June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Mechanistic actions of baicalein in human trabecular meshwork cells
Author Affiliations & Notes
  • Hoi-lam Li
    School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • Sze Wan Shan
    School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
  • Daniel W Stamer
    Department of Ophthalmology, Duke University, Durham, North Carolina, United States
    Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States
  • Henry Ho-lung Chan
    School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
    Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
  • Chi-ho To
    School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
    Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
  • Thomas Chuen Lam
    School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
    Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
  • Chi-wai Do
    School of Optometry, The Hong Kong Polytechnic University, Hong Kong, Hong Kong
    Centre for Eye and Vision Research (CEVR), 17W Hong Kong Science Park, Hong Kong
  • Footnotes
    Commercial Relationships   Hoi-lam Li None; Sze Wan Shan None; Daniel Stamer None; Henry Chan None; Chi-ho To None; Thomas Chuen Lam None; Chi-wai Do None
  • Footnotes
    Support  Health Medical Research Fund (16172571, ZC3L); PolyU grants (CD65, UAHG, UAG1, UAHD, BD6R); CEVR; RCSV; Shenzhen Science and Technology Innovation Commission (JCYJ20180507183409601)
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 449. doi:
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    • Get Citation

      Hoi-lam Li, Sze Wan Shan, Daniel W Stamer, Henry Ho-lung Chan, Chi-ho To, Thomas Chuen Lam, Chi-wai Do; Mechanistic actions of baicalein in human trabecular meshwork cells. Invest. Ophthalmol. Vis. Sci. 2022;63(7):449.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Baicalein is a natural flavonoid derived from the dried roots of Scutellaria baicalensis Georgi. We have previously demonstrated that baicalein lowers intraocular pressure (IOP) by increasing trabecular meshwork (TM) outflow facility. In this study, we investigated the mechanistic effects underlying the baicalein-mediated increase in outflow facility.

Methods : Five independent strains of primary human TM (hTM) cells were used. The effects of baicalein on hTM cell volume regulation, cell contractility and cell migration were determined by electronic cell sorting, collagen gel assay and scratch assay, respectively. Measurements of phosphorylated myosin light chain (pMLC) were conducted by Western blot analysis. Differential protein expression profile after baicalein treatment for 3 hours was assessed using isobaric tag for relative and absolute quantitation (iTRAQ) based quantitative proteomics.

Results : Our results showed that baicalein (1-100 µM) had no effect on cell volume under iso-osmotic condition, but caused a concentration-dependent inhibition of regulatory volume decrease (RVD) by up to 70% under hypotonic condition. Similarly, baicalein exhibited a concentration-dependent hTM cell relaxation and retarded cell migration when compared to the vehicle control. At 100 µM, baicalein reduced MLC phosphorylation by 18±9% (n=4, p<0.05). After a 3-hour baicalein treatment, 47 proteins were significantly regulated in hTM cells (n=3, p<0.05). Consistent with in vitro findings, baicalein significantly altered the expression of pre-B-cell leukemia transcription factor-interacting protein 1 (PBXIP1, ↓60%), matrix metalloproteinase-14 (MMP-14, ↑14%) and cathepsin B (CTSB, ↑51%).

Conclusions : These findings suggest that baicalein triggers cell relaxation via MLC phosphorylation along with inhibiting RVD and migratory behavior in hTM cells. The baicalein-mediated changes in protein expression support the notion of altered extracellular matrix homeostasis, potentially contributing to a reduction of outflow resistance and thereby IOP.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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