MAPPING THE INFLAMMATORY MICROENVIRONMENT OF MUSCLE TISSUE AND ITS RELATIONSHIP TO INCISIONAL HERNIA DEVELOPMENT
Alexander F. Siegel*, Kalley Johnson, Emily Krier, Swati Agrawal, Robert J. Fitzgibbons
Creighton University School of Medicine, Omaha, NE
Background
An incisional hernia (IH) is one of the most frequent complications after a laparotomy, affecting between 10 -20% of patients. This incidence increases substantially in patients with comorbidities such as obesity, smoking, diabetes, immunosuppression and certain conditions such as diverticulitis or abdominal aortic aneurysm. The molecular basis for this variability is poorly understood but is now being addressed by many investigators. In this study, we looked at the role of molecular proteins called cytokines in the improper wound healing that leads to IH. We examined the cytokines present within muscle tissues of IH. We hypothesize that increased proinflammatory cytokines and decreased anti-inflammatory cytokines lead to impaired wound healing and the development of IH. Understanding the molecular microenvironment of muscle tissue in IH is important because these cytokines serve as potential therapeutic targets for improving the body's repair response to ultimately decrease susceptibility to IH.
Experimental Design
Samples of muscle, adipose, and fascia were collected during IH repair. Muscle tissue was separated, processed, transversely sectioned onto glass slides, and stained using immunofluorescent tagged antibodies that bind leptin, adiponectin, TNF-α, and IL-6. The immunofluorescent findings were compared with the results of RTPCR quantification of the specific genes studied within the same tissues. The stained sections were scanned and analyzed using ImageJ software to quantify the expression of each cytokine in the samples compared to controls. Control muscle tissue was obtained from brain dead organ donors without prior abdominal surgery.
Results
Results of our immunofluorescence analysis demonstrate that proinflammatory cytokines leptin, TNF-α, and IL-6 were expressed in higher quantities while anti-inflammatory cytokine adiponectin was expressed in lower quantity in IH tissue compared to control tissue. The results of RTPCR analysis also showed significantly increased gene expression of leptin, TNF-α, and IL-6. However, adiponectin was significantly increased in patients compared to controls which was not consistent with our immunofluorescence analysis. This discrepancy may be due to a regulatory mechanism that affects the translation of mRNA (RTPCR) to protein (immunofluorescence) in a predominantly proinflammatory environment.
Conclusion
We found a significantly increased expression of proinflammatory cytokines leptin, TNF-α, and IL-6 in muscles tissue and decreased expression of anti-inflammatory cytokine adiponectin from IH patients when compared to controls. This supports the notion that an imbalance of cytokines with a predominance of proinflammatory cytokines impairs the wound healing process and may be a treatable target to prevent postoperative IH.
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