Identification of a host collagen inducing factor from the excretory secretory proteins of Trichinella spiralis using immunoscreening

Abstract

BackgroundIn a previous study, we found that Trichinella spiralis excretory and secretory proteins (ES-P) most likely activate collagen synthesis via TGF-{beta}/Smad signaling, and this event could influence collagen capsule formation.\n\nMethodology/Principal FindingsIn order to identify the specific collagen inducing factor, ES-P was fractionated by a Superdex 200 10/300 GL column. We obtained three large fractions, F1, F2, and F3, but only F3 had collagen gene inducing ability. After immunoscreening, 10 collagen inducing factor candidates were identified. Among them, TS 15-1 and TS 15-2 were identical to the putative trypsin of T. spiralis. The deduced TS 15-1 (M.W. = 72 kDa) had two conserved catalytic motifs, an N-terminal Tryp_SPc domain (TS 15- 1n) and a C-terminal Tryp_SPc domain (TS 15-1c). To determine their collagen inducing ability, recombinant proteins (rTS 15-1n and rTS 15-1c) were produced using the pET-28a expression system. TS 15-1 is highly expressed during the muscle larval stage and has strong antigenicity. We determined that rTS 15-1c could elevate collagen I via activation of the TGF-{beta}1 signaling pathway in vitro and in vivo.\n\nConclusion/SignificanceIn conclusion, we identified a host collagen inducing factor from T. spiralis ES-P using immunoscreening and demonstrated its molecular characteristics and functions.\n\nAuthor SummaryTrichinella spiralis can make collagen capsules in host muscle cells during its life cycle, which encapsulates muscle stage larvae. Many investigators have tried to reveal the complex mechanism behind this collagen capsule architecture, and it has been suggested that several serine proteases in excretory-secretory proteins of the parasite are potential collagen capsule inducing factors. In addition, collagen synthesis is activated through the TGF-{beta}/Smad signaling pathway and these events are closely related with protease activated receptor 2 which was activated by various serine proteases. In this study, we isolated and characterized a collagen gene expression inducer from T. spiralis ES-P using immunoscreening and investigated the candidate protein for its usefulness as a wound healing therapeutic agent.