Association Between Genetic Variation Of Protoporphyrin Ⅸ Biosynthesis Pathway And Susceptibility To Antituberculosis Drug-induced Liver Inury

Backgrounds: Antituberculosis drug-induced liver injury(ATLI)is a serious adverse drug reaction,and its pathogenic mechanism is still largely unknown.Pregnane X receptor(PXR,encoded by the NR1I2 gene)is a ligand-dependent transcription factor,and rifampicin is a human PXR-specific activator.Rifampicin and isoniazid co-therapy targets porphyrin biosynthesis via PXR and results in hepatic protoporphyrin IX accumulation and subsequent liver injury.Activated PXR could up-regulate the expression of aminolevulinic synthase-1(ALAS1),which is a speed-limit enzyme of heme biosynthesis pathway.In addition,isoniazid can also induce ALAS1 expression,reduce the chelating ferrous enzyme(ferrochelatase,FECH)expression that catalytic synthesis of heme.As a reactive substrate for the conversion of PPIX to heme,Fe2+ reflects the activity of ferrous chelatase indirectly and can also reflect the accumulation of PPIX in liver cells.PPIX accumulates in hepatocytes and is transported from hepatocytes to the biliary tract system by breast cancer resistance protein(BCRP,encoded by the ABCG2 gene),where it is excreted by bile metabolism.Therefore,the anabolic process of protoporphyrin IX is closely related to ATLI.Part 1 Association between NR1I2 polymorphisms and susceptibility to antituberculosis drug-induced liver injuryObjectives: The present study aimed to investigate the associations between genetic polymorphisms in NR1I2 and ATLI in an Eastern Chinese Han population.Methods: A 1:4 matched case-control study was conducted using 146 ATLI cases and 584 controls.Seven single nucleotide polymorphisms(SNPs)were detected and analyzed.Multivariate conditional logistic regression analysis was used to estimate the association between genotypes and risk of ATLI by the odds ratios(ORs)with 95% confidence intervals(CIs),with liver disease history,hepato-protectant use,smoking history and drinking history as covariates.Results: Patients carrying the GG genotype of rs7643645 were at a higher risk of ATLI than those carrying the AA genotype(OR = 1.864,95% CI: 1.106-3.141,P = 0.020),and significant differences were also found under the recessive model(P = 0.029)and additive model(P = 0.021).Patients with a polymorphism at rs2276707 were at a reduced risk of ATLI under the recessive model(OR = 0.600,95% CI: 0.364-0.988,P = 0.045).Subgroup analysis confirmed the relationship in mild hepatotoxicity cases under the additive model(rs7643645,OR = 1.429,95% CI: 1.027-1.988,P = 0.034)and recessive model(rs2276707,OR = 0.478,95% CI: 0.253-0.902,P = 0.023).Conclusions: Based on this case-control study,SNPs rs7643645 and rs2276707 in NR1I2 may contribute to susceptibility to ATLI in Eastern Chinese Han anti-TB treatment patients.Further studies in larger varied populations are needed to validate our findings.Part 2 NR1I2 genetic polymorphisms and the risk of anti-tuberculosis drug-induced hepatotoxicity: A systematic review and metaanalysisObjectives: Conflicting results have been obtained regarding the associations of nuclear receptor subfamily 1 group I member 2(NR1I2)gene polymorphisms on susceptibility to ATLI.Therefore,we aimed to evaluate the associations using a systematic review/meta-analysis approach.Methods: Pub Med,Cochrane Library,Web of Science,Sino Med,CNKI,Wanfang databases were searched for all eligible studies from inception to June 10,2020.Pooled adjusted odds ratios(ORs)with 95% confidence intervals(CIs)were employed to evaluate the strength of the association between the NR1I2 polymorphisms and the risk of ATLI.Subgroup analysis was performed by region of origin,and meta-regression were performed to detect potential sources of heterogeneity.Results: A total of five case-control studies involving 572 cases and 1867 controls were identified.Fourteen SNPs in the NR1I2 gene have been reported,and the most heavily studied SNPs were rs3814055 and rs7643645.The pooled estimates did not exhibit any significant associations between SNPs rs3814055 and rs7643645 and the risk of ATLI(rs3814055: dominant model,OR = 1.00,95% CI: 0.82-1.22,P = 1.00;recessive model,OR = 1.17,95% CI: 0.76-1.78,P = 0.48;rs7643645: dominant model,OR = 1.04,95% CI: 0.64-1.68,P = 0.89;recessive model,OR = 0.98,9 5% CI: 0.65-1.49,P = 0.93).Subgroup analysis obtained similar negative results in Chinese patients,and the diagnostic criteria of ATLI may be the source of heterogeneity.Conclusions: Based on the meta-analysis described in this report,we did not observe any association between NR1I2 gene polymorphisms and ATLI susceptibility.However,this conclusion should be interpreted with caution due to the low number of studies and the relatively small sample size.Part 3 Association between ALAS1、FECH、ABCG2 polymorphisms and susceptibility to antituberculosis drug-induced liver injuryObjectives: To investigate the association of ALAS1,FECH,ABCG2 gene polymorphisms and serum iron levels with ATLI in an Eastern Chinese Han population.Methods: A 1:4 matched case-control study was conducted on patients receiving antituberculosis treatment in four hospitals in Jiangsu province from May 2016 to December 2019,and 10 single nucleotide polymorphisms(SNPs)of ALAS1,FECH and ABCG2 genes were genotyped.Multivariate conditional logistic regression analysis was used to estimate the association between genotypes and risk of ATLI by the odds ratios(ORs)with 95% confidence intervals(CIs),with liver disease history,hepato-protectant use,smoking history and drinking history as covariates.Subgroup analysis was conducted according to the severity of hepatotoxicity,clinical type,association evaluation intensity and gender.Results: Based on 202 ATLI cases and 808 controls,the rs2231142 GT genotype may have a correlation with ATLI(OR = 1.387,95% CI: 0.994 1.936,P = 0.055),and the association also been found in mild ATLI subgroup(OR = 1.560,95%CI: 1.043-2.332,P = 0.030).Patients carrying the GG genotype of rs72627248 were at a higher risk of mixed ATLI than others(OR = 2.887,95%CI: 1.054-7.905,P = 0.039).In gender subgroup analysis,the men who carried rs2622605-CC were at a higher risk of ATLI than who carried TT/TC(OR = 1.615,95% CI: 1.119 2.332,P = 0.011).And the association between rs11660001 gene polymorphism and ATLI was found in women patients with additive model(OR = 1.673,95% CI: 1.015-2.760,P = 0.044).In addition,most of the serum iron content in the ATLI group showed an upward trend,with a greater increase than that in the control group,and the difference was statistically significant(P = 0.023).Conclusions: Based on this case-control study,SNPs rs11660001,rs2231142,rs2622605 and rs72627248 may contribute to susceptibility to ATLI in Chinese Han anti-TB treatment patients.Further studies in larger varied populations are needed to validate our findings.Moreover,the occurrence of ATLI may be accompanied by the increase of serum iron content.