高原地区大鼠烫伤延迟复苏后Peyer结中低氧诱导因子-1α表达对T淋巴细胞凋亡与增殖的影响

目的 探讨低氧诱导因子-1α(HIF-1α)和淋巴细胞凋亡在不同海拔高度大鼠烫伤延迟复苏后的变化及意义.方法 Wistar大鼠132只,分别在l 517 m和3 848 m海拔高度随机分为延迟复苏组(DFR,,n=30)、即时复苏组(IFR,n=30)、假伤组(SG,n=6).建立30%总体表面积(TBSA)Ⅱ度烫伤模型,分别于伤后6、12、24、48和72 h各取6只大鼠开腹,取回肠组织肠肇Peyer结,采用原位末端缺刻标记法(TUNEL)、免疫组化染色与图像分析技术.观察回肠Peyer结中淋巴细胞凋亡率及HIF-1α和CD3的阳性表达.结果 DFR组伤后各时间点Peyer结淋巴细胞凋亡率均明显高于同海拔高度IFR各组,随海拔高度上升凋亡率升高,伤后12 h凋亡率最高(P均<0.05).HIF-1α阳性表达位于Peyer结中淋巴细胞胞核内,IFR组和DFR组表达强度明显高于同海拔SG组,并随海拔高度上升而增强(P均<0.05).CD3表达位于Peyer结中T淋巴细胞胞膜上,IFR组和DFR组CD3表达强度低于同海拔SG组,并随海拔高度上升而减弱,伤后12 h表达降至最低(P均<0.05).结论 高原地区烫伤延迟复苏后HIF-1α表达增高可能是Peyer结T淋巴细胞凋亡率增加和细胞数降低的重要原因之一.     

MAdCAM-1在大鼠小肠移植肠管中的表达及其意义

【目的】通过建立大鼠小肠移植模型,观察粘附素细胞粘附分子-1（MAdCAM-1）在大鼠小肠移植肠管中的表达及移植肠管的改变。【方法】实验分三组,第Ⅰ组为同系同基因移植（从LEW鼠到LEW鼠）;第Ⅱ组为异系同基因移植（从DA鼠到LEW鼠）;第Ⅲ组为使用抗-MAdCAM-1抗体的异系同基因移植。将DarkAgouti（DA）鼠的小肠异位移植到Lewis（LEW）鼠中。观察各组移植肠管的形态和组织学变化;并用免疫染色检测MAdCAM-1和整合素a4137在移植肠管中的表达。通过荧光激活细胞分类术来分析移植肠管中肠系膜淋巴结和肠管Peyer＇s淋巴结的淋巴细胞浸润情况。【结果】实验组大鼠移植肠管存活期为（7．0±3．3）d,对照组为（24．6±8．4）d（P〈0．05）。并且,在实验组的移植肠管中MAdCAM-1的表达被抑制。而对照组在Peyefs淋巴结中CD4^＋T细胞和CD8^＋T细胞无显著差别,实验组的肠系膜淋巴结中CD4^＋T细胞有显著降低。【结论】在小肠移植中,通过阻断抗-MAdCAM-1抗体可以用来预防急性排斥反应。     

黄芪多糖对毛囊干细胞增殖及其特异性标记物K19及β1整合素基因表达的调控作用

目的:观察黄芪多糖对毛囊干细胞增殖及其特异性标记物K19及β1整合素基因表达的调控作用。方法:取7～8 d龄Wistar大鼠,分离隆突区细胞,用Ⅳ型胶原黏附法获取毛囊干细胞。将获取的毛囊干细胞分为实验组a1～a4(培养液中分别加入黄芪多糖50～5μg/mL)及对照组b,未黏附细胞设为对照组c(KSFM培养液中均不加入黄芪多糖),培养10 d。运用K15、19及β1整合素单克隆抗体免疫组化鉴定培养细胞;并测定各组培养细胞K15、K19、β1整合素阳性表达率;Real-Time PCR检测各组培养细胞K19、β1整合素mRNA表达因表达水平。结果:免疫组化鉴定显示Ⅳ型胶原黏附细胞符合毛囊干细胞特征。实验组K15、K19、β1整合素阳性表达率及K19、β1整合素基因表达水平较对照组显著提高(P<0.05),黄芪多糖浓度为10～20μg/mL时作用最为明显。结论:黄芪多糖能促进毛囊干细胞增生及特异性标记物K19、β1整合素基因表达,中药黄芪促进毛发生长或治疗脱发病的机制可能与此相关。     

宣肺通腑化瘀法对肺间质纤维化小鼠羟脯氨酸和转化生长因子-β1含量的影响

目的 探讨宣肺通腑化瘀法防治肺间质纤维化(PF)的作用及其机制.方法 将28只ICR小鼠随机分为对照组、模型组、宣肺通腑化瘀法(中药)组、泼尼松组4组,每组7只.经鼻滴入博莱霉素建立小鼠PF模型.中药组和泼尼松组于制模8 h内开始分别灌胃中药组方15.86 g/kg或泼尼松1.3 mg/kg,每日1次,连用28 d;对照组及模型组给予等量生理盐水.于制模28 d取小鼠肺组织观察病理学改变及纤维化程度;用酶联免疫吸附法测定支气管肺泡灌洗液(BALF)中转化生长因子-β1(TGF-β1)含量;用样本碱水解法检测肺组织中羟脯氨酸(HYP)含量.结果 模型组小鼠肺泡炎症及纤维化程度均明显重于对照组;肺组织中HYP含量及BALF中TGF-β1含量均较对照组显著升高(P均<0.01).中药组和泼尼松组炎症及纤维化程度明显改善,HYP及TGF-β1含量均明显低于模型组(P均<0.01),且中药组TGF-β1降低程度更为显著(P<0.05).结论 宣肺通腑化瘀法能明显减轻博来霉素致小鼠PF程度,降低肺组织中HYP含量;其机制可能是通过抑制TGF-β1蛋白表达,减少胶原蛋白产生,使PF病变减轻.     

重组人骨形成蛋白2对下颌骨牵引成骨中整合素β_1表达的影响

背景:骨组织中整合素表达水平可影响细胞功能,调控成骨和骨吸收,但整合索只有被其他因于激活后才能发挥强大的黏附作用,重组人骨形成蛋白2具有此作用吗?目的:观察不同质量重组人骨形成蛋白2对兔下颌骨牵引成骨区整合素B_1的表达影响.设计、时间及地点:随机分组动物实验,组织学观察,于2006-05/2007-05在辽宁医学院动物实验中心和免疫组化中心完成.材料:日本成年大耳白兔45只.重组人骨形成蛋白2由北京军事医学科学院三所八室提供.方法:选用日本成年大耳白兔45只建立下颌骨牵引模型,造模后采用随机数表法将分为3组:空白对照组、1.5,3.0 mg重组人骨形成蛋白2胶原海绵载体组,15只/组.分别将不含重组人骨形成蛋白2胶原海绵载体、含1.5,3.0 mg重组人骨形成蛋白胶原复合物植入3组兔下颌骨切开处,固定、牵引0.4 mm/次,2次/d,共计5 d,总延长下颌骨4 mm.主要观察指标:牵引后稳定期第1,3,7,14,28天取牵引区新生骨痂行免疫组织化学染色观察骨组织中整合素β_1的表达.结果:45只日本大耳白兔均建模成功,进入结果分析.整合素β_1在牵引区表达主要反映在牵引7 d后.在同一时间内,随着重组人骨形成蛋白2质量的增加,整合素β_1阳性细胞表达率、阳性面积百分比逐渐增多(P<0.05):在同一质量下,随着时间的延长,整合素β_1阳性细胞阳性表达率、阳性面积百分比逐渐上升(P<0.05).结论:局部应用外源性重组人骨形成蛋白2在牵引成骨中晚期对整合素β_1的表达有促进作用,并且整合素β_1的表达对重组人骨形成蛋白2呈质量依赖性.     

HIV感染与肠道免疫系统关系的研究进展

近年对人类免疫缺陷病毒(human immunodeficiency virus,HIV)发病机制研究催生出肠道是HIV感染的主要病灶的新观点.该理论认为:(1)在急性感染阶段,T淋巴细胞主要是在肠道组织中被HIV消耗;(2)肠道中的T淋巴细胞消耗是快速的、大量的和持续的,原因与T淋巴细胞的归巢受体CCR9和整合素α4β7密切相关;(3)抗病毒治疗并不能完全重建肠道的免疫系统.研究发现在急性HIV感染阶段,外周血CD4+T淋巴细胞的数量尚未出现改变时,肠道CD4+T淋巴细胞就已经开始消耗;接受高效抗逆转录病毒治疗(highly active antiretroviral therapy,HAART)的患者,外周血CD4+T淋巴细胞数量大幅度的恢复,但是肠道中CD4+T淋巴细胞在很大程度上仍然被消耗,肠道CD4+T淋巴细胞数量比外周血恢复慢得多.因此主要以外周血CD4+T淋巴细胞的数量和病毒载量来决定是否开始或停止治疗的策略是不完全正确的.在急性感染后,由于HIV直接杀伤和间接的细胞凋亡作用,CD4+T淋巴细胞在肠道迅速被消耗.后期随着机体T淋巴细胞的减少和HIV的大量复制,使得机体的免疫系统的完全崩溃,最终发展为艾滋病(acquired immunodeficiency syndrome,AIDS).     

督脉电针对脊髓损伤后MAPK/ERK/1/2信号通路的影响

目的 观察督脉电针对脊髓损伤（SCI）小鼠MAPK/ERK1/2信号通路相关蛋白表达的影响。 方法 采用随机数字表法将64只C57BL/6小鼠分为假手术组、脊髓损伤组、督脉针刺组和督脉电针组。将脊髓损伤组、督脉针刺组及督脉电针组小鼠制成SCI动物模型。假手术组及脊髓损伤组小鼠制模后均未给予特殊处理,督脉针刺组小鼠于制模后次日给予单纯针刺治疗（取穴大椎、命门）,督脉电针组小鼠于制模后次日给予电针治疗,取穴方法同督脉针刺组,电刺激设置疏密波（2/100 Hz）,电刺激强度0.2 mA。于制模后3 d、7 d、14 d及28 d时分别采用免疫荧光、蛋白印迹法测定各组小鼠受损脊髓p-ERK1/2、p-Akt及髓鞘碱性蛋白(MBP)表达情况。 结果 与脊髓损伤组同期比较,督脉电针组在制模后3 d、14 d及28 d时,督脉针刺组在制模后28 d时其受损脊髓p-ERK1/2蛋白表达均显著增强(P<0.05);与督脉针刺组比较,督脉电针组在制模后3 d、14 d时其受损脊髓p-ERK1/2蛋白表达均明显增强(P<0.05)。督脉电针组在制模后14 d、28 d时,督脉针刺组在制模后28 d 时其受损脊髓p-Akt蛋白表达均较脊髓损伤组显著增强(P<0.05),督脉针刺组在制模后3 d时其受损脊髓p-Akt蛋白表达较脊髓损伤组明显减弱(P<0.05)。督脉电针组在制模后3 d、7 d、14 d时,督脉针刺组在制模后3 d、7 d时其受损脊髓MBP蛋白表达均较脊髓损伤组明显增强(P<0.05)。 结论 督脉电针可促进SCI小鼠p-ERK1/2、p-Akt及MBP蛋白表达。     

阿的平对微波辐射小鼠血液系统炎症反应的影响

本研究旨在探讨阿的平(Quinacrine)对微波辐射后小鼠外周血粒细胞、淋巴细胞、血清白介素1(IL-1)、白介素6(IL-6)含量的影响,观察阿的平对微波辐射引起的炎症反应的拮杭作用.130只BALB/c小鼠随机分为4组:正常对照组、辐射对照组(注射用水组)、低剂量组(阿的平12.6 mg/kg)、高剂量组(阿的平50.4 mg/kg).小鼠灌胃给予阿的平后1小时,将辐射对照组、低剂量组、高剂量组用强度为50 mW/cm2的微波照射30分钟.在照射后即刻、1天、2天、7天处死小鼠取血,用血细胞分析仪测定外周血粒细胞数,用放射免疫法检测血清IL-1β、IL-6含量的变化.结果表明,微波辐照后粒细胞和淋巴细胞数量随时间延长明显增加,在给药组这些细胞数量改变的趋势均明显延缓;50 mW/cm2微波辐射1天后小鼠血清IL-1β水平明显升高,直至7天后方逐渐恢复至正常水平,而2个浓度的阿的平灌胃均能抑制辐射引起的血清IL-1β水平升高;50mW/cm2微波辐射后血清IL-6水平从即刻至7天逐渐升高,阿的平灌胃能够明显延缓IL-6的升高,在辐射后2天内阿的平的作用尤为明显.结论:辐照前灌胃给予阿的平能够明显延缓微波辐射引起的小鼠粒细胞和淋巴细胞数量增加,能够部分抑制血清IL-1β和IL-6水平的增高并产生了一定的拮抗作用.本研究结果提示阿的平可能有一定的抗微波辐射效应.     

肠血管活性多肽或生长抑素对多器官功能障碍综合征鼠肠黏膜MAdCAM-1表达的影响

目的 探讨肠血管活性多肽(VIP)或生长抑素(SST)对多器官功能障碍综合征(NODS)大鼠小肠黏膜地址素黏附分子-1(MAdCAM-1)表达的影响及其对MODS防治的意义.方法 36只雄性Wistar大鼠随机分为6组(每组6只),包括对照组(正常大鼠)、VIP1组和SST1组(分别经VIP和SST处置的止常人鼠)、MODS组(MODS大鼠)、VIP2组和SST2组(分别经VIP和SST处置的MODS大鼠).采用肠缺血再灌注方法制作MODS大鼠(出现全身炎症反应,＞2个器官功能障碍)模型.VIP或～SYITM以0.2 ρmol·g-1·h-1静脉输入和0.25 ρmol/g腹腔注入大鼠体内.各组收集的肠淋巴细胞用51 Cr标记后心输入大鼠体内,γ计数器测定其在肠相关淋巴组织(GALT)的数量分布;Western blot测定各组小肠黏膜MAdCAM-1的表达;组织化学法观察各组小肠黏膜组织学变化.数据采用t检验进行分析.结果 VIP1组和SST1组小肠弥散淋巴组织MAdCAM-1表达的峰浓度值分别为(157.67±2.52)、(154.33±3.22),Peyer's结为(136.00±1.00)、(137.00±1.00),较对照组[(165.33±1.53)、(152.67±2.31)]无显著改变(P＞0.05);归巢至小肠弥散淋巴组织51 Cr-细胞量占总 51 Cr-细胞量的1.04%±0.59%、1.01%±0.83%,较对照组(1.07%±0.61%)无显著改变(P＞0.05);Peyer's结为1.83%±0.90%、1.56%±0.64%,显著低于MODS组[(3.85%±2.02%),P＜0.05].VIP2组和SST2组小肠弥散淋巴组织MAdCAM-1表达的峰浓度值分别为(158.00±2.65)、(154.33±1.53),Peyer's结为(156.33±1.53)、(151.33±2.31),较MODS绀[(175.33±2.52)、(173.00±2.65),P＜0.05];归巢至小肠弥散淋巴组织51 Cr-细胞量占总51 Cr-细胞量的1.58%±0.42%、1.45%±0.26%,Peyer's结为2.14%±1.49%、0.81%±0.35%,显著低于NODS组[(3.23%±1.69%)、(5.04%±1.23%),P＜0.05],并伴有肠黏膜组织学损害的减轻.结论 增加MODS人鼠血循环中的VIP或SST,可通过抑制肠黏膜MAdCAM-1表达,减少肠淋巴细胞门巢至GALT,减轻MODS时肠黏膜的炎性损伤.     

α7-nAchR激动剂GTS-21对放射性肠炎小鼠的疗效及对其血清炎症因子的影响

目的探讨α7-n AchR激动剂GTS-21对放射性肠炎小鼠的临床疗效,并观察其对血清炎症因子水平的影响。方法选取100只成年雌性BALB/c小鼠,对其腹部进行10 Gy照射建立放射性肠炎模型,并随机分为GTS-21组和对照组,各50只。其中GTS-21组分别在照射前1 d和照射后1 d腹腔注射GTS-21,对照组腹腔注射无菌生理盐水。分别于照射后1 d、2 d、3 d、4 d、5 d抽取小鼠尾静脉血检测血清肿瘤坏死因子-α(TNF-α)、白介素-1β(IL-1β)、白介素-6(IL-6)水平。对比不同时刻两组小鼠体质量、粪便成型量、血清炎症因子水平变化。另在照射5 d后处死并采用HE染色观察肠道隐窝深度。结果对照组小鼠体质量、粪便成型量每2个时刻间对比差异均有统计学意义(P0.05),且治疗后2 d、3 d、4 d和5 d时GTS-21组小鼠体质量、粪便成型量均明显高于对照组(P0.05);两组血清TNF-α、IL-1β、IL-6水平均随着时间的延长逐渐显著升高,除1 d后每2个时刻间对比差异均有统计学意义(P0.05),且治疗后2 d、3 d、4 d和5 d时GTS-21组小鼠血清炎性因子水平均明显低于对照组(P0.05);GTS-21组小鼠肠道隐窝深度明显高于对照组。结论α7-n AchR激动剂GTS-21对放射性肠炎小鼠有理想的治疗作用,并且能够降低血清炎症因子水平,增多肠道隐窝结构。     

Aberrant activation of integrin alpha4beta7 suppresses lymphocyte migration to the gut

Integrin adhesion molecules mediate lymphocyte migration and homing to normal and inflamed tissues. While the ligand-binding activity of integrins is known to be modulated by conformational changes, little is known about how the appropriate balance of integrin adhesiveness is maintained in order to optimize the migratory capacity of lymphocytes in vivo. In this study we examined the regulation of the gut homing receptor alpha4beta7 integrin by manipulating at the germline level an integrin regulatory domain known as adjacent to metal ion-dependent adhesion site (ADMIDAS). ADMIDAS normally serves to raise the activation threshold of alpha4beta7, thereby stabilizing it in the default nonadhesive state. Lymphocytes from knockin beta7 (D146A) mice, which harbor a disrupted ADMIDAS, not only expressed an alpha4beta7 integrin that persistently adhered to mucosal addressin cell adhesion molecule-1 (MAdCAM-1), but also exhibited perturbed cell migration along MAdCAM-1 substrates resulting from improper de-adhesion of the lymphocyte trailing edge. In vivo, aberrantly activated alpha4beta7 enhanced adhesion to Peyer's patch venules, but suppressed lymphocyte homing to the gut, diminishing the capacity of T cells to induce colitis. Our results underscore the importance of a proper balance in the adhesion and de-adhesion of the alpha4beta7 integrin, both for lymphocyte trafficking to the gut and for colitis progression.     

Lymphocyte homing to bronchus-associated lymphoid tissue (BALT) is mediated by L-selectin/PNAd,alpha4beta1 integrin/VCAM-1, and LFA-1 adhesion pathways

Bronchus-associated lymphoid tissue (BALT) participates in airway immune responses. However, little is known about the lymphocyte-endothelial adhesion cascades that recruit lymphocytes from blood into BALT. We show that high endothelial venules (HEVs) in BALT express substantial levels of VCAM-1, in marked contrast to HEVs in other secondary lymphoid tissues. BALT HEVs also express the L-selectin ligand PNAd. Anti-L-selectin, anti-PNAd, and anti-LFA-1 mAbs almost completely block the homing of B and T lymphocytes into BALT, whereas anti-alpha4 integrin and anti-VCAM-1 mAbs inhibit homing by nearly 40%. alpha4beta7 integrin and MAdCAM-1 are not involved. Importantly, we found that mAbs against alpha4 integrin and VCAM-1 significantly block the migration of total T cells (80% memory phenotype) but not naive T and B cells to BALT. These results suggest that an adhesion cascade, which includes L-selectin/PNAd, alpha4beta1 integrin/VCAM-1, and LFA-1, targets specific lymphocyte subsets to BALT. This high level of involvement of alpha4beta1 integrin/VCAM-1 is unique among secondary lymphoid tissues, and may help unify lymphocyte migration pathways and immune responses in BALT and other bronchopulmonary tissues.     

早期药膳饮食对烫伤大鼠肠黏膜Peyer’s结T淋巴细胞及亚群的影响

背景：肠相关淋巴组织的组成部分Peyer’s 结是肠黏膜免疫系统的重要诱导部位,含有参与免疫应答的各种免疫细胞,如CD4 ＋T 细胞、CD8 ＋T 细胞、B细胞等。目的：观察早期药膳饮食对烫伤大鼠肠道肠黏膜Peyer’s结T淋巴细胞及其亚群的影响。设计、时间及地点：随机对照动物实验,于2006-04/2007-03 在南昌大学一附属医院完成。材料：Wistar 大鼠100 只,随机分成药膳喂养组（n=30）、肉汤喂养组（n=30）、常规喂养组（n=30）、正常对照组（n=10）。药膳成分：党参20 g、白术25 g、茯苓25 g、炙甘草15 g、黄芪20 g、薏苡仁20 g、瘦猪肉200 g。方法：药膳喂养组、肉汤喂养组、常规喂养组实施背部30%体表面积Ⅲ度烫伤,伤后早期分别给予药膳、肉汤和生理盐水,2 mL/次,2 次/d。正常对照组实施37 ℃假伤。主要观察指标：伤后3,7,14 d 检测大鼠肠黏膜Peyer’s结T 淋巴细胞及亚群。结果：伤后3,7 d,药膳喂养组、肉汤喂养组、常规喂养组Peyer’s结淋巴细胞总数、CD3＋淋巴细胞的百分比及总数、CD4＋百分比及总数、CD8＋细胞的百分比及总数较正常对照组明显减少 （P 〈 0.05,P 〈 0.01）,至14 d,药膳喂养组与正常对照组相比差异不显著。伤后3,7,14 d 药膳喂养组CD3＋淋巴细胞的百分比及总数、CD4＋百分比及总数较肉汤喂养组、常规喂养组明显升高（P 〈 0.05）。伤后3,7 d 药膳喂养组Peyer’s结CD8＋细胞的百分比及总数较肉汤喂养组、常规喂养组明显下降（P 〈 0.05）。结论：早期药膳饮食有利于肠道Peyer’s 结淋巴细胞的增生,并改善Peyer’s 结T 淋巴细胞亚群的比例,从而改善烫伤大鼠肠道免疫功能。     

Lymphocyte migration in lymphocyte function-associated antigen (LFA)-1-deficient mice

Using lymphocyte function-associated antigen (LFA)-1(-/-) mice, we have examined the role of LFA-1 and other integrins in the recirculation of lymphocytes. LFA-1 has a key role in migration to peripheral lymph nodes (pLNs), and influences migration into other LNs. Second, the alpha4 integrins, alpha4beta7 and alpha4beta1, have a hitherto unrecognized ability to compensate for the lack of LFA-1 in migration to pLNs. These findings are confirmed using normal mice and blocking LFA-1 and alpha4 monoclonal antibodies. Unexpectedly, vascular cell adhesion molecule (VCAM)-1, which is essential in inflammatory responses, serves as the ligand for the alpha4 integrins on pLN high endothelial venules. VCAM-1 also participates in trafficking into mesenteric LNs and Peyer's patch nodes where mucosal addressin cell adhesion molecule 1 (MAdCAM-1), the alpha4beta7-specific ligand, dominates. Both alpha4beta1, interacting with ligand VCAM-1, and also LFA-1 participate in substantial lymphocyte recirculation through bone marrow. These observations suggest that organ-specific adhesion receptor usage in mature lymphocyte recirculation is not as rigidly adhered to as previously considered, and that the same basic sets of adhesion receptors are used in both lymphocyte homing and inflammatory responses.     

Gut ischemia-reperfusion affects gut mucosal immunity: a possible mechanism for infectious complications after severe surgical insults

OBJECTIVE: To examine influences of gut ischemia/reperfusion (I/R) on gut-associated lymphoid tissue (GALT) mass and function. DESIGN: Prospective, randomized controlled study. SETTING: Research laboratory. SUBJECTS: Male Institute of Cancer Research mice. INTERVENTIONS: Ninety mice were randomized to three groups: I/R (60-min gut ischemia), sham (laparotomy only), and control (no operation). On days 1, 2, 4, 7, and 10, mice were killed to harvest lymphocytes from Peyer patches, the intraepithelial space, and the lamina propria (LP) of the small intestine. Respiratory tract and small intestinal washings were also obtained. MEASUREMENTS AND MAIN RESULTS: Gut I/R significantly reduced lymphocyte numbers in Peyer patches, the intraepithelial space, and the LP. The reduction was prominent in GALT effector sites, that is, the intraepithelial space and LP, but numbers recovered quickly in LP. Changes in cell numbers in Peyer patches, GALT inductive sites, were subtle but persistent. Gut I/R reduced B cell numbers in Peyer patches; alphabeta T cell receptor (TCR)+, gammadeltaTCR+, CD8+, and B cell numbers in the intraepithelial space; and gammadeltaTCR+, CD8+, and B cell numbers in the LP, in comparison with the sham or control group. There were no significant differences in respiratory tract immunoglobulin A levels between the I/R and sham groups. Intestinal immunoglobulin A was elevated on day 1 in the I/R group, with no significant difference after day 2 in comparison with the sham group. CONCLUSIONS: Despite the maintained mucosal immunoglobulin A level, gut I/R markedly reduces GALT cell numbers, with changes in lymphocyte phenotypes. These alterations may be associated with increased morbidity due to infectious complications after severe surgical insults.     

The alpha 4 integrin chain is a ligand for alpha 4 beta 7 and alpha 4 beta 1

The heterodimeric alpha 4 integrins alpha 4 beta 7 lymphocyte Peyer's patch adhesion molecule ([LPAM]-1) and alpha 4 beta 1 (very late antigen-4) are cell surface adhesion molecules involved in lymphocyte trafficking and lymphocyte-cell and matrix interactions. Known cellular ligands include vascular cell adhesion molecule (VCAM)-1, which binds to alpha 4 beta 1 and alpha 4 beta 7, and the mucosal addressin cell adhesion molecule (MAdCAM)-1, which binds to alpha 4 beta 7. Here we show that the alpha 4 chain of these integrins can itself serve as a ligand. The alpha 4 chain, immunoaffinity purified and immobilized on glass slides, binds thymocytes and T lymphocytes. Binding exhibits divalent cation requirements and temperature sensitivity which are characteristic of integrin-mediated interactions, and is specifically inhibited by anti-alpha 4 integrin antibodies, which exert their effect at the cell surface. Cells expressing exclusively alpha 4 beta 7 (TK-1) or alpha 4 beta 1 (L1-2) both bound avidly, whereas alpha 4-negative cells did not. A soluble 34-kD alpha 4 chain fragment retained binding activity, and it inhibited lymphocyte adhesion to alpha 4 ligands. It has been shown that alpha 4 integrin binding to fibronectin involves an leucine-aspartic acid-valine (LDV) motif in the HepII/IIICS region of fibronectin (CS-1 peptide), and homologous sequences are important in binding to VCAM-1 and MAdCAM-1. Three conserved LDV motifs occur in the extracellular sequence of alpha 4. A synthetic LDV-containing alpha 4- derived oligopeptide supports alpha 4-integrin-dependent lymphocyte adhesion and blocks binding to the 34-kD alpha 4 chain fragment. Our results suggest that alpha 4 beta 7 and alpha 4 beta 1 integrins may be able to bind to the alpha 4 subunit on adjacent cells, providing a novel mechanism for alpha 4 integrin-mediated and activation-regulated lymphocyte interactions during immune responses.     

Vascular addressins are induced on islet vessels during insulitis in nonobese diabetic mice and are involved in lymphoid cell binding to islet endothelium.

In the nonobese diabetic (NOD) mouse, lymphocytic and monocytic infiltration of the pancreatic islets leads to beta cell destruction. To investigate the mechanisms by which lymphocytes enter the NOD pancreas, pancreata were immunostained using monoclonal antibodies to a variety of adhesion molecules known to be involved in lymphocyte binding to vascular endothelium, an initial step in the migration of lymphocytes from blood into organized lymphoid and inflamed tissues. These adhesion molecules include: lymphocyte homing receptors involved in tissue-selective binding of lymphocytes to peripheral lymph node (L-selectin) or mucosal lymphoid tissue (LPAM-1, alpha 4 beta 7-integrin) high-endothelial venules (HEV); and HEV ligands peripheral vascular addressin (PNAd) and mucosal vascular addressin (MAdCAM-1). In NOD pancreata, alpha 4 beta 7 is expressed on most infiltrating cells at all stages of insulitis, whereas L-selectin expression is more pronounced on cells in the islets at later stages. During the development of insulitis, MAdCAM-1 and to a lesser extent PNAd became detectable on vascular endothelium adjacent to and within the inflamed islets. The Stamper-Woodruff in vitro assay was used to examine lymphoid cell binding to such vessels. These functional assays show that both the mucosal (MAdCAM-1/alpha 4 beta 7) and the peripheral (PNAd/L-selectin) recognition systems are involved in this binding. Our findings demonstrate that expression of peripheral and mucosal vascular addressins is induced on endothelium in inflamed islets in NOD pancreas, and that these addressins participate in binding lymphoid cells via their homing receptors. This suggests that these adhesion molecules play a role in the pathogenesis of diabetes in these mice by being involved in the migration of lymphocytes from blood into the inflamed pancreas.     

Intestinal mast cell progenitors require CD49dbeta7 (alpha4beta7 integrin) for tissue-specific homing.

Mast cells (MCs) are centrally important in allergic inflammation of the airways, as well as in the intestinal immune response to helminth infection. A single lineage of bone marrow (BM)-derived progenitors emigrates from the circulation and matures into phenotypically distinct MCs in different tissues. Because the mechanisms of MC progenitor (MCp) homing to peripheral tissues have not been evaluated, we used limiting dilution analysis to measure the concentration of MCp in various tissues of mice deficient for candidate homing molecules. MCp were almost completely absent in the small intestine but were present in the lung, spleen, BM, and large intestine of beta7 integrin-deficient mice (on the C57BL/6 background), indicating that a beta7 integrin is critical for homing of these cells to the small intestine. MCp concentrations were not altered in the tissues of mice deficient in the alphaE integrin (CD103), the beta2 integrin (CD18), or the recombination activating gene (RAG)-2 gene either alone or in combination with the interleukin (IL)-receptor common gamma chain. Therefore, it is the alpha4beta7 integrin and not the alphaEbeta7 integrin that is critical, and lymphocytes and natural killer cells play no role in directing MCp migration under basal conditions. When MCp in BALB/c mice were eliminated with sublethal doses of gamma-radiation and then reconstituted with syngeneic BM, the administration of anti-alpha4beta7 integrin, anti-alpha4 integrin, anti-beta7 integrin, or anti-MAdCAM-1 monoclonal antibodies (mAbs) blocked the recovery of MCp in the small intestine. The blocking mAbs could be administered as late as 4 d after BM reconstitution with optimal inhibition, implying that the MCp must arise first in the BM, circulate in the vasculature, and then translocate into the intestine. Inasmuch as MCp are preserved in the lungs of beta7 integrin-deficient and anti-alpha4beta7 integrin-treated mice but not in the small intestine, alpha4beta7 integrin is critical for tissue specific extravasation for localization of MCp in the small intestine, but not the lungs.