Abstract
Purpose:
Previously, we demonstrated that Slurp1 serves an immunomodulatory function in the ocular surface. Although Slurp1 transcripts are the 11th most abundant in the mouse cornea, it is not known if this high expression is reflected at the protein level. Also, several tear proteomic studies have not identified SLURP1, resulting in ambiguity about the baseline SLURP1 concentration in human tears. Here, we examine the mouse Slurp1 expression in different strains, age-groups, genders, and ocular surface health conditions, and quantify SLURP1 expression in human tears collected from healthy or inflamed ocular surfaces.
Methods:
Early embryonic (E) and postnatal (PN) mouse corneal Slurp1 expression was quantified using QPCR. The influence of mouse genetic background, age, and gender on Slurp1 expression was examined by QPCR and immunofluorescent staining in Balb/C, FVBN, C57Bl/6, and DBA/2J strains at PN10, PN20 and PN56. Human tears were collected from 34 adults (18-80 years) with absorbent wicks using an IRB-approved protocol, and the SLURP1 levels quantified by ELISA.
Results:
Slurp1 expression, undetectable in E13, E16, and PN1 mouse corneas and barely detectable in PN10, increased rapidly in post-eyelid opening stages levelling off around PN20. Slurp1 expression did not differ significantly between different strains, or genders. Human tear SLURP1 levels did not vary significantly between genders and age groups. However, tears from inflamed human ocular surface contained significantly decreased amounts of SLURP1 (0.35 ng/100ng tear protein) compared with those from healthy individuals (0.68 ng/100ng tear protein).
Conclusions:
These data provide the first detailed description of the influence of age, gender, and genetic background on Slurp1 expression in the mouse cornea, establish the baseline for SLURP1 concentration in human tears, and demonstrate that the tears from inflamed ocular surface contain decreased amounts of SLURP1.