Therapeutic use of pantethine in experimental autoimmune encephalomyelitis

Pantethine is a low molecular weight thiol and represents the stable disulfate form of pantetheine, the metabolic substrate constituting the active part of coenzyme A (CoA). For decades, pantethine has been administrated to patients with metabolic disorders for its lipid lowering activity, without any side effect reported. Recent data showed that pantethine prevents the occurrence of cerebral malaria, with the down-regulation of key cellular responses to the inflammatory cerebral syndrome. Immunometabolism represents a new frontier in immunology and the aim of this study was to investigate the effect of metabolic intervention with pantethine on experimental autoimmune encephalomyelitis (EAE), the animal model of human multiple sclerosis (MS). Our in vivo experiments demonstrated that pantethine treatment prevents the development of chronic and relapsing-remitting EAE by delaying the disease onset and reducing the clinical score. Furthermore, pantethine treatment started after disease onset significantly ameliorated disease course and severity. The surprising clinical results were accompanied by a decrease in inflammatory infiltrates and in demyelination in pantethine treated-mice, proved by our neuropathological studies. Moreover, using IVIS 200 system we found that pantethine treated-mice had a reduced BBB leakage during the pre-clinical phase of relapsing-remitting EAE. Importantly, T-cells isolated from draining lymph nodes of mice treated with pantethine showed a significant reduction in antigen-specific proliferation and pro-inflammatory cytokines production at disease peak when compared with untreated-mice. Furthermore, our data from in vitro experiments demonstrated that pantethine pre-treatment of encephalitogenic T-cells blocked T-cell adhesion on purified integrin ligands. In addition, pantethine inhibited activated T-cell adhesion in vivo using an intravital microscopy model performed in inflamed brain venules. Importantly, pantethine had no effect on chemokine-induced naïve T-cell adhesion, proving that pantethine treatment has a selective effect only on activated T-cells. On the other hand, ImageStream analysis show that the important inhibition of proteolipid-specific T-cells adhesion could not be explain by changes on integrin expression or on their ability to form clusters upon chemokine-induce activation. Integrin functionality does not depend only on their avidity for their ligands but also on its localization into cholesterol-rich membrane rafts on cell surface. Thus, we next investigated the role of pantethine treatment on lipid rafts conformation on activated T-cells. Surprisingly, our in vitro experiments demonstrated that pantethine pre-treatment strongly reduced lipid rafts formation and raft clusters on encephalitogenic T-cells, although integrins were still present in big polarized caps. These results suggest that pantethine dissolve lipid rafts on activated T-cell, possibly interfering with the signal transduction necessary to support integrin-dependent firm adhesion. To further understand pantethine effect on in T-cell functions, we performed metabolomics analysis on pantethine-treated activated T-cells. Our data suggested a global metabolic effect of pantethine on T-cells. Overall, pantethine treatment significantly and differently affected the metabolism of memory T lymphocytes with respect to naïve T lymphocytes, leading to the modulation of at least 45 metabolic pathways with a huge availability of CoA that greatly enhances the Krebs cycle efficiency. These final consideration made us believe that pantethine could be able to perform a fine metabolic tuning of the pathogenic T-cells involved in demyelinating diseases, as MS. In conclusion, our results demonstrate that pantethine has an immuno-modulatory effect on EAE by reducing T-cell activation and adhesiveness, and maintaining BBB integrity. As pantethine has a low-cost and has successfully administered in different context to man in the absence of side effects, our results suggest that this low molecular weight thiol may represent a valuable new therapeutic approach in MS.