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Critical Reviews™ in Immunology
IF: 1.352 5-Year IF: 3.347 SJR: 1.022 SNIP: 0.55 CiteScore™: 2.19

ISSN Print: 1040-8401
ISSN Online: 2162-6472

Critical Reviews™ in Immunology

DOI: 10.1615/CritRevImmunol.v23.i12.20
30 pages

Activation of Mammalian Toll-like Receptors by Endogenous Agonists

Geoffrey B. Johnson
Departments of Immunology, Mayo Clinic, Rochester, MN 55905
Gregory J. Brunn
Departments of Immunology, Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905
Jeffrey L. Platt
Departments of Immunology, Surgery, and Pediatrics, Mayo Clinic, Rochester, MN 55905


Toll-like receptors activate innate and adaptive immune systems in mammals. This ancient family of receptors has been evolving since before the taxonomic split between the plant and animal kingdoms. The discovery of the mammalian Toll-like receptors was heralded as confirmation of a predicted biological system explicitly designed to detect exogenous molecules from micro-organisms. However, there is accumulating evidence that Toll-like receptors also detect endogenous agonists, such as the degradation products of macromolecules, products of proteolytic cascades, intracellular components of ruptured cells, and products of genes that are activated by inflammation. Here we review endogenous models of Toll-like receptor activation, a subject of extensive debate. Endogenous activation of mammalian Toll-like receptors may provide key insights for the treatment of multiple conditions, from atherosclerosis to transplant rejection.