Lacritin and other new proteins of the lacrimal functional unit

McKown, Robert L.; Wang, Ningning; Raab, Ronald W.; Karnati, Roy; Zhang, Yinghui; Williams, Patricia B.; Laurie, Gordon W.

doi:10.1016/j.exer.2008.09.002

Cited by 64 publications

(61 citation statements)

References 72 publications

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“…This is the case of prolin-rich protein 4, a lacrytin protein of emerging and increasing interest in ocular surface pathology. 16,17 The following proteins were identified and quantified in the present work: lysozyme C, lactoferrin, serum albumin, lipocalin 1, lipophillin A and B, ZAG.…”

Section: Discussionmentioning

confidence: 99%

“…For patients, the inclusion criteria were a Schirmer test I value higher than 10 mm/5 min, a tear film break-up time (TFBUT) value p10 s, mild subjective symptoms of ocular discomfort as evaluated by an OSDI questionnaire 11 (score [12][13][14][15][16][17][18][19][20][21][22][23][24], and use of tear substitutes only, for treatment, which were suspended for at least 3 days before tear collection.…”

Section: Subjectsmentioning

confidence: 99%

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Tear proteomics in evaporative dry eye disease

Versura

Nanni

Bavelloni

et al. 2010

Eye

141

114

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Purpose: To analyze tear protein variations in patients suffering from dry eye symptoms in the presence of tear film instability but without epithelial defects. Methods: Five microlitres of non-stimulated tears from 60 patients, suffering from evaporative dry eye (EDE) with a break-up time (BUT) o10 s, and from 30 healthy subjects as control (no symptoms, BUT 410 s) were collected. Tear proteins were separated by mono and bi-dimensional SDS-PAGE electrophoresis and characterized by immunoblotting and enzymatic digestion. Digested peptides were analyzed by liquid chromatography coupled to electrospray ionization quadrupole-time of flight mass spectrometry followed by comparative data analysis into Swiss-Prot human protein database using Mascot. Statistical analysis were performed by applying a t-test for independent data and a MannWhitney test for unpaired data (Po0.05). Results: In EDE patients vs controls, a significant decrease in levels of lactoferrin (data in % ± SD): 20.15 ± 2.64 vs 24.56 ± 3.46 (P ¼ 0.001), lipocalin-1: 14.98±2.70 vs 17.73±2.96 (P ¼ 0.0001), and lipophilin A-C: 2.89±1.06 vs 3.63±1.37 (P ¼ 0.006) was revealed, while a significant increase was observed for serum albumin: 9.45 ± 1.87 vs 3.46 ± 1.87 (P ¼ 0.0001). No changes for lysozyme and zinc a-2 glycoprotein (P ¼ 0.07 and 0.7, respectively) were shown. Proteomic analysis showed a downregulation of lipophilin A and C and lipocalin-1 in patients, which is suggested to be associated with post-translational modifications. Conclusions: Data show that tear protein changes anticipate the onset of more extensive clinical signs in early stage dry eye disease.

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Section: Discussionmentioning

confidence: 99%

Section: Subjectsmentioning

confidence: 99%

Tear proteomics in evaporative dry eye disease

Versura

Nanni

Bavelloni

et al. 2010

Eye

141

114

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“…33 Once synthesized, 12 O-and 1 N-glycoslyation sites are predicted. 9 In Coomasie blue staining of recombinant lacritin (Fig. 1B), the appearance of a~6 kDa lacritin proteolytic fragment was noted.…”

Section: Detection Of Tear Lacritin By Western Blotmentioning

confidence: 99%

“…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. 9 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 eye conditions. 10 Sensitivity, inability to provide relative tear concentrations, and lack of information on normal baseline levels or whether lacritin levels are subject to time-ofday variation are all limitations of these studies.…”

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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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“…Lipocalins are a family of lipid binding proteins, they play a role in host defense because of their protease inhibitor activity [183] and by sequestrating iron, they limit bacterial growth [184]. Lacritin is a secreted protein found in tears and saliva, it promotes secretion [185], epithelial cell proliferation [186], corneal wound healing [187], additionally, its C-terminal fragment has bactericidal activity [188]. Changes of tear AMP levels are likely not the cause but rather the consequence of diabetic retinopathy progression, hence, it can be used to develop bedside test for screening purposes.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%