Therapeutic Potential of Ponesimod Alone and in Combination with Dimethyl Fumarate in Experimental Models of Multiple Sclerosis.

Background: Despite the recent approval of new oral therapies for the treatment of multiple sclerosis (MS), a significant percentage of patients are still not free from disease activity. In view of the complex pathogenesis and the relapsing and progressive nature of MS, combination therapy, a classical approach to treat many chronic diseases, could improve disease control over monotherapy. Ponesimod, a selective and rapidly reversible sphingosine-1-phosphate receptor Type 1 (S1P1) modulator, currently in Phase III clinical trial stage in relapsing MS (RMS), and dimethyl fumarate (DMF) would potentially be an ideal combination due to their differing mechanisms of action and oral administration. Objective: The goal of the study was to evaluate the therapeutic effect of ponesimod monotherapy and investigate the potential additive, or synergistic, activity of ponesimod-DMF combination therapy in experimental autoimmune encephalomyelitis (EAE) animal models of MS. Methods: Efficacy was evaluated in the myelin oligodendrocyte glycoprotein (MOG)-induced EAE model in C57BL/6 mice (ponesimod monotherapy) and in the myelin basic protein (MBP)-induced EAE model in Lewis rats (monotherapies and combination therapy). The principal readout was the clinical score assessing paralysis. Additional readouts, such as histopathology, survival, and disease prevalence, were generated in parallel when applicable. Results: Ponesimod monotherapy in the mouse EAE model showed significant efficacy in both preventative and therapeutic settings. In the rat EAE model, ponesimod demonstrated significant dose-dependent efficacy on clinical scores, while DMF showed only modest activity. Combination therapy synergistically reduced the severity and prevalence of disease. Only the combination treatment of ponesimod and DMF fully suppressed clinical disease activity by the end of the study. Conclusion: The results support the potential therapeutic benefits of combining ponesimod with DMF to improve disease activity control in patients with MS. Additionally, the results suggest that combining ponesimod with other oral agents that have different mechanisms of action might also be therapeutically beneficial to patients with MS.

Essential role for CCR6 in certain inflammatory diseases demonstrated using specific antagonist and knockin mice.

The chemokine receptor CCR6 marks subsets of T cells and innate lymphoid cells that produce IL-17 and IL-22, and as such may play a role in the recruitment of these cells to certain inflammatory sites. However, the precise role of CCR6 has been controversial, in part because no effective monoclonal antibody (mAb) inhibitors against this receptor exist for use in mouse models of inflammation. We circumvented this problem using transgenic mice expressing human CCR6 (hCCR6) under control of its native promoter (hCCR6-Tg/mCCR6-/-). We also developed a fully humanized mAb against hCCR6 with antagonistic activity. The expression pattern of hCCR6 in hCCR6-Tg/mCCR6-/- mice was consistent with the pattern observed in humans. In mouse models of experimental autoimmune encephalomyelitis (EAE) and psoriasis, treatment with anti-hCCR6 mAb was remarkably effective in both preventive and therapeutic regimens. For instance, in the imiquimod model of psoriasis, anti-CCR6 completely abolished all signs of inflammation. Moreover, anti-hCCR6 attenuated clinical symptoms of myelin oligodendrocyte glycoprotein-induced (MOG-induced) EAE and reduced infiltration of inflammatory cells in the central nervous system. CCR6 plays a critical role in Th17 type inflammatory reactions, and CCR6 inhibition may offer an alternative approach for the treatment of these lesions.

Amnion cell-mediated immune modulation following bleomycin challenge: controlling the regulatory T cell response.

INTRODUCTION: The immunomodulatory properties of human amnion epithelial cells (hAECs) have been previously described in several disease models. We previously reported on the ability of hAECs to influence macrophage phenotype and chemotaxis. In this study, we aim to elucidate the contribution of regulatory T cells (Tregs) to macrophage polarisation and downstream effects on inflammation and fibrosis in a bleomycin model of lung injury. METHODS: Either CD45(+)/FoxP3(+) Tregs or CD45(+)/FoxP3 (-) non-Tregs were adoptively transferred into Rag1 (-/-) mice immediately prior to bleomycin challenge. Four million hAECs were administered 24 hours later. Outcomes were measured 7 or 14 days later. RESULTS: Mitigation of lung inflammation and fibrosis was observed only in animals that received both hAECs and Tregs. hAEC treatment also induced the maturation of non-Tregs into FoxP3-expressing Tregs. This event was found to be transforming growth factor-beta (TGFß)-dependent. Furthermore, polarisation of macrophages from M1 to M2 occurred only in animals that received hAECs and Tregs. CONCLUSIONS: This study provides the first evidence that Tregs are required for hAEC-mediated macrophage polarisation and consequential mitigation of bleomycin-induced lung injury. Uncovering the interactions between hAECs, macrophages, and T-cell subsets is central to understanding the mechanisms by which hAECs elicit lung repair.