The overall hypothesis of this proposal is that necrotizing enterocolitis (NEC) is a disease of immature intestinal host defenses triggered by the introduction of artificial feedings and propagated by inappropriate microbial colonization. To test this hypothesis we will use newly established in vitro models for study of human intestinal host defense including a recently established human fetal small intestinal cell line, organ cultures of small intestine from NEC patients and age matched controls, Ussing chamber techniques to quantitate antigen uptake and bacterial translocation, and a transplanted fetal human intestinal loop model for simulated intraluminal conditions in the immature intestine. Using these methods, we will study aspects of developmental regulation of bacterial colonization, antibacterial properties of developing Paneth cells, the functional significance of a newly discovered intestinal Fc receptor for human IgG and selective aspects of intestinal inflammatory responses and immune function. If, as expected, we note developmental differences in these studies, we plan to assess developmental regulation of these host defenses by growth factors (IGF-l, EGF, TGF-alpha and beta, cortisone) and cytokines (INF-gamma, TNF-alpha, PAF, etc). To study bacterial colonization and toxin interactions, we will extend previous animal studies to examine glycosyltransferases and microvillus membrane glycoconjugates (the putative bacterial gut receptor) developmentally and fimbrial adhesion molecules from two strains of enterotoxigenic E.Coli in intestine from NEC patients and at various ages (fetal-childhood). Because Paneth cells have been shown to produce and secrete antibacterial substances including TNF-alpha, lysozyme, alpha-l-antitrypsin and cryptdins, an intestinal form of defensin, we will study the ontogeny of Paneth cell protective function and specifically its anti bacterial properties in NEC intestine. We will define the significance of the newly described Fc receptor by first quantitating IgG and their subclass levels in amniotic fluids and preterm colostrum. We will then use the same concentrations of IgG to test for preferential binding to the fetal enterocyte and transport across the epithelium into the circulation. We will also test IgG-IgA at concentrations reported to protect premature infants against necrotizing enterocolitis to see if these concentrations actually bind to this receptor. Finally, we will measure the response to stimulus of inflammatory cytokines (IL-1, IL-6, IL-8, PAF) and class II antigen expression in various ages of intestinal enterocytes and intestine from NEC patients for developmental differences and determine if growth factors affect their expression at the mRNA and post transcriptional levels. These studies in human immature small intestine should help our understanding of the pathogenesis of NEC and may lead to new strategies for prevention and treatment.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD031852-05
Application #
2673761
Study Section
Special Emphasis Panel (SRC (05))
Project Start
1994-05-01
Project End
1999-04-30
Budget Start
1998-05-01
Budget End
1999-04-30
Support Year
5
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Lu, Lei; Bao, Yuanwu; Khan, Abdullah et al. (2008) Hydrocortisone modulates cholera toxin endocytosis by regulating immature enterocyte plasma membrane phospholipids. Gastroenterology 135:185-193.e1
Savidge, Tor C; Newman, Paul; Pothoulakis, Charalabos et al. (2007) Enteric glia regulate intestinal barrier function and inflammation via release of S-nitrosoglutathione. Gastroenterology 132:1344-58
Meng, Di; Newburg, David S; Young, Cheryl et al. (2007) Bacterial symbionts induce a FUT2-dependent fucosylated niche on colonic epithelium via ERK and JNK signaling. Am J Physiol Gastrointest Liver Physiol 293:G780-7
Chen, Chien-Chang; Louie, Steve; McCormick, Beth A et al. (2006) Helminth-primed dendritic cells alter the host response to enteric bacterial infection. J Immunol 176:472-83
Nanthakumar, N Nanda; Dai, Dingwei; Meng, Di et al. (2005) Regulation of intestinal ontogeny: effect of glucocorticoids and luminal microbes on galactosyltransferase and trehalase induction in mice. Glycobiology 15:221-32
Nanthakumar, N Nanda; Young, Cheryl; Ko, Jae Sung et al. (2005) Glucocorticoid responsiveness in developing human intestine: possible role in prevention of necrotizing enterocolitis. Am J Physiol Gastrointest Liver Physiol 288:G85-92
Claud, Erika C; Lu, Lei; Anton, Pauline M et al. (2004) Developmentally regulated IkappaB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation. Proc Natl Acad Sci U S A 101:7404-8
Yuan, Qian; Walker, W Allan (2004) Innate immunity of the gut: mucosal defense in health and disease. J Pediatr Gastroenterol Nutr 38:463-73
Shi, Hai Ning; Walker, Allan (2004) Bacterial colonization and the development of intestinal defences. Can J Gastroenterol 18:493-500
Huang, Fu-Chen; Werne, Adam; Li, Qian et al. (2004) Cooperative interactions between flagellin and SopE2 in the epithelial interleukin-8 response to Salmonella enterica serovar typhimurium infection. Infect Immun 72:5052-62

Showing the most recent 10 out of 39 publications