Trichinella spiralis Serine Proteinase Disrupted Intestinal Epithelial Integrity via Binding to RACK1 and Activating ERK1/2 Pathway in Mice.

Previous studies showed that a T. spiralis serine proteinase (TsSPc) was identified in intestinal infective larvae (IIL) surface and excretory-secretory (ES) proteins. The in vitro experiments revealed that rTsSPc bound to intestinal epithelial cells and promoted larval invasion, but the in vivo role of rTsSPc in T. spiralis infection remains unclear. The purpose of this study was to investigate the TsSPc's function and mechanism in T. spiralis infection in mice. Immunofluorescence assay (IFA), qPCR, and Western blotting showed that rTsSPc specifically bound and co-localized with RACK1 receptor in intestinal mucosal epithelium, activated the ERK1/2 pathway, decreased the expression of the tight junctions (E-cad, Occludin, and Claudin-1), increased intestinal permeability, impaired intestinal epithelial integrity and barrier function, thereby promoted T. spiralis invasion of intestinal mucosa. The H&E and PAS staining showed that rTsSPc also caused intestinal mucosal inflammation reactions; the number and size of goblet cells in the rTsSPc group were distinctly increased, and the expression levels of inflammatory cytokines (TNF-α, IL-1β, TGF-β, and IL-10) and mucins (Muc2 and Muc5ac) were significantly elevated. These findings further verified that the in vivo binding of TsSPc to RACK1 disrupted gut epithelial integrity and mediated T. spiralis invasion of intestinal mucosa, and TsSPc may be regarded as a potential vaccine target to block T. spiralis infection.