黄芩汤调控肠道菌群治疗小鼠肠道急性移植物抗宿主病的机制

Mechanism by which Huangqintang regulates intestinal flora for treatment of intestinal acute graft-versus-host disease in mice

背景:肠道急性移植物抗宿主病是异基因造血干细胞移植后最凶险的并发症之一,具有较高的致死率,如何通过应用中药改善肠道炎症、调节自噬以治疗肠道急性移植物抗宿主病是当下值得研究的问题。目的:探讨黄芩汤调控肠道菌群治疗肠道急性移植物抗宿主病的机制。方法:CB6F1小鼠经总剂量8 Gy的60Co X射线照射后通过尾静脉输入Balb/c H-2d小鼠的单个核细胞悬液(骨髓+脾)制备急性移植物抗宿主病模型,随机分为模型组及黄芩汤高、中、低剂量组。造模后分别给予不同剂量黄芩汤或等体积生理盐水连续灌胃14 d,进行临床急性移植物抗宿主病评分并记录生存时间,取小肠组织做苏木精-伊红染色行小肠黏膜病理分级评分。使用16S rDNA测序检测各组小鼠肠道菌群,行免疫荧光、免疫组化染色、PCR等检测自噬相关标志物的表达。结果与结论:(1)与模型组相比,黄芩汤中、高剂量组小鼠存活时间显著延长(P<0.01),临床急性移植物抗宿主病评分显著降低(P<0.01),小肠黏膜病理分级评分显著降低(P<0.01),小肠组织炎症因子肿瘤坏死因子α、白细胞介素1β、白细胞介素6水平显著下降(P<0.01),小鼠小肠黏膜上皮结构完整性部分恢复;(2)肠道菌群研究发现,与模型组相比,黄芩汤中剂量组促炎菌株肠球菌显著减少(P<0.05),而有益菌如梭状芽孢杆菌及促自噬的红球菌显著增多(P<0.05);(3)与模型组相比,黄芩汤中剂量组的自噬标志物显著升高(P<0.05);透射电镜下,黄芩汤中剂量组自噬泡数量显著增多;(4)结果表明:黄芩汤显著降低条件性致病菌丰度和小肠组织炎症因子水平,并提高有益菌相对丰度,同时促进小肠黏膜自噬的表达,从而明显改善急性移植物抗宿主病小鼠肠道症状。

BACKGROUND:Intestinal acute graft-versus-host disease is one of the most aggressive complications after allogeneic hematopoietic stem cell transplantation with high lethality.How to improve intestinal inflammation and regulate autophagy by applying traditional Chinese medicine in order to treat intestinal acute graft-versus-host disease is a worthwhile research issue nowadays.OBJECTIVE:To investigate the mechanism of Huangqintang modulating intestinal flora for the treatment of intestinal acute graft-versus-host disease.METHODS:CB6F1 mice were irradiated with 60Co X radiation at a total dose of 8 Gy,and then single nucleated cell suspensions(bone marrow cells+splenocytes)from Balb/c H-2d mice were injected into the tail vein in order to prepare a model of intestinal acute graft-versus-host disease.These samples were randomly divided into the model group and the high-,moderate-,and low-dose Huangqintang groups.After modeling,the model,high-,moderate-,and low-dose groups received different doses of Huangqintang or an equal volume of saline by continuous gavage for 14 days.Clinical acute graft-versus-host disease grading,and survival time was recorded.Small intestinal tissues from each group were stained with hematoxylin and eosin for small intestinal mucosal pathology scoring.The intestinal flora of mice in each group was detected using 16S rDNA sequencing.Autophagy-related markers were detected using immunofluorescence,immunohistochemistry,and PCR.RESULTS AND CONCLUSION:(1)Compared with the model group,the survival time of mice was significantly prolonged(P<0.01);the clinical acute graftversus-host disease scores were significantly reduced(P<0.01);the pathological grading scores of the small intestinal mucosa were significantly diminished(P<0.01);the levels of the small intestinal tissue inflammatory factors tumor necrosis factor-α,interleukin-1β,and interleukin-6,were significantly decreased(P<0.01);the structural integrity of the small intestinal mucosal epithelium was partially restored in mice after the intervention of moderate and high-dose Huangqintang.(2)The study of intestinal flora found that compared with the model group,the pro-inflammatory strain Enterococcus was significantly reduced(P<0.05),while beneficial bacteria such as Clostridium_innocuum and Rhodococcus,a pro-autophagy bacterium,were significantly elevated(P<0.05)in the moderate-dose Huangqintang group.(3)Compared with the model group,the autophagy markers were significantly elevated in the moderate-dose Huangqintang group(P<0.05);under transmission electron microscopy,the number of autophagic vacuoles of moderate-dose Huangqintang group increased significantly.(4)The results showed that Huangqintang significantly reduced the abundance of conditionally pathogenic bacteria and the level of inflammatory factors in small intestinal tissues,and increased the relative abundance of beneficial bacteria and promoted the expression of autophagy in the small intestinal mucosa,which resulted in a significant improvement of intestinal symptoms in mice with acute graft-versus-host disease.