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Updated: May 21, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Temperature- and time-dependent changes in TLR2-activated microglial NF-κB activity and concentrations of
Tomohiro Matsui1, Moe Tasaki, Takahiro Yoshioka
1Department of Laboratory Sciences, Yamaguchi University Graduate School of Medicine, 1-1-1 Minami-kogushi, Ube, Yamaguchi 755-8505, Japan. giants@yamaguchi-u.ac.jp
Purpose:
Therapeutic hypothermia protects neurons following injury to the central nervous system (CNS). Microglia express toll-like receptors (TLRs) that play significant roles in pathological processes in sterile CNS injury. We have examined the effects of culture temperature on the TLR2-activated microglial production of cytokines and nitric oxide (NO), which are known to be associated with CNS damage, and the possible involvement of nuclear factor-κB (NF-κB) activation underlying such effects.
Methods:
Rat microglia were cultured with a selective TLR2 agonist, Pam(3)CSK(4), under hypothermic, normothermic, and hyperthermic conditions, and with Pam(3)CSK(4) in the presence of a NF-κB activation inhibitor at 37 °C. Cytokine and NO levels and NF-κB p65 activation were measured.
Results:
The production of tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), and NO and the activation of NF-κB p65 were reduced by hypothermia, but augmented by hyperthermia at 3-6, 24-48, 48, and 0.5 h, post-treatment initiation, respectively. Pharmacological inhibition of NF-κB activation impaired the Pam(3)CSK(4)-induced TNF-α, IL-10, and NO production.
Conclusions:
In TLR2-activated microglia, hypothermia reduced, while hyperthermia increased, the early activation of NF-κB and the subsequent NF-κB-mediated production of TNF-α, IL-10, and NO in a time-dependent manner, suggesting that attenuation of these factors via suppression of NF-κB in microglia is one possible neuroprotective mechanism of therapeutic hypothermia. Moreover, temperature-dependent changes in microglial TNF-α production during the early phase and IL-10 and NO production during the late phase indicate that these factors might be useful as clinical markers to monitor hypothermia-related neuronal protection and hyperthermia-related neuronal injury.
Insights
Therapeutic hypothermia reduces microglial production of TNF-α, IL-10, and NO by inhibiting NF-κB activation. This suggests a neuroprotective mechanism, with these factors potentially serving as clinical markers for hypothermia-related neuronal protection or injury.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Therapeutic hypothermia offers neuroprotection in central nervous system (CNS) injuries.
- Microglia, immune cells in the CNS, express toll-like receptors (TLRs) involved in CNS injury pathology.
- TLR2 activation in microglia can lead to the production of cytokines and nitric oxide (NO), contributing to CNS damage.
Purpose of the Study:
- To investigate the impact of culture temperature on TLR2-activated microglial production of cytokines (TNF-α, IL-10) and NO.
- To explore the role of nuclear factor-κB (NF-κB) activation in temperature-dependent microglial responses.
- To determine potential neuroprotective mechanisms of therapeutic hypothermia related to microglial activation.
Main Methods:
- Rat microglia were stimulated with a TLR2 agonist (Pam3CSK4) under hypothermic, normothermic, and hyperthermic conditions.
- NF-κB activation was assessed, along with the production of TNF-α, IL-10, and NO.
- Experiments were also conducted with an NF-κB activation inhibitor at 37°C to confirm pathway involvement.
Main Results:
- Hypothermia significantly reduced the production of TNF-α, IL-10, and NO, as well as NF-κB p65 activation.
- Hyperthermia conversely augmented the production of these inflammatory mediators and NF-κB activation.
- Inhibition of NF-κB activation abolished Pam3CSK4-induced TNF-α, IL-10, and NO production, confirming NF-κB's central role.
Conclusions:
- Hypothermia suppresses TLR2-mediated NF-κB activation and subsequent inflammatory mediator production in microglia, indicating a neuroprotective mechanism.
- Hyperthermia exacerbates these responses, suggesting potential for neuronal injury.
- Temperature-dependent changes in TNF-α, IL-10, and NO production may serve as clinical biomarkers for monitoring therapeutic hypothermia efficacy or hyperthermia-induced injury.
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