Abstract
BACKGROUND: The excretory-secretory (ES) antigen of Trichinella spiralis (T. spiralis) has garnered significant attention owing to its notable immunomodulatory activities, particularly its ability to regulate the maturation of dendritic cells (DCs). To elucidate the role of key ES components, this study employed the recombinant antigen p53 of T. spiralis (rTs p53) to evaluate the specific regulatory effects of this protein on DCs maturation and immune function. METHODS: To dissect the immunomodulatory effect of rTs p53 on DCs, we determined its activity on DCs and its impact on indoleamine 2,3-dioxygenase (IDO) expression. Moreover, we quantitatively detected the mRNA levels and secretion levels of interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-α). The concentration of tryptophan in the cell supernatant was measured. In addition, we analyzed the expression levels of the DC surface molecules MHC-II, CD80, and CD86 on DCs and observed the morphology of the DCs. RESULTS: Compared with the blank group, the ES antigen group and the rTs p53 group presented significantly increased IDO expression, a marked decrease in tryptophan concentration, and significantly upregulated mRNA transcription levels and secretion levels of IL-10, IL-6, and TNF-α. Morphologically, the DCs in the ES antigen group and the rTs p53 group exhibited more surface wrinkles but fewer spiny protrusions compared with those in the lipopolysaccharide (LPS) group, suggesting that both antigens can inhibit the maturation of DCs. In terms of surface molecules, the LPS group presented higher levels of MHC-II, CD80, and CD86 than the blank group. In the rTs p53 group, MHC-II expression was comparable to that in the blank group, and the levels of CD80 and CD86 were increased. However, the extent of this increase was significantly weaker than that in the LPS group, indicating that the rTs p53 inhibits the complete maturation of DCs. CONCLUSIONS: The findings of this study contribute to elucidating the pathogenic mechanism of T. spiralis, increase our understanding of its immune response, and provide a basis for exploring the underlying immune regulatory mechanisms involved.