Functional role of Thioredoxin peroxidase from Clonorchis sinensis in host immune reactions (112.3)

Abstract

Abstract Clonorchis sinensis (C. sinensis), one of liver flukes, can cause chronic infection while they reside in the bile duct and leads to cholangiocarcinoma in humans. We investigated interaction between live C. sinensis worm and murine macrophage cell line, RAW264.7, using a non contact co-culture transwell plate. The results shown that the worms are able to activate RAW cells to express surface TLR4 and to promote IL-10 and TGF-β secretion. There are minor differences between direct and indirect exposure of the worms. As we hypothesized that anti-oxidant enzyme produced by C. sinensis might stimulate host immune reactions, we cloned antioxidant enzyme, Thioredoxin peroxidase (TPX, 2-Cys peroxidase), and the recombinant protein (rTPX) has been produced by using the bacterial system. Mouse macrophage cells, RAW264.7 cells, were treated with rTPX and checked the level of cell surface markers. We found that expression of TLR4 and CD40 molecules were augmented at 3 and 6 hours time points, respectively. Surface expression of TLR4 was prolonged up to 48 hrs, while CD40 was temporarily expressed. ELISA results showed that IL-4 level was slightly down-regulated by TPX treatment, however, IL-10 secretion was increased and even doubled when IL-4 and TPX were treated together. Although, more than one molecule could be involved in antigenicity of C. sinensis, we report here that the TPX from C. sinensis is a candidate that acts as “infection alarm” to awake the host innate immune cells.