Vitamin D Binding Protein a Potential Biomarker in MS

Lower blood levels of vitamin D binding protein, known as VDBP, were observed in newly diagnosed multiple sclerosis (MS) patients in a new study — findings that suggest the protein could potentially act as a biomarker for the neurodegenerative disease.

“The present study revealed an independent association between lower … levels of VDBP and the risk of MS,” the researchers wrote. However, the team said further studies are needed to confirm their findings.

The study, “Reduction in circulating vitamin D binding protein in patients with multiple sclerosis,” was published in BMC Neurology.

Genetic and environmental risk factors are associated with MS. One such risk factor is the blood level of vitamin D, which is involved in the secretion of anti-inflammatory factors. 

VDBP is a protein that binds and transports metabolized vitamin D to prevent vitamin D deficiency.

“Because VDBP is the key determinant of vitamin D, it can efficiently affect the sustainability, biocompatibility, and biological performance of vitamin D,” the researchers wrote.

Previous studies showed inconsistent results regarding a possible association between vitamin D binding protein and MS prevalence and disease progression.

Thus, a team of researchers at the Tehran University of Medical Sciences, in Iran, investigated the relationship between MS risk and VDBP levels in recently diagnosed MS patients — those with a diagnosis within the previous year — to determine if the protein could act as a disease biomarker.

A total of 609 study participants were recruited between March 2018 and February 2020. Altogether, there were 296 MS patients (79.1% female, mean age of 33.1) and 313 healthy people (58.8% female, mean age of 35.1) who served as controls. 

Two common VDBP gene variations — called rs7041 and rs4588 — were assessed and found to occur at similar frequencies in the MS and control groups.

Then, researchers further analyzed a subgroup of participants that included 77 MS patients diagnosed one year before the study’s start, and 67 healthy people who were matched in terms of age and sex.

More than half (54.5%) of the MS patients in the subgroup analysis reported taking regular vitamin D supplements as compared with only 18% of the controls. Unsurprisingly, the mean blood level of vitamin D was higher in these MS patients (33.6 nanograms/ml) than in the controls (21.6 nanograms/ml).

Notably, the mean level of circulating VDBP was significantly lower in MS patients (3.64 micrograms (mcg)/ml) than in controls (5.31 mcg/ml), even after adjusting for the participants’ vitamin D levels, body mass index (a measure of body fat based on height and weight), and vitamin D supplement use. 

No association between VDBP and vitamin D levels was observed in either group. Moreover, VDBP levels were not significantly different in MS patients receiving MS-specific treatment compared with non-treated individuals.

“In conclusion, we identified no risk association between common genetic variants of VDBP and MS,” the researcher wrote, adding, however, that the data suggest “an association between lower levels of circulating VDBP and multiple sclerosis in newly diagnosed patients.”

The team emphasized that their study was limited by its observational design and short-term nature.

“Further works are needed to establish whether VDBP could be known as a biomarker at early stages of MS,” the researchers said, noting that the “VDBP causative role in the development of MS is still unclear.”