Journal Article

An Automated Method to Quantify Microglia Morphology and Application to Monitor Activation State Longitudinally In Vivo

Kozlowski, Cleopatra, Weimer, Robby M.

2012

Overview

Microglia are specialized immune cells of the brain. Upon insult, microglia initiate a cascade of cellular responses including a characteristic change in cell morphology. To study the dynamics of microglia immune response in situ, we developed an automated image analysis method that enables the quantitative assessment of microglia activation state within tissue based solely on cell morphology. Per cell morphometric analysis of fluorescently labeled microglia is achieved through local iterative threshold segmentation, which reduces errors caused by signal-to-noise variation across large volumes. We demonstrate, utilizing systemic application of lipopolysaccharide as a model of immune challenge, that several morphological parameters, including cell perimeter length, cell roundness and soma size, quantitatively distinguish resting versus activated populations of microglia within tissue comparable to traditional immunohistochemistry methods. Furthermore, we provide proof-of-concept data that monitoring soma size enables the longitudinal assessment of microglia activation in the mouse neocortex imaged via 2-photon in vivo microscopy. The ability to quantify microglia activation automatically by shape alone allows unbiased and rapid analysis of both fixed and in vivo central nervous system tissue.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Activation analysis / Animals / Antigens / Antigens, CD - metabolism / Antigens, Differentiation, Myelomonocytic - metabolism / Automation / Biology / Brain / Brain injury / Calcium-Binding Proteins - metabolism / Cell morphology / Cell size / Central nervous system / Central Nervous System - metabolism / CX3C Chemokine Receptor 1 / Cytology / Data processing / Dendritic cells / Fluorescence / Gene expression / Green Fluorescent Proteins - genetics / Green Fluorescent Proteins - metabolism / Image analysis / Image processing / Image segmentation / Immune response / Immune system / Immunohistochemistry / Immunohistochemistry - methods / Iterative methods / Lipopolysaccharides / Lipopolysaccharides - pharmacology / Medicine / Methods / Mice / Mice, Inbred C57BL / Mice, Transgenic / Microfilament Proteins - metabolism / Microglia / Microglia - cytology / Microglia - drug effects / Microglia - metabolism / Microscopy / Microscopy, Confocal - methods / Mitogens / Morphology / Morphometry / Neocortex / Nervous tissues / Physical characteristics / Receptors, Cytokine - genetics / Receptors, Cytokine - metabolism / Receptors, HIV - genetics / Receptors, HIV - metabolism / Reproducibility of Results / Rodents / Roundness / Segmentation / Shape / Technology application / Traumatic brain injury