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SPARC knockdown attenuated TGF-β1-induced fibrotic effects through Smad2/3 pathways in human pterygium fibroblasts
Jianwu Fan1, Xin Zhang2, Yaping Jiang2
1Department of Ophthalmology, Yangpu Hospital, Tongji University School of Medicine, Shanghai, 200090, China; Center for Clinical Research and Translational Medicine, Yangpu Hospital, Tongji University School of Medicine, Shanghai, 200090, China.
Purpose:
Secreted protein acidic and rich in cysteine (SPARC), a matricellular glycoprotein, has been found to regulate processes involved in fibrotic diseases. The aim of this study was to investigate the anti-fibrotic effects of SPARC in primary human pterygium fibroblasts (HPFs) and elucidate the underlying mechanisms.
Methods:
The expression of SPARC in HPFs was knocked down by RNA interference-based approach. Subsequently, we examined the expression of profibrotic markers induced by transforming growth factor-β1 (TGF-β1), including type 1 collagen (COL1), α-smooth muscle actin (α-SMA), and fibronectin (FN). The changes in signaling pathways and matrix metalloproteinases (MMPs) were also detected by western blotting. The cellular migration ability, proliferation ability, apoptosis, and contractile phenotype were detected using the wound healing assay, Cell Counting Kit-8 assay, flow cytometry, and collagen gel contraction assay, respectively. The interaction between SPARC and TGF-β RII was detected by Co-IP RESULTS: Silencing of SPARC inhibited the basal and TGF-β1-induced expression of COL1, α-SMA, and FN in HPFs, and suppressed the expression of p-Smad2, p-Smad3, Smad4 and MMP2, MMP9. The downregulation of SPARC also attenuated the cell migration and contractile phenotype of HPFs. SPARC could bind to TGF-βRII under TGF-β1 treatment. However, knockdown of SPARC did not affect the proliferation and apoptosis of HPFs.
Conclusion:
SPARC knockdown attenuated the fibrotic effect induced by TGF-β1 at least in part by inactivating the Smad2/3 pathways in HPFs. Therefore, SPARC may be a promising therapeutic target for the treatment of pterygium.
Insights
Secreted protein acidic and rich in cysteine (SPARC) inhibits fibrotic processes in human pterygium fibroblasts by inactivating Smad2/3 pathways. SPARC shows potential as a therapeutic target for treating pterygium.
Area of Science:
- Ophthalmology
- Cell Biology
- Biochemistry
Background:
- Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein involved in fibrotic disease regulation.
- Pterygium is a fibrotic condition affecting the eye.
Purpose of the Study:
- To investigate the anti-fibrotic effects of SPARC in primary human pterygium fibroblasts (HPFs).
- To elucidate the underlying mechanisms of SPARC's anti-fibrotic action.
Main Methods:
- SPARC knockdown in HPFs using RNA interference.
- Assessment of profibrotic markers (COL1, α-SMA, FN) and signaling pathways (Smad2/3) after TGF-β1 stimulation.
- Evaluation of cellular functions including migration, proliferation, apoptosis, and contractility.
Main Results:
- SPARC knockdown inhibited basal and TGF-β1-induced expression of fibrotic markers (COL1, α-SMA, FN) and MMPs (MMP2, MMP9).
- Downregulation of SPARC attenuated HPF migration and contractile phenotype.
- SPARC interacts with TGF-β receptor type II (TGF-βRII) under TGF-β1 treatment.
Conclusions:
- SPARC knockdown mitigates TGF-β1-induced fibrosis in HPFs, partly by inactivating Smad2/3 pathways.
- SPARC represents a potential therapeutic target for pterygium treatment.
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