**7. Prophylactic effect of VitD on EAE**

Prophylactic strategies in EAE, and also in other autoimmune pathologies, are based in the concept of "inverse vaccination." This procedure refers to the use of an immunization protocol that, differently from classical vaccination, aims to achieve an antigen‐specific tolerogenic state [120]. Even though the term "inverse vaccination" could also be used as a therapeutical strategy, in this text we applied it only in the context of prophylactic vaccination. The majority of the prophylactic strategies in EAE have been done by administration of a diversity of MOG formulations delivered by distinct routes. A few examples of these procedures and the main histological and immunological findings are illustrated in **Table 1**.

The prophylactic potential of VitD (or analogs) alone or associated with other pharmaceuti‐ cals has been tested in EAE. The adopted experimental protocols are not standardized and therefore, different amounts of VitD are administered by distinct routes. Time periods chosen for VitD administration in relation to EAE induction are also variable and some procedures consist in prolonged administration periods, even reaching the disease clinical phase. However, a general consensus is that VitD is able to improve clinical disease mani‐ festation and also to trigger evident effects on the CNS and the immune system. Some of the effects observed in mice with EAE that were previously injected with VitD are exempli‐ fied in **Table 2**.


**Table 1.** MOG prophylactic procedures in EAE.

with reduced production of IL‐6 and IL‐17 by spleen and CNS cell cultures stimulated with MOG, reduced splenic DC maturation, and also a striking decline in CNS inflammation

**Figure 2.** MOG + active vitamin D3 association strategy for EAE prophylaxis and treatment. C57BL/6 mice were vacci‐ nated or treated with this association and the effect on EAE was evaluated in the acute EAE phase. Both strategies de‐ creased production of inflammatory cytokines by CNS mononuclear cells, frequency of CD4+CD25+Foxp3+ Treg cells,

Prophylactic strategies in EAE, and also in other autoimmune pathologies, are based in the concept of "inverse vaccination." This procedure refers to the use of an immunization protocol that, differently from classical vaccination, aims to achieve an antigen‐specific tolerogenic state [120]. Even though the term "inverse vaccination" could also be used as a therapeutical strategy, in this text we applied it only in the context of prophylactic vaccination. The majority of the prophylactic strategies in EAE have been done by administration of a diversity of MOG formulations delivered by distinct routes. A few examples of these procedures and the main

The prophylactic potential of VitD (or analogs) alone or associated with other pharmaceuti‐ cals has been tested in EAE. The adopted experimental protocols are not standardized and therefore, different amounts of VitD are administered by distinct routes. Time periods chosen for VitD administration in relation to EAE induction are also variable and some procedures consist in prolonged administration periods, even reaching the disease clinical phase. However, a general consensus is that VitD is able to improve clinical disease mani‐ festation and also to trigger evident effects on the CNS and the immune system. Some of the effects observed in mice with EAE that were previously injected with VitD are exempli‐

[119] (**Figure 2**).

216 A Critical Evaluation of Vitamin D - Clinical Overview

and inflammation in the CNS.

fied in **Table 2**.

**7. Prophylactic effect of VitD on EAE**

histological and immunological findings are illustrated in **Table 1**.


**Table 2.** Vitamin D3 prophylactic procedures in EAE.

The combination of VitD with other substances as calcitonin [125], IFN‐β [126], bisphospho‐ nate [127], rapamycin [128], and cyclosporine [129] has determined cooperative effects over EAE control. We recently tested the association of VitD with MOG as a prophylactic approach to control EAE development. Again, in this procedure, we explored the concept of VitD as a tolerogenic adjuvant. This concept and its potential application to trigger self‐tolerance in autoimmune diseases were conceived by Kang et al. [130]. These authors validated this hypothesis by demonstrating that FK506 (tacrolimus) associated with MOG was prophylactic in encephalomyelitis [131]. In this context, we hypothesized that active VitD could also behave as a tolerogenic adjuvant if associated with a CNS‐specific antigen. Vaccination with MOG associated with VitD, before EAE induction in C57BL/6 female mice, determined a significant clinical improvement characterized by absence of clinical score and no body weight loss. An impressive reduction in CNS inflammation, DC maturation and also cytokine production by CNS and spleen cell cultures was detected in these vaccinated animals [132]. As described in Section 6 of this chapter, this combination of MOG with VitD was also very efficient as a therapeutic procedure in the EAE model. This prophylactic and therapeutic potential of the MOG/VitD association in EAE is illustrated in **Figure 2**. The possible use of VitD as a tolero‐ genic adjuvant in association with other self‐antigens, as a strategy to control autoimmune pathologies, warrants future investigation. In our opinion, the fact that VitD is already accepted for human supplementation will facilitate its adoption for MS treatments based on its associ‐ ation with neuronal self‐antigens.
