亚麻籽油对脂多糖刺激仔猪肝脏Toll样受体4和核苷酸结合寡聚化结构域信号通路关键基因表达的影响

Effects of Flaxseed Oil on mRNA Expression of Key Genes in TLR4 and NOD Signaling Pathways in Liver of Piglets after LPS Challenge

本试验旨在研究亚麻籽油对脂多糖(LPS)刺激仔猪肝脏Toll样受体4(TLR4)和核苷酸结合寡聚化结构域(NOD)信号通路关键基因表达的影响。选取24头断奶仔猪,按体重相近原则随机分为4个组,分别为对照组、LPS组、2.5%亚麻籽油组(2.5%亚麻籽油+LPS)、5.0%亚麻籽油组(5.0%亚麻籽油+LPS),每组6个重复,每个重复1头猪,试验期21 d。试验组注射100μg/kg体重的LPS,对照组注射等量的生理盐水。注射LPS或生理盐水4 h后屠宰仔猪,取肝脏,测定TLR4和NOD信号通路关键基因及相关炎性介质的mRNA表达水平。结果表明:1)LPS刺激显著提高了肝脏肿瘤坏死因子-α(TNF-α)、环氧酶2(COX2)、热休克蛋白70(HSP70)的mRNA相对表达量(P<0.05),2.5%亚麻籽油可显著降低COX2、TNF-α的mRNA相对表达量(P<0.05),5.0%亚麻籽油可显著降低TNF-α的mRNA相对表达量(P<0.05)。2)LPS刺激显著提高了肝脏TLR4、髓样分化因子88(My D88)、白细胞介素-1受体相关激酶1(IRAK1)、NOD1、NOD2、受体互作蛋白2(RIPK2)、核因子-κB(NF-κB)的mRNA相对表达量(P<0.05);2.5%亚麻籽油可显著降低NOD1、NOD2的mRNA相对表达量(P<0.05),有降低RIPK2 mRNA相对表达量的趋势(0.05≤P<0.10);5.0%亚麻籽油可显著降低NOD2的mRNA相对表达量(P<0.05)。这表明LPS刺激导致仔猪发生炎症反应,亚麻籽油可能通过抑制NOD信号通路进而缓解肝脏炎症反应。

This experiment was conducted to investigate the effects of flaxseed oil on mRNA expression of key genes in Toll-like receptor 4（ TLR4） and nucleotide binding oligomerization domain protein（ NOD） signaling pathways in liver of piglets after lipopolysaccharide（ LPS） challenge. Twenty four pigs with similar body weight were randomly divided into 4 groups with 6 replicates per group and 1 pig per replicate,and the 4groups were control group,LPS group,2. 5 % flaxseed oil group（ 2. 5 % flaxseed oil ＋ LPS）,and 5. 0 %flaxseed oil group（ 5. 0 % flaxseed oil ＋ LPS）,respectively. The experiment lasted for 21 days. The pigs in the experimental groups were injected intraperitoneally with 100 μg / kg body weight LPS,whereas the pigs in the control group were injected with an equivalent amount of sterile saline. At 4 h post-challenge,the pigs were slaughtered and liver samples were collected. The mRNA expression levels of inflammatory cytokines and the key genes in TLR4 and NOD signaling pathways were detected by real-time PCR. The results showed as follows： 1） after LPS challenge,the mRNA relative expression levels of cyclo-oxygenase 2（ COX2）,heat shock protein 70（ HSP70） and tumor necrosis factor-α（ TNF-α） in liver were significantly increased（ P〈 0.05）. The mRNA relative expression levels of COX2 and TNF-α in 2. 5 % flaxseed oil group were significantly lower than those in LPS group（ P 〈0. 05）,and the TNF-α mRNA relative expression level in 5. 0 % flaxseed oil group was significantly lower than that in LPS group（ P 〈0. 05）. 2） After LPS challenge,the mRNA relative expression levels of TLR4,myeloid differentiation factor 88（ My D88）,interleukin-1 receptor-associated kinase 1（ IRAK1）,NOD1,NOD2,receptor-interacting serine / threonine-protein kinase 2（ RIPK2） and nuclear factor-κB（ NF-κB） in liver were significantly increased（ P〈 0. 05）. The mRNA relative expression levels of NOD1 and NOD2 in 2. 5 % flaxseed oil group were significantly lower than those in LPS group（ P〈 0.05）,and the mRNA relative expression level of RIPK2 had a tendency to decrease control to the LPS group（ 0. 05≤P 0. 10）. The mRNA relative expression level of NOD2 in 5. 0% flaxseed oil group was significantly lower than that in LPS group（ P〈 0. 05）. These results indicate that LPS challenge induces inflammatory response in piglets,flaxseed oil can alleviate liver inflammatory response via NOD signaling pathway inhibition.