Prior Bordetella pertussis infection modulates allergen priming and the severity of airway pathology in a murine model of allergic asthma

Live attenuated pertussis vaccine for prevention and treatment of allergic airway inflammation in mice

Live attenuated vaccines often have beneficial non-specific effects, protecting against heterologous infectious and non-infectious diseases. We have developed a live attenuated pertussis vaccine, named BPZE1, currently in advanced clinical development. Here, we examined the prophylactic and therapeutic potential of its pertactin-deficient derivative BPZE1P in a mouse model of house dust mite (HDM)-induced allergic airway inflammation (AAI). BPZE1P was given nasally either before or after sensitization with HDM, followed by HDM challenge, or between two challenge episodes. Vaccination prior to sensitization reduced resistance in the airways, the numbers of infiltrating eosinophils and the concentrations of proinflammatory cytokines, such as IL-1α, IL-1β and IL-33, in the lungs but had no effect on Th2 cytokine levels. BPZE1P also protected when delivered after sensitization or between two challenge episodes. However, in this case the levels of Th2 cytokines in the lung were decreased without significant effects on IL-1α, IL-1β and IL-33 production. The vaccine restored lung function and decreased eosinophil influx in the lungs of HDM-treated mice. BPZE1P has a better take than BPZE1 in hosts vaccinated with acellular pertussis vaccines. Therefore, it has interesting potential as a preventive and therapeutic agent against AAI, even in acellular pertussis-vaccinated populations.

Disrupting Bordetella Immunosuppression Reveals a Role for Eosinophils in Coordinating the Adaptive Immune Response in the Respiratory Tract

Recent findings revealed pivotal roles for eosinophils in protection against parasitic and viral infections, as well as modulation of adaptive immune responses in the gastric mucosa. However, the known effects of eosinophils within the respiratory tract remain predominantly pathological, associated with allergy and asthma. Simulating natural respiratory infections in mice, we examined how efficient and well-adapted pathogens can block eosinophil functions that contribute to the immune response. Bordetella bronchiseptica, a natural pathogen of the mouse, uses the sigma factor btrS to regulate expression of mechanisms that interfere with eosinophil recruitment and function. When btrS is disrupted, immunomodulators are dysregulated, and eosinophils are recruited to the lungs, suggesting they may contribute to much more efficient generation of adaptive immunity induced by this mutant. Eosinophil-deficient mice failed to produce pro-inflammatory cytokines, to recruit lymphocytes, to organize lymphoid aggregates that resemble Bronchus Associated Lymphoid Tissue (BALT), to generate an effective antibody response, and to clear bacterial infection from the respiratory tract. Importantly, the failure of eosinophil-deficient mice to produce these lymphoid aggregates indicates that eosinophils can mediate the generation of an effective lymphoid response in the lungs. These data demonstrate that efficient respiratory pathogens can block eosinophil recruitment, to inhibit the generation of robust adaptive immune responses. They also suggest that some post-infection sequelae involving eosinophils, such as allergy and asthma, might be a consequence of bacterial mechanisms that manipulate their accumulation and/or function within the respiratory tract.

Diphteria-tetanus-pertussis vaccine reduces specific IgE, inflammation and remodelling in an animal model of mite-induced respiratory allergy

BACKGROUND

Adjuvants, such as bacterial lipopolysaccharides, have been studied to improve the efficacy of allergen-specific immunotherapy. The Bordetella pertussis (Pw) vaccine has been shown to have a protective role in ovalbumin-induced asthma models. However, its role in allergy to mites is unknown. We evaluated the effects of the diphtheria-tetanus-pertussis (DTPw) vaccine on a murine model of respiratory allergy induced by Dermatophagoides pteronyssinus (Derp).

METHODS

In a 30-day protocol, BALB/c mice were immunized subcutaneously with saline or Derp, alone or in combination with diphtheria-tetanus (DT) or DTPw vaccines (days 0, 7 and 14). Subsequently, they underwent a daily intranasal challenge with saline or Derp (days 22-28) and were then sacrificed (day 29). We evaluated serum-specific immunoglobulins, bronchoalveolar lavage (BAL) cellularity, remodelling of the lower airways, density of polymorphonuclear leukocytes (PMNs) and acidic nasal mucus content.

RESULTS

The animals sensitized with Derp produced high levels of specific immunoglobulins, increased density of PMNs and nasal mucus content, and elevated BAL cellularity and remodelling. Vaccines led to a reduction in IgE levels, with the Derp-DTPw group being similar to the saline groups. The vaccinated groups had reductions of BAL cellularity and remodelling, with more expressive results in the Derp-DTPw group compared to the Derp-DT group. The DT and DTPw vaccines inhibited the nasal PMN infiltrate, and DTPw modulated the production of acidic nasal mucus.

CONCLUSIONS

The DTPw vaccine reduced serum specific IgE, nasal and pulmonary inflammation and remodelling of the lower airways.

The pertussis hypothesis: Bordetella pertussis colonization in the etiology of asthma and diseases of allergic sensitization

Decades of peer reviewed evidence demonstrate that: 1)Bordetellapertussisand pertussis toxin are potent adjuvants, inducing asthma and allergic sensitization in animal models of human disease, 2)Bordetella pertussisoften colonizes the human nasopharynx, and is well documented in highly pertussis-vaccinated populations and 3) in children, a history of whooping cough increases the risk of asthma and allergic sensitization disease. We build on these observations with six case studies and offer a pertussis-based explanation for the rapid rise in allergic disease in former East Germany following the fall of the Berlin Wall; the current asthma, peanut allergy, and anaphylaxis epidemics in the United States; the correlation between the risk of asthma and gross national income per capita by country; the lower risk of asthma and allergy in children raised on farms; and the reduced risk of atopy with increased family size and later sibling birth order. To organize the evidence for the pertussis hypothesis, we apply the Bradford Hill criteria to the association between Bordetella pertussisand asthma and allergicsensitization disease. We propose that, contrary to conventional wisdom that nasopharyngealBordetella pertussiscolonizing infections are harmless, subclinicalBordetella pertussiscolonization is an important cause of asthma and diseases of allergic sensitization.

Novel intranasal pertussis vaccine based on bacterium-like particles as a mucosal adjuvant

Pertussis, or whooping cough, has recently reemerged as a major public health threat despite high levels of vaccination. The development of a novel pertussis vaccine, especially an intranasal (i.n.) vaccine is undoubtedly necessary, and mucosal adjuvants have been explored to enhance the immune response. In the present study, bacterium-like particles (BLPs) were adopted as a mucosal adjuvant for an i.n. pertussis vaccine and evaluated on the ability to induce serum and mucosal antibodies as well as potency against i.n. challenge in mice. Groups with or without aluminum adjuvant were also evaluated through both i.n. and intraperitoneal inoculations. Vaccination with BLPs via the i.n. route led to rapid IgG and IgA production and provided strong protection against inflammation induced by infection. The results support an i.n. pertussis vaccine with BLPs adjuvant as a promising candidate to elicit protective immunity against whooping cough.

Detection of specific bacterial agents by quantitative PCR assays in the bronchoalveolar lavage fluid of dogs with eosinophilic bronchopneumopathy vs. dogs with chronic bronchitis and healthy dogs

In humans, Mycoplasma pneumoniae and Bordetella pertussis infections are suggested to trigger or exacerbate asthma. Whether Mycoplasma or Bordetella are associated with chronic inflammatory bronchial diseases in dogs has not been investigated. The aim of this study was to assess detection rates of Mycoplasma canis (M. canis), M. cynos and Bordetella bronchiseptica (Bb), in dogs with eosinophilic bronchopneumopathy (EBP) and chronic bronchitis (CB), compared with healthy dogs. Specific quantitative PCR (qPCR) analysis for M. canis, M. cynos and Bb were retrospectively performed on bronchoalveolar lavage fluid (BALF) collected from 24 dogs with EBP, 21 dogs with CB and 15 healthy dogs. Possible associations between qPCR results and age, BALF cytology or clinical severity scores (CSS) in dogs with EBP were investigated. There was no difference in M. canis, M. cynos and Bb detection rates in dogs with EBP (n=6, n=2 and n=6, respectively) and dogs with CB (n=2, n=2 and n=2, respectively) compared with control dogs (n=4, n=2 and n=2, respectively). In dogs with EBP, the proportion that were qPCR-positive for Bb was higher in dogs with higher CSS (P=0.014) and BALF from Bb-positive dogs had higher percentage of neutrophils (P<0.001). Among dogs that were qPCR-positive for Bb, moderate to high loads were only detected in dogs with EBP. M. canis and M. cynos detection was not associated with EBP or CB; higher Bb loads were only present in dogs with EBP and high CSS. A possible cause and effect relationship between Bb infection or load and EBP remains unclear and requires further investigation.

Live attenuated vaccines against pertussis

The intensive use of pertussis vaccines has dramatically reduced the incidence of whooping cough during the 20th century. However, recent outbreaks in countries with high vaccination coverage illustrate the shortcomings of current vaccination regimens, and immunity induced by the most recent, acellular vaccines wanes much faster than anticipated. As an alternative, live attenuated vaccine candidates have recently been developed in order to mimic natural infection, which induces long-lasting immunity. One of them has successfully completed a Phase I trial in humans and is now undergoing further product and clinical developments. This article describes the development of such vaccines, discusses their advantages over existing vaccines and their interesting bystander properties as powerful anti-inflammatory agents, which widens their potential use far beyond that for protection against whooping cough.

Attenuated Bordetella pertussis vaccine protects against respiratory syncytial virus disease via an IL-17-dependent mechanism

RATIONALE

We attenuated virulent Bordetella pertussis by genetically eliminating or detoxifying three major toxins. This strain, named BPZE1, is being developed as a possible live nasal vaccine for the prevention of whooping cough. It is immunogenic and safe when given intranasally in adult volunteers.

OBJECTIVES

Before testing in human infants, we wished to examine the potential effect of BPZE1 on a common pediatric infection (respiratory syncytial virus [RSV]) in a preclinical model.

METHODS

BPZE1 was administered before or after RSV administration in adult or neonatal mice. Pathogen replication, inflammation, immune cell recruitment, and cytokine responses were measured.

MEASUREMENTS AND MAIN RESULTS

BPZE1 alone did not cause overt disease, but induced efflux of neutrophils into the airway lumen and production of IL-10 and IL-17 by mucosal CD4(+) T cells. Given intranasally before RSV infection, BPZE1 markedly attenuated RSV, preventing weight loss, reducing viral load, and attenuating lung cell recruitment. Given neonatally, BPZE1 also protected against RSV-induced weight loss even through to adulthood. Furthermore, it markedly increased IL-17 production by CD4(+) T cells and natural killer cells and recruited regulatory cells and neutrophils after virus challenge. Administration of anti-IL-17 antibodies ablated the protective effect of BPZE1 on RSV disease.

CONCLUSIONS

Rather than enhancing RSV disease, BPZE1 protected against viral infection, modified viral responses, and enhanced natural mucosal resistance. Prevention of RSV infection by BPZE1 seems in part to be caused by induction of IL-17. Clinical trial registered with www.clinicaltrials.gov (NCT 01188512).

Immune evasion, immunopathology and the regulation of the immune system

Costs and benefits of the immune response have attracted considerable attention in the last years among evolutionary biologists. Given the cost of parasitism, natural selection should favor individuals with the most effective immune defenses. Nevertheless, there exists huge variation in the expression of immune effectors among individuals. To explain this apparent paradox, it has been suggested that an over-reactive immune system might be too costly, both in terms of metabolic resources and risks of immune-mediated diseases, setting a limit to the investment into immune defenses. Here, we argue that this view neglects one important aspect of the interaction: the role played by evolving pathogens. We suggest that taking into account the co-evolutionary interactions between the host immune system and the parasitic strategies to overcome the immune response might provide a better picture of the selective pressures that shape the evolution of immune functioning. Integrating parasitic strategies of host exploitation can also contribute to understand the seemingly contradictory results that infection can enhance, but also protect from, autoimmune diseases. In the last decades, the incidence of autoimmune disorders has dramatically increased in wealthy countries of the northern hemisphere with a concomitant decrease of most parasitic infections. Experimental work on model organisms has shown that this pattern may be due to the protective role of certain parasites (i.e., helminths) that rely on the immunosuppression of hosts for their persistence. Interestingly, although parasite-induced immunosuppression can protect against autoimmunity, it can obviously favor the spread of other infections. Therefore, we need to think about the evolution of the immune system using a multidimensional trade-off involving immunoprotection, immunopathology and the parasitic strategies to escape the immune response.

Attenuated Bordetella pertussis BPZE1 protects against allergic airway inflammation and contact dermatitis in mouse models

BACKGROUND

We previously reported that prior nasal administration of highly attenuated Bordetella pertussis BPZE1 provides effective and sustained protection against lethal challenge with influenza A viruses. The protective effect was mediated by suppressing the production of major pro-inflammatory mediators. To further explore the anti-inflammatory properties of BPZE1, we investigated the effect of BPZE1 nasal pretreatment on two mouse models of allergic disease, allergic airway inflammation, and contact hypersensitivity (CHS).

METHODS

Allergic reactions were induced in mice nasally pretreated with live attenuated BPZE1 bacteria using the ovalbumin (OVA)-induced allergic airway inflammation and dinitrochlorobenzene (DNCB)-induced CHS models.

RESULTS

Prior BPZE1 nasal treatment suppressed OVA-induced lung inflammation and inflammatory cell recruitment and significantly reduced IgE levels and cytokine production. Similarly, BPZE1 nasal pretreatment markedly inhibited ear swelling, skin inflammation, and production of pro-inflammatory cytokines in the DNCB-induced CHS model. For both models, we showed that BPZE1 pretreatment does not affect the sensitization phase. Upon challenge, BPZE1 pretreatment selectively reduced the level of cytokines whose production is increased and did not affect the basal level of other cytokines. Together, our observations suggest that BPZE1 pretreatment specifically targets those cytokine-producing effector cells that are recruited and involved in the inflammatory reaction.

CONCLUSION

Our study demonstrates the broad anti-inflammatory properties of the attenuated B. pertussis BPZE1 vaccine candidate and supports its development as a promising agent to prevent and/or treat allergic diseases.

Pertussis in infancy and the association with respiratory and cognitive disorders at toddler age

Pertussis in unvaccinated infants can run a severe course and is often accompanied by complications. In this pilot study, we studied whether there is an association between pertussis hospitalisation in infancy and, respiratory symptoms, growth and cognitive development in early childhood. A group of 89 children aged 13-45 months and hospitalised for laboratory confirmed pertussis within the first six months of their life were compared with 172 children without a history of pertussis. Risk ratios (RR) with 95% confidence intervals (CI) of the association between health outcomes and pertussis in infancy were calculated. Weight-for-length and length-for-age z-scores were calculated to investigate growth. Van Wiechen scores were compared to study cognitive development. Children with a history of pertussis in infancy had a greater chance on "asthma symptoms" (RR 2.8 95%CI 1.1-7.0) on toddler age and were more likely to report "respiratory infections" (RR 3.3 95%CI 1.6-6.6). In addition, children with a history of pertussis in infancy had significantly lower weight-for-height in the first 40 months of life. No significant differences in cognitive development were found. We found an association between severe pertussis in infancy and respiratory symptoms on toddler age. The mechanisms that may underlie this association require further investigation.

Attenuated Bordetella pertussis vaccine strain BPZE1 modulates allergen-induced immunity and prevents allergic pulmonary pathology in a murine model

BACKGROUND

Virulent Bordetella pertussis, the causative agent of whooping cough, exacerbates allergic airway inflammation in a murine model of ovalbumin (OVA) sensitization. A live genetically attenuated B. pertussis mucosal vaccine, BPZE1, has been developed that evokes full protection against virulent challenge in mice but the effect of this attenuated strain on the development of allergic responses is unknown.

OBJECTIVE

To assess the influence of attenuated B. pertussis BPZE1 on OVA priming in a murine model of allergic airway inflammation.

METHODS

Mice were challenged with virulent or attenuated strains of B. pertussis, and sensitized to allergen (OVA) at the peak of bacterial carriage. Subsequently, airway pathology, local inflammation and OVA-specific immunity were examined.

RESULTS

In contrast to virulent B. pertussis, live BPZE1 did not exacerbate but reduced the airway pathology associated with allergen sensitization. BPZE1 immunization before allergen sensitization did not have an adjuvant effect on allergen specific IgE but resulted in a statistically significant decrease in airway inflammation in tissue and bronchoalveolar lavage fluid. BPZE1 significantly reduced the levels of OVA-driven IL-4, IL-5 and IL-13 but induced a significant increase in IFN-gamma in response to OVA re-stimulation.

CONCLUSIONS

These data demonstrate that, unlike virulent strains, the candidate attenuated B. pertussis vaccine BPZE1 does not exacerbate allergen-driven airway pathology. BPZE1 may represent an attractive T-helper type 1 promoting vaccine candidate for eradication of whooping cough that is unlikely to promote atopic disease.

Management of bacterial infections in children with asthma

Respiratory viruses are the single most common causes of asthma exacerbations in children. Rhinovirus-induced wheezing is a risk factor for chronic asthma, but its mechanism has remained unknown. Human bocavirus is a common finding in wheezing children, but its role as a respiratory pathogen is still unclear. Mycoplasma pneumoniae may, like viruses, induce wheezing and asthma exacerbation. Chlamydia pneumoniae and, in recent studies, Chlamydia trachomatis, may not only induce asthma exacerbations but may also be involved in the pathogenesis of chronic asthma. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are often involved in respiratory infections associated with wheezing, but there is no evidence for their active role in asthma pathogenesis or exacerbation. This review summarizes current knowledge on the association between respiratory infections and asthma in children, with a special focus on the role of antibiotics in incipient asthma, asthma exacerbation and chronic stable asthma.

A live attenuated Bordetella pertussis candidate vaccine does not cause disseminating infection in gamma interferon receptor knockout mice

Bordetella pertussis is the cause of whooping cough and responsible for 300,000 infant deaths per annum. Current vaccines require 6 months to confer optimal immunity on infants, the population at highest risk. Recently, an attenuated strain of B. pertussis (BPZE1) has been developed to be used as a low-cost, live, intranasal, single-dose vaccine for newborns. Preclinical proof of concept has been established; however, it is necessary to evaluate the safety of BPZE1, especially in immunodeficient models, prior to human clinical trials. Here, the preclinical safety of BPZE1 was examined in well-characterized murine models. Immunocompetent and gamma interferon (IFN-gamma) receptor knockout mice were challenged by aerosol with either virulent B. pertussis or BPZE1. The two strains colonized the lung at equal levels, but inflammation was associated with carriage of only virulent bacteria. Virulent bacteria disseminated to the liver of IFN-gamma receptor-deficient mice, resulting in atypical pathology. In contrast, attenuated BPZE1 did not disseminate in either immunocompetent or immunodeficient mice and did not induce atypical pathology. In neonatal challenge models, virulent B. pertussis infection resulted in significant mortality of both immunodeficient and immunocompetent mice, whereas no mortality was observed for any neonatal mice challenged with BPZE1. BPZE1 was shown to elicit strong IFN-gamma responses in mice, equivalent to those elicited by the virulent streptomycin-resistant B. pertussis Tohama I derivative BPSM, also inducing immunoglobulin G2a, a process requiring TH1 cytokines in mice. These data indicate that a live attenuated whooping cough vaccine candidate shows no signs of disseminating infection in preclinical models but rather evokes an immunological profile associated with optimal protection against disease.

Risk factors for asthma and allergic diseases in school children across Lebanon

Introduction:

Childhood asthma is one of important diseases of childhood. There is no known prevalence of asthma and allergic diseases in Lebanon. This study was conducted with a secondary objective of finding the odds of exposure to asthma, allergic rhinitis and eczema potential risk factors in Lebanese children.

Material and methods:

It is a cross-sectional study on children in public and private schools. A sample of 22 schools participated, where standardized written core questionnaires were distributed. 5–12 year old students completed the questionnaires at home, while 13–14 year old students filled it in class.

Results:

5522 children were evaluated for asthma, allergic rhinitis and atopic eczema prevalence and their associated factors. These diseases seem to be similarly affected by parental respiratory problems, parental smoking, infancy gastroesophageal reflux, recurrent otitis, and previous pertussis. Humidity on the bedroom walls is associated with both asthma and allergic rhinitis, a spongy pillow with both allergic rhinitis and eczema, animal possession with asthma, and noncotton mattress with atopic eczema. The adjusted odds ratios for significant associations varied between 1.25 and 3 (0.0001 < p-value < 0.01).

Conclusion:

These factors are preventable, thus permitting a possible reduction of the prevalence of these diseases.

Inhibition of airway eosinophilia and pulmonary pathology in a mouse model of allergic asthma by the live vaccine strain of Francisella tularensis

BACKGROUND

It has been suggested that exposure to certain microbes and their products, particularly during neonatal and early childhood periods, may shift the immune response towards a T-helper cell (Th) 1 phenotype and thereby prevent the development of and/or alleviate the clinical symptoms of allergic airway diseases.

OBJECTIVE

We evaluated the ability of the live vaccine strain (LVS) of Francisella tularensis to suppress airway eosinophilia and pulmonary pathology in a murine model of allergic airway disease.

METHODS

C57BL/6 mice were sensitized by intraperitoneal injection of ovalbumin (OVA) on days 1 and 14, and challenged intranasally (i.n.) with OVA on day 21 or thereafter. Some sensitized mice were i.n. treated with live LVS or its cell-free sonicate extract (CFSE) before i.n. OVA challenge. Bronchoalveolar lavage fluid, regional lymph node cells, lung tissues and serum samples were collected 3-7 days after the i.n. challenge.

RESULTS

Intranasal and, to a lesser degree, intradermal immunization of OVA-sensitized mice with LVS suppressed the development of airway eosinophilia and associated pulmonary pathology induced by i.n. OVA challenge. Moreover, CFSE prepared from LVS showed a similar inhibitory effect whereas neither LPS nor DNA purified from F. tularensis LVS had such an effect. The inhibition was associated with the reduction in mRNA expression and protein levels of Th2 cytokines IL-5 and IL-13 in the lungs and the enhanced production of OVA-induced IFN-gamma by local draining lymph node cells, but not with the serum levels of OVA-specific IgG1 or IgE.

CONCLUSION

F. tularensis LVS is capable of suppressing allergic airway inflammation probably through a Th1-mediated suppression of an ongoing Th2 response mechanism, and raises the possibility of exploring LVS and its components as potential therapeutic modalities for human allergic asthma.

Reported pertussis infection and risk of atopy in 8- to 12-yr-old vaccinated and non-vaccinated children

Pertussis infection has been suspected to be a potential causal factor in the development of atopic disease because of the effect of pertussis immunization on specific IgE antibodies. Although several studies found a positive association between pertussis infection and atopic disorders, this relationship has not yet been studied in a population stratified by vaccination status. To assess the association between pertussis infection and atopic disorders in pertussis-unvaccinated children and in pertussis-vaccinated children. Using data from a previously conducted study on the relationship between the diphtheria-tetanus-pertussis-(inactivated) poliomyelitis vaccination in the first year of life and atopic disorders, the study population of 1872 8-12 yr old was divided into children pertussis-unvaccinated and children pertussis-vaccinated in the first year of life. Within each group, the association between pertussis infection and atopic disorders (both as reported by the parents) was assessed. In the unvaccinated group, there were no significant associations between pertussis infection and atopic disorders. In the vaccinated group, all associations between pertussis infection and atopic disorders were positive, the associations with asthma [odds ratio (OR) = 2.24, 95% confidence interval (CI(95%)): 1.36-3.70], hay fever (OR = 2.35, CI(95%): 1.46-3.77) and food allergy (OR = 2.68, CI(95%): 1.48-4.85) being significant. There was a positive association between pertussis infection and atopic disorders in the pertussis vaccinated group only. From the present study, it cannot be concluded whether this association is causal or due to reverse causation.

Inhibition of allergic airways disease by immunomodulatory therapy with whole killed Streptococcus pneumoniae

Asthma is a common inflammatory disease of the airways. Current therapies alleviate symptoms but do not treat the disease. We aim to develop effective immunomodulatory therapies (IMTs) for asthma that target the underlying causes of disease based on Streptococcus pneumoniae (Spn). The effect of Spn IMT on the development of asthma [allergic airways disease (AAD)] was determined in mice. Killed Spn was administered before, during or after ovalbumin sensitization, and the subsequent development of AAD was assessed. IMT attenuated T cell cytokine production, goblet cell hyperplasia, airways hyperresponsiveness (AHR), and eosinophil numbers in the blood, bronchoalveolar lavage fluid and peribronchial tissue. This indicates the potential of Spn as an IMT for asthma.

Formalin-Fixed Staphylococcus aureus Particles Prevent Allergic Sensitization in a Murine Model of Type I Allergy

BACKGROUND

Bacterial infections are supposed to act counterregulatory to the development of allergen-specific Th2 immune responses. We analyzed whether administration of extracellular Staphylococcus aureus inhibited experimental sensitization against allergens.

METHODS

BALB/c mice were immunized with alum-adsorbed ovalbumin (OVA) together with formalin-fixed Staphylococcus particles. OVA-specific antibody production and cytokine synthesis by spleen cells was analyzed. Airway reactivity and cellular infiltration into the airways was assessed after intranasal challenge of mice with OVA. In addition, the capacity of Staphylococcus particles to modulate cytokine production by bone marrow-derived dendritic cells was analyzed in vitro.

RESULTS

Simultaneous application of OVA and Staphylococcus particles very efficiently inhibited production of specific IgE and IgG1 as well as secretion of IL-4 and IL-5 by splenocytes, while enhancing IgG2a formation and production of IFN-gamma, indicating a shift from a Th2 response towards a Th1-biased response. This effect was not dependent on the expression of protein A by Staphylococcus. An enhanced frequency or activity of regulatory T cells after administration of Staphylococcus particles was not apparent. Treatment of mice with Staphylococcus particles during the sensitization phase prevented lung inflammation (airway hyperreactivity, eosinophilia) after local challenge with OVA. Culture of bone marrow-derived dendritic cells with Staphylococcus particles induced IL-12p35 and p40 mRNA expression as well as secretion of IL-12p70, and increased production of IL-10 mRNA and protein.

CONCLUSIONS

Administration of formalin-fixed Staphylococcus particles induced Th1-biased immune responses and prevented allergic sensitization.

IL-1beta and TNF-alpha induce increased expression of CCL28 by airway epithelial cells via an NFkappaB-dependent pathway

CCL28 is a mucosal chemokine that attracts eosinophils and T cells via the receptors CCR3 and CCR10. Consequently, it is a candidate mediator of the pathology associated with asthma. This study examined constitutive and induced expression of CCL28 by A549 human airway epithelial-like cells. Real-time RT-PCR and ELISA of cultured cells and supernatants revealed constitutive levels of CCL28 expression to be low, whereas IL-1beta and TNF-alpha, induced significantly increased expression. Observations from induced sputum and human airway biopsies supported this. Signal transduction studies revealed that IL-1beta and TNF-alpha stimulation induced NFkappaB phosphorylation in A549 cells, but antagonist inhibition of NFkappaB p50-p65 phosphorylation correlated with marked reduction of IL-1beta or TNF-alpha induced CCL28 expression. Together these studies imply a role for CCL28 in the orchestration of airway inflammation, and suggest that CCL28 is one link between microbial insult and the exacerbation of pathologies such as asthma, through an NFkappaB-dependent mechanism.

Downregulation of IgE antibody and allergic responses in the lung by epidermal biolistic microparticle delivery

BACKGROUND

Biolistic injections provide a needle-free delivery of antigen-laden microparticles to the epithelium. The precision of the injection preferentially targets the Langerhans cell network, which, although ideal for vaccination, might not be suitable for the downregulation of immune responses in immunotherapy.

OBJECTIVE

We sought to determine the ability of biolistic injection of antigen into the epithelium of sensitized mice to inhibit IgE antibody and lung inflammatory responses produced by further exposure to antigen.

METHODS

Mice were sensitized by means of a needle injection of ovalbumin (OVA) in alum and given a series of biolistic injections of OVA or vehicle control, followed by a boost of OVA in alum. Serum IgE and IgG antibodies were measured before and after the boost. The mice were then challenged intranasally, and the infiltration of inflammatory cells was measured by means of bronchoalveolar lavage. Airway reactivity of the challenged mice was measured by examining responses to methacholine with forced oscillatory techniques.

RESULTS

Biolistic injection of OVA into the dorsal skin of sensitized mice markedly inhibited IgE and IgG1 antibody responses induced by boosting. IgG2a antibody responses were reduced rather than stimulated. The eosinophilic inflammation in the bronchoalveolar lavage fluid induced by intranasal challenge was also markedly inhibited. Lung hyperreactivity showed an initial increase and then a decrease of responsiveness to methacholine, with elastance returning to the level of unsensitized mice. Biolistic injection into the buccal epithelium was also inhibitory.

CONCLUSIONS

Biolistic injection of allergen inhibited the boosting of IgE antibody and eosinophilic lung inflammatory responses without inducing T(H)1 immunity.

Inflammation of the respiratory tract is associated with CCL28 and CCR10 expression in a murine model of allergic asthma

Mouse models and in vitro cell culture were used to examine airway expression of the mucosal chemokine CCL28. Low levels of constitutively expressed mRNA were observed in transformed murine epithelial cells, but high levels could be induced by stimulation. Cytokines that signal through NF-kappaB, including IL-1beta and TNF-alpha or via JAK-STAT pathway including oncostatin M induced CCL28 in airway epithelial cells in vitro. Immunohistochemistry of murine airway tissue revealed that constitutive expression of CCL28 protein in vivo was low and not ubiquitous. However, abundant expression was detected in epithelia and lymphoid aggregates following allergic sensitization and challenge with ovalbumin. This was accompanied by increased detection of cells expressing CCR10 protein and mRNA in inflamed airways. Taken together, these data support a role for CCL28 in contributing to allergen driven airway pathologies, show that proinflammatory cytokines can induce this signal and suggest a role for CCR10 expressing cells in airway inflammation.

Immunogenicity of adult mesenchymal stem cells: lessons from the fetal allograft

Herein we review recent data that support host tolerance of allogeneic adult mesenchymal stem cells (MSC). Evidence is emerging that donor MSC deploy a very powerful array of mechanisms that allow escape from host allogeneic responses. These mechanisms include limited expression of alloantigen by the stem cell and cell contact-dependent and -independent mechanisms. MSC modulate host dendritic cell and T cell function, promoting induction of suppressor or regulatory T cells. These effects are complemented by the induction of divisional arrest anergy in T cells and by stem cell production of soluble immunomodulatory factors, including interleukin-10, transforming growth factor-beta, prostaglandin E2, and hepatocyte growth factor. In addition, MSC express the enzyme indoleamine 2,3-dioxygenase, which creates a tryptophan-depleted milieu that promotes immunosuppression. We propose that these observations show striking similarity to emerging data on the maternal acceptance of the fetal allograft. This comparison suggests new approaches to determine the contribution of different mechanisms to the successful use of MSC in regenerative medicine.

Acellular pertussis vaccine protects against exacerbation of allergic asthma due to Bordetella pertussis in a murine model

The prevalence of asthma and allergic disease has increased in many countries, and there has been speculation that immunization promotes allergic sensitization. Bordetella pertussis infection exacerbates allergic asthmatic responses. We investigated whether acellular pertussis vaccine (Pa) enhanced or prevented B. pertussis-induced exacerbation of allergic asthma. Groups of mice were immunized with Pa, infected with B. pertussis, and/or sensitized to ovalbumin. Immunological, pathological, and physiological changes were measured to assess the impact of immunization on immune deviation and airway function. We demonstrate that immunization did not enhance ovalbumin-specific serum immunoglobulin E production. Histopathological examination revealed that immunization reduced the severity of airway pathology associated with sensitization in the context of infection and decreased bronchial hyperreactivity upon methacholine exposure of infected and sensitized mice. These data demonstrate unequivocally the benefit of Pa immunization to health and justify selection of Pa in mass vaccination protocols. In the absence of infection, the Pa used in this study enhanced the interleukin-10 (IL-10) and IL-13 responses and influenced airway hyperresponsiveness to sensitizing antigen; however, these data do not suggest that Pa contributes to childhood asthma overall. On the contrary, wild-type virulent B. pertussis is still circulating in most countries, and our data suggest that the major influence of Pa is to protect against the powerful exacerbation of asthma-like pathology induced by B. pertussis.

Mesenchymal stem cells avoid allogeneic rejection

Adult bone marrow derived mesenchymal stem cells offer the potential to open a new frontier in medicine. Regenerative medicine aims to replace effete cells in a broad range of conditions associated with damaged cartilage, bone, muscle, tendon and ligament. However the normal process of immune rejection of mismatched allogeneic tissue would appear to prevent the realisation of such ambitions. In fact mesenchymal stem cells avoid allogeneic rejection in humans and in animal models. These finding are supported by in vitro co-culture studies. Three broad mechanisms contribute to this effect. Firstly, mesenchymal stem cells are hypoimmunogenic, often lacking MHC-II and costimulatory molecule expression. Secondly, these stem cells prevent T cell responses indirectly through modulation of dendritic cells and directly by disrupting NK as well as CD8+ and CD4+ T cell function. Thirdly, mesenchymal stem cells induce a suppressive local microenvironment through the production of prostaglandins and interleukin-10 as well as by the expression of indoleamine 2,3,-dioxygenase, which depletes the local milieu of tryptophan. Comparison is made to maternal tolerance of the fetal allograft, and contrasted with the immune evasion mechanisms of tumor cells. Mesenchymal stem cells are a highly regulated self-renewing population of cells with potent mechanisms to avoid allogeneic rejection.

Whole-cell pertussis vaccine protects against Bordetella pertussis exacerbation of allergic asthma

The prevalence of asthma and allergic disease has increased in many countries and there has been speculation that immunization promotes allergic sensitization. Bordetella pertussis infection exacerbates allergic asthmatic responses. We investigated whether whole-cell pertussis vaccine (Pw) enhanced or prevented B. pertussis induced exacerbation of allergic asthma. Groups of mice were immunized with Pw, infected with B. pertussis and/or sensitized to ovalbumin. Immunological, pathological and physiological changes were measured to assess the impact of Pw immunization on immune deviation and airway function. Pw immunization modulated ovalbumin-specific serum IgE production, and reduced local and systemic IL-13 and other cytokine responses to sensitizing allergen. Histopathological examination revealed Pw immunization reduced the severity of airway pathology and decreased bronchial hyperreactivity to methacholine exposure. Pw does not enhance airway IL-13 and consequently does not enhance but protects against the exacerbation of allergic responses. We find no evidence of Pw contributing to allergic asthma, but rather provide evidence of a mechanism whereby whole-cell pertussis vaccination has a protective role.