Antigen-specific Cellular Immune Responses Research Articles

High Molecular Weight Chitosan-Complexed RNA Nanoadjuvant for Effective Cancer Immunotherapy.

Nucleic acid-based adjuvants have recently emerged as promising candidates for use in cancer vaccines to induce tumor-suppressing immune cells. In this study, we tested whether complexation of a nucleic acid-based adjuvant with chitosan (CTS) modulates immune adjuvant functions. As a nucleic acid-based adjuvant, we used toll-like receptor 3-recognizing RNA adjuvant (RA). Negatively charged RA formed nanoscale polyplexes with cationic CTS that possessed positive zeta potentials. RA/CTS polyplexes exerted dendritic cell (DC)-maturation effects without causing significant DC toxicity. This DC-maturation effect was CTS molecular weight dependent, with RA/CTS polyplexes with a CTS molecular weight of 340 kDa (RA/CTS 340K) producing the greatest effect. Subcutaneous injection of RA/CTS 340K polyplexes with the model tumor antigen ovalbumin exerted a preventive effect against challenge by ovalbumin-expressing tumor cells. It also provided greater inhibitory effects against a second challenge with the same tumor cells compared with other treatments. These protective effects of subcutaneous RA/CTS polyplex treatment were associated with the highest tumor antigen-specific humoral and cellular immune responses after tumor challenge, and with the greatest infiltration of CD4 helper T cell and CD8 T cell into the tumor tissues. Mice vaccinated with ovalbumin and RA/CTS polyplexes showed complete survival, even after repeated challenge with tumor cells. Our results suggest the potential of RA/CTS polyplexes as effective nanoadjuvants in the design of tumor vaccines and cancer immunotherapy.

Dissolving undercut microneedle arrays for multicomponent cutaneous vaccination

The skin is an attractive tissue target for vaccination, as it is readily accessible and contains a dense population of antigen-presenting and immune-accessory cells. Microneedle arrays (MNAs) are emerging as an effective tool for in situ engineering of the cutaneous microenvironment to enable diverse immunization strategies. Here, we present novel dissolving undercut MNAs and demonstrate their application for effective multicomponent cutaneous vaccination. The MNAs are composed of micron-scale needles featuring pyramidal heads supported by undercut stem regions with filleted bases to ensure successful skin penetration and retention during application. Prior efforts to fabricate dissolving undercut microstructures were limited and required complex and lengthy processing and assembly steps. In the current study, we strategically combine three-dimensional (3D) laser lithography, an emerging micro-additive manufacturing method with unique geometric capabilities and nanoscale resolution, and micromolding with favorable materials. This approach enables reproducible production of dissolving MNAs with undercut microneedles that can be tip-loaded with multiple biocargos, such as antigen (ovalbumin) and adjuvant (Poly(I:C)). The resulting MNAs fulfill the geometric (sharp tips and smooth edges) and mechanical-strength requirements for failure-free penetration of human and murine skin to simultaneously deliver multicomponent (antigen plus adjuvant) vaccines to the same cutaneous microenvironment. Cutaneous vaccination of mice using these MNAs induces more potent antigen-specific cellular and humoral immune responses than those elicited by traditional intramuscular injection. Together, the unique geometric features of these undercut MNAs and the associated manufacturing strategy, which is compatible with diverse drugs and biologics, could enable a broad range of non-cutaneous and cutaneous drug delivery applications, including multicomponent vaccination.

Humoral and cellular immunity to measles and rubella virus antigens in healthy subjects

An issue of eradicating measles and rubella virus-induced infections currently remains unresolved, despite existing effective methods for specific prophylaxis and WHO’s commitment to a mass vaccination policy. While improving epidemic situation, analysis of new challenges, such as measles incidence in adults, especially in adults vaccinated in childhood, is of particular interest. The aim of the study was to analyze serum measles and rubella virus-specific IgG antibodies in young healthy people and estimate antigen-specific cellular immune response in seronegative subjects. There were examined 100 healthy adults aged 18–30 years old. Level of serum specific IgG was measured by ELISA (Vector-Best, Russia). Antigen-specific cellular immune response was assessed by magnitude of surface CD107a expression on CD8hi T cells challenged by measles and rubella virus-derived antigens. It was found that average level of antibodies against rubella virus comprised 175.5 IU/ml, 49% of which recovered after rubella, 46% were vaccinated, whereas 5% subjects contained no virus-specific antibodies. In addition, mean level of anti-measles virus antibodies was below protective magnitude, among which 1% subjects recovered after measles, 31% displayed post-vaccination immunity, 55% subjects were seronegative, and 13% had equivocal levels of specific antibodies. Thus, 68% subjects were unprotected against measles virus based on the level of serum virus-specific antibodies. Moreover, 40 out of 68 subjects were vaccinated against measles in childhood. Additional screening adult subjects for intensity of measles and rubella virus-specific cellular immunity demonstrated that 57.37% of them contained peripheral blood CD8 T cells against measles virus and 59.01% — against rubella virus. Further analysis allowed to identify 4 subgroups displaying: 1) high level of virus-specific antibodies and T cells; 2) neither antibodies nor specific T-cells reaching as low as 20% of baseline group; 3) high antibody level combined with low amount of specific T cells; and 4) low antibody level combined with high level of specific T cells. thus, it may be assumed that cellular and humoral immune arms are maintained independently and being active for a long term after vaccination. Preserving a specific T-cell immunity seems to provide protection against infection, thereby accounting for the lack of measles manifestation in all seronegative subjects.

Oral Vaccination with Hepatitis E Virus Capsid Protein and Immunobiotic Bacterium-Like Particles Induce Intestinal and Systemic Immunity in Mice.

The hepatitis E virus (HEV) genotype 3 (GT3) is an emergent pathogen in industrialized countries. It is transmitted zoonotically and may lead to chronic hepatitis in immunocompromised individuals. We evaluated if the major antigen of HEV, the capsid protein, can be used in combination with immunobiotic bacterium-like particles (IBLP) for oral vaccination in a mouse model. We have cloned and expressed the RGS-His5-tagged HEV GT3 capsid protein (ORF2) in E. coli and purified it by NiNTA. IBLP were obtained from two immunobiotic Lactobacillus rhamnosus strains acid- and heat-treated. ORF2 and the IBLP were orally administered to Balb/c mice. After three oral immunizations (14-day intervals), blood, intestinal fluid, Peyer´s patches, and spleen samples were drawn. IgA- and IgG-specific antibodies were determined by ELISA. Mononuclear cell populations from Peyer's patches and spleen were analyzed by flow cytometry, and the cytokine profiles were determined by ELISA to study cellular immunity. Orally administered recombinant ORF2 and IBLP from two L. rhamnosus strains (CRL1505 and IBL027) induced both antigen-specific humoral and cellular immune responses in mice. IBLP027 was more effective in inducing specific secretory IgA in the gut. IFN-γ, TNF-α, and IL-4 were produced by Peyer's plaques lymphocytes stimulated with ORF2 ex vivo suggesting a mixed Th1/Th2-type adaptive immune response in immunized mice. Oral vaccines are not invasive, do not need to be administered by specialized personal, and elicit both systemic and local immune responses at the port of entry. Here, we present an experimental oral vaccine for HEV GT3, which could be further developed for human and/or veterinary use.

Development of pH-Responsive Hyaluronic Acid-Based Antigen Carriers for Induction of Antigen-Specific Cellular Immune Responses.

Cancer immunotherapy has gained much attention because of the recent success of immune checkpoint inhibitors. Nevertheless, clinical therapeutic effects of immune checkpoint inhibitors remain limited, probably because most patients have other immune checkpoint molecules or because they lack cancer-specific cytotoxic T lymphocytes. Induction of cancer-specific cytotoxic T lymphocytes requires efficient antigen delivery systems that can convey cancer antigens specifically to antigen presenting cells, promote the endosomal escape of antigen into cytosol, and activate immune cells. Earlier, we reported cytoplasmic delivery systems of antigen using pH-sensitive polymer-modified liposomes. Adjuvant molecules were further incorporated into these liposomes to provide activation properties of cellular immune responses. This study further introduced cell specificity to these liposomal systems using hyaluronic acid-based pH-sensitive polymers, which are recognized by CD44 expressing on antigen presenting cells. pH-Sensitive hyaluronic acid derivative-modified liposomes showed much higher cellular association to antigen presenting cells than to fibroblasts with less CD44 expression. These liposomes achieved the delivery of model antigenic proteins into cytosol of dendritic cells and promoted Th1 cytokine production from the cells. Subcutaneous administration of these liposomes to mice induced antigen-specific cellular immune response in the spleen, leading to tumor regression in tumor-bearing mice. The results show that pH-sensitive hyaluronic acid derivative-modified liposomes are promising as multifunctional antigen carriers having cell-specificity, cytoplasmic antigen delivery performance, and adjuvant property to induce antigen-specific cellular immunity.

Recombinant adenoviral vaccine encoding the spike 1 subunit of the Middle East Respiratory Syndrome Coronavirus elicits strong humoral and cellular immune responses in mice.

Background and Aim:Middle East respiratory syndrome coronavirus (MERS-CoV) has rapidly spread throughout the Middle East since its discovery in 2012. The virus poses a significant global public health threat with potentially devastating effects. In this study, a recombinant adenoviral-based vaccine encoding the spike 1 (S1) subunit of the MERS-CoV genome was constructed, and its humoral, and cellular immune responses were evaluated in mice.Materials and Methods:Mice were immunized initially by intramuscular injection and boosted 3 weeks later by intranasal application. Expression of the S1 protein in the lungs and kidneys was detected using conventional polymerase chain reaction (PCR) and immunohistochemistry (IHC) targeting specific regions within the S1 subunit at weeks 3, 4, 5, and 6 after the first vaccination. Antigen-specific humoral and cellular immune responses were evaluated in serum and in cell culture following in vitro stimulation with a specific 9-mer epitope within the S1 protein (CYSSLILDY).Results:S1 protein expression was only detected by IHC in the kidneys of the Ad-MERS-S1 group at week 6 from first immunization, and in both lungs and kidneys of Ad-MERS-S1 group by conventional PCR at weeks 3 and 5 post-prime. The vaccine elicited a specific S1-immunoglobulin G antibody response, which was detected in the sera of the vaccinated mice at weeks 4 and 6 from the onset of the first immunization. There was a significant increase in the amount of Th1-related cytokines (interferon-γ and interleukin [IL] 12), and a significant decrease in the Th2-related cytokine IL-4 in splenocyte cell culture of the vaccinated group compared with the control groups.Conclusion:The results of this study suggest that this recombinant adenovirus vaccine encoding the S1 subunit of MERS-CoV elicits potentially protective antigen-specific humoral and cellular immune responses in mice. This study demonstrates a promising vaccine for the control and/or prevention of MERS-CoV infection in humans.

Yeast-produced subunit protein vaccine elicits broadly neutralizing antibodies that protect mice against Zika virus lethal infection

Zika virus (ZIKV) infection is a serious public health concern due to its ability to induce neurological defects and its potential for rapid transmission at a global scale. However, no vaccine is currently available to prevent ZIKV infection. Here, we report the development of a yeast-derived subunit protein vaccine for ZIKV. The envelope protein domain III (EDIII) of ZIKV was produced as a secretory protein in the yeast Pichia pastoris. The yeast-derived EDIII could inhibit ZIKV infection in vitro in a dose-dependent manner, suggesting that it had acquired an appropriate conformation to bind to cellular receptors of ZIKV. Immunization with recombinant EDIII protein effectively induced antigen-specific binding antibodies and cellular immune responses. The resulting anti-EDIII sera could efficiently neutralize ZIKV representative strains from both Asian and African lineages. Passive transfer with the anti-EDIII neutralizing sera could confer protection against lethal ZIKV challenge in mice. Importantly, we found that purified anti-EDIII antibodies did not cross-react with closely related dengue virus (DENV) and therefore did not enhance DENV infection. Collectively, our results demonstrate that yeast-produced EDIII is a safe and effective ZIKV vaccine candidate.

Multiple viral proteins and immune response pathways act to generate robust long-term immunity in Sudan virus survivors

BackgroundProfiles of immunity developed in filovirus patients and survivors have begun to shed light on antigen-specific cellular immune responses that had been previously under-studied. However, our knowledge of the breadth and length of those responses and the viral targets which mediate long-term memory immunity still lags significantly behind. MethodsWe characterized antigen-specific immune responses in whole blood samples of fifteen years post-infected survivors of the Sudan virus (SUDV) outbreak in Gulu, Uganda (2000−2001). We examined T cell and IgG responses against SUDV complete antigen and four SUDV proteins; glycoprotein (GP), nucleoprotein (NP), and viral protein 30 (VP30), and 40 (VP40). FindingsWe found survivors-maintained antigen-specific CD4+ T cell memory immune responses mediated mainly by the viral protein NP. In contrast, activated CD8+ T cell responses were nearly absent in SUDV survivors, regardless of the stimulating antigen used. Analysis of anti-viral humoral immunity revealed antigen-specific IgG antibodies against SUDV and SUDV proteins. Survivor IgGs mediated live SUDV neutralization in vitro and FcγRI and FcγRIII antibody Fc-dependent responses, mainly via antibodies to the viral proteins GP and VP40. InterpretationWe highlight the key role of several proteins, i.e., GP, NP, and VP40, to act as mediators of distinctive and sustained cellular memory immune responses in long-term SUDV survivors. We suggest that the inclusion of these viral proteins in vaccine development may best mimic survivor native memory immune responses with the potential of protecting against viral infection. FundsThis research was funded by the Defense Threat Reduction Agency (CB4088) and by the National Institute Of Allergy And Infectious Diseases of the National Institutes of Health under Award Number R01AI111516. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Abstract CT114: INO-5401 and INO-9012 delivered by electroporation (EP) in combination with cemiplimab (REGN2810) in newly-diagnosed glioblastoma (GBM) (NCT03491683)

Abstract Despite advances in therapy, glioblastoma (GBM) remains one of the most deadly cancers, with five-year survival under 5%. Newer immunotherapies hold promise in the treatment of GBM, and T cell-enabling therapies may improve progression-free and overall survival for newly-diagnosed patients. Checkpoint inhibitors, such as PD-1 inhibitors, have increased response rates in many cancers, but not yet in GBM. In this study, a novel antigen-specific T cell-generating therapy, INO-5401, combined with INO-9012, together with a PD-1 checkpoint inhibitor, cemiplimab, will be given to patients with newly-diagnosed GBM in order to evaluate tolerability, immunogenicity and any activity of the combination. INO-5401 is a mixture of three synthetic plasmids that target Wilms tumor gene-1 (WT-1) antigen, prostate specific membrane antigen (PSMA), and human telomerase reverse transcriptase (hTERT) antigen. INO-9012 is a plasmid encoding human interleukin-12 (IL-12) p35 and p40 subunit proteins. In preclinical studies, targeting WT-1, PSMA and hTERT induced robust cellular immune responses and slowed tumor growth in murine tumor implantation and ALL models. This is a Phase I/IIA, open-label, multi-center trial to evaluate the safety, immunogenicity and preliminary clinical efficacy of INO-5401 + INO-9012 delivered by intramuscular (IM) injection followed by electroporation (EP), in combination with cemiplimab, and radiation and chemotherapy, in participants with newly-diagnosed GBM. INO-5401 + INO-9012 will be administered Q3w for the first four doses, and then Q9w until disease progression. Cemiplimab will be administered Q3w until disease progression. The trial population is divided into two cohorts: Cohort A are patients with an unmethylated O6-methylguanine-deoxyribonucleic acid (DNA) methyltransferase (MGMT) promoter; and Cohort B are patients with a methylated O6-methylguanine-deoxyribonucleic acid (DNA) methyltransferase (MGMT) promoter. Both cohorts will receive radiation and temozolomide (TMZ), if clinically indicated, in combination with study therapies. Cohort B will continue TMZ for a total of 6 cycles. A safety run-in will be performed with up to six participants (safety analysis participants) from Cohort A and Cohort B. Correlative studies include the assessment of antigen-specific cellular immune responses in peripheral blood and tumor tissue. Fifty-two patients are estimated to be enrolled, 32 in Cohort A and 18 in Cohort B. Enrollment began in May of 2018 and the trial is continuing to accrue as planned. Citation Format: David Reardon, Seema Nagpal, Scott Soltys, Steven Brem, Antonio Omuro, Macarena De La Fuente, Amy-Lee Bredlau, Isreal Lowy, Matthew Fury, Matthew Morrow, Kim Kraynyak, Trevor McMullan, Ashley L. Santo, Brian Sacchetta, Jeffrey Skolnik. INO-5401 and INO-9012 delivered by electroporation (EP) in combination with cemiplimab (REGN2810) in newly-diagnosed glioblastoma (GBM) (NCT03491683) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT114.

Abstract CT177: INO-5401 + INO-9012 in combination with atezolizumab for locally advanced unresectable or metastatic/recurrent urothelial carcinoma

Abstract Background: Advanced urothelial carcinoma (UCa; bladder cancer) remains a deadly disease with patients often failing to respond to, or ineligible for, platinum-based therapy. Checkpoint inhibitors (CPIs) have increased response rates, but a majority of patients remain refractory to such agents or relapse. In this study, a novel antigen-specific T cell-generating therapy, INO-5401, combined with INO-9012, together with a CPI will be given to patients with advanced UCa with the aim of demonstrating tolerability, immunogenicity and efficacy (ORR, DoR, PFS, OS) of the combination. INO-5401 is a mixture of three synthetic plasmids that target Wilms tumor gene-1 (WT-1) antigen, prostate specific membrane antigen (PSMA) and human telomerase reverse transcriptase (hTERT) antigen. INO-9012 is a plasmid encoding human interleukin-12 (IL-12) p35 and p40 subunit proteins. In preclinical studies, targeting WT-1, PSMA and hTERT induced robust cellular immune responses and slowed tumor growth in murine tumor implantation and ALL models. Methods: This is a Phase I/IIA, open-label, multi-center trial to evaluate the safety, immunogenicity and preliminary clinical efficacy of INO-5401 + INO-9012 delivered by intramuscular (IM) injection followed by electroporation (EP) in combination with atezolizumab in participants with locally advanced unresectable or metastatic/recurrent UCa. INO-5401 + INO-9012 is administered Q3w for the first 4 doses, Q6w for the next 6 doses and Q12w thereafter until disease progression. Atezolizumab will be delivered Q3w until disease progression. The trial population includes Cohort A patients with confirmed disease progression during or following treatment with anti-Programmed Death receptor-1/Programmed Death receptor Ligand-1 (anti-PD-1/PD-L1) therapy and Cohort B patients who are treatment naïve and ineligible for cisplatin-based chemotherapy. All patients must have locally advanced unresectable or metastatic/recurrent UCa, measurable disease without previously treated target lesions (unless progressed following therapy) and ECOG of 0-1. Patients must not have had any approved anti-cancer therapy within 2 weeks of enrollment, nor any investigational therapy within 4 weeks of enrollment, any other malignancies within 3 yrs of enrollment, any autoimmune disease, and any immunostimulatory or immunosuppressive treatments. A safety run-in will be performed with up to six patients from Cohort A. Correlative studies include the assessment of antigen-specific cellular immune responses in peripheral blood and tumor tissue. ClinicalTrials.gov NCT03502785. EudraCT 2018-000309-21. Enrollment: Eighty-five patients are estimated to be enrolled. Enrollment began May 2018 and is continuing to accrue as planned. The safety run-in has been completed (no DLTs were observed in participants dosed to date), and the study is now open to full enrollment. Citation Format: Jeffrey Skolnik, Noah Hahn, Joaquim Bellmunt, Samantha Rosencranz, Malissa Diehl, Matthew Morrow, Kimberly Kraynyak, Trevor McMullan. INO-5401 + INO-9012 in combination with atezolizumab for locally advanced unresectable or metastatic/recurrent urothelial carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT177.

Abstract 2732: Frameshift neoantigen vaccination prevent Lynch syndrome mouse model intestinal cancer

Abstract Microsatellite-unstable (MSI) cancers occurring in the context of Lynch syndrome elicit pronounced tumor-specific immune responses directed against frameshift peptide (FSP) neoantigens, which result from mismatch repair (MMR) deficiency-induced insertion/deletion mutations in coding microsatellites (cMS). We have recently completed a clinical phase I/IIa trial that successfully demonstrated safety and immunogenicity of an FSP neoantigen-based vaccine in MSI colorectal cancer patients (Clinical trial number: NCT01461148). The vaccine was safe and induced robust cellular and humoral immune responses in all vaccinated patients. To further develop a cancer preventive vaccine against MSI cancers in Lynch syndrome, we aimed to establish a preclinical mouse model. A systematic database search was performed to identify cMS sequences in the murine genome. Subsequently, intestinal tumors obtained from Lynch syndrome mice (Msh2flox/flox VpC+/+) were evaluated for mutations affecting these candidate microsatellites. Thirteen candidate cMS were detected that presented with a mutation frequency of 15% or higher. Epitope prediction using the netMHC4.0 algorithm was performed, and ten most promising FSP neoantigens were synthesized. Immunogenicity was evaluated after vaccination of C57BL/6 mice using IFN-gamma ELISpot. Four FSP neoantigens derived from cMS mutations in the genes Nacad, Maz, Xirp1, and Senp6 elicited strong antigen-specific cellular immune responses. CD4-specific T cell responses were detected for Maz, Nacad, and Senp6 and CD8-positive T cells were detected for Xirp1 and Nacad. Vaccination with peptides encoding these four intestinal cancer FSP neoantigens promoted anti-neoantigen immunity, reduced intestinal tumorigenicity and prolonged overall survival (P<0.01). Additionally, NSAIDs, which have chemopreventive efficacy for Lynch syndrome, increase T cell immunity against neoantigens. Mechanistic tumor mutation burden and adaptive immune response studies will be shown. In summary, these data support the further development of vaccination strategies for preventing cancers associated with Lynch syndrome. Citation Format: Ozkan Gelincik, Hamza Ibrahim, Mine Ozkan, Aysel Ahadova, Shizuko Sei, Robert Shoemaker, Mattias Kloor, Magnus Von Knebel Doeberitz, Steven M. Lipkin. Frameshift neoantigen vaccination prevent Lynch syndrome mouse model intestinal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2732.

Enzyme-linked immunospot assay to monitor antigen-specific cellular immune responses in mouse tumor models.

Critical to the advancement of tumor immunotherapy is the reliable identification of responders and the quantification of the tumor-specific immune response elicited by treatments. In this regard, Enzyme-Linked Immunospot assay (ELISpot) is an ideal monitoring technique due to its high sensitivity, ease of execution and cost-effectiveness. Originally developed for the enumeration of B cells secreting antigen-specific antibodies, ELISpot assay has been adapted to detect and quantify cytokine-secreting immune cells present at low frequency in a variety of biological samples, including blood, in response to antigen-specific stimuli. The above-mentioned features emphasize the role of ELISpot as valuable assay for translational research and clinical applications. In the present chapter, we will focus on the use of ELISpot assay for monitoring the tumor-specific effector responses induced by different treatments in preclinical models and will provide some protocols and technical hints for its application.

Adjuvant activity of PCP-II, a polysaccharide from Poria cocos, on a whole killed rabies vaccine

Adjuvants are important components of vaccination strategies because they boost and accelerate the immune response. The aim of this study was to investigate the adjuvant activity of PCP-II, a polysaccharide isolated from Poria cocos, together with an inactivated rabies vaccine. The polysaccharide PCP-II was compared with the common veterinary rabies vaccine adjuvant Alhydrogel by co-administration of either adjuvant with the inactivated rabies virus rCVS-11-G to mice via the intramuscular route. Blood samples were collected to determine the virus-neutralizing antibody (VNA) titer and assess activation of B and T lymphocytes. Inguinal lymph node samples were collected, and proliferation of B lymphocytes was measured. Splenocytes were isolated, and antigen-specific cellular immune responses were evaluated by enzyme-linked immunospot and immunosorbent assays (ELISpot assay and ELISA, respectively). The results showed that PCP-II enhanced and promoted an increase in the VNA titer in the mice compared to Alhydrogel. Flow cytometry assays revealed that the polysaccharide activated more B lymphocytes in the lymph nodes and more B and T lymphocytes in the blood. Assessment of antigen-specific cellular immune responses showed that PCP-II strongly induced T lymphocyte proliferation in the spleen and high levels of cytokine secretion from splenocytes. All of these data suggest that PCP-II possesses excellent adjuvant activity and enhances both cellular and humoral immunity in mice.After examining the adjuvant activities of PCP-II in mice, dogs were immunized with rCVS-11-G together with Alhydrogel or PCP-II as an adjuvant; the control group was injected with a commercial rabies vaccine. Serum samples were collected, and the VNA titers were measured. PCP-II caused increases in the VNA titers in both the booster and single-dose immunization tests when co-administered with rCVS-11-G compared with Alhydrogel. The VNA titer of the commercial vaccine group was also significantly lower than that of the PCP-II group. These data indicate that PCP-II is an excellent candidate adjuvant for inactive rabies vaccines in the veterinary setting.

Sudachitin, polymethoxyflavone from Citrus sudachi, enhances antigen-specific cellular and humoral immune responses in BALB/c mice.

Scdachitin is a polymethoxyflavone (5,7,4'-trihydroxy-6,8,3-trimethoxyflavone) that is found in the peel of Citrus sudachi. We examined the effect of sudachitin on immune response in ovalbumin-immunized BALB/c mice. Treatment with sudachitin increased ovalbumin-specific IL-4 and IL-10 productions. In addition, mice that received sudachitin showed higher levels of ovalbumin-specific IgE, IgG1 and IgG l production than did control mice. The antibody response to the thymus-independent antigen 2,4,6-trinitrophenyl Ficoll was not different in the control and sudachitin groups, suggesting that sudachitin does not directly stimulate antibody production. An in vitro study showed that treatment of sudachitin enhanced the ability of antigen presentation in bone marrow-derived dendritic cells. Furthermore, CD11c+ cells that had been treated with sudachitin showed increased expression of co-stimulatory molecules. The results indicate that sudachitin regulates immune function both in vivo and in vitro.

Injectable Biodegradable Chitosan-Alginate 3D Porous Gel Scaffold for mRNA Vaccine Delivery.

mRNA vaccines have proven to be more stable, effective, and specific than protein/peptide-based vaccines in stimulating both humoral and cellular immune response. However, mRNA's fast degradation rate and low-transfection efficiency in vivo impede its potential in vaccination. Recent research in gene delivery has focused on nonviral vaccine carriers and either implantable or injectable delivery systems to improve transgene expression in vivo. Here, an injectable chitosan-alginate gel scaffold for the local delivery of mRNA vaccines is reported. Gel scaffold biodegradation rates and biocompatibility are quantified. Scaffold-mediated mRNA in vivo transgene expression as well as ovalbumin antigen specific cellular and humoral immune responses are evaluated in vivo. Luciferase reporter protein expression resulting from mRNA lipoplex-loaded gel scaffolds is five times higher than systemic injection. Compared to systemic injections of naked mRNA or mRNA:lipoplexes, elevated levels of T cell proliferation and IFN-γ secretion are seen with in vivo scaffold-mediated mRNA lipoplex delivery. Furthermore, a humoral response (ovalbumin antigen specific IgG levels) is observed as early as week 1 for scaffold-mediated mRNA lipoplex delivery, while protein-based immunization did not elicit IgG production until 2 weeks post-injection. Results suggest that injectable scaffold mRNA vaccine delivery maybe a viable alternative to traditional nucleic acid immunization methods.

Glycyrrhiza uralensis Fisch L. crude polysaccharides enhance mouse immunity and immune responses induced by HPV-DNA vaccine

Objective To investigate the effects of Glycyrrhiza uralensis Fisch L. crude polysaccharides (GUCP) as an adjuvant on the immunity of mice and the immune responses induced by human papilloma virus (HPV)-DNA vaccine. Methods ICR mice were injected with different concentrations of GUCP by different ways to detect the influences of GUCP on body weight, organ indexes and the numbers of immune cells in spleen. C57BL/6 mice were co-immunized with HPV-DNA vaccine and GUCP to detect the adjuvant efficacy on antigen-specific cellular and humoral immune responses. Results GUCP in all injected groups had no side effect on mouse body weight and liver, heart, lung and kidney indexes, but intraperitoneal injection of GUCP significantly increased spleen and thymus indexes and the numbers of B cells, CD4+ T cells, macrophages and dendritic cells in spleen. Subcutaneous injection of GUCP significantly increased the numbers of B cells and macrophages in spleen and intragastric administration significantly increased the numbers of CD4+ and CD8+ T cells in spleen. Furthermore, GUCP as an adjuvant enhanced the antigen-specific CD4+ and CD8+ T cell responses and the levels of IgG, IgG1 and IgG2a induced by HPV-DNA vaccine at a certain degree. Conclusion GUCP enhanced the immunity of mice and the antigen-specific cellular and humoral immune responses induced by HPV-DNA vaccine. These results suggested that GUCP might be used as an adjuvant for DNA vaccine. Key words: Glycyrrhiza uralensis Fisch L.; Crude polysaccharides; Immunity; DNA vaccine; Immune response

Physical activation of innate immunity by spiky particles.

Microbial biochemicals have been indicated as the primary stimulators of innate immunity, the first line of the body's defence against infections. However, the influence of topological features on a microbe's surface on immune responses remains largely unknown. Here we demonstrate the ability of TiO2 microparticles decorated with nanospikes (spiky particles) to activate and amplify the immune response in vitro and in vivo. The nanospikes exert mechanical stress on the cells, which results in potassium efflux and inflammasome activation in macrophages and dendritic cells during phagocytosis. The spiky particles augment antigen-specific humoral and cellular immune responses in the presence of monophosphoryl lipid A and elicit protective immunity against tumour growth and influenza viral infection. The study offers insights into how surface physical cues can tune the activation of innate immunity and provides a basis for engineering particles with increased immunogenicity and adjuvanticity.

Mechanistic study of the adjuvant effect of chitosan-aluminum nanoparticles

The use of tailored particle-based adjuvants constitutes a promising way to enhance antigen-specific humoral and cellular immune responses. However, a thorough understanding of the mechanisms underlying their adjuvanticity is crucial to generate more effective vaccines. We studied the ability of chitosan-aluminum nanoparticles (CH-Al NPs), which combine the immunostimulatory effects of chitosan and aluminum salts, to promote dendritic cell activation, assess their impact on innate and adaptive immune responses, and compare the results to those reported for conventional chitosan particles (CH-Na NPs). All tested CH-NP formulations were capable of modulating cytokine secretion by dendritic cells. CH-Al NPs promoted NLRP3 inflammasome activation, enhancing the release of IL-1β without significantly inhibiting Th1 and Th17 cell-polarizing cytokines, IL-12p70 or IL-23, and induced DC maturation, but did not promote pro-inflammatory cytokine production on their own.In vivo results showed that mice injected with CH-Al NPs generated a local inflammatory response comparable to that elicited by the vaccine adjuvant alum. Importantly, after subcutaneous immunization with CH-Al NPs combined with the hepatitis B surface antigen (HBsAg), mice developed antigen-specific IgG titers in serum, nasal and vaginal washes.Overall, our results established CH-Al NPs as a potential adjuvant to enhance both innate and adaptive immune responses.

Beyond Passive Immunity: Is There Priming of the Fetal Immune System Following Vaccination in Pregnancy and What Are the Potential Clinical Implications?

Infection is responsible for over half a million neonatal deaths worldwide every year, and vaccination in pregnancy is becoming increasingly recognized as an important strategy for the protection of young infants. Increasing evidence suggests that exposure to maternal infection in utero may “prime” the developing immune system, even in the absence of infant infection. It is also possible that in utero priming may occur following maternal vaccination, with antigen-specific cellular immune responses detectable in utero and at birth. However, this remains a topic of some controversy. This review focuses on the evidence for in utero priming and the clinical implications for vaccination in pregnancy, considering whether in utero priming following vaccination could provide protection independent of antibody-mediated passive immunity, the possible effects of vaccination on subsequent infant vaccinations, their potential “non-specific” effects, and how the design and timing of vaccination might affect prenatal priming. Looking forward, we describe other possible options for quantifying antigen-specific cellular responses, including MHC tetramers, novel proliferation and cytokine-based assays, and animal models. Together, these may help us address future research questions and establish more robust evidence of fetal immune system priming.

Administration of plasmacytoid dendritic cell-stimulative lactic acid bacteria enhances antigen-specific immune responses

Lactic acid bacteria (LAB) have been reported to have beneficial effects on protective immunity against viruses and pathogenic bacteria by activating innate immune cells such as dendritic cells (DC) or macrophages. However, little is known about whether LAB contributes to antigen-specific immune responses. Because plasmacytoid DC (pDC) links innate and acquired immunity, here we investigated whether the pDC-stimulative LAB, Lactococcus lactis strain Plasma (LC-Plasma), influences antigen-specific immune responses. In in vitro co-culture experiments, LC-Plasma enhanced the expression of MHC class I and II, and CD80 and CD86 on both pDC and conventional DC, and this enhancement was abolished by treatment with a Toll-like receptor 9 antagonist. A subsequent in vitro study showed that LC-Plasma increased antigen-specific T cell responses via DC activation. In mice, oral administration of LC-Plasma in combination with intraperitoneal antigen administration enhanced the percentage of antigen-specific CD8+ T cells and the amount of antigen-specific IgG. Furthermore, continuous intake of LC-Plasma increased T helper 1 responses, which contribute to antigen-specific cellular and humoral immune responses. Taken together, these results reveal that the oral intake of pDC-stimulative LAB enhances antigen-specific immune responses.