The inhibitory function of recombinant thioredoxin peroxidase of Clonorchis sinensis on Fas-mediated apoptosis in Jurkat T cells

Abstract

Clonorchis sinensis is a carcinogenic liver fluke distributed in East Asia including Korea, China, Vietnam, and parts of Russia. Adult worm of C. sinensis can dwell in bile duct for over 10 years and its chronic infection promotes persistent oxidative stress such as reactive oxygen species (ROS). To ensure parasites long-term survival, anti-oxidant mechanism is important and thioredoxin peroxidase (TPX) is one of the redox enzymes used by parasites. Main function of TPX is neutralizing H2O2 and it also has additional biological functions including cell proliferation, intracellular signaling, iron metabolism, immune regulation, and apoptosis. Here, soluble recombinant TPX protein of C. sinensis (rCsTPX) was produced in Eschericia coli system and investigated its modulation of apoptosis. When rCsTPX was expressed, at first, most of the expressed protein was insoluble form because of low solubility of rCsTPX. To improve its solubility, the expression conditions such as isopropyl β-D-1-thiogalactopyranoside (IPTG) concentration, temperature, or duration of induction was changed. Eventually the proper expression condition that can get soluble form of rCsTPX was set at 20℃ for overnight with 100 μM IPTG. With this soluble rCsTPX, its effect of apoptosis was observed in macrophage cell line and T cell line. Only in T cells which is induced apoptosis with anti-Fas antibody, rCsTPX has shown regulatory effect. Caspase cascade was also confirmed by western blot analysis, and rCsTPX had influence on caspase-3 and -9 activation, but not caspase-8. In conclusion, these results suggest the better method of producing soluble rCsTPX and further imply that rCsTPX has modulatory function of Fas-mediated apoptosis in T cells as a potential candidate for therapeutic application.