B. W. Padon1, 2, T. J. Prajapati1, 2, F. M. Faruk1, 2, W. D. Short1, 2, O. Olutoye1, 2, H. Li1, 2, M. Rae1, T. Lu1, S. G. Keswani1, 2, S. Balaji1, 2 1Baylor College of Medicine, Pediatric General Surgery, Houston, TX, USA 2Texas Children’s Hospital, Pediatric General Surgery, Houston, TX, USA
Introduction:
Our lab has shown a significant role for IL-10 overexpression in regulating inflammation and extracellular matrix (ECM) production, thereby attenuating fibrosis in skin wounds. However, the role of IL-10 in wound closure is unclear, as previous studies in murine wounds, not controlled for contraction and moist wound environment, have shown increased rates of wound closure in IL-10-/- mice. The objective of this study is to determine the role of endogenous IL-10 on wound closure when controlling for contraction and a moist wound environment.
Methods:
Full thickness 6mm wounds were made in C57B6/J WT and IL-10-/- mice and controlled for contraction using a silicone stent. A moist wound environment was provided by Tegaderm dressing. Wounds were serially photographed at 3, 5 and 7d, harvested at 7d and 30d post wounding, then examined for epithelial gap, granulation tissue, scar area(H&E), myofibroblasts(aSMA), and leukocyte(CD45) and macrophage content(F4/80). Data is mean+-SD, n=8-10 wounds/group/time; p-value by ANOVA.
Results:
In contrast to prior reports, unstented IL-10-/- wounds maintained in a moist wound environment showed no significant difference in epithelial gap at d7, but had an increase in granulation tissue (IL-10-/- 1.4+-0.6 vs WT 0.8+-0.4 mm2, p<0.01) compared to WT. Unstented IL-10-/- wounds exhibited a heightened inflammatory response, with an elevated % of CD45+ (IL-10-/- 28.9%+-14.1 vs WT 6.0+-2.7, p<.01) and F4/80+ (IL-10-/- 53.7%+-1.2 vs WT 28.3+-0.5, p<.01) cells/high power field(HPF). Upon stenting the wounds, no difference in epithelial gap and granulation tissue was seen. The increase in % of F4/80+ cells/HPF (IL-10-/- 21.3%+-3.6 vs WT 22.4+-5.4, p<.05) persisted in stented wounds. There was a marked increase in the % of CD45+ cells/HPF (IL-10-/-22.4%+-1.5 vs WT 13.6%+-1.7, p=ns) as well. aSMA showed abundant expression at the wound margins in all wounds, but stented wounds had more aSMA present in the granulation tissue compared to unstented wounds. IL-10-/- wounds had more aSMA staining in the wound bed than WT. However, analysis of the % of aSMA + cells/HPF showed no significant difference in the stented and unstented wounds. At d30, wounds in IL-10-/- mice had significantly larger scar area as compared WT in stented (IL-10-/- 0.24+-0.02 vs WT 0.17+-0.06 mm2, p<.05) and unstented (IL-10-/- 0.18+-0.01 vs WT 0.13+-0.03 mm2, p<.05) groups.
Conclusion:
Our data showed endogenous IL-10 does not delay normal healing of skin wounds when controlled for contraction and moist environment. However, the loss of IL-10 leads to increased inflammation and fibrosis. This data signifies a previously unrecognized role for endogenously expressed IL-10 contributing to the tissue repair response.
