Effect of TGF-β on ocular surface epithelial cells

Area of Science:

• Ophthalmology
• Cell Biology
• Immunology

Background:

• Transforming growth factor-beta (TGF-β) is implicated in ocular surface disease pathogenesis.
• The role of TGF-β and its receptors in ocular surface epithelial cells under inflammatory conditions requires further investigation.

Purpose of the Study:

• To determine if TGF-β secretion and TGF-β receptor expression (RI, RII, RIII) in human ocular surface epithelial cells are altered by inflammation.
• To investigate the response of these cells to TGF-β.
• To analyze TGF-β pathway activation in ocular surface cells from dry eye patients.

Main Methods:

• Human corneal (HCE) and conjunctival (IOBA-NHC) epithelial cell lines were treated with TGF-β1, TGF-β2, and proinflammatory cytokines (IL-4, TNF-α, IFN-γ).
• Gene expression of TGF-β receptors was analyzed using real-time RT-PCR.
• Protein expression, receptor phosphorylation (pSMAD2/SMAD2), TGF-β isoforms, cytokines, chemokines, metalloproteinases (MMPs), and SLPI secretion were assessed via Western blot, immunofluorescence, and immunoassays.

Main Results:

• Inflammatory cytokines modulated TGF-β receptor expression in HCE and IOBA-NHC cells (e.g., IL-4 down-regulated TGF-β RI, TNF-α upregulated TGF-β RII and TGF-β2).
• TGF-β treatment induced SMAD2 phosphorylation, indicating pathway activation.
• TGF-β significantly altered cytokine/chemokine and MMP secretion. In dry eye patients, TGF-β2 and TGF-β3 were upregulated, while TGF-β RIII mRNA was downregulated in conjunctival epithelium.

Conclusions:

• TGF-β plays a significant role in modulating inflammatory responses within ocular surface epithelial cells.
• Differential regulation of TGF-β receptors and isoforms under inflammatory conditions and in dry eye disease suggests a key role in ocular surface homeostasis and pathology.