Characterizing microglia activation: a spatial statistics approach to maximize information extraction

Summary Microglia play an important role in the pathology of CNS disorders, however, there remains significant uncertainty about the neuroprotective/degenerative role of these cells due to a lack of techniques to adequately assess their complex behaviour in response to injury. This talk briefly describes a novel technique for microglia analysis, combining improved immunohistological image analysis with spatial statistical techniques (Ripley-K function and Dixon's χ2-test). Using this approach, a comprehensive set of morphological parameters describing microglia activation status was developed to characterise microgliosis in a murine optic nerve injury model. In addition to monitoring global changes in microglia density, nearest neighbour distance, and regularity index, cluster analyses based on changes in soma size and roundness were used to yield novel insights into the behaviour of different microglia phenotypes. These methods should be considered a generic tool to quantitatively assess microglia activation status, to profile these phenotypic changes into microglia subpopulations, and to map their spatial distributions in virtually every CNS region and disease state.