表达Ⅰ型耐热肠毒素的重组大肠杆菌诱发仔猪小肠炎症的分子机制研究

doi:10.16431/j.cnki.1671-7236.2019.04.023

摘要/Abstract

摘要：

本试验旨在研究表达Ⅰ型耐热肠毒素（STa）的重组大肠杆菌诱发7日龄仔猪小肠炎症反应。选取24头7日龄健康仔猪，随机分为4个处理组：对照组（人工乳）、STa组（人工乳+2×10⁹ CFU重组菌LMG194-pBAD-STa）、LMG194组（人工乳+2×10⁹ CFU大肠杆菌LMG194）和K88组（人工乳+2×10⁹ CFU大肠杆菌K88），每组6头。试验第5天进行攻毒，第7天屠宰取样，观察空肠组织形态学变化，并检测血清中炎性细胞因子含量及空肠免疫相关基因的相对表达量。结果显示，与对照组相比，STa与K88组仔猪空肠绒毛明显萎缩变短，有明显损伤甚至脱落；STa、LMG194及K88组血清中IL-10、IL-8和IL-6浓度均显著升高（P<0.05），LMG194和K88组血液和肠道iFABP浓度均显著降低（P<0.05），STa和K88组血清中TNF-α浓度显著降低、NF-κB浓度显著升高，LMG194组NF-κB浓度显著降低、TNF-α浓度显著升高（P<0.05）；STa和LMG194组CCL2和CXCL9基因表达水平显著上调（P<0.05），VNN1基因表达水平显著下调（P<0.05），STa和LMG194组IFN-γ组基因水平分别显著上升和下降（P<0.05）；K88组CXCL9和IFN-γ基因表达水平显著下调（P<0.05），VNN1基因表达水平显著上调（P>0.05），CCL2基因表达水平无明显差异（P>0.05）。以上结果表明，表达Ⅰ型耐热肠毒素STa的重组大肠杆菌几乎具有与K88一样的毒性，可导致7日龄仔猪小肠黏膜受损，诱发严重的炎症反应，导致仔猪腹泻，可作为仔猪腹泻模型的候选菌株。

关键词: 耐热肠毒素(STa); 重组大肠杆菌; 仔猪; 炎症

Abstract:

This experiment was conducted to investigate the effects of recombinant E.coli expressing heat-stable enterotoxin (STa) on jejunum inflammation of 7 days old piglets.Twenty-four 7 days old piglets were allotted to four treatments:Control group (artificial milk),STa group (artificial milk+2×10⁹ CFU E.coli LMG194-pBAD-STa),LMG194 group (artificial milk+2×10⁹ CFU E.coli LMG194),and K88 group (artificial milk+2×10⁹ CFU E.coli K88),six piglets each group.The pigs were treated with E.coli on the 5th day and slaughtered on the 7th day.The results showed that compared with control group,the jejunum villi of STa and K88 groups were significantly atrophied and shortened with obvious damage or even falling off.Compared with control group,the concentrations of IL-10,IL-8 and IL-6 in the serum of STa,LMG194 and K88 groups were significantly increased (P<0.05),and the concentrations of iFABP in the blood and intestinal tract of LMG194 and K88 groups were significantly decreased (P<0.05);The concentrations of TNF-α in serum of STa and K88 groups were significantly decreased,the concentration of NF-κB was significantly increased (P<0.05);The concentration of NF-κB in LMG194 group was significantly decreased,and the concentration of TNF-α was significantly increased (P<0.05).Compared with control group,the expression levels of CCL2 and CXCL9 genes in STa and LMG194 groups were significantly up-regulated (P<0.05),and the expression level of VNN1 gene was significantly down-regulated (P<0.05),the expression level of IFN-γ in STa and LMG194 groups was significantly increased and decreased,respectively (P<0.05);The expression of CXCL9 and IFN-γ genes was significantly down-regulated in K88 group (P<0.05),and the expression level of VNN1 gene was significantly up-regulated (P>0.05).There was no significant difference in CCL2 gene expression level (P>0.05).These results suggested that recombinant E.coli expressing type Ⅰ heat-stable enterotoxin STa was almost as toxic as E.coli K88,which could cause damage to intestinal mucosa of 7-day-old piglets,induce serious inflammatory reaction,lead to diarrhea in piglets,and could be used as a candidate strain for piglet diarrhea model.

Key words: heat-stable enterotoxin (STa); recombinant E.coli; piglets; inflammation

中图分类号:

S858.28

李雪妮, 史宇涛, 杜林晓, 吕阳, 马志鹏, 易丹, 王蕾, 赵迪, 侯永清, 吴涛. 表达Ⅰ型耐热肠毒素的重组大肠杆菌诱发仔猪小肠炎症的分子机制研究[J]. 《中国畜牧兽医》, 2019, 46(4): 1151-1157.

LI Xueni, SHI Yutao, DU Linxiao, LYU Yang, MA Zhipeng, YI Dan, WANG Lei, ZHAO Di, HOU Yongqing, WU Tao. Study on Molecular Mechanism of Intestinal Inflammation in Piglets Induced by Recombinant Escherichia coli Expressing Type Ⅰ Heat-stable Enterotoxin[J]. , 2019, 46(4): 1151-1157.

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