Clark JA, Gan H, Samocha AJ, Fox AC, Buchman TG, Coopersmith CM. Enterocyte-specific epidermal growth factor prevents barrier dysfunction and improves mortality in murine peritonitis. Am J Physiol Gastrointest Liver Physiol 297: G471-G479, 2009. First published July 1, 2009 doi:10.1152/ajpgi.00012.2009.-Systemic administration of epidermal growth factor (EGF) decreases mortality in a murine model of septic peritonitis. Although EGF can have direct healing effects on the intestinal mucosa, it is unknown whether the benefits of systemic EGF in peritonitis are mediated through the intestine. Here, we demonstrate that enterocyte-specific overexpression of EGF is sufficient to prevent intestinal barrier dysfunction and improve survival in peritonitis. Transgenic FVB/N mice that overexpress EGF exclusively in enterocytes (IFABP-EGF) and wild-type (WT) mice were subjected to either sham laparotomy or cecal ligation and puncture (CLP). Intestinal permeability, expression of the tight junction proteins claudins-1, -2, -3, -4, -5, -7, and -8, occludin, and zonula occludens-1; villus length; intestinal epithelial proliferation; and epithelial apoptosis were evaluated. A separate cohort of mice was followed for survival. Peritonitis induced a threefold increase in intestinal permeability in WT mice. This was associated with increased claudin-2 expression and a change in subcellular localization. Permeability decreased to basal levels in IFABP-EGF septic mice, and claudin-2 expression and localization were similar to those of sham animals. Claudin-4 expression was decreased following CLP but was not different between WT septic mice and IFABP-EGF septic mice. Peritonitis-induced decreases in villus length and proliferation and increases in apoptosis seen in WT septic mice did not occur in IFABP-EGF septic mice. IFABP-EGF mice had improved 7-day mortality compared with WT septic mice (6% vs. 64%). Since enterocyte-specific overexpression of EGF is sufficient to prevent peritonitis-induced intestinal barrier dysfunction and confers a survival advantage, the protective effects of systemic EGF in septic peritonitis appear to be mediated in an intestine-specific fashion.
Objective-While most septic patients have an underlying comorbidity, most animal models of sepsis use mice that were healthy prior to the onset of infection. Malignancy is the most common comorbidity associated with sepsis. The purpose of this study was to determine whether mice with cancer have a different response to sepsis than healthy animals.Design-Prospective, randomized controlled study.Setting-Animal laboratory in a university medical center.Subjects-C57Bl/6 mice.Interventions-Animals received a subcutaneous injection of either 250,000 cells of the transplantable pancreatic adenocarcinoma cell line Pan02 (cancer) or phosphate-buffered saline (healthy). Three weeks later, mice given Pan02 cells developed reproducible, non-metastatic tumors. Both groups of mice then underwent intratracheal injection of either Pseudomonas aeruginosa (septic) or 0.9% NaCl (sham). Animals were sacrificed 24 hours post-operatively or followed seven days for survival.Measurements and Main Results-Cancer and healthy mice appeared similar when subjected to sham operation, although cancer animals had lower levels of T and B lymphocyte apoptosis. Cancer septic mice had increased mortality compared to previously healthy septic mice subjected to the identical injury (52% vs. 28%, p=0.04). This was associated with increased bacteremia but no difference in local pulmonary infection. Cancer septic mice also had increased intestinal epithelial apoptosis. Although sepsis induced an increase in T and B lymphocyte apoptosis in all animals, cancer septic mice had decreased T and B lymphocyte apoptosis compared to previously healthy septic mice. Serum and pulmonary cytokines, lung histology, complete blood counts and intestinal proliferation were similar between cancer septic and previously healthy septic mice. Conclusions-When subjected to the same septic insult, mice with cancer have increased mortality compared to previously healthy animals. Decreased systemic bacterial clearance and alterations in both intestinal epithelial and lymphocyte apoptosis may help explain this differential response.
Although BRAF mutation was found to be an independent predictor of central LNM in the overall cohort of patients with PTC, this relationship lost significance when only classical variant PTC was included in the analysis. The usefulness of BRAF in predicting the presence of LNM remains questionable. Prospective studies are needed before BRAF mutation can be considered a reliable factor to guide the treatment of patients with PTC, specifically whether to perform prophylactic CLND.
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