Liu Jia, Zhu Haitao, Li Bo, Robinson Shaiya C, Lee Carol, O'Connell Joshua S, Bindi Edoardo, Zheng Shan, Sherman Philip M, Pierro Agostino
Department of Pediatric Surgery, Children's Hospital of Fudan University, Shanghai, China.
Department of General and Thoracic Surgery, Hospital for Sick Children, Toronto, Ontario, Canada.
Eur J Pediatr Surg. 2020 Feb;30(1):90-95. doi: 10.1055/s-0039-1693728. Epub 2019 Jul 25.
Necrotizing enterocolitis (NEC) is a devastating intestinal illness in premature infants characterized by severe intestinal inflammation. Despite medical interventions, NEC mortality remains alarmingly high, which necessitates improved therapies. Lactoferrin is among the most abundant proteins in human milk and has important immunomodulatory functions. While previous studies have indicated protective effects of lactoferrin against neonatal sepsis and NEC, the underlying mechanism remains unclear. We hypothesize that lactoferrin downregulates inflammation and upregulates proliferation in intestinal epithelium during NEC injury.
NEC was induced by hypoxia, gavage feeding of hyperosmolar formula and lipopolysaccharide between postnatal day P5 and P9 ( = 8). Breastfed mice were used as control ( = 7). Lactoferrin (0.3 g/kg/day) was administered once daily by gavage from P6 to P8 in both NEC (NEC + Lac; = 9) and control mice (Cont + Lac; = 5). Distal ileum was harvested on P9 and analyzed for disease severity, inflammation, and proliferation. Groups were compared using one-way ANOVA and -test appropriately; < 0.05 was considered significant.
Compared to NEC group, lactoferrin-treated NEC mice had reduced disease severity, reduced inflammation markers IL-6 and TNF-α expression and increased intestinal stem cell marker Lgr5 + expression. Lactoferrin-treated NEC mice exhibited increased nuclear β-catenin, indicating upregulated Wnt pathway, and increased Ki67 positivity, suggesting enhanced proliferation. Furthermore, lactoferrin administration to control mice did not affect intestinal inflammation as well as Lgr5 + stem cell expression and epithelial proliferation. This supports the safety of lactoferrin administration and indicates that the beneficial effects of lactoferrin are present when intestinal injury such as NEC is present.
Lactoferrin administration reduces the intestinal injury in experimental NEC by downregulating inflammation and upregulating cell proliferation. This beneficial effect of lactoferrin in stimulating cell proliferation is mediated by the Wnt pathway. This experimental study provides insights on the mechanism of action of lactoferrin in NEC and the role of lactoferrin in enteral feeding.
坏死性小肠结肠炎（NEC）是一种发生于早产儿的严重肠道疾病，其特征为严重的肠道炎症。尽管采取了医学干预措施，NEC的死亡率仍然高得惊人，因此需要改进治疗方法。乳铁蛋白是母乳中含量最丰富的蛋白质之一，具有重要的免疫调节功能。虽然先前的研究表明乳铁蛋白对新生儿败血症和NEC有保护作用，但其潜在机制仍不清楚。我们推测，在NEC损伤期间，乳铁蛋白可下调肠道上皮细胞的炎症反应并上调其增殖能力。
在出生后第5天至第9天（共8天）期间，通过缺氧、灌喂高渗配方奶和脂多糖诱导NEC。以母乳喂养的小鼠作为对照（共7只）。在NEC组（NEC + Lac；共9只）和对照组小鼠（Cont + Lac；共5只）中，从出生后第6天至第8天，每天通过灌胃给予乳铁蛋白（0.3 g/kg/天）。在出生后第9天采集远端回肠，分析疾病严重程度、炎症反应和增殖情况。使用单因素方差分析和适当的检验对各组进行比较；P < 0.05被认为具有统计学意义。
与NEC组相比，经乳铁蛋白治疗的NEC小鼠疾病严重程度降低，炎症标志物白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）的表达减少，肠道干细胞标志物Lgr5 +的表达增加。经乳铁蛋白治疗的NEC小鼠细胞核β-连环蛋白增加，表明Wnt信号通路上调，Ki67阳性率增加，提示增殖增强。此外，对对照组小鼠给予乳铁蛋白并不影响肠道炎症以及Lgr5 +干细胞表达和上皮细胞增殖。这支持了乳铁蛋白给药的安全性，并表明当存在如NEC这样的肠道损伤时，乳铁蛋白具有有益作用。
给予乳铁蛋白可通过下调炎症反应和上调细胞增殖来减轻实验性NEC中的肠道损伤。乳铁蛋白在刺激细胞增殖方面的这种有益作用是由Wnt信号通路介导的。这项实验研究为乳铁蛋白在NEC中的作用机制以及乳铁蛋白在肠内喂养中的作用提供了见解。
