University of Wisconsin–Madison

Peter Ferrazzano, MD

Peter Ferrazzano, MD Slide of the Week

Title: Developmental Profile of Microglia Phenotype and Gene Expression.

Legend: A. Double immunohistological staining for microglia (Iba1, green) and neurons (MAP2, red) in the hippocampus from postnatal day 2, 9, 30, and 60 mice is shown demonstrating the developmental profile of microglia morphology and regional distribution. Nuclei were stained with DAPI (blue). B. Quantification of the number microglia branch points and cell body volume are shown from microglia in P2, P9, P30 and P60 hippocampus, cortex and striatum (*p<0.05 vs. P2; n=8). C. Relative gene expression of TGFb receptor and MerTK is shown, as well as downstream effectors of both receptors: SERPINE1 and SOCS3 (* p<0.05 vs P2; n=8).

Citation: Zafer D, Abdul-Kareem S, Al-Subu R, Novak R, Bogost J, Chandrashekhar J, Chanana V, Cengiz P, Ferrazzano P.  Age-dependent differences in microglia during normal brain development and in response to cerebral ischemia. Presented at the 142nd Annual Meeting of the American Neurological Association, October 16, 2017, San Diego CA

Abstract: Immunostaining and microglia isolation via magnetic cell sorting was performed at P2, P9, P30 and P60 (P2, P9, P30, P60). Microglia branching and soma size were quantified using semiautomated software analysis (Imaris, Oxford Insturments). RT-PCR was performed on isolated microglia using a custom Taqman low-density array card to assess a panel of genes responsible for microglia function. Microglia demonstrated an increasingly branched morphology from P2-P30, associated with a progressive decrease in cell body size. The highly branched morphology seen in P30 and P60 mice was associated with a transition in the expression of genes in the transforming growth factor beta (TGFb) pathway and the mer tyrosine kinase (MERTK) pathway between P9 and P30. Microglia in P30 and P60 mice demonstrated increased expression of the TGFb receptor (TGFbr) and MerTK, and downstream signaling was increased in both pathways as evidenced by increased expression of SERPINE1 and the suppressor of cytokine signaling 3 (SOCS3), respectively.

About the Lab: By identifying MRI biomarkers in animal models of pediatric brain injury, Ferrazzano hopes to provide a means for selecting the patients most likely to benefit from a particular neuroprotective intervention in subsequent clinical trials. Basing patient selection on the physiologic target of therapy rather than simply the disease state will reduce the sample size needed, increase the likelihood of observing a drug effect, and facilitate the translation of promising neuroprotective interventions into clinical use.

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