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Alternatively activated brain-infiltrating macrophages facilitate recovery from collagenase-induced intracerebral hemorrhage.

Min H, Jang YH, Cho IH, Yu SW, Lee SJ - Mol Brain (2016)

Bottom Line: In the macrophage-depleted mice, ICH-induced brain lesion volume was larger and neurological deficits were more severe compared to those of control mice, indicating a protective role of these macrophages in ICH.Upon co-culture with glia, the number of mannose receptor-positive M2 macrophages was significantly increased.Furthermore, treatment with glia-conditioned media increased the number of BMDM of M2 phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience and Dental Research Institute, School of Dentistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

ABSTRACT

Background: Intracerebral hemorrhage (ICH) is one of the major causes of stroke. After onset of ICH, massive infiltration of macrophages is detected in the peri-hematoma regions. Still, the function of these macrophages in ICH has not been completely elucidated.

Results: In a collagenase-induced ICH model, CX3CR1(+) macrophages accumulated in the peri-hematoma region. Characterization of these macrophages revealed expression of alternatively activated (M2) macrophage markers. In the macrophage-depleted mice, ICH-induced brain lesion volume was larger and neurological deficits were more severe compared to those of control mice, indicating a protective role of these macrophages in ICH. In the ICH-injured brain, mannose receptor-expressing macrophages increased at a delayed time point after ICH, indicating M2 polarization of the brain-infiltrating macrophages in the brain microenvironment. To explore this possibility, bone marrow-derived macrophages (BMDM) were co-cultured with mouse brain glial cells and then tested for activation phenotype. Upon co-culture with glia, the number of mannose receptor-positive M2 macrophages was significantly increased. Furthermore, treatment with glia-conditioned media increased the number of BMDM of M2 phenotype.

Conclusions: In this study, our data suggest that brain-infiltrating macrophages after ICH are polarized to the M2 phenotype by brain glial cells and thereby contribute to recovery from ICH injury.

No MeSH data available.


Related in: MedlinePlus

CX3CR1+ cells increase in the peri-hematoma region after ICH. a CX3CR1+ cells were detected in peri-hematoma regions of hemorrhagic brain sections. b–e Representative images on brain sections were obtained from Cx3cr1+/GFP mice at 1, 3, and 7 days after ICH or sham operation. Three days after ICH, amoeboid cells were detected in the peri-hematoma region (arrows) (Scale bar, 100 μm). f Myeloid cells (F4/80+) in the lesion were analyzed and further divided into CD45-low microglia and CD45-high macrophage populations according to the expression level of CD45 according to flow cytometry. The flow cytometry data are representative of three independent experiments
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Fig1: CX3CR1+ cells increase in the peri-hematoma region after ICH. a CX3CR1+ cells were detected in peri-hematoma regions of hemorrhagic brain sections. b–e Representative images on brain sections were obtained from Cx3cr1+/GFP mice at 1, 3, and 7 days after ICH or sham operation. Three days after ICH, amoeboid cells were detected in the peri-hematoma region (arrows) (Scale bar, 100 μm). f Myeloid cells (F4/80+) in the lesion were analyzed and further divided into CD45-low microglia and CD45-high macrophage populations according to the expression level of CD45 according to flow cytometry. The flow cytometry data are representative of three independent experiments

Mentions: To detect macrophages infiltrating brain parenchyma after ICH injury, we utilized Cx3cr1+/GFP mice in which CX3CR1-expressing macrophages and microglia can be monitored using GFP fluorescence. Following ICH, the cells with GFP fluorescence increased as soon as 1 day post-injury (dpi) in the surrounding area of hematoma, indicating upregulation of CX3CR1 in microglia/macrophages in this area (Fig. 1b and c). Three days after ICH, CX3CR1+ cells greatly increased in the injured brain area. In particular, round CX3CR1+ cells, morphologically presumed to be brain-infiltrating activated macrophages, accumulated in the peri-hematoma region, which was further increased on 7 dpi (Fig. 1d and e). To differentiate macrophages from microglia in this CX3CR1+ population, we analyzed the F4/80-positive monocytic cell population in the injured brain using flow cytometry based on the expression level of CD45 (Fig. 1f) [24]. The percentage of CD45high/F4/80+ leukocytes representing the macrophage population increased to 11.5 % on 1 dpi and 31 % on 3 dpi from 1.8 % (sham). In the same time frame, the number of CD45low/F4/80+ cells representing the microglia population was not as significantly altered; it increased only to 58 % on 3 dpi from 40 % (sham). These data demonstrate that the increase in CX3CR1+ cells after ICH is mainly due to macrophage infiltration rather than microglia proliferation.Fig. 1


Alternatively activated brain-infiltrating macrophages facilitate recovery from collagenase-induced intracerebral hemorrhage.

Min H, Jang YH, Cho IH, Yu SW, Lee SJ - Mol Brain (2016)

CX3CR1+ cells increase in the peri-hematoma region after ICH. a CX3CR1+ cells were detected in peri-hematoma regions of hemorrhagic brain sections. b–e Representative images on brain sections were obtained from Cx3cr1+/GFP mice at 1, 3, and 7 days after ICH or sham operation. Three days after ICH, amoeboid cells were detected in the peri-hematoma region (arrows) (Scale bar, 100 μm). f Myeloid cells (F4/80+) in the lesion were analyzed and further divided into CD45-low microglia and CD45-high macrophage populations according to the expression level of CD45 according to flow cytometry. The flow cytometry data are representative of three independent experiments
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4837536&req=5

Fig1: CX3CR1+ cells increase in the peri-hematoma region after ICH. a CX3CR1+ cells were detected in peri-hematoma regions of hemorrhagic brain sections. b–e Representative images on brain sections were obtained from Cx3cr1+/GFP mice at 1, 3, and 7 days after ICH or sham operation. Three days after ICH, amoeboid cells were detected in the peri-hematoma region (arrows) (Scale bar, 100 μm). f Myeloid cells (F4/80+) in the lesion were analyzed and further divided into CD45-low microglia and CD45-high macrophage populations according to the expression level of CD45 according to flow cytometry. The flow cytometry data are representative of three independent experiments
Mentions: To detect macrophages infiltrating brain parenchyma after ICH injury, we utilized Cx3cr1+/GFP mice in which CX3CR1-expressing macrophages and microglia can be monitored using GFP fluorescence. Following ICH, the cells with GFP fluorescence increased as soon as 1 day post-injury (dpi) in the surrounding area of hematoma, indicating upregulation of CX3CR1 in microglia/macrophages in this area (Fig. 1b and c). Three days after ICH, CX3CR1+ cells greatly increased in the injured brain area. In particular, round CX3CR1+ cells, morphologically presumed to be brain-infiltrating activated macrophages, accumulated in the peri-hematoma region, which was further increased on 7 dpi (Fig. 1d and e). To differentiate macrophages from microglia in this CX3CR1+ population, we analyzed the F4/80-positive monocytic cell population in the injured brain using flow cytometry based on the expression level of CD45 (Fig. 1f) [24]. The percentage of CD45high/F4/80+ leukocytes representing the macrophage population increased to 11.5 % on 1 dpi and 31 % on 3 dpi from 1.8 % (sham). In the same time frame, the number of CD45low/F4/80+ cells representing the microglia population was not as significantly altered; it increased only to 58 % on 3 dpi from 40 % (sham). These data demonstrate that the increase in CX3CR1+ cells after ICH is mainly due to macrophage infiltration rather than microglia proliferation.Fig. 1

Bottom Line: In the macrophage-depleted mice, ICH-induced brain lesion volume was larger and neurological deficits were more severe compared to those of control mice, indicating a protective role of these macrophages in ICH.Upon co-culture with glia, the number of mannose receptor-positive M2 macrophages was significantly increased.Furthermore, treatment with glia-conditioned media increased the number of BMDM of M2 phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience and Dental Research Institute, School of Dentistry, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

ABSTRACT

Background: Intracerebral hemorrhage (ICH) is one of the major causes of stroke. After onset of ICH, massive infiltration of macrophages is detected in the peri-hematoma regions. Still, the function of these macrophages in ICH has not been completely elucidated.

Results: In a collagenase-induced ICH model, CX3CR1(+) macrophages accumulated in the peri-hematoma region. Characterization of these macrophages revealed expression of alternatively activated (M2) macrophage markers. In the macrophage-depleted mice, ICH-induced brain lesion volume was larger and neurological deficits were more severe compared to those of control mice, indicating a protective role of these macrophages in ICH. In the ICH-injured brain, mannose receptor-expressing macrophages increased at a delayed time point after ICH, indicating M2 polarization of the brain-infiltrating macrophages in the brain microenvironment. To explore this possibility, bone marrow-derived macrophages (BMDM) were co-cultured with mouse brain glial cells and then tested for activation phenotype. Upon co-culture with glia, the number of mannose receptor-positive M2 macrophages was significantly increased. Furthermore, treatment with glia-conditioned media increased the number of BMDM of M2 phenotype.

Conclusions: In this study, our data suggest that brain-infiltrating macrophages after ICH are polarized to the M2 phenotype by brain glial cells and thereby contribute to recovery from ICH injury.

No MeSH data available.


Related in: MedlinePlus