The viral dsRNA analogue poly (I:C) induces necrotizing enterocolitis in neonatal mice

Abstract

Background: Necrotizing enterocolitis (NEC) is a lifethreatening gastrointestinal disease in premature infants with high mortality and morbidity with uncertain pathogenesis. Recent research focused on the role of intraluminal bacteria and lipopolysaccharide (LPS). However, an additional role of viral agents in the pathogenesis of NEC has recently been postulated. We assessed the role of polyinosinic:polycytidylic acid (pIC) mimicking viral dsRNA in contributing to the development of NEC in neonatal mice. Methods: Four-d-old C57BL/6J pups were stressed by asphyxia and hypothermia twice daily. Animals were either fed by formula only (FO), formula containing LPS or pIC. After 72 h, mice were euthanized, intestines harvested, and the severity of NEC was assessed. results: Breastfed mice showed no evidence of NEC. Very mild NEC-like lesions were observed in mice fed by FO. Supplementation of LPS or pIC to the formula led to increased intestinal tissue damage and inflammation compared with FO in a similar manner. conclusion: Our study demonstrates the ability of viral factors to induce NEC in neonatal mice even in the absence of LPS. Furthermore, we present a new mouse model of pIC-induced NEC which may be used to obtain further mechanistic insights in the pathogenesis of this disease.

Dextran sodium sulfate (DSS) induces necrotizing enterocolitis-like lesions in neonatal mice

“…The remaining intestinal tissue was fixed for three days in 10% buffered paraformaldehyde (PFA) and embedded in paraffin, sectioned (4 μm) and stained with hematoxylin-eosin using a standard protocol. Small and large intestinal tissue was investigated histologically for intestinal damage as previously described [ 11 ].…”

“…Animals were randomly divided into two groups (i) LPS: Formula feeding supplemented with LPS from E . coli 0127:B8 (10μg/g body weight, Sigma Aldrich) and exposure to hypothermia and hypoxia as previously described [ 11 ]; (ii) DSS: Formula feeding supplemented with 3% (w/v) DSS without physical stress. Age-matched breast fed animals served as controls.…”

“…The longitudinal length of intestinal defects (= size of intestinal lesions) was measured using a scale bar. The severity of intestinal lesions was assessed by two blinded investigators (RvW, JKP) using an intestinal tissue injury score (0–4) based on the histologic injury scoring system of Caplan et al [ 2 , 11 ]: Grade 0: intact villi; 1: superficial epithelial cell sloughing; 2: mid-villous necrosis; 3: complete villous necrosis; 4: transmural necrosis. Samples with histological scores of 2 or higher were considered positive for NEC.…”

“…Total RNA was isolated from whole organ jejunal, ileal and colonic samples of adult and neonatal mice using the RNeasy mini kit (Qiagen, Hilden, Germany) according to the manufacturer’s instructions as described previously [ 11 ]. The concentration and purity was determined with a Nanodrop 2000 spectrophotometer (Thermo scientific, Waltham, MA, USA), integrity was analyzed on a 2% agarose gel.…”

Berberine ameliorates neonatal necrotizing enterocolitis by activating the phosphoinositide 3-kinase/protein kinase B signaling pathway

“…Necrosis of the intestinal tract significantly compromises the function of the digestive system and results in a loss of appetite and weight loss (4). Additionally, previous studies have indicated that inflammation and apoptosis are associated with disease progression in patients with neonatal NEC (5,6). Therefore, attenuating inflammation and inhibiting the apoptosis of epithelial cells in the small intestine are potential methods of treating neonatal NEC.…”