Format

Send to

Choose Destination
Stroke. 2016 Feb;47(2):498-504. doi: 10.1161/STROKEAHA.115.012079. Epub 2016 Jan 5.

Interleukin-4 Is Essential for Microglia/Macrophage M2 Polarization and Long-Term Recovery After Cerebral Ischemia.

Author information

1
From the Department of Neurology, University of Pittsburgh School of Medicine, PA (X.L., S.Z., H.Z., W.C., J.C., X.H.); Cerebrovascular Diseases Research Institute, Xuanwu Hospital of Capital Medical University, Beijing, P.R. China (X.L., X.J.); State Key Laboratory of Medical Neurobiology, Institute of Brain Sciences, Fudan University, Shanghai, China (J.L., M.C., Y.G., J.C., X.H.); Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA (R.K.L.); and Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, PA (J.C., X.H.).
2
From the Department of Neurology, University of Pittsburgh School of Medicine, PA (X.L., S.Z., H.Z., W.C., J.C., X.H.); Cerebrovascular Diseases Research Institute, Xuanwu Hospital of Capital Medical University, Beijing, P.R. China (X.L., X.J.); State Key Laboratory of Medical Neurobiology, Institute of Brain Sciences, Fudan University, Shanghai, China (J.L., M.C., Y.G., J.C., X.H.); Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA (R.K.L.); and Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, PA (J.C., X.H.). hux2@upmc.edu.

Abstract

BACKGROUND AND PURPOSE:

Interleukin-4 (IL-4) is a unique cytokine that may contribute to brain repair by regulating microglia/macrophage functions. Thus, we examined the effect of IL-4 on long-term recovery and microglia/macrophage polarization in 2 well-established stroke models.

METHODS:

Transient middle cerebral artery occlusion or permanent distal middle cerebral artery occlusion was induced in wild-type and IL-4 knockout C57/BL6 mice. In a separate cohort of wild-type animals, IL-4 (60 ng/d for 7 days) or vehicle was infused into the cerebroventricle after transient middle cerebral artery occlusion. Behavioral outcomes were assessed by the Rotarod, corner, foot fault, and Morris water maze tests. Neuronal tissue loss was verified by 2 independent neuron markers. Markers of classically activated (M1) and alternatively activated (M2) microglia were assessed by real-time polymerase chain reaction, immunofluorescence, and flow cytometry.

RESULTS:

Loss of IL-4 exacerbated sensorimotor deficits and impaired cognitive functions ≤21 days post injury. In contrast to the delayed deterioration of neurological functions, IL-4 deficiency increased neuronal tissue loss only in the acute phase (5 days) after stroke and had no impact on neuronal tissue loss 14 or 21 days post injury. Loss of IL-4 promoted expression of M1 microglia/macrophage markers and impaired expression of M2 markers at 5 and 14 days post injury. Administration of IL-4 into the ischemic brain also enhanced long-term functional recovery.

CONCLUSIONS:

The cytokine IL-4 improves long-term neurological outcomes after stroke, perhaps through M2 phenotype induction in microglia/macrophages. These results are the first to suggest that immunomodulation with IL-4 is a promising approach to promote long-term functional recovery after stroke.

KEYWORDS:

flow cytometry; interleukin-4; macrophages; neurological function; stroke

PMID:
26732561
PMCID:
PMC4729613
DOI:
10.1161/STROKEAHA.115.012079
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Atypon Icon for PubMed Central
Loading ...
Support Center