Modulating inflammatory monocytes with a unique microRNA gene signature ameliorates murine ALS
Oleg Butovsky, … , Merit E. Cudkowicz, Howard L. Weiner
Oleg Butovsky, … , Merit E. Cudkowicz, Howard L. Weiner
Published August 6, 2012
Citation Information: J Clin Invest. 2012;122(9):3063-3087. https://doi.org/10.1172/JCI62636.
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Research Article Neuroscience

Modulating inflammatory monocytes with a unique microRNA gene signature ameliorates murine ALS

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive disease associated with neuronal cell death that is thought to involve aberrant immune responses. Here we investigated the role of innate immunity in a mouse model of ALS. We found that inflammatory monocytes were activated and that their progressive recruitment to the spinal cord, but not brain, correlated with neuronal loss. We also found a decrease in resident microglia in the spinal cord with disease progression. Prior to disease onset, splenic Ly6Chi monocytes expressed a polarized macrophage phenotype (M1 signature), which included increased levels of chemokine receptor CCR2. As disease onset neared, microglia expressed increased CCL2 and other chemotaxis-associated molecules, which led to the recruitment of monocytes to the CNS by spinal cord–derived microglia. Treatment with anti-Ly6C mAb modulated the Ly6Chi monocyte cytokine profile, reduced monocyte recruitment to the spinal cord, diminished neuronal loss, and extended survival. In humans with ALS, the analogous monocytes (CD14+CD16–) exhibited an ALS-specific microRNA inflammatory signature similar to that observed in the ALS mouse model, linking the animal model and the human disease. Thus, the profile of monocytes in ALS patients may serve as a biomarker for disease stage or progression. Our results suggest that recruitment of inflammatory monocytes plays an important role in disease progression and that modulation of these cells is a potential therapeutic approach.

Authors

Oleg Butovsky, Shafiuddin Siddiqui, Galina Gabriely, Amanda J. Lanser, Ben Dake, Gopal Murugaiyan, Camille E. Doykan, Pauline M. Wu, Reddy R. Gali, Lakshmanan K. Iyer, Robert Lawson, James Berry, Anna M. Krichevsky, Merit E. Cudkowicz, Howard L. Weiner

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Figure 14

Anti-Ly6C mAb treatment decreases infiltration of Ly6Chi monocytes into the spinal cord and attenuates neuronal loss.

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Anti-Ly6C mAb treatment decreases infiltration of Ly6Chi monocytes into ...
SOD1 mice were treated as described in Figure 12. (A) FACS analysis of Ly6C+ monocytes in the spinal cord of anti-Ly6C–treated SOD1 mice compared with the IC group 30 days after treatment. Cells were gated using Annexin V and 7-AAD to eliminate apoptotic and necrotic cells. Numbers represent the percentage of CD11b-gated cells in each respective quadrant as indicated. Pooled data from 5 mice are shown. (B) Significantly reduced proportion of Ly6C+ monocytes and increased numbers of CD39+ microglia among CD11b+ cells 50 days after α-Ly6C treatment. (C) Significant reduction in CD11b+CD169+ monocytes was detected after 50 days of α-Ly6C treatment. Numbers represent the percentage of cells in each gate. (D) Representative confocal images stained for NeuN (green; neurons), IBA1 (blue; myeloid cells), and CD169 (red; recruited monocytes) of whole mount lumbar axial sections of spinal cords from IC- and Ly6C-treated mice at the end stage (140 days old). Scale bar: 500 μm. Boxed areas showed insets at high magnification. Scale bars: 200 μm. (E) Quantitation of neurons (NeuN+) and recruited monocytes (IBA1+/CD169+) in ventral and dorsal horns in the spinal cord of SOD1 mice treated with isotype control or anti-Ly6C mAbs (n = 6–8 per group). Results are representative of 2 independent experiments. Error bars represent mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, Student’s t test (2-tailed).