Mucus Secretion Rate Research Articles

Activation of goblet cell Piezo1 alleviates mucus barrier damage in mice exposed to WAS by inhibiting H3K9me3 modification

BackgroundOur recent studies found that intestinal mechanical signals can regulate mucus synthesis and secretion of intestinal goblet cells through piezo type mechanosensitive ion channel component 1 (Piezo1), but the detailed molecular mechanisms remain to be investigated. Previous studies using a water avoidance stress (WAS) model reported decreased intestinal mucus accompanied by abnormal intestinal motility. It has also been reported that the expression of mucin2 was negatively correlated with histone H3 lysine 9 trimethylation (H3K9me3), a key regulator of histone methylation, and that mechanical stimulation can affect methylation. In this study, we aimed to determine whether and how Piezo1 expressed on goblet cells regulates mucus barrier function through methylation modification.MethodsA murine WAS model was established and treated with Yoda1 (Piezo1 agonist), and specific Piezo1 flox-mucin2 Cre mice were also tested. The mucus layer thickness and mucus secretion rate of mouse colonic mucosa were detected by a homemade horizontal Ussing chamber, intestinal peristaltic contraction was detected by the ink propulsion test and organ bath, goblet cells and mucus layer morphology were assessed by HE and Alcian blue staining, mucus permeability was detected by FISH, and the expression levels of Piezo1, H3K9me3 and related molecules were measured by Western blots and immunofluorescence. LS174T cells were cultured on a shaker board in vitro to simulate mechanical stimulation. Piezo1 and H3K9me3 were inhibited, and changes in mucin2 and methylation-related pathways were detected by ELISAs and Western blots. ChIP-PCR assays were used to detect the binding of H3K9me3 and mucin2 promoters under mechanical stimulation.ResultsCompared with those of the controls, the mucus layer thickness and mucus secretion rate of the mice exposed to WAS were significantly decreased, the mucus permeability increased, the number of goblet cells decreased, and the intestinal contraction and peristalsis were also downregulated and disordered. Intraperitoneal injection of Yoda1 improved mucus barrier function and intestinal contraction. In the colonic mucosa of mice exposed to WAS, Piezo1 was decreased, and histone H3 lysine 9 trimethylation (H3K9me3) and methyltransferase suppressor of variegation 3–9 homolog 1 (SUV39h1) were increased, but activating Piezo1 alleviated these effects of WAS. Piezo1 flox-mucin2 Cre mice showed decreased mucus expression and increased methylation compared to wild-type mice. Cell experiments showed that mechanical stimulation induced the activation of Piezo1, decreased H3K9me3 and SUV39h1, and upregulated mucin2 expression. Inhibition of Piezo1 or H3K9me3 blocked the promoting effect of mechanical stimulation on LS174T mucin2 expression. The binding of H3K9me3 to the mucin2 promoter decreased significantly under mechanical stimulation, but this could be blocked by the Piezo1 inhibitor GsMTx4.ConclusionPiezo1 mediates mechanical stimulation to inhibit SUV39h1, thereby reducing H3K9me3 production and its binding to the mucin2 promoter, ultimately promoting mucin2 expression in goblet cells. This study further confirmed that piezo1 on goblet cells could regulate mucus barrier function through methylation.

Prediction of Hazardous Effect of Heavy Metals of Point-Source Wastewater on Fish (Anabas cobojius) and Human Health.

Aquatic ecosystems are exceedingly contrived due to industrial dispenses, as a huge amount of toxicants especially heavy metals are released, causing drastic effects on aquatic lives and the human body. This study was performed to assess the quality of point-source industrial wastewater at varying percentage levels and their subsequent hazardous effect on fish (Anabas cobojius) and human health. The perceived value revealed that water quality parameters declined with the increase of wastewater concentration and trace metal evaluation index (TEI) ascertained a high level of water pollution due to Cr, Mn, Fe, Co, Ni, Cu, Zn, and As content for all percentages of wastewater. Concentration of wastewater and culture treatment duration largely impacted on fish mortality rate, body dis-pigmentation, mucus secretion rate, coagulation of mucus all over the body, and accumulation of heavy metals by fish samples. Metal pollution index (MPI) indicated low contamination of fish by the measured elements. Zn and Hg exceeded the threshold limit of target hazard quotient (THQ > 1) and contributed significantly to non-carcinogenic health implications for both the population group. Maximum hazard index in adults and children was observed to be 10.638 and 16.548 for 100% effluent at 96-h exposure period and the overall HI value manifested a very high to medium significant health effects regardless of age. Carcinogen Pb showed insignificant risk but Cr and Ni showed extremely high to medium-high risk for both the population group, and children were found more vulnerable receptors than adults. However, source of heavy metals in wastewater and fish samples stipulated anthropogenic sources.

Effect of continuous positive airway pressure treatment on permeability, inflammation and mucus production of human epithelial cells.

Continuous positive airway pressure (CPAP) therapy is the gold standard treatment for obstructive sleep apnoea, which affects millions of people worldwide. However, this therapy normally results in symptoms such as dryness, sneezing, rhinorrhoea, post-nasal drip, nasal congestion and epistaxis in the upper airways.Using bronchial epithelial (Calu-3) and nasal epithelial (RPMI 2650) cells in an in vitro respiratory model, this study, for the first time, investigates the effect of CPAP positive pressure on the human respiratory epithelial mechanisms that regulate upper airways lubrication characteristics. To understand how the epithelium and mucus are affected by this therapy, several parameters were determined before and after positive pressure application.This work demonstrates that the positive pressure not only compresses the cells, but also reduces their permeability and mucus secretion rate, thus drying the airway surface liquid layer and altering the mucus/water ratio. It is also observed that the respiratory epithelia is equally inflamed without or with external humidification during CPAP application.These findings clearly identify the causes of the side-effects reported by patients under CPAP therapy.

Interleukin‐8 stimulates CFTR‐mediated mucus secretion by submucosal glands in swine (869.10)

Cystic Fibrosis (CF) is an autosomal recessive condition caused by mutations in the gene encoding the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) anion channel. As a result epithelial fluid and ion transport is compromised. Many organs are affected in CF patients, but most of the mortality and morbidity arise from airway disease characterized by chronic infection and inflammation. However, the events leading from CFTR mutation to airway disease are not fully understood. Recent data suggest that abnormal bacteria clearance due to abnormal mucus secretion is the pathogenic event that triggers airway disease in CF. Thus we studied the response of airway epithelia to proinflammatory cytokines, such as Interleukin‐8 (IL‐8), that are released in response to bacterial infection and are elevated in CF airways.Secretion assays and electrophysiological techniques were used to measure the response of submucosal glands, the principal mucus source, to IL‐8. The mucus secretion rate increased from 0.052 to 0.156 nl/min upon the addition of IL‐8 (50 ng/ml). IL‐8 stimulated Na+ flux across the serous acini of the submucosal glands. Both effects were blocked by treatment with the CFTR inhibitor, CFTRinh172. Exposure to CFTRinh172 reduced IL‐8‐stimulated mucus secretion to 0.062 nl/min and abolished Na+ transport across the serous acini.Our results suggest that, in normal lungs, bacteria‐activated secretion increases mucus and bactericidal compounds in the airways, thereby facilitating bacterial removal by mucociliary clearance and reducing the proinflammatory stimulus. In CF airways, bacteria would activate proinflammatory signalling to trigger innate immune responses, but CFTR‐mediated mucus secretion and the resulting “bacterial flush” would be missing, leading to sustained inflammation that may permanently alter the physiology and anatomy of the airways.Grant Funding Source: Supported by APS, University of Saskatchewan, NSERC, Cystic Fibrosis Canada

Acute responses of brown mussel ( Perna perna) exposed to sub-lethal copper levels: Integration of physiological and cellular responses

This study examined the effect of sub-lethal copper levels on selected physiological and cellular responses of the marine bivalve Perna perna. Animals were exposed to five environmentally relevant concentrations of 12.5, 25.0, 37.5 and 50.0 μg L −1 copper and metal accumulation was found to be significantly increased at the two higher copper concentrations after 24 h of exposure. Physiological responses found to increase during acute copper exposure included mucus secretion rate (at 25 and 50 μg L −1 copper), nitrogen excretion rates and oxygen consumption rates (both at 25 and 50 μg L −1 copper). Perna perna changed its substrate utilisation at 25, 37.5 and 50 μg L −1 copper in favour of protein-based metabolism. A higher degree of ROS induced DNA damage was observed at acute exposure to 37.5 and 50 μg L −1 copper. Filtration rate was unchanged during acute copper exposure. A model is proposed that integrates cellular and physiological responses to copper during short-term acute and long-term chronic exposures.

Mucin Dynamics in the Chick Small Intestine Are Altered by Starvation

The absorptive surface of the small intestine is covered by a layer of mucus secreted by goblet cells. The secreted mucins and thickness of the adherent layer influence nutrient digestion and absorption processes as well as the functionality of the mucosa. In this study, methods for the analysis of mucin synthesis and dynamics in the chick small intestine are described. A fragment of chicken mucin cDNA was isolated and characterized; this fraction had 60% homology to human mucin MUC-5AC. The thickness of the mucus adherent layer and the relative amounts of mucin glycoprotein and mRNA were also examined in the small intestines of control and starved chicks. Relative amounts of intestinal mucin mRNA and protein increased in the duodenum and jejunum of starved chicks, and mucus adherent layer thickness decreased throughout the small intestine. In starved chicks, higher mRNA expression and protein concentrations with lower amounts of adherent mucus may be related to a higher rate of degradation of the mucus layer, a lower rate of mucus secretion, or an altered rate of mucin turnover. It thus appears that starvation alters mucus dynamics in the small intestine, and this may affect intestinal digestive function and defense.

Effects of contaminated sediment on the epidermis of mummichog, Fundulus heteroclitus

AbstractSecretion of mucus by epidermal goblet cells protects fish against many biological, physical, and chemical insults encountered in the environment. This study monitored changes in hemoglobin concentration in epidermal mucus and in the density, diameter, and mucus quality of epidermal goblet cells in the mummichog, Fundulus heteroclitus, following exposure to creosote‐contaminated sediment from the Elizabeth River, Virginia, USA. Fish were exposed for 13 d in flow‐through aquaria to either uncontaminated (US) or contaminated (CS) sediments and were sampled periodically. The condition index was lower and the mortality rate and the occurrence of epidermal lesions were higher in CS‐exposed fish than in US‐exposed fish. Hemoglobin contents in epidermal mucus from the former group were significantly higher than from the latter. Significant reductions in both size and density of goblet cells in CS‐exposed fish suggested a mucus secretion rate exceeding its production rate. Significant changes in mucin types between treatments did not occur until day 13 and are not believed to be directly related to the creosote present in the contaminated sediment. These results all indicate that exposure to creosote‐contaminated sediment had a profound and deleterious effect on fish health.

The potential role of mucus in the depuration of copper from the mussels Perna viridis (L.) and Septifer virgatus (Wiegmann)

Experiments were conducted to measure the mucus secretion rate in two common mussels in Hong Kong, Perna viridis (L.) and Septifer virgatus (Wiegmann), when chronically exposed to Cu (50 μg l −1). After a 3-month exposure period, the mucus production rate of P. viridis at 25°C in the metal treatment was 2.65 times that of the control (10.7 vs 4.0 mg g −1 dry wt h −1), while S. virgatus showed a 1.85 times difference (4.41 vs 2.38 mg g −1 dry wt h −1). Mucus secretion by P. viridis under acute Cu exposure (0.5 mg l −1) was significantly higher in the metal treatment than the control (13.43 vs 9.16 mg g −1 dry flesh wt). Metal contents of the mucus secreted was about 18 times those in the control and 6 times in the soft tissues. Therefore, mucus appears to be an effective agent for Cu depuration in the mussel. The significance of these results to the local distribution and abundance of the mussels is discussed.

Mucus gel thickness and turnover in the gastrointestinal tract of the rat: response to cholinergic stimulus and implication for mucoadhesion.

The thickness of the mucus gel and its turnover rate were measured in the stomach, proximal jejunum, cecum and proximal colon of the rat, using microscopy and staining techniques. The specific mucus-secretory responses to carbachol-induced cholinergic stimulus in these locations were also studied. The mucus gel was found to be the thinnest (18 +/- 1 microns) in the cecum, and the thickest in the stomach (39 +/- 14 microns). The effect of carbachol on mucus secretion was profound and dose dependent in the stomach, and less profound, although still dose dependent, in the proximal jejunum. The least responsive organs were the cecum and the proximal colon, where no effect was observed after three doses of carbachol. Mucus secretion rate was significantly higher in the jejunum (1.1 +/- 0.5 microgram glucose equivalent min-1 cm-2) than in the colon (0.5 +/- 0.2 microgram glucose equivalent min-1 cm-2). Also, the proximal jejunum was more responsive to the carbachol stimulus (mucus secretion rate of 5.4 +/- 2.2 micrograms glucose equivalent min-1 cm-2 after carbachol treatment) than the colon (mucus secretion rate of 1.0 +/- 0.4 micrograms glucose equivalent min-1 cm-2 after carbachol treatment). In vitro mucoadhesion studies with Polycarbophil disks were performed in the mucosal tissues of the stomach, jejunum, cecum and proximal colon of the rat with and without cholinergic (carbachol) stimulus. The adhesion force in the cecum and the colon was significantly stronger than in the stomach and proximal jejunum when the studies were performed at pH 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of daylight variations on the energy budgets of shallow-water corals

Energy budgets were determined for small pieces (nubbins) of the coralsPocillopora damicornis, Montipora verrucosa andPorites lobata living at a water depth of 3 m on the fringing reef of Coconut Island, Kaneohe, Hawaii. The budgets were determined for three different types of day: an “ideal” day with no cloud and an in situ daily integrated irradiance at 3 m of 14.385 E m−2 d−1; a “normal” day with sporadic cloud cover and daily irradiance of 11.915 E m−2 d−1; and an “overcast” day with daily irradiance of 6.128 E m−2 d−1. On the “ideal” day, the energy fixed in photosynthesis was more than that required for respiration and growth of both zooxanthellae and animal components of the association, and there was a predicted loss of between 19.3 and 32.4% of the energy fixed. On a “normal” day, the total photosynthetic energy fixation was lower and the excess was between 12.1 and 27.9% of the energy fixed. On the “overcast” day, however, in bothPocillopora damicornis andPorites lobata energy expenditure exceeded photosynthetic energy fixation and the budget was in deficit. Estimates of rate of mucus secretion on an “overcast” day were derived and, when incorporated into the energy budget, it was predicted that all three species would have a deficit budget, necessitating the catabolism of lipid reserves. From published values for lipid storage in these species it was calculated that the reserves would last from 28 d inPocillopora damicornis to 114 d inM. verrucosa. A model is suggested in which corals draw upon their extensive lipid stores on days of sub-optimal light, replenishing the reserves again when daily light levels are high, and finally excreting the excess energy fixed, as mucus-lipid when the lipid stores are replete.

The actions of methacholine, phenylephrine, salbutamol and histamine on mucus secretion from the ferret in-vitro trachea.

Methacholine, phenylephrine and histamine produced highly significant and salbutamol significant increases in the rate of mucus secretion from the ferret trachea. Methacholine, phenylephrine and histamine all produced highly significant increases in the rate of output of lysozyme, but the concentration of lysozyme in the mucus was significantly increased only by phenylephrine. Salbutamol produced no significant change in the output of lysozyme, and the concentration of lysozyme in the mucus was significantly decreased. It is concluded that methacholine, phenylephrine and histamine are potent stimulators of serous cell secretion whereas salbutamol has only a weak secretory action on these cells. Methacholine, histamine and salbutamol probably stimulate secretion from mucous cells as well as from serous cells. The increase in the concentration of lysozyme produced by phenylephrine may be due to stimulation of a fluid reabsorption mechanism.

The effects of peptides and mediators on mucus secretion rate and smooth muscle tone in the ferret trachea.

The effects of a number of peptides and mediators were measured on the secretion rate of tracheal mucus and tracheal smooth muscle tone in the ferret in vitro whole trachea. The comparison of secretion rate and smooth muscle tone, measured simultaneously in the same preparation, shows that there are wide differences in sensitivity between the two systems; there appears to be no relationship between mucus volume output and smooth muscle contraction. The comparison of mucus secretion rate and glycoprotein output in other models and species to these drugs in the same concentrations indicates that there may be mucus glycoprotein output without an increase in volume output.

Cholinergic nerves stimulate mucociliary transport, ciliary activity, and mucus secretion in the frog palate.

Mucociliary transport, ciliary activity, and mucus secretion were studied in the palate of the frog Rana pipiens by direct observation, stroboscopic synchronization of ciliary beating, and histochemistry. Excised palates were studied in vitro, and intact palates were studied in vivo. Electrical stimulation of the glossopharyngeal nerve in vivo or of the palatine nerve in vitro stimulated all three activities. The effect was mimicked by acetylcholine and pilocarpine, enhanced by physostigmine, and blocked by atropine but unaffected by d-tubocurarine. Stimulation increased the number of cilia beating and their rate of beating, the number of goblet cells secreting and, for small acidic cells, the amount of mucus secreted, and the rate and extent of particle transport. The response to tactile stimulation was locally restricted in vitro but widespread in vivo. It was concluded that, although there is a low basal rate of mucus secretion and ciliary activity that is independent of nervous control, stimulation of these activities in the intact animal is mediated through the central nervous system and cholinergic nerves to the palate.

Sympathomimetic drugs stimulate the output of secretory glycoproteins from human bronchi in vitro.

1. We describe a method for supporting pieces of human bronchi in Ussing chambers, for radiolabelling the contents of the secretory cells with 35S, and for collecting radiolabelled macromolecules secreted on to the luminal aspect of the tissue. This method has previously been used to study airway secretions in animals [R. J. Phipps, J. A. Nadel & B. Davis, American Review of Respiratory Disease, (1980) 121, 359-365]. Evidence is given that the radiolabelled molecules are secretory glycoproteins, probably mucus glycoproteins. 2. Phenylephrine, an alpha-adrenoceptor agonist, increased the rate at which the bronchi secreted radiolabelled glycoproteins. Thymoxamine, an alpha-adrenoceptor antagonist, blocked this effect but propranolol, a beta-adrenoceptor antagonist, did not. 3. Dobutamine, a beta-adrenoceptor agonist, increased the rate of secretion of radiolabelled glycoproteins. Propranolol blocked this but thymoxamine did not. 4. Salbutamol, a beta 2-adrenoceptor agonist, also increased the rate of secretion of radiolabelled glycoproteins. Propranolol blocked this effect. 5. We conclude that both alpha- and beta- adrenoceptor agonists increase the rate of glycoprotein secretion in human bronchi in vitro and that this almost certainly means that they increase the rate of mucus secretion.

Regulation of intestinal goblet cell secretion. II. A survey of potential secretagogues.

The factors that regulate the rate of mucus secretion in intestinal goblet cells are only partially defined. Autoradiographic and ultrastructural studies demonstrated that muscarinic cholinergic agents accelerate the exocytosis of mucus from goblet cells in the crypts throughout the small and large intestine, both in vivo and in mucosal organ culture. The present study seeks to identify other factors that may alter mucous secretory rates. Mucosal explants were exposed to potential secretagogues and inhibitors in the organ-culture system and analyzed by light and electron microscopy, alpha- and beta-Adrenergic agents, gastrointestinal regulatory peptides, serotonin, histamine, and dibutyryl cyclic nucleotides were tested over wide concentration ranges. With the exception of histamine, none of these agents accelerated or inhibited the exocytosis of mucous granules. Histamine was effective at the concentration of 10(-4) M and induced rapid, compound exocytosis by crypt goblet cells in mucosal explants from the colon but not from small intestine. The response to histamine was unaffected by atropine. Goblet cells on the mucosal surface released mucus by compound exocytosis when exposed to mustard oil, a nonspecific chemical irritant, but not when exposed to histamine or cholinergic agents.

CYCLIC PENETRABILITY OF HUMAN CERVICAL MUCUS TO SPERMATOZOA IN VITRO

A new method for studying penetration of cervical mucus by spermatozoa in vitro is described involving the use of microtubes and barrier marker bubble. This method is considered better than slide cover glass preparations because it prevents undiscoverable mechanical mixing of mucus and semen and drying of the preparation and because it can be used to study penetration quantitatively and to study the longevity of the spermatozoa in the mucus. Results by this method confirmed the in vivo and in vitro findings of Seguy and Vimeux namely that there is a cyclic production of a glairy translucent cervicalmucus at about midcycle which renders the cervix temporarily penetrable by spermatozoa. Roughly the spread of this phase was in this study from days 9-19 but for any given cycle the period may actually be approximately 4 days. Indications are that menstrual discharge is penetrable by spermatozoa but the mucus of the period between menstruation and midcycle is relatively impenetrable and that of the phase between midcycle and subsequent menstruation is impenetrable. Correlated with the midcycle peak in penetrability is the peak in freedom from leucocytes the peak in pH (except during the menstrual flow) the peak in amount of mucus secreted and the height of conditions favoring greatest longevity of spermatozoa in the mucus. It may well be that the actual viscosity of the mucus encountered by sperm is lowest at midcycle. It is suggested that both low pH and large number of cells in the secretory phase may be caused at least in part by the low rate of mucus secretion. An investigation of the cervical mucus over the cycle by the in vitro method is suggested in cases of otherwise unexplained infertility. A field of usefulness for artificial insemination may be developed in cases due to persistent impenetrable cervical mucus. (authors modified)