Biomedical subjects

Jeffrey P Pearson

Publications and source records attributed to Jeffrey P Pearson.

16 recordsLinked to original sources

PubMed2005

Major secretory mucin expression in chronic sinusitis.

OBJECTIVE: The aim of this study was to investigate mucin expression in chronic sinusitis compared to that in normal nasal mucus. STUDY DESIGN AND SETTING: Sinus mucus samples were collected during functional endoscopic sinus surgery (FESS). The expression of 3 airway mucins, MUC2, MUC5AC, and MUC5B, was determined by ELISA. RESULTS: The 3 mucins are expressed in chronic sinusitis and in normal nasal mucus. MUC5AC and MUC5B represent a major component in sinus mucins while MUC5B and MUC2 predominated in normal nasal mucin. In sinus mucins, upregulation of MUC5AC was associated with downregulation of MUC2 and vice versa. This inverse relationship was strengthened in the presence of nasal polyps. CONCLUSION: At least 3 mucins are expressed at various levels in chronic sinusitis. An inverse relationship was identified between expression of MUC5AC and MUC2. Large prospective studies are required to unravel the complexities of sinus mucus in chronic sinusitis. SIGNIFICANCE: Mucins may be used as markers for assessment of disease severity and may also help as prognostic indicators following medical or surgical treatment.

Adolescent↗

PubMed2005

Mucin gene expression in nasal polyps.

CONCLUSIONS: A large set of mucin genes is expressed in nasal polyps. The expression pattern is complex and may reflect the wide spectrum of variables involved in polyp formation and progression. Prospective studies including subgroups of nasal polyps and involving substantial numbers of cases in each subgroup will be required to elucidate these variables and to understand how they affect mucus secretion. OBJECTIVE: At present, 15 of the 19 known mucin genes are expressed in the human airways. Nasal polyps might be expected to have a mucin expression pattern comparable to that of the airways. The aim of this study was to investigate mucin expression in nasal polyps. MATERIAL AND METHODS: Nasal polyp samples were obtained from 20 patients during functional endoscopic sinus surgery. Normal (control) sphenoid sinus mucosa was obtained from patients undergoing trans-sphenoid hypophysectomy. The expression of eight mucin genes (MUC1-4, -5AC, -5B, -6 and -7) was studied by in situ hybridization utilizing digoxigenin-labelled oligonucleotide probes. RESULTS: MUC6 and -7 were not expressed in sphenoid sinus mucosa, while all the studied mucin genes were expressed in nasal polyps. Expression patterns varied widely between individual polyps. The predominant epithelial mucin genes were MUC4, -5AC and -3, while MUC5B and -7 were mainly of glandular origin. MUC1, -2 and -6 were weakly expressed. The major alteration in gene expression in nasal polyps was found in the submucosal glands. MUC4 and -5AC represent a major component of both submucosal glands and epithelial cells in nasal polyps.

Biomarkers, Tumor↗

PubMed2005

Evidence of T-helper cell 2 cytokine regulation of chronic otitis media with effusion.

Cytokine and cellular patterns of effusions may reflect stages of middle ear inflammation. The local interplay between IL-2 and -4 is likely to play a crucial role in the switching of inflammation in the chronic stage. The T-helper cell 2 (Th2) cytokines IL-4, -5 and -13 and the Th2/Th1 cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) regulate the cellular and molecular processes of chronic inflammation in the middle ear and therefore the chronic condition of otitis media with effusion (OME). Early identification of the cytokine and cellular patterns of effusions can be helpful in directing the clinical treatment of OME.We hypothesized that IL-2 and the group of Th2 cytokines regulate chronic inflammation in the middle ear and chronic OME. Effusions from children with persistent OME were analysed to determine the presence of cytokines (the Th1 cytokine IL-2, the Th2 cytokines IL-4, -5 and -13 and the Th1/Th2 cytokine GM-CSF), inflammatory cells (CD4+ T cells, eosinophils, macrophages and neutrophils) and mucin. Cytokines were evaluated by means of a quantitative "sandwich"-type ELISA, inflammatory cells by means of alkaline phosphatase-anti-alkaline phosphatase immunocytostaining and mucin by means of a modified periodic acid-Schiff method based on a slot-blot technique. The cytokine pattern in effusions varied from patient to patient. GM-CSF correlated positively and IL-4 inversely with IL-2 and the increased level of IL-4 may have had an inhibitory effect on IL-2. IL-5 and -13 correlated with IL-4. Inflammatory cells correlated with cytokines as follows: CD4+ T cells with IL-2 and -4; macrophages and neutrophils with GM-CSF; and eosinophils with IL-5. Some cytokine-cellular correlations in effusions were reflected at the clinical level. The mucin content of effusions correlated with the concentrations of IL-4 (>10 pg/ml) and -13, suggesting involvement of IL-4 and -13 in upregulation of the middle ear mucin metabolism.

CD4-Positive T-Lymphocytes↗

PubMed2004

Two rheologically different gastric mucus secretions with different putative functions.

Previous work has shown the presence of different mucin gene products and glycosylated species in gastric mucus secretions, however, the functional relevance of these differences is unclear. This study aimed to investigate rheologically, differences in the gel behaviour within gastric mucus samples using a pig model. Rheological measurements were made on a Bohlin CVO50 rheometer. Mucins were characterised by antigenicity, lectin reactivity and proteolytic fragmentation patterns. Two distinct mucus gel secretions, one compliant with and the other resistant to shear stress, were removed from the gastric mucosa. The two gels had different rheological behaviour profiles and exhibited structural differences in their constituent mucins. The shear-compliant mucus was located superficially to the adherent shear-resistant mucus layer and was shown not to be a proteolytic product of the latter. This study has demonstrated that there are two rheologically distinct mucus gel secretions with structural/compositional differences in the stomach. Rheological properties suggest that the adherent, shear-resistant gel could provide the mucus barrier in vivo while the shear-compliant gel could act primarily as a lubricant.

Animals↗

PubMed2004

The immunoregulatory and allergy-associated cytokines in the aetiology of the otitis media with effusion.

Inflammation in the middle ear mucosa, which can be provoked by different primary factors such as bacterial and viral infection, local allergic reactions and reflux, is the crucial event in the pathogenesis of otitis media with effusion (OME). Unresolved acute inflammatory responses or defective immunoregulation of middle inflammation can promote chronic inflammatory processes and stimulate the chronic condition of OME. Cytokines are the central molecular regulators of middle ear inflammation and can switch the acute phase of inflammation in the chronic stage and induce molecular-pathological processes leading to the histopathological changes accompanying OME. In this review we present cytokines identified in otitis media, immunoregulatory [interleukin (IL)-2, IL-10, transforming growth factor-beta]) and allergy associated (IL-4, IL-5, granulocyte-macrophage colony-stimulating factor), as crucial molecular regulators, responsible for chronic inflammation in the middle ear and the chronic condition of OME.

Chronic Disease↗

PubMed2003

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.

Cell Line↗

PubMed2003

Colonic mucin: methods of measuring mucus thickness.

Mucus is a water-insoluble gel secreted by the gastrointestinal tract. It exists as a protective gel layer adherent to the epithelial surface of the stomach, small intestine and colon. The mucus gel is composed of 1-10 % (w/v) mucin glycoprotein in a plasma-like fluid. Since the mucus gel is predominantly water, standard histological techniques dehydrate the mucus, making visualisation of the functional barrier difficult. Specialist techniques have been developed to enable visualisation of the intact mucus layer. A simple histological method using snap-frozen tissue, sectioned with a cryostat and stained with modified periodic acid-Schiffs/Alcian blue in mucus-preserving conditions will be described. A second powerful in vivo animal model is described which enables measurement of mucus secretion over time. The use of these two methods has allowed the characterisation of the normal mucus layer in the colon and the determination of how it is affected by disease and dietary intervention, in particular the effect of dietary fibre, and evidence that fibre deficiency results in colonic mucosal fragility is presented.

Animals↗

PubMed2003

Colonic mucus: secretion and turnover in relation to dietary fibre intake.

The colon is subjected to a myriad of potentially damaging agents that may reside within the lumen for 1-2 d. Its first line of defence against these agents is the protective mucus bilayer that lines the entire colonic mucosa. This bilayer acts as a physical barrier to mucosal aggressors and also reduces shear stress to the mucosa. These actions are dependent on the unstimulated ('resting') colonic mucus thickness, and also on the rate that this layer can be replenished. The colonic mucus layer is altered in a number of colonic diseases that have been linked to a deficiency of fibre in the diet. The action of fibre intake on colonic mucus thickness and secretion is unknown. Using an in vivo rat model it has been demonstrated that: (1). fibre deficiency leads to a decreased protective potential of the mucus layer (e.g. the mean resting mucus thickness of the fibre-deficient group (429 microm) was significantly lower than its respective control (579 microm; P< 0-001), as was its total mucus secretion over 6 h (270 microm v. 541 microm; P<0-01); (2). specific fibre types in the diet alter the secretion dynamics of colonic mucus (e.g. a cellulose-based diet reduces total mucus secretion over 6 h compared with its control (175 microm v. 463 microm). Analysis of the diets suggested a necessity for both soluble and insoluble fibre types in the diet to increase mucosal protection.

Animals↗

PubMed2003

Cell biology of laryngeal epithelial defenses in health and disease: further studies.

This is the second annual report of an international collaborative research group that is examining the cellular impact of laryngopharyngeal reflux (LPR) on laryngeal epithelium. The results of clinical and experimental studies are presented. Carbonic anhydrase (CA), E-cadherin, and MUC gene expression were analyzed in patients with LPR, in controls, and in an in vitro model. In patients with LPR, we found decreased levels of CAIII in vocal fold epithelium and increased levels in posterior commissure epithelium. The experimental studies confirm that laryngeal CAIII is depleted in response to reflux. Also, cell damage does occur well above pH 4.0. In addition, E-cadherin (transmembrane cell surface molecules, which have a key function in epithelial cell adhesion) was not present in 37% of the LPR laryngeal specimens. In conclusion, the laryngeal epithelium lacks defenses comparable to those in esophageal epithelium, and these differences may contribute to the increased susceptibility of laryngeal epithelium to reflux-related injury.

Acid-Base Equilibrium↗

PubMed2002

In vitro study of IL-8 and goblet cells: possible role of IL-8 in the aetiology of otitis media with effusion.

One of the main characteristics of otitis media with effusion (OME) is the differentiation of basal cells into goblet cells with subsequent proliferation in a modified respiratory epithelium leading to the formation of mucin-rich effusion in the middle ear cleft. In order to determine the effect of pro-inflammatory cytokines identified in OME, e.g. IL-1beta, tumour necrosis factor (TNF)-alpha, IL-6 and IL-8, on goblet cells, and to clarify the role of IL-8 in particular, we used the human goblet cell line HT29-MTX, which secretes two OME-related mucins: MUC5AC and MUC5B. IL-1beta and TNF-alpha stimulated the secretion of IL-8 in HT29-MTX goblet cells. Dose- (2-200 ng/ml) and time- (0-5 days) response studies of IL-8-induced mucin secretion were carried out. IL-8 upregulated the secretion of MUC5AC and MUC5B mucins in a concentration-dependent manner, with a maximum response at an IL-8 concentration of 20 ng/ml. IL-8 (20 ng/ml)-mediated mucin secretion persisted for up to 5 days, with a peak response 72 h after the addition of cytokine. These results suggest that: (i) goblet cells are target cells for the pro-inflammatory cytokines IL-1beta, TNF-alpha and IL-8 and can contribute to the pathogenesis of OME by increasing both the concentration of IL-8 and the secretion of mucin; and (ii) IL-8 stimulates prolonged mucin secretion from goblet cells and may be involved in the maintenance of the disease in the chronic stage.

Cell Differentiation↗

PubMed2002

Mixed nasal mucus as a model for sinus mucin gene expression studies.

OBJECTIVE/HYPOTHESIS: It is necessary to obtain sinus mucus from the paranasal sinus cavities to study mucin gene expression occurring in the sinuses during chronic sinusitis. This requires an invasive procedure to access the sinus cavity. There are embryological as well as histological similarities between nasal and sinus epithelia; therefore, we postulated that the mucin expression in the secreted nasal and sinus mucins might be similar. Nasal mucus, which can be obtained easily, could then replace sinus mucus in these studies. STUDY DESIGN: Sinus and nasal mucus from six patients with chronic sinusitis were analyzed in this study. METHODS: High-molecular-weight glycoproteins (mucins) were isolated and purified by sequential density gradient centrifugation in caesium chloride (CsCl). Enzyme-linked immunosorbent assay was performed to identify the antigenic identity of these mucins. RESULTS: The MUC2, MUC5AC, and MUC5B mucin genes were all expressed in the nasal and sinus mucus secretions. Antigenic studies showed an inverse relationship between MUC2 and MUC5AC expression in nasal and sinus mucus secretions. The MUC5B gene was the major mucin gene expressed in sinus mucus but not in nasal mucus. Expression of MUC2 was significantly higher in sinus mucus. Expression of MUC5AC was different between nasal and sinus mucus. CONCLUSIONS: Individual mucin expression in sinus and nasal mucus was markedly different. From this preliminary study, we conclude that nasal mucus is not a suitable substitute for sinus mucus in sinus mucin gene studies and that different pathological processes are taking place in nasal and sinus tissue in chronic sinusitis.

Chronic Disease↗

PubMed2002

Is gastric reflux a cause of otitis media with effusion in children?

OBJECTIVES/HYPOTHESIS: Otitis media with effusion is the most common cause of childhood deafness. Gastroesophageal reflux has been implicated in the disease pathogenesis; therefore, it is necessary to identify the presence or absence of gastric juice in the middle ear. STUDY DESIGN: Middle ear effusions were collected from children undergoing myringotomy. If gastric reflux has occurred, effusions should contain pepsin protein. METHODS: Total pepsin/pepsinogen protein, fibrinogen, and albumin content of effusions were measured in enzyme-linked immunosorbent assays using antibodies to porcine pepsin, human albumin, and human fibrinogen. Proteolytic activity of each effusion was measured at pH 2. The pH of effusions was measured. RESULTS: Fifty-nine of 65 effusion samples gave a positive result with the antipepsin antibody, which also recognized pepsinogen. Pepsin/pepsinogen levels ranged from 0.8 to 213.9 microg/mL (serum reference levels, 49.8-86.6 ng/mL). All effusions contained albumin and fibrinogen with respective ranges of 1.77 to 95.75 and 0.30 to 2.30 mg/mL (serum reference levels, 35-45 and 2.2 to 4.6 mg/mL, respectively). Acidic protease activity occurred in 19 of 65 effusion samples. The pH of effusion samples was 7 to 9. CONCLUSIONS: The majority of effusion samples contained pepsin/pepsinogen protein; only 29% were active. The pepsin level in effusion samples based on activity is substantially lower than levels based on antibody detection; however, the pH present would irreversibly inhibit pepsin, which would explain the low levels of active enzyme. Pepsin/pepsinogen levels in the effusion samples were up to 1000 times higher than serum levels, whereas albumin and fibrinogen levels were of the same magnitude. The pepsin in middle ear effusions is almost certainly due to reflux of gastric contents, and there may be a role for antireflux therapy in the treatment of otitis media with effusion.

Albumins↗

PubMedDate not supplied

The gel matrix of gastric mucus is maintained by a complex interplay of transient and nontransient associations.

The gel nature of mucus is fundamental to its physiological functions; however, the structure of the mucus gel matrix is unclear. Here, small and large deformation rheology has been used to investigate the physical nature of the gel matrix and the forces that maintain this matrix in pig gastric mucus. The gelation process in mucus has been shown to be comparable with that of other polymer gel systems. Nongelling portions of mucin have been identified within the gel network, and the importance of transient, relaxable interactions to the maintenance of the mucus gel matrix has been demonstrated. The structure of the mucus gel matrix is considered in relation to the functional properties of mucus gels.

Animals↗

PubMedDate not supplied

Mucous systems show a novel mechanical response to applied deformation.

Mucous secretions have a wide range of biological functions that are intimately linked with their rheological properties. In addition, many mucous secretions are exposed to significant stress and deformation during physiological function. This study has examined the rheological response of three mucous systems, native pig gastric mucus, purified mucin gels, and mucin alginate gels, to increasing applied stress to a level sufficient to induce flow behavior. A novel, frequency-dependent stress hardening was observed in all three systems. This hardening behavior may play a significant role in the ability of mucous systems to resist mechanical disruption in the physiological state.

Animals↗

PubMedDate not supplied

MUC5B secretion is up-regulated in sinusitis compared with controls.

BACKGROUND: The mucus that lines the airway epithelium provides a barrier against pathogenic and noxious agents and participates in the innate mucosal response to inflammation and infection. Mucins are the major components of mucus and the macromolecules that impart rheologic properties to airway mucus. Airway mucus is overproduced in chronic rhinosinusitis (CRS). Biochemical and biophysical characterization of mucus in CRS and in normal airways will elucidate important aspects of CRS pathophysiology and allow the design of targeted medical treatments. The aim of this study was to estimate secretion of sinus mucus mucins in healthy individuals and CRS and correlate them with mucus biophysical properties. METHODS: Twenty-seven sinus mucus samples from 21 patients were collected (14 subjects with CRS undergoing sinus surgery as part of their treatment and 7 control subjects undergoing hypophysectomy without sinonasal disease). Biophysical properties of the mucus were measured by rheometry. ELISA was done to estimate MUC5AC and MUC5B mucin content in comparison with standards, i.e., porcine gastric mucin (MUC5AC) and human salivary mucin (MUC5B). RESULTS: MUC5B secretion +/- SEM was 0.49 +/- 0.16 microg/mL (n = 14) and 0.17 +/- 0.05 microg/mL (n = 7) and MUC5AC secretion +/- SEM was 1.26 +/- 0.26 microg/mL (n = 14) and 1.46 +/- 0.61 microg/mL (n = 7) in chronic sinusitis and control subjects, respectively. There was linear correlation between viscosity and mucin content in the control group but not in the CRS group. CONCLUSION: MUC5B secretion is significantly up-regulated in CRS compared with control subjects (p = 0.04). Correlation between viscosity and mucin content was lost in CRS. This is likely to have important implications for future therapies in CRS.

Case-Control Studies↗

PubMedDate not supplied

Role of the pro-inflammatory cytokines tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6 and interleukin-8 in the pathogenesis of the otitis media with effusion.

Inflammation in the middle ear mucosa, caused usually by bacterial and viral pathogens, is the primary event in the middle ear predisposing the development of otitis media with effusion (OME). Numerous inflammatory mediators have been identified in OME. However, cytokines play a central role as initiators, mediators and regulators of middle ear inflammation and subsequent molecular-pathological processes in middle ear tissues, leading to histopathological changes in the middle ear cavity and the pathogenesis of OME. In this article, we aim to present an overview of current research developments in the pro-inflammatory cytokine involvement in the aetiology of otitis media with effusion.

Humans↗