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Glucocorticoids modulate TGF-beta production by human fetal lung fibroblasts
Fu-Qiang Wen1, Tadashi Kohyama, C Magnus Sköld
1Pulmonary and Critical Care Medicine Section, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198-5125, USA.
Abstract:
TGF-beta1 is thought to play a central role in pulmonary fibrosis inducing fibroblast differentiation and extracellular matrix synthesis. In human lung fibroblasts, it is still unclear how various TGF-beta isoforms affect TGF-beta production and whether glucocorticoids, commonly used agents to treat fibrotic lung disease, modulate these processes. To this end, human fetal lung fibroblasts (HFLF) were cultured with various concentrations of glucocorticoids (budesonide, dexamethasone or hydrocortisone) with and without TGF-beta1, -beta2, or -beta3. Post-culture media were collected for ELISA assays of TGF-beta1, -beta2, and -beta3. TGF-beta mRNA was assessed by real time RT-PCR. Smad 2, 3, and 4 and AP-1 complex (c-fos and c-Jun) cellular localization were evaluated by immunostaining. TFG-beta2 and -beta3 stimulated TGF-beta1 production significantly (p < 0.01 relative to control). TGF-beta1 stimulated TGF-beta2 production (p < 0.01 relative to control). TGF-beta3 was undetectable. Glucocorticoids significantly inhibited TGF-beta1 and TGF-beta2 production and reduced expression of the up-regulated TGF-beta1 and TGF-beta2 mRNA induced by exogenous TGF-beta1, -beta2, or -beta3 (p < 0.01 for each) but had no effect on Smads. Although c-jun-related nuclear staining was not intensified in TGF-beta-stimulated cells, it was reduced by glucocorticoids. Thus, TGF-beta isoforms may stimulate production of various TGF-beta isoforms in the lung. Glucocorticoids then may block TGF-beta production by modulating mRNA levels and c-Jun.
Insights
Transforming growth factor-beta (TGF-β) isoforms stimulate TGF-β production in lung fibroblasts. Glucocorticoids inhibit this production by affecting mRNA levels and c-Jun, offering potential therapeutic insights for fibrotic lung disease.
Area of Science:
- Pulmonary medicine
- Cell biology
- Molecular biology
Background:
- Transforming growth factor-beta 1 (TGF-β1) is implicated in pulmonary fibrosis.
- The influence of different TGF-β isoforms on TGF-β production in human lung fibroblasts and the effect of glucocorticoids remain unclear.
Purpose of the Study:
- To investigate how TGF-β isoforms (TGF-β1, TGF-β2, TGF-β3) affect TGF-β production in human fetal lung fibroblasts (HFLF).
- To determine if glucocorticoids modulate TGF-β production and related signaling pathways in HFLF.
Main Methods:
- HFLF were cultured with TGF-β isoforms and/or glucocorticoids (budesonide, dexamethasone, hydrocortisone).
- TGF-β1, -β2, and -β3 levels in culture media were measured by ELISA.
- TGF-β mRNA expression was assessed using real-time RT-PCR.
- Cellular localization of Smad proteins and AP-1 complex (c-fos, c-Jun) was evaluated by immunostaining.
Main Results:
- TGF-β2 and TGF-β3 significantly stimulated TGF-β1 production; TGF-β1 stimulated TGF-β2 production. TGF-β3 was undetectable.
- Glucocorticoids significantly inhibited TGF-β1 and TGF-β2 production and reduced their mRNA expression.
- Glucocorticoids reduced c-Jun nuclear staining but did not affect Smad protein localization.
Conclusions:
- Various TGF-β isoforms can stimulate the production of other TGF-β isoforms in lung fibroblasts.
- Glucocorticoids may inhibit TGF-β production by modulating mRNA levels and the c-Jun pathway, suggesting a mechanism for their therapeutic effect in fibrotic lung diseases.
