The investigators conduct this study to investigate whether oral administration of Dimethyl Fumarate, a Food and Drug Administration-approved drug for multiple sclerosis, is safe and effective in combination with alteplase in patients with Acute Ischemic Stroke.

Inclusion Criteria:

1. more than 18years old
2. NIHSS score≥5
3. MRI shows anterior circulation infarction
4. Patients who meet Alteplase thrombolytic therapy within 4.5h
5. The time from onset to DMF application was less than 24 hours

Exclusion Criteria:

1. Hemorrhagic stroke
2. Patients who have received or plan to receive endovascular therapy
3. Other diseases of the central nervous system
4. Pre-existing neurological disability (mRS Score >2)
5. Vertebrobasilar artery obstruction
6. Difficulty swallowing
7. Patients who cannot accept MRI examination
8. Abnormal liver function (transaminase higher than 2 times the normal upper limit)
9. The lymphocyte count was lower than the lower limit of normal value
10. Anti-tumor drugs, other immunosuppressive and immunomodulatory drugs are being used
11. Patients known to have hypersensitivity to dimethyl fumarate or any excipients
12. Pregnant and lactating women