Effects of Glycyrrhiza Polysaccharides on Chickens' Intestinal Health and Homeostasis

Abstract

The overuse of antibiotics in poultry farming causes the accumulation of drug residue in animals' bodies and the occurrence of antibiotic-resistant bacteria, which not only compromise animals' health but ultimately endanger human health. Thus, there is an urgent need for a novel poultry feed additive to substitute for excessive antibiotics. Glycyrrhiza polysaccharides (GPS) derived from Chinese licorice have shown promising immunomodulatory effects in previous studies. The present study investigated the pharmacological effects of GPS on poultry intestines to assess whether it can be used as a feed additive. The results show that GPS can increase production of sIgA, promote the secretion activity of goblet cells, alter the gut microbial composition and lead to changes in short-chain fatty acids. GPS also elevated both Th1 and Th2 immune responses by facilitating the expression of IL-2, IL-4, IL-1β, and IFN-γ while increasing the proportion of both CD4+ and CD8+ cells in the intestine. Moreover, the results of 16S rRNA gene sequencing showed that GPS could significantly change intestinal microbiota composition in the intestine, evidenced by the increased proportion of Bacteroides, Butyricicoccus and Eisenbergiella, as well as a decreased portion of Erysipelatoclostridium, leading to a healthier intestinal microbiota composition for the host. Taken together, it can be concluded that GPS is safe to use as a novel feed additive that can be used as an alternative to prophylactic antibiotics in poultry feeding.

Structure of a new glycyrrhiza polysaccharide and its immunomodulatory activity

“…Researchers have also demonstrated a positive correlation between the immune activity of polysaccharides and their uronic acid content (9). Our previous study also confirmed that glycyrrhiza polysaccharides can prolong the efficacy and duration of the Newcastle disease virus (NDV) vaccine (10) and improve the intestinal immune function and microbial composition of roosters (4). In addition, the glycyrrhiza polysaccharide (GiP-B1) can cause significant phenotypic changes in dendritic cells (DCs) and the improvement of bioactive functions with a mechanism of action related to the TLRs/NF-B signaling pathway (11).…”

“…It is reported that some scholars have pointed out that the intake of pectin polysaccharide can be a therapeutic strategy for managing intestinal inflammation. Among them, anti-inflammatory cytokines and intestinal barrier function tend to be regulated by galactan-rich pectic polysaccharides ( 4 ). Since GPS-1 is a pectin polysaccharide rich in galacturonic acid, it has a positive effect on improving intestinal immunity, which is consistent with the previous study in our laboratory that GPS-1 can improve the intestinal immunity of laying hens.…”

“…Since GPS-1 is a pectin polysaccharide rich in galacturonic acid, it has a positive effect on improving intestinal immunity, which is consistent with the previous study in our laboratory that GPS-1 can improve the intestinal immunity of laying hens. In laying hens, the addition of glycyrrhiza polysaccharide in the feed can regulate the abundance of intestinal flora and promote the increase of beneficial bacteria ( 4 ). It also suggested the effect of this type of polysaccharide on the intestinal barrier and immune function.…”

“…After spleens were collected on day 14 (n = 5 per group), primary spleen lymphocytes were extracted according to literature reports ( 4 , 10 ). The stained cells were incubated with lipopolysaccharides (LPS, from Sigma) and CD3-FITC, CD4-PC, and CD8-APC (eBioscience™, AB_2536505) for 24 h, then measured using a flow cytometer (BD Biosciences AccuriC6, USA).…”

“…Licorice’s medicinal benefits are now recorded in the pharmacopeias of China, South Korea, and Japan ( 3 ). Studies of active ingredients in licorice have found that polysaccharides are important components ( 4 , 5 ) and that one of the main functions of licorice polysaccharides is to improve immunity ( 4 , 6 , 7 ). Another investigation found that licorice polysaccharides could dose-dependently counteract cyclophosphamide-induced immunosuppression in mice ( 8 ).…”