Immunological study of recombinant protein fragments from Clonorchis sinensis thioredoxin peroxidase on inhibitory effect of macrophage activation (MPF6P.656)

Abstract

Abstract Clonorchis sinensis (C. sinensis) estabilishes long term parasitism within bile ducts without notable symptoms. General down-modulated host immune responses in helminth infestation are maintained by excretory-secretory products (ESP), produced by the live parasites and considered as an important immunomodulator in this context. Reference based study found out that Thioredoxin peroxidase (TPX) of helminth parasites had an immune-modulating property toward Th2 type through induction of regulatory phenotype of macrophages. Hence, full length of TPX and a number of recombinant TPX fragments of C. sinensis were produced by using bacteria system. The CS-TPX was able to inhibit LPS-induced surface expression of TLR4 in mouse macrophage cell line, RAW264.7, and LPS-induced secretion of pro-inflammatory mediators NO, TNF-α and IL-6. Moreover, CS-TPX induces IL-10, but not TGF-β. Pull-down assay results revealed that the direct interaction between CS-TPX and TLR4 protein. Furthermore, we found that the smallest recombinant fragment of CS-TPX, which is T44, has comparable anti-inflammatory property as compared with full length CS-TPX. In conclusion, present study describes the macrophage regulatory function of C. sinensis ESP and the smallest fragment of CS-TPX, T44, could function of the negative regulator in LPS treated macrophage cell line RAW264.7 cells. Defined CS-TPX T44 will be one of the best candidates for therapeutic immunosuppressant in allergies and autoimmune diseases.