HBV vaccination with Fendrix is effective and safe in pre-dialysis CKD population

Using the AS04C-adjuvanted hepatitis B vaccine in patients classified as non-responders

BACKGROUND

Chronic hepatitis B (HB) remains a significant global health concern, despite the widespread availability of the HB vaccine. While the standard vaccine demonstrates an impressive serological response rate exceeding 90%, a subset of individuals exhibit suboptimal immunity. This study aims to elucidate the efficacy of the AS04C-adjuvanted HB vaccine in addressing non-responsiveness.

METHODS

Conducted at the Preventive Medicine Service of the University Albacete Hospital in Spain from 2017 to 2021, this single-center observational study enrolled 195 patients. Among them, 126 (65%) were classified as non-responders following one or two complete standard vaccination courses.

RESULTS

After the administration of a complete four-dose regimen of the AS04C-adjuvanted vaccine, 73.81% of non-responder patients exhibited antibody titers indicative of robust immunity (anti-HBs >10).

CONCLUSIONS

These findings underscore the pivotal role of the AS04C-adjuvanted HB vaccine in addressing non-responsiveness, emphasizing its potential as a crucial tool in augmenting immunization strategies for various populations. This includes non-responders to standard vaccination, individuals with chronic kidney disease, those requiring seroprotection due to factors like immunosuppression or occupational hazards, as well as patients for whom conventional revaccination strategies have proven futile. Additional research is needed to expand on the promising results obtained through our protocol.

Vaccine Strategies to Elicit Mucosal Immunity

Vaccines are essential tools to prevent infection and control transmission of infectious diseases that threaten public health. Most infectious agents enter their hosts across mucosal surfaces, which make up key first lines of host defense against pathogens. Mucosal immune responses play critical roles in host immune defense to provide durable and better recall responses. Substantial attention has been focused on developing effective mucosal vaccines to elicit robust localized and systemic immune responses by administration via mucosal routes. Mucosal vaccines that elicit effective immune responses yield protection superior to parenterally delivered vaccines. Beyond their valuable immunogenicity, mucosal vaccines can be less expensive and easier to administer without a need for injection materials and more highly trained personnel. However, developing effective mucosal vaccines faces many challenges, and much effort has been directed at their development. In this article, we review the history of mucosal vaccine development and present an overview of mucosal compartment biology and the roles that mucosal immunity plays in defending against infection, knowledge that has helped inform mucosal vaccine development. We explore new progress in mucosal vaccine design and optimization and novel approaches created to improve the efficacy and safety of mucosal vaccines.

Revolutionizing medicine with toll-like receptors: A path to strengthening cellular immunity

Toll-like receptors play a vital role in cell-mediated immunity, which is crucial for the immune system's defense against pathogens and maintenance of homeostasis. The interaction between toll-like-receptor response and cell-mediated immunity is complex and essential for effectively eliminating pathogens and maintaining immune surveillance. In addition to pathogen recognition, toll-like receptors serve as adjuvants in vaccines, as molecular sensors, and recognize specific patterns associated with pathogens and danger signals. Incorporating toll-like receptor ligands into vaccines can enhance the immune response to antigens, making them potent adjuvants. Furthermore, they bridge the innate and adaptive immune systems and improve antigen-presenting cells' capacity to process and present antigens to T cells. The intricate signaling pathways and cross-talk between toll-like-receptor and T cell receptor (TCR) signaling emphasize their pivotal role in orchestrating effective immune responses against pathogens, thus facilitating the development of innovative vaccine strategies. This article provides an overview of the current understanding of toll-like receptor response and explores their potential clinical applications. By unraveling the complex mechanisms of toll-like-receptor signaling, we can gain novel insights into immune responses and potentially develop innovative therapeutic approaches. Ongoing investigations into the toll-like-receptor response hold promise in the future in enhancing our ability to combat infections, design effective vaccines, and improve clinical outcomes.

Vaccines, Adjuvants and Key Factors for Mucosal Immune Response

Vaccines are the most effective tool to control infectious diseases, which provoke significant morbidity and mortality. Most vaccines are administered through the parenteral route and can elicit a robust systemic humoral response, but they induce a weak T-cell-mediated immunity and are poor inducers of mucosal protection. Considering that most pathogens enter the body through mucosal surfaces, a vaccine that elicits protection in the first site of contact between the host and the pathogen is promising. However, despite the advantages of mucosal vaccines as good options to confer protection on the mucosal surface, only a few mucosal vaccines are currently approved. In this review, we discuss the impact of vaccine administration in different mucosal surfaces; how appropriate adjuvants enhance the induction of protective mucosal immunity and other factors that can influence the mucosal immune response to vaccines. This article is protected by copyright. All rights reserved.

Small Molecule Calcium Channel Activator Potentiates Adjuvant Activity

There remains an unmet need for reliable fully synthetic adjuvants that increase lasting protective immune responses from vaccines. We previously reported a high-throughput screening for small molecules that extended nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) activation after a Toll-like receptor 4 (TLR4) ligand, lipopolysaccharide (LPS), stimulation using a human myeloid reporter cell line. We identified compounds with a conserved aminothiazole scaffold including 2D216 [N-(4-(2,5-dimethylphenyl)thiazol-2-yl)-4-(piperidin-1-ylsulfonyl)benzamide], which increased murine antigen-specific antibody responses when used as a co-adjuvant with LPS. Here, we examined the mechanism of action in human cells. Although 2D216 activated the major mitogen-activated protein kinases, it did not interact with common kinases and phosphatases and did not stimulate many of the pattern recognition receptors (PRRs). Instead, the mechanism of action was linked to intracellular Ca2+ elevation via Ca2+ channel(s) at the plasma membrane and nuclear translocation of the nuclear factor of activated T-cells (NFAT) as supported by RNA-seq data, analysis by reporter cells, Ca2+ flux assays, and immunoblots. Interestingly, 2D216 had minimal, if any, activity on Jurkat T cells but induced cytokine production and surface expression of costimulatory molecules on cells with antigen-presenting functions. A small series of analogs of 2D216 were tested for the ability to enhance a TLR4 ligand-stimulated autologous mixed lymphocyte reaction (MLR). In the MLR, 2E151, N-(4-(2,5-dimethylphenyl)thiazol-2-yl)-4-((4-propylpiperidin-1-yl)sulfonyl)benzamide, was more potent than 2D216. These results indicate that a small molecule that is not a direct PRR agonist can act as a co-adjuvant to an approved adjuvant to enhance human immune responses via a complementary mechanism of action.

Hepatitis B Vaccination in Advanced Chronic Kidney Disease: A Quality Improvement Project at a Veteran Affairs Chronic Kidney Disease Clinic

Hepatitis B vaccination is recommended in all patients with end-stage kidney disease (ESKD). However, only 50–60% of these patients achieve protective antibody levels if immunized after starting dialysis. Strategies to overcome this low seroconversion rate include a 6-month vaccination schedule starting earlier [chronic kidney disease (CKD) stage 4 and 5] to ensure immunity when patients progress to ESKD. We conducted a quality improvement program to immunize pre-dialysis patients. Patients who were found to have a negative baseline serology with a negative hepatitis B surface antibody level (HBsAb) were offered vaccination on a 6-month schedule (0, 1 and 6 months) with one of two available vaccines within the VA system (Recombivax™ or Engerix™). HBsAb titers were checked 3–4 months later, and titers ≥ 12 mIU/mL were indicative of immunity at VA. Patients who did not seroconvert were offered a repeat schedule of three more doses. We screened 198 patients (187 males and 11 females) with CKD 4 and 5 [glomerular filtration rate (GFR) < 29 mL/min/1.73 m²]. The median age of this cohort was 72 years (range 38–92 years). During the study period of 5 years (2015–2020), 10 patients were excluded since their GFR had improved to more than 30 mL/min/1.73 m², 24 others had baseline immunity and 2 refused vaccination. The hepatitis B vaccination series was not started on 106 patients. Of the remaining 56, 12 patients progressed to ESKD and started dialysis before completion of the vaccination schedule, 6 expired and 1 did not come to clinic in 2020 due to the pandemic. Of the 37 patients who completed the vaccination schedule, 16 achieved seroconversion with adequate HBsAb titers, 10 did not develop immunity despite a second hepatitis B vaccination series, while 11 did not get a second series. Given the low seroconversion rate, albeit in a small cohort, vaccination should be considered in patients with earlier stages of CKD. Other options include studies on FDA approved vaccines of shorter duration. We plan to increase awareness among nephrologists, patients and nursing staff about the importance of achieving immunity against hepatitis B.

Nano-adjuvant based on silk fibroin for the delivery of recombinant hepatitis B surface antigen

Nanotechnology has a vital role in vaccine development. Nano-adjuvants, as robust delivery systems, could stimulate immune responses. Using nanoparticles (NPs) in vaccine formulations enhances the target delivery, immunogenicity, and stability of the antigens. Herein, silk fibroin nanoparticles (SFNPs) were used as a nano-adjuvant for delivering recombinant hepatitis B surface antigen (HBsAg). HBsAg was loaded physically and chemically on the surface of SFNPs. The HBsAg-loaded SFNPs had a spherical morphology. The in vitro release studies showed that HBsAg had a continuous and slow release from SFNPs during 56 days. During this time, ∼45.6% and 34.1% HBsAg was released from physical-SFNPs and chemical-SFNPs, respectively. HBsAg-loaded SFNPs were also stable for six months with slight changes in the size, surface charge, and morphology. The results of circular dichroism (CD) and fluorescence spectroscopy indicated that the released HBsAg preserved the native secondary and tertiary structures. The quantitative cellular uptake study also showed that physical-SFNPs were taken up more into J774A.1 macrophage cells than chemical-SFNPs. After 28 and 56 days post-injection, the immunogenicity studies showed that the specific total IgG, IgG1, and IgG2a levels against HBsAg were significantly higher in the physically loaded group than in the chemically loaded group and commercial hepatitis B vaccine. IgG2a levels were detected only in mice immunized with physical-SFNPs. However, the low levels of IL-4 and IFN-γ were produced in all vaccinated groups and differences in mean values were not significant compared with control groups. Results indicated an improvement in the levels of anti-HBsAg IgG in mice immunized with the physical-SFNPs group compared to other groups.

Hepatitis B virus vaccine and chronic kidney disease. The advances

BACKGROUND

Hepatitis B is an important agent of liver disease in patients with chronic kidney disease and chronic HBV infection promotes the development of CKD in the adult general population. Patients with CKD have a suboptimal response to various vaccines, and it remains unclear how we boost the immune response of CKD patients to HB vaccine.

STUDY AIMS AND DESIGN

We performed a narrative review to assess the mechanisms of lower immunogenicity of HBV vaccine in CKD population; multiple approaches to improve the response rate of CKD patients to HBV vaccine have been reported. This is a very important topic for nephrologists who often serve as primary case providers for patients with CKD.

RESULTS

The recommended vaccine schedule for CKD patients including those on maintenance dialysis is based on recombinant vaccine, four doses (month 0,1,2, and 6; 40mcg each) by intramuscular route (deltoid muscle). According to RCTs or observational studies, some recombinant vaccines with adjuvants (i.e., HBV-AS02 and HBV-AS04) look promising. HBV-AS04 showed to give better seroprotection rates and durable immune response over extended follow-ups compared with licensed HBV vaccine in CKD patients. The seroprotection rate was 95% (97/102) and 82% (202/248) in pre-dialysis and dialysis patients, respectively, one month after completing vaccine schedule with HBV-AS04. HBV-AS02 was superior to licensed vaccine in terms of seroprotection rate, 76.9% vs. 37.6%.

CONCLUSIONS

We suggest adjuvanted recombinant (HBV-AS04) vaccine (0,1,2 and 3 months; 20 mcg each dose) and post vaccination testing of anti-HBs antibody after vaccination. Booster doses to patients whose anti-HBs titers fall below the seroprotection level (<10IU/mL) during the follow-up are appropriate. The patho-physiologic mechanisms responsible for the poor immunogenicity of HBV vaccine in CKD patients are under active investigation.

TLR Agonists as Vaccine Adjuvants Targeting Cancer and Infectious Diseases

Modern vaccines have largely shifted from using whole, killed or attenuated pathogens to being based on subunit components. Since this diminishes immunogenicity, vaccine adjuvants that enhance the immune response to purified antigens are critically needed. Further advantages of adjuvants include dose sparing, increased vaccine efficacy in immunocompromised individuals and the potential to protect against highly variable pathogens by broadening the immune response. Due to their ability to link the innate with the adaptive immune response, Toll-like receptor (TLR) agonists are highly promising as adjuvants in vaccines against life-threatening and complex diseases such as cancer, AIDS and malaria. TLRs are transmembrane receptors, which are predominantly expressed by innate immune cells. They can be classified into cell surface (TLR1, TLR2, TLR4, TLR5, TLR6) and intracellular TLRs (TLR3, TLR7, TLR8, TLR9), expressed on endosomal membranes. Besides a transmembrane domain, each TLR possesses a leucine-rich repeat (LRR) segment that mediates PAMP/DAMP recognition and a TIR domain that delivers the downstream signal transduction and initiates an inflammatory response. Thus, TLRs are excellent targets for adjuvants to provide a "danger" signal to induce an effective immune response that leads to long-lasting protection. The present review will elaborate on applications of TLR ligands as vaccine adjuvants and immunotherapeutic agents, with a focus on clinically relevant adjuvants.