PLGA-encapsulation of the Pseudomonas aeruginosa PopB vaccine antigen improves Th17 responses and confers protection against experimental acute pneumonia

The Pseudomonas aeruginosa type III secretion system protein PopB and its chaperon protein PcrH, when co-administered with the adjuvant curdlan, elicit Th17 responses after intranasal immunization of mice. These PopB/PcrH-curdlan vaccines protect mice against acute lethal pneumonia in an IL-17-dependent fashion involving CD4 helper T cells secreting IL-17 (Th17 cells). In this study, we tested whether encapsulation of PopB/PcrH in poly-lactic-co-glycolic acid (PLGA) nanoparticles could elicit Th17 responses to PopB. Recombinant PopB/PcrH or PcrH alone was encapsulated into PLGA nanoparticles. Mice (FVB/N) were intranasally immunized with the PLGA-PopB/PcrH nanoparticles, PLGA-PcrH nanoparticles, PLGA alone, or PopB/PcrH alone. The protective efficacy was assessed in an acute lung infection model with a lethal dose of an ExoU-producing version of P. aeruginosa strain PAO1. Th17 responses were assayed by intracellular flow cytometry and by ELISA for IL-17 in supernatants of splenocytes co-cultured with purified PopB/PcrH. PLGA-PopB/PcrH-immunized mice showed 3–4-fold higher Th17 responses both in the lung and in the spleen compared to mice immunized with empty PLGA or PopB/PcrH alone. After challenge with P. aeruginosa, PLGA-PopB/PcrH-immunized mice showed significantly lower bacterial counts in the lungs and improved survival. In conclusion, encapsulation of PopB/PcrH in PLGA nanoparticles can elicit Th17 responses to intranasal vaccination and protect mice against acute lethal P. aeruginosa pneumonia.     

Incorporation of immunostimulatory motifs in the transcribed region of a plasmid DNA vaccine enhances Th1 immune responses and therapeutic effect against Mycobacterium tuberculosis in mice

T-helper type 1 (Th1) immune response is involved in the development of protective immunity against Mycobacterium tuberculosis. Thus, an increase in Th1 and cellular immune responses should lead to enhanced anti-mycobacterial activity. In this study, we aimed to improve Th1 immune responses to a DNA vaccine by adding potentially immunostimulatory nucleotide sequences into the transcribed region downstream of the antigen. The Mycobacterium leprae gene for hsp65, codon-optimized for expression in mammalian cells, was inserted into pVAX1 with and without 3′-sequences containing CpG and dsRNA motifs. When the plasmid contained both motifs, transfected murine macrophage-like RAW264.7 cells showed markedly increased levels of mRNA for immune molecules of Th1 (IFN-α, IL-12) and Th17 (IL-17, IL-23 and IL-6) responses and for T cell co-stimulatory molecules (CD80 and CD86) but not for a Th2 response (IL-4 and IL-10). Immunized mice showed substantially increased serum anti-Hsp65 IgG2a antibody levels and IFN-γ production by spleen cells, confirming enhancement of the Th1 response in vivo. Furthermore, when non-vaccinated mice were infected with H37Rv by low-dose aerosol challenge, and then 4 weeks later were treated with plasmids by intramuscular injection, the mice that had been treated with plasmids containing immunostimulatory motifs showed an enhanced reduction in mycobacterial loads in lung and spleen. We conclude that DNA vaccines may be made more highly immunogenic and more effective for treatment by including transcribed stimulatory sequences.     

Induction of protective Th1 immune responses in mice by vaccination with recombinant Toxoplasma gondii nucleoside triphosphate hydrolase-II

The Toxoplasma gondii nucleoside triphosphate hydrolase (TgNTPase) has apyrase activity, degrading ATP to the di- and mono-phosphate forms and may be used by the parasite to salvage purines from the host cell for survival and replication. To study the immune-protective value of TgNTPase-II, BALB/c mice were immunized with a recombinant form of the antigen rTgNTPase-II combined with alum. All immunized mice produced specific anti-rTgNTPase-II immunoglobulins, with high IgG antibody titers and a mixed IgG1/IgG2a response, with predominance of IgG2a production. The cellular immune response was associated with the production of IFN-γ and IL-2 cytokines and the increase of the percentage of CD8+ T cells. Vaccinated mice displayed significant protection against acute infection with the virulent RH strain (P < 0.05 in survival rate) and also chronic infection with PRU cyst (62.9% and 57.6% reduction in brain parasite load for rTgNTPase-II + alum and rTgNTPase-II alone vaccinated groups) compared to the non-vaccinated control group. In conclusion, rTgNTPase-II elicits a strong specific Th1 immune response providing partial protection against both T. gondii acute and chronic infection.     

Th17/Th1 biased immunity to the pneumococcal proteins PcsB, StkP and PsaA in adults of different age

Streptococcus pneumoniae is a major human pathogen, causing high morbidity and mortality in children, and also in the elderly, who are particularly susceptible to S. pneumoniae infections due to the dysregulated function of the aged immune system. As the current generation of polysaccharide vaccines do not provide sufficient protection for elderly, new vaccination strategies are urgently needed.To learn whether pneumococcal proteins are able to induce adaptive immune responses in adults in different age groups, we determined serum IgG antibody titers and T cell immunity (IFN-γ, IL-17A and IL-5 production) to three pneumococcal antigens, PcsB, StkP and PsaA, that are components of an investigational protein-based pneumococcal vaccine, IC47. Therefore, sera and PBMCs of 108 healthy adults in three different age groups (young, middle-aged and elderly) were analyzed by ELISA and ELISpot, respectively.We found naturally acquired antibodies to all three proteins in all age groups against all three antigens. However, elderly individuals had significantly lower IgG levels to PcsB and PsaA compared to those of younger donors. There was no significant age-related difference in the overall rate of T cell immunity for the three pneumococcal proteins. We found that the Th17 response was dominant in all age groups and was frequently combined with a Th1 or Th2 response in young and middle-aged subjects. However, in elderly persons there was a lower percentage of PBMC samples producing more than one cytokine upon antigenic stimulation. The narrow cytokine secretion pattern was the most striking difference between elderly and younger adult age groups.Our results demonstrate that in the majority of adults there is a naturally acquired humoral and cellular immune response to the three pneumococcal proteins tested. The dominance of the Th17 response is especially interesting in the light of new insights regarding the role of Th17 cells in mucosal protection against this pathogen.     

A novel adjuvant G3 induces both Th1 and Th2 related immune responses in mice after immunization with a trivalent inactivated split-virion influenza vaccine

A preferred adjuvant should promote both Th1 and Th2 responses. However, most adjuvants in common use are biased towards a Th2-driven response. Therefore, the ability of a novel saponin-based adjuvant G3 to inducing balanced Th1 and Th2 responses in BALB/c mice immunized with a split trivalent seasonal influenza vaccine was evaluated in comparison to that of the adjuvant Al(OH)₃. Clear differences in the IgG profiles induced by G3, Al(OH)₃ or non-adjuvanted vaccine were recorded. Both adjuvants enhanced high and similar levels of the Th2 associated IgG1 subtype compared to mice given vaccine alone. Only G3 enhanced the IgG2a subclass reflecting a Th1 response, whereas Al(OH)₃ even abrogated the IgG2a production. Accordingly, G3 enhanced the production of IL-2 and IFN-γ and also of IL-2/IFN-γ double secreting cells, emphasizing the strong Th1 driving effect of G3. Only Al(OH)₃ increased splenocyte production of IL-17. Taken together, the results indicate a strong propensity for G3 to induce both Th1 and Th2 driven immune responses.     

Th17和Treg细胞的平衡状态与肺结核的关系

Th17和Treg细胞均来源于CD4+T细胞,在机体免疫应答中的作用基本相反,Th17促进免疫应答,而Treg细胞抑制免疫应答,正常情况下两者之间的平衡状态有利于保持机体免疫平衡.结核分枝杆菌感染可能打破两者之间的平衡从而导致疾病进展,而抗结核治疗可能恢复二者平衡关系.此文就Th17和Treg细胞的分化、调控和功能,以及两者在艾滋病及肺结核患者中的变化等进行综述.     

Recombinant NADP-dependent isocitrate dehydrogenase of Edwardsiella tarda induces both Th1 and Th2 type immune responses and evokes protective efficacy against edwardsiellosis

Edwardsiella tarda has become one of the most severe fish pathogens throughout the world. Thus, studies on the design and production of highly protective vaccines against this pathogen, as well as the mechanisms of vaccine-induced disease resistance are urgently needed. In this study, the NADP-dependent isocitrate dehydrogenase (IDH) of E. tarda was recombinantly expressed and flounder (Paralichthys olivaceus) anti-rIDH serum was prepared. Also, the outer membrane proteins (OMPs) of E. tarda were extracted and analyzed by western blotting. The results showed that flounder anti-rIDH serum could specifically recognize a 44 kDa protein of E. tarda OMPs, which was identified to be the native IDH of E. tarda by mass spectrometric. Consistently, immunogold electron microscopy showed that IDH could be detected on the membrane of E. tarda. Then, the vaccine potential of rIDH was tested in a flounder model, and the results showed that rIDH produced a relative percent survival (RPS) of 73.3%, which was significantly higher than that produced by formalin killed E. tarda cells. Immunological analysis showed that rIDH could induce the proliferation of rIDH-specific sIg+ lymphocytes, which resulted in the production of anti-E. tarda antibodies. Accordingly, serum bactericidal activity assay showed that the serum of rIDH vaccinated fish exhibited the highest bactericidal activity compared with other groups. qRT-PCR analysis showed that rIDH could enhance the expressions of IFN-γ, NKEF, IL-6, MHCIα, CD4-1 and CD8α. Moreover, the bacterial burden was also detected in vaccinated fish after challenge, which showed that the number of E. tarda cells in spleen of rIDH group was significantly lower than other groups. All these results suggested that rIDH is a promising vaccine candidate against E. tarda infection.     

Mucosal delivery switches the response to an adjuvanted tuberculosis vaccine from systemic TH1 to tissue-resident TH17 responses without impacting the protective efficacy

Pulmonary tuberculosis (TB) remains one of the leading causes of infectious disease death despite widespread usage of the BCG vaccine. A number of new TB vaccines have moved into clinical evaluation to replace or boost the BCG vaccine including ID93+GLA-SE, an adjuvanted subunit vaccine. The vast majority of new TB vaccines in trials are delivered parenterally even though intranasal delivery can augment lung-resident immunity and protective efficacy in small animal models. Parenteral immunization with the adjuvanted subunit vaccine ID93+GLA-SE elicits robust TH1 immunity and protection against aerosolized Mycobacterium tuberculosis in mice and guinea pigs. Here we describe the immunogenicity and efficacy of this vaccine when delivered intranasally. Intranasal delivery switches the CD4 T cell response from a TH1 to a TH17 dominated tissue-resident response with increased frequencies of ID93-specific cells in both the lung tissue and at the lung surface. Surprisingly these changes do not affect the protective efficacy of ID93+GLA-SE. Unlike intramuscular immunization, ID93+GLA does not require the squalene-based oil-in-water emulsion SE to elicit protective CD4 T cells when delivered intranasally. Finally we demonstrate that TNF and the IL-17 receptor are dispensable for the efficacy of the intranasal vaccine suggesting an alternative mechanism of protection.     

Epitope diversification driven by non-tumor epitope-specific Th1 and Th17 mediates potent antitumor reactivity

MHC class I-restricted peptide-based vaccination therapies have been conducted to treat cancer patients, because CD8(+) CTL can efficiently induce apoptosis of tumor cells in an MHC class I-restricted epitope-specific manner. Interestingly, clinical responders are known to demonstrate reactivity to epitopes other than those used for vaccination; however, the mechanism underlying how antitumor T cells with diverse specificity are induced is unclear. In this study, we demonstrated that dendritic cells (DCs) that engulfed apoptotic tumor cells in the presence of non-tumor MHC class II-restricted epitope peptides, OVA(323-339), efficiently presented tumor-associated antigens upon effector-dominant CD4(+) T cell balance against regulatory T cells (Treg) for the OVA(323-339) epitope. Th1 and Th17 induced tumor-associated antigens presentation of DC, while Th2 ameliorated tumor-antigen presentation for CD8(+) T cells. Blocking experiments with anti-IL-23p19 antibody and anti-IL-23 receptor indicated that an autocrine mechanism of IL-23 likely mediated the diverted tumor-associated antigens presentation of DC. Tumor-associated antigens presentation of DC induced by OVA(323-339) epitope-specific CD4(+) T cells resulted in facilitated antitumor immunity in both priming and effector phase in vivo. Notably, this immunotherapy did not require pretreatment to reduce Treg induced by tumor. This strategy may have clinical implications for designing effective antitumor immunotherapies.     

Modulation of Th1/Th2 immune responses to HIV-1 Tat by new pro-GSH molecules

We have previously demonstrated that in Ova-immunized mice the increase in intra-macrophage thiol pool induced by pro-GSH molecules modulates the Th1/Th2 balance in favour of a Th1-type immune response. We show now that the same molecules can support a Th1-type over Th2-type immunity against Tat, which is an early HIV-1 regulatory protein and a Th1 polarizing immunomodulator that is increasingly considered in new anti-HIV vaccination strategies. Our results indicate that Tat-immunized mice pre-treated with the C4 (n-butanoyl) derivative of reduced glutathione (GSH-C4) or a pro-drug of N-acetylcysteine (NAC) and beta-mercaptoethylamine (MEA) (I-152), have decreased levels of anti-Tat IgG1 as well as increased levels of anti-Tat IgG2a and IgG2b isotypes suggesting a Th1-type response. Moreover, Th1-(IFN-γ and IL-2) Ag-specific cellular responses were detected by ELISPOT assay in splenocytes of the same animals as well as an increase of IL-12 levels in the plasma. These findings suggest that the Th1 immune response to HIV-1 Tat could be further polarized by these molecules. These results together with those previously reported suggest that pro-GSH molecules could be used to modulate the immune response towards different antigens and may be further exploited for inducing specific Th1 immune responses against other HIV antigens as well as other intracellular pathogens in new Tat-based vaccination protocols.     

Th17细胞因子IL-17A与乙肝疫苗无/弱应答关联的研究

目的了解Th17细胞因子IL-17A水平与乙肝疫苗免疫无/弱应答发生的关联。方法在1 481名完成乙肝疫苗全程接种的年轻成人中筛选出无/弱应答者30人,根据无/弱应答者性别、年龄和BMI,分别选择抗-HBs抗体中滴度、高滴度正常应答者各30例与之匹配形成对照,检测、比较三组人群血清中IL-17A的浓度差异。并检测无/弱应答者,加强接种1剂次60μg乙肝疫苗后血清IL-17A变化情况。结果 IL-17A在无/弱应答组血清水平中位数为225.16pg/ml(QIR:176.91,287.13),中滴度组为237.37pg/ml(QIR:164.09,266.68),高滴度组为219.05pg/ml(QIR:194.62,261.82),三组间差异无统计学意义(x~2=0.072,P=0.965);无/弱应答组在加强一剂次后IL-17A浓度为241.64pg/ml(QIR:222.40,241.64),高于加强前水平,但差异无统计学意义(Z=-1.175,P=0.240)。结论本研究未能证明Th17细胞因子IL-17A与乙肝疫苗接种无/弱反应发生存在关联。     

Protective efficacy of Mycobacterium indicus pranii against tuberculosis and underlying local lung immune responses in guinea pig model

Tuberculosis kills two million people each year. As the current vaccine BCG fails to prevent adult cases of TB, an improved vaccine and/or vaccination strategy is urgently needed to combat TB. Previously we reported the higher protective efficacy of Mycobacterium indicus pranii (MIP), formerly known as Mycobacterium w (M.w) as compared to BCG in murine model of TB. In this study we further evaluated the protective efficacy of MIP in guinea pig model of TB. Modulation of post infection immune response was analyzed in the lungs of MIP immunized and control groups. We found reduced bacterial loads, improved pathology and organized granulomatous response at different post infection time points in the MIP-immunized group as compared to the BCG-immunized group. Combined results suggest that MIP-immunization results in heightened protective Th1 response as compared to BCG group, early after infection with M.tb and a balanced Th1 versus immunosuppressive response at late chronic stage of infection. The study demonstrates the higher antigen presenting cells function both inside the granuloma as well as in the single cell suspension of the lung in the MIP-immunized group. We further demonstrate that live MIP is safe to use in vivo as we observed quick clearance of MIP from the body and no untoward reaction was found. Aerosol route of immunization provided higher protection. Further this study provides evidence that MIP-immunization gives significantly better long term protection as compared to BCG against TB.     

Sublingual immunization with a subunit influenza vaccine elicits comparable systemic immune response as intramuscular immunization,but also induces local IgA and TH17 responses

Influenza is a vaccine-preventable disease that remains a major health problem world-wide. Needle and syringe are still the primary delivery devices, and injection of liquid vaccine into the muscle is still the primary route of immunization. Vaccines could be more convenient and effective if they were delivered by the mucosal route. Elicitation of systemic and mucosal innate and adaptive immune responses, such as pathogen neutralizing antibodies (including mucosal IgA at the site of pathogen entry) and CD4⁺ T-helper cells (especially the Th17 subset), have a critical role in vaccine-mediated protection. In the current study, a sublingual subunit influenza vaccine formulated with or without mucosal adjuvant was evaluated for systemic and mucosal immunogenicity and compared to intranasal and intramuscular vaccination. Sublingual administration of adjuvanted influenza vaccine elicited comparable antibody titers to those elicited by intramuscular immunization with conventional influenza vaccine. Furthermore, influenza-specific Th17 cells or neutralizing mucosal IgA were detected exclusively after mucosal immunization.     

Ginsenoside Rd elicits Th1 and Th2 immune responses to ovalbumin in mice

Ginsenoside Rd (Rd), a saponin isolated from the roots of panax notoginseng, was evaluated for inducing Th1 or Th2 immune responses in mice against ovalbumin (OVA). ICR mice were immunized subcutaneously with OVA 100 microg alone or with OVA 100 microg dissolved in saline containing alum (200 microg), or Rd (10, 25 or 50 microg) on days 1 and 15. Two weeks later (day 28), concanavalin A (Con A)-, lipopolysaccharide (LPS)- and OVA-stimulated splenocyte proliferation was determined using MTT assay, and OVA-specific antibody titers and levels of cytokines in serum were measured by ELISA and microparticle-based flow cytometric immunoassay, as well as peripheral blood T-lymphocyte subsets analyzed using flow cytometer. Rd significantly enhanced the Con A-, LPS-, and OVA-induced splenocyte proliferation in the OVA-immunized mice. OVA-specific IgG, IgG1, and IgG2b antibody titers in serum were significantly enhanced by Rd compared with OVA control group. Meanwhile, Rd also significantly promoted the production of the Th1 and Th2 cytokines in OVA-immunized mice. Further, the effects of Rd on expression of cytokine mRNA in Con A-stimulated mice splenocytes were evaluated by RT-PCR analysis. Rd significantly enhanced the interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-4, and IL-10 mRNA expression in mice splenocyte induced by Con A. These results suggested that Rd had immunological adjuvant activity, and elicited a Th1 and Th2 immune response by regulating production and gene expression of Th1 cytokines and Th2 cytokines.     

Comparison of immune responses and protective efficacy of intranasal prime-boost immunization regimens using adenovirus-based and CpG/HH2 adjuvanted-subunit vaccines against genital Chlamydia muridarum infection

An efficacious Chlamydia vaccine is urgently needed to control Chlamydia infections. Heterologous prime-boost vaccination regimens are emerging as a promising strategy for preventing intracellular viral and bacterial infections. However, it remains to be determined if this regimen would be a feasible and effective approach for Chlamydia infection. In this study, we examined the immune response and the protective efficacy induced by various vaccination regimens using a recombinant adenovirus vector expressing the Chlamydia antigen CPAF (AdCPAF) and recombinant CPAF (rCPAF) subunit vaccines formulated with CpG oligodeoxynucleotides and/or a synthetic immunomodulatory peptide HH2 as adjuvants. A single dose of AdCPAF stimulated potent antibody production but weak cellular immune responses in mice. A booster rCPAF vaccine formulated with both CpG and HH2, but not CpG alone or HH2 alone, showed robust adjuvant effects on induction of Th1-biased cellular immune responses in mice primed with AdCPAF. In contrast, a homologous regimen using rCPAF/CpG/HH2 subunit vaccine for both priming and boosting induced a weak antibody response, but potent cellular immunity with a mixed Th1/Th17 profile. Despite the disparities observed in humoral and cellular immune responses, both the heterologous and homologous prime-boost regimens conferred significant immune protection against genital Chlamydia muridarum challenge in C3H/HeN and BALB/c mice.     

Minimal immune response to booster vaccination against Yellow Fever associated with pre-existing antibodies

Ever since its development in the 1930′s, the live-attenuated Yellow Fever virus vaccine YF-17D has been highly effective. Despite the increasing knowledge on the immune biology of the YF-17D vaccine, most studies have focused only on a few types of immune cells and pathways or mainly on the primary adaptive immune response to YF-17D vaccination. Here, we examined humoral, innate and adaptive cellular responses in a longitudinal YF-17D vaccination study in Switzerland, comparing both primary and booster vaccination. In contrast to the strong innate and adaptive immune response to the primary vaccination, we find that the response to boosting is much reduced. Our data show an inverse association of neutralizing antibodies at baseline with vaccine virus replication and with the immune response upon boosting. These results suggest that booster vaccination may not have major immunological effects when neutralizing antibodies are present. Importantly, our study population was healthy adults in a non-endemic country and ultimately booster vaccine requirement must be assessed based on additional epidemiological and public health considerations in endemic areas.