Inflammatory and immune responses in the brain can shape the clinical presentation and outcome of stroke. Approaches for effective management of acute stroke are sparse and many measures for brain protection fail, but our ability to modulate the immune system and modify the disease progression of multiple sclerosis is increasing. As a result, immune interventions are currently being explored as therapeutic interventions in acute stroke. In this Review, we compare the immunological features of acute stroke with those of multiple sclerosis, identify unique immunological features of stroke, and consider the evidence for immune interventions. In acute stroke, microglia activation and cell death products trigger an inflammatory cascade that damages vessels and the parenchyma within minutes to hours of the ischaemia or haemorrhage. Immune interventions that restrict brain inflammation, vascular permeability and tissue oedema must be administered rapidly to reduce acute immune-mediated destruction and to avoid subsequent immunosuppression. Preliminary results suggest that the use of drugs that modify disease in multiple sclerosis might accomplish these goals in ischaemic and haemorrhagic stroke. Further elucidation of the immune mechanisms involved in stroke is likely to lead to successful immune interventions.

No abstract

Background Inflammatory and immune responses triggered by brain ischemia worsen clinical outcomes of stroke and contribute to hemorrhagic transformation, massive edema and reperfusion injury associated with intravenous alteplase. We assessed whether a combination of the immune-modulator fingolimod and alteplase is safe and effective in attenuating reperfusion injury in patients with acute ischemic stroke (AIS) treated within the first 4.5 hours of symptom onset. Methods and Results In this multi-center trial, we randomly assigned 25 eligible patients with hemispheric ischemic stroke stemming from anterior or middle cerebral arterial occlusion to receive alteplase alone or 22 patients to receive alteplase plus oral fingolimod 0.5 mg daily for three consecutive days within 4.5 hours of the onset of ischemic stroke. Compared with patients who received alteplase alone or patients who received combination of fingolimod with alteplase exhibited lower circulating lymphocytes, smaller lesion volumes (10.1 vs 34.3 ml, P = 0.04), less hemorrhage (1.2 vs 4.4 ml, p = 0.01) and attenuated neurodeficits in National Institute of Health Stroke Scales (4 vs 2, P =0.02) at day 1. Furthermore, restrained lesion growth from day 1 to day 7 (−2.3 vs 12.1 ml, P < 0.01) with a better recovery at day 90 (modified Rankin Scale 0-1, 73% vs 32%, P < 0.01) was evident in patients given fingolimod and alteplase. No serious adverse events were recorded in all patients. Conclusions In this pilot study, combination therapy of fingolimod and alteplase was well tolerated, attenuated reperfusion injury and improved clinical outcomes in AIS patients. These findings need to be tested in further clinical trials.

Peripheral lymphocytes entering brain ischemic regions orchestrate inflammatory responses, catalyze tissue death, and worsen clinical outcomes of acute ischemic stroke (AIS) in preclinical studies. However, it is not known whether modulating brain inflammation can impact the outcome of patients with AIS. In this open-label, evaluator-blinded, parallel-group clinical pilot trial, we recruited 22 patients matched for clinical and MRI characteristics, with anterior cerebral circulation occlusion and onset of stroke that had exceeded 4.5 h, who then received standard management alone (controls) or standard management plus fingolimod (FTY720, Gilenya, Novartis), 0.5 mg per day orally for 3 consecutive days. Compared with the 11 control patients, the 11 fingolimod recipients had lower circulating lymphocyte counts, milder neurological deficits, and better recovery of neurological functions. This difference was most profound in the first week when reduction of National Institutes of Health Stroke Scale was 4 vs. −1, respectively (P = 0.0001). Neurological rehabilitation was faster in the fingolimod-treated group. Enlargement of lesion size was more restrained between baseline and day 7 than in controls (9 vs. 27 mL, P = 0.0494). Furthermore, rT1%, an indicator of microvascular permeability, was lower in the fingolimod-treated group at 7 d (20.5 vs. 11.0; P = 0.005). No drug-related serious events occurred. We conclude that in patients with acute and anterior cerebral circulation occlusion stroke, oral fingolimod within 72 h of disease onset was safe, limited secondary tissue injury from baseline to 7 d, decreased microvascular permeability, attenuated neurological deficits, and promoted recovery.acute ischemic stroke | immune modulation | fingolimod