Mucus Composition Research Articles

Surface mucus in the non-glandular region of the equine stomach

In horses, ulceration of the non-glandular region of the stomach is common and has been attributed to the lack of a protective mucus covering. This study aimed to determine whether the non-glandular region is covered by a mucus layer. A mixture of antibodies raised against human gastric mucin (MUC 5 AC) showed a tissue distribution in the glandular region of the equine stomach similar to that seen in humans. Dot blots of mucus from the glandular and non-glandular regions showed cross-reactivity with these antibodies. Various histological fixation and processing techniques were compared for their ability to preserve mucus in the non-glandular region. Fixing frozen sections on-slide for 20 seconds in 20 per cent formalin/1 per cent cetylpyridinium chloride was considered the best method. In conclusion, the equine stomach expresses a gene homologous to human MUC 5 AC. Its product is expressed as a neutral mucin, which is present in the mucus that covers both the glandular and non-glandular regions. Future comparison of mucus composition in the healthy and ulcerated stomach will improve our understanding of gastric ulceration in the horse.

Transdermal contraception.

This review summarizes the clinical studies involving the once-weekly Ortho Evra/Evra contraceptive patch. The patch delivers norelgestromin (NGMN), 150 microg, and ethinyl estradiol (EE), 20 microg, daily to the systemic circulation. The contraceptive patch provided ovulation suppression and cycle control similar to that of oral norgestimate 250 microg/EE 35 microg, significantly decreased mean maximum follicular diameter following a 3-day intentional delayed dosing phase when compared with oral levonorgestrel (LNG) 50/75/125 microg/EE 30/40/30 micorg and oral LNG 100 microg/EE 20 microg, and was as effective as oral LNG 50/75/125 microg/EE 30/40/30 microg and oral desogestrel 150 microg/EE 20 microg in altering cervical mucus composition (i.e., creating a scanty, viscous consistency). The contraceptive patch provided efficacy, cycle control, and safety comparable to that seen with oral LNG 50/75/125 microg/EE 30/40/30 microg, but women were able to correctly follow the weekly dosing regimen significantly more often than the daily oral contraceptive dosing regimen. Less than 2% of patches were replaced because of complete detachment in these trials. The patch was not associated with phototoxicity or photoallergy. The contraceptive patch, the only noninvasive, weekly birth control method that a woman can self-administer, will be a valuable addition to current contraceptive options.

Effect of D-002 on gastric mucus composition in ethanol-induced ulcer

This study was designed to determine the effect of D-002, a natural product isolated and purified from beeswax (Apis mellifera), on gastric mucus composition on ethanol-induced ulcer in rats. The morphology of the lesions was analysed histologically, and morphometric analysis of gastric-gland content in total glycoprotein and sulphated macromolecules were done. Oral pretreatment with D-002 at 5 and 25 mgkg−11 before oral administration of ethanol at 60%, produced a significant increase in the amount of gastric mucus and total protein. The histomorphometric evaluation of the gastric damage at the same doses showed a significant increase in neutral glycoproteins and sulfated macromolecules. It is concluded that enhancement of the quantity and quality of the mucus could partly explain the gastroprotective effect of D-002.

ANALYSIS OF PULMONATE MUCUS BY INFRARED SPECTROSCOPY

Infrared (IR)-spectroscopy can analyse a range of molecules in diverse biological systems and has already found use in forensic biology, clinical diagnosis, and environmental monitoring. Using IR-spectroscopy to analyse gastropod mucus represents an original application of this technique. This study describes the differences in mucus composition that appear to be species specific, as well as identifying many of the molecular components of the mucus itself. All species studied showed IR absorbance bands indicating the presence of amide bonds as well as profiles associated with the sugar side chains, indicating a commonality associated with the gel properties of pedal mucus which may have a role in locomotion. The species-specific band profiles may provide an indication of the differing roles required of the mucus by the specific gastropod tested.

Effects of Clarithromycin on Rheological Properties of Nasal Mucus in Patients with Chronic Sinusitis

Macrolide antibiotics have a variety of actions along with antimicrobial action. To determine the effects of oral administration of clarithromycin (CAM) on rheological properties, we measured the spinability, dynamic viscoelasticity, and solid composition of human nasal mucus from 18 patients with chronic sinusitis before and after administration of CAM for 4 weeks. After administration of CAM, the spinability and percent solid composition of nasal mucus increased from 26.5 +/- 12.2 mm to 40.2 +/- 18.7 mm and 7.86% +/- 3.47% to 13.90% +/- 3.67% (p < .05), respectively, whereas the ratio of the viscosity to the elasticity (eta'/G') of nasal mucus after the administration of CAM decreased in all of the mucus samples. These results suggest that treatment with CAM may modulate the rheological properties of nasal mucus in patients with chronic sinusitis.

Changes in the Electrophoretic Profiles of Gill Mucus Proteases of the Eastern Oyster Crassostrea virginica in Response to Infection by the Turbellarian Urastoma cyprinae

Urastoma cyprinae occurs on the gills of various bivalves species, including the eastern oyster Crassostrea virginica. While the worm is known to cause severe gill disruption in mussels, no evidence of this nature has been described for oysters. Nonetheless, high levels of U. cyprinae have been reported in oysters, which may, in turn, reduce the oyster's overall condition. U. cyprinae is strongly attracted to oyster gill mucus, which is suggested to play an active role in the worm's feeding activities. Furthermore, host mucus contains many active components, including proteases, which have been suggested to play a defensive role against invading organisms. It follows, therefore, that some of the interactions between U. cyprinae and oysters take place in host gill mucus. Studies were undertaken to determine whether the presence of U. cyprinae altered the electrophoretic profiles of oyster gill mucus, using proteases as indicators. Findings reveal that oyster gill mucus contains three proteases, a putative acid protease at 96 kDa, a zinc metalloprotease at 64 kDa, and a serine protease at 33 kDa. Results based on experiments using mucus preparations extracted from infected and noninfected oysters, along with those using lyophilized mucus incubated with live U. cyprinae, confirm that the presence of U. cyprinae alters the protease composition of gill mucus. The present data demonstrate that both U. cyprinae and host gill mucus actively secrete proteases. While the precise roles of these enzymes still need to be defined, one of their functions may be associated with digestion-related activities induced by the worm.

The chemotactic response of Vibrio anguillarum to fish intestinal mucus is mediated by a combination of multiple mucus components.

Chemotactic motility has previously been shown to be essential for the virulence of Vibrio anguillarum in waterborne infections of fish. To investigate the mechanisms by which chemotaxis may function during infection, mucus was isolated from the intestinal and skin epithelial surfaces of rainbow trout. Chemotaxis assays revealed that V. anguillarum swims towards both types of mucus, with a higher chemotactic response being observed for intestinal mucus. Work was performed to examine the basis, in terms of mucus composition, of this chemotactic response. Intestinal mucus was analyzed by using chromatographic and mass spectrometric techniques, and the compounds identified were tested in a chemotaxis assay to determine the attractants present. A number of mucus-associated components, in particular, amino acids and carbohydrates, acted as chemoattractants for V. anguillarum. Importantly, only upon combination of these attractants into a single mixture were levels of chemotactic activity similar to those of intestinal mucus generated. A comparative analysis of skin mucus revealed its free amino acid and carbohydrate content to be considerably lower than that of the more chemotactically active intestinal mucus. To study whether host specificity exists in relation to vibrio chemotaxis towards mucus, comparisons with a human Vibrio pathogen were made. A cheR mutant of a Vibrio cholerae El Tor strain was constructed, and it was found that V. cholerae and V. anguillarum exhibit a chemotactic response to mucus from several animal sources in addition to that from the human jejunum and fish epithelium, respectively.

Differences in the Composition of Adhesive and Non-Adhesive Mucus From the Limpet Lottia limatula.

The mucus used by the limpet Lottia limatula to form glue-like attachments was compared biochemically to the slippery mucus produced during other activities, such as suction adhesion. Colorimetric assays revealed the protein content of the adhesive mucus to be 2.1 times greater than that of the non-adhesive form, and the carbohydrate content to be 1.9 times greater. Both forms of mucus contained roughly six times as much protein as carbohydrate, and there was no difference in their inorganic elemental compositions. Quantitative analysis of the protein content by SDS-PAGE and a scanning densitometer revealed a similar protein composition in both forms of mucus; but three notable differences emerged. First, the overall difference in protein concentration was confirmed. In addition, there was a 118 kD protein that was common only in the adhesive mucus, and a 68 kD protein that occurred only in the non-adhesive mucus.

Colonization of the Murine Gut byBifidobacterium bifidumandClostridium perfringensduring Ageing

The level in bifidobacteria colonizing the human gut is decreasing during ageing whereas clostridia proliferate. It was hypothezised that the poorly growing bifidobacteria became unable to exert colonization resistance against clostridia. In order to analyse the relationship between bifidobacteria and clostridia; we investigated in germfree mice the bifidobacterial colonization of the gut according to the diet and to the endogenous bifidus factors (BB) contained in the mucus. The slower colonization might be related to the lack of bifidogenic factors in the control food (SHF mice) whereas the low contamination level found later in SHF and CHF mice would be the result of the modification to the mucus composition induced by either diet. In a second step, C. perfringens was given to B. bifidum monoassociated mice fed the most efficient food and we studied the colonization by both strains during ageing. In conclusion, B. bifidum did not exert any colonization resistance against C. perfringens , neither did C. perfringens against B. bifidum . As the intestinal bifidobacterial growth seemed to depend on the intestinal glycoprotein concentration, the relative decrease observed in dixenic mice might be the result of a change in the mucus secretion induced by C. perfringens colonization. Keywords: Bifidobacterium bifidum , Clostridium perfringens , age, colonization, gut, mice.

Some histochemical characteristics of the mucous microenvironment in four salmonids with different susceptibilities to gyrodactylid infections

AbstractSkin mucous cells and mucus from four salmonids (rainbow trout, brown trout, Conon salmon, Iijoki salmon) with different susceptibilities to infection withGyrodactylus derjaviniandG. salariswere partly characterized by cytochemistry, immunoblotting and immunocytochemistry. Mucous cell densities in various fin types were partly correlated with resistance to infection withG. derjavinibut not withG. salaris. Lectin binding assays indicated slight differences in carbohydrate composition of mucus from the four salmonids but serum antigens specific for salmonids were found in mucus from all of them. Antisera against salmon immunoglobulin and rainbow trout complement factor C3 reacted with mucus from all of the salmonids but not with mucus from phylogenetically unrelated fish. Antisera raised against ACTH reacted with mucus components from rainbow trout, brown trout and Conon salmon but not with mucus from Iijoki salmon. These findings are discussed in relation to the host specificity of ectoparasites and susceptibility to infection.

The influence of intestinal mucus components on the diffusion of drugs.

Mucus, a potential diffusional barrier to drug absorption, is a complex mixture of mucin and other components. The objective of this study was to investigate the composition of native pig intestinal mucus (PIM) and the influence of identified mucus components on drug diffusion. The mucus components were separated by CsCl-density gradient centrifugation and further analyzed. The self-diffusion coefficients of mannitol, metoprolol, propranolol, hydrocortisone, and testosterone, ranging in lipophilicity from logK = -3.1 to logK = 3.3, were determined, using a small scale tracer technique. The diffusion of drugs in PIM, in solutions or dispersions of individual mucus components, and in an artificial mucus model (MLPD) reconstituted from the major mucus components mucin, lipids, protein, and DNA was compared. The dry weight of pig intestinal mucus contained (%, w/w); mucin (5%), lipids (37%), proteins (39%), DNA (6%), and unidentified materials. The most commonly occurring lipids were free fatty acids, cholesterol, and phospholipids while the most common protein was serum albumin. In PIM, but not in the purified pig gastric mucin (PPGM) solution, the diffusion of the lipophilic drugs metoprolol, propranolol, hydrocortisone, and testosterone was reduced compared to that of the hydrophilic drug mannitol. The diffusion of the lipophilic drugs was also significantly reduced in a dispersion of identified mucus lipids compared to that of mannitol. The diffusion in MLPD was similar to that in PIM for mannitol, propranolol, hydrocortisone, and testosterone, but somewhat lower for metoprolol. Lipids, rather than mucin glycoproteins, are a major component which contributes to reduced diffusion of drugs in native intestinal mucus. The results suggest that reconstituted artificial mucus models are interesting alternatives to native mucus models.

Heterogeneity of the composition and thickness of tracheal mucus in rats.

Inability to preserve airway mucus in situ has limited our understanding of its structure and function. This light- and transmission electron-microscopic study of rat tracheal mucus used a nonaqueous fixative that retains mucus (epiphase) over a lucent layer (hypophase). The fixative is a 1% solution of osmium tetroxide dissolved in a perfluorocarbon. The mean thickness of rat tracheal epiphase was 5 microns, with significant variation (0.1-50 microns) around the tracheal circumference. Tracheal mucus was thickest at the trachealis muscle region and contained cells, cellular debris, and a variable amount of surfactant and lipid, estimated at 4-16% of the total epiphase in five rats, with a mean composition of 9%. Lipid was observed on the surface of the epiphase, embedded within mucus, and at the epiphase-hypophase interface. Refined study of developmental, physiological, and pathological alterations to the airway coat may benefit from this approach.

Changes in the Elemental Composition of Bladder Mucus in Stone and Non-Stone forming Patients following Augmentation Cystoplasty

The incidence of bladder stones is increased by 50% following bladder augmentation(l,2). Stones require surgical removal as they are typically too large to pass. A recurrence rate of 19% has been noted(2) necessitating multiple sugical procedures. Etiology of stones in augmented bladders is due to a number of factors including foreign body reactions, metabolic abnormalities, infection and intestinal mucus. In order to determine whether the elemental composition of bladder mucus plays a role in the development of bladder calculi, energy dispersive x-ray spectrometry(EDXS) was done on the mucus from stone and non-stone forming patients. In addition, stones from the same patients were examined and analyzed and the data compared with the composition of the mucus.Eighteen patients participated in this study, 14 of whom had ileo-cystoplasties and 2 ileo-cecal augments. Two were cloacal extrophy patients where the hind gut was incorporated with the bladder halves. To avoid any foreign body reactions, metal staples were not used in any of the bladder augmentation procedures.

Bifidobacteria and Human Health: Regulatory Effect of Indigenous Bifidobacteria onEscherichia coliIntestinal Colonization

Bifidobacteria are assumed to exert colonization resistance to enteric pathogens. We associated C3H germfree mice with eitherBifidobacterium longumorEscherichia colior both strains and studied how they settled in the gut and the lymphoid organs as well as their effect on mucus composition. Within 24 hE. colicolonized the gut of germfree orB. longumex-germfree mice. In contrast,B. longumwas established in the intestine ofE. coliex-germfree mice only 1 month after inoculation whereas it colonized the germfree gut within 24 h. AlthoughB. longumdid not exert colonization resistance toE. coli, the establishing of bifidobacteria in the gut partly prevented changes in theE. colicell wall. After colonization of the germfree orB. longummono-associated mice,E. colilipopolysaccharide exhibited a higher concentration of Kdo and the O-antigen side chain disappeared. A reduction in Kdo content was observed within 1 month inE. coli–B. longumdiassociated mice whereas it remained at a high level inE. colimono-associated mice. Association in a second step withB. longumled to Kdo reduction. Changes inE. coliLPS might be related to mucus modification. Inoculation of either bacterium led to a slow increase in mucus protein content which was however twice as high afterE. coliimplantation. Inoculation ofB. longumin a second step led to a reduction in protein content beforeB. longumcolonized the intestine at a high level suggesting that the protein concentration in the mucus was controlled by the host itself. A new glycoprotein of 200–230 kDa detected during the period preceeding colonization seemed to be broken down byB. longum. The resulting end product might participate in the restoration ofE. coliLPS. Finally,B. longuminoculation led to the disappearance ofE. colifrom kidneys, liver, spleen and lung. The organs were cleared ofE. colibeforeB. longumhighly colonized the intestine suggesting that high intestinal colonization byB. longumwas not required. Regulation ofE. coliinvasion seemed to depend on the ability ofB. longumto stimulate the immune system.

Ontogenetic development and composition of the mucous cells and the occurrence of saccular cells in the epidermis of Atlantic halibut

An increase in the number of mucous cells of the epidermis, as well as qualitative changes of the mucus composition from predominantly neutral to a mixture of neutral and sulphated glycoproteins occurred during the development from a pelagic larva to a bottom‐dwelling flatfish. Numerous saccular cells were observed in the epidermis of the yolk‐sac larvae that disappeared simultaneously as the mucous cells increased in number in the epidermis of the metamorphosed halibut. These findings may help to understand the protective role of the mucus layer of Atlantic halibut during development as compared to other fish species in aquaculture.

Relationships among the composition of mucus, epithelial lining liquid, and adhesion of microorganisms.

Airway surface liquid (ASL) is complex and comes from many sources, in particular glands and epithelium. The mucoglycoproteins present bind to bacteria. Bacterial membranes contain adhesins that bind to receptors on the mucus. The bound bacteria multiply and release toxins that diffuse to the epithelium and damage or destroy it, inhibiting mucociliary transport. The damaged epithelium releases products such as phospholipids into the ASL. These change the physical properties of the mucus and also promote mucus secretion, which may block smaller airways. Airway surface liquid contains constituents such as immunoglobulins, lysozyme, and lactoferrin and neutrophil products such as proteases that act on bacteria. Few bacteria adhere to healthy epithelium. To adhere, most require damaged tissue with membrane receptors that encourage bacterial invasion. If the epithelium is destroyed, bacteria adhere to the basement membrane or extracellular matrix. A damaged epithelium can also cause hyperresponsiveness of airway secretory mechanisms, with increased gland secretion that in turn interacts with the bacteria.

Molecular anatomy of an endodermal gland: investigations on mucus glycoproteins and cell turnover in Brunner's glands of Didelphis virginiana using lectins and PCNA immunoreactivity.

Brunner's glands are located in the submucosa of the proximal duodenum and are unique to mammalian species. The North American opossum (Didelphis virginiana) is generally regarded as a prototype marsupial that closely resembles fossil didelphids which can be placed at the beginning of mammalian evolution. The current investigation provided an opportunity for the analysis of secretory products from these glands in a species thought to be more closely related to earlier evolutionary forms. Extracts of Brunner's glands were subjected to SDS-PAGE and Western blotting. The results indicate the presence of two high molecular weight PAS-positive glycoprotein bands. In addition to these two PAS-positive bands, several other glycoprotein bands were detected in the high molecular weight range that bind several lectins which typically recognize O-linked carbohydrates indicative of mucus type glycoproteins. The same lectins bind to glandular structures in tissue sections. Comparison of lectin binding sites with the pyloric glands of the stomach and duodenal goblet cells indicates that Brunner's glands carbohydrate residues resemble those of the pyloric glands more closely than those of the duodenal goblet cells. The low cell turnover rate in Brunner's glands is in contrast to the rapid turnover rate of goblet cell precursors in the duodenal crypts. The mucus composition and the cell turnover rate correlate well with embryological data and suggest that Brunner's glands of Didelphis evolved from an epithelium more closely associated with the stomach than that of the duodenum as the topography of the gland would suggest.

Rat intestinal mucosal responses to a microbial flora and different diets.

The effects of diet on the histochemical composition of intestinal mucosubstances and the morphology of the villi and crypts were investigated by comparing the data of germ free and conventionally maintained rats fed either a purified diet or a commercial diet. The influence of intestinal microflora was evaluated by comparing the germ free rats and those harbouring either a conventional rat flora or a human microbial flora. In both germ free rats and those maintained conventionally, feeding a purified diet resulted in shallower crypts in the small intestine but deeper crypts in the large intestine compared with their counterparts fed on the commercial diet. The preliminary data obtained with association of human flora showed a reduction of the villus height and crypt depth in the small intestine and, to some extent, the amount of neutral mucins in the goblet cells of both small and large intestine and an increase in the amount of sulphated mucins in the large intestine. In rats given the commercial diet the periodic acid Schiff staining for neutral mucins was more intense in the upper crypts of the small intestine than in the lower crypts, and to a lesser extent in the upper crypts of the large intestine. These results provide evidence that the dietary composition, microbial flora, as well as the interactions between the dietary constituents and microbial flora change the mucosal architecture and the mucus composition and therefore alter the functional characteristics of the intestinal tract.

New Concepts of Pathogenesis in Inflammatory Bowel Disease

The precise etiology and mechanisms of inflammatory bowel disease (IBD) are still unclear. Nevertheless, several concepts are gaining acceptance and constitute the basis for a better understanding of its pathogenesis and for improved therapy. The association of Crohn’s disease (CD) and ulcerative colitis (UC) with ‘western’ lifestyle is well recognized, and is considered a reason for the increasing frequency of CD and UC in countries with previously low incidence. Proposed linkages of CD and UC with particular human leukocyte antigen haplotypes suggest a genetic predisposition, but no uniform or consistent patterns have emerged. Similarly, the study of susceptibility or disease markers has not offered reproducible results. The search for specific infectious agents is being pursued, and the measles virus is presently considered a possible culprit. A true explosion has occurred in the area of animal models, and a large number of chemically or genetically induced experimental colitides are at hand. Immunological factors continue to dominate the bulk of basic research in IBD. This area is vast and complex, and autoantibodies, immune, epithelial and mesenchymal cells, lipid mediators, cytokines, neuropeptides and oxygen metabolites are under investigation. Finally, other factors whose role in IBD is uncertain, including smoking and possible abnormalities of intestinal permeability or mucus composition, continue to receive attention. These extensive and varied efforts are yielding some profits, and new forms of therapy are being devised. Based mostly on studies of soluble mediators, a number of novel immunosuppressive and highly specific blocking agents are being developed and undergoing clinical trials.

Differences in mucus and serum immunoglobulin of carp ( Cyprinus carpio L.)

Electrophoretic analysis did not reveal clear differences between skin mucus and serum immunoglobulin (Ig) of carp. The majority of both Igs were tetrameric (±760 kDa) and composed of 25 kDa light (L) chains and 70 kDa heavy (H) chains, but dimeric and monomeric forms were found as well. Monoclonal antibody (mAb) WCI 12 produced from serum Ig appeared to react with the H chain of both molecules. After immunisation of mice with purified mucus Ig, mAbs could be selected that were reactive with mucus Ig only. Two of these mAbs (WCI M1 and WCI M2) were immunoreactive with the H chain of mucus Ig and not or hardly immunoreactive with the H chain of serum Ig, indicating differences in the composition of the H chains of both molecules. Because WCI M2 appeared to recognize a carbohydrate determinant, differences seem to occur in the protein as well as carbohydrate composition of mucus and serum Ig. Flow cytometric results showed that both mAbs were reactive with the same subpopulation of WCI 12-positive B cells. Immunohistochemical reactions on cryosections also showed a limited reaction by these mAbs compared with WCI 12; only epithelium of skin and bile ducts and capillaries in the liver were strongly positive with these mAbs. The presence of mucus Ig at these locations is discussed. Our results indicate structural and functional differences between mucus and serum Ig, which may explain the mucosal immune responses reported for fish. Such a specific mucosal defense system can be very important for fish, living in a pathogenrich environment.