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Kurisu K, Zheng Z, Kim JY, Shi J, Kanoke A, Liu J, Hsieh CL, Yenari MA. Triggering receptor expressed on myeloid cells-2 expression in the brain is required for maximal phagocytic activity and improved neurological outcomes following experimental stroke. J Cereb Blood Flow Metab 2019; 39:1906-1918. [PMID: 30523715 PMCID: PMC6775587 DOI: 10.1177/0271678x18817282] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Triggering receptor expressed on myeloid cells-2 (TREM2) is an innate immune receptor that promotes phagocytosis by myeloid cells such as microglia and macrophages. We previously showed that TREM2 deficiency worsened outcomes from experimental stroke and impeded phagocytosis. However, myeloid cells participating in stroke pathology include both brain resident microglia and circulating macrophages. We now clarify whether TREM2 on brain microglia or circulating macrophages contribute to its beneficial role in ischemic stroke by generating bone marrow (BM) chimeric mice. BM chimera mice from TREM2 knockout (KO) or wild type (Wt) mice were used as donor and recipient mice. Mice were subjected to experimental stroke, and neurological function and infarct volume were assessed. Mice with intact TREM2 in brain microglia showed better neurological recovery and reduced infarct volumes, compared with mice lacking microglial TREM2. Myeloid cell activation and numbers of phagocytes were decreased in mice lacking brain TREM2, compared with mice with intact brain TREM2. These results suggest that TREM2 expression is important for post-stroke recovery, and that TREM2 expression on brain resident microglia is more essential to this recovery, than that of circulating macrophages. These findings might suggest a new therapeutic target for cerebrovascular diseases.
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Affiliation(s)
- Kota Kurisu
- Department of Neurology, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Zhen Zheng
- Department of Neurology, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Jong Youl Kim
- Department of Neurology, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Jian Shi
- Department of Neurology, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Atsushi Kanoke
- Department of Neurosurgery, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Jialing Liu
- Department of Neurosurgery, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Christine L Hsieh
- Department of Medicine, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
| | - Midori A Yenari
- Department of Neurology, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA
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Yang Y, Liu H, Zhang H, Ye Q, Wang J, Yang B, Mao L, Zhu W, Leak RK, Xiao B, Lu B, Chen J, Hu X. ST2/IL-33-Dependent Microglial Response Limits Acute Ischemic Brain Injury. J Neurosci 2017; 37:4692-4704. [PMID: 28389473 PMCID: PMC5426564 DOI: 10.1523/jneurosci.3233-16.2017] [Citation(s) in RCA: 158] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 02/14/2017] [Accepted: 03/03/2017] [Indexed: 12/11/2022] Open
Abstract
ST2, a member of the interleukin (IL) 1 receptor family, and its ligand IL-33 play critical roles in immune regulation and inflammatory responses. This study explores the roles of endogenous IL-33/ST2 signaling in ischemic brain injury and elucidates the underlying mechanisms of action. The expression of IL-33 rapidly increased in oligodendrocytes and astrocytes after 60 min transient middle cerebral artery occlusion (tMCAO). ST2 receptor deficiency exacerbated brain infarction 3 d after tMCAO as well as distal permanent MCAO. ST2 deficiency also aggravated neurological deficits up to 7 d after tMCAO. Conversely, intracerebroventricular infusions of IL-33 after tMCAO attenuated brain infarction. Flow cytometry analyses demonstrated high levels of ST2 expression on microglia, and this expression was dramatically enhanced after tMCAO. The absence of ST2 enhanced the expression of M1 polarization markers on microglia/macrophages, and impaired the expression of M2 polarization markers after tMCAO. In vitro studies on various types of cultures and coculture systems confirmed that IL-33/ST2 signaling potentiated expression of IL-10 and other M2 genes in primary microglia. The activation of ST2 on microglia led to a protective phenotype that enhanced neuronal survival against oxygen glucose deprivation. Further in vitro studies revealed that IL-33-activated microglia released IL-10, and that this was critical for their neuroprotective effects. Similarly, intracerebroventricular infusions of IL-33 into IL-10 knock-out mice failed to provide neuroprotection against tMCAO in vivo These results shed new light on the IL-33/ST2 axis as an immune regulatory mechanism that serves as a natural brake on the progression of ischemic brain injury.SIGNIFICANCE STATEMENT This is the first study to identify the function of interleukin (IL) 33/ST2 signaling in poststroke microglial responses and neuroprotection against ischemia. Using two models of ischemic stroke, we demonstrate here that ST2 deficiency shifted microglia/macrophages toward a M1-like phenotype, thereby expanding brain infarcts and exacerbating long-term behavioral deficits after stroke. Using stroke models and various in vitro culture and coculture systems, we further characterized a previously undefined mechanism whereby IL-33/ST2 engagement stimulates the production of IL-10 from microglia, which, in turn, enhances neuronal survival upon ischemic challenge. These results shed light on endogenous IL-33/ST2 signaling as a potential immune regulatory mechanism that serves to promote beneficial microglial responses and mitigate ischemic brain injury after stroke.
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Affiliation(s)
- Yuanyuan Yang
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
- Xiangya Third Hospital, Central South University, Changsha, Hunan 410013, China
- Department of Neurology, Xiangya Hospital, Changsha, Hunan 410008, China
| | - Huan Liu
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
- Xiangya Third Hospital, Central South University, Changsha, Hunan 410013, China
| | - Haiyue Zhang
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
- Xiangya Third Hospital, Central South University, Changsha, Hunan 410013, China
| | - Qing Ye
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
| | - Jianyi Wang
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
- Xiangya Third Hospital, Central South University, Changsha, Hunan 410013, China
| | - Boyu Yang
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
| | - Leilei Mao
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
| | - Wen Zhu
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
| | - Rehana K Leak
- Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282, and
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Changsha, Hunan 410008, China
| | - Binfeng Lu
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Jun Chen
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
- Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, Pennsylvania 15261
| | - Xiaoming Hu
- Pittsburgh Institute of Brain Disorders and Recovery, Department of Neurology and
- Geriatric Research, Educational and Clinical Center, Veterans Affairs Pittsburgh Health Care System, Pittsburgh, Pennsylvania 15261
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Ritzel RM, Patel AR, Grenier JM, Crapser J, Verma R, Jellison ER, McCullough LD. Functional differences between microglia and monocytes after ischemic stroke. J Neuroinflammation 2015; 12:106. [PMID: 26022493 PMCID: PMC4465481 DOI: 10.1186/s12974-015-0329-1] [Citation(s) in RCA: 219] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/20/2015] [Indexed: 01/16/2023] Open
Abstract
Background The brain’s initial innate response to stroke is primarily mediated by microglia, the resident macrophage of the CNS. However, as early as 4 h after stroke, the blood–brain barrier is compromised and monocyte infiltration occurs. The lack of discriminating markers between these two myeloid populations has led many studies to generate conclusions based on the grouping of these two populations. A growing body of evidence now supports the distinct roles played by microglia and monocytes in many disease models. Methods Using a flow cytometry approach, combined with ex-vivo functional assays, we were able to distinguish microglia from monocytes using the relative expression of CD45 and assess the function of each cell type following stroke over the course of 7 days. Results We found that at 72 h after a 90-min middle cerebral artery occlusion (MCAO), microglia populations decrease whereas monocytes significantly increase in the stroke brain compared to sham. After stroke, BRDU incorporation into monocytes in the bone marrow increased. After recruitment to the ischemic brain, these monocytes accounted for nearly all BRDU-positive macrophages. Inflammatory activity peaked at 72 h. Microglia produced relatively higher reactive oxygen species and TNF, whereas monocytes were the predominant IL-1β producer. Although microglia showed enhanced phagocytic activity after stroke, monocytes had significantly higher phagocytic capacity at 72 h. Interestingly, we found a positive correlation between TNF expression levels and phagocytic activity of microglia after stroke. Conclusions In summary, the resident microglia population is vulnerable to the effects of severe ischemia, show compromised cell cycle progression, and adopt a largely pro-inflammatory phenotype after stroke. Infiltrating monocytes are primarily involved with early debris clearance of dying cells. These findings suggest that the early wave of infiltrating monocytes may be beneficial to stroke repair and future therapies aimed at mitigating microglia cell death may prove more effective than attempting to elicit targeted anti-inflammatory responses from damaged cells. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0329-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rodney M Ritzel
- Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
| | - Anita R Patel
- Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
| | - Jeremy M Grenier
- Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
| | - Joshua Crapser
- Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
| | - Rajkumar Verma
- Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
| | - Evan R Jellison
- Department of Immunology, University of Connecticut Health Center, Farmington, CT, USA.
| | - Louise D McCullough
- Department of Neurology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT, 06030, USA.
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Abstract
Microglia are considered the brain's resident immune cell involved in immune defense, immunocompetence, and phagocytosis. They maintain tissue homeostasis within the brain and spinal cord under normal condition and serves as its initial host defense system. However, when the central nervous system (CNS) faces injury, microglia respond through signaling molecules expressed or released by neighboring cells. Microglial responses are dual in nature. They induce a nonspecific immune response that may exacerbate CNS injury, especially in the acute stages, but are also essential to CNS recovery and repair. The full range of microglial mechanisms have yet to be clarified, but there is accumulating knowledge about microglial activation in acute CNS injury. Microglial responses require hours to days to fully develop, and may present a therapeutic target for intervention with a much longer window of opportunity compare to other neurological treatments. The challenge will be to find ways to selectively suppress the deleterious effects of microglial activation without compromising its beneficial functions. This review aims to provide an overview of the recent progress relating on the deleterious and beneficial effect of microglia in the setting of acute CNS injury and the potential therapeutic intervention against microglial activation to CNS injury.
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Affiliation(s)
- Masahito Kawabori
- Department of Neurology, University of California, San Francisco and the San Francisco Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA, 94121, USA
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Targeting the peripheral inflammatory response to stroke: role of the spleen. Transl Stroke Res 2014; 5:635-7. [PMID: 25252625 DOI: 10.1007/s12975-014-0372-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 12/12/2022]
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Brain arteriovenous malformation modeling, pathogenesis, and novel therapeutic targets. Transl Stroke Res 2014; 5:316-29. [PMID: 24723256 DOI: 10.1007/s12975-014-0343-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 03/24/2014] [Accepted: 03/25/2014] [Indexed: 02/07/2023]
Abstract
Patients harboring brain arteriovenous malformation (bAVM) are at life-threatening risk of rupture and intracranial hemorrhage (ICH). The pathogenesis of bAVM has not been completely understood. Current treatment options are invasive, and ≈ 20 % of patients are not offered interventional therapy because of excessive treatment risk. There are no specific medical therapies to treat bAVMs. The lack of validated animal models has been an obstacle for testing hypotheses of bAVM pathogenesis and testing new therapies. In this review, we summarize bAVM model development and bAVM pathogenesis and potential therapeutic targets that have been identified during model development.
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