Expression of mucin genes in chronic ethmoiditis

Analysis of Bacterial Biofilm Formation and MUC5AC and MUC5B Expression in Chronic Rhinosinusitis Patients

Chronic rhinosinusitis (CRS) is a condition affecting as much as 16% of the adult population in developed countries with many factors attributed to its development, including the more recently proposed role of bacterial biofilm infections. Plenty of research has been conducted on biofilms in CRS and the causes behind the development of such an infection in the nasal cavity and sinuses. One such probable cause is the production of mucin glycoproteins by the mucosa of the nasal cavity. To investigate the possible link between biofilm formation and mucin expression levels and their relationship with CRS etiology, we examined samples from 85 patients by means of spinning disk confocal microscopy (SDCM) to establish their biofilm status and quantitative reverse transcription polymerase chain reaction (qRT-PCR) to determine MUC5AC and MUC5B expression levels. We observed a significantly higher prevalence of bacterial biofilms in the CRS patient group compared to the control group. In addition, we detected higher expression levels of MUC5B but not MUC5AC in the CRS group, which suggested a possible role for MUC5B in CRS development. Finally, we found no direct relationship between biofilm presence and mucin expression levels, thereby showing a multifaceted connection between these two major factors implicated in CRS etiology.

Expression and Clinical Significance of Mucin Gene in Chronic Rhinosinusitis

PURPOSE OF REVIEW

This review highlights the expression and regulation of mucin in CRS and discusses its clinical implications.

RECENT FINDINGS

Chronic rhinosinusitis (CRS) is common chronic nasal disease; one of its main manifestations and important features is mucus overproduction. Mucin is the major component of mucus and plays a critical role in the pathophysiological changes in CRS. The phenotype of CRS affects the expression of various mucins, especially in nasal polyps (NP). Corticosteroids(CS), human neutrophil elastase (HNE), and transforming growth factor-β1 (TGF-β1) are closely related to the tissue remodeling of CRS and regulate mucin expression, mainly MUC1, MUC4, MUC5AC, and MUC5B. "It is expected that CS, HNE and TGF - β could be used to regulate the expression of mucin in CRS." However, at present, the research on mucin is mainly focused on mucin 5AC and mucin 5B, which is bad for finding new therapeutic targets. Investigating the expression and location of mucin in nasal mucosa and understanding the role of various inflammatory factors in mucin expression are helpful to figure out regulatory mechanisms of airway mucin hypersecretion. It is of great significance for the treatment of CRS.

Mucins and Pathogenic Mucin-Like Molecules Are Immunomodulators During Infection and Targets for Diagnostics and Vaccines

Mucins and mucin-like molecules are highly O-glycosylated proteins present on the cell surface of mammals and other organisms. These glycoproteins are highly diverse in the apoprotein and glycan cores and play a central role in many biological processes and diseases. Mucins are the most abundant macromolecules in mucus and are responsible for its biochemical and biophysical properties. Mucin-like molecules cover various protozoan parasites, fungi and viruses. In humans, modifications in mucin glycosylation are associated with tumors in epithelial tissue. These modifications allow the distinction between normal and abnormal cell conditions and represent important targets for vaccine development against some cancers. Mucins and mucin-like molecules derived from pathogens are potential diagnostic markers and targets for therapeutic agents. In this review, we summarize the distribution, structure, role as immunomodulators, and the correlation of human mucins with diseases and perform a comparative analysis of mucins with mucin-like molecules present in human pathogens. Furthermore, we review the methods to produce pathogenic and human mucins using chemical synthesis and expression systems. Finally, we present applications of mucin-like molecules in diagnosis and prevention of relevant human diseases.

A Comprehensive Systematic Review of the Association Between Airway Mucins and Chronic Rhinosinusitis

Objective

Airway mucins are the major constituents of mucus and one of the first lines of host defense against inhaled pathogens. However, aberrant expression of mucins is associated with mucus hypersecretion resulting in chronic nasal drainage, a common complaint from patients with chronic rhinosinusitis (CRS). Our goal in this systematic review was to determine (1) expression profiles, (2) regulatory mechanisms, and (3) the pathologic roles of mucins associated with CRS.

Methods

MEDLINE, Cochrane Library, Embase, Scopus, Web of Science, and ClinicalTrials.gov were searched for studies focused on the role of mucins in CRS. Quality was assessed using the Cochrane Risk of Bias tool. The full text articles selected were then categorized into 3 study groups: (1) clinical, (2) animal, and (3) in vitro cultures. Data regarding study design, population/setting, methods, and bias were extracted and synthesized.

Results

Our initial search generated 392 titles/abstracts. After the primary review, 111 articles underwent secondary review. The final review included 53 articles, including 34 articles (64%) in the clinical study group, 3 articles (6%) in the animal study group, and 16 articles (30%) in the in vitro study group. In total, aberrant expression of 8 mucins—6 secreted-mucins (MUC2, -5AC, -5B, -6, -7, and -8) and 2 membrane-bound mucins (MUC1 and -4)—were identified in CRS tissues compared to healthy controls. Mucin expression was associated with bacterial sinusitis, inflammatory markers, and the response to steroid therapy in patients with CRS with nasal polyposis.

Conclusion

There is a strong correlation between alterations in mucin expression profiles and CRS. This systematic review highlights the most recent literature on the role of mucins in CRS. The analysis of these studies is limited by the heterogeneity in study designs, relatively few numbers of clinical samples, and lack of mechanistic studies in animal models and in vitro cultures.

Exploring the role and diversity of mucins in health and disease with special insight into non-communicable diseases

Mucins are major glycoprotein components of the mucus that coats the surfaces of cells lining the respiratory, digestive, gastrointestinal and urogenital tracts. They function to protect epithelial cells from infection, dehydration and physical or chemical injury, as well as to aid the passage of materials through a tract i.e., lubrication. They are also implicated in the pathogenesis of benign and malignant diseases of secretory epithelial cells. In Human there are two types of mucins, membrane-bound and secreted that are originated from mucous producing goblet cells localized in the epithelial cell layer or in mucous producing glands and encoded by MUC gene. Mucins belong to a heterogeneous family of high molecular weight proteins composed of a long peptidic chain with a large number of tandem repeats that form the so-called mucin domain. The molecular weight is generally high, ranging between 0.2 and 10 million Dalton and all mucins contain one or more domains which are highly glycosylated. The size and number of repeats vary between mucins and the genetic polymorphism represents number of repeats (VNTR polymorphisms), which means the size of individual mucins can differ substantially between individuals which can be used as markers. In human it is only MUC1 and MUC7 that have mucin domains with less than 40% serine and threonine which in turn could reduce number of PTS domains. Mucins can be considered as powerful two-edged sword, as its normal function protects from unwanted substances and organisms at an arm's length while, malfunction of mucus may be an important factor in human diseases. In this review we have unearthed the current status of different mucin proteins in understanding its role and function in various non-communicable diseases in human with special reference to its organ specific locations. The findings described in this review may be of direct relevance to the major research area in biomedicine with reference to mucin and mucin associated diseases.

Clinicopathological and prognostic significance of MUC-2, MUC-4 and MUC-5AC expression in japanese gastric carcinomas

BACKGROUND

The mucin components of the gastric gel layer function as a protective and lubricating factor against luminal acid and proteolytic enzymes. Alteration of mucin expression in gastric preneoplastic and neoplastic lesions has suggested potential roles in neoplastic processes. This study aimed to assess the clinicopathological and prognostic significance of MUC-2, MUC-4 and MUC-5AC in Japanese gastric cancer.

METHODS

Expression of MUC-2, -4 and -5AC was evaluated on tissue microarrays of gastric carcinomas and adjacent non-cancerous mucosa specimens by immunohistochemistry and compared with clinicopathological parameters and survival time of the patients.

RESULTS

The three mucins were found to be expressed to a lesser extent in gastric carcinomas in comparison with non-cancerous mucosa (p<0.05). MUC-2 expression was negatively correlated with tumor size, depth of invasion, and TNM staging of gastric cancer (p<0.05), while that of MUC-5AC was negatively associated with the depth of invasion, venous invasion, lymph node metastasis and TNM staging (p<0.05), but positively with MUC-4 and MUC-2 expression (p<0.05). There was higher MUC-2 expression in intestinal- than diffuse-type carcinomas (p<0.05). Kaplan-Meier analysis indicated no relationship between expression of the three mucins and the cumulative survival rate of patients, even stratified according to the depth of invasion (p>0.05).

CONCLUSION

Down-regulated expression of MUC-2, -4 and -5AC may be involved in pathogenesis, invasion, metastasis or differentiation of gastric carcinoma. Their altered expression might therefore be employed as an indicator of pathobiological behavior.

Sinus microbiome diversity depletion and Corynebacterium tuberculostearicum enrichment mediates rhinosinusitis

Persistent mucosal inflammation and microbial infection are characteristics of chronic rhinosinusitis (CRS). Mucosal microbiota dysbiosis is found in other chronic inflammatory diseases; however, the relationship between sinus microbiota composition and CRS is unknown. Using comparative microbiome profiling of a cohort of CRS patients and healthy subjects, we demonstrate that the sinus microbiota of CRS patients exhibits significantly reduced bacterial diversity compared with that of healthy controls. In our cohort of CRS patients, multiple, phylogenetically distinct lactic acid bacteria were depleted concomitant with an increase in the relative abundance of a single species, Corynebacterium tuberculostearicum. We recapitulated the conditions observed in our human cohort in a murine model and confirmed the pathogenic potential of C. tuberculostearicum and the critical necessity for a replete mucosal microbiota to protect against this species. Moreover, Lactobacillus sakei, which was identified from our comparative microbiome analyses as a potentially protective species, defended against C. tuberculostearicum sinus infection, even in the context of a depleted sinus bacterial community. These studies demonstrate that sinus mucosal health is highly dependent on the composition of the resident microbiota as well as identify both a new sino-pathogen and a strong bacterial candidate for therapeutic intervention.

Muco-ciliary differentiation of nasal epithelial cells is decreased after wound healing in vitro

BACKGROUND

Epithelial damage and modifications of cell differentiation are frequent in airway diseases with chronic inflammation, in which transforming growth factor-beta1 (TGF-beta1) plays an important role. The aim of this study was to evaluate the differentiation of human nasal epithelial cells (HNEC) after wound healing and the potential effects of TGF-beta1.

METHODS

Basal, mucus, and ciliated cells were characterized by cytokeratin-14, MUC5AC, and betaIV tubulin immunodetection, respectively. Their expression was evaluated in situ in nasal polyps and in an in vitro model of wound healing in primary cultures of HNEC after wound closure, under basal conditions and after TGF-beta1 supplementation. Using RT-PCR, the effects of TGF-beta1 on MUC5AC and DNAI1 genes, specifically transcribed in mucus and ciliated cells, were evaluated.

RESULTS

In situ, high TGF-beta1 expression was associated with low MUC5AC and betaIV tubulin expression. In vitro, under basal conditions, MUC5AC expression remained stable, cytokeratin-14 expression was strong and decreased with time, while betaIV tubulin expression increased. Transforming growth factor-beta1 supplementation downregulated MUC5AC and betaIV tubulin expression as well as MUC5AC and DNAI1 transcripts.

CONCLUSION

After a wound, differentiation into mucus and ciliated cells was possible and partially inhibited in vitro by TGF-beta1, a cytokine that may be involved in epithelial remodeling observed in chronic airway diseases.

Localization and expression of MUC5B and MUC7 mucins in pediatric sinus mucosa

OBJECTIVES

The purpose of this study was to analyze the secretory cell population and distribution of MUC5B and MUC7 mucins in the sinus mucosa of pediatric patients with and without chronic rhinosinusitis (CRS).

METHODS

Sinus mucosal specimens were collected at surgery in a pediatric tertiary care facility. Histologic, immunohistochemical, and morphometric analyses were performed on sinus mucosa of 20 children with CRS and 7 children without CRS.

RESULTS

A significant increase in the area of submucosal glands was evident in the sinus mucosa of children with CRS as compared to controls. MUC5B and MUC7 mucins were expressed in the submucosal glands, as well as in goblet cells, in the sinus mucosa of both populations. No differences in MUC5B or MUC7 expression were observed when mucin expression was normalized to glandular area.

CONCLUSIONS

Children with CRS have an increased number of submucosal glands, indicating that glandular mucins contribute to mucus overproduction in CRS. MUC5B and MUC7 mucins, which have previously been considered only glandular mucins, are also expressed in goblet cells in the sinus mucosa.

Expression profiles of MUC mucins and trefoil factor family (TFF) peptides in the intrahepatic biliary system: physiological distribution and pathological significance

Mucin secreted by mucosal epithelial cells plays a role in the protection of the mucosal surface and also is involved in pathological processes. So far, MUC1-4, 5AC, 5B, 6-8, 11-13 and 15-17 genes coding the backbone mucin core protein have been identified in humans. Their diverse physiological distribution and pathological alterations have been reported. Trefoil factor family (TFF) peptides are mucin-associated molecules co-expressed with MUC mucins and involved in the maintenance of mucosal barrier and the biological behavior of epithelial and carcinoma cells. Intrahepatic biliary system is a route linking the bile canaliculi and the extrahepatic bile duct for the excretion of bile synthesized by hepatocytes. Biliary epithelial cells line in the intrahepatic biliary system, secreting mucin and other molecules involved in the maintenance and regulation of the system. In this review, the latest information regarding properties, expression profiles and regulation of MUC mucins and TFF peptides in the intrahepatic biliary system is summarized. In particular, we focus on the expression profiles and their significance of MUC mucins in developmental and normal livers, various hepatobiliary diseases and intrahepatic cholangiocarcinoma.

Mucins and TFF peptides of the tear film and lacrimal apparatus

The three-dimensional organization of the tear film, which is produced and drained by the different structures of the ocular adnexa, is essential for maintainance and protection of the ocular surface. This is facilitated by a class of large, highly glycosylated, hydrophilic glycoproteins, the mucins, which are usually expressed in association with a class of peptides having a well-defined, structurally conserved trefoil domain, the mammalian trefoil factor family (TFF) peptides. In this review, the latest information regarding mucin and TFF peptide function and regulation in the human lacrimal system, the tear film and the ocular surface is summarized with regard to mucous epithelia integrity, rheological and antimicrobial properties of the tear film and tear outflow, age-related changes and certain disease states such as dry eye, dacryostenosis and dacryolith formation.

Immunohistochemical analyses of MUC5AC mucin expression in sinus mucosa of children with sinusitis and controls

OBJECTIVES

The purpose of this study was to analyze MUC5AC protein expression in sinus mucosal specimens of children with and without chronic sinusitis.

METHODS

Morphometric, histologic, and immunohistochemical analyses were carried out on sinus mucosa of 7 children with chronic sinusitis and 6 children without sinusitis.

RESULTS

MUC5AC protein was expressed in a subset of goblet cells in the surface epithelium, but not in the submucosal glands in either pediatric population. The number of goblet cells that expressed MUC5AC mucin was not significantly different in patients with and without chronic sinusitis. All specimens had similar numbers of goblet cells in the surface epithelium.

CONCLUSIONS

The data demonstrate that neither goblet cell hyperplasia nor increased MUC5AC expression occurs in the sinus mucosa of children with chronic sinusitis. This suggests that in contrast to asthma, in which goblet cell hyperplasia is present in the lower respiratory tract, mucus hypersecretion in pediatric chronic sinusitis may involve other secretory cells, eg, submucosal glandular cells, and mucins secreted by these glandular cells.

Prognostic value of mucins in the classification of ampullary carcinomas

The ampulla of Vater is of high clinical relevance with regard to influx of chyme, ascending inflammation, intubation during diagnostic and therapeutic endoscopic investigation, therapeutic papillotomy, and especially to malignant transformation. Little is known about the distribution of mucins in the ampulla. In this study, we have investigated the mucin distribution in the normal ampulla of Vater and compared it to duodenal mucosa and Brunner glands. Expression of mucins in the ampulla of Vater and duodenum was monitored by reverse transcription-polymerase chain reaction and localization of the products by immunohistochemistry. The samples investigated originated from 30 autopsy cases. Mucins MUC1, MUC3, MUC4, MUC5AC, MUC5B, MUC6, MUC7, and MUC8 were expressed in the ampulla of Vater. Immunohistochemistry revealed production of MUC4, MUC5AC, MUC5B, and MUC6. The mucin composition varied in comparison with the duodenum referring to MUC2, MUC7, and MUC8. Detected mucins contribute to innate immunity, epithelial restitution, and protection against the aggressive secretions of the liver, gall bladder, and pancreas. By cross-linking, they influence the rheological properties of the secretions in the ampulla and facilitate unidirectional flow into the duodenum. Knowledge of their pattern of expression has prognostic value with regard to the detection of malignancy. The observed differences in the mucin distribution between the duodenum and the ampulla of Vater support the use of MUC2, MUC7, and MUC8 as useful tool in the classification of ampullary carcinomas.

Cell and molecular biology of human lacrimal gland and nasolacrimal duct mucins

The old concept that the lacrimal gland is only a serous gland has been superseded by the finding that lacrimal acinar cells are able to produce mucins--high-molecular-weight proteins--the major mass being carbohydrates with the common feature of tandem repeats of amino acids rich in serine, threonine, and proline in the central domain of the mucin core peptide. At the ocular surface, maintenance of the tear film, lubrication, and provision of a pathogen barrier on the epithelia, conjunctiva, and cornea have been shown to be facilitated by mucins that are present in membrane-anchored (lining epithelial cells) or secreted (goblet cells) form. Also in the lacrimal gland, both membrane-anchored (MUCs 1, 4, and 16) and secreted (MUCs 5B and 7) mucins have been identified. The lacrimal gland is the main contributor to the aqueous portion of the tear film. It is part of the lacrimal apparatus that comprises, together with the lacrimal gland, the paired lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, which collects the tear fluid and conveys it into the nasal cavity. In this review, the latest information regarding mucin function in the human lacrimal gland and the human efferent tear ducts is summarized with regard to mucous epithelia integrity, rheological and antimicrobial properties of the tear film and tear outflow, age-related changes, and certain disease states such as the pathogenesis of dry eye, dacryostenosis, and dacryolith formation.

Tr�nendr�senassoziierte Muzine

BACKGROUND

The secretory cells of the human lacrimal gland show a PAS-positive reaction in cytochemical staining procedures, suggesting the production of mucous substances. Recently, these substances were differentiated according to modern molecular classifications.

RESULTS

Expression studies detected mRNA for MUC1, MUC4, MUC5AC, MUC5B, MUC6, and MUC7, whereas MUC2 transcripts were absent in all samples investigated. Immunohistochemistry revealed membrane-bound MUC1 at the apical surface of acinar cells, MUC5AC associated with goblet cells of excretory ducts, MUC5B and MUC7 in the cytoplasm of acinar cells, and MUC7 also in epithelial cells of excretory ducts. MUC2 (RT-PCR negative) and MUC6 (RT-PCR positive) were not detectable by immunohistochemistry. MUC4 mRNA was present in all samples from patients treated for dry eye but only in 6 of 30 glands from individuals who did not receive treatment with artificial tears. Dot-blot analyses clearly revealed increased amounts of MUC4, MUC5AC and MUC5B in the glands of elderly women who received treatment for dry eye as compared to the remaining samples.

CONCLUSION

These results confirm that the human lacrimal gland synthesizes a spectrum of mucins, some of which might be involved in the pathophysiology of dry eye syndrome.

MUC8 mucin gene up-regulation in chronic rhinosinusitis

The primary mechanisms leading to mucus hypersecretion in chronic sinus inflammation are not well understood. This study aims to investigate the expression of MUC8 messenger RNA (mRNA) and protein and to compare between normal and chronically inflamed sinus mucosae in terms of the expression of MUC8 mRNA. Ten patients with chronic rhinosinusitis who were undergoing functional endoscopic sinus surgery were recruited for the study. Ten patients with no evidence of sinus disease were used as control subjects. RNAs were extracted from sinus mucosa, and semiquantitative reverse transcription-polymerase chain reaction was performed for MUC8. Localization of MUC8 protein was sought by immunohistochemical analysis. Messenger RNA encoding MUC8 was detected in human sinus mucosa. The level of MUC8 mRNA in chronic rhinosinusitis was significantly increased compared with that in normal maxillary sinus mucosa. We found more intense expression of MUC8 protein in the sinuses with chronic rhinosinusitis than in normal sinus mucosa. These results suggest that MUC8 may play an important role in the pathogenesis of sinus hypersecretion in chronic rhinosinusitis.

LPS up-regulates mucin and cytokine mRNA expression and stimulates mucin and cytokine secretion in goblet cells

Bacterial inflammation in mucosa is accompanied by morphological and proliferative changes in goblet cells and mucin hypersecretion. Main stimulators of bacterial inflammation are bacterial lipopolysaccharides (LPS). In vitro investigation of the LPS effect on the molecular processes in goblet cells, using the human mucin-secreting goblet cell line HT29-MTX, showed the following results. LPS up-regulated mucin and cytokine mRNA expression and secretion in goblet cells in a concentration and time-dependent manner, with a maximum output at an LPS concentration of 100 ng/ml. LPS (100 ng/ml) increased mRNA expression of MUC5AC (2.4x), MUC5B (2.1x), and IL-8 (2.3x) and stimulated secretion of mucins (MUC5AC up to 39%, MUC5B up to 31%) and the inflammatory cytokine IL-8 (up to 10x). A significant correlation was found between the LPS-induced IL-8 secretion and secretion of mucins. These results suggest: (1) goblet cells, responding to the direct stimulation of bacterial LPS by two inflammatory-related processes such as production and secretion of the gel-forming mucins and the inflammatory cytokine IL-8, can be considered as an important part of mucosal immunity and (2) LPS- induced goblet cell mucin secretion can occur partly via IL-8-dependent pathway.

Effects of dexamethasone on mucin gene expression in cultured human nasal epithelial cells

OBJECTIVE

To clarify 1) which mucin gene expression is influenced by glucocorticoid and 2) whether glucocorticoid influences steady-state mucin expression or mucin gene expression induced by lipopolysaccharide.

METHODS

Dissociated cells obtained from nasal polyps were cultured on a collagen gel substrate in an air-liquid interface. Dexamethasone was added to the culture medium in the steady-state and prior to the stimulation by LPS. RNAs were extracted from culture cells, and semiquantitative reverse transcriptase-polymerase chain reaction was performed for MUC2, MUC5AC, MUC5B, MUC8, and beta-actin.

RESULTS

Dexamethasone did not influence steady-state messenger RNA levels of either mucin gene. Dexamethasone suppressed lipopolysaccharide-induced messenger RNA levels of MUC8.

CONCLUSION

Glucocorticoid does not influence steady-state mucin gene expression but suppresses mucin gene expression induced by secretagogues such as lipopolysaccharide.