Immune cells promote paralytic disease in mice infected with enterovirus D68
Mikal A. Woods Acevedo, Jie Lan, Sarah Maya, Jennifer E. Jones, Isabella E. Bosco, John V. Williams, Megan Culler Freeman, Terence S. Dermody
Mikal A. Woods Acevedo, Jie Lan, Sarah Maya, Jennifer E. Jones, Isabella E. Bosco, John V. Williams, Megan Culler Freeman, Terence S. Dermody
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Research Article Immunology Infectious disease Virology

Immune cells promote paralytic disease in mice infected with enterovirus D68

Abstract

Enterovirus D68 (EV-D68) is associated with acute flaccid myelitis (AFM), a poliomyelitis-like illness causing paralysis in young children. However, the mechanisms of paralysis are unclear, and antiviral therapies are lacking. To better understand EV-D68 disease, we inoculated newborn mice intracranially to assess viral tropism, virulence, and immune responses. WT mice inoculated intracranially with a neurovirulent strain of EV-D68 showed infection of spinal cord neurons and developed paralysis. Spinal tissue from infected mice revealed increased levels of chemokines, inflammatory monocytes, macrophages, and T cells relative to those in controls, suggesting that immune cell infiltration influences pathogenesis. To define the contribution of cytokine-mediated immune cell recruitment to disease, we inoculated mice lacking CCR2, a receptor for several EV-D68–upregulated cytokines, or RAG1, which is required for lymphocyte maturation. WT, Ccr2–/–, and Rag1–/– mice had comparable viral titers in spinal tissue. However, Ccr2–/– and Rag1–/– mice were significantly less likely to be paralyzed relative to WT mice. Consistent with impaired T cell recruitment to sites of infection in Ccr2–/– and Rag1–/– mice, antibody-mediated depletion of CD4+ or CD8+ T cells from WT mice diminished paralysis. These results indicate that immune cell recruitment to the spinal cord promotes EV-D68–associated paralysis and illuminate potential new targets for therapeutic intervention.

Authors

Mikal A. Woods Acevedo, Jie Lan, Sarah Maya, Jennifer E. Jones, Isabella E. Bosco, John V. Williams, Megan Culler Freeman, Terence S. Dermody

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Figure 7

Mice lacking mature B and T cells have diminished EV-D68–induced paralysis relative to WT mice.

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Mice lacking mature B and T cells have diminished EV-D68–induced paralys...
Three-day-old WT or Rag1–/– mice were inoculated i.c. with PBS (mock) or EV-D68 IL52. (A) Brain and spinal tissue were resected at 3 dpi, and viral titers were determined by plaque assay. Data from WT mice are the same as those presented in Figure 5A, as these experiments were conducted concurrently. Dotted lines indicate the limit of detection. (B) Virus-inoculated mice were monitored daily and euthanized upon signs of paralysis. n = 16–21 mice per group. Data from WT mice are the same as those presented in Figure 5C, as these experiments were conducted concurrently. (C) Spinal tissue was resected 3 dpi and analyzed by Luminex protein assay. Data from WT mice are the same as those presented in Figure 2A, as these experiments were conducted concurrently. Cytokine concentrations are presented as mean values in pg/mL from 7–12 mice and shown as a heatmap normalized to concentrations in mock-inoculated mice. (D) Levels of CCL2, CCL7, and CCL12 are shown. Data are representative of 2–3 independent experiments. Each symbol represents an individual mouse. Error bars indicate mean ± SD. Mann-Whitney U test (A and D) or log-rank test (B): *P ≤ 0.05; **P ≤ 0.01.