[PDF][PDF] Invasive bacterial pathogens exploit TLR-mediated downregulation of tight junction components to facilitate translocation across the epithelium

TB Clarke, N Francella, A Huegel, JN Weiser - Cell host & microbe, 2011 - cell.com
TB Clarke, N Francella, A Huegel, JN Weiser
Cell host & microbe, 2011cell.com
Streptococcus pneumoniae and Haemophilus influenzae are members of the normal human
nasal microbiota with the ability to cause invasive infections. Bacterial invasion requires
translocation across the epithelium; however, mechanistic understanding of this process is
limited. Examining the epithelial response to murine colonization by S. pneumoniae and H.
influenzae, we observed the TLR-dependent downregulation of claudins 7 and 10, tight
junction components key to the maintenance of epithelial barrier integrity. When modeled in …
Summary
Streptococcus pneumoniae and Haemophilus influenzae are members of the normal human nasal microbiota with the ability to cause invasive infections. Bacterial invasion requires translocation across the epithelium; however, mechanistic understanding of this process is limited. Examining the epithelial response to murine colonization by S. pneumoniae and H. influenzae, we observed the TLR-dependent downregulation of claudins 7 and 10, tight junction components key to the maintenance of epithelial barrier integrity. When modeled in vitro, claudin downregulation was preceded by upregulation of SNAIL1, a transcriptional repressor of tight junction components, and these phenomena required p38 MAPK and TGF-β signaling. Consequently, downregulation of SNAIL1 expression inhibited bacterial translocation across the epithelium. Furthermore, disruption of epithelial barrier integrity by claudin 7 inhibition in vitro or TLR stimulation in vivo promoted bacterial translocation. These data support a general mechanism for epithelial opening exploited by invasive pathogens to facilitate movement across the epithelium to initiate disease.
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