TGF-β1 epigenetically modifies Thy-1 expression in primary lung fibroblasts

Area of Science:

• Pulmonary Medicine
• Epigenetics
• Cell Biology

Background:

• Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with increasing incidence in aging populations.
• Aging lungs exhibit a profibrotic phenotype characterized by decreased thymocyte differentiation antigen 1 (Thy-1) and increased transforming growth factor-beta 1 (TGF-β1).
• Thy-1 expression is known to be epigenetically regulated.

Purpose of the Study:

• To investigate the epigenetic mechanisms by which TGF-β1 influences lung fibroblast phenotype.
• To determine the role of DNA methylation in TGF-β1-induced changes in Thy-1 expression.
• To evaluate the therapeutic potential of DNA methyltransferase (DNMT) inhibition in mitigating TGF-β1-driven profibrotic responses.

Main Methods:

• Primary lung fibroblasts (PLFs) were treated with TGF-β1 and/or the DNMT inhibitor 5-aza-2'-deoxycytidine (5-AZA).
• Gene and protein expression of Thy-1, α-smooth muscle actin (α-SMA), and collagen type 1 (Col1A1) were assessed.
• DNMT activity and Thy-1 promoter methylation were quantified.
• DNMT1 was inhibited using silencing RNA (siRNA) in the presence of TGF-β1.

Main Results:

• TGF-β1 inhibited Thy-1 expression in PLFs, an effect ameliorated by 5-AZA, which also appeared to inhibit DNMT1 activation.
• TGF-β1 induced Thy-1 promoter methylation, and 5-AZA treatment attenuated TGF-β1-induced Col1A1 and α-SMA gene expression.
• DNMT1 inhibition by siRNA reduced TGF-β1-induced DNMT activity, suppressed Thy-1, α-SMA, and Col1A1 expression, and decreased Thy-1 promoter methylation.
• 5-AZA treatment inhibited stress fiber formation, indicated by immunofluorescence for α-SMA.

Conclusions:

• TGF-β1 epigenetically regulates lung fibroblast phenotype through methylation of the Thy-1 promoter.
• Targeted DNMT inhibition may prevent fibroblast to myofibroblast transdifferentiation and collagen deposition.
• Inhibition of DNMT could be a potential therapeutic strategy to prevent fibrogenesis in the lung and other organs.