Dietary genistein supplementation improves intestinal mucosal barrier function in Escherichia coli O78-challenged broilers

An Isofibrous Diet with Fiber Konjac Glucomannan Ameliorates Salmonella typhimurium-Induced Colonic Injury by Regulating TLR2-NF-κB Signaling and Intestinal Microbiota in Mice

This study aimed to investigate the hypothesis that dietary konjac glucomannan (KGM) could alleviate Salmonella typhimurium-induced colitis by modulating intestinal microbiota. Mice were fed an isocaloric and isofibrous diet supplemented with either 7% KGM or cellulose and were treated with 5 × 108 CFU of S. typhimurium. The results showed that KGM had an average molecular weight of 936 kDa and predominantly consisted of mannose and glucose at a molar ratio of 1:1.22. In vivo studies demonstrated that dietary KGM effectively mitigated colonic lesions, oxidative stress, disruption of tight junction protein 2 and occludin, and the inflammatory response induced by S. typhimurium. Moreover, KGM administration alleviated the dramatic upregulation of toll-like receptor 2 (TLR2) and phosphonuclear factor κB (NF-κB) protein abundance, induced by Salmonella treatment. Notably, dietary KGM restored the reduced Muribaculaceae and Lactobacillus abundance and increased the abundance of Blautia and Salmonella in S. typhimurium-infected mice. Spearman correlation analysis revealed that the gut microbiota improved by KGM contribute to inhibit inflammation and oxidative stress. These results demonstrated the protective effects of dietary KGM against colitis by modulating the gut microbiota and the TLR2-NF-κB signaling pathway in response to Salmonella infection.

Long-term supplementation of genistein improves immune homeostasis in the aged gut and extends the laying cycle of aged laying hens

Aging is associated with alterations in gut function, including intestinal inflammation, leaky gut, and impaired epithelial regeneration. Rejuvenating the aged gut is imperative to extend the laying cycle of aged laying hens. Genistein is known to have beneficial effects on age-related diseases, but its precise role in homeostasis of the aged gut of laying hens remains to be elucidated. In this study, 160 45-wk-old Hyline Brown laying hens were continuously fed a basal diet or a diet supplemented with 40 mg/kg genistein until they reached 100 wk of age. The results revealed that long-term genistein supplementation led to an improvement in the egg production rate and feed conversion ratio, as well as an increase in egg quality. Moreover, the expression levels of senescence markers, such as β-galactosidase, P16, and P21, were decreased in the gut of genistein-treated aged laying hens. Furthermore, genistein ameliorated gut dysfunctions, such as intestinal inflammation, leaky gut, and impaired epithelial regeneration. Treg cell-derived IL-10 plays a crucial role in the genistein-induced regulation of age-related intestinal inflammation. This study demonstrates that long-term consumption of genistein improves homeostasis in the aged gut and extends the laying cycle of aged laying hens. Moreover, the link between genistein and Treg cells provides a rationale for dietary intervention against age-associated gut dysfunction.

Dietary ethylenediamine dihydroiodide mitigated Escherichia coli O78-induced immune and intestinal damage of ducks via suppression of NF-κB signal

This study investigated the effect of Ethylenediamine dihydroiodide (EDDI) on growth performance, immune function and intestinal health of meat ducks challenged with Avian pathogenic Escherichia coli (APEC). A total of 360 one-day-old Cherry Valley ducks with similar body weight were randomly allocated to 6 treatments (6 floor cages, 10 birds/cage). A 3 × 2 factor design was used with 3 dietary iodine levels (0, 8, 16 mg/kg in the form EDDI and whether APEC was challenged or not at 7-day-old ducks. The feeding period lasted for 20 d. The results showed that the addition of EDDI reduced APEC-induced decrease of the 20-d weight loss of meat ducks (P < 0.05), and alleviated the inflammatory response of liver tissue induced by APEC challenge in meat ducks. In terms of immune function, EDDI supplementation reduced the immune organ index and increased the immune cell count of meat ducks, reduced the level of endotoxins in the serum of meat ducks (P < 0.05), as well as inhibited the expression levels of liver and spleen inflammatory factors and TLR signaling pathway related genes induced by APEC (P < 0.05). In terms of intestinal health, EDDI inhibited APEC-induced decreases in ZO-3 genes expression and increases in IL-1β and TNF-α expression, increased relative abundance of beneficial bacteria in the cecum and content of metabolites. Pearson correlation analysis showed that there was a significant correlation between liver inflammatory factors and TLR4 signaling pathway genes, and there might be a significant correlation between intestinal microbial flora and other physiological indexes of meat ducks, which indicated that EDDI could reduce the damage to immune function and intestinal health caused by APEC challenge through regulating the structure of intestinal flora. Collectively, our findings suggest that the EDDI can promote growth performance, improve immune function and the intestinal barrier in APEC-challenged meat ducks, which may be related to the suppression of NF-κB signal.

Short-term supplementation with uncoated and encapsulated Enterococcus faecium affected growth performance, gut microbiome and intestinal barrier integrity in broiler chickens

Enterococcus faecium (E. faecium) is an alternative to antibiotics, while the probiotic effect of short-term application in mature broiler chickens remains unclear. In the current study, 48 Arbor Acres male broilers were chosen to investigate the effects of E. faecium on growth performance, the gut microbiome and intestinal health during the finishing period. Forty-eight birds were randomly allocated to 4 treatment groups that were fed a corn-soybean meal basal diet (Con), a basal diet supplemented with 1 g/kg amoxicillin (ABX), 5×106 CFU/g encapsulated E. faecium (cEF), or 5×106 CFU/g uncoated E. faecium (EF) from d 33 to 42. The results showed that 10 d of antibiotic treatment decreased the growth performance of the broilers (P < 0.05). The feed conversion ratio of the cEF and EF groups were lower than that of the Con group by 0.13 and 0.07, respectively (P > 0.05). The abundance of viable ileal and cecal E. faecium in the cEF group was greater than that in the EF group (P < 0.05), and both groups were markedly greater than those in the Con and ABX groups (P < 0.05). The ABX treatment decreased the Shannon and Chao1 indices of the cecal microbiota, while the dietary E. faecium treatment resulted in significant differences in the β diversity of the ileal and cecal microbiota (P < 0.05). Mantel correlation revealed that the ileal microbiota at the genus level was significantly correlated with the growth performance of broilers, with Lactobacillus, Bacillus and Escherichia-Shigella showing positive and strong correlations (P < 0.05). In the ileum, the crypt depth was lower in the cEF group than in the Con group, but the villi height-to-crypt depth ratio was greater in the cEF group than in the other groups (P = 0.037). However, the expression of the ZO-2 and Occludin genes was downregulated in the E. faecium-fed birds (P < 0.05). In the cecum, the acetate, butyrate and total SCFA levels were greater in the EF group (P < 0.05), while the propionate, isobutyrate and isovalerate levels were lower in the ABX group (P < 0.05). In summary, 10 d of dietary supplementation with E. faecium markedly increased colonization in mature broilers and potentially improved growth performance by modulating the ileal microbiota. Encapsulation techniques could enable a slow release of E. faecium in the intestine, thereby reducing the negative impacts of rapid expansion of E. faecium on the intestinal epithelium.

Dietary pectin attenuates Salmonella typhimurium-induced colitis by modulating the TLR2-NF-κB pathway and intestinal microbiota in mice

The role of dietary pectin on microbial-induced colitis, oxidative status, barrier function, and microbial composition, as well as the underlying mechanisms, is scarce. In this study, we aimed to investigate whether dietary pectin alleviates Salmonella typhimurium-induced colitis in mice. Male C57BL/6J mice fed an isocaloric and isofibrous diet with 7% pectin or cellulose were administered sterile water or Salmonella typhimurium to induce colitis, which is equal to a human food dose of 0.57% (5.68 g/kg). Dietary pectin alleviated Salmonella typhimurium-induced colitis and oxidative stress as shown by the reduced disease activity index score, decreased colon shortening and histological damage score, colonic hydrogen peroxide, malondialdehyde concentrations, and relative mRNA expressions of coenzyme Q-binding protein COQ10 homologue B (Coq10b), Ccl-2, Ccl-3, Ccl-8, Tnf-α, Il-1β, Ifn-γ, Ifn-β, and serum TNF-α protein level. Moreover, pectin administration ameliorated the downregulated colonic abundances of occludin, zonula occludens-1, zonula occludens-2, and the upregulated abundances of TLR2 and p-NF-κB in Salmonella-infected mice. Additionally, 16S rRNA analysis demonstrated that pectin altered the microbial beta-diversity and reduced Salmonella levels. Collectively, pectin ameliorated Salmonella typhimurium-induced colitis, oxidative stress, and tight junction, which may be related to the inactivation of TLR2-NF-κB signalling and reduced abundance of Salmonella.

Dietary genistein increases microbiota-derived short chain fatty acid levels, modulates homeostasis of the aging gut, and extends healthspan and lifespan

Age-related gastrointestinal decline contributes to whole-organism frailty and mortality. Genistein is known to have beneficial effects on age-related diseases, but its precise role in homeostasis of the aging gut remains to be elucidated. Here, wild-type aging mice and Zmpste24^-/- progeroid mice were used to investigate the role of genistein in lifespan and homeostasis of the aging gut in mammals. A series of longitudinal, clinically relevant measurements were performed to evaluate the effect of genistein on healthspan. It was found that dietary genistein promoted a healthier and longer life and was associated with a decrease in the levels of systemic inflammatory cytokines in aging mice. Furthermore, dietary genistein ameliorated gut dysfunctions, such as intestinal inflammation, leaky gut, and impaired epithelial regeneration. A distinct genistein-mediated alteration in gut microbiota was observed by increasing Lachnospira abundance and short-chain fatty acid (SCFA) production. Further fecal microbiota transplantation and dirty cage sharing experiments indicated that the gut microbiota from genistein-fed mice rejuvenated the aging gut and extended the lifespan of progeroid mice. It was demonstrated that genistein-associated SCFAs alleviated tumor necrosis factor alpha-induced intestinal organoid damage. Moreover, genistein-associated propionate promoted regulatory T cell-derived interleukin 10 production, which alleviated macrophage-derived inflammation. This study provided the first data, to the authors' knowledge, indicating that dietary genistein modulates homeostasis in the aging gut and extends the healthspan and lifespan of aging mammals. Moreover, the existence of a link between genistein and the gut microbiota provides a rationale for dietary interventions against age-associated frailty.

The Effect of Genistein on Anastomotic Healing in Intestinal Ischemia/Reperfusion Injury

INTRODUCTION

Genistein is a natural isoflavonoid and has several pharmacological effects, such as antioxidant, antitumor activity, and improvement of glucose metabolism. The safety of intestinal anastomosis after ischemia-reperfusion (I/R) injury is a critical issue for surgeons. This experimental study aimed to investigate the effects of genistein on anastomotic healing after intestinal I/R injury.

METHODS

A total of 36 male Wistar Albino rats were divided into four groups: control, I/R, genistein, and genistein + I/R. The control group received segmental ileal resection and ileoileal anastomosis. The I/R group received resection + anastomosis after intestinal I/R. The genistein group was administered subcutaneous injection of 1 mg/kg genistein 12 h and 1 h before the procedure and received ileal resection + anastomosis. The genistein + I/R group received I/R + ileal resection + anastomosis after genistein injection. Anastomotic bursting pressure, hydroxyproline, superoxide dismutase, and glutathione peroxidase levels and histopathological wound healing scores of all rats were measured on postoperative day 5.

RESULTS

The anastomotic bursting pressure was significantly higher in the genistein and genistein + I/R groups (P < 0.001). Genistein increased the hydroxyproline concentration and the superoxide dismutase and glutathione peroxidase levels in the intestinal anastomosis (P < 0.001). In histopathological assessment, the mean wound healing score was significantly higher in the genistein group than in the other groups (P < 0.001).

CONCLUSIONS

Genistein, with its anti-inflammatory and antioxidant properties, shows protective effects against increased oxidative stress after intestinal I/R injury and contributes positively to intestinal anastomotic healing.

Pharmacological Effects of Polyphenol Phytochemicals on the Intestinal Inflammation via Targeting TLR4/NF-κB Signaling Pathway

TLR4/NF-κB is a key inflammatory signaling transduction pathway, closely involved in cell differentiation, proliferation, apoptosis, and pro-inflammatory response. Toll like receptor 4 (TLR4), the first mammalian TLR to be characterized, is the innate immune receptor that plays a key role in inflammatory signal transductions. Nuclear factor kappa B (NF-κB), the TLR4 downstream, is the key to accounting for the expression of multiple genes involved in inflammatory responses, such as pro-inflammatory cytokines. Inflammatory bowel disease (IBD) in humans is a chronic inflammatory disease with high incidence and prevalence worldwide. Targeting the TLR4/NF-κB signaling pathway might be an effective strategy to alleviate intestinal inflammation. Polyphenol phytochemicals have shown noticeable alleviative effects by acting on the TLR4/NF-κB signaling pathway in intestinal inflammation. This review summarizes the pharmacological effects of more than 20 kinds of polyphenols on intestinal inflammation via targeting the TLR4/NF-κB signaling pathway. We expected that polyphenol phytochemicals targeting the TLR4/NF-κB signaling pathway might be an effective approach to treat IBD in future clinical research applications.

Genistein accelerates glucose catabolism via activation the GPER-mediated cAMP/PKA-AMPK signaling pathway in broiler chickens

Genistein, the most abundance of phytoestrogens in soybeans, has beneficial effects in regulating metabolism-related disease; however, there is few available literatures about whether genistein regulates glucose metabolism that in turn affects the lipid accumulation in animals or humans. The current study showed that genistein promoted glucose uptake by enhancing glucose transporter-2 (GLUT2) protein level; and it also increased the activity of phosphofructokinase-1 (PFK) and pyruvate dehydrogenase (PDH), and the mRNA level of succinate dehydrogenase (SDH) both in broiler chickens or hepatocytes. Moreover, genistein obviously increased the p-LKB1 and p-AMPKα protein levels both in vivo and in vitro. Furthermore, the enhancement of genistein on glucose uptake and catabolism were reversed in hepatocytes pre-treated with AMPK inhibitor Compound C, and the increasing of genistein on the p-LKB1 and p-AMPKα protein levels were also reversed in hepatocytes pre-treated with PKA inhibitor H89. Importantly, the results showed that genistein simultaneously increased the estrogen receptor β (ERβ) and G protein-coupled estrogen receptor (GPER) protein levels, but the elevation effect of genistein on cAMP content was completely reversed in hepatocytes pre-treated with GPER antagonist G15, rather than ERβ inhibitor PHTPP. Meanwhile, the increasing of p-LKB1 and p-AMPKα protein levels induced by genistein were also reversed in hepatocytes pre-treated with G15. Collectively, our data demonstrated that genistein improves glucose metabolism via activating the GPER-mediated cAMP/PKA-AMPK signaling pathway. These findings provide theoretical basis for genistein as a promising nutritional supplemental to alleviate metabolism disorders and related diseases in animals or even humans.

Effect of Dietary Zinc Methionine Supplementation on Growth Performance, Immune Function and Intestinal Health of Cherry Valley Ducks Challenged With Avian Pathogenic Escherichia coli

This study was carried out to evaluate the effects of supplemental zinc methionine (Zn-Met) on growth performance, immune function, and intestinal health of meat ducks challenged with avian pathogenic Escherichia coli (APEC). A total of 480 1-day-old Cherry Valley male ducks were randomly assigned to 8 treatments with 10 replicates, each replicate containing 10 ducks. A 4 × 2 factor design was used with four dietary zinc levels (0, 30, 60, 120 mg Zn/kg in the form Zn-Met was added to the corn-soybean basal diet) and challenged with or without APEC at 8-days-old ducks. The trial lasted for 14 days. The results showed that a dietary Zn-Met supplementation significantly increased body weight (BW) of 14 days and BW gain, and decreased mortality during 7-14-days-old ducks (p < 0.05). Furthermore, dietary 30, 60, 120 mg/kg Zn-Met supplementation noticeably increased the thymus index at 2 days post-infection (2 DPI) and 8 DPI (p < 0.05), and 120 mg/kg Zn-Met enhanced the serum IgA at 2 DPI and IgA, IgG, IgM, C3 at 8 DPI (p < 0.05). In addition, dietary 120 mg/kg Zn-Met supplementation dramatically increased villus height and villus height/crypt depth (V/C) of jejunum at 2 DPI and 8 DPI (p < 0.05). The TNF-α and IFN-γ mRNA expression were downregulated after supplemented with 120 mg/kg Zn-Met in jejunum at 8 DPI (p < 0.05). Moreover, dietary 120 mg/kg Zn-Met supplementation stimulated ZO-3, OCLN mRNA expression at 2 DPI and ZO-2 mRNA expression in jejunum at 8 DPI (p < 0.05), and improved the MUC2 concentration in jejunum at 2 DPI and 8 DPI (p < 0.05). At the same time, the cecal Bifidobacterium and Lactobacillus counts were increased (p < 0.05), and Escherichia coli counts were decreased (p < 0.05) after supplemented with Zn-Met. In conclusion, inclusion of 120 mg/kg Zn-Met minimizes the adverse effects of APEC challenge on meat ducks by improving growth performance and enhancing immune function and intestinal health.

Genistein-based reactive oxygen species-responsive nanomaterial site-specifically relieves the intestinal toxicity of endocrine-disrupting chemicals

Endocrine-disrupting chemicals (EDCs) can disrupt the gastrointestinal endocrine system and induce oxidative stress, which eventually leads to intestinal toxicity. Genistein (Gen) has a beneficial effect on the physiological functions of the gastrointestinal tract and can alleviate EDCs damage. As an estrogen-like substance, Gen may also synergize the deleterious influence of EDCs. Therefore, the targeting and concentration of Gen must be controlled during its application. In this study, a novel reactive oxygen species (ROS)-responsive nanomaterial (Gen-NM-2) containing Tempol conjugated β-cyclodextrin and Gen was prepared. The nano-polymer exhibits a uniform rod-like morphology with an average diameter of 833±12 nm and a negative zeta-potential of -20.3±3.7 mV. Gen-NM-2 protected Gen from rapid metabolism in gastrointestinal tract and displayed a strong ROS scavenging ability. In response to high ROS levels, this material can effectively locate the target site and release Gen, which then exerted its effect by reducing the ROS content and regulating the ERβ signaling pathway. Owing to its high bioavailability, Gen-NM-2 at relatively low doses can reduce the intestinal cytotoxicity of EDCs, thus providing a basis for the development of EDCs detoxification therapy.

Intestinal Barrier in Human Health and Disease

The intestinal mucosa provides a selective permeable barrier for nutrient absorption and protection from external factors. It consists of epithelial cells, immune cells and their secretions. The gut microbiota participates in regulating the integrity and function of the intestinal barrier in a homeostatic balance. Pathogens, xenobiotics and food can disrupt the intestinal barrier, promoting systemic inflammation and tissue damage. Genetic and immune factors predispose individuals to gut barrier dysfunction, and changes in the composition and function of the gut microbiota are central to this process. The progressive identification of these changes has led to the development of the concept of ‘leaky gut syndrome’ and ‘gut dysbiosis’, which underlie the relationship between intestinal barrier impairment, metabolic diseases and autoimmunity. Understanding the mechanisms underlying this process is an intriguing subject of research for the diagnosis and treatment of various intestinal and extraintestinal diseases.

Dietary hydrolyzed wheat gluten supplementation ameliorated intestinal barrier dysfunctions of broilers challenged with Escherichia coli O78

This study aimed to investigate a protective effect of hydrolyzed wheat gluten (HWG) on Escherichia coli (E. coli)-induced intestinal barrier dysfunctions in broilers. Broilers fed a basal diet unsupplemented or supplemented with HWG (0.5% or 1%) were intraperitoneally injected with either E. coli O78 suspension (10⁸ CFU/mL) or equal volume of vehicle on d 18 of age. Blood and tissue samples were collected 3rd d post infection. The results showed that E. coli-infection increased immune-organ indexes of spleen and thymus, enhanced serum diamine oxidase (DAO) level, impaired ileal villus structure and reduced tight junction mRNA levels (Occludin, Claudin-1, ZO-1, P < 0.05), while increased mRNA levels of inflammatory cytokines (TNF-α, IFN-γ, IL-1β, IL-6, IL-8) and TLR4 in the ileum of broilers (P < 0.05). The effects of E. coli O78 challenge on organ indexes of spleen and thymus, serum DAO level, mRNA levels of tight junctions were alleviated by 1% HWG supplementation, the upregulations of IL-1β and TLR4 were prevented by 0.5% HWG supplementation (P < 0.05). In addition, increased IFN-γ of E. coli-infected broilers was abrogated by 0.5% or 1% HWG supplementation (P < 0.05). In summary, dietary HWG supplementation ameliorated intestinal barrier dysfunctions triggered by E. coli-infection in the ileum of broilers. HWG supplementation might be a nutritional strategy to improve the intestinal mucosal barrier function of broilers.

Gut relief formula attenuates dextran sulfate sodium-induced colitis by regulating NF-κB signaling and the intestinal microbiota in mice

Background. Inflammatory bowel disease (IBD) is a chronic relapsing disorder of the gastrointestinal tract. The nutrition care gut relief formula (GR), a combination of natural products and nutrients, has been shown to benefit gastrointestinal health. However, the underlying mechanism responsible for this effect is incompletely defined. Objective. This study was conducted to evaluate the hypothesis that GR could attenuate dextran sulfate sodium (DSS)-induced colitis by enhancing intestinal mucosal immunity and regulating intestinal microflora in mice. Methods. Six-week-old C57BL/6J mice orally administered with GR (7.5 mg per mouse per day) or an equal volume of vehicle were treated with sterile water or 2.5% DSS for 6 days to induce colitis. Histological damage, inflammatory cell infiltration, and colonic microbiome community were analyzed to evaluate the beneficial effect of GR. Results. GR administration ameliorated the severity of colitis as evidenced by reduced body weight loss, decreased colon shortening, reduced myeloperoxidase (MPO) activity, inhibited proinflammatory cytokine secretion, and decreased histological damage in DSS-challenged mice. Additionally, enhancement of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in response to DSS was attenuated by GR administration. Meanwhile, DSS treatment resulted in reduction of the glutathione (GSH) level and tight junction protein abundance, as compared with the controls. Of note, these adverse effects were remarkably eliminated by GR administration. Further study showed that the protective effect of GR was associated with the inhibited activation of STAT3 and NF-κB signaling pathways, as well as upregulated abundances of Lactobacillus in the colon tissues of mice. Conclusion. Collectively, the data provided herein demonstrated that GR administration alleviated intestinal mucosal inflammation and mucosal barrier dysfunction. These beneficial effects were associated with inhibited activation of STAT3 and NF-κB signaling pathways, as well as upregulated abundances of Lactobacillus in the colon tissues of mice.

Influence of Trans-anethole on the nutrient digestibility and intestinal barrier function in broilers

This experiment was undertaken to investigate the effects of dietary trans-anethole (TA) at 5 levels (0, 200, 400, 600, and 800 mg/kg of diet) on the growth performance, apparent nutrient digestibility and intestinal barrier function in broilers. Three hundred twenty 1-day-old Arbor Acres broilers were randomly divided into the 5 dietary treatments with 8 replicates each for 42 d. Dietary TA supplementation increased (P < 0.05) average daily feed intake (ADFI), but had no effects (P > 0.05) on average daily gain (ADG), feed/gain (F/G), and body weight (BW) of broilers throughout the entire experimental period. The apparent metabolizable energy (AME) and nitrogen-corrected apparent metabolizable energy (AMEn), the apparent total tract digestibility of dry matter (DM), crude protein (CP), organic matter (OM), and gross energy (GE) showed a quadratic increase (P < 0.05) with the increasing TA concentration in the diet. The apparent ileal digestibility of Lys, Met, Leu, Thr, Ala, Tyr, and Pro were higher (P < 0.05) in birds fed TA diets compared with control group. Dietary supplementation of 400 mg/kg of TA increased (P < 0.05) mRNA levels of jejunal and ileal Na+/glucose co-transporter (SGLT1) on d 21 and d 42, oligopeptide transporter 1 (PepT1) on d 42, and ileal mRNA expressions of occludin (OCLN), claudin-1 (CLDN-1), and mucin 2 (MUC2), villus height (VH), crypt depth (CD), and VH:CD on d 21, as well as jejunal zonula-occludens-1 (ZO-1) and ileal mucin 2 on d 42. Linear or quadratic responses of the jejunal CD and villus VH:CD ratio occurred (P < 0.01) with increasing dietary TA concentration on d 42. The inclusion of 400 mg/kg TA decreased (P < 0.05) cecal Escherichia coli population on d 21 and d 42, but increased (P < 0.05) Bifidobacterium population on d 21 and ileal Bifidobacterium on d 42. In conclusion, 400 mg/kg of TA is the optimum concentration for increasing nutrient utilization and intestinal barrier function of broilers.

A respiratory commensal bacterium acts as a risk factor for Mycoplasma gallisepticum infection in chickens

Commensal microbiota has been shown to play an important role in local infections. However, the correlation between host respiratory microbiota and Mycoplasma gallisepticum (MG) infection is not well characterized. Here, the results of 16S rRNA sequencing showed that MG infection correlated with alteration in respiratory microbiota of chickens characterized by decreased richness and diversity. To explore whether respiratory microbiota contributed to MG infection, an antibiotics cocktail was used to deplete respiratory microbiota. It has been found that depletion of respiratory Gram-positive and Gram-negative bacteria promoted MG infection, as reflected in the form of increased MG colonization, pro-inflammatory cytokines and proteins expression, and severe lung damage compared to the control group. Importantly, depletion of Gram-negative bacteria in respiratory tract mitigated MG infection, which indicated that certain Gram-negative bacteria may promote MG infection. By reconstitution of individual cultivable respiratory tract bacteria in antibiotic-treated chickens, a respiratory commensal microbe Serratia marcescens was identified to facilitate MG infection. We further found that Serratia marcescens may promote MG infection by downregulating Mucin 2 (MUC2) and tight junction related gene mRNA expression levels in trachea and lung tissues. Together, our data demonstrated that MG infection induced disturbed respiratory microbiota and the specific respiratory commensal bacterium Serratia marcescens could promote MG infection, and thus expand our understanding of the pathogenesis of MG infection.

Assessment of Probiotic Properties of Lactobacillus salivarius Isolated From Chickens as Feed Additives

The continued use of sub-therapeutic antibiotics as feed additives in the poultry industry improved health and growth performance. However, the resulting antibiotic resistance increasingly becomes a major threat to public health. Probiotics are promising alternatives for the antibiotics used in poultry industry. The aim of this study was to evaluate the probiotic properties of Lactobacillus salivarius as feed additive in chickens. White leghorn chickens were randomly assigned to experimental groups. Effects of Lactobacillus salivarius supplementation on growth performance, resistance to Escherichia coli O78 challenge and heat-stress, and immune response after vaccinated with attenuated infectious bursal disease virus (IBDV) vaccine were determined. The results showed that Lactobacillus salivarius supplementation improved growth performance, such as weight and longer shank length, increased relative weights of the immune organs and decreased concentrations of odor-causing compounds. In addition, Lactobacillus salivarius supplementation alleviated organ injury caused by Escherichia coli O78 challenge and heat stress. Furthermore, Lactobacillus salivarius results in enhanced immune response after IBDV vaccine immunization, enhanced specific antibody and IFN-γ production, and lymphocyte proliferation. Our results revealed a tremendous potential of Lactobacillus salivarius as antibiotics' substitute in poultry production.