补充双歧杆菌可促进烫伤大鼠肠道sIgA合成与分泌

目的探讨严重烫伤后补充双歧杆菌与肠道sIgA合成、分泌的关系.方法Wistar大鼠70只随机分为烫伤对照组(BC,n=30)、烫伤治疗组(BT,n=30)、假伤组(NC,n=10).BT组伤后灌胃双歧杆菌悬液(5×109cfu/ml),1.5ml,2/d.检测大鼠细菌及内毒素移位、膜菌群中双歧杆菌量、肠粘液sIgA浓度及肠道浆细胞sIgA表达情况等.结果(1)伤后3d,BC组与BT组细菌移位率分别为42%和16%(P=0.004),伤后5d分别为30%和8%(P=0.002).(2)伤后大鼠盲肠膜菌群中双歧杆菌减少约10～60倍;灌胃双歧杆菌悬液后肠道双歧杆菌明显增多.(3)BC组肠粘液sIgA平均减少约30%,伤后3d达最低;BT组3d伤后基本恢复正常.伤后回肠粘膜下固有层浆细胞sIgA表达减弱,补充双歧杆菌后sIgA表达显著增强,5d接近NC组.(4)膜菌群中双歧杆菌量与肠粘液sIgA浓度呈显著正相关.结论严重烫伤后肠道sIgA产生明显受抑制,其改变与膜菌群中双歧杆菌减少有关,补充外源性双歧杆菌可促进肠道sIgA合成与分泌.     

益生菌与核黄素联用对烫伤大鼠肠道屏障的保护作用

目的　观察益生菌与核黄素联合应用对烫伤大鼠细菌移位的防治效果 ,探讨其可能的作用机制。　方法　将Wistar大鼠随机分为烫伤对照组 (SC组 ,30只 )、烫伤治疗组 (ST组 ,30只 )、正常对照组 (NC组 ,10只 )。SC、ST组大鼠作 30 %ⅢTBSA度烫伤 ,ST组大鼠伤后立即向胃中灌注含双歧杆菌 5× 10 12 个集落形成单位 /L、蜡样芽孢杆菌 5× 10 10 个集落形成单位 /L和核黄素 5 0 0mg/L的等渗盐水混悬液 1.5ml,2次 /d。SC、NC组于相同时间灌注等量等渗盐水。观察细菌移位、肠道膜菌群、回肠分泌型免疫球蛋白A(SIgA)合成分泌及肠黏膜损伤修复等变化。　 结果　与SC组比较 ,ST组大鼠各脏器细菌移位率显著下降 (P =0.0 0 0～ 0.0 2 5),血浆内毒素水平在伤后 3d内降低显著 (P <0 0 5 ),回盲部膜菌群中双歧杆菌量升高 2 0～ 4 0倍 ,大肠杆菌和真菌量显著降低 ( P <0.0 1),致伤后 5d内黏膜损伤评分为 0～ 3(P <0.0 5),小肠黏液SIgA含量伤后 5d可恢复正常 ( P <0 0 1)。结论　益生菌与核黄素联合应用 ,可减轻烫伤大鼠细菌 /内毒素移位程度 ,有效保护肠道屏障     

休克期切痂对烫伤大鼠全身和肠道局部免疫功能的影响

目的　观察休克期切痂对烫伤大鼠全身和肠道局部免疫功能的影响 ,探讨其可能的机制。　方法　选用 96只Wistar大鼠。取其中 2 4只大鼠的躯干部皮肤冻存于液氮中 ,另取 8只作正常对照组。余下 6 4只造成 30 %TBSAⅢ度烫伤后 ,随机分为A组 2 4只 ,伤后不作任何处理 ;B组 2 4只 ,伤后 2 4h腹腔注射等渗盐水 5 0ml/kg,一次性切痂后用上述冻存异体皮覆盖 ;C组 1 6只 ,伤后 72h进行处理 ,方法同B组。检测A、B组大鼠伤后 2、4、8d和C组伤后 4、8d及正常对照组大鼠的脾淋巴细胞增殖功能、血浆和肠组织白细胞介素 (IL)2水平、肠黏液分泌型免疫球蛋白A(sIgA)及肠组织中二胺氧化酶 (DAO)含量的变化。　结果　各时相点下A、B、C组大鼠脾淋巴细胞增殖功能、血浆IL 2水平、肠组织IL 2及肠黏液sIgA含量均较正常对照组减少。B组伤后 4、8d和C组伤后 8d的脾淋巴细胞增殖功能接近正常对照组 ,血浆和肠组织IL 2水平明显高于A组 (P <0.0 1)。伤后 4、8d,B组肠黏液sIgA含量分别为 (3.5 1± 2 .1 4 )、(3.0 3± 0 .95 )mg/g,C组分别为 (1 .4 0± 0 .6 4 )、(1 .5 2± 1 .2 6 )mg/g,B组较C组增加近 1倍 (P 0.0 1 )。A组伤后 4、8d肠组织DAO活性低于正常对照组和B组 (P 0.0 5)。结论　休克期切痂有助于烫伤大鼠全身和肠道     

肠道双歧杆菌与烫伤大鼠肠源性细菌/内毒素移位

目的　观察肠道双歧杆菌在肠源性细菌 /内毒素移位中的变化和作用。　方法　制作严重烫伤大鼠模型 ,同时设假伤组。检测细菌和内毒素 (LPS)移位及盲肠膜菌群变化 ,ELISA法检测血浆白细胞介素 6(IL 6)浓度。　结果　大鼠严重烫伤后脏器细菌移位明显增多 (P <0 .0 1) ;血LPS水平在致伤 1、3、5d后分别为 (0 .2 3 6± 0 148)Eu/ml、(0 .197± 0 .15 6)Eu/ml、(0 10 4± 0 .0 90 )Eu/ml,显著高于假伤组的 (0 .0 72± 0 .0 49)Eu/ml(P <0 .0 5 ) ;盲肠膜菌群中双歧杆菌数剧减 2 0～2 5 0倍、真菌数剧增至 5～ 60倍、大肠杆菌数增加 0 .5～ 3 0倍 ,双歧杆菌与大肠杆菌比值由假伤组的2 5 0 0 0∶1降为伤后的 4～ 80 0∶1;血浆IL 6水平显著增高。经分层统计 ,与未发生肠道细菌移位大鼠相比 ,盲肠膜菌群移位大鼠的双歧杆菌量减少约 12 0倍 ,真菌数增加约 5 0倍 ,大肠杆菌数增加约 3 0倍。盲肠膜菌群中双歧杆菌数量与血浆中IL 6、LPS浓度呈负相关 (r1=- 0 .4817,r2 =- 0 .4912 ,P <0 .0 1) ,血IL 6和LPS浓度间存在显著正相关 (r =0 .82 5 8,P =0 .0 0 0 1)。　结论　严重烫伤可导致大鼠盲肠膜菌群紊乱 ,细菌和LPS移位增加 ;盲肠膜菌群中双歧杆菌的比例和数量的减少 ,可能促使了严重烫伤后肠源性细菌 /内毒素移位     

严重烧伤后大鼠肠道生物屏障损害的初步研究

目的　观察严重烧伤大鼠肠道生物屏障的动态变化。　方法　以 30 %TBSAⅢ度烫伤大鼠为模型并设对照组。于伤后 2 4、4 8、72、96h分别采用微生物分析、生化、放射免疫等方法观察盲肠膜菌群、肠内容物粘蛋白、分泌型免疫球蛋白A(SIgA)、内毒素、肠道细菌移位率及定量分析腔静脉内毒素含量等。　结果　严重烧伤后早期 ,大鼠肠道生物屏障发生明显变化 :肠道膜菌群总量减少 ,其中以双歧杆菌为主的厌氧菌群显著减少 ,需氧菌群略有增加 ,酵母样真菌迅速过度生长 ,需、厌氧菌比例严重失调 ;肠道生物屏障被破坏 ,定植抗力减小 ;肠道细菌移位率明显增加 ,肠内容物、腔静脉内毒素含量增高 ,粘蛋白、SIgA含量降低。　结论　严重烧伤可致大鼠肠道生物屏障受损 ,成为烧伤后肠源性感染发生的原因之一。     

四君子汤药膳对严重烫伤大鼠免疫功能紊乱的调理作用

目的 了解四君子汤药膳对严重烫伤大鼠免疫功能紊乱的调理作用.方法 将90只健康Wistar大鼠造成30%TBSAⅢ度烫伤后,按照完全随机法分为药膳喂养组30只、肉汤喂养组30只、常规喂养组30只;另设对照组10只(模拟烫伤).药膳喂养组大鼠烫伤后按常规复苏及处理创面,分笼饲养,并于伤后2 h开始向胃内灌注37℃的四君子汤药膳,2 ml/次、2次/d;肉汤喂养组除灌注肉汤外,其余处理同前;常规喂养组伤后常规处理,自由进食、饮水.前3组大鼠于伤后3、7、14 d检测T淋巴细胞亚群和天然杀伤(NK)细胞的活性,血浆IgA、IgG、IgM、C 3、C 4水平,肠道分泌型IgA(sIgA)水平;对照组亦行相应检测.结果 前3组大鼠伤后大部分时相点各项指标(除CD8+T淋巴细胞活性外)均低于对照组(P＜0.05或P＜0.01).伤后3～14 d,药膳喂养组sIgA水平为(50±8)～(57±11)μg/ml,明显高于其他2个致伤组水平(P＜0.05或P＜0.01);其余免疫指标组间比较结果与此相似.结论 四君子汤药膳可以改善严重烫伤大鼠T淋巴细胞亚群的分布,提高NK细胞活性,促进血浆IgA、IgM、IgG、C 3、C 4水平的恢复和肠黏膜细胞slgA的分泌,从而改善机体免疫功能.     

中药清胰汤及双歧杆菌合剂对急性坏死性胰腺炎肠道细菌移位影响的比较研究

目的 观察中药清胰汤(CM)及双歧杆菌合剂(BM)对犬急性坏死性胰腺炎(ANP)肠道细菌移位(BT)的影响。方法 杂种犬31只,分对照组(n=7)、ANP组(n=8)、中药治疗组(CM,n=8)和双歧杆菌合剂治疗组(BM,n=8)。结照组犬仅行剖腹术;经主胰管注入5％牛磺胆酸钠(0.5ml/kg)和胰蛋白酶(3000U/kg)复制ANP模型,CM组和BM组犬术后每天分别经胃管灌服中药清胰汤及双歧杆菌合剂。结果 与ANP组比较,CM及BM组肠粘膜损害明显减轻;肠粘膜菌群中大肠杆菌、类杆菌数量减少,双歧杆菌、乳杆菌数量显著增加(P<0.05),肠道微生态趋于平衡;CM组脏器细菌移位率减少SO％,BM组减少37.5％,两组移位细菌数量减少10～40倍:两组血培养阳性率均由100％降为37.5％;两组血中内毒素水平下降1～2倍,淀粉酶水平下降2～3倍,磷脂酶A_2活性亦显著下降,并均于第7天后接近正常;肠通透性下降。结论 中药清胰汤及双歧杆菌合剂具有减轻ANP后肠粘膜损害,调节肠道菌群微生态平衡、保护肠屏障功能,从而减少BT致肠源性感染的作用     

大肠癌术后肠道菌群变化的临床研究

目的探讨大肠癌手术后肠道菌群的变化。方法对 30例大肠癌患者于手术前后留取粪便作肠道菌群分析 ,检测血中细菌DNA ,血细菌培养 ,观察术后感染并发症。结果术后大肠杆菌和肠球菌计数均明显增加 (P <0 0 5 ) ,双歧杆菌和乳杆菌计数则明显减少 (P <0 0 5 ) ,双歧杆菌 /大肠杆菌比值较术前倒置更为显著 (0 0 2 8± 0 0 7vs.0 75± 0 4 6 ,P <0 0 1 ) ,术前血中细菌DNA和细菌培养均为阴性 ,术后阳性率则分别为 4 3% (3/30 )、7% (2 /30 ) ,术后感染并发症发生率为 30 % (9/30 )。结论大肠癌手术可引起肠道菌群失调 ,损害肠屏障功能 ,导致细菌移位 ,增加术后感染并发症 ,围手术期应重视肠道菌群的微生态调理     

早期肠内免疫营养对烫伤大鼠免疫功能的影响

目的了解早期肠内免疫营养对烫伤大鼠全身及肠道免疫功能的影响。方法将健康SD大鼠分为标准营养组（EN组）和免疫营养组（EIN组），每组32只。将两组大鼠制成烧伤总面积30％TBSA的Ⅲ度烫伤模型，于伤后1、4、7、10d检测其外周血T淋巴细胞亚群、肠黏膜增殖细胞核抗原（PCNA）表达水平、浆细胞数量及肠黏液分泌型免疫球蛋白A（S-IgA）含量的变化。另取8只健康大鼠检测上述指标作为正常参考值。结果（1）与正常值比较，伤后EN组CD3^＋、CD4^＋、CD4^＋／CD8^＋降低但CD8^＋升高，与各项指标大部分时相点比较，差异有统计学意义（P〈0．05或P〈0．01）。伤后10d与EN组（CD4^＋／CD8^＋为1．26±0．10）比较，EIN组CD3^＋、CD4^＋、CD4^＋／CD8^＋（CD4^＋／CD8^＋为1．86±0．25）升高而CD8^＋下降（P〈0．01）。（2）伤后4、7、10d，EIN组肠黏膜PCNA表达水平、浆细胞数量及肠黏液S-IgA含量较EN组明显升高（P〈0．05或P〈0．01）。结论烫伤后早期给予肠内免疫营养，可以提高全身及肠道免疫功能，效果优于标准肠内营养。     

胆囊切除术后肠道菌群及sIgA含量的研究

目的　研究胆囊切除后肠道菌群及肠道sIgA含量的变化。方法　 60例研究对象中2 0例为体格检查健康者 ,40例为胆囊良性病变行胆囊切除术后患者 ,其中 2 0例术后大便正常 ,2 0例术后大便次数或性状较情况术前有改变。用培养的方法检测肠道菌群 ,透射比浊法测定粪便中sIgA。结果　胆囊切除后肠道双歧杆菌、乳酸杆菌明显减少 ,大肠杆菌、肠球菌明显增加 ;粪便中sIgA的含量明显下降。 结论　胆囊切除术对肠道菌群及肠道免疫功能均有影响     

Role of intestinal bifidobacteria in the pathogenesis of gut-derived bacteria/endotoxin translocation and the effect of bifidobacterial supplement on gut barrier function following burns

Early multiple organ dysfunction syndrome appears to be facilitated with bacterial translocation in severely burn injury, yet the mechanisms of bacterial translocation remains in dispute. The aim of this study was to investigate the potential role of intestinal bifidobacteria in the pathogenesis of gut-derived bacteria/endotoxin translocation following burns and the effects of bifidobacterial supplement on gut barrier. Methods: Wistar rats were randomly divided into burn group (Burn, n=60),sham burn group (SB, n=10) in experiment Ⅰ , and burn + saline group (BS, n=30), burn + bifidobacteria group (BB, n=30), and sham-burn + saline group (SS, n= 10) in experiment Ⅱ. Animals in BB group were fed bifidobacterial preparation (5 × 109 CFU/ml) after burns, 1.5ml,twice daily. Animals in BS and SS were fed saline. Samples were taken on days 1, 3, and 5 in burn groups, and on day 3 in sham-burn groups. The incidence of bacteria/endotoxin translocation and counts of Bifidobacterium, Fungi and Escherichia coli in gut mucosa were determined with standard methods. The levels of sIgA in mucus of small intestine were measured by RIA. The positive sIgA expression in lamina propria and ileum mucosal injury was evaluated light microscopically by blinded examiners. Results: Our results showed that the incidence of bacterial translocation was increased after burns, which was accompanied by significant decrease in number of bifidobacteria but significant increase in E. coli and fungi in gut mucosa, and elevation of levels of plasma endotoxin and IL-6 (P<0. 001).The incidence of bacterial translocation was markedly reduced after 3- and 5-day supplementation of bifidobacteria compared with control group (P<0.05). The counts of mucosal bifidobacteria were increased by 4- to 40-fold,while E. coli and fungi were decreased by 2- to 30-fold and 10- to 150-fold, respectively, after bifidobacterial supplementation in contrast to control group. The damage of mucosa tended to be less pronounced after 3-day bifidobacteria-supplemented formula compared with control group [grade 2(0-6) vs. grade 4(3-6), P<0.05]. Moreover, the expression and release of sIgA was markedly augmented after 3-day bifidobacteria-supplementation formula and it returned to normal range on day 5. Conclusion: The decrease in counts and proportion of bifidobacteria in mucous membrane flora may play an important role in the development of bacteria/endotoxin translocation following thermal injury. The supplement of exogenous bifidobacteria could per se improve gut barriers, and attenuate bacteria/endotoxin translocation secondary to major burns.     

The role of bifidobacteria in gut barrier function after thermal injury in rats

BACKGROUND: Early multiple organ dysfunction syndrome appears to be facilitated with bacterial translocation in severe burn injury, yet the mechanisms of bacterial translocation remain in dispute. The aim of this study was to characterize the potential role of intestinal bifidobacteria in the pathogenesis of gut-derived bacterial translocation after burns and to analyze the effects of bifidobacterial supplement on gut barrier function. METHODS: Wistar rats were randomly divided into burn group (Burn, n = 60), sham burn group (SB, n = 10) in experiment 1, and burn + saline group (BS, n = 30), burn + bifidobacteria group (BB, n = 30), and sham-burn + saline group (SS, n = 30) in experiment 2. Animals in BB group were fed bifidobacterial preparation (5 x 10(9) CFU/mL) after burns, 1.5 mL, twice daily. Animals in BS and SS were fed saline. Samples were taken on postburn days 1, 3, and 5. The incidence of bacterial translocation and counts of Bifidobacterium, fungi and Escherichia coli in gut mucosa, as well as the sIgA levels in mucus of the small intestine were determined. The positive sIgA expression in lamina propria and ileum mucosal injury were evaluated light microscopically by blinded examiners. RESULTS: The incidence of bacterial translocation was increased after burns, which was accompanied by significant decrease in number of bifidobacteria but significant increase in E. coli and fungi in gut mucosa, and elevation of levels of plasma endotoxin and IL-6 (p < 0.001). The incidence of bacterial translocation was markedly reduced after 3- and 5-day supplementation of bifidobacteria compared with control group (p < 0.05). The counts of mucosal bifidobacteria were increased by 4- to 40-fold, whereas E. coli and fungi were decreased by 2- to 30-fold and 10- to 150-fold, respectively, after bifidobacterial supplementation. The damage of mucosa tended to be less pronounced after 3-day bifidobacteria-supplemented formula compared with control group (grade 2 [0-6] versus grade 4 [3-6], p < 0.05). Moreover, the expression and release of sIgA was markedly augmented after 3-days of bifidobacteria-supplementation formula and it returned to normal range on postburn day 5. CONCLUSIONS: The decrease in counts and proportion of bifidobacteria to other flora in gut may play an important role in the development of bacterial translocation after thermal injury. Supplementation of exogenous bifidobacteria could improve gut barrier function, and attenuate bacterial/endotoxin translocation secondary to major burns.     

The effect of N-acetylcysteine on oxidative stress in intestine and bacterial translocation after thermal injury

Ischemia due to transient splanchnic vasoconstriction following major burns causes oxidative and/or nitrosative damage in intestinal tissue followed by reperfusion injury. Thus, burn injury leads to breakdown in the intestinal mucosal barrier which can induce bacterial translocation (BT). As an antioxidant and anti-inflammatory agent the protective effects of N-acetylcysteine (NAC) are documented in several studies. This study was designed to determine the effect of NAC treatment on the oxidative stress in the intestine and BT after burn injury. To evaluate this, 32 Wistar rats were randomly divided into four groups as sham (n = 8), burn (n = 8), pre-burn, NAC injection (150 mg kg⁻¹, intraperitoneally) 15 min before thermal injury (n = 8), post-burn, NAC injection (150 mg kg⁻¹, intraperitoneally) 2 h after thermal injury. Under anesthesia, the shaved dorsal skin of rats was exposed to boiling water for 12 s to induce burn injury in a standardized manner. Twenty-four hours later, tissue samples from mesenteric lymph nodes (MLN), spleen, and liver were obtained under sterile conditions for microbiological analysis and ileum samples were harvested for biochemical analysis. In the burn group, the incidence of isolating bacteria in MLN, spleen, and liver specimens was significantly higher than other groups. NAC treatment prevented burn-induced BT in both pre- and post-burn groups. Thermal injury caused a significant decrease in glutathione (GSH) level, significant increases in malondialdehyde (MDA) and myeloperoxidase (MPO) activity at post-burn 24th hour. Treatment of rats with NAC significantly elevated the reduced GSH levels while decreasing MDA levels and MPO activity. These data suggested that NAC has a crucial cytoprotective role in intestinal mucosal barrier and preventive effects against burn injury-induced BT.     

两种糖分子探针用于测定重症胰腺炎时肠通透性的改变

目的:观察甘露醇和乳果糖用于测定重症胰腺炎时肠通透性的改变.方法:杂种犬15条,随机分为对照组和实验性急性坏死性胰腺炎(ANP)组.发病后给犬灌服甘露醇和乳果糖混合液,收集6小时尿,气相色谱法测定其含量,并作脏器细菌培养.结果:胰腺炎组尿中乳果糖/甘露醇(L/M)比值高出对照组2～12倍,于发病后第2天最为显著.所有动物都出现了肠道细菌移位,血培养阳性率为100%,以发病后48小时内最高.对照组只有2条犬在肠系膜淋巴结培养出细菌.血培养全部阴性.结论:ANP发病后48小时内肠粘膜屏障即遭到严重破坏,发生肠道细菌移位,成为胰腺感染的来源.     

Can bacterial translocation be a beneficial event?

Infection is a major concern in intestinal transplant recipients. Bacterial migration to extraintestinal sites is a central component of the gut hypothesis of sepsis. However, some studies have cited the beneficial effects of bacterial translocation (BT) on the host acquired immune system. We evaluated the role of previous BT on a subsequent BT challenge, examined the BT index in organs as well as changes in white blood cell (WBC) count in mesenteric lymph and blood for correlation with outcomes. Wistar rats (n = 60) were divided into a BT group (n = 20), which underwent inoculation of 10 mL of 10(10) CFU/mL Escherichia coli R-6 confined to the small intestine as opposed to a BT1-14 group (n = 20), which underwent the BT procedure on days 1 and 14 or a S1-BT14 group (n = 20) that received 10 mL of saline on day 1 and the BT procedure on day 14. Half of the animals were killed 2 hours following the BT procedure. Samples from different compartments were collected for culture. Mesenteric lymph and peripheral blood were examined for WBC counts. The other half of the hosts was subjected to outcome evaluation concerning weight gain and mortality. Animals undergoing double BT showed a significantly lower index of bacterial recovery (liver, spleen, and blood) compared with those having a single BT (P < .05). The WBC count of mesenteric lymph cells after double BT was similar to na?ve animals, but significantly lower than the single BT group (P < .05). The outcome was unchanged among double BT versus other groups. A previous BT challenge was efficient to generate a host-defense mechanism against a second BT episode induced by intestinal overgrowth with the same bacterial strain.     

天然蒙脱石防治烧伤后肠道细菌移位的实验研究

目的　探讨天然蒙脱石对烧伤大鼠肠道细菌移位的防治作用。　方法　SD大鼠54只,分为正常对照组6只、烧伤对照组与烧伤治疗组各24只。后两组大鼠预先喂服转染了质粒pUC19的示踪菌JM109,证实质粒已定植于其肠道后,制成30%TBSAⅢ度烫伤(以下称烧伤)模型。烧伤治疗组大鼠伤后立即喂服天然蒙脱石0. 6g d-1 kg-1,烧伤对照组大鼠不喂服药物。观察正常对照组大鼠以及烧伤对照组、烧伤治疗组大鼠伤后12h和1、3、5d血液、肠系膜淋巴结细菌移位情况,并行酶切鉴定;检测大鼠肠组织丙二醛(MDA)及超氧化物歧化酶(SOD)的含量;用病理学方法观察整段小肠的损伤情况,测量空肠黏膜绒毛高度并计算基底膜细胞核分裂相。　结果　血液细菌培养:伤后1、5d,烧伤对照组阳性鼠数多于正常对照组,烧伤治疗组阳性鼠数少于烧伤对照组(P<0 05).肠系膜淋巴结细菌定量:烧伤治疗组伤后1、5d为(38±16)、(68±20)集落形成单位(CFU) /g;烧伤对照组伤后1、5d为( 228±67 )、( 183±29 )CFU/g,明显高于前者(P<0. 01 ).MDA、SOD含量:烧伤治疗组与烧伤对照组伤后各时相点比较,差异有统计学意义(P<0. 05).烧伤治疗组大鼠伤后各时相点空肠绒毛高度及基底膜细胞核分裂相明显高于或多于烧伤对照组(P<0. 05或0. 01)。　结论　天然蒙脱石对严重烧伤大鼠肠     

内毒素耐受对脓毒症大鼠肠道功能的保护作用

目的：动态观察内毒素耐受大鼠在内毒素血症时肠道炎症反应和免疫功能的变化,探讨内毒素耐受对内毒素血症大鼠肠道的保护作用及其机制。方法：选择健康成年雄性SD大鼠70只,随机分成3组：正常对照组（10只）、内毒素（LPS）组（30只）和内毒素耐受组（30只）。内毒素耐受组大鼠于实验第1日经腹腔注射LPS 0.25 mg/kg,24h后经腹腔注射LPS 0.5 mg/kg,LPS组在上述时间均给予等量生理盐水;实验第5日上述两组大鼠均腹腔注射大剂量LPS 10 mg/kg,于注射大剂量LPS前（0h）和注射后2、4、6、12h取大鼠肠组织制备肠黏膜上清液,用双抗体夹心法测定肠黏膜组织中分泌型免疫球蛋白A（sIgA）的含量,用免疫组化技术检测肠组织细胞间黏附分子-1（ICAM-1）的表达,并与正常对照组进行比较;光学显微镜下观察3组大鼠肠组织病理学变化,并进行病理学评分。结果：内毒素耐受组在给予小剂量LPS后没有出现体重下降。内毒素耐受组肠黏膜中slgA的含量较正常对照组明显升高,6 h最为明显（P〈0.05）,LPS组sIgA含量2 h明显升高（P〈0.05）,从6 h开始下降（P〈0.05）。内毒素耐受组给予大剂量LPS后肠黏膜ICAM-1的表达没有呈上升趋势,各时间点ICAM-1的表达与正常对照组比较差异有显著性,以6h ICAM-1的表达最低,而LPS组肠黏膜ICAM-1的表达随时间的延长逐渐升高,明显高于内毒素耐受组。肠组织病理学观察可见：LPS组肠黏膜水肿,绒毛脱落,并伴有大量炎性细胞浸润;内毒素耐受组上述表现较LPS组减轻。两组肠黏膜炎症损伤病理学评分[LPS组（3.89±0.45）分;内毒素耐受组（2.65±0.36）分]差异有显著性（P〈0.01）。结论：内毒素耐受可减轻内毒素血症导致的肠道黏膜屏障的损害,升高sIgA水平,减少ICAM-1表达,从而起到肠保护作用。