Association between airway hyperreactivity and bronchial macrophage dysfunction in individuals with mild asthma

Little is known about the functional capabilities of bronchial macrophages (BMs) and their relationship to airway disease such as asthma. We hypothesize that BMs from asthmatics may be modulated in their function compared with similar cells from healthy individuals. BMs obtained by induced sputum from mild asthmatics (n = 20) and healthy individuals (n = 20) were analyzed using flow cytometry for CD16, CD64, CD11b, CD14, and human leukocyte antigen-DR expression, phagocytosis of IgG opsonized yeast, and oxidant production. Asthma status was assessed by lung function [percent predicted forced vital capacity and forced expiratory volume in 1 s (FEV(1))], percent sputum eosinophils, and nonspecific airway responsiveness [provocative concentration that produces a 20% fall in FEV(1) (PC(20,FEV1))]. Asthmatics with >5% airway eosinophils (AEo+) had decreased BM CD64 expression and phagocytosis compared with asthmatics with <5% eosinophils (AEo-). Among asthmatics, a significant correlation was found between CD64 expression and BM phagocytosis (R = 0.7, P < 0.009). Phagocytosis was also correlated with PC(20,FEV1) (R = 0.6, P < 0.007), lung function (%predicted FEV(1), R = 0.7, P < 0.002) and percent eosinophils (R = -0.6, P < 0.01). In conclusion, BM from asthmatics are functionally modulated, possibly by Th2 cytokines involved in asthma pathology.     

IL-2 and IL-4 stimulate MEK1 expression and contribute to T cell resistance against suppression by TGF-beta and IL-10 in asthma

The T cell-driven airway inflammation in chronic asthma is uninhibited and sustained. We examined the resistance of T cells from asthmatic patients against suppression by TGF-β, IL-10 and glucocorticoids and explored its signaling mechanism. CD4(+)CD25(-) T cells from allergic asthmatic subjects demonstrated increased TCR-stimulated proliferation as compared with healthy and chronic obstructive pulmonary disease controls. This proliferation was resistant to inhibition by TGF-β, IL-10, and dexamethasone and to anergy induction. CD4 T cells from asthmatic patients, but not chronic obstructive pulmonary disease, allergic rhinitis, and healthy subjects, showed increased expression of MEK1, heightened phosphorylation of ERK1/2, and increased levels of c-Fos. IL-2 and IL-4 stimulated the expression of MEK1 and c-Fos and induced T cell resistance. The inhibition of MEK1 reversed, whereas induced expression of c-Fos and JunB promoted T cell resistance against TGF-β- and IL-10-mediated suppression. We have uncovered an IL-2- and IL-4-driven MEK1 induction mechanism that results in heightened ERK1/2 activation in asthmatic T cells and make them resistant to certain inhibitory mechanisms.     

Anti-inflammatory non-steroidal drug able to modulate IL-10 in allergic asthma

Our studies target alternative/adjuvant therapies in allergic diseases, able to qualitatively/quantitatively modify cytokine profiles produced by both CD4+ T-cell subsets (mainly Th1 and Th2) and B-cells, macrophages, etc. Current investigations aim to identify compounds capable to down-regulate IL-10 as an exponent of Th2 cell function and, consequently, to up-regulate Th1 cytokine levels. Experiments on ten allergic asthmatic patients and ten healthy subjects as control were performed. Cytokine production, triggered in PBMCs culture systems by PHA, was modulated with Indomethacin, a non-steroidal anti-inflammatory drug and IL-10 was measured in 24 hours culture supernatants. According to our experimental data, IL-10 level of asthmatic patients' PBMCs in the resting state is not significantly different from control. PHA-activated PBMCs from asthmatic patients do not display significantly higher IL-10 levels than the normal subjects. The results obtained up-to-date reveal the fact that Indomethacin strongly down-regulates IL-10 levels in PBMCs cultures, in both asthmatic allergic patients and healthy subjects. It is obvious that the inhibitory effect of Indomethacin on IL-10 released by PBMCs is higher in the case of allergic asthmatic patients. The results obtained in this study demonstrate that Indomethacin is a possible therapeutic candidate in allergic asthma.     

Increased interleukin-4 and decreased interferon-γ levels in serum of children with asthma

Background and purposeImmune and inflammatory responses, mediated by cytokines, play important roles in the pathophysiology of asthma. These responses are associated with over expression of T helper (Th)-2 cytokine, particularly interleukin (IL)-4 and IL-5, and decreased expression of Th-1 cytokine, IL-2 and IFN-γ. We hypothesized that there would be an imbalance in the levels of circulating IL-4 and IFN-γ in the asthmatic subjects.MethodWe investigated serum levels of IL-4 and IFN-γ among eighty children (18 steroid-naïve, 30 steroid-treated children with asthma and 32 healthy controls) using commercially available ELISA kits.ResultsSerum level of IL-4 was significantly higher in steroid-naïve group of asthmatic children compared to the healthy control subjects and was lower in steroid-treated group though the level was statistically not significant. In contrast, serum levels of IFN-γ were significantly lower in both steroid-naïve and steroid-treated groups of asthmatic children compared to healthy control subjects.ConclusionThe results of our study suggest that serum level of IL-4 may be elevated in concert with decreased level of IFN-γ in asthma. Determination of serum levels of IL-4 and IFN-γ may be a useful tool for understanding the disease processes in asthma.     

The Characteristics of Th1/Th2 Cytokine Receptors on Monocytes in Untreated Patients of Long Term Nonprogressor or Chronic HIV Infection

Monocytes/macrophages play crucial roles in immunity to microorganisms and are one of the important targets for human immunodeficiency virus (HIV) infection. The phenotypes and function of monocytes in HIV-infected patients were poorly determined. We herein detected the expression of Th1/Th2 cytokine receptors on monocyte subsets in the untreated HIV-infected patients of either long term nonprogressor (LTNP) or chronic infection (CHI). CD14+CD16- monocytes were significantly increased and CD14+CD16+ monocytes were reduced in patients of LTNP or CHI compared with healthy control. IL-6R expression on CD14+CD16- monocytes were decreased in patients of LTNP or CHI, whereas IL-4R and IL-10R expression on both CD14+CD16- and CD14+CD16+ monocyte subsets were increased in patients with LTNP or CHI, as determined by flow cytometry and real time PCR assays. The decreased IL-6R expression and enhanced IL-4R and IL-10R expression were also observed on CD4+ T cells of these patients, indicating that these changes in monocytes are not cell-specific. CD14+CD16- monocytes of HIV-infected patients produced less TNF-α and IL-1β but identical levels of IL-6, and IL-12 as the control after IFN-γ/LPS stimulation. However, in the presence of IL-4 or IL10, CD14+CD16- monocytes of HIV-infected patients produced more TNF-α, IL-6, IL-12 or Il-1β after IFN-γ/LPS stimulation than the healthy control, supporting the impaired IL-4R and IL-10R signal pathways in patients with LTNP and CHI. Therefore, our present study offered the basic information for the Th1/Th2 cytokine receptor expression and function on monocyte subsets in untreated HIV-infected individuals.     

IL-17 Enhances Chemotaxis of Primary Human B Cells during Asthma

IL-17 is a pro-inflammatory mediator that is believed to play a critical role in regulating tissue inflammation during asthma, COPD, as well as other inflammatory disorders. The level of expression of IL-17 has been shown to be upregulated in lung bronchial tissue of asthmatic patients. Several reports have provided further evidence that this cytokine could play a key role in enhancing the migration of inflammatory as well as structural cells of the bronchial lung tissue during asthma and COPD. B cell infiltration to sites of inflammation during inflammatory disorders such as bowel disease, asthma and COPD has been reported. Accordingly, in this study we hypothesized that IL-17 may exert a chemotactic effect on primary B cells during asthma. We observed that B cells from asthmatic patients expressed significantly higher levels of IL-17RA and IL-17RC, compared to those of healthy subjects. Using an in-vitro migration assay, B cells were shown to migrate towards both IL-17A and IL-17F. Interestingly, blocking IL-17A and IL-17F signaling using either anti-IL-17R antibodies or MAP kinase inhibitors prevented in vitro migration of B cell towards IL-17. These observations indicate a direct chemotactic effect of IL-17 cytokines on primary peripheral blood B cells with higher effect being on asthmatic B cells. These findings revealed a key role for IL-17 in enhancing the migration of B cells to the lung tissue during asthma or COPD.     

Serum levels of soluble IL-2R, CD4 and CD8 in bronChial asthma

The aim of the present study was to compare serum levels of soluble forms of interleukin-2 receptor, CD4 and CD8, released by lymphocytes during activation of the immune system, in patients with allergic bronchial asthma, with those in healthy subjects. Significantly higher levels of soluble IL-2R and soluble CD4 were found in patients with asthma compared with the control group. In contrast, lower levels of soluble CD8 values were found in patients with asthma compared to the control group. Significant correlations were found for both sIL-2R and sCD4 and these two molecules, with lung function measured as bronchial responsiveness to inhaled methacholine. These results strengthen previous suggestions that in allergic bronchial asthma, activation of T cells plays a significant role in the disease pathogenesis.     

支气管哮喘病儿外周血树突状细胞功能变化

目的:观察支气管哮喘病儿外周血单个核细胞(PBMC)来源树突状细胞(DC)功能变化。方法:以18例健康儿童为对照,选择16例支气管哮喘发作期病儿为研究对象,分离PBMC并经rhGM-CSF诱生成熟DC。采用流式细胞仪(FACS)检测DC表面共刺激分子CD80(B7-1)、CD86(B7-2)和CD83的表达率;ELISA法检测培养上清液中IL-10和IL-12的变化。结果:①哮喘组DC表面CD86的表达率明显高于健康对照组(t=2.27,P<0.05),CD80、CD83的表达率与健康对照组比较均无显著性差异(t=1.17,1.34;P>0.05)。②哮喘组DC分泌IL-10、IL-12水平均明显低于健康对照组(t’=3.31,3.39;P<0.01)。③哮喘组DC分泌IL-10与IL-12成正相关(r=0.740,P<0.01),而健康对照组IL-10与IL-12无相关性(r=0.232,P>0.05)。结论:支气管哮喘病儿DC存在功能缺陷,主要表现在CD86表达升高、IL-10、IL-12分泌减少。     

Elevation of IL-6 in the allergic asthmatic airway is independent of inflammation but associates with loss of central airway function

Background

Asthma is a chronic inflammatory disease of the airway that is characterized by a Th2-type of immune response with increasing evidence for involvement of Th17 cells. The role of IL-6 in promoting effector T cell subsets suggest that IL-6 may play a functional role in asthma. Classically IL-6 has been viewed as an inflammatory marker, along with TNFα and IL-1β, rather than as regulatory cytokine.

Objective

To investigate the potential relationship between IL-6 and other proinflammatory cytokines, Th2/Th17 cytokines and lung function in allergic asthma, and thus evaluate the potential role of IL-6 in this disease.

Methods

Cytokine levels in induced sputum and lung function were measured in 16 healthy control and 18 mild-moderate allergic asthmatic subjects.

Results

The levels of the proinflammatory biomarkers TNFα and IL-1β were not different between the control and asthmatic group. In contrast, IL-6 levels were specifically elevated in asthmatic subjects compared with healthy controls (p < 0.01). Hierarchical regression analysis in the total study cohort indicates that the relationship between asthma and lung function could be mediated by IL-6. Among Th2 cytokines only IL-13 (p < 0.05) was also elevated in the asthmatic group, and positively correlated with IL-6 levels (r_S = 0.53, p < 0.05).

Conclusions

In mild-moderate asthma, IL-6 dissociates from other proinflammatory biomarkers, but correlates with IL-13 levels. Furthermore, IL-6 may contribute to impaired lung function in allergic asthma.     

Co-Culture of Human Bronchial Fibroblasts and CD4+ T Cells Increases Th17 Cytokine Signature

Background

Airway inflammation is an important characteristic of asthma and has been associated with airway remodelling and bronchial hyperreactivity. The mucosal microenvironment composed of structural cells and highly specialised extracellular matrix is able to amplify and promote inflammation. This microenvironment leads to the development and maintenance of a specific adaptive response characterized by Th2 and Th17. Bronchial fibroblasts produce multiple mediators that may play a role in maintaining and amplifying this response in asthma.

Objective

To investigate the role of bronchial fibroblasts obtained from asthmatic subjects and healthy controls in regulating Th17 response by creating a local micro-environment that promotes this response in the airways.

Methods

Human bronchial fibroblasts and CD4⁺T cells were isolated from atopic asthmatics and non-atopic healthy controls. CD4⁺T were co-cultured with bronchial fibroblasts of asthmatic subjects and healthy controls. RORc gene expression was detected by qPCR. Phosphorylated STAT-3 and RORγt were evaluated by western blots. Th17 phenotype was measured by flow cytometry. IL-22, IL17, IL-6 TGF-β and IL1-β were assessed by qPCR and ELISA.

Results

Co-culture of CD4⁺T cells with bronchial fibroblasts significantly stimulated RORc expression and induced a significant increase in Th17 cells as characterized by the percentage of IL-17⁺/CCR6⁺ staining in asthmatic conditions. IL-17 and IL-22 were increased in both normal and asthmatic conditions with a significantly higher amount in asthmatics compared to controls. IL-6, IL-1β, TGF-β and IL-23 were significantly elevated in fibroblasts from asthmatic subjects upon co-culture with CD4⁺T cells. IL-23 stimulates IL-6 and IL-1β expression by bronchial fibroblasts.

Conclusion

Interaction between bronchial fibroblasts and T cells seems to promote specifically Th17 cells profile in asthma. These results suggest that cellular interaction particularly between T cells and fibroblasts may play a pivotal role in the regulation of the inflammatory response in asthma.     

Airway diffusing capacity of nitric oxide and steroid therapy in asthma.

Exhaled nitric oxide (NO) concentration is a noninvasive index for monitoring lung inflammation in diseases such as asthma. The plateau concentration at constant flow is highly dependent on the exhalation flow rate and the use of corticosteroids and cannot distinguish airway and alveolar sources. In subjects with steroid-naive asthma (n = 8) or steroid-treated asthma (n = 12) and in healthy controls (n = 24), we measured flow-independent NO exchange parameters that partition exhaled NO into airway and alveolar regions and correlated these with symptoms and lung function. The mean (+/-SD) maximum airway flux (pl/s) and airway tissue concentration [parts/billion (ppb)] of NO were lower in steroid-treated asthmatic subjects compared with steroid-naive asthmatic subjects (1,195 +/- 836 pl/s and 143 +/- 66 ppb compared with 2,693 +/- 1,687 pl/s and 438 +/- 312 ppb, respectively). In contrast, the airway diffusing capacity for NO (pl.s-1.ppb-1) was elevated in both asthmatic groups compared with healthy controls, independent of steroid therapy (11.8 +/- 11.7, 8.71 +/- 5.74, and 3.13 +/- 1.57 pl.s-1.ppb-1 for steroid treated, steroid naive, and healthy controls, respectively). In addition, the airway diffusing capacity was inversely correlated with both forced expired volume in 1 s and forced vital capacity (%predicted), whereas the airway tissue concentration was positively correlated with forced vital capacity. Consistent with previously reported results from Silkoff et al. (Silkoff PE, Sylvester JT, Zamel N, and Permutt S, Am J Respir Crit Med 161: 1218-1228, 2000) that used an alternate technique, we conclude that the airway diffusing capacity for NO is elevated in asthma independent of steroid therapy and may reflect clinically relevant changes in airways.     

Flow cytometrical determination of regulatory cytokines (IL-10, IL-12) and circulating dendritic cell cytokines in allergic asthmatic children

Interleukin (IL)-10 and IL-12 have been suggested to be key regulators in the pathogenesis of allergic asthma. Several of the secretion products of dendritic cells (DC), such as IL-12, IL-10, IL-1beta and TNF-alpha, are considered to play a role in allergic asthma. This study compares the production of IL-10 and IL-12 in allergic asthmatic children (n = 17) and controls (n = 14) by measuring their extracellular secretion in whole blood samples after stimulation, using a microsphere-based immunoassay. Additionally, we assessed intracellular production of IL-1beta, TNF-alpha, IL-12 and IL-10 by circulating DC in stimulated whole blood samples of asthmatic and healthy children. The concentration of IL-10 in the supernatants of LPS-stimulated whole blood was significantly lower in allergic asthmatic children as compared to healthy children (463 (207-768) vs 881 (364-2626) pg/mL; p = 0.005). When a combined LPS and IFN-gamma stimulation was used, IL-10 production decreased significantly as compared to LPS alone, especially in healthy children. Consequently, no difference in IL-10 production after LPS/IFN-gamma stimulation was found between healthy and allergic children. In contrast to isolated LPS stimulation, stimulation with LPS/IFN-gamma induced higher IL-12 production; allergic asthmatic children showed a significantly lower IL-12 secretion after LPS/IFN-gamma stimulation as compared to healthy children (20 (5-247) vs 208 (7-775) pg/mL; p=0.03). Moreover, the number of IL-12 producing CD11c-positive DC (DC1) tended to be lower in asthmatic children compared to healthy children (0.05 (0.00-0.45) vs 0.27 (0.00-0.83) 10(6)/L) and correlated with the extracellular release of IL-12 in asthmatic children (r = 0.65; p = 0.016). The number of IL-1beta and TNF-alpha producing CD11c-positive DC (DC1) was comparable between healthy and asthmatic children. We hypothesize that the decreased production of IL-10 and IL-12 is responsible for Th2 polarized responses in allergic asthmatic children.     

Inflammatory response in induced sputum mononuclear cells from patients with acute exacerbation of asthma

Examination of sputum provides a direct method to investigate airway inflammation non-invasively in particular Th1 (IL-2, IFN-gamma) and Th2 (IL-4, IL-10) cytokine production. IL-2, IL-4, IL-10 and IFN-gamma cytokine were studied in induced sputum mononuclear cells of asthmatic patients. Sputum induction was performed on 10 patients and 10 normal controls. Basal and mitogen-stimulated cytokine production was determined in induced sputum T-cell culture. Supernatants were collected and assayed not only with specific ELISA but also with polymerase chain reaction (PCR) techniques. Data showed a significantly higher production of IL-10 by both the ELISA and the RT-PCR techniques in asthmatic patients compared with sputum mononuclear cells from healthy controls. IL-4 production was detected at a low level using the ELISA method in asthmatic patients. The RT-PCR analysis detected a significantly IL-4-mRNA expression in all asthmatic patients, compared with controls. Results of IL-10 and IL-4 mRNA expression were reproducible. We did not find any alteration in the expression of the type 1 derived cytokines (IL-2 and IFN-gamma) in asthmatic patients or in healthy controls. Our study showed a tendency of induced sputum mononuclear cells to express a Th2-like cytokine pattern in acute exacerbation of asthmatic patients, where IL-10 and IL-4 are synthesized in larger amounts. The combination of sputum induction as a non-invasive tool to explore the lung and the identification of disease-associated cytokine expression and of specific cytokine mRNA should help elucidate mechanisms of the immunologically mediated inflammatory responses in asthma.     

Interleukin (IL)-4/IL-9 and exogenous IL-16 induce IL-16 production by BEAS-2B cells, a bronchial epithelial cell line

Previous studies have suggested that bronchial epithelial cells may perpetuate airway inflammation. We have reported that the bronchial epithelial cell line BEAS-2B can produce interleukin (IL)-16, a potent chemoattractant for CD4+ T cells. IL-16 is thought to regulate airway inflammation in asthmatics. Recent studies showed that IL-4 induces inflammatory cytokines in bronchial epithelial cells and that IL-9 is a candidate gene for development of asthma. The present study demonstrated that BEAS-2B cells produced specifically IL-16 by synergistic effects of IL-4 + IL-16, or IL-9 + IL-16, and that the synthesized IL-16 induced migration of CD4+ T cells. This study is a first report indicating that IL-16 production may be maintained by an autocrine machinery by epithelial cell-derived IL-16 with IL-4 and IL-9 in asthma.     

Essential role for both CD80 and CD86 costimulation, but not CD40 interactions, in allergen-induced Th2 cytokine production from asthmatic bronchial tissue: role for alphabeta, but not gammadelta, T cells

CD80 and CD86 interact with CD28 and deliver costimulatory signals required for T cell activation. We demonstrate that ex vivo allergen stimulation of bronchial biopsy tissue from mild atopic asthmatic, but not atopic nonasthmatic, subjects induced production of IL-5, IL-4, and IL-13. Explants from both study groups did not produce IFN-gamma, but secreted the chemokine RANTES without any overt stimulation. In addition to allergen, stimulation of asthmatic explants with mAbs to CD3 and TCR-alphabeta but not TCR-gammadelta induced IL-5 secretion. Allergen-induced IL-5 and IL-13 production by the asthmatic tissue was inhibited by anti-CD80 and, to a lesser extent, by anti-CD86 mAbs. In contrast, the production of these cytokines by PBMCs was not affected by mAbs to CD80, was inhibited by anti-CD86, and was strongly attenuated in the presence of both Abs. FACS analysis revealed that stimulated asthmatic bronchial tissue was comprised of CD4+ T cells that expressed surface CD28 (75. 3%) but little CTLA-4 (4.0%). Neutralizing mAbs to CD40 ligand had no effect on the cytokine levels produced by asthmatic tissue or PBMCs. Collectively, these findings suggest that allergen-specific alphabeta T cells are resident in asthmatic bronchial tissue and demonstrate that costimulation by both CD80 and CD86 is essential for allergen-induced cytokine production. In contrast, CD86 appears to be the principal costimulatory molecule required in PBMC responses. Attenuation of type 2 alphabeta T cell responses in the bronchial mucosa by blocking these costimulatory molecules may be of therapeutic potential in asthma.     

Functional expression of IL-9 receptor by human neutrophils from asthmatic donors: role in IL-8 release

Human polymorphonuclear neutrophils (PMNs) express surface receptors for various inflammatory mediators, including IgE and IL-4. Recently, the IL-9R locus has been genetically linked to asthma and bronchial hyperresponsiveness in humans. In this study, we evaluated expression of the IL-9R and the effect of IL-9 on human PMNs. RT-PCR analysis showed the presence of IL-9Ralpha-chain mRNA in PMN RNA preparations from asthmatic patients. Using FACS analysis, surface expression of IL-9Ralpha was detected on PMNs freshly isolated from asthmatics, and to a lesser extent on normal controls. In addition, protein expression of IL-9Ralpha was also detected in peripheral blood and bronchoalveolar lavage PMNs. Furthermore, functional studies showed that IL-9 stimulation of PMNs results in the release of IL-8 in a concentration-dependent manner. The anti-IL-9 neutralizing Ab suppressed this effect, but had no effect on GM-CSF-induced IL-8 release from PMNs. Taken together, these findings suggest a novel role for PMNs in allergic disease through the expression and activation of the IL-9R.