Deficiency of Socs3 leads to brain-targeted experimental autoimmune encephalomyelitis via enhanced neutrophil activation and ROS production
Zhaoqi Yan, Wei Yang, Luke Parkitny, Sara A. Gibson, Kevin S. Lee, Forrest Collins, Jessy S. Deshane, Wayne Cheng, Amy S. Weinmann, Hairong Wei, Hongwei Qin, Etty N. Benveniste
Zhaoqi Yan, Wei Yang, Luke Parkitny, Sara A. Gibson, Kevin S. Lee, Forrest Collins, Jessy S. Deshane, Wayne Cheng, Amy S. Weinmann, Hairong Wei, Hongwei Qin, Etty N. Benveniste
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Research Article Inflammation

Deficiency of Socs3 leads to brain-targeted experimental autoimmune encephalomyelitis via enhanced neutrophil activation and ROS production

Abstract

Dysregulation of the JAK/STAT signaling pathway is associated with multiple sclerosis (MS) and its mouse model, experimental autoimmune encephalomyelitis (EAE). Suppressors of cytokine signaling (SOCS) negatively regulate the JAK/STAT pathway. We previously reported a severe, brain-targeted, atypical form of EAE in mice lacking Socs3 in myeloid cells (Socs3ΔLysM), and that this atypical EAE is associated with cerebellar neutrophil infiltration. There is emerging evidence that neutrophils are detrimental in the pathology of MS/EAE; however, their exact function is unclear. Here we demonstrate that neutrophils from the cerebellum of Socs3ΔLysM mice show a hyperactivated phenotype with excessive production of reactive oxygen species (ROS) at the peak of EAE. Neutralization of ROS in vivo delayed the onset and reduced severity of atypical EAE. Mechanistically, Socs3-deficient neutrophils exhibited enhanced signal transducer and activator of transcription 3 (STAT3) activation, a hyperactivated phenotype in response to granulocyte colony–stimulating factor (G-CSF), and upon G-CSF priming, increased ROS production. Neutralization of G-CSF in vivo significantly reduced the incidence and severity of the atypical EAE phenotype. Overall, our work elucidates that hypersensitivity of G-CSF/STAT3 signaling in Socs3ΔLysM mice leads to atypical EAE by enhanced neutrophil activation and increased oxidative stress, which may explain the detrimental role of G-CSF in MS patients.

Authors

Zhaoqi Yan, Wei Yang, Luke Parkitny, Sara A. Gibson, Kevin S. Lee, Forrest Collins, Jessy S. Deshane, Wayne Cheng, Amy S. Weinmann, Hairong Wei, Hongwei Qin, Etty N. Benveniste

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Figure 2

ROS plays an important role in the pathology of atypical EAE.

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ROS plays an important role in the pathology of atypical EAE. EAE was in...
EAE was induced in Socs3ΔLysM mice. Beginning on day 7, ROS scavenger cocktail (FeTPPS 20 mg/kg, PBN 50 mg/kg, and EUK-134 15 mg/kg) was administered i.p. twice per day for 5 days. (A) Atypical EAE score of mice treated with ROS scavenger cocktail (n = 14) or vehicle control (n = 14). Mice that did not develop EAE (classical or atypical) were excluded. (B) Demyelination was assessed on day 14 and quantified by Black Gold staining (n = 3). Arrows indicate demyelinated regions. (C) On days 13 to 14, immune cells from the cerebellum were isolated by Percoll gradient, and the frequencies of microglia (CD45loCD11b+), neutrophils (CD45+CD11b+Ly6CloLy6G+), Ly6C+ monocytic cells (CD45+CD11b+Ly6C+Ly6G–), Ly6C– monocytic cells (CD45+CD11b+Ly6C–Ly6G–), and CD3+ T cells (CD45+CD11b–CD3+) were determined (n = 6). (D) RNA was isolated from whole cerebellum on day 13, and Hmox1 expression was analyzed by qRT-PCR (n = 5). All error bars represent ± SEM. *P < 0.05, and **P < 0.01 by Mann-Whitney rank-sum test (A) or 2-tailed Student’s t test (B–D).