title: M-CSF increases proliferation and phagocytosis while modulating receptor and transcription factor expression in adult human microglia.
abstract: BACKGROUND
  Microglia are the primary immune cells of the brain whose phenotype largely depends on their surrounding micro-environment. Microglia respond to a multitude of soluble molecules produced by a variety of brain cells. Macrophage colony-stimulating factor (M-CSF) is a cytokine found in the brain whose receptor is expressed by microglia. Previous studies suggest a critical role for M-CSF in brain development and normal functioning as well as in several disease processes involving neuroinflammation.
  
  
  METHODS
  Using biopsy tissue from patients with intractable temporal epilepsy and autopsy tissue, we cultured primary adult human microglia to investigate their response to M-CSF. Mixed glial cultures were treated with 25 ng/ml M-CSF for 96 hours. Proliferation and phagocytosis assays, and high through-put immunocytochemistry, microscopy and image analysis were performed to investigate microglial phenotype and function.
  
  
  RESULTS
  We found that the phenotype of primary adult human microglia was markedly changed following exposure to M-CSF. A greater number of microglia were present in the M-CSF- treated cultures as the percentage of proliferating (BrdU and Ki67-positive) microglia was greatly increased. A number of changes in protein expression occurred following M-CSF treatment, including increased transcription factors PU.1 and C/EBPβ, increased DAP12 adaptor protein, increased M-CSF receptor (CSF-1R) and IGF-1 receptor, and reduced HLA-DP, DQ, DR antigen presentation protein. Furthermore, a distinct morphological change was observed with elongation of microglial processes. These changes in phenotype were accompanied by a functional increase in phagocytosis of Aβ1-42 peptide.
  
  
  CONCLUSIONS
  We show here that the cytokine M-CSF dramatically influences the phenotype of adult human microglia. These results pave the way for future investigation of M-CSF-related targets for human therapeutic benefit.
authors.affiliation: Department of Pharmacology and Clinical Pharmacology, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Smith
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Gibbons
authors.forename: Robyn L
authors.initials: RL
authors.lastname: Oldfield
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bergin
authors.forename: Edward W
authors.initials: EW
authors.lastname: Mee
authors.forename: Maurice A
authors.initials: MA
authors.lastname: Curtis
authors.forename: Richard L M
authors.initials: RL
authors.lastname: Faull
authors.forename: Mike
authors.initials: M
authors.lastname: Dragunow
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000235:genetics; D000963:Antimetabolites; D001344:Autopsy; D001706:Biopsy; D001973:Bromodeoxyuridine; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D006680:HLA Antigens / Q000096:biosynthesis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D008262:Macrophage Activation / Q000187:drug effects; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D010587:Phagocytosis / Q000187:drug effects*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis*; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000963:Antimetabolites; D001973:Bromodeoxyuridine; D022782:CCAAT-Enhancer-Binding Protein-beta; D006680:HLA Antigens; D019394:Ki-67 Antigen; D016173:Macrophage Colony-Stimulating Factor; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor; D015534:Trans-Activators; D014157:Transcription Factors; D000099232:Proto-Oncogene Protein Spi-1; C110546:TYROBP protein, human