Mucinas salivales: estructura química, mecanismos de liberación y participación en la defensa no inmunológica de la cavidad bucal / Salivary mucins: chemical structure, release mechanisms and participation in the non-immunological defense of the oral cavity

En este artículo se describen: 1) las características físico-químicas de las mucinas salivales, denominadas MG1 y MG2. 2) El mecanismo de secreción por estimulación simpática y parasimpática. 3) La distinta participación de MG1 y MG2 tanto en la actividad deglutoria como en los mecanismos de defensa de la cavidad bucal, en relación con sus propiedades físico-químicas. 4) El rol de las mucinas salivales en la protección de la mucosa del tracto gastrointestinal. 5) La relación entre las mucinas saliales y las patologías de la cavidad bucal.

Neutrophil Elastase Causes MUC5AC Mucin Synthesis Via EGF Receptor, ERK and NF-kB Pathways in A549 Cells

BACKGROUND: Neutrophil elastase (NE) was found to increase the respiratory mucin gene, MUC5AC, although the molecular mechanisms of this process remain unknown. We attempted to determine the signal transduction pathway through which NE induces MUC5AC gene expression in bronchial epithelial cells. METHODS: A fragment of 1.3 Kb MUC5AC promoter which had been cloned into the pGL3-Basic luciferase vector was transfected to the A549 cells. By measuring the luciferase activity, we were able to evaluate the MUC5AC promoter activity in A549 cells. The involvement of mitogen-activated protein kinases (MAPK) was confirmed by Western blotting. To confirm the involvement of nuclear factor kappaB (NF-kB), we used site-directed mutagenesis and electrophoretic mobility shift assay (EMSA) autoradiogram. The MUC5AC mRNA expression was confirmed by RT-PCR. RESULTS: NE increased the transcriptional activity of the MUC5AC promoter in A549 cells. The increased transcriptional activity of the MUC5AC promoter by NE was found to be associated with increased NF-kB activity. Site-directed mutagenesis showed that the transfection of the mutated NF-kB binding sites from the PGL3-MUC5AC-3752 promoter luciferase reporter plasmid decreased the luciferase activity after NE stimulation. Among the MAPKs, only extracellular signal-regulated kinases (ERK) were involved in this NE-induced MUC5AC mucin expression. RT-PCR also showed that NE increased MUC5AC mRNA. An EMSA autoradiogram revealed that NE induced NF-kB: DNA binding. CONCLUSIONS: These results indicate that human NE induces MUC5AC mucin through the epidermal growth factor receptor (EGF-R), ERK, and NF-kB pathways in A549 cells.

Effects of glucocorticoid on IL-13-induced Muc5ac expression in airways of mice / 华中科技大学学报（医学）（英德文版）

To study the effects of glucocorticoid on the IL-13-induced Muc5ac expression in airways of mice, and investigate its role in mucus secretion of airways, 24 pathogen-free BALB/c mice were randomly divided into 3 groups. IL-13 group received an nasal instillation of 100 microg of recombinant murine IL-13 solution on days 1, 3 and 5. In dexamethasone group, dexamethasone (0.5 mg/kg) was administered intraperitoneally 24 h before and 1 h before the first instillation of IL-13 and on 4 consecutive days (day 0 to day 5, 6 consecutive days in total), while control group was not treated with IL-13 or dexamethasone. Bronchoalveolar lavage fluid (BALF) was collected and eosinophils were counted, and expression of Muc5ac mRNA and protein in lungs were detected by reverse transcription-polymerase chain reaction (RT-PCR) technology and immunohistochemical assay respectively. Our results showed that the number of mice, with positve Muc5ac protein expression, expression of Muc5ac mRNA and eosinophils in BALF after IL-13 treatment were all significantly higher than that of control group (all P<0.01). Despite eosinophils reduced (P<0.01), the number of mice with positive Muc5ac protein expression, expression of Muc5ac mRNA afterdexamethasone treatment didn't decreas significantly as compared with that of IL-13 group. It is concluded that IL-13 can up-regulate the expression of Muc5ac mRNA and protein, which may play a pivotal role in the mucus overproduction of airways. Dexamethasone can suppress IL-13-induced eosinophilic infiltration in lung but can't inhibit the mucus overproduction.

Interleukin-1 beta Induces MUC2 Gene Expression and Mucin Secretion via Activation of PKC-MEK/ERK,and PI3K in Human Airway Epithelial Cells

Interleukin 1 beta (IL-1 beta), a proinflammatory cytokine, is related with inflammatory diseases and it up-regulates MUC2 gene expression and mucin secretion. This study was designed to investigate the signal transduction pathway of the IL-1 beta-mediated MUC2 gene expression and mucin secretion in human airway epithelial cells. In cultured human airway NCI-H292 epithelial cells, the steady state of the mRNA level of MUC2 gene expression and mucin secretion induced by IL-1 were determined by reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme immunoassay, and immunoblot analysis. To observe the signal pathway of the IL-1 beta-mediated MUC2 gene expression and mucin secretion, we used several specific inhibitors. PD98059 (MEK/ERK inhibitor) suppressed IL-1 beta-mediated MUC2 gene expression and mucin secretion, while SB203580 (p38 inhibitor) did not. Ro31-8220 (PKC inhibitor) inhibited IL-1 beta-mediated MUC2 gene expression and mucin secretion. It inhibited ERK phosphorylation, but did not inhibit p38 phosphorylation. LY294002 (PI3K inhibitor) also suppressed MUC2 expression, but did not inhibit any MAPKs phosphorylation. These results suggest that the IL-1 -mediated MUC2 gene expression and mucin secretion in NCI-H292 cells are regulated through activation of the PKC-MEK/ERK pathway, and that PI3K is also involved in the IL-1 beta-mediated MUC2 gene expression and mucin secretion.

Coexpression of MUC1 with p53 or MUC2 correlates with Lymph Node Metastasis in Colorectal Carcinomas

The alteration of the mucin profile have been known to play a role in colorectal carcinogenesis. MUC1 is up-regulated and MUC2 is down-regulated in colorectalcarcinomas. Overexpression of p53 is frequently noted in colorectal carcinomas with deep invasion or lymph node metastasis. However, there have been few reports about the association between MUC1, MUC2, and p53 expression with respect to the metastatic potential. This study was aimed to investigate the relationship of MUC1, MUC2, and protein p53 expressions with clinicopathological factors in colorectal carcinomas. Expressions of MUC1, MUC2, and p53 protein were examined immunohistochemically. Of total 97 cancers, 44 (45%) were MUC1 positive, 39 (40%) were MUC2 positive and 58 (59%) showed a p53 overexpression. Coexpression of MUC1 with p53 and dual expression of MUC1 with MUC2 were associated with a higher frequency of lymph node metastasis (p<0.05). The right colon showed a higher MUC1 positivity and frequent lymph node metastasis than the left colon (p<0.05). These results suggest that the coexpression of MUC 1 with p53 or MUC2 are involved in regional lymph node metastasis in colorectal carcinomas. The high expression of MUC1 in the right colon cancer was revealed to relate with lymph node metastasis.

Orcein-alcian blue technique for demonstration of prostatic mucins

Mucin production by prostatic carcinomas has been recognized for many years. The identification of acidic mucin with an appropriate stain may be useful in routine diagnostic surgical pathology. In this study of 30 cases of prostatic carcinoma, 6 [20%] demonstrated significant sulfated acid mucin production by tumor cells. All of the tumors which produced significant amount of mucin were either moderately or well differentiated while, tumors of poor differentiation showed less mucin. The use of such relatively simple, inexpensive histochemical stain such as modified orcein-alcian blue may help to confirm suspicions gleaned from a crushed needle biopsy and convert an equivocal report to definitive diagnosis

Histologia, histopatologia e histoquímica de mucinas do fundo e do corpo do estômago em Philander opossum / Histology, histopathology and mucins histochemistry of the stomach fundus and body in Philander opossum

Foram realizados estudos histológicos, histopatológicos e histoquímicos de mucinas do epitélio gástrico do fundo e do corpo de seis cuicas de quatro olhos (PPhilander opossum), adultos e de ambos os sexos. Os animais forma separados em dois grupos e submetidos a dois tipos diferentes de alimentaçäo. A morfologia do fundo e do corpo gástrico da cuica segue o padräo histológico geral para a maioria dos mamíferos. Nos animais submetidos a alimentaçäo natural, a mucosa apresentou-se com características normais. Naqueles cujos hábitos alimentares näo foram preservados após a captura e mantidos em biotério, verificou-se a ocorrência de células com significativa degeneraçäo hidrópica no epitélio de revestimento da mucosa, das fossetas e nas glândulas. Esta degeneraçäo foi mais intensa nas células parietais. Sugere-se ao se trabalhar com animais silvestres, sacrificá-los logo após a captura ou proporcionar aos mesmos alimentaçäo adequada. A mudança de alimentaçäo pode causar lesöes no estômago. Mucina neutras foram evidenciada no epitélio de revestimento da mcuosa, das fossetas e nas células mucosas do colo de todos os animais estudados

Aspectos histológicos, histopatológicose histoquímicos de mucinas do epitélio gástrico da regiäo pilórica de Philander opossum / Some histological, histopathological and histochemical (Mucins) aspects of the gastric epitheluim of pyloric region in Phelander Opossum

Estudos histológicos, histopatológicos e histoquímicos de mucinas do epitélio gástrico da regiäo pilórica de seis cuicas em jejum, foram realizados. Os animais eram adultos, de ambos os sexos e foram separados em dois grupos submetidos a diferentes dietas alimentares. A morfologia da regiäo pilórica da cuica (Philander opossum) segue o plano histológico geral para a maioria dos mamíferos. Nos animais submetidos `a alimentaçäo natural e mucosa apresentou-se normal. Naqueles cujos hábitos alimentares näo foram preservados após a captura e mantidos em biotério, verificou-se a ocorrência de células com significativa degeneraçäo hidrópica no epitélio de revestimento da mucosa e nas fovéolas. Nas células secretoras das glândulas pilóricas a degeneraçäo hidrópica foi discreta. Sugere-se ao se trabalhar com animais silvestres, sacrificá-los logo após a captura ou maior cuidado na preservaçäo de seus hábitos alimentares. A mudança de alimentaçäo pode causar lesöes no estômago. Mucinas neutras foram detectadas no epiélio de revestimento da mucosa, epitélio das fovéolas e nas glândulas pilóricas. Näo houve diferenças nas mucinas detectadas nos animais submetidos `as diferentes condiçöes de alimentaçäo