ABSTRACT
Objective@#To investigate the effects of Lactobacillus paracasei N1115 combined with fructooligosaccharides (FOS) on non-alcoholic fatty liver disease (NAFLD) in mice and its possible mechanism.@*Methods@#A total of 50 male C57 mice were randomly and equally divided into five experimental groups. Group 1 received a normal diet (ND). Other four groups received a high-fat diet (HFD) to establish NAFLD models. In addition to HFD, group 3 received Lactobacillus paracasei N1115 (2.2×109 CFU/mL), group 4 received FOS (4 g/kg per day), and group 5 received Lactobacillus paracasei N1115 (2.2×109 CFU/mL) and FOS (4 g/kg per day). All groups received continuous intervention for 16 weeks. The following indices were measured for all groups after intervention: general condition, the levels of fasting blood glucose, insulin, and lipopolysaccharide (LPS), and the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and interferon (IFN)-γ in the serum and liver. The mRNA levels of Toll-like receptor (TLR)4, nuclear factor (NF)-κb, insulin receptor (InsR), and insulin receptor substrate (IRS)-1 were measured by real-time RT-PCR. The data were subjected to one-way analysis of variance and comparison between groups was made by Bonferroni method.@*Results@#Compared with group 2, groups 3, 4, and 5 had significantly lower body weight, Lee's index, liver index, and the levels of blood glucose and insulin resistance (P < 0.05). The serum level of LPS in group 2 was significantly higher than that in the other experimental groups (group 1: 8.80 ± 0.85 U/L, group 3: 12.31 ± 1.01 U/L, group 4: 12.27 ± 0.98 U/L, and group 5: 10.17 ± 0.79 U/L vs group 2: 15.45 ± 1.14 U/L, F = 55.117, P < 0.001). The levels of TNF-α, IL-1β, IL-6, and IFN-γ in the serum and liver in group 2 were also significantly higher than those in the other groups (P < 0.05). Group 2 had significantly higher mRNA levels of TLR4 and NF-κb in the liver than the other groups (F = 82.933, P < 0.001; F = 149.033, P < 0.001); however, it had significantly lower mRNA levels of InsR and IRS-1 in the liver than the other groups (F = 33.347, P < 0.001; F = 70.225, P < 0.001).@*Conclusion@#Lactobacillus paracasei N1115 combined with FOS can reduce the level of LPS in the blood circulation, inhibit activation of the LPS/TLR4 signaling pathway, and reduce the release of inflammatory factor and the body's insulin resistance, so it can relieve NAFLD.
ABSTRACT
Objective To investigate the effectiveness of Lactobacillus paracasei N1115 combined with fructooligosaccharides (FOS) in the treatment of nonalcoholic fatty liver disease(NAFLD) in a mouse model and to analyze the possible mechanism.Methods Fifty male C57BL/6 mice were randomly divided into five groups and respectively given normal diet (ND group), high-fat diet (HFD group), HFD containing Lactobacillus paracasei N1115 (HFD+L) (2.2×109 CFU/ml), HFD containing FOS (HFD+FOS) (4 g/kg per day) and HFD containing Lactobacillus paracasei N1115 and FOS for 16 consecutive weeks.Levels of triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), lipopolysaccharide (LPS) and diamine oxidase (DAO) in serum samples from each group were measured.Expression of tight-junction proteins (Claudin-1 and Occludin), p38 and phosphorylated p38 (p-p38) in intestinal tissues were analyzed.Results Compared with the HFD group, the HFD+FOS+L group showed decreased levels of TC, TG, LDL, LPS and DAO in serum samples, but increased serum HDL level (P<0.05).Moreover, combined treatment with Lactobacillus paracasei N1115 and FOS alleviated liver lipid deposition, significantly increased the expression of Claudin-1 and Occludin in intestine and inhibited the phosphorylation of p38 (P<0.05).Conclusion Lactobacillus paracasei N1115 combined with FOS may increase the expression of Claudin-1 and Occludin through inhibiting the phosphorylation of intestinal p38, which is conducive to maintaining the intestinal mucosal barrier integrity and alleviating NAFLD.
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Objective To investigate that butyrate-producing probiotic clostridium butyricum improves the intestinal epithelial barrier function in food allergic mice by regulating TWIK-related potassium channel-1 (Trek1) expression in intestinal epithelial cells.Methods An intestinal allergy mouse model was created,then the model construction effect was verified by detecting the related indicators by ELISA,flow cytometer.The change of small intestinal tissue permeability was detected by the Ussing chambers.The Trek1 expressions in mouse jejunum tissue in control group and allergy group were detected by Western blot and immunofluorescent method;in the Transwell system,T84 cells were used to establish epithelial cellular monolayer for exposing to the allergic mediators,the Trek1 mRNA and protein expression were detected by qRT-PCR and Western blot.Then the allergic mice were grouped and treated by different methods including normal saline,SIT,SIT/SB,SB,SIT/CB,CB,SIT/CB/Spadin,the expression of mice intestinal Trek1,intestinal barrier function and allergic reaction indicators were detected.Results Compared with the control group,the small intestinal Trek1 protein and tissue expression level in the food allergic mice were significantly decreased,the intestinal mucosal permeability was significantly increased,the differences were statistically significant(P＜0.05);after T84 cells exposing to the allergic mediators,Trek1 mRNA and protein expression were significantly decreased(P＜0.05),but adding p38 inhibitor in advance could antagonize this change;the single use of SIT,clostridium butyricum and sodium butyrate could increase the intestinal Trek1 expression in food allergic mice,and alleviated the allergic reaction(P＜0.05),whereas the combined use of SIT and clostridium butyricum or sodium butyrate had more significant effect(compared with the SIT group,P＜0.05),moreover could significantly decrease small intestinal mucosal permeability and improved the intestinal barrier function(P＜0.05).Conclusion Sodium butyrate or butyrate-producing probiotic clostridium butyricum can restore the intestinal barrier function,alleviates the allergic reaction and strengthens the SIT curative effect in allergic mice by increasing Trek1 expression.
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Objective To investigate the effects of two cholesterol-lowering probiotics, DM9054 (Lac-tobacillus Rhamnosus GG, LGG) in combination with 86066 (Lactobacillus plantarum WCFS1, LP), on the metabolism of bile acid via a rat model of non-alcoholic fatty liver disease (NAFLD) and the possible mecha-nism. Methods Twenty-one SD male rats were randomly divided into three groups including control group, NAFLD model group and probiotics intervention group. Rats in the control group received normal diet. The rat model of NAFLD was established by feeding rats with chronic high fat diet (45% of calories derived from fat di-et) for 20 weeks. Rats in the probiotics intervention group were given high fat diet together with cholesterol-low-ering probiotics through oral gavage. General indexes of each group including body weight and the levels of tri-glyceride, cholesterol and CK18-M30 in serums samples were detected. The expression of cholesterol 7-alpha hydroxy-lase (CYP7A1), fibroblast growth factor receptor 4 (FGFR4), farnesoid X receptor (FXR), fibroblast grwoth factor 15 (FGF15) and apical sodium-dependent bile acid transparter(ASBT) at mRNA level were de-tected by using real-time polymerase chain reaction (real-time PCR). Western blot assay was used to detect the protein expression of CYP7A1, FXR in liver tissues and ASBT in ileum tissues. The expression of FXR in liver and ileum tissues were analyzed by immunohistochemistry. Results Rats with NAFLD showed loss of body weight and decreased levels of the serological markers after treating with the probiotics (P0. 05). Conclusion Probiotics intervention might up-regulate the expression of CYP7A1 by suppressing the FXR path-way in liver tissues and inhibiting the expression of ASBT in ileum tissues. Treating NAFLD rats with cholester-ol-lowering probiotics could activate the FXR-FGF15 pathway in ileum tissues and enhance the metabolism of bile acid, which contributed to the alleviation of NAFLD.
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Objective To analyze the roles and mechanisms of lactitol and Bifidobacterium infantis in the treatment of rat constipation and to investigate their effects on aquaporin3 (AQP3) and interstitial cells of Cajal (ICC) in colon tissues.Methods Thirty SD male rats were recruited in this study,6 of which were randomly selected as the control and the rest were given 4 mg/kg.d of loperamide for 5 consecutive days to construct the rat model of constipation.The rats with constipation were randomly divided into four groups including model group,lactitol treatment group,Bifidobacterium infantis treatment group and lactitol in combination with Bifidobacterium infantis treatment group.General indexes including food intake,water intake,body weight,fecal water content and intestinal transit rate of each rat were measured after receiving corresponding treatments for 7 consecutive days.The levels of substance P (SP) and vasoactive intestinal peptide (VIP) in serums samples were detected by ELISA.The expression of protein kinase A (PKA) and neurokinin-1 receptor (NK-1) at mRNA level in colon tissues were detected by real-time polymerase chain reaction (real-time PCR).Western blot assay and real-time PCR analysis were used to detect the expression of AQP3 and c-kit at protein and mRNA levels,respectively.Results Compared with the rats in model group,the levels of fecal water content and intestinal transit rate,the concentrations of SP and VIP in serums samples,the expression of PKA and NK-1 at mRNA level and the expression of AQP3 and c-kit at mRNA and protein levels were significantly increased in rats from the three treatment groups (P＜0.05).The most effective treatment was lactitol in combination with Bifidobacterium infantis,followed by the lactitol treatment and then the Bifidobacterium infantis treatment.Conclusion The combination therapy with lactitol and Bifidobacterium infantis increased the serum levels of SP and VIP in rats with constipation.SP could enhance the contraction of gastrointestinal smooth muscles and improve the intestinal motility by binding to the NK-1 receptor on the membrane of ICC.VIP could promote the absorption of water in intestinal tracts,soften stools and alleviate constipation by upregulating the expression of AQP3 at both protein and mRNA levels via the cyclic adenosine monophosphate-PKA (cAMP-PKA) signaling pathway.