title: Time lapse in vivo microscopy reveals distinct dynamics of microglia-tumor environment interactions-a new role for the tumor perivascular space as highway for trafficking microglia.
abstract: Microglial cells are critical for glioma growth and progression. However, only little is known about intratumoral microglial behavior and the dynamic interaction with the tumor. Currently the scarce understanding of microglial appearance in malignant gliomas merely originates from histological studies and in vitro investigations. In order to understand the pattern of microglia activity, motility and migration we designed an intravital study in an orthotopic murine glioma model using CX3CR1-eGFP(GFP/wt) mice. We analysed the dynamics of intratumoral microglia accumulation and activity, as well as microglia/tumor blood vessel interaction by epi-illumination and 2-photon laser scanning microscopy. We further investigated cellular and tissue function, including the enzyme activity of intratumoral and microglial NADPH oxidase measured by in vivo fluorescence lifetime imaging. We identified three morphological phenotypes of tumor-associated microglia cells with entirely different motility patterns. We found that NADPH oxidase activation is highly divergent in these microglia subtypes leading to different production levels of reactive oxygen species (ROS). We observed that microglia motility is highest within the perivascular niche, suggesting relevance of microglia/tumor blood vessel interactions. In line, reduction of tumor blood vessels by antivascular therapy confirmed the relevance of the tumor vessel compartment on microglia biology in brain tumors. In summary, we provide new insights into in vivo microglial behavior, regarding both morphology and function, in malignant gliomas. GLIA 2016;64:1210-1226.
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin, Germany.
authors.forename: Simon Heinrich
authors.initials: SH
authors.lastname: Bayerl
authors.affiliation: German Rheumatism Research Center Berlin, Berlin, Germany, Charitéplatz 1, Berlin, Germany.
authors.forename: Raluca
authors.initials: R
authors.lastname: Niesner
authors.affiliation: German Rheumatism Research Center Berlin, Berlin, Germany, Charitéplatz 1, Berlin, Germany.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Cseresnyes
authors.affiliation: Department of Neuropathology, Charité Universitätsmedizin Berlin, Charitéplatz 1, Berlin, Germany.
authors.forename: Helena
authors.initials: H
authors.lastname: Radbruch
authors.affiliation: German Rheumatism Research Center Berlin, Berlin, Germany, Charitéplatz 1, Berlin, Germany.
authors.forename: Julian
authors.initials: J
authors.lastname: Pohlan
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin, Germany.
authors.forename: Susan
authors.initials: S
authors.lastname: Brandenburg
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin, Germany.
authors.forename: Marcus Alexander
authors.initials: MA
authors.lastname: Czabanka
authors.affiliation: Department of Neurosurgery, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Vajkoczy
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D000073883:CX3C Chemokine Receptor 1 / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology*; D004195:Disease Models, Animal; D059647:Gene-Environment Interaction; D005910:Glioma / Q000000981:diagnostic imaging / Q000473:pathology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D000069416:Intravital Microscopy; D019394:Ki-67 Antigen / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D017628:Microglia / Q000473:pathology* / Q000502:physiology; D018613:Microscopy, Confocal; D009249:NADP / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000209:etiology / Q000473:pathology; D023041:Xenograft Model Antitumor Assays
chemical_list: D000073883:CX3C Chemokine Receptor 1; C471885:Cx3cr1 protein, mouse; D019394:Ki-67 Antigen; D049452:Green Fluorescent Proteins; D009249:NADP
keywords: 2 photon microscopy; NADPH oxidase; angiogenesis; glioma; microglia motility