TFF peptides and mucins are major components of dacryoliths
The study was performed to determine whether trefoil factor peptides (TFF) and/or mucins are components of dacryoliths and to gain further insight into dacryolith composition and formation.
Twenty dacryoliths found in lacrimal surgery in patients suffering from primary acquired nasolacrimal duct obstruction were analyzed for the presence of TFF peptides (TFF1, 2, 3), mucins (MUC1, 2, 3, 4, 5AC, 5B, 6, 7, 8), defense cells (T- and B lymphocytes, macrophages, neutrophils), and antimicrobial substances (alpha defensins 1-3, secretory phospholipase A2) by means of light microscopy, histochemistry, immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR.
All dacryoliths except one revealed clear immunoreactivity for all three TFF peptides. The immunohistochemical distribution of mucins was inhomogeneous throughout the different dacryoliths. However, in some dacryoliths all mucins investigated were detected. MUC8 showed reactivity in 14 out of 15 dacryoliths analyzed by immunohistochemistry. Most dacryoliths contained alpha defensins 1-3 as the secretory product of neutrophils. T and B lymphocytes, macrophages and secretory phospholipase A2 were only present in single dacryoliths. Quantification of TFF peptide expression supported the immunohistochemical finding that all three TFF peptides are augmented in dacryoliths.
Dacryoliths consist partly of secreted mucins comparable with the mucin spectrum of the epithelium of healthy nasolacrimal ducts. Beside TFF1 and TFF3, both of which are produced under healthy circumstances, TFF2 is additionally induced and secreted in cases of dacryolithiasis. All three TFF peptides appear to be augmented in dacryoliths. With regard to their rheologic properties, TFF peptides may play a functional role in dacryolith formation. However, our results raise the question of whether TFF peptides per se influence dacryolith formation or whether their secretion, as in secretion of mucins and alpha defensins 1-3, is merely a secondary phenomenon.
KeywordsNasolacrimal ducts Mucin Trefoil Dacryolith Dacryostenosis
This work was supported by the Deutsche Forschungsgemeinschaft (German Research Foundation) - program grant PA 738/1-5 and Wilhelm-Roux-program grants FKZ 9/18 and FKZ 12/08. The authors thank Karin Stengel and Michaela Risch for their excellent technical assistance; Ingemar Carlstedt, University of Lund, Sweden, for LUM5B-2, LUM6-3, and LUM7-1; Michael McGuckin, University of Queensland, Australia, for BC2 and David Thornton, University of Manchester, UK, for 5B III, Werner Hoffmann, Institute of Molecular Biology and Medical Chemistry, Otto von Guericke University, Magdeburg, Germany, for anti-hTFF2-1, anti-hTFF3-2 and anti-rTFF3-1.
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