Liu Zi-Yan, Yang Hong-Ling, Li Sha, Cai Guo-He, Ye Ji-Dan, Zhang Chun-Xiao, Sun Yun-Zhang
The Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, 361021, China.
The Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Fisheries College, Jimei University, Xiamen, 361021, China; Xiamen Key Laboratory for Feed Quality Testing and Safety Evaluation, Fisheries College, Jimei University, Xiamen, 361021, China.
Fish Shellfish Immunol. 2023 Oct;141:109010. doi: 10.1016/j.fsi.2023.109010. Epub 2023 Aug 19.
β-conglycinin is a recognized factor in leading to intestinal inflammation and limiting application of soybean meal in aquaculture. Our previous study reported that heat-killed B. siamensis LF4 could effectively mitigate inflammatory response and apoptosis caused by β-conglycinin in spotted seabass (Lateolabrax maculatus) enterocytes, but the mechanisms involved are not fully understood. In the present study, therefore, whole cell wall (CW), peptidoglycan (PG) and lipoteichoic acid (LTA) and cell-free supernatant (CFS) have been collected from B. siamensis LF4 and their mitigative function on β-conglycinin-induced adverse impacts and mechanisms underlying were evaluated. The results showed that β-conglycinin-induced cell injury, characterized with significantly decreased cell viability and increased activities of lactate dehydrogenase, glutamic oxaloacetic transaminase, glutamic propylic transaminase (P < 0.05), were reversed by subsequent heat-killed B. siamensis LF4 and its CW, LTA, PG and CFS treatment. Enterocytes co-cultured with heat-killed B. siamensis LF4 and its CW, LTA, PG and CFS (especially PG) significantly increased expressions of anti-inflammatory genes (IL-2, IL-4, IL-10 and TGF-β1), tight junction proteins (ZO-1, occludin and claudin-b) and antimicrobial peptides (β-defensin, hepcidin-1, NK-lysin and piscidin-5), and decreased expressions of pro-inflammatory genes (IL-1β, IL-8 and TNF-α) and apoptosis-related genes (caspase 3, caspase 8 and caspase 9) (P < 0.05), indicating their excellent mitigation effects on β-conglycinin-induced cell damages. In addition, heat-killed B. siamensis LF4 and its CW, LTA, PG and CFS significantly increased TLR2 mRNA level (especially in PG treatment), and decreased MAPKs (JNK, ERK, p38 and AP-1) and NF-κB related genes expressions. In conclusion, heat-killed B. siamensis LF4 and its CW, LTA, PG and CFS could modulating TLR2/MAPKs/NF-κB signaling and alleviating β-conglycinin-induced enterocytes injury in spotted seabass (L. maculatus), and PG presented the best potential.
β-伴大豆球蛋白是导致肠道炎症并限制豆粕在水产养殖中应用的一个公认因素。我们之前的研究报道，热灭活的暹罗芽孢杆菌LF4可有效减轻β-伴大豆球蛋白对斑鲈（Lateolabrax maculatus）肠细胞造成的炎症反应和细胞凋亡，但其中涉及的机制尚未完全明确。因此，在本研究中，我们从暹罗芽孢杆菌LF4中收集了全细胞壁（CW）、肽聚糖（PG）、脂磷壁酸（LTA）和无细胞上清液（CFS），并评估了它们对β-伴大豆球蛋白诱导的不利影响的缓解作用及其潜在机制。结果表明，β-伴大豆球蛋白诱导的细胞损伤，表现为细胞活力显著降低以及乳酸脱氢酶、谷草转氨酶、谷丙转氨酶活性增加（P < 0.05），随后经热灭活的暹罗芽孢杆菌LF4及其CW、LTA、PG和CFS处理后得到了逆转。与热灭活的暹罗芽孢杆菌LF4及其CW、LTA、PG和CFS（尤其是PG）共培养的肠细胞显著增加了抗炎基因（IL-2、IL-4、IL-10和TGF-β1）、紧密连接蛋白（ZO-1、闭合蛋白和claudin-b）和抗菌肽（β-防御素、铁调素-1、NK-溶素和杀鱼菌素-5）的表达，并降低了促炎基因（IL-1β、IL-8和TNF-α）和凋亡相关基因（caspase 3、caspase 8和caspase 9）的表达（P < 0.05），表明它们对β-伴大豆球蛋白诱导的细胞损伤具有良好的缓解作用。此外，热灭活的暹罗芽孢杆菌LF4及其CW、LTA、PG和CFS显著增加了TLR2 mRNA水平（尤其是在PG处理组），并降低了MAPKs（JNK、ERK、p38和AP-1）和NF-κB相关基因的表达。总之，热灭活的暹罗芽孢杆菌LF4及其CW、LTA、PG和CFS可调节TLR2/MAPKs/NF-κB信号通路，减轻β-伴大豆球蛋白诱导的斑鲈（L. maculatus）肠细胞损伤，且PG表现出最佳潜力。
