miR-21 Exerts Anti-proliferative and Pro-apoptotic Effects in LPS-induced WI-38 Cells via Directly Targeting TIMP3

Area of Science:

• Pulmonary Medicine
• Molecular Biology
• Cell Biology

Background:

• Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease driven by inflammation and tissue damage.
• The role of microRNA-21 (miR-21) in IPF, particularly in lung fibroblasts under inflammatory conditions, remains unclear.

Purpose of the Study:

• To investigate the function of miR-21 in lipopolysaccharide (LPS)-induced injury in embryonic lung-derived diploid fibroblasts (WI-38 cells).
• To elucidate the molecular mechanism by which miR-21 influences cell proliferation, apoptosis, and inflammatory responses in the context of lung injury.

Main Methods:

• Analysis of miRNA expression profiles from public databases (GEO).
• In vitro experiments using WI-38 cells treated with LPS to mimic lung injury.
• Luciferase reporter assays to confirm miR-21 targeting of TIMP3.
• Quantitative real-time PCR (qRT-PCR), Western blotting, and ELISA to assess molecular and inflammatory markers.

Main Results:

• miR-21 levels were elevated in IPF patients and LPS-treated WI-38 cells.
• Overexpression of miR-21 reduced the proliferation and increased apoptosis of LPS-treated WI-38 cells.
• miR-21 directly targets TIMP3; TIMP3 re-established normal proliferation and apoptosis.
• miR-21 modulated apoptotic proteins (Bcl-2, Bax, caspases) and inflammatory cytokines (IL-6, IL-1β, IL-10), effects counteracted by TIMP3.

Conclusions:

• miR-21 aggravates LPS-induced lung injury and modulates inflammatory responses by targeting TIMP3.
• TIMP3 acts as a protective factor against miR-21-mediated lung injury.
• Targeting the miR-21/TIMP3 axis presents a potential therapeutic avenue for IPF.