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Asthma is characterized by eosinophilic airway inflammation and remodeling of the airway wall. Features of airway remodeling include increased airway smooth muscle (ASM) mass. However, little is known about the interaction between inflammatory eosinophils and ASM cells. In this study, we investigated the effect of eosinophils on ASM cell proliferation. Eosinophils were isolated from peripheral blood of mild asthmatics and non-asthmatic subjects and co-cultured with human primary ASM cells. ASM proliferation was estimated using Ki-67 expression assay. The expression of extracellular matrix (ECM) mRNA in ASM cells was measured using quantitative real-time PCR. The role of eosinophil derived Cysteinyl Leukotrienes (CysLTs) in enhancing ASM proliferation was estimated by measuring the release of leukotrienes from eosinophils upon their direct contact with ASM cells using ELISA. This role was confirmed either by blocking eosinophil-ASM contact or co-culturing them in the presence of leukotrienes antagonist. ASM cells co-cultured with eosinophils, isolated from asthmatics, but not non-asthmatics, had a significantly higher rate of proliferation compared to controls. This increase in ASM proliferation was independent of their release of ECM proteins but dependent upon eosinophils release of CysLTs. Eosinophil-ASM cell to cell contact was required for CysLTs release. Preventing eosinophil contact with ASM cells using anti-adhesion molecules antibodies, or blocking the activity of eosinophil derived CysLTs using montelukast inhibited ASM proliferation. Our results indicated that eosinophils contribute to airway remodeling during asthma by enhancing ASM cell proliferation and hence increasing ASM mass. Direct contact of eosinophils with ASM cells triggers their release of CysLTs which enhance ASM proliferation. Eosinophils, and their binding to ASM cells, constitute a potential therapeutic target to interfere with the series of biological events leading to airway remodeling and Asthma.

Background: Subepithelial fibrosis is one of the most critical structural changes affecting bronchial airway function during asthma. Eosinophils have been shown to contribute to the production of pro-fibrotic cytokines, TGF-β and IL-11, however, the mechanism regulating this process is not fully understood., Objective: In this report, we investigated whether cytokines associated with inflammation during asthma may induce eosinophils to produce pro-fibrotic cytokines., Methods: Eosinophils were isolated from peripheral blood of 10 asthmatics and 10 normal control subjects. Eosinophils were stimulated with Th1, Th2 and Th17 cytokines and the production of TGF-β and IL-11 was determined using real time PCR and ELISA assays., Results: The basal expression levels of eosinophil derived TGF-β and IL-11 cytokines were comparable between asthmatic and healthy individuals. Stimulating eosinophils with Th1 and Th2 cytokines did not induce expression of pro-fibrotic cytokines. However, stimulating eosinophils with Th17 cytokines resulted in the enhancement of TGF-β and IL-11 expression in asthmatic but not healthy individuals. This effect of IL-17 on eosinophils was dependent on p38 MAPK activation as inhibiting the phosphorylation of p38 MAPK, but not other kinases, inhibited IL-17 induced pro-fibrotic cytokine release., Conclusions: Th17 cytokines might contribute to airway fibrosis during asthma by enhancing production of eosinophil derived pro-fibrotic cytokines. Preventing the release of pro-fibrotic cytokines by blocking the effect of Th17 cytokines on eosinophils may prove to be beneficial in controlling fibrosis for disorders with IL-17 driven inflammation such as allergic and autoimmune diseases.

Background: Airway inflammation assessed by bronchial biopsies demonstrates distinct eosinophilic and noneosinophilic phenotypes in severe asthma, but their relationship to other biomarkers of disease (induced sputum and nitric oxide [NO]) is not clear., Objectives: We sought to compare airway inflammation using noninvasive (induced sputum, exhaled NO), and invasive (bronchial biopsies) methods in moderate and severe asthma and to assess whether induced sputum and exhaled NO would allow the identification of eosinophilic and noneosinophilic phenotypes in severe asthma., Methods: We performed a cross-sectional study of 32 subjects with severe asthma and 35 subjects with moderate asthma, from whom we obtained bronchial biopsies, induced sputum, and exhaled NO measurements., Results: Among subjects with severe asthma, we identified eosinophilic and noneosinophilic phenotypes using both bronchial biopsies and sputum cell counts. However, the vast majority of subjects with high sputum eosinophil counts did not have high mucosal eosinophil counts. Exhaled NO was increased in the eosinophilic phenotype as judged from bronchial biopsy findings, but not on the basis of induced sputum. Subjects with high sputum eosinophil counts experienced more asthma exacerbations than the subjects with low sputum eosinophil counts. In contrast, we did not find any differences in the clinical characteristics between eosinophilic and noneosinophilic phenotypes that were identified by bronchial biopsies., Conclusion: The use of sputum cell counts allowed the identification of a subgroup of subjects with severe asthma who were at risk of more frequent asthma exacerbations., Clinical Implications: Monitoring sputum eosinophil counts in subjects with severe asthma may allow identifying the subjects with the greatest disease activity.

Bullous pemphigoid is an inflammatory disease of the skin associated with eosinophil infiltration and the presence of high levels of Th2 cytokines in the associated blister fluid. Little is known about the contribution of chemokines in this disease. We found that eotaxin and MCP-4 mRNA and immunoreactivity were expressed in all biopsies of BP patients and were mainly localized to the epidermis and eosinophils. The expression of eotaxin and MCP-4 was enhanced in eosinophils following IL-5 treatment. Subsequent stimulation of IL-5-primed eosinophils with Ig-immune complexes, results in increase secretion of eotaxin and MCP-4 in the supernatants. Using immunostaining, these two chemokines were localized to the granules of eosinophils. BF was found to contain chemotactic activity for eosinophils, neutrophils and T cells. The chemotactic effect of BF for eosinophils was more effective when eosinophils were stimulated with IL-5 or IL-4. We also found that the levels of Th(2)-associated chemokines (eotaxin and MCP-4) in BF were significantly higher than the Th(1)-associated chemokines (MIP-1beta and IP-10). This was consistent with the increased chemotaxis of polarized Th(2) cells toward BF, when compared to Th(1)-differentiated T cells. Our results support the involvement of Th(2)-associated chemokines in the pathogenesis of BP disease.

Background: IL-17E is a new TH2 cytokine that promotes airway eosinophilia in mice. IL-17E proinflammatory activity has been proposed to involve induction of cytokine and chemokine production. Recruitment of inflammatory cells may be mediated by tissue-resident cells., Objective: This study aimed to evaluate whether fibroblasts represent a target of IL-17E for the production of eosinophil active mediators in the lung., Methods: Expression of IL-17B receptor (IL-17BR), a receptor for IL-17E, was evaluated by immunofluorescent staining, Western blot, and real-time PCR in human primary lung fibroblasts. Mediator production was analyzed by using real-time PCR and ELISA after stimulation of fibroblasts with IL-17E alone or in combination with TNF-alpha and TGF-beta1. Expression of IL-17E and of eosinophil major basic protein was evaluated by immunohistochemistry in bronchial biopsies from subjects with asthma., Results: Human primary lung fibroblasts constitutively expressed IL-17BR. IL-17BR mRNA levels were increased in cells stimulated with TNF-alpha and decreased with TGF-beta1. IL-17E slightly upregulated CC chemokine ligand (CCL)-5, CCL-11, GM-CSF, and CXC chemokine ligand (CXCL)-8 mRNA in fibroblasts. Moreover, IL-17E and TNF-alpha synergistically induced GM-CSF and CXCL-8 mRNA. IL-17E also potentiated the upregulation of CXCL-8 transcripts observed with TGF-beta1. In contrast, TGF-beta1 decreased IL-17E-induced CCL-11 mRNA. The capacity of IL-17E to enhance GM-CSF and CXCL-8 responses to TNF-alpha was accompanied by production and secretion of both proteins by lung fibroblasts. Finally, IL-17E was detected in asthma in eosinophil-infiltrated bronchial submucosa., Conclusion: IL-17E may contribute to the induction and maintenance of eosinophilic inflammation in the airways by acting on lung fibroblasts. This study supports a role for IL-17E in asthma pathophysiology.

Prostaglandin (PG) D2 is an arachidonic acid metabolite that is released by allergen-stimulated mast cells. It is a potent in vitro chemoattractant for human eosinophils, acting through the DP2 receptor/chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). Furthermore, there is in vivo evidence that PGD2 contributes to allergen-induced pulmonary eosinophilia via its classic DP1 receptor. The PGD2-derived product 15-deoxy-Delta12,14-PGJ2 is widely used as a peroxisome proliferator-activated receptor gamma agonist and has been shown to have anti-inflammatory properties. However, this substance can also activate eosinophils in vitro through the DP2 receptor. The objectives of the present study were to determine whether PGD2 and 15-deoxy-Delta12,14-PGJ2 can induce pulmonary eosinophilia, and, if so, to examine the abilities of selective DP1 and DP2 receptor agonists to induce this response. Brown Norway rats were treated by intratracheal instillation of PGs. Vehicle and 5-oxo-6,8,11,14-eicosatetraenoic acid were used as negative and positive controls, respectively. Lung eosinophils were identified by immunostaining of lung sections with an antibody to major basic protein. Both PGD2 and 15-deoxy-Delta12,14-PGJ2 induced robust eosinophilic responses that were apparent by 12 h and persisted for at least 48 h. Two selective DP2 receptor agonists, 15R-methyl-PGD2 and 13-14-dihydro-15-keto-PGD2, induced similar responses, the former being more potent than PGD2, whereas the latter was less potent. The selective DP1 receptor agonist BW245C [(4S)-(3-[(3R,S)-3-cyclohexyl-3-hydroxypropyl]-2,5-dioxo)-4-imidazolidineheptanoic acid] was completely inactive. We conclude that PGD2 and 15-deoxy-Delta12,14-PGJ2 induce eosinophil infiltration into the lungs through the DP2 receptor. The potent in vitro DP2 receptor agonist 15R-methyl-PGD2 is also very active in vivo and should be a useful tool in examining the role of this receptor.

Background: Cytokines and chemokines have been implicated in the pathogenesis of asthma. Inhaled corticosteroids have been shown to decrease the number of eosinophils and to downregulate T H 2 cytokines but to increase neutrophils. The effect of corticosteroids on chemokine expression in asthma has not yet been investigated., Objective: We sought to investigate the effect of a 2-week course of oral corticosteroid (methylprednisolone, 40 mg/d) on the expression of CXC chemokines (IL-8 and IFN-gamma-inducible protein 10 [IP-10]) and CC chemokines (eotaxin and monocyte chemotactic proteins [MCPs] 1-4) in endoscopic biopsy specimens of 13 patients with moderate-to-severe asthma., Methods: CD3, major basic protein, and elastase immunoreactivities were monitored before and after treatment by using immunocytochemistry. Eotaxin, IL-8, IP-10, MCP-1, MCP-2, MCP-3, and MCP-4 mRNA expression in epithelium and submucosa were studied by using in situ hybridization., Results: Corticosteroids reduced the number of CD3-positive T cells and major basic protein-positive eosinophils ( P < .05), whereas the number of neutrophils were increased ( P < .05). Corticosteroids also reduced the number of eotaxin ( P < .05), MCP-3, and MCP-4 mRNA-positive cells ( P < .001) in the epithelium and subepithelium. However, corticosteroids caused a significant increase in the epithelial expression of IL-8 ( P < .001), IP-10 ( P < .05), and MCP-2 mRNAs ( P < .01). Corticosteroids had no effects on MCP-1 mRNA expression., Conclusion: Our results demonstrate the dual nature of corticosteroids. Although corticosteroids can downregulate the expression of some asthma-associated chemokines, such as eotaxin, MCP-3, and MCP-4, they can also upregulate the expression of other chemokines, including IL-8, IP-10, and MCP-2. The failure of oral corticosteroids to inhibit IL-8 mRNA expression might contribute to persistent airway neutrophilia observed in patients with moderate-to-severe asthma, despite treatment with corticosteroids.

Background: Otitis media with effusion (OME) occurs in the setting of eustachian tube (ET) dysfunction. Previous studies have demonstrated a predominance of T helper 2 (Th2) mediators in the middle ear effusions (MEEs) of atopic children, suggesting that allergy plays a role in the pathogenesis of OME. Given that the middle ear is contiguous with the upper airway, the allergic inflammation seen in the middle ear of atopic patients with OME may also have been observed in the nasopharynx., Objective: We hypothesize that atopic children have different cellular and cytokine profiles in MEE compared with nonatopic patients and that this allergic inflammation occurs in both the middle ear and the nasopharynx., Methods: Forty-five patients undergoing both ventilation tube placement for OME and adenoidectomy for adenoid hypertrophy were recruited. The atopic status was determined for each patient using standard skin testing. The cellular and cytokine profiles of the MEEs and the torus tubarius and adenoid tissues were investigated using immunocytochemistry and in situ hybridization., Results: Our results indicate that, within the atopic patient, there is a similar cellular and cytokine profile within the three regions sampled, with a predominant expression of interleukin-4 (a Th2 cytokine) and an increased infiltration of eosinophils compared with the nonatopic patient., Conclusion: These findings confirm the association of allergy with MEE and support the hypothesis that the middle ear may be an integral part of the United Airway Concept.

Objectives: To investigate the possible role of eosinophil peroxidase (EPO) in 3-nitrotyrosine (3NT) formation., Study Design and Setting: Observational study employing immunocytochemistry to assess the presence of 3NT, inducible nitric oxide synthase (iNOS), eosinophils, mast cells, neutrophils, and lymphocytes in ethmoid sinus mucosal biopsies from normal controls and subjects with allergic and nonallergic chronic sinusitis and nasal polyposis., Results: 3NT was more evident in biopsies from sinusitis patients (2.67 +/- 0.14, n = 21) than in healthy mucosa (0.43 +/- 0.2, n = 7, P < 0.01), but scores in atopic and nonatopic subjects were similar. Colocalization studies confirmed that 3NT was largely confined to eosinophils. No relationship was found between 3NT and other immune cells. 3NT detection was not correlated with the amount of immunostaining for iNOS., Significance: Chronic sinusitis is accompanied by 3NT formation, which is largely restricted to the eosinophils, and likely driven by the action of eosinophil peroxidase, rather than by nitric oxide levels., Ebm Rating: B-2.

Background: New hydrofluoroalkane (HFA) formulations of glucocorticoids have been shown to effectively control asthma. HFA glucocorticoids are deposited across all sizes of airways, including the small ones. However, it is not clear whether they can suppress peripheral airway inflammation., Objective: We sought to determine whether HFA-flunisolide could suppress peripheral inflammation in asthma., Methods: Twelve patients with mild to moderate asthma received HFA-flunisolide for 6 weeks. Transbronchial and endobronchial biopsy specimens were obtained before and after treatment, and spirometry was performed. Changes in inflammatory cells (eosinophils, neutrophils, lymphocytes, macrophages, basophils) and IL-5 and eotaxin were measured by using immunocytochemistry and in situ hybridization., Results: Lung function significantly improved after treatment (P <.05). HFA-flunisolide significantly reduced eosinophils, IL-5, and eotaxin in both peripheral and central airways (P <.01). Neutrophils significantly increased after treatment in peripheral and central airways (P <.05). The numbers of lymphocytes remained unchanged., Conclusions: These results show that HFA-flunisolide effectively suppressed eosinophilic inflammation in peripheral and central airways. These changes were accompanied by improvement in lung function.

Background: Glucocorticoids inhibit allergen-induced airway eosinophilia and airway hyperresponsiveness (AHR). Whether glucocorticoids mediate their effects on AHR by inhibiting eotaxin and IL-5, 2 of the principal mediators of eosinophilia, or through IL-13, an important mediator of AHR, has not been established., Objective: We sought to investigate the effects of glucocorticoids on airway eosinophilia and the expression of IL-5, eotaxin, and IL-13 in relation to the induction of AHR in a murine model of allergic asthma., Methods: Dexamethasone (4 mg/kg) and mAbs against eotaxin (80 micro g/kg) and IL-5 (100 micro g/kg) singly and in combination were administered to immunized mice before antigen challenge. Airway responsiveness to methacholine was measured in anesthetized and mechanically ventilated animals. Eotaxin, IL-5, and IL-13 in bronchoalveolar lavage fluid (BALF), lung homogenates, or both were measured by means of ELISA., Results: A single antigen challenge induced AHR that lasted at least 10 days. Eotaxin protein and mRNA levels increased in lung tissue but not in BALF after challenge. IL-5 protein and mRNA levels increased both in BALF and in lung tissue. Dexamethasone reduced airway eosinophilia, AHR, and protein and mRNA for eotaxin and IL-5. Anti-murine eotaxin and anti-IL-5 antibodies alone and in combination reduced the ovalbumin-induced airway eosinophilia significantly but failed to inhibit AHR. Both dexa-methasone and anti-IL-5/anti-eotaxin inhibited the increases in lung IL-13 levels after ovalbumin challenge to a similar extent., Conclusion: These findings suggest that the inhibition of AHR by the glucocorticoid dexamethasone does not appear to be explained by effects on eosinophilia, eotaxin, IL-5, or IL-13.

Background: Eosinophils develop from CD34(+) progenitors under the influence of IL-5. Atopic asthmatic individuals have increased numbers of mature eosinophils and eosinophil pro-genitors within their bone marrow and bronchial mucosa. We have previously reported that anti-IL-5 monoclonal antibody treatment decreases total bone marrow and bronchial mucosal eosinophil numbers in asthma., Objective: Using an anti-IL-5 monoclonal antibody, we examined the role of IL-5 in eosinophil development within the bone marrow and bronchial mucosa in asthma., Methods: Blood, bone marrow, and airway mucosal biopsy specimens were examined before and after anti-IL-5 (mepolizumab) treatment of asthmatic individuals in a double-blind, placebo-controlled trial. Numbers of mature and immature eosinophils were measured by histologic stain (bone marrow myelocytes, metamyelocytes, and mature eosinophils), flow cytometry (bone marrow and blood CD34(+)/IL-5Ralpha(+) cells), enumeration of bone marrow-derived eosinophil/basophil colony-forming units in methylcellulose culture, and sequential immunohistochemistry and in situ hybridization (bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cells)., Results: Mepolizumab decreased mature eosinophil numbers in the bone marrow by 70% (P =.017) in comparison with placebo and decreased numbers of eosinophil myelocytes and metamyelocytes by 37% (P =.006) and 44% (P =.003), respectively. However, mepolizumab had no effect on numbers of blood or bone marrow CD34(+), CD34(+)/IL-5Ralpha(+) cells, or eosinophil/basophil colony-forming units. There was a significant decrease in bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cell numbers in the anti-IL-5 treated group (P =.04)., Conclusion: These data suggest that anti-IL-5 therapy might induce partial maturational arrest of the eosinophil lineage in the bone marrow. The reduction in airway CD34(+)/IL-5 mRNA(+) cell numbers suggests that IL-5 might also be required for local tissue eosinophilopoiesis.

The involvement of chemokines in eosinophil recruitment during inflammation and allergic reactions is well established. However, a functional role for chemokines in eosinophil differentiation has not been investigated. Using in situ RT-PCR, immunostaining, and flow cytometric analysis, we report that human CD34+ cord blood progenitor cells contain CCR3 mRNA and protein. Activation of CD34+ progenitor cells under conditions that promote Th2 type differentiation up-regulated surface expression of the CCR3. In contrast, activation with IL-12 and IFN-gamma resulted in a significant decrease in the expression of CCR3. Eotaxin induced Ca2+ mobilization in CD34+ progenitor cells, which could explain the in vitro and in vivo chemotactic responsiveness to eotaxin. We also found that eotaxin induced the differentiation of eosinophils from cord blood CD34+ progenitor cells. The largest number of mature eosinophils was found in cultures containing eotaxin and IL-5. The addition of neutralizing anti-IL-3, anti-IL-5, and anti-GM-CSF Abs to culture medium demonstrated that the differentiation of eosinophils in the presence of eotaxin was IL-3-, IL-5-, and GM-CSF-independent. These results could explain how CD34+ progenitor cells accumulate and persist in the airways and peripheral blood of patients with asthma and highlight an alternative mechanism by which blood and tissue eosinophilia might occur in the absence of IL-5.

Eosinophil, basophil, and T helper 2 (TH2) cell recruitment into tissues is a characteristic feature of allergic diseases. These cells have in common the expression of the chemokine receptor CCR3, which may represent a specific pathway for their accumulation in vivo. Although animal models of allergic reactions are available, findings cannot always be extrapolated to man. To overcome these limitations, we have developed a humanized mouse model of allergic cutaneous reaction using severe combined immunodeficiency mice engrafted with skin and autologous peripheral blood mononuclear cells from allergic donors. Intradermal injection of the relevant allergen into human skin xenografts from allergic individuals induced a significant recruitment of human CD4(+) T cells, basophils, and TH2-type cytokine mRNA-expressing cells, as well as murine eosinophils. Human skin xenografts, atopic status, and autologous peripheral blood mononuclear cell reconstitution were all mandatory to induce the allergic reaction. Next, we addressed the role of CCR3 in the endogenous mechanisms involved in the inflammatory cell recruitment in this experimental model of allergic cutaneous reaction. In vivo administration of an anti-human CCR3-blocking antibody selectively reduced accumulation of eosinophils but not that of CD4(+) cells, basophils, or cells expressing mRNA for TH2-type cytokines. These findings establish a new in vivo model of humanized allergic reaction and suggest that eosinophil migration is mediated mainly through CCR3. Finally, these results suggest that this model might be useful to test human-specific antiallergic modulators.

BackgroundEosinophilic airway inflammation is heterogeneous in asthmatic patients. We recently described a distinct subtype of asthma defined by the expression of genes inducible by T(H)2 cytokines in bronchial epithelium. This gene signature, which includes periostin, is present in approximately half of asthmatic patients and correlates with eosinophilic airway inflammation. However, identification of this subtype depends on invasive airway sampling, and hence noninvasive biomarkers of this phenotype are desirable.ObjectiveWe sought to identify systemic biomarkers of eosinophilic airway inflammation in asthmatic patients.MethodsWe measured fraction of exhaled nitric oxide (Feno), peripheral blood eosinophil, periostin, YKL-40, and IgE levels and compared these biomarkers with airway eosinophilia in asthmatic patients.ResultsWe collected sputum, performed bronchoscopy, and matched peripheral blood samples from 67 asthmatic patients who remained symptomatic despite maximal inhaled corticosteroid treatment (mean FEV(1), 60% of predicted value; mean Asthma Control Questionnaire [ACQ] score, 2.7). Serum periostin levels are significantly increased in asthmatic patients with evidence of eosinophilic airway inflammation relative to those with minimal eosinophilic airway inflammation. A logistic regression model, including sex, age, body mass index, IgE levels, blood eosinophil numbers, Feno levels, and serum periostin levels, in 59 patients with severe asthma showed that, of these indices, the serum periostin level was the single best predictor of airway eosinophilia (P = .007).ConclusionPeriostin is a systemic biomarker of airway eosinophilia in asthmatic patients and has potential utility in patient selection for emerging asthma therapeutics targeting T(H)2 inflammation.

Background: Long‐term trajectories of asthma with fixed airflow obstruction (FAO) may reveal links to inflammatory endotypes. Objective: We investigated whether measures of asthma control and airway inflammation and remodelling differed by long‐term FAO status in moderate‐to‐severe asthma. Methods: Adults enrolled in the Difficult Asthma Study assessed initially using serial Asthma Control Questionnaire (ACQ), exacerbation history, spirometry and sputum cytology over 12 months, as well as endoscopic bronchial biopsy with airway smooth muscle (ASM) quantification, were revaluated three or more years later with questionnaires and spirometry. FAO was defined as a persistent post‐bronchodilator forced expired volume in one second (FEV1)‐to‐forced vital capacity ratio below 0.70. Results: Sixty‐two participants (mean ± SD age 48 ± 11 years; 50% female; 75% atopic; asthma duration 24 ± 14 years) returned for follow‐up assessment (median interval 7.9 years; IQR: 5.4‐8.8 years). Compared to participants without FAO (n = 28), those with FAO at baseline and long‐term follow‐up (n = 18) had higher baseline sputum neutrophil content and ASM, and a higher exacerbation frequency that persisted at long‐term follow‐up. Sputum eosinophils, ACQ and long‐term FEV1 decline did not differ. Participants with incident FAO at long‐term follow‐up (n = 16) had higher baseline exacerbation frequency, sputum eosinophil content, higher ACQ scores and greater decline in FEV1, whereas baseline ASM was similar to those without FAO. Conclusion: In moderate‐to‐severe asthma, long‐term FAO is characterized by neutrophilic sputum inflammation and airway remodelling, but FEV1 decline is similar to those without FAO. Long‐term incident FAO is preceded by higher exacerbation frequency, higher sputum eosinophil content and significant FEV1 decline. [ABSTRACT FROM AUTHOR]

Asthma is characterized by chronic inflammation of the airways in which there is an overabundance of eosinophils, mast cells, and activated T helper lymphocytes. These inflammatory cells release mediators that then trigger bronchoconstriction, mucus secretion, and remodeling. The inflammatory mediators that drive this process include cytokines, chemokines, growth factors, lipid mediators, immunoglobulins, and histamine. The inflammation in allergic asthma can be difficult to control. This is mainly due to the development of an adaptive immunity to an allergen, leading to immunological memory. This leads to recall reactions to the allergen, causing persistent inflammation and damage to the airways. Generally, in asthma inflammation is directed by Th2 cytokines, which can act by positive feedback mechanisms to promote the production of more inflammatory mediators including other cytokines and chemokines. This review discusses the role of cytokines and chemokines in the immunobiology of asthma and attempts to relate their expression to morphological and functional abnormalities in the lungs of asthmatic subjects. We also discuss new concepts in asthma immunology, in particular the role of cytokines in airway remodeling and the interaction between cytokines and infection. [ABSTRACT FROM AUTHOR]

The article presents a comparison of the patterns of expression of representative T-helper (Th) type 1 and Th-2 cytokines and the neutrophil- and eosinophil-associated chemokines in the airway tissues of patients with severe and moderate asthma. Researchers use immunocytochemistry in examining the expression of proteins in the airway. They found that patients with severe asthma have increases in neutrophils and eosinophils in the sputum and have different airway cytokine/chemokine expression.

Background: Inhaled corticosteroids (ICSs) have been shown to reverse epithelial damage and decrease lamina reticularis thickness in patients with asthma. Objective: This study investigated whether clinical asthma control and airway inflammation could be maintained after switching therapy from medium-dose fluticasone propionate (FP) to low-dose FP administered with the long-acting β2-agonist (LABA) salmeterol. Methods: Eighty-eight subjects (age, ≥18 years) who, during open-label screening, demonstrated improved asthma control after an increase from 100 μg of FP twice daily to 250 μg of FP twice daily were randomized to receive 100/50 μg of FP/salmeterol through a Diskus inhaler (GlaxoSmithKline, Research Triangle Park, NC) twice daily or continue 250 μg of FP twice daily through a Diskus inhaler for 24 weeks. Clinical outcomes were monitored, and bronchial biopsy specimens and bronchoalveolar lavage fluid were obtained before and after 24 weeks of treatment. Results: There were no significant differences between treatments with respect to eosinophils in the bronchial mucosa and bronchoalveolar lavage fluid; mucosal mast cells, neutrophils, or CD3+, CD4+, CD8+, or CD25+ T lymphocytes; or concentration of mediators (GM-CSF, IL-8, and eosinophil cationic protein). The 2 treatments were not different with respect to lamina reticularis thickness. Consistent with the airway inflammatory measures, clinical and physiologic measures of asthma control were also similar. Conclusion: This study demonstrates that control of asthma and airway inflammation is maintained over the 24-week treatment period when patients requiring a medium-dose ICS are switched to a lower-dose ICS with a LABA. Clinical implications: A lower-dose ICS with a LABA is effective in controlling inflammation and providing clinical asthma control, confirming current guideline recommendations. [Copyright &y& Elsevier]

Background: Although increased nitric oxide (NO) production in asthma is mediated largely by upregulation of the inducible form of nitric oxide synthase (iNOS, or NOS 2), some studies have suggested an important role for the usually constitutive neural NOS isoform (nNOS, or NOS 1). Aim: To investigate how NOS 1 may influence allergic inflammation, we used NOS 1 knockout mice and their wild-type (WT) controls. Methods: Mice were sensitized and challenged with ovalbumin (OVA) using a protocol known to upregulate NOS 2 in the airways. Results: In addition to expected increases in NOS 2 activity, OVA challenge led to increases in calcium-dependent NOS activity, which was accounted for by increased expression of NOS 1 at both mRNA (n = 5, p < 0.001) and protein levels (n = 5, p < 0.01). In NOS-1-deficient mice, OVA challenge induced less eosinophilia (n = 7, p < 0.05) and much less NO production (n = 10, p < 0.01) than in WT controls, reflecting not only the expected absence of NOS 1, but also lack of upregulation of NOS 2. This interaction appeared to be stimulus specific as NOS-1-deficient mice did upregulate NOS 2 following exposure to lipopolysaccharide (n = 5, p < 0.001). Conclusions: These findings underscore the importance of NOS 1 in allergic airway inflammation and suggest a mechanism by which NOS 1 may influence overall NO production in the airways. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: The role of CD8+ T cells in the immune response to airway challenge with an allergen is poorly understood. Objective: The aim of this study was to test the hypothesis that resident naive CD8+ T cells modulate the magnitude of CD4+ T cell–dependent allergic airway responses. Methods: Cervical lymph node CD4+ T cells (2 × 106) were harvested from ovalbumin (OVA)– or sham-sensitized rats and injected intraperitoneally into naive Brown Norway recipients. The recipients were treated with a CD8α mAb (OX-8) to deplete the resident CD8+ T cells (n=12) or mouse ascites (n=12). Two days after adoptive transfer, the recipient animals were OVA challenged, lung resistance was measured for 8 hours, and bronchoalveolar lavage (BAL) was performed. Results: After OVA challenge, primed CD4-transferred CD8-depleted rats had larger early airway responses and late airway responses compared with primed CD4-transferred CD8-nondepleted rats (early airway responses: 158.6% ± 19.2% vs 115.7% ± 5.9%, P < .05; late airway responses: 8.5% ± 1.7% vs 4.4% ± 0.9%, P < .05). BAL eosinophilia was also greater (4.67% ± 0.45% vs 2.34 ± 0.26%, P < .01). The cells in BAL fluid expressing IL-4 mRNA were not significantly changed by CD8 depletion, but IL-5 mRNA+ cells were higher in number, and IFN-γ mRNA+ cells were fewer in the CD8-depleted group. Conclusions: Resident CD8+ T cells downregulate the late allergic response and airway inflammation evoked by CD4+ T-cell transfers in Brown Norway rats. This downregulation does not require antigen priming. [ABSTRACT FROM AUTHOR]

Background: Cytokines and chemokines have been implicated in the pathogenesis of asthma. Inhaled corticosteroids have been shown to decrease the number of eosinophils and to downregulate TH2 cytokines but to increase neutrophils. The effect of corticosteroids on chemokine expression in asthma has not yet been investigated. Objective: We sought to investigate the effect of a 2-week course of oral corticosteroid (methylprednisolone, 40 mg/d) on the expression of CXC chemokines (IL-8 and IFN-γ–inducible protein 10 [IP-10]) and CC chemokines (eotaxin and monocyte chemotactic proteins [MCPs] 1-4) in endoscopic biopsy specimens of 13 patients with moderate-to-severe asthma. Methods: CD3, major basic protein, and elastase immunoreactivities were monitored before and after treatment by using immunocytochemistry. Eotaxin, IL-8, IP-10, MCP-1, MCP-2, MCP-3, and MCP-4 mRNA expression in epithelium and submucosa were studied by using in situ hybridization. Results: Corticosteroids reduced the number of CD3-positive T cells and major basic protein–positive eosinophils (P < .05), whereas the number of neutrophils were increased (P < .05). Corticosteroids also reduced the number of eotaxin (P < .05), MCP-3, and MCP-4 mRNA–positive cells (P < .001) in the epithelium and subepithelium. However, corticosteroids caused a significant increase in the epithelial expression of IL-8 (P < .001), IP-10 (P < .05), and MCP-2 mRNAs (P < .01). Corticosteroids had no effects on MCP-1 mRNA expression. Conclusion: Our results demonstrate the dual nature of corticosteroids. Although corticosteroids can downregulate the expression of some asthma-associated chemokines, such as eotaxin, MCP-3, and MCP-4, they can also upregulate the expression of other chemokines, including IL-8, IP-10, and MCP-2. The failure of oral corticosteroids to inhibit IL-8 mRNA expression might contribute to persistent airway neutrophilia observed in patients with moderate-to-severe asthma, despite treatment with corticosteroids. [Copyright &y& Elsevier]

Asthma is a complex disorder associated with the activation of T lymphocytes and with eosinophil infiltration within the airways. A substantial amount of current research involves the interaction among inflammatory cells as a result of the production of a wide array of T helper (h) 2 cytokines. Recent advances in the pathophysiologic mechanisms of asthma point to the importance of transcription factors of cytokines that underlie the development of Th2-type responses. The study of transcription factors has begun to reveal mechanisms of dysregulated gene regulation in asthmatic diathesis. [ABSTRACT FROM AUTHOR]

Background: Eosinophils develop from bone marrow (BM) progenitors, and interleukin–5 (IL–5) and eotaxin may act in expansion and mobilisation of BM eosinophils in asthma. Methods: We have examined phenotypic changes as CD34+ cells develop to the eosinophil lineage in vitro, and have evaluated BM eosinophils from asthmatic and control subjects for expression of the eotaxin receptor, CCR3. Results: Acquisition of receptors for IL–5 and CCR3 was an early event in eosinophil development. There were increased CD34+ cells, and mature and immature CCR3+ eosinophils in BM from asthmatics. Conclusion: These data suggest that IL–5 may act early in eosinophil development, and that eotaxin has the capacity to mobilise a BM eosinophil pool in asthma. [ABSTRACT FROM AUTHOR]

An abstract of the article "Th17 cytokines regulate profibrotic cytokines release by human eosinophils," by Rabih Halwani and colleagues is presented.

Abstract: Bullous pemphigoid is an inflammatory disease of the skin associated with eosinophil infiltration and the presence of high levels of Th2 cytokines in the associated blister fluid. Little is known about the contribution of chemokines in this disease. We found that eotaxin and MCP-4 mRNA and immunoreactivity were expressed in all biopsies of BP patients and were mainly localized to the epidermis and eosinophils. The expression of eotaxin and MCP-4 was enhanced in eosinophils following IL-5 treatment. Subsequent stimulation of IL-5-primed eosinophils with Ig-immune complexes, results in increase secretion of eotaxin and MCP-4 in the supernatants. Using immunostaining, these two chemokines were localized to the granules of eosinophils. BF was found to contain chemotactic activity for eosinophils, neutrophils and T cells. The chemotactic effect of BF for eosinophils was more effective when eosinophils were stimulated with IL-5 or IL-4. We also found that the levels of Th2-associated chemokines (eotaxin and MCP-4) in BF were significantly higher than the Th1-associated chemokines (MIP-1β and IP-10). This was consistent with the increased chemotaxis of polarized Th2 cells toward BF, when compared to Th1-differentiated T cells. Our results support the involvement of Th2-associated chemokines in the pathogenesis of BP disease. [Copyright &y& Elsevier]