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Updated: Jul 15, 2026
Modeling Hypoxia/Reoxygenation Injury in Proximal Tubular Epithelial Cells
Published on: November 21, 2025
TLR2 is constitutively expressed within the kidney and participates in ischemic renal injury through both
Alana A Shigeoka1, Todd D Holscher, Andrew J King
1Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Abstract:
TLRs are an evolutionarily conserved family of cell membrane proteins believed to play a significant role in innate immunity and the response to tissue injury, including that induced by ischemia. TLR signaling pathways activate transcription factors that regulate expression of prosurvival proteins, as well as proinflammatory cytokines and chemokines through one of two proximal adapter proteins, MyD88 or Toll/IL-1R domain-containing adaptor-inducing IFN-beta (Trif). Our study defines the constitutive protein expression of TLR2 in kidneys of humans and mice, and provides insight into the signaling mechanisms by which a deficiency of TLR2 protects from ischemic organ injury. Our study compared and contrasted the effects of renal ischemia in wild-type mice and mice deficient in TLR2, MyD88, Trif, and MyD88xTrif. TLR2 protein was evident in many cell types in the kidney, including renal tubules of the outer stripe of the medulla, glomeruli, and in the renal vasculature. The pattern of protein expression was similar in humans and mice. The absence of TLR2, MyD88, and MyD88xTrif conferred both physiologic and histologic protection against sublethal ischemia at 24 h. Interestingly, TLR2-deficient mice were better protected from ischemic renal injury than those deficient for the adapter protein MyD88, raising the intriguing possibility that TLR-2-dependent/MyD88-independent pathways also contribute to kidney injury. We conclude that TLR2 protein is constitutively expressed in the kidney and plays an important role in the pathogenesis of acute ischemic injury by signaling both MyD88-dependent and MyD88-independent pathways.
Insights
Toll-like receptor 2 (TLR2) is present in the kidney and contributes to ischemic injury. Removing TLR2 or its signaling adapters protects kidneys from damage, suggesting new therapeutic targets for acute kidney injury.
Area of Science:
- Immunology
- Nephrology
- Cell Biology
Background:
- Toll-like receptors (TLRs) are crucial for innate immunity and tissue injury responses.
- TLR signaling involves adapter proteins MyD88 and Trif, influencing gene expression.
- Constitutive TLR2 expression in the kidney suggests a role in renal pathophysiology.
Purpose of the Study:
- To define TLR2 protein expression in human and mouse kidneys.
- To investigate the protective mechanisms of TLR2 deficiency against ischemic organ injury.
- To elucidate TLR2 signaling pathways in renal ischemia.
Main Methods:
- Compared renal ischemia effects in wild-type and knockout mice (TLR2, MyD88, Trif, MyD88xTrif).
- Assessed physiologic and histologic outcomes at 24 hours post-ischemia.
- Examined constitutive TLR2 protein expression in kidney tissues.
Main Results:
- TLR2 protein is constitutively expressed in human and mouse kidney cells, including tubules, glomeruli, and vasculature.
- Absence of TLR2, MyD88, or MyD88xTrif provided significant protection against ischemic renal injury.
- TLR2-deficient mice showed greater protection than MyD88-deficient mice, indicating MyD88-independent pathways.
Conclusions:
- TLR2 is constitutively expressed in the kidney and plays a key role in acute ischemic injury pathogenesis.
- TLR2 signaling contributes to kidney injury via both MyD88-dependent and -independent pathways.
- Targeting TLR2 may offer a therapeutic strategy for ischemic acute kidney injury.
