Cytokine stability in chronic wound fluid and its association to fibroblast proliferation.

Cytokines are commonly deregulated in venous leg ulcers. We have investigated cytokine stability by incubating sterile-filtered wound fluids from chronic venous leg ulcers in vitro. Incubation of wound fluids for 24 h at 37°C decreased IL-1β levels by 88% and TNF-α levels by 64%. IL-1β was degraded by serine proteinases and metalloproteinases while the mechanism for reduced TNF-α remains elusive. The levels of the other peptides did not change significantly (p > 0.05). Normal human dermal fibroblasts exposed to five of the six wound fluids showed increased proliferation with the length of prior incubation using an assay optimised for evaluation of wound fluid bioactivity. Exogenous IL-1β and TNF-α unexpectedly increased (p < 0.001) cell proliferation at concentrations that were measured in the wound fluids. In conclusion, the stability of the eight investigated cytokines in wound fluids differed and presumably the loss of detrimental factors, unlikely IL-1β or TNF-α, resulted in increased fibroblast proliferation.