Morpholino Analogues of Fingolimod as Novel and Selective S1P1 Ligands with In Vivo Efficacy in a Mouse Model of Experimental Antigen-Induced Encephalomyelitis

Abstract

Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune disease of the central nervous system (CNS) which is associated with lower life expectancy and disability. The experimental antigen-induced encephalomyelitis (EAE) in mice is a useful animal model of MS, which allows exploring the etiopathogenetic mechanisms and testing novel potential therapeutic drugs. A new therapeutic paradigm for the treatment of MS was introduced in 2010 through the sphingosine 1-phosphate (S1P) analogue fingolimod (FTY720, Gilenya®), which acts as a functional S1P1 antagonist on T lymphocytes to deplete these cells from the blood. In this study, we synthesized two novel structures, ST-1893 and ST-1894, which are derived from fingolimod and chemically feature a morpholine ring in the polar head group. These compounds showed a selective S1P1 activation profile and a sustained S1P1 internalization in cultures of S1P1-overexpressing Chinese hamster ovary (CHO)-K1 cells, consistent with a functional antagonism. In vivo, both compounds induced a profound lymphopenia in mice. Finally, these substances showed efficacy in the EAE model, where they reduced clinical symptoms of the disease, and, on the molecular level, they reduced the T-cell infiltration and several inflammatory mediators in the brain and spinal cord. In summary, these data suggest that S1P1-selective compounds may have an advantage over fingolimod and siponimod, not only in MS but also in other autoimmune diseases.

ST-2191, an Anellated Bismorpholino Derivative of Oxy-Fingolimod, Shows Selective S1P1 Agonist and Functional Antagonist Potency In Vitro and In Vivo

“…ST-2191 (9a-(4-(heptyloxy)phenethyl)hexahydro-1 H ,3 H -[1,4]oxazino [3,4- c ][1,4]oxazine) is structurally related to the previously reported S1P 1 selective modulator ST-1894 ( Figure 1 ) [ 18 ]. Both can be synthesized using the oxy-analogue of fingolimod [ 19 ] as a precursor ( Supplementary File ).…”

“…ST-2191 can be synthesized in an analogous route to that of ST-1894, a previously reported S1P 1 receptor modulator with a morpholino moiety ( Figure 1 ) [ 18 ]. Furthermore, ST-2191, which is an anellated bismorpholino derivative by the formal condensation of two morpholine rings, i.e., perhydro[1,4]oxazino[3,4-c][1,4]oxazine derivative of oxy-fingolimod, strongly resembles the oxazolo-oxazolo derivative ST-1071 [ 20 ], but contains a larger polar head group.…”

“…Previously, we developed two morpholino analogues of fingolimod (ST-1893 and ST-1894), which showed a selective S1P 1 activation profile and sustained S1P 1 internalization consistent with a functional antagonism. Both compounds induced profound lymphopenia in mice and were efficacious in the experimental autoimmune encephalomyelitis model of multiple sclerosis [ 18 ]. Here, we report on two novel compounds, ST-2191, which is an anellated bismorpholino derivative of oxy-fingolimod, and ST-2192, which is a fusion of two oxy-analogues of fingolimod by a N , N ’-dimethylene bridge.…”

The immune regulatory effects of tetrahedral framework nucleic acid on human T cells via the mitogen‐activated protein kinase pathway

“…It is well documented that those irregular provoked T cells also associated with cytokine and chemokine cascades, which might cause target organ damages, as well as disease progression and poor prognosis of patients 2 . Clinically, other than biological therapy, mounts of small‐molecular drugs are currently used in preventing and eliminating T cell–mediated autoimmune responses, including cell proliferation inhibitor cyclosporine A (CsA), IMPDH inhibitor mycophenolate mofetil, and lymphocyte homing inhibitor fingolimod 3‐5 . Nevertheless, the above‐mentioned immunosuppressive strategies exhibit a less selective manner and are often found to break the homeostasis of the host immune system 6 .…”

“… 2 Clinically, other than biological therapy, mounts of small‐molecular drugs are currently used in preventing and eliminating T cell–mediated autoimmune responses, including cell proliferation inhibitor cyclosporine A (CsA), IMPDH inhibitor mycophenolate mofetil, and lymphocyte homing inhibitor fingolimod. 3 , 4 , 5 Nevertheless, the above‐mentioned immunosuppressive strategies exhibit a less selective manner and are often found to break the homeostasis of the host immune system. 6 Therefore, it is urgent to develop an efficient way not only decreases specific immune response induced by autoreactive T cells, but also protects regular host immune responses.…”