Alginate oligosaccharide-induced intestinal morphology, barrier function and epithelium apoptosis modifications have beneficial effects on the growth performance of weaned pigs
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摘要
Background: Alginate oligosaccharide(AOS), produced from alginate by alginate lyase-mediated depolymerisation, is a potential substitute for antibiotics and possesses growth-enhancing effects. Nevertheless, the mechanisms by which AOS regulates porcine growth remain to be elucidated. Therefore, we investigated the AOS-mediated changes in the growth performance of weaned pigs by determining the intestinal morphology, barrier function,as well as epithelium apoptosis.Methods: Twenty-four weaned pigs were distributed into two groups(n = 12) and received either a basal diet(control group) or the same diet supplemented with 100 mg/kg AOS. On d 15, D-xylose(0.1 g/kg body weight)was orally administrated to eight randomly selected pigs per treatment, and their serum and intestinal mucosa samples were collected 1 h later.Results: Our results showed that inclusion of AOS in the diet for 2 wk increased(P < 0.05) the average daily body weight gain in weaned pigs. Notably, AOS supplementation ameliorated the intestinal morphology and barrier function, as suggested by the enhanced(P < 0.05) intestinal villus height, secretory immunoglobulin A content and goblet cell counts. Compared to the control group, AOS ingestion both decreased(P < 0.05) the total apoptotic percentage and increased(P < 0.05) the proportion of S phase in the intestinal epithelial cells. Furthermore, AOS not only up-regulated(P < 0.05) the B-cell lymphoma-2(BCL2) transcriptional level but also down-regulated(P < 0.05) the B-cell lymphoma-2-associated X protein(BAX), cysteinyl aspartate-specific proteinase-3(caspase-3) and caspase-9 transcriptional levels in the small intestine.Conclusions: In summary, this study provides evidence that supplemental AOS beneficially affects the growth performance of weaned pigs, which may result from the improved intestinal morphology and barrier function,as well as the inhibited enterocyte death, through reducing apoptosis via mitochondria-dependent apoptosis.
Background: Alginate oligosaccharide(AOS), produced from alginate by alginate lyase-mediated depolymerisation, is a potential substitute for antibiotics and possesses growth-enhancing effects. Nevertheless, the mechanisms by which AOS regulates porcine growth remain to be elucidated. Therefore, we investigated the AOS-mediated changes in the growth performance of weaned pigs by determining the intestinal morphology, barrier function,as well as epithelium apoptosis.Methods: Twenty-four weaned pigs were distributed into two groups(n = 12) and received either a basal diet(control group) or the same diet supplemented with 100 mg/kg AOS. On d 15, D-xylose(0.1 g/kg body weight)was orally administrated to eight randomly selected pigs per treatment, and their serum and intestinal mucosa samples were collected 1 h later.Results: Our results showed that inclusion of AOS in the diet for 2 wk increased(P < 0.05) the average daily body weight gain in weaned pigs. Notably, AOS supplementation ameliorated the intestinal morphology and barrier function, as suggested by the enhanced(P < 0.05) intestinal villus height, secretory immunoglobulin A content and goblet cell counts. Compared to the control group, AOS ingestion both decreased(P < 0.05) the total apoptotic percentage and increased(P < 0.05) the proportion of S phase in the intestinal epithelial cells. Furthermore, AOS not only up-regulated(P < 0.05) the B-cell lymphoma-2(BCL2) transcriptional level but also down-regulated(P < 0.05) the B-cell lymphoma-2-associated X protein(BAX), cysteinyl aspartate-specific proteinase-3(caspase-3) and caspase-9 transcriptional levels in the small intestine.Conclusions: In summary, this study provides evidence that supplemental AOS beneficially affects the growth performance of weaned pigs, which may result from the improved intestinal morphology and barrier function,as well as the inhibited enterocyte death, through reducing apoptosis via mitochondria-dependent apoptosis.
Background: Alginate oligosaccharide(AOS), produced from alginate by alginate lyase-mediated depolymerisation, is a potential substitute for antibiotics and possesses growth-enhancing effects. Nevertheless, the mechanisms by which AOS regulates porcine growth remain to be elucidated. Therefore, we investigated the AOS-mediated changes in the growth performance of weaned pigs by determining the intestinal morphology, barrier function,as well as epithelium apoptosis.Methods: Twenty-four weaned pigs were distributed into two groups(n = 12) and received either a basal diet(control group) or the same diet supplemented with 100 mg/kg AOS. On d 15, D-xylose(0.1 g/kg body weight)was orally administrated to eight randomly selected pigs per treatment, and their serum and intestinal mucosa samples were collected 1 h later.Results: Our results showed that inclusion of AOS in the diet for 2 wk increased(P < 0.05) the average daily body weight gain in weaned pigs. Notably, AOS supplementation ameliorated the intestinal morphology and barrier function, as suggested by the enhanced(P < 0.05) intestinal villus height, secretory immunoglobulin A content and goblet cell counts. Compared to the control group, AOS ingestion both decreased(P < 0.05) the total apoptotic percentage and increased(P < 0.05) the proportion of S phase in the intestinal epithelial cells. Furthermore, AOS not only up-regulated(P < 0.05) the B-cell lymphoma-2(BCL2) transcriptional level but also down-regulated(P < 0.05) the B-cell lymphoma-2-associated X protein(BAX), cysteinyl aspartate-specific proteinase-3(caspase-3) and caspase-9 transcriptional levels in the small intestine.Conclusions: In summary, this study provides evidence that supplemental AOS beneficially affects the growth performance of weaned pigs, which may result from the improved intestinal morphology and barrier function,as well as the inhibited enterocyte death, through reducing apoptosis via mitochondria-dependent apoptosis.
引文
1.Kim JC,Hansen CF,Mullan BP,Pluske JR.Nutrition and pathology of weaner pigs:nutritional strategies to support barrier function in the gastrointestinal tract.Anim Feed Sci Technol.2012;173:3-16.
2.Smith F,Clark JE,Overman BL,Tozel CC,Huang JH,Rivier JE,et al.Early weaning stress impairs development of mucosal barrier function in the porcine intestine.Am J Physiol Gastrointest Liver Physiol.2010;298:G352-G63.
3.Boudry G,Péron V,Le Hu?rou-Luron I,Lallès JP,Sève B.Weaning induces both transient and long-lasting modifications of absorptive,secretory,and barrier properties of piglet intestine.J Nutr.2004;134:2256-62.
4.Hu CH,Song ZH,Xiao K,Song J,Jiao LF,Ke YL.Zinc oxide influences intestinal integrity,the expressions of genes associated with inflammation and TLR4-myeloid differentiation factor 88 signaling pathways in weanling pigs.Innate Immun.2014;20:478-86.
5.Yin J,Wu MM,Xiao H,Ren WK,Duan JL,Yang G,et al.Development of an antioxidant system after early weaning in piglets.J Anim Sci.2014;92:612-9.
6.Zhu LH,Zhao KL,Chen XL,Xu JX.Impact of weaning and an antioxidant blend on intestinal barrier function and antioxidant status in pigs.J Anim Sci.2012;90:2581-9.
7.Yang HS,Xiong X,Wang XC,Li TJ,Yin YL.Effects of weaning on intestinal crypt epithelial cells in piglets.Sci Rep.2016;6:36939.
8.Wan J,Li Y,Chen DW,Yu B,Zheng P,Mao XB,et al.Expression of a tandemly arrayed plectasin gene from Pseudoplectania nigrella in Pichia pastoris and its antimicrobial activity.J Microbiol Biotechnol.2016;26:461-8.
9.Yin XX,Song FJ,Gong YH,Tu XC,Wang YX,Cao SY,et al.A systematic review of antibiotic utilization in China.J Antimicrob Chemother.2013;68:2445-52.
10.Gill EE,Franco OL,Hancock REW.Antibiotic adjuvants:diverse strategies for controlling drug-resistant pathogens.Chem Biol Drug Des.2015;85:56-78.
11.Liu P,Piao XS,Kim SW,Wang L,Shen YB,Lee HS,et al.Effects of chitooligosaccharide supplementation on the growth performance,nutrient digestibility,intestinal morphology,and fecal shedding of and in weaning pigs.J Anim Sci.2008;86:2609-18.
12.Wu Y,Pan L,Shang QH,Ma XK,Long SF,Xu YT,et al.Effects of isomaltooligosaccharides as potential prebiotics on performance,immune function and gut microbiota in weaned pigs.Anim Feed Sci Technol.2017;230:126-35.
13.Ruvinov E,Cohen S.Alginate biomaterial for the treatment of myocardial infarction:progress,translational strategies,and clinical outlook:from ocean algae to patient bedside.Adv Drug Deliver Rev.2016;96:54-76.
14.Lu JJ,Yang H,Hao J,Wu CL,Liu L,Xu NY,et al.Impact of hydrolysis conditions on the detection of mannuronic to guluronic acid ratio in alginate and its derivatives.Carbohydr Polym.2015;122:180-8.
15.Guo JJ,Ma LL,Shi HT,Zhu JB,Wu J,Ding ZW,et al.Alginate oligosaccharide prevents acute doxorubicin cardiotoxicity by suppressing oxidative stress and endoplasmic reticulum-mediated apoptosis.Mar Drugs.2016;14:231.
16.Wang P,Jiang XL,Jiang YH,Hu XK,Mou HJ,Li M,et al.In vitro antioxidative activities of three marine oligosaccharides.Nat Prod Res.2007;21:646-54.
17.Tusi SK,Khalaj L,Ashabi G,Kiaei M,Khodagholi F.Alginate oligosaccharide protects against endoplasmic reticulum-and mitochondrial-mediated apoptotic cell death and oxidative stress.Biomaterials.2011;32:5438-58.
18.Zhou R,Shi XY,Gao Y,Cai N,Jiang ZD,Xu X.Anti-inflammatory activity of guluronate oligosaccharides obtained by oxidative degradation from alginate in lipopolysaccharide-activated murine macrophage RAW 264.7cells.J Agric Food Chem.2015;63:160-8.
19.Yang Y,Ma ZH,Yang GK,Wan J,Li GJ,Du LJ,et al.Alginate oligosaccharide indirectly affects toll-like receptor signaling via the inhibition of microrna-29b in aneurysm patients after endovascular aortic repair.Drug Des Devel Ther.2017;11:2565-79.
20.Wan J,Zhang J,Chen DW,Yu B,He J.Effects of alginate oligosaccharide on the growth performance,antioxidant capacity and intestinal digestion-absorption function in weaned pigs.Anim Feed Sci Technol.2017;234:118-27.
21.National Research Council.Nutrient requirements of swine.11th ed.Washington,DC:National Academics Press;2012.
22.Hou YQ,Wang L,Zhang W,Yang ZG,Ding BY,Zhu HL,et al.Protective effects of N-acetylcysteine on intestinal functions of piglets challenged with lipopolysaccharide.Amino Acids.2012;43:1233-42.
23.Wan J,Li Y,Chen DW,Yu B,Chen G,Zheng P,et al.Recombinant plectasin elicits similar improvements in the performance and intestinal mucosa growth and activity in weaned pigs as an antibiotic.Anim Feed Sci Technol.2016;211:216-26.
24.Chen H,Mao XB,He J,Yu B,Huang ZQ,Yu J,et al.Dietary fibre affects intestinal mucosal barrier function and regulates intestinal bacteria in weaning piglets.Br J Nutr.2013;110:1837-48.
25.Fang TT,Liu GM,Cao W,Wu XJ,Jia G,Zhao H,et al.Spermine:new insights into the intestinal development and serum antioxidant status of suckling piglets.RSC Adv.2016;6:31323-35.
26.Cao W,Liu GM,Fang TT,Wu XJ,Jia G,Zhao H,et al.Effects of spermine on the morphology,digestive enzyme activities,and antioxidant status of jejunum in suckling rats.RSC Adv.2015;5:76607-14.
27.Yu ZQ,Wang FY,Liang N,Wang CH,Peng X,Fang J,et al.Effect of selenium supplementation on apoptosis and cell cycle blockage of renal cells in broilers fed a diet containing aflatoxin B1.Biol Trace Elem Res.2015;168:242-51.
28.Haag D,Goerttler K,Tschahargane C.The proliferative index(PI)of human breast cancer as obtained by flow cytometry.Pathology-Research and Practice.1984;178:315-22.
29.Wan J,Jiang F,Zhang J,Xu QS,Chen DW,Yu B,et al.Amniotic fluid metabolomics and biochemistry analysis provides novel insights into the diet-regulated foetal growth in a pig model.Sci Rep.2017;7:44782.
30.Livak KJ,Schmittgen TD.Analysis of relative gene expression data using real-time quantitative PCR and the 2-ΔΔCtmethod.Methods.2001;25:402-8.
31.Montagne L,Boudry G,Favier C,Le Hu?rou-Luron I,Lallès JP,Sève B.Main intestinal markers associated with the changes in gut architecture and function in piglets after weaning.Br J Nutr.2007;97:45-57.
32.Hu CH,Xiao K,Luan ZS,Song J.Early weaning increases intestinal permeability,alters expression of cytokine and tight junction proteins,and activates mitogen-activated protein kinases in pigs.J Anim Sci.2013;91:1094-101.
33.Montagne L,Pluske JR,Hampson DJ.A review of interactions between dietary fibre and the intestinal mucosa,and their consequences on digestive health in young non-ruminant animals.Anim Feed Sci Technol.2003;108:95-117.
34.Wijtten PJ,van der Meulen J,Verstegen MW.Intestinal barrier function and absorption in pigs after weaning:a review.Br J Nutr.2011;105:967-81.
35.Pluske JR,Hampson DJ,Williams IH.Factors influencing the structure and function of the small intestine in the weaned pig:a review.Livest Prod Sci.1997;51:215-36.
36.Wan J,Jiang F,Xu QS,Chen DW,He J.Alginic acid oligosaccharide accelerates weaned pig growth through regulating antioxidant capacity,immunity and intestinal development.RSC Adv.2016;6:87026-35.
37.Hou YQ,Wang L,Ding BY,Liu YL,Zhu HL,Liu J,et al.Dietaryα-ketoglutarate supplementation ameliorates intestinal injury in lipopolysaccharide-challenged piglets.Amino Acids.2010;39:555-64.
38.Moeser AJ,Ryan KA,Nighot PK,Blikslager AT.Gastrointestinal dysfunction induced by early weaning is attenuated by delayed weaning and mast cell blockade in pigs.Am J Physiol Gastrointest Liver Physiol.2007;293:G413-G1.
39.McLamb BL,Gibson AJ,Overman EL,Stahl C,Moeser AJ.Early weaning stress in pigs impairs innate mucosal immune responses to enterotoxigenic E coli challenge and exacerbates intestinal injury and clinical disease.PLoSOne.2013;8:e59838.
40.Wan J,Jiang F,Xu QS,Chen DW,Yu B,Huang ZQ,et al.New insights into the role of chitosan oligosaccharide in enhancing growth performance,antioxidant capacity,immunity and intestinal development of weaned pigs.RSC Adv.2017;7:9669-79.
41.Yang CM,Ferket PR,Hong QH,Zhou J,Cao GT,Zhou L,et al.Effect of chitooligosaccharide on growth performance,intestinal barrier function,intestinal morphology and cecal microflora in weaned pigs.J Anim Sci.2012;90:2671-6.
42.Corthésy B.Role of secretory immunoglobulin a and secretory component in the protection of mucosal surfaces.Future Microbiol.2010;5:817-29.
43.Keren DF.Intestinal mucosal immune defense mechanisms.Am J Surg Pathol.1988;12:100-5.
44.Lamont JT.Mucus:the front line of intestinal mucosal defense.Ann N YAcad Sci.1992;664:190-201.
45.McCauley HA,Guasch G.Three cheers for the goblet cell:maintaining homeostasis in mucosal epithelia.Trends Mol Med.2015;21:492-503.
46.Linden SK,Sutton P,Karlsson NG,Korolik V,McGuckin MA.Mucins in the mucosal barrier to infection.Mucosal Immunol.2008;1:183-97.
47.Günther C,Neumann H,Neurath MF,Becker C.Apoptosis,necrosis and necroptosis:cell death regulation in the intestinal epithelium.Gut.2013;62:1062-71.
48.Zhu LH,Cai X,Guo Q,Chen XL,Zhu SW,Xu JX.Effect of N-acetyl cysteine on enterocyte apoptosis and intracellular signalling pathways'response to oxidative stress in weaned piglets.Br J Nutr.2013;110:1938-47.
49.Zhu LH,Xu JX,Zhu SW,Cai X,Yang SF,Chen XL,et al.Gene expression profiling analysis reveals weaning-induced cell cycle arrest and apoptosis in the small intestine of pigs.J Anim Sci.2014;92:996-1006.
50.Ghobrial IM,Witzig TE,Adjei AA.Targeting apoptosis pathways in cancer therapy.CA Cancer J Clin.2005;55:178-94.
51.Hockenbery D,Nu?ez G,Milliman C,Schreiber RD,Korsmeyer SJ.Bcl-2 is an inner mitochondrial membrane protein that blocks programmed cell death.Nature.1990;348:334-6.
52.Reed JC,Miyashita T,Takayama S,Wang HG,Sato T,Krajewski S,et al.BCL-2family proteins:regulators of cell death involved in the pathogenesis of cancer and resistance to therapy.J Cell Biochem.1996;60:23-32.
53.Zapata JM,Pawlowski K,Haas E,Ware CF,Godzik A,Reed JC.A diverse family of proteins containing tumor necrosis factor receptor-associated factor domains.J Biol Chem.2001;276:24242-52.
54.Elmore S.Apoptosis:a review of programmed cell death.Toxicol Pathol.2007;35:495-516.
55.Riedl SJ,Shi Y.Molecular mechanisms of caspase regulation during apoptosis.Nat Rev Mol Cell Biol.2004;5:897-907.
2.Smith F,Clark JE,Overman BL,Tozel CC,Huang JH,Rivier JE,et al.Early weaning stress impairs development of mucosal barrier function in the porcine intestine.Am J Physiol Gastrointest Liver Physiol.2010;298:G352-G63.
3.Boudry G,Péron V,Le Hu?rou-Luron I,Lallès JP,Sève B.Weaning induces both transient and long-lasting modifications of absorptive,secretory,and barrier properties of piglet intestine.J Nutr.2004;134:2256-62.
4.Hu CH,Song ZH,Xiao K,Song J,Jiao LF,Ke YL.Zinc oxide influences intestinal integrity,the expressions of genes associated with inflammation and TLR4-myeloid differentiation factor 88 signaling pathways in weanling pigs.Innate Immun.2014;20:478-86.
5.Yin J,Wu MM,Xiao H,Ren WK,Duan JL,Yang G,et al.Development of an antioxidant system after early weaning in piglets.J Anim Sci.2014;92:612-9.
6.Zhu LH,Zhao KL,Chen XL,Xu JX.Impact of weaning and an antioxidant blend on intestinal barrier function and antioxidant status in pigs.J Anim Sci.2012;90:2581-9.
7.Yang HS,Xiong X,Wang XC,Li TJ,Yin YL.Effects of weaning on intestinal crypt epithelial cells in piglets.Sci Rep.2016;6:36939.
8.Wan J,Li Y,Chen DW,Yu B,Zheng P,Mao XB,et al.Expression of a tandemly arrayed plectasin gene from Pseudoplectania nigrella in Pichia pastoris and its antimicrobial activity.J Microbiol Biotechnol.2016;26:461-8.
9.Yin XX,Song FJ,Gong YH,Tu XC,Wang YX,Cao SY,et al.A systematic review of antibiotic utilization in China.J Antimicrob Chemother.2013;68:2445-52.
10.Gill EE,Franco OL,Hancock REW.Antibiotic adjuvants:diverse strategies for controlling drug-resistant pathogens.Chem Biol Drug Des.2015;85:56-78.
11.Liu P,Piao XS,Kim SW,Wang L,Shen YB,Lee HS,et al.Effects of chitooligosaccharide supplementation on the growth performance,nutrient digestibility,intestinal morphology,and fecal shedding of and in weaning pigs.J Anim Sci.2008;86:2609-18.
12.Wu Y,Pan L,Shang QH,Ma XK,Long SF,Xu YT,et al.Effects of isomaltooligosaccharides as potential prebiotics on performance,immune function and gut microbiota in weaned pigs.Anim Feed Sci Technol.2017;230:126-35.
13.Ruvinov E,Cohen S.Alginate biomaterial for the treatment of myocardial infarction:progress,translational strategies,and clinical outlook:from ocean algae to patient bedside.Adv Drug Deliver Rev.2016;96:54-76.
14.Lu JJ,Yang H,Hao J,Wu CL,Liu L,Xu NY,et al.Impact of hydrolysis conditions on the detection of mannuronic to guluronic acid ratio in alginate and its derivatives.Carbohydr Polym.2015;122:180-8.
15.Guo JJ,Ma LL,Shi HT,Zhu JB,Wu J,Ding ZW,et al.Alginate oligosaccharide prevents acute doxorubicin cardiotoxicity by suppressing oxidative stress and endoplasmic reticulum-mediated apoptosis.Mar Drugs.2016;14:231.
16.Wang P,Jiang XL,Jiang YH,Hu XK,Mou HJ,Li M,et al.In vitro antioxidative activities of three marine oligosaccharides.Nat Prod Res.2007;21:646-54.
17.Tusi SK,Khalaj L,Ashabi G,Kiaei M,Khodagholi F.Alginate oligosaccharide protects against endoplasmic reticulum-and mitochondrial-mediated apoptotic cell death and oxidative stress.Biomaterials.2011;32:5438-58.
18.Zhou R,Shi XY,Gao Y,Cai N,Jiang ZD,Xu X.Anti-inflammatory activity of guluronate oligosaccharides obtained by oxidative degradation from alginate in lipopolysaccharide-activated murine macrophage RAW 264.7cells.J Agric Food Chem.2015;63:160-8.
19.Yang Y,Ma ZH,Yang GK,Wan J,Li GJ,Du LJ,et al.Alginate oligosaccharide indirectly affects toll-like receptor signaling via the inhibition of microrna-29b in aneurysm patients after endovascular aortic repair.Drug Des Devel Ther.2017;11:2565-79.
20.Wan J,Zhang J,Chen DW,Yu B,He J.Effects of alginate oligosaccharide on the growth performance,antioxidant capacity and intestinal digestion-absorption function in weaned pigs.Anim Feed Sci Technol.2017;234:118-27.
21.National Research Council.Nutrient requirements of swine.11th ed.Washington,DC:National Academics Press;2012.
22.Hou YQ,Wang L,Zhang W,Yang ZG,Ding BY,Zhu HL,et al.Protective effects of N-acetylcysteine on intestinal functions of piglets challenged with lipopolysaccharide.Amino Acids.2012;43:1233-42.
23.Wan J,Li Y,Chen DW,Yu B,Chen G,Zheng P,et al.Recombinant plectasin elicits similar improvements in the performance and intestinal mucosa growth and activity in weaned pigs as an antibiotic.Anim Feed Sci Technol.2016;211:216-26.
24.Chen H,Mao XB,He J,Yu B,Huang ZQ,Yu J,et al.Dietary fibre affects intestinal mucosal barrier function and regulates intestinal bacteria in weaning piglets.Br J Nutr.2013;110:1837-48.
25.Fang TT,Liu GM,Cao W,Wu XJ,Jia G,Zhao H,et al.Spermine:new insights into the intestinal development and serum antioxidant status of suckling piglets.RSC Adv.2016;6:31323-35.
26.Cao W,Liu GM,Fang TT,Wu XJ,Jia G,Zhao H,et al.Effects of spermine on the morphology,digestive enzyme activities,and antioxidant status of jejunum in suckling rats.RSC Adv.2015;5:76607-14.
27.Yu ZQ,Wang FY,Liang N,Wang CH,Peng X,Fang J,et al.Effect of selenium supplementation on apoptosis and cell cycle blockage of renal cells in broilers fed a diet containing aflatoxin B1.Biol Trace Elem Res.2015;168:242-51.
28.Haag D,Goerttler K,Tschahargane C.The proliferative index(PI)of human breast cancer as obtained by flow cytometry.Pathology-Research and Practice.1984;178:315-22.
29.Wan J,Jiang F,Zhang J,Xu QS,Chen DW,Yu B,et al.Amniotic fluid metabolomics and biochemistry analysis provides novel insights into the diet-regulated foetal growth in a pig model.Sci Rep.2017;7:44782.
30.Livak KJ,Schmittgen TD.Analysis of relative gene expression data using real-time quantitative PCR and the 2-ΔΔCtmethod.Methods.2001;25:402-8.
31.Montagne L,Boudry G,Favier C,Le Hu?rou-Luron I,Lallès JP,Sève B.Main intestinal markers associated with the changes in gut architecture and function in piglets after weaning.Br J Nutr.2007;97:45-57.
32.Hu CH,Xiao K,Luan ZS,Song J.Early weaning increases intestinal permeability,alters expression of cytokine and tight junction proteins,and activates mitogen-activated protein kinases in pigs.J Anim Sci.2013;91:1094-101.
33.Montagne L,Pluske JR,Hampson DJ.A review of interactions between dietary fibre and the intestinal mucosa,and their consequences on digestive health in young non-ruminant animals.Anim Feed Sci Technol.2003;108:95-117.
34.Wijtten PJ,van der Meulen J,Verstegen MW.Intestinal barrier function and absorption in pigs after weaning:a review.Br J Nutr.2011;105:967-81.
35.Pluske JR,Hampson DJ,Williams IH.Factors influencing the structure and function of the small intestine in the weaned pig:a review.Livest Prod Sci.1997;51:215-36.
36.Wan J,Jiang F,Xu QS,Chen DW,He J.Alginic acid oligosaccharide accelerates weaned pig growth through regulating antioxidant capacity,immunity and intestinal development.RSC Adv.2016;6:87026-35.
37.Hou YQ,Wang L,Ding BY,Liu YL,Zhu HL,Liu J,et al.Dietaryα-ketoglutarate supplementation ameliorates intestinal injury in lipopolysaccharide-challenged piglets.Amino Acids.2010;39:555-64.
38.Moeser AJ,Ryan KA,Nighot PK,Blikslager AT.Gastrointestinal dysfunction induced by early weaning is attenuated by delayed weaning and mast cell blockade in pigs.Am J Physiol Gastrointest Liver Physiol.2007;293:G413-G1.
39.McLamb BL,Gibson AJ,Overman EL,Stahl C,Moeser AJ.Early weaning stress in pigs impairs innate mucosal immune responses to enterotoxigenic E coli challenge and exacerbates intestinal injury and clinical disease.PLoSOne.2013;8:e59838.
40.Wan J,Jiang F,Xu QS,Chen DW,Yu B,Huang ZQ,et al.New insights into the role of chitosan oligosaccharide in enhancing growth performance,antioxidant capacity,immunity and intestinal development of weaned pigs.RSC Adv.2017;7:9669-79.
41.Yang CM,Ferket PR,Hong QH,Zhou J,Cao GT,Zhou L,et al.Effect of chitooligosaccharide on growth performance,intestinal barrier function,intestinal morphology and cecal microflora in weaned pigs.J Anim Sci.2012;90:2671-6.
42.Corthésy B.Role of secretory immunoglobulin a and secretory component in the protection of mucosal surfaces.Future Microbiol.2010;5:817-29.
43.Keren DF.Intestinal mucosal immune defense mechanisms.Am J Surg Pathol.1988;12:100-5.
44.Lamont JT.Mucus:the front line of intestinal mucosal defense.Ann N YAcad Sci.1992;664:190-201.
45.McCauley HA,Guasch G.Three cheers for the goblet cell:maintaining homeostasis in mucosal epithelia.Trends Mol Med.2015;21:492-503.
46.Linden SK,Sutton P,Karlsson NG,Korolik V,McGuckin MA.Mucins in the mucosal barrier to infection.Mucosal Immunol.2008;1:183-97.
47.Günther C,Neumann H,Neurath MF,Becker C.Apoptosis,necrosis and necroptosis:cell death regulation in the intestinal epithelium.Gut.2013;62:1062-71.
48.Zhu LH,Cai X,Guo Q,Chen XL,Zhu SW,Xu JX.Effect of N-acetyl cysteine on enterocyte apoptosis and intracellular signalling pathways'response to oxidative stress in weaned piglets.Br J Nutr.2013;110:1938-47.
49.Zhu LH,Xu JX,Zhu SW,Cai X,Yang SF,Chen XL,et al.Gene expression profiling analysis reveals weaning-induced cell cycle arrest and apoptosis in the small intestine of pigs.J Anim Sci.2014;92:996-1006.
50.Ghobrial IM,Witzig TE,Adjei AA.Targeting apoptosis pathways in cancer therapy.CA Cancer J Clin.2005;55:178-94.
51.Hockenbery D,Nu?ez G,Milliman C,Schreiber RD,Korsmeyer SJ.Bcl-2 is an inner mitochondrial membrane protein that blocks programmed cell death.Nature.1990;348:334-6.
52.Reed JC,Miyashita T,Takayama S,Wang HG,Sato T,Krajewski S,et al.BCL-2family proteins:regulators of cell death involved in the pathogenesis of cancer and resistance to therapy.J Cell Biochem.1996;60:23-32.
53.Zapata JM,Pawlowski K,Haas E,Ware CF,Godzik A,Reed JC.A diverse family of proteins containing tumor necrosis factor receptor-associated factor domains.J Biol Chem.2001;276:24242-52.
54.Elmore S.Apoptosis:a review of programmed cell death.Toxicol Pathol.2007;35:495-516.
55.Riedl SJ,Shi Y.Molecular mechanisms of caspase regulation during apoptosis.Nat Rev Mol Cell Biol.2004;5:897-907.