Vitamin D-binding protein and multiple sclerosis: Evidence, controversies, and needs.

The vitamin D-binding protein (DBP) occupies a key node in the regulation of the vitamin D system. Being the main plasma carrier of vitamin D metabolites, it regulates their stability and bioavailability. However, DBP is also a multifunctional protein with roles in the organism's actin scavenging system and immunomodulation. All these activities may affect multiple sclerosis (MS) pathophysiology. DBP can be measured in blood and cerebrospinal fluid, body fluids that have been investigated as sources of accessible biomarkers of MS. Yet, available data on DBP expression and function in MS are scattered and somewhat controversial. Aims of this review are to summarize current evidence from studies on DBP in MS patients, to discuss possible shortcomings and to highlight key points that need to be addressed to gain deeper insight into the role of DBP in MS.