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Tina Wong, Sharon Finger, Li-Fong Seet; SPARC Deficiency Prolongs Bleb Survival In A Mouse Model Of Glaucoma Filtration Surgery By Attenuating Pro-inflammatory and Pro-fibrotic Gene Expression. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2136.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma filtration surgery (GFS) commonly fails due to scarring at the surgical site. We have previously reported that the SPARC knockout (Sparc-/-) mouse exhibited significantly improved bleb survival in the mouse model of GFS. Besides inhibiting collagen deposition, other possible mechanisms by which SPARC deficiency exerts anti-fibrotic effects are as yet unknown. In the current study, we describe the differential gene expression changes in the early and late phases of subconjunctival wound healing in the SPARC knockout mouse following experimental glaucoma surgery.
Modified GFS was performed on both WT and Sparc-/- mouse. Surgery was performed on the left eyes only. Bleb tissue and conjunctiva from the contralateral unoperated eye were harvested at Day 2 and Day 7 post-surgery. The unoperated tissue was used as baseline control to calculate the fold change in gene expression after surgery. mRNA expression of extracellular matrix (ECM), ECM-modifying, and pro-inflammatory cytokine genes were quantified using real-time PCR (qPCR) analysis. Cytokine expression was quantified using a multiplexed antibody-based assay (n=15 per genotype per time point).
qPCR analysis indicated that induction of GM-CSF, IL-6, IL-13, TNF-α and MMP-1 mRNA transcripts were significantly reduced at Day 2 post-surgery in the Sparc-/- mouse compared to WT. On Day 7-post-surgery, the induction of ColIa1 mRNA transcript was significantly reduced in the Sparc-/- mouse compared to WT. At the protein level, the induction of GM-CSF was profoundly reduced on Day 7 post-surgery in Sparc-/- mice.
Our data suggests that SPARC deficiency is prolongs bleb survival by attenuating the expression of both pro-fibrotic and pro-inflammatory genes in vivo. In addition to the putative direct effect of SPARC on collagen deposition, SPARC may regulate collagen expression by modulating cytokine-induced signaling pathways. Therefore, silencing SPARC may be a promising therapeutic strategy in modulating post-surgical scarring through the abrogation of early inflammation and late fibrogenesis in wound healing.
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