Biology subjects

Buxton, L.

Publications and source records attributed to Buxton, L..

2 recordsLinked to original sources

bioRxiv2025

Investigating the role of cortical microglia in a mouse model of viral infection-induced seizures

Microglia, resident immune sentinels in the brain, are crucial in responding to tissue damage, infection, damage signals like purines (ATP/ ADP), and clearing cellular debris. It is currently unknown how microglial reactivity progresses and contributes to seizure development following Theilers Murine Encephalomyelitis Virus (TMEV) infection. Previously, our group has demonstrated that purinergic signaling in microglia is disrupted in the hippocampus of TMEV-infected mice. However, whether reactive cortical microglia also exhibit changes in purinergic signaling, cytokine levels, and purinergic receptors are unknown. Thus, we seek to evaluate region-based differences in microglial reactivity in the TMEV model. We employed a custom triple transgenic mouse line expressing tdTomato and GCaMP6f under a CX3CR1 Cre promoter and exogenously applied ATP/ADP to acute brain slice preparations from TMEV-infected mice and controls. Interestingly and in contrast to what is observed in hippocampus, we found that despite microglial reactivity in the cortex, microglia can respond to purinergic damage signals and engage calcium signaling pathways, comparable to PBS controls. Using a cytokine panel, we also found that pro-inflammatory cytokine levels (TNF-, IL-1 and IFN-{gamma}) are brain-region dependent in mice infected with TMEV. Using RNAScope-FISH, we observed increases in expression of purinergic receptors responsible for microglial motility (P2Y12R) and inflammation (P2X7R) in the cortex. Collectively our results suggest that following TMEV infection, microglial response to novel damage signals, as well as the production of proinflammatory cytokines, varies as a function of brain region.

neuroscience↗

bioRxiv2024

Reactive microglia fail to respond to environmental damage signals in a viral-induced mouse model of temporal lobe epilepsy

Microglia are highly adaptable innate immune cells that rapidly respond to damage signals in the brain through adoption of a reactive phenotype and production of defensive inflammatory cytokines. Microglia express a distinct transcriptome, encoding receptors that allow them to dynamically respond to pathogens, damage signals, and cellular debris. Expression of one such receptor, the microglia-specific purinergic receptor P2ry12, is known to be downregulated in reactive microglia. Here, we explore the microglial response to purinergic damage signals in reactive microglia in the TMEV mouse model of viral brain infection and temporal lobe epilepsy. Using two-photon calcium imaging in acute hippocampal brain slices, we found that the ability of microglia to detect damage signals, engage calcium signaling pathways, and chemoattract towards laser-induced tissue damage was dramatically reduced during the peak period of seizures, cytokine production, and infection. Using combined RNAscope in situ hybridization and immunohistochemistry, we found that during this same stage of heightened infection and seizures, microglial P2ry12 expression was reduced, while the pro-inflammatory cytokine TNF-a expression was upregulated in microglia, suggesting that the depressed ability of microglia to respond to new damage signals via P2ry12 occurs during the time when local elevated cytokine production contributes to seizure generation following infection. Therefore, changes in microglial purinergic receptors during infection likely limit the ability of reactive microglia to respond to new threats in the CNS and locally contain the scale of the innate immune response in the brain.

neuroscience↗