Dietary protocatechuic acid ameliorates inflammation and up-regulates intestinal tight junction proteins by modulating gut microbiota in LPS-challenged piglets

Abstract

Background Weaning is one of the major factors that cause stress and intestinal disease in piglets. Protocatechuic acid (PCA) is an active plant phenolic acid which exists in Chinese herb, Duzhong (Eucommia ulmoides Oliver), and is also considered as the main bioactive metabolite of polyphenol against oxidative stress and inflammation. This study aimed to investigate the effect of PCA on growth performance, intestinal barrier function, and gut microbiota in a weaned piglet model challenged with lipopolysaccharide (LPS). Methods Thirty-six piglets (Pig Improvement Company line 337 × C48, 28 d of age, 8.87 kg ± 0.11 kg BW) were randomly allocated into 3 treatments and fed with a basal diet (CTL), a diet added 50 mg/kg of aureomycin (AUR), or a diet supplemented with 4000 mg/kg of PCA, respectively. The piglets were challenged with LPS (10 μg/kg BW) on d 14 and d 21 by intraperitoneal injection during the 21-d experiment. Animals (n = 6 from each group) were sacrificed after being anesthetized by sodium pentobarbital at 2 h after the last injection of LPS. The serum was collected for antioxidant indices and inflammatory cytokines analysis, the ileum was harvested for detecting mRNA and protein levels of tight junction proteins by PCR and immunohistochemical staining, and the cecum chyme was collected for intestinal flora analysis using 16S rRNA gene sequencing. Results Dietary supplementation of PCA or AUR significantly increased the expression of tight junction proteins including ZO-1 and claudin-1 in intestinal mucosa, and decreased the serum levels of thiobarbituric acid reactive substances (TBARS) and IL-6, as compared with CTL group. In addition, PCA also decreased the serum levels of IL-2 and TNF-α (P < 0.05). Analysis of gut microbiota indicated that PCA increased the Firmicutes/Bacteroidetes ratio (P < 0.05). Spearman’s correlation analysis at the genus level revealed that PCA reduced the relative abundance of Prevotella 9, Prevotella 2, Holdemanella, and Ruminococcus torques group (P < 0.05), and increased the relative abundance of Roseburia and Desulfovibrio (P < 0.05), whereas AUR had no significant effect on these bacteria. Conclusions These results demonstrated that both PCA and AUR had protective effect on oxidative stress, inflammation and intestinal barrier function in piglets challenged with LPS, and PCA potentially exerted the protective function by modulating intestinal flora in a way different from AUR. Holdemanella

Gut Immunity and Microbiota Dysbiosis Are Associated with Altered Bile Acid Metabolism in LPS‐Challenged Piglets

“…The reported studies revealed an elevated expression level of proinflammatory cytokines in patients affected with IBD, which implied that targeting the balance between proinflammatory and anti-inflammatory cytokines could be a potential treatment for gut inflammation [47]. In the current study, the obtained results indicated that LPS stimulation not only enhanced the mRNA expression of IL-6 and IL-1β but also enhanced the transcriptional and translational level of iNOS, and further induced intestinal inflammation, which showed consistency with the other reported studies [48,49]. Some studies revealed that gut immunity has been considerably associated with gut microbiota [4,5], and a wide range of gastrointestinal diseases, such as recurrent C. difficile infection (CDI), inflammatory bowel diseases (IBD, including Crohn's disease (CD) and ulcerative colitis (UC)), colorectal cancer (CRC), and metabolic disorders, are affected by the variations observed in the composition and functions of gut microbiota [6,50].…”

Green Tea Polyphenol-Sensitive Calcium Signaling in Immune T Cell Function

“…The interaction between polyphenols including their metabolites and gut microbiota is critical to understanding the biological mechanisms of polyphenols, since polyphenols are poorly absorbed and most of them are metabolized by the microbiome to form phenolic metabolites ( 40 ). Dietary polyphenols could play a key role in growth of several beneficial bacteria including Lactobacillus and Bifidobacterium spp .…”

Modulation of Gut Microbiota and Oxidative Status by β-Carotene in Late Pregnant Sows

“…Lachnospiraceae and Ruminococcaceae are closely related to the production of butyrate (31,32). Prevotellaceae UCG-001 belongs to the family of Prevotellace showed a positive correlation with the expression of inflammatory factors in our recent study (33). Sutterella is positively correlated with neutral detergent fiber (NDF) digestibility (34), and Bilophila has a positive correlation with obesity-related markers (18), while Sedimentibacter can secrete cellulase enzyme to digest cellulose into glucose (19,34).…”