Objective: To investigate the effect of advanced oxidation protein products (AOPP) on the secretion of tumor necrosis factor alpha eTNFalphae in monocytes and its possible mechanism.
Method: Human monocyte cell line THP-1 and peripheral blood monocytes were incubated with AOPP-bovine serum albumin(BSA) prepared by incubation of BSA with hypochlorous acid. TNFalpha in the supernatant of the culture medium of THP-1 cells was measured by enzyme-linked immunosorbent assay and the production of reactive oxygen species (ROS) evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2,7-dichlorefluorescin using Wallac 1420 multilabel counter. The intracellular signal was observed by pre-treatment of the cells with antioxidant pyrrolidine dithiocarbamate, NADPH oxidase inhibitor apocynin or p38 phosphorylation inhibitor SB203580.
Results: AOPP-BSA induced TNF-alpha secretion and ROS production in monocytes. Pretreatment of the cells with pyrrolidine dithiocarbamate scavenged most of ROS and almost completely blocked TNF-alpha secretion induced by AOPP-BSA. Inhibition of NADPH oxidase by apocynin and p38 phosphorylation by SB203580 could both effectively block AOPP-BSA-induced TNF-alpha secretion.
Conclusion: AOPP-BSA induced TNF-alpha secretion in monocytes, and the intracellular signaling involves ROS produced by activated NADPH oxidase and subsequent p38 phosphorylation.