title: Microglia and astrocytes attenuate the replication of the oncolytic vaccinia virus LIVP 1.1.1 in murine GL261 gliomas by acting as vaccinia virus traps.
abstract: BACKGROUND
  Oncolytic virotherapy is a novel approach for the treatment of glioblastoma multiforme (GBM) which is still a fatal disease. Pathologic features of GBM are characterized by the infiltration with microglia/macrophages and a strong interaction between immune- and glioma cells. The aim of this study was to determine the role of microglia and astrocytes for oncolytic vaccinia virus (VACV) therapy of GBM.
  
  
  METHODS
  VACV LIVP 1.1.1 replication in C57BL/6 and Foxn1(nu/nu) mice with and without GL261 gliomas was analyzed. Furthermore, immunohistochemical analysis of microglia and astrocytes was investigated in non-, mock-, and LIVP 1.1.1-infected orthotopic GL261 gliomas in C57BL/6 mice. In cell culture studies virus replication and virus-mediated cell death of GL261 glioma cells was examined, as well as in BV-2 microglia and IMA2.1 astrocytes with M1 or M2 phenotypes. Co-culture experiments between BV-2 and GL261 cells and apoptosis/necrosis studies were performed. Organotypic slice cultures with implanted GL261 tumor spheres were used as additional cell culture system.
  
  
  RESULTS
  We discovered that orthotopic GL261 gliomas upon intracranial virus delivery did not support replication of LIVP 1.1.1, similar to VACV-infected brains without gliomas. In addition, recruitment of Iba1(+) microglia and GFAP(+) astrocytes to orthotopically implanted GL261 glioma sites occurred already without virus injection. GL261 cells in culture showed high virus replication, while replication in BV-2 and IMA2.1 cells was barely detectable. The reduced viral replication in BV-2 cells might be due to rapid VACV-induced apoptotic cell death. In BV-2 and IMA 2.1 cells with M1 phenotype a further reduction of virus progeny and virus-mediated cell death was detected. Application of BV-2 microglial cells with M1 phenotype onto organotypic slice cultures with implanted GL261 gliomas resulted in reduced infection of BV-2 cells, whereas GL261 cells were well infected.
  
  
  CONCLUSIONS
  Our results indicate that microglia and astrocytes, dependent on their activation state, may preferentially clear viral particles by immediate uptake after delivery. By acting as VACV traps they further reduce efficient virus infection of the tumor cells. These findings demonstrate that glia cells need to be taken into account for successful GBM therapy development.
authors.affiliation: Department of Biochemistry, Biocenter, University of Wuerzburg, Am Hubland, 97074, Würzburg, Germany. christina.kober@uni-wuerzburg.de.
authors.forename: Christina
authors.initials: C
authors.lastname: Kober
authors.affiliation: Department of Biochemistry, Biocenter, University of Wuerzburg, Am Hubland, 97074, Würzburg, Germany. Susannerohn@gmx.de.
authors.forename: Susanne
authors.initials: S
authors.lastname: Rohn
authors.affiliation: Department of Biochemistry, Biocenter, University of Wuerzburg, Am Hubland, 97074, Würzburg, Germany. Weibel_S@ukw.de.|Department of Anesthesia and Critical Care, University Hospital of Wuerzburg, Oberduerrbacher Str. 6, 97080, Würzburg, Germany. Weibel_S@ukw.de.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Weibel
authors.affiliation: Genelux Corporation, San Diego Science Center, 3030 Bunker Hill Street, San Diego, CA, 92109, USA. UlrikeGeissinger@genelux.com.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Geissinger
authors.affiliation: Department of Radiation Medicine and Applied Sciences, Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, CA, 92093, USA. chen_nanhai@yahoo.com.|Genelux Corporation, San Diego Science Center, 3030 Bunker Hill Street, San Diego, CA, 92109, USA. chen_nanhai@yahoo.com.
authors.forename: Nanhai G
authors.initials: NG
authors.lastname: Chen
authors.affiliation: Department of Biochemistry, Biocenter, University of Wuerzburg, Am Hubland, 97074, Würzburg, Germany. szalay@biozentrum.uni-wuerzburg.de.|Rudolf Virchow Center for Experimental Biomedicine and Institute for Molecular Infection Biology, University of Wuerzburg, 97080, Würzburg, Germany. szalay@biozentrum.uni-wuerzburg.de.|Department of Radiation Medicine and Applied Sciences, Rebecca and John Moores Comprehensive Cancer Center, University of California, San Diego, CA, 92093, USA. szalay@biozentrum.uni-wuerzburg.de.|Genelux Corporation, San Diego Science Center, 3030 Bunker Hill Street, San Diego, CA, 92109, USA. szalay@biozentrum.uni-wuerzburg.de.
authors.forename: Aladar A
authors.initials: AA
authors.lastname: Szalay
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000187:drug effects / Q000473:pathology* / Q000821:virology; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D005434:Flow Cytometry; D005910:Glioma / Q000473:pathology* / Q000821:virology*; D006801:Humans; D015552:Injections, Intralesional; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects / Q000473:pathology*; D009336:Necrosis; D050504:Oncolytic Viruses / Q000187:drug effects / Q000502:physiology*; D018874:Spheroids, Cellular / Q000187:drug effects / Q000473:pathology; D014616:Vaccinia virus / Q000187:drug effects / Q000502:physiology*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D008070:Lipopolysaccharides; D007371:Interferon-gamma