title: Novel association between microglia and stem cells in human gliomas: A contributor to tumour proliferation?
abstract: Brain tumour stem cells and microglia both promote the growth of astrocytomas, the commonest form of primary brain tumour, with recent emerging evidence that these cell types may interact in glioma models. It is unclear whether microglia and stem cells are associated in human gliomas. To investigate this question, we used the technique of tissue microarrays to perform a correlative study of a large number of tumour samples. We quantified immunostaining of human astrocytic tumour tissue microarrays (86 patients; World Health Organisation grade II-IV) for microglia Ionized calcium binding adaptor molecule 1 (Iba1) and CD68, and stem cell nestin, SOX2 and CD133. Ki67 was used to assess proliferation and GFAP for astrocytic differentiation. Immunoreactivity for both microglial markers and stem cell markers nestin and SOX2 significantly increased with increasing tumour grade. GFAP was higher in low grade astrocytomas. There was a positive correlation between: (i) both microglial markers and nestin and CD133, (ii) nestin and tumour cell proliferation Ki67 and (iii) both microglial markers and Ki67. SOX2 was not associated with microglia or tumour proliferation. To test the clinical relevance, we investigated the putative association of these markers with clinical outcomes. High expression for nestin and Iba1 correlated with significantly shorter survival times, and high expression for nestin, Iba1, CD68 and Ki67 was associated with faster tumour progression on univariate analysis. On multivariate analysis, nestin, CD133 and Ki67 remained significant predictors of poorer survival, after adjustment for other markers. These results confirm previous in vitro findings, demonstrating their functional relevance as a therapeutic target in humans. This is the first report of a novel correlation between microglia and stem cells that may drive human astrocytic tumour development.
authors: Clinical Neurosciences Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton Southampton UK.
authors: Imran
authors: I
authors: Noorani
authors: Clinical NeurosciencesClinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of SouthamptonSouthamptonUK; Department of Cellular PathologyUniversity Hospital Southampton NHS Foundation TrustSouthamptonUK.
authors: Gareth
authors: G
authors: Petty
authors: Wessex Neurological Centre University Hospital Southampton NHS Foundation Trust Southampton UK.
authors: Paul L
authors: PL
authors: Grundy
authors: Wessex Neurological Centre University Hospital Southampton NHS Foundation Trust Southampton UK.
authors: Geoff
authors: G
authors: Sharpe
authors: Clinical Neurosciences Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton Southampton UK.
authors: Sandrine
authors: S
authors: Willaime-Morawek
authors: Public Health Sciences and Medical Statistics Faculty of Medicine, University of Southampton Southampton UK.
authors: Scott
authors: S
authors: Harris
authors: Cancer Science Academic Unit Faculty of Medicine, University of Southampton Southampton UK.
authors: Gareth J
authors: GJ
authors: Thomas
authors: Clinical NeurosciencesClinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of SouthamptonSouthamptonUK; Department of Cellular PathologyUniversity Hospital Southampton NHS Foundation TrustSouthamptonUK.
authors: James Ar
authors: JA
authors: Nicoll
authors: Clinical Neurosciences Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton Southampton UK.
authors: Delphine
authors: D
authors: Boche
keywords: brain tumour; glioma; microglia; stem cells