Figure 1. Suppression of TNF-α-induced IL-6 and ccl2 mRNAand protein by OTC. ARPE-19 cells were exposed to tumor necrosis factor-α (TNF-α;
10 ng/ml; 24 h incubation) in the presence or absence of L-2-oxothiazolidine-4-carboxylic acid (OTC; 0.5 mM) and nicotinic
acid (NA; 1 mM; positive control). Quantitative polymerase chain reaction (qPCR) analysis of (A) interleukin-6 (IL-6) and (B) chemokine (C-C) motif ligand 2 (Ccl2) mRNA expression. The cell culture medium was then collected and used for enzyme-linked
immunosorbent assay (ELISA) analysis of the (C) IL-6 and (D) Ccl2 proteins. *p<0.01 compared to control cells; ** p<0.01 compared to TNF-α-treated cells.