肠三叶因子对内毒素血症幼鼠肠组织Toll样受体2和4表达的影响

目的：探讨肠三叶因子对内毒素血症幼鼠肠组织Toll样受体（TLR）2、4表达的调节及对肠组织损伤的影响。方法：24只10日龄Wistar幼鼠随机分为正常对照组（NS组,n=8,生理盐水1 mL/kg腹腔注射）;内毒素血症组（LPS组,n=8,LPS 5 mg/kg 腹腔注射）;肠三叶因子组（ITF组,n=8,重组肠三叶因子 0.1 mL/只＋LPS 5 mg/kg腹腔注射）。于腹腔注射后3 h处死,留取远端回肠组织观察肠组织病理改变,RT-PCR检测肠组织TLR2、4-mRNA的表达。结果：光镜下NS组肠组织结构正常,ITF组和LPS组均可见间质和上皮细胞水肿,ITF组较LPS组病变明显减轻。ITF组肠组织TLR2 mRNA 表达较NS组、LPS组明显增高（P＜0.01）; 而TLR4 mRNA表达较NS组和LPS组明显下降（P＜0.01）。结论：肠三叶因子可减轻内毒素血症幼鼠肠组织损伤,这种保护作用可能与其下调TLR4 mRNA的表达相关。     

Lipopolysaccharide induces IL-6 production in respiratory syncytial virus-infected airway epithelial cells through the toll-like receptor 4 signaling pathway

Respiratory syncytial virus (RSV) is a leading cause of bronchiolitis in young children. Microbial agents such as endotoxin and RSV are implicated in airway inflammation during the development of reactive airway disease (RAD) later in childhood. Toll-like receptors (TLRs) are involved in an inflammation cascade through pathogen-associated molecular pattern recognition including lipopolysaccharide (LPS) and viral components. In this study, we investigated the expression of TLRs and cytokine-chemokine production profiles of RSV-infected epithelial cells. In live-RSV infected human tracheal epithelial cell line (9HTEo), TLRs 1-10 mRNA levels were up-regulated in a time-dependent manner compared with ultraviolet (UV)-inactivated RSV. RSV was shown to alter TLR4 membrane and cytosolic location in epithelial cells. Stimulating RSV-infected epithelial cells with TLR4 agonist LPS increased synthesis of IL-6, IL-8, and reduced regulated on activation, normal T cell expressed and secreted (RANTES) production. TLR4 neutralizing antibody HTA125 and TLR4-targeting RNA interference experiments revealed that TLR4 signaling pathway played a predominant role in mediating LPS-induced-IL-6 production of RSV infected epithelial cells. Altogether, our studies indicated that TLR4 play a critical role in leading LPS mediated-IL-6 response in RSV infected-epithelial cells and might be an important factor influencing the cytokine-chemokine profile of epithelial cells interacting with virus and endotoxin, which is correlated with phenotypes of RSV diseases.     

Toll-like receptors and agonist responses in the developing fetal sheep lung

Toll-like receptors (TLRs) are pattern recognition molecules that initiate innate immune responses. Intra-amniotic exposure of fetal sheep to pro-inflammatory stimuli causes pulmonary inflammation and induced lung maturation. We examined TLR ontogeny and fetal lung responsiveness to three different TLR agonists. We cloned ovine TLRs 2, 3, and 4 and found 83-88% homology between these ovine and human TLRs. Lung TLR2 and 4 mRNAs increased throughout late gestation to 50% of adult level in the term newborn lamb. Doses of 10 mg of PAMCysK4 (TLR2 agonist), poly I:C dsRNA (TLR3 agonist), or E. coli O55:B5 lipopoysaccharide (LPS) (TLR4 agonist) were given by intra-amniotic injection 2 d or 7 d before operative delivery of preterm lambs at 123 d (n = 4-7/group). The TLR4 agonist induced lung inflammation and maturation, whereas the TLR2 agonist gave less consistent responses. Intra-amniotic LPS increased TLR2 mRNA expression primarily in the inflammatory cells and TLR4 mRNA diffusely in multiple cell types. The TLR3 agonist had no effects, and TLR3 mRNA in the fetal lung did not change after LPS exposure. We conclude that TLR2 and TLR4 mRNAs increase through gestation and expression of TLR2 and TLR4 are induced by LPS in the fetal sheep lung.     

Toll样受体2对肠上皮细胞屏障通透性的保护作用及机制

目的 肠上皮细胞屏障的损伤与多种胃肠道疾病的发生密切相关,有效维持屏障功能是治疗这些疾病的关键.本研究试图通过体外实验探讨Toll样受体2(toll-like receptor,TLR2)对肠上皮细胞屏障通透性的保护作用及其机制.方法 正常组将未转染Caco-2细胞,TLR2基因沉默Caco-2细胞,TLR2基因过表达Caco-2细胞培养21d形成单层,检测跨膜电阻(transepithelial electrical resistance,TEER)值,其反应上皮细胞屏障的通透性.炎症组3类细胞分别于培养第19d给予10 ng/ml IL-1β刺激48 h,于第21d检测TEER值.抑制剂组3类细胞分别在IL-1β前再给予PI3K/Akt通路抑制剂处理1h,于第21 d检测TEER值.结果 TLR2基因沉默能够显著减低Caco-2细胞单层的TEER值(P＜0.01),而TLR2基因过表达能够升高TEER值,但不具有统计学意义.TLR2能够防止IL-1β造成的TEER值下降(P＜0.01),此作用在给予PI3K/Akt通路抑制剂后消失.结论 TLR2对肠上皮细胞屏障通透性具有调节作用,并且能够防止炎症造成的通透性增高,这种保护作用由PI3K/Akt通路参与介导.     

高迁移率族蛋白1在新生儿败血症中的表达与机制

目的 探讨高迁移率族蛋白1（HMGB1）在新生儿败血症中的表达与机制。方法 选取62例新生儿败血症患儿为败血症组,66例局部感染新生儿为局部感染组,70例健康新生儿为健康对照组。检测三组新生儿血清中IL-6、IL-8、IL-17、IL-23、C反应蛋白（CRP）和降钙素原（PCT）的含量,外周血单个核细胞中HMGB1、Toll样受体4（TLR4）、核转录因子κB（NF-κB）mRNA及TLR4、NF-κB蛋白的表达。将健康新生儿的外周血单个核细胞分为对照组、HMGB1处理组、HMGB1+TAK-242（TLR4抑制剂）组、HMGB1+PDTC（NF-κB抑制剂）组,检测各组TLR4、NF-κB、IL-8 mRNA及TLR4、NF-κB蛋白的表达。将健康新生儿的外周血单个核细胞分为对照组、LPS处理组、LPS+甘草甜素（HMGB1抑制剂）组,检测HMGB1、TLR4、NF-κB、IL-8 mRNA及TLR4、NF-κB蛋白的表达。结果 败血症组患儿血清中IL-6、IL-8、IL-17、IL-23、CRP、PCT含量均显著高于局部感染组和健康对照组（P < 0.05）。败血症组患儿外周血单个核细胞中HMGB1、TLR4、NF-κBmRNA及TLR4、NF-κB蛋白的相对表达量均显著高于局部感染组和健康对照组（P < 0.05）。HMGB1可以显著诱导外周血单个核细胞高表达TLR4、NF-κB mRNA及其蛋白（P < 0.05）;使用TAK-242可抑制TLR4、NF-κBmRNA及其蛋白的高表达,并进而抑制IL-8 mRNA的表达（P < 0.05）;使用PDTC可抑制NF-κB mRNA及其蛋白的高表达,并进而抑制IL-8 mRNA的表达（P < 0.05）。LPS可显著诱导HMGB1 mRNA,以及TLR4、NF-κBmRNA及其蛋白的高表达,进而刺激IL-8 mRNA的表达（P < 0.05）;使用甘草甜素可抑制HMGB1 mRNA的高表达,抑制TLR4、NF-κB mRNA及其蛋白的高表达,进而降低IL-8 mRNA的高表达（P < 0.05）。结论 HMGB1可能通过激活TLR4/NF-κB信号通路诱导IL-8等炎症因子的高分泌在新生儿败血症的发病中起重要作用,HMGB1阻断剂甘草甜素可抑制TLR4/NF-κB信号通路的活化及炎症因子的分泌。     

IL-1β对肠上皮细胞屏障通透性的影响

目的 炎症性肠病是儿童和青少年时期重要的慢性胃肠道疾病,肠黏膜屏障的损伤在其发病中起重要作用.本研究通过IL-β刺激Caco-2细胞单层,体外模拟炎症性肠上皮细胞屏障,为研究炎症性肠病的发病及治疗提供基础.方法 体外培养Caco-2细胞21d模拟肠上皮细胞单层屏障.炎症1组从培养第5天开始每隔1天应用IL-1β处理2h检测TEER值,至第21天.炎症2组于培养第18天换用含IL-1β培养液,分别于处理0、12、24、48、72 h检测TEER.正常对照组用普通培养液培养,也于相应时间点检测TEER.结果 正常对照组细胞TEER从第5天至第15天逐渐增加,在第15天达到600 Ω·cm2,并到达平台期保持至第21 d.炎症1组细胞TEER值均低于正常组细胞,并且直至第21天仍＜500 Ω·cm2.炎症2组细胞显示时间依赖性的TEER逐渐降低,在48 h达到最大值,然后在72 h轻度回升.结论 培养2～3周的Caco-2细胞能够形成具有极性的肠上皮细胞单层,对其给予IL-1β刺激可在体外模拟炎症性肠上皮细胞屏障.     

二十碳五烯酸对E.coli LF82感染后肠上皮细胞紧密连接蛋白ZO-1 mRNA的影响

目的探讨二十碳五烯酸(EPA)对黏附侵袭性大肠杆菌(AIEC)LF82感染后肠上皮细胞(Caco-2)紧密连接蛋白(ZO-1)表达的影响。方法用Caco-2细胞株建立体外肠上皮细胞紧密连接模型,分为EPA处理组,EPA 0、25、50、100、200μmol/L干预96 h;以及EPA(EPA 0、25、50、100、200μmol/L)+E.coli LF82联合处理组,在不同浓度EPA干预96 h的基础上,予E.coli LF82分别干预0 h、6 h、12 h。通过细胞形态学观察,MTT法测定细胞生长曲线,以及细胞膜两侧碱性磷酸酶(ALP)活性检测对Caco-2细胞模型进行评价。流式细胞术检测不同浓度EPA对Caco-2细胞凋亡的影响。RT-q PCR检测EPA和/或E.coli LF82作用于Caco-2细胞后ZO-1 m RNA的表达情况。酶联免疫吸附法检测Caco-2细胞上清中TNF-α的变化。结果 EPA25、50μmol/L处理后,Caco-2细胞存活率均高于0浓度组,且增高呈浓度依赖性(P0.05);EPA100、200μmol/L处理组的细胞存活率下降呈浓度依赖性,均低于0浓度组(P0.05)。EPA浓度为100、200μmol/L时,细胞凋亡率较0浓度组增加(P0.05)。单独E.coli LF82干预Caco-2细胞6 h、12 h后,ZO-1 m RNA表达随处理时间延长而减少,均低于未处理组(P0.05)。EPA 25、50μmol/L干预联合E.coli LF82处理6 h或12 h,Caco-2细胞的ZO-1 m RNA表达随EPA浓度增加而增加,均高于E.coli LF82单独处理组(P0.05)。单独E.coli LF82处理6 h、12 h组的TNF-α分泌随干预时间延长而增加,均高于未处理组(P0.05)。EPA25、50μmol/L联合LF82处理6 h或12 h,细胞上清液中TNF-α分泌量随EPA浓度的增加而减少,均少于单独LF82处理组(P0.05)。结论 EPA能有效预防E.coli LF82感染后肠上皮细胞紧密连接的破坏,抑制炎症因子的分泌,对肠黏膜屏障有一定的保护作用。     

血管活性肠肽对肺损伤大鼠Toll样受体mRNA表达的影响

目的 探讨血管活性肠肽(vasoactive intestinal peptide,VIP)对内毒素(脂多糖,lipopolysaceberide,LPS)致休克大鼠肺损伤后Toll样受体(Toll-like receptor,TLR)2和TLR4 mRNA表达的影响.方法 40只SD大鼠,随机分为LPS组(16只)、LPS+VIP组(16只)和对照组(8只).LPS组尾静脉注射LPS(E.coli O_(55)B_5)10 mg/kg;LPS+VIP组尾静脉注射LPS 10 ms/kg后注射VIP 5 nmol/kg;对照组尾静脉注射等容量生理盐水.分别于注射后6 h和24 h处死,留取肺标本,RT-PCR检测肺TLR2/4 mRNA表达,并观察24 h时肺组织病理变化.结果 (1)肺组织病理改变:制模24 h时.光镜和透射电镜下,LPS组见肺泡间隔弥漫性增宽、炎性细胞浸润,隔内毛细血管不同程度充血,肺泡壁增厚,肺泡腔结构破坏、炎性细胞浸润、出血、间质水肿、细胞器破坏,LPS+VIP组病变较轻.(2)TLR2/4 mRNA表达:注射LPS后6 h、24 h,肺组织TLR2/4 mRNA表达升高(F=16.638,P=0.000;t=5.876,P=0.000);24 h时LPs+VIP组TLR2/4 mRNA表达低于LPS组(F=16.676,P=0.000;t=3.9,16,P<0.001).结论 LPS致休克大鼠肺损伤时,肺组织TLR2/4 mRNA表达增强.VIP可减轻LPS所致肺损伤,其机制可能与下调重要炎症基因TLR2/4 mRNA表达有关.     

自噬在脂多糖诱导的A549细胞炎症反应中的作用及机制研究

目的 探讨自噬在脂多糖(lipopolysaccharide,LPS)诱导的人肺泡上皮A549细胞炎症反应中的作用及机制。方法 用LPS刺激A549细胞建立炎症反应模型,按浓度(0、1、5、10μg/mL)和时间(0、4、8、12、24h)分组(各组n=3)。用自噬抑制剂3-甲基腺嘌呤(3-methyladenine,3-MA)处理细胞,分为对照组、LPS组、3-MA组、3-MA+LPS组(各组n=3);用自噬激动剂雷帕霉素(rapamycin,RAPA)处理细胞,分为对照组、LPS组、RAPA组、RAPA+LPS组(各组n=3)。通过Toll样受体4 (Toll-like receptor 4,TLR4)过表达质粒和siRNA转染A549细胞,实验分为两部分,每部分各分4组(各组n=3):TLR4过表达对照组、TLR4过表达组、TLR4过表达对照+LPS组、TLR4过表达+LPS组;TLR4沉默对照组、TLR4沉默组、TLR4沉默对照+LPS组、TLR4沉默+LPS组。采用CCK-8法检测细胞存活率,免疫印迹法检测炎症指标(NLRP3、Caspase-1、ASC)、自噬指标(LC3B...     

Probiotics up-regulate MUC-2 mucin gene expression in a Caco-2 cell-culture model

Enteral probiotics such as Lactobacillus casei GG (LGG) have been used in the treatment of a variety of intestinal disorders in infants and children, including diarrhea, malabsorption, and Clostridium difficile colitis. Previous studies have identified the gene locus for mucin (MUC-2) and its expression in Caco-2 cells. Others have demonstrated that mucin, located on the surface of the intestinal epithelium, inhibits bacterial translocation (BT). We previously demonstrated that both mucin and the probiotic bacterium LGG have an inhibitory effect on BT in both an in-vitro Caco-2 cell model and a neonatal rabbit model. We hypothesized that the decline in BT by LGG is mediated by up-regulation of epithelial MUC-2. Human enterocyte Caco-2 cells were grown to confluence and incubated at 37 degrees C with either medium (control group) or 10(4) or 10(8) LGG for 180 min. Non-adherent LGG was washed away. Caco-2 cells were then lysed, purified, and quantified for MUC-2 protein and mRNA. The addition of LGG to the enterocyte monolayer surface resulted in significantly ( P < 0.05) increased MUC-2 expression compared to the untreated monolayers. Protein densities for MUC-2 significantly ( P < 0.05) increased with LGG. Density (expressed as ratio to control group) was 8.6 +/- 1.3 in the low-dose group (10(4) LGG) and 15.6 +/- 2.3 in the high-dose group (10(8) LGG). LGG may thus bind to specific receptor sites on the enterocyte and stimulate the up-regulation of MUC-2, resulting in increased inhibition of BT.     

Dextran sulfate sodium-induced inflammation is enhanced by intestinal epithelial cell chemokine expression in mice

Dextran sulfate sodium (DSS) induces an inflammatory bowel disease-like colitis in animals. To determine the contribution of epithelium to inflammation in the intestine, we examined the effects of DSS in transgenic mice that specifically secrete macrophage inflammatory protein-2 (MIP-2) from the intestinal epithelium. We first confirmed the production of MIP-2 from intestinal epithelial cells by Western blots in transgenic mice. MIP-2 transgenic mice were therefore an appropriate model to examine the role of epithelial cell chemokines in an inflammatory state induced by DSS. We then examined the neutrophil migration into the intestine and the effect of DSS on this migration by myeloperoxidase staining. There was an increase of myeloperoxidase-positive neutrophils in the intestine from wild-type and transgenic mice after the DSS treatment. Furthermore, the increase of neutrophils under stimulation with DSS was confirmed quantitatively by measuring specific tissue myeloperoxidase activities. It was significantly greater in DSS-treated MIP-2 transgenic mice than in wild-type mice in both the small intestine and colon. These results suggest that the inflammatory effects of DSS on both small intestine and colon are enhanced by MIP-2 secreted by epithelial cells in the transgenic mice. In conclusion, intestinal epithelial cells can act in concert with other inflammatory stimuli in maintaining inflammation.     

Caco-2建立肠黏膜屏障模型及其在通透性研究中的应用

目的：利用 Caco-2细胞建立体外肠黏膜屏障模型,系统评价并初步探讨其在炎症损伤后黏膜通透性改变中的应用。方法体外培养 Caco-2细胞,接种于 Transwell 板上,每日观察细胞形态;自培养第5天起,隔日测细胞膜的跨上皮电阻(transepithelial electrical resistance,TEER);对于 TEER 值达标准的孔测定荧光黄透过率,进行透射电镜的完整性验证。应用培养21 d 的 Caco-2细胞屏障,加入不同浓度(0、50、100、200 nmol /L)的血小板活化因子(platelet-activating factor,PAF)孵育24 h,光镜、电镜观察形态学改变,检测 TEER 和荧光黄透过率,应用间接免疫荧光和 Western blot 观察 ZO-1蛋白的分布及表达。结果Caco-2细胞单层 TEER 从第5～15天逐渐增加,在第15天已经达到600Ω?cm2,平台期保持至第21天;在此期间,细胞形成紧密单层,电镜下细胞呈高分化,细胞间形成紧密连接,绒毛整齐,极性形成;荧光黄透过量极低,体外肠上皮细胞屏障形成。加入 PAF 后,以100 nmol /L 对黏膜屏障通透性影响最大：电镜下见紧密连接结构破坏、断裂,细胞表面微绒毛脱落、稀疏;免疫荧光可见紧密连接的标志蛋白 ZO-1荧光信号减弱,ZO-1环断裂,胞浆内可见阳性染色,提示其向膜下转移。此时,TEER 值下降,荧光黄透过量明显增加,与对照组比较差异有统计学意义(P ＜0.01),与形态学改变规律一致;ZO-1蛋白表达亦降至最低,与对照组相比差异有统计学意义(P ＜0.01)。结论经形态学及细胞通透性验证,培养2～3周的 Caco-2细胞可形成肠屏障模型,用于体外肠黏膜屏障的研究;PAF 影响紧密连接相关蛋白的表达,破坏紧密连接结构,从而影响肠黏膜屏障通透性。     

The role of intestinal bifidobacteria on immune system development in young rats

Aim

The effects of intestinal bifidobacteria on the development of immunity in early life were explored.

Methods

Neonatal SD rats born and housed under strict barrier systems were fed from birth with sufficient antibiotics (bifidobacteria minimisation group) or supplemented daily with 1 × 10¹⁰ colony-forming units of live Bifidobacterium longum (bifidobacteria supplementation group). Relevant indices of immune development were determined at one, three and six weeks old.

Results

Compared to the control group, minimisation of the intestinal bifidobacteria delayed maturation of dendritic cells in Peyer's Patches and the development of T cells in the thymus, increased IL-4 secretion in the plasma, down-regulated IL-12, IL-10 mRNA and the interferon-γ/IL-4 mRNA ratio in intestinal mucosa, decreased interferon-γ mRNA in cultured peripheral blood mononuclear cells (PBMCs), and reduced immunoglobulin-M production in cultured PBMCs. Conversely, supplementation with bifidobacteria promoted dendritic cell maturation in Peyer's Patches, up-regulated IL-12, IL-10, interferon-γ mRNA and the interferon-γ/IL-4 ratio in intestinal mucosa, increased interferon-γ gene expression in cultured PBMCs, and raised immunoglobulin-M secretion in cultured PBMCs.

Conclusions

Intestinal bifidobacteria could promote the maturation of dendritic cells and its expression of IL-12 locally in the gut, influence the development of T cells in the thymus, favour the development of T-helper cell type 1 response by increasing the local and systemic expression of interferon-γ and ensure the intestinal regulatory T cell response by promoting the local expression of IL-10. In addition, they enhance antibody synthesis by PBMCs, thereby affecting the development of both the gut and systemic immunity in early life.     

Peroxisome proliferator‐activated receptor γ 2 mutation may cause a subset of ulcerative colitis

Aim: Previous studies suggest the homeostasis between acquisition of tolerance to the indigenous microflora and protective immune responses appears to be disrupted in inflammatory bowel disease (IBD). Some experimental studies indicate peroxisome proliferator‐activated receptor γ (PPARγ) has been implicated as a regulator of intestinal inflammatory responses. In addition, the toll‐like receptor (TLR)‐4 can regulate expression of PPARγ in colonic epithelial cells. We attempted to demonstrate whether the functional imbalance between TLRs and PPARγ could lead to the onset and some polymorphisms of those genes could contribute to susceptibility to IBD. Methods: RT‐PCR analysis were performed to detect TLR4 and PPARγ mRNA associated with those of P65 of NFκB, TNFα, MyD88, NOD2/CARD15, TLR‐2,5,9, in the diseased colonic mucosa in ulcerative colitis (UC; n = 13) and Crohn's disease (CD; n = 7) compared with normal controls (n = 18). Consequently, we genotyped UC (n = 29) and CD (n = 10) compared with normal controls (n = 134) for the prevalence of suspicious mutations. Results: In a subset of UC patients who were revealed to carry PPARγ Pro12Ala mutation later, impaired expression of normal PPARγ mRNA was noted in the diseased mucosa accompanied with upregulations of MyD88 TLR‐4, 5, 9, P65 and TNFα in mRNA levels. The prevalence of PPARγ Pro12Ala mutation was more frequently found in UC patients compared with CD patients and normal controls (P < 0.05). Conclusions: These findings suggested that imbalances between TLRs and PPARγ in response to luminal bacteria could lead to colonic inflammation in some UC patients. Alternative explanations will be needed for the onset of the rest of UC and CD.     

Polyunsaturated fatty acid supplementation alters proinflammatory gene expression and reduces the incidence of necrotizing enterocolitis in a neonatal rat model

Although supplementation of preterm formula with polyunsaturated fatty acids (PUFA) has been shown to reduce the incidence of necrotizing enterocolitis (NEC) in animal models and clinical trials, the mechanisms remain elusive. We hypothesized that the protective effect of PUFA on NEC may be due to the ability of PUFA to suppress Toll-like receptor (TLR) 4 and platelet-activating factor receptor (PAFR) gene expression (molecules that are important in the pathogenesis of NEC) in epithelial cells. To investigate the efficacy of different PUFA preparations on NEC in a neonatal rat model, we compared the incidence of NEC among the four PUFA supplemented groups--A: arachidonic acid and docosahexaenoic acid (AA+DHA), B: egg phospholipids (EP), C: DHA, and D: control without PUFA. PUFA supplementation reduced the incidence of NEC and inhibited intestinal PAFR and TLR4 gene expression compared with the controls. To validate the in vivo observations, IEC-6 cells were exposed to PAF after pretreatment with AA or DHA. Both AA and DHA supplementation blocked PAF-induced TLR4 and PAFR mRNA expression in these enterocytes. These results suggest that PUFA modulates gene expression of key factors involved in experimental NEC pathogenesis. These effects might in part explain the protective effect of PUFA on neonatal NEC.     

Toll样受体阻断剂对内毒素血症小鼠肠黏膜损伤的影响

目的 探究Toll样受体（TLR）阻断剂对小鼠肠黏膜上皮细胞间紧密连接蛋白ZO-1的影响及对核转录因子-κB （NF-κB）和肿瘤坏死因子-α（TNF-α）的影响。方法 将32只BALB/C小鼠分为对照组、模型组、TLR4处理组、TLR2处理组（n=8）,腹腔注射LPS建立内毒素血症小鼠模型,TLR4处理组、TLR2处理组在腹腔注射LPS同时分别给予TLR4抗体和TLR2抗体（10 μg/只）腹腔注射,对照组以生理盐水替代。取各组小鼠远端小肠组织,采用RT-PCR及免疫组化法检测ZO-1、NF-κBp65及TNF-α的mRNA和蛋白定位表达。结果 模型组ZO-1 mRNA及蛋白表达明显低于对照组（P < 0.05）,NF-κBp65、TNF-α mRNA及蛋白表达明显高于对照组（P < 0.05）;TLR4处理组及TLR2处理组ZO-1 mRNA及蛋白表达明显高于模型组（P < 0.05）,NF-κBp65、TNF-α mRNA及蛋白表达明显低于模型组（P < 0.05）;TLR4处理组与TLR2处理组ZO-1、NF-κBp65、TNF-α mRNA及蛋白表达比较差异无统计学意义（P > 0.05）。结论 抗TLR2、TLR4单克隆抗体可减少核转录因子的激活,抑制炎症因子大量分泌,保护紧密连接蛋白,有望对治疗肠源性感染疾病提供新的思路。     

宫内注射脂多糖对围产期大鼠肺Toll样受体4信号转导通路的影响

目的 观察宫内注射脂多糖(LPS)对围产期大鼠肺内天然免疫相关的Toll样受体4(TLR4)信号转导通路的影响,探讨天然免疫在宫内感染中的免疫调节能力及对肺发育的影响.方法 将30只孕17d的SD大鼠随机分为LPS组和生理盐水对照组,LPS组宫内注射LPS 10μl(40μg/ml),对照组宫内注射等体积的灭菌生理盐水.分别留取胎龄18、20、22 d(E18、E20、E22)的胎鼠肺组织、胎盘组织标本以及生后1、3、7d(P1、P3、P7)新生鼠肺组织标本,HE染色观察病理改变,RT-PCR技术检测TLR4、髓样分化因子88(MyD88)和白介素1 β(IL-1β)mRNA表达,免疫组织化学技术检测肺组织TLR4、MyD88的表达分布情况.实验数据采用单因素方差分析和q检验进行统计学分析.结果 (1)LPS组孕鼠胎盘组织有大量中性粒细胞浸润,宫内感染模型建立成功;(2)在E18、E20和E22时,LPS组胎鼠肺组织无明显病理学改变,以后逐渐出现改变,于P7时可见肺泡数量减少,肺泡腔变大,间隔变薄,但未见明显结构紊乱;(3)LPS组TLR4、MyD88和IL-1β mRNA水平于E20和E22均高于对照组,差异有统计学意义(P<0.05),且均于E22表达达高峰,后缓慢下降;(4)免疫组织化学结果显示E18时两组肺组织内均未见明显TLR4和MyD88阳性染色,后均逐渐表达增加,且主要在细支气管和肺泡上皮细胞表达.结论 (1)宫内注射LPS可导致胎鼠和早产鼠肺组织TLR4、MyD88表达在一定范围内增加,后逐渐回复正常水平,同时肺组织的病理改变和炎症反应较为温和,推测在围产期胎肺天然免疫系统可以调节LPS诱导的炎症反应强度;(2)该实验在一定程度上证实宫内感染激活的信号转导通路是MyD88依赖性途径.