Effects And Mechanism Of Long-term Use Of Tenofovir Disoproxil Fumarate On Lactate Metabolism

Objective: Chronic hepatitis B(CHB)infection is one of the major causes of chronic liver disease,and there are a significant proportion of CHB patients will progress to cirrhosis and hepatocellular carcinoma.Therefore,prevention of disease progression and its complications is the primary goal of CHB therapy,which is primarily achieved by inhibiting the replication of hepatitis B virus(HBV)DNA.As most CHB patients require long-term treatment,the safety of these antiviral agents become important,besides their treatment effect.Tenofovir disoproxil fumarate(TDF),as a first-line antiviral drug for chronic hepatitis B,has been recommended by various guidelines for long-term or even lifelong using to inhibit viral replication and slow the progression of the disease.Therefore,it is necessary to know the safety of long-term using TDF.Recently,some case reports have reported that lactic acidosis occurred in TDF treated HIV or HBV patients.However,the effect and specific mechanism of long-term using TDF on blood lactate levels in CHB patients are still unclear.Methods: In the clinical cohort study,we observed the changes of blood lactate levels in patients with chronic hepatitis B treated with TDF in a national multicenter cohort.And detail of the factors associated with increased lactate were analyzed.In animal experiments,mice were gavage with TDF for 4 months to simulate the long-term use of TDF in humans.Then,we detected the changes of serum lactate levels in mice treated with TDF for 4 months,and further analyzed the effects of TDF on the production and clearance of lactate in the body by enzyme activity detection,histochemical staining,PCR and Western Blot in skeletal muscle,myocardium,liver and kidney tissues.Finally,we used RNA-seq to screen out the key molecules affecting the lactate metabolism by TDF.All results were analyzed by SPSS 20.0 software.Results: In the clinical cohort,we found that more than a half(52.34%)of 128 CHB patients treated with TDF for 96 weeks had at least one-time hyperlactatemia during TDF treatment.In addition,13 patients(10.16%)developed hyperlactatemia,which was determined to be an adverse event related to TDF.In the subgroup analysis,we found that the blood lactate levels at 96 weeks of TDF treatment was significantly higher than that at baseline.Further stratified analysis with alanine aminotransferase(ALT)revealed that elevated blood lactate levels at 96 weeks were mainly present in patients with severely impaired liver function(5-10 times the upper limit of normal).In animal experiments,we found that blood lactate levels were significantly increased in TDF treated mice.Next,we examined the changes of glycolysis in skeletal muscle tissue and found that TDF significantly promoted glycolysis in skeletal muscle,which further increased the production of lactate.However,no significant effect of TDF on glycolysis was found in myocardial tissue.Then,we detected the changes of gluconeogenesis in liver and kidney tissues,and found that TDF had no effect on the gluconeogenesis in liver and kidney tissues.At the same time,we also detected changes of mitochondrial function in these tissues and found that TDF caused mitochondrial dysfunction in skeletal muscle,but not in myocardial,liver and kidney tissues.Finally,through RNA-seq of skeletal muscle tissues,we found that PGC1α,a critical transcriptional coactivator that regulates lactate homeostasis and mitochondrial biogenesis,was dramatically decreased in skeletal muscle from TDF-treated mice.Conclusions: TDF elevates lactate levels by accelerating glycolysis and damaging mitochondrial function in skeletal muscle.Abnormal blood lactate caused by long-term use of TDF is an adverse side effect ignored by us previously.Therefore,we should pay attention to blood lactate levels in patients during clinical use of TDF,especially in those with apparently impaired liver function.