Pentoxifylline reduces the incidence and severity of necrotizing enterocolitis in a neonatal rat model

Necrotizing enterocolitis (NEC) is a potentially fatal illness in premature neonates. Tumor necrosis factor alpha (TNF-alpha) has been shown to play a central role in the inflammatory cascade leading to the development of NEC. Published evidence points to a significant role of pentoxifylline in inhibition of TNF-alpha and in reducing mucosal injury and improving healing in ischemia-reperfusion experiments. Our aim was to investigate the effect of pentoxifylline on the incidence of NEC in a neonatal rat model. Newborn Sprague-Dawley rat pups originating from eight separate litters were delivered by cesarean section at 21.5 d and were formula fed from birth by orogastric gavage. The rat pups were randomized to receive either intraperitoneal pentoxifylline (15 mg/kg/dose) or placebo, given every 8 h beginning at 24 h of age, in a blinded fashion. Experimental NEC was induced by exposure to hypoxia for 60 s followed by cold stress at 4 degrees C for 10 min. The animals were euthanized at development of NEC or at 96 h and intestinal tissue was processed and examined for histologic changes of NEC. The incidence of NEC was significantly lower in the pentoxifylline group [pentoxifylline 5/38 versus placebo 15/36; p = 0.008, odds ratio (OR) = 0.21 95% confidence interval (CI) 0.07-0.67]. Among the pups developing NEC, significantly fewer rat pups treated with pentoxifylline had severe (>or=3) intestinal injury scores [pentoxifylline 1/5 versus placebo 10/15; p = 0.031, OR 0.06, 95% CI 0.01-0.79]. We conclude that intraperitoneal administration of pentoxifylline significantly reduced the incidence and severity of NEC in our experimental animal model.     

Effect of polyunsaturated fatty acid (PUFA) supplementation on intestinal inflammation and necrotizing enterocolitis (NEC) in a neonatal rat model

Inasmuch as long-chain polyunsaturated fatty acids (PUFA, metabolites of the essential n-3 and n-6 fatty acids) are known to modulate inflammation, we hypothesized that supplementation of formula with these compounds would prevent necrotizing enterocolitis (NEC) and intestinal inflammation in our neonatal rat model. Newborn rats were stressed with asphyxia and formula feeding, and randomly assigned to control formula, control with PUFA supplementation, and PUFA with nucleotides. Animals were followed for 72--96 h and assessed for death, gross and histologic NEC, intestinal apoptosis, endotoxemia, and intestinal mRNA synthesis of phospholipase A(2)-II (rate-limiting enzyme for platelet activating factor production), platelet activating factor receptor, and inducible nitric oxide synthase. We found that PUFA reduced the incidence of death and NEC compared with the other groups (NEC 8 of 24 versus 17 of 24 control and 13 of 23 PUFA + nucleotides, p < 0.05). Furthermore, PUFA reduced plasma endotoxemia at 48 h (25 +/- 4 EU/mL versus 276 +/- 39 EU/mL in control and 170 +/- 28 EU/mL in PUFA + nucleotide), intestinal phospholipase A(2)-II expression at 24 h, and platelet activating factor receptor expression at 48 h. Formula supplementation had no effect on apoptosis of intestinal epithelium or intestinal inducible nitric oxide synthase expression. Addition of nucleotides with PUFA abrogated the beneficial effects of PUFA on intestinal inflammation. We conclude that PUFA reduces the incidence of NEC and intestinal inflammation in a neonatal rat model.     

Maternal milk reduces severity of necrotizing enterocolitis and increases intestinal IL-10 in a neonatal rat model

Necrotizing enterocolitis (NEC) is a devastating intestinal disease of premature infants. Maternal milk has been suggested to be partially protective against NEC; however, the mechanisms of this protection are not defined. The aim of this study was to examine the effect(s) of artificial feeding of rat milk (RM)-versus cow milk-based rat milk substitute (RMS) on the development of NEC in a neonatal rat model and elucidate the role of inflammatory cytokines in NEC pathogenesis. Newborn rats were artificially fed with either collected RM or RMS. Experimental NEC was induced by exposure to asphyxia and cold stress and evaluated by histologic scoring of damage in ileum. Intestinal cytokine mRNA expression was determined by real-time PCR. Cytokine histologic localization was performed by confocal microscopy. Similar to human NEC, artificial feeding of RM reduces the incidence and severity of NEC injury in neonatal rats. Freezing and thawing of collected RM did not eliminate the protective effect of maternal milk. Ileal IL-10 expression was significantly increased in the RM group compared with RMS. Increased IL-10 peptide production was detected in the RM group with signal localized predominantly in the cytoplasm of villus epithelial cells. These results suggest that the protective effect of maternal milk is associated with increased production of anti-inflammatory IL-10 in the site of injury. Better understanding of the mechanisms underlying these protective effects could be beneficial either in the prevention of NEC or in the development of future therapeutic strategies to cure NEC.     

新生鼠坏死性小肠结肠炎动物模型建立及评价

目的 利用新生SD大鼠建立缺氧、冷刺激、鼠乳代用品人工喂养等多因素造成的新生鼠坏死性小肠结肠炎动物模型,并对其进行评价.方法 按析因设计,32只新生SD大鼠出生48 h开始随机分成4组,每组动物各8只.A组采用鼠乳代用品人工喂养,并给予100%氮气缺氧90 s,4 ℃冷刺激10 min,每天2次,连续3 d;B组为单纯采用鼠乳代用品人工喂养,未进行缺氧冷刺激;C组采用鼠乳喂养,给予同样的缺氧冷刺激;D组为正常对照组,采用鼠乳喂养,未进行缺氧冷刺激.HE染色后光镜下观察回盲部近端肠组织形态学改变,采用肠损伤病理评分进行评价,组织学评分≥2分确定为坏死性小肠结肠炎(NEC).结果 A、B、C组新生SD大鼠相继出现腹泻、腹胀、萎靡、活动减少,生长减慢,A组程度最为严重.A、B、C、D 4组肠损伤病理评分(±s)分别为(3.25±0.89)分、(2.63±0.92)分、(1.13±1.36)分、(0.25±0.46)分,各组间差异均有统计学意义(H=19.30,P＜0.01).NEC发病率分别为100%、87.5%、37.5%和0.喂养方式和缺氧冷刺激为肠组织损伤病理评分值影响因素,两因素间无明显交互作用.结论 新生鼠在剔除鼠乳喂养,改用鼠乳代用品人工喂养的前提下,经过连续多次的缺氧冷刺激后,诱导的新生鼠坏死性小肠结肠炎模型与人类新生儿NEC临床特征、病理改变相一致,是一种理想的新生儿坏死性小肠结肠炎动物模型.     

新生鼠坏死性小肠结肠炎动物模型建立及评价

目的利用新生SD大鼠建立缺氧、冷刺激、鼠乳代用品人工喂养等多因素造成的新生鼠坏死性小肠结肠炎动物模型,并对其进行评价。方法按析因设计,32只新生SD大鼠出生48h开始随机分成4组,每组动物各8只。A组采用鼠乳代用品人工喂养,并给予100%氮气缺氧90s,4℃冷刺激10min,每天2次,连续3d;B组为单纯采用鼠乳代用品人工喂养,未进行缺氧冷刺激;C组采用鼠乳喂养,给予同样的缺氧冷刺激;D组为正常对照组,采用鼠乳喂养,未进行缺氧冷刺激。HE染色后光镜下观察回盲部近端肠组织形态学改变,采用肠损伤病理评分进行评价,组织学评分≥2分确定为坏死性小肠结肠炎(NEC)。结果A、B、C组新生SD大鼠相继出现腹泻、腹胀、萎靡、活动减少,生长减慢,A组程度最为严重。A、B、C、D4组肠损伤病理评分(x-±s)分别为(3.25±0.89)分、(2.63±0.92)分、(1.13±1.36)分、(0.25±0.46)分,各组间差异均有统计学意义(H=19.30,P<0.01)。NEC发病率分别为100%、87.5%、37.5%和0。喂养方式和缺氧冷刺激为肠组织损伤病理评分值影响因素,两因素间无明显交互作用。结论新生鼠在剔除鼠乳喂养,改用鼠乳代用品人工喂养的前提下,经过连续多次的缺氧冷刺激后,诱导的新生鼠坏死性小肠结肠炎模型与人类新生儿NEC临床特征、病理改变相一致,是一种理想的新生儿坏死性小肠结肠炎动物模型。     

新生儿坏死性小肠结肠炎血浆肠脂肪酸结合蛋白水平变化的意义

目的 探讨血浆肠脂肪酸结合蛋白（I-FABP）水平变化在指导新生儿坏死性小肠结肠炎（NEC）诊断及治疗中的意义.方法 选择2011年5月至2012年12月我院新生儿科收治的患儿,按入院先后顺序,以明确诊断NEC的50例新生儿为NEC组,其中NECⅡ期30例,NECⅢ期20例,以非NEC新生儿50例为对照组.NEC组在确诊后24 h内、对照组在相应日龄取血,采用酶联免疫吸附法（ELISA）检测血浆I-FABP水平,根据NEC患儿病情转归分为存活组及病死组,按治疗方法分为保守治疗组和手术治疗组,比较不同组间血浆I-FABP水平、新生儿危重病例评分（NCIS）分值、脓毒症的发生率及病死率.结果 NECⅡ期组、NECⅢ期组和对照组血浆I-FABP水平分别为（95.6±18.5） μmol/L、（151.2±10.8）μmol/L和（1.2±2.3）μmol/L,组间比较差异有统计学意义（P＜0.05）;NECⅡ期组和NECⅢ期组NCIS评分明显低于对照组,脓毒症发生率和病死率均高于对照组,差异有统计学意义（P＜0.05）,NECⅡ期组和NECⅢ期组差异无统计学意义（P＞0.05）.病死组血浆I-FABP水平、脓毒症发生率高于存活组,NCIS评分低于存活组;保守治疗组I-FABP水平低于手术治疗组,NCIS评分高于手术治疗组,差异均有统计学意义（P＜0.05）.结论 血浆I-FABP水平可较敏感地反映NEC患儿的病情变化,可作为预测NEC病情严重程度及指导采取内外科治疗的指标之一.     

新生鼠坏死性小肠结肠炎肠组织血小板活化因子与肿瘤坏死因子变化及意义

目的 研究新生鼠肠损伤时肠组织中血小板活化因子(PAF)、肿瘤坏死因子(TNF)-α含量变化及肠组织损伤程度与肠组织中PAF、TNF-α表达水平的关系,探讨将PAF、TNF-α表达水平作为肠损伤的检测指标的可能性.方法 按析因设计,32只48 h新生SD大鼠随机分成4组,每组各8只.A组给予鼠乳代用品人工喂养,每天2次连续3 d给予100%氮气缺氧90 s,4℃冷刺激10 min;B组用鼠乳代用品人工喂养3 d,未受缺氧和冷刺激;C组每天2次连续3 d给予100%氮气缺氧90 s,4℃冷刺激10min、鼠母乳喂养;D组为正常对照组.在实验结束后24 h空腹断头处死大鼠,留取十二指肠下端至直肠上端肠道组织进行肠组织损伤评分和肠组织中PAF、TNF-α含量检测.组织学评分≥2确定为坏死性小肠结肠炎(NEC);肠组织中PAF、TNF-α含量采用ELISA双抗体夹心法检测.应用Kruskal-Wallis H检验等方法进行统计学分析,α=0.05为显著性检验标准.结果 经Kruskal-Wallis H检验,A、B、C、D各组肠组织PAF、TNF-α含量不同,差异有显著性.采用非参数Spearman等级相关分析结果 ,肠组织PAF含量与相应平均损伤程度均呈显著正相关关系(r=0.71,P＜0.05);肠组织TNF-α含量与相应平均损伤程度均呈显著正相关关系(r=0.81,P<0.05).结论 肠组织内源性聊小和TNF-a可能是NEC发生的关键介质,其本身又作为致病因子参与了NEC的发生和发展.肠损伤程度与肠组织中PAF、TNF-α含量呈正相关,肠组织中PAF和TNF-α含量与肠黏膜损伤评分一样能反映肠黏膜损伤程度.     

H2S 通过上调HO-1 表达保护坏死性小肠结肠炎大鼠肠黏膜

目的观察新型外源性硫化氢(H2S)供体GYY 4137对坏死性小肠结肠炎(NEC)大鼠肠黏膜的保护作用,并探讨其可能的作用机制。方法取60只健康新生SD大鼠,随机分成4组。正常对照组,不施加任何干预;NEC模型组,通过人工喂养、缺氧、冷刺激、脂多糖方法制备NEC模型;H_2S干预组,在NEC模型的基础上,腹腔注射H2S供体GYY 4137;血红素加氧酶-1(HO-1)抑制剂组,在H_2S干预组已有干预的基础上,腹腔注射HO-1抑制剂Znpp。于试验第4天处死大鼠,取回盲部肠管进行苏木精-伊红(HE)染色并作组织病理学评分;检测各组新生鼠小肠组织中丙二醛(MDA)及超氧化物歧化酶(SOD)含量,肿瘤坏死因子α(TNF-α)水平以及肠道组织HO-1表达。结果 4组新生大鼠肠组织病理评分的差异有统计学意义(P0.001),NEC模型组的病理评分最高,其次为HO-1抑制剂组、H_2S干预组。NEC组病理评分≥2,表明建模方法有效。NEC组与对照组相比,MDA及TNF-α含量明显上升,T-SOD含量下降,差异有统计学意义(P0.05);H_2S干预组同NEC组相比,MDA及TNF-α含量明显降低,T-SOD含量明显升高,HO-1表达增加,差异有统计学意义(P0.05);HO-1抑制剂组较H_2S干预组相比,MDA及TNF-α含量明显升高,T-SOD含量降低,差异有统计学意义(P0.05)。结论新型H2S供体GYY 4137能够有效保护NEC大鼠肠黏膜,降低MDA及TNF-α的含量,增加T-SOD的含量;其保护作用可能与上调HO-1蛋白的表达有关。     

肠道微生物稳态对坏死性小肠结肠炎新生大鼠模型造血系统的影响北大核心CSCD

目的探讨肠道菌群对坏死性小肠结肠炎(necrotizing enterocolitis,NEC)新生大鼠模型造血系统的影响。方法Sprague-Dawley新生大鼠随机分为对照组和模型组(NEC组),每组6只。采用配方奶结合缺氧和冷刺激构建NEC新生大鼠模型。苏木精-伊红染色观察肠组织及造血相关器官病理变化;检测各组血常规;免疫组化法检测造血相关器官中特定细胞的改变;流式细胞术检测骨髓中特定细胞的变化;采用16S rDNA测序技术检测分析各组肠道菌群的组成及丰度。结果与对照组比较,NEC组肠组织充血坏死,肠绒毛破损、萎缩脱落,NEC病理评分显著增加;NEC组外周血白细胞及淋巴细胞计数显著低于对照组(P<0.05);NEC组脾脏、胸腺、骨髓的有核细胞及肝脏的嗜碱性细胞核的小细胞聚集体数量均明显少于对照组;NEC组肝脏中CD71^(+)红系祖细胞显著减少,脾脏、骨髓中的CD45^(+)白细胞及胸腺中的CD3^(+)T淋巴细胞显著降低,骨髓中CD45^(+)CD3^(-)CD43^(+)SSChi的中性粒细胞比例明显下降(P<0.05);NEC组肠道菌群组成与对照组比较差异明显,NEC组利乳杆菌属的相对丰度降低,而埃希菌-志贺菌属的相对丰度显著升高(P<0.05),取代利乳杆菌属成为优势菌属。结论NEC新生大鼠模型存在多谱系造血异常,可能与肠道微生物稳态失衡及致病菌属埃希菌-志贺菌属的异常扩增有关。     

肠三叶因子在新生鼠坏死性小肠结肠炎模型中对Bax和Bcl-2及Caspase-3表达的影响及意义

目的 通过研究肠三叶因子(ITF)对新生大鼠坏死性小肠结肠炎(NEC)模型肠组织病理学改变及肠道组织中蛋白酶Caspase-3、蛋白Bax和Bcl-2的含量变化,探讨ITF对NEC保护作用的可能机制.方法 30只新生1日龄Wistar大鼠随机分为3组,正常对照组、实验组、干预组,每组10只.实验组为NEC模型后加生理盐水0.2 ml腹腔注射;干预组为NEC模型后予以腹腔注射TTF 0.2 mg(0.2 ml);正常对照组未予处理.第4天处死所有大鼠,取肠组织待检,取近回盲部1～2 cm肠道组织,采用分光光度法检查Caspase-3的表达、采用免疫组化法检测肠道组织中Bax及Bcl-2的含量变化并做病理学检查.结果 实验组Caspase-3表达高于正常对照组和干预组(P均＜0.05),干预组与正常对照组比较差异无统计学意义(P＞0.05);实验组Bax表达高于正常对照组和干预组(P均＜0.05),干预组与正常对照组相近(P＞0.05);干预组Bcl-2表达高于正常对照组和干预组(P均＜0.05),实验组高于正常对照组(P＜0.05).正常对照组的肠组织病理学未见异常,病理评分为0分;实验组HE染色切片见肠壁损伤轻重不一,可见全肠黏膜绒毛坏死,病理评分的中位积分为3分;干预组肠上皮细胞少量脱落,顶端绒毛坏死,病理评分的中位积分为1分.与实验组比较,ITF治疗后NEC导致的组织病理学改变明显减轻.结论 注射ITF可通过减少Caspase-3、Bax表达和增加Bcl-2表达减轻NEC肠道损伤.     

肠三叶因子在新生鼠坏死性小肠结肠炎模型中对Bax和Bcl-2及Caspase-3表达的影响及意义

目的通过研究肠三叶因子(ITF)对新生大鼠坏死性小肠结肠炎(NEC)模型肠组织病理学改变及肠道组织中蛋白酶Caspase-3、蛋白Bax和Bcl-2的含量变化,探讨ITF对NEC保护作用的可能机制。方法30只新生1日龄Wistar大鼠随机分为3组,正常对照组、实验组、干预组,每组10只。实验组为NEC模型后加生理盐水0.2ml腹腔注射;干预组为NEC模型后予以腹腔注射ITF 0.2 mg(0.2 ml);正常对照组未予处理。第4天处死所有大鼠,取肠组织待检,取近回盲部1～2 cm肠道组织,采用分光光度法检查Caspase-3的表达、采用免疫组化法检测肠道组织中Bax及Bcl-2的含量变化并做病理学检查。结果实验组Caspase-3表达高于正常对照组和干预组(P均<0.05),干预组与正常对照组比较差异无统计学意义(P>0.05);实验组Bax表达高于正常对照组和干预组(P均<0.05),干预组与正常对照组相近(P>0.05);干预组Bcl-2表达高于正常对照组和干预组(P均<0.05),实验组高于正常对照组(P<0.05)。正常对照组的肠组织病理学未见异常,病理评分为0分;实验组HE染色切片见肠壁损伤轻重不一...     

肠细胞凋亡在新生鼠坏死性小肠结肠炎肠损伤中动态变化

目的 动态观察新生大鼠坏死性小肠结肠炎(NEC)发病过程中肠细胞凋亡率变化及其与肠损伤关系.方法 40只新生SD大鼠随机分成对照组(C)和模型组(M).对照组8只;模型组32只,在出生48 h开始给予鼠配方奶人工喂养,100%氮气缺氧90 s,4℃冷刺激10 min,每天2次,连续3 d,建立新生大鼠NEC模型;模型组开始造模后24 h(M24)、48 h(M48)、72 h(造模结束,M72)及造模结束后24 h(M96)分别处死8只,留取肠管进行肠组织损伤评分和肠细胞凋亡率检测(流式细胞仪).组织学评分≥2确定为NEC.各组随机选取1份回盲部近端小肠标本进行肠黏膜透射电镜检查.采用SPSS 11.0统计学软件进行统计分析,α =0.05为显著性检验标准.结果 透射电镜显示模型组大鼠肠黏膜出现大量凋亡细胞,形成凋亡小体.对照组、M24、M48、M72和M96肠组织损伤评分分别为(0.08±0.15)、(1.38±0.42)、(1.46±0.69)、(1.58±0.30)分和(3.33±0.59)分,肠细胞凋亡率分别为4.8%±2.9%、12.8%±6.3%、14.9%±5.5%、17.7%±5.5%和27.6%±9.9%.肠损伤程度与肠细胞凋亡率呈显著正相关(r＜凋亡率=0.853,P＜0.01).结论 新生鼠肠细胞凋亡增加是NEC肠组织损伤起始事件;随时间延长,肠细胞凋亡增加程度进一步加重;肠细胞凋亡增加是造成新生鼠NEC肠道进行性损伤的病理基础.     

肠细胞凋亡在新生鼠坏死性小肠结肠炎肠损伤中动态变化

目的动态观察新生大鼠坏死性小肠结肠炎(NEC)发病过程中肠细胞凋亡率变化及其与肠损伤关系。方法40只新生SD大鼠随机分成对照组(C)和模型组(M)。对照组8只;模型组32只,在出生48h开始给予鼠配方奶人工喂养,100%氮气缺氧90s,4℃冷刺激10min,每天2次,连续3d,建立新生大鼠NEC模型;模型组开始造模后24h(M24)、48h(M48)、72h(造模结束,M72)及造模结束后24h(M96)分别处死8只,留取肠管进行肠组织损伤评分和肠细胞凋亡率检测(流式细胞仪)。组织学评分≥2确定为NEC。各组随机选取1份回盲部近端小肠标本进行肠黏膜透射电镜检查。采用SPSS11.0统计学软件进行统计分析,α=0.05为显著性检验标准。结果透射电镜显示模型组大鼠肠黏膜出现大量凋亡细胞,形成凋亡小体。对照组、M24、M48、M72和M96肠组织损伤评分分别为(0.08±0.15)、(1.38±0.42)、(1.46±0.69)、(1.58±0.30)分和(3.33±0.59)分,肠细胞凋亡率分别为4.8%±2.9%、12.8%±6.3%、14.9%±5.5%、17.7%±5.5%和27.6%±9.9%。肠损伤程度与肠细胞凋亡率呈显著正相关(r凋亡率=0.853,P<0.01)。结论新生鼠肠细胞凋亡增加是NEC肠组织损伤起始事件;随时间延长,肠细胞凋亡增加程度进一步加重;肠细胞凋亡增加是造成新生鼠NEC肠道进行性损伤的病理基础。     

Serum cytosolic beta-glucosidase activity in a rat model of necrotizing enterocolitis

The diagnosis of necrotizing enterocolitis (NEC) is made from a combination of clinical and radiographic findings. There are no useful screening biochemical markers of intestinal injury. The serum concentration of cytosolic beta-glucosidase (CBG), an enzyme found primarily in enterocytes, is markedly elevated in animal models of ischemia and bowel obstruction. We hypothesized that in a rat model of NEC, serum CBG activity would significantly increase before microscopic evidence of severe intestinal injury. Cohorts of 2-wk-old Sprague-Dawley rats (n = 10/cohort) were anesthetized and underwent laparotomy with occlusion of the superior mesenteric artery (SMA). Platelet-activating factor (200 microg/animal) was injected in the proximal duodenum. Serum and intestinal samples were obtained at time 0 (control) and 30, 60, and 90 min of ischemia (I) and after 90 min of I followed by 60 min of reperfusion (I/R). Histopathologic injury was categorized as either no or minimal injury or mural necrosis by two masked investigators and CBG activity was measured by ELISA. Data were analyzed with Fisher's exact test and ANOVA. Only the I/R group had significantly greater mural necrosis compared with the control group (90% versus 0%, respectively, p < 0.001). In contrast, CBG activity was significantly elevated after only 90 min of I and after I/R (15.1 +/- 5.6 and 16.4 +/- 4.3 units/mL, respectively, p < 0.05). We conclude that serum CBG is elevated before transmural intestinal injury in this model and may have utility as an early marker of ischemia in patients at risk for NEC.     

Seasonal variation in the incidence of necrotizing enterocolitis

Background  

Necrotizing enterocolitis (NEC) has been reported to occur in a sporadic manner and in clusters of cases. We hypothesized that variations in the incidence of NEC were random, without clustering. In order to define the pattern of NEC in the United States, we analyzed the Pediatric Health Information System (PHIS) database to evaluate whether NEC cases are distributed randomly or exhibit temporal clustering or periodicity.     

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??Necrotizing enterocolitis??NEC?? is considered to be the most common gastrointestinal emergency among neonates. Although the pathogenesis of NEC is incompletely understood??there are several established risk factors??including prematurity??altered intestinal blood flow/oxygen delivery??formula feeding and bacterial infection. Recently??a large number of studies showed that intestinal flora imbalance had been implicated as key risk factor in the pathogenesis of NEC. After birth??the neonatal gut must acquire a healthy complement of commensal bacteria??which leads to deficient or abnormal microbial colonization of the gut??may protect the immature gut from inflammation and injury. Providing a healthy complement of commensal bacteria can maintain the intestinal microflora balance??shift the balance of intestinal microbiota from a pathegenic to protective complement of bacteria??protect the gut from inflammation and subsequent injury??and prevent NEC. We review the relationship between intestinal microbiota and NEC in preterm infants??the mechanism of probiotics in preventing NEC??and the efficacy and safety of probiotics in preterm infants.     

Intestinal epithelial apoptosis initiates gross bowel necrosis in an experimental rat model of neonatal necrotizing enterocolitis

The histopathology of necrotizing enterocolitis (NEC) is characterized by destruction of the mucosal layer in initial stages and by transmural necrosis of the intestinal wall in advanced stages of the disease. To test the hypothesis that enhanced epithelial apoptosis is an initial event underlying the gross histologic changes, we analyzed epithelial apoptosis and tissue morphology in an animal model of NEC and evaluated the effect of caspase inhibition on the incidence of experimental NEC in this model. Apoptosis was analyzed with terminal deoxynucleotidyltransferase-mediated dUTP-FITC nick end labeling (TUNEL) staining in intestinal sections and by measuring caspase 3 activity from intestinal lysates of neonatal rats subjected to formula feeding and cold/asphyxia stress (FFCAS) and from mother-fed (MF) controls. Morphologic evaluation was based on hematoxylin and eosin staining of intestinal sections. FFCAS resulted in histologic changes consistent with NEC, which were absent from MF animals. FFCAS was also associated with a significantly increased rate of nuclear DNA fragmentation in the small intestinal epithelium compared with MF. Elevated tissue caspase 3 activity confirmed the presence of apoptosis in samples with increased DNA fragmentation. Analysis of the coincidence of morphologic damage and apoptosis in corresponding tissue sections indicated that apoptosis precedes gross morphologic changes in this model. Furthermore, supplementation of formula with 8 boc-aspartyl(OMe)-fluoromethylketone, a pan-caspase inhibitor, significantly reduced the incidences of apoptosis and experimental NEC. These findings indicate that in neonatal rats FFCAS induces epithelial apoptosis that serves as an underlying cause for subsequent gross tissue necrosis.     

新生儿坏死性小肠结肠炎研究进展与展望

坏死性小肠结肠炎(NEC)的早期识别和严重程度判断较为困难,临床常使用Bell分期作为其诊断及分期标准。随着分子医学和新生儿医学水平的提高,NEC的预防、治疗和管理策略都有了新的进展,但其发病率和病死率仍居高不下。近年来,组学与临床数据结合寻找早期预测NEC的相关生物标志物、母乳喂养及维持肠道菌群稳态对NEC的预防、干细胞和外泌体相关治疗的探索,都为NEC诊治带来了新方向,有望降低NEC发生率和病死率,改善患儿远期预后。