The effects of nucleoside/nucleotide analogues on host immune cells: the baseline for future immune therapy for HBV?

Discovery of Hepatitis B Virus Surface Antigen Suppressor GS-8873

Chronic hepatitis B (CHB) virus infection afflicts hundreds of millions of people and causes nearly one million deaths annually. The high levels of circulating viral surface antigen (HBsAg) that characterize CHB may lead to T-cell exhaustion, resulting in an impaired antiviral immune response in the host. Agents that suppress HBsAg could help invigorate immunity toward infected hepatocytes and facilitate a functional cure. A series of dihydropyridoisoquinolizinone (DHQ) inhibitors of human poly(A) polymerases PAPD5/7 were reported to suppress HBsAg in vitro. An example from this class, RG7834, briefly entered the clinic. We set out to identify a potent, orally bioavailable, and safe PAPD5/7 inhibitor as a potential component of a functional cure regimen. Our efforts led to the identification of a dihydropyridophthalazinone (DPP) core with improved pharmacokinetic properties. A conformational restriction strategy and optimization of core substitution led to GS-8873, which was projected to provide deep HBsAg suppression with once-daily dosing.

Addition of PEG-interferon to long-term nucleos(t)ide analogue therapy enhances HBsAg decline and clearance in HBeAg-negative chronic hepatitis B: Multicentre Randomized Trial (PAS Study)

We studied whether 48 weeks of PEG-IFN alfa-2a add-on increases HBsAg-decline and clearance in HBeAg-negative patients on long-term nucleo(s)tide analogue (NA) therapy. In this investigator-initiated, randomized, controlled trial conducted in Europe and Canada, HBeAg-negative patients treated with NA > 12 months, with HBVDNA < 200 IU/mL, were enrolled. Patients were randomized 2:1 to 48 weeks of PEG-IFN alfa-2a add-on (180 μg per week) or continued NA-monotherapy with subsequent follow-up to Week 72. Endpoints were HBsAg decline (≥1 log10 IU/mL) and HBsAg clearance at Week 48. Of the 86 patients in the modified-intention-to-treat analysis, 58 patients received PEG-IFN add-on, and 28 continued NA monotherapy. At Week 48, 16(28%) patients achieved HBsAg decline ≥1 log10 in the add-on arm versus none on NA-monotherapy (p < .001), and HBsAg clearance was observed in 6 (10%) PEG-IFN add-on patients versus 0% NA-monotherapy (p = .01). HBVRNA was only detected in 2% after PEG-IFN treatment versus 19% in NA-monotherapy (p = .002) at Week 48. PEG-IFN add-on therapy was well tolerated in majority of patients. Low baseline HBsAg levels (<10 IU/mL) identified patients most likely to achieve HBsAg loss with PEG-IFN add-on, whereas an HBsAg level > 200 IU/mL at on-treatment Week 12 was highly predictive of non-response (NPV = 100%). Addition of PEG-IFN to long-term NA enhanced HBsAg decline and increased the chance of HBsAg clearance in HBeAg-negative patients on long-term NA. On-treatment HBsAg levels >200 IU/mL identify patients unlikely to benefit from PEG-IFN add-on and could be used as a potential stopping-rule for PEG-IFN therapy. Our findings support further exploration of immune modulation add-on to antiviral therapy, preferably using response-guided strategies, to increase functional cure rates in patients with CHB.

Effect of prophylactic antiviral intervention on T cell immunity in hepatitis B virus-infected pregnant women

BACKGROUND

Antiviral intervention in hepatitis B virus (HBV)-infected pregnant women can effectively reduce mother-to-child transmission. However, the immunological characteristics of pregnant women with chronic HBV infection and the effects of antiviral intervention during pregnancy on maternal immune response remain unknown. We aimed to investigate these effects by comparing mothers who received antiviral intervention during pregnancy with those who did not.

METHODS

Pregnant women positive for hepatitis B surface antigen and hepatitis B e-antigen (HBsAg⁺ HBeAg⁺) were enrolled at delivery, including 34 received prophylactic antiviral intervention during pregnancy (AVI mothers) and 15 did not (NAVI mothers). T lymphocyte phenotypes and functions were analysed using flow cytometry.

RESULTS

At delivery, maternal regulatory T cell (Treg) frequency in AVI mothers was significantly higher than that in NAVI mothers (P < 0.002), and CD4⁺ T cells in AVI mothers displayed a decreased ability to secrete IFN-γ (P = 0.005) and IL-21 (P = 0.043), but an increased ability to secrete IL-10 and IL-4 (P = 0.040 and P = 0.036), which represented a higher Treg frequency, enhanced Th2 response and suppressed Th1 response. Treg frequency among AVI mothers was correlated negatively with serum HBsAg and HBeAg levels. After delivery, the ability of CD4⁺ T cells or CD8⁺ T cells to secrete IFN-γ or IL-10 was similar and no significant difference in Treg frequency was found between the two groups.

CONCLUSIONS

Prophylactic antiviral intervention during pregnancy has an effect on T cell immunity in pregnant women, which was characterised by increased maternal Treg frequency, enhanced Th2 response and suppressed Th1 response at delivery.

Levels of Antibodies to Hepatitis B Core Antigen Are Associated With Liver Inflammation and Response to Peginterferon in Patients With Chronic Hepatitis B

BACKGROUND

Emerging evidence suggests a pivotal role for B-cell responses in the natural history of chronic hepatitis B. Serum levels of antibodies to hepatitis B core antigen (anti-HBc) vary across infection stages, but their role in predicting response to antiviral therapy is uncertain.

METHODS

Anti-HBc levels were assessed before peginterferon (PEG-IFN) therapy in patients with chronic hepatitis B who either started de novo PEG-IFN (n = 299; 195 hepatitis B e antigen [HBeAg] positive) or started PEG-IFN as add-on to an existing nucleo(s)tide analogue backbone (n = 91; all HBeAg-positive). Associations were explored between anti-HBc and (1) serum biomarkers, (2) liver histological findings, and (3) treatment response.

RESULTS

We studied 390 patients. The hepatitis B virus (HBV) genotype were A, B, C, and D in 24%, 9%, 16%, and 49%, respectively; 72% of patients were Caucasian. Among currently untreated HBeAg-positive patients, anti-HBc was correlated with HBV DNA, hepatitis B core-related antigen (HBcrAg), hepatitis B surface antigen (HBsAg), and HBV RNA, but not with alanine aminotransferase (ALT). Higher anti-HBc was associated with more severe histological inflammatory activity (P < .001), irrespective of HBeAg status. After de novo PEG-IFN, higher anti-HBc levels were associated with HBeAg loss, sustained response, HBsAg decline, and HBsAg clearance (P < .050). Among patients treated with add-on PEG-IFN, higher anti-HBc was associated with HBeAg loss (P = .01).

CONCLUSIONS

Serum anti-HBc levels correlate with histological inflammatory activity. Higher anti-HBc levels were associated with favorable treatment outcomes. These findings suggest that anti-HBc could be used to select patients most likely to respond to immunomodulatory therapy.

CLINICAL TRIALS REGISTRATION

NCT00114361, NCT00146705, NCT00877760, and NCT01532843.

Indoleamine 2,3-dioxygenase 1 limits hepatic inflammatory cells recruitment and promotes bile duct ligation-induced liver fibrosis

Liver fibrosis is a course of chronic liver dysfunction, can develop into cirrhosis and hepatocellular carcinoma. Inflammatory insult owing to pathogenic factors plays a crucial role in the pathogenesis of liver fibrosis. Indoleamine 2,3-dioxygenase 1 (IDO1) can affect the infiltration of immune cells in many pathology processes of diseases, but its role in liver fibrosis has not been elucidated completely. Here, the markedly elevated protein IDO1 in livers was identified, and dendritic cells (DCs) immune-phenotypes were significantly altered after BDL challenge. A distinct hepatic population of CD11c+DCs was decreased and presented an immature immune-phenotype, reflected by lower expression levels of co-stimulatory molecules (CD40, MHCII). Frequencies of CD11c+CD80+, CD11c+CD86+, CD11c+MHCII+, and CD11c+CD40+ cells in splenic leukocytes were reduced significantly. Notably, IDO1 overexpression inhibited hepatic, splenic CD11c+DCs maturation, mature DCs-mediated T-cell proliferation and worsened liver fibrosis, whereas above pathological phenomena were reversed in IDO1-/- mice. Our data demonstrate that IDO1 affects the process of immune cells recruitment via inhibiting DCs maturation and subsequent T cells proliferation, resulting in the promotion of hepatic fibrosis. Thus, amelioration of immune responses in hepatic and splenic microenvironment by targeting IDO1 might be essential for the therapeutic effects on liver fibrosis.