gene expression in fibrotic fibroblasts is primarily govern...
(A) Experimental design. IPF or control fibroblasts were cultured on IPF or control ECM using a 2 × 2 experimental design. (B) Isolation of polysome-associated RNA. Sample polysome tracing shows absorbance at 254 nm across the sucrose gradient. Transcripts that are translated are enriched among polysome-associated RNA. The portion of the gradient collected to measure polysome-associated RNA levels is indicated. (C–H) Histograms of gene-by-gene P values for different biological comparisons. Dashed lines represent theoretical null distributions. (C–E) Comparison of polysome-associated RNA levels of (C) IPF fibroblasts seeded on IPF ECM and control fibroblasts seeded on control ECM, (D) IPF fibroblasts and control fibroblasts (independent of ECM type), and (E) IPF and control ECM (independent of cell origin). (F–H) Same comparisons as in A–C using steady-state RNA data. (I) Genes that showed cell origin modulation in polysome-associated RNA (P < 0.05) in both our current study and in a previous study (microarray data obtained from GSE11196) were collected. Plotted are the fold changes in the previous study (x axis) and in our current dataset (y axis). Genes upregulated in one study are more likely to be upregulated in the other (κ = 0.476, 95% CI = [0.269, 0.682]). (J) Histogram of P values for comparison of RNA obtained from control and IPF cells grown under standard culture conditions (microarray data obtained from GEO GSE10921).