• • 
  Introduction
• • 
  TLR signalling
• • 
  Endogenous TLR ligands
• • 
  Biological significance of signalling triggered by endogenous TLR ligands

  • ‐ 
    Ischemia and reperfusion injury
  • ‐ 
    Tissue repair and regeneration
  • ‐ 
    Endogenous ligands and autoimmune diseases
  • ‐ 
    Tumorigenesis and tumour progression
  • ‐ 
    Other inflammatory responses mediated by endogenous TLR ligands
• • 
  Conclusions

Toll‐like receptors (TLRs), a family of pattern recognition receptors, recognize and respond to conserved components of microbes and play a crucial role in both innate and adaptive immunity. In addition to binding exogenous ligands derived from pathogens, TLRs interact with endogenous molecules released from damaged tissues or dead cells and regulate many sterile inflammation processes. Putative endogenous TLR ligands include proteins and peptides, polysaccharides and proteoglycan, nucleic acids and phospholipids, which are cellular components, particularly extracellular matrix degradation products. Accumulating evidence demonstrates that endogenous ligand‐mediated TLR signalling is involved in pathological conditions such as tissue injury, repair and regeneration; autoimmune diseases and tumorigenesis. The ability of TLRs to recognize endogenous stimulators appears to be essential to their function in regulating non‐infectious inflammation. In this review, we summarize current knowledge of endogenous TLR ligands and discuss the biological significance of TLR signalling triggered by endogenous ligands in several sterile inflammation conditions.