Coenzyme A fueling with pantethine limits autoreactive T cell pathogenicity in experimental neuroinflammation.

BACKGROUND: Immune cell metabolism governs the outcome of immune responses and contributes to the development of autoimmunity by controlling lymphocyte pathogenic potential. In this study, we evaluated the metabolic profile of myelin-specific murine encephalitogenic T cells, to identify novel therapeutic targets for autoimmune neuroinflammation. METHODS: We performed metabolomics analysis on actively-proliferating encephalitogenic T cells to study their overall metabolic profile in comparison to resting T cells. Metabolomics, phosphoproteomics, in vitro functional assays, and in vivo studies in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis (MS), were then implemented to evaluate the effect of metabolic targeting on autoreactive T cell pathogenicity. Finally, we confirmed the translational potential of our targeting approach in human pro-inflammatory T helper cell subsets and in T cells from MS patients. RESULTS: We found that autoreactive encephalitogenic T cells display an altered coenzyme A (CoA) synthesis pathway, compared to resting T cells. CoA fueling with the CoA precursor pantethine (PTTH) affected essential immune-related processes of myelin-specific T cells, such as cell proliferation, cytokine production, and cell adhesion, both in vitro and in vivo. Accordingly, pre-clinical treatment with PTTH before disease onset inhibited the development of EAE by limiting T cell pro-inflammatory potential in vivo. Importantly, PTTH also significantly ameliorated the disease course when administered after disease onset in a therapeutic setting. Finally, PTTH reduced pro-inflammatory cytokine production by human T helper 1 (Th1) and Th17 cells and by T cells from MS patients, confirming its translational potential. CONCLUSION: Our data demonstrate that CoA fueling with PTTH in pro-inflammatory and autoreactive T cells may represent a novel therapeutic approach for the treatment of autoimmune neuroinflammation.

Inverse agonism of cannabinoid CB1 receptor blocks the adhesion of encephalitogenic T cells in inflamed brain venules by a protein kinase A-dependent mechanism.

It is well known that the cannabinoid system has a significant role in the regulation of the immune responses. Cannabinoid receptors CB1 and CB2 are expressed on T lymphocytes and mediate the immunomodulatory effects of cannabinoids on T cell functions. Here we show that the treatment of proteolipid protein (PLP)139-151-specific T cells with SR141716A, a CB1 inverse agonist and prototype of the diarylpyrazoles series, induced a strong inhibition of firm adhesion in inflamed brain venules in intravital microscopy experiments. In contrast, SR144528, a potent CB2 inverse agonist, had no significant effect on both rolling and arrest of activated T cells. In addition, two analogs of SR141716A and CB1 inverse agonists, AM251 and AM281 inhibited encephalitogenic T cell adhesion suggesting that selective CB1 inverse agonism interfere with lymphocyte trafficking in the CNS. Flow cytometry experiments showed that CB1 inverse agonists have no effect on adhesion molecule expression suggesting that CB1 blockade interferes with signal transduction pathways controlling T cell adhesion in inflamed brain venules. In addition, integrin clustering was not altered after treatment with CB1 inverse agonists suggesting that adhesion blockade is not due to the modulation of integrin valency. Notably, the inhibitory effect exerted by AM251 and AM281 on the adhesive interactions was completely reverted in the presence of protein kinase A (PKA) inhibitor H89, suggesting that cAMP and PKA activation play a key role in the adhesion blockade mediated by CB1 inverse agonists. To further strengthen these results and unveil a previously unknown inhibitory role of cAMP on activated T cell adhesion in vivo in the context of CNS inflammation, we showed that intracellular increase of cAMP induced by treatment with Bt2cAMP, a permeable analog of cAMP, and phosphodiesterase (PDE) inhibitor theophylline efficiently blocked the arrest of encephalitogenic T cells in inflamed brain venules. Our data show that modulation of CB1 function has anti-inflammatory effects and suggests that inverse agonism of CB1 block signal transduction mechanisms controlling encephalitogenic T cells adhesion in inflamed brain venules by a PKA-dependent mechanism.