TGF-β1 modulates microglial phenotype and promotes recovery after intracerebral hemorrhage
Roslyn A. Taylor, … , J. Christopher Love, Lauren H. Sansing
Roslyn A. Taylor, … , J. Christopher Love, Lauren H. Sansing
Published January 3, 2017; First published November 28, 2016
Citation Information: J Clin Invest. 2017;127(1):280-292. https://doi.org/10.1172/JCI88647.
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Research Article Inflammation Neuroscience

TGF-β1 modulates microglial phenotype and promotes recovery after intracerebral hemorrhage

Abstract

Intracerebral hemorrhage (ICH) is a devastating form of stroke that results from the rupture of a blood vessel in the brain, leading to a mass of blood within the brain parenchyma. The injury causes a rapid inflammatory reaction that includes activation of the tissue-resident microglia and recruitment of blood-derived macrophages and other leukocytes. In this work, we investigated the specific responses of microglia following ICH with the aim of identifying pathways that may aid in recovery after brain injury. We used longitudinal transcriptional profiling of microglia in a murine model to determine the phenotype of microglia during the acute and resolution phases of ICH in vivo and found increases in TGF-β1 pathway activation during the resolution phase. We then confirmed that TGF-β1 treatment modulated inflammatory profiles of microglia in vitro. Moreover, TGF-β1 treatment following ICH decreased microglial Il6 gene expression in vivo and improved functional outcomes in the murine model. Finally, we observed that patients with early increases in plasma TGF-β1 concentrations had better outcomes 90 days after ICH, confirming the role of TGF-β1 in functional recovery from ICH. Taken together, our data show that TGF-β1 modulates microglia-mediated neuroinflammation after ICH and promotes functional recovery, suggesting that TGF-β1 may be a therapeutic target for acute brain injury.

Authors

Roslyn A. Taylor, Che-Feng Chang, Brittany A. Goods, Matthew D. Hammond, Brian Mac Grory, Youxi Ai, Arthur F. Steinschneider, Stephen C. Renfroe, Michael H. Askenase, Louise D. McCullough, Scott E. Kasner, Michael T. Mullen, David A. Hafler, J. Christopher Love, Lauren H. Sansing

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Figure 1

Microglia downregulate proinflammatory genes by 7 days after ICH.

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Microglia downregulate proinflammatory genes by 7 days after ICH. (A) Mu...
(A) Multiplex assays (IL-6, CCL2, IL-17, IFN-γ, IL-10, IL-4, IL-13) and ELISA assays (TGF-β1 and BDNF) were performed on brain tissue homogenates of the perihematomal regions of WT mice at baseline and 1, 3, 7, 10, and 14 days after ICH. Individual mice represented as one dot with the line at the median value. n = 4–7 mice/time point. (B) Gating strategy to isolate microglia for cell sorting experiments. Samples were gated on live singlets prior to leukocytes being found by forward and side scatter. Samples were then gated on side scatter, CD45int to separate microglia from peripheral leukocytes and then on CD45int, CD11b+ to obtain microglia. (C) qRT-PCR for Il6 and Ccl2 was performed on cell-sorted microglia from CX3CR1-heterozygous mice at baseline, 12 hours, and 1, 3, 7, and 14 days after ICH. Means graphed with SEM; n = 7–16. Results in A and C were analyzed by ANOVA followed by Tukey’s post hoc test; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.