Postischemic vascular permeability requires both TLR-2 and TLR-4, but only TLR-2 mediates the transendothelial migration of leukocytes.
Ischemia-reperfusion (I/R) activates innate immunity involving Toll-like receptor (TLR) 2 and TLR-4 signaling. Leukocyte migration and vascular permeability contribute to postischemic tissue damage. We hypothesized that TLR-2 and TLR-4 directly mediate leukocyte migration and vascular permeability during I/R. We used in vivo microscopy on postischemic murine cremaster muscle to quantify leukocyte adhesion as well as transendothelial and interstitial migration in sham-operated wild-type mice and in wild-type, TLR-2(-/-), and TLR-4-mutant mice 30 and 120 min after I/R. Alterations in fluorescein isothiocyanate-dextran leakage across cremasteric venules were determined as a measure of endothelial permeability. I/R-induced leukocyte adhesion in TLR-2(-/-) and TLR-4-mutant mice was comparable to that in wild-type mice. The number of transmigrated leukocytes was increased upon I/R in wild-type mice as compared with the sham-operated group. In contrast, leukocyte transmigration was significantly attenuated in TLR-2(-/-) but not in TLR-4-mutant mice. Motility and polarization of interstitially migrating leukocytes did not significantly differ in TLR-2(-/-) and TLR-4-mutant mice from wild-type mice. Postischemic vascular leakage was significantly lower in both TLR-2(-/-) and TLR-4-mutant than in wild-type mice. We conclude that both TLR-2 signaling and TLR-4 signaling enhance postischemic vascular permeability and that TLR-2 has additional effects on the transendothelial migration of leukocytes at the postischemic vascular wall.
Khandoga
Alexander Georg
AG
Walter Brendel Centre of Experimental Medicine, Ludwig-Maximilians-Universität München, Munich, Germany. alexander.khandoga@med.uni-muenchen.de
Khandoga
Andrej
A
Anders
Hans-Joachim
HJ
Krombach
Fritz
F
D000818:Animals; D002199:Capillary Permeability / Q000235:genetics / Q000502:physiology*; D002448:Cell Adhesion / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D007958:Leukocyte Count; D007962:Leukocytes / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008856:Microscopy, Fluorescence; D015427:Reperfusion Injury / Q000503:physiopathology*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000502:physiology*
D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4