Inducible activation of TLR4 confers resistance to hyperoxia-induced pulmonary apoptosis.

Journal Article (Journal Article)

TLRs are essential mediators of host defense against infection via recognition of unique microbial structures. Recent observations indicate that TLR4, the principal receptor for bacterial LPS, may also be activated by noninfectious stimuli including host-derived molecules and environmental oxidant stress. In mice, susceptibility to ozone-induced lung permeability has been linked to the wild-type allele of TLR4, whereas deficiency of TLR4 predisposes to lethal lung injury in hyperoxia. To precisely characterize the role of lung epithelial TLR4 expression in the host response to oxidant stress, we have created an inducible transgenic mouse model that targets the human TLR4 signaling domain to the airways. Exposure of induced transgenic mice to hyperoxia revealed a significant reduction in pulmonary apoptosis compared with controls. This phenotype was associated with sustained up-regulation of antiapoptotic molecules such as heme oxygenase-1 and Bcl-2, yet only transient activation of the transcription factor NF-kappaB. Specific in vivo knockdown of pulmonary heme oxygenase-1 or Bcl-2 expression by intranasal administration of short interfering RNA blocked the effect of TLR4 signaling on hyperoxia-induced lung apoptosis. These results define a novel role for lung epithelial TLR4 as a modulator of cellular apoptosis in response to oxidant stress.

Full Text

Duke Authors

Cited Authors

  • Qureshi, ST; Zhang, X; Aberg, E; Bousette, N; Giaid, A; Shan, P; Medzhitov, RM; Lee, PJ

Published Date

  • April 15, 2006

Published In

Volume / Issue

  • 176 / 8

Start / End Page

  • 4950 - 4958

PubMed ID

  • 16585591

International Standard Serial Number (ISSN)

  • 0022-1767

Digital Object Identifier (DOI)

  • 10.4049/jimmunol.176.8.4950

Language

  • eng

Conference Location

  • United States