Nonredundant roles of basophils in immunity.

Basophils are the rarest granulocytes and represent less than 1% of peripheral blood leukocytes. They are evolutionarily conserved in many animal species, but their functional significance remained an enigma long after their discovery by Paul Ehrlich in 1879. Studies of basophils were hindered by their rarity, by difficulties in identifying them, and by the paucity of useful analytical tools. Because basophils display several characteristics shared by tissue-resident mast cells, they were often considered minor and possibly redundant relatives of mast cells or even blood-circulating precursors of mast cells. However, newly developed tools for their functional analysis, including basophil-depleting antibodies and genetically engineered mice deficient only in basophils, have fueled basophil research and defined previously unrecognized functions of basophils. We now appreciate that basophils play nonredundant roles in acquired immunity regulation, protective immunity to pathogens, and immunological disorders such as allergy and autoimmunity.

Immunization with Components of the Viral Fusion Apparatus Elicits Antibodies That Neutralize Epstein-Barr Virus in B Cells and Epithelial Cells.

Epstein-Barr virus (EBV) causes infectious mononucleosis and is associated with epithelial-cell cancers and B cell lymphomas. An effective EBV vaccine is not available. We found that antibodies to the EBV glycoprotein gH/gL complex were the principal components in human plasma that neutralized infection of epithelial cells and that antibodies to gH/gL and gp42 contributed to B cell neutralization. Immunization of mice and nonhuman primates with nanoparticle vaccines that displayed components of the viral-fusion machinery EBV gH/gL or gH/gL/gp42 elicited antibodies that potently neutralized both epithelial-cell and B cell infection. Immune serum from nonhuman primates inhibited EBV-glycoprotein-mediated fusion of epithelial cells and B cells and targeted an epitope critical for virus-cell fusion. Therefore, unlike the leading EBV gp350 vaccine candidate, which only protects B cells from infection, these EBV nanoparticle vaccines elicit antibodies that inhibit the virus-fusion apparatus and provide cell-type-independent protection from virus infection.

Vaccination with Intradermal Bacillus Calmette-Guérin Provides Robust Protection against Extrapulmonary Tuberculosis but Not Pulmonary Infection in Cynomolgus Macaques.

Recently, the efficacy of Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccination is being reassessed in accordance with the achievements of clinical tuberculosis (TB) vaccine research. However, the mechanisms ultimately determining the success or failure of BCG vaccination to prevent pulmonary TB remain poorly understood. In this study, we analyzed the protective effects of intradermal BCG vaccination by using specific pathogen-free cynomolgus macaques of Asian origin that were intradermally vaccinated with BCG (Tokyo strain) followed by Mycobacterium tuberculosis (Erdman strain) infection. Intradermal BCG administration generated TB Ag-specific multifunctional CD4 T cell responses in peripheral blood and bronchoalveolar lavage and almost completely protected against the development of TB pathogenesis with aggravation of clinical parameters and high levels of bacterial burdens in extrapulmonary organs. However, interestingly, there were no differences in bacterial quantitation and pathology of extensive granulomas in the lungs between BCG-vaccinated monkeys and control animals. These results indicated that the changes in clinical parameters, immunological responses, and quantitative gross pathology that are used routinely to determine the efficacy of TB vaccines in nonhuman primate models might not correlate with the bacterial burden and histopathological score in the lung as measured in this study.

A New Mouse Model of Chronic Myocarditis Induced by Recombinant Bacille Calmette-Guèrin Expressing a T-Cell Epitope of Cardiac Myosin Heavy Chain-α.

Dilated cardiomyopathy (DCM) is a potentially lethal disorder characterized by progressive impairment of cardiac function. Chronic myocarditis has long been hypothesized to be one of the causes of DCM. However, owing to the lack of suitable animal models of chronic myocarditis, its pathophysiology remains unclear. Here, we report a novel mouse model of chronic myocarditis induced by recombinant bacille Calmette-Guérin (rBCG) expressing a CD4+ T-cell epitope of cardiac myosin heavy chain-α (rBCG-MyHCα). Mice immunized with rBCG-MyHCα developed chronic myocarditis, and echocardiography revealed dilation and impaired contraction of ventricles, similar to those observed in human DCM. In the heart, CD62L-CD4+ T cells were increased and produced significant amounts of IFN-γ and IL-17 in response to cardiac myosin. Adoptive transfer of CD62L-CD4+ T cells induced myocarditis in the recipient mice, which indicated that CD62L-CD4+ T cells were the effector cells in this model. rBCG-MyHCα-infected dendritic cells produced proinflammatory cytokines and induced MyHCα-specific T-cell proliferation and Th1 and Th17 polarization. This novel chronic myocarditis mouse model may allow the identification of the central pathophysiological and immunological processes involved in the progression to DCM.

Immunological association of inducible bronchus-associated lymphoid tissue organogenesis in Ag85B-rHPIV2 vaccine-induced anti-tuberculosis mucosal immune responses in mice.

We previously reported that Ag85B-expressing human parainfluenza type 2 virus (Ag85B-rHPIV2) was effective as a nasal vaccine against tuberculosis in mice; however, the mechanism by which it induces an immune response remains to be investigated. In the present study, we found that organogenesis of inducible bronchus-associated lymphoid tissue (iBALT) played a role in the induction of antigen-specific T cells and IgA antibody responses in the lung of mice intra-nasally administered Ag85B-rHPIV2. We found that expression of Ag85B was dispensable for the development of iBALT, suggesting that HPIV2 acted as an iBALT-inducing vector. When iBALT organogenesis was disrupted in Ag85B-rHPIV2-immunized mice, either by neutralization of the lymphotoxin pathway or depletion of CD11b+ cells, Ag85B-specific immune responses (i.e. IFN γ-producing T cells and IgA antibody) were diminished in the lung. Furthermore, we found that immunization with Ag85B-rHPIV2 induced neutrophil and eosinophil infiltration temporally after the immunization in the lung. Thus, our results show that iBALT organogenesis contributes to the induction of antigen-specific immune responses by Ag85B-rHPIV2 and that Ag85B-rHPIV2 provokes its immune responses without inducing long-lasting inflammation.

Basophils play a pivotal role in immunoglobulin-G-mediated but not immunoglobulin-E-mediated systemic anaphylaxis.

Anaphylaxis is an acute, severe, and potentially fatal systemic allergic reaction. Immunoglobulin E (IgE), mast cells, and histamine have long been associated with anaphylaxis, but an alternative pathway mediated by IgG has been suggested to be more important in the elicitation of anaphylaxis. Here, we showed that basophils, the least common blood cells, were dispensable for IgE-mediated anaphylaxis but played a critical role in IgG-mediated, passive and active systemic anaphylaxis in mice. In vivo depletion of basophils but not macrophages, neutrophils, or NK cells ameliorated IgG-mediated passive anaphylaxis and rescued mice from death in active anaphylaxis. Upon capture of IgG-allergen complexes, basophils released platelet-activating factor (PAF), leading to increased vascular permeability. These results highlight a pivotal role for basophils in vivo and contrast two major, distinct pathways leading to allergen-induced systemic anaphylaxis: one mediated by basophils, IgG, and PAF and the other "classical" pathway mediated by mast cells, IgE, and histamine.

Simian immunodeficiency virus SIVmac239 infection and simian human immunodeficiency virus SHIV89.6P infection result in progression to AIDS in cynomolgus macaques of Asian origin.

Simian immunodeficiency virus (SIV) infection models in cynomolgus macaques are important for analysis of the pathogenesis of immunodeficiency virus and for studies on the efficacy of new vaccine candidates. However, very little is known about the pathogenesis of SIV or simian human immunodeficiency virus (SHIV) in cynomolgus macaques from different Asian countries. In the present study, we analysed the infectivity and pathogenicity of CCR5-tropic SIVmac and those of dual-tropic SHIV89.6P inoculated into cynomolgus macaques in Indonesian, Malaysian or Philippine origin. The plasma viral loads in macaques infected with either SIVmac239 or SHIV89.6P were maintained at high levels. CD4+ T cell levels in macaques infected with SIVmac239 gradually decreased. All of the macaques infected with SHIV89.6P showed greatly reduced CD4+ T-cell numbers within 6 weeks of infection. Eight of the 11 macaques infected with SIVmac239 were killed due to AIDS symptoms after 2-4.5 years, while four of the five macaques infected with SHIV89.6P were killed due to AIDS symptoms after 1-3.5 years. We also analysed cynomolgus macaques infected intrarectally with repeated low, medium or high doses of SIVmac239, SIVmac251 or SHIV89.6P. Infection was confirmed by quantitative RT-PCR at more than 5000, 300 and 500 TCID50 for SIVmac239, SIVmac251 and SHIV89.6P, respectively. The present study indicates that cynomolgus macaques of Asian origin are highly susceptible to SIVmac and SHIV infection by both intravenous and mucosal routes. These models will be useful for studies on virus pathogenesis, vaccination and therapeutics against human immunodeficiency virus/AIDS.

Suppressor of cytokine signaling 1 DNA administration inhibits inflammatory and pathogenic responses in autoimmune myocarditis.

Myocarditis and subsequent dilated cardiomyopathy are major causes of heart failure in young adults. Myocarditis in humans is highly heterogeneous in etiology. Recent studies have indicated that a subgroup of myocarditis patients may benefit from immune-targeted therapies, because autoimmunity plays an important role in myocarditis as well as contributing to the progression to cardiomyopathy and heart failure. Suppressor of cytokine signaling (SOCS) 1 plays a key role in the negative regulation of both TLR- and cytokine receptor-mediated signaling, which is involved in innate immunity and subsequent adaptive immunity. In this study, we investigated the therapeutic effect of SOCS1 DNA administration on experimental autoimmune myocarditis (EAM) in mice. EAM was induced by s.c. immunization with cardiac-specific peptides derived from α myosin H chain in BALB/c mice. In contrast to control myocarditis mice, SOCS1 DNA-injected mice were protected from development of EAM and heart failure. SOCS1 DNA administration was effective for reducing the activation of autoreactive CD4(+) T cells by inhibition of the function of Ag-presenting dendritic cells. Our findings suggest that SOCS1 DNA administration has considerable therapeutic potential in individuals with autoimmune myocarditis and dilated cardiomyopathy.

Pitavastatin regulates helper T-cell differentiation and ameliorates autoimmune myocarditis in mice.

PURPOSE: Experimental autoimmune myocarditis (EAM) is a mouse model of inflammatory cardiomyopathy, and the involvement of T helper (Th) 1 and Th17 cytokines has been demonstrated. Accumulated evidence has shown that statins have anti-inflammatory and immunomodulatory effects; however, the mechanism has not been fully elucidated. This study was designed to test the hypothesis that pitavastatin affects T cell-mediated autoimmunity through inhibiting Th1 and Th17 responses and reduces the severity of EAM in mice. METHODS: The EAM model was established in BALB/c mice by immunization with murine α-myosin heavy chain. Mice were fed pitavastatin (5 mg/kg) or vehicle once daily for 3 weeks from day 0 to day 21 after immunization. RESULTS: Pitavastatin reduced the pathophysiological severity of the myocarditis. Pitavastatin treatment inhibited the phosphorylation of signal transducer and activator of transcription (STAT)3 and STAT4, which have key roles in the Th1 and Th17 lineage commitment, respectively, in the heart, and suppressed production of Th1 cytokine interferon-γ and Th17 cytokine interleukin-17 from autoreactive CD4(+) T cells. In in vitro T-cell differentiation experiments, pitavastatin-treated T cells failed to differentiate into Th1 and Th17 cells through inhibiting the transcription of T-box expressed in T-cells (T-bet) and RAR-related orphan receptor γt (RORγT) which have critical roles in the development of Th1 and Th17 cells, respectively, and this failure was rescued by adding mevalonate. CONCLUSIONS: Pitavastatin inhibits Th1 and Th17 responses and ameliorates EAM. These results suggest that statins may be a promising novel therapeutic strategy for the clinical treatment of myocarditis and inflammatory cardiomyopathy.

Catheter-associated Mycobacterium intracellulare biofilm infection in C3HeB/FeJ mice.

Non-tuberculosis mycobacterial (NTM) diseases are steadily increasing in prevalence and mortality worldwide. Mycobacterium avium and M. intracellulare, the two major pathogens of NTM diseases, are resistant to antibiotics, and chlorine, necessitating their capacity to survive in natural environments (e.g. soil and rivers) and disinfected municipal water. They can also form biofilms on artificial surfaces to provide a protective barrier and habitat for bacilli, which can cause refractory systemic disseminated NTM disease. Therefore, preventing biofilm formation by these pathogens is crucial; however, not many in vivo experimental systems and studies on NTM biofilm infection are available. This study develops a mouse model of catheter-associated systemic disseminated disease caused by M. intracellulare that reproduces the pathophysiology of catheter-associated infections observed in patients undergoing peritoneal dialysis. In addition, the bioluminescence system enabled noninvasive visualization of the amount and distribution of bacilli in vivo and conveniently examine the efficacy of antimicrobials. Furthermore, the cellulose-based biofilms, which were extensively formed in the tissue surrounding the catheter insertion site, reduced drug therapy effectiveness. Overall, this study provides insights into the cause of the drug resistance of NTM and may guide the development of new therapies for NTM diseases.

Long-term protective immunity induced by an adjuvant-containing live-attenuated AIDS virus.

The use of an adjuvant in vaccination is thought to be effective for enhancing immune responses to various pathogens. We genetically constructed a live attenuated simian human immunodeficiency virus (SHIV) to express the adjuvant molecule Ag85B (SHIV-Ag85B). SHIV-Ag85B could not be detected 4 weeks after injection in cynomolgus macaques, and strong SHIV-specific T cell responses were induced in these macaques. When the macaques in which SHIV-Ag85B had become undetectable were challenged with pathogenic SHIV89.6P at 37 weeks after SHIV-Ag85B had become undetectable, SHIV89.6P was not detected after the challenge. Eradication of SHIV89.6P was confirmed by adoptive transfer experiments and CD8-depletion studies. The SHIV-Ag85B-inoculated macaques showed enhancement of Gag-specific monofunctional and polyfunctional CD8+ T cells in the acute phase of the pathogenic SHIV challenge. The results suggest that SHIV-Ag85B elicited strong sterile immune responses against pathogenic SHIV and that it may lead to the development of a vaccine for AIDS virus infection.

IgG-mediated systemic anaphylaxis to protein antigen can be induced even under conditions of limited amounts of antibody and antigen.

Systemic anaphylaxis is an acute, severe, and potentially fatal allergic reaction. Two classes of antibodies, IgE and IgG, contribute to the development of anaphylaxis in mice, through different mechanisms with distinct usage of effector cells and chemical mediators. Larger quantities of antibody and antigen are reportedly required to induce IgG-mediated anaphylaxis than IgE-mediated one, suggesting that the former may not happen as frequently as the latter in real life. To readdress this issue, we established in the present study a novel mouse model of passive IgG-mediated systemic anaphylaxis to a native protein antigen, ovalbumin (OVA), rather than artificially haptenated protein antigens used in previous studies. Passive sensitization of mice with a cocktail of but not individual IgG1 mAbs specific to distinct OVA epitopes elicited systemic anaphylaxis in response to OVA challenge. Importantly, much smaller doses of antibody and antigen than previously reported were sufficient for the induction of IgG-mediated systemic anaphylaxis. Moreover, a relatively small dose of antigen could induce severe anaphylaxis through both IgE- and IgG-mediated mechanisms when mice had been passively sensitized with antigen-specific IgE and IgG. These results strongly suggest that IgG-mediated systemic anaphylaxis is not rare among antibody-mediated systemic anaphylaxis, in contrast to previous thought, and significantly contributes to active systemic anaphylaxis in real life, at least in mice.

Leucine-rich alpha 2 glycoprotein is a new marker for active disease of tuberculosis.

Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is a global health problem. At present, prior exposure to Mtb can be determined by blood-based interferon-gamma release assay (IGRA), but active TB is not always detectable by blood tests such as CRP and ESR. This study was undertaken to investigate whether leucine-rich alpha-2 glycoprotein (LRG), a new inflammatory biomarker, could be used to assess active disease of TB. Cynomolgus macaques pretreated with or without Bacille Calmette-Guerin (BCG) vaccination were inoculated with Mtb to induce active TB. Blood was collected over time from these animals and levels of LRG as well as CRP and ESR were quantified. In the macaques without BCG vaccination, Mtb inoculation caused extensive TB and significantly increased plasma CRP and LRG levels, but not ESR. In the macaques with BCG vaccination, whereas Mtb challenge caused pulmonary TB, only LRG levels were significantly elevated. By immunohistochemical analysis of the lung, LRG was visualized in epithelioid cells and giant cells of the granulation tissue. In humans, serum LRG levels in TB patients were significantly higher than those in healthy controls and declined one month after anti-tubercular therapy. These findings suggest that LRG is a promising biomarker when performed following IGRA for the detection of active TB.

[The roles for basophils in allergy].

Basophils are the least common granulocytes, and account for less than 1% of peripheral blood leukocytes. Because of this minority status and their phenotypic similarity to mast cells, basophils have often been neglected in immunological studies or considered to have minor, redundant roles in immune responses in vivo. We have recently demonstrated that basophils play critical roles in IgG-mediated systemic anaphylaxis and IgE-mediated chronic allergic inflammation. Basophils also promote the Th2 differentiation and enhance the humoral memory response. Thus, basophils are a key player in both immune regulation and allergic responses. Basophils and their products seem to be promising therapeutic targets for allergic disorders.

Allergy Vaccines Using a Mycobacterium-Secreted Antigen, Ag85B, and an IL-4 Antagonist.

In recent decades, the prevalence of allergic diseases, including bronchial asthma, airway hypersensitivity, hay fever, and atopic dermatitis, has been increasing in the industrialized world, and effective treatments probably require manipulating the inflammatory response to pathogenic allergens. T helper (Th) 2 cells are thought to play a crucial role in the initiation, progression, and persistence of allergic responses in association with production of interleukin (IL)-4, IL-5, and IL-13. Therefore, a strategy of a shift from Th2- to Th1-type immune response may be valuable in the prophylaxis and management of allergic diseases. It is also necessary to develop prophylactic and therapeutic treatment that induces homeostatic functions in the multifaceted allergic environment, because various factors including innate and adaptive immunity, mucosal immune response, and functional and structural maintenance of local tissue might be involved in the pathogenesis of allergic disorders. We review herein recent findings related to the curative effect for mouse models of asthma and atopic dermatitis using DNA-, virus-, and protein-based vaccines of a Mycobacterium secretion antigen, Ag85B, and a plasmid encoding cDNA of antagonistic IL-4 mutant.

Asymmetric cooperativity in tandem hybridization of enantiomeric metal complex-tethered short fluorescent DNA probes.

The complex [Ru(phen)(2)(dppz)](2+)(phen = 1,10-phenanthroline, dppz = dipyrido[3,2-aratio2',3'-c]phenazine) was attached to the 5' end of a short oligonucleotide to form conjugates, the Delta-isomer of which showed a high cooperativity during the recognition of the repetitive sequence, while the Lambda-isomer did not.

Effects of mycobacteria major secretion protein, Ag85B, on allergic inflammation in the lung.

Many epidemiological studies have suggested that the recent increase in prevalence and severity of allergic diseases such as asthma is inversely correlated with Mycobacterium bovis bacillus Calmette Guerin (BCG) vaccination. However, the underlying mechanisms by which mycobacterial components suppress allergic diseases are not yet fully understood. Here we showed the inhibitory mechanisms for development of allergic airway inflammation by using highly purified recombinant Ag85B (rAg85B), which is one of the major protein antigens secreted from M. tuberculosis. Ag85B is thought to be a single immunogenic protein that can elicit a strong Th1-type immune response in hosts infected with mycobacteria, including individuals vaccinated with BCG. Administration of rAg85B showed a strong inhibitory effect on the development of allergic airway inflammation with induction of Th1-response and IL-17and IL-22 production. Both cytokines induced by rAg85B were involved in the induction of Th17-related cytokine-production innate immune cells in the lung. Administration of neutralizing antibodies to IL-17 or IL-22 in rAg85B-treated mice revealed that IL-17 induced the infiltration of neutrophils in BAL fluid and that allergen-induced bronchial eosinophilia was inhibited by IL-22. Furthermore, enhancement of the expression of genes associated with tissue homeostasis and wound healing was observed in bronchial tissues after rAg85B administration in a Th17-related cytokine dependent manner. The results of this study provide evidence for the potential usefulness of rAg85B as a novel approach for anti-allergic effect and tissue repair other than the role as a conventional TB vaccine.

Recombinant Ag85B vaccine by taking advantage of characteristics of human parainfluenza type 2 virus vector showed Mycobacteria-specific immune responses by intranasal immunization.

Viral vectors are promising vaccine candidates for eliciting suitable Ag-specific immune response. Since Mycobacterium tuberculosis (Mtb) normally enters hosts via the mucosal surface of the lung, the best defense against Mtb is mucosal vaccines that are capable of inducing both systemic and mucosal immunity. Although Mycobacterium bovis bacille Calmette-Guérin is the only licensed tuberculosis (TB) vaccine, its efficacy against adult pulmonary forms of TB is variable. In this study, we assessed the effectiveness of a novel mucosal TB vaccine using recombinant human parainfluenza type 2 virus (rhPIV2) as a vaccine vector in BALB/c mice. Replication-incompetent rhPIV2 (M gene-eliminated) expressing Ag85B (rhPIV2-Ag85B) was constructed by reverse genetics technology. Intranasal administration of rhPIV2-Ag85B induced Mtb-specific immune responses, and the vaccinated mice showed a substantial reduction in the number of CFU of Mtb in lungs and spleens. Unlike other viral vaccine vectors, the immune responses against Ag85B induced by rhPIV2-Ag85B immunization had an advantage over that against the viral vector. In addition, it was revealed that rhPIV2-Ag85B in itself has an adjuvant activity through the retinoic acid-inducible gene I receptor. These findings provide further evidence for the possibility of rhPIV2-Ag85B as a novel TB vaccine.

Single systemic administration of Ag85B of mycobacteria DNA inhibits allergic airway inflammation in a mouse model of asthma.

The immune responses of T-helper (Th) and T-regulatory cells are thought to play a crucial role in the pathogenesis of allergic airway inflammation observed in asthma. The correction of immune response by these cells should be considered in the prevention and treatment of asthma. Native antigen 85B (Ag85B) of mycobacteria, which cross-reacts among mycobacteria species, may play an important biological role in host-pathogen interaction since it elicits various immune responses by activation of Th cells. The current study investigated the antiallergic inflammatory effects of DNA administration of Ag85B from Mycobacterium kansasii in a mouse model of asthma. Immunization of BALB/c mice with alum-adsorbed ovalbumin followed by aspiration with aerosolized ovalbumin resulted in the development of allergic airway inflammation. Administration of Ag85B DNA before the aerosolized ovalbumin challenge protected the mice from subsequent induction of allergic airway inflammation. Serum and bronchoalveolar lavage immunoglobulin E levels, extent of eosinophil infiltration, and levels of Th2-type cytokines in Ag85B DNA-administered mice were significantly lower than those in control plasmid-immunized mice, and levels of Th1-and T-regulatory-type cytokines were enhanced by Ag85B administration. The results of this study provide evidence for the potential utility of Ag85B DNA inoculation as a novel approach for the treatment of asthma.