气道黏液高分泌的信号传导通路

目的探讨中性粒细胞弹性蛋白酶（NE）诱导气道黏蛋白（MUC）5AC基因表达的信号传导机制。方法用NE刺激A549细胞,以活性氧（ROS）清除剂DMTU、组织激肽释放酶抑制剂aprotinin和表皮生长因子受体（EGFR）酪氨酸激酶抑制剂AG1478为干预条件,用RT-PCR检测MUC5AC转录水平,用ELISA和Western blot法检测表皮生长因子（EGF）、EGFR及其磷酸化水平。结果NE刺激组MUC5AC mRNA水平显著高于对照组,同时伴有EGF浓度升高和磷酸化EGFR增加。DMTU、aprotinin和AG1478干预组MUC5AC mRNA水平与NE刺激组相比显著降低,DMTU和aprotinin干预组EGF和磷酸化EGFR也显著降低。结论NE经EGFR信号通路诱导A549细胞MUC5AC表达,其上游途径有氧化剂、组织激肽释放酶和EGF参与。     

卡他莫拉菌经NADPH 氧化酶/ ROS / TGF-α信号通路诱导支气管上皮细胞表达MUC5AC

目的:初步探究卡他莫拉菌诱导支气管上皮细胞表达MUC5AC的分子机制,为阐明卡他莫拉菌的致病机制提供理论依据。方法:培养人正常支气管上皮细胞(BEAS-2B),采用不同感染复数(MOI=0.001、0.01、0.1)的卡他莫拉菌感染BEAS-2B细胞后,ELISA、qPCR分别检测细胞中TGF-α及MUC5AC含量,DCFH-DA法检测细胞内ROS水平,并通过Western blot检测细胞质及细胞膜上NADPH氧化酶p47~(phox)的表达情况;ROS抑制剂NAC以及NADPH氧化酶抑制剂Apocynin预处理感染细胞后,分别检测细胞中MUC5AC、ROS及TGF-α水平;通过TGF-α中和抗体处理卡他莫拉菌感染的细胞,并检测细胞内MUC5AC的变化情况。最后采用ELISA检测卡他莫拉菌感染患者血清以及肺泡灌洗液中TGF-α以及MUC5AC分泌水平。结果:不同感染复数卡他莫拉菌感染细胞后能够显著诱导MUC5AC表达,且呈浓度依赖性;此外,在卡他莫拉菌感染的细胞内,ROS及TGF-α水平显著上升,细胞质内p47~(phox)表达降低而细胞膜上p47~(phox)表达则显著上升;ROS抑制剂及NADPH氧化酶抑制剂处理后,细胞中ROS、MUC5AC及TGF-α水平均明显减少;而采用TGF-α中和抗体处理也能够明显减少感染细胞内MUC5AC的分泌。此外,卡他莫拉菌感染患者血清以及肺泡灌洗液中TGF-α和MUC5AC分泌水平均显著高于正常组。结论:卡他莫拉菌能够通过激活NADPH氧化酶/ROS/TGF-α信号通路促进人支气管上皮细胞分泌MUC5AC。     

肺炎衣原体感染通过PI3K激活Rac1而诱导血管平滑肌细胞迁移

 目的:研究Rac1活化在肺炎衣原体（C.pn）感染诱导血管平滑肌细胞（VSMCs）迁移中的作用及磷脂酰肌醇3-激酶（PI3K）对其活化的影响。方法:谷胱甘肽巯基转移酶（GST）-p21活化激酶1 p21结合结构域（PBD）即GST-PBD重组质粒转化感受态细菌,诱导融合蛋白表达并纯化;GST-pull down实验检测C.pn感染VSMCs后Rac1活性的变化;PI3K特异性抑制剂LY294002 （25 μmol/L）预处理VSMCs,GST-pull down实验检测Rac1活性的变化;Rac1特异性抑制剂NSC23766（50 μmol/L）预处理VSMCs,wound-healing 实验和Transwell 实验观察VSMCs迁移能力的变化。结果:重组质粒转化感受态细菌后,经诱导表达和纯化,得到足量有效的GST-PBD融合蛋白;GST-pull down实验结果显示,C.pn感染VSMCs后Rac1活性增强且显著高于正常对照组（P<0.05）;LY294002预处理VSMC后,C.pn感染诱导的Rac1活性明显下降（P<0.05）;细胞迁移实验结果显示,NSC23766预处理的 C.pn感染组细胞迁移能力明显低于单纯感染组（P<0.05）。结论: C.pn感染可能通过PI3K激活Rac1,从而诱导VSMCs迁移。     

DHA激活NADPH氧化酶/ROS/Nrf2通路诱导ARPE-19细胞表达HO-1

目的:观察二十二碳六烯酸(Docosahexaenoic acid,DHA)诱导人视网膜色素上皮细胞表达血红素氧合酶(Heme oxygenase,HO)-1的分子机制。方法:培养人视网膜色素上皮细胞系ARPE-19,加入30~100μmol/L DHA作用4~24 h。Western blot检测HO-1的表达及NADPH氧化酶p47~(phox)亚基的磷酸化;荧光探针H2DCFDA检测活性氧(Reactive oxygen species,ROS)的产生;免疫荧光分析Nrf2在细胞核及胞浆中的表达;最后采用NADPH氧化酶抑制剂DPI,ROS抑制剂NAC或采用siRNA干扰Nrf2表达,检测其对HO-1表达的影响。结果:100μmol/L DHA作用ARPE-19细胞30 min即可诱导p47~(phox)亚基的磷酸化,同时能增加细胞内ROS的含量;采用NADPH氧化酶抑制剂DPI处理后,ROS水平显著降低;免疫荧光实验显示DHA作用细胞2 h后,可诱导Nrf2核转位,采用DPI或NAC处理后,Nrf2核转位水平明显减少;采用Nrf2 siRNA沉默其表达,或采用DPI或NAC处理后,可抑制DHA诱导ARPE-19细胞表达HO-1。结论:DHA可能通过NADPH氧化酶/ROS/Nrf2通路途径诱导视网膜色素上皮细胞表达HO-1,从而发挥对细胞的保护作用。     

槲皮素基于EGFR信号通路减轻大鼠气道黏液高分泌北大核心CSCD

目的:探讨槲皮素对LPS诱导的大鼠气道黏液高分泌的作用及其分子机制。方法:将36只SD大鼠随机分为:对照组、LPS组、槲皮素低、中、高剂量组、AG1478组;气道内滴注LPS建立大鼠气道黏液高分泌模型。HE染色观察肺组织的病理变化;AB-PAS染色观察杯状细胞增生和黏液分泌情况;ELISA检测肺组织中MUC5AC浓度;采用免疫组织化学法(IHC)检测MUC5AC、EGFR、PKC、NF-κB表达;RT-qPCR检测肺组织MUC5AC及EGFR mRNA表达;Western blot检测p-EGFR、EGFR、p-PI3K、PI3K、p-PKC、PKC、p-AKT、AKT、NF-κB表达。结果:与LPS组相比,槲皮素低、中、高剂量组病理变化逐渐减轻,肺组织炎症积分和AB-PAS阳性着色面积逐渐降低(P<0.05);槲皮素能减少肺组织MUC5AC、EGFR、PKC、NF-κB表达,降低MUC5AC含量,并下调MUC5AC及EGFR的mRNA水平(P<0.05);槲皮素能减少p-EGFR/EGFR、p-PI3K/PI3K、p-PKC/PKC、p-AKT/AKT、NF-κB蛋白表达(P<0.05)。结论:气管内滴注LPS能成功诱导大鼠气道黏液高分泌模型,槲皮素对LPS诱导大鼠气道黏液高分泌具有拮抗作用,其作用机制可能与抑制EGFR信号通路,调控p-EGFR/EGFR、p-PI3K/PI3K、p-PKC/PKC、p-AKT/AKT、NF-κB表达,下调MUC5AC表达有关。     

李斯特菌溶血素通过激活PI3K / Akt 信号通路促进呼吸道上皮细胞炎症反应及MUC5AC 表达

目的:初步探讨李斯特菌溶血素(LLO)刺激呼吸道上皮细胞株(16-HEB)产生炎性反应及促进MUC5AC表达的分子机制,为阐明李斯特菌的致病机制提供理论依据。方法:采用不同浓度的LLO(15、30、45μg/ml)刺激16-HEB细胞株24 h后,qRT-PCR和ELISA法分别检测细胞中MUC5AC的mRNA转录水平与蛋白浓度变化,以及炎性因子IL-6与IL-1β的含量及mRNA转录水平; Western blot检测不同浓度LLO刺激后细胞中p-Akt、Akt的表达情况及相对含量; PI3K抑制剂LY294002预处理后检测p-Akt、Akt的表达情况,随后用LLO刺激16-HEB细胞株,并进一步检测细胞中MUC5AC与炎性因子的表达转录情况。结果:随着LLO刺激浓度的增加,细胞中MUC5AC的转录水平与浓度逐渐上升,且均显著高于对照组(P0. 05),炎性因子IL-6与IL-1β的含量与转录水平也显著增加(P 0. 05); Western blot结果显示LLO能够激活p-Akt的表达(P0. 05),而使用抑制剂LY294002处理后则会显著降低细胞中p-Akt的表达(P0. 05);抑制剂处理后细胞中MUC5AC与炎性因子的表达与转录水平均出现降低,且显著低于LLO刺激组(P0. 05)。结论:LLO能够激活PI3K/Akt信号通路进而诱导16-HEB细胞产生炎性因子IL-6、IL-1β,并促进细胞中MUC5AC的表达。     

Rac1信号通路在小鼠可卡因情景线索记忆过程中的作用

目的:探讨Rac1信号通路在小鼠可卡因情景线索记忆过程中的作用。方法:将成年雄性C57BL/6J小鼠随机分为对照组(control)、可卡因配对的条件性位置偏爱组(CPP)和Rac1抑制剂NSC23766处理组(NSC),利用CPP实验检测可卡因是否可诱导小鼠产生CPP,利用立体定位技术注射AAV-GFP病毒于小鼠海马CA1区并做免疫荧光染色观察海马CA1区神经元的形态;利用Western Blot及GST-pull down方式检测蛋白表达及活性变化;采用Rac1抑制剂NSC23766阻断信号通路探讨其对小鼠可卡因诱导的CPP的影响。结果:可卡因可以诱导小鼠形成CPP,并导致Rac1 GTPase活性增强及其下游信号分子cofilin磷酸化活性升高,并最终导致海马CA1区锥体神经元发生神经可塑性变化。结论:Rac1信号通路通过影响小鼠海马CA1区锥体神经元发生结构可塑性,从而参与调控可卡因情景线索记忆。     

二烯丙基三硫诱导人髓样白血病HL-60细胞活性氧产生及其细胞毒性作用

目的：探讨二烯丙基三硫(DATS)诱导人白血病HL-60细胞产生活性氧(ROS)及其细胞毒性作用。方法: 用浓度为50、100、150、200 μmol/L DATS处理HL-60细胞1、3、6、12、24 h后，流式细胞计数法检测HL-60细胞内的ROS水平，NBT还原实验分析NADPH氧化酶的活性，分别用NADPH氧化酶特异性阻断剂apocynin与抗氧化剂NAC（N-acetyl-L-cystein）预处理30 min后，观察DATS对HL-60细胞产生活性氧的影响，分光光度法检测细胞质膜氧化产物丙二醛（MDA）与细胞蛋白氧化产物羰基化蛋白（protein carbonyl）。结果: DATS能诱导人白血病HL-60细胞产生ROS，当DATS处理细胞1-3 h 时，HL-60细胞产生ROS随DATS浓度的升高和处理时间的延长而升高，当浓度为150 μmol/L DATS处理细胞3h时，ROS的荧光强度达到最高峰，其后维持在一个较高水平。NADPH氧化酶活性与ROS的产生一致。HL-60细胞的脂质过氧化和羰基化蛋白浓度与DATS诱导ROS产生的趋势基本一致，都在3 h、150 μmol/L处理点达到最高值。应用NADPH氧化酶特异性阻断剂apocynin或抗氧化剂NAC后，能显著降低HL-60细胞ROS的产生和细胞损伤。结论: NADPH氧化酶是DATS诱导 HL-60 细胞产生ROS的主要酶系，ROS能氧化细胞质膜和蛋白质。     

前列腺素D2受体调节PGD2诱导的人气道黏液高分泌

目的研究前列腺素D2(PGD2)通过D类前列腺素受体2(DP2)对人气道上皮细胞黏液分泌的效应及其作用机制。方法用PGD2刺激人气道上皮16HBE细胞,以DP2拮抗剂AZD6430、DP1拮抗剂BWA868C及三磷酸肌醇蛋白激酶(PI3K)抑制剂LY294002为干预因素,将细胞分为对照组、PGD2刺激组、PGD2刺激+AZD6430组、PGD2刺激+BWA868C组、PGD2刺激+LY294002组。ELISA检测细胞中肿瘤坏死因子(TNF)-α、白介素(IL)-4和IL-13的蛋白含量,激光共聚焦技术检测细胞内黏蛋白(MUC)5AC含量;Western blot检测DP2、DP1、PI3K和磷酸化AKT(p-AKT)表达水平;实时荧光定量PCR检测TNF-α、IL-4、IL-13和MUC5AC mRNA表达水平。结果 PGD2刺激后MUC5AC、TNF-α、IL-4、IL-13、DP2、PI3K和p-AKT表达显著高于对照组(P0.05);AZD6430拮抗组中MUC5AC、TNF-α、IL-4、IL-13、PI3K及p-AKT表达较PGD2刺激组明显减弱(P0.05);LY294002组TNF-α、IL-4、IL-13和MUC5AC表达较PGD2组亦显著减弱(P0.05)。结论 PGD2激活人气道上皮细胞的DP2受体,活化PI3K/AKT引起黏液高分泌。     

表皮生长因子干预人羊膜间充质干细胞的增殖和迁移

背景：人羊膜间充质干细胞移植可促进皮肤创伤的愈合。 目的：观察表皮生长因子对体外培养人羊膜间充质干细胞增殖和迁移的影响。 方法：人羊膜间充质干细胞经分离、鉴定并培养至第3代。细胞经过不同浓度的表皮生长因子处理后,用MTT法测量吸光度值从而计算出细胞存活率,通过计数穿过Transwell小室的细胞数测定表皮生长因子对细胞迁移能力的影响;并用表皮生长因子受体的抑制剂AG1478及PI3K的抑制剂LY294002检测其对细胞迁移能力的影响。 结果与结论：表皮生长因子处理后细胞的吸光度值升高1.55倍,穿过膜的数量增高1.5倍;AG1478、LY294002对表皮生长因子引起的迁移有抑制作用。提示表皮生长因子处理后细胞增殖和迁移能力均增强,迁移与EGFR-PI3K信号通路有关。     

Role of epidermal growth factor receptor in maintaining airway goblet cell hyperplasia in rats sensitized to allergen

Background Stimulation of epidermal growth factor receptor (EGFR) induces airway goblet cell hyperplasia, but the role of this molecule in the maintenance of this pathologic change remains uncertain. Objective To determine the mechanisms by which goblet cell hyperplasia is maintained in airway epithelium, we investigated EGFR‐induced signalling pathways that lead to both mucin production and antiapoptosis in vitro. We also tested whether the inhibition of EGFR tyrosine kinase speeds reversal of established goblet cell hyperplasia to normal epithelial phenotype in vivo. Methods MUC5AC production was measured by immunoassay, and antiapoptotic responses were determined by Bcl‐2 expression and terminal deoxynucleotidyl transferase‐mediated dUTP‐biotin Nick End Labelling staining using NCI‐H292 cells. The effect of an inhibitor of EGFR tyrosine kinase (AG1478) on goblet cell hyperplasia was also determined in rats sensitized with ovalbumin (OVA). Results MUC5AC was constitutively expressed and few apoptotic cells were observed in NCI‐H292 cells under non‐stimulated condition. TGF‐α increased MUC5AC and Bcl‐2 expression, an effect that was prevented by inhibitors of EGFR tyrosine kinase (AG1478), MEK (PD98059), and NF‐κB (CAPE). After the addition of TGF‐α, AG1478 and an inhibitor of phosphatidylinositol 3 kinase/Akt (LY294002), but not PD98059, induced a marked apoptotic response, which was prevented by the caspase inhibitor Z‐VAD fmk. Goblet cell hyperplasia and EGFR expression in airway epithelium were noted in the OVA‐sensitized rats. Intratracheal instillation of AG1478 induced apoptosis of goblet cells, reverting the airway epithelium to normal epithelial phenotype. Conclusion These findings indicate that EGFR plays an important role in the maintenance of goblet cell hyperplasia. We speculate that inhibitors of the EGFR cascade might be an effective therapy of airway remodelling.     

Src homology 2-containing phosphotyrosine phosphatase regulates endothelin-1-induced epidermal growth factor receptor transactivation in rat renal tubular cell NRK-52E

Epidermal growth factor (EGF) and endothelin-1 (ET-1) have been shown to be involved in proliferation and autoregeneration of renal tubular cells. This study aims to investigate the regulatory mechanism of ET-1-mediated EGF receptor (EGFR) transactivation in rat renal tubular cells (NRK-52E). Exposure of NRK-52E cells to ET-1 was found to stimulate the phosphorylation of EGFR and induce reactive oxygen species (ROS) generation. Both NAD(P)H oxidase inhibitor, diphenyliodonium (DPI) and ROS scavenger N-acetylcysteine (NAC), inhibited EGFR transactivation and extracellular signal-regulated kinase (ERK) phosphorylation caused by ET-1. In contrast, blockade of EGFR by AG1478 inhibited the phosphorylation of ERK but not ROS generation following ET-1 exposure. We found that the catalytic cysteine of Src homology 2-containing phosphotyrosine phosphatase (SHP-2) was transiently oxidized by ET-1 treatment in a modified malachite green phosphatase assay. In EGFR co-immunoprecipitation, SHP-2 was also found to interact with EGFR following ET-1 treatment. In SHP-2 knockdown NRK-52E cells, ET-1-induced EGFR transactivation was dramatically elevated and not influenced by NAC. However, GM6001 (an MMP inhibitor) and heparin binding (HB)-EGF neutralizing antibody suppressed this elevation. Our data suggest that ROS-mediated oxidation of SHP-2 is essential for HB-EGF-mediated EGFR transactivation in ET-1 signaling pathway in NRK-52E cells.     

Epidermal growth factor receptor signaling mediates vesicant-induced airway epithelial secretion of interleukin-6 and production of mucin

The chemical warfare agent sulfur mustard (HD) and its analogue nitrogen mustard (HN2) are highly reactive vesicants that can cause airway epithelial injury. However, little is known about the mechanisms governing vesicant-related airway damage. This study assessed the role of epidermal growth factor receptor (EGFR) signaling in mediating the effects of exposure to vesicants on the secretion of cytokines and production of mucin in human airway epithelial cells. Normal human bronchial epithelial cells (NHBECs) at an air-liquid interface were challenged apically with either 200 μM HN2 or medium alone (mock treatment, MT), and cultures were evaluated for receptor fate, the secretion of IL-6, and the production of both total mucin and Mucin 5AC (MUC5AC). Exposure to HN2 induced the activation of both EGFR and (44/42)mitogen-activated protein kinase ((44/42)MAPK), as well as the ubiquitination and colocalization of EGFR within lysosomal structures. Moreover, challenge with HN2 induced the up-regulation of IL-6 and MUC5AC at the mRNA and protein levels, and stimulated the secretion of total mucin in NHBECs. HN2-related effects on the secretion of IL-6 and the production of total mucin and MUC5AC were reversed by the selective EGFR inhibitor AG1478 and by an EGFR-blocking antibody. The HN2-induced activation of (44/42)MAPK and the up-regulation of IL-6 secretion in NHBECs were also largely reversed by a transforming growth factor-α (TGF-α)-blocking antibody and by the metalloprotease inhibitor GM 6001, suggesting that the HN2-related effects on EGFR signaling were TGF-α-dependent. Collectively, these findings suggest that EGFR signaling may play a significant role in mediating vesicant-induced airway epithelial injury.     

Study on TRPV1-mediated mechanism for the hypersecretion of mucus in respiratory inflammation

Transient receptor potential vanilloid 1 (TRPV1) is sensitized by the high affinity TrkA receptor, which promotes pro-inflammatory cytokine production and mediates mucus hypersecretion in bronchial epithelial cells. The purpose of this study was to investigate the mechanism of TRPV1-mediated mucus hypersecretion and respiratory inflammation. Firstly, using Western blot analysis we found that epidermal growth factor receptor (EGFR) and TRPV1 were highly co-expressed in human bronchial epithelial cells (HBE16) with HNE and capsaicin co-treated, the levels of pro-inflammatory cytokines and MUC5AC were also highly co-expressed; however, TRPV1 receptor expression was low in these cells with only HNE stimulation, which demonstrated that sensitization of TRPV1 was not increased in HBE16 cells treated with HNE alone. Secondly, the EGF receptor antagonist (AG1478) and the TrkA receptor inhibitor (K252a) significantly inhibited TRPV1 sensitivity and the expression of MUC5AC and pro-inflammatory cytokines. Furthermore, the PI3K inhibitor LY294002, the PKC inhibitor bisindoylmaleimide (BIM) and the TRPV1 antagonist capsazepine completely abrogated the EGF sensitizing effect. Furthermore, the hypoxia-inducible factor (HIF-1α) inhibitor 2-methoxyestradiol (2-ME2) decreased the activity of PKC by a specific pathway. These findings strongly suggest that TRPV1 sensitization influences the hypersecretion of mucus and inflammatory cytokines, is associated with the PI3K and PKC signaling pathways and is involved HIF-1α activity.     

Cigarette smoke synergistically enhances respiratory mucin induction by proinflammatory stimuli

Pathogenic factors associated with chronic obstructive pulmonary disease (COPD), such as cigarette smoke, proinflammatory cytokines, and bacterial infections, can individually induce respiratory mucins in vitro and in vivo. Since co-presence of these factors is common in lungs of patients with COPD, we hypothesized that cigarette smoke can amplify mucin induction by bacterial exoproducts and proinflammatory cytokines, resulting in mucin hyperproduction. We demonstrated that cigarette smoke extract (CSE) synergistically increased gene expression and protein production of MUC5AC mucin induced by LPS or TNF-alpha in human airway epithelial NCI-H292 cells. CSE also enhanced expression and production of MUC5AC mucin induced by epidermal growth factor receptor (EGFR) ligands TGF-alpha and amphiregulin, as well as LPS- and TNF-alpha- induced expression and/or release of TGF-alpha and amphiregulin. Furthermore, (4-[(3-bromophenyl)amino]-6,7-diaminoquinazoline), a potent inhibitor of EGFR, blocked synergistic induction of MUC5AC mucin. H(2)O(2) mimicked the synergistic effects of CSE, while antioxidant N-acetyl-L-cysteine prevented synergistic induction of MUC5AC mucin by CSE. In a rat model of LPS-induced airway inflammation, concurrent cigarette smoke inhalation enhanced mucin content of the bronchoalveolar lavage fluid, muc5AC gene expression, and mucous cell metaplasia in the airways. These results suggest that cigarette smoke has the potential to synergistically amplify induction of respiratory mucins by proinflammatory stimuli relevant to COPD pathogenesis and contribute to mucin hyperproduction observed in patients with COPD.     

Respiratory carcinoma cell lines. MUC genes and glycoconjugates

Lung carcinoma cell lines are being used in many laboratories to study various airway epithelial functions, including mucin gene expression. To identify model systems for investigating regulation of MUC5/5AC gene expression and secretion of MUC5/5AC mucins in airway epithelial cells, we evaluated the expression of several mucin genes in six carcinoma cell lines of respiratory tract origin. RNA was extracted from A549, Calu-3, NCI H292, Calu-6, RPMI 2650, and A-427 cells; MUC1, MUC2, MUC4, MUC5/5AC, and MUC5B messenger RNA (mRNA) expression was determined. By Northern analyses, all cell lines expressed MUC1 mRNA, whereas MUC2 mRNA was not detectable in any of the cell lines. RPMI 2650 cell lines expressed only MUC1 mRNA. NCI-H292 cells expressed MUC4 and low levels of MUC5/5AC mRNA. Calu-3 and A549 cells expressed MUC5/5AC mRNA; A549 cells also expressed MUC5B mRNA. Glycoconjugates secreted by lung carcinoma cells were also examined. By wheat germ lectin analysis, Calu-3, H292, and A549 cells secreted high molecular weight glycoproteins having N-acetylglucosamine and/or sialic acid moieties. Western blot analyses with an anti-MUC5:TR-3A antibody demonstrated that Calu-3 and A549 cells secreted MUC5/5AC mucins. All six carcinoma cell lines secreted large, radiolabeled, sulfated macromolecules; the majority were proteoglycans that were digested by hyaluronidase. However, Calu-3 cells also secreted sulfated high molecular-weight glycoproteins that were immunoprecipitated by anti-MUC5:TR-3A antibody. These studies demonstrated that Calu-3 and A549 cell lines expressed high and moderate amounts of MUC5/5AC mRNA and MUC5/5AC mucins, whereas H292 cells expressed lesser amounts. These cell lines should prove useful for studies of MUC5/5AC gene expression and MUC5/5AC biosynthesis, trafficking, and secretions in airway epithelial cells.     

The role of Nox4 in oxidative stress-induced MUC5AC overexpression in human airway epithelial cells

Mucus hypersecretion is a prominent manifestation in patients with chronic inflammatory airway diseases, and MUC5AC is a major airway mucin. It is well known that reactive oxygen species (ROS) may be involved in the pathogenesis of various inflammatory airway diseases. The purpose of this study was to identify which secreted mucin genes are induced by exogenous hydrogen peroxide and the mechanism by which these genes are up-regulated in normal human nasal epithelial (NHNE) cells. Exogenous H(2)O(2) induced the ligand-independent activation of epidermal growth factor receptors (EGFR) and the subsequent activation of ERK1 mitogen-activated protein kinase, resulting in the induction of intracellular ROS generation. Through this signal pathway, exogenous H(2)O(2) markedly induced overexpression of the MUC5AC gene alone. In addition, Nox4, a subtype of nonphagocytic NADPH oxidase, was found to play a key role in intracellular ROS generation and exogenous H(2)O(2)-induced MUC5AC gene expression in NHNE cells.     

Hyaluronan fragments/CD44 mediate oxidative stress-induced MUC5B up-regulation in airway epithelium

Mucus hypersecretion with elevated MUC5B mucin production is a pathologic feature in many airway diseases associated with oxidative stress. In the present work, we evaluated MUC5B expression in airways and in primary cultures of normal human bronchial epithelial (NHBE) cells, as well as the mechanisms involved in its regulation. We found that oxidative stress generated by cigarette smoke or reactive oxygen species (ROS) induces MUC5B up-regulation in airway epithelium from smokers and in NHBE cells, respectively. We have previously shown that ROS-induced MUC5AC expression in NHBE cells is dependent on hyaluronan depolymerization and epidermal growth factor receptor (EGFR)/mitogen-activated protein kinase (MAPK) activation. Since hyaluronan fragments can activate MAPK through the hyaluronan receptor CD44, and CD44 heterodimerizes with EGFR, we tested whether ROS and/or hyaluronan fragments induce MUC5B mRNA and protein expression through CD44/EGFR. We found that ROS promotes CD44/EGFR interaction, EGFR/MAPK activation, and MUC5B up-regulation that are prevented by blocking CD44 and/or EGFR. These results were mimicked by hyaluronan fragments. In summary, our results show that oxidative stress in vivo (cigarette smoke) or in vitro (ROS) induces MUC5B up-regulation. This ROS-induced MUC5B expression requires CD44 as well as EGFR and MAPK activation. In addition, we also provide evidence that hyaluronan fragments are sufficient to induce CD44/EGFR interaction and downstream signaling that results in MUC5B up-regulation, suggesting that hyaluronan depolymerization during inflammatory responses could be directly involved in the induction of mucus hypersecretion.