title: DNA attenuates enterocyte Toll-like receptor 4-mediated intestinal mucosal injury after remote trauma.
abstract: Intestinal mucosal injury occurs after remote trauma although the mechanisms that sense remote injury and lead to intestinal epithelial disruption remain incompletely understood. We now hypothesize that Toll-like receptor 4 (TLR4) signaling on enterocytes after remote injury, potentially through the endogenous TLR4 ligand high-mobility group box-1 (HMGB1), could lead to intestinal dysfunction and bacterial translocation and that activation of TLR9 with DNA could reverse these effects. In support of this hypothesis, exposure of TLR4-expressing mice to bilateral femur fracture and systemic hypotension resulted in increased TLR4 expression and signaling and disruption of the ileal mucosa, leading to bacterial translocation, which was not observed in TLR4-mutant mice. TLR4 signaling in enterocytes, not immune cells, was required for this effect, as adenoviral-mediated inhibition of TLR4 in enterocytes prevented these findings. In seeking to identify the endogenous TLR4 ligands involved, the expression of HMGB1 was increased in the intestinal mucosa after injury in wild-type, but not TLR4-mutant, mice, and administration of anti-HMGB1 antibodies reduced both intestinal mucosal TLR4 signaling and bacterial translocation after remote trauma. Strikingly, mucosal injury was significantly increased in TLR9-mutant mice, whereas administration of exogenous DNA reduced the extent of TLR4-mediated enterocyte apoptosis, restored mucosal healing, and maintained the histological integrity of the intestinal barrier after remote injury. Taken together, these findings identify a novel link between remote injury and enterocyte TLR4 signaling leading to barrier injury, potentially through HMGB1 as a ligand, and demonstrate the reversal of these adverse effects through activation of TLR9.
authors.affiliation: Div. of Pediatric Surgery, Department of Surgery, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, PA 15224, USA.
authors.forename: Chhinder
authors.initials: C
authors.lastname: Sodhi
authors.forename: Ryan
authors.initials: R
authors.lastname: Levy
authors.forename: Roop
authors.initials: R
authors.lastname: Gill
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Neal
authors.forename: Ward
authors.initials: W
authors.lastname: Richardson
authors.forename: Maria
authors.initials: M
authors.lastname: Branca
authors.forename: Anthony
authors.initials: A
authors.lastname: Russo
authors.forename: Thomas
authors.initials: T
authors.lastname: Prindle
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Billiar
authors.forename: David J
authors.initials: DJ
authors.lastname: Hackam
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D018988:Bacterial Translocation; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay; D020895:Enterocytes / Q000187:drug effects / Q000473:pathology*; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D024243:HMGB1 Protein / Q000378:metabolism; D007113:Immunity, Innate / Q000502:physiology; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000187:drug effects / Q000293:injuries* / Q000473:pathology*; D051379:Mice; D008809:Mice, Inbred C3H; D009154:Mutation / Q000502:physiology; D016328:NF-kappa B / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051197:Toll-Like Receptor 4 / Q000187:drug effects* / Q000502:physiology*; D051217:Toll-Like Receptor 9 / Q000187:drug effects / Q000235:genetics
chemical_list: D024243:HMGB1 Protein; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D049452:Green Fluorescent Proteins; D004247:DNA