Mannan Oligosaccharides Application: Multipath Restriction From Aeromonas hydrophila Infection in the Skin Barrier of Grass Carp (Ctenopharyngodon idella)

Abstract

The objective of this study was to evaluate the efficacy of dietary Mannan oligosaccharides (MOS) supplementation on skin barrier function and the mechanism of on-growing grass carp (Ctenopharyngodon idella). Five hundred forty grass carp were fed for 60 days from the growing stage with six different levels of MOS diets (0, 200, 400, 600, 800, and 1,000 mg kg-1). At the end of the growth trial, the 14-day Aeromonas hydrophila challenge experiment has proceeded. The obtained data indicate that MOS could (1) decline skin lesion morbidity after being challenged by the pathogenic bacteria; (2) maintain physical barrier function via improving antioxidant ability, inhibiting excessive apoptosis, and strengthening the tight junction between the epithelial cell and the related signaling pathway (Nrf2/Keap1, p38MAPK, and MLCK); and (3) regulate immune barrier function by modulating the production of antimicrobial compound and expression of involved cytokines and the related signaling pathway (TOR and NFκB). Finally, we concluded that MOS supplementation reinforced the disease resistance and protected the fish skin barrier function from Aeromonas hydrophila infection.

Dietary Mannan Oligosaccharides Enhance the Non-Specific Immunity, Intestinal Health, and Resistance Capacity of Juvenile Blunt Snout Bream (Megalobrama amblycephala) Against Aeromonas hydrophila

“…GST is a key enzyme catalyzing the initial step in the glutathione binding reaction, and its activity was also inhibited postinfection, whereas dietary MOS could maintain its activity in the present study. Similar results have been reported in grass carp ( 38 ). In summary, dietary MOS enhanced the antioxidant ability of juvenile M. amblycephala by inducing or maintaining the activities of SOD, CAT, and GST, which could assist in increasing the survival rate of M. amblycephala upon infection.…”

“…LZM can dissolve glycoproteins on the surface of bacteria, and ACP is an enzyme marker for lysosomes with bactericidal effects. Thus, the upregulated activities of ACP and LZM reflected increased host bactericidal effects, which have also been previously observed ( 7 , 35 , 37 , 38 ). The activity of AKP was positively correlated with A. hydrophila infection levels, and the resistance level of the host to the pathogen was reflected by the significantly lower AKP activity in the immune-stimulated groups ( 39 ).…”

“…The effects of dietary MOS on fish immunity and other biological functions could be relevant in activating or inhibiting related signaling pathways, reflected as the expression of pathway genes. In C. idella , the expression of antioxidant-, apoptosis-, tight junction-, and immune-related genes was regulated by dietary MOS, among which the expression of most antioxidant and tight junction-related genes was induced, whereas that of pro-apoptotic and pro-inflammatory factors was reduced ( 38 ). Similarly, the expression of antioxidant-related genes was also upregulated in the intestines ( 9 ).…”

Dietary mannan oligosaccharides strengthens intestinal immune barrier function via multipath cooperation during Aeromonas Hydrophila infection in grass carp (Ctenopharyngodon Idella)

“…Laboratory analysis and the operational parameters of the blotting of intestinal homogenates and antibodies were performed as previously described ( 4 , 5 ). Extraction and determination of tissue proteins was done using the RIPA and BCA assay kit (Beyotime).…”

“…Following membrane washing, incubation with secondary antibodies was done incubated at room temperature for 90 minutes. Based on the previous description, protein signals were then visualized and quantified using NIH Image J, 1.42q ( 4 , 5 , 28 ). The detailed description of all antibodies is listed in Supplementary Table 5 of the current study.…”