Biomechanical rigidity and quantitative proteomics analysis of segmental regions of the trabecular meshwork at physiologic and elevated pressures

Janice A. Vranka, Julia A. Staverosky, Ashok P. Reddy, Phillip A. Wilmarth, Larry L. David, Ted S. Acott, Paul Russell, Vijay Krishna Raghunathan

Research output: Contribution to journalArticle

Abstract

PURPOSE. The extracellular matrix (ECM) of the trabecular meshwork (TM) modulates resistance to aqueous humor outflow, thereby regulating IOP. Glaucoma, a leading cause of irreversible blindness worldwide, is associated with changes in the ECM of the TM. The elastic modulus of glaucomatous TM is larger than age-matched normal TM; however, the biomechanical properties of segmental low (LF) and high flow (HF) TM regions and their response to elevated pressure, are unknown. METHODS. We perfused human anterior segments at two pressures using an ex vivo organ culture system. After extraction, we measured the elastic modulus of HF and LF TM regions by atomic force microscopy and quantitated protein differences by proteomics analyses. RESULTS. The elastic modulus of LF regions was 2.3-fold larger than HF regions at physiological (1×) pressure, and 7.4-fold or 3.5-fold larger than HF regions at elevated (2×) pressure after 24 or 72 hours, respectively. Using quantitative proteomics, comparisons were made between HF and LF regions at 1× or 2× pressure. Significant ECM protein differences were observed between LF and HF regions perfused at 23, and between HF regions at 13 compared to 2× pressures. Decorin, TGF-β-induced protein, keratocan, lumican, dermatopontin, and thrombospondin 4 were common differential candidates in both comparisons. CONCLUSIONS. These data show changes in biomechanical properties of segmental regions within the TM in response to elevated pressure, and levels of specific ECM proteins. Further studies are needed to determine whether these ECM proteins are specifically involved in outflow resistance and IOP homeostasis.

LanguageEnglish (US)
Pages246-259
Number of pages14
JournalInvestigative Ophthalmology and Visual Science
Volume59
Issue number1
DOIs
StatePublished - Jan 1 2018

Fingerprint

Trabecular Meshwork
Proteomics
Pressure
Elastic Modulus
Extracellular Matrix Proteins
Extracellular Matrix
Decorin
Aqueous Humor
Atomic Force Microscopy
Organ Culture Techniques
Blindness
Transforming Growth Factor beta
Glaucoma
Proteins
Homeostasis

Keywords

  • Anterior segment
  • Atomic forcy microscopy
  • Biomechanics
  • Proteomics
  • Trabecular meshwork

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Biomechanical rigidity and quantitative proteomics analysis of segmental regions of the trabecular meshwork at physiologic and elevated pressures. / Vranka, Janice A.; Staverosky, Julia A.; Reddy, Ashok P.; Wilmarth, Phillip A.; David, Larry L.; Acott, Ted S.; Russell, Paul; Raghunathan, Vijay Krishna.

In: Investigative Ophthalmology and Visual Science, Vol. 59, No. 1, 01.01.2018, p. 246-259.

Research output: Contribution to journalArticle

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abstract = "PURPOSE. The extracellular matrix (ECM) of the trabecular meshwork (TM) modulates resistance to aqueous humor outflow, thereby regulating IOP. Glaucoma, a leading cause of irreversible blindness worldwide, is associated with changes in the ECM of the TM. The elastic modulus of glaucomatous TM is larger than age-matched normal TM; however, the biomechanical properties of segmental low (LF) and high flow (HF) TM regions and their response to elevated pressure, are unknown. METHODS. We perfused human anterior segments at two pressures using an ex vivo organ culture system. After extraction, we measured the elastic modulus of HF and LF TM regions by atomic force microscopy and quantitated protein differences by proteomics analyses. RESULTS. The elastic modulus of LF regions was 2.3-fold larger than HF regions at physiological (1×) pressure, and 7.4-fold or 3.5-fold larger than HF regions at elevated (2×) pressure after 24 or 72 hours, respectively. Using quantitative proteomics, comparisons were made between HF and LF regions at 1× or 2× pressure. Significant ECM protein differences were observed between LF and HF regions perfused at 23, and between HF regions at 13 compared to 2× pressures. Decorin, TGF-β-induced protein, keratocan, lumican, dermatopontin, and thrombospondin 4 were common differential candidates in both comparisons. CONCLUSIONS. These data show changes in biomechanical properties of segmental regions within the TM in response to elevated pressure, and levels of specific ECM proteins. Further studies are needed to determine whether these ECM proteins are specifically involved in outflow resistance and IOP homeostasis.",
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AU - Wilmarth, Phillip A.

AU - David, Larry L.

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AU - Raghunathan, Vijay Krishna

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