Trichinella spiralis C-type lectin mediates larva invasion of gut mucosa via binding to syndecan-1 and damaging epithelial integrity in mice

C-type lectin (CTL) plays a vital role in parasite adhesion, invading host's cells and immune escape. The objective of this research was to explore whether recombinant T. spiralis CTL (rTsCTL) binding with syndecan-1 damages intestine epithelial integrity and mediates T. spiralis intrusion in mice. The results showed that rTsCTL interacted with syndecan-1 and activated STAT3 pathway in gut epithelium, decreased tight junctions (TJs) expressions and damaged gut epithelium integrity, promoted T. spiralis intrusion, and increased expression level of inflammatory cytokine and mucin. The syndecan-1 inhibitor (beta-xyloside) and STAT3 phosphorylation inhibitor (Stattic) significantly suppressed syndecan-1 expression and STAT3 pathway activation, reduced the expression levels of TJs, pro-inflammatory cytokines (TNF-alpha and IL-1 beta), Muc2 and Muc5ac, and declined intestinal permeability in T. spiralis-infected mice. These results revealed that the inhibitors suppressed T. spiralis invasion and development in gut mucosa, decreased intestinal adult burdens and relieved gut inflammation. These findings further testified that the in vivo binding of TsCTL with syndecan-1 destroyed enteral mucosal epithelial integrity and promoted T. spiralis intrusion of gut mucosa via activating STAT3 pathway and decreasing TJs expression. TsCTL could be deemed as a promising vaccine target to interrupt T. spiralis infection.