Variability of tear protein levels in normal young adults: between-day variation

Ng, Vincent; Cho, Pauline; Mak, Shearer; Lee, August

doi:10.1007/s004170000165

Cited by 43 publications

(37 citation statements)

References 15 publications

(19 reference statements)

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“…11 Quantitation of major tear proteins has been studied by gel electrophoresis (lactoferrin, tear-specific prealbumin, and lysozyme) [12][13][14] and by size-exclusion chromatography combined with enzymatic assays and immunologic methods (lysozyme, IgA, IgG, albumin, and lactoferrin). 15 More recent studies have employed a variety of mass spectrometry-based methods.…”

Section: Purposementioning

confidence: 99%

Tear Lacritin Levels by Age, Sex, and Time of Day in Healthy Adults

Seifert¹,

Gandia²,

Wilburn³

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.Several small proteomic studies suggest that the prosecretory tear protein lacritin may be selectively downregulated in dry eye syndrome and in blepharitis, yet little information is available about normal baseline levels. This study assessed lacritin levels in tears from healthy individuals and addressed whether they differ according to sex, age, or time of day.METHODS. Rabbit antibodies against lacritin N-terminal peptide EDASSDSTGADPAQEAGTS (Pep Lac N-Term) were generated and characterized against human recombinant lacritin and N-65 truncation mutant. Basal tears were collected from 66 healthy individuals ranging in age from 18 to 52 years, and at four times during one 24-hour period from 34 other individuals. Lacritin levels were then analyzed by ELISA and Western blotting.RESULTS. Anti-Pep Lac N-Term bound lacritin, but not truncation mutant N-65 that lacks the N-terminal antigenic site. Tear lacritin levels followed a normal distribution with a mean of 4.2 6 1.17 ng/100 ng total tear protein. Levels differed little by age or sex, and decreased slightly between 4 and 8 hours in a 24-hour cycle. Tear-blocking effects were minimal, as suggested by spiking of tears with recombinant lacritin.CONCLUSIONS. Anti-Pep Lac N-Term-detectable lacritin comprises~4.2 ng/100 ng total tear protein in healthy individuals, with no significant differences between males and females or among individuals between 18 and 52 years old. Levels decrease slightly in the late afternoon. These findings provide a baseline for future immunodiagnostic studies of lacritin in dry eye and other ocular diseases. (Invest Ophthalmol Vis Sci. 2012;53:6610-6616 Lacritin's ability to stimulate tear production makes it an interesting protein to study for its potential involvement in dry eye syndrome and other eye-related diseases. Dry eye affects the lives of over 25 million Americans, yet it is poorly understood and lacks sensitive early-stage diagnostics. Current tests are more appropriate for later disease stages, making difficult the diagnosis of patients with mild to moderate symptoms. 3 Moreover, tests such as Schirmer strips, ocular surface staining, and tear film breakup time are still not uniformly applied 4 (although standardization has improved with publication of the International Dry Eye Workshop report 5 ), and new devices to assess tear osmolarity show promise, 6 although not in isolation. 7 Development of an assay to help diagnose both early-onset and later dry eye, recognizing that there may be different etiologies, would be of great benefit.Dry eye syndrome and other associated conditions are believed to correlate with changes in specific protein content of the ocular surface. 8 Some small proteomic studies suggest that lacritin is one of only 4% to 5% of the tear proteome that is downregulated in dry eye or dry eye-related conditions. Lacritin levels measured by mass spectroscopy analysis of tear samples were 7-fold less from 11 individuals with contact lensrelated dry eye than from 10 users of contact lenses with normal ...

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Section: Purposementioning

confidence: 99%

Tear Lacritin Levels by Age, Sex, and Time of Day in Healthy Adults

Seifert¹,

Gandia²,

Wilburn³

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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“…They are involved not only in the defence against microbial invasion of the eye, but also in maintaining tear film stability and lubrication between the eye and the eyelids. Tear protein composition may show a between-day variation [22] and is evidence for a nocturnal change of tear fluid protein composition [27]. The concentration of tear proteins also depends on age, when the level of lysozyme in tears decreases while that of IgA increases [19].…”

Section: Discussionmentioning

confidence: 99%

“…By this method, a between-day variation of tear protein levels in normal young adults was observed [22].…”

Section: Introductionmentioning

confidence: 99%

The effect of sample treatment on separation profiles of tear fluid proteins: Qualitative and semi-quantitative protein determination by an automated analysis system

Schmut

Horwath‐Winter

Zenker

et al. 2002

Graefe's Arch Clin Exp Ophthalmol

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Tear proteins - in contrast to serum or aqueous humour proteins - are very sensitive to changes in sample buffer temperature as well as incubation time with buffer. To obtain comparable results for tear fluid proteins, the sample buffer applied and the incubation time and temperature must be observed carefully. This can be demonstrated by both the new Agilent 2100 Bioanalyzer method and PAGE. These results are of importance when comparing tear fluid protein pattern for the diagnosis and course control of dry-eye syndrome and of other diseases of the anterior part of the eye.

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“…(a) chemical stimuli: gas like bromacetone [6,34], fumes (or vapor) of liquid agents like ethanol, formalin or ammonium [3,35,36] or cigarette fumes [37]; (b) physical stimuli: intensive light [38], mechanical stimuli by means of gentle aggression on the cornea (puff of air, fine brush, little sponge placed against the lower fornix) [15,37,39,40,41] and (c) physiological stimuli: the tearing reflex can be induced by a sneezing or yawning stimulation, which presents the great advantage of not altering ocular structures [14,42,43].…”

Section: Tearing Stimulationmentioning

confidence: 99%

“…20-100 Ìl saline solution) in order to collect a sufficient volume [28,46,47]. Protein levels obtained using this preliminary instillation leads to values significantly lower compared to other techniques [14]. Great cautions must be taken to avoid overflowing and to verify the homogenisation of the agent in lachrymal fluid.…”

Section: Tearing Stimulationmentioning

confidence: 99%

Lachrymal Determinations: Methods and Updates on Biopharmaceutical and Clinical Applications

Dumortier

Chaumeil²

2004

Ophthalmic Res

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This article displays different procedures used to collect lachrymal fluid and describes some of its applications. Sampling tears represents the main difficulty to produce precise and reproducible results. The direct sampling procedure consists in collecting tears with capillary tubes and has the drawback of demanding previous stimulation that induces major dilution. The indirect method does not require preliminary stimulation but has been held responsible for altering epithelium and promoting leakage from plasma. Schirmer strips and sponges are classically required. Applications are numerous in biopharmaceutical and clinical fields. The determination of endogenous components has great potentiality as a diagnostic tool, but the use of tear as a substitute of plasma does not present clinical relevance. Levels of drugs like immunosuppressive or antibiotic agents are determined in tears to verify that pharmacological concentrations are reached and frequency of administration is deduced from kinetic fitting.

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Variability of tear protein levels in normal young adults: between-day variation

Cited by 43 publications

References 15 publications

Tear Lacritin Levels by Age, Sex, and Time of Day in Healthy Adults

Tear Lacritin Levels by Age, Sex, and Time of Day in Healthy Adults

The effect of sample treatment on separation profiles of tear fluid proteins: Qualitative and semi-quantitative protein determination by an automated analysis system

Lachrymal Determinations: Methods and Updates on Biopharmaceutical and Clinical Applications

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