Surfactant protein levels in bronchoalveolar lavage after segmental allergen challenge in patients with asthma

BACKGROUND: Allergic asthma is associated with airway inflammation and dysfunction of pulmonary surfactant. Because surfactant proteins (SP) account for immunomodulatory functions as well as biophysical functions, we hypothesized that the allergic response in asthma might be accompanied by a dysregulation of SPs. METHODS: We measured levels of SP-A, SP-B, SP-C and SP-D by enzyme-linked immunosorbent assay in bronchoalveolar lavage (BAL) fluid of 23 asthma patients and 10 healthy control subjects under well-controlled conditions before and 24 h after segmental allergen provocation. These data were related to surfactant function, Th(2) cytokine levels in BAL fluid and to the degree of eosinophilic inflammation. RESULTS: In patients with asthma, allergen challenge increased BAL levels of SP-B, SP-C and SP-D while SP-A was decreased. For SP-B and SP-D, a moderate increase was also observed after saline challenge. In contrast, no alterations were observed in healthy control subjects. Levels of SP-B and SP-C in asthmatics correlated with the ratio of small to large surfactant aggregates (SA/LA ratio) and correlated negatively with BAL surface activity. Furthermore, increased SP-C but not SP-B levels after allergen challenge correlated with eosinophil numbers, interleukin (IL)-5, and IL-13 in BAL while increased SP-D levels only correlated with eosinophil numbers. CONCLUSIONS: This study demonstrates significant alterations of all SPs in BAL fluid after allergen challenge of which SP-C was most closely related to surfactant dysfunction and the degree of the allergic inflammation.     

Lysophosphatidic acid is detectable in human bronchoalveolar lavage fluids at baseline and increased after segmental allergen challenge

BACKGROUND: Lysophosphatidic acid (LPA) is a biologically active lysophospholipid and a component of normal plasma. LPA binds to receptors expressed on circulating and structural lung cells and affects cell growth and activation. Whether LPA is present in the lung has not been previously reported. OBJECTIVE: To develop an assay to measure LPA in bronchoalveolar lavage (BAL) fluids, and to study the association between LPA and allergic airway inflammation. METHODS: Seventeen allergic subjects underwent bronchoscopy and segmental allergen challenge, followed 18 h later by BAL. Supernatants were analysed for LPA content using liquid chromatography and mass spectroscopy. Expression of LPA receptors on primary bronchial epithelial cells was analysed by immunolabelling, and the effects of LPA on epithelial cell barrier function was investigated by measuring transepithelial resistance. RESULTS: LPA was detectable in BAL from control lung segments, and significantly increased 18 h after allergen challenge. Polyunsaturated species of LPA were especially increased following segmental allergen challenge. LPA levels did not strongly correlate with the number or percentages of eosinophils, neutrophils of lymphocytes, whereas MIP-3alpha (CCL20) levels correlated significantly with the allergen-driven influx of lymphocytes. The levels of LPA from control sites correlated inversely with BAL protein content, suggesting that LPA promoted epithelial barrier integrity at baseline. Experiments using primary human bronchial epithelial cells confirmed that LPA tightened the epithelial cell barrier. CONCLUSION: Lysophosphatidic acid is detectable in human BAL fluids at baseline and its expression increases during allergic inflammation. LPA does not appear to be a dominant chemoattractant for eosinophils or lymphocytes during allergic airway inflammation. In the absence of ongoing inflammation, LPA may promote epithelial barrier integrity.     

Chemokine receptor expression on human eosinophils from peripheral blood and bronchoalveolar lavage fluid after segmental antigen challenge

BACKGROUND: The recruitment of circulating eosinophils to the lung is a characteristic feature of allergic airway inflammation. Chemokine receptors likely play a role in this complex process. However, reports of chemokine receptor expression on human eosinophils are conflicting. OBJECTIVE: The aim of this study was to determine whether the chemokine receptor profile of human eosinophils change when these cells are recruited to the airway after an antigen challenge and development of an allergic inflammatory response. METHODS: Blood and bronchoalveolar lavage (BAL) cells were obtained from 13 allergic subjects 48 hours after segmental bronchoprovocation with antigen. The CC chemokine receptor (CCR) 1 to 7, 9, and CXC chemokine receptor (CXCR) 1 to 4 were determined by flow cytometric analysis of whole blood and unseparated BAL cells. RESULTS: Compared with their circulating counterparts, airway eosinophils had decreased CCR3 and increased CCR4, CCR9, and CXCR3 expression on their cell surface. Furthermore, expression of CCR3, CCR4, and CXCR3 was significantly correlated with the percentage of eosinophils in BAL fluid at 48 hours. Eosinophils also expressed CXCR4, but this receptor did not change after antigen-induced recruitment to the airway. In contrast, the expression of CCR1, CCR2, CCR5, CCR6, CCR7, CXCR1, and CXCR2 remained undetectable on either blood or BAL eosinophils. CONCLUSIONS: Our data suggest that recruitment of eosinophils to the airway is associated with a modulation of their chemokine receptor profiles. These changes in chemokine receptors could be involved in determining eosinophil function and antigen-induced airway inflammation.     

Removal of bronchoalveolar cells augments the late eosinophilic response to segmental allergen challenge

BACKGROUND: In patients with quiescent asthma, macrophages are the most prevalent cells recovered by bronchoalveolar lavage (BAL). Through activation via their FcepsilonRII receptors or by acting as antigen-presenting cells, macrophages could, in theory, promote the late airway response to allergen. OBJECTIVE: In order to investigate the importance of macrophages and other airway luminal cells in inducing the late airway response, a novel washout experiment was designed. METHODS: Five patients with ragweed-allergic asthma underwent bronchoscopy and segmental bronchial challenge with either normal saline or short ragweed extract in two segments of one lung. In a third segment of the opposite lung, 12 successive BALs (25 mL each) were performed, followed by challenge with an identical dose of short ragweed (washed-challenged segment). After 24 h, all three challenged segments underwent BAL. RESULTS: Initially, in the washed-challenged segment, over 80% (mean 80.4%, range 68-88%) of the recoverable airway dwelling cells were removed. Unexpectedly, 24 h later these same washed-challenged segments contained more eosinophils in the BAL than the challenged segments from the opposite lung (P = 0.033). CONCLUSIONS: Removing the majority of airway luminal cells followed by allergen bronchoprovocation increased the number of eosinophils recovered 24 h after challenge. Our results suggest that in quiescent allergic asthma, the airway luminal cells are protective and attenuate the late eosinophilic response to allergen challenge.     

Increased expression of IL-16 immunoreactivity in bronchial mucosa after segmental allergen challenge in patients with asthma

BACKGROUND: We have previously shown increased expression of the CD4(+) cell chemoattractant IL-16 in bronchial mucosa of patients with asthma. We investigated the effects of allergen challenge on airway IL-16 expression. METHODS: We investigated the expression of IL-16 immunoreactivity in bronchial biopsy samples obtained from atopic asthmatic subjects (n = 19) and normal subjects (n = 6) 24 hours after segmental allergen challenge. Control biopsy samples were obtained either at baseline or after diluent challenge. IL-16 expression was correlated to numbers of CD4(+) cells, CD25(+) cells, and activated eosinophils. IL-16 bioactivity was assessed in bronchoalveolar fluid obtained from patients with asthma. RESULTS: IL-16 expression was higher in control biopsy specimens obtained from subjects with asthma compared with normal subjects (P<.05). In patients with asthma, numbers of IL-16 immunoreactive cells were significantly higher in biopsy specimens obtained after allergen challenge compared with control biopsy specimens (P<.001). Allergen provocation was associated with release of IL-16 in bronchoalveolar fluid in patients with asthma. In normal subjects, there was no difference in the number of IL-16-immunoreactive cells in biopsy specimens obtained after allergen challenge compared with biopsy specimens obtained after diluent challenge. Allergen challenge was associated with an increase in the numbers of EG2(+) eosinophils in patients with asthma but not in normal subjects. IL-16 expression correlated with the numbers of CD4(+) cells and CD25(+) cells after allergen challenge in asthmatic subjects with a provocative concentration required to decrease the FEV(1) by 20% of its baseline value (PC(20)FEV(1)) < 4 mg/mL. IL-16-immunoreactive cells were identified mainly as T cells and eosinophils in asthmatic subjects after allergen challenge. CONCLUSION: Endobronchial allergen provocation in atopic asthmatic patients resulted in increased airway expression of IL-16 and release of bioactive IL-16 in airways. IL-16 may contribute to the immunoregulation of the inflammatory infiltrate in the airways in response to antigen.     

Cytokine profile of bronchoalveolar lavage-derived CD4(+), CD8(+), and gammadelta T cells in people with asthma after segmental allergen challenge

T cell-derived cytokines play an important role in the pathogenesis of allergic asthma, but little is known about the cytokine profile of their different subsets. The aim of the present study was to investigate the cytokine production potential of CD4(+), CD8(+), or gammadelta(+) T cells derived from the bronchoalveolar space of mild atopic asthmatic subjects (n = 11) and nonatopic control subjects (n = 9) before and 24 h after segmental allergen challenge. The cytokine production was determined using the technique of intracellular cytokine detection by flow cytometry. Comparing asthmatic with control subjects we found no difference in the percentage of CD4(+), CD8(+), or gammadelta T cells in the bronchoalveolar lavage fluid before and after allergen challenge. Before allergen challenge the proportion of cells producing the cytokines interferon (IFN)-gamma, interleukin (IL)-2, IL-4, IL-5, and IL-13 was not different in CD4(+) and CD8(+) cells. The major difference between the groups was an increased percentage of positive-staining cells for the T helper-(Th)2-cytokines IL-5 and IL-13 in the gammadelta T-cell subset. After allergen challenge, all T-cell subsets revealed a decreased proportion of cells producing the Th1-type cytokines IFN-gamma and IL-2. The percentage of IL-4- and IL-5-positive cells did not change in all subsets, and there was a decreased proportion of IL-13- positive cells in the CD4(+) subset. These findings indicate an increased Th2-cytokine profile in gammadelta T cells. After allergen challenge, the dysbalance between Th1 and Th2 cytokines was further accentuated by a reduction in Th1 cytokine-producing T cells.     

Down modulation of L-Selectin expression on eosinophils recovered from bronchoalveolar lavage fluid after allergen provocation

In allergic asthma eosinophils infiltrate into the lung after allergen challenge. The mechanism of this cellular infiltration is not fully understood. L-Selectin is involved in leucocyte-endothelial cell recognition and participates in homing of leucocytes into sites of inflammation. To find indications for a role of L-Selectin in the migration of eosinophils to the bronchoalveolar space we measured L-Selectin expression on eosinophils in peripheral blood and bronchoalveolar lavage fluid (BAL) 4 hr after the early allergic reaction after allergen challenge. Nine patients with allergic asthma participated in the study. An eosinophil specific high depolarization signal enabled us to measure L-Selectin expression on eosinophils in a FACS analysis without isolation of these cells. Eosinophils recovered from BAL showed a strong decrease of L-Selectin expression compared to blood eosinophils. This decrease in L-Selectin expression can be induced in vitro by activation of eosinophils with PMA or FMLP whereas priming of eosinophils during several hours with GM-CSF did not influence L-Selectin expression. Our results are a first indication that L-Selectin may play a role during homing of eosinophils in the lung in asthma after allergen challenge. Moreover, the low expression of L-Selectin on eosinophils in the lung is a further indication that these cells exhibit an activated phenotype.     

Segmental allergen challenge in patients with atopic asthma leads to increased IL-9 expression in bronchoalveolar lavage fluid lymphocytes

BACKGROUND: IL-9 is a T(H)2 cell-derived cytokine that might be involved in the pathophysiology of allergic diseases. Little is known about its expression and release during the allergic response in the human lung. OBJECTIVE: The expression of IL-9 was measured in 10 atopic subjects with mild asthma and 5 nonatopic healthy control subjects at baseline and 24 hours after segmental sham and allergen challenge. METHODS: IL-9 protein was measured in bronchoalveolar lavage (BAL) fluid by means of ELISA and detected within the BAL cells by means of immunocytochemistry. Furthermore, IL9 mRNA expression of BAL cells was detected by means of real-time PCR. RESULTS: Although only low or undetectable amounts of IL9 mRNA and IL-9 protein were present in nonatopic control subjects and atopic asthmatic patients at baseline, there was an increase after segmental allergen challenge in the atopic subjects. Lymphocytes were identified as major cellular sources of IL-9 production by means of immunocytochemistry. Furthermore, IL-9 protein and IL9 mRNA expression correlated with eosinophil numbers in BAL fluid. CONCLUSIONS: These findings demonstrate that IL-9 is specifically upregulated after local allergen challenge in the lungs of atopic asthmatic patients. Lymphocytes are the major cellular source of IL-9. The increased expression and its correlation with eosinophil numbers suggest a potential role for IL-9 in the late phase of the allergic response.     

Comparison of inflammatory cell counts in asthma: induced sputum vs bronchoalveolar lavage and bronchial biopsies

Background Induced sputum potentially allows monitoring of airway inflammation in patients with asthma in a non-invasive way. However, the relationship between the cellular content in sputum and airway tissue has not been fully clarified. Objective We compared the cellular compositions of hypertonic saline-induced sputum, bronchoalveolar lavage fluid (BAL) and bronchial biopsies in 18 clinically stable patients with mild to moderate atopic asthma (baseline FEV₁: range 61–114%pred, PC₂₀ methacholine: 0.04–4.7 mg/mL). They were treated with inhaled short-acting bronchodilators on demand, with (n = 8) or without (n= 10) regular inhaled steroids. Methods Each patient underwent sputum induction and fiberoptic bronchoscopy on separate days in random order. Differential cell counts of induced sputum, bronchoalveolar lavage and bronchial wash were determined on May-Grünwald-Giemsa stained cytospins. Flow cytometry was performed on sputum and BAL samples. Immunohistochemical techniques were used to stain inflammatory cells in 6 μm cryostat sections of bronchial biopsies. Results Sputum cell differentials were not different between the patients with and without inhaled steroids, and showed a median value of 19.4% squamous cells, with 1.0% eosinophils, 3.3% lymphocytes, 28.7% neutrophils, 49.4% macrophages and 6.9% cylindric epithelial cells (in percentage non-squamous cells). The percentage eosinophils in sputum was significantly correlated with their percentage in bronchial wash(R_s= 0.52, P = 0.03) and in BAL (R_s= 0.55,P = 0.02), whilst there was a trend towards such a correlation between the number of eosinophils/mL sputum and the number of EG2⁺ eosinophils/mm² lamina propria in bronchial biopsies (R_s= 0.44,P= 0.07). In addition, the percentage of CD4⁺ lymphocytes correlated between sputum and BAL (R_s= 0.55, P= 0.03). Conclusion We conclude that the eosinophil counts in hypertonic saline-induced sputum from patients with asthma are related to those in bronchial wash and BAL and, to a lesser extent, with the counts in bronchial biopsies. This suggests that induced sputum can be used to monitor the presence and severity of airway inflammation in asthma.     

Basic fibroblast growth factor in asthma: measurement in bronchoalveolar lavage fluid basally and following allergen challenge

Airway remodeling in asthma refers to a collection of chronic structural changes including subepithelial fibrosis, airway smooth muscle hypertrophy/hyperplasia, and possibly angiogenesis. The mechanisms leading to remodeling are not well defined. One molecule of possible relevance is basic fibroblast growth factor (bFGF), which is a potent mitogen for fibro-blasts, airway smooth muscle cells, and endothelial cells. To test the hypothesis that bFGF expression is increased in asthma, we measured levels of the growth factor in bronchoalveolar lavage (BAL) fluid. Basally, BAL fluid bFGF concentrations were significantly higher in subjects with atopic asthma than in control subjects without asthma (median 0.22 vs 0.06 pg/mL, P = .003). The effect of acute allergen exposure was examined with a segmental bronchoprovocation model in a separate group of subjects with atopic asthma. Ten minutes after segmental bronchoprovocation there was a 5-fold increase in bFGF levels in BAL fluid recovered from allergen-challenged sites compared with control saline-challenged sites (1.52 vs 0.30 pg/mL, P < .002). We conclude that basal levels of BAL fluid bFGF are increased in atopic asthma and that a further increase occurs in response to acute allergen exposure. These findings lend support to the hypothesis that bFGF is implicated in airway remodeling in asthma.     

Total and specific IgE in serum, bronchial lavage and bronchoalveolar lavage of asthmatic patients

Total and specific IgE were assessed in serum, bronchial lavage (BL) and broncho-alveolar lavage (BAL) of allergic asthmatics and healthy controls. Serum total IgE were found to be correlated with total IgE in BAL but not in BL. Total IgE/K⁺ ratio in serum and BL was higher in asthmatics than in controls, while the total IgE/albumin ratio was significantly higher in asthmatics than in controls in serum but not in BL and BAL. The mean of specific IgE in serum and BL was significantly higher in the group of patients with positive specific bronchial provocation test (sBPT) than in the group with negative sBPT. Similar results were observed between specific IgE serum level and BL and prick tests (PT). which show that BL does not always reflect the total IgE level of serum; in asthmatics, albumin can not be used to determine the degree of dilution in the recovered fluids; as in the serum, there is agreement between specific IgE in BL and PT or sBPT results.     

急慢性MCMV感染对小鼠脾细胞Foxp3/T-bet/GATA-3蛋白表达水平的影响

目的：在整体水平研究鼠巨细胞病毒（MCMV）感染对小鼠辅助性T细胞亚群Th1、Th2和调节性T细胞（Treg）分化特异性转录因子T-bet、GATA-3和Foxp3蛋白表达水平的影响。方法：建立MCMV播散型感染模型,依据主要脏器内病毒滴度,确定感染后28天为本模型急、慢性期界定点。42只模型鼠分别于接种MCMV Smith株后第1、3、7、14、28、45天和60天各处死6只,分离脾细胞;另设42只正常小鼠作为模拟感染对照。Western blot法检测脾细胞中特异转录因子T-bet、GATA-3和Foxp3蛋白表达水平。结果：MCMV感染后第3天T-bet蛋白表达显著增高达峰值,与模拟感染对照组比较有显著差异（P〈0.01）,随后下降,第28天后降至模拟感染对照组相当水平;而GATA-3蛋白表达在感染后第3天开始升高,第7天达峰值（P〈0.01）,第14天开始缓慢下降,但至第60天仍显著高于模拟感染对照组（P〈0.05）;Foxp3蛋白表达在感染后7天明显低于模拟感染对照组,第28天降至最低（P〈0.01）,第45天和60天表达明显上调,并显著高于模拟感染对照组水平（P〈0.05）。结论：感染急性期,MCMV上调Th1/Th2特异性转录因子T-bet和GATA-3的蛋白表达;感染慢性期,MCMV诱导Treg特异性转录因子Foxp3蛋白表达上调,同时显著抑制T-bet和GATA-3蛋白表达,提示CMV诱导Foxp3表达增加可能是其抑制宿主抗病毒免疫,导致慢性持续性感染的重要原因。     

维药祖发奇尼对哮喘大鼠肺组织T-bet、GATA-3、STAT-3 mRNA表达水平的影响

目的:研究维吾尔药祖发奇尼对哮喘大鼠肺组织T-bet、GATA-3、STAT-3 mRNA的表达水平的影响,探讨祖发奇尼治疗哮喘的免疫机制。方法:将大鼠随机分为正常对照组,哮喘模型组,地塞米松治疗组及祖发奇尼高、低剂量治疗组。采用卵清白蛋白(OVA)、氢氧化铝[Al(OH)3]及百白破疫苗联合致敏和OVA生理盐水雾化激发的方法制备哮喘模型。采用逆转录聚合酶链反应(RT-PCR)方法检测各组大鼠肺组织T-bet、GATA-3、STAT-3 mRNA的表达水平。结果:正常对照组与哮喘模型组、哮喘模型组与各治疗组大鼠肺组织T-bet、GATA-3、STAT-3 mRNA的表达水平差异均有统计学意义(P<0.05);与模型组比较,祖发奇尼治疗后哮喘大鼠肺组织GATA-3、STAT-3 mRNA的表达水平显著降低(P<0.05),而T-bet的表达水平显著增高(P<0.05);祖发奇尼高剂量治疗组大鼠肺组织GATA-3、STAT-3 mRNA的表达水平明显低于低剂量治疗组(P<0.05),而T-bet的水平明显高于低剂量治疗组(P<0.05)。各组大鼠肺组织T-bet mRNA和GATA-3 mRNA表达水平呈负相关关系(r=-0.696),STAT-3mRNA表达水平与T-bet mRNA和GATA-3 mRNA表达水平分别呈负、正相关(r=-0.767,r=0.772),P值均<0.05。结论:祖发奇尼可能在转录水平对Th1、Th2和Th17的分化进行调节,发挥抗炎作用。     

Eotaxin-2 and eotaxin-3 expression is associated with persistent eosinophilic bronchial inflammation in patients with asthma after allergen challenge

BACKGROUND: Eotaxin-1, eotaxin-2, and eotaxin-3 are chemokines involved in the activation and recruitment of eosinophils through activation of their main receptor, CC chemokine receptor 3. The differential roles of these chemokines still remain to be established. It has been suggested that eotaxin-1 is an important mediator in the early phase of allergen-induced recruitment of eosinophils into the airways. Eotaxin-2 and eotaxin-3 might play a role in the subsequent persistence of allergen-induced bronchial eosinophilia. OBJECTIVE: The aim of this study was to determine the expression of eotaxins and eosinophil counts in the bronchial mucosa of subjects with mild asthma after resolution of the late-phase asthmatic response (LAR). METHODS: The expression of eotaxins and eosinophil counts were determined in bronchial biopsy specimens obtained from 10 subjects with mild asthma 48 hours after diluent and allergen challenge by using immunohistochemistry. Positively stained cells were counted in a 125-mum-deep zone of the lamina propria. RESULTS: Eotaxin-2 and eotaxin-3 expression in bronchial mucosa was significantly increased 48 hours after allergen challenge ( P = .001 and P = .013, respectively). At this time point, when marked tissue eosinophilia was still present, these increases were positively correlated with the magnitude of the LAR ( r = 0.72, P = .019 and r = 0.64, P = .046, respectively). Furthermore, eotaxin-2 expression was associated with the number of eosinophils after allergen challenge ( r = 0.72, P = .018). CONCLUSION: Our findings suggest that eotaxin-2 and eotaxin-3 might account for the persistence of bronchial eosinophilia after resolution of the LAR.