A Neonatal BALB/c Mouse Model of Necrotizing Enterocolitis

Summary

Necrotizing enterocolitis (NEC) is the most severe gastrointestinal (GI) disease that often occurs in premature infants, especially very low birth weight infants, with high mortality and unclear pathogenesis. The cause of NEC may be related to inflammatory immune regulatory system abnormalities. An NEC animal model is an indispensable tool for NEC disease immune research. NEC animal models usually use C57BL/6J neonatal mice; BALB/c neonatal mice are rarely used. Related studies have shown that when mice are infected, Th2 cell differentiation is predominant in BALB/c mice compared to C57BL/6J mice. Studies have suggested that the occurrence and development of NEC are associated with an increase in T helper type 2 (Th2) cells and are generally accompanied by infection. Therefore, this study used neonatal BALB/c mice to induce an NEC model with similar clinical characteristics and intestinal pathological changes as those observed in children with NEC. Further study is warranted to determine whether this animal model could be used to study Th2 cell responses in NEC.

Abstract

Necrotizing enterocolitis (NEC) is the most severe gastrointestinal (GI) disease that often occurs in premature infants, especially very low birth weight infants, with high mortality and unclear pathogenesis. The cause of NEC may be related to inflammatory immune regulatory system abnormalities. An NEC animal model is an indispensable tool for NEC disease immune research. NEC animal models usually use C57BL/6J neonatal mice; BALB/c neonatal mice are rarely used. Related studies have shown that when mice are infected, Th2 cell differentiation is predominant in BALB/c mice compared to C57BL/6J mice. Studies have suggested that the occurrence and development of NEC are associated with an increase in T helper type 2 (Th2) cells and are generally accompanied by infection. Therefore, this study used neonatal BALB/c mice to induce an NEC model with similar clinical characteristics and intestinal pathological changes as those observed in children with NEC. Further study is warranted to determine whether this animal model could be used to study Th2 cell responses in NEC.

Introduction

Necrotizing enterocolitis (NEC), the most severe gastrointestinal (GI) disease, occurs in most premature infants (>90%), especially those with very low birth weight (VLBW)¹. In VLBW infants, the incidence of the disease ranges from 10% to 12%, and the mortality of children diagnosed with NEC is between 20% and 30%^2,3. The cause of NEC may be related to mucosal injuries, invasion by pathogenic bacteria, and intestinal feeding, which can lead to inflammatory responses and the induction of intestinal injuries in susceptible hosts³. The pathogenesis of NEC is unc....

Protocol

This research was approved by the Medical Ethics Committee of Guangzhou Women and Children's Medical Center (NO. 174A01) and the Animal Ethical Committee of the Guangzhou Forevergen Biosciences Laboratory Animal Center (IACUC-G160100). All animals were bred in the same room in a specific pathogen-free (SPF) environment, and experiments were carried out in a conventional environment. The mice used for breeding were 7-8 weeks old; the mice for inducing NEC (n = 72) were separated from the dam on Day 4, and the dams(n=14) were kept in the original cage and nursed the control (Cont.) group mice(n=24).

1. Preparation of reage....

Results

The BALB/c mouse NEC model was induced by formula feeding, LPS feeding, hypoxia, and cold stimulation. During the induction period, the mice were observed for intestinal pathology, stool characteristics, body weight changes, and daily survival. Representative images of the small intestine during NEC induction; the numbers in the picture represent the intestinal pathology score from 0 (normal epithelium) to 4 (the most severe) (Figure 3A). The intestinal pathology score was significantly high.......

Discussion

NEC is the most common gastrointestinal system emergency for neonates, with a high incidence and mortality, especially in premature infants^1,2,3. However, its pathogenesis is still unclear. It is currently believed that mucosal damage, pathogen invasion, and enteral feeding are high-risk factors for NEC³. To date, the animals used for the NEC model are mainly pigs, rats, and mice. Most studies have used n.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Absolute ethanol	Sinopharm Chemical Reagent Co., LTD.	100092683
Goat Milk powder	Petag	71795558417
HE dye solution	Sinopharm Chemical Reagent Co., LTD.	G1003
Isoflurane	RWD, Shenzhen Reward Life Technology Co., LTD.	R510
LPS	Sigma-Adrich	L2880
Medical oxygen	various	various
Microscope	NIKON	NIKON imaging system (DS-Ri2)
Neutral resin	Sinopharm Chemical Reagent Co., LTD.	10004160
Paraffin	various	various
Premature baby milk powder	Abbott	57430
Xylene	Sinopharm Chemical Reagent Co., LTD.	10023418
1% Hydrochloric acid	various	various
10% Formalin	LEAGENE	DF0110