Cecal Infusion of Sodium Propionate Promotes Intestinal Development and Jejunal Barrier Function in Growing Pigs

Unlocking the power of short-chain fatty acids in ameliorating intestinal mucosal immunity: a new porcine nutritional approach

Short-chain fatty acids (SCFAs), a subset of organic fatty acids with carbon chains ranging from one to six atoms in length, encompass acetate, propionate, and butyrate. These compounds are the endproducts of dietary fiber fermentation, primarily catalyzed by the glycolysis and pentose phosphate pathways within the gut microbiota. SCFAs act as pivotal energy substrates and signaling molecules in the realm of animal nutrition, exerting a profound influence on the intestinal, immune system, and intestinal barrier functions. Specifically, they contibute to 60-70% of the total energy requirements in ruminants and 10-25% in monogastric animals. SCFAs have demonstrated the capability to effectively modulate intestinal pH, optimize the absorption of mineral elements, and impede pathogen invasion. Moreover, they enhance the expression of proteins associated with intestinal tight junctions and stimulate mucus production, thereby refining intestinal tissue morphology and preserving the integrity of the intestinal structure. Notably, SCFAs also exert anti-inflammatory properties, mitigating inflammation within the intestinal epithelium and strengthening the intestinal barrier's defensive capabilities. The present review endeavors to synthesize recent findings regarding the role of SCFAs as crucial signaling intermediaries between the metabolic activities of gut microbiota and the status of porcine cells. It also provides a comprehensive overview of the current literature on SCFAs' impact on immune responses within the porcine intestinal mucosa.

Do high-protein diets have the potential to reduce gut barrier function in a sex-dependent manner?

PURPOSE

Impaired gut barrier function is associated with systemic inflammation and many chronic diseases. Undigested dietary proteins are fermented in the colon by the gut microbiota which produces nitrogenous metabolites shown to reduce barrier function in vitro. With growing evidence of sex-based differences in gut microbiotas, we determined whether there were sex by dietary protein interactions which could differentially impact barrier function via microbiota modification.

METHODS

Fermentation systems were inoculated with faeces from healthy males (n = 5) and females (n = 5) and supplemented with 0.9 g of non-hydrolysed proteins sourced from whey, fish, milk, soya, egg, pea, or mycoprotein. Microbial populations were quantified using fluorescence in situ hybridisation with flow cytometry. Metabolite concentrations were analysed using gas chromatography, solid phase microextraction coupled with gas chromatography-mass spectrometry and ELISA.

RESULTS

Increased protein availability resulted in increased proteolytic Bacteroides spp (p < 0.01) and Clostridium coccoides (p < 0.01), along with increased phenol (p < 0.01), p-cresol (p < 0.01), indole (p = 0.018) and ammonia (p < 0.01), varying by protein type. Counts of Clostridium cluster IX (p = 0.03) and concentration of p-cresol (p = 0.025) increased in males, while females produced more ammonia (p = 0.02), irrespective of protein type. Further, we observed significant sex-protein interactions affecting bacterial populations and metabolites (p < 0.005).

CONCLUSIONS

Our findings suggest that protein fermentation by the gut microbiota in vitro is influenced by both protein source and the donor's sex. Should these results be confirmed through human studies, they could have major implications for developing dietary recommendations tailored by sex to prevent chronic illnesses.

Cell migration and proliferation capacity of IPEC-J2 cells after short-chain fatty acid exposure

Novel antimicrobial strategies are necessary to tackle using antibiotics during the suckling and weaning period of piglets, often characterized by E. coli-induced diarrhea. In the last decades, acetate, propionate, and butyrate, all short-chain fatty acids (SCFAs), have been proposed as an alternative to antibiotics. SCFAs are instrumental in promoting the proliferation of enterocytes, preserving intestinal integrity, and modulating the microbial community by suppressing the growth of pathogenic bacteria in pigs. The effect of individual SCFAs (proprionate, acetate and butyrate) on the regenerative capacity of intestinal cells was investigated via an optimized wound-healing assay in IPEC-J2 cells, a porcine jejunal epithelial cell line. IPEC-J2 cells proved a good model as they express the free fatty acid receptor 2 (FFAR2), an important SCFA receptor with a high affinity for proprionate. Our study demonstrated that propionate (p = 0.005) and acetate (p = 0.037) were more effective in closing the wound than butyrate (p = 0.190). This holds promise in using SCFA's per os as an alternative to antibiotics.

Dietary sodium acetate and sodium butyrate attenuate intestinal damage and improve lipid metabolism in juvenile largemouth bass (Micropterus salmoides) fed a high carbohydrate diet by reducing endoplasmic reticulum stress

High-carbohydrate (HC) diets decrease the intestinal levels of sodium acetate (SA) and sodium butyrate (SB) and impair the gut health of largemouth bass; however, SA and SB have been shown to enhance immunity and improve intestinal health in farmed animals. Thus, the present study was to investigate the effects of dietary SA and SB on HC diet-induced intestinal injury and the potential mechanisms in juvenile largemouth bass. The experiment set five isonitrogenous and isolipidic diets, including a low-carbohydrate diet (9% starch) (LC), a high carbohydrate diet (18% starch) (HC), and the HC diet supplemented with 2 g/kg SA (HCSA), 2 g/kg SB (HCSB) or a combination of 1 g/kg SA and 1 g/kg SB (HCSASB). The feeding experiment was conducted for 8 weeks. A total of 525 juvenile largemouth bass with an initial body weight of 7.00 ± 0.20 g were used. The results showed that dietary SA and SB improved the weight gain rate and specific growth rate (P < 0.05) and ameliorated serum parameters (alkaline phosphatase, acid phosphatase, glutamate transaminase, and glutamic oxaloacetic transaminase) (P < 0.05). And, importantly, dietary SA and SB repaired the intestinal barrier by increasing the expression levels of zonula occludens-1, occludin, and claudin-7 (P < 0.05), reduced HC-induced intestinal damage, and alleviated intestinal inflammation and cell apoptosis by attenuating HC-induced intestinal endoplasmic reticulum stress (P < 0.05). Further results revealed that dietary SA and SB reduced HC-induced intestinal fat deposition by inhibiting adipogenesis and promoting lipolysis (P < 0.05). In summary, this study demonstrated that dietary SA and SB attenuated HC-induced intestinal damage and reduced excessive intestinal fat deposition in largemouth bass.

Saposhnikovia divaricata root and its major components ameliorate inflammation and altered gut microbial diversity and compositions in DSS-induced colitis

Background

The root of Saposhnikovia divaricata (Turcz.) Schischk is a well-known traditional medicinal plant, containing various bioactive compounds with anti-inflammatory, antioxidant, and analgesic properties. However, no scientific studies have validated its clinical use as an anti-inflammatory agent against inflammatory bowel disease (IBD). This study aimed to investigate whether the root extract of S. divaricata ameliorates IBD and induces gut microbial alteration, using a RAW 264.7 cell line and a DSS-induced colitis mouse model.

Methods

To investigate the anti-inflammatory effects and alleviation of IBD, using a methanol extract of Saposhnikovia divaricata (Turcz.) Schischk. root (MESD), RAW 264.7, murine macrophages and a dextran sodium sulfate (DSS)-induced colitis mouse model were employed. 16S rRNA gene sequencing was conducted to determine the alterations in the gut microbiota of mice with DSS-induced colitis.

Results

MESD significantly decreased nitric oxide (NO) and inflammatory cytokine levels in lipopolysaccharide (LPS)-induced RAW 264.7 cells in vitro. Oral administration of MESD reduced the expression of inflammatory cytokines in the colons of mice with DSS-induced colitis. Additionally, MESD inhibited the abundance of Clostridium sensu stricto 1 and enhanced the predicted functional pathways, including l-glutamate degradation VIII (to propanoic acid). Seven compounds with anti-inflammatory properties were isolated from the MESD. Among them, 3'-O-acetylhamaudol and 3'-O-angeloylhamaudol exhibited strong anti-inflammatory effects in vitro.

Conclusion

Overall, MESD may be a potential natural product for the treatment of IBD by lowering inflammatory cytokine levels and altering gut microbiota composition.

IPA and its precursors differently modulate the proliferation, differentiation, and integrity of intestinal epithelial cells

BACKGROUND/OBJECTIVES

Indole-3-propionic acid (IPA) is a tryptophan-derived microbial metabolite that has been associated with protective effects against inflammatory and metabolic diseases. However, there is a lack of knowledge regarding the effects of IPA under physiological conditions and at the intestinal level.

MATERIALS/METHODS

Human intestinal epithelial Caco-2 cells were treated for 2, 24, and/or 72 h with IPA or its precursors - indole, tryptophan, and propionate - at 1, 10, 100, 250, or 500 μM to assess cell viability, integrity, differentiation, and proliferation.

RESULTS

IPA induced cell proliferation and this effect was associated with a higher expression of extracellular signal-regulated kinase 2 (ERK2) and a lower expression of c-Jun. Although indole and propionate also induced cell proliferation, this involved ERK2 and c-Jun independent mechanisms. On the other hand, both tryptophan and propionate increased cell integrity and reduced the expression of claudin-1, whereas propionate decreased cell differentiation.

CONCLUSIONS

In conclusion, these findings suggested that IPA and its precursors distinctly contribute to the proliferation, differentiation, and barrier function properties of human intestinal epithelial cells. Moreover, the pro-proliferative effect of IPA in intestinal epithelial cells was not explained by its precursors and is rather related to its whole chemical structure. Maintaining IPA at physiological levels, e.g., through IPA-producing commensal bacteria, may be important to preserve the integrity of the intestinal barrier and play an integral role in maintaining metabolic homeostasis.

Soluble dietary fiber and cellulose from Saccharina japonica by-product ameliorate Loperamide-induced constipation via modulating enteric neurotransmitters, short-chain fatty acids and gut microbiota

The effects of soluble dietary fiber (SDF) and cellulose (IDF) from Saccharina japonica by-product and their differences in improving constipation were further clarified in the present study. We demonstrated that SDF was mainly made up of d-mannuronic acid and d-mannose while IDF consisted of d-glucose , which is different from other reported dietary fibers of terrestrial plants. In this research, both SDF and IDF improved fecal-related indicators, gastrointestinal transit rate and histological morphology in Lop-induced mice. Moreover, they could increase the level of antioxidant enzymes (SOD and GSH-Px), restore the expression of enteric neurotransmitters, and maintain the function of ZO-1, JAM-1 as well as Occludin. Interestingly, SDF and IDF had a significant up-regulated effect on the proportion of Muribaculacea, Prevotellaceaen and Lachnospiraceae, which are critical to preserving intestinal immune homeostasis. Besides, they promoted the biosynthesis of short-chain fatty acids (SCFAs). The overall index showed that SDF is more effective for constipation due to its better water retention capacity. Thus, they can be used as a safe dietary supplement for the treatment of chronic or occasional constipation in humans.

Compound organic acid could improve the growth performance, immunity and antioxidant properties, and intestinal health by altering the microbiota profile of weaned piglets

This study aimed to investigate the impact of compound organic acid (COA) and chlortetracycline (CTC) on serum biochemical parameters, intestinal health, and growth performance of weaned piglets. Twenty-four piglets (24 d of age) were randomly allocated into three treatments with eight replicate pens (one piglet per pen). Feed the basal diet or a diet containing 3,000 mg/kg COA or 75 mg/kg CTC, respectively. Results showed that both COA and CTC significantly increased average daily gain and reduced diarrhea rates (P < 0.05). They also upregulated serum total antioxidant capacity and downregulated serum interleukin (IL-10) levels (P < 0.05), increased crude protein digestibility and propionic acid concentration in the colon, and decreased spermidine and putrescine contents (P < 0.05). Intestinal microbiota analysis revealed that both COA and CTC increased the Shannon and Chao1 index and decreased the relative abundance of Blautia and Roseburia, but increased the relative abundance of Clostridium-sensu-stricto-1. Correlation analysis indicated that Clostridium-sensu-stricto-1 may be closely related to inflammation levels and microbial metabolites in piglets. Based on the results, COA may be a potential substitute for CTC to reduce antibiotic use and biogenic amine emission while improving piglet growth and intestinal health.

Effects of Protein-Chelated Zinc Combined with Mannan-Rich Fraction to Replace High-Dose Zinc Oxide on Growth Performance, Nutrient Digestibility, and Intestinal Health in Weaned Piglets

A total of 168 weaned piglets (average initial body weight of 7.70 ± 0.75 kg) were used in a 4-week feeding trial to investigate the effects of dietary supplementation with protein-chelated zinc (Zn-Pro) alone or combined with a mannan-rich fraction (MRF) to replace high-dose zinc oxide (ZnO) for weaned piglets. The dietary treatments included a basal diet as control (CON), a ZnO diet (basal diet + 1600 mg Zn/kg from ZnO), a Zn-Pro diet (basal diet + 60 mg Zn/kg from Zn-Pro), and a MRF plus Zn-Pro diet (MRP, basal diet + 800 mg/kg MRF + 60 mg Zn/kg from Zn-Pro). The average daily gain of piglets in the MRP group was higher (p ≤ 0.05) than that in CON and Zn-Pro groups during d 15-28 and d 1-28 of experiment. The apparent total tract digestibility of dry matter, organic matter, and crude protein in the MRP group was higher (p ≤ 0.05) than that in the CON group. The serum insulin-like growth factor-1 level in the MRP group was markedly higher (p ≤ 0.05) than that of piglets in the other three treatment groups. Piglets fed the Zn-Pro and ZnO diets had greater (p ≤ 0.05) acetic acid in cecal digesta than those fed the CON diet, while the MRP diet had higher (p ≤ 0.05) cecal propionate concentration than those that were fed the CON diet on d 28 of experiment. Moreover, the villus height of ileum in the MRP group tended to be greater than the CON group (p = 0.09). Compared with the CON and MRP groups, the relative abundance of Lactobacillaceae (p = 0.08) and Lachnospiraceae (p = 0.09) in the Zn-Pro group showed an increasing trend. The relative abundance of Prevotellaceae in the Zn-Pro group was significantly lower (p ≤ 0.05) than that in the MRP group. In conclusion, the combined addition of MRF and Zn-Pro acted as a suitable alternative to ZnO to beneficially support the growth performance and intestinal health of weaned piglets, as well as contribute to a lower diarrhea rate and environmental pollution from fecal zinc excretion.

Role of short chain fatty acids in gut health and possible therapeutic approaches in inflammatory bowel diseases

Inflammatory bowel diseases (IBDs) are characterized by inflammation in the gastrointestinal tract and include Ulcerative Colitis and Crohn’s Disease. These diseases are costly to health services, substantially reduce patients’ quality of life, and can lead to complications such as cancer and even death. Symptoms include abdominal pain, stool bleeding, diarrhea, and weight loss. The treatment of these diseases is symptomatic, seeking disease remission. The intestine is colonized by several microorganisms, such as fungi, viruses, and bacteria, which constitute the intestinal microbiota (IM). IM bacteria promotes dietary fibers fermentation and produces short-chain fatty acids (SCFAs) that exert several beneficial effects on intestinal health. SCFAs can bind to G protein-coupled receptors, such as GPR41 and GPR43, promoting improvements in the intestinal barrier, anti-inflammatory, and antioxidant effects. Thus, SCFAs could be a therapeutic tool for IBDs. However, the mechanisms involved in these beneficial effects of SCFAs remain poorly understood. Therefore, this paper aims to provide a review addressing the main aspects of IBDs, and a more detailed sight of SCFAs, focusing on the main effects on different aspects of the intestine with an emphasis on IBDs.

Alterations in Intestinal Brush Border Membrane Functionality and Bacterial Populations Following Intra-Amniotic Administration (Gallus gallus) of Nicotinamide Riboside and Its Derivatives

Nicotinamide riboside (NR) acts as a nicotinamide adenine dinucleotide (NAD+) precursor where NR supplementation has previously been shown to be beneficial. Thus, we synthesized and characterized nicotinamide riboside tributyrate chloride (NRTBCl, water-soluble) and nicotinamide riboside trioleate chloride (NRTOCl, oil-soluble) as two new ester derivatives of nicotinamide riboside chloride (NRCl). NRCl and its derivatives were assessed in vivo, via intra-amniotic administration (Gallus gallus), with the following treatment groups: (1) non-injected (control); and injection of (2) deionized H₂O (control); (3) NRCl (30 mg/mL dose); (4) NRTBCl (30 mg/mL dose); and (5) NRTOCl (30 mg/mL dose). Post-intervention, the effects on physiological markers associated with brush border membrane morphology, intestinal bacterial populations, and duodenal gene expression of key proteins were investigated. Although no significant changes were observed in average body weights, NRTBCl exposure increased average cecum weight. NR treatment significantly increased Clostridium and NRCl treatment resulted in increased populations of Bifidobacterium, Lactobacillus, and E. coli. Duodenal gene expression analysis revealed that NRCl, NRTBCl, and NRTOCl treatments upregulated the expression of ZnT1, MUC2, and IL6 compared to the controls, suggesting alterations in brush border membrane functionality. The administration of NRCl and its derivatives appears to trigger increased expression of brush border membrane digestive proteins, with added effects on the composition and function of cecal microbial populations. Additional research is now warranted to further elucidate the effects on inflammatory biomarkers and observe changes in the specific intestinal bacterial populations post introduction of NR and its derivatives.

Gut microbiome-produced metabolites in pigs: a review on their biological functions and the influence of probiotics

The gastrointestinal tract is a complex ecosystem that contains a large number of microorganisms with different metabolic capacities. Modulation of the gut microbiome can improve the growth and promote health in pigs. Crosstalk between the host, diet, and the gut microbiome can influence the health of the host, potentially through the production of several metabolites with various functions. Short-chain and branched-chain fatty acids, secondary bile acids, polyamines, indoles, and phenolic compounds are metabolites produced by the gut microbiome. The gut microbiome can also produce neurotransmitters (such as γ-aminobutyric acid, catecholamines, and serotonin), their precursors, and vitamins. Several studies in pigs have demonstrated the importance of the gut microbiome and its metabolites in improving growth performance and feed efficiency, alleviating stress, and providing protection from pathogens. The use of probiotics is one of the strategies employed to target the gut microbiome of pigs. Promising results have been published on the use of probiotics in optimizing pig production. This review focuses on the role of gut microbiome-derived metabolites in the performance of pigs and the effects of probiotics on altering the levels of these metabolites.

Effects of Tetrabasic Zinc Chloride on Growth Performance, Nutrient Digestibility and Fecal Microbial Community in Weaned Piglets

The study was conducted to explore the effects of tetrabasic zinc chloride (TBZC), as an alternative to zinc oxide (ZnO), on growth performance, serum indexes, and fecal microbiota of weaned piglets. A total of 108 weaned piglets (average initial body weight of 7.84 ± 0.97 kg) were randomly allocated into one of three dietary treatments with six replicate pens and six piglets per pen. The dietary treatments included a control diet (CON, negative control), a ZnO diet (CON + 1,600 mg Zn/kg from ZnO, positive control), and a TBZC diet (CON + 1,000 mg Zn/kg from TBZC). The average daily gain of pigs in the TBZC group was greater (P < 0.05) than those in CON and ZnO groups during the whole period. Piglets fed the ZnO and TBZC diets showed lower (P < 0.05) diarrhea incidence than those fed the CON diet during d 1-14 and the whole period. Piglets fed the TBZC diet had higher (P < 0.05) digestibility of crude protein and gross energy than those fed the CON diet. Serum concentrations of IGF-I and GH, as well as ALP activity, were significantly elevated (P < 0.05) in the TBZC treatment group compared to the CON group on d 14. Piglets fed the ZnO diet had greater (P < 0.05) acetate and total short-chain fatty acids concentrations, while the TBZC diet had greater (P < 0.05) fecal acetate and propionate concentrations on d 28. Moreover, TBZC supplementation significantly increased (P < 0.05) microbial α-diversity compared with the CON group. The fecal microbiota of piglets in ZnO and TBZC treatment groups tended (P = 0.08) to have greater relative abundance of Prevotellaceae compared with the CON piglets. In conclusion, TBZC acted as a suitable alternative to ZnO to reduce zinc excretion, and improve growth performance of weaned piglets.

Sophorolipid protects against early-weaning syndrome by improving the gut microenvironment in early-weaned piglets

Background

In animals, weaning stress is the first and most critical stress. Weaning can negatively affect the growth performance of animals physically, psychologically, and pathologically. Our previous studies on the HT-29 cell line and early-weaned rats demonstrated that adequate sophorolipid (SPL) supplementation in feed could enhance the mucin-producing and wound healing capacities of the gut defense system by modulating gut microbiota.

Methods

We conducted an experiment with one hundred forty 21-day-old early weaned piglets (L x Y x D). They were allocated into 4 treatment and 7 replications (4 pigs per pen) according to their initial body weight. Body weight and feed intake were measured biweekly during experimental period. After 6 weeks, 28 pigs were randomly selected and sacrificed to collect plasma, jejunum, and cecal content samples.

Results

Dietary SPL supplementation at 5 and 10 mg/kg quadratically increased the average daily gain during the experimental period in the treatment groups when compared with the control group. The albumin levels of piglets fed with the SPL supplemented diet were downregulated to the normal range. Moreover, in feed, SPL supplementation at 5 and 10 mg/kg improved jejunal histological indices and gene expression levels related to mucin secretion and local inflammation markers. Consistent with these results, adequate SPL supplementation (5 and 10 mg/kg) increased the population of Prevotella, a beneficial bacterium, and its short-chain fatty acid production in the ceca of piglets.

Conclusions

The occurrence of diarrhea after weaning in piglets could be reduced by feeding a 10 ppm of SPL supplemented diet which improves the gut defense system by improving the microbial population and enhancing mucin layer integrity.

Propionate and Dietary Fermentable Fibers Upregulate Intestinal Heat Shock protein70 in Intestinal Caco-2 Cells and Mouse Colon

Short-chain fatty acids (SCFAs), including propionate, are major metabolites of intestinal microorganisms and play an essential role in regulating intestinal epithelial integrity. Heat shock proteins (HSPs) promote cellular homeostasis under physiological and stressed conditions. This study aimed to investigate the regulation of intestinal HSP70 by propionate in human intestinal Caco-2 cells and the colon of fermentable dietary fiber (DF)-fed mice and germ-free mice. The results showed that propionate increased Hspa1a (HSP70 mRNA) level in Caco-2 cells, upregulated HSP70 protein, and phosphorylation of heat shock factor 1; however, the latter two were reduced by mitogen-activated protein kinases and the mechanistic target of rapamycin inhibitors. Feeding fermentable DFs, such as guar gum (GG) and partially hydrolyzed GG, increased both cecal SCFAs and colonic HSP70 expression, both of which were reduced in germ-free mice than in specific-pathogen-free mice. Collectively, the propionate-induced HSP70 expression was shown to be possibly involved in intestinal homeostasis.

Butyrate Mitigates Weanling Piglets From Lipopolysaccharide-Induced Colitis by Regulating Microbiota and Energy Metabolism of the Gut-Liver Axis

Inflammatory bowel disorder is accompanied by the destruction of immunity homeostasis, gut microbiota perturbation, and chronic inflammatory liver diseases. Butyrate is known as a primary energy source for colonocytes and functional substances for mitigating pathological features of colitis. However, it is still unclear whether butyrate alleviates colitis progression by regulation of microbiota and metabolism in the gut-liver axis. In the present study, we aimed to determine the role of microbiota and metabolism of the gut-liver axis in ameliorating lipopolysaccharide (LPS)-induced colitis in piglets using protected butyrate administration. Eighteen crossbred male piglets were weaned at 30 days old and were randomly allocated to three treatments, with CON (basal diet), LPS (basal diet + LPS), and BT-LPS (basal diet + 3.0 g/kg protected butyrate + LPS). On days 19 and 21, piglets in the LPS and BT-LPS groups were intraperitoneally challenged with LPS at 100 μg/kg body weight. Butyrate administration significantly decreased LPS-induced rise in the clinical score of piglets and colonic histological scores and reduced the susceptibility to LPS-induced severe inflammatory response by decreasing proinflammatory (IL-1β, IL-6, IL-8, and TNF-α) cytokines. Butyrate supplementation accelerated the prevalence of Faecalibacterium and Lactobacillus by enhancing the tricarboxylic acid (TCA) cycle of colonocytes. Dietary supplementation with protected butyrate significantly targeted increased concentrations of butyric acid in the colon and portal venous circulation, and enhanced the TCA cycle in the gut-liver axis by mobilizing amino acid and vitamin B group as a coenzyme. Meanwhile, during this progress, LPS increased fatty acid synthesis that was reversed by butyrate treatment, which was reflected by decreased acylcarnitines. Butyrate-reshaped colonic microbial community and metabolism in the gut-liver axis contributed to morphology integrity and immunity homeostasis by promoting anti-inflammatory (IL-10 and TGF-β) cytokines and suppressing inflammatory mediator hypoxia-inducible factor 1α and its downstream response elements cyclooxygenase 2 and inducible nitric oxide synthase. These results identified the pivotal role of colonic microbiota and metabolism in the gut-liver axis for alleviating inflammatory progression and possible therapeutic targets.

Effects of wheat bran in comparison to antibiotics on growth performance, intestinal immunity, barrier function, and microbial composition in broiler chickens

This experiment was conducted to evaluate the effects of wheat bran (WB) and antibiotics on growth performance, intestinal immunity, barrier function, and microbial composition in broiler chickens. A total of 168 one-day-old male Arbor Acre chicks were allocated to 3 treatments consisting of 7 replicates with 8 birds per replicate. The 3 treatments were: an antibiotic-free control diet (control, CON), CON + 75 mg/kg chlortetracycline as an antibiotic growth promoter (AGP), and CON + 3% WB. Birds fed AGP and WB had greater (P < 0.05) ADG during days 1 to 21 and lower (P < 0.05) feed-to-gain ratio during each phase than those fed CON. The WB supplementation reduced (P < 0.05) serum concentrations of tumor necrosis factor-α and diamine oxidase activity compared with CON on both day 21 and 42. The AGP and WB supplementation decreased (P < 0.05) interleukin-1β concentration in jejunal mucosa on day 21 and increased (P < 0.05) secretory immunoglobulin A concentration in jejunal mucosa on day 21 and 42. The relative expression of occludin in jejunal mucosa was upregulated (P < 0.05) in WB than in CON on day 21. Moreover, both AGP and WB supplementation upregulated (P < 0.05) the relative expression of zonula occludens-1 in jejunal mucosa on day 21 and 42. The WB supplementation enhanced the α-diversity of cecal microbiota, as evidenced by the increased Shannon index (P < 0.05). At the phylum level, the phylum Firmicutes was enriched (P < 0.05) in WB. At the genus level, the WB supplementation enriched (P < 0.05) Lachnoclostridium and Butyricicoccus. The WB supplementation increased (P < 0.05) cecal total short chain fatty acids concentrations on day 21 and 42, and butyric acid concentrations on day 42 compared with CON. Collectively, supplementation of 3% WB could promote growth by improving intestinal immunity, barrier function, and microbial composition in broilers. Thus, WB may have a role in replacing antibiotics for improved growth performance and intestinal health in broilers.

Hepatic Metabolomic and Transcriptomic Responses Induced by Cecal Infusion of Sodium Propionate in a Fistula Pig Model

Short-chain fatty acids (SCFAs) are the major products of the microbial fermentation of indigestible carbohydrates. SCFAs are known to improve the host metabolism, but their underlying mechanism of action remains elusive. In this study, 16 growing pigs were infused with saline or sodium propionate solution (25 mL, 2 mol/L) through a cecal fistula twice a day during a 28 day experimental period. The results showed that the cecal infusion of the SCFA propionate decreased serum and liver triglyceride levels and increased serum PYY secretion in growing pigs. Hepatic metabolomics identified 12 metabolites that were significantly altered by propionate. These included decreased levels of lipid metabolism-related stearic acid and glycerol-2-phosphate; increased levels of TCA cycle components including malic acid, fructose-6-phosphate, and succinic acid; and decreased levels of the amino acid metabolism products aspartic acid and serine. Hepatic transcriptomics demonstrated that propionate inhibited fatty acid synthesis and promoted the lipid metabolic process. Pathway enrichment analysis showed that propionate accelerated gluconeogenesis and decreased glycolysis. Taken together, these data support a role of the SCFA propionate on host lipid and glucose metabolism.