Innate defense regulator peptide synergizes with CpG ODN for enhanced innate intestinal immune responses in neonate piglets

The in vivo immunoadjuvant effects of the combination of CpG oligodeoxynucleotide (CpG ODN) and innate defense-regulator peptides (IDRs) have been studied in mice. However, little is known about the efficacy of these molecules in stimulating the innate intestinal immune system in neonatal piglets. In this study, we observed that intranasal (IN) administration of CpG-IDR (peptide HH2 (VQLRIRVAVIRA)) complex significantly increased intestinal mRNA expression of Th1 cytokines, CC chemokines and CXC chemokines when compared to HH2 and CpG ODN alone. Also an obvious cellular infiltration was observed in the intestine of CpG-HH2-treated neonatal piglets, which was associated with increased protection against Enterotoxigenic Escherichia coli (ETEC). Moreover, we showed that pro-inflammatory cytokine TNF-α was inhibited when CpG ODN combined with HH2. This was the first report that deciphered the role played by CpG-HH2 complex in the intestine of neonatal piglets. This work clearly demonstrated that efficiency of the IN route inducing intestinal responses in neonatal piglets might be taken into consideration for further vaccine development against neonatal intestinal diseases.     

Intranasal administration of CpG oligonucleotides induces mucosal and systemic Type 1 immune responses and adjuvant activity to porcine reproductive and respiratory syndrome killed virus vaccine in piglets in vivo

Oligonucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice. Recently, it has been showed that CpG ODN is a promising mucosal adjuvant in mice, but data on mucosal immune responses induced by CpG ODN in piglets are scarce. We have previously demonstrated that CpG ODN is a potent adjuvant to pseudorabies attenuated virus (PRV) vaccine when administered subcutaneously (SC) in newborn piglets. Herein, we evaluated intranasal (IN) delivery of CpG ODN with porcine reproductive and respiratory syndrome (PRRS) killed virus vaccine (PRRSV) to determine its potential as a mucosal adjuvant to a commercial vaccine. CpG ODN augmented systemic (IgG in serum, Peripheral blood mononuclear cells (PBMC) proliferation) and mucosal (IgA in feces, nasal and oral secretions) immune responses against antigen. CpG ODN stimulated both T-helper type1 (Type 1) (IgG2) and Type 2 (IgA) responses when delivered intranasally. Results from this study indicate that stimulatory CpG ODN may be effective as a mucosal adjuvant with commercial vaccine in husbandry animals.     

CpG oligodinucleotides induce strong humoral and cellular responses to swine streptococcic septicemia vaccine in piglets in vivo

Oligodinucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice, but data on humoral and cellular immune responses in piglets are scarce. In this report, using the swine streptococcus as model bacteria, CpG ODN was used as immunoadjuvants to enhance the immune responses of the piglets to swine streptococcic septicemia killed vaccine (SSSK vaccine). The titre of specific antibodies to SSSK vaccine, the proliferation of lymphocytes, SSSK-specific interferon-gamma(IFN-gamma) and IL-6, the expression of major histocompatibility complex class II (MHC-II) and CD14 of peripheral blood mononuclear cells (PBMCs) were examined to identify the immune responses of the piglets. The results were found that the above-mentioned immune responses of the piglets with CpG ODN were significantly stronger than standard immunization protocols. All these data suggested that immunostimulatory CpG ODN was promising immune enhancers for vaccination against SSSK vaccine.     

CpG oligodeoxynucleotide promotes protective immunity in the enteric mucosa and suppresses enterotoxigenic E. coli in the weaning piglets

CpG oligodeoxynucleotide (CpG ODN) has been described as an effective activator of the innate immune system, with potential to protect against infection caused by a range of pathogens in a non-specific manner. We therefore investigated if intranasal (IN), oral (OR)-mucosal, and intramuscular (IM)-systemic administrations of CpG ODN without antigen codelivery could all enhance innate immunity in the enteric mucosa and control the extent of enterotoxigenic Escherichia coli (ETEC) infection in weaning piglets. Here our data showed that CpG ODN dosed by IN, OR or IM routes protected weaning piglets against a subsequent challenge with ETEC. The level of protection was greater when CpG ODN was administered IN and OR than IM, demonstrating a clear relationship between the route of CpG dosing and protection. IN and OR treatments with CpG ODN reduced bacterial load in the phases at days 3–5 post challenge. The CXC chemokine (CXCL10 and CXCL11) and CC chemokine (CCL4 and CCL5) mRNA expressions were elevated in the intestinal tissues from animals treated IN or OR with CpG ODN compared to untreated controls. Significantly enhanced mRNA expressions for cathelicidins (PR-39 and protegrin-1), but moderately for β-defensin (pBD1 and pBD2), were observed in IN or OR CpG-treatments. Also, significant production of cytokines (IL-12, IFN-γ, and MCP-1) and F4-specific antibodies (IgG/IgA) was detected in intestinal washings following IN and OR CpG-treatments. In contrast, IM delivery induced marked production of sera F4-specific antibodies. It was possible that these chemokines, cytokines, cathelicidins and antibodies played a role in the clearance of ETEC. These findings suggested that IN or OR administration of CpG ODN without antigen codelivery might represent a valuable strategy for induction of innate immunity against ETEC infection.     

CpG ODN纳米粒增强免疫抑制小鼠对重组乙肝疫苗的免疫应答

目的：探讨CpG ODN壳聚糖纳米粒联合重组乙肝疫苗对免疫抑制小鼠的免疫增强作用。方法：选月环磷酰胺建立免疫抑制模型小鼠。将乙肝疫苗单独或和CpG ODN或CpG ODN纳米粒经后腿胫骨前肌注射到小鼠体内，ELISA方法检测抗HBsAg IgG抗体、IL-12水平；流式细胞仪检测外周血CD4^＋、CD8^＋T淋巴细胞亚群。结果：CpG ODN纳米粒联合疫苗组的CD4^＋细胞百分数，IL-12水平及抗HBsAg IgG抗体的含量显著高于CpG ODN联合疫苗组（P〈0．05）。结论：包裹在壳聚糖纳米粒中的CpG ODN较相同剂量的CpG ODN更能增强免疫抑制小鼠对乙肝疫苗的免疫应答。     

The efficacy of CpG oligodinucleotides, in combination with conventional adjuvants, as immunological adjuvants to swine streptococcic septicemia vaccine in piglets in vivo

Oligodinucleotides containing CpG motifs (CpG ODN) are strong adjuvants for immune responses, particularly in mice, the immunostimulatory effects of CpG in combination with aluminum hydroxide (alum) or Emulsigen (Em) were investigated in cattle, rabbits or mice, but not piglets. In this report, using the swine streptococcus as model bacteria, the efficacy of CpG ODN as an adjuvant for piglets was assessed alone and in combination with alum (CpG/alum) or Em (CpG/Em). The CpG/alum or CpG/Em combination elicited greater immune responses to swine streptococcic septicemia killed vaccine (SSSK vaccine) compared with CpG alone, or alum or Em. A GpC/alum or GpC/Em combination did not have the same effects as CpG/alum or CpG/Em suggesting that the adjuvanticity was related to the CpG motifs. In addition, we also found that the 10% Em in combination with CpG ODN had similar immunological effects as 30% Em combination. Our results demonstrate that the addition of CpG ODN to alum or to Em significantly improves the efficiency of the adjuvants in piglets.     

In vivo effects of oligodeoxynucleotides containing synthetic immunostimulatory motifs in weaned piglets

The innate immunostimulatory effects of CpG ODN have been demonstrated in mouse, monkey, sheep and chicken in some reports. Unfortunately, little work has been carried out with regard to their effects on the innate immune system of weaned piglets. In this study, the proportion of CD4(+), CD8(+) T lymphocytes subpopulations and interferon-gamma (IFN-gamma) and IL-4 in serum, proliferation of peripheral blood mononuclear cells (PBMCs) were tested at different time-points. The results suggested that, the CD4(+)/CD8(+) ratio decreased significantly in weaned piglets inoculated with phosphate buffer saline (PBS) alone, however, it was stable in CpG ODN-inoculated piglets. Proliferation of PBMCs and IFN-gamma levels of CpG ODN-injected piglets were significantly higher than those of PBS-injected piglets. The ODN-induced responses were stronger in animals injected with CpG ODN formulated in 30% emulsigen than in PBS and alum. The innate immunostimulatory activity of CpG ODN appeared to be in dose-dependent manner. These in vivo data demonstrate for the first time that CpG ODN can stimulate innate immune system in weaned piglets.     

CpG oligodeoxynucleotide-adjuvanted fusion peptide derived from HBcAg epitope and HIV-Tat may elicit favorable immune response in PBMCs from patients with chronic HBV infection in the immunotolerant phase

The absence or insufficiency of specific immune response results in chronic hepatitis B virus (HBV) infection and immunotolerance. Therapeutic fusion peptide containing hepatitis B core antigen (HBcAg)(18-27) CTL epitope and human immunodeficiency virus (HIV)-Tat(49-57) peptide was synthesized and the activity when adjuvanted with CpG oligodeoxynucleotide (CpG ODN) was evaluated in PBMCs from patients with chronic HBV infection in the immunotolerant phase in this study. Results showed that the fusion peptide when adjuvanted with CpG ODN could induce significantly higher levels of IFN-γ and IL-4 in the PBMCs compared with fusion peptide or CpG ODN alone. The magnitude of augmentation to IFN-γ by the fusion peptide plus CpG ODN was much higher than that to IL-4. Cytotoxicity assay showed that the percentage of target cell lysis by effector cells stimulated by fusion peptide plus CpG ODN was higher than that in fusion peptide or CpG ODN alone at most of the E/T ratios tested. The magnitude augmented to IFN-γ by fusion peptide plus CpG ODN was also much higher than that to the percentage of target cell lysis. It is concluded that HBcAg(18-27) and HIV-Tat(49-57) fusion peptide when adjuvanted with CpG ODN may have much higher potency to induce IFN-γ than to induce IL-4 and cytotoxicity, suggesting the favorable immune response towards noncytolytic inactivation of the virus mediated by IFN-γ and the potential to break the tolerant state in chronic HBV infection.     

CpG寡脱氧核苷酶对2型糖尿病患者外周血Th1/Th2型免疫应答的调节作用

目的观察CpG寡脱氧核苷酶(ODN)对2型糖尿病(T2DM)患者外周血单个核细胞(PBMC)γ干扰素(IFN-γ)、白细胞介素(IL)-12以及IL-10表达的影响。方法将20例T2DM患者和20名健康人PBMC根据刺激物不同分为空白对照组、CpG ODN组(2μmol/L)。用实时足量聚合酶链反应(real time-PCR)法检测PBMC IFN-γmRNAI、L-12 mRNA和IL-10 mRNA的表达。结果T2DM患者PBMC空白对照组IFN-γmRNA和IL-12 mRNA的表达低于健康人(P<0.01,P<0.05),IL-10 mRNA的表达与健康人相似(P>0.05)。经CpGODN刺激,IFN-γmRNA和IL-12 mRNA的表达高于空白对照组(P<0.01,P<0.01),但低于健康人(P<0.01,P<0.05),IL-10 mRNA的表达与空白对照组相似(P>0.05),与健康人差异无统计学意义(P>0.05)。结论CpG ODN可促进T2DM人PBMC产生IFN-γ和IL-12,增强Th1型免疫反应。     

CpG ODN mediated prevention from ovalbumin-induced anaphylaxis in mouse through B cell pathway

Allergic inflammation is induced by type 2 T helper cell (Th2) and Th2 cytokines such as interleukin (IL)-4, IL-5 and IL-13. These cytokines induce the production of allergen-specific immunoglobulin (Ig)E by B cells, and the ensuing degranulation of mast cells via IgE cross-linking leads to most clinical manifestations of allergic diseases. We examined the ability of immunomodulatory unmethylated CpG oligodeoxynucleotides (ODN), which are potent inducers of Th1 cytokines, to prevent allergic symptoms in mice immunized and sensitized with allergen. Coadministration of CpG ODN with ovalbumin (OVA) before OVA sensitization substantially prevented mice from allergic anaphylaxis representing enhanced circulating concentrations of OVA-specific IgE and histamine, and decreased body temperature. Although CpG ODN provokes an abundance of Th1-skewing cytokines, including IL-12, interferon (IFN)-alpha and IFN-gamma, administration of CpG ODN in IFN-gamma deficient mice inhibited IgE production and prevented from OVA-induced anaphylaxis, indicating a dispensable role of IFN-gamma in mediating these protective effects. In vitro analysis revealed that CpG ODN inhibited class switching from IgM to IgE and IgG1 in response to CD40 and IL-4 in B cells, and this effect did not correlate with up-regulation of IFN-alpha production. These results imply a B cell-intrinsic, T cell-independent mechanism by which CpG ODN directly acts on B cells and inhibits IgE and IgG1 production leading to cause prevention from allergic symptoms.     

Intranasal administration of peptide antigens of HIV with mucosal adjuvant CpG ODN coentrapped in microparticles enhances the mucosal and systemic immune responses

The mucosal immune system acts as a first line of defense against infection caused by luminal pathogens. Because HIV is transmitted primarily via mucosal associated tissues, particularly with sexual transmission, understanding antiviral immunity present at these sites is important. As most of the peptide antigens show poor immunogenicity when immunized alone but after incorporating the same peptide antigens along with adjuvant CpG ODN in microparticles has shown enhanced immunogenicity in the murine model. In the present study we have investigated the immunomodulatory effects of two adjuvants, CpG 1826 and CpG 2006 (Class B, Also known as type K) to the four peptide antigens of HIV such as envelope glycoproteins gp41 Leucine Zipper, gp41 fusion domain and gp120-C2 as well as regulatory protein (Nef) in microparticles, exploring nasal route with single immunization schedule. Peptide (s) alone in the microparticles elicited low peptide specific IgG and IgA peak titres in the sera, whereas the inclusion of CpG ODN with peptides in microparticles significantly enhanced peptide specific IgG and IgA peak titres and such responses were sustained for longer durations. Similarly higher SIgA response was achieved in the mucosal washes with CpG encapsulated in microparticles. Such presence of SIgA in washes was further correlated with the presence of secretory component (SC) in the respective washes. Both adjuvants induced excellent peptide specific IgG and IgA immune responses. Thus the overall study highlighted the importance of CpG ODNs as a mucosal adjuvant for weaker peptide antigens and thus can explore for developing peptide based vaccine against HIV.     

Intranasal immunization using biphasic lipid vesicles as delivery systems for OmlA bacterial protein antigen and CpG oligonucleotides adjuvant in a mouse model

The nasal mucosa is an important arm of the mucosal system since it is often the first point of contact for inhaled antigens. The ineffectiveness of the simple delivery of soluble antigens to mucosal membranes for immunization has stimulated extensive studies in appropriate delivery systems and adjuvants. We have evaluated biphasic lipid vesicles as a novel intranasal (i.n.) delivery system (designated as vaccine targeting adjuvant, VTA) containing bacterial antigens and CpG oligodeoxynucleotides (ODNs). Results show that administration of antigen and CpG ODNs in biphasic lipid vesicles resulted in greater induction of IgA levels in serum (P< 0.05) and mucosal antibody responses such as IgA in nasal secretions and lung (P< 0.01) after immunization with a combined subcutaneous (s.c.)/i.n. as compared to s.c./s.c. approach. Based on antibody responses, VTA formulations were found to be suitable as delivery systems for antigens and CpG ODNs by the intranasal route, resulting in a Th2-type of immune response, characterized by IgG1 and IL-4 production at the systemic level.     

A comparative study of the antigen-specific immune response induced by co-delivery of CpG ODN and antigen using fusion molecules or biodegradable microparticles

CpG ODN are toll-like receptor 9 (TLR9) agonists that can enhance antigen presentation by antigen presenting cells (APCs) such as dendritic cells (DCs). The most potent antigen-specific responses are seen when CpG ODN and the antigen are co-localized in the same APC. CpG ODN-antigen fusion molecules and biodegradable microparticles entrapping CpG ODN and antigen can ensure both components are delivered to the same APC. In this study, we compared the efficacy of the CpG-ODN fusion molecules against biodegradable microparticles entrapping antigen and CpG ODN. Microparticles were prepared using a double emulsion solvent evaporation methodology. CpG ODN-OVA fusion molecules were prepared by mixing maleimide-activated protein with thiolated CpG ODN. Both CpG ODN-OVA fusion molecules and microparticles co-entrapping CpG ODN and OVA generated stronger IgG2a and interferon-gamma (IFN-gamma) responses than delivery of soluble CpG ODN and OVA. The microparticles generated stronger IgG2a and IFN-gamma immune responses than did CpG ODN-antigen fusion molecules.     

Development of a Poly (lactic-co-glycolic acid) Particle Vaccine to Protect Against House Dust Mite Induced Allergy

Poly(lactic-co-glycolic acid) (PLGA) particles carrying antigen and adjuvant is a promising vaccine system which has been shown to stimulate systemic antigen-specific immune responses. In this study, we investigated the relationship of (i) the sizes of PLGA particle and (ii) the presence of cytosine-phosphate-guanine motifs (CpG), with the extent and type of immune response stimulated against Dermatophagoides pteronyssinus-2 (Der p2) antigen. Different sizes of PLGA particles encapsulating CpG were prepared using a double emulsion solvent evaporation method. Mice were vaccinated with Der p2 and different sizes of empty or CpG-loaded PLGA particles. Vaccinated mice were exposed to daily intranasal instillation of Der p2 for 10 days followed by euthanization to estimate leukocyte accumulation in bronchoalveolar lavage (BAL) fluids, antibody profiles, and airway hyperresponsiveness. PLGA particles showed a size-dependent decrease in the proportion of eosinophils found in BAL fluids. Mice vaccinated with the Der p2 coated on 9-μm-sized empty PLGA particles showed increased levels of IgE and IgG1 antibodies as well as increased airway hyperresponsiveness. All sizes of PLGA particles encapsulating CpG prevented airway hyperresponsiveness after Der p2 exposures. Inflammatory responses to Der p2 exposure were significantly reduced when smaller PLGA particles were used for vaccination. In addition, encapsulating CpG in PLGA particles increased IgG2a secretion. This study shows that the size of PLGA particles used for vaccination plays a major role in the prevention of house dust mite-induced allergy and that incorporation of CpG into the PLGA particles preferentially develops a Th1-type immune response.     

DNA-based vaccination against hepatitis B virus using dissolving microneedle arrays adjuvanted by cationic liposomes and CpG ODN

DNA vaccines are simple to produce and can generate strong cellular and humoral immune response, making them attractive vaccine candidates. However, a major shortcoming of DNA vaccines is their poor immunogenicity when administered intramuscularly. Transcutaneous immunization (TCI) via microneedles is a promising alternative delivery route to enhance the vaccination efficacy. A novel dissolving microneedle array (DMA)-based TCI system loaded with cationic liposomes encapsulated with hepatitis B DNA vaccine and adjuvant CpG ODN was developed and characterized. The pGFP expression in mouse skin using DMA was imaged over time. In vivo immunity tests in mice were performed to observe the capability of DMA to induce immune response after delivery of DNA. The results showed that pGFP could be delivered into skin by DMA and expressed in skin. Further, the amount of expressed GFP was likely to peak at day 4. The immunity tests showed that the DMA-based DNA vaccination could induce effective immune response. CpG ODN significantly improved the immune response and achieved the shift of immune type from predominate Th2 type to a balance Th1/Th2 type. The cationic liposomes could further improve the immunogenicity of DNA vaccine. In conclusion, the novel DMA-based TCI system can effectively deliver hepatitis B DNA vaccine into skin, inducing effective immune response and change the immune type by adjuvant CpG ODN.     

CpG oligonucleotides as adjuvants for vaccines targeting infectious diseases

Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs act as immune adjuvants, accelerating and boosting antigen-specific immune responses. CpG motifs promote the induction of Th1 and pro-inflammatory cytokines and support the maturation/activation of professional antigen presenting cells (particularly plasmacytoid dendritic cells). These effects are optimized by maintaining close physical contact between the CpG ODN and the immunogen. Co-administering CpG ODN with a variety of vaccines has improved the resultant humoral and/or cellular immune responses, culminating in enhanced protective immunity in rodent and primate challenge models. Ongoing clinical studies indicate that CpG ODN are safe and well-tolerated when administered as adjuvants to humans, and that they can support increased vaccine-specific immune responses.     

Evaluation of the immune response following a short oral vaccination schedule with hepatitis B antigen encapsulated into alginate-coated chitosan nanoparticles

The purpose of this work was to assess the ability of recombinant hepatitis B vaccine, encapsulated in alginate-coated chitosan nanoparticles, to induce local and systemic immune responses following oral vaccination. The antigen was administered either alone or in combination with the immunopotentiator, synthetic oligodeoxynucleotide containing immunostimulatory CpG motif (CpG ODN) as adjuvant, and associated or not with the alginate-coated chitosan nanoparticles. After two immunizations the group I (HBsAg associated with nanoparticles) and the group VI (HBsAg and CpG, both associated with nanoparticles) showed enhanced immune responses. Both groups showed significant higher values of the CD69 expression in CD4+ and CD8+ T-lymphocytes and lower values of this marker in B lymphocytes. Moreover, a strongest proliferative response of the splenocytes, ex vivo stimulated with concanavalin A, was observed in the same groups. Although with a presence of non-responder mice within the groups, only mice of the groups I and VI elicited the generation of anti-HBsAg antibodies detected in serum (IgG) and in the intestinal washings (sIgA). The results demonstrated that coated chitosan nanoparticles might have potential for being used as a deliver system for oral vaccination with the recombinant hepatitis B surface antigen.     

Multiple antigen peptide consisting of B- and T-cell epitopes of F1 antigen of Y. pestis showed enhanced humoral and mucosal immune response in different strains of mice

Yersinia pestis is a causative agent of plague. F1 and V antigen based vaccines have shown remarkable protection in experimental animals. In order to develop epitope based immunogen, three B and one T-cell epitopes of F1 antigen with palmitate residue at amino terminal were assembled on a lysine backbone as multiple antigen peptide (MAP or F1-MAP). MAP was characterized by SDS-PAGE, immunoblot and immunoreactivity with anti F1 sera. MAP was entrapped in PLGA (polylactide-co-glycolide) microparticles and humoral, mucosal immune responses were studied after intranasal immunization with/without CpG ODN 1826 (CpG)/murabutide in different strains of mice. Serum and mucosal washes were measured for MAP specific IgG, IgA, sIgA and IgG subclasses in three strains of mice. F1-MAP showed high serum antibody and mucosal IgG and IgA peak antibody titers. MAP with CpG showed significantly high (p < 0.001) peak antibody titer ranging from 102,400 to 204,800 for IgG and 6400 to 12,800 for IgA. High mucosal sIgA and its secretary component detection confirmed generation of mucosal response in intestinal and lung washes. MAP antisera also showed significant immunoreactivity with individual peptides. Moreover, antibody specific activity (IgG, IgA and sIgA) positively correlates with peak antibody titers. Predominantly IgG2a/IgG2b subclass was observed with CpG formulation but in other formulation a mixed IgG1 and IgG2a response was observed. The present study highlights the importance of multiple antigen peptide approach of F1-antigen with CpG as an alternative approach for subunit vaccine.     

Encapsulating immunostimulatory CpG oligonucleotides in listeriolysin O-liposomes promotes a Th1-type response and CTL activity

Immunostimulatory sequences (ISS) are short DNA sequences containing unmethylated CpG dimers that have multiple effects on the host immune system, including the ability to stimulate antigen-specific cytotoxic T lymphocytes (CTLs) and drive Th1-type immune responses. Listeriolysin O (LLO)-containing pH-sensitive liposomes have been shown to efficiently deliver macromolecules to the cytosol of APCs and efficiently stimulate CTLs. We hypothesized that encapsulating ISS-oligodeoxyribonucleotides (ODNs) in this delivery system would enhance the cell-mediated immune response and skew Th1-type responses in protein antigen-based vaccination utilizing LLO-liposomes. In vitro studies indicated that coencapsulation of ISS in LLO-liposomes engendered activation of the NF-κB pathway while maintaining the efficient cytosolic delivery of antigen mediated by the coencapsulated LLO. Antigen-specific CTL responses monitored by using the model antigen ovalbumin (OVA) in mice were enhanced when mice were immunized with OVA and ISS-ODN-containing LLO-liposomes compared with those immunized with OVA-containing LLO-liposomes. The enhanced immune responses were of the Th1-type as monitored by the robust OVA-specific IgG2a induction and the OVA CD8 peptide-stimulated IFN-γ secretion. Our study suggests that including ISS-ODN in LLO-containing pH-sensitive liposomes yields a vaccine delivery system that enhances the cell-mediated immune response and skews this response toward the Th1-type.     

Alginate coated chitosan nanoparticles are an effective subcutaneous adjuvant for hepatitis B surface antigen

We recently described a delivery system that is composed of a chitosan core to which the hepatitis B surface antigen (HBsAg) was adsorbed and subsequently coated with sodium alginate. In this present work, alginate coated chitosan nanoparticles were evaluated as a subcutaneous adjuvant for HBsAg. HBsAg loaded, alginate coated or uncoated chitosan nanoparticles, associated or not with CpGODN were subcutaneously administered to mice and several immunological parameters were evaluated. A high anti-HBsAg IgG titer (2271+/-120 mIU/ml), with the majority of antibodies being of Th2 type, was observed within group I, vaccinated with HBsAg loaded onto coated nanoparticles. However, regarding cellular immune response, no significant differences were observed for antigen-specific splenocyte proliferation or for the secretion of IFN-gamma and IL-4, when compared to the control group. The co-delivery of antigen-loaded nanoparticles in the presence of the immunopotentiator, CpG ODN 1826, resulted in an increase of anti-HBsAg IgG titers that was not statistically different from the first group; however, an increase of the IgG2a/IgG1 ratio from 0.1 to 1.0 and an increase (p<0.01) of the IFN-gamma production by the splenocytes stimulated with the HBV antigen was observed. The enhancement of the immune response observed with the antigen-loaded nanoparticles demonstrated that chitosan is a promising platform for parenteral HBsAg delivery and, when co-administered with the CpG ODN, resulted in a mixed Th1/Th2 type immune response.