MMP-9 inhibitor SB-3CT improves neurological outcomes in ischemic stroke mice by modulation of astrocytic lipid metabolism.

The acute phase of ischemic stroke is marked by a surge in matrix metalloproteinase-9 (MMP-9) activity. While integral to natural repair processes, MMP-9 exacerbates injury by breaking down the blood-brain barrier (BBB) and promoting edema and inflammation. MMP-9 is predominantly secreted by inflammatory cells such as neutrophils, macrophages and microglia soon after stroke onset. In this study we investigated the effects of MMP-9 inhibition via SB-3CT on astrocytic lipid metabolism, and its potential to enhance neuronal survival and recovery following ischemic stroke. Mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min, mice then were injected with SB-3CT (25 mg/kg, i.v.). On D3 post tMCAO, neurological outcomes were assessed, and whole brains were collected for analysis. Lipidomic analysis of brain tissue showed that SB-3CT treatment significantly restrained astrocytic cholesterol metabolism by modulating the sphingolipid and glycerophospholipid pathways. Specifically, SB-3CT reduced ceramide accumulation and promoted an increase in neuroprotective hexosylceramides, leading to enhanced neuronal survival and synaptic integrity. In addition, SB-3CT treatment reduced astrocytic and microglial reactivity, thereby mitigating neuroinflammation. In order to optimize the timing and dosage of MMP-9 inhibition to maximize the therapeutic efficacy, tMCAO mice were given three injections of SB-3CT on D0, D2 and D4 within 7 days after modeling. We found that prolonged MMP-9 inhibition alleviated astrogliosis, concurrently impaired neurological recovery and inhibited angiogenesis. These results demonstrate the critical role of lipid metabolism in MMP-9-mediated brain injury and the potential of SB-3CT as a therapeutic strategy for ischemic stroke by targeting astrocytic lipid metabolism.