The Origins of Salivary Vitamin A, Vitamin B12 and Vitamin D-Binding Proteins.

Matthew Blakeley,Agata Sobczyńska-Malefora,Guy Carpenter

doi:10.3390/nu12123838

Matthew Blakeley, Agata Sobczyńska-Malefora + Show 1 more

Open Access

https://doi.org/10.3390/nu12123838

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Journal: Nutrients	Publication Date: Dec 16, 2020
Citations: 5	License type: CC BY 4.0

Affiliation: King's College London, St Thomas' Hospital

Abstract

Vitamin A- (retinol), vitamin B12- (haptocorrin) and vitamin D-binding proteins are the major circulatory transporters of their respective ligands; they are also constituents of the salivary proteome, the origins of which, remain unclear. The aim of this study was to explore how these proteins enter saliva and their relationship (if any) with vitamin status. Firstly, the three vitamin-binding proteins were quantified in resting whole mouth saliva and chewing-stimulated saliva from healthy donors (n = 10) to determine if they enter the mouth by salivary secretion or from the circulation. Secondly paired whole mouth saliva and serum samples were analysed from healthy donors (n = 14) to determine the relationships between the vitamin-binding proteins and vitamin status. Salivary output of all three vitamin-binding proteins studied increased when secretion was stimulated, suggesting they are secreted by the salivary glands. Whilst retinol-binding protein and haptocorrin were secreted by all major salivary glands, vitamin D-binding protein was restricted to the mucus glands. Salivary vitamin-binding protein concentrations were not found to be indicative of systemic vitamin status.

Highlights

The proteome of whole mouth saliva (WMS) is vast, consisting of over 2000 species, and sharing approximately 27% homology to that of plasma [1,2]
This study focuses on retinol-binding protein (RBP), haptocorrin (Hc), and vitamin D-binding protein (DBP), which are present in the proteome of plasma [1]
To examine the source of the vitamin-binding proteins (VBP) in saliva, concentrations were measured in resting and chewing-stimulated saliva (Table 1). If these proteins were leaking into WMS from the serum compartment via the gingival crevicular fluid, it would not be expected for their output to increase with increasing salivary flow

Summary

Introduction

The proteome of whole mouth saliva (WMS) is vast, consisting of over 2000 species, and sharing approximately 27% homology to that of plasma [1,2]. Proteins enter saliva via a number of routes, with the majority being expressed by salivary gland acinar compartments and secreted by the exocytotic pathway [3]. Many salivary constituents are discretely expressed by the various glands, and the regulation of those glands is controlled by the extrinsic stimuli and circadian rhythm [3,6]. This complex regulation in WMS flow and composition yields a dynamic biofluid which, in health, supports the diverse functions of the oral cavity [7]

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