Neural precursor cell–secreted TGF-β2 redirects inflammatory monocyte-derived cells in CNS autoimmunity
Donatella De Feo, … , Melanie Greter, Gianvito Martino
Donatella De Feo, … , Melanie Greter, Gianvito Martino
Published September 25, 2017
Citation Information: J Clin Invest. 2017;127(11):3937-3953. https://doi.org/10.1172/JCI92387.
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Research Article Autoimmunity

Neural precursor cell–secreted TGF-β2 redirects inflammatory monocyte-derived cells in CNS autoimmunity

Abstract

In multiple sclerosis, the pathological interaction between autoreactive Th cells and mononuclear phagocytes in the CNS drives initiation and maintenance of chronic neuroinflammation. Here, we found that intrathecal transplantation of neural stem/precursor cells (NPCs) in mice with experimental autoimmune encephalomyelitis (EAE) impairs the accumulation of inflammatory monocyte-derived cells (MCs) in the CNS, leading to improved clinical outcome. Secretion of IL-23, IL-1, and TNF-α, the cytokines required for terminal differentiation of Th cells, decreased in the CNS of NPC-treated mice, consequently inhibiting the induction of GM-CSF–producing pathogenic Th cells. In vivo and in vitro transcriptome analyses showed that NPC-secreted factors inhibit MC differentiation and activation, favoring the switch toward an antiinflammatory phenotype. Tgfb2–/– NPCs transplanted into EAE mice were ineffective in impairing MC accumulation within the CNS and failed to drive clinical improvement. Moreover, intrathecal delivery of TGF-β2 during the effector phase of EAE ameliorated disease severity. Taken together, these observations identify TGF-β2 as the crucial mediator of NPC immunomodulation. This study provides evidence that intrathecally transplanted NPCs interfere with the CNS-restricted inflammation of EAE by reprogramming infiltrating MCs into antiinflammatory myeloid cells via secretion of TGF-β2.

Authors

Donatella De Feo, Arianna Merlini, Elena Brambilla, Linda Ottoboni, Cecilia Laterza, Ramesh Menon, Sundararajan Srinivasan, Cinthia Farina, Jose Manuel Garcia Manteiga, Erica Butti, Marco Bacigaluppi, Giancarlo Comi, Melanie Greter, Gianvito Martino

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Figure 11

NPC-secreted TGF-β2 is nonredundant for the therapeutic effect.

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NPC-secreted TGF-β2 is nonredundant for the therapeutic effect. (A and B...
(A and B) Representative immunostainings showing similar localization of GFP+ Tgfb2+/+ (A) and Tgfb2–/– (B) eNPCs (green) in meningeal perivascular areas in proximity to CD11b+ cells (red). Nuclei stained with DAPI (blue). Scale bars: 25 μm. (C) Left: Clinical scores of EAE mice treated with intrathecal injection of PBS (black dots), Tgfb2+/+ eNPCs (red dots), or Tgfb2–/– eNPCs (gray dots) at the peak of the disease (arrow) (n = 10 mice per group). Each point represents the mean ± SEM. *P ≤ 0.05, 2-way ANOVA with Bonferroni’s post-test. Right: Linear regression curves from day of treatment (18 dpi); dashed lines indicate 95% CI. ***P ≤ 0.001. (D–F) Quantification of spinal cord demyelination (Luxol fast blue staining) (D), axonal loss (Bielschowsky silver staining) (E), and inflammatory infiltration (H&E staining) (F) at 60 dpi in EAE mice treated with Tgfb2–/– eNPCs (gray bars), Tgfb2+/+ eNPCs (white bars), and PBS (black bars) (n = 20 sections per mouse, 4 mice per group). Data are mean ± SEM and represent the percentage area of damage per total section area. *P ≤ 0.05, unpaired t test. (G) Flow cytometry of CNS leukocytes from EAE mice treated as in C, assessed at day 7 after transplantation (n = 4 mice per group). Frequencies of inflammatory MCs (CD45hiCD11b+Ly6G–Ly6ChiCD11c+MHC-II+) are shown in the plots and quantified in the graph. Black bars, PBS; white bars, Tgfb2+/+ eNPCs; gray bars, Tgfb2–/– eNPCs. (H) Levels of MHC-II on microglia in EAE mice treated with PBS (black line), Tgfb2+/+ eNPCs (red line), and Tgfb2–/– eNPCs (gray line) at the same time point as I are shown in the histogram and quantified in the graph (n = 4 per group). *P ≤ 0.05, 1-way ANOVA followed by Bonferroni’s post-test. (I) Confocal images and frequency of phospho-SMAD2+ cells over CD11b+ cells in the spinal cord of EAE mice treated with PBS, Tgfb2+/+ eNPCs, and Tgfb2–/– eNPCs, 7 days after treatment (n = 8–12 inflammatory infiltrates per mouse; n = 3 mice per group). ***P ≤ 0.001, 1-way ANOVA followed by Bonferroni’s post-test. Data are mean ± SEM and are representative of 2 independent experiments.