Association of hepatitis delta virus with liver morbidity and mortality: A systematic literature review and meta-analysis

Hepatitis Delta Coinfection Rates and All-Cause Mortality Among Hepatitis B-Infected Veterans in the USA

Screening for hepatitis D virus (HDV) is recommended for all individuals with hepatitis B virus (HBV) infection. Coinfected individuals experience more severe liver-related outcomes. We determined the HDV testing and coinfection rates and all-cause mortality among those infected with HBV. We used the US Department of Veterans Affairs (VA) healthcare system's national databases to identify individuals with HBV infection. We determined the proportion of individuals referred to gastroenterologists/hepatologists, or infectious diseases providers, and the proportion screened and tested positive for HDV. We calculated the HBV treatment rates, defined as ≥ 3 months of continuous prescription with an approved drug. Finally, we calculated all-cause mortality stratified by HDV coinfection and HBV treatment status. Among 44,951 individuals with at least one positive HBsAg, HBeAg or HBV DNA test, 5964 (13.3%) were screened for HDV (180 [3.0%] tested positive), and 28,291 (62.9%) were referred to gastroenterology/hepatology or infectious diseases. Treatment for HBV was prescribed for 73 (40.5%) of HDV-coinfected and 2425 (41.9%) HDV-uninfected individuals. All-cause mortality rate per 100 person-years was lower among those without HDV coinfection (2.98 for untreated HBV, 2.53 for treated HBV; p < 0.001) compared with those with HDV coinfection (5.14 for untreated HBV, 3.0 for treated HBV; p = 0.02). Kaplan-Meier curves demonstrated a significantly higher mortality among HDV-coinfected individuals who were not treated for HBV (log-rank p < 0.0001). Screening rates for HDV among HBV-infected individuals are suboptimal. While HDV coinfection is associated with higher all-cause mortality, HBV treatment may confer a survival benefit.

Current research insights into the role of CTLA-4 in hepatitis B virus (HBV) infection

Chronic hepatitis B virus (HBV) infection is a significant global public health concern, and the clearance of HBV is closely linked to the activity of HBV-specific T cells, which is regulated by various co-suppressor molecules. Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is among these co-suppressor molecules which induces T cell exhaustion by competitively inhibiting CD28 and dampening the function of HBV-specific T cells. CTLA-4 also plays a role in the regulation of T helper (Th) cell differentiation and influences cytokine release. In addition, CTLA-4 can impact glucose metabolism in hepatocellular carcinoma through its interaction with T regulatory (Treg) cells. This review aims to provide a comprehensive overview of the existing literature related to the role of CTLA-4 in HBV patients across different subsets of T cells. Additionally, we propose a discussion on the possible mechanisms through which CTLA-4 may contribute to HBV infection, as well as the development of HBV-induced cirrhosis and hepatocellular carcinoma.

Outcomes of a 1-Year Pilot Study Implementing Universal Hepatitis Delta Virus Testing Among Veterans With Chronic Hepatitis B

Current US guidelines recommend risk-based testing for hepatitis delta virus (HDV) in persons with chronic hepatitis B (CHB). While there is debate as to whether a risk-based or universal testing approach is most effective, limited data exist on universal HDV testing programs in the United States. We performed a 1-year pilot study evaluating the outcomes of a universal HDV testing approach among US veterans with CHB. All consecutive adults with CHB receiving care at hepatology clinics at a single-centre Veterans Affairs Health System from 1 October 2022 to 30 September 2023 were prospectively tested for anti-HDV antibody (anti-HDV). Patients who were anti-HDV Ab-positive were subsequently tested for HDV RNA. Comparison of HDV testing between groups utilised chi-square testing. A total of 91 consecutive CHB patients (90.0% male, mean age 60.9 ± 14.1 years, 73.9% Asian, 26.1% non-Asia, 16.5% cirrhosis and 17.1% with active or past history of drug use) had anti-HDV ordered. Overall, 76.9% (n = 70) completed anti-HDV testing; 4.3% (n = 3) were positive. HDV RNA testing was ordered in all three patients; two patients completed HDV RNA testing and one had detectable HDV RNA. No significant differences in completion of anti-HDV testing was observed by age, sex, race/ethnicity, cirrhosis status or drug use history. Among a single-centre prospective cohort study piloting a universal HDV testing approach, one patient with viremic HDV was identified. Implementing true reflex testing of all CHB patients with anti-HDV, followed by automated HDV RNA testing for anti-HDV-positive patients would improve the HDV testing cascade and timely diagnosis of HDV.

Advances in hepatitis delta research: emerging insights and future directions

OBJECTIVES

Hepatitis delta virus (HDV) is a defective virus needing the envelope provided by hepatitis B virus (HBV) in order to enter liver cells and propagate. Chronic HDV infection is considered the most severe viral hepatitis, resulting in accelerated fibrosis progression until cirrhosis and its complications (hepatocellular carcinoma, liver decompensation) compared with HBV mono-infected patients. Off-label treatment with interferon has represented the only treatment option in the last 40 years, resulting in suboptimal virological response rates and being limited by safety issues especially in patients with advanced cirrhosis. Recently, the first HBV-HDV entry inhibitor Bulevirtide (BLV) has been approved by the European Medicines Agency (EMA) for treatment of chronic compensated HDV.

METHODS

This review summarises most recent updates on HDV epidemiology, diagnosis and treatment, with a special focus both on clinical trials and real-life studies about BLV. An overview on new HDV compounds under development is also provided.

RESULTS

BLV, the HBV-HDV entry inhibitor, has shown promising safety and efficacy data in clinical trials and in real-life studies, also in patients with advanced cirrhosis and portal hypertension. However, according to EMA label treatment is currently intended long-term until clinical benefit and predictors of responses are still undefined. The potential combination with PegIFNα seems to increase virological and clinical responses. New compounds are under development or in pipeline for treatment of HDV.

CONCLUSION

After more than 40 years since HDV discovery, new treatment options are currently available to provide efficient strategies for chronic hepatitis Delta.

Oxytocin alleviates liver fibrosis via hepatic macrophages

Background & Aims

Previous studies demonstrated oxytocin treatment effectiveness in reducing mortality and reversing liver fibrosis in mice. However, the underlying mechanism remains obscure, given the absence of oxytocin receptor expression in hepatic stellate cells, the primary liver fibrosis effector cells.

Methods

A comprehensive map of cell populations in fibrotic liver was generated using single-cell sequencing. The map enabled our study of the target cells of oxytocin action in the liver in more dimensions. Furthermore, we elucidated the mechanism of the oxytocin signaling system in hepatic macrophages using oxytocin receptor-specific knockout mice and liver fibrosis animal models.

Results

The carbon tetrachloride-induced hepatic fibrosis and bile duct ligation hepatic fibrosis mouse models demonstrated that oxytocin reversed hepatic fibrosis in mice. The mapped liver cell populations demonstrated that oxytocin promoted the phenotypic switch from Ly6high to Ly6Clow in myeloid-derived macrophages. The phenotypic control of oxytocin signaling system activation on this phenotypic switch was validated using myeloid-specific oxytocin receptor knockout mice. Subsequent studies demonstrated that the calcium inward flow induced by oxytocin receptor activation activated the key orphan nuclear receptor NR4A1, which controls macrophage phenotypic switching. Specifically, calcium ions activated CREB, a key target regulator of NR4A1 expression.

Conclusions

The findings established hepatic macrophages as a hub responsible for the oxytocin-mediated alleviation of liver fibrosis. This study revealed a novel pathway where oxytocin regulates macrophage phenotype.

Impact and implications

Previous studies revealed for the first time the expression of oxytocin receptors in the liver. The present study shows that oxytocin reverses hepatic fibrosis and that hepatic macrophages are the central hub of oxytocin-mediated alleviation of hepatic fibrosis by promoting a phenotypic switch in hepatic macrophages, transitioning from Ly6high to Ly6Clow expression. The present study reveals a novel pathway by which oxytocin regulates macrophage phenotype. In addition, the potential applications of oxytocin and its analogues, as traditional drugs for clinical application, in the treatment of liver fibrosis deserve to be further explored.

Understanding the Natural History of Chronic Hepatitis D: Proposal of a Model for Cost-Effectiveness Studies

BACKGROUND

As new therapeutic options become available, better understanding the potential impact of emerging therapies on clinical outcomes of hepatits D virus (HDV) is critical.

OBJECTIVE

The aim of this study was to develop a natural history model for patients with hepatitis D virus.

METHODS

We developed a model (decision tree followed by a Markov cohort model) in adults with chronic HDV infection to assess the natural history and impact of novel treatments on disease progression versus best supportive care (BSC). The model time horizon was over a lifetime (up to 100 years of age); state transitions and health states were defined by responder status. Patients in fibrosis stages 0 through 4 received treatment; decompensated patients were not treated. Response was defined as the combined response endpoint of achievement of HDV-RNA undetectability/≥2-log10 decline and alanine aminotransferase normalization; response rates of 50% and 75% were explored. Health events associated with advanced liver disease were modeled as the number of events per 10,000 patients. Scenario analyses of early treatment, alternate treatment response, and no fibrosis regression for treatment responders were also explored.

RESULTS

The model was able to reflect disease progression similarly to published natural history studies for patients with HBV/HDV infection. In a hypothetical cohort of patients reflecting a population enrolled in a recent clinical trial, fewer advanced liver disease events were observed with a novel HDV treatment versus BSC. Fewer liver-related deaths were observed under 50% and 75% response (900 and 1,358 fewer deaths, respectively, per 10,000 patients). Scenario analyses showed consistently fewer advanced liver disease events with HDV treatment compared with BSC, with greater reductions observed with earlier treatment.

CONCLUSION

This HDV disease progression model replicated findings from natural history studies. Furthermore, it found that a hypothetical HDV treatment results in better clinical outcomes for patients versus BSC, with greater benefit observed when starting treatment early. This validated natural history model for HBV/HDV infection can serve as a foundation for future clinical and economic analyses of novel HDV treatments that can support healthcare stakeholders in the management of patients with chronic HDV.