June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Cathepsin S can alter the expression of pro-inflammatory cytokines, proteases, and protease activated receptor associated with inflammatory dry eye in human corneal epithelial cells
Author Affiliations & Notes
  • Wannita Klinngam
    Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , Los Angeles , California, United States
  • Maria Edman
    Department of Ophthalmology, Roski Eye Institute and Keck School of Medicine , University of Southern California, Los Angeles , California, United States
  • Zhen Meng
    Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , Los Angeles , California, United States
  • Sarah Hamm-Alvarez
    Department of Ophthalmology, Roski Eye Institute and Keck School of Medicine , University of Southern California, Los Angeles , California, United States
  • Footnotes
    Commercial Relationships   Wannita Klinngam, None; Maria Edman, None; Zhen Meng, None; Sarah Hamm-Alvarez, None
  • Footnotes
    Support  NIH Grant EY011386 and Unrestricted grant from RPB
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 448. doi:
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    • Get Citation

      Wannita Klinngam, Maria Edman, Zhen Meng, Sarah Hamm-Alvarez; Cathepsin S can alter the expression of pro-inflammatory cytokines, proteases, and protease activated receptor associated with inflammatory dry eye in human corneal epithelial cells. Invest. Ophthalmol. Vis. Sci. 2017;58(8):448.

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

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Abstract

Purpose : Cathepsin S (CTSS) has increased activity in tears of male NOD mice, a murine model of Sjögren’s Syndrome (SS), and is also increased in tears of patients with SS. However, the contribution of its increased activity in tears to the ocular surface inflammation that is a part of SS has not been investigated. We hypothesized that elevated CTSS in tears might drive ocular surface inflammation by altering gene and protein expression of factors linked to corneal inflammation

Methods : The human corneal epithelial cell line (HCE-T) was cultured and treated with recombinant human CTSS at activity levels seen in SS patient tears. Gene expression of pro-inflammatory cytokines, proteases, and protease-activated receptor-2 (PAR-2) were measured after 2-,4-,8-,and 24-hours of treatment by RT-and q-PCR. CTSS protein expression and its activity in lysates were determined using Western Blotting and CTSS activity assay kits, respectively. PAR-2 protein expression was measured by immunofluorescence.

Results : Recombinant human CTSS induced gene expression of IL-6, IL-8, TNF-α and IL-1β at 2 and 4 hours. Increased IL-1β and TNF-α reached a peak at 2 hours (Relative Quantity (RQ)=2, p≤0.001 and ≤0.05 respectively). Increased IL-8 and IL-6 reached a peak at 4 hours (RQ=4, p≤0.001). CTSS, MMP-9, and PAR-2 gene expression was increased after 24-hour treatment (RQ= 4, 2, and 1.5 respectively, p≤0.001). Exposure of HCE-T cells to heat-inactivated CTSS was not as effective as in elevating IL-6 and IL-8 gene expression, suggesting that CTSS protein activity was important in eliciting the effect. Recombinant human CTSS exposure also increased expression of endogenous CTSS protein levels and endogenous CTSS activity (fold change=3.5, p≤0.05) after 24 hrs. Finally, recombinant human CTSS increased PAR-2 immunofluorescence after 24 hours.

Conclusions : These findings suggest that elevated CTSS levels in tears of SS patients may induce inflammatory cytokines, proteases, and PAR-2 expression in corneal epithelial cells, possibly contributing to ocular surface inflammation in SS patients.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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