Mucosal immunization with high-mobility group box 1 in chitosan enhances DNA vaccine-induced protection against coxsackievirus B3-induced myocarditis

Vaccines against Group B Coxsackieviruses and Their Importance

The group B coxsackieviruses (CVBs) exist in six serotypes (CVB1 to CVB6). Disease associations have been reported for most serotypes, and multiple serotypes can cause similar diseases. For example, CVB1, CVB3, and CVB5 are generally implicated in the causation of myocarditis, whereas CVB1 and CVB4 could accelerate the development of type 1 diabetes (T1D). Yet, no vaccines against these viruses are currently available. In this review, we have analyzed the attributes of experimentally tested vaccines and discussed their merits and demerits or limitations, as well as their impact in preventing infections, most importantly myocarditis and T1D.

Infectious Inflammatory Processes and the Role of Bioactive Agent Released from Imino-Chitosan Derivatives Experimental and Theoretical Aspects

The paper focuses on the development of a multifractal theoretical model for explaining drug release dynamics (drug release laws and drug release mechanisms of cellular and channel-type) through scale transitions in scale space correlated with experimental data. The mathematical model has been developed for a hydrogel system prepared from chitosan and an antimicrobial aldehyde via covalent imine bonds. The reversible nature of the imine linkage points for a progressive release of the antimicrobial aldehyde is controlled by the reaction equilibrium shifting to the reagents, which in turn is triggered by aldehyde consumption in the inhibition of the microbial growth. The development of the mathematical model considers the release dynamic of the aldehyde in the scale space. Because the release behavior is dictated by the intrinsic properties of the polymer–drug complex system, they were explained in scale space, showing that various drug release dynamics laws can be associated with scale transitions. Moreover, the functionality of a Schrödinger-type differential equation in the same scale space reveals drug release mechanisms of channels and cellular types. These mechanisms are conditioned by the intensity of the polymer–drug interactions. It was demonstrated that the proposed mathematical model confirmed a prolonged release of the aldehyde, respecting the trend established by in vitro release experiments. At the same time, the properties of the hydrogel recommend its application in patients with intrauterine adhesions (IUAs) complicated by chronic endometritis as an alternative to the traditional antibiotics or antifungals.

Recent advances on chitosan as an adjuvant for vaccine delivery

Chitosan (CS) is a natural polymer derived from chitin that has wide applications in drugs, vaccines, and antigen delivery. The distinctive mucoadhesive, biocompatibility, biodegradable, and less toxic properties of chitosan compared to the currently used vaccine adjuvants made it a promising candidate for use as an adjuvant/carrier in vaccine delivery. In addition, chitosan exhibits intrinsic immunomodulating properties making it a suitable adjuvant in preparing vaccines delivery systems. Nanoparticles (NPs) of chitosan and its derivatives loaded with antigen have been shown to induce cellular and humoral responses. Versatility in the physicochemical properties of chitosan can provide an excellent opportunity to engineer antigen-specific adjuvant/delivery systems. This review discusses the recent advances of chitosan and its derivatives as adjuvants in vaccine deliveryand the published literature in the last fifteen years. The impact of physicochemical properties of chitosan on vaccine formulation has been described in detail. Applications of chitosan and its derivatives, their physicochemical properties, and mechanisms in enhancing immune responses have been discussed. Finally, challenges and future aspects of chitosan use has been pointed out.

An Albumin-Binding Domain Peptide Confers Enhanced Immunoprotection Against Viral Myocarditis by CVB3 VP1 Vaccine

Coxsackievirus B3 (CVB3)-induced viral myocarditis is a common clinical cardiovascular disease without effective available vaccine. In this study, we tried to potentiate the immunoprotection efficacy of our previous CVB3-specific VP1 protein vaccine by introducing a streptococcal protein G-derived, draining lymph nodes (dLNs)-targeting albumin-binding domain (ABD) peptide. We found that compared with the original VP1 vaccine, ABD-fused VP1 (ABD-VP1) vaccine gained the new ability to efficiently bind murine albumin both in vitro and in vivo, possessed a much longer serum half-life in serum and exhibited more abundance in the dLNs after immunization. Accordingly, ABD-VP1 immunization not only significantly facilitated the enrichment and maturation of dendritic cells (DCs), induced higher percentages of IFN-γ+ CD8 + cells in the dLNs, but also robustly promoted VP1-induced T cell proliferation and cytotoxic T lymphocyte (CTL) responses in the spleens. More importantly, ABD-VP1 also elicited higher percentages of protective CD44hi CD62Lhi memory T cells in dLNs and spleens. Consequently, obvious protective effect against viral myocarditis was conferred by ABD-VP1 vaccine compared to the VP1 vaccine, reflected by the less body weight loss, improved cardiac function, alleviated cardiac histomorphological changes and an increased 28-day survival rate. Our results indicated that the ABD might be a promising immune-enhancing regime for vaccine design and development.

gB co-immunization with GP96 enhances pulmonary-resident CD8 T cells and exerts a long-term defence against MCMV pneumonitis

Human cytomegalovirus (HCMV) infection in the respiratory tract leads to pneumonitis in immunocompromised hosts without available vaccine. Considering cytomegalovirus (CMV) mainly invades through the respiratory tract, CMV-specific pulmonary mucosal vaccine development that provides a long-lasting protection against CMV challenge gains our attention. In this study, N-terminal domain of GP96 (GP96-NT) was used as a mucosal adjuvant to enhance the induction of pulmonary-resident CD8 T cells elicited by MCMV glycoprotein B (gB) vaccine. Mice were intranasally co-immunized with 50 μg pgB and equal amount of pGP96-NT vaccine 4 times at 2-week intervals, and then i.n. challenged with MCMV at 16 weeks after the last immunization. Compared with pgB immunization alone, co-immunization with pgB/pGP96-NT enhanced a long-lasting protection against MCMV pneumonitis by significantly improved pneumonitis pathology, enhanced bodyweight, reduced viral burdens and increased survival rate. Moreover, the increased CD8 T cells were observed in lung but not spleen from pgB/pGP96-NT co-immunized mice. The increments of pulmonary CD8 T cells might be mainly due to non-circulating pulmonary-resident CD8 T-cell subset expansion but not circulating CD8 T-cell populations that home to inflammation site upon MCMV challenge. Finally, the deterioration of MCMV pneumonitis by depletion of pulmonary site-specific CD8 T cells in mice that were pgB/pGP96-NT co-immunization might be a clue to interpret the non-circulating pulmonary-resident CD8 T subset expansion. These data might uncover a promising long-lasting prophylactic vaccine strategy against MCMV-induced pneumonitis.

Alteration of serum high-mobility group protein 1 (HMGB1) levels in children with enterovirus 71-induced hand, foot, and mouth disease

Hand, foot, and mouth disease (HFMD) is a common pediatric disease caused by enterovirus infection. It typically presents as a fever along with flat, discolored spots and bumps on the hands, feet, and mouth. Compared with other viruses, enterovirus 71 (EV71)-induced HFMD is more prone to cause severe complications in children, such as brainstem encephalitis, cardiopulmonary disorders, and even death. More in-depth studies are still necessary to understand the characteristics of EV71-induced HFMD, although some related research has been reported so far. High-mobility group box 1 (HMGB1) is an inflammatory cytokine that can upregulate other inflammatory factors through its receptors, such as Toll-like receptors and the receptor for advanced glycation endproducts.We prospectively investigated the alteration of serum HMGB1, interleukin (IL)-6, and tumor necrosis factor (TNF)-α levels before and after treatment in 82 children with HFMD.We found that the serum HMGB1, IL-6, and TNF-α levels were significantly increased in EV71-induced HFMD, and that these changes were more serious in the severe and critical HMFD groups; however, there was no significant difference in the HMGB1 level between the normal control and mild HMFD groups. Moreover, the serum HMGB1 level was positively correlated with the alteration of serum IL-6 and TNF-α concentrations.These results suggest that HMGB1 is involved in the inflammatory pathogenesis of EV71-induced HFMD and that the serum level of HMGB1 could be applied as a clinical indicator for the severity of HFMD, and also a sign for the recovery prognosis of HFMD.

Synergistic effect of high-mobility group box-1 and lipopolysaccharide on cytokine induction in bovine peripheral blood mononuclear cells

High-mobility group box 1 (HMGB1) is one of the potent endogenous adjuvants released by necrotic and activated innate immune cells. HMGB1 modulates innate and adaptive immune responses in humans and mice by mediating immune cells crosstalk. However, the immuno-modulatory effects of HMGB1 in the bovine immune system are not clearly known. In this study, the effect of bovine HMGB1 alone or in combination with LPS on the expression kinetics of cytokines upon in vitro stimulation of bovine peripheral blood mononuclear cells (PBMCs) was investigated by quantitative PCR assay. The biological activity of bovine HMGB1 expressed in this prokaryotic expression system was confirmed by its ability to induce nitric oxide secretion in RAW 264.7 cells. The present results indicate that HMGB1 induces a more delayed TNF-α response than does LPS in stimulated PBMCs. However, IFN-γ, IFN-β and IL-12 mRNA transcription peaked at 6 hr post stimulation after both treatments. Further, HMGB1 and LPS heterocomplex up-regulated TNF-α, IFN-γ and IL-12 mRNA expression significantly than did individual TLR4 agonists. The heterocomplex also enhanced the expression of TLR4 on bovine PBMCs. In conclusion, the data indicate that HMGB1 and LPS act synergistically and enhance proinflammatory cytokines, thereby eliciting Th1 responses in bovine PBMCs. These results suggest that HMGB1 can act as an adjuvant in modulating the bovine immune system and thus lays a foundation for using HMGB1 as an adjuvant in various bovine vaccine preparations.

Hp91 immunoadjuvant: An HMGB1-derived peptide for development of therapeutic HPV vaccines

BACKGROUND

High percentage of human cervical malignancy is related to human papillomavirus (HPV) infections. Thus, it is important to find novel non-invasive treatment strategies among various therapeutic HPV vaccines. In current study, we investigated the protective and therapeutic effects of DNA- and protein-based vaccines using HPV16 E7 as a model antigen in tumor mice model. In this line, the full length of high-mobility group box 1 (HMGB1) protein as well as an HMGB1-derived short peptide (Hp91) was used as an adjuvant for stimulating adaptive immunity and developing the potency of these vaccines.

METHODS

DNA vaccination of HPV16 E7 with HMGB1 was performed as the complexed and conjugated forms. The immunostimulatory properties of Hp91 peptide along with Hp121 control peptide were compared to Montanide 720 in protein vaccination.

RESULTS

Our data showed that co-immunization of HPV16 E7 protein with Hp91 peptide or Hp91+Hp121 peptides significantly increased the secretion of IFN-γ, IgG2a antibody response, and protected 100% of mice against a TC-1 tumor challenge. Furthermore, the linkage of HMGB1 with E7 antigen led to enhance the immunogenicity of DNA vaccine especially in combination with Hp91 and Hp121 peptides.

CONCLUSIONS

These findings suggest that Hp91 peptide, and the full length of HMGB1 gene could be an efficient adjuvant for improvement of therapeutic HPV protein- and DNA-based vaccines, respectively.

Is a multivalent hand, foot, and mouth disease vaccine feasible?

Enterovirus A infections are the primary cause of hand, foot and mouth disease (HFMD) in infants and young children. Although enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) are the predominant causes of HFMD epidemics worldwide, EV-A71 has emerged as a major neurovirulent virus responsible for severe neurological complications and fatal outcomes. HFMD is a serious health threat and economic burden across the Asia-Pacific region. Inactivated EV-A71 vaccines have elicited protection against EV-A71 but not against CV-A16 infections in large efficacy trials. The current development of a bivalent inactivated EV-A71/CV-A16 vaccine is the next step toward that of multivalent HFMD vaccines. These vaccines should ultimately include other prevalent pathogenic coxsackieviruses A (CV-A6 and CV-A10), coxsackieviruses B (B3 and B5) and echovirus 30 that often co-circulate during HFMD epidemics and can cause severe HFMD, aseptic meningitis and acute viral myocarditis. The prospect and challenges for the development of such multivalent vaccines are discussed.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Development of a DNA vaccine for chicken infectious anemia and its immunogenicity studies using high mobility group box 1 protein as a novel immunoadjuvant indicated induction of promising protective immune responses

Chicken infectious anaemia (CIA) is an economically important and emerging poultry disease reported worldwide. Current CIA vaccines have limitations like, the inability of the virus to grow to high titres in embryos/cell cultures, possession of residual pathogenicity and a risk of reversion to virulence. In the present study, a DNA vaccine, encoding chicken infectious anaemia virus (CIAV) VP1 and VP2 genes, was developed and co-administered with truncated chicken high mobility group box 1 (HMGB1ΔC) protein in young chicks for the evaluation of vaccine immune response. CIAV VP1 and VP2 genes were cloned in pTARGET while HMGB1ΔC in PET32b vector. In vitro expression of these gene constructs was evaluated by Western blotting. Further, recombinant HMGB1ΔC was evaluated for its biological activity. The CIAV DNA vaccine administration in specific pathogen free chicks resulted in moderately protective ELISA antibody titres in the range of 4322.87 ± 359.72 to 8288.19 ± 136.38, increased CD8(+) cells, and a higher titre was observed by co-administration of novel adjuvant (HMGB1ΔC) and booster immunizations. The use of vaccine with adjuvant showed achieving antibody titres nearly 8500, titre considered as highly protective, which indicates that co-immunization of HMGB1ΔC may have a strong adjuvant activity on CIAV DNA vaccine induced immune responses. The able potential of HMGB1 protein holding strong adjuvant activity could be exploited further with trials with vaccines for other important pathogens for achieving the required protective immune responses.

Structural, phenotypic and functional maturation of bone marrow dendritic cells (BMDCs) induced by Chitosan (CTS)

The objective of the present work was to explore the effect of CTS on structural, phenotypic and functional maturation of murine bone marrow derived dendritic cells (BMDCs). The maturity of BMDCs post treatment with CTS was evaluated using transmission electron microscopy (TEM) for structure changes, flow cytometry (FCM) for changes of key surface molecules, FITC-dextran bio-assay for phagocytosis, test of acid phosphatase activity (ACP) for biochemical changes and enzyme linked immunosorbent assay (ELISA) for cytokine level. We found that CTS downregulated the numbers of phagosomes inside the BMDCs, up-regulated the expression of MHC II, CD40, CD83, CD80 and CD86 molecules on BMDCs, decreased activity of ACP and phagocytosis by BMDCs, and induced production of higher levels of IL-12 and TNF-α. It was therefore confirmed that CTS could effectively promote the maturation of BMDCs. Our study provided more detailed evidence and rationale to support the application of CTS as an immune stimulator for enhancing host immunity and as an adjuvant in the design of DC-based vaccines.

M cell-targeting strategy facilitates mucosal immune response and enhances protection against CVB3-induced viral myocarditis elicited by chitosan-DNA vaccine

Efficient delivery of antigen to mucosal associated lymphoid tissue is a first and critical step for successful induction of mucosal immunity by vaccines. Considering its potential transcytotic capability, M cell has become a more and more attractive target for mucosal vaccines. In this research, we designed an M cell-targeting strategy by which mucosal delivery system chitosan (CS) was endowed with M cell-targeting ability via conjugating with a CPE30 peptide, C terminal 30 amino acids of clostridium perfringens enterotoxin (CPE), and then evaluated its immune-enhancing ability in the context of coxsackievirus B3 (CVB3)-specific mucosal vaccine consisting of CS and a plasmid encoding CVB3 predominant antigen VP1. It had shown that similar to CS-pVP1, M cell-targeting CPE30-CS-pVP1 vaccine appeared a uniform spherical shape with about 300 nm diameter and +22 mV zeta potential, and could efficiently protect DNA from DNase I digestion. Mice were orally immunized with 4 doses of CPE30-CS-pVP1 containing 50 μg pVP1 at 2-week intervals and challenged with CVB3 4 weeks after the last immunization. Compared with CS-pVP1 vaccine, CPE30-CS-pVP1 vaccine had no obvious impact on CVB3-specific serum IgG level and splenic T cell immune responses, but significantly increased specific fecal SIgA level and augmented mucosal T cell immune responses. Consequently, much milder myocarditis and lower viral load were witnessed in CPE30-CS-pVP1 immunized group. The enhanced immunogenicity and immunoprotection were associated with the M cell-targeting ability of CPE30-CS-pVP1 which improved its mucosal uptake and transcytosis. Our findings indicated that CPE30-CS-pVP1 may represent a novel prophylactic vaccine against CVB3-induced myocarditis, and this M cell-targeting strategy indeed could be applied as a promising and universal platform for mucosal vaccine development.

A vesicular stomatitis virus-based mucosal vaccine promotes dendritic cell maturation and elicits preferable immune response against coxsackievirus B3 induced viral myocarditis

Recombinant vesicular stomatitis virus (VSV) is widely used as a vaccine platform. However, the capacity of VSV-based vaccines to induce mucosal immunity has not been fully investigated. In the present study, a recombinant VSV expressing coxsackievirus B3 (CVB3) major immunogen VP1 has been generated and the immune protection elicited by VSV-VP1 was evaluated. We demonstrated that intranasal delivery of VSV-VP1 can induce a potent antigen-specific mucosal immune response as well as a systemic immune response, particularly the induction of polyfunctional T cells. Importantly, mice immunized with VSV-VP1 were better protected against CVB3-induced viral myocarditis than those receiving a chitosan-formulated DNA vaccine. Increased dendritic cell (DC) maturation in the mesenteric lymph node (MLN) was observed in the mice vaccinated with VSV-VP1, which could be a potential mechanism for the protective immune response. These findings support VSV as a viral delivery vector that can induce robust mucosal immunity that should be considered for further vaccine development.