IL-4 and IL-5 mRNA and protein in bronchial biopsies from patients with atopic and nonatopic asthma: evidence against "intrinsic" asthma being a distinct immunopathologic entity

TRP channels: emerging targets for respiratory disease

The mammalian transient receptor potential (TRP) superfamily of cation channels is divided into six subfamilies based on sequence homology TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPA (ankyrin), TRPP (polycystin) and TRPML (mucolipin). The expression of these channels is especially abundant in sensory nerves, and there is increasing evidence demonstrating their existence in a broad range of cell types which are thought to play a key role in respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). These ion channels can be activated by a diverse range of chemical and physical stimuli. Physical stimuli include temperature, membrane potential changes and osmotic stress, and some of the more well known chemical stimuli include capsaicin (TRPV1), menthol (TRPM8) and acrolein (TRPA1). There is increasing evidence in this rapidly moving field to suggest that selective blockers of these channels may represent attractive novel strategies to treat characteristic features of respiratory diseases such as asthma and COPD. This review focuses on summarising the evidence that modulation of selected TRP channels may have beneficial effects at targeting key features of these respiratory diseases including airways inflammation, airways hyper-reactivity, mucus secretion and cough.

Seeking common pathophysiology in asthma, atopy and sinusitis

Asthma and chronic sinusitis are inexplicably common airway diseases that are linked to atopy and allergic inflammation. T helper type 2 (Th2) cells and the associated cytokines are believed to play crucial pathogenic roles in asthma, but the environmental factors that instigate allergic airway disease remain poorly understood. Environmental proteinases are highly allergenic and are candidate inducers of airway Th2 responses. Determining the proteinases and their sources that are relevant to airway disease, however, remains challenging. In this Opinion, we summarize the evidence that implicates fungi as both a relevant source of allergenic proteinases and a potential cause of asthma, atopy and chronic sinusitis through airway infection. Clarification of the extrinsic causes of these processes will markedly improve diagnosis, prognosis and therapy.

Immunological and genetic aspects of asthma and allergy

Prevalence of allergy and allergic asthma are increasing worldwide. More than half of the US population has a positive skin prick test and approximately 10% are asthmatics. Many studies have been conducted to define immunological pathways underlying allergy and asthma development and to identify the main genetic determinants. In the effort to find missing pieces of the puzzle, new genomic approaches and more standardized ones, such as the candidate gene approach, have been used collectively. This article proposes an overview of the actual knowledge about immunological and genetic aspects of allergy and asthma. Special attention has been drawn to the challenges linked to genetic research in complex traits such as asthma and to the contribution of new genomic approaches.

Increases in airway eosinophilia and a th1 cytokine during the chronic asymptomatic phase of asthma

BACKGROUND

Studies using allergen challenge models have suggested Th2 cytokines promote airway inflammation in asthma. We assessed mediators of airway inflammation during the chronic asymptomatic phase of asthma.

METHODS

Nine non-atopic asthma (NAA) patients, 19 atopic asthma (AA) patients, 20 atopic controls (AC), and 38 normal controls (NC) underwent sputum induction while asymptomatic. Sputum total cell counts and differentials were determined; levels of cytokines IL-4, IL-5, IL-13, GM-CSF, and IFN-gamma, and chemokines eotaxin (CCL11) and RANTES (CCL5) were measured by ELISA; and levels of eosinophil-derived neurotoxin (EDN) were measured by radioimmunoassay.

RESULTS

NAA patients showed higher % eosinophils and total eosinophils compared to AA. NAA and AA patients showed higher IFN-gamma and EDN levels compared to AC and NC, with no differences in IL-4, IL-5, or IL-13 levels among the four groups. GM-CSF levels were higher in AA patients compared to AC or NC. In NAA, AA, and AC patients, % eosinophils and EDN levels correlated positively with IFN-gamma, GM-CSF, eotaxin, and RANTES, but not with IL-5 levels.

CONCLUSIONS

Baseline airway inflammation of intrinsic and extrinsic asthma is characterized by eosinophilic inflammation and the Th1 cytokine, IFN-gamma. GM-CSF, instead of IL-5, and chemokines may coordinate airway eosinophilia during the chronic asymptomatic phase of asthma.

The role of the T cell in asthma

Since the initial detection of T(H)2 cytokines in asthmatic airways, our understanding of the complexity of T-cell subtypes and flexibility and of the potential role of airway structural cells in the immunopathology of asthma has increased. Cytokines derived from airway epithelium, including IL-25, IL-33, and thymic stromal lymphopoietin, might be important drivers of T(H)2-type inflammation in asthma. The balance between effector T(H)2 cells and suppressive regulatory T cells is skewed toward a proinflammatory T(H)2 response in atopy and asthma, and there is much interest in how to redress this equilibrium. Novel T-cell subsets, including T(H)17, T(H)9, and T(H)22, have been described, although their role in asthma remains unclear. Other T cells, including natural killer T cells, γδ T cells, and CD8 T cells, have also been implicated in asthma, although their importance remains to be confirmed. Therapeutic strategies aimed at T(H)2 cytokines are beginning to bear fruit in patients with asthma, although like many biologic agents, these might need specific targeting at subgroups of patients. Strategies directed specifically at the T cells are currently being evaluated, including novel forms of allergen immunotherapy. T cells remain an exciting potential target for new treatments in patients with asthma.

Anisakis pegreffii-induced airway hyperresponsiveness is mediated by gamma interferon in the absence of interleukin-4 receptor alpha responsiveness

Infection with the fish parasite Anisakis following exposure to contaminated fish can lead to allergic reactions in humans. The present study examined the immunological mechanisms underlying the development of allergic airway inflammation in mice after different routes of sensitization to Anisakis. Wild-type and interleukin-4 receptor alpha (IL-4Ralpha)-deficient BALB/c mice were sensitized intraperitoneally with live or heat-killed Anisakis larvae or by intranasal administration of an Anisakis extract and were subsequently challenged intranasally with an Anisakis extract. Both routes of sensitization induced IL-4Ralpha-dependent allergic airway responses, whereas allergen-specific antibody responses developed only when mice were sensitized intraperitoneally. Intranasal sensitization induced airway hyperresponsiveness (AHR) in wild-type mice only, showing that AHR was IL-4/IL-13 dependent. Unexpectedly, infection with Anisakis larvae induced AHR in both wild-type and IL-4Ralpha-deficient mice. IL-4Ralpha-independent AHR was mediated by gamma interferon (IFN-gamma), as evidenced by the fact that in vivo neutralization of IFN-gamma abrogated AHR. Together, these results demonstrate that both infection with larvae and inhalational exposure to Anisakis proteins are potent routes of allergic sensitization to Anisakis, explaining food- and work-related allergies in humans. Importantly for diagnosis, allergic airway inflammation can be independent of detectable Anisakis-specific antibodies. Moreover, depending on the route of sensitization, AHR can be induced either by IL-4/IL-13 or by IFN-gamma.

Asthma and autoimmunity: a complex but intriguing relation

Asthma and autoimmune diseases apparently have little to share except for the involvement of the immune system in both types of disorder. However, epidemiological studies have shown that asthma and Type 1 diabetes, a typical autoimmune disease, are associated at the population level, and some experimental findings have suggested that autoimmune mechanisms might be operating in asthma as well. Female preponderance, increased incidence of antinuclear autoantibodies and detection of autoantibodies against either bronchial epithelial antigens or endothelial antigens in patients with nonallergic asthma suggest that the disease may have an autoimmune basis. Approximately 50% of patients with nonallergic asthma react to intradermal injection of autologous serum, indicating the presence of circulating vasoactive factors and suggesting an autoreactive mechanism. Recent findings in experimental animals support the involvement of an autoreactive mechanism in allergic asthma as well, indicating that human alpha-nascent polypeptide-associated complex, identified as an IgE-reactive autoantigen, has the potential to sensitize and induce immediate skin reactions and airway inflammation. In summary, asthma is a heterogeneous disorder characterized by chronic inflammation of the respiratory airways that can be triggered by allergen exposure or by other mechanisms, possibly autoreactive/autoimmune. The autoimmune hypothesis is further, indirectly, supported by the response to immunosuppressive drugs.

Local production of IgE in the respiratory mucosa and the concept of entopy: does allergy exist in nonallergic rhinitis?

OBJECTIVE

To review research regarding locally produced IgE and its impact on patients with chronic rhinitis.

DATA SOURCES

PubMed search with the following keywords: entopy, local IgE, nonallergic rhinitis, idiopathic rhinitis, vasomotor rhinitis, and allergic rhinitis.

STUDY SELECTION

Articles were selected based on their relevance to entopy and locally produced IgE and its clinical effect and relationship to idiopathic rhinitis (IR).

RESULTS

Local IgE has been found in a variety of tissues, including nasal and bronchial mucosa. IgE is produced in these local tissues and not simply the product of migration to the tissue from regional lymphoid tissue or blood. Local IgE has been identified in most of both atopic and nonatopic asthmatic patients and allergic rhinitis patients. Up to 40% of patients with IR and a positive nasal provocation test result have evidence of locally produced IgE, which has been coined entopy. Although patients with allergic rhinitis and IR show similar inflammatory patterns with increased activated mast cells, eosinophils, and T-cell subsets in some studies, other studies on IR patients are conflicting with regard to both inflammation and allergen-specific nasal provocation test results.

CONCLUSION

The concept of local allergy in IR patients is both intriguing and controversial. Studies have reported conflicting results, and currently there is no single best test to evaluate for entopy. It is known that there are a large number of IR patients for whom current treatment regimens are suboptimal. Therefore, further research elucidating the mechanisms of IR and the concept of localized IgE are needed to optimally diagnose this condition and treat this group of patients.

Importance of cytokines in murine allergic airway disease and human asthma

Asthma is a common, disabling inflammatory respiratory disease that has increased in frequency and severity in developed nations. We review studies of murine allergic airway disease (MAAD) and human asthma that evaluate the importance of Th2 cytokines, Th2 response-promoting cytokines, IL-17, and proinflammatory and anti-inflammatory cytokines in MAAD and human asthma. We discuss murine studies that directly stimulate airways with specific cytokines or delete, inactivate, neutralize, or block specific cytokines or their receptors, as well as controversial issues including the roles of IL-5, IL-17, and IL-13Ralpha2 in MAAD and IL-4Ralpha expression by specific cell types. Studies of human asthmatic cytokine gene and protein expression, linkage of cytokine polymorphisms to asthma, cytokine responses to allergen stimulation, and clinical responses to cytokine antagonists are discussed as well. Results of these analyses establish the importance of specific cytokines in MAAD and human asthma and have therapeutic implications.

Natural killer T cells are not the predominant T cell in asthma and likely modulate, not cause, asthma

Asthma is a multifactorial disease of the airways characterized by airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. Conventional MHC class II-restricted CD4(+) T cells are considered a key cell in asthma pathogenesis because they have a broad T-cell receptor repertoire, providing specificity and reactivity to diverse protein allergens. This notion was challenged when a study found that invariant Natural Killer (NK) T cells were the predominant T cells in the lung and bronchoalveolar lavage fluid of all asthmatic subjects studied. This finding was provocative because invariant NKT cells have a very limited T-cell receptor repertoire and are specific for a restricted set of lipid antigens that bind to CD1d, a nonpolymorphic MHC-like molecule. However, multiple subsequent studies failed to replicate the initial study and instead found that invariant NKT cells are present as a small fraction of the total T cells in the asthmatic lung. Thus, we believe that although CD1d-restricted NKT cells might play a role in modulating the asthmatic phenotype, they are not the critical drivers of the asthmatic response, a role we believe is still held by conventional MHC class II-restricted CD4(+) T cells.

Gastrointestinal eosinophils in health, disease and functional disorders

Eosinophils are potent innate immune cells that home to the gastrointestinal tract where they participate in host immunity to luminal pathogens, and help to maintain intestinal epithelial homeostasis. However, these cells are now recognized to have key functions in the pathogenesis of numerous other disorders of the gastrointestinal tract, including primary eosinophilic gastrointestinal disease, common functional conditions, such as dyspepsia, and also in gastrointestinal disorders in patients with allergic disease. We are just beginning to understand the potential pathological role of eosinophils in gastrointestinal disease, and it is increasingly likely that gastroenterologists and histopathologists will need to account for the presence of gastrointestinal eosinophils and relate their presence to gastrointestinal symptoms. This Review discusses the role of gastrointestinal eosinophils in health and disease, including their associations with functional and allergic disorders.

Asthma: Pathophysiology and Diagnosis

Although asthma is a common disorder affecting approximately 7.8% of the United States population (Schiller et al. 2006) or 23 million Americans, the pathogenesis of this disease remains to be fully elucidated. Extensive research over the last few decades has yielded a better understanding of asthma. We know that the basic features of asthma include episodic airways inflammation, airways hyperresponsiveness, and mucous hypersecretion. Although we understand the basic clinical features of asthma, the links between symptoms, physical signs, and underlying pathophysiological mechanisms are still being delineated. Asthma is a heterogeneous disease process with varying phenotypes and presentations. In this chapter, we will briefly explore some major theories of asthma pathogenesis, both new and old. We will also explore how understanding the pathophysiology of asthma can help us to understand the symptoms and presentation of asthma, as well as the best strategies for diagnosing this disease.

Effects of omalizumab on markers of inflammation in patients with allergic asthma

Asthma is a chronic inflammatory disease of the airways in which immunoglobulin E (IgE) plays a key role by activating a variety of inflammatory cells through interactions with FcepsilonRI and FcepsilonRII receptors. The role of IgE in allergic inflammation provided the rationale for developing omalizumab, a humanized monoclonal anti-IgE antibody, for patients with moderate-to-severe or severe allergic asthma. The reductions in circulating levels of IgE resulting from omalizumab treatment leads to reductions in FcepsilonRI expression on mast cells, basophils and dendritic cells. This combined effect results in attenuation of several markers of inflammation, including peripheral and bronchial tissue eosinophilia and levels of granulocyte macrophage colony stimulating factor, interleukin (IL)-2, IL-4, IL-5 and IL-13. By blocking IgE binding to its receptors and diminishing dendritic cell FcepsilonRI receptor expression, omalizumab may also reduce allergen presentation to T cells and the production of Th2 cytokines. The anti-inflammatory effects of omalizumab may, therefore, explain the reductions in asthma exacerbations and symptoms seen in clinical trials in patients with moderate-to-severe or severe, persistent, inadequately controlled allergic asthma.

Exhaled nitric oxide and exercise-induced bronchoconstriction in young wheezy children - interactions with atopy

The association between exercise-induced bronchoconstriction (EIB) and exhaled nitric oxide (FE(NO)) has not been investigated in young children with atopic or non-atopic wheeze, two different phenotypes of asthma in the early childhood. Steroid naïve 3- to 7-yr-old children with recent wheeze (n = 84) and age-matched control subjects without respiratory symptoms (n = 71) underwent exercise challenge test, measurement of FE(NO) and skin prick testing (SPT). EIB was assessed by using impulse oscillometry, and FE(NO) by standard online technique. Although FE(NO) levels were highest in atopic patients with EIB, both atopic and non-atopic wheezy children with EIB showed higher FE(NO) than atopic and non-atopic control subjects, respectively. In atopic wheezy children, a significant relationship between FE(NO) and the severity of EIB was found (r = 0.44, p = 0.0004), and FE(NO) was significantly predictive of EIB. No clear association between FE(NO) and EIB or predictive value was found in non-atopic wheezy children. Both atopic and non-atopic young wheezy children with EIB show increased FE(NO) levels. However, the association between the severity of EIB and FE(NO) is present and FE(NO) significantly predictive of EIB only in atopic subjects, suggesting different interaction between bronchial responsiveness and airway inflammation in non-atopic wheeze.

Link between allergic asthma and airway mucosal infection suggested by proteinase-secreting household fungi

Active fungal proteinases are powerful allergens that induce experimental allergic lung disease strongly resembling atopic asthma, but the precise relationship between proteinases and asthma remains unknown. Here, we analyzed dust collected from the homes of asthmatic children for the presence and sources of active proteinases to further explore the relationship between active proteinases, atopy, and asthma. Active proteinases were present in all houses and many were derived from fungi, especially Aspergillus niger. Proteinase-active dust extracts were alone insufficient to initiate asthma-like disease in mice, but conidia of A. niger readily established a contained airway mucosal infection, allergic lung disease, and atopy to an innocuous bystander antigen. Proteinase produced by A. niger enhanced fungal clearance from lung and was required for robust allergic disease. Interleukin 13 (IL-13) and IL-5 were required for optimal clearance of lung fungal infection and eosinophils showed potent anti-fungal activity in vitro. Thus, asthma and atopy may both represent a protective response against contained airway infection due to ubiquitous proteinase-producing fungi.

Chronic and repeated Chlamydophila pneumoniae lung infection can result in increasing IL-4 gene expression and thickness of airway subepithelial basement membrane in mice

BACKGROUND/PURPOSE

Chlamydophila pneumoniae infection has been associated with several pulmonary and cardiac diseases. However, it has not been explored for its ability to activate the same immunopathologic mechanisms of asthma, namely, a predominant Th2 immune response and structural changes that are termed airway remodeling. This study evaluated immune responses in the lung and airway pathology of BALB/c mice with chronic and repeated C. pneumoniae infections.

METHODS

Mice were inoculated intranasally with 5 x 10(6) inclusion-forming units of C. pneumoniae TWAR strain, and re-inoculated at 14 and 42 days after the primary inoculation. Cytokine gene expression in bronchoalveolar lavage (BAL) cells was analyzed by RT-PCR on day 70. Airway pathology was also evaluated by morphometric measurements.

RESULTS

A significant increase of interleukin (IL)-4 mRNA was detected in BAL cells in infected mice, and a significant increase in subepithelial basement membrane thickness of the airways was also noted in infected mice as compared with control mice (8.95 +/- 0.28 microm vs. 5.54 +/- 0.22 microm, p < 0.0001). We further analyzed the correlation between IL-4 cytokine expression and the increased subepithelial basement membrane thickness of airways in infected mice. We found that mice with increased IL-4 mRNA expression had significant increases in the thickness of subepithelial basement membrane as compared with mice without increased IL-4 mRNA expression (9.87 +/- 0.51 microm vs. 6.49 +/- 0.52 microm, p < 0.0001).

CONCLUSION

It is believed that our results demonstrated for the first time that chronic and repeated infections with C. pneumoniae increased IL-4 gene expression and thickness of airway subepithelial basement membrane in mice.

Regulatory T cells in bronchial asthma

The main focus of this review was the role of a specific subset of T cells with immunomodulatory or immunosuppressive activities, termed regulatory T cells (Tregs), in the pathogenesis and treatment of bronchial asthma. Evidence that these cells are important in maintaining immune homeostasis in health and exhibit impaired activity in active disease will be discussed. Their therapeutic potential is perhaps best highlighted by evidence that therapies with demonstrated efficacy in allergic and asthmatic disease are associated with the induction or restoration of regulatory T-cell function, e.g. glucocorticoids, allergen immunotherapy. Strategies to improve the safety and efficacy of these treatments and that induce or boost Tregs in bronchial asthma are discussed.

Protein/DNA vaccine-induced antigen-specific Treg confer protection against asthma

Asthma is a chronic inflammatory disorder caused by T-cell-mediated inflammation within airways. No antigen-specific treatment has been available. Using an OVA-induced murine asthma model, we find that co-immunization of an OVA epitope peptide with a DNA vaccine encoding the same epitope is able to prevent this experimental asthma as evidenced in the marked reduction of infiltrations of eosinophils and lymphocytes into the site of the allergen challenge. We demonstrate that the prevention of experimental asthma was directly related to the induction of a population of OVA-specific T-regulatory cells (Treg) exhibiting a CD4(+)CD25(-)FoxP3(+) phenotype and expressing IL-10, TGF-beta and IFN-gamma following the co-immunization. Blockade of IL-10 and TGF-beta of the Treg by anti-IL-10 and TGF-beta antibodies is partially able to reverse the suppression in vitro and in vivo, which caused the recurrence of the inflammation. Furthermore, adoptive transfer of the induced Treg is also able to suppress the OVA-induced asthma. To our knowledge, the combination of peptide with its cognate DNA vaccine protect experimental asthma via the induced epitope-specific Treg has not been previously reported and such strategy may lead to a novel immunotherapy against asthma in humans.

Asthma: a syndrome composed of heterogeneous diseases

OBJECTIVE

To review the concept that asthma comprises distinct heterogeneous inflammatory disorders characterized by patients showing different phenotypes with distinct genetic components, environmental causes, and immunopathologic signa-

DATA SOURCES

Ovid MEDLINE and PubMed databases from 1950 to the present time were searched for relevant articles and references regarding the heterogeneity of asthma.

STUDY SELECTION

Articles that described the various phenotypes of asthma were used for this review.

RESULTS

Asthma is unlikely to be a single disease but rather a series of complex, overlapping individual diseases or phenotypes, each defined by its unique interaction between genetic and environmental factors. These conditions include syndromes characterized by allergen-exacerbated, nonallergic, and aspirin-exacerbated factors along with syndromes best distinguished by their pathologic findings (eosinophilic, neutrophilic, pauci-granulocytic), response to therapy (corticosteroid resistant), and natural history (remodeling prone). Additional phenotypes will almost certainly be identified as advances in genetics and other profiling methods are made and will be accompanied by the availability of clear biomarkers for distinguishing among them.

CONCLUSIONS

Responses to asthma medications vary considerably among patients, likely reflecting, at least in part, the differing sensitivities of the various asthma phenotypes. Selecting the best possible treatment course in individual patients will be aided by clearly identifying the different phenotypes. Physicians need to recognize this when making decisions to adjust treatment to improve asthma control.

Dipeptidyl peptidase I-dependent neutrophil recruitment modulates the inflammatory response to Sendai virus infection

The role of innate immunity in the pathogenesis of asthma is unclear. Although increased presence of neutrophils is associated with persistent asthma and asthma exacerbations, how neutrophils participate in the pathogenesis of asthma remains controversial. In this study, we show that the absence of dipeptidyl peptidase I (DPPI), a lysosomal cysteine protease found in neutrophils, dampens the acute inflammatory response and the subsequent mucous cell metaplasia that accompanies the asthma phenotype induced by Sendai virus infection. This attenuated phenotype is accompanied by a significant decrease in the accumulation of neutrophils and the local production of CXCL2, TNF, IL-1beta, and IL-6 in the lung of infected DPPI-/- mice. Adoptive transfer of DPPI-sufficient neutrophils into DPPI-/- mice restored the levels of CXCL2 and enhanced cytokine production on day 4 postinfection and subsequent mucous cell metaplasia on day 21 postinfection. These results indicate that DPPI and neutrophils play a critical role in Sendai virus-induced asthma phenotype as a result of a DPPI-dependent neutrophil recruitment and cytokine response.

Interleukin-4, interleukin-13, signal transducer and activator of transcription factor 6, and allergic asthma

Interleukin (IL)-4 and IL-13 share many biological activities. To some extent, this is because they both signal via a shared receptor, IL-4Ralpha. Ligation of IL-4Ralpha results in activation of Signal Transducer and Activator of Transcription factor 6 (STAT6) and Insulin Receptor Substrate (IRS) molecules. In T- and B-cells, IL-4Ralpha signaling contributes to cell-mediated and humoral aspects of allergic inflammation. It has recently become clear that IL-4 and IL-13 produced in inflamed tissues activate signaling in normally resident cells of the airway. The purpose of this review is to critically evaluate the contributions of IL-4- and IL-13-induced tissue responses, especially those mediated by STAT6, to some of the pathologic features of asthma including eosinophilic inflammation, airway hyperresponsiveness, subepithelial fibrosis and excessive mucus production. We also review the functions of some recently identified IL-4- and/or IL-13-induced mediators that provide some detail on molecular mechanisms and suggest an important contribution to host defense.

Asthma: eosinophil disease, mast cell disease, or both?

Although there is much circumstantial evidence implicating eosinophils as major orchestrators in the pathophysiology of asthma, recent studies have cast doubt on their importance. Not only does anti-interleukin-5 treatment not alter the course of the disease, but some patients with asthma do not have eosinophils in their airways, whereas patients with eosinophilic bronchitis exhibit a florid tissue eosinophilia but do not have asthma. In contrast, mast cells are found in all airways and localize specifically to key tissue structures such as the submucosal glands and airway smooth muscle within asthmatic bronchi, irrespective of disease severity or phenotype. Here they are activated and interact exclusively with these structural cells via adhesive pathways and through the release of soluble mediators acting across the distance of only a few microns. The location of mast cells within the airway smooth muscle bundles seems particularly important for the development and propagation of asthma, perhaps occurring in response to, and then serving to aggravate, an underlying abnormality in asthmatic airway smooth muscle function. Targeting this mast cell-airway smooth muscle interaction in asthma offers exciting prospects for the treatment of this common disease.

Nonatopic children with multitrigger wheezing have airway pathology comparable to atopic asthma

RATIONALE

Epidemiologic studies have shown that, in atopic children, wheezing is more likely to persist into adulthood, eventually becoming asthma, whereas it appears to resolve by adolescence in nonatopic children.

OBJECTIVES

To investigate whether among children with multitrigger wheeze responsive to bronchodilators the airway pathology would be different in nonatopic wheezers, who are often considered nonasthmatic, compared with atopic wheezers, who are more frequently diagnosed as having asthma.

METHODS

Bronchial biopsies were obtained from 55 children undergoing bronchoscopy for appropriate clinical indications: 18 nonatopic children with multitrigger wheeze (median age, 5 yr; range, 2-10 yr), 20 atopic children with multitrigger wheeze (medan age, 5 yr; range, 2-15 yr), and 17 control children with no atopy or wheeze (median age, 4; range, 2-14 yr). By histochemistry and immunohistochemistry, we quantified epithelial loss, basement membrane thickness, angiogenesis, inflammatory cells, IL-4(+,) and IL-5(+) cells in subepithelium.

MEASUREMENTS AND MAIN RESULTS

Unexpectedly, all pathologic features examined were similar in atopic and nonatopic wheezing children. Compared with control subjects, both nonatopic and atopic wheezing children had increased epithelial loss (P = 0.03 and P = 0.002, respectively), thickened basement membrane (both P < 0.0001), and increased number of vessels (P = 0.003 and P = 0.03, respectively) and eosinophils (P < 0.0001 and P = 0.002, respectively). Moreover, they had increased cytokine expression, which was highly significant for IL-4 (P = 0.002 and P = 0.0001, respectively) and marginal for IL-5 (P = 0.02 and P = 0.08, respectively).

CONCLUSIONS

This study shows that the airway pathology typical of asthma is present in nonatopic wheezing children just as in atopic wheezing children. These results suggest that, when multitrigger wheezing responsive to bronchodilators is present, it is associated with pathologic features of asthma even in nonatopic children.

Non-atopic asthma in children is related to maternal bronchial hyperreactivity

Data on the pathogenic mechanisms underlying the development of non-atopic asthma in children are scarce. Our aim was to evaluate the association and compare the atopic status, pulmonary functions, bronchial hyperresponsiveness and serum total immunoglobulin E (IgE) levels of parents of atopic and non-atopic asthmatic children by using objective methods. Fifty-one asthmatic children aged 4-16 yr and their parents were included into the study. Initially the American Thoracic Society's Respiratory Disease questionnaire inquiring data on symptoms of asthma, rhinitis and past medical history was filled in. Afterwards, skin prick test with aeroallergens, pulmonary function and methacholine bronchial provocation tests and serum sampling for total IgE level determinations were carried out. Bronchial hyperresponsiveness to methacholine was significantly more common in the mothers of non-atopic children compared to those of atopic ones, although no significant difference was observed in the skin prick test reactivity, pulmonary function test parameters and serum IgE levels. Questionnaire data revealed that the presence of asthmatic symptoms such as wheezing and phlegm and doctor-diagnosed asthma were more common in the mothers of non-atopic children. Meanwhile, asthmatic symptoms were also found to be significantly more common in fathers of non-atopic children. Logistic regression analyses revealed that maternal PC(20) was the only predictive factor for the risk of displaying non-allergic asthma in children. The results demonstrate that among the risk factors studied, maternal bronchial hyperreactivity was associated with the development of asthma in non-atopic children.

Elevated CCR6+ CD4+ T lymphocytes in tissue compared with blood and induction of CCL20 during the asthmatic late response

CCR6 is expressed by multiple leucocyte subsets, including peripheral blood memory T cells, and mouse models implicate a role for this receptor in diverse inflammatory responses that include allergic airway disorders, inflammatory bowel disease and autoimmune encephalitis. In order to study the role of CCR6 in humans, we have investigated the patterns of CCR6 expression and function on T cells from the peripheral blood, skin, nose and lung, in health and in allergic disease. Results show that CCR6 was expressed consistently on a higher proportion of tissue versus peripheral blood-derived CD4+ T cells (P < 0.01). CCR6 was expressed predominantly on CD4+ compared with CD8+ cells in both blood- and tissue-derived T cells (P < 0.001). The number of cells showing CCR6 expression was not proportionally greater in peripheral blood or nasal mucosal T cells of subjects with symptomatic allergic rhinitis. CCR6+ cells demonstrated enhanced functional responses to CCL20 and CCL20 was increased in bronchoalveolar lavage fluid of asthmatics following endobronchial allergen provocation (P < 0.05). Thus, CCR6 may be important in the regulation of T cell recruitment to tissue and up-regulation of CCL20 expression may contribute to the recruitment and/or retention of effector T cells in allergic asthma.

Sinonasal pathology in nonallergic asthma and COPD: 'united airway disease' beyond the scope of allergy

BACKGROUND

In contrast to the epidemiological and clinical association between allergic rhinitis and asthma, upper airway inflammation is less characterized in patients with nonatopic asthma and virtually unexplored in chronic obstructive pulmonary disease (COPD). Here, sinonasal pathology is studied in patients with allergic asthma, nonallergic asthma and COPD.

METHODS

Ninety patients with stable bronchial disease were included in the study, of which 35 were diagnosed with allergic asthma, 24 with nonallergic asthma and 31 with COPD. Concurrently, 61 control subjects without pulmonary disease were included and matched for age and smoking habits respectively with the asthma and the COPD group. Sinonasal symptoms were evaluated on a visual analogue scale and rhinosinusitis-related impairment of quality of life was assessed with the sino-nasal outcome test-22 (SNOT-22) questionnaire. Nasal mucosal abnormalities were quantified with nasal endoscopy and nasal secretions collected for measuring inflammatory mediators.

RESULTS

Allergic asthmatics, nonallergic asthmatics and COPD patients reported more nasal symptoms than their respective control subjects, had a higher SNOT-22 score and presented more mucosal abnormalities in the nose. Nasal secretions of both allergic and nonallergic asthmatics contained higher levels of eotaxin, G-CSF, IFN-gamma and MCP-1 than controls. Allergic asthmatics had higher nasal IP-10 levels as well. COPD-patients had higher nasal levels of eotaxin, G-CSF and IFN-gamma than controls.

CONCLUSION

Patients with allergic and nonallergic asthma and COPD show increased nasal symptoms and more nasal inflammation. Hence, our data confirm the 'united airways' concept to be beyond the scope of allergic asthma.

Novel clinical and serological aspects in non-allergic asthma

BACKGROUND

We have recently observed that skin reactivity to autologous serum injection is common in patients with non-allergic asthma. However, clinical significance of skin reactivity to autologous serum remains to be defined.

OBJECTIVE

To evaluate the possible relation between skin reactivity to autologous serum and clinical and laboratory characteristics in a series of patients with non-allergic asthma.

METHODS

Fifty-five patients with non-allergic asthma underwent in vivo autologous serum skin test (ASST) and in vitro basophil histamine release assay using basophils from a normal donor. Clinical and laboratory characteristics including peripheral blood eosinophilia, antinuclear antibodies and total IgE concentration were evaluated. As control, ASST was performed in 10 allergic asthmatic patients, 10 patients with allergic rhinitis and 10 normal subjects.

RESULTS

ASST was positive in 29/55 non-allergic asthmatics (53%), whereas it was negative in all 30 control subjects (P<0.001). The sera of 6 out of 51 patients induced in vitro histamine release from autologous basophils. The sera from two patients induced histamine release from membrane IgE-stripped basophils. A significant predominance of female sex (83%) and a high incidence of antinuclear antibodies (ANA) positivity (55%) were found among ASST-positive patients.

CONCLUSION

These findings indicate that ASST is positive in about half patients with non-allergic asthma and that a proportion of patients (16%) has functional evidence of circulating histamine-releasing factors. In addition, predominance of female sex and frequent ANA positivity are in line with an autoimmune basis of non-allergic asthma.

Novel cytokine peptide-based vaccines: an interleukin-4 vaccine suppresses airway allergic responses in mice

BACKGROUND

Monoclonal antibodies or soluble receptors have been used to block over-produced endogenous cytokines. However, they have disadvantages of short half-lives, high costs, and possible adverse effects. Using interleukin (IL)-4 as a model target, we sought to develop a novel therapeutic strategy by constructing an IL-4 peptide-based vaccine for blocking IL-4 on a persistent basis, and to evaluate its efficacy in a mouse model of asthma.

METHODS

A peptide was selected by antigenic prediction and structure analysis of IL-4/receptor complex. The vaccine was constructed by employing truncated hepatitis B core antigen as carrier with the peptide inserted using gene engineering methods. It was then expressed, purified and identified. Prior to intraperitoneal sensitization and intranasal challenge with ovalbumin, mice were subcutaneously immunized three times with the vaccine, or the carrier or saline as controls. Serum antibodies, inflammatory cells in bronchoalveolar lavage fluids (BALF), lung histology, and responsiveness to inhaled methacholine were analyzed.

RESULTS

The vaccine presented as virus-like particles and reacted to polyclonal anti-IL-4 in Western blotting. Vaccinated mice produced high titers of IgG to IL-4. Serum ovalbumin-specific IgE, eosinophil accumulation in BALF, goblet cell hyperplasia, tissue inflammation and methacoline-induced respiratory responses were markedly suppressed in vaccinated mice with statistical significance, as compared with those in the control groups.

CONCLUSIONS

Administration of this novel IL-4 vaccine led to an overall decrease in the development of airway allergic inflammatory responses. The results indicate that cytokine peptide-based vaccines hold potential for treatment of asthma and, by extension, other diseases where over-expressed cytokines play a pivotal role in pathogenesis.

Local mucosal immunoglobulin E production: does allergy exist in non-allergic rhinitis?

In this review, we critically evaluate the evidence for local IgE production in allergic rhinitis mucosa and the concept of local allergy in non-atopic idiopathic rhinitis. Significantly, fewer studies have focused on the disease pathways associated with non-allergic rhinitis compared with their allergic counterparts. Recently, there's been a revival of the hypothesis concerning the existence of local tissue-specific allergic disease confined to the nasal mucosa of some systemically non-atopic rhinitis subjects. Providing the evidence for local mucosal IgE production in allergic rhinitis is a pre-requisite to reviewing its existence in non-allergic rhinitis. In addition, practical and theoretical approaches useful in the detection of allergy in non-allergic rhinitis will be discussed. Furthermore, successful therapeutic regimens used in the treatment of non-allergic rhinitis will be examined as these could provide an insight into the underlying pathophysiology of this common but poorly understood disease.

Chemokines and their receptors as potential targets for the treatment of asthma

Asthma is a chronic and sometimes fatal disease, which affects people of all ages throughout the world. Important hallmarks of asthma are airway inflammation and remodelling, with associated bronchial hyperresponsiveness and variable airflow obstruction. These features are orchestrated by cells of both the innate (eosinophils, neutrophils and mast cells) and the adaptive (T(H)2 T cells) immune system, in concert with structural airway cells. Chemokines are important for the recruitment of both immune and structural cells to the lung, and also for their microlocalisation within the lung tissue. Specific blockade of the responses elicited by chemokines and chemokine receptors responsible for the pathological migration of airway cells could therefore be of great therapeutic interest for the treatment of asthma.

The reclassification of asthma based on subphenotypes

PURPOSE OF REVIEW

Despite asthma being widely regarded as a heterogeneous disease, a consensus for an accurate system of classification has not been agreed. Recent studies have suggested that the recognition of subphenotypes of asthma based on the pattern of airway inflammation may be particularly useful in increasing our understanding of the disease. The present review discusses the important literature in this field, placing current work in its historical context.

RECENT FINDINGS

The use of noninvasive markers of airway inflammation has suggested the presence of four distinct phenotypes: eosinophilic, neutrophilic, mixed inflammatory and paucigranulocytic asthma. Recent studies suggest that these subgroups may differ in their aetiology, immunopathology and response to treatment. Several studies have focused on refractory asthma as a distinct phenotype with evidence of a more distal pattern of airway inflammation and of upregulation of the tumour necrosis factor-alpha axis. Finally, novel treatment approaches targeted at specific patterns of airway inflammation are emerging, making an appreciation of subphenotypes particularly relevant.

SUMMARY

The present review will discuss limitations to current classification systems, identify key current studies based on identifying inflammatory subphenotypes and provide suggestions for a novel approach that may further improve our understanding in this area.

Class switch recombination to IgE in the bronchial mucosa of atopic and nonatopic patients with asthma

BACKGROUND

Class switching from IgM/IgG/IgA to IgE is required for B cells to express IgE. This requires class switch recombination in the Ig heavy-chain gene locus. It is generally believed that class switch recombination occurs in lymphoid tissue, but it was recently shown that class switching to IgE occurs in the nasal mucosa in allergic rhinitis.

OBJECTIVE

We aimed to determine whether class switching to IgE also occurs in the bronchial mucosa in asthma, and to look for possible differences/similarities between atopic and nonatopic asthma.

METHODS

We have used RT-PCR to examine epsilon immunoglobulin heavy-chain germline gene transcripts (GLTs; epsilonGLTs), epsilon circle transcripts (CTs; Ivarepsilon-Cmu CT or Ivarepsilon-Cgamma CT), and mRNA encoding the heavy chain of IgE (epsilon mRNA) and activation-induced cytidine deaminase (AID) in bronchial biopsies from atopic patients with asthma, nonatopic patients with asthma, atopic controls without asthma, and nonatopic controls without asthma (10 subjects in each group).

RESULTS

The varepsilonGLT and AID mRNA were detectable in the bronchial mucosa of subjects in all 4 groups. In contrast, Iepsilon-Cmu CT, Ivarepsilon-Cgamma CT, and epsilon mRNA were detectable in the bronchial mucosa of the majority of both atopic and nonatopic patients with asthma, but rarely in the controls without asthma.

CONCLUSION

The bronchial mucosa is a site primed in all individuals for class switching to IgE, because of B-cell expression of epsilonGLT and AID mRNA. However, it is only in patients with asthma, regardless of atopic status, that class switching to IgE occurs.

CLINICAL IMPLICATIONS

Our findings reveal prospects for local targeting of the Ig class switch mechanism in the management of atopic and nonatopic asthma.

Pathological features and inhaled corticosteroid response of eosinophilic and non-eosinophilic asthma

BACKGROUND

Non-eosinophilic asthma is a potentially important clinicopathological phenotype since there is evidence that it responds poorly to inhaled corticosteroid therapy. However, little is known about the underlying airway immunopathology and there are no data from placebo-controlled studies examining the effect of inhaled corticosteroids.

METHODS

Airway immunopathology was investigated using induced sputum, bronchial biopsies, bronchial wash and bronchoalveolar lavage in 12 patients with symptomatic eosinophilic asthma, 11 patients with non-eosinophilic asthma and 10 healthy controls. The patients with non-eosinophilic asthma and 6 different patients with eosinophilic asthma entered a randomised, double-blind, placebo-controlled crossover study in which the effects of inhaled mometasone 400 microg once daily for 8 weeks on airway responsiveness and asthma quality of life were investigated.

RESULTS

Patients with non-eosinophilic asthma had absence of eosinophils in the mucosa (median 4.4 cells/mm(2) vs 23 cells/mm(2) in eosinophilic asthma and 0 cells/mm(2) in normal controls; p = 0.03) and normal subepithelial layer thickness (5.8 microm vs 10.3 microm in eosinophilic asthma and 5.1 microm in controls, p = 0.002). Non-eosinophilic and eosinophilic asthma groups had increased mast cell numbers in the airway smooth muscle compared with normal controls (9 vs 8 vs 0 cells/mm(2), p = 0.016). Compared with placebo, 8 weeks of treatment with inhaled mometasone led to less improvement in methacholine PC(20) (0.5 vs 5.5 doubling concentrations, 95% CI of difference 1.1 to 9.1; p = 0.018) and asthma quality of life (0.2 vs 1.0 points, 95% CI of difference 0.27 to 1.43; p = 0.008).

CONCLUSIONS

Non-eosinophilic asthma represents a pathologically distinct disease phenotype which is characterised by the absence of airway eosinophilia, normal subepithelial layer thickness and a poor short-term response to treatment with inhaled corticosteroids.

Chemokine receptor expression on allergen-specific T cells in asthma and allergic bronchopulmonary aspergillosis

BACKGROUND

Allergic bronchopulmonary aspergillosis (ABPA) is a rare variant of severe asthma resulting from hypersensitivity to Aspergillus fumigatus (Asp f) present in the airways.

AIMS OF THE STUDY

We analyzed the expression of a panel of six chemokine receptors (CCR3, CCR4, CCR8, CCR5, CXCR3 and CXCR4) on total blood CD4(+) T cells and Asp f-specific-T cells in ABPA patients. We hypothesized that chemokine receptor pattern on T cells differs between ABPA patients, non-ABPA allergic asthmatics sensitized to Dermatophagoides pteronyssinus (Der p) or Phleum pratense (Phl p) and healthy controls.

METHODS

We used the fluorescent dye PKH26, a membrane bound marker, to identify accumulated proliferating (cell-sorted PKH26(low)) CD4(+) T cells in response to allergens (Asp f, Der p, Phl p) or recall antigens (PPD and TT). Chemokine receptor expression was analyzed by flow cytometry on proliferating CD3(+) CD4(+) PKH26(low) cells.

RESULTS

Stimulation of CD4(+) T cells with the relevant allergen resulted in different patterns of chemokine receptor expression in ABPA and non-ABPA allergic asthmatics. Upon Asp f exposure, proliferating CD4(+) T cells from ABPA patients down-regulated the expression of CCR4 and CXCR3 while CCR4 and CXCR3 were up-regulated in allergen-specific T cells from non-ABPA allergic asthmatics. Considering each group of patients, the pattern of chemokine receptors expressed on proliferating allergen-specific CD4(+) T cells was similar to that expressed by recall antigen-specific T cells.

CONCLUSIONS

The down-regulation of CCR4 and CXCR3 after allergen exposure in Asp f-specific T cells seems to be a characteristic feature of ABPA patients and requires further evaluation.

Sublingual immunotherapy in children modulates allergen-induced in vitro expression of cytokine mRNA in PBMC

BACKGROUND

During subcutaneous immunotherapy (SCIT), there is a local mucosal shift from Th2 to Th1 type cytokine predominance and downregulation of interleukin (IL)-5 and eosinophilia. According to recent studies IL-10- and transforming growth factor (TGF)-beta-induced tolerance is another key phenomenon in SCIT. Few data to date is available on mechanisms and roles of these cytokines in sublingual immunotherapy (SLIT).

SCOPE

This study was undertaken to analyse the allergen-induced in vitro mRNA expression of IL-4, IL-5, IL-10, TGF-beta and interferon (IFN)-gamma during SLIT in peripheral blood mononuclear cells (PBMC) of children with allergic rhinitis (AR).

METHODS

Ten patients with AR undergoing pollen SLIT with a weekly dose of 200,000 SQ-U, 10 with a weekly dose of 24,000 SQ-U of glycerinated mixture of Betula verrucosa, Corylus avellana and Alnus glutinosa and 10 with placebo were included in the study. Peripheral blood mononuclear cell samples were collected and stimulated with pollen allergen extract prior to the treatment, after 1 and 2 years of the treatment. The cytokine mRNA expression was assessed using kinetic real time reverse transcription polymerase chain reaction (RT-PCR; TaqMan).

RESULTS

The in vitro allergen-induced mRNA expression of IL-5 by PBMC in the placebo group at 1 (P = 0.0065) and 2 (P = 0.013) years of therapy were increased in comparison with the highest dose. The expression of IL-10 mRNA was increased in the highest dose group (P = 0.0016) and the lower dose group (P = 0.034) at 2 years of therapy when compared with placebo. The change in the expression of allergen-induced TGF-beta had an inversed correlation with the change of IL-5 (r = -0.38, P = 0.036) and positive correlation with the change of IL-10 (r = 0.58, P = 0.0019).

CONCLUSIONS

Sublingual immunotherapy induced a dose-dependent systemic allergen-specific immunological response in children with AR. During high-dose SLIT, there was activation of regulatory cytokine IL-10 and an inhibitory effect on IL-5 expression increase that was associated with TGF-beta.

Immunoglobulin E: role in asthma and allergic disease: lessons from the clinic

The role of immunoglobulin E (IgE) in allergic asthmatic disease is well established. Allergen-specific IgE binds to its cognate receptors, thus triggering a series of cellular events. These events include presentation of antigen by dendritic cells and the degranulation of mast cells and basophils to release numerous factors that play an integral part in potentiating the disease symptoms. Studies in the mouse indicate that a reduction in IgE levels could lead to significant attenuation of the allergic inflammatory response associated with diseases such as asthma, making IgE a target for the development of new therapeutic agents. Omalizumab (Xolair), a recombinant humanised monoclonal anti-IgE antibody that blocks the interaction of IgE with its receptors, is the first anti-IgE agent to undergo clinical development. Several clinical studies have been performed in adults and children with moderate-to-severe allergic asthma to evaluate the efficacy and safety of this agent, but which have also enabled an insight into the role of IgE in human disease. IgE plays a significant role in a number of allergic conditions including allergic rhinitis and allergies to various substances. Recent data suggests that local IgE production may occur in mucosal tissues and that locally significant concentrations of IgE, not reflected by serum IgE concentrations, indicate that it may play a role in non-atopic as well as atopic disease.

Germinal-centre reactions in allergic inflammation

Primary and secondary immune responses in the germinal centres of lymphoid organs have been studied in the past. There is now compelling evidence of a third stage in the immune response, in 'tertiary lymphoid organs' that develop at sites of chronic inflammation in response to persistent local antigen challenge. Germinal-centre-like reactions are well-documented in the target organs of autoimmune diseases. Here, we review recent evidence that they also occur at sites of allergic inflammation.

Asthma: defining of the persistent adult phenotypes

The common disease asthma is probably not a single disease, but rather a complex of multiple, separate syndromes that overlap. Although clinicians have recognised these different phenotypes for many years, they have remained poorly characterised, with little known about the underlying pathobiology contributing to them. Development of targeted therapies for asthma, and phenotype-specific clinical trials have raised interest in these phenotypes. Improved understanding of these phenotypes in complex diseases such as asthma will also improve our ability to link specific genotypes to their associated disease, which should help development of biomarkers. However, there is no standardised method to define asthma phenotypes. This Review analyses some of the methods that have been used to define asthma phenotypes and proposes an integrated method of classification to improve our understanding of these phenotypes.

Effect of thymoquinone on cyclooxygenase expression and prostaglandin production in a mouse model of allergic airway inflammation

Prostaglandins (PGs) are potent proinflammatory mediators generated through arachidonic acid metabolism by cyclooxygenase-1 and -2 (COX-1 and COX-2) in response to different stimuli and play an important role in modulating the inflammatory responses in a number of conditions, including allergic airway inflammation. Thymoquinone (TQ) is the main active constituent of the volatile oil extract of Nigella sativa seeds and has been reported to have anti-inflammatory properties. We examined the effect of TQ on the in vivo production of PGs and lung inflammation in a mouse model of allergic airway inflammation. Mice sensitized and challenged through the airways with ovalbumin (OVA) exhibited a significant increase in PGD2 and PGE2 production in the airways. The inflammatory response was characterized by an increase in the inflammatory cell numbers and Th2 cytokine levels in the bronchoalveolar lavage (BAL) fluid, lung airway eosinophilia and goblet cell hyperplasia, as well as the induction of COX-2 protein expression in the lung. Intraperitoneal injection of TQ for 5 days before the first OVA challenge attenuated airway inflammation as demonstrated by the significant decrease in Th2 cytokines, lung eosinophilia, and goblet cell hyperplasia. This attenuation of airway inflammation was concomitant to the inhibition of COX-2 protein expression and PGD2 production. However, TQ had a slight inhibitory effect on COX-1 expression and PGE2 production. These findings suggest that TQ has an anti-inflammatory effect during the allergic response in the lung through the inhibition of PGD2 synthesis and Th2-driven immune response.

[IgE and respiratory disease]

INTRODUCTION

IgE is known to provide the biological basis for allergy and immediate hypersensitivity. However, recent data provide some evidence that IgE responses are involved in other inflammatory processes apart from allergy, including several respiratory diseases.

STATE OF THE ART

IgE binds to mast cells and basophils but also to other inflammatory cells, which are involved in non-allergic processes. IgE has a role in antigen presentation and is implicated in a number of other immune mechanisms. In the airways, IgE plays an important role in bronchial hyperactivity, even in the absence of an allergen. Epidemiological studies have demonstrated that IgE response is related not only to allergy but also to asthma symptoms, in the presence or absence of atopy, as well as exposure to cigarette smoke. IgE response is altered in several respiratory diseases including extrinsic and intrinsic asthma and allergic bronchopulmonary aspergillosis.

CONCLUSION AND PERSPECTIVES

Since anti-IgE monoclonal antibodies are now available for administration to humans, a better understanding of the IgE response may allow the identification of novel therapeutic targets in the field of respiratory disease.

Eotaxin-3 and a uniquely conserved gene-expression profile in eosinophilic esophagitis

Eosinophilic esophagitis (EE) is an emerging disorder with a poorly understood pathogenesis. In order to define disease mechanisms, we took an empirical approach analyzing esophageal tissue by a genome-wide microarray expression analysis. EE patients had a striking transcript signature involving 1% of the human genome that was remarkably conserved across sex, age, and allergic status and was distinct from that associated with non-EE chronic esophagitis. Notably, the gene encoding the eosinophil-specific chemoattractant eotaxin-3 (also known as CCL26) was the most highly induced gene in EE patients compared with its expression level in healthy individuals. Esophageal eotaxin-3 mRNA and protein levels strongly correlated with tissue eosinophilia and mastocytosis. Furthermore, a single-nucleotide polymorphism in the human eotaxin-3 gene was associated with disease susceptibility. Finally, mice deficient in the eotaxin receptor (also known as CCR3) were protected from experimental EE. These results implicate eotaxin-3 as a critical effector molecule for EE and provide insight into disease pathogenesis.

Protective effect of the DNA vaccine encoding the major house dust mite allergens on allergic inflammation in the murine model of house dust mite allergy

Background

Vaccination with naked DNA encoding antigen induces cellular and humoral immunity characterized by the activation of specific Th1 cells.

Objective

To evaluate the effects of vaccination with mixed naked DNA plasmids encoding Der p 1, Der p 2, Der p 3, Der f 1, Der f 2, and Der f 3, the major house dust mite allergens on the allergic inflammation to the whole house dust mites (HDM) crude extract.

Methods

Three hundred micrograms of these gene mixtures were injected into muscle of BALB/c mice. Control mice were injected with the pcDNA 3.1 blank vector. After 3 weeks, the mice were actively sensitized and inhaled with the whole house dust mite extract intranasally.

Results

The vaccinated mice showed a significantly decreased synthesis of total and HDM-specific IgE compared with controls. Analysis of the cytokine profile of lymphocytes after challenge with HDM crude extract revealed that mRNA expression of interferon-γ was higher in the vaccinated mice than in the controls. Reduced infiltration of inflammatory cells and the prominent infiltration of CD8+ T cells were observed in histology of lung tissue from the vaccinated mice.

Conclusion

Vaccination with DNA encoding the major house dust mite allergens provides a promising approach for treating allergic responses to whole house dust mite allergens.

Cytokine production from sputum cells in eosinophilic versus non-eosinophilic asthmatics

The inflammatory pathways involved in asthma are more complex than the sole Th2-mediated eosinophilic airway inflammation. Different phenotypes of asthma have been recently highlighted and are probably underlied by different immunological profiles. The aim of the study was to assess cytokine production from sputum cells in eosinophilic versus non-eosinophilic asthmatics. Induced sputum was obtained from 48 consecutive stable mild to moderate asthmatics (20 eosinophilic asthmatics, 28 non-eosinophilic asthmatics) and 31 healthy subjects. Cytokine released from sputum cells were measured by a home-made two-step sandwich immunoassay. Cytokines investigated were interleukin (IL)-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma. Sputum cells from eosinophilic asthmatics produced more IL-4 than those from both healthy subjects (P < 0.05) and non-eosinophilic asthmatics (P < 0.05). Conversely, sputum cells from eosinophilic asthma were found to release lower amounts of TNF-alpha than those from healthy subjects (P < 0.05). The group of non-eosinophilic asthmatics did not distinguish from healthy subjects with respect to any cytokines measured. Sputum cells from asthmatics exhibiting eosinophilic airway inflammation release more IL-4 and less TNF-alpha than those of healthy subjects. By contrast, non-eosinophilic asthmatics did not distinguish from healthy subjects by abnormal cytokine release from their sputum cells.

Evaluation of airway inflammation by quantitative Th1/Th2 cytokine mRNA measurement in sputum of asthma patients

BACKGROUND

Asthma is a chronic inflammatory disorder of the airways driven by T cell activation. Th2 cells and their cytokines are thought to play a role in the pathophysiology of allergic as well as non-allergic asthma.

METHODS

Airway cells were obtained by sputum induction from 15 healthy and 39 asthmatic individuals and the airway T cell cytokine profiles (interleukin (IL)-4, IL-5, IL-13, IL-10 and interferon (IFN)-gamma) at the mRNA level were studied by real time RT-PCR.

RESULTS

Asthma patients had increased expression of IL-5 (p = 0.001) and IL-13 (p = 0.03) mRNA in sputum compared with non-asthmatic controls. IL-4 mRNA and IFN-gamma mRNA were detectable in the sputum of 44% and 21% of patients, respectively, but not in controls. Sputum IL-10 mRNA levels did not differ significantly between patients and controls. Sputum mRNA expression levels of IL-4, IL-5, and IL-13 were significantly correlated with the percentage of eosinophils and were higher in subjects with allergic asthma than in those with non-allergic asthma (p = 0.03, p = 0.02 and p = 0.0002, respectively); they did not differ between mild asthmatic subjects and those with moderate to severe asthma. In contrast, IFN-gamma mRNA expression was higher in non-allergic than in allergic patients (p = 0.04) and higher in patients with moderate to severe asthma than in those with mild asthma (p<0.01). Sputum IL-5 mRNA levels (but not the other cytokine mRNA levels) were also correlated with exhaled nitric oxide (eNO) and with bronchial hyperreactivity expressed as the histamine concentration resulting in a 20% decrease in forced expiratory volume in 1 second.

CONCLUSION

Real time RT-PCR analysis of mRNA in induced sputum confirms a predominance of Th2 cytokines in both allergic and non-allergic asthma. IL-5 levels reflect eosinophil infiltration as well as eNO levels and hyperreactivity, and levels of the Th1 cytokine IFN-gamma indicate asthma severity. The technique is a promising tool for use in further studies of asthma severity and disease activity.

Airway generation-specific differences in the spatial distribution of immune cells and cytokines in allergen-challenged rhesus monkeys

BACKGROUND

Accumulation of immune cell populations and their cytokine products within tracheobronchial airways contributes to the pathogenesis of allergic asthma. It has been postulated that peripheral regions of the lung play a more significant role than proximal airways with regard to inflammatory events and airflow obstruction.

OBJECTIVE

To determine whether immune cell populations and associated cytokines are uniformly distributed throughout the conducting airway tree in a non-human primate model of allergic asthma.

METHODS

We used a stereologic approach with a stratified sampling scheme to measure the volume density of immune cells within the epithelium and interstitium of trachea and 4-5 intrapulmonary airway generations from house dust mite (HDM) (Dermatophagoides farinae)-challenged adult monkeys. In conjunction with immune cell distribution profiles, mRNA levels for 21 cytokines/chemokines and three chemokine receptors were evaluated at four different airway generations from microdissected lungs.

RESULTS

In HDM-challenged monkeys, the volume of CD1a+ dendritic cells, CD4+ T helper lymphocytes, CD25+ cells, IgE+ cells, eosinophils, and proliferating cells were significantly increased within airways. All five immune cell types accumulated within airways in unique patterns of distribution, suggesting compartmentalized responses with regard to trafficking. Although cytokine mRNA levels were elevated throughout the conducting airway tree of HDM-challenged animals, the distal airways (terminal and respiratory bronchioles) exhibited the most pronounced up-regulation.

CONCLUSION

These findings demonstrate that key effector immune cell populations and cytokines associated with asthma differentially accumulate within distinct regions and compartments of tracheobronchial airways from allergen-challenged primates.