Immature intestinal NF-kB regulation, probiotics, and necrotizing enterocolitis

描述（由申请人提供）：坏死性小肠结肠炎（NEC）是一种危及生命的不明原因的炎症性肠病，约有10%的早产儿出生时体重<1500克。早产是最大的风险因素，而不是任何特定的侮辱，这表明肠道不成熟是一个根本问题。然而，导致NEC的不成熟的确切方面知之甚少。我发现未成熟和成熟肠上皮细胞（IEC）之间发育差异的关键点是核因子κ B的调节。作为对RFA-HD-07 - 08 "预防和治疗坏死性小肠结肠炎的新方法"的回应，我建议检验以下假设：肠上皮细胞NF-κ B调节的内在不成熟导致过度的炎症反应，使早产儿易患NEC。此外，我假设益生菌分泌的可溶性因子可以调节NF-κ B的调节和保护肠道屏障功能，从而减少炎症和保护免受NEC。该提案的初步数据表明，与成熟的IEC相比，未成熟的IEC在抑制性kappaB α和A20-关键NF-κ B下调蛋白的调节方面存在差异。此外，我们的初步数据表明，益生菌的分泌产物可以降低NF-kB活性，并在动物模型中保护免受NEC。益生菌是具有超出其固有营养价值的有益健康效果的细菌。最近的临床试验表明，益生菌可能会对NEC提供一些保护。该提案旨在1。评估在未成熟IEC中通过IkBa和A20的NF-κ B信号传导下调不足背后的可能机制。2.在不引入活微生物的动物模型中，测定益生菌植物乳杆菌、嗜酸乳杆菌和双歧杆菌分泌的细菌产物预防坏死性小肠结肠炎的能力。实验设计使用两种未成熟IEC模型-从断奶前小鼠和人胎儿小肠细胞系H4分离的IEC。将使用常规和无菌小鼠。为了对疾病建模，将使用已建立的NEC的Caplan大鼠模型。这一建议将产生重要的信息方面的肠道不成熟，有助于NEC和相关的理解任何拟议的治疗的效果。此外，了解无微生物益生菌条件培养基的潜在作用可以允许在没有活生物体风险的情况下施用益生菌的有益效果的手段，从而提供治疗或预防处于风险中的婴儿的NEC的新方法。公共卫生相关性：坏死性小肠结肠炎是一种知之甚少的早产儿危及生命的炎症性肠病。虽然20 - 30%的患者死亡，幸存者有严重的肠道和神经发育后果的风险，但没有已知的具体治疗方法。该提案将调查肠道不成熟的哪些方面导致这种疾病，并确定某些有益菌或益生菌分泌的因子是否会影响这些方面，从而降低脆弱婴儿对坏死性小肠结肠炎的易感性。

DESCRIPTION (provided by applicant): Necrotizing enterocolitis (NEC) is a life-threatening inflammatory bowel disorder of unknown cause that affects approximately 10% of premature infants born <1500gm. Prematurity is the greatest risk factor rather than any particular insult, suggesting that intestinal immaturity is a fundamental issue. However, the exact aspects of immaturity contributing to NEC are poorly understood. I have found that a key point of developmental difference between immature and mature intestinal epithelial cells (IEC) is regulation of nuclear factor kappaB. In response to RFA-HD-07-08 "New Approaches for the prevention and treatment of necrotizing enterocolitis," I propose to test the hypothesis that an intrinsic immaturity of intestinal epithelial cell NF-kB regulation leads to an exaggerated inflammatory response predisposing the preterm infant to NEC. Furthermore I hypothesize that soluble factors secreted by probiotic bacteria can modulate NF-kB regulation and preserve intestinal barrier function, thus decreasing inflammation and protecting against NEC. Preliminary data for this proposal demonstrate that compared to mature IEC, immature IEC have differences in regulation of both inhibitory kappaB alpha and A20 - key NF-kB down-regulatory proteins. Furthermore, our preliminary data demonstrate that secreted products from probiotic bacteria can decrease NF-kB activity and protect against NEC in an animal model. Probiotics are bacteria which have beneficial health effects beyond their inherent nutritive value. Recent clinical trials suggest that probiotics may confer some protection against NEC. This proposal is designed to 1. Assess possible mechanisms behind deficient down-regulation of NF-kB signaling via IkBa and A20 in immature IEC. 2. Determine the ability of secreted bacterial products from the probiotic organisms Lactobacillus plantarum, Lactobacillus acidophilus, and Bifidobacterium infantis to protect against necrotizing enterocolitis in an animal model without the introduction of live organisms. The experimental design uses two models of immature IEC - IEC isolated from pre-weaned mice and the human fetal small intestinal cell line H4. Both conventional and germ-free mice will be used. To model disease, the well established Caplan rat model of NEC will be used. This proposal will yield important information regarding aspects of intestinal immaturity which contribute to NEC and which are relevant to understanding the effect of any proposed treatment. Furthermore understanding the potential role of microbe free probiotic conditioned media may allow a means to administer the beneficial effects of probiotics without the risk of live organisms, thus providing a novel approach to treating or preventing NEC in at risk infants. PUBLIC HEALTH RELEVANCE: Necrotizing Enterocolitis is a poorly understood, life threatening inflammatory bowel disease of premature infants. Although 20-30% of patients die and survivors are at risk for significant intestinal and neurodevelopmental consequences, there is no known specific treatment. This proposal will investigate what aspects of intestinal immaturity contribute to this disease and determine if factors secreted by certain beneficial or probiotic bacteria can influence these aspects, thus decreasing the susceptibility of vulnerable infants to necrotizing enterocolitis.