GPR109A介导的猪肠上皮屏障功能调控的分子机制

Several studies have shown that weaning has a deleterious impact on intestinal barrier function in the piglets resulting in increased intestinal permeability and inflammation. G protein coupled receptor 109A (GPR109A) which was also named HCA2 were wildly expressed in adipose tissue, immune cells, epidermal cells and epithelia which provide potential involvement in intestinal barrier regulation. The objective of the present study was to determine the effect of GPR109A activation in regulating intestinal barrier function in early weaning piglets. Western blotting, real-time PCR, ELISA, cell co-culture will be used to explore the relativity between the GPR109A system and the intestinal barrier function, to study the influences and mechanism of GPR109A activation on intestinal permeability, tight junction protein expression and Epithelia apoptosis. Molecular mechanism involved in the process will be further investigated. These results will provide scientific basis to further understand the regulatory mechanism in intestinal barrier function, which will provide potential target and new ideas in treatment of post weaning diarrhea in piglets.

仔猪断奶腹泻是影响仔猪肠道健康及制约养猪业发展的主要因素。腹泻往往伴随着肠道炎症的加剧和肠道屏障的损伤。饲料中填加丁酸钠，对于缓解仔猪断奶腹泻具有一定作用，但其机制尚不完全清楚。丁酸可以激活GPR109A，GPR109A属于烟酸受体，β-羟丁酸被认为是GPR109A的内源性配体，烟酸、丁酸被认为是其外源性配体。GPR109A在断奶仔猪肠道呈现怎样的变化，其是否介导对仔猪肠道上皮细胞屏障功能的调控，目前未见相关报道。本研究拟通过早期断奶诱导仔猪腹泻模型和体外细胞培养方法，探讨早期断奶仔猪肠道内GPR109A的变化规律，观测β-羟基丁酸、丁酸钠对于猪原代肠上皮细胞屏障作用的影响，检测GPR109A下游相关信号通路的活化情况，探讨GPR109A介导的肠屏障功能调控的间接途径。以期阐明GPR109A在肠道屏障调控中的作用机制，为揭示仔猪断奶腹泻发生机理和寻找潜在治疗靶点提供实验依据。

仔猪断奶腹泻是影响仔猪肠道健康及制约养猪业发展的重要因素。腹泻往往伴随着肠道炎症的加剧和肠道屏障的损伤。饲料中填加丁酸钠，对于缓解仔猪断奶腹泻具有一定作用，但其机制尚不完全清楚。丁酸可以激活GPR109A，发挥抑制炎症的作用。本研究旨在通过在体和细胞实验，观测GPR109A在断奶仔猪肠道的变化规律，探讨其介导仔猪肠道机械屏障、免疫屏障、化学屏障、生物屏障的影响及分子机制。以期为阐明揭示仔猪断奶腹泻发生机理和寻找潜在治疗靶点提供实验依据。. 结果证实，（1）猪AMP010014A09基因编码猪GPR109A，饲料中填加丁酸钠能够显著降低断奶仔猪的腹泻频率和腹泻指数，抑制断奶仔猪肠道局部炎症；（2）丁酸钠能够通过激活GPR109A和Akt信号通路，提高结肠上皮细胞紧密连接蛋白分子的表达。（3）通过化学诱导及外科手术诱导的肠道通透性破坏动物模型，验证了丁酸钠通过GPR109A抑制炎性细胞因子的产生，进而改善了屏障功能受损所致的紧密连接蛋白表达减少和化学屏障、微生物屏障的破坏，从而对化学性结肠炎和实验性败血症动物模型发挥保护作用。研究结果为全面揭示GPR109A在动物肠道健康及屏障维持中的作用提供了丰富的实验数据，圆满完成了本课题研究内容。