Effect Of APS On TLR4 Signaling Pathway In Immune Organs Of Chickens

In order to explore the effect of Astragalus Polysaccharides on TLR4 signaling pathway in the immune organs of chickens, we extract the rough polysaccharide from astragalus by the method of extracting of water. Then extract the elaborate polysaccharide from the rough polysaccharide by Sevag method. The content of astragalus polysaccharide is 84.7%, determined through the phenol-sulfuric acid method with glucose as standard. Then, 140 of 7-day-age chickens were randomly divided into four groups in the experiment. Group I, II, III were respectively given APS one time daily with a volume of 0.2 m L at a dosage of 80, 40 and 20 mg·m L-1(p.o.) for 5 days, and group C were given physiological saline in the same way. At 14-day-age, the chickens were vaccinated with infectious bursal disease moderate virelence live vaccine. On the 1st, 3rd, 5th and 7th days after the first treatment and 7th, 14 th, 21 st after inoculation, 5 chickens were selected randomly from each group and the thymus, spleen and bursa of fabricius were collected, and the ch TLR4 m RNA and ch TLR4 protein expression of the immune organs were detected by RT-PCR and immunohistochemistry. And we also determinated the signaling molecule of TLR4 signaling pathway(ch My D88, ch TRIF, ch NF-κB, ch IRF3, ch IFN-β, and ch TNF-α m RNA) by RT-PCR. The results displayed that in all time the expression of ch TLR4 m RNA in experimental groups are higher than or weigh against those in control group. On 8 days the expression of ch TLR4 m RNA in thymus in high group were significantly higher than those in control group(p<0.05), then shown wave change, and at last, it weigh against those in control group. Three weeks later, the expression of ch TLR4 m RNA in high groups are higher than those in control group once again, and the expression also improved in the low group, but it later than the high and middle groups correspondingly. In spleen,the expression of ch TLR4 m RNA in high group and middle group were developed significantly in all of time. The expression of ch TLR4 m RNA in experimental groups were higher than those in control group(p<0.01 or p<0.05). And the expression of ch TLR4 m RNA in low group were higher than those in high and middle groups. The ch TLR4 protein variation trend was consistent with the ch TLR4 m RNA in all organs. The expression of ch My D88, ch TRIF, NF-κB and ch IRF3 m RNA also were developed with the development of ch TLR4 m RNA in all organs tested. The expression of ch IFN-β and ch TNF-α m RNA were different from those in control group(p<0.01 or p<0.05). Before the immunization, the indexes of ch IFN-β and ch TNF-α m RNA in experimental groups were higher than or weigh against those in control group. However, after the immunization the indexes in experimental groups were higher than those in control group significantly. In all time the changes shown wave change.This study demonstrated that APS can activate ch TLR4 signaling pathways including My D88-depending signaling pathway and My D88-independing signaling pathway in chickens immune organ, and improve immunity. So that we can clarify the molecular mechanism of APS regulating immune function from the point of pattern recognition and signaling transduction in vivo, which can provide evidence for using APS to improve disease-resistant ability clinically.