表达Ⅰ型耐热肠毒素的重组大肠杆菌对7日龄仔猪肠道免疫、屏障及抗氧化功能的影响

Effects of Recombinant Escherichia coli Expressing Heat-stable Enterotoxin on Intestinal Immune and Barrier Function and Antioxidant Capacity of Seven Days Old Piglets

旨在研究表达Ⅰ型耐热肠毒素(STa)的重组大肠杆菌对7日龄仔猪肠道吸收、屏障、转运及抗氧化功能的影响。选取24头7日龄仔猪,分成4个处理组,分别为对照组(基础日粮)、STa组(基础日粮+2×109 CFU重组菌LMG194-STa)、LMG194组(基础日粮+2×109 CFU大肠杆菌LMG194)和K88组(基础日粮+2×109 CFU大肠杆菌K88)。使用人工乳饲养,第5天进行攻毒,第7天屠宰取样。测量回肠免疫相关基因IFN-γ、IL-4与VNN1及回肠黏膜损伤基因Villin与MMP3的相对转录量,空肠黏膜上皮连接蛋白Occludin与Claudin-1相对表达量,以及十二指肠、回肠氧化相关酶谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)的活力与氧化相关产物丙二醛(MDA)的含量。试验结果表明,与对照组相比,STa组显著降低了回肠IFN-γ和IL-4基因相对转录量,VNN1相对转录量显著上调(P<0.05);STa组显著降低了基因Villin与MMP3相对转录量(P<0.05)及蛋白Occludin与Claudin-1相对表达量(P<0.05);同时,STa组十二指肠、回肠GSH-Px和回肠MPO活力显著降低(P<0.05);STa组十二指肠丙二醛(MDA)含量显著升高(P<0.05)。结果显示,表达Ⅰ型耐热肠毒素的重组大肠杆菌可导致7日龄仔猪肠道免疫、屏障及抗氧化功能下降。

This experiment was conducted to investigate the effects of recombinant escherichia coli expressing heat-stable enterotoxin （STa） on intestinal immune and barrier function and antioxi- dant capacity of 7 days old piglets. Twenty-four 7 days old piglets were allotted to four treat- ments： control group, STa group （2× 109 CFU E. coli LMG194-STa）, LMG194 group （2×109 CFU E. coli LMG194）, and K88 group （2× 109 CFU E. coli K88）. The pigs were fed with artificial milk and slaughtered 7 days later. The result showed that, compared with the control group, STa group significantly reduced IFN-γ and IL-4 gene transcription levels （P〈0.05）, and increased VNN1 transcription level in ileum （P〈0. 05）. STa group also significantly reduced gene transcription levels of Villin and MMP3 in ileum （P〈0.05） and protein expression levels of Occludin and Claudin-1 in jejunum （P〈0.05）. STa group significantly reduced activity of gluta- thione peroxidase （GSH-Px） in duodenum and ileum （P〈0.05）, and significantly reduced activity of myeloperoxidase （MPO） in ileum （P〈0.05）, and had a higher production of malondialdehyde （MDA） in duodenum （P〈0.05）. These results suggest that recombinant Escherichia coli expressing STa can reduce intestinal immune and barrier function and antioxidant capacity of 7 days old piglets.