April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Lack of Diurnal Variation of the Human Tear Protein Lacritin in Healthy Adults
Author Affiliations & Notes
  • Robert L. McKown
    Integrated Science & Technology,
    James Madison University, Harrisonburg, Virginia
  • N. Gandia
    Biology,
    James Madison University, Harrisonburg, Virginia
  • J. K. Wilburn
    Integrated Science & Technology,
    James Madison University, Harrisonburg, Virginia
  • K. S. Bower
    The Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland
  • R. K. Sia
    Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, Dist. of Columbia
  • D. S. Ryan
    Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, Dist. of Columbia
  • K. Seifert
    Biology,
    James Madison University, Harrisonburg, Virginia
  • G. W. Laurie
    Cell Biology, University of Virginia, Charlottesville, Virginia
  • Footnotes
    Commercial Relationships  Robert L. McKown, EyeRx Research, Inc. (F), Office of Tech Transfer, JMU (P); N. Gandia, None; J. K. Wilburn, None; K. S. Bower, None; R. K. Sia, None; D. S. Ryan, None; K. Seifert, None; G. W. Laurie, EyeRx Research, Inc. (F), UVa Patent Foundation (P)
  • Footnotes
    Support  This research was supported by grant funding from Virginia’s Commonwealth Health Research Board (KS and RLM). NIH RO1 EY013143 and NIH RO1 EY0 18222 (RLM and GWL). NIH R42 EY015376 (RLM).
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 3713. doi:
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      Robert L. McKown, N. Gandia, J. K. Wilburn, K. S. Bower, R. K. Sia, D. S. Ryan, K. Seifert, G. W. Laurie; Lack of Diurnal Variation of the Human Tear Protein Lacritin in Healthy Adults. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3713.

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Abstract

Purpose: : Lacritin is a human tear protein that is prosecretory, mitogenic, antimicrobial and promotes sustained basal tearing in rabbits (Samudre, et al., IVOS, 2010). Mass spec studies have shown that lacritin is selectively downregulated in blepharitis and dry eye patients. Several tear proteins such as lysozyme and angiostatin exhibit diurnal variations in normal individuals. Here we ask if lacritin levels in tear samples from healthy adults are subject to variations during the diurnal cycle.

Methods: : Tears were collected from the lower cul-de-sac from 100 healthy individuals using a polyester fiber rod (Transorb Wick, Filtrona, Richmond, VA). Single tear samples were collected at random times from 66 healthy subjects ranging in age from 21-52. Multiple samples were collected from 34 individuals ages 24-52 for the diurnal study at time 0, (7:30-8:30 am), 4 hr (11:30 am-12:30 pm), 8 hr (4:30 pm-5:30 pm), and 24 hr (7:30 am-8:30 am the following day). Rabbit antiserum made against lacritin was used in a direct ELISA to quantitate lacritin present in the tear samples.

Results: : The amount of lacritin present in tears from healthy individuals (n=66) was ~ 4.5% with no significant difference in age groups. Preliminary results from the diurnal study (n=34) suggest that there is no significant difference in the amount of lacritin in tears collected at various time points during normal daylight hours (7:30 am-5:30 pm), with average values from the time points between 4-5%.

Conclusions: : Immunoanalysis suggest that human lacritin comprises approximately 4-5% of total tear protein in healthy individuals with no significant differences between males and females. The diurnal study suggests that levels of lacritin produced in healthy individuals do not fluctuate significantly during normal daylight hours. This finding will help guide future study design in healthy and diseased individuals.

Keywords: cornea: tears/tear film/dry eye • lacrimal gland • cornea: clinical science 
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