β-1,3/1,6-Glucan alleviated intestinal mucosal barrier impairment of broiler chickens challenged with Salmonella enterica serovar Typhimurium

Abstract

This study investigated the protective effect of β-1,3/1,6-glucan on gut morphology, intestinal epithelial tight junctions, and bacterial translocation of broiler chickens challenged with Salmonella enterica serovar Typhimurium. Ninety Salmonella-free Arbor Acre male broiler chickens were randomly divided into 3 groups: negative control group (NC), Salmonella Typhimurium-infected positive group (PC), and the Salmonella Typhimurium-infected group with dietary 100 mg/kg of β-1,3/1,6-glucan supplementation (T) to determine the effect of β-1,3/1,6-glucan on intestinal barrier function. Salmonella Typhimurium challenge alone significantly decreased villus height (P < 0.001), villus height/crypt depth ratio (P < 0.05), and the number of goblet cells (P < 0.001) in the jejunum at 14 d postinfection (dpi), but significantly increased the number of intestinal secretory IgA (sIgA)-expressing cells at 14 dpi (P < 0.01) and total sIgA levels in the jejunum at 7 (P < 0.05) and 14 dpi (P < 0.01) compared with the unchallenged birds (NC). Dietary β-1,3/1,6-glucan supplementation not only significantly increased villus height, villus height/crypt depth ratio, and the number of goblet cells (P < 0.01), but also increased the number of sIgA-expressing cells (P < 0.05) and sIgA content in the jejunum at 14 dpi (P < 0.01) in birds challenged with Salmonella Typhimurium in comparison with Salmonella Typhimurium challenge alone. β-1,3/1,6-Glucan addition had significant inhibitory effects (P < 0.05) on cecal Salmonella colonization levels and liver Salmonella invasion of the Salmonella Typhimurium-infected birds compared with the PC group. Intestinal tight junction proteins claudin-1, claudin-4, and occludin mRNA expression in the jejunum at 14 dpi was significantly decreased by Salmonella Typhimurium challenge alone (P < 0.01) compared with that of the NC group, whereas β-1,3/1,6-glucan supplementation significantly increased claudin-1 and occludin mRNA expression (P < 0.01) at 14 dpi in the jejunum of the Salmonella Typhimurium-infected birds in comparison with the PC group. Our results indicate that dietary β-1,3/1,6-glucan can alleviate intestinal mucosal barrier impairment in broiler chickens challenged with Salmonella Typhimurium.

Intestinal barrier and mucosal immunity in broilers, Thai Betong, and native Thai Praduhangdum chickens

“…Therefore, intestinal TJ proteins could improve gut integrity and nutrient absorption, thereby increasing the growth rate in Thai-breed chickens. TJs are also related to innate mucosal immunity, protecting the host from bacterial colonization and invasion to the submucosa (8,17). It was found that these molecules were present in significantly low numbers in Thai-breed chickens.…”

“…It is also found in the intestinal crypts of chickens (15). Antimicrobial defensin peptides from Paneth cells form a gradient within the mucosal layer on the epithelial surface (14) and aid antimicrobials against both gramnegative and positive bacteria (8,(15)(16)(17)(18). The temporary weakening of the mucosal surface and lower amount of β-defensin resulted in the intestine being more penetrable to intraluminal bacteria.…”

“…Improved mucosal immune responses were also observed in broilers when challenged with pathogenic bacteria (8,17,21). Impairment of TJ proteins in broilers has been found to be associated with intestinal disruption, but studies on the role of claudin-1 and occludin in the small intestine are still limited (8). The current study aimed to determine the morphologic localization of TJ and mucosal proteins and describe their effect on the gut health of different strains of chickens from Thailand.…”

“…Claudin and occludin proteins are mainly responsible for intestinal barrier function and paracellular diffusion (1,7,8,19). Claudin-1 proteins are constantly expressed in the intestinal lining from the hatching period to the formation of adult chickens (20).…”

“…In chickens, an impaired intestinal barrier can lead to poor growth performance due to inefficient nutrient digestion and absorption (7). Several studies have noted that mRNA expression and the levels of serum proteins, e.g., claudin-1, occludin, ZO-1, and cytokines, can be used in broilers as biomarkers to determine the function of the gut barrier (7,8).…”