Formulation of Huangqin Decoction Influence Immune Function and Fecal Microbiome of Chicks Suffered Escherichia Coli O78 Challenge

Abstract

Ethnopharmacological relevance: Huangqin Decoction (HQD), a traditional Chinese medicine formula from the Shang Han Lun written by Zhang Zhongjing, has been used in China for nearly two thousand years. According to traditional Chinese medicine and a previous literature, HQD has the effect of clearing heat and removing toxin, antidiarrhea, and relieving pain. Therefore, HQD were used to prevent or cure many diseases, such as inflammation, diarrhea, malaria, and other acute or chronic gastrointestinal diseases. Materials and methods: HQD consist of four components: Scutellariae Radix (huangqin, HQ), Paeoniae Radix Alba (shaoyao, SY), Jujubae Fructus (dazao, DZ), Licorice (gancao, GC). A total of 80 1-day-old male Esa brown chicks were divided into eight groups (n=10): Control group (CG), model group (MG), Enrofloxacin group (ENR, 10 mg/kg·BW), HQD group (HQD, 500 mg/kg·BW), HQD-GC group (GC absent HQD, 500 mg/kg·BW), HQD-HQ group (HQ absent HQD, 500 mg/kg·BW), HQD-DZ group (DZ absent HQD, 500 mg/kg·BW) and HQD-SY group (SY absent HQD, 500 mg/kg·BW). The chicks, which were given HQD, herb absent HQD, or enrofloxacin orally at 19 days of age for 7 days, and then were intraperitoneally injected with inoculum of E. coli O78，fed continuously for 5 days as before. Results: It showed that E. coli O78 challenge decreased the average daily gain (ADG) and increased the mortality rate of chicks, increased the heart index and the liver index, decreased the bursal index, and had no effect on the spleen index. E. coli O78 challenge increased the serum lysozyme (LZM) and IL-1β, TNF-α, IL-10, IL-6, up-regulated the mRNA expression of TLR4, TLR5 and TLR15 in the spleen, and had no effect on the bursal compared with CG. E. coli O78 challenge increased the Operational Taxonomic Unit (OTU), increased the relative abundance of harmful bacteria Proteobacteria, and decreased the relative abundance of probiotics Bacteroidetes and Firmicutes at the phylum levels. E. coli O78 challenge increased the relative abundance of harmful bacteria Escherichia-Shigella and Pseudomonas at the genus levels. HQD supplementation showed higher ADG and reduced the mortality rate caused by E. coli O78 challenge, decreased the heart index and liver index, and increased the bursal index and spleen index. HQD supplementation decreased the serum LZM, IL-1β, TNF-α, IL-10, IL-6 levels, down-regulated the mRNA expression of TLR4, TLR5 and TLR15 in the spleen in E. coli O78 challenged chicks, and up-regulated the mRNA expression of TLR4, TLR5 and TLR15 in the bursal in that. At the phylum levels, HQD supplementation reversed the increased of OTUs, decreased the relative abundance of harmful bacteria Proteobacteria, increased the relative abundance of probiotics Bacteroidetes and Firmicutes. At the genus levels, HQD decreased the relative abundance of harmful bacteria Escherichia-Shigella and Pseudomonas. It means that HQD reversed the change of the gut microbiota structure. Compared with HQD, HQD-DZ and HQD-HQ increased the mortality rate. HQD-HQ decreased the ADG and liver index. HQD-GC decreased the spleen index. HQD-DZ, HQD-HQ, HQD-SY and HQD-GC increased the serum TL-6, but only the HQD-HQ and HQD-SY increased the serum TNF-α. All herb absent HQD did not activate the toll-like receptors signaling pathways in spleen and bursal of chicks. HQD-DZ and HQD-HQ increased the harmful bacteria Escherichia-Shigella, and HQD-DZ increased the harmful bacteria Proteobacteria levels. Conclusions: Dietary supplementation with HQD, by down-regulating the mRNA expression of TLR4, TLR5 and TLR15 in the spleen, further decreasing the serum LZM and IL-1β, TNF-α, IL-10, IL-6 levels, improves the immune function and reverse the change of fecal microbiome in chicks challenged with E. coli O78. About herb absent groups, the results shown that SY and DZ play a key role in reducing the level of inflammatory factors and keeping fecal microbiome balance respectively. what’s more, we highlighted that HQ is indispensable in HQD, HQ not only play a key role in reducing the level of inflammatory factors, but also keep the balance of fecal microflora.