In vitro cell culture models to study hepatitis B and D virus infection

Contrasting Effect of Curcumin on Hepatitis B Virus Replication According to the Hepatoma Cell Line

In recent decades, considerable advances have been achieved in the treatment of chronic hepatitis B. However, the currently available drugs have shortcomings. In this context, several natural compounds have been proposed as potential agents to improve either the outcome of antiviral treatment or the progression of chronic infection, with curcumin being one of the most evaluated compounds due to its pleiotropic antiviral activity. The aim of this study was to characterize the effect and mechanism of curcumin on hepatitis B virus (HBV) replication in two different experimental models. Treatment of HepG22.15 and HBV-transfected Huh7 cells with curcumin revealed that the phytochemical differentially modulated HBV replication in both cell lines. In HepG22.15 cells, the addition of curcumin had no effect on viral DNA, pregenomic RNA (pgRNA), and e antigen (HBeAg) levels, while it decreased Precore RNA and s antigen (HBsAg) levels. Conversely, in Huh-7 cells, curcumin significantly increased viral progeny more than tenfold, as well as HBV RNAs and viral antigens. Furthermore, the analysis of the cellular mechanisms associated with the modulation of viral replication revealed that in Huh-7 cells, curcumin-induced cell cycle arrest in the G2/M phase and the modulation of genes involved in proliferation, cell cycle progression, and apoptosis, whereas no changes in cell cycle progression and gene expression were observed in HepG22.15 cells. In conclusion, curcumin elicits a differential cellular response in two hepatoma cell lines, which, in the case of Huh-7 cells, would provide an optimal cellular setting that enhances HBV replication. Therefore, the antiviral effect of this phytochemical remains controversial.

Inhibition of HBV Replication by a Fully Humanized Neutralizing Antibody In Vivo and In Vitro

Neutralizing antibodies are capable of specifically binding to the HBsAg virus, thereby preventing HBV infection and subsequently reducing viral antigen load in both the liver and systemic circulation. This has significant implications for restoring the postnatal immune function. By utilizing the phage antibody library technology, we successfully screened a fully humanized neutralizing antibody targeting the hepatitis B surface antigen. The antiviral activity was assessed in primary human hepatocytes (PHHs) by determining the EC50 values for HBeAg and HBsAg biomarkers in HBV types B, C, and D; no cytotoxicity was observed within the tested concentration range. Furthermore, HT-102 exhibited no ADCC effect but displayed a weak CDC effect along with a dose-dependent response. We established an AAV/HBV mouse model and observed significant dose-dependent reduction in HBsAg and HBV DNA levels for both the medium-dose and highdose groups. The immunohistochemical staining data showed dose-dependent reduction in HBsAg expression in the liver, with high-dose group exhibiting minimal positive expression. Finally, a mild immune response was induced, while reducing the burden of antigen-antibody complexes circulating within the system. Consequently, strain on the patient's immune system was alleviated by effectively slowing down CD8+T lymphocyte depletion, and functional cure was ultimately achieved as intended.

Study of tree shrew biology and models: A booming and prosperous field for biomedical research

The tree shrew ( Tupaia belangeri) has long been proposed as a suitable alternative to non-human primates (NHPs) in biomedical and laboratory research due to its close evolutionary relationship with primates. In recent years, significant advances have facilitated tree shrew studies, including the determination of the tree shrew genome, genetic manipulation using spermatogonial stem cells, viral vector-mediated gene delivery, and mapping of the tree shrew brain atlas. However, the limited availability of tree shrews globally remains a substantial challenge in the field. Additionally, determining the key questions best answered using tree shrews constitutes another difficulty. Tree shrew models have historically been used to study hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, myopia, and psychosocial stress-induced depression, with more recent studies focusing on developing animal models for infectious and neurodegenerative diseases. Despite these efforts, the impact of tree shrew models has not yet matched that of rodent or NHP models in biomedical research. This review summarizes the prominent advancements in tree shrew research and reflects on the key biological questions addressed using this model. We emphasize that intensive dedication and robust international collaboration are essential for achieving breakthroughs in tree shrew studies. The use of tree shrews as a unique resource is expected to gain considerable attention with the application of advanced techniques and the development of viable animal models, meeting the increasing demands of life science and biomedical research.

Generation and characterization of mature hepatocyte organoids for liver metabolic studies

Hepatocyte organoids (HOs) generated in vitro are powerful tools for liver regeneration. However, previously reported HOs have mostly been fetal in nature with low expression levels of metabolic genes characteristic of adult liver functions, hampering their application in studies of metabolic regulation and therapeutic testing for liver disorders. Here, we report development of novel culture conditions that combine optimized levels of triiodothyronine (T3) with the removal of growth factors to enable successful generation of mature hepatocyte organoids (MHOs) of both mouse and human origin with metabolic functions characteristic of adult livers. We show that the MHOs can be used to study various metabolic functions including bile and urea production, zonal metabolic gene expression, and metabolic alterations in both alcoholic liver disease and non-alcoholic fatty liver disease, as well as hepatocyte proliferation, injury and cell fate changes. Notably, MHOs derived from human fetal hepatocytes also show improved hepatitis B virus infection. Therefore, these MHOs provide a powerful in vitro model for studies of human liver physiology and diseases. The human MHOs are potentially also a robust research tool for therapeutic development.

TRPV4 promotes HBV replication and capsid assembly via methylation modification of H3K4 and HBc ubiquitin

Hepatitis B virus (HBV) infection poses a significant burden on global public health. Unfortunately, current treatments cannot fully alleviate this burden as they have limited effect on the transcriptional activity of the tenacious covalently closed circular DNA (cccDNA) responsible for viral persistence. Consequently, the HBV life cycle should be further investigated to develop new anti-HBV pharmaceutical targets. Our previous study discovered that the host gene TMEM203 hinders HBV replication by participating in calcium ion regulation. The involvement of intracellular calcium in HBV replication has also been confirmed. In this study, we found that transient receptor potential vanilloid 4 (TRPV4) notably enhances HBV reproduction by investigating the effects of several calcium ion-related molecules on HBV replication. The in-depth study showed that TRPV4 promotes hepatitis B core/capsid protein (HBc) protein stability through the ubiquitination pathway and then promotes the nucleocapsid assembly. HBc binds to cccDNA and reduces the nucleosome spacing of the cccDNA-histones complex, which may regulate HBV transcription by altering the nucleosome arrangement of the HBV genome. Moreover, our results showed that TRPV4 promotes cccDNA-dependent transcription by accelerating the methylation modification of H3K4. In conclusion, TRPV4 could interact with HBV core protein and regulate HBV during transcription and replication. These data suggest that TRPV4 exerts multifaceted HBV-related synergistic factors and may serve as a therapeutic target for CHB.

Photobiological modulation of hepatoma cell lines and hepatitis B subviral particles secretion in response to 650 nm low level laser treatment

BACKGROUND

Chronic hepatitis B virus (HBV) infection is a serious global health concern, with an increased incidence and risk of developing cirrhosis and hepatocellular carcinoma (HCC). Patients chronically infected with HBV are likely to experience chronic oxidative stress, leading to mitochondrial dysfunction. Photobiomodulation is induced by the absorption of low-level laser therapy (LLLT) with a red or infrared laser by cytochrome C oxidase enzyme, resulting in mitochondrial photoactivation. Although it is widely used in clinical practice, the use of LLL as adjuvant therapy for persistent HBV infection is uncommon. This study aimed to investigate the effect of LLLT dosage from 2 J/cm2 to 10 J/cm2 of red diode laser (650 nm) on both hepatoma cell lines (HepG2.2.15 [integrated HBV genome stable cell model] and non-integrated HepG2), with a subsequent impact on HBVsvp production.

METHODS

The present study evaluated the effects of different fluences of low-level laser therapy (LLLT) irradiation on various aspects of hepatoma cell behavior, including morphology, viability, ultrastructure, and its impact on HBVsvp synthesis.

RESULTS

In response to LLLT irradiation, we observed a considerable reduction in viability, proliferation, and HBVsvp production in both hepatoma cell lines HepG2.2.15 and HepG2. Ultrastructural modification of mitochondria and nuclear membranes: This effect was dose, cell type, and time-dependent.

CONCLUSIONS

The use of LLLT may be a promising therapy for HCC and HBV patients by reducing cell proliferation, HBVsvp production, and altering mitochondrial and nuclear structure involved in cellular death inducers. Further research is required to explore its clinical application.