The small tellurium-based compound SAS suppresses inflammation in human retinal pigment epithelium

Purpose: Pathological angiogenesis and chronic inflammation greatly contribute to the development of choroidal neovascularization (CNV) in chorioretinal diseases involving abnormal contact between retinal pigment epithelial (RPE) and endothelial cells (ECs), associated with Bruch's membrane rupture. We explored the ability of the small organotellurium compound octa-O-bis-(R,R)-tartarate ditellurane (SAS) to mitigate inflammatory processes in human RPE cells. Methods: Cell adhesion assays and analyses of gene and protein expression were used to examine the effect of SAS on ARPE-19 cells or primary human RPE cells that were grown alone or in an RPE-EC co-culture. Results: Adhesion assays showed that SAS inhibited av integrins expressed on RPE cells. Co-cultures of RPE cells with ECs significantly reduced the gene expression of PEDF, as compared to RPE cells cultured alone. Both SAS and the anti-alpha v beta 3 antibody LM609 significantly enhanced the production of PEDF at both mRNA and protein levels in RPE cells. RPE cells co-cultured with EC exhibited increased gene expression of CXCL5, COX1, MMP2, IGF1, and IL8, all of which are involved in both angiogenesis and inflammation. The enhanced expression of these genes was greatly suppressed by SAS, but interestingly, remained unaffected by LM609. Zymography assay showed that SAS reduced the level of MMP-2 activity in RPE cells. We also found that SAS significantly suppressed IL-1 beta-induced IL-6 expression and secretion from RPE cells by reducing the protein levels of phospho-IkappaBalpha (pI kappa B alpha). Conclusions: Our results suggest that SAS is a promising anti-inflammatory agent in RPE cells, and may be an effective therapeutic approach for controlling chorioretinal diseases.