Role Of Intestinal Flora In Mucosal Damage After HDMTX Chemotherapy Associated With Drug Metabolizing Enzyme Related

ObjectiveExplore the changes of intestinal flora in ALL patients during chemotherapy and the effect of intestinal flora on HDMTX related gastrointestinal mucosal damage related to MTX related drug metabolizing enzyme gene polymorphism,and to screen strains that can alleviate HDMTX related mucosal damage.MethodsMTX related drug metabolizing enzyme gene polymorphisms were detected in the remission stage of ALL.The main detection sites included ABCB1,GSTP1,MTHFR 1298 and MTHFR 677.Stool samples were collected at the time of initial diagnosis,before HDMTX chemotherapy and after HDMTX chemotherapy,and 16SrDNA gene sequences were analyzed to determine the diversity and composition of bacterial 16SrDNA gene;Combined with clinical data analysis,we evaluated the influence of intestinal flora composition before HDMTX chemotherapy on gastrointestinal mucosal damage during HDMTX chemotherapy,and established a prediction model combined with MTX related drug metabolizing enzyme gene polymorphism.Results(1)At the initial diagnosis,the intestinal flora of ALL children was significantly different from that of healthy controls,with a diversity decreasing(4.45 VS 5.40,p<0.01),the relative abundance of Bacteroides(6.46%vs 33.70%,P<0.05),Faecalibacterium(0.00%vs 1.20%,P<0.05)decreased,and the relative abundance of Enterococcus(17.51%vs 0.00%,P<0.05)and Shigella(8.38%vs 0.46%,P<0.05)increased;(2)With the gradual remission of ALL,the a diversity in children after HDMTX was higher than baseline((Shannon index)After vs FV=5.00 vs 4.45,P<0.05),but still lower than that of healthy children(After vs FV=5.00 vs 5.40,P<0.05);The relative abundance of Blautia increased gradually during chemotherapy(11.69%vs 1.19%,p<0.05),while the relative abundance of Enterococcus decreased(1%vs 17.51%,P<0.05);(3)According to the results of gene polymorphism,MTX dosage was adjusted,the increase of MTX final concentration and HDMTX related gastrointestinal mucosal damage did not significantly increase in children with homozygous and heterozygous mutations(P>0.05);There was a positive correlation between the occurrence of gastrointestinal mucosal damage and 44 h MTX plasma concentration;(4)The α diversity of intestinal flora in Severe group was lower than that in Mild group(Shannon index 4,80 vs 4.85,P>0.05).The relative abundance of Faecalibacterium flora in Severe group was lower than that in Mild group(0.96%vs 4.94%,P<0.01);In the MTHFR 677CT mutation heterozygous children with severe mucosal damage(CT-S),the relative abundance of Faecalibacterium was lower than that of MTHFR 677CT mutation heterozygous children without severe mucosal damage(CT-M)(1.03%vs 5.52%,P<0.05),and the relative abundance of Blautia was lower(3.06%vs 7.78%,P<0.05);(5)In children with ABCB1 homozygous mutation,the early clearance rate of MTX elimination phase decreased(0.115 vs 0.170,P<0.05);The AUC of the area under the curve of MTX elimination phase curve and event encircle:ment was significantly increased in the homozygous children with ABCB1,mthfr1298 and mthfr677 mutations(75 vs 30,p<0.05;75 VS 40,p<0.01;75 VS 35,p<0.05)。Conclusion(1)The composition of intestinal flora in ALL children was different from that in healthy children,which showed the decrease of species diversity,the decrease of relative abundance of Bacteroides and Faecalibacterium,and the increase of relative abundance of Enterococcus and Escherichia-Shigella.(2)With the progress of chemotherapy and remission of the disease,the species diversity of intestinal flora in ALL children increased.The relative abundance of Blautia increased gradually with the remission of the disease,while the relative abundance of Enterococcus decreased compared with the baseline.In the middle and late stage of chemotherapy,maintaining the stability and structural balance of intestinal flora may be beneficial to the long-term prognosis of ALL;(3)The increase of relative abundance of Blautia and Faecalibacterium can prevent HDMTX related gastrointestinal mucosal damage;(4)It is not necessary to rely on the results of gene polymorphisms related to drug metabolizing enzymes to decide whether to rescue calcium folinate at an early stage;It is necessary to monitor MTX plasma concentration during HDMTX and make early treatment;(5)ABCB1 mutation homozygous may slow down the clearance rate of MTX elimination phase.The homozygous mutations of ABCB1,MTHFR1298 and MTHFR677 indicate the late accumulation of MTX.It may be necessary to monitor the blood concentration of MTX in these homozygous children.