Treatment with tenofovir disoproxil fumarate or entecavir in chronic hepatitis B virus-infected patients with renal impairment: results from a 7-year, multicentre retrospective cohort study.

BACKGROUND: Limited data exist regarding tenofovir disoproxil fumarate (TDF) safety and effectiveness in chronic hepatitis B virus-infected (CHB) patients with renal impairment (RI). AIMS: To compare real-world data on renal safety and effectiveness of TDF vs entecavir (ETV) in CHB patients with moderate-to-severe RI. METHODS: Retrospective, non-interventional, cohort study analysing medical records for TDF/ETV-treated CHB patients (54 European centres). Included patients experienced moderate-to-severe RI (creatinine clearance 20-60 mL/min [Cockcroft-Gault]) either before TDF/ETV initiation ('before' subgroup [baseline = treatment initiation]) or after TDF/ETV initiation ('after' subgroup [baseline = first RI occurrence]). The primary objective was TDF safety, particularly renal-related adverse events of special interest (AESI). TDF and ETV safety and effectiveness were compared and multivariate analyses were performed using inverse probability treatment weighting. RESULTS: 'Before' subgroup included 107 TDF- and 91 ETV-treated patients; 'after' subgroup included 212 TDF- and 77 ETV-treated patients. Mean baseline creatinine clearance was higher for TDF- vs ETV-treated patients (both subgroups). Median follow-up was 3.1 years (both treatments). AESI were more frequent with TDF vs ETV ('before': 18.7% vs 8.8%; 'after': 9.9% vs 3.9%); however, differences were not significant by multivariate analysis. Only TDF-treated patients experienced renal tubular dysfunction (6.5% 'before'; 1.9% 'after') as well as renal adverse events leading to treatment discontinuation (8.4% 'before'; 7.1% 'after'). Effectiveness was similar between treatments. CONCLUSIONS: Overall safety was similar for TDF vs ETV (both subgroups). Given that renal tubular dysfunction occurred with TDF and not with ETV, renal safety concerns may be greater with TDF in CHB patients with RI.

Long-term response after stopping tenofovir disoproxil fumarate in non-cirrhotic HBeAg-negative patients - FINITE study.

BACKGROUND & AIMS: There is currently no virological cure for chronic hepatitis B but successful nucleos(t)ide analogue (NA) therapy can suppress hepatitis B virus (HBV) DNA replication and, in some cases, result in HBsAg loss. Stopping NA therapy often leads to viral relapse and therefore life-long therapy is usually required. This study investigated the potential to discontinue tenofovir disoproxil fumarate (TDF) therapy in HBeAg-negative patients. METHODS: Non-cirrhotic HBeAg-negative patients who had received TDF for ≥4years, with suppressed HBV DNA for ≥3.5years, were randomly assigned to either stop (n=21) or continue (n=21) TDF monotherapy. Standard laboratory tests including HBV DNA viral load, HBsAg and alanine aminotransferase (ALT) measurements, and adverse event reporting were carried out during treatment and post-treatment follow-up for 144weeks. RESULTS: Of the patients who stopped TDF therapy, 62% (n=13) remained off-therapy to Week 144. Median HBsAg change in this group was -0.59log10IU/ml (range -4.49 to 0.02log10IU/ml) vs. 0.21log10IU/ml in patients who continued TDF therapy. Four patients (19%) achieved HBsAg loss. Patients stopping therapy had initial fluctuations in viral load and ALT; however, at Week 144, 43% (n=9) had either achieved HBsAg loss or had HBV DNA <2,000IU/ml. There were no unexpected safety issues identified with stopping TDF therapy. CONCLUSIONS: This controlled study demonstrated the potential for HBsAg loss and/or sustained virological response in non-cirrhotic HBeAg-negative patients stopping long-term TDF therapy. Lay summary: Nucleos(t)ide analogue (NA) is usually a life-long therapy for HBV patients. This randomised controlled study investigated the discontinuation of tenofovir disoproxil fumarate (TDF) therapy in HBeAg-negative patients. Of the patients who stopped TDF therapy, 62% remained off-therapy to Week 144, of which 43% of patients had achieved either HBsAg loss or HBV DNA <2,000IU/ml. This offers a potential for long-term HBV-suppressed patients without cirrhosis to stop NA therapy under strict surveillance. Clinical trial number: NCT01320943.

Kupffer cells interact with hepatitis B surface antigen in vivo and in vitro, leading to proinflammatory cytokine production and natural killer cell function.

BACKGROUND: Based on their localization, Kupffer cells (KCs) likely interact with hepatitis B virus (HBV). However, the role of KCs in inducing immunity toward HBV is poorly understood. Therefore, the interaction of hepatitis B surface antigen (HBsAg) and KCs, and possible functional consequences, were assessed. METHODS: KCs in liver tissue from patients with chronic HBV were analyzed for presence of HBsAg and their phenotype, and compared with KCs in control liver tissue. Liver graft perfusate-derived KCs and in vitro-generated monocyte-derived macrophages were investigated for functional interaction with patient-derived HBsAg. RESULTS: Intrahepatic KCs were HBsAg positive and more activated than those from control livers. KCs internalized HBsAg in vitro, which did not change their phenotype, but strongly induced proinflammatory cytokine production. Additionally, monocyte-derived macrophages also interacted with HBsAg, leading to activation and cytokine production. Furthermore, HBsAg-exposed macrophages and KC activated natural killer (NK) cells, resulting in increased CD69 expression and interferon-γ production. CONCLUSIONS: KCs directly interact with HBsAg in vivo and in vitro. HBsAg-induced cytokine production by KCs and monocyte-derived macrophages and subsequent NK cell activation may be an early event in viral containment and may support induction of HBV-specific immunity upon HBV infection, but may also contribute to liver pathology.

Assessment of the effect of ribavirin on myeloid and plasmacytoid dendritic cells during interferon-based therapy of chronic hepatitis B patients.

The combination of ribavirin and peginterferon is the current standard of anti-viral treatment for chronic HCV patients. However, little is known on the mode of action of ribavirin in the anti-viral treatment of HCV patients. To investigate the immunomodulatory mechanism of ribavirin, we studied peginterferon alone versus peginterferon and ribavirin in chronic HBV patients. The addition of ribavirin did not affect the number of myeloid dendritic cells (mDC) or plasmacytoid dendritic cells (pDC), nor did it enhance T-helper-1 cell activity or T-cell proliferation. In contrast, it increased upregulation of activation markers on mDC and pDC, which was sustained throughout treatment. However, the addition of ribavirin had no effect on IFNα production by pDC. Our findings demonstrate that, although ribavirin does not lead to a viral load decline, in vivo treatment with ribavirin affects the activation of pDC and mDC in chronic HBV patients.

Hepatitis B virus lacks immune activating capacity, but actively inhibits plasmacytoid dendritic cell function.

Chronic hepatitis B virus (HBV) infection is caused by inadequate anti-viral immunity. Activation of plasmacytoid dendritic cells (pDC) leading to IFNα production is important for effective anti-viral immunity. Hepatitis B virus (HBV) infection lacks IFNα induction in animal models and patients and chronic HBV patients display impaired IFNα production by pDC. Therefore, HBV and HBV-derived proteins were examined for their effect on human pDC in vitro. In addition, the in vitro findings were compared to the function of pDC derived from chronic HBV patients ex vivo. In contrast to other viruses, HBV did not activate pDC. Moreover, HBV and HBsAg abrogated CpG-A/TLR9-induced, but not Loxoribine/TLR7-induced, mTOR-mediated S6 phosphorylation, subsequent IRF7 phosphorylation and IFNα gene transcription. HBV/HBsAg also diminished upregulation of co-stimulatory molecules, production of TNFα, IP-10 and IL-6 and pDC-induced NK cell function, whereas TLR7-induced pDC function was hardly affected. In line, HBsAg preferentially bound to TLR9-triggered pDC demonstrating that once pDC are able to bind HBV/HBsAg, the virus exerts its immune regulatory effect. HBV not only directly interfered with pDC function, but also indirectly by interfering with monocyte-pDC interaction. Also HBeAg diminished pDC function to a certain extent, but via another unknown mechanism. Interestingly, patients with HBeAg-positive chronic hepatitis B displayed impaired CpG-induced IFNα production by pDC without significant alterations in Loxoribine-induced pDC function compared to HBeAg-negative patients and healthy controls. The lack of activation and the active inhibition of pDC by HBV may both contribute to HBV persistence. The finding that the interaction between pDC and HBV may change upon activation may aid in the identification of a scavenging receptor supporting immunosuppressive effects of HBV and also in the design of novel treatment strategies for chronic HBV.

The mannose receptor acts as hepatitis B virus surface antigen receptor mediating interaction with intrahepatic dendritic cells.

Dendritic cells (DC) play a key role in anti-viral immunity. Direct interactions between DC and hepatitis B virus (HBV) may explain the impaired DC function and the ineffective anti-viral response of chronic HBV patients resulting in HBV persistence. Here, the interaction between HBV surface antigens (HBsAg) and DC and the receptor involved were examined by flow cytometry in blood and liver tissue of HBV patients. The in vitro data showed that the mannose receptor (MR) is involved in HBsAg recognition and uptake by DC. The presence of HBsAg-positive DC was demonstrated sporadically in blood, but frequently in the liver of HBV patients. Interestingly, a positive correlation was found between HBsAg positivity and MR expression level in both liver- and blood-derived DC. These data suggest that in HBV infected patients, MR-mediated interaction between HBsAg and DC and subsequent impairment of DC predominantly occurs at the main site of infection, the liver.

Hepatitis B virus surface antigen impairs myeloid dendritic cell function: a possible immune escape mechanism of hepatitis B virus.

Chronic hepatitis B virus (HBV) infection is the result of an inadequate immune response towards the virus. Myeloid dendritic cells (mDC) of patients with chronic HBV are impaired in their maturation and function, resulting in more tolerogenic rather than immunogenic responses, which may contribute to viral persistence. The mechanism responsible for altered mDC function remains unclear. The HBV-infected patients display large amounts of HBV particles and viral proteins in their circulation, especially the surface antigen HBsAg, which allows multiple interactions between the virus, its viral proteins and DC. To assess whether HBV directly influences mDC function, the effects of HBV and HBsAg on human mDC maturation and function were investigated in vitro. As already described for internalization of HBV by DC, the present study shows that peripheral blood-derived mDC of healthy controls also actively take up HBsAg in a time-dependent manner. Cytokine-induced maturation in the presence of HBV or HBsAg resulted in a significantly more tolerogenic mDC phenotype as demonstrated by a diminished up-regulation of costimulatory molecules and a decreased T-cell stimulatory capacity, as assessed by T-cell proliferation and interferon-gamma production. In addition, the presence of HBV significantly reduced interleukin-12 production by mDC. These results show that both HBV particles and purified HBsAg have an immune modulatory capacity and may directly contribute to the dysfunction of mDC in patients with chronic HBV. The direct immune regulatory effect of HBV and circulating HBsAg particles on the function of DC can be considered as part of the mechanism by which HBV escapes immunity.