The Ca2+/CaMKK2 axis mediates the telbivudine induced upregulation of creatine kinase: Implications for mechanism of antiviral nucleoside analogs' side effect

Creatine kinase elevation in chronic hepatitis B patients with telbivudine therapy: influence of telbivudine plasma concentration and single nucleotide polymorphisms of TK2, RRM2B, and NME4

PURPOSE

To study the correlations of genetic variants of telbivudine phosphorylase kinases and telbivudine plasma concentration with creatine kinase elevation in chronic hepatitis B patients who received telbivudine.

METHODS

An observational study was performed in China chronic hepatitis B patients receiving telbivudine therapy at 600 mg once daily. Plasma concentration was measured 12 h after taking telbivudine using ultra-performance liquid chromatography-tandem mass spectrometry and SNPs located in RRM2B, TK2, and NME4 was detected by MALDI-TOF mass spectrometry. All statistical analyses were performed with R 4.3.1 and all graphs were drawn by Origin 2023b and P value < 0.05 was considered statistically significant.

RESULTS

A total of 140 patients receiving telbivudine therapy were recruited with a median plasma concentration of 952.49 (781.07-1238.98) ng/mL. The value of plasma concentration was proportional to the grade of creatine kinase elevation and the best telbivudine plasma concentration threshold to discriminate the grade 3/4 CK elevation was 1336.61 ng/mL. Multivariate analysis revealed that plasma concentration and rs3826160 were the independent risk factor of telbivudine-induced creatine kinase elevation. Patients with TC and CC genotype in rs3826160 not only had a higher incidence of creatine kinase elevation but also a higher plasma concentration than TT genotype carriers.

CONCLUSION

Chronic hepatitis B patients with TC and CC genotype in rs3826160 have high telbivudine plasma concentration are at risk of elevated creatine kinase.

Insights into the mechanisms of telbivudine-induced myopathy associated with mitochondrial dysfunction

As a nucleotide analogue (NA), telbivudine was widely used in the treatment for chronic hepatitis B (CHB) by interfering with reverse transcriptase of hepatitis B virus. However, the use of NAs for hepatitis B treatment has been accompanied by numerous reports highlighting the occurrence of neuromyopathy, particularly in the case of telbivudine. This study aimed to investigate the underlying mechanisms responsible for telbivudine-induced myopathy. We established animal and cell models of telbivudine-induced myopathy using C57BL/6 mice and C2C12 cells, respectively. Our findings revealed that telbivudine significantly reduced mitochondrial DNA (mtDNA) copy number and caused increase of oxidative stress. Telbivudine treatment significantly inhibited mitochondrial complex I and IV expression, impairing the oxidative phosphorylation function of the respiratory chain. Modified Gomori trichrome (MGT) staining of the muscle sections displayed an increase in ragged red fibers (RRFs), indicating abnormal mitochondrial accumulation. In conclusion, our study provides compelling evidence suggesting that telbivudine-induced myopathy is associated with mitochondrial toxicity and impaired energy metabolism. The observed muscle pathology, depletion of mtDNA, elevation of oxidative stress and altered mitochondrial function support the hypothesis that telbivudine disrupts mitochondrial homeostasis, ultimately leading to muscle damage. This may be also a common mechanism for NAs to cause neuromyopathy.

Modulation of hepatitis B virus pregenomic RNA stability and splicing by histone deacetylase 5 enhances viral biosynthesis

Hepatitis B virus (HBV) is a worldwide health problem without curative treatments. Investigation of the regulation of HBV biosynthesis by class I and II histone deacetylases (HDACs) demonstrated that catalytically active HDAC5 upregulates HBV biosynthesis. HDAC5 expression increased both the stability and splicing of the HBV 3.5 kb RNA without altering the translational efficiency of the viral pregenomic or spliced 2.2 kb RNAs. Together, these observations point to a broader role of HDAC5 in regulating RNA splicing and transcript stability while specifically identifying a potentially novel approach toward antiviral HBV therapeutic development.

This study demonstrates that HDAC5 deacetylation of host cellular factor(s) results in increased HBV biosynthesis by enhancing viral transcript stability and splicing via direct or indirect binding of host factors to viral intron sequences. This represents the first demonstration of this type of post-transcriptional regulation in the liver and is similar to observations seen for cellular transcripts in neural and cardiac cell types. These observations suggest a more general phenomenon which could represent an additional post-transcriptional code governing the regulation of RNA:protein interactions and hence RNA metabolism. Therefore, covalent modifications of RNA binding proteins may modulate post-transcriptional gene expression in an analogous manner to the known histone code that controls gene transcription. Although this analysis primarily relates to the mechanism(s) by which HDAC5 governs HBV RNA metabolism, it does have significant therapeutic implications. The inhibition of HDAC5 in combination with current nucleos(t)ide analog drugs targeting the viral reverse transcriptase/DNA polymerase might aid in the treatment and possible resolution of chronic infections by targeting both host and viral factors.

Slow walking speed overlapped with low handgrip strength in chronic liver disease patients with hepatocellular carcinoma

AIM

Walking speed and grip strength are parameters of muscle function; however, evaluating walking speed is not always available in clinical practice. We aimed to investigate the impact of walking speed on the evaluation of muscle dysfunction in chronic liver disease (CLD) patients with hepatocellular carcinoma (HCC).

METHODS

We enrolled 107 consecutive CLD patients with HCC in this study (age 76 years [range 60-92 years]; female/male 39/68; body mass index 22.9 [range 20.0-25.3]; chronic hepatitis/liver cirrhosis 25/82). Muscle dysfunction was evaluated using the Asian Working Group for Sarcopenia criteria (grip strength or walking speed) and the Japan Society of Hepatology criteria (grip strength). A correlation between walking speed and skeletal muscle index was evaluated. Independent factors for slow walking speed were evaluated using a logistic regression analysis.

RESULTS

There was no significant correlation between walking speed and skeletal muscle index (r = 0.14, P = 0.16). For both the Asian Working Group for Sarcopenia and Japan Society of Hepatology criteria, 33.6% of all patients were classified as having muscle dysfunction. All patients with slow walking speed (4.7% of all patients) also showed low handgrip strength. The logistic regression analysis identified grip strength as an independent factor for slow walking speed (OR 0.65; 95% CI 0.432-0.838; P = 0.008).

CONCLUSIONS

No difference was seen in the prevalence of muscle dysfunction between the Asian Working Group for Sarcopenia and Japan Society of Hepatology criteria in CLD patients with HCC. Furthermore, all patients with slow walking speed also showed low handgrip strength. Thus, for the evaluation of muscle dysfunction, grip strength might be a suitable proxy for walking speed in CLD patients with HCC.