白介素13通过FOXA2调控气道上皮细胞粘液分泌

目的:研究白介素13(Interleukin-13,IL-13)对气道上皮细胞粘液分泌的效应并探讨其作用机制。方法:HBE16细胞在无血清培养基中培养24小时后加入IL-13刺激24小时,ELISA检测粘蛋白(MUC)5AC的表达;Western检测磷酸化细胞外信号调节激酶1/2(Extracellular signal-regulated kinase 1/2,ERK1/2)和磷酸化c-Jun氨基端激酶1/2(c-Jun N-terminal kinase 1/2,JNK1/2的表达;使用SP600125阻滞JNK信号通路后检测MUC5AC蛋白表达;RT-PCR检测STAT4和STAT6的表达变化;EMSA检测通路下游核蛋白FOXA2的表达。结果:IL-13刺激24小时后MUC5AC和p-JNK1/2表达升高,而p-ERK1/2表达无显著变化;使用SP600125阻断JNK通路表达后,MUC5AC表达减弱;IL-13刺激后STAT4表达无显著变化,STAT6表达显著升高,FOXA2表达显著降低。结论:IL-13通过JNK-STAT6-FOXA2通路调控粘液分泌。     

气道黏液高分泌机制的研究进展

气道黏液高分泌主要表现为气道黏液理化性质的改变,包括以MUC5AC为主的黏液组分改变和由黏液腺细胞为主过渡到以杯状细胞为主的分泌黏液细胞的改变。香烟烟雾为主的吸入性有害物和细菌感染是诱导气道黏液高分泌的主要刺激物,而热休克蛋白、信号传导通路和黏蛋白MUC5AC表达的增加是气道黏液高分泌的主要机制。     

TNF-α与香烟烟雾在诱导气道上皮细胞株黏蛋白表达的相互作用

目的 探讨肿瘤坏死因子TNF-α与香烟提取物共同诱导气道黏液高分泌的相互关系及作用特点。方法 培养的人气道上皮细胞BEAS-2B,转染核转录因子（NF）-κB"decoy"寡核苷酸（ODNs）,并以乱序NF-κB ODNs为对照转染组,各组均分别予以TNF-α、10%香烟提取物（CSE）单独刺激及共同刺激,以Western blot、ELISA及RT-PCR法检测各组刺激前后磷酸化表皮生长因子受体（p-EGFR）、黏蛋白（MUC5AC）蛋白及mRNA水平。结果 转染乱序NF-κB ODNs的细胞予以TNF-α、10% CSE刺激后,各组细胞中p-EGFR蛋白水平较对照组升高,伴随MUC5AC蛋白含量及基因转录水平的提高(P<0.05);共孵育组中较单独刺激组升高更为显著（P<0.05）。转染NF-κB"decoy"ODNs组再予以TNF-α刺激,细胞中MUC5AC蛋白含量及mRNA水平与未转染组相比升高不明显,而单用CSE刺激组中的MUC5AC、p-EGFR水平仍有明显升高（P<0.05）;共孵育组显示出与CSE单独刺激组相似的结果。结论 TNF-α、CSE能协同促进气道上皮细胞中黏蛋白合成,转录因子NF-κB主要参与TNF-α所致的MUC5AC表达,而在CSE诱导的效应过程中作用不明显。     

血红素加氧酶-1抑制香烟烟雾提取物致体外人肺A549细胞黏液高分泌

目的探讨血红素加氧酶-1(HO-1)对香烟烟雾提取物(CSE)所致人气道黏液高分泌的影响。方法用CSE刺激A549细胞,复制黏液高分泌细胞模型。分为对照组、CSE组、氯化高铁血红素(Hemin)组和锌原卟啉(ZnPPIX)组,观察黏蛋白(MUC)5AC、表皮生长因子受体(EGFR)、磷酸化(p)-EGFR、HO-1及双功能氧化酶1(Duox1)的表达。用MTT法测定细胞活性;RT-PCR法检测HO-1、Duox1、EGFR及MUC5AC的mRNA;Western blot法检测p-EGFR、EGFR、Duox1和HO-1蛋白;ELISA法检测细胞裂解液中MUC5AC蛋白表达。结果CSE组MUC5AC的mRNA吸光度积分相对值和蛋白水平分别为0.660±0.044和(157±3)μg/mg,较对照组0.412±0.043和(105±8)μg/mg明显升高(P<0.05),p-EGFR蛋白水平、EGFR、HO-1及Duox1的mRNA和蛋白水平也较对照组明显增高。与CSE组相比,Hemin组HO-1mRNA及蛋白进一步增高,而p-EGFR蛋白水平、Duox1、EGFR及MUC5AC的mRNA和蛋白水平明显回降。与...     

BRAP对LPS诱导的人气道上皮细胞系黏液高分泌的影响

目的探讨蛙皮素受体激活蛋白(BRAP)对脂多糖(LPS)诱导的气道黏液高分泌的影响及相关作用机制。方法体外培养人气道上皮HBE16细胞,转染已构建好的p EGFP-N1-BRAP,以空质粒载体作为对照,给予LPS刺激,同时分别以ERK抑制剂U0126、JNK抑制剂SP600125、P38抑制剂SB203580干预。观察细胞内活性氧(ROS)含量、黏蛋白(MUC)5AC表达和核因子-κB(NF-κB)活性以及细胞活力的变化。结果转染p EGFP-N1-BRAP后ROS明显减少(P0.01);同单纯LPS刺激相比,MUC5AC蛋白含量和mRNA水平在转染p EGFP-N1-BRAP后明显降低(P0.01),NF-κB活性亦呈相同趋势(P0.05);在U0126组,MUC5AC的表达较转染重组质粒组显著降低(P0.01),NF-κB活性也显著下调(P0.05)。结论 BRAP可以通过ROS/ERK/MAPK信号通路阻止胞质内NF-κB的活化,从而下调MUC5AC的生成。     

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。     

Cortactin在应力诱导的气道黏液分泌过程中的介导作用

目的:探讨皮层肌动蛋白结合肽(Cortactin)对剪应力(SS)诱导的气道黏液高分泌的影响及其关键靶点。方法:体外培养气道上皮细胞Beas-2B,并随机分为6组:空白对照组、SS组、SS+Wild-Cortactin组、SS+pc DNA3-Cortactin~(421)-MU组、SS+pcDNA3-Cortactin~(466)-MU组、SS+pcDNA3-Cortactin~(482)-MU组。用Western blot法检测Cortactin蛋白、p-Cortactin蛋白表达水平,RT-PCR、ELISA法分别检测MUC5AC转录水平和MUC5AC的分泌量。结果:转染Cortactin各型重组表达载体后细胞Cortactin蛋白明显增加,提示转染成功。转染Wild-Cortactin后再予剪应力处理,细胞的p-Cortactin蛋白、MUC5AC mRNA及蛋白表达显著增加。而转染pc DNA3-Cortactin~(466)-MU后,细胞p-Cortactin蛋白、细胞培养上清液MUC5AC的相对分泌量显著下降,但MUC5AC的转录水平无明显影响。结论:在剪应力刺激诱导的气道上皮细胞MUC5AC高分泌过程中,Cortactin具有重要的介导作用,且Y466为其介导该过程的潜在关键作用靶点。     

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。     

Ezrin介导中性粒细胞弹性蛋白酶诱导的人气道上皮细胞株分泌黏蛋白增加

目的探讨膜连接蛋白Ezrin在中性粒细胞弹性蛋白酶(NE)诱导气道黏液高分泌的作用及相关调节机制。方法以中性粒细胞弹性蛋白酶刺激培养的人气道上皮HBE16细胞,ELISA法、real-time PCR法测定黏蛋白(MUC)5AC的蛋白及mRNA水平。免疫荧光法检测Ezrin蛋白含量。结果 NE刺激30 min后MUC5AC mRNA表达增强,细胞中及培养上清中黏蛋白MUC5AC的含量均显著高于对照组(P0.01);转染Ezrin永久磷酸化载体pEGFPN1-Ezrin-T567D的细胞经NE刺激后,胞质内磷酸化Ezrin表达明显增强,且胞膜分布增多。同时,细胞培养上清液中的MUC5AC蛋白含量亦显著高于单纯NE组(P0.01)。遏制Ezrin磷酸化pEGFP-N1-Ezrin-T567A载体转染组在NE刺激后,Ezrin蛋白与pEGFP-N1-Ezrin-T567D组相比有明显减少,且未出现向胞膜聚集的趋势,同时分泌至培养上清的MUC5AC蛋白也有明显减少(P0.01),同时伴随胞质内MUC5AC蛋白有所增加(P0.05)。结论 Ezrin蛋白参与了NE诱导的MUC5AC蛋白分泌,是气道上皮细胞MUC5AC分泌的重要调控分子。     

高渗诱导人气道上皮细胞系黏液高分泌

目的研究高渗条件对正常人气道上皮细胞(HBE)黏蛋白(MUC)5AC分泌的影响,以及蛋白激酶C(PKC)-热休克蛋白(HSP)70信号途径在其中的可能作用。方法 采用高渗盐水诱导培养HBE16细胞的方法复制黏液高分泌体外模型,分别用PKCμ抑制剂G 6976、PKCα抑制剂Safingol、PKCβ抑制剂LY333531和PKCδ抑制剂Rot-tlerin干预HBE16细胞。Western blot检测HSP70-2的蛋白含量;RT-PCR检测人HSP70-2转录水平;ELISA检测培养上清MUC5AC蛋白含量c各高渗组的培养上清MUC5AC蛋白含量、HSP70-2蛋白和转录水平较对照组显著升高,并随着培养时间的延长而逐渐增加(P<0.05)。G 6976处理组的上述指标显著降低(P<0.01),但仍高于对照组(P<0.05);而Safingol、LY333531和Rottlerin处理组均无改变。结论 高渗盐水可诱导人气道上皮细胞MUC5AC的高分泌,HSP70-2系通过PKC中的μ亚型在该过程中起重要作用的。     

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.     

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.     

Theaflavins Extracted from Black Tea Inhibit Airway Mucous Hypersecretion Induced by Cigarette Smoke in Rats

Theaflavins isolated from black tea have been used in studies on the prevention of tumor growth. The aim of this study was to investigate whether treatment with theaflavins influences the mucus hypersecretion induced by cigarette smoke in the lungs of experimental rats. Firstly, cigarette smoke was aerosolized using a machine designed for inhalation by rats. The rats were divided into the negative control group, the cigarette smoke inhalation group, the theaflavins (TFs) treatment group, and the TFs + cigarette smoke inhalation group. The animals were sacrificed on day 60 of the experiment. Secondly, the rats were treated with theaflavins at different doses via a gastric tube and sacrificed on day 30. The changes in the levels of mucin 5AC (MUC5AC) and epidermal growth factor receptor (EGFR) in the airway were evaluated. Cigarette smoke induced a significant increase in the levels of MUC5AC and EGFR in all groups. These increases could be reversed by intragastric administration of theaflavins. The effect was more pronounced with the duration of treatment and coincided with a decrease in the expression of both targets. The rats showed various degrees of reduction in the expression of these parameters, which correlated with the theaflavin dose. TFs could inhibit the activation of EGFR, decrease the level of MUC5AC, and relieve airway mucous hypersecretion via the EGFR signaling pathway. These effects correlated directly with the duration of action and the dosage. In the future, oral theaflavins might be valuable in the treatment of chronic airway inflammation.     

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.     

Gene expression of gastric type mucin (MUC5AC) in pancreatic tumors: its relationship with the biological behavior of the tumor

Previously it has been found that the MUC2 gene for intestinal type secretory mucin is highly expressed in intraductal papillary mucinous tumors (IPMT), which are characterized by non-invasive growth and a favorable outcome. In contrast, MUC2 mRNA is rarely expressed in invasive ductal carcinomas (IDC), which have poor outcomes. The gastric type secretory mucin, MUC5AC, is strongly expressed in the surface mucous cells of gastric mucosa. As both MUC2 and MUC5AC mucins share the characteristics of forming highly viscous gels, it is expected that not only MUC2 mucin expression but also MUC5AC mucin expression may be associated with a favorable prognosis in patients with pancreatic tumors. MUC5AC mucin gene expression was examined in 24 cases of IPMT and 38 cases of IDC by in situ hybridization using a digoxigenin-labeled oligonucleotide. The results were compared with MUC2 mucin gene expression. Neither MUC5AC mRNA nor MUC2 mRNA was detected in normal pancreatic tissues. MUC5AC mRNA was expressed in 20 of 24 cases of IPMT (83%) and in five of 38 cases of IDC (13%). In contrast, MUC2 mRNA was expressed in 14 of 24 cases of IPMT (58%) and in none of the 38 cases of IDC (0%). The expression rates of MUC5AC mRNA and MUC2 mRNA in IPMT were significantly higher than those in IDC (P< 0.001, respectively). Intraductal papillary mucinous tumors are characterized by three histological types: (i) villous dark cell type; (ii) papillary clear cell type; and (iii) compact cell type. The villous dark cell type generally expressed both MUC5AC+ and MUC2+ genes. Alternatively, the papillary clear cell type and the compact cell type usually showed MUC5AC+ and MUC2- expression. Patients with MUC5AC mRNA expression had a significantly better survival prognosis than those with no MUC5AC mRNA expression (P< 0.005). In conclusion, MUC5AC gene expression occurs in a majority of IPMT cases, even in those with no MUC2 production. MUC5AC expression can be     

Role of MUC5AC in the pathogenesis of exercise-induced bronchoconstriction

BACKGROUND: The pathogenesis of exercise-induced bronchoconstriction (EIB) involves the release of mediators from several airway cells in response to exercise challenge, but the mechanism leading to airflow obstruction during EIB is incompletely understood. OBJECTIVE: To evaluate the role of secreted mucin in the pathogenesis of EIB. METHODS: Induced sputum was collected at baseline and 30 minutes after exercise challenge in patients with asthma with EIB. The expression of gel-forming mucins and epidermal growth factor receptor ligands were assessed by quantitative polymerase chain reaction. Secreted mucin 5AC (MUC5AC), the eicosanoids cysteinyl leukotrienes (cysLTs) and 15S-hydroxyeicosatetraenoic acid (15S-HETE), and tachykinins neurokinin A (NKA) and substance P (SP) were measured in induced sputum supernatant. RESULTS: Among the gel-forming mucins, MUC5AC was expressed at the highest level. The gene expression of MUC5AC increased after exercise challenge compared with baseline and was associated with EIB severity by regression analysis. The relative levels of MUC5AC in induced sputum increased from a geometric mean of 9.5 at baseline to 18.4 postexercise challenge. Associations between the levels of MUC5AC and cysLTs and between the levels of cysLTs and NKA postexercise challenge were identified by regression analysis. CONCLUSIONS: These data indicate that (1) the predominant gel-forming mucin expressed in induced sputum of patients with asthma with EIB is MUC5AC; (2) an increase in MUC5AC gene expression and release of MUC5AC protein occurs after exercise challenge; and (3) MUC5AC release may occur through the cysLT-associated activation of sensory airway nerves.