姜黄素通过肠道菌群调节Treg/Th17平衡改善脊髓损伤

Curcumin ameliorates spinal cord injury by regulating the Treg/Th17 balance via gut microbiota

摘要:

目的 脊髓损伤后引发的免疫炎症反应是阻碍神经功能恢复的关键因素。近期研究表明，肠道菌群紊乱可通过“肠-脊髓轴”参与中枢神经系统的免疫调控。本研究旨在探讨姜黄素能否通过重塑肠道菌群，调节脊髓局部Treg/Th17平衡，从而发挥对脊髓损伤的保护作用。方法 将200-220 g左右的雌性Sprague-Dawley (SD)大鼠随机分为假手术组、脊髓损伤组、姜黄素组、粪菌移植组、粪菌移植姜黄素组、粪菌移植姜黄素+GPRs抑制剂组。通过Basso-Beattie-Bresnahan (BBB)运动功能评分和步态分析评估神经功能恢复情况；采用苏木精-伊红染色、尼氏染色和劳克坚牢蓝染色观察损伤区域的组织病理学变化；运用实时荧光定量逆转录PCR检测、酶联免疫吸附测定和蛋白印迹分析，检测各组脊髓中Treg细胞关键转录因子FOXP3、抗炎因子IL-10和TGF-β1，以及Th17细胞关键转录因子RORγt、促炎因子IL-17和IL-6的表达情况。结果 与脊髓损伤组和粪菌移植组相比，姜黄素组和粪菌移植姜黄素组大鼠的神经功能改善最为显著，具体表现为BBB运动功能评分和步态协调性显著提升，同时脊髓组织损伤范围明显缩小。在分子水平上，这2组脊髓组织中FOXP3、IL-10和TGF-β1的基因和蛋白表达显著上调，而RORγt、IL-17A和IL-6的表达则被显著抑制，这提示姜黄素干预肠道菌群后免疫平衡向Treg主导的抗炎状态倾斜。值得注意的是，联合使用GPRs抑制剂后，姜黄素修饰菌群带来的上述有益效应被逆转。结论 本研究表明，姜黄素干预后的肠道菌群能够有效促进脊髓损伤后的运动功能恢复，其作用机制可能与激活GPRs信号通路，上调Treg细胞活性、抑制Th17细胞分化，最终纠正Treg/Th17免疫失衡密切相关。这为将姜黄素及其修饰后的肠道菌群作为脊髓损伤的辅助治疗策略提供了新的实验依据和应用价值。

Abstract:

Objective The immunoinflammatory response induced by spinal cord injury is a key factor hindering the recovery of neurological functions. Recent studies have shown that gut microbiota dysbiosis can participate in the immune regulation of the central nervous system through the gut-spinal cord axis. This study aims to explore whether curcumin can exert its protective effect on spinal cord injury by reshaping the gut microbiota and thereby regulating the local Treg/Th17 balance in the spinal cord.Methods Female Sprague-Dawley rats weighing 200?220 g were randomly assigned into the sham operation group, spinal cord injury group, curcumin group, fecal microbiota transplantation group, fecal microbiota transplantation+ curcumin group, and fecal microbiota transplantation+curcumin+GPR inhibitor group. Neurological function recovery was evaluated based on the Basso-Beattie-Bresnahan motor function score and gait analysis. Histopathological changes in the injured area were observed via hematoxylin-eosin staining, Nissl staining, and Luxol Fast Blue staining. RT-qPCR, ELISA, and Western blotting were employed to quantify the expression levels of key transcription factor forkhead box protein 3 (FOXP3) for Treg cells, anti-inflammatory cytokines interleukin (IL)-10 and transforming growth factor (TGF)-β1, as well as key transcription factor retinoic acid receptor-related orphan receptor gamma t (RORγt) for Th17 cells and pro-inflammatory cytokines IL-17 and IL-6 in the spinal cord of each group.Results Compared with the spinal cord injury group and fecal microbiota transplantation group, the curcumin group and fecal microbiota transplantation+ curcumin group showed the most significant improvement in neurological function, specifically manifested by significant increases in BBB motor function scores and gait coordination, along with a marked reduction in the scope of spinal cord injury. At the molecular level, the two groups showed significantly upregulated gene and protein levels of FOXP3, IL-10, and TGF-β1 and significantly inhibited expression of RORγt, IL-17A, and IL-6 in the spinal cord tissue. This suggests that after curcumin intervention in the gut microbiota, the immune balance shifted toward a Treg-dominated anti-inflammatory state. Notably, the aforementioned beneficial effects of curcumin-modified gut microbiota were reversed after combined use of the GPR inhibitor.Conclusion This study indicates that curcumin can act on the gut microbiota to promote the recovery of motor function after spinal cord injury. Curcumin may exert the effect by activating the GPR signaling pathway, thereby upregulating Treg viability, inhibiting Th17 differentiation, and ultimately correcting the Treg/Th17 imbalance. This provides new experimental evidence and application value for using curcumin and its modified gut microbiota as an adjuvant therapeutic strategy for spinal cord injury.