ChTLR4 pathway activation by Astragalus polysaccharide in bursa of Fabricius

Ruili Zhang,Ming Ge,Rui Liu,Guangliang Shi,Qun Yu,Weiqian Zhang,Guangxing Li,Xia Zhao

doi:10.1186/s12917-017-1039-y

Ruili Zhang, Ming Ge + Show 6 more

Open Access

https://doi.org/10.1186/s12917-017-1039-y

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Abstract

BackgroundThe Toll-like receptor 4 (TLR4) pathway involves in the pathogen recognition and defense against infection in mammals. Considering that avian and mammalian TLR are differentially mediated, the action of a natural product on avian TLR4 pathway was unclear. High, medium and low doses of Astragalus polysaccharide (APS), were treated the chicken at 7-days-old age by gavage. The sIgA level in the intestinal fluid, the expression of chTLR4 mRNA/protein in bursa of Fabricius as well as the expression of downstream molecules of chTLR4 (chMyD88, chTRIF, chNF-κB, chIRF3, chIFN-β and chTNF-α) were measured on alternate days.ResultsThe content of sIgA and the chTLR4 mRNA expression/protein level were increased in non-dose-dependent manner after APS supplement. Also, the expressions of a subset of MyD88-independent pathway genes were more than MyD88-independent, in particular with low doses of APS supplement for 7 days.ConclusionsThese suggest that administration of APS activates chTLR4 pathway in bursa of Fabricius in MyD88-independent pathway. Meanwhile, low dose of APS shows better performance regarding the activation of chTLR4 and regulation of MyD88-independent pathway.

Highlights

The Toll-like receptor 4 (TLR4) pathway involves in the pathogen recognition and defense against infection in mammals
Toll-like receptor family (TLRs) as important components of innate immune response can bind to specific antigen, activate a signal transduction pathway and accelerate the release of inflammatory cytokines in early pathogen recognition, which favors the initiation of specific adaptive immune response [2, 5]
Recent scientific investigations conducted in the models of porcine reproductive and respiratory syndrome virus and H9N2 avian influenza virus have reported Astragalus polysaccharide (APS) could exert immunoprotecting effect [4, 6]

Summary

Introduction

The Toll-like receptor 4 (TLR4) pathway involves in the pathogen recognition and defense against infection in mammals. Toll-like receptor family (TLRs) as important components of innate immune response can bind to specific antigen, activate a signal transduction pathway and accelerate the release of inflammatory cytokines in early pathogen recognition, which favors the initiation of specific adaptive immune response [2, 5]. Recent scientific investigations conducted in the models of porcine reproductive and respiratory syndrome virus and H9N2 avian influenza virus have reported APS could exert immunoprotecting effect [4, 6]. These are confined to inflammatory cytokines instead of pathway.

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