Effects of Astragalus polysaccharides on intestinal morphology and intestinal immune cells of Muscovy ducklings infected with Muscovy duck reovirus

Abstract

Muscovy duck reovirus ( MDRV ) infection induces serious immunosuppression and intestinal injury in Muscovy ducklings with a high morbidity and mortality, and Astragalus polysaccharide ( APS ) pretreatment could efficiently protect ducklings from MDRV infection, although the underlying immunoregulatory mechanisms remain unclear. Thus, the objective of this study was to investigate effects of APS on the intestinal mucosal immunity in MDRV-infected Muscovy ducklings. A total of 190 1-day-old healthy Muscovy ducklings were randomly assigned to 3 groups (n = 50): normal control group, APS pretreatment for MDRV-infected group, and cohabitation infection group, then pretreated with 0.6 g/L APS or only drinking water followed by MDRV cohabitation infection with the remaining 40 artificially infected ducklings, respectively. At the 2, 3, 4, 6, 9 and 15 d after cohabitation infection, the intestinal samples were prepared to measure intestinal parameters including villus length, villus length/crypt depth ( V/C ) ratio, and wall thickness, together with counts of intraepithelial lymphocyte ( IEL ) and goblet cell ( GC ) by hematoxylin–eosin staining. Meanwhile, ileal secretory IgA ( sIgA ) and duodenal cytokine levels of IL-4, IL-6, IL-15, tumor necrosis factor-alpha, and interferon gamma were detected by the ELISA and radioimmunoassay, respectively. The results showed that APS significantly improved intestinal injuries of villi length, V/C ratio, and wall thickness of the small intestine infected with MDRV, effectively inhibited the reduction of IEL and GC caused by MDRV infection, subsequently increased sIgA and all the cytokine secretions at most time points, suggesting that APS pretreatment can effectively stimulate mucosal immune function by improving intestinal morphology and repair MDRV caused injures of small intestinal mucosal immune barrier in infected ducklings. Our findings lay the foundation for further application of APS in prevention and treatment of MDRV infection.

Potential Application of Dandelion (Taraxacum Mongolicum Hand.-Mazz.) on Broiler Chickens: Growth Performance, Expression of Tight Junction Protein and Mucin Genes, and Microbiota Composition in Ileum

“…In addition, the equilibrium among proand anti-in ammatory cytokines is necessary for gut immunological homeostasis [22]. However, in contrast to previous studies, we observed no effects of dandelion on in ammatory cytokines and SIgA in the current study [40,41], indicating that dandelion failed to induce any notable effects in the immunological barrier.…”

Polysaccharides derived from Astragalus membranaceus and Glycyrrhiza uralensis improve growth performance of broilers by enhancing intestinal health and modulating gut microbiota

“…These results were in agreement with those of Wang et al (2021) who showed that dietary APS increased VH of 3 small intestine segments and VH/CD ratio of the jejunum and ileum. Liao et al (2021) revealed that APS supplementation could maintain intestinal integrity of Muscovy ducklings infected with Muscovy duck reovirus by increasing VH, VH/CD ratio and wall thickness of the small intestine. The study on weaned piglets also showed that dietary APS could improve jejunal VH and V/C ratio ( Yang et al, 2019a ).…”

“…It has been well-known that plant polysaccharides possess immunomodulatory properties ( Long et al, 2020 ; Zhao et al, 2020 ; Liu et al, 2021a ). Liao et al (2021) reported that oral administration of APS could promote the production of secretory IgA in ileal mucosa of Muscovy ducklings infected with Muscovy duck reovirus. Wu et al (2022) verified GPS as an immune booster capable of enhancing the antibody potency of the Newcastle disease vaccine in chickens.…”

“…Dietary supplementation with APS has been found to improve the body weight gain of juvenile broilers, potentially due to enhanced digestive enzyme activity and antioxidant capacity ( Wu, 2018 ). Moreover, APS intake by drinking water could effectively stimulate mucosal immune function and improve intestinal morphology of Muscovy ducklings infected with Muscovy duck reovirus ( Liao et al, 2021 ). Glycyrrhiza polysaccharides ( GPS ) is one of the major active components of Glycyrrhiza uralensis , and its biological activity is closely connected with the spatial structure of alpha-D-pyran polysaccharide ( Shen et al, 2015 ).…”

Evaluation of serum antioxidative status, immune status and intestinal condition of Linwu duck challenged by lipopolysaccharide with various dosages and replications

“…10 sections of the proper microscopic fields were chosen from each sample for the analysis of villus height ( VH ), crypt depth ( CD ), wall thickness ( WT ), and mucosa thickness ( MT ) under an image analysis system (Image-Pro, Media Cybernetics, Inc., Silver Springs, MD, USA). Briefly speaking, villus length was measured from the villous tip to the villous crypt junction; crypt depth was determined from the opening to basing of crypt; wall thickness was measured from the outer of the intestine to the submucosa and muscular layer junction, including the serosa layer and the muscular layer ( Liao et al., 2020 ). The ratio of VH and CD ( VCR ) was calculated.…”