Vitamin D-binding Protein in Cerebrospinal Fluid is Associated with Multiple Sclerosis Progression

Abstract

Multiple sclerosis is a neurological disorder that presents with symptoms including inflammation, neurodegeneration, and demyelination of the central nervous system (CNS). Secondary progressive multiple sclerosis (SPMS) manifests with serious physical disability. To quantitatively analyze differential protein expression in patients with SPMS, we performed two-dimensional fluorescence difference in-gel electrophoresis, followed by mass spectrometry on the cerebrospinal fluid of these patients and patients with other neurological diseases. Vitamin D-binding protein (DBP), gelsolin, albumin, etc. showed more than a 1.5-fold difference between the two groups. Based on these results, an experimental allergic encephalomyelitis (EAE) model of multiple sclerosis in Lewis rats was used to investigate DBP's role in the disease. Protein levels, mRNA transcripts, and ligands of DBP in different regions of the CNS were evaluated under various vitamin D intake levels. Here, DBP levels increased in the experimental rat groups compared to the control groups regardless of vitamin D intake. Moreover, DBP mRNA levels varied in different parts of the CNS including spinal cords in the experimental groups. The observed differences between DBP protein and mRNA levels in the experimental groups' spinal cords could be derived from the disruption of the blood-brain barrier. Furthermore, an interaction between DBP and actin was confirmed using coimmunoprecipitation and western blot. These results indicate a role for DBP in the actin scavenge system. Moreover, in the experimental group that received oral vitamin D3 supplement, we observed both delayed onset and diminished severity of the disease. When DBP was upregulated, however, the benefits from the vitamin D3 supplements were lost. Thus, we inferred that high levels of DBP were adverse to recovery. In conclusion, here we observed upregulated DBP in the cerebrospinal fluid could serve as a specific diagnostic biomarker for the progression of multiple sclerosis. Next, we demonstrate the vital function of increased levels of free vitamin D metabolites for multiple sclerosis treatment. Finally, vitamin D supplements may be particularly beneficial for SPMS patients.

Overexpression of GSN could decrease inflammation and apoptosis in EAE and may enhance vitamin D therapy on EAE/MS

“…pGSN can scavenge pro-inflammatory signals, such as actin and lipopolysaccharidet, to ameliorate deleterious inflammatory response, while cGSN has been implicated in numerous biological processes, including cell motility, apoptosis, and phagocytosis 47 . In previous studies, we observed a > 1.5-fold decrease of pGSN in MS and OND patients by using 2-D DIGE 39, 46 , and in current research we confirmed the results by Western blotting. In EAE (the rat model of MS), a decrease of pGSN in the serum was also found in this study.…”

“…Experiments in animal models found that mice have an increased susceptibility to EAE when they were fed a vitamin D-deficient diet, while administration of 1,25-(OH) 2 D 3 in mice could slow the progression of EAE 54 . Our research in rats also achieved the same results 22, 39 . This suggests that vitamin D intake could remit the process of EAE, but cannot prevent it.…”

“…An epidemiological survey has found that there is a close correlation between the incidence of MS and light 34 , and since light is the catalyst of vitamin D synthesis in body, people presume that light affects the levels of vitamin D and thus, affects the incidence of MS 35 . Subsequent experiments present that 25- (OH) 2 D 3 level in MS patients is significantly lower than normal 36, 37 , and animal experiments in EAE prove that dietary supplement of vitamin D during the acute stage of EAE can effectively delay the onset time and alleviate the symptoms, but cannot prevent the development of EAE completely 38 (our previous animal experiments also got the same results 39, 22 ).…”

“…The results suggest that pGSN is more than 1.5-fold downregulated in the CSF of MS patients 39, 46 . In order to confirm the findings, we detected the concentration of pGSN in the CSF and serum from 4 MS and OND patients.…”

Behind the scenes of vitamin D binding protein: More than vitamin D binding

“…In patients with multiple sclerosis, two-dimensional fluorescence difference in-gel electrophoresis followed by mass spectrometry has shown that the determination of DBP in cerebrospinal fluid could serve as a specific diagnostic biomarker of progressive disease [45]. In addition, proteomics studies have reported decreased DBP levels in cerebrospinal fluid in patients with relapsing-remitting multiple sclerosis in comparison with subjects with other neurological diseases [46].…”