中文摘要：

目的探究以MyD88为关键传导分子的TLR4下游炎症-凋亡信号通路在NEC发病过程中的作用机制。方法采用SPF级，新生10日龄MyD88^-／-幼鼠和相应的野生型幼鼠，共32只，分别按照数字表法随机分配进入NEC实验组或对照组；NEC实验组幼鼠置入自制新生保育箱内造模处理（每日人工配置鼠乳代用品喂养，5次／d；每次给予N2缺氧90S后，快速充入O2复氧，再次置入4℃环境冷刺激10min，3次／d，连续3d；LPS10mg／kg稀释于0．1ml灭菌水中，去芯留置针头口腔插管灌胃，1次／d，连续3d）；对照组继续与母鼠同笼，鼠乳喂养。实验结束后取材回肠末端肠管组织，HE染色法组织病理评分及液相芯片细胞因子TNF-α及IL-1β检测判断各组肠道NEC炎症程度。TUNEL方法检测各组小鼠肠道细胞的凋亡水平变化。实时荧光定量逆转录聚合酶链反应（reverse transcription-polymerase chain reaction，RT-PCR）检测各组小肠组织内TLR4炎症-凋亡通路中TRIF、IRF-3、NF-κb、Bax、Bcl-2、Caspases的mRNA表达情况。结果与野生鼠NEC组相比，MyD88敲除鼠小肠炎症程度评分（1．63±0．52比2．75±0．46）、炎症效应分子NF_小表达（1．38±0．25比2．33±0．76）、促炎因子IL-1β（465．57±81．59比863．58±198．28）、TNF-α（5．41±0．83比6．48±1．15）水平明显降低；肠上皮细胞凋亡明显减少（4．44±0．47比9．75±1．00），凋亡效应分子Caspases 8（2．03±0．20比4．06±0．44）、Caspases 9（1．02±0．08比1．93±0．09）、Caspases 3（1．87±0．28比6．75±1．12）和促凋亡基因Bax（1．15±0．25比2．40±0．42）表达降低（P〈0．05）。MyD88非依赖通路中关键因子TRIF（1．85±0．38比1．4±0．19）和IRF-3（2．01±0．41比1．53±0．38）表达上调（P〈0．05）；抗凋亡基因Bcl-2（1．18±0．31比1．10±0．20）表达无变化（P〉0．05）。结论①TLR4下游的MyD88-NF-κb信号通路是NE

英文摘要：

Objective To explore the effects of myeloid differentiation protein 88 （MyD88） in TLR4 downstream inflammation-apoptosis signaling on inflammatory severity in the development of necrotizing enterocolitis （NEC）. Methods Thirty-two SPF （specific pathogen-free） newborn （10-day- old）, 16 MyD88-deficient （MyD88-/-） and 16 MyD88 wild-type （MyD88-WT） （C57BL/6j） mice were selected and randomly divided into control and NEC groups. Each group was further divided into two equal subgroups of MyD88-Ko and MyD88-WT. NEC was induced in a self-made incubator （formula feeding, 5 times/day; hypoxia for 90 sec, rapid reoxygenation, 4 ℃ for 10 min, thrice daily;lipopolysaccharide 10 mg/kg into 0. 1 ml water, tubular indwelling needle in stomach, once daily, 3 consecutive days）. The control newborn mice remained breast-fed. The NEC severity of terminal ileum tissue was evaluated by histopathologic grading system with hematoxylin ＆ eosin staining and the levels of tumor necrosis factor-alpha （TNF-α） and interleukin-1β （IL-1β） were detected with liquid chip. Enterocytic apoptosis was evaluated by terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling （TUNEL）. Inflammatory or apoptotic molecules including NF-eB, TRIF, IRF-3, Bax, Bcl-2 and caspases were examined by quantitative reverse transcription-polymerase chain reaction （qRT-PCR）. Results Compared with wide-type NEC group, NEC severity （1.63±0. 52 vs 2. 75±0. 46） and the levels of IL-1β （465.57 ± 81.59 vs 863.58 ±198. 28） and TNF-α （5.41 ± 0. 83 vs 6. 48 ± 1.15） all decreased in MyD88-Ko group. The apoptotic rate of intestinal enteroeytes （4. 44 ±0. 47 vs 9. 75 ± 1.00） declined （P〈0. 05）. And the expressions of NF-κb （1.38±0. 25 vs 2. 33 ± 0. 76）, easpase 8 （2. 03±0. 20 vs 4. 06 ±0. 44）, caspase 9 （1.02 ± 0. 08 vs 1.93± 0. 09）, caspase 3 （1.87 ±0. 28 vs 6. 75 ± 1.12） and Bax （1.15 ± 0. 25 vs 2. 40 ± 0. 42） were all down-regulated （P〈0. 05） while