Related Experiment Video
Updated: Jan 2, 2026
Real-Time Imaging of CCL5-Induced Migration of Periosteal Skeletal Stem Cells in Mice
Published on: September 16, 2020
Knockout of TLR4 promotes fracture healing by activating Wnt/β-catenin signaling pathway
Cunju Zhao1, Tao Yu1, Qingjun Dou2
1Department of Spinal Surgery, Qilu Hospital of ShanDong University, No. 107, Cultural West Road, Jinan City, Shandong Province, 250012, China; Department Of Orthopedics, Liaocheng People's Hospital, No. 67, Dongchang West Road, Liaocheng City, Shandong Province, 252000, China.
Objectives:
The aim of this study was to investigate the effect of Toll like receptor 4 (TLR4) on fracture healing.
Methods:
The open tibial fracture models in TLR4 knockout (TLR4-/-) and wild type (WT) C57BL-6 J mice were established. The radiological examination, tartrate-resistant acid phosphatase (TRAP) staining, Micro-CT scan and biological torsion test were performed on 7, 14 and 21 days after operation. Enzyme Linked Immunosorbent Assay (ELISA) kit was used to detect the expression levels of tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β) and interleukin 6 (IL-6). Western blotting was used to detect the expression of β-catenin, Wingless-type MMTV integration site family, member 4 and 5B (Wnt4 and Wnt5B), proliferating cell nuclear antigen (PCNA) and bone morphogenetic protein-2 (BMP-2) of the callus tissue obtained from mice.
Results:
TLR4 knockout promoted fracture healing, reduced the number of osteoclasts, increased bone callus volume (BV) and callus mineralized volume fraction (BV/TV%) (P < 0.05), increased the maximum torque and torsional stiffness of callus (P < 0.05), reduced TNF-α, IL-1β and IL-6 expression (P < 0.01), and increased the expression levels of β-catenin, Wnt4, Wnt5B, PCNA and BMP-2 (P < 0.01).
Conclusion:
TLR4 knockout reduced inflammatory and promoted fracture healing by activating Wnt/β-catenin signaling pathway.
Insights
Toll like receptor 4 (TLR4) knockout enhances fracture healing by reducing inflammation and promoting bone formation. This involves activating the Wnt/β-catenin signaling pathway, leading to improved bone callus quality and mechanical strength.
Area of Science:
- Orthopedics
- Immunology
- Molecular Biology
Background:
- Fracture healing is a complex biological process influenced by inflammatory signaling.
- Toll like receptor 4 (TLR4) plays a role in innate immunity and inflammation.
- The specific impact of TLR4 on fracture healing requires further elucidation.
Purpose of the Study:
- To investigate the role of Toll like receptor 4 (TLR4) in the process of fracture healing.
- To determine the effects of TLR4 deficiency on bone callus formation and mechanical properties.
Main Methods:
- Establishment of open tibial fracture models in TLR4 knockout and wild-type mice.
- Radiological examination, Micro-CT scans, and mechanical torsion tests were performed.
- Analysis of inflammatory cytokine expression (TNF-α, IL-1β, IL-6) and key signaling molecules (Wnt/β-catenin pathway, PCNA, BMP-2) via ELISA and Western blotting.
Main Results:
- TLR4 knockout significantly promoted fracture healing, evidenced by increased bone callus volume and mineralized volume fraction.
- Mechanical testing showed enhanced maximum torque and torsional stiffness in TLR4-deficient mice.
- Reduced expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and increased expression of Wnt/β-catenin pathway components, PCNA, and BMP-2 were observed.
Conclusions:
- TLR4 knockout accelerates fracture healing by suppressing inflammation.
- Activation of the Wnt/β-catenin signaling pathway is a key mechanism by which TLR4 deficiency promotes bone repair.
- Targeting TLR4 may offer a therapeutic strategy for improving fracture healing outcomes.
Related Concept Videos
02:54Canonical Wnt Signaling Pathway
01:41Non-Canonical Wnt Signaling Pathways
01:27Fractures: Bone Repair
Minor fractures with no bone displacement are treated by immobilizing the fractured bone using a cast or splint. However, in the case of fractures with displaced bones, the broken bones are repositioned before immobilization to ensure successful healing without deformation and loss of function. The realignment of fractured bone ends is performed through a process called reduction. If the...
01:16TGF - β Signaling Pathway
01:28Phases of Wound Repair
Formation of Blood Clot
In case of deep injuries, trauma to blood vessels results in blood loss. In the meantime, phospholipids released from the ruptured endothelial cellular membrane are converted into arachidonic...