Non-healing is associated with persistent stimulation of the innate immune response in chronic venous leg ulcers.
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.
Pukstad
Brita S
BS
Institute of Cancer Research and Molecular Medicine, Norwegian University of Technology and Science, 7089 Trondheim, Norway. brita.pukstad@ntnu.no
Ryan
Liv
L
Flo
Trude H
TH
Stenvik
Jørgen
J
Moseley
Ryan
R
Harding
Keith
K
Thomas
David W
DW
Espevik
Terje
T
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*
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