Secreted human conjunctival mucus contains MUC5AC glycoforms

Ellingham, Roger B.; Berry, Monica; Stevenson, D.Lang; Corfield, Anthony P.

doi:10.1093/glycob/9.11.1181

Cited by 48 publications

(45 citation statements)

References 26 publications

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“…After a minimum of 24 h dispersal in the chaotrope, mucins were purified from the samples using methods as previously described, for dog, rabbit [32] and human samples [33]. Briefly, mucins were isolated from proteins, glycoproteins, and nucleic acids by caesium chloride density gradient centrifugation at a starting density of 1.4 g/ml, Fractions were pooled between 1.3 and 1.47 g/ml, and subjected to gel filtration on Sepharose CL-4B columns.…”

Section: Collection Of Mucus Samples and Purification Of Mucinsmentioning

confidence: 99%

Glycan structures of ocular surface mucins in man, rabbit and dog display species differences

et al. 2008

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The composition of the mucus gel of the tear film reflects the competing needs for transparency, stability, hydration, and protection of the ocular surface. Mucins form the macromolecular scaffolding of this hydrated gel, and glycans decorating these glycoproteins represent a rich source of binding ligands that may both modulate microbial binding and regulate the physicochemical characteristics of the gel. This study compares the structure of O-linked glycans derived from the ocular mucins of three species, to determine whether the ocular surface microenvironment dictates the need for a common pattern of O-linked carbohydrate structures. Ocular mucus aspirates were collected from healthy humans, rabbits and dogs. Mucins were purified using standard protocols. O-glycans were released by hydrazinoloysis and subsequently analysed by a combination of HPLC, exoglycosidase digestions and LC-MS/MS. A total of 12 different O-glycans were identified. In human ocular mucin, the majority were negatively charged and terminated in sialic acid, whilst those from rabbit or dog were mainly neutral and terminated in alpha 1-2 fucose and/or alpha 1-3 N-acetylgalactosamine. The glycans were short: the most common structures being tetra-, tri- or disaccharides. Less elaborate glycan structures are encountered at the ocular surface than at many other mucosal surfaces. Species-specific glycan expression is a feature of ocular surface mucins, and has implications for their defensive properties where different microbial and environmental challenges are encountered.

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Section: Collection Of Mucus Samples and Purification Of Mucinsmentioning

confidence: 99%

Glycan structures of ocular surface mucins in man, rabbit and dog display species differences

et al. 2008

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“…Mucins are decorated with epitopes whose ligands can be found on cells of the immune system (Hajela et al 1994;Handa et al 1997;Kim et al 1999;Prakobphol et al 1999;Leppanen et al 2002). We have shown that these epitopes are also common on normal human ocular mucins (Berry et al 1996(Berry et al , 2000(Berry et al , 2003Ellingham et al 1999).…”

Section: Introductionmentioning

confidence: 98%

Normal but not altered mucins activate neutrophils

et al. 2004

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Interactions between leucocytes and their surroundings are mediated through oligosaccharide epitopes, some of which are also expressed on ocular mucins. Neutrophils represent the majority of immune cells in the proinflammatory environment of the ocular surface during sleep. We have tested whether changes in mucin glycosylation, as occur in dry eyes, influence the phenotype and activation of neutrophils. Peripheral blood leucocytes were circulated over equal concentration mats of ocular surface mucins purified from normal volunteers and dry-eye patients, and in sequence over normal and pathological mucins in all combinations. Non-adherent cells were tagged with monoclonal fluorescent antibodies to leucocyte determinants and analysed by flow cytometry. Oxidative burst, assessed with dihydrorhodamine, was followed in cells and supernatant. At a speed similar to that of leucocyte traffic in the retina, normal mucins caused a decrease in neutrophil cathepsin G fluorescence, a decrease that was not observed with mucins from patients with Meibomian gland disease or Sjogren syndrome. No effect was detected at a higher flow. Supernatant and cells collected after circulation over normal mucin showed increased rhodamine fluorescence, indicative of oxidative burst. Fluorescence could also be observed in intact cells adherent to dry-eye mucins. Non-adherent cells could be activated with phorbol 12-myristate 13-acetate after flow over any mucin or combination of mucins. Differences in neutrophil activation after exposure to normal and pathological mucins highlight reciprocal influences at the interface between local and systemic immunity.

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“…It is constituted primarily of secretory MUC5AC mucin secreted from conjunctival goblet cells (28), while membrane-bound mucins, MUC1 and MUC4, are present on corneal and conjunctival epithelial cells (1), with recent evidence that a soluble form of MUC4 is present in human tears (41). Ocular mucin is polydisperse, consisting of species with different size, charge, and glycosylation patterns (3,17,23) that contribute to the structure and function of mucus.…”

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confidence: 99%

Mucin Degradation Mechanisms by DistinctPseudomonas aeruginosaIsolates In Vitro

Aristoteli

Willcox

2003

Infect Immun

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Pseudomonas aeruginosa has emerged as an important causative agent of bacterial keratitis, a rapidly progressive ocular condition that may result in blindness. Secretory mucin forms the main constituent of the precorneal tear film, a three-layer film on the ocular surface protecting the underlying corneal epithelium from potential pathogens. The purpose of the present study was to compare mucin degradation mechanisms between ocular P. aeruginosa strains. Mucin degradation was assessed by agarose electrophoresis, lectin blotting, and size exclusion chromatography. The results indicate that certain P. aeruginosa strains (Paer12, ATCC 15442, 6294, and Paer25) had depleted mucin from the culture supernatant and that this was contingent on the inherent ability of these isolates to produce proteases. Non-protease-producing strains (Paer1 and Paer3) did not appreciably degrade mucin. Further, galactosidase, N-acetylglucosaminidase, and N-acetylgalactosaminidase activities were detected in some strains, suggesting the operation of further mechanisms of mucin degradation by P. aeruginosa. Mucin degradation by P. aeruginosa also seemed to be for the acquisition of nutrients, as a growth advantage was observed in mucin-depleting strains over nondepleting strains in the long term. It is postulated that the degradation of mucin serves to collapse the mucin barrier and its associated network containing antibacterial tear components and to provide energy for sustained bacterial growth.Microbial keratitis is a highly destructive and invasive infection that may result in corneal ulceration and loss of vision if prompt treatment is not administered (11). Pseudomonas aeruginosa has been isolated from most microbial keratitis patients, in some cases as the predominant bacterium (7, 56) and in others as the main gram-negative bacterium (44). It has also been associated with ocular disease resulting from contact lens wear, namely, contact lens acute red eye (CLARE) (24). This noninvasive ocular condition, characterized by a host inflammatory response, is presumably initiated by bacterial lipopolysaccharide (47). Contact lens wear seems to reduce tear exchange (39), where mucus is the predominant component of the tear film. Delayed tear clearance in certain contact lens wearers may prove opportune for the initiation of pathogenesis such as microbial keratitis.In the eye, mucus is the predominant component of the tear film (8, 37, 43), a three-layered film on the surface of the eye forming the first barrier between the outside environment and the underlying corneal epithelial cells. It is constituted primarily of secretory MUC5AC mucin secreted from conjunctival goblet cells (28), while membrane-bound mucins, MUC1 and MUC4, are present on corneal and conjunctival epithelial cells (1), with recent evidence that a soluble form of MUC4 is present in human tears (41). Ocular mucin is polydisperse, consisting of species with different size, charge, and glycosylation patterns (3, 17, 23) that contribute to the structure and function of mucus...

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Secreted human conjunctival mucus contains MUC5AC glycoforms

Cited by 48 publications

References 26 publications

Glycan structures of ocular surface mucins in man, rabbit and dog display species differences

Glycan structures of ocular surface mucins in man, rabbit and dog display species differences

Normal but not altered mucins activate neutrophils

Mucin Degradation Mechanisms by DistinctPseudomonas aeruginosaIsolates In Vitro

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