Related Experiment Video
Updated: Jun 18, 2026
Development of an Insert Co-culture System of Two Cellular Types in the Absence of Cell-Cell Contact
Published on: July 17, 2016
Microglial MyD88 signaling regulates acute neuronal toxicity of LPS-stimulated microglia in vitro
1Perinatal Centre, Department of Physiology and Neuroscience, Sahlgrenska Academy, Gothenburg University, Goteborg, Sweden.
Abstract:
Although the role of microglial activation in neural injury remains controversial, there is increasing evidence for a detrimental effect in the immature brain, which may occur in response to release of neurotoxic substances including pro-inflammatory cytokines. However, the signaling mechanisms involved in microglial-induced neuronal cell death are unclear. Microglia isolated from the brains of wild-type (WT) or MyD88 knockout (KO) mice were exposed to PBS or the TLR4-ligand LPS (100 ng/mL) for 2, 6, 14, or 24 h, and the microglia-conditioned medium (MCM) collected. Detection of multiple inflammatory molecules in MCM was performed using a mouse 22-plex cytokine microbead array kit. Primary neuronal cultures were supplemented with the 14 or 24 h MCM, and the degree of neuronal apoptosis examined after exposure for 24 h. Results showed a rapid and sustained elevation in multiple inflammatory mediators in the MCM of WT microglia exposed to LPS, which was largely inhibited in MyD88 KO microglia. There was a significant increase in apoptotic death measured at 24 h in cultured neurons exposed to CM from either 14 or 24 h LPS-stimulated WT microglia (p<.05 vs. WT control). By contrast, there was no increase in apoptotic death in cultured neurons exposed to CM from 14 or 24 h LPS-stimulated MyD88 KO microglia (p=.15 vs. MyD88 KO control). These data suggest that MyD88-dependent activation of microglia by LPS causes release of factors directly toxic to neurons.
Insights
Myeloid differentiation factor 88 (MyD88)-dependent activation of microglia by lipopolysaccharide (LPS) releases neurotoxic factors. This MyD88-dependent pathway contributes to neuronal apoptosis, highlighting a key mechanism in brain injury.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglial activation's role in neural injury is debated, but evidence suggests detrimental effects in immature brains due to neurotoxic substances like pro-inflammatory cytokines.
- The specific signaling pathways driving microglial-induced neuronal cell death remain largely unknown.
Purpose of the Study:
- To investigate the signaling mechanisms underlying microglial-induced neuronal cell death.
- To determine the role of Myeloid differentiation factor 88 (MyD88) in mediating microglial responses to lipopolysaccharide (LPS) and subsequent neuronal apoptosis.
Main Methods:
- Primary microglia from wild-type (WT) or MyD88 knockout (KO) mice were stimulated with LPS.
- Microglia-conditioned medium (MCM) was collected and analyzed for inflammatory mediators using a 22-plex cytokine assay.
- Primary neuronal cultures were exposed to MCM, and neuronal apoptosis was quantified.
Main Results:
- LPS stimulation led to a rapid and sustained increase in inflammatory mediators in WT microglia MCM, largely absent in MyD88 KO microglia.
- Neurons exposed to MCM from LPS-stimulated WT microglia showed significantly increased apoptosis.
- Neurons exposed to MCM from LPS-stimulated MyD88 KO microglia did not exhibit increased apoptosis.
Conclusions:
- Myeloid differentiation factor 88 (MyD88)-dependent activation of microglia by lipopolysaccharide (LPS) results in the release of factors directly toxic to neurons.
- These findings implicate MyD88-dependent microglial activation as a significant contributor to neuronal cell death and potential brain injury.
