The Foreign Body Response to Biomaterial Implants is reduced by co-inhibition of TLR2 and TLR4
1Materials Science and Engineering Program, University of Colorado Boulder, Boulder, CO USA.
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Summary
Toll-like receptors (TLRs) 2 and 4 are key to the foreign body response (FBR) against biomaterials. Blocking both TLR2 and TLR4 significantly reduces fibrous encapsulation, offering a therapeutic target for implantable materials.
Area of Science:
- Biomaterials Science
- Immunology
- Cell Biology
Background:
- The foreign body response (FBR) leads to fibrous encapsulation of implanted biomaterials.
- Protein adsorption initiates FBR, activating innate immune cells.
- The specific receptors and mechanisms driving material-dependent FBR remain unclear.
Purpose of the Study:
- To identify the primary receptors mediating the FBR to biomaterials.
- To elucidate the role of Toll-like receptors (TLRs) in initiating FBR.
- To determine if TLRs dictate the material-dependent nature of the FBR.
Main Methods:
- In vitro models using macrophages and neutrophils exposed to adsorbed plasma on various biomaterials.
- In vivo subcutaneous implantation in mice with genetic deletions of TLR2 and TLR4.
- Assessment of fibrous capsule formation and immune cell activation.
Main Results:
- Toll-like receptors (TLRs) 2 and 4 are critical for recognizing adsorbed proteins as damage-associated molecular patterns (DAMPs).
- Macrophages, not neutrophils, utilize TLR2/TLR4 to initiate FBR.
- Simultaneous deletion of TLR2 and TLR4 nearly abrogated FBR and eliminated material dependency in vivo.
Conclusions:
- TLR2 and TLR4 are necessary receptors for initiating the FBR to biomaterials.
- Macrophage recognition of DAMPs from adsorbed proteins, dependent on biomaterial type, drives FBR.
- Targeting TLR2 and TLR4 presents a promising strategy to mitigate FBR for diverse implantable materials.