Mucin gene 19 (MUC19) expression and response to inflammatory cytokines in middle ear epithelium

Peptidome analysis of umbilical cord mesenchymal stem cell (hUC-MSC) conditioned medium from preterm and term infants

Background

The therapeutic role of mesenchymal stem cells (MSCs) has been widely confirmed in several animal models of premature infant diseases. Micromolecule peptides have shown promise for the treatment of premature infant diseases. However, the potential role of peptides secreted from MSCs has not been studied. The purpose of this study is to help to broaden the knowledge of the hUC-MSC secretome at the peptide level through peptidomic profile analysis.

Methods

We used tandem mass tag (TMT) labeling technology followed by tandem mass spectrometry to compare the peptidomic profile of preterm and term umbilical cord MSC (hUC-MSC) conditioned medium (CM). Gene Ontology (GO) enrichment analysis and ingenuity pathway analysis (IPA) were conducted to explore the differentially expressed peptides by predicting the functions of their precursor proteins. To evaluate the effect of candidate peptides on human lung epithelial cells stimulated by hydrogen peroxide (H₂O₂), quantitative real-time PCR (qRT-PCR), western blot analysis, and enzyme-linked immunosorbent assay (ELISA) were, respectively, adopted to detect inflammatory cytokines (TNF-α, IL-1β, and IL-6) expression levels at the mRNA and protein levels.

Results

A total of 131 peptides derived from 106 precursor proteins were differentially expressed in the preterm hUC-MSC CM compared with the term group, comprising 37 upregulated peptides and 94 downregulated peptides. Bioinformatics analysis showed that these differentially expressed peptides may be associated with developmental disorders, inflammatory response, and organismal injury. We also found that peptides ⁷¹¹⁸TGAKIKLVGT⁷¹²⁷ derived from MUC19 and ⁵⁰⁸AAAAGPANVH⁵¹⁷ derived from SIX5 reduced the expression levels of TNF-α, IL-1β, and IL-6 in H₂O₂-treated human lung epithelial cells.

Conclusions

In summary, this study provides further secretomics information on hUC-MSCs and provides a series of peptides that might have antiinflammatory effects on pulmonary epithelial cells and contribute to the prevention and treatment of respiratory diseases in premature infants.

Human Metapneumovirus Induces Mucin 19 Which Contributes to Viral Pathogenesis

Human Metapneumovirus (HMPV) remains one of the most common viral infections causing acute respiratory tract infections, especially in young children, elderly, and immunocompromised populations. Clinical symptoms can range from mild respiratory symptoms to severe bronchiolitis and pneumonia. The production of mucus is a common feature during HMPV infection, but its contribution to HMPV-induced pathogenesis and immune response is largely unknown. Mucins are a major component of mucus and they could have an impact on how the host responds to infections. Using an in vitro system and a mouse model of infection, we identified that Mucin 19 is predominantly expressed in the respiratory tract upon HMPV infection. Moreover, the lack of Muc19 led to an improved disease, lower lung viral titers and a decrease in the number of CD4+ T cells. These data indicate that mucin 19 contributes to the activation of the immune response to HMPV and to HMPV-induced pathogenesis.

Antibiotic modulation of mucins in otitis media; should this change our approach to watchful waiting?

BACKGROUND

Gel-forming mucins (GFMs) play important roles in otitis media (OM) pathogenesis. Increased mucin expression is activated by pathogens and proinflammatory cytokines. Bacterial biofilms influence inflammation and resolution of OM and may contribute to prolonged mucin production. The influence of specific pathogens on mucin expression and development of chronic OM with effusion (OME) remains an area of significant knowledge deficit.

OBJECTIVES

To assess the relationship between GFM expression, specific pathogens, middle ear mucosal (MEM) changes, biofilm formation, and antibiotic utilization.

METHODS

Mixed gender chinchillas were inoculated with nontypeable Haemophilus influenzae (NTHi) strain 86028NP or Streptococcus pneumoniae (SP) strain TIGR4 via transbulla injection. Antibiotic was administered on day 3-5 post inoculation. GFM expression was measured by quantitative PCR. Biofilm formation was identified and middle ear histologic changes were measured.

RESULTS

SP infection resulted in higher incidence of biofilm and ME effusion compared with NTHi infection. However, NTHi persisted in the ME longer than SP with no substantive bacterial clearance detected on day 10 compared with complete bacterial clearance on day 10 for 50-60% of the SP-infected chinchillas. Both infections increased MEM inflammatory cell infiltration and thickening. NTHi upregulated the Muc5AC, Muc5B and Muc19 expression on day 10 (p = 0.0004, 0.003, and 0.002 respectively). SP-induced GFM upregulations were trended toward significant. In both NTHi and SP infections, the degree of GFM upregulation had a direct relationship to increased MEM hypertrophy, inflammatory cell infiltration and biofilm formation. Antibiotic treatment reduced the incidence of ME effusion and biofilm, limited the MEM changes and reversed the GFM upregulation. In NTHi infection, the rate of returning to baseline level of GFMs in treated chinchillas was quicker than those without treatment.

CONCLUSIONS

In an animal model of OM, GFM genes are upregulated in conjunction with MEM hypertrophy and biofilm formation. This upregulation is less robust and more quickly ameliorated to a significant degree in the NTHi infection with appropriate antibiotic therapy. These findings contribute to the understanding of pathogen specific influences on mucin expression during OM pathogenesis and provide new data which may have implications in clinical approach for OM treatment.

Gene expression vs. sequence divergence: comparative transcriptome sequencing among natural Rhinolophus ferrumequinum populations with different acoustic phenotypes

BACKGROUND

Although the sensory drive hypothesis can explain the geographic variation in echolocation frequencies of some bat species, the molecular mechanisms underlying this phenomenon are still unclear. The three lineages of greater horseshoe bat (Rhinolophus ferrumequinum) in China (northeast, central-east, and southwest) have significant geographic variation in resting frequencies (RF) of echolocation calls. Because their cochleae have an acoustic fovea that is highly sensitive to a narrow range of frequencies, we reported the transcriptomes of cochleae collected from three genetic lineages of R. ferrumequinum, which is an ideal organism for studying geographic variation in echolocation signals, and tried to understand the mechanisms behind this bat phenomenon by analyzing gene expression and sequence variation.

RESULTS

A total of 8190 differentially expressed genes (DEGs) were identified. We identified five modules from all DEGs that were significantly related to RF or forearm length (FL). DEGs in the RF-related modules were significantly enriched in the gene categories involved in neural activity, learning, and response to sound. DEGs in the FL-related modules were significantly enriched in the pathways related to muscle and actin functions. Using 21,945 single nucleotide polymorphisms, we identified 18 candidate unigenes associated with hearing, five of which were differentially expressed among the three populations. Additionally, the gene ERBB4, which regulates diverse cellular processes in the inner ear such as cell proliferation and differentiation, was in the largest module. We also found 49 unigenes that were under positive selection from 4105 one-to-one orthologous gene pairs between the three R. ferrumequinum lineages and three other Chiroptera species.

CONCLUSIONS

The variability of gene expression and sequence divergence at the molecular level might provide evidence that can help elucidate the genetic basis of geographic variation in echolocation signals of greater horseshoe bats.

Ocular Surface Membrane-Associated Mucins

Ocular surface epithelial cells produce and secrete mucins that form a hydrophilic barrier for protection and lubrication of the eye. This barrier, the glycocalyx, is formed by high molecular weight heavily glycosylated membrane-associated mucins (MAMs) that include MUC1, MUC4, and MUC16. These mucins extend into the tear film from the anterior surfaces of the conjunctiva and cornea, and, through interactions with galectin-3, prevent penetrance of pathogens into the eye. Due primarily to the glycosylation of the mucins, the glycocalyx also creates less friction during blinking and enables the tear film to maintain wetting of the eye. The secretory mucins include soluble MUC7 and gel-forming MUC5AC. These mucins, particularly MUC5AC, assist with removal of debris from the tear film and contribute to the hydrophilicity of the tear film. While new methodologies and cell culture models have expanded our understanding of mucin structure and function on the ocular surface, there is still a paucity of studies characterizing the glycosylation of MAMs on a normal ocular surface and a diseased ocular surface. Although studies have shown alterations in mucin production and expression in dry eye diseases, the relationship between changes in mucins and functional consequences is unclear. This review focuses on comparing what is known about MAMs in wet-surfaced epithelia of the body to what has been studied on the eye.

1,8-Cineol Reduces Mucus-Production in a Novel Human Ex Vivo Model of Late Rhinosinusitis

Inflammatory diseases of the respiratory system such as rhinosinusitis, chronic obstructive pulmonary disease, or bronchial asthma are strongly associated with overproduction and hypersecretion of mucus lining the epithelial airway surface. 1,8-cineol, the active ingredient of the pharmaceutical drug Soledum, is commonly applied for treating such inflammatory airway diseases. However, its potential effects on mucus overproduction still remain unclear.In the present study, we successfully established ex vivo cultures of human nasal turbinate slices to investigate the effects of 1,8-cineol on mucus hypersecretion in experimentally induced rhinosinusitis. The presence of acetyl-α-tubulin-positive cilia confirmed the integrity of the ex vivo cultured epithelium. Mucin-filled goblet cells were also detectable in nasal slice cultures, as revealed by Alcian Blue and Periodic acid-Schiff stainings. Treatment of nasal slice cultures with lipopolysaccharides mimicking bacterial infection as observed during late rhinosinusitis led to a significantly increased number of mucin-filled goblet cells. Notably, the number of mucin-filled goblet cells was found to be significantly decreased after co-treatment with 1,8-cineol. On a molecular level, real time PCR-analysis further showed 1,8-cineol to significantly reduce the expression levels of the mucin genes MUC2 and MUC19 in close association with significantly attenuated NF-κB-activity. In conclusion, we demonstrate for the first time a 1,8-cineol-dependent reduction of mucin-filled goblet cells and MUC2-gene expression associated with an attenuated NF-κB-activity in human nasal slice cultures. Our findings suggest that these effects partially account for the clinical benefits of 1,8-cineol-based therapy during rhinosinusitis. Therefore, topical application of 1,8-cineol may offer a novel therapeutic approach to reduce bacteria-induced mucus hypersecretion.

Emerging potential of natural products for targeting mucins for therapy against inflammation and cancer

Deregulated mucin expression is a hallmark of several inflammatory and malignant pathologies. Emerging evidence suggests that, apart from biomarkers, these deregulated mucins are functional contributors to the pathogenesis in inflammation and cancer. Both overexpression and downregulation of mucins in various organ systems is associated with pathobiology of inflammation and cancer. Restoration of mucin homeostasis has become an important goal for therapy and management of such disorders has fueled the quest for selective mucomodulators. With improved understanding of mucin regulation and mechanistic insights into their pathobiological roles, there is optimism to find selective non-toxic agents capable of modulating mucin expression and function. Recently, natural compounds derived from dietary sources have drawn attention due to their anti-inflammatory and anti-oxidant properties and low toxicity. Considerable efforts have been directed towards evaluating dietary natural products as chemopreventive and therapeutic agents; identification, characterization and synthesis of their active compounds; and improving their delivery and bioavailability. We describe the current understanding of mucin regulation, rationale for targeting mucins with natural products and discuss some natural products that modulate mucin expression and functions. We further discuss the approaches and parameters that should guide future research to identify and evaluate selective natural mucomodulators for therapy.

Sensory rewiring in an echolocator: genome-wide modification of retinogenic and auditory genes in the bat Myotis davidii

Bats comprise 20% of all mammalian species and display a number of characteristics, including true flight, echolocation, and a heightened ability to resist viral load that uniquely position this group for comparative genomic studies. Here we searched for evidence of genomic variation consistent with sensory rewiring through bat evolution. We focused on two species with divergent sensory preferences. Myotis davidii is a bat species that echolocates and possesses dim- but not daylight-adapted vision whereas the black flying fox (Pteropus alecto) has highly developed day vision but does not echolocate. Using the naked mole rat as a reference, we found five functional genes (CYP1A2, RBP3, GUCY2F, CRYBB1, and GRK7) encoding visual proteins that have degenerated into pseudogenes in M. davidii but not P. alecto. In a second approach genome-wide codon usage bias (CUB) was compared between the two bat species. This CUB ranking systematically enriched for vision-related (CLN8, RD3, IKZF1, LAMC3, CRX, SOX8, VAX2, HPS1, RHO, PRPH2, and SOX9) and hearing-related (TPRN, TMIE, SLC52A3, OTOF, WFS1, SOD1, TBX18, MAP1A, OTOS, GPX1, and USH1G) machinery in M. davidii but not P. alecto. All vision and hearing genes selectively enriched in M. davidii for which orthologs could be identified also were more biased in the echolocating M. lucifugus than the nonecholocating P. vampyrus. We suggest that the existence of codon bias in vision- and hearing-related genes in a species that has evolved echolocation implies CUB is part of evolution’s toolkit to rewire sensory systems. We propose that the two genetic changes (pseudogene formation and CUB) collectively paint a picture of that incorporates a combination of destruction and gain-of-function. Together, they help explain how natural selection has reduced physiological costs associated with the development of a smaller eye poorly adapted to day vision but that also contribute to enhanced dim light vision and the hearing adaptations consonant with echolocation.

Differential response of gel-forming mucins to pathogenic middle ear bacteria

OBJECTIVE

To assess the differential response of the secretory gel forming mucins (GFM) to the most common bacterial pathogens causing otitis media, Streptococcus pneumoniae (SP), nontypeable Haemophilus influenza (NTHi), and Moraxella catarrhalis (Mcat), in a culture model of human middle ear epithelium (HMEEC).

METHODS

In vitro cultured HMEEC was exposed to 5 μg/ml of bacterial whole cell lysate (WCL). RNA was extracted to generate cDNA. The expression levels of each of the targeted mucin transcripts, MUC2, MUC5AC, MUC5B and MUC19, were detected by quantitative PCR.

RESULTS

The submerged HMEEC exposed to NTHi-86028NP WCL demonstrated a significant increase of MUC2, MUC5AC and MUC5B as compared to the control non-treated cells while MUC19 transcript level remained unchanged. WCL of additional major OM pathogens significantly increase the transcription of these three mucin genes as well. A combination of NTHi and SP further synergistically induced MUC2 and MUC5AC gene expression however, not all NTHi strains synergized with SP in the induction. Addition of Mcat WCL to the synergized combination of NTHi and SP did not participate in the synergistic response of mucins.

CONCLUSION

The specific pathogen combinations were important in determining the degree of synergistic effects to GFM expression. The current data are substantive in guiding future work to extend our understanding of OM pathogens and GFMs.

The inflammasome adaptor ASC contributes to multiple innate immune processes in the resolution of otitis media

This study was designed to understand the contribution of the inflammasome and IL-1β activation in otitis media (OM). We examined the middle ear (ME) response to non-typeable Haemophilus influenzae (NTHi) in wild type (WT) mice using gene microarrays and a murine model of acute OM. Expression of members of the NOD domain-like receptor family of inflammasome genes was significantly up-regulated early in NTHi infection of the ME, potentially activating specific downstream regulatory cascades that contribute to the proliferative inflammatory response observed during OM. Expression of the pro-forms of the inflammasome targets IL-1β and IL-18 were also up-regulated. To evaluate the role of inflammasome-mediated cytokine maturation, NTHi-induced OM was examined in Asc(-/-)-deficient mice and compared with that seen in WT mice. Mice lacking the Asc gene showed near absence of IL-1β maturation in the ME and a reduction in leukocyte recruitment and infiltration to the cavity, and their macrophages exhibited reduced phagocytosis of NTHi. These inflammatory defects were linked to an increase in the degree and duration of mucosal epithelial hyperplasia in the ME of Asc(-/-) mice, as well as a delay in bacterial clearance from their MEs. These data demonstrate an important role for the inflammasome and cytokine processing in the course and resolution of OM.

Panel 4: Recent advances in otitis media in molecular biology, biochemistry, genetics, and animal models

BACKGROUND

Otitis media (OM) is the most common childhood bacterial infection and also the leading cause of conductive hearing loss in children. Currently, there is an urgent need for developing novel therapeutic agents for treating OM based on full understanding of molecular pathogenesis in the areas of molecular biology, biochemistry, genetics, and animal model studies in OM.

OBJECTIVE

To provide a state-of-the-art review concerning recent advances in OM in the areas of molecular biology, biochemistry, genetics, and animal model studies and to discuss the future directions of OM studies in these areas.

DATA SOURCES AND REVIEW METHODS

A structured search of the current literature (since June 2007). The authors searched PubMed for published literature in the areas of molecular biology, biochemistry, genetics, and animal model studies in OM.

RESULTS

Over the past 4 years, significant progress has been made in the areas of molecular biology, biochemistry, genetics, and animal model studies in OM. These studies brought new insights into our understanding of the molecular and biochemical mechanisms underlying the molecular pathogenesis of OM and helped identify novel therapeutic targets for OM.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Our understanding of the molecular pathogenesis of OM has been significantly advanced, particularly in the areas of inflammation, innate immunity, mucus overproduction, mucosal hyperplasia, middle ear and inner ear interaction, genetics, genome sequencing, and animal model studies. Although these studies are still in their experimental stages, they help identify new potential therapeutic targets. Future preclinical and clinical studies will help to translate these exciting experimental research findings into clinical applications.

Tissue distibution of murine Muc19/smgc gene products

The recently identified gene Muc19/Smgc encodes two diverse splice variants, Smgc (submandibular gland protein C) and Muc19 (mucin 19). Muc19 is a member of the large gel-forming mucin family and is an exocrine product of sublingual mucous salivary glands in mice. SMGC is a transiently expressed secretion product of developing rodent submandibular and sublingual glands. Little is known about the expression of Muc19/Smgc gene products in other murine salivary and non-salivary tissues containing the mucous cell phenotype. Muc19 expression was therefore initially assessed by RT-PCR and immunohistochemistry. As a complementary approach, we developed a knockin mouse model, Muc19-EGFP, in which mice express a fusion protein containing the first 69 residues of Muc19 followed by enhanced green fluorescent protein (EGFP) as a marker of Muc19 expression. Results from both approaches are consistent, with preferential Muc19 expression in salivary major and minor mucous glands as well as submucosal glands of the tracheolarynx and bulbourethral glands. Evidence also indicates that individual mucous cells of minor salivary and bulbourethral glands produce another gel-forming mucin in addition to Muc19. We further find tissue expression of full-length Smgc transcripts, which encode for SMGC, and are restricted to neonatal tracheolarynx and all salivary tissues.

A novel model of spontaneous otitis media with effusion (OME) in the Oxgr1 knock-out mouse

OBJECTIVE

A novel mouse model with a specific genetic mutation in a G protein coupled receptor (GPCR) encoded by the Oxgr1 gene results in a predisposition to spontaneous otitis media with effusion. As a primary component of interest in OME, mucin expression was examined in this model to assess expression as compared to wild type animals and suitability as a murine model of OME.

METHOD

Mutant (Oxgr1(-/-)) and wild-type (Oxgr1(+/+)) mice between ages of 2 and 5 months were examined by otoscopy and auditory brainstem response (ABR). Histology changes in the middle ear were evaluated. Expression of mucin genes in the middle ear epithelium was determined using RT-PCR and quantitative PCR.

RESULT

Otoscopic exam showed signs of inflammation in 82% of mutant mice. Significant elevated ABR thresholds were detected in mutant mice indicating hearing loss. Histology analysis of the middle ears demonstrated the presence of inflammatory cells, changes in the mucosal epithelium, and middle ear fluid. RT PCR using universal primers for bacterial 18s rRNA suggested the absence of bacteria in the middle ear. The knockout mice demonstrated expression of Muc1, Muc2, Muc3, Muc4, Muc5AC, Muc5B, Muc9, Muc10, Muc13, Muc15, Muc16, Muc18, Muc19 and Muc20. There was a trend of increase in Muc5B and Muc19 expression in the middle ear of the knockout mice compared to that of wild-type. There was no significant change in the level of Muc2, and Muc5AC was expressed at a level below the detection limit of quantification.

CONCLUSION

Development of a murine model with genetic defect has several attractive features. The rate of OME in these animals is high at 82%. It is clear that this OME is related to histopathologic changes in the middle ear epithelium of these knock-out mice. Induction of mucus effusion is evident though the viation in dysregulation of GFM does exist in this non-challenge study condition. The underlying cause of these differences between individual animal requires further investigation. Given this, the Oxgr1(-/-) model is likely to be an ideal model to examine mucin regulation in MEE and potentially develop novel GPCR-specific targeted interventions to regulate these processes.

Cryopyrin-associated periodic syndromes: otolaryngologic and audiologic manifestations

OBJECTIVE

Cryopyrin-associated periodic syndromes (CAPS) represent a spectrum of CIAS1 gene-mediated autoinflammatory diseases characterized by recurrent systemic inflammation. The clinical spectrum of CAPS varies from mild to severe and includes the syndromes historically described as familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS), and neonatal-onset multisystem inflammatory disease (NOMID). This article presents the largest cohort of patients with CAPS. The objective is to describe the pathogenesis, otolaryngologic, and audiologic manifestations of CAPS.

STUDY DESIGN

Prospective (2003-2009).

SETTING

National Institutes of Health.

SUBJECTS AND METHODS

Fifty-seven patients with a diagnosis of CAPS were identified (31 NOMID, 11 NOMID/MWS, 9 MWS, and 6 FCAS). Comprehensive data regarding clinical manifestations, audiologic phenotype, and fluid attenuation inversion recovery MRI (FLAIR-MRI) of the brain and inner ear were obtained.

RESULTS

Complete audiologic data obtained on 70% of ears revealed conductive hearing loss in 4 (11%) NOMID ears and mixed hearing loss in 5 (13%) NOMID and 2 (14%) NOMID/MWS ears. Sensorineural hearing loss (SNHL), worse in higher frequencies, was the most common type of hearing loss and was present in 23 (61%) NOMID, 10 (71%) NOMID/MWS, and 4 (33%) MWS ears. All of the patients with FCAS had normal hearing except 2, who had SNHL from 4 to 8 kHz. On FLAIR-MRI sequence, cochlear enhancement was noted in 26 of 29 (90%) NOMID, 6 of 11 (55%) NOMID/MWS, 3 of 9 (33%) MWS, and 1 of 6 (17%) FCAS patients and was significantly associated with the presence of hearing loss. Maxillary sinus hypoplasia and mucosal thickening were found in 39% and 86% of the cohort, respectively.

CONCLUSION

CIAS1 pathway–mediated CAPS is associated with unregulated autoinflammation mediated by interleukin-1 in the cochlea and hearing loss. Timely diagnosis is crucial to initiate early treatment with interleukin-1 receptor antagonists.

Otitis Media

During most of recorded history, the application of knowledge to the care of individual patients was founded on the experience of individual medical practitioners; when published, it basically took the form of case reports. Not until the middle of the 20th Century did randomized controlled trials (RCTs) come to be the gold standard. By the beginning of the 21st Century, however, the limitations of RCTs and their syntheses, the meta-analyses, have come to be recognized, and their applicability to the individual patient questioned and, indeed, challenged. The intense increase in our knowledge base and in accompanying technology has made possible the personalization of medicine beyond the possibilities of earlier periods. The approach of personalized medicine requires evaluation of four parameters: the individual patient’s intrinsic susceptibility, intrinsic morbidity, extrinsic susceptibility, and extrinsic morbidity. The characteristics of the disease agent—how much (duration) and how virulent—also must be factored in. These individualized data define the appropriate intervention: high susceptibility and/or morbidity or low susceptibility and/or morbidity and the aggregate of the intrinsic and extrinsic risk factors are cofactored in medical decision making.

Otitis media and associations with overweight status in toddlers

INTRODUCTION

Otitis media (OM) is a significant disease that affects nearly all children early in life. Recently, childhood overweight has become an epidemic. Past research has demonstrated that a history of OM is related to food preferences and overweight through proposed physiological mechanisms. The purpose of this study was to explore the relationship between recurrent OM (ROM)/tympanostomy tube treatment and overweight status.

METHODS

Data were analyzed from a prospective cohort of mothers and children recruited from 1991-1996 from a local health maintenance organization. ROM and tympanostomy tube status were obtained through a combination of physical exam and medical record abstraction. ROM and tympanostomy tube status were analyzed as categorical variables with weight-for-length (WFL) data from well child checks. Chi-square and logistic regression for univariate and multivariate analyses were performed.

RESULTS

11.4% of children had a WFL measure at two years of age ≥ 95 th percentile. Those children with a history of tympanostomy tube treatment had a significantly increased risk of having a WFL ≥ 95 th percentile after controlling for birth weight, maternal prenatal smoking, maternal education, and family income (OR 3.32, 95% CI 1.43-7.72). The alternative hypothesis that children with larger WFL at two month of age would have a greater number of OM episodes by two years of age was not significant.

CONCLUSION

The findings of this study are consistent with the hypothesis and prior research that OM treated with tympanostomy tubes is associated with overweight status.

Cloning and characterization of human MUC19 gene

The most recently discovered gel-forming mucin, MUC19, is expressed in both salivary glands and tracheal submucosal glands. We previously cloned the 3'-end partial sequence (AY236870), and here report the complete sequencing of the entire MUC19 cDNA. One highly variable region (HVR) was discovered in the 5' end of MUC19. A total of 20 different splicing variants were detected in HVR, and 18 variants are able to translate into proteins along with the rest of the MUC19 sequence. The longest variant of MUC19 consists of 182 exons, with a transcript of approximately 25 kb. A central exon of approximately 12 kb contains highly repetitive sequences and has no intron interruption. The deduced MUC19 protein has the bona fide gel-forming mucin structure, VWD-VWD-VWD-"threonine/serine-rich repeats"-VWC-CT. An unusual structural feature of MUC19, which is lacking in other gel-forming mucins, is its long amino terminus upstream of the first VWD domain. The long amino terminus is mostly translated from the sequences in HVR, and contains serine-rich repetitive sequences. To validate the integrity of the MUC19 sequence, primers from both the 3' and 5' end were used to demonstrate a similar tissue expression pattern of MUC19 in trachea and salivary glands. In addition, antibodies were developed against either the amino (N) or carboxy (C) terminus of MUC19, and similar antibody staining patterns were observed in both salivary and tracheal submucosal glands. In conclusion, we have cloned and elucidated the entire MUC19 gene, which will facilitate understanding of the function and regulation of this important, yet understudied, mucin gene in airway diseases.

Mucin gene expression and mouse middle ear epithelium

OBJECTIVES

To investigate the expression of recently identified human mucin genes in an in vitro model of cultured mouse middle ear epithelial cells (MMEEC).

METHODS

MMEEC were established, RNA was extracted and primers were designed for RT-PCR to assess for expression of mucin genes Muc1, Muc2, Muc3, Muc4, Muc5AC, Muc5B, Muc6, Muc7, Muc8, Muc9, Muc10, Muc11/12, Muc13, Muc15, Muc16, Muc17, Muc18, Muc19 and Muc20 expression.

RESULTS

Mucin genes Muc1, Muc2, Muc3, Muc4, Muc5AC, Muc5B, Muc9, Muc10, Muc13, Muc15, Muc16, Muc18, Muc19 and Muc20 were identified and expressed in MMEEC. The genes Muc6, Muc7, Muc8, Muc11/12 and Muc17 were not identified.

CONCLUSION

Many of the mucin genes that have been recently identified in human MEE and chinchilla MEE are also expressed in MMEEC. There are differences in expression, however, which may have implications in utilizing various animal models for study of middle ear physiology and pathogenesis; specifically as it relates to mucin gene expression.

Current status of mucins in the diagnosis and therapy of cancer

Mucins are the most abundant high molecular weight glycoproteins in mucus. Their nature and glycosylation content dictates the biochemical and biophysical properties of viscoelastic secretions, pointing out an important role in diverse biological functions, such as differentiation, cell adhesions, immune responses, and cell signaling. Mucins are expressed in tubular organs by specialized epithelial cells in the body. Their aberrant expression is well documented in a variety of inflammatory or malignant diseases. From a prognosis point of view, their expression and alterations in glycosylation are associated with the development and progression of malignant diseases. Therefore, mucins can be used as valuable markers to distinguish between normal and disease conditions. Indeed, this alteration in glycosylation patterns generates several epitopes in the oligosaccharide side chains that can be used as diagnostic and/or prognostic markers. Furthermore, these characteristic tumor-associated epitopes are extensively used as appropriate immunotargets of malignant epithelial cells. Therefore, in an effort to detect and treat cancer at the earliest stage possible, mucins are analyzed as potential markers of disease for diagnosis, progression, and for therapeutic purposes. In this review, we focused on the current status of the distribution of mucins in normal and pathologic conditions and their clinical use both in cancer diagnosis and therapeutics treatments.