Gut flora and its modification as a therapy

Functions and mechanisms of nonstarch polysaccharides in monogastric animal production

As natural active ingredients, polysaccharides are a class of biological macromolecules that are ubiquitous in living organisms and have antibacterial, antioxidant, antitumor and intestinal flora-regulating functions. Nonstarch polysaccharides (NSPs) are an important class of polysaccharides that include both soluble and insoluble nonstarch polysaccharides. As green feed additives, NSPs play important roles in promoting immunity and disease resistance in the body, regulating the intestinal microbial balance and improving the quality of animal products. NSPs regulate cell signal transduction mainly via interactions between short-chain fatty acids and G protein-coupled receptors and inhibiting the histone deacetylation pathway to protect the intestinal barrier in animals. In this paper, the composition, physiological functions, and molecular mechanisms of the gut protective effects of NSPs are reviewed to provide a reference for the application of NSPs in monogastric animal production.

Transdermal Administration of Volatile Oil from Citrus aurantium-Rhizoma Atractylodis Macrocephalae Alleviates Constipation in Rats by Altering Host Metabolome and Intestinal Microbiota Composition

Background

The Citrus aurantium- (ZhiShi, ZS-) Rhizoma Atractylodis Macrocephalae (BaiZhu, BZ) pairs are often found in herbal formulas for constipation. The volatile oils of ZS and BZ (ZBVO) have good pharmacological activity against constipation, but the mechanism for treatment of slow transit constipation (STC) remains unclear.

Method

A rat model using diphenoxylate tablets was constructed to investigate if transdermal administration of ZBVO would mediate intestinal microorganisms and fecal metabolites and improve STC symptoms. The regulatory effects of ZBVO at 0.15, 0.30, and 0.60 mL kg⁻¹ d⁻¹ on STC rats were assessed by measuring fecal water content, intestinal propulsion rate, histopathology, expression of gastrointestinal hormones, brain and intestinal peptides, and inflammatory factors. The changes in intestinal flora of STC rats were analyzed by 16S rRNA gene sequencing. Moreover, the untargeted fecal metabolomics analysis was performed by ultraperformance liquid chromatography quadrupole time-of-flight mass spectrometer (UPLC-Q-TOF-MS) technology.

Results

The results showed that ZBVO had a modulating effect on STC by increasing the fecal water content and intestinal propulsion rate. Transdermal administration of ZBVO decreased serum levels of interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) and increased the levels of gastrin (GAS) and substance P (SP). In addition, ZBVO increased 5-hydroxytryptamine (5-HT) levels and decreased vasoactive intestinal peptide (VIP) levels in colon and hippocampus tissues. The results of intestinal microbiota showed that ZBVO improved the diversity and abundance of intestinal microbiota and changed the community composition by decreasing Romboutsia and increasing Proteobacteria, Allobaculum, and Ruminococcaceae. And the feces metabolomics found that nicotinate and nicotinamide metabolism, purine metabolism, citrate cycle (TCA cycle), pyruvate metabolism, arachidonic acid metabolism, pyrimidine metabolism, and primary bile acid biosynthesis were modulated.

Conclusion

These findings suggest that ZBVO can alleviate STC symptoms by promoting intestinal peristalsis, increasing fecal water content, regulating gastrointestinal hormone level, reducing the inflammatory response, and regulating brain and intestinal peptides after transdermal administration. And structural changes in the intestinal microbiota are closely related to host metabolism and intestinal microbiota destroyed in STC modeling could be significantly improved by the ZBVO, which provides a reference for the development of aromatic drug macrohealth products.

Effect of Niacin on Growth Performance, Intestinal Morphology, Mucosal Immunity and Microbiota Composition in Weaned Piglets

Simple Summary

The protective effect of niacin on growth performance and gut health of weaned piglets and the underlying mechanism remains unclear despite it being a common additive in pig diets. The present study aimed to investigate the effect of niacin on growth performance, intestinal morphology, intestinal mucosal immunity, and colonic microbiota in weaned piglets. Our results show that niacin supplementation significantly improved the growth performance in piglets as compared with those given a niacin receptor antagonist. Niacin also significantly improved the relative abundance of beneficial bacteria in the colon and alleviate the inflammatory response in the intestinal mucosa as compared with control piglets and those given a niacin receptor antagonist. These results provide new insight into the beneficial effects of niacin on growth performance and gut health in weaned piglets.

Abstract

This study aimed to investigate the effects of niacin on growth performance, intestinal morphology, intestinal mucosal immunity, and colonic microbiota in weaned piglets. A total of 96 weaned piglets (Duroc × (Landrace × Yorkshire), 21-d old, 6.65 ± 0.02 kg body weight (BW)) were randomly allocated into 3 treatment groups (8 replicate pens per treatment, each pen containing 4 males; n = 32/treatment) for 14 d. Piglets were fed a control diet (CON) or the CON diet supplemented with 20.4 mg/kg niacin (NA) or an antagonist for the niacin receptor GPR109A (MPN). The results showed that NA or MPN had no effect on ADG, ADFI, G/F or diarrhea incidence compared with the CON diet. However, compared with piglets in the NA group, piglets in the MPN group had lower ADG (p = 0.042) and G/F (p = 0.055). In comparison with the control and MPN group, niacin supplementation increased the villus height and the ratio of villus height to crypt depth (p < 0.05), while decreasing the crypt depth in the duodenum (p < 0.05). Proteomics analysis of cytokines showed that niacin supplementation increased the expression of duodenal transforming growth factor-β (TGF-β), jejunal interleukin-10 (IL-10) and ileal interleukin-6 (IL-6) (p < 0.05), and reduced the expression of ileal interleukin-8 (IL-8) (p < 0.05) compared with the control diet. Piglets in the MPN group had significantly increased expression of ileal IL-6, and jejunal IL-8 and interleukin-1β (IL-1β) (p < 0.05) compared with those in the control group. Piglets in the MPN group had lower jejunal IL-10 level and higher jejunal IL-8 level than those in the NA group (p < 0.05). The mRNA abundance of duodenal IL-8 and ileal granulocyte-macrophage colony-stimulating factor (GM-CSF) genes were increased (p < 0.05), and that of ileal IL-10 transcript was decreased (p < 0.05) in the MPN group compared with both the control and NA groups. Additionally, niacin increased the relative abundance of Dorea in the colon as compared with the control and MPN group (p < 0.05), while decreasing that of Peptococcus compared with the control group (p < 0.05) and increasing that of Lactobacillus compared with MPN supplementation (p < 0.05). Collectively, the results indicated that niacin supplementation efficiently ensured intestinal morphology and attenuated intestinal inflammation of weaned piglets. The protective effects of niacin on gut health may be associated with increased Lactobacillus and Dorea abundance and butyrate content and decreased abundances of Peptococcus.

Mechanism of Intestinal Flora and Proteomics on Regulating Immune Function of Durio zibethinus Rind Polysaccharide

In this study, cyclophosphamide was injected intraperitoneally to establish an immunosuppressive mouse model to study the immune regulating effects of Durio zibethinus Murr rind polysaccharide (DZMP) through proteomics and intestinal flora. The results showed that the thymus and spleen indexes of the high-dose DZMP (200 mg/kg) group were significantly increased, and the tissue structure of the spleen was improved compared with the model group ( $P<0.01$ ). The contents of IL-2, IL-4, IL-6, and TNF-α in the high-dose group of DZMP were significantly increased ( $P<0.001$ ). Activities of acid phosphatase (ACP), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) were increased in serum ( $P<0.01$ ). In the liver, catalase (CAT) activity was increased ( $P<0.001$ ) while the malondialdehyde (MDA) content was decreased and immune activity was increased ( $P<0.001$ ). Proteomics studies showed that the drug group could significantly increase the low-affinity immunoglobulin gamma Fc receptor III (FcγRIII) protein and protein kinase C-α (PKC-α) compared with the model group ( $P<0.001$ ). In addition, the result showed that those proteins were likely involved in the regulation of the metabolic pathways of autoimmune thyroid disease, Staphylococcus aureus infection, and NF-κB signaling pathway. Intestinal microbial studies showed that short-chain fatty acid (SCFA) content was increased as well as the relative abundance of beneficial bacteria Akkermansia, Bacteroides, and Paraprevotella, while the relative abundance of Ruminococcus and Oscillospira was decreased compared with the model group ( $P<0.001$ ). The results showed that DZMP might play a beneficial role in immune regulation by improving intestinal flora.

Effect of Durio zibethinus rind polysaccharide on functional constipation and intestinal microbiota in rats

The prevalence of constipation increases rapidly with the increased pressure of some people's life, which seriously affects the quality of life in related patients. In this study, the improvement of functional constipation by Durio zibethinus Murr rind polysaccharide (DZMP) and the effects of DZMP on intestinal microbiota were investigated in a constipation model of Sprague-Dawley (SD) rats established by loperamide hydrochloride. Results showed that DZMP at 200 mg/kg could significantly (P < 0.05) increase the intestinal transit rate, motilin, gastrin, substance P levels and concentration of short-chain fatty acids (SCFAs), reduce the somatostatin levels and improve the gastrointestinal peristalsis of rats. Sequencing showed that the Lachnospiraceae-NK4A136-group in the rats given 200 mg/kg DZMP (16.07%) was significantly higher than that of the model group (10.13%), while the Desulfovibrio was lower (2.99%) than that of the model group (4.19%). Principal co-ordinates analysis (PcoA) revealed a significant difference in intestinal microbiota composition between the model group and the high-dose DZMP group (200 mg/kg). The results demonstrated that DZMP has a regulatory effect of treating functional constipation and regulating intestinal flora in rats.

Evaluation of Prebiotic Potential of Three Marine Algae Oligosaccharides from Enzymatic Hydrolysis

Alginate oligosaccharides (AlgO), agarose oligosaccharides (AO), and κ-carrageenan oligosaccharides (KCO) were obtained by specific enzymatic hydrolysis method. The molecular weight distributions of the three oligosaccharides were 1.0⁻5.0 kDa, 0.4⁻1.4 kDa, and 1.0⁻7.0 kDa, respectively. The culture medium was supplemented with the three oligosaccharides and fermented by pig fecal microbiota in vitro, for 24 h. Each oligosaccharide was capable of increasing the concentration of short-chain fatty acids (SCFAs), especially butyric acid, and altering the microbiota composition. Linear discriminant analysis effect size (LEfSe) analysis results showed that the opportunistic pathogenic bacteria Escherichia, Shigella, and Peptoniphilus, were significantly decreased in AlgO supplemented medium. AO could improve the gut microbiota composition by enriching the abundance of Ruminococcaceae, Coprococcus, Roseburia, and Faecalibacterium. Besides, KCO could increase the abundance of SCFA microbial producers and opportunistic pathogenic flora. Therefore, these results indicate that AlgO and AO can be used as gut microbial regulators and can potentially improve animal/human gastrointestinal health and prevent gut disease, whereas the physiological function of KCO needs further evaluation.

Dietary fucoidan modulates the gut microbiota in mice by increasing the abundance ofLactobacillusandRuminococcaceae

This study provides a new insight into the well-recognized beneficial effects of dietary fucoidan by demonstrating its positive modulations on gut microbiota.