MicroRNAs are a growing family of conserved molecules involved in normal biological processes including cell growth and differentiation and pathological conditions such as cancer. MiR-124 is expressed specifically in the CNS but not other tissues and plays an important role in the regulation of the genes involved in differentiation of neurons. We found that miR-124 was expressed only in normal CNS-resident macrophages, but not in inflammatory macrophages or normal macrophages isolated from blood, spleen, bone marrow, peritoneal cavity or liver. We also found that overexpression of miR-124 deactivated inflammatory macrophages and converted them into microglia-like cells. Further analysis demonstrated that miR-124 inhibited macrophage activation by targeting CEBPa, a transcription factor responsible for the differentiation of myeloid linage cells. We applied these new basic findings related to miR-124 to EAE which serves as a model of MS. We found that microRNA 124 (miR-124) is expressed in microglia cells but not in peripheral macrophages isolated from mice with EAE. Furthermore, we found that i.v. injection of liposomes containing miR-124 markedly suppressed clinical EAE and inhibited the infiltration of encephalitogenic T cells and inflammatory macrophages into the CNS. Based on these findings we hypothesize that brain-specific miR-124 mediates phenotype switching of inflammatory macrophages into a non-inflammatory phenotype, which results in suppression of autoimmune inflammation. Our data suggest that miR-124 provides a new avenue to understand basic mechanisms of microglia/monocyte biology and provides a novel therapeutic approach for diseases such as MS. We will address these specific aims in our proposal AIM 1: How does miR-124 affect the phenotype and function of macrophages? We will investigate how transfection of M? with miR-124 in vitro affects 1) polarization of macrophages into M1 or M2 types and secretion of pro- and anti-inflammatory cytokines;2) the ability of M? to stimulate or inhibit proliferation and cytokine production by autoimmune T cells.
AIM 2 : What is the role of miR-124 in promoting quiescence of microglia cells in the CNS microenvironment? We found that co-culture of macrophages with astroglial and neuronal cell lines deactivated macrophages and induced expression of miR-124 in these cells. We will utilize this co-culture system to investigate factors that result in upregulation in the expression of miR-124 in microglia/macrophages in CNS.
AIM 3 : What are the mechanisms of EAE suppression by peripheral administration of miR-124? We investigated which cell types are affected by i.v. injection of miR-124 and found that miR-124 directly affects macrophages but not DCs, or T and B cells. We will investigate whether suppression of EAE is related to induction of regulatory subsets of myeloid cells or T cells in vivo and will investigate the treatment of relapsing and progressive EAE mouse models with miR-124.

Public Health Relevance

MicroRNAs are a growing family of conserved molecules involved in normal biological processes including cell growth and differentiation and pathological conditions such as cancer. MiR-124 is expressed specifically in the CNS but not other tissues and plays an important role in the regulation of the genes involved in differentiation of neurons. We found that miR-124 was expressed only in normal CNS-resident macrophages, but not in inflammatory macrophages or normal macrophages isolated from blood, spleen, bone marrow, peritoneal cavity or liver. We also found that over-expression of miR-124 deactivated inflammatory macrophages and converted them into microglia-like cells. Further analysis demonstrated that miR-124 inhibited macrophage activation by targeting CEBPa, a transcription factor responsible for the differentiation of myeloid lineage cells. We applied these new basic findings related to miR-124 to EAE which serves as a model of MS. We found that microRNA 124 (miR-124) is expressed in microglia cells but not in peripheral macrophages isolated from mice with EAE. Furthermore, we found that i.v. injection of liposomes containing miR-124 markedly suppressed clinical EAE and inhibited the infiltration of encephalitogenic T cells and inflammatory macrophages into the CNS. Based on these findings we hypothesize that brain-specific miR-124 mediates phenotype switching of inflammatory macrophages into a non-inflammatory phenotype, which results in suppression of autoimmune inflammation. Our data suggest that miR-124 provides a new avenue to understand basic mechanisms of microglia/monocyte biology and provides a novel therapeutic approach for diseases such as MS. We will address these specific aims in our proposal AIM 1: How does miR-124 affect the phenotype and function of macrophages? We will investigate how transfection of M? with miR-124 in vitro affects 1) polarization of macrophages into M1 or M2 types and secretion of pro- and anti-inflammatory cytokines;2) the ability of M? to stimulate or inhibit proliferation and cytokine production by autoimmune T cells.
AIM 2 : What is the role of miR-124 in promoting quiescence of microglia cells in the CNS microenvironment? We found that co-culture of macrophages with astroglial and neuronal cell lines deactivated macrophages and induced expression of miR-124 in these cells. We will utilize this co-culture system to investigate factors that result in upregulation in the expression of miR-124 in microglia/macrophages in CNS.
AIM 3 : What are the mechanisms of EAE suppression by peripheral administration of miR-124? We investigated which cell types are affected by i.v. injection of miR-124 and found that miR-124 directly affects macrophages but not DCs, or T and B cells. We will investigate whether suppression of EAE is related to induction of regulatory subsets of myeloid cells or T cells in vivo and will investigate the treatment of relapsing and progressive EAE mouse models with miR-124.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS071039-02
Application #
8135285
Study Section
Clinical Neuroimmunology and Brain Tumors Study Section (CNBT)
Program Officer
Utz, Ursula
Project Start
2010-09-01
Project End
2014-05-31
Budget Start
2011-06-01
Budget End
2012-05-31
Support Year
2
Fiscal Year
2011
Total Cost
$315,861
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
Seiler, Stephan; Fletcher, Evan; Hassan-Ali, Kinsy et al. (2018) Cerebral tract integrity relates to white matter hyperintensities, cortex volume, and cognition. Neurobiol Aging 72:14-22
Starossom, Sarah C; Veremeyko, Tatyana; Yung, Amanda W Y et al. (2015) Platelets Play Differential Role During the Initiation and Progression of Autoimmune Neuroinflammation. Circ Res 117:779-92
Starossom, Sarah C; Veremeyko, Tatyana; Dukhinova, Marina et al. (2014) Glatiramer acetate (copaxone) modulates platelet activation and inhibits thrombin-induced calcium influx: possible role of copaxone in targeting platelets during autoimmune neuroinflammation. PLoS One 9:e96256
Sotnikov, Ilya; Veremeyko, Tatyana; Starossom, Sarah C et al. (2013) Platelets recognize brain-specific glycolipid structures, respond to neurovascular damage and promote neuroinflammation. PLoS One 8:e58979
Veremeyko, Tatyana; Siddiqui, Shafiuddin; Sotnikov, Ilya et al. (2013) IL-4/IL-13-dependent and independent expression of miR-124 and its contribution to M2 phenotype of monocytic cells in normal conditions and during allergic inflammation. PLoS One 8:e81774
Ponomarev, Eugene D; Veremeyko, Tatiana; Weiner, Howard L (2013) MicroRNAs are universal regulators of differentiation, activation, and polarization of microglia and macrophages in normal and diseased CNS. Glia 61:91-103
Veremeyko, Tatiana; Starossom, Sarah-Christine; Weiner, Howard L et al. (2012) Detection of microRNAs in microglia by real-time PCR in normal CNS and during neuroinflammation. J Vis Exp :
Ponomarev, Eugene D; Veremeyko, Tatyana; Barteneva, Natasha et al. (2011) MicroRNA-124 promotes microglia quiescence and suppresses EAE by deactivating macrophages via the C/EBP-*-PU.1 pathway. Nat Med 17:64-70