内毒素在小鼠过敏性哮喘模型所起作用的实验研究

目的建立小鼠过敏性哮喘模型,在过敏原的致敏和激发阶段给予不同剂量内毒素(即脂多糖LPS),探讨内毒素在哮喘模型中的作用机制。方法建立BALB/c小鼠哮喘模型,设立实验组和对照组开展后续实验。实验组包括:鸡卵清白蛋白(OVA)致敏,OVA激发组;OVA致敏,LPS激发组;OVA致敏,OVA+LPS联合激发组;LPS暴露于OVA致敏前,OVA激发组;对照组包括试剂对照组和健康对照组。各实验组的LPS剂量均分为高、中、低三个剂量组。通过测定小鼠气道阻力和肺顺应性来反映其肺功能改变;流式细胞术(FCM)测定FITC、PE阳性细胞数,表征CD4+CD2+5调节性T淋巴细胞(以下简称Treg细胞)的相对比例;荧光实时聚合酶链反应定量测定肺脏和脾脏Foxp3mRNA表达的水平;ELISA法测定血浆总IgE和OVA特异性IgE水平,抗体夹心ELISA法测定支气管肺泡灌洗液(BALF)中Th2细胞因子(IL-4和IL-5)的水平;计数BALF中白细胞总数和嗜酸性粒细胞等各类白细胞所占百分比;常规病理切片观察肺组织改变情况。结果结果表明,与哮喘模型组小鼠相比,在LPS各处理组中,总体上能诱导Treg细胞的产生,改善肺功能,降低IgE滴度,降低Th2介导的免疫反应,同时诱导肺部炎症。尤其是在致敏阶段腹腔注射内毒素可以缓解由过敏原诱导的气道炎症和改善肺功能,诱导肺组织和脾组织Foxp3mRNA表达的增加。结论LPS抑制了Th2介导的过敏反应,可能与Foxp3表达量的增加相关,后者诱导Treg细胞增殖,对哮喘症状起到缓解作用。     

CD4^＋CD25^＋调节性T细胞对哮喘大鼠气道炎症的影响

目的观察CD4^＋CD25^＋调节性T细胞（CD4^＋CD25^＋Treg）对哮喘大鼠气道炎症的影响。方法将卵白蛋白（OVA）免疫耐受大鼠CD4^＋CD25^＋Treg细胞过继转移给哮喘大鼠,然后观察支气管肺泡灌洗液（BALF）中细胞计数及分类,ELISA检测BALF中IL-4、IL-5和IFN-1及血清OVA特异性IgE含量,HE染色观察肺组织的病理改变。结果与哮喘组比较,过继转移CD4^＋CD25^＋Treg细胞后哮喘大鼠BALF中细胞总数、中性粒细胞和淋巴细胞百分率降低（P〈0．05）,嗜酸性粒细胞（Eos）百分率明显降低（P〈0．01）;BALF中IL4和IL-5含量明显降低,IFN-1含量明显升高,血清OVA特异性IgE含量明显降低（P〈0．05）;气道炎症明显减轻。结论过继转移OVA免疫耐受大鼠CD4^＋CD25^＋Treg细胞可以明显抑制哮喘的慢性气道炎症。     

磷酸酰肌醇-3激酶抑制剂对小鼠气道炎症影响的实验研究

目的观察磷酸酰肌醇-3激酶(PI3K)抑制剂LY294002对卵白蛋白(OVA)诱导哮喘小鼠气道炎症的影响。方法Balb/c小鼠30只,随机分为三组,每组10只:PI3K抑制剂治疗组(LY组),OVA组和正常对照组(NC组)。通过OVA多次腹腔注射致敏和反复雾化激发,建立哮喘小鼠模型。末次抗原激发后48h收集支气管肺泡灌洗液(BALF)和骨髓标本,计数细胞总数和嗜酸性粒细胞(Eos),并行肺组织学检查。结果与OVA组比较,LY组BALF中细胞总数及Eos绝对数明显减少(p<0.05);肺组织中细支气管、血管周围Eos浸润得到控制,气道粘液分泌减少。结论PI3K抑制剂(LY294002)对卵白蛋白(OVA)致敏的哮喘小鼠气道炎症具有抑制作用。     

影响子代哮喘发生的小鼠孕期多环芳烃暴露模型的构建

目的建立小鼠孕期暴露于多环芳烃混合物的模型,明确多环芳烃是否加重子代哮喘小鼠肺部气道炎症反应。方法采用滴鼻方式对怀孕小鼠进行多环芳烃混合物暴露,并用超高效液相色谱串联质谱法测定孕鼠尿液中多环芳烃羟基代谢物1-羟基芘(1-OHP)的含量;对子代小鼠用致敏原卵清蛋白(OVA)致敏,通过观察子代小鼠肺组织病理形态学变化,计数支气管肺泡灌洗液(BALF)中炎症细胞的数量,测定BALF中炎症相关细胞因子IL-4以及血清中卵清蛋白特异性IgE抗体的表达。结果多环芳烃暴露孕鼠尿中1-OHP含量为8.28μmol/mol肌酐,验证了多环芳烃孕期暴露的有效性。与对照组子代小鼠相比,哮喘组和多环芳烃暴露哮喘组BALF中炎性细胞明显增多,支气管局部黏膜上皮受损脱落,管壁各层充血及水肿,周围大量炎性细胞浸润,气道壁杯状细胞增生,BALF中IL-4以及血清中总Ig E明显增高。结论通过滴鼻给药的方法成功构建了影响子代哮喘发生的小鼠孕期多环芳烃暴露模型。     

皮肤暴露邻苯二甲酸二丁酯对小鼠过敏性哮喘的影响

目的 探究皮肤暴露邻苯二甲酸二丁酯(Dibutyl phthalate,DBP)对过敏性哮喘的影响.方法 30只Balb/c雄性小鼠随机分为5组:(1)对照组;(2) Ovalbumin (OVA)致敏组;(3)4 mg/kg/d DBP+ OVA组;(4) 40 mg/kg/d DBP+ OVA组;(5)400 mg/kg/d DBP+ OVA组.第1～5组小鼠每天皮肤暴露于生理盐水或不同浓度的DBP,连续28 d.第2～5组小鼠分别在实验的11、18及25 d腹腔注射OVA致敏液,并且在第29～35 d进行每日一次每次30 min的OVA(1％)雾化,构建小鼠过敏性哮喘模型.第36 d处死实验小鼠,取肺组织和血清,使用ELISA法检测肺组织中的白介素-4(interleukin-4,IL-4)、干扰素-γ(interferon-γ,IFN-γ)和血清中的免疫球蛋白E(immunoglobulin E,IgE)含量.同时,采用HE染色法观察小鼠肺部气道的病理学变化.结果 与过敏性小鼠模型组相比,DBP皮肤暴露会提高肺组织中IL-4和血清中IgE的含量,具有统计学意义(P＜0.01).同时,会显著的加重小鼠肺组织的气道重塑和炎性细胞浸润等病理学变化.结论 长期皮肤暴露于DBP(＞4 mg/kg/d)会诱导小鼠产生过敏性体制,加重过敏原诱导过敏性哮喘.     

不同剂量卵蛋白诱发幼年大鼠支气管哮喘模型的比较

目的：利用不同剂量的卵清蛋白（OVA）诱导大鼠,探索建立-个稳定、理想的大鼠支气管哮喘模型。方法：用低、中、高剂量卵清蛋白致敏大鼠后再雾化吸人同-致敏原从而诱发大鼠哮喘发作,分别观察各组大鼠肺组织病理切片、支气管肺泡灌洗液（BALF）中细胞计数和分类以及双抗体夹心酶联免疫吸附试验法检测BALF中OVA特异性IgE（OVA--IgE）以及外周血和BALF自细胞介素（IL-4）和干扰素-Y（interferOn～7,IFN-y）水平。结果：3个模型组大鼠较正常对照组均出现哮喘异常症状,但高剂量组有明显的腹式呼吸和呼吸短促,且高剂量组肺组织病理显示气道炎症较低、中剂量组明显严重,3个模型组的BALF中细胞总数较对照组均有不同程度增高,且高剂量组增高有显著性（P〈0．05）;中、高剂量组的嗜酸粒细胞较对照组增高,且3个剂量组之间差异均有显著性（分别为P〈O．05和P〈O．01）。中、高剂量组的淋巴细胞较对照组增高均有显著性（分别为P〈O．05和P〈O．01）。中、高剂量组较低剂量组显著升高（P均〈O．05）。高剂量组大鼠血清中IL-4和BALF中0VrA-IgE较对照组和低、中剂量组增高有显著性（P〈O．05）,中剂量组BALF中OVA—IgE较对照组增高有显著性（P〈O．05）。高、中剂量组较低剂量组和对照组IFN-7下降,差异均有显著性（P分别〈O．01和〈O．05）。结论：幼年大鼠哮喘模型中的致敏原剂量的大小与哮喘气道变应性炎症的程度有关,大剂量腹腔注射OVA是-种操作简便的诱发大鼠哮喘模型的方法,成功率高,重复性好,值得动物实验推广使用。     

细胞因子IL-12在哮喘小鼠发病机制中的作用

目的探讨白细胞介素-12(IL-12)在哮喘小鼠发病机制中的作用及对气道炎症的影响。方法 65只小鼠随机分为对照组(A组)、哮喘组(B组)、重组白细胞介素-12(rm IL-12)组(C组)和IL-12基因敲除组(D组),以卵白蛋白(OVA)致敏和激发制备哮喘模型。C组在每次激发前30 min给予rm IL-12腹腔注射,D组在激发前1 d给小鼠植入含有抗IL-12多克隆抗体的缓释泵,A组小鼠在末次激发后24 h处死,其余三组小鼠在末次激发后的1 d、2 d、4 d、7 d分别处死。摘眼球取血进行血浆一氧化氮(NO)和免疫球蛋白E(Ig E)的检测。收集各组小鼠的支气管肺泡灌洗液(BALF),ELISA法检测其上清中白细胞介素-10(IL-10)、IL-12、肿瘤坏死因子-α(TNF-α)含量。离心后的细胞沉淀行白细胞总数和嗜酸性粒细胞(EOS)分类计数;剪下结扎右肺下叶用于HE染色。结果(1)细胞计数:小鼠BALF中的细胞总数和EOS百分比,B组明显高于A组(P0.05),C组明显低于B组(P0.05),D组较B组明显升高(P0.05)。(2)ELISA检测:与A组相比,B组小鼠BALF中IL-10、IL-12水平明显降低(P0.05),TNF-α、NO、Ig E水平明显升高(P0.05)。与B组相比,C组小鼠BALF中IL-10、IL-12水平明显升高,TNF-α、NO、Ig E水平明显降低;D组小鼠TNF-α、NO、Ig E水平明显升高,IL-10、IL-12水平明显降低;于1 d、2 d、4 d、7 d差异均有统计学意义(P0.05)。(3)肺组织病理改变:A组小鼠HE染色未见异常;B组小鼠肺泡间隔及小血管周围可见大量炎性细胞浸润;C组小鼠的炎性细胞浸润较B组缓解;D组小鼠部分可见小气道管腔完全闭塞,炎性细胞浸润较B组明显加重。结论 rm IL-12能够明显抑制哮喘小鼠炎症细胞的浸润,同时降低炎症因子TNF-α、NO和Ig E的表达,促进抑炎因子IL-10的表达,从而在哮喘发病过程中起到保护作用。     

支气管哮喘气道IL4和IL12动态变化及对气道炎症反应的影响

目的研究支气管哮喘(哮喘)﹚炎症促进因子白细胞介素4(IL-4)和炎症抑制因子(IL-12)的变化趋势,相互关系及对气道炎症反应的影响.方法用卵蛋白(OVA)﹚敏原制备wistar大鼠哮喘模型,在激发后1、8、24、48、96h及7、14d行支气管肺泡灌洗(BAL),测定支气管肺泡灌洗液(BALF)中炎症细胞总数与嗜酸细胞数(EOS);酶联免疫吸附法(ELISA)测定BALF中IL-4、IL-12的浓度.结果 OVA激发后,气道出现明显的炎症反应.EOS计数1h上升,8h后迅速上升,24h达到高峰期,96h后开始回落,7～14d回落到略高于对照组;炎症细胞总数1h上升,8h后迅速上升,24～96h处于高峰期,7d回落到接近8h水平,14d接近基础水平.BALF中,IL-4在1h上升,8～96h处于高峰期,7～14d回落到基础水平;IL-12在1h上升,8处于低水平,24h上升,48～96h处于高峰期,7～14d回落到基础水平;EOS与IL-4有正相关性(r=0.74,P＜0.001),与IL-12无相关性(r=-0.13,P＞0.05),与IL-4/IL-12有密切相关性(r=0.85,P＜0.001).结论哮喘气道中存在IL-4/IL-12比值失衡,IL-4/IL-12比值对哮喘气道炎症反应起重要的调节作用.     

复方甘草酸苷对哮喘大鼠气道炎症的影响

目的探讨复方甘草酸苷对哮喘大鼠气道炎症的影响及其机制。方法40只SPF级Wistar大鼠随机分成健康对照组（Ⅰ组）、哮喘模型组（Ⅱ组）、复方甘草酸苷哮喘治疗组（Ⅲ组）、哮喘治疗阴性对照组（Ⅳ组）,10只／组,Ⅱ、Ⅲ、Ⅳ组大鼠用卵清蛋白（OVA）氢氧化铝混合液腹腔注射致敏和OVA超声雾化吸入激发建立哮喘大鼠模型,Ⅲ组大鼠每次激发前1h腹腔注射复方甘草酸苷200μg,Ⅳ组大鼠每次激发前用等体积生理盐水代替复方甘草酸苷腹腔注射,Ⅰ组大鼠腹腔注射用等体积生理盐水代替OVA氢氧化铝混合液,超声雾化吸入用等体积生理盐水代替OVA。所有大鼠在末次激发后6h取中心静脉血2ml测定IgE含量,取左肺支气管肺泡灌洗液（BALF）行细胞计数与分类,并测定BALF中细胞因子IL4、IL-5、IL-13及IFN-γ含量。结果Ⅱ组静脉血IgE含量及BALF中中性粒细胞、淋巴细胞、嗜酸性粒细胞计数和IL-4、IL-5、IL-13含量显著高于Ⅰ组和Ⅲ组（P〈0．01）,IFN-γ含量显著低于Ⅰ组和Ⅲ组（P〈0．01）;Ⅱ组与Ⅳ组各项指标差异均无统计学意义（P〉0．05）;Ⅲ组与Ⅰ组相比,IgE含量及中性粒细胞、淋巴细胞、嗜酸性粒细胞计数和IL4、IL-5及IL-13含量升高,单核巨噬细胞计数和IFN-γ含量降低,但均无统计学意义（P〉0．05）。结论复方甘草酸苷可能通过调节Th1／Th2细胞因子平衡,来抑制Th2细胞免疫学效应,促进Th1细胞免疫学效应,从而减轻气道炎症,降低气道高反应性。     

乙酰半胱氨酸对肥胖哮喘小鼠气道炎症和重建的作用

目的探讨乙酰半胱氨酸对哮喘气道炎症和重建的影响。方法60只雌性C57／6J小鼠按随机数字表法分为哮喘组（A组）,肥胖哮喘组（B组）,治疗组（C组）,对照组（D组）,每组15只。经腹腔注射与雾化吸入卵蛋白（OVA）制作慢性哮喘模型,高脂饮食制造肥胖模型。计数支气管肺泡灌洗液（BALF）中细胞总数及分类,ELISA法测定肺组织匀浆中IL-6和8-异前列腺素F2α（8-iso-PGF2α）水平,肺组织切片观察各组小鼠病理变化,并测定气管壁面积（WAt）、气管平滑肌面积（WAm）、管腔基底膜周长（Pbm）。结果,A组、B组小鼠BALF中白细胞总数及嗜酸性粒细胞比例、肺组织IL-6水以及病理切片中气管壁厚度（WAt／Pbm）、气管平滑肌厚度（WAm／Pbm）均较D组明显增加,且B组IL-6和WAt／Pbm较A组进一步增加（P〈0．05）。C组小鼠BALF中白细胞总数、IL-6和WAt／Pbm均较B组明显下降（P〈0．05）。四组小鼠肺组织匀浆8-iso—PGF2α水平按D组、C组、A组、B组依次升高,各组差异有统计学意义（F=101．8,P〈0．01）。Pearson相关分析表明,8-iso—PGF2α水平与肺组织IL-6水平和WAt／Pbm和呈正相关（r=0．817、0．737,P〈0．01）。结论乙酰半胱氨酸能够通过抑制氧化应激反应,抑制哮喘小鼠的气道炎症和气道重建。     

Anti-inflammatory activity of sublingual immunoglobulin (SLIG) in a murine model of allergen-driven airway inflammation

Aim

Intravenous immunoglobulin (IVIG) displays anti-inflammatory activities in many diseases. Subcutaneous administration of anti-IgE in humans provides benefit in severe persistent allergic asthma. Given the well established efficacy of sublingual allergen immunotherapy in respiratory type I allergies, we investigated the therapeutic potential of sublingual immunoglobulin (SLIG), most particularly anti-IgE SLIG, in a murine model of allergen-driven airway inflammation.

Methods

BALB/c mice sensitized with ovalbumin (OVA) were treated sublingually with rat monoclonal IgG1 or IgG2a, either directed to mouse IgE or with no reported specificity. Airway hyperresponsiveness (AHR) was assessed by whole body plethysmography, and eosinophil infiltrates were characterized in bronchial alveolar lavages (BAL). OVA-specific antibody and T cell responses were analyzed in sera and saliva or lung and draining lymph nodes, by ELISA or CBA measurement of cytokine production, respectively.

Results

AHR and BAL eosinophil infiltrates were substantially decreased in mice treated sublingually with particulate OVA (positive control), as well as in animals receiving various rat IgG1, irrespective of their specificity for murine IgE. In contrast, no improvement was observed in mice treated with PBS (negative control) or various rat IgG2a. SLIG anti-inflammatory activity is not related to a downregulation of Th2, Th17 or an induction of Foxp3⁺ CD4⁺ regulatory T cell responses. Mass spectrometry analysis of glycan moieties, such as sialic acid, suggests that the differential efficacy of rat IgG1 and IgG2a is not related to their capacity to interact with lectins borne by oral immune cells.

Conclusions

In a murine model of allergen-driven airway inflammation, SLIG exhibits an anti-inflammatory activity irrespective of the immunoglobulin specificity, and in the absence of allergen. As a noninvasive approach, SLIG deserves to be further studied as a treatment for other inflammatory diseases beyond allergic asthma.     

In utero exposure to environmental tobacco smoke potentiates adult responses to allergen in BALB/c mice

BACKGROUND: Fetal stress has been linked to adult atherosclerosis, obesity, and diabetes. Epidemiology studies have associated fetal exposure to maternal smoking and postnatal exposure to environmental tobacco smoke (ETS) with increased asthma risk. OBJECTIVE: We tested the hypothesis, in a mouse model of asthma, that in utero ETS exposure alters airway function and respiratory immune responses in adults. METHODS: Pregnant Balb/c mice were exposed daily to ETS or HEPA-filtered air (AIR). Offspring inhaled aerosolized ovalbumin (OVA) or saline in weeks 7-8. Regardless of whether they inhaled OVA or saline, mice were sensitized by OVA injections in weeks 11 and 13 followed by OVA aerosol challenge in weeks 14-15. At three time points, we assessed OVA-specific serum immunoglobins, bronchoalveolar lavage cells and cytokines, lung and nasal histopathology, and airway hyperresponsiveness (AHR). RESULTS: At 6 weeks, we found no significant differences between in utero ETS and AIR mice. At 10 weeks, following OVA aerosol, ETS mice displayed greater AHR than AIR mice (alpha = 0.05), unaccompanied by changes in histopathology, cytokine profile, or antibody levels. At 15 weeks, mice that had inhaled saline in weeks 7-8 developed airway inflammation: eosinophilia (alpha = 0.05), interleukin-5 (alpha = 0.05), and AHR (alpha = 0.05) were greater in ETS mice than in AIR mice. Mice that had inhaled OVA in weeks 7-8 demonstrated no airway inflammation after sensitization and challenge. CONCLUSION: In utero ETS exposure exacerbates subsequent adult responses to initial allergen exposure.     

Liposomal retinoic acids modulate asthma manifestations in mice

Signaling of all-trans retinoic acid (ATRA) through nuclear retinoid acid (RA) receptors regulates several biological functions in airway epithelial cells, eosinophils, and immune cells, yet its impact on different in vivo aspects of pulmonary allergic reaction remains elusive. We compared the effect of a treatment with liposomally encapsulated ATRA (Lipo-ATRA) in a mouse model of ovalbumin (OVA)-induced T helper (Th) 2-type responses and airway remodeling. Daily intraperitoneal injections of 10 mg/kg Lipo-ATRA, at the time of each of the 2 systemic sensitizing injections, increased OVA-induced Immunoglobulin E synthesis, bronchoalveolar lavage (BAL) eosinophilia, and accumulation of IL-5, transforming-growth factor beta1, fibronectin, eotaxin/chemokine (C-C motif) ligand 11 (eotaxin/CCL11) and regulated upon activation, normal T expressed and secreted chemokine (C-C motif) ligand 5. In contrast, Lipo-ATRA, administered during each of the 4 intranasal OVA challenges, did not affect these variables. Regardless of the treatment regimen, Lipo-ATRA augmented mucin levels in BAL fluid and reduced lung total collagen content. In vitro incubation of mouse splenocytes or purified spleen cluster of differentiation (CD) 4-positive T lymphocytes, with ATRA, increased, respectively, OVA- and anti-CD 3 antibody-induced IL-4 and IL-5 production and inhibited IFNgamma release. These findings demonstrate that, when given during systemic sensitization, Lipo-ATRA exacerbates allergic immune and inflammatory responses, most likely by promoting Th2 development.     

γ-维生素E对哮喘小鼠血清及肺泡灌洗液嗜酸性粒细胞趋化因子的影响

目的 探讨γ-维生素E(γ-T)对哮喘的治疗作用及机制。方法 将40只雄性Balb/c小鼠(4周,18~20 g)随机分为正常组、哮喘组、地塞米松组及γ-T治疗组。给予小鼠腹腔注射及雾化吸入卵白蛋白建立哮喘气道炎症反应模型,分别给予地塞米松及γ-T,正常组仅给予生理盐水。28 d后处死小鼠,留取血清及肺泡灌洗液。ELISA法测定各组血清及肺泡灌洗液中嗜酸性粒细胞趋化因子(eotaxin)的含量。用one-way ANOVA检验组间差异,P＜0.05具有统计学意义。结果 哮喘组小鼠血清及肺泡灌洗液中eotaxin浓度均较正常组升高,地塞米松组及γ-T组均较哮喘组下降。在血清中地塞米松组下降最明显,γ-T组次之,γ-T组与哮喘组,γ-T组与地塞米松组相比差异无统计学意义(P>0.05);在BALF中,γ-T组的eotaxin下降最明显,与哮喘组相比,二者间差异明显(P<0.05);γ-T组与地塞米松组相比,二者差异无统计学意义(P>0.05)。 结论 γ-T有利于减少哮喘小鼠肺组织eotaxin,γ-T可能是有用的抗哮喘药物。     

Murine Lung Responses to Ambient Particulate Matter: Genomic Analysis and Influence on Airway Hyperresponsiveness

Background

Asthma is a complex disease characterized by airway hyperresponsiveness (AHR) and chronic airway inflammation. Epidemiologic studies have demonstrated that exposures to environmental factors such as ambient particulate matter (PM), a major air pollutant, contribute to increased asthma prevalence and exacerbations.

Objective

We investigated pathophysiologic responses to Baltimore, Maryland, ambient PM (median diameter, 1.78 μm) in a murine model of asthma and attempted to identify PM-specific genomic/molecular signatures.

Methods

We exposed ovalbumin (OVA)-sensitized A/J mice intratracheally to PM (20 mg/kg), and assayed both AHR and bronchoalveolar lavage (BAL) on days 1, 4, and 7 after PM exposure. Lung gene expression profiling was analyzed in OVA- and PM-challenged mice.

Results

Consistent with this murine model of asthma, we observed significant increases in airway responsiveness in OVA-treated mice, with PM exposure inducing significant changes in AHR in both naive mice and OVA-induced asthmatic mice. PM evoked eosinophil and neutrophil infiltration into airways, elevated BAL protein content, and stimulated secretion of type 1 T helper (T_H1) cytokines [interferon-γ, interleukin-6 (IL-6), tumor necrosis factor-α] and T_H2 cytokines (IL-4, IL-5, eotaxin) into murine airways. Furthermore, PM consistently induced expression of genes involved in innate immune responses, chemotaxis, and complement system pathways.

Conclusion

This study is consistent with emerging epidemiologic evidence and indicates that PM exposure evokes proinflammatory and allergic molecular signatures that may directly contribute to the asthma susceptibility in naive subjects and increased severity in affected asthmatics.     

Combined vaccination against IL-5 and eotaxin blocks eosinophilia in mice

Interleukin-5 (IL-5) is a cytokine which is essential for the maturation of eosinophils in bone marrow and for their release into the blood. Eotaxin is a CC type chemokine implicated in the recruitment of eosinophils in a variety of inflammatory disorders. Since eosinophil-activity is governed by these two pathways, we targeted both IL-5 and eotaxin by active vaccination to block eosinophilia. We produced two vaccines by chemically cross-linking IL-5 or eotaxin to a virus-like particle (VLP) derived from the bacteriophage Qβ, yielding highly repetitive arrays of these cytokines on the VLP surface. Both vaccines overcame self-tolerance and induced high antibody titers against the corresponding self-molecules in mice. Immunization with either of the two vaccines reduced eosinophilic inflammation of the lung in an ovalbumin (OVA) based mouse model of allergic airway inflammation. Animals immunized with the two vaccines at the same time developed high antibody titers against both cytokines and also reduced eosinophil-infiltration of the lung. These data demonstrate that targeting either IL-5 or eotaxin may lower eosinophilia. Simultaneous immunization against IL-5 and eotaxin demonstrates that such a therapeutic approach may be used to treat complex disorders in which multiple mediators are involved.     

Modulation of Distinct Asthmatic Phenotypes in Mice by Dose-Dependent Inhalation of Microbial Products

Background: Humans with asthma display considerable heterogeneity with regard to T helper (Th) 2–associated eosinophilic and Th17-associated neutrophilic inflammation, but the impact of the environment on these different forms of asthma is poorly understood.Objective: We studied the nature and longevity of asthma-like responses triggered by inhalation of allergen together with environmentally relevant doses of inhaled lipopolysaccharide (LPS).Methods: Ovalbumin (OVA) was instilled into the airways of mice together with a wide range of LPS doses. Following a single OVA challenge, or multiple challenges, animals were assessed for pulmonary cytokine production, airway inflammation, and airway hyperresponsiveness (AHR).Results: Mice instilled with OVA together with very low doses (≤ 10^–3 μg) of LPS displayed modest amounts of Th2 cytokines, with associated airway eosinophilia and AHR after a single challenge, and these responses were sustained after multiple OVA challenges. When the higher but still environmentally relevant dose of 10^–1 μg LPS was used, mice initially displayed similar Th2 responses, as well as Th17-associated neutrophilia. After multiple OVA challenges, however, the 10^–1 μg LPS animals also accumulated large numbers of allergen-specific T regulatory (Treg) cells with high levels of inducible co-stimulatory molecule (ICOS). As a result, asthma-like features in these mice were shorter-lived than in mice sensitized using lower doses of LPS.Conclusions: The nature and longevity of Th2, Th17, and Treg immune responses to inhaled allergen are dependent on the quantity of LPS inhaled at the time of allergic sensitization. These findings might account in part for the heterogeneity of inflammatory infiltrates seen in lungs of asthmatics.Citation: Whitehead GS, Thomas SY, Cook DN. 2014. Modulation of distinct asthmatic phenotypes in mice by dose-dependent inhalation of microbial products. Environ Health Perspect 122:34–42; http://dx.doi.org/10.1289/ehp.1307280     

Phycocyanin enhances secretary IgA antibody response and suppresses allergic IgE antibody response in mice immunized with antigen-entrapped biodegradable microparticles

In the present study, we have investigated the effects of phycocyanin, a biliprotein of Spirulina platensis, on mucosal and systemic immune responses and allergic inflammation in C3H/HeN and BALB/cA mice. To induce the antigen-specific antibodies in the peripheral lymphoid tissues such as Peyer's patches and mesenteric lymph nodes, biodegradable ovalbumin-entrapped poly (DL-lactide-co-glycolide) particles were used as an antigen. Two weeks after the onset of phycocyanin ingestion, mice were immunized with an aqueous ovalbumin (OVA) solution. Starting at one week after the primary immunization, the mice were subjected to oral immunization with the biodegradable OVA microparticles twice a week. IgA, IgE and IgG1 antibodies were determined by ELISA. The OVA microparticles of 4-microm diameter successfully induced antigen-specific antibodies. In the mice that received phycocyanin treatment for 6 wk, a marked increase in the antigen-specific, as well as the total, IgA antibody level was observed in the Peyer's patches, mesenteric lymph nodes and intestinal mucosa as well as in the spleen cells. Both antigen-specific IgG1 and IgE antibody levels in the serum were suppressed by ingestion of phycocyanin for 8 wk. However, inflammation of the small intestine, monitored as vascular permeability by the Evans blue-leaking method was reduced by phycocyanin at 6 wk, which preceded the suppression of antigen-specific IgG1 and IgE antibody production by 2 wk. These results suggest that phycocyanin enhances biological defense activity against infectious diseases through sustaining functions of the mucosal immune system and reduces allergic inflammation by the suppression of antigen-specific IgE antibody.     

Cis-9,trans-11-conjugated linoleic acid inhibits allergic sensitization and airway inflammation via a PPARgamma-related mechanism in mice

Milk consumption from early childhood on has been found to be inversely correlated with allergic sensitization and the onset of bronchial asthma. We tested whether cis-9,trans-11-conjugated linoleic acid (c9,t11-CLA), naturally occurring in milk fat, may prevent allergic sensitization and inhibit airway inflammation in a murine asthma model. BALB/c mice were fed a diet enriched in 1 wt% of c9,t11-CLA or a control diet 7 d prior to and for 32 d during sensitization [d 1 and 14, 100 mg/L ovalbumin (OVA) in adjuvant vs. PBS] and airway challenges (d 28-30, 1% OVA in PBS vs. PBS). Subgroups of mice were coadministered 20 micromol/L of the selective PPARgamma antagonist GW9662 during each OVA challenge. C9,t11-CLA feeding resulted in significantly reduced IgE production and allergen-induced in vivo airway hyperresponsiveness. Further, less mucous plugging of segmental bronchi and significantly reduced interleukin-5 and eosinophils were determined in bronchoalveolar lavage fluids of c9,t11-CLA-fed mice. C9,t11-CLA feeding prevented the downregulation of PPARgamma mRNA in the lung tissues observed after allergen sensitization and airway challenges in control mice. The inhibitory effects of c9,t11-CLA on airway inflammation were partially prevented by coadministration of GW9962. Further, c9,t11-CLA feeding resulted in a significantly lower concentration of the eicosanoid precursor, arachidonic acid, in tissue lipids. These findings demonstrate that dietary c9,t11-CLA can reduce allergic airway inflammation, most likely via a PPARgamma-related mechanism and by reducing eicosanoid precursors. They give new insights into the fatty acid-mediated mechanism of immunomodulation and may represent a step toward an attractive novel strategy in the dietary prevention and treatment of allergic asthma.