BIOMIN Research Center, Technopark 1, 3430 Tulln an der Donau, Austria.
Toxins (Basel). 2020 Sep 29;12(10):622. doi: 10.3390/toxins12100622.
Lipopolysaccharides (LPS), also termed endotoxins, are the major component of the outer membrane of Gram-negative bacteria. In general, endotoxins in the intestine are considered harmless in healthy animals. However, different stressors, such as heat stress, can lead to a compromised gut barrier, resulting in endotoxin translocation. Chickens are considered to be less sensitive to the effects of LPS compared with other species, for example, humans, pigs, or calves, probably because of the lack of the functional-specific TRAM-TRIF signalling pathway (MyD88-independent). Therefore, six LPS preparations (three different strains with two different preparation methods each) were compared in murine macrophages and characterized according to their MyD88-dependent pathway activation. All tested LPS preparations induced a strong inflammatory response after 4 and 24 h on a murine macrophage cell line. However, there was a similar strong response in the gene expression profile as well as production of nitrite oxide and TNF-alpha from LPS of different strains and preparation methods. On the basis of the results of the in vitro study, one LPS preparation was chosen for the subsequent in vivo study with broilers to assess the effect of an oral LPS bolus ( O55:B5 phenol extracted; 2 mg/kg b.w.) during heat stress conditions (10 h, 36 °C). The most pronounced effects were seen in broilers receiving the oral LPS bolus during heat stress conditions. The endotoxin activity in the intestine as well as the serum concentration of the 3-OH C14 (part of LPS) were increased. In addition, an increased expression of genes related to inflammation and stress response (e.g., IL-6, IL-1beta, HSP70) was observed, whereas the expression of genes associated with gut health (e.g., MUC2, FABP2) was decreased. To conclude, an increase of intestinal LPS combined with heat stress can pose a risk to animal health.
脂多糖（LPS），也称为内毒素，是革兰氏阴性菌外膜的主要成分。一般来说，健康动物肠道内的内毒素是无害的。然而，不同的应激源，如热应激，会导致肠道屏障受损，导致内毒素易位。与其他物种相比，鸡被认为对内毒素的影响不敏感，例如人类、猪或小牛，可能是因为缺乏功能性特定的 TRAM-TRIF 信号通路（MyD88 非依赖性）。因此，在鼠巨噬细胞中比较了六种 LPS 制剂（三种不同菌株，每种两种不同的制备方法），并根据其 MyD88 依赖性途径激活进行了表征。所有测试的 LPS 制剂在鼠巨噬细胞系上 4 和 24 小时后均诱导强烈的炎症反应。然而，不同菌株和制备方法的 LPS 基因表达谱以及亚硝酸盐和 TNF-α的产生均有类似的强烈反应。基于体外研究的结果，选择一种 LPS 制剂用于随后的肉鸡体内研究，以评估在热应激条件（10 小时，36°C）下口服 LPS 冲击（O55:B5 酚提取；2mg/kg b.w.）的效果。在接受热应激条件下口服 LPS 冲击的肉鸡中，观察到最明显的效果。肠道内的内毒素活性以及血清中 3-OH C14（LPS 的一部分）的浓度均增加。此外，观察到与炎症和应激反应相关的基因（例如 IL-6、IL-1β、HSP70）的表达增加，而与肠道健康相关的基因（例如 MUC2、FABP2）的表达减少。总之，肠道 LPS 的增加与热应激相结合可能对动物健康构成风险。
