The rs2296651 (S267F) variant on NTCP (SLC10A1) is inversely associated with chronic hepatitis B and progression to cirrhosis and hepatocellular carcinoma in patients with chronic hepatitis B

Bile acid-microbiota crosstalk in hepatitis B virus infection

Hepatitis B virus (HBV) is a hepatotropic non-cytopathic virus characterized by liver-specific gene expression. HBV infection highjacks bile acid metabolism, notably impairing bile acid uptake via sodium taurocholate cotransporting polypeptide (NTCP), which is a functional receptor for HBV entry. Concurrently, HBV infection induces changes in bile acid synthesis and the size of the bile acid pool. Conversely, bile acid facilitates HBV replication and expression through the signaling molecule farnesoid X receptor (FXR), a nuclear receptor activated by bile acid. However, in HepaRG cells and primary hepatocytes, FXR agonists suppress HBV RNA expression and the synthesis and secretion of DNA. In the gut, the size and composition of the bile acid pool significantly influence the gut microbiota. In turn, the gut microbiota impacts bile acid metabolism and innate immunity, potentially promoting HBV clearance. Thus, the bile acid-gut microbiota axis represents a complex and evolving relationship in the context of HBV infection. This review explores the interplay between bile acid and gut microbiota in HBV infection and discusses the development of HBV entry inhibitors targeting NTCP.

Sodium taurocholate cotransporting polypeptide (NTCP) polymorphisms may influence HDV RNA load and early response to bulevirtide

BACKGROUND & AIMS

Genetic polymorphisms in the sodium taurocholate cotransporting peptide (NTCP encoded by SLC10A1) have been described, but their role in untreated and treated patients with chronic hepatitis delta (CHD) remains unknown. Virological response (VR) to the NTCP inhibitor bulevirtide (BLV) was achieved at week 48 by >70% of patients with CHD, but nearly 15% experienced virological non-response (VNR) or partial response (PR). This study aimed to evaluate whether NTCP genetic polymorphisms affect baseline HDV RNA load and response to BLV in patients with CHD.

METHODS

BLV-untreated and -treated patients were enrolled in a retrospective cross-sectional and longitudinal study. Clinical and virological characteristics were collected at baseline and up to 96 weeks in the BLV-treated patients. NTCP genetic polymorphisms were identified by Sanger sequencing.

RESULTS

Of the six NTCP polymorphisms studied in 209 untreated patients with CHD, carriers of the rs17556915 TT/CC (n = 142) compared to CT (n = 67) genotype presented with higher median HDV RNA levels (5.39 vs. 4.75 log10 IU/ml, p = 0.004). Of 209 patients receiving BLV monotherapy at 2 mg/day, 76 were evaluated at week 24 and 40 up to week 96. Higher mean baseline HDV RNA levels were confirmed in TT/CC (n = 43) compared to CT (n = 33) carriers (5.38 vs. 4.72 log10 IU/ml, p = 0.010). Although 24-week VR was comparable between TT/CC and CT carriers (25/43 vs. 17/33, p = 0.565), the former group presented VNR more often than PR (9/11 vs. 9/23, p = 0.02) at week 24. 7/9 TT/CC genotype carriers remained VNR at week 48 of BLV treatment.

CONCLUSIONS

The NTCP rs17556915 C>T genetic polymorphisms may influence baseline HDV RNA load both in BLV-untreated and -treated patients with CHD and may contribute to identifying patients with different early virological responses to BLV.

IMPACT AND IMPLICATIONS

Although several sodium taurocholate cotransporting polypeptide (NTCP) genetic polymorphisms have been described, no data are available on their potential role in modifying HDV RNA load or treatment response to bulevirtide (BLV) in patients with chronic hepatitis delta (CHD). In this study, we demonstrated that patients with CHD, either treated or untreated, carrying NTCP rs17556915 TT/CC, presented higher baseline HDV RNA levels compared to those with the CT genotype. Higher HDV RNA levels in TT/CC carriers compared to CT carriers were also confirmed in patients with CHD treated with BLV monotherapy up to 96 weeks. Furthermore, carriers of TT/CC, compared to CT genotype, more frequently showed viral non-response (VNR) than partial response (PR) at week 24 of BLV treatment, and 7/9 TT/CC genotype carriers remained VNR at week 48 of BLV treatment. This is the first study demonstrating a potential role of NTCP genetic polymorphisms in influencing HDV viral load and early virological response to BLV monotherapy. Since no direct HDV resistance to BLV has been described so far, if confirmed in larger studies, the genetic polymorphisms in NTCP may help identify patients with different patterns of early virological response to BLV.

Population genetic admixture and evolutionary history in the Shandong Peninsula inferred from integrative modern and ancient genomic resources

BACKGROUND

Ancient northern East Asians (ANEA) from the Yellow River region, who pioneered millet cultivation, play a crucial role in understanding the origins of ethnolinguistically diverse populations in modern China and the entire landscape of deep genetic structure and variation discovery in modern East Asians. However, the direct links between ANEA and geographically proximate modern populations, as well as the biological adaptive processes involved, remain poorly understood.

RESULTS

Here, we generated genome-wide SNP data for 264 individuals from geographically different Han populations in Shandong. An integrated genomic resource encompassing both modern and ancient East Asians was compiled to examine fine-scale population admixture scenarios and adaptive traits. The reconstruction of demographic history and hierarchical clustering patterns revealed that individuals from the Shandong Peninsula share a close genetic affinity with ANEA, indicating long-term genetic continuity and mobility in the lower Yellow River basin since the early Neolithic period. Biological adaptive signatures, including those related to immune and metabolic pathways, were identified through analyses of haplotype homozygosity and allele frequency spectra. These signatures are linked to complex traits such as height and body mass index, which may be associated with adaptations to cold environments, dietary practices, and pathogen exposure. Additionally, allele frequency trajectories over time and a haplotype network of two highly differentiated genes, ABCC11 and SLC10A1, were delineated. These genes, which are associated with axillary odor and bilirubin metabolism, respectively, illustrate how local adaptations can influence the diversification of traits in East Asians.

CONCLUSIONS

Our findings provide a comprehensive genomic dataset that elucidates the fine-scale genetic history and evolutionary trajectory of natural selection signals and disease susceptibility in Han Chinese populations. This study serves as a paradigm for integrating spatiotemporally diverse ancient genomes in the era of population genomic medicine.

SLC10A1 rs2296651 variant (S267F mutation) predicts biochemical traits, hepatitis B virus infection susceptibility and the risk of gallstone disease

Sodium taurocholate co-transporting polypeptide (NTCP), a bile acid transporter, plays a crucial role in regulating bile acid levels and influencing the risk of HBV infection. Genetic variations in the SLC10A1 gene, which encodes NTCP, affect these functions. However, the impact of SLC10A1 gene variants on the metabolic and biochemical traits remained unclear. We aimed to investigate the association of SLC10A1 gene variants with the clinical and biochemical parameters, and the risk of different HBV infection statuses and gallstone disease in the Taiwanese population. Genotyping data from 117,679 Taiwan Biobank participants were analyzed using the Axiom genome-wide CHB arrays. Regional-plot association analysis demonstrated genome-wide significant association between the SLC10A1 rs2296651 genotypes and lipid profile, gamma glutamyl transferase (γGT) level and anti-HBc-positivity. Genotype-phenotype association analyses revealed significantly lower total cholesterol, low-density lipoprotein (LDL) cholesterol and uric acid levels, a higher γGT level and a higher gallstone incidence in rare rs2296651-A allele carrier. Participants with the rs2296651 AA-genotype exhibited significantly lower rates of anti-HBc-positivity and HBsAg-positivity. Compared to those with the GG-genotype, individuals with non-GG-genotypes had reduced risks for various HBV infection statuses: the AA-genotype showed substantially lower risks, while the GA-genotype demonstrated modestly lower risks. Predictive tools also suggested that the rs2296651 variant potentially induced protein damage and pathogenic effects. In conclusion, our data revealed pleiotropic effects of the SLC10A1 rs2296651 genotypes on the levels of biochemical traits and the risk of HBV infection and gallstone disease. This confirms SLC10A1's versatility and implicates its genotypes in predicting both biochemical traits and disease susceptibility.

Structural basis of hepatitis B virus receptor binding

Hepatitis B virus (HBV), a leading cause of developing hepatocellular carcinoma affecting more than 290 million people worldwide, is an enveloped DNA virus specifically infecting hepatocytes. Myristoylated preS1 domain of the HBV large surface protein binds to the host receptor sodium-taurocholate cotransporting polypeptide (NTCP), a hepatocellular bile acid transporter, to initiate viral entry. Here, we report the cryogenic-electron microscopy structure of the myristoylated preS1 (residues 2-48) peptide bound to human NTCP. The unexpectedly folded N-terminal half of the peptide embeds deeply into the outward-facing tunnel of NTCP, whereas the C-terminal half formed extensive contacts on the extracellular surface. Our findings reveal an unprecedented induced-fit mechanism for establishing high-affinity virus-host attachment and provide a blueprint for the rational design of anti-HBV drugs targeting virus entry.

Development of a promising PPAR signaling pathway-related prognostic prediction model for hepatocellular carcinoma

The peroxisome proliferator-activated receptor (PPAR) signaling pathway plays a crucial role in systemic cell metabolism, energy homeostasis and immune response inhibition. However, its significance in hepatocellular carcinoma (HCC) has not been well documented. In our study, based on the RNA sequencing data of HCC, consensus clustering analyses were performed to identify PPAR signaling pathway-related molecular subtypes, each of which displaying varying survival probabilities and immune infiltration status. Following, a prognostic prediction model of HCC was developed by using the random survival forest method and Cox regression analysis. Significant difference in survival outcome, immune landscape, drug sensitivity and pathological features were observed between patients with different prognosis. Additionally, decision tree and nomogram models were adopted to optimize the prognostic prediction model. Furthermore, the robustness of the model was verified through single-cell RNA-sequencing data. Collectively, this study systematically elucidated that the PPAR signaling pathway-related prognostic model has good predictive efficacy for patients with HCC. These findings provide valuable insights for further research on personalized treatment approaches for HCC.

Signature construction and molecular subtype identification based on liver-specific genes for prediction of prognosis, immune activity, and anti-cancer drug sensitivity in hepatocellular carcinoma

BACKGROUND

Liver specific genes (LSGs) are crucial for hepatocyte differentiation and maintaining normal liver function. A deep understanding of LSGs and their heterogeneity in hepatocellular carcinoma (HCC) is necessary to provide clues for HCC diagnosis, prognosis, and treatment.

METHODS

The bulk and single-cell RNA-seq data of HCC were downloaded from TCGA, ICGC, and GEO databases. Through unsupervised cluster analysis, LSGs-based HCC subtypes were identified in TCGA-HCC samples. The prognostic effects of the subtypes were investigated with survival analyses. With GSVA and Wilcoxon test, the LSGs score, stemness score, aging score, immune score and stromal score of the samples were estimated and compared. The HCC subtype-specific genes were identified. The subtypes and their differences were validated in ICGC-HCC samples. LASSO regression analysis was used for key gene selection and risk model construction for HCC overall survival. The model performance was estimated and validated. The key genes were validated for their heterogeneities in HCC cell lines with quantitative real-time PCR and at single-cell level. Their dysregulations were investigated at protein level. Their correlations with HCC response to anti-cancer drugs were estimated in HCC cell lines.

RESULTS

We identified three LSGs-based HCC subtypes with different prognosis, tumor stemness, and aging level. The C1 subtype with low LSGs score and high immune score presented a poor survival, while the C2 subtype with high LSGs score and immune score indicated an enduring survival. Although no significant survival difference between C2 and C3 HCCs was shown, the C2 HCCs presented higher immune score and stroma score. The HCC subtypes and their differences were confirmed in ICGC-HCC dataset. A five-gene prognostic signature for HCC survival was constructed. Its good performance was shown in both the training and validation datasets. The five genes presented significant heterogeneities in different HCC cell lines and hepatocyte subclusters. Their dysregulations were confirmed at protein level. Furthermore, their significant associations with HCC sensitivities to anti-cancer drugs were shown.

CONCLUSIONS

LSGs-based HCC subtype classification and the five-gene risk model might provide useful clues not only for HCC stratification and risk prediction, but also for the development of more personalized therapies for effective HCC treatment.

Role of sodium taurocholate cotransporting polypeptide (NTCP) in HBV-induced hepatitis: Opportunities for developing novel therapeutics

Hepatitis B is an infectious disease caused by the HBV virus. It presents a significant challenge for treatment due to its chronic nature and the potential for developing severe complications, including hepatocirrhosis and hepatocellular carcinoma. These complications not only cause physical and psychological distress to patients but also impose substantial economic and social burdens on both individuals and society as a whole. The internalization of HBV relies on endocytosis and necessitates the involvement of various proteins, including heparin sulfate proteoglycans, epidermal growth factor receptors, and NTCP. Among these proteins, NTCP is pivotal in HBV internalization and is primarily located in the liver's basement membrane. As a transporter of bile acids, NTCP also serves as a receptor facilitating HBV entry into cells. Numerous molecules have been identified to thwart HBV infection by stifling NTCP activity, although only a handful exhibit low IC50 values. In this systematic review, our primary focus dwells on the structure and regulation of NTCP, as well as the mechanism involved in HBV internalization. We underscore recent drug breakthroughs that specifically target NTCP to combat HBV infection. By shedding light on these advances, this review contributes novel insights into developing effective anti-HBV medications.

Identification of a bile acid and bile salt metabolism-related lncRNA signature for predicting prognosis and treatment response in hepatocellular carcinoma

Bile acids and salts have been shown to play a role in liver carcinogenesis through DNA damage, inflammation, and tumor proliferation. However, the correlation between bile acid metabolism and hepatocellular carcinoma (HCC) prognosis remains unclear. This study aimed to identify a predictive signature of bile acid and bile salt metabolism-related long non-coding RNAs (lncRNAs) for HCC prognosis and treatment response. The study used HCC RNA-sequencing data and corresponding clinical and prognostic data from The Cancer Genome Atlas. A prognostic model consisting of five bile acid and bile salt metabolism-related lncRNAs was developed and evaluated in a training set, a validation set and an external set. The model demonstrated good performance in predicting HCC prognosis and was shown to be an independent biomarker for prognosis. Additionally, our study revealed a significant association between the signature and immune cell infiltration, as well as its predictive value for therapeutic responses to both immunotherapy and chemotherapy. Furthermore, three LncRNAs (LUCAT1, AL031985.3 and AC015908.3) expression levels in our signature were validated through qRT-PCR in a cohort of 50 pairs of HCC patient tumor samples and corresponding adjacent non-tumor samples, along with 10 samples of normal liver tissue adjacent to benign lesions. These findings suggest that this novel bile acid and bile salt metabolism-related lncRNA signature can independently predict the prognosis of patients with HCC and may be utilized as a potential predictor of response to treatment in this setting.

Targeting Hepatitis B Virus DNA Using Designer Gene Editors

Chronic hepatitis B virus (HBV) infection is a serious disease that currently has no cure. Key forms of HBV include covalently closed circular DNA, which mediates chronic persistence, and integrated DNA, which contributes to immune evasion and carcinogenesis. These forms are not targeted by current therapies; however, gene editing technologies have emerged as promising tools for disrupting HBV DNA. Gene editor-induced double-stranded breaks at precise locations within the HBV genome can induce effects ranging from inactivation of target genes to complete degradation of the target genome. Although promising, several challenges remain in efficacy and safety that require solutions.

Hepatitis D virus infection, innate immune response and antiviral treatments in stem cell-derived hepatocytes

BACKGROUND

Human pluripotent stem cell (hPSC)-derived hepatocyte-like cells (HLCs) are a valuable model to investigate host-pathogen interactions of hepatitis viruses in a mature and authentic environment. Here, we investigate the susceptibility of HLCs to the hepatitis delta virus (HDV).

METHODS

We differentiated hPSC into HLCs, and inoculated them with infectious HDV produced in Huh7NTCP . HDV infection and cellular response was monitored by RTqPCR and immunostaining.

RESULTS

Cells undergoing hepatic differentiation become susceptible to HDV after acquiring expression of the viral receptor Na+ -taurocholate co-transporting polypeptide (NTCP) during hepatic specification. Inoculation of HLCs with HDV leads to detection of intracellular HDV RNA and accumulation of the HDV antigen in the cells. Upon infection, the HLCs mounted an innate immune response based on induction of the interferons IFNB and L, and upregulation of interferon-stimulated genes. The intensity of this immune response positively correlated with the level of viral replication and was dependant on both the JAK/STAT and NFκB pathway activation. Importantly, this innate immune response did not inhibit HDV replication. However, pre-treatment of the HLCs with IFNα2b reduced viral infection, suggesting that ISGs may limit early stages of infection. Myrcludex efficiently abrogated infection and blocked innate immune activation. Lonafarnib treatment of HDV mono infected HLCs on the other hand led to exacerbated viral replication and innate immune response.

CONCLUSION

The HDV in vitro mono-infection model represents a new tool to study HDV replication, its host-pathogen interactions and evaluate new antiviral drugs in cells displaying mature hepatic functions.

Host and HBV Interactions and Their Potential Impact on Clinical Outcomes

Hepatitis B virus (HBV) is a challenge for global health services, affecting millions and leading thousands to end-stage liver disease each year. This comprehensive review explores the interactions between HBV and the host, examining their impact on clinical outcomes. HBV infection encompasses a spectrum of severity, ranging from acute hepatitis B to chronic hepatitis B, which can potentially progress to cirrhosis and hepatocellular carcinoma (HCC). Occult hepatitis B infection (OBI), characterized by low HBV DNA levels in hepatitis B surface antigen-negative individuals, can reactivate and cause acute hepatitis B. HBV genotyping has revealed unique geographical patterns and relationships with clinical outcomes. Moreover, single nucleotide polymorphisms (SNPs) within the human host genome have been linked to several clinical outcomes, including cirrhosis, HCC, OBI, hepatitis B reactivation, and spontaneous clearance. The immune response plays a key role in controlling HBV infection by eliminating infected cells and neutralizing HBV in the bloodstream. Furthermore, HBV can modulate host metabolic pathways involved in glucose and lipid metabolism and bile acid absorption, influencing disease progression. HBV clinical outcomes correlate with three levels of viral adaptation. In conclusion, the clinical outcomes of HBV infection could result from complex immune and metabolic interactions between the host and HBV. These outcomes can vary among populations and are influenced by HBV genotypes, host genetics, environmental factors, and lifestyle. Understanding the degrees of HBV adaptation is essential for developing region-specific control and prevention measures.

Bile acid increase during bulevirtide treatment of hepatitis D is not associated with a decline in HDV RNA

Bulevirtide (BLV) is an entry inhibitor blocking entry of HBsAg into hepatocytes by interfering with the bile acid transporter Na+-taurocholate co-transporting polypeptide. We here investigated if bile acid levels before or during BLV treatment would correlate with HDV RNA declines. We studied 20 patients with compensated HDV infection receiving a daily dose of 2 mg bulevirtide subcutaneously qd for at least 24 weeks. ALT levels improved in all patients including 13/20 patients showing normal ALT values at treatment Week 24. An HDV RNA drop of at least 50% was evident in 20/20 patients at Week 24 including 10 patients showing a ≥ 2 log HDV RNA decline. Elevated bile acid levels were detected already before treatment in 10 patients and further increased during BLV administration with different kinetics. Baseline bile acids were associated with higher transient elastography values (p = .0029) and evidence of portal hypertension (p = .0004). Bile acid levels before treatment were associated with HDV RNA declines throughout therapy, but not at Week 24 (rho = -0.577; p = .0078; rho = -0.635, p = .0026; rho = -0.577, p = .0077; rho = -0.519, p = .0191; rho = -0.564, p = .0119 and rho = -0.393, p = .087 at treatment Weeks 2, 8, 12, 16, 20 and 24, respectively). However, bile acid increases during treatment were not associated with HDV RNA or ALT declines at any of the time points. BLV-induced increases in bile salts do not correlate with HDV RNA declines suggesting that the inhibitory effects of BLV on NTCP differ between blocking bile acid transport and hindering HBsAg entry. If baseline bile salt levels could be useful to predict virological response remains to be confirmed.

LINC00659 Inhibits Hepatocellular Carcinoma Malignant Progression by Blocking Aerobic Glycolysis through FUS Recruitment and SLC10A1 Modulation

Hepatocellular carcinoma (HCC) is a malignant type of liver cancer that poses severe threat to human health worldwide. Aerobic glycolysis is a hallmark of HCC and facilitates its progression. Solute carrier family 10 member 1 (SLC10A1) and long intergenic non-protein coding RNA 659 (LINC00659) were detected to be downregulated in HCC cells, yet their potential functions underlying HCC progression remained unidentified. In the current work, colony formation and transwell assays were used to detect HCC cells (HepG2 and HuH-7) proliferation and migration in vitro study. The quantitative real-time polymerase chain reaction (qRT-PCR) and western blot assays were used for gene/protein expression determination. Seahorse assay was performed for aerobic glycolysis assessment. RNA immunoprecipitation (RIP) and RNA pull-down assays were conducted for detection of the molecular interaction between LINC00659 and SLC10A1. The results showed that overexpressed SLC10A1 significantly suppressed the proliferation, migration, and aerobic glycolysis in HCC cells. Mechanical experiments further demonstrated that LINC00659 positively regulated SLC10A1 expression in HCC cells by recruiting fused protein in sarcoma (FUS). Our work elucidated that LINC00659 inhibited HCC progression and aerobic glycolysis via the FUS/SLC10A1 axis, revealing a novel lncRNA-RNA-binding protein-mRNA network in HCC, which might provide potential therapeutic targets for HCC.

Genetic Variants within SARS-CoV-2 Human Receptor Genes May Contribute to Variable Disease Outcomes in Different Ethnicities

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into a global pandemic, with an alarming infectivity and mortality rate. Studies have examined genetic effects on SARS-CoV-2 disease susceptibility and severity within Eurasian populations. These studies identified contrasting effects on the severity of disease between African populations. Genetic factors can explain some of the diversity observed within SARS-CoV-2 disease susceptibility and severity. Single nucleotide polymorphisms (SNPs) within the SARS-CoV-2 receptor genes have demonstrated detrimental and protective effects across ethnic groups. For example, the TT genotype of rs2285666 (Angiotensin-converting enzyme 2 (ACE2)) is associated with the severity of SARS-CoV-2 disease, which is found at higher frequency within Asian individuals compared to African and European individuals. In this study, we examined four SARS-CoV-2 receptors, ACE2, Transmembrane serine protease 2 (TMPRSS2), Neuropilin-1 (NRP1), and Basigin (CD147). A total of 42 SNPs located within the four receptors were reviewed: ACE2 (12), TMPRSS2 (10), BSG (CD147) (5), and NRP1 (15). These SNPs may be determining factors for the decreased disease severity observed within African individuals. Furthermore, we highlight the absence of genetic studies within the African population and emphasize the importance of further research. This review provides a comprehensive summary of specific variants within the SARS-CoV-2 receptor genes, which can offer a better understanding of the pathology of the SARS-CoV-2 pandemic and identify novel potential therapeutic targets.

Interactions of Na+/taurocholate cotransporting polypeptide with host cellular proteins upon hepatitis B and D virus infection: novel potential targets for antiviral therapy

Na⁺/taurocholate cotransporting polypeptide (NTCP) is a member of the solute carrier (SLC) family 10 transporters (gene symbol SLC10A1) and is responsible for the sodium-dependent uptake of bile salts across the basolateral membrane of hepatocytes. In addition to its primary transporter function, NTCP is the high-affinity hepatic receptor for hepatitis B (HBV) and hepatitis D (HDV) viruses and, therefore, is a prerequisite for HBV/HDV virus entry into hepatocytes. The inhibition of HBV/HDV binding to NTCP and internalization of the virus/NTCP receptor complex has become a major concept in the development of new antiviral drugs called HBV/HDV entry inhibitors. Hence, NTCP has emerged as a promising target for therapeutic interventions against HBV/HDV infections in the last decade. In this review, recent findings on protein-protein interactions (PPIs) between NTCP and cofactors relevant for entry of the virus/NTCP receptor complex are summarized. In addition, strategies aiming to block PPIs with NTCP to dampen virus tropism and HBV/HDV infection rates are discussed. Finally, this article suggests novel directions for future investigations evaluating the functional contribution of NTCP-mediated PPIs in the development and progression of HBV/HDV infection and subsequent chronic liver disorders.

Structure of the bile acid transporter and HBV receptor NTCP

Chronic infection with hepatitis B virus (HBV) affects more than 290 million people worldwide, is a major cause of cirrhosis and hepatocellular carcinoma, and results in an estimated 820,000 deaths annually^1,2. For HBV infection to be established, a molecular interaction is required between the large glycoproteins of the virus envelope (known as LHBs) and the host entry receptor sodium taurocholate co-transporting polypeptide (NTCP), a sodium-dependent bile acid transporter from the blood to hepatocytes³. However, the molecular basis for the virus-transporter interaction is poorly understood. Here we report the cryo-electron microscopy structures of human, bovine and rat NTCPs in the apo state, which reveal the presence of a tunnel across the membrane and a possible transport route for the substrate. Moreover, the cryo-electron microscopy structure of human NTCP in the presence of the myristoylated preS1 domain of LHBs, together with mutation and transport assays, suggest a binding mode in which preS1 and the substrate compete for the extracellular opening of the tunnel in NTCP. Our preS1 domain interaction analysis enables a mechanistic interpretation of naturally occurring HBV-insusceptible mutations in human NTCP. Together, our findings provide a structural framework for HBV recognition and a mechanistic understanding of sodium-dependent bile acid translocation by mammalian NTCPs.

Genetic variants of NTCP gene and hepatitis B vaccine failure in Taiwanese children of hepatitis B e antigen positive mothers

BACKGROUND AND AIMS

Hepatitis B virus (HBV) vaccine failure remains a hurdle to the global elimination of HBV infections in the vaccination era. We aimed to elucidate the relationships between HBV entry receptor sodium taurocholate co-transporting polypeptide (NTCP) and vaccine failure in children born to highly infectious mothers.

METHODS

The genetic variants rs7154439, rs4646285, rs4646287, and rs2296651 were genotyped in 170 children with chronic HBV infections and 138 control children of mothers positive for hepatitis B e antigen (HBeAg). All children received hepatitis B immunoglobulin and complete HBV vaccination. Total RNAs from 82 adult non-tumor liver tissues were quantified for NTCP, type I interferons and interferon-induced transmembrane protein 3 (IFITM3) levels.

RESULTS

A higher rate of the GA/AA genotype (28.3% vs. 15.3%, p = 0.006) of the genetic variant rs4646287 in intron 1 of the NTCP gene was detected in control children compared to the carrier children. The rs4646287 G > A genotype was associated with younger ages at which spontaneous HBeAg seroconversion occurred (10.8 ± 8.4 vs. 14.6 ± 8.7 years, p = 0.003) in chronic HBV-infected children. Unique correlation patterns of NTCP and innate immunity-related genes (type I interferons and IFITM3) were found in HBV-infected liver tissues with the rs4646287 G > A genotype.

CONCLUSION

The rs4646287 G > A genotype of the NTCP gene may be associated with lower risk for HBV vaccine failure in children born to highly infectious mothers. The protective effect of rs4646287 G > A was also present in carrier children, evidenced by earlier spontaneous HBeAg seroconversion.

Efficacy and Safety of Bulevirtide plus Tenofovir Disoproxil Fumarate in Real-World Patients with Chronic Hepatitis B and D Co-Infection

Background: The hepatitis B and D virus (HBV/HDV) hepatocyte entry inhibitor bulevirtide (BLV) has been available in Europe since July 2020, after the registrational trial MYR202. Real-life data on the efficacy and safety of BLV are sparse. Methods: We have analysed the course of treatment with BLV (2 mg/day) plus tenofovir disoproxil fumarate (TDF) (245 mg/day) in patients with chronic hepatitis delta (CHD). Virologic (≥2 log reduction in HDV RNA or suppression of HDV RNA below the lower limit of detection) and biochemical (normalisation of serum ALT) treatment responses after 24 weeks were defined according to the MYR202 trial. Results: Seven patients were recruited (four with liver cirrhosis Child−Pugh A). After 24 weeks, a virologic response was observed in five of seven and a biochemical response was seen in three of six patients with elevated serum ALT at baseline. Extended treatment data > 48 weeks were available in three cases: two presented with continuous virologic and biochemical responses and in one individual an HDV-RNA breakthrough was observed. Adverse effects were not recorded. Conclusions: The first real-life data of the approved dosage of 2 mg of BLV in combination with TDF confirm the safety, tolerability, and efficacy of the registrational trial MYR202 for a treatment period of 24 weeks and beyond.

Regulation of the HBV Entry Receptor NTCP and its Potential in Hepatitis B Treatment

Hepatitis B virus (HBV) is a globally prevalent human DNA virus responsible for more than 250 million cases of chronic liver infection, a condition that can lead to liver inflammation, cirrhosis, and hepatocellular carcinoma. Sodium taurocholate co-transporting polypeptide (NTCP), a transmembrane protein highly expressed in human hepatocytes and a mediator of bile acid transport, has been identified as the receptor responsible for the cellular entry of both HBV and its satellite, hepatitis delta virus (HDV). This has led to significant advances in our understanding of the HBV life cycle, especially the early steps of infection. HepG2-NTCP cells and human NTCP-expressing transgenic mice have been employed as the primary cell culture and animal models, respectively, for the study of HBV, and represent valuable approaches for investigating its basic biology and developing treatments for infection. However, the mechanisms involved in the regulation of NTCP transcription, translation, post-translational modification, and transport are still largely elusive. Improvements in our understanding of NTCP biology would likely facilitate the design of new therapeutic drugs for the prevention of the de novo infection of naïve hepatocytes. In this review, we provide critical findings regarding NTCP biology and discuss important questions that remain unanswered.

Genetically edited hepatic cells expressing the NTCP-S267F variant are resistant to hepatitis B virus infection

The sodium-dependent taurocholate co-transporting polypeptide (NTCP)-S267F variant is known to be associated with a reduced risk of hepatitis B virus (HBV) infection and disease progression. The NTCP-S267F variant displays diminished function in mediating HBV entry, but its function in HBV infection has not been fully established in more biologically relevant models. We introduced the NTCP-S267F variant and tested infectivity by HBV in genetically edited hepatic cells. HepG2-NTCP clones with both homozygous and heterozygous variants were identified after CRISPR base editing. NTCP-S267F homozygous clones did not support HBV infection. The heterozygote clones behaved similarly to wild-type clones. We generated genetically edited human stem cells with the NTCP-S267F variant, which differentiated equally well as wild-type into hepatocyte-like cells (HLCs) expressing high levels of hepatocyte differentiation markers. We confirmed that HLCs with homozygous variant did not support HBV infection, and heterozygous variant clones were infected with HBV equally as well as the wild-type cells. In conclusion, we successfully introduced the S267F variant by CRISPR base editing into the NTCP/SLC10A gene of hepatocytes, and showed that the variant is a loss-of-function mutation. This technology of studying genetic variants and their pathogenesis in a natural context is potentially valuable for therapeutic intervention against HBV.

Na+-Taurocholate Co-Transporting Polypeptide (NTCP) in Livers, Function, Expression Regulation, and Potential in Hepatitis B Treatment

Chronic hepatitis B virus (HBV) infection has become one of the leading causes of liver cirrhosis and hepatocellular carcinoma globally. The discovery of sodium taurocholate co-transporting polypeptide (NTCP), a solute carrier, as a key receptor for HBV and hepatitis D virus (HDV) has opened new avenues for HBV treatment. Additionally, it has led researchers to generate hepatoma cell lines (including HepG2-NTCP and Huh-7-NTCP) susceptible to HBV infection in vitro, hence, paving the way to develop and efficiently screen new and novel anti-HBV drugs. This review summarizes the history, function and critical findings regarding NTCP as a viral receptor for HBV/HDV, and it also discusses recently developed drugs targeting NTCP.

Association Analysis of Genetic Variants of Sodium Taurocholate Co-Transporting Polypeptide NTCP Gene (SLC10A1) and HBV Infection Status in a Cohort of Egyptian Patients

Background: Single nucleotide polymorphisms (SNPs) in the SLC10A1 gene, coding for a functional receptor of hepatitis B virus (HBV), sodium taurocholate co-transporting polypeptide (NTCP), may influence the susceptibility, outcome, and disease course of HBV infection in some populations. Aim: to determine the prevalence of SNPs of the NTCP gene, rs2296651 and rs943277, and their relationship with chronic HBV infection in a group of Egyptian patients. Methods: One hundred and thirty seven patients with HBV and 65 healthy controls were enrolled, and the patients were divided into two groups; group I chronic HBV infection (68 patients with normal ALT and minimal or no liver necroinflammation or fibrosis) and group II chronic hepatitis B (69 patients with elevated ALT and moderate or severe liver necroinflammation). They were subjected to full history taking, clinical examination, laboratory investigations, abdominal ultrasound, and liver stiffness measurement using both Echosens® Fibroscan and acoustic radiation force impulse (ARFI). A real time PCR TaqMan 5′ allelic discrimination assay was applied to detect the SNPs in the NTCP gene, rs2296651 and rs943277. Results: On studying the rs2296651 variant, all controls and patients had genotype GG without any significant association with HBV infection or disease progression. However, the rs943277 variant in all controls and 98% of patients had genotype GA, except for two chronic HBV infection patients who had genotype AA, but no significant difference between patients and controls was found. The non-invasive methods for liver fibrosis assessment ARFI, AST/platelet’s ratio (APRI), and fibrosis-4 score (FIB-4) could predict the stages of fibrosis in agreement with Fibroscan with AUCOR 0.8, 0.79, and 0.76, respectively. Conclusion: These findings may suggest that there is no relation between these SNPs of the NTCP gene and the susceptibility or chronicity of HBV infection in the Egyptian population. We also suggest that the use of the non-invasive methods for liver fibrosis assessment, ARFI, FIB-4, and APRI, may decrease the need for liver biopsies in the prediction of significant hepatic fibrosis in chronic HBV patients.

Entry of hepatitis B virus: going beyond NTCP to the nucleus

Hepatitis B virus (HBV) infection remains a major cause of liver diseases and hepatocellular carcinoma. HBV infection begins by low-affinity attachment to hepatocytes and subsequent binding with a specific receptor sodium taurocholate cotransporting polypeptide (NTCP) on sinusoidal-basolateral side of liver parenchymal cells. Following internalization with an unclear mechanism, HBV undergoes uncoating, capsid disassembling and culminates in delivering its genome into the nucleus and forms the covalently closed circular (ccc) DNA. In this review, we briefly summarize the current understanding of HBV entry and discuss some unanswered questions along the entry pathway beyond NTCP binding into the nucleus.

Viral hepatitis update: Progress and perspectives

Viral hepatitis, secondary to infection with hepatitis A, B, C, D, and E viruses, are a major public health problem and an important cause of morbidity and mortality. Despite the huge medical advances achieved in recent years, there are still points of conflict concerning the pathogenesis, immune response, development of new and more effective vaccines, therapies, and treatment. This review focuses on the most important research topics that deal with issues that are currently being solved, those that remain to be solved, and future research directions. For hepatitis A virus we will address epidemiology, molecular surveillance, new susceptible populations as well as environmental and food detections. In the case of hepatitis B virus, we will discuss host factors related to disease, diagnosis, therapy, and vaccine improvement. On hepatitis C virus, we will focus on pathogenesis, immune response, direct action antivirals treatment in the context of solid organ transplantation, issues related to hepatocellular carcinoma development, direct action antivirals resistance due to selection of resistance-associated variants, and vaccination. Regarding hepatitis D virus, we describe diagnostic methodology, pathogenesis, and therapy. Finally, for hepatitis E virus, we will address epidemiology (including new emerging species), diagnosis, clinical aspects, treatment, the development of a vaccine, and environmental surveillance.

Targeting the Four Pillars of Enterohepatic Bile Salt Cycling; Lessons From Genetics and Pharmacology

Bile salts play a pivotal role in lipid homeostasis, are sensed by specialized receptors, and have been implicated in various disorders affecting the gut or liver. They may play a role either as culprit or as potential panacea. Four very efficient transporters mediate most of the hepatic and intestinal bile salt uptake and efflux, and are each essential for the efficient enterohepatic circulation of bile salts. Starting from the intestinal lumen, conjugated bile salts cross the otherwise impermeable lipid bilayer of (primarily terminal ileal) enterocytes through the apical sodium-dependent bile acid transporter (gene SLC10A2) and leave the enterocyte through the basolateral heteromeric organic solute transporter, which consists of an alpha and beta subunit (encoded by SLC51A and SLC51B). The Na+ -taurocholate cotransporting polypeptide (gene SLC10A1) efficiently clears the portal circulation of bile salts, and the apical bile salt export pump (gene ABCB11) pumps the bile salts out of the hepatocyte into primary bile, against a very steep concentration gradient. Recently, individuals lacking either functional Na+ -taurocholate cotransporting polypeptide or organic solute transporter have been described, completing the quartet of bile acid transport deficiencies, as apical sodium-dependent bile acid transporter and bile salt export pump deficiencies were already known for years. Novel pathophysiological insights have been obtained from knockout mice lacking functional expression of these genes and from pharmacological transporter inhibition in mice or humans. Conclusion: We provide a concise overview of the four main bile salt transport pathways and of their status as possible targets of interventions in cholestatic or metabolic disorders.

Long-term trans-inhibition of the hepatitis B and D virus receptor NTCP by taurolithocholic acid

Human hepatic bile acid transporter Na⁺/taurocholate cotransporting polypeptide (NTCP) represents the liver-specific entry receptor for the hepatitis B and D viruses (HBV/HDV). Chronic hepatitis B and D affect several million people worldwide, but treatment options are limited. Recently, HBV/HDV entry inhibitors targeting NTCP have emerged as promising novel drug candidates. Nevertheless, the exact molecular mechanism that NTCP uses to mediate virus binding and entry into hepatocytes is still not completely understood. It is already known that human NTCP mRNA expression is downregulated under cholestasis. Furthermore, incubation of rat hepatocytes with the secondary bile acid taurolithocholic acid (TLC) triggers internalization of the rat Ntcp protein from the plasma membrane. In the present study, the long-term inhibitory effect of TLC on transport function, HBV/HDV receptor function, and membrane expression of human NTCP were analyzed in HepG2 and human embryonic kidney (HEK293) cells stably overexpressing NTCP. Even after short-pulse preincubation, TLC had a significant long-lasting inhibitory effect on the transport function of NTCP, but the NTCP protein was still present at the plasma membrane. Furthermore, binding of the HBV/HDV myr-preS1 peptide and susceptibility for in vitro HDV infection were significantly reduced by TLC preincubation. We hypothesize that TLC rapidly accumulates in hepatocytes and mediates long-lasting trans-inhibition of the transport and receptor function of NTCP via a particular TLC-binding site at an intracellularly accessible domain of NTCP. Physiologically, this trans-inhibition might protect hepatocytes from toxic overload of bile acids. Pharmacologically, it provides an interesting novel NTCP target site for potential long-acting HBV/HDV entry inhibitors.NEW & NOTEWORTHY The hepatic bile acid transporter NTCP is a high-affinity receptor for hepatitis B and D viruses. This study shows that TLC rapidly accumulates in NTCP-expressing hepatoma cells and mediates long-lasting trans-inhibition of NTCP's transporter and receptor function via an intracellularly accessible domain, without substantially affecting its membrane expression. This domain is a promising novel NTCP target site for pharmacological long-acting HBV/HDV entry inhibitors.

Epidemiology of Virus Infection and Human Cancer

Seven viruses including the Epstein-Barr virus (EBV), hepatitis B virus (HBV), hepatitis C virus (HCV), Kaposi's sarcoma herpes virus (KSHV), human immunodeficiency virus, type-1 (HIV-1), human T cell lymphotrophic virus, type-1 (HTLV-1), and human papillomavirus (HPV) have been classified as Group 1 human carcinogens by the International Agency for Research on Cancer (IARC). The conclusions are based on the findings of epidemiological and mechanistic studies. EBV, HPV, HTLV-1, and KSHV are direct carcinogens; HBV and HCV are indirect carcinogens through chronic inflammation; and HIV-1 is an indirect carcinogen through immune suppression. Some viruses may cause more than one cancer, while some cancers may be caused by more than one virus. However, only a proportion of persons infected by these oncogenic viruses will develop specific cancers. A series of studies have been carried out to assess the viral, host, and environmental cofactors of EBV-associated nasopharyngeal carcinoma, HBV/HCV-associated hepatocellular carcinoma, and HPV-associated cervical carcinoma. Persistent infection, high viral load, and viral genotype are important risk predictors of these virus-caused cancers. Risk calculators incorporating host and viral risk predictors have been developed for the prediction of long-term risk of hepatocellular carcinoma, nasopharyngeal carcinoma and cervical cancer. These risk calculators are useful for the triage and clinical management of infected patients. Both clinical trials and national programs of immunization, antiviral therapy and screening have demonstrated a significant reduction in the incidence of cancers caused by HBV, HCV, and HPV. Future research on gene-gene and gene-environment interactions of oncogenic viruses and the human host using large-scale longitudinal studies with serial measurements of biosignatures are in urgent need.

Potent and Specific Inhibition of NTCP-Mediated HBV/HDV Infection and Substrate Transporting by a Novel, Oral-Available Cyclosporine A Analogue

Analogues of the natural product cyclosporine A (CsA) were developed and assessed as antivirals against infection of hepatitis B virus (HBV) and its satellite hepatitis D virus (HDV). An analogue termed 27A exhibits potent inhibition of HBV/HDV infection by specifically blocking viral engagement to its cellular receptor NTCP, while it lacks immunosuppressive activity found in natural CsA. Intraperitoneal injection or oral intake of 27A protects HDV-susceptible mouse model from HDV infection. 27A serves as a promising lead for the development of novel anti-HDV/HBV agents.

Human genetic susceptibility to hepatitis B virus infection

Hepatitis B virus (HBV) infection is still a serious health threat worldwide. The outcomes of HBV infection consist of spontaneous HBV clearance and chronic HBV infection. Multiple factors contribute to the disparity of HBV infection outcomes, including host factors, viral factors and environmental factors. The present review comprehends the current researches mainly focusing on the relationships between genetic determinants, including single nucleotide polymorphisms (SNPs) and haplotypes, and susceptibility of HBV infection, namely chronic (persistent) HBV infection and HBV clearance. A number of determinants in the chromosomes, including mutations in human leukocyte antigens (HLAs), cytokines genes, toll-like receptors (TLRs), and other genes are related to the human susceptibility to HBV infection. Among the above variants, some of those in HLAs have been studied and replicated in multiple-ethnic populations and came to consistent conclusions, while some others are novel and need to be evaluated further.

Animal models for the study of human hepatitis B and D virus infection: New insights and progress

Hepatitis B virus (HBV) is a member of the Hepadnaviridae family and infects hepatocytes, leading to liver pathology in acutely and chronically infected individuals. Co-infection with Hepatitis D virus (HDV), which requires the surface proteins of HBV to replicate, can exacerbate this disease progression. Thus, the >250 million people living with chronic HBV infection, including 13 million co-infected with HDV, would significantly benefit from an effective and affordable curative treatment. Animal models are crucial to the development of innovative disease therapies, a paradigm repeated again and again throughout the fields of immunology, neurology, reproduction, and development. Unfortunately, HBV has a highly-restricted species tropism, infecting limited species including humans, chimpanzees, and treeshrews. The first experimentally controlled studies of HBV infection were following inoculation of human volunteers in 1942, which identified the transmissibility of hepatitis through serum transfer and led to the hypothesis that the etiological agent was viral. Subsequent research in chimpanzees (Desmyter et al., 1971; Lichter, 1969) and later in other species, such as the treeshrews (Walter et al., 1996; Yan et al., 1996), further confirmed the viral origin of hepatitis B. Shortly thereafter, HBV-like viral infections were identified in woodchucks (Summers et al., 1978; Werner et al., 1979) and ducks, and much of our understanding of HBV replication can be attributed to these important models. However, with the exodus of chimpanzees from research and the limited reagents and historical data for treeshrews and other understudied species, there remains an urgent need to identify physiologically relevant models of chronic HBV infection. While large strides have been made in generating such models, particularly over the past two decades, there is still no available model that faithfully recapitulates the immunity and pathogenesis of HBV infection. Here, we discuss recent advancements in the generation of murine and non-human primate (NHP) models of HBV/HDV infection.

NTCP gene polymorphisms and hepatitis B virus infection status in a Ghanaian population

BACKGROUND

SLC10A1 gene codes NTCP, a receptor through which the hepatitis B virus (HBV) gets access into hepatocytes - a stage of the viral cycle necessary for replication. Polymorphism variants of SLC10A1 play roles in HBV infection, viral clearance, treatment outcome, and complications, in diverse ethnic groups and countries. However, no such study has been conducted in the Ghanaian population, a country with HBV endemicity. Therefore, an exploratory study was conducted to investigate the presence of three (3) single nucleotide polymorphisms (SNPs) in the SLC10A1 gene (rs2296651, rs61745930, and rs4646287) and assessed the risk of HBV infection among the Ghanaian population.

METHOD

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to determine the presence of the SNPs among 292 participants comprising 146 HBV infected persons as case-subjects and 146 HBV non-infected persons as control-subjects.

RESULTS

The minor allele frequency (T) of rs2296651 was present in a significantly high proportion of cases compared with the control group (11.6% vs. 3.1%, p < 0.0001). The homozygote recessive variant of rs61745930 was present in 2.7% of the control group and 5.5% of the case group. Moreover, the minor allele frequencies of rs4646287 were 9.3 and 8.2% among the control and the case group, respectively (p = 0.767). Under the dominant (CC) genetic model of inheritance, rs2296651 was found to be protective of HBV infection [OR = 0.18 (0.07-0.44)], whereas under the co-dominant and additive model, rs2296651 was a potential risk factor for HBV infection [OR = 5.2 (95%CI: 2.1-12.8); 3.5 (95%CI: 1.6-7.6], respectively. Variants of rs61745930 and rs4646287 were not associated with HBV infection (p > 0.05). Polymorphisms in SLC10A1, however, did not show any significant association with HBV infectivity (p > 0.05).

CONCLUSION

The study highlights some polymorphism proof that variants rs2296651, rs61745930, and rs4646287 exist in HBV-infected individuals in Ghana. Although variant rs2296651 was found to be associated with HBV infection, this association warrants more studies. Polymorphisms in SLC10A1 were not associated with HBV infectivity among the Ghanaian population. Further investigation is warranted to assess the offensive role of the relationship between rs2296651 and HBV infectivity.

Metabolomics study of the metabolic changes in hepatoblastoma cells in response to NTCP/SLC10A1 overexpression

NTCP (SLC10A1) has been well recognized as a basolateral (sinusoidal) Na+-bile acid co-transporter that mediates the hepatic uptake of bile acids. However, little is known about the effects of NTCP (SLC10A1) on hepatoblastoma (HB) and its underlying metabolic mechanisms. In this study, we found that NTCP (SLC10A1) expression was downregulated in HB cells and tissues, and it was demonstrated that NTCP (SLC10A1) reduced cell viability, promoted cell cycle arrest and induced apoptosis of HB cells. The metabolic profiles of HB cells with NTCP (SLC10A1) overexpression were further examined to determine their biochemical alterations and deepen our understanding on the metabolic regulation of NTCP (SLC10A1) overexpression. The metabolomics study based on ultra performance liquid chromatography-mass spectrometry revealed alterations in the metabolites of HB cells following NTCP (SLC10A1) overexpression. Next, we stably overexpressed NTCP (SLC10A1) in HepG2 cells, and found that NTCP (SLC10A1)-overexpressing cells could inhibit the production of adenosine and decreased both mRNA and protein levels of HIF1α. Further overexpression of HIF1α in the NTCP (SLC10A1)-overexpression group restored the production of adenosine. Collectively, these findings provide strong evidence that NTCP (SLC10A1) overexpression significantly disrupts the metabolism of adenosine in HB cells and highlight that NTCP (SLC10A1) mediates adenosine production mainly through HIF1α.

Inhibition of Hepatic Bile Acid Uptake by Myrcludex B Promotes Glucagon-Like Peptide-1 Release and Reduces Obesity

BACKGROUND & AIMS

Bile acids are important metabolic signaling molecules. Bile acid receptor activation promotes body weight loss and improves glycemic control. The incretin hormone GLP-1 and thyroid hormone activation of T4 to T3 have been suggested as important contributors. Here, we identify the hepatic bile acid uptake transporter Na⁺ taurocholate co-transporting polypeptide (NTCP) as target to prolong postprandial bile acid signaling.

METHODS

Organic anion transporting polypeptide (OATP)1a/1b KO mice with or without reconstitution with human OATP1B1 in the liver were treated with the NTCP inhibitor Myrcludex B for 3.5 weeks after the onset of obesity induced by high fat diet-feeding. Furthermore, radiolabeled T4 was injected to determine the role of NTCP and OATPs in thyroid hormone clearance from plasma.

RESULTS

Inhibition of NTCP by Myrcludex B in obese Oatp1a/1b KO mice inhibited hepatic clearance of bile acids from portal and systemic blood, stimulated GLP-1 secretion, reduced body weight, and decreased (hepatic) adiposity. NTCP inhibition did not affect hepatic T4 uptake nor lead to increased thyroid hormone activation. Myrcludex B treatment increased fecal energy output, explaining body weight reductions amongst unaltered food intake and energy expenditure.

CONCLUSIONS

Pharmacologically targeting hepatic bile acid uptake to increase bile acid signaling is a novel approach to treat obesity and induce GLP1- secretion.

The role of IL22 polymorphisms on liver cirrhosis in patients with hepatitis B virus: A case control study

AIMS

Interleukin(IL)-22 plays an important role in promoting liver regeneration and repair, but its role in chronic HBV-related liver diseasesis not clear. The goal of this study was to evaluate associations between eight IL22 single nucleotide polymorphisms (SNPs) and the development of chronic HBV cirrhosis and HBV-related HCC within a Chinese Han population.

METHODS

We investigated associations between single nucleotide polymorphisms (SNPs) in the IL22 gene (rs1026788, rs2227472, rs2227491, rs2227485, rs1179249, rs2046068,rs2227473, and rs7314777) and the risk of HBV-related chronic liver diseases within a Han population in Northeast China. A total of 649 participants were included in the study, including 103 patients with CHB, 264 patients with LC, and 282 patients with HCC. The odds ratios (OR) and corresponding 95% confidence intervals (CI) were calculated using chi-square test. Haplotype analysis was conducted by haploview software.

RESULTS

Genotype and allele distributions of SNPs rs1179249 and rs2227472 differed between LC and CHB groups (both P < 0.05).The G alleles of SNP rs2227491 and rs1026788 were more frequent in the LC group than in the CHB group (P = 0.046, P = 0.041 respectively). A IL22 haplotype consisting of the minor alleles of SNP rs1179249 and the major alleles of seven other SNPs occurred less frequently in the LC and HCC groups than in the CHB group (28.2%, 33.94%, and 37.86%, respectively, P < 0.05). Moreover, there were no significant associations between smoking or drinking and IL22 SNPs on the risk of HCC (P > 0.05).

CONCLUSION

IL22 genetic variations were associated with chronic HBV infection progression, especially in the HBV-LC group. The IL22 genetic variations may help clinicians initiate the correct treatment strategy at the CHB stage.

SLC10A1 S267F variant influences susceptibility to HBV infection and reduces cholesterol level by impairing bile acid uptake

The SLC10A1 Ser267Phe (S267F) variant has been reported to severely inhibit hepatitis B virus (HBV) infection and taurocholate transport activity. This study aimed to clarify the effects of this variant on HBV infection and bile acid metabolism. SLC10A1 S267F was genotyped in 2907 HBV-exposed subjects (including HBV persistent carriers and spontaneously recovered subjects) and 1364 unexposed subjects (HBV marker-negative subjects), followed by replication I, comprising 914 exposed subjects and 1123 unexposed subjects, and replication II, comprising 355 children born to HBsAg-positive mothers (226 HBV-infected children and 129 controls). Intriguingly, SLC10A1 AA was observed only in the unexposed group, but not in the exposed group. The SLC10A1 A allele consistently decreased HBV infection risk compared with the G allele (OR = 0.76, 95% CI: 0.64-0.90 in combined samples). In addition, children with the SLC10A1 GA genotype had a reduced risk of perinatal transmission (OR = 0.31, 95% CI: 0.14-0.71). Moreover, unexposed subjects with the SLC10A1 AA genotype exhibited decreased serum total cholesterol and low-density lipoprotein cholesterol compared to those with the GG or GA genotypes (P = 2.975 × 10^-4 and 0.004, respectively). The study highlighted the role of the SLC10A1 S267F variant in the loss of the ability to support HBV infection and taurocholate transport activity. Subjects with the AA genotype may escape from HBV infection and present decreased cholesterol levels as a consequence of impaired bile acid uptake.

Association of the S267F variant on NTCP gene and treatment response to pegylated interferon in patients with chronic hepatitis B: a multicentre study

BACKGROUND

Sodium taurocholate co-transporting polypeptide (NTCP) is a cell receptor for HBV. The S267F variant on the NTCP gene is inversely associated with the chronicity of HBV infection, progression to cirrhosis and hepatocellular carcinoma in East Asian populations. The aim of this study was to determine whether the S267F variant was associated with response to pegylated interferon (PEG-IFN) in patients with chronic HBV infection.

METHODS

A total of 257 patients with chronic HBV, treated with PEG-IFN for 48 weeks, were identified from 13 tertiary hospitals included in the hepatitis B database of the Thai Association for the Study of the Liver (THASL).

RESULTS

Of these, 202 patients were infected with HBV genotype C (84.9%); 146 patients were hepatitis B e antigen (HBeAg)-positive (56.8%). Genotypic frequencies of the S267F polymorphism were 85.2%, 14.8% and 0% for the GG, GA and AA genotypes, respectively. S267F GA was associated with sustained alanine aminotransferase (ALT) normalization (OR = 3.25, 95% CI 1.23, 8.61; P=0.02) in HBeAg-positive patients. Patients with S267F variant tended to have more virological response, sustained response with hepatitis B surface antigen (HBsAg) loss at 24 weeks following PEG-IFN treatment. There was no association between the S267F variant and improved patient outcomes in HBeAg-negative patients.

CONCLUSIONS

The S267F variant on the NTCP gene is independently associated with sustained normalization of ALT following treatment with PEG-IFN in patients with HBV infection who are HBeAg-positive. The findings of this study provide additional support for the clinical significance of the S267F variant of NTCP beyond HBV entry.

The Loss-of-Function S267F Variant in HBV Receptor NTCP Reduces Human Risk for HBV Infection and Disease Progression

Background

Sodium taurocholate cotransporting polypeptide (NTCP, SLC10A1) is a hepatocyte receptor for hepatitis B virus (HBV) infection. The natural NTCP S267F variant causes loss of NTCP HBV receptor function. We assessed the association of S267F with HBV resistance, HBV infection clearance, and HBV-related cirrhosis and hepatocellular carcinoma (HCC).

Methods

We tested the effects of S267F in 1117 Han Chinese patients with various HBV infection outcomes using multivariate logistic regression analysis.

Results

The frequency of S267F (T allele) was higher in HBV-resistant healthy controls (n = 179, 4.0%) compared to HBV-infected patients (n = 648, 1.5%); odds ratio (OR) 0.32 (95% confidence interval [CI] 0.15-0.68; P = .003; dominant model). 267F variant genotypes were also associated with reduced risk for cirrhosis (n = 192, 0.5%) and HCC (n = 258, 1.0%) compared to those with chronic HBV infection (n = 202, 3.0%); OR 0.15 (95% CI, 0.03-0.70) and OR 0.21 (95% CI, 0.062-0.72), respectively. There was no association of the S267F variant with spontaneous HBV clearance.

Conclusion

The S267F variant for the HBV cell-entry receptor NTCP was associated with increased resistance to HBV infection and decreased risk for cirrhosis and liver cancer among those with chronic HBV infection.

Host genetic background affects the course of infection and treatment response in patients with chronic hepatitis B

BACKGROUND

Hepatitis B virus (HBV) utilizes proteins encoded by the host to infect hepatocytes and replicate. Recently, several novel host factors have been identified and described as important to the HBV lifecycle. The influence of host genetic background on chronic hepatitis B (CHB) pathogenesis is still poorly understood.

OBJECTIVES

Here, we aimed to investigate the association of NTCP, FXRα, HNF1α, HNF4α, and TDP2 genetic polymorphisms with the natural course of CHB and antiviral treatment response.

STUDY DESIGN

We genotyped 18 single-nucleotide polymorphisms using MALDI-TOF mass spectrometry in 136 patients with CHB and 100 healthy individuals. We investigated associations of the selected polymorphisms with biochemical, serological and hepatic markers of disease progression and treatment response.

RESULTS

No significant differences in genotypic or allelic distribution between CHB and control groups were observed. Within TDP2, rs3087943 variations were associated with treatment response, and rs1047782 modified the risk of advanced liver inflammation. Rs7154439 within NTCP was associated with HBeAg seroconversion after 48 weeks of nucleos(t)ide analogue treatment. HNF1α genotypes were associated with treatment response, liver damage and baseline HBeAg presence. HNF4α rs1800961 predicted PEG-IFNα treatment-induced HBsAg clearance in long-term follow up.

CONCLUSIONS

This study indicates host genetic background relevance in the course of CHB and confirms the role of recently described genes for HBV infection. The obtained results might serve as a starting point for validation studies on the clinical application of selected genetic variants to predict individual risks of CHB-induced liver failure and treatment response.

Design, synthesis and biological evaluation of benzamide derivatives as novel NTCP inhibitors that induce apoptosis in HepG2 cells

Sodium taurocholate cotransport polypeptide (NTCP) plays an important role in the development of hepatitis and acts as a switch to allow hepatitis virus to enter hepatic cells. As the entry receptor protein of hepatitis virus, NTCP is also an effective target for the treatment of hepatocellular carcinoma. Herein, twenty-five benzamide analogues were synthesized based on the virtual screening design and their anti-proliferative activities against HepG2 cells were evaluated in vitro. Compound 35 was found to be promising, with an IC₅₀ value of 2.8 μM. The apoptosis induced by 35 was characterized by the regulation of markers, including an increase in Bax, cleaved-caspase 3, and cleaved-PARP proteins, and a decrease in Bcl-2 protein. Molecular docking and molecular dynamics (MD) simulation confirmed that compound 35 can bind tightly to NTCP. Western blot analysis also showed that NTCP was inhibited. Altogether, these results indicate that compound 35 acts as a novel NTCP inhibitor to induce apoptosis in HepG2 cells.

Host Genetic Determinants of Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection is still a major health problem worldwide. Recently, a great number of genetic studies based on single nucleotide polymorphisms (SNPs) and genome-wide association studies have been performed to search for host determinants of the development of chronic HBV infection, clinical outcomes, therapeutic efficacy, and responses to hepatitis B vaccines, with a focus on human leukocyte antigens (HLA), cytokine genes, and toll-like receptors. In addition to SNPs, gene insertions/deletions and copy number variants are associated with infection. However, conflicting results have been obtained. In the present review, we summarize the current state of research on host genetic factors and chronic HBV infection, its clinical type, therapies, and hepatitis B vaccine responses and classify published results according to their reliability. The potential roles of host genetic determinants of chronic HBV infection identified in these studies and their clinical significance are discussed. In particular, HLAs were relevant for HBV infection and pathogenesis. Finally, we highlight the need for additional studies with large sample sizes, well-matched study designs, appropriate statistical methods, and validation in multiple populations to improve the treatment of HBV infection.

Mechanistic insights into the inhibition of NTCP by myrcludex B

Background & aims

The sodium taurocholate co-transporting polypeptide (NTCP) is the entry receptor for the hepatitis B and delta virus (HBV/HDV) and the main hepatic uptake transporter of conjugated bile acids. Myrcludex B, a synthetic peptide mimicking the NTCP-binding domain of HBV, blocks HBV/HDV infection and inhibits NTCP-mediated bile acid uptake. In humans this increases systemic bile acid levels, which remain elevated for hours even after Myrcludex B is cleared from the circulation. Here, we investigated the dynamics of Myrcludex B-induced NTCP-mediated bile acid transport inhibition in mice and if/how the duration of this effect relates to NTCP protein turnover.

Methods

Plasma bile acids were determined in Myrcludex B-treated OATP1a/1b-deficient mice. In vitro, plasma membrane-resident NTCP was labeled with biotin or fluorescein isothiocyanate (FITC)-labeled Myrcludex B and traced in time using hNTCP-overexpressing U2OS cells. Förster resonance energy transfer by fluorescent lifetime imaging microscopy was used to investigate whether Myrcludex B can transfer to newly synthesized NTCP.

Results

Conjugated bile salt levels in plasma peaked 4 h after subcutaneous Myrcludex B administration. After 24 h, plasma bile salt levels were completely normalized, in line with restored NTCP-mediated bile acid transport in vitro. Biotin-labeled NTCP disappeared faster than Myrcludex B-FITC, with almost 40% of FITC signal remaining after 24 h. FITC fluorescence lifetime was strongly decreased upon expression of DY547-labeled acyl carrier protein-tagged NTCP, demonstrating transfer of pre-bound Myrcludex B-FITC to newly formed NTCP.

Conclusions

The dynamics of NTCP protein turnover and Myrcludex B-induced plasma bile salt elevations are similar, suggesting that the Myrcludex B:NTCP interaction is very long-lived. Nevertheless, Myrcludex B is not completely degraded together with NTCP and can transfer to newly synthesized NTCP.

Lay summary

The experimental drug Myrcludex B binds the sodium taurocholate co-transporting polypeptide (NTCP), the viral entry receptor for the hepatitis B and D virus (HBV/HDV), and thereby prevents infection, but also inhibits hepatic bile salt uptake leading to transiently elevated bile salt levels. This study describes that while the normalization of plasma bile salt levels likely depends on the protein turnover rate of NTCP, Myrcludex B partly escapes co-degradation with NTCP by transferring from one NTCP molecule to another. This is of importance to the HBV/HDV research field as it provides a potential explanation for the distinct kinetics and dose-dependence of Myrcludex B’s effects on viral infection versus bile salt transport.

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Myrcludex B-induced plasma bile salt elevations coincide with NTCP protein turnover.

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NTCP-bound Myrcludex B can transfer from one NTCP molecule to another.

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Transfer to newly synthesized NTCP might extend the inhibitory potential of Myrcludex B.

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50% occupation of NTCP by Myrcludex B is not enough to block bile acid transport.

NTCP deficiency in mice protects against obesity and hepatosteatosis

Bile acids play a major role in the regulation of lipid and energy metabolism. Here we propose the hepatic bile acid uptake transporter Na⁺ taurocholate cotransporting polypeptide (NTCP) as a target to prolong postprandial bile acid elevations in plasma. Reducing hepatic clearance of bile acids from plasma by genetic deletion of NTCP moderately increased plasma bile acid levels, reduced diet-induced obesity, attenuated hepatic steatosis, and lowered plasma cholesterol levels. NTCP and G protein–coupled bile acid receptor–double KO (TGR5–double KO) mice were equally protected against diet-induced obesity as NTCP–single KO mice. NTCP-KO mice displayed decreased intestinal fat absorption and a trend toward higher fecal energy output. Furthermore, NTCP deficiency was associated with an increased uncoupled respiration in brown adipose tissue, leading to increased energy expenditure. We conclude that targeting NTCP-mediated bile acid uptake can be a novel approach to treat obesity and obesity-related hepatosteatosis by simultaneously dampening intestinal fat absorption and increasing energy expenditure.

Targeting bile acid uptake simultaneously dampens intestinal fat absorption and increases energy expenditure, suggesting a potential approach to treat obesity and obesity-related hepatosteatosis.

Association of NTCP polymorphisms with clinical outcome of hepatitis B infection in Thai individuals

BACKGROUND

Single nucleotide polymorphisms (SNPs) in the sodium taurocholate co-transporting polypeptide (NTCP) have been showed to be associated with natural history of hepatitis B virus (HBV) infection. However, it is unclear whether the SNPs are related to the clinical outcome of HBV infection in Thai individuals.

METHODS

The rs2296651 and rs4646287 polymorphisms of NTCP were determined by allelic discrimination using commercial TaqMan probes in blood samples of 1021 Thai individuals. These subjects included 610 patients with chronic HBV infection [CHB, 305 with hepatocellular carcinoma (HCC) and 305 without HCC], 206 subjects with spontaneous HBV clearance and 205 healthy controls who were age and gender-matched.

RESULTS

The frequencies of rs2296651 A minor allele in the CHB group, the HBV clearance group and healthy controls were 7.8, 7.3 and 13.9%, respectively. For rs4646287, the frequencies of T minor allele of the corresponding groups were 10.4, 8.0 and 9.5%, respectively. Compared with healthy controls, the frequencies of rs2296651 GA + AA genotypes were significantly lower in the CHB group (P &lt; 0.001) and in the HBV clearance group (P = 0.001). There was no difference in their distribution between the HBV clearance and CHB groups. Among the CHB group, the distribution of GA + AA genotypes in patients with HCC were significantly lower than in patients without HCC (P = 0.014). The frequencies of HBeAg positivity in patients harboring GG and GA + AA genotypes were 39.8 and 23.5%, respectively (P = 0.004). Among patients with HCC, the mean HBV DNA of the corresponding genotypes were 4.9 ± 1.3 vs. 2.7 ± 1.0 log₁₀ IU/mL, respectively (P &lt; 0.001). There was no difference in genotype and allele frequencies of rs4646287 polymorphism among all studied groups.

CONCLUSIONS

Our results showed that rs2296651 polymorphism was associated with a decreased risk of susceptibility to HBV infection and the development of HCC. These data suggest that the NTCP polymorphism might have an influence on natural history of HBV infection in Thai individuals. This abstract was partly presented at the American Association for the Study of Liver Diseases (AASLD) Meeting 2018, November 9-13, 2018, in San Francisco, CA, USA and was published in Hepatology 2018; 68:1237A-1238A.