Dimethyl fumarate modulates the immune environment and improves prognosis in the acute phase after ischemic stroke

Introduction: Dimethyl fumarate (DMF) has shown potential for protection in various animal models of neurological diseases. However, the impact of DMF on changes in peripheral immune organs and the central nervous system (CNS) immune cell composition after ischemic stroke remains unclear. Methods: Eight-week-old C57BL/6J mice with photothrombosis (PT) ischemia and patients with acute ischemic stroke (AIS) were treated with DMF. TTC staining, flow cytometry, and immunofluorescence staining were used to evaluate the infarct volume and changes in immune cells in the periphery and the CNS. Results: DMF reduced the infarct volume on Day 1 after PT. DMF reduced the percentages of peripheral immune cells, such as neutrophils, dendritic cells, macrophages and monocytes, on Day 1, followed by NK cells on Day 3 and B cells on Day 7 after PT. In the CNS, DMF significantly reduced the percentage of monocytes in the brain on Day 3 after PT. In addition, DMF increased the number of microglia in the peri-infarct area and reduced the number of neurons in the peri-infarct area in the acute and subacute phases after PT. In AIS patients, B cells decreased in patients receiving alteplase in combination with DMF. Conclusion: DMF can change the immune environment of the periphery and the CNS, reduce infarct volume in the acute phase, promote the recruitment of microglia and preserve neurons in the peri-infarct area after ischemic stroke.