Unravelling the interplay of sphingolipids and TGF-? signaling in the human corneal stroma.

ABSTRACT:

Purpose

To delineate the role of Sphingolipids (SPLs) in the human cornea and their cross-talks with transforming growth factor beta (TGF-?) in order to develop novel, non-invasive therapies.

Methods

Human corneal fibroblasts (HCFs) were harvested from healthy donors, stimulated with Vitamin C to promote extracellular matrix assembly, treated with exogenous sphingosine-1-phosphate (S1P) or sphingosine kinase inhibitor 2 (SPHK I2) and isolated after 4 weeks for further analysis.

Results

Data showed that S1P led to a significant decrease in cellular migration where SPHK I2 just delayed it for 24h. Significant modulation of the sphingolipid pathway was also noted. Sphingosine kinase-1 (SphK1) was significantly downregulated upon exogenous stimulation with S1P at a concentration of 5?M and Sphingosine kinase-2 (SphK2) was also significantly downregulated at concentrations of 0.01?M, 0.1?M, and 5?M; whereas no effects were observed upon stimulation with SPHK I2. S1PR3 was significantly downregulated by 0.1?M and 5?M S1P and upregulated by 5?M and 10?M SPHK I2. Furthermore, both S1P and SPHK I2 regulated corneal fibrosis markers such as alpha-smooth muscle actin, collagen I, III, and V. We also investigated the interplay between two TGF-? isoforms and S1P/SPHK I2 treatments and found that TGF-?1 and TGF-?3 were both significantly upregulated with the 0.1?M S1P but were significantly downregulated with the 5?M S1P concentration. When TGF-?1 was compared directly to TGF-?3 expression, we observed that TGF-?3 was significantly downregulated compared to TGF-?1 in the 5?M concentration of S1P. No changes were observed upon SPHK I2 treatment.

Conclusion

Our study delineates the role of sphingolipids in the human cornea and highlights their different activities based on the cell/tissue type.

SUBMITTER: Nicholas SE 

PROVIDER: S-EPMC5555661 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature