Fellow Physician University of Iowa University of Iowa Iowa City, Iowa, United States
Background: Multiple studies have shown an association between chorioamnionitis and later development of necrotizing enterocolitis (NEC) in offspring, but mechanisms to explain this association are unclear. A major effect of chorioamnionitis is fetal exposure to maternal inflammation (FEMI). Our laboratory has shown that Paneth cell disruption is associated with development of NEC. However, the impact of FEMI on Paneth cell biology and susceptibility to NEC is not well understood.
Objective: Determine the impact of FEMI on Paneth cell development and subsequent susceptibility to development of NEC.
Design/Methods: FEMI was induced by injecting pregnant C57Bl/6J dams at e15.5 with intraperitoneal (IP) LPS (100 μg/kg). To induce NEC in P14 offspring, pups were administered IP dithizone (40 mg/kg) followed 8 hours later by enteral gavage of Klebsiella pneumoniae (1x108 CFU/g), and compared to sham controls. Serum and ileal tissue were harvested for quantification of inflammatory markers, gene regulation, tight junction localization, and histologic injury, and cecal samples were harvested for metagenomic sequencing. All groups had n ≥3 and statistical significance was set at 0.05.
Results: FEMI significantly reduced Paneth cell quantity (10% reduction at P14, 35% reduction at P28, p<0.05) and functional ability (30% reduction of α-defensin-1 mRNA compared to controls, p=0.003). FEMI did not increase intestinal injury compared to controls. However, while sham animals required both Paneth cell disruption and inflammatory dysbiosis for induction of NEC, pups with FEMI required only subsequent exposure to dysbiosis to induce equivalent intestinal injury (mean injury score in NEC group = 1.40, FEMI+Kleb group = 1.33, p>0.99). The combination of FEMI+NEC also induced a pro-inflammatory surge with significantly higher IL-6, KC-GRO (murine IL-8), and IL-17a compared to controls (all p<0.05). Conclusion(s): FEMI, which simulates chorioamnionitis, significantly impairs Paneth cell development and function. No differences were seen in severity of injury or phenotype of illness between FEMI and non-FEMI animals exposed to experimental NEC. However, FEMI was sufficient to allow for development of NEC-like injury when combined with exposure to inflammatory dysbiosis, even in the absence of dithizone-induced Paneth cell disruption. This suggests that disruption of Paneth cell biology by chorioamnionitis may be mechanistically linked to mortality and morbidity in offspring.
Authors/Institutions: Brian Juber, University of Iowa, Iowa City, Iowa, United States; Huiyu Gong, University of Iowa, Iowa City, Iowa, United States; Sarah N. Watson, University of Iowa, Iowa City, Iowa, United States; Shiloh R. Lueschow, University of Iowa, Iowa City, Iowa, United States; Tim Elgin, University of Iowa, Iowa City, Iowa, United States; Steven McElroy, University of Iowa, Iowa City, Iowa, United States