Different Forms of TFF3 in the Human Saliva: Heterodimerization with IgG Fc Binding Protein (FCGBP).

Till Houben,Harmut Schlüter,Sönke Harder,Werner Hoffmann,Hubert Kalbacher

doi:10.3390/ijms20205000

Abstract

The peptide TFF3 is a member of a family of secretory lectins, and is typically synthesized by mucous epithelia together with mucins. It is mainly released from intestinal goblet cells as a high-molecular mass heterodimer with IgG Fc binding protein (FCGBP). Herein, we investigated human saliva by fast protein liquid chromatography (FPLC) and proteomics and identified high- and low-molecular-mass forms of TFF3. Whereas the high-molecular-mass forms represent a heterodimer with FCGBP, the low-molecular-mass forms represent homodimeric TFF3 forms. Proteomic analysis also revealed a C-terminally truncated form of TFF3. We hypothesize that salivary TFF3-FCGBP might play a role in the innate immune defense of the oral cavity and that TFF3 might also bind to microbial glycans. The known interaction of TFF3 with the agglutinin DMBT-1, a typical constituent of human saliva, further supports this protective role.

Highlights

The oral cavity is the entrance for food, and a variety of microorganisms
When human saliva was separated by size exclusion chromatography (SEC), TFF3 immunoreactivity appeared in both a high- and low-molecular-mass range (Figure 1)
We show for the first time that TFF3 in human saliva appears in both high- and low-molecular-mass forms

Summary

Introduction

The oral cavity is the entrance for food, and a variety of microorganisms. It is protected by the oral epithelial immune barrier [1]. The initial steps of alimentation are greatly facilitated by saliva. This fluid shows major individual differences and is secreted by three pairs of major glands (i.e., sublingual, submandibular, and parotid glands) and various minor glands (e.g., labial and palatal glands). Saliva fulfills a key role for the protection of teeth and the oral cavity, and is part of the first steps of digestion [2,3,4,5]. The major protective functions of saliva focus on both the defense against microorganisms and the support of healing processes in the oral epithelium

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Conclusion