Premium
Involvement of TLR4 in burn‐induced microvascular endothelial hyperpermeability.
Author(s) -
Breslin Jerome W,
Wu Mack H,
Guo Mingzhang,
Reynoso Rashell,
Yuan Sarah Y
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a490-d
Subject(s) - tlr4 , in vivo , inflammation , medicine , evans blue , receptor , trif , burn injury , vascular permeability , pharmacology , immunology , chemistry , toll like receptor , biology , innate immune system , surgery , microbiology and biotechnology
Systemic inflammation and microvascular leakage play a key role in the development of multiple organ failure following severe burn injury. Toll‐like receptors are known to regulate host responses to pathogens as well as injury‐associated inflammatory responses. We investigated whether the toll‐like receptor 4 (TLR4) contributes to microvascular leakage during thermal injury, using both cell culture and in vivo models. The transendoethelial electrical resistance (TER) of rat lung microvascular endothelial cell (RLMEC) monolayers served as an index of endothelial barrier function. RLMEC were treated with plasma from rats that received either a 20% total body surface area scalding burn or sham burn. To investigate the role of TLR4 in RLMEC barrier function, we treated cells with siRNA to decrease TLR4 expression. Phosphorylation of IRAK‐1, a downstream effector in the TLR4 signaling pathway, was evaluated by immunoblotting. In addition, we assessed burn‐induced hyperpermeability in vivo by measuring transvascular flux of FITC‐albumin in a TLR4 knockout mouse mesentery model. The results show that burn plasma caused a significant drop in RLMEC TER, compared to sham plasma, which was associated with elevated phosphorylation of IRAK‐1. Knockdown of TLR4 expression by siRNA attenuated the response. Moreover, TLR4 KO mice displayed an attenuated increase in microvascular leakage following burn injury, compared to wild‐type mice. The data indicate that TLR4 plays an important role in thermal injury‐induced microvascular leakage. Supported by NIH R01 HL‐70752, HL‐61507, HL‐084542, HL‐73324, and F32 HL‐76079.