IFN-β-mediated immunomodulatory functions may differentially operate depending on the responding cell subset acting on T- or B-cell proliferation, find more modulation of cytokine production, and regulation of adhesion molecules involved in lymphocyte migration across the blood-brain barrier [18]. For these reasons, investigating the action of IFN-β therapy on B cells might be of great relevance to understand

their pathogenic role in the development and regulation of autoimmune inflammatory response in MS. There is increasing recognition that TLRs and TLR-driven responses can play a key role in the pathogenesis of several autoimmune diseases, including MS. TLR7 and TLR9 are selectively expressed by B cells, and when activated by specific ligands, lead to their proliferation and differentiation into Ig-secreting cells. Given the key importance of B lymphocytes in MS disease, we investigated whether IFN-β therapy would modulate Ig synthesis in MS patients by performing a longitudinal study conducted with unseparated PBMCs isolated from 15 Lenvatinib molecular weight MS patients before (T0) and

1 month after (T1) the beginning of IFN-β therapy. Moreover, PBMCs isolated from 10 healthy donors (HDs) were also included in this study as comparative control. To this end, PBMCs were cultured in vitro with either a specific TLR7 (the synthetic small molecule

3M001) or TLR9 (a type B CpG, 2006) agonist for 7 days and then IgM (Fig. 1A) and IgG production were Terminal deoxynucleotidyl transferase evaluated by Elispot (Fig. 1B) and Elisa assay (Supporting Information Fig. 1). The TLR9-mediated B-cell stimulation led to a similar frequency of IgM- and IgG-secreting cells in both HD- and MS-affected individuals and this Ab release was not modified in response to IFN-β treatment. On the other hand, it was very interesting to find that the basal level of TLR7-induced Ig production was significantly lower in MS patients as compared with that in HD, showing a specific defect in TLR7 responses in B cells from MS sufferers. Surprisingly, 1 month of IFN-β therapy was able to partially restore this deficiency and selectively increase the production of IgM and IgG upon TLR7 triggering, re-establishing the level of Ab release found in HDs. The analysis of Ig content by Elisa confirmed the results obtained by Elispot assay (Supporting Information Fig. 1). IFN-β-mediated effect was long-lasting since it was still observed after 6 months of IFN-β treatment (data not shown). However, IFN-β did not enhance auto-Ab production as demonstrated by measurement of both homogeneous and speckled patterns of anti-ANA Abs on sera of MS patients before and after therapy (data not shown) [19].