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2007 Program and Abstracts | 2007 Posters
Effects of Inflammatory Cytokines and Hypoxia On Intestinal Wound Healing and Matrix Metalloproteinase Expression
Dana M. Hayden*1, Christopher Forsyth2, Ali Keshavarzian2, Richard a. Prinz1
1Department of General Surgery, Rush University Medical Center, Chicago, IL; 2Department of Gastroenterology, Rush University Medical Center, Chicago, IL

Wound healing is a key consideration in gastrointestinal surgery and poor anastomotic healing is a major source of postoperative morbidity and mortality. Multiple factors propagate poor healing, including inflammation, and studies have shown inflammatory cytokines to have deleterious effects. Mechanistic studies have linked cytokines to matrix metalloproteinases (MMPs) which appear to play a crucial role in both normal and abnormal wound healing. This study examines the relationship between expression of MMPs and the effects of cytokines on intestinal cell wound healing. Rat intestinal epithelial cells were wounded with 30ul pipette tips and wounds were measured at time points 0, 8 and 24 hours. The supernatants were collected for wounded and unwounded cells and Western blots were performed. Abnormal conditions were created by exposing cells to tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ) and interleukin-1 beta (IL-1β) as well as hypoxia. The mean percent healing for wounded cells under normal conditions was 50% at 8 hours and 99% at 24 hours. MMP-7 was not present immediately but increased 2-3 fold over unwounded cells at both 8 and 24 hours (p=0.001). In contrast to MMP-7, both MMP-3 and -9 increased immediately following wounding by 5-15 fold when compared to unwounded cells at time 0 (p=0.001). This trend continued at 8 hours; however the difference disappeared at 24 hours. When compared to normal conditions, statistically significant delays in wound closure at 8 hours were evident in cells stimulated by IL-1β and IFN-γ (13% and 29% vs. 45%, p=0.001 and p=0.018, respectively). These differences remained significant at 24 hours. Although hypoxia delayed healing, the difference did not reach statistical significance. TNF-α did not appear to affect the rate of wound healing. When examining MMP-7 expression under abnormal conditions, IL1-β stimulated a 130% and 56% increase when compared to normal wounded cells at 8 and 24 hours, respectively. TNF-α appeared to increase the amount of MMP-7 released by both wounded and unwounded cells; thus the overall difference was not significant. Hypoxia and IFN-γ did not appear to affect levels of MMP-7 in wounded or unwounded cells. This study suggests that several MMPs are increased and in a specific sequence during normal intestinal wound healing. However, it appears that certain inflammatory conditions stimulate higher levels of MMP-7 than are released during normal wound repair while simultaneously delaying the healing of intestinal epithelial cells. Ongoing gene-specific inhibition studies will further elucidate this relationship.

2007 Program and Abstracts | 2007 Posters
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