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Honarpisheh P, Lee J, Banerjee A, Blasco-Conesa MP, Honarpisheh P, d'Aigle J, Mamun AA, Ritzel RM, Chauhan A, Ganesh BP, McCullough LD. Potential caveats of putative microglia-specific markers for assessment of age-related cerebrovascular neuroinflammation. J Neuroinflammation 2020; 17:366. [PMID: 33261619 PMCID: PMC7709276 DOI: 10.1186/s12974-020-02019-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/29/2020] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The ability to distinguish resident microglia from infiltrating myeloid cells by flow cytometry-based surface phenotyping is an important technique for examining age-related neuroinflammation. The most commonly used surface markers for the identification of microglia include CD45 (low-intermediate expression), CD11b, Tmem119, and P2RY12. METHODS In this study, we examined changes in expression levels of these putative microglia markers in in vivo animal models of stroke, cerebral amyloid angiopathy (CAA), and aging as well as in an ex vivo LPS-induced inflammation model. RESULTS We demonstrate that Tmem119 and P2RY12 expression is evident within both CD45int and CD45high myeloid populations in models of stroke, CAA, and aging. Interestingly, LPS stimulation of FACS-sorted adult microglia suggested that these brain-resident myeloid cells can upregulate CD45 and downregulate Tmem119 and P2RY12, making them indistinguishable from peripherally derived myeloid populations. Importantly, our findings show that these changes in the molecular signatures of microglia can occur without a contribution from the other brain-resident or peripherally sourced immune cells. CONCLUSION We recommend future studies approach microglia identification by flow cytometry with caution, particularly in the absence of the use of a combination of markers validated for the specific neuroinflammation model of interest. The subpopulation of resident microglia residing within the "infiltrating myeloid" population, albeit small, may be functionally important in maintaining immune vigilance in the brain thus should not be overlooked in neuroimmunological studies.
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Affiliation(s)
- Pedram Honarpisheh
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA.,UTHealth Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center, Houston, USA
| | - Juneyoung Lee
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - Anik Banerjee
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA.,UTHealth Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center, Houston, USA
| | - Maria P Blasco-Conesa
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - Parisa Honarpisheh
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - John d'Aigle
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - Abdullah A Mamun
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - Rodney M Ritzel
- Department of Anesthesiology, Center for Shock, Trauma, and Anesthesiology Research, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Anjali Chauhan
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - Bhanu P Ganesh
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA
| | - Louise D McCullough
- Department of Neurology, University of Texas John P. and Kathrine G. McGovern Medical School, Houston, TX, USA.
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