The long term goal of this proposal is to understand the pathogenesis of surgical necrotizing enterocolitis (NEC), the most frequent and lethal gastrointestinal disorder affecting the stressed, preterm infant. Although initially affecting the intestine, patients with NEC may rapidly develop systemic sepsis and multi-system organ failure and death from overwhelming septic shock. Current thinking indicates that the development of NEC reflects the effects of systemic stress causing a breakdown of the intestinal barrier. This leads to the translocation of bacteria and lipopolysaccharide (LPS), which is recognized on immune cells and enterocytes by Toll Like Receptor 4 (TLR4). We now propose that activation of TLR4 by LPS leads to sepsis and further intestinal injury, characteristic of NEC. Healing of the injured intestinal mucosa typically occurs through epithelial restitution, in which healthy enterocytes migrate towards the denuded mucosa. We have developed a rodent model that mimics human NEC, and have shown that intestinal restitution is significantly impaired in animals with NEC compared with controls. Strikingly, mice with mutations in TLR4 have significantly reduced severity of NEC as compared to wild-type littermates. In vitro, enterocyte migration is regulated by RhoA and integrins, and treatment of enterocytes with LPS leads to a significant inhibition in enterocyte migration through the activation of RhoA and increased cell-matrix adhesion. We now hypothesize that TLR4 plays a critical role in the pathogenesis of NEC through the activation of RhoA and integrins and impaired intestinal restitution. To test this hypothesis, we propose:
Aim 1 To assess the effects of LPS on the expression and activity of TLR4 in enterocytes in vitro and in vivo.
Aim 2. To determine whether TLR4 signaling is necessary for the effects of LPS on RhoA activation and enterocyte migration and to determine the signaling pathways involved.
Aim 3. To determine whether TLR4 is required for the induction of necrotizing enterocolitis in vivo through effects on RhoA activity and enterocyte migration. By testing the hypothesis that TLR4 signaling plays a critical role in the pathogenesis of NEC, we propose to understand the principal steps that lead to the development of this devastating illness, and to identify novel treatment strategies for these fragile patients. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM078238-02
Application #
7281722
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Somers, Scott D
Project Start
2006-09-01
Project End
2011-08-31
Budget Start
2007-09-01
Budget End
2008-08-31
Support Year
2
Fiscal Year
2007
Total Cost
$269,674
Indirect Cost
Name
Children's Hosp Pittsburgh/Upmc Health Sys
Department
Type
DUNS #
044304145
City
Pittsburgh
State
PA
Country
United States
Zip Code
15224
Hackam, David J; Sodhi, Chhinder P (2018) Toll-Like Receptor-Mediated Intestinal Inflammatory Imbalance in the Pathogenesis of Necrotizing Enterocolitis. Cell Mol Gastroenterol Hepatol 6:229-238.e1
Renz, Harald; Adkins, Becky D; Bartfeld, Sina et al. (2018) The neonatal window of opportunity-early priming for life. J Allergy Clin Immunol 141:1212-1214
Goldstein, Seth D; Beaulieu, Robert J; NiƱo, Diego F et al. (2018) Early detection of necrotizing enterocolitis using broadband optical spectroscopy. J Pediatr Surg 53:1192-1196
Sodhi, Chhinder P; Fulton, William B; Good, Misty et al. (2018) Fat composition in infant formula contributes to the severity of necrotising enterocolitis. Br J Nutr 120:665-680
Lu, P; Sodhi, C P; Yamaguchi, Y et al. (2018) Intestinal epithelial Toll-like receptor 4 prevents metabolic syndrome by regulating interactions between microbes and intestinal epithelial cells in mice. Mucosal Immunol 11:727-740
Chen, May W; Reyes, Michael; Kulikowicz, Ewa et al. (2018) Abdominal near-infrared spectroscopy in a piglet model of gastrointestinal hypoxia produced by graded hypoxia or superior mesenteric artery ligation. Pediatr Res 83:1172-1181
Sodhi, Chhinder P; Wohlford-Lenane, Christine; Yamaguchi, Yukihiro et al. (2018) Attenuation of pulmonary ACE2 activity impairs inactivation of des-Arg9 bradykinin/BKB1R axis and facilitates LPS-induced neutrophil infiltration. Am J Physiol Lung Cell Mol Physiol 314:L17-L31
Martin, Laura Y; Ladd, Mitchell R; Werts, Adam et al. (2018) Tissue engineering for the treatment of short bowel syndrome in children. Pediatr Res 83:249-257
Hackam, David J; Sodhi, Chhinder P; Good, Misty (2018) New insights into necrotizing enterocolitis: From laboratory observation to personalized prevention and treatment. J Pediatr Surg :
Jia, Hongpeng; Sodhi, Chhinder P; Yamaguchi, Yukihiro et al. (2018) Toll Like Receptor 4 Mediated Lymphocyte Imbalance Induces Nec-Induced Lung Injury. Shock :

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