Quantification of MUC5AC Protein in Human Tears

Abstract

A method was established to quantify MUC5AC in human tear samples obtained on Schirmer strips. There was no correlation between the amount of MUC5AC and age or gender in the healthy population. Dry eye disease patients, however, typically showed reduced concentrations of soluble MUC5AC in the tear film.

Assay of mucins in human tear fluid

“…Previous reports that MUCs 1, 4 and 5AC are present in human tear fluid (Ellingham et al, 1997;Garcher et al, 1998;Jumblatt et al, 1999;Pflugfelder et al, 2000;Zhao et al, 2001;Argueso et al, 2002) have been corroborated by this study. This report also corroborates the presence of low levels of MUC2 in tears (McKenzie et al, 2000), with weak binding of 2 of the 3 antibodies tested on 100μg of total tear protein, an amount 10 times greater than the mid-linear range for MUC5AC detection.…”

“…The quantitative assay for mucins in tears reported in this study has several advantages over previously reported ELISA and Schirmer strip collection assays (Garcher et al, 1998;Zhao et al, 2001;Argueso et al, 2002). Garcher et al (Garcher et al, 1998) assayed tears eluted from impression cytology samples using an ELISA for the tumor marker CA19-9, which has since been identified as a marker for MUC1/Y (Akagi et al, 2001), a splice variant of MUC1 that is missing the tandem repeat domain (Zrihan-Licht et al, 1994).…”

“…The interpretation of these results is complicated by the inability to exclude mucin contamination from cells in the impression cytology samples. Two previous quantitative assays have been reported for MUC5AC in tears (Zhao et al, 2001;Argueso et al, 2002). Zhao et al (Zhao et al, 2001) presented the first quantitative analysis of MUC5AC in the human tear film with a direct immunochemical assay of MUC5AC absorbed to Schirmer strips.…”

“…Lacrimal gland epithelia have been shown to produce the small soluble secreted mucin MUC7 (Jumblatt et al, 2003), as well as MUC1, 5AC, and 5B (Paulsen et al, 2004), but it is not clear whether MUC7 and 5B are present in the tear fluid. Previous studies have demonstrated the presence of MUC1, 2, 4, and 5AC protein in human preocular tear fluid (Ellingham et al, 1997;Garcher et al, 1998;Jumblatt et al, 1999;McKenzie et al, 2000;Pflugfelder et al, 2000;Zhao et al, 2001;Argueso et al, 2002;Jumblatt et al, 2002). Most of these studies examined tears for only one mucin; six used a single antibody for detection (Garcher et al, 1998;Jumblatt et al, 1999;Zhao et al, 2001;Argueso et al, 2002;Jumblatt et al, 2002) and one used two antibodies that recognize different epitopes on the same mucin (Pflugfelder et al, 2000).…”

“…Previous studies have demonstrated the presence of MUC1, 2, 4, and 5AC protein in human preocular tear fluid (Ellingham et al, 1997;Garcher et al, 1998;Jumblatt et al, 1999;McKenzie et al, 2000;Pflugfelder et al, 2000;Zhao et al, 2001;Argueso et al, 2002;Jumblatt et al, 2002). Most of these studies examined tears for only one mucin; six used a single antibody for detection (Garcher et al, 1998;Jumblatt et al, 1999;Zhao et al, 2001;Argueso et al, 2002;Jumblatt et al, 2002) and one used two antibodies that recognize different epitopes on the same mucin (Pflugfelder et al, 2000). Two of the studies investigated more than one mucin (MUC1, MUC2, MUC5AC), using one antibody for each mucin examined (Ellingham et al, 1997;McKenzie et al, 2000).…”