ObjectiveTo investigate in a cross-sectional study the effect of serum-derived exosomes on primary human blood monocyte-derived macrophages (MDMs) comparing exosomes from healthy donors vs patients with relapsing-remitting multiple sclerosis in remission and in relapse and to assess whether the response correlates with exosomal Epstein-Barr virus (EBV) protein expression.MethodsA total of 45 serum-derived exosome preparations were isolated from patients and healthy controls and verified for the expression of exosomal and EBV markers. MDMs were differentiated from monocytes for 7 days and incubated for 24 hours with exosomes, and then, cell supernatants were collected for cytokine measurement by cytometric bead array. Cells were immunophenotyped before and after differentiation.ResultsSerum-derived exosomes of patients with multiple sclerosis (MS) expressed higher levels of EBV proteins than healthy controls. Of interest, expression of EBV nuclear antigen EBNA1 and latent membrane proteins LMP1 and 2A was higher on exosomes derived from patients with active RRMS compared with healthy controls and stable patients. After data normalization, we observed that incubation with EBV(+) exosomes induced CXCL10 and CCL2 secretion by MDMs. MDMs differentiated from patients with active disease were better secretors of CXCL10 and other interferon-γ–inducible chemokines, including CCL2 and CXCL9, than MDMs from healthy and stable MS groups. MDMs from active patients had a higher frequency of a CD14(++) subset that correlated with the secreted CXCL10.ConclusionExosomes expressing EBV proteins correlate with disease activity and induce an inflammatory response in MDMs that is compounded by the origin of the responder cells.

Bioactive vitamin D is a steroid hormone transported in blood via the vitamin D binding protein (DBP). Our study aimed to investigate the vitamin D status in a young Lebanese population and study the association of hypovitaminosis with levels of DBP. Polymorphisms in the GC gene that encodes DBP were also screened. Blood samples were collected from 179 university students. Vitamin D status and DBP levels were assayed by enzyme-linked immunosorbent assay (ELISA). DNA was extracted from 128 participants, and genotyping of the two GC gene SNPs, rs7041, and rs4588, was carried out by restriction fragment length polymorphism. Forty-seven percent of participants had hypovitaminosis D (<20 ng/ml). A significant positive correlation was observed between vitamin D status and DBP. Genotyping data showed that participants carrying the rs7041 GG and rs4588 AA genotypes had higher concentrations of DBP than those carrying other genotypes. Four allelic versions of the GC gene were observed, one of which, GC*3, was encountered for the first time in this study, and was found to be associated with both normal vitamin D and high DBP levels. Modifying genes such as GC could therefore affect DBP levels, and contribute, along with environmental factors, to the hypovitaminosis D observed in sunny countries.