M1/MUC5AC mucin released by human airways in vitro.

A series of monoclonal antibodies which bind to a mucin known as M1 (anti-M1 MAbs) have also been shown to detect the product of the human gene MUC5AC. The aim of this investigation was to determine the concentration of the M1 mucin in the surface epithelium of human bronchial preparations by means of immunohistochemistry and in the bronchial fluid derived from human airways by means of an immunoradiometric assay. Human bronchial ring preparations from the resection material of 20 patients were challenged with methacholine, leukotriene D4, or anti-immunoglobulin E. Experiments were performed in preparations with an intact epithelium as well as in tissues in which the epithelium had been mechanically removed. The anti-M1 MAbs stained the goblet cells in the epithelium intensely and there was also light and less uniform staining in the submucosa. The M1/MUC5AC mucin in the fluids secreted by the bronchial preparations was not modified during either the experimental protocol or stimulation with the different secretagogues. However, in preparations in which the epithelium had been removed, there was a significant reduction in the amount of M1/MUC5AC mucin detected. These data suggest that the M1/MUC5AC mucin detected in the biological fluids produced by human airways in vitro may be released constantly, and principally from the goblet cells in the epithelial layer.     

MUC1 and MUC5AC mucin expression in liver fluke-associated intrahepatic cholangiocarcinoma

AIM: To investigate the expressions of MUC1 and MUC5AC in intrahepatic cholangiocarcinoma (ICC). Association of expressions of mucins MUC1 and MUC5AC with clinical findings, metastasis, and survival of the liver fluke-associated ICC patients was determined. METHODS: The expressions of MUC1 and MUC5AC mucins were examined by immunohistochemical staining in 87 cases of histologically-proven ICC. The expressions of mucins in relationship between clinicopathological significance and prognosis of the patients were evaluated. RESULTS: Fifty-two patients (60%) exhibited both MUC1 and MUC5AC expressions, whereas 31% expressed either MUC1 or MUC5AC, and 9% expressed neither. High MUC1 immunoreactivity displayed a significant correlation with tumor progression as reflected by vascular invasion (P<0.01), whereas high expression of MUC5AC significantly correlated with neural invasion (P = 0.022) and advanced ICC stage (P= 0.008). Patients with high expression of MUC1 had a significantly shorter survival (P = 0.0002). According to multivariate analyses, MUC1 reactivity (P = 0.026), histological grading and stage of tumor represented the least probability of survival. CONCLUSION: MUC1 is overexpressed in liver fluke-associated cholangiocarcinoma and relates to vascular invasion and poor prognosis, whereas MUC5AC mucin is neoexpressed and relates to neural invasion and advanced ICC stage. High MUC1 expression in tumor may be useful for predicting the poor outcome of ICC patients.     

Dual oxidase 1-dependent MUC5AC mucin expression in cultured human airway epithelial cells

Mucus hypersecretion is a prominent manifestation in patients with chronic inflammatory airway diseases. MUC5AC mucin is a major component of airway mucus, and its expression is modulated by a TNF-α-converting enzyme (TACE)–EGF receptor pathway that can be activated by reactive oxygen species (ROS). Dual oxidase 1 (Duox1), a homologue of glycoprotein p91^phox, is expressed in airway epithelium and generates ROS. We hypothesize that Duox1 activates TACE, cleaving pro-TGF-α into soluble TGF-α, resulting in mucin expression. To examine this hypothesis, we stimulated both normal human bronchial epithelial cells and NCI-H292 airway epithelial cells with phorbol 12-myristate 13-acetate and with human neutrophil elastase. These stimuli induced TACE activation, TGF-α release, and mucin expression, effects that were inhibited by ROS scavengers, implicating ROS in TACE activation. Inhibition of epithelial NADPH oxidase or knockdown of Duox1 expression with small interfering RNA prevented ROS generation, TGF-α release, and mucin expression by these stimuli, implicating Duox1 in TACE activation and mucin expression. Furthermore, the PKCδ/PKCθ inhibitor rottlerin prevented the effects induced by phorbol 12-myristate 13-acetate and human neutrophil elastase, suggesting that PKCδ and PKCθ are involved in Duox1 activation. From these results, we conclude that Duox1 plays a critical role in mucin expression by airway epithelial cells through PKCδ/PKCθ-Duox1-ROS-TACE-pro-ligand-EGF receptor cascade.     

Submucosal gland cells in human lower airways produce MUC5AC protein

Background and objective:   It is now considered that the major component of mucus, MUC5AC, is mainly produced by goblet cells but not submucosal glands, and the role of the submucosal glands in the production of MUC5AC is unclear. The aim of this study was to clarify whether human submucosal glands produce MUC5AC.
Methods:   Immunohistochemical analysis with MUC5AC antibody of lower airways resected from six lung cancer patients and three patients with acute myocardial infarction was performed.
Results:   The submucosal glands contained both MUC5AC-positive cells and non-positive cells.
Conclusions:   These data suggest that MUC5AC protein is produced in both goblet cells and in airway submucosal glands.     

灯盏花素在气道黏液高分泌大鼠模型中的治疗作用

目的研究灯盏花素在气道黏液高分泌疾病中的治疗作用。方法采用中性粒细胞弹力酶雾化吸人法制作大鼠气道黏液高分泌病理模型,以灯盏花素注射液为干预因素,生理盐水为对照,分别以RT-PCR、ELISA法检测各组气道上皮黏蛋白的表达情况,wester nblot检测蛋白激酶C（PKC）的蛋白水平,放射活性法测定PKC的活性。结果灯盏花素治疗组中的黏蛋白基因转录及蛋白表达水平明显低于对照组,同时伴有组织中蛋白激酶C（PKC）蛋白水平及活性的降低。结论灯盏花素能在一定程度上抑制大鼠气道黏液高分泌,其作用是通过抑制PKC活性而实现。     

Tumor necrosis factor alpha-converting enzyme mediates MUC5AC mucin expression in cultured human airway epithelial cells

Ectodomain shedding of epidermal growth factor receptor (EGFR) ligands [e.g., transforming growth factor type alpha (TGF-alpha)] and EGFR phosphorylation are implicated in mucin production in airway epithelial cells. Tumor necrosis factor alpha-converting enzyme (TACE) is reported to cleave precursor of TGF-alpha, with release of soluble mature TGF-alpha in various epithelial tissues. We hypothesized that TACE increases the shedding of TGF-alpha, resulting in EGFR phosphorylation and inducing mucin production in human airway epithelial (NCI-H292) cells. To examine this hypothesis, we stimulated NCI-H292 cells with phorbol 12-myristate 13-acetate (PMA, an activator of TACE) and pathophysiologic stimuli [lipopolysaccharide (LPS) and supernatant from the Gram-negative bacterium Pseudomonas aeruginosa (PA sup)]. PMA, PA sup, and LPS increased MUC5AC gene expression and mucin protein production, effects that were prevented by pretreatment with AG1478, a selective inhibitor of EGFR phosphorylation and by preincubation with an EGFR-neutralizing Ab or with a TGF-alpha-neutralizing Ab, implicating ligand (TGF-alpha)-dependent EGFR phosphorylation in mucin production. These stimuli induced release of soluble TGF-alpha, EGFR phosphorylation, and MUC5AC expression, which were blocked by the metalloprotease inhibitors tumor necrosis factor-alpha protease inhibitor-1 and tissue inhibitor of metalloprotease-3. We specifically knocked down the expression of metalloprotease TACE by using small interfering RNA for TACE. Knockdown of TACE inhibited PMA-, PA sup-, and LPS-induced TGF-alpha shedding, EGFR phosphorylation, and mucin production. From these results, we conclude that TACE plays a critical role in mucin production by airway epithelial cells by means of a TACE ligand-EGFR cascade in response to various stimuli.     

Assembly and organization of the N-terminal region of mucin MUC5AC: Indications for structural and functional distinction from MUC5B

Elevated levels of MUC5AC, one of the major gel-forming mucins in the lungs, are closely associated with chronic obstructive lung diseases such as chronic bronchitis and asthma. It is not known, however, how the structure and/or gel-making properties of MUC5AC contribute to innate lung defense in health and drive the formation of stagnant mucus in disease. To understand this, here we studied the biophysical properties and macromolecular assembly of MUC5AC compared to MUC5B. To study each native mucin, we used Calu3 monomucin cultures that produced MUC5AC or MUC5B. To understand the macromolecular assembly of MUC5AC through N-terminal oligomerization, we expressed a recombinant whole N-terminal domain (5ACNT). Scanning electron microscopy and atomic force microscopy imaging indicated that the two mucins formed distinct networks on epithelial and experimental surfaces; MUC5B formed linear, infrequently branched multimers, whereas MUC5AC formed tightly organized networks with a high degree of branching. Quartz crystal microbalance-dissipation monitoring experiments indicated that MUC5AC bound significantly more to hydrophobic surfaces and was stiffer and more viscoelastic as compared to MUC5B. Light scattering analysis determined that 5ACNT primarily forms disulfide-linked covalent dimers and higher-order oligomers (i.e., trimers and tetramers). Selective proteolytic digestion of the central glycosylated region of the full-length molecule confirmed that MUC5AC forms dimers and higher-order oligomers through its N terminus. Collectively, the distinct N-terminal organization of MUC5AC may explain the more adhesive and unique viscoelastic properties of branched, highly networked MUC5AC gels. These properties may generate insight into why/how MUC5AC forms a static, “tethered” mucus layer in chronic muco-obstructive lung diseases.

Gel-forming mucins are an essential component of the mucus layer that covers and protects epithelial surfaces from environmental insults. The mucin composition of mucus lining different mucosal surfaces depends on the functional requirements imposed on the epithelium. For instance, in the small intestine and colon, which harbor diverse microbiota, MUC2 is the mucin structurally adapted to form a “tight mucus layer” that provides a niche for the microbes and protects the underlying epithelia by preventing bacterial invasion (1). While in the stomach, MUC6 and MUC5AC together provide a barrier that protects the epithelium from the harsh effects of high luminal acidity (pH = 2 to 3) (2). The mouth, which is the major portal of food and microbes, is protected by saliva, and the dominant gel-forming mucin is MUC5B (3). The lungs, another major portal with exposure to the environment, are mainly protected during homeostasis by MUC5B with a lesser contribution by MUC5AC (4, 5). The distinct regions of the airways have different functional and innate protective requirements for homeostasis, and this necessitates the diverse expression patterns of both mucins throughout the respiratory system (6). MUC5B, secreted by cells in the submucosal glands and the surface epithelium (6), has been shown to be essential for lung innate defense (7). MUC5AC, secreted only by cells in the surface epithelium mainly in the larger airways (6), is generally produced in response to stresses such as cigarette smoke and allergens and is closely associated with muco-obstructive lung diseases, including chronic bronchitis (CB), chronic obstructive pulmonary disease (COPD) (4, 8), and asthma (9, 10). MUC5AC is also critical for defense against enteric parasites, some of which invade the lung (11).Both MUC5B and MUC5AC are large (2 to 100 MDa), polymeric glycoproteins with a high degree of sequence similarity and domain homology, particularly in their N- and carboxyl- terminal regions (12–15). Similar to MUC5B, the N-terminal region of MUC5AC contains von Willebrand factor–like domains (D1, D2, and D3) in addition to trypsin inhibitory–like (TIL) domains and unique regions. The N terminus is followed by a central, highly O-glycosylated mucin domain, which is interrupted by cysteine-rich (CysD) domains and a carboxyl-terminal region that mediates dimerization. In contrast to other gel-forming mucins, MUC5AC contains a putative leucine zipper (LZ) domain (16) at the end of the carboxyl-terminal end of the D1 domain of the N terminus, with no known function.The major gel-forming mucins (MUC2, MUC5AC, MUC5B, and MUC6) assemble intracellularly to form polymers, first via disulfide-linked dimerization between their carboxyl termini and then via disulfide-linked N-terminal multimerization. However, knowledge of multimerization is incomplete. The MUC5B N-terminal region is assembled exclusively as dimers (17). However, assembly of the MUC2 N-terminal region is more controversial, and it has been reported to assemble solely as trimers (18) or dimers (19). The N-terminal assembly of MUC5AC has not been investigated. It is thought that the unique structural organization of the different gel-forming mucins results in mucus gels optimized to meet the functional demands and provide proper protection to the diverse epithelial environments across the body.MUC5AC mucin production is modulated by both type 1 [e.g., in response to viral infections (20, 21) and cigarette smoke (22)] and type 2 [e.g., in response to allergens (9)] immune responses, associated with lung disease and, indeed, disproportionately increases as compared to MUC5B (4, 8, 9, 23, 24). How MUC5AC contributes to both innate defense of the lung and the pathogenesis of chronic obstructive lung diseases remains unclear. As a first step of understanding the structural, organizational, and functionally distinctive properties of MUC5AC mucin and how these properties may affect the mucus gel organization/properties as compared to the other major lung mucin, MUC5B, we investigated the nature of MUC5AC multimeric organization through its N-terminal domain using an expressed recombinant protein (5ACNT), with a focus on the unique LZ region at the carboxyl-terminal end of the D1 domain. To understand if the LZ region has an organizational role in the assembly of the N-terminal region of MUC5AC, we mutated the four leucine residues in the LZ region of 5ACNT.     

H pylori colocalises with MUC5AC in the human stomach

BACKGROUND: The bacterium Helicobacter pylori is able to adhere to and to colonise the human gastric epithelium, yet the primary gene product responsible as a receptor for its adherence has not been identified. AIMS: To investigate the expression of the gastric mucins MUC5AC and MUC6 in the gastric epithelium in relation to H pylori colonisation in order to examine their possible roles in the binding of H pylori. PATIENTS: Seventy two consecutive patients suspected of having H pylori infection. METHODS: MUC5AC, MUC6, and H pylori were detected in single sections of antral biopsy specimens using immunohistochemical triple staining. RESULTS: MUC5AC was expressed in the superficial epithelium and the upper part of the gastric pits. MUC6 expression was detected in the lower part of the gastric pits. The expression of both mucins in the epithelium was complementary. In each patient, there was a sharply delineated transition between MUC5AC and MUC6 producing cell populations. In all H pylori positive patients there was a striking colocalization of H pylori and MUC5AC; more than 99% of the bacteria were associated with either extracellular MUC5AC or the apical domain of MUC5AC producing cells. CONCLUSIONS: H pylori is very closely associated with extracellular MUC5AC and epithelial cells that produce MUC5AC. This indicates that MUC5AC, but not MUC6, plays a role in the adhesion of H pylori to the gastric mucosa.     

粘蛋白MUC1、MUC2、MUC4和MUC5AC在胰腺导管腺癌中的表达及意义

目的 研究胰腺导管腺癌(pancreatic ductal adenocarcinoma,PDA)组织中粘蛋白MUC1、MUC2、MUC4和MUC5AC的表达及其与临床病理参数间的关系.方法 应用SP免疫组织化学方法检测26例PDA、4例CP、16例正常胰腺组织、2例导管内乳头状黏液性肿瘤(IPMN)、4例实性假乳头状瘤(SPT)和1例浆液性囊性肿瘤(SCN)组织中MUC1、MUC2、MUC4、MUCSAC的表达.结果 正常胰腺和CP组织仅有MUC1表达,表达率均为100%;PDA中MUC1、MUC4和MUC5AC表达率分别为100%、88.5%(23/26)和76.9%(20/26);2例IPMN均见MUC2和MUC5AC表达;SPT和SCN中4种粘蛋白均无表达.MUC4和MUC5AC表达同PDA的临床病理参数之间无相关性(P＞0.05).结论 PDA时存在多种粘蛋白的表达,联合检测MUC1、MUC2、MUC4和MUC5AC的表达可能有助于对PDA的诊断和鉴别诊断.     

血清MUC1、MUC2及MUC5AC表达与胃癌的关系

目的:探讨胃癌血清中MUC1、MUC2及MUC5AC与胃癌的关系.方法:利用黏蛋白MUC1、MUC2及MUC5AC的单抗及多抗,制备黏蛋白芯片,用免疫荧光原理进行检测,并用CEA作为指示指标,对30例胃癌患者及30例健康人进行黏蛋白血清水平的检测.结果:胃癌组与对照组相比,3种黏蛋白血清水平均增高,两组间差异显著.MUC1的阳性表达与胃癌TNM分期相关(P=0.0047),MUC2和MUC5AC的阳性表达与TNM分期无关(P=0.136.P=0.201).3种黏蛋白的表达均随胃癌分化程度降低而阳性表达增高的趋势,各单一黏蛋白以及黏蛋白两两之间联合用于胃癌诊断的敏感性及特异性均较高,其中单一黏蛋白中,MUC1的的敏感性和特异性最好,分别达到81.5%、75.8%,联合诊断(3种黏蛋白中至少2种阳性)的敏感性和特异性达到96.0%、82.9%.结论:检测血清黏蛋白MUC1、MUC2及MUC5AC水平,可以提高胃癌诊断的敏感性及特异性,为早期诊断提供新的思路,并对判断分期及预后提供帮助.     

Expression of the human MUC1 mucin cDNA in a hamster pancreatic tumor cell line HP-1.

A full length cDNA for the human mucin gene, MUC1, under the control of human beta actin promoter, was transfected into a carcinogen induced hamster pancreatic ductal tumor cell line, HP-1. Transfectants were selected by resistance to geneticin. Integration of the foreign human MUC1 cDNA occurred at multiple sites in the genome of HP-1. Northern blot analysis showed MUC1 expression in cells transfected with MUC1 cDNA placed in the correct orientation, but not in control cells (HP-1 cells transfected with vector alone, or with the MUC1 cDNA placed in the antisense orientation). Western blot analysis using monoclonal antibody HMFG-2, which is reactive with the MUC1 protein, showed results consistent with the Northern blot data. Positive immunoperoxidase staining using HMFG-2 was seen in HP-1 cells transfected with MUC1 cDNA but not with untransfected or HP-1 control cells. The integration of human MUC1 mucin gene in HP-1 cells caused no significant change in the growth rate of HP-1 cells in vitro, but resulted in an enhanced growth rate for xenografts of MUC1 transfected HP-1 cells grown in nude mice.     

呼吸道黏蛋白5AC基因顺式调控元件特殊蛋白-1在其转录调控中的作用

目的探讨中性粒细胞弹力酶(neutrophil elastase,NE)诱导气道黏液上皮细胞呼吸道黏蛋白(MUC)5AC产生和mRNA表达以及MUC5AC基因顺式调控元件特殊蛋白-1(specificity protein,Sp-1)在该基因转录调控中的作用。方法2006年3月至9月,在重庆医科大学病毒性肝炎研究所采用酶联免疫吸附试验(ELISA)和反转录聚合酶链反应(RT-PCR)方法分别检测培养细胞经0,10,50,100nmol/LNE刺激诱导5,10,30min后上清液MUC5AC质量浓度和细胞中MUC5ACmRNA表达水平。应用定点突变技术,在重组质粒的基础上建立MUC5AC启动子区Sp-1结合位点和核转录因子(NF)-κB结合位点单独突变体,并测定NE刺激的转染细胞荧光素酶相对活性。结果(1)10,50,100nmol/LNE处理A549细胞30min,相同时间点不同浓度NE组MUC5AC蛋白表达水平分别与对照组比较差异均有显著性意义(t=3·406～20·909,均P<0·05),且呈剂量依赖的趋势(P<0·01)。(2)100nmol/LNE处理30min后A549细胞MUC5ACmRNA相对表达量明显高于对照组(t=10·299,P<0·01)。(3)NE可诱导含有启动子序列-324bp的重组质粒荧光素酶相对光强度(1·430±0·042)及pGL3E-MUC5AC-NF-κB-MU荧光素酶相对光强度(1·570±0·071)增加,与未经NE诱导的未突变对照组相对光强度(0·799±0·051)相比差异具有显著性意义(t=25·675,t=11·110,P均<0·01),而NE不能诱导pGL3E-MUC5AC-Sp-1-MU荧光素酶表达增加(P>0·05)。结论NE可诱导A549细胞MUC5AC产生及其mRNA表达;MUC5AC基因启动子顺式作用元件下游Sp-1位点在NE诱导MUC5AC基因表达机制中起重要作用。     

慢性烟曲霉暴露对支气管哮喘大鼠气道黏蛋白MUC5AC表达的影响

[目的]探讨慢性烟曲霉暴露对支气管哮喘(简称哮喘)大鼠气道黏蛋白MUC5AC表达的影响.[方法]将56只雄性Wistar大鼠按随机数字表法分为7组(每组8只):慢性哮喘(A)组、慢性哮喘+烟曲霉孢子吸入1周(B)、3周(C)和5周(D)组、慢性哮喘+生理盐水吸入(E)组、卵清白蛋白(OVA)致敏生理盐水激发(F)组和OVA致敏生理盐水激发+烟曲霉孢子吸入(G)组.测定各组大鼠基础气道阻力和应用乙酰胆碱后气道阻力变化率,RT-PCR测定肺组织MUC5AC mRNA的表达,免疫组织化学染色测定各组大鼠气道上皮细胞MUC5AC的表达,酶联免疫吸附(ELISA)法测定BALF中IL-13水平,肺组织切片过碘酸雪夫染色(PAS)观察气道上皮杯状细胞增生程度.[结果]B、C和D组大鼠肺组织MUC5AC mRNA(MUC5AC mRNA/β-actin mRNA)(分别为1.9±0.4、2.3±0.6、2.9±0.8)、气道上皮细胞MUC5AC表达(A值)(分别为278±58、566±64、891±80)、BALF上清液IL-13[分别为(96±16)、(136±22)、(197±34)μg/L]及杯状细胞/上皮细胞面积(分别为16％±5％、23％±7％、36％±9％)均高于A、E、F及G组(均P＜0.05);C和D组大鼠气道阻力变化率(分别为61.91％±5.26％、84.69％±6.38％)均高于A、E、F及G组(均P＜0.05).B、C和D组哮喘大鼠MUC5AC的A值及MUC5AC Mma/β-actin mRNA与气道上皮杯状细胞增生程度(PAS染色区面积/上皮细胞面积)呈正相关(r值分别为0.578和0.614,均P＜0.05),与气道反应性(Raw变化率)呈正相关(r值分别为0.638和0.564,均P＜0.05).[结论]慢性烟曲霉暴露可上调哮喘大鼠气道上皮黏蛋白MUC5AC的表达,促进杯状细胞增生,加重气道高反应.     

黏蛋白MUC5AC与肺部疾病的研究进展

黏蛋白是由气道上皮杯状细胞和黏膜下层的黏液细胞分泌的一种高相对分子质量糖蛋白。MUC5AC作为气道黏液中最为重要的黏蛋白,起保护和润滑上皮作用,可防御外来具有生物活性的刺激物质,阻止细菌在气道植入和生长,参与上皮生长、更新和分化,细胞识别和信号传导等。众多研究表明,MUC5AC与肺部疾病如支气管哮喘、COPD、弥漫性泛细支气管炎、支气管扩张、肺癌、肺囊性纤维化等有着密切的关系。随着对其研究的深入,MUC5AC将有望成为新药作用的靶点,在肺部疾病的治疗方面发挥着重要作用。本文就MUC5AC的种类、结构、信号传导通路与肺部疾病的关系进行综述。     

Expression of MUC5AC and MUC5B mucins in normal and cystic fibrosis lung

Hypersecretion of airway mucus is a characteristic feature of chronic airway diseases like cystic fibrosis (CF) and leads via impairment of the muco-ciliary clearance and bacterial superinfection to respiratory failure. The major components of the mucus matrix forming family of mucins in the airways are MUC5AC and MUC5B. To investigate the expression of these glycoproteins in CF, immunohistochemistry was carried out on trachea, bronchi and peripheral lung obtained from CF patients and compared to normal lung tissues. MUC5AC immunohistochemistry demonstrated signals in goblet cells of the epithelial lining. Also, goblet cells inside glandular secretory ducts revealed MUC5AC-positive staining. In comparison to those from normal subjects, CF sections were characterized by inflammatory changes and goblet cell hyperplasia, resulting in increased numbers of MUC5AC-positive cells. Immunohistochemical staining for MUC5B showed abundant staining of submucosal glands and epithelial goblet cells. Inside the glands, the immunoreactivity was restricted to glandular mucous cells. MUC5AC and MUC5B are expressed in the same histological pattern in CF compared to normal tissues with an increase of MUC5AC-positive cells due to goblet cell hyper- and metaplasia.     

The effects of 5-HT on cholinergic contraction in human airways in vitro.

Inhaled 5-hydroxytryptamine (5-HT) causes bronchoconstriction in asthmatics, and 5-HT plasma levels are elevated in asthma. Electrical field stimulation (EFS) of human airways, in vitro, evokes cholinergic contraction mediated by the release of acetylcholine (Ach) from postganglionic cholinergic nerves. The present study investigates whether selective 5-HT agonists and antagonists can modulate EFS-induced cholinergic contraction in human airways in vitro. Human airways, obtained from resections for bronchial carcinoma or organ transplant donors, were suspended under 2-g tension, between two platinum wire electrodes, in carbogenated Krebs solution at 37 degrees C and EFS was applied (1-32 Hz, 50 V, 0.5 ms, 15 s every 4 min) to elicit cholinergic contractions. 5-HT (10 microM-0.3 mM) produced frequency- and concentration-dependent facilitation of cholinergic contraction, but did not displace the concentration/response curve to Ach. Tropisetron (1 microM), a 5-HT3 and 5-HT4 antagonist, completely blocked the facilitatory effect of 5-HT (100 microM), whereas both ondansetron (1 microM) and GR 125478D (1 microM), a selective 5-HT3 and 5-HT4 antagonist, respectively, also attenuated the 5-HT-induced enhancement of cholinergic contraction. This facilitatory effect of 5-HT was partially mimicked by both selective 5-HT3 (2-methyl-5-HT) and 5-HT4 (RS 67333 and 5-methoxytryptamine) agonists. Fluoxetine (10 microM), a 5-HT uptake inhibitor, had no effect on the 5-HT (10-100 microm) induced potentiation of cholinergic contraction. These findings suggest that 5-HT facilitates cholinergic contraction in human airways in vitro through stimulation of both prejunctional 5-HT3 and 5-HT4 receptors. This may implicate a role of 5-HT in asthma.     

胰腺导管内乳头状黏液性肿瘤组织中MUC1,MUC2,MUC5AC和TFF1的表达意义

目的:了解胰腺导管内乳头状黏液性肿瘤(IPMN)中MUC1,MUC2,MUC5AC及TFF1的表达意义.方法:采用免疫组织化学方法,检测IPMN手术切除标本9例中MUC1,MUC2,MUC5AC及TFF1的表达,分析不同组织学类型及不同性质IPMN之间黏液蛋白及TFF1表达的差异.结果:MUC1表达率为44.4%,MUC2为66.7%,MUC5AC和TFF1为100%.胃型IPMN黏液蛋白表达模式主要为MUC1-,MUC2-,MUC5AC .肠型IPMN为MUC1-,MUC2 ,MUC5AC .嗜酸性细胞型IPMN为MUC1 ,MUC2 ,MUC5AC .IPMN相关管状癌MUC1阳性,胶质癌MUC2阳性.MUC5AC和TFF1共同表达,在浸润癌中表达下降.胃型IPMN常与其他类型IPMN同时出现并且不同上皮之间出现移行过渡,提示胃型可能是其他类型IPMN的前期病变.结论:不同组织学亚型的IPMN具有不同的黏液蛋白表达模式.MUC1表达提示侵袭性生物.     

Altered expression of MUC2 and MUC5AC in progression of colorectal carcinoma

AIM:To study the expression profiles of MUC2 and MUC5AC in tumorigenesis of colorectal carcinoma and in its different pathologic types.METHODS:Formalin-fixed,paraffin-embedded human colorectal tissue specimens were immunostained with antibodies against MUC2 and MUC5AC.Six samples of normal mucosa(NM),12 samples of hyperplastic polyp(HP),15 samples of tubular adenoma with low-grade dysplasia(LGD),14 samples of tubular adenoma with high-grade dysplasia(HGD),26 samples of conventional colorectal adenocarcinoma...