IL-10 expression in pyramidal neurons after neuropathogenic coronaviral infection

Area of Science:

• Neuroscience
• Virology
• Immunology

Background:

• JHMV is a neuropathogenic virus.
• Mu-3 is a neuropathogenic strain of JHMV.
• Neuronal apoptosis in the hippocampus can be induced by various infections.

Purpose of the Study:

• To investigate the mechanism of pyramidal neuron apoptosis in the hippocampus after Mu-3 infection.
• To determine if Mu-3 directly infects pyramidal neurons or causes indirect damage.
• To analyze the role of cytokines in Mu-3-induced neuronal apoptosis.

Main Methods:

• Infection of mice with Mu-3 virus.
• Analysis of viral antigen distribution in the hippocampus.
• Detection of apoptotic cells using caspase 3 (Cas3) activation.
• Assessment of proinflammatory and anti-inflammatory cytokine expression.

Main Results:

• Apoptosis of pyramidal neurons in CA2 and CA3 subregions occurred 4-5 days post-inoculation.
• Viral antigens were primarily found in CD11b-positive cells outside the pyramidal layer; few pyramidal neurons were infected.
• A high number of apoptotic cells were uninfected, suggesting indirect mechanisms of cell death.
• No correlation was found between cytokine expression distribution and apoptotic subregions.
• The anti-inflammatory cytokine IL-10 was produced by CA2 and CA3 pyramidal neurons at 3 dpi, prior to observable damage.

Conclusions:

• Mu-3 virus induces indirect apoptosis in hippocampal pyramidal neurons.
• The observed neuronal apoptosis is likely mediated by inflammatory responses rather than direct viral infection.
• IL-10 production by pyramidal neurons may play a role in the early stages of the host response to Mu-3 infection.