NXC736, a Functional Antagonist of S1P₄, Attenuates Brain Injury in Mice with Permanent Ischemic Stroke

Stroke is the leading cause of death and long-term disability worldwide, with ischemic stroke accounting for nearly 87% of all cases. Vascular occlusion, a key pathological event in ischemic stroke, has been reliably reproduced in preclinical studies using permanent ischemic stroke models. This study demonstrated the neuroprotective effect of NXC736, a functional antagonist of sphingosine-1-phosphate receptor 4 (S1P₄, currently in phase II clinical trials for alopecia areata), against acute injury in mice with permanent middle cerebral artery occlusion (pMCAO). pMCAO-challenged mice received oral NXC736 1 h after occlusion. NXC736 demonstrated substantial therapeutic activity against permanent ischemic stroke by attenuating pMCAO-induced acute brain infarction, neurological deficits, and apoptosis. Additionally, NXC736 reduced blood-brain barrier disruption and edema in the injured brain. Moreover, NXC736 reduced microglial activation and proliferation, oxidative stress, and suppressed pro-inflammatory cytokine expression, suggesting that the efficacy of NXC736 in permanent ischemic stroke is associated with the suppression of neuroinflammatory responses. Mechanistically, we found that NXC736-mediated neuroprotective effects were dependent on the inactivation of NF-κB and MAPKs, including ERK1/2, JNK, and p38. Collectively, our findings indicate that NXC736 is an effective neuroprotective drug for permanent ischemic brain stroke, highlighting S1P₄ as a promising therapeutic target for ischemic stroke.