Neonatal necrotizing enterocolitis (NEC) is the single most devastating gastrointestinal cause of mortality and morbidity in premature infants. Although the pathophysiology of NEC is uncertain, the leading hypothesis is that intestinal bacteria penetrate the immature intestinal epithelial barrier defenses, leading to tissue invasion and subsequent necrosis. A key gastrointestinal cell of the innate immune system is the Paneth cell, which is located in the base of the intestinal crypts. Paneth cells protect the intestine through secretion of pro-inflammatory mediators and antimicrobial substances. Compared to age-matched controls, infants with NEC have significantly decreased numbers of Paneth cells. Despite the key role Paneth cells play in immune function, it is unclear what role these cells play in the pathogenesis of NEC. Traditional animal models have not yet developed Paneth cells, and are thus unable to address this gap in knowledge. The overall objective of this pre-clinical application is to determine the role of Paneth cells in the development of tissue injury in the immature intestine. To achieve this objective, we will utilize our newly described mouse model of NEC that uses Paneth cell necrosis to induce NEC-like injury. Our hypothesis is that Paneth cell loss renders the immature small intestine susceptible to development of NEC. In this application, we propose to test this hypothesis in the following two Aims: 1: Establish the mechanism of Paneth cell involvement in the pathogenesis of NEC. Infants with NEC lack Paneth cells, and Paneth cell ablation in the presence of Klebsiella produces NEC- like pathology in mice. However, the role of Paneth cells in intestinal injury remains unclear. In this Aim we will examine methods of Paneth cell loss, and the role of Paneth cell secretions to establish how Paneth cell disruption renders the immature ileum susceptible to injury. 2: Establish the role of TLR4 signaling in Paneth cell ablation-induced NEC. Bacteria are required for development of NEC, and TLR4 activation has been proposed as an initiator for disease development4. In the ileum where NEC occurs, TLR4 is expressed in the intestinal crypts. However, these studies were done in intestines that had not yet developed Paneth cells. Thus, it is unclear what role TLR4 plays in Paneth cell ablation-induced NEC. In this Aim we will examine the TLR4 signaling pathway in connection to Paneth cell disruption and subsequent injury. These proposed studies are innovative as they investigate a heretofore-unappreciated role for Paneth cells in the development of NEC. The results of this research will provide a clearer understanding of the mechanism of Paneth cell ablation-induced NEC in the immature intestine. This is the first important step needed for developing novel ways to predict disease development and new pharmacologic strategies to treat NEC.

Public Health Relevance

The proposed research is relevant to public health because determining the role of Paneth cells in the development of NEC is expected to increase understanding of the pathogenesis of NEC. As a consequence, we expect our studies to lead to a new vertical advancement in the study of NEC, and ultimately reduce the morbidity and mortality of premature infants. Thus, the proposed research is relevant to the NIH's mission to develop fundamental knowledge to enhance health and reduce burdens of human illness and disability.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Small Research Grants (R03)
Project #
1R03DK097335-01A1
Application #
8581538
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Podskalny, Judith M,
Project Start
2013-07-01
Project End
2015-06-30
Budget Start
2013-07-01
Budget End
2014-06-30
Support Year
1
Fiscal Year
2013
Total Cost
$75,500
Indirect Cost
$25,500
Name
University of Iowa
Department
Pediatrics
Type
Schools of Medicine
DUNS #
062761671
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Fricke, Erin M; Elgin, Timothy G; Gong, Huiyu et al. (2018) Lipopolysaccharide-induced maternal inflammation induces direct placental injury without alteration in placental blood flow and induces a secondary fetal intestinal injury that persists into adulthood. Am J Reprod Immunol 79:e12816
White, Jessica R; Gong, Huiyu; Pope, Brock et al. (2017) Paneth-cell-disruption-induced necrotizing enterocolitis in mice requires live bacteria and occurs independently of TLR4 signaling. Dis Model Mech 10:727-736
Fung, Camille M; White, Jessica R; Brown, Ashley S et al. (2016) Intrauterine Growth Restriction Alters Mouse Intestinal Architecture during Development. PLoS One 11:e0146542
Wynn, James Lawrence; Wilson, Chris S; Hawiger, Jacek et al. (2016) Targeting IL-17A attenuates neonatal sepsis mortality induced by IL-18. Proc Natl Acad Sci U S A 113:E2627-35
White, Jessica R; Gong, Huiyu; Colaizy, Tarah T et al. (2016) Evaluation of hematologic variables in newborn C57/BL6 mice up to day 35. Vet Clin Pathol 45:87-95
McElroy, Steven J (2015) The Role of Bacteria in Necrotizing Enterocolitis: Understanding the Forest for the Trees. Neonatology 108:196-7
McElroy, S J (2014) Unraveling the enigma that is neonatal necrotizing enterocolitis. J Perinatol 34:729-30
Brown, Kathryn S; Gong, Huiyu; Frey, Mark R et al. (2014) Tumor necrosis factor induces developmental stage-dependent structural changes in the immature small intestine. Mediators Inflamm 2014:852378
McElroy, Steven J; Castle, Shannon L; Bernard, Jessica K et al. (2014) The ErbB4 ligand neuregulin-4 protects against experimental necrotizing enterocolitis. Am J Pathol 184:2768-78