TNF and infection: If microglia are activated rapidly following infection or insult, they can release cytotoxic molecules such as proinflammatory cytokines (e.g., interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α), reactive oxygen species (ROS) and proteinases to induce neurotoxicity and neuronal apoptosis (Dheen et al. 2007).