title: Non-healing is associated with persistent stimulation of the innate immune response in chronic venous leg ulcers.
abstract: BACKGROUND
  The molecular pathogenesis of chronic skin wounds is complex and not fully understood. Although these wounds are often characterized as being in a state of persistent inflammation, the impact and participation of the innate immune responses in sustaining this inflammation needs further investigation.
  
  
  OBJECTIVE
  We investigated the cytokine profiles, Toll-like receptor (TLR)-stimulating activities and the levels of the antibacterial peptide Lipocalin-2 (Lcn-2) in a series of healing and non-healing chronic venous leg ulcers (CVLUs) through a study time of 8 weeks.
  
  
  METHODS
  Wound fluids from healing and non-healing CVLUs were run on a Human Cytokine Antibody Array, and Lcn-2 levels measured with ELISA. HEK 293 cells transfected with TLR2 or TLR4 and their respective co-receptors, and human peripheral blood monocytes were then stimulated with the wound fluids from healing and non-healing venous leg ulcers.
  
  
  RESULTS
  Healing wounds were associated with decreasing levels of IL-1alpha, IL-1beta and MIP-1delta, whereas in non-healing wounds decreasing levels of IL-8 and MIP-1alpha were found. Accordingly, wound fluid from non-healing CVLUs contained persistent Lcn-2 levels and TLR2- and TLR4-stimulating activities, while, in healing wounds, the TLR-stimulating activities decreased over time with significantly diminished levels of Lcn-2 (p<0.005).
  
  
  CONCLUSIONS
  Innate immune responses contribute to the chronic inflammation in non-healing CVLUs through participation of Toll-like receptors. The levels of the antimicrobial peptide Lcn-2 in wound fluids from these ulcers are elevated as a reflection of this contribution.
authors.affiliation: Institute of Cancer Research and Molecular Medicine, Norwegian University of Technology and Science, 7089 Trondheim, Norway. brita.pukstad@ntnu.no
authors.forename: Brita S
authors.initials: BS
authors.lastname: Pukstad
authors.forename: Liv
authors.initials: L
authors.lastname: Ryan
authors.forename: Trude H
authors.initials: TH
authors.lastname: Flo
authors.forename: Jørgen
authors.initials: J
authors.lastname: Stenvik
authors.forename: Ryan
authors.initials: R
authors.lastname: Moseley
authors.forename: Keith
authors.initials: K
authors.lastname: Harding
authors.forename: David W
authors.initials: DW
authors.lastname: Thomas
authors.forename: Terje
authors.initials: T
authors.lastname: Espevik
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism; D002478:Cells, Cultured; D054405:Chemokine CCL3 / Q000378:metabolism; D002908:Chronic Disease; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D016209:Interleukin-8 / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism; D000071068:Lipocalin-2; D054834:Lipocalins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D014647:Varicose Ulcer / Q000503:physiopathology*; D014945:Wound Healing / Q000502:physiology*
chemical_list: D000209:Acute-Phase Proteins; D054405:Chemokine CCL3; D016209:Interleukin-8; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4