TNFAIP3 is anti-inflammatory in the retinal vasculature

PURPOSE: To determine whether tumor necrosis factor alpha-induced protein 3 (TNFAIP3) regulates inflammatory and permeability proteins in the retinal vasculature. METHODS: We used retinal lysates from type 1 diabetic mice and endothelial cell-specific exchange protein for cAMP 1 (Epac1) knockout mice to determine the protein levels of TNFAIP3. We also treated retinal endothelial cells (RECs) in normal (5 mM) and high (25 mM) glucose with an Epac1 agonist or with TNFAIP3 siRNA. We performed western blotting for TNFAIP3 and inflammatory and permeability proteins after treatment. TNFAIP3 siRNA was used only in cells grown in high glucose. Immunostaining was performed for localization of ZO-1 and tight junction protein 1. RESULTS: TNFAIP3 was reduced in the diabetic retinas and the retinas of the Epac1 conditional knockout mice. The Epac1 agonist increased TNFAIP3 levels in RECs grown in high glucose. Reduction of TNFAIP3 with siRNA led to increased levels of tumor necrosis factor alpha (TNFα) and phosphorylation of nuclear factor kappa beta (NF-kB), while decreasing occludin and zonula occludens 1 (ZO-1) protein levels and inhibitory kappa beta kinase (IkB) phosphorylation. Tumor receptor-associated factor 6 (TRAF6) levels were increased above high glucose levels. CONCLUSIONS: TNFAIP3 serves as an anti-inflammatory factor in the retinal vasculature. Epac1 regulates TNFAIP3. TNFAIP3 may offer a new mechanism for regulating inflammation and permeability in the retinal vasculature.