Mechanism for the lethal effect of enterovirus A71 intracerebral injection in neonatal mice

Figures

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  Fig. 1. Astrocytes were involved in the lethal effect of EV-A71 intracerebral injection in neonatal mice. Proliferation of the virus in neonatal (a) and adult (b) mice brain. c Representative HE staining of pathological lesions in brainstem, including glial cell proliferation and glial nodule formation (black arrows), vascular congestion and lymphocyte infiltration (red arrows), and swollen and loose arrangement cells (blue arrows). d Viral antigen expression in the brainstem tissues from EV-A71-infected neonatal mice, scale bars are shown at bottom right. e Immunofluorescence confocal microscopy observations of astrocytes (or neurons) and EV-A71 antigen in brainstem tissues from infected neonatal mice, scale bar = 10 μm.

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  Fig. 2. The modulation of cytokine release from astrocytes stimulated by virus in vitro. a The astrocytes from neonatal mice were grown on glass slides and stained with an anti-GFAP antibody; scale bar = 50 μm. Proliferations of the virus in cultured mouse astrocytes (b) and Vero cells (c) were measured based on virus titration from 0.5 to 72 h post infection. d Microscopy observations of EV-A71-infected cultured mice astrocytes, images are shown at ×400 magnification. e Immunofluorescence confocal microscopy observations of astrocytes and EV-A71 antigen in cultured mouse astrocytes; scale bar = 50 μm. f Detection of the presence of EV-A71 negative-stranded RNA in cells (black arrow). M marker; AS astrocyte; Vero Vero cells. g IL-6 released by astrocytes from 6 to 64 h post infection. **p ≤ 0.01 compared with the corresponding control group.

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  Fig. 3. Upregulated cytokines and neurotransmitters in the brains of infected neonatal mice compared with the brains of adult mice in vivo. IL-6 (a, b) and adrenaline (c, d) detection in brainstem homogenates from EV-A71 infected neonatal and adult mice. AD adrenaline.

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  Fig. 4. IL-6 and adrenaline mediated the lethal effect in neonatal mice injected intracerebrally with EV-A71. a IL-6 (1 ng/mouse, ic) and b adrenaline (1 μg/mouse, ic) decreased the survival rate of neonatal mice infected with FY-22. c An anti-IL-6 neutralizing antibody (20 ng/mouse, ic), and d the adrenergic-antagonist phenoxybenzamine (500 ng/mouse, sc) increased the survival rate of EV-A71-infected suckling mice. AD adrenaline. *p < 0.05 in comparison to the AD group; #p < 0.05 in comparison to the corresponding FY-23 group.