Human Keratoconus Cell Contractility is Mediated by Transforming Growth Factor-Beta Isoforms

Area of Science:

• Ophthalmology
• Biomaterials Science
• Extracellular Matrix Biology

Background:

• Keratoconus (KC) is a progressive corneal disease associated with structural defects in the corneal stroma's extracellular matrix (ECM).
• Transforming growth factor-beta (TGF-β) signaling regulates ECM production by corneal keratocytes, and pathway alterations have been noted in KC.
• Previous work identified TGF-β pathway differences between human keratoconus cells (HKCs) and normal corneal fibroblasts (HCFs).

Purpose of the Study:

• To investigate variations in contractility and matrix metalloproteinase (MMP) expression by HKCs compared to HCFs within a 3D collagen gel model.
• To analyze the impact of TGF-β isoforms on ECM contraction and collagen expression in HKCs.
• To explore potential links between altered collagen ratios and the pathobiology of keratoconus.

Main Methods:

• Seeding HKCs and HCFs in 3D-collagen gels to assess matrix contractility.
• Quantifying collagen ratios (Col I:V and Col I:III) in the gels.
• Evaluating MMP expression in response to TGF-β isoforms.

Main Results:

• HKCs exhibited delayed ECM contractility and decreased Collagen I:Collagen V ratios compared to HCFs.
• TGF-β1 significantly enhanced ECM contraction and the expression of Collagen I and Collagen V by HKCs.
• HKCs demonstrated significantly decreased Collagen I:Collagen III ratios, indicating altered collagen isoform expression in KC.

Conclusions:

• HKCs display distinct collagen secretion patterns and delayed matrix contraction in a 3D collagen gel environment compared to HCFs.
• This study introduces a novel collagen gel model for characterizing HKC contractility and MMP expression, offering insights into KC pathobiology.
• Findings suggest that altered collagen composition and ECM remodeling by HKCs contribute to the development of keratoconus.