谷氨酰胺对肠组织TLR2、4及NF-κB的调节与内毒素致肠损伤保护作用的关系

Glutamine protects against endotoxin-induced intestinal injury by down-regulating TLR4 and NF-κB expression in rats

目的:探讨谷氨酰胺对肠组织TLR2、4及NF-κB的调节与内毒素引起的肠损伤保护作用的关系.方法:24只日龄10d的Wistar幼鼠随机分为正常对照组(n=8),生理盐水1mL/kg腹腔注射;内毒素血症组(n=8),脂多糖组(lipopolysaccharide,LPS)(5g/L)5mg/kg腹腔注射;谷氨酰胺组(glutamine,Gln)(n=8),Gln10mL/kg(含谷氨酰胺13.46mg/100mL)+LPS5mg/kg腹腔注射.于腹腔注射后3h处死幼鼠,留取远端回肠组织,HE染色.光镜下观察肠组织病理改变,RT-PCR检测肠组织TLR2、4及NF-κBmRNA的表达,免疫组织化学检测肠组织TLR2、4及NF-κB蛋白定位表达.结果:光镜下对照组肠组织结构正常,Gln组和LPS组均可见间质和上皮细胞水肿,Gln组较LPS组明显减轻;肠组织TLR2、4及NF-κmRNA表达Gln组较LPS组明显下降(3.055±0.51vs4.09±0.90,3.92±0.50vs16.71±1.20.37±0.14vs2.23±0.72,均P<0.01),肠组织TLR4及NF-κB蛋白定位表达Gln组较LPS组明显降低(P<0.05).TLR2蛋白定位表达Gln组较NS组、LPS组均增强(P<0.01).结论:Gln减轻肠组织损伤的保护作用可能与其下调TLR4及NF-κBmRNA和蛋白的表达相关.

AIM： To investigate whether glutamine （Gln） exerts protective effects against endotoxin-induced intestinal injury in rats and to explore possible mechanisms involved. METHODS： Twenty-four 10-day-oId Wistar rats were equally and randomly divided into three groups： control group （intraperitoneally injected with normal saline 1 mL/kg）, lipopolysaccharide （LPS） group （intraperitoneally injected with LPS 5 g/L）, and Gln group （intraperitoneally injected with Gln 10 mL/kg and LPS 5 mg/kg）. Rats were sacrificed 3 h after injection. A segment of distal ileum was dissected. The pathologic changes in the small intestine were observed under an optical microscope after hematoxylin- eosin staining. The mRNA and protein expres- sion of TLR2/4 and NF-κB was detected by RT-PCR and immunohistochemistry, respectively RESULTS： The structure of the small intestine of rats in the control group was normal. Although inflammatory cell infiltration and interstitial and epithelial edema were observed in both the LPS group and Gln group, the pathological changes were significantly milder in the Gln group than in the LPS group. Compared to the LPS group, the mRNA and protein expression of TLR4 and NF-κB was significantly lower in the Gln group （TLR4：3.92± 0.50 vs 16.71± 1.28, 38.80 ± 2.42 vs 20.69 ±2.42; NF-κB： 0.37 ± 0.14 vs 2.23 ±0.72, 17.21 ± 5.07 vs 22.76 ± 3.68, P 〈 0.01, P 〈 0.05）. CONCLUSION： Gln exerts protective effects against intestinal injury in rats possibly by down- regulating TLR4 and NF-κB mRNA and protein expression.