Long-term Adefovir Treatment Cause Injury To Mtdna Of PBMCs

Objective: Adefovir dipivoxil was approved for the treatment of chronichepatitis B (CHB) by American FDA in2002and admitted by Chinese SFDAto be used in clinical treatment three years later. To2008, the number takingadefovir dipivoxil in the world was about4.1million per year. But the courseof treatment is long and depends on individuals, the safty of prolongedtreatment has caught the eyes of medical workers and patients. As adefovirdipivoxil may affect DNA polymerase-gamma, which control the proliferationof mitochondria, this pilot study is to address whether long-term treatment ofadefovir dipivoxil in patients with CHB can cause damage to mitochondrialDNA(mtDNA) in the peripheral blood mononuclear cells(PBMCs).Material and Methods:37na ve patients with CHB were enrolled whowould receive adefovir dipivoxil monotherapy for four years. The diagnosesof CHB were according to the Guideline on Prevention and Treatment forChronic Hepatitis B in China (2005).37patients were prospectivelyfollowed-up once a year, totally four years and were divided into four groups:Group A baseline of the37na ve CHB patients; Group B adefovir dipivoxilmonotherapy for two years; Group C adefovir dipivoxil monotherapy for threeyears; Group D adefovir dipivoxil monotherapy for four years. The content ofmitochondrial DNA (mtDNA) in PBMCs and8-Hydroxy-desoxyguanosine(8-OHdG) were detected by Real-time quantitative Polymerase ChainReaction (RT-PCR). The mtDNA4977depletion was measured by nested PCR.Clinical parameters in each group such as ALT, AST, HBV DNA, creatinekinase (CK), serum urea nitrogen (BUN), serum creatinine (SCr), lactic acid(LAC) were recorded. Repetitive measure analysis of variance (ANOVA) andtwo-sample t-test were used to data satisfy normal distribution. Kruskal-WallisH test and Wilcoxon rank sum test were practiced to those skewnessdistribution data. Chi-aquare test or fisher's exact test was performed to those categorical variables. Curve correlation and multiple linear regressionwere used to find the correlation among the indexes.Results:1.homogeneity:37cases (male34, female3) aged21-63withthe average age (40.11±10.69) years. The ALT statistic value is F=22.948,P=0.000, the ALT level in group A is much higher than group B, group C andgroup D, P=0.000,0.000,0.000respectivly, while there is no significantdifference between group B, group C and group D. The AST statistic value isF=22.948, P=0.000, the AST level has the same varience as ALT.8cases getHBeAg sero-conversion at group B, the rate is33.33%,10cases get HBeAgsero-conversion at group C and group D, the rate is41.67%. There is nostatistic difference of HBeAg during the four years, χ2=7.400, P=0.060. TheHBV DNA statistic value is χ2=62.438, P=0.000, the HBV DNA in group A ismuch higher than the other three grous, P=0.000,0.000,0.000respectively,but there is no noticeable differences among the other three groups. The BMI,CK, BUN, SCr have no statistic differences among the four groups.2.mtDNAcontent: The RQ (mtDNA/nDNA) value in group A,14.7±9.5, is significantlyhigher than group B at7.8±4.2, P=0.028and group C at8.5±4.4, P=0.045butlower than group D at36.6±24.0,P=0.000. The RQ value in group B andgroup C are markedly lower than group D, P=0.000,0.000respectively buthas no difference between the two groups, P=0.806.3.mtDNA4977depletion:the tendency of mtDNA4977depletion rate first rise then maintain in a certainlevel during the four years, F=6.887,P=0.000. The mtDNA4977depletion rateof group A0.2±0.1, is much lower than group B at0.3±0.1, group C at0.3±0.2and group D at0.3±0.2, P=0.000,0.000,0.000, respectively. But there is nosignificant difference among the three groups.4.point mutations in mtDNA:the tendency of8-OHdG level first rise then maintain in a certain level duringthe four years, F=5.721,P=0.005. The8-OHdG level of group A2.4±0.9, ismuch lower than group B at3.5±1.2, group C at3.4±0.8and group D at3.4±1.1, P=0.000,0.000,0.000, respectively. But there is no significantdifference among the three groups.5.normal and abnormal clinical parameters:to the fouth year taking adefovir dipivoxil,8cases (28.6%) have elevated LAC,2cases (5.9%) have elevated BUN,7case (20.6%) have elevated CK.But there is no statistic differences of mtDNA contents, mtDNA4977depletionrate and8-OHdG level among the four groups, P＞0.05.6.correlation analysis:mtDNA contents has a curve correlation with mtDNA4977depletion rate and8-OHdG level, the coefficient of determination R2=0.104,0.053, respectivelybut has no correlation with other parameters. By multiple linear regression wefound that mtDNA4977depletion is positive correlated with8-OHdG only,F=2.916,P=0.002, R2=0.257, the partial regression coefficient B=0.034,P=0.012.8-OHdG level is positive related with mtDNA4977depletion rate andnegative correlated with CK, F=2.268, P=0.014, R2=0.212, B=1.755,-0.602,P=0.012,0.044, respectively.Conclusion:37patients were studied as long as four years. Repeatedmeasurement was used to overcome the variance caused by course of disease,age, gender, smoke, alcohol, eating habit, et al. Three indexes: mtDNAcontents, mtDNA4977depletion and point mutation (8-OHdG) were taken toget the conclusion that to the fouth year of adefovir dipivoxil treatment,mtDNA contents increases as a feedback effect, so are the mitochondrialoxidative damages although no clinical symtomics were seen yet. So whetherlonger time taking adefovir can cause serious mitochondrial toxicity or notneed to be further studied.