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Updated: Feb 22, 2026
Electromagnetic Controlled Closed-Head Model of Mild Traumatic Brain Injury in Mice
Published on: September 28, 2022
Decreased Secondary Lesion Growth and Attenuated Immune Response after Traumatic Brain Injury in Tlr2/4 Mice
Sandro M Krieg1, Florian Voigt1,2, Pascal Knuefermann3
1Department of Neurosurgery, Technische Universität München, Munich, Germany.
Abstract:
Danger-associated molecular patterns are released by damaged cells and trigger neuroinflammation through activation of non-specific pattern recognition receptors, e.g., toll-like receptors (TLRs). Since the role of TLR2 and 4 after traumatic brain injury (TBI) is still unclear, we examined the outcome and the expression of pro-inflammatory mediators after experimental TBI in Tlr2/4 and wild-type (WT) mice. Tlr2/4 and WT mice were subjected to controlled cortical injury and contusion volume and brain edema formation were assessed 24 h thereafter. Expression of inflammatory markers in brain tissue was measured by quantitative PCR 15 min, 3 h, 6 h, 12 h, and 24 h after controlled cortical impact (CCI). Contusion volume was significantly attenuated in Tlr2/4 mice (29.7 ± 0.7 mm3 as compared to 33.5 ± 0.8 mm3 in WT; p < 0.05) after CCI while brain edema was not affected. Only interleukin (IL)-1β gene expression was increased after CCI in the Tlr2/4 relative to WT mice. Inducible nitric oxide synthetase, TNF, IL-6, and COX-2 were similar in injured WT and Tlr2/4 mice, while the increase in high-mobility group box 1 was attenuated at 6 h. TLR2 and 4 are consequently shown to potentially promote secondary brain injury after experimental CCI via neuroinflammation and may therefore represent a novel therapeutic target for the treatment of TBI.
Insights
Toll-like receptors 2 and 4 (TLR2/4) activation exacerbates traumatic brain injury (TBI) by promoting neuroinflammation. Targeting TLR2/4 may offer a new therapeutic strategy for TBI treatment.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Danger-associated molecular patterns (DAMPs) released by damaged cells initiate neuroinflammation via pattern recognition receptors like toll-like receptors (TLRs).
- The specific roles of TLR2 and TLR4 in the context of traumatic brain injury (TBI) remain incompletely understood.
Purpose of the Study:
- To investigate the impact of TLR2 and TLR4 on outcomes and pro-inflammatory mediator expression following experimental TBI.
- To elucidate the potential of TLR2 and TLR4 as therapeutic targets for TBI.
Main Methods:
- Experimental TBI was induced using controlled cortical impact (CCI) in wild-type (WT) and Tlr2/4 knockout mice.
- Contusion volume and brain edema were assessed 24 hours post-injury.
- Pro-inflammatory marker gene expression (including IL-1β, iNOS, TNF, IL-6, COX-2, and HMGB1) was quantified via qPCR at multiple time points.
Main Results:
- Tlr2/4 mice exhibited significantly reduced contusion volume compared to WT mice after CCI (29.7 vs. 33.5 mm³).
- Brain edema formation was not significantly different between genotypes.
- Interleukin-1β (IL-1β) gene expression was elevated in Tlr2/4 mice post-TBI, while high-mobility group box 1 (HMGB1) increase was attenuated at 6 hours.
Conclusions:
- TLR2 and TLR4 signaling appear to exacerbate secondary brain injury following experimental TBI, primarily through neuroinflammatory pathways.
- These findings suggest that TLR2 and TLR4 represent promising therapeutic targets for mitigating TBI-induced damage.
