Expression of the translocator protein 18 kDa (TSPO) in glial reactivity and utility as a phenotypic marker in mouse models of perinatal brain injury

Student thesis: Master's ThesisMaster of Science

Abstract

Perinatal brain injury is a major cause of neurological disabilities in infants and microglial activation has been implicated in the pathophysiology of these injuries. Activated microglia adopt a series of varied phenotypes including pro-inflammatory M1, anti-inflammatory M2a and immunomodulatory M2b. Efforts have been directed to the development of PET imaging of activated microglia using radiolabelled ligands of the translocator protein 18 kDa (TSPO) found in activated microglia. In this study, BV-2 microglia and astrocytes were polarised with lipopolysaccharide and interleukin 4 as inducers of M1 and M2 microglia respectively. Semi-quantitative protein analysis with Western blotting and immunofluorescent staining was used to characterise expression of TSPO, pro-inflammatory marker COX-2 and anti-inflammatory marker Arg1. We also assessed TSPO ligand [3H]PK11195 binding in M1 and M2-polarised microglia and in mouse models of neonatal cerebral hypoxia-ischemia (HI) and perinatal inflammation (PI) +/- endotoxin challenge at adulthood. Protein analysis suggests there is a larger increase in TSPO expression in M2 microglia compared to M1. In contrast with the literature, activation of microglia reduces binding of [3H]PK11195 corrected to number of cells and this may be due to differences in cellular environment in tissue and in vivo. HI injury models expressed increased binding of [3H]PK11195 at 72 hours vs 24 hours which may correspond to a predominantly M2 microglial activation. Endotoxin-challenged PI model brains showed no apparent difference in [3H]PK11195 binding compared to control. These findings suggest TSPO as a possible marker of M2a phenotype microglia and further studies are warranted to establish this proposition.
Date of AwardSept 2013
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorBobbi Fleiss (Supervisor), Tony Gee (Supervisor), Pierre Gressens (Supervisor) & Zilin Yu (Supervisor)

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