胆红素对抗脂多糖诱导致大鼠急性肺损伤的实验研究

目的：探讨胆红素对抗急性肺损伤（ALI）的作用及其机制。方法： 用雄性Wistar大鼠（200-250 g） 30只，随机分为生理盐水对照组、脂多糖（LPS）致ALI动物模型组、胆红素干预组。观察病理形态变化并检测肺组织肺系数（LI）；支气管肺泡灌洗液（BALF）中白细胞（WBC）计数、中性粒细胞（PMN）百分比、蛋白质含量（Pr）；肺泡通透指数（LPI）及肺组织匀浆中超氧化物歧化酶（SOD）、脂质过氧化产物丙二醛（MDA）、谷胱甘肽过氧化物酶（GSH-Px）水平变化。结果： （1）ALI模型组LI，BALF中WBC计数、PMN百分比、Pr及LPI均显著高于生理盐水对照组（均P<0.01）。胆红素干预组LI，BALF中WBC计数和LPI均显著低于AIL模型组（均P<0.01），PMN百分比和Pr明显低于ALI模型组（均P<0.05），且与生理盐水对照组无显著差异（P>0.05）。（2）ALI模型组MDA含量显著多于生理盐水对照组（P<0.01），SOD活性和GSH-Px含量都明显低于生理盐水对照组(P<0.01)。胆红素干预组MDA含量明显低于ALI模型组 (P<0.01)，而SOD活性和GSH-Px含量显著多于ALI模型组（P<0.01，P<0.05)且与生理盐水对照组无显著差异（P>0.05）。结论： 胆红素通过其抗氧化作用对抗大鼠急性肺损伤。     

髓过氧化物酶、CD11b和IL-8在哮喘大鼠模型中表达增加

目的观察哮喘模型大鼠中性粒细胞(PMN)CD11bI、L-8和髓过氧化物酶(MPO)的表达,探讨PMN在哮喘中的作用及其可能的机制。方法复制哮喘大鼠模型,随机分成哮喘组和对照组,分离纯化血PMN;免疫组化法检测MPO表达,ELISA法测定IL-8蛋白,流式细胞术测定血PMN CD11b表达,支气管肺泡灌洗液(BALF)行细胞计数。结果哮喘组肺组织和血PMN中MPO、CD11b及血PMN和BALF中IL-8的水平显著高于对照组(P<0.01)。哮喘组BALF中PMN和嗜酸性粒细胞计数显著高于对照组(P<0.01)。结论BALF中PMN数量增加及血中PMN和肺组织中CD11bI、L-8和MPO在哮喘时表达增加,他们可能参与了哮喘的炎症过程。     

益活清胰Ⅰ号对重症急性胰腺炎大鼠中性粒细胞与内皮细胞黏附的抑制作用

目的观察益活清胰Ⅰ号对重症急性胰腺炎(severe acute pancreatitis,SAP)大鼠的中性粒细胞(polymorphonuclear cell,PMN)-内皮细胞(endothelial cell,EC)黏附率及PMN表面黏附分子CD11/CD18表达的影响,探讨其治疗SAP的机理。方法81只SD大鼠随机分为假手术组(n=27)、造模组(n=27)、治疗组(n=27),SAP模型采用5%的牛磺胆酸钠胰胆管逆行注射方法建立。6、12、24h分批处死动物9只采集动脉血和胰腺组织标本,测定胰腺组织的MPO活性,HE染色光镜下观察胰腺组织的病理变化。分离PMN,与体外培养的血管内皮细胞作用测定PMN-EC黏附率,ELISA法测定PMN表面CD11a/CD18、CD11b/CD18。结果与假手术组比较,造模组和治疗组术后各时点胰腺组织MPO活性、PMN-EC黏附率、PMN表面CD11a/CD18和CD11b/CD18均增高(P<0.01),治疗组术后各时点胰腺组织MPO活性、PMN-EC黏附率、PMN表面CD11a/CD18和CD11b/CD18均显著低于造模组(P<0.01)。造模组胰腺组织出血和坏死严重,治疗组的病理损伤明显减轻。结论益活清胰Ⅰ号能降低PMN表面CD11a/CD18和CD11b/CD18的表达水平,减轻PMN与EC的黏附,从而有助于减轻PMN与EC黏附所致的胰腺组织病理损伤。     

P38 MAPK抑制剂对急性肺损伤大鼠细胞间黏附分子-1表达的影响

目的观察P38 MAPK抑制剂预处理对脂多糖(LPS)致大鼠急性肺损伤(ALI)细胞间黏附分子-1(ICAM-1)的影响,探讨P38 MAPK抑制剂干预ALI的理论基础。方法腹腔内注射 气管内给LPS复制大鼠ALI模型,用免疫组化方法测定肺组织ICAM-1的表达。结果模型组和预处理组的ICAM-1表达显著高于对照组(P<0.01,P<0.05),且模型组高于预处理组(P<0.05)。结论P38MAPK抑制剂预处理可下调大鼠细胞黏附分子ICAM-1的表达,减轻肺组织的病理损害,能起到防治ALI的作用。     

小檗碱抗小鼠脂多糖性肺损伤的作用机制

目的：探讨小檗碱(Ber)对抗脂多糖(LPS)性急性肺损伤(ALI)的作用机制。方法：雄性BALB/c小鼠随机分为对照组、ALI组和Ber防治组，分别予以双蒸水、Ber(50 mg/kg)灌胃，1次/d，连续3 d，于实验第3 d灌胃后1 h，腹腔注射生理盐水或LPS (20 mg/kg)。测定各组12 h肺湿/干重比值(W/D)，肺泡灌洗液(BALF)中微量总蛋白含量、白细胞(WBC)和中性粒细胞(PMN)总数；观察肺组织病理改变及磷酸化胞浆型磷脂酶A₂(cPLA₂)在肺组织中的表达。进一步用酶联免疫吸附法(ELISA)测定BALF中血栓素B₂(TXB₂)的含量，并测定肺组织丙二醛(MDA)的含量和超氧化物歧化酶(SOD)的活性。结果：ALI组，LPS 攻击后12 h肺W/D、BALF中蛋白含量、WBC 及PMN总数显著高于对照组(P<0.05)；病理检查发现肺间质充血、水肿，大量炎性细胞浸润。免疫组织化学观察显示肺组织中磷酸化cPLA₂的表达明显增加；同时，BALF中TXB₂含量、肺组织MDA的含量显著高于对照组(P<0.05)。Ber防治组，肺W/D、BALF中蛋白含量、WBC及PMN总数均明显低于ALI组；与ALI组比较，Ber防治组肺组织病理损伤明显减轻(P<0.05)；而且，肺组织中磷酸化cPLA₂的表达明显减少 (P<0.05)； BALF中TXB₂含量和肺组织MDA的含量显著低于ALI组。结论：抑制肺组织cPLA₂的磷酸化并对抗脂质过氧化损伤可能是Ber防治小鼠脂多糖性肺损伤的重要机制。     

联合应用氨溴索与小剂量肝素对急性肺损伤ICAM-1和EP-selectin的影响

目的: 制作急性肺损伤(ALI)模型并检测细胞间黏附分子-1(ICAM-1)、E-选择素和P-选择素在实验兔血清、肺组织及支气管肺泡灌洗液(BALF)中的变化情况以探讨三者在ALI中的作用并观察联合应用氨溴索与小剂量肝素对其的影响。方法: 24只健康兔随机分成3组:对照组(NC组),油酸损伤组(OA组),氨溴索＋小剂量肝素治疗组(AH组)。采用耳缘静脉法静注油酸复制兔ALI模型,检测各组动脉氧分压(PaO₂),ELISA法检测ICAM-1和E-选择素,TUNEL法检测凋亡指数(AI),免疫组化检测P-选择素,电镜观察肺组织超微结构变化并测定湿干重比值(W/D)。结果: 与NC组比较, OA组和AH组PaO₂显著降低(P<0.01),但AH组显著高于OA组(P<0.01); ICAM-1、E-选择素的浓度(血清、肺组织及BALF中)、肺组织AI和W/D升高(P<0.05或P<0.01),但AH组低于OA组(P<0.05或P<0.01)。与同组给予治疗药物前0 h比较,NC组无差异(P>0.05),OA组各时点PaO₂显著降低(P<0.01),ICAM-1和E-选择素浓度显著升高(P<0.01),AH组各时点PaO₂降低(P<0.05)、ICAM-1和E-选择素浓度升高(P<0.05)。肺组织中P-选择素在OA组表达较为广泛:主要为炎症细胞、毛细血管的内皮细胞和血管内的血浆等,NC组呈低水平表达,AH组的表达介于两者之间。细胞凋亡以OA组最为明显,NC组未见细胞凋亡或偶有凋亡,AH组凋亡的细胞明显比OA组减少。结论: 在OA致ALI时,ICAM-1、E-选择素和P-选择素明显增高,参与了ALI的发生、发展;联合应用氨溴索与小剂量肝素可以降低ICAM-1、E-选择素和P-选择素的水平,减轻肺脏细胞的损伤、改善肺通气和换气功能、减轻肺水肿,从而发挥对ALI的防治作用。     

槲皮素对LPS诱导中性粒细胞活性化效应的抑制作用

目的研究槲皮素(Quercetin,Que)对细菌脂多糖(Lipopolysaccharide,LPS)诱导的中性粒细胞(Polymorphonuclear,PMN)活化效应的影响。方法运用免疫荧光法和流式细胞术,对接受1h LPS刺激的PMN表面黏附分子(CD62L,CD11b／CD18)的表达进行测定,同时应用MTT法对不同状态下的PMN活性进行测定。结果Que对LPS诱导的中性粒细胞活化效应有明显抑制作用,表现为抑制细胞表面黏附分子CD62L的表达和促进CD11b／CD18的表达,同时Que对LPS增加细胞活性的效应有抑制作用。结论槲皮素通过对抗LPS对PMN黏附分子CD62L,CD11b／CD18的表达的影响,抑制LPS诱导的中性粒细胞活化效应,从而阻止PMN对血管内皮细胞的黏附,减少炎症细胞向炎症局灶的浸润,这可能是槲皮素发挥抗炎作用的一个重要机制。     

牛磺酸对大鼠肢体缺血再灌注后肺损伤时黏附分子ICAM-1表达的影响

目的：探讨牛磺酸对大鼠肢体缺血再灌注致肺损伤时黏附分子ICAM-1表达的影响。方法：复制大鼠肢体缺血再灌注(LIR)损伤模型,采用流式细胞技术、逆转录聚合酶链反应（RT-PCR）和Western blotting观察LIR后肺损伤发生过程中，血液中CD18阳性的多形核白细胞（PMN）百分率、肺系数（LI）与肺通透指数（LPI）、肺组织形态学的改变、肺组织ICAM-1 在mRNA和蛋白水平的变化及牛磺酸对上述指标的影响。结果：大鼠肢体缺血再灌注后LI、LPI及CD18阳性细胞数均明显增加，肺组织髓过氧化物酶（MPO）活性增加，ICAM-1表达明显升高，而提前给予牛磺酸可以明显抑制这些变化，从而对肺起一定保护作用。结论： 肺组织细胞ICAM-1表达上调及血液中CD18阳性细胞数的增加可能参与LIR后肺损伤的发生；牛磺酸可减少血液中CD18阳性细胞数，并且下调肺组织ICAM-1的表达，从而减轻肺损伤。     

抗巨噬细胞移动抑制因子抗体在油酸致急性肺损伤发病中的干预作用

目的:探讨抗巨噬细胞移动抑制因子单克隆抗体(anti-MIFMAb)在油酸诱导的大鼠急性肺损伤(ALI)中的干预作用,及其对巨噬细胞移动抑制因子(MIF)和细胞间粘附分子-1(ICAM-1)表达的影响。方法:雄性Wistar大鼠静脉注射油酸复制ALI为油酸组,静脉注射生理盐水为对照组,大鼠先给予抗-MIF单抗腹腔注射后再给予油酸静脉注射为抗-MIF单抗干预组。静注后4h,3组大鼠分别测定动脉血氧分压(PaO₂),肺泡通透指数等肺损伤指标;用ELISA法测定支气管肺泡灌洗液(BALF)中可溶性细胞间粘附分子-1(sICAM-1)水平;用原位杂交检测MIF和ICAM-1mRNA表达水平;用免疫组化双重套染方法检测巨噬细胞浸润程度与MIF表达的关系。结果:油酸组PaO₂低于对照组和干预组,肺通透性指数高于对照组和干预组(P<0.01),BALF中sICAM-1水平显著高于对照组和干预组(P<0.01)。油酸组肺组织MIF和ICAM-1表达明显高于对照组和干预组(P<0.01),经抗-MIF单抗干预ICAM-1表达变化不明显,但MIF表达显著下调,巨噬细胞浸润减少且肺损伤指标改善。结论:MIF和ICAM-1在介导巨噬细胞对组织的粘附、浸润和ALI的发生发展中起重要作用,抗-MIF单抗主要通过阻断MIF表达,减少巨噬细胞浸润而起肺保护作用。     

hUCB-MSCs对TBI大鼠神经炎症的影响

目的探讨人脐血间充质干细胞(h UCB-MSCs)移植对大鼠创伤性脑损伤(TBI)模型炎性细胞分泌的调节及脑保护作用机制。方法将用Brdu标记的h UCB-MSCs经鼠尾静脉植入大鼠TBI模型。检测和比较假伤组、损伤组和移植组大鼠血清细胞黏附分子-1(ICAM-1)含量、白细胞计数(WBC)及多形核嗜中性白细胞(PMN)计数及脑组织髓过氧化物酶(MPO)活性的改变。结果与假伤组相比,TBI模型大鼠血ICAM-1、WBC及PMN计数、脑组织MPO活性明显增加。h UCB-MSCs移植后各时间点上述指标表达较损伤组减低;至注射后7 d,移植组血ICAM-1、WBC及PMN计数已接近假伤组水平,脑组织MPO表达仍高于假伤组水平(P0.05)。经相关性分析,s ICAM-1与外周血PMN计数、白细胞计数与PMN计数、PMN计数与MPO活性表达均呈正相关。结论经尾静脉注射h UCB-MSCs能有效促进脑组织损伤的修复,其机制可能与减少血ICAM-1、WBC及PMN的数量、抑制脑组织MPO的分泌有关。     

实验性急性肺损伤肺组织中细胞间粘附分子的表达及大黄对其影响

目的:主要探讨肺组织中细胞间粘附分子-1(ICAM-1mRNA)表达与急性肺损伤(ALI)的关系和大黄对其影响。方法:注射脂多糖(LPS)复制ALI动物模型并分为LPS组、对照组、大黄+LPS组、地塞米松+LPS组。观察病理形态和ALI生物学标志并测定肺组织中ICAM-1mRNA的表达。结果:肺血管内皮细胞ICAM-1mRNA表达在LPS组显著高于对照组(P＜0.01),而大黄+LPS和地塞米松+LPS组显著弱于LPS组(P＜0.05,P＜0.01)。肺湿/干重比,肺泡灌洗液中性粒细胞比、蛋白含量以及肺血管壁通透性、肺泡通透指数也显著小于LPS组。结论:在ALI肺组织中ICAM-1mRNA表达增强参与了ALI发病的作用,大黄可使ICAM-1mRNA的表达减弱从而使肺组织损伤减轻。     

同型半胱氨酸增强血白细胞粘附分子的表达

用免疫荧光流式细胞仪检测同型半胱氨酸是否改变体外健康人血单核细胞,中性粒细胞,及淋巴细胞表达粘附分子CD11b,CD18和L－选择素（L-selectin)的表达。结果显示,同型半胱氨酸在低浓度20μmol/L时明显增加CD11b和CD18在各种白细胞表面的表达,同时也增加了CD14在单核及中性粒细胞的表达。这种作用随同型半胱氨酸浓度升高而增强,但当浓度升至等于或大于1mmol/L时,各种粘附分子的表达反而降低。同型半胱氨酸使各种细胞类型表面L-selectin降低。此结果表明同型半胱氨酸可改变白细胞表面粘附分子的表达,可能在体内通过此途径导致白细胞粘附并游出血管内皮。     

Difference in the Blood Monocyte Phenotype Between Uremic Patients and Healthy Controls: Its Relation to Monocyte Differentiation into Macrophages in the Peritoneal Cavity

The phenotypic alterations between blood monocytes from 11 patients with end-stage renal disease, who had been on peritoneal dialysis for less than one week, and blood monocytes from 10 healthy controls, were analyzed. In addition, peritoneal macrophages in the dialysate effluent were enclosed. Analysis of functional receptor density was performed using immunostaining and flow cytometry. The phenotypic characterization was selected to represent various biological functions such as adhesion, phagocytosis (CD11b/CD18, CD11c/CD18, CD16), antigen-presentation (HLA-DR, ICAM-1), differentiation (transferrin receptor, CD71), receptor for LPS (CD14) and initiation of the coagulation cascade (Tissue factor, CD142). The proportion of CD16-positive blood monocytes and the quantitative level of ICAM-1 were higher in the patient group, compared to healthy controls. A significant increase in the quantitative level of CD11b/CD18, CD11c/CD18, HLA-DR and ICAM-1, transferrin receptor, CD 14 and CD 16, was found on peritoneal macrophages, compared to monocytes, harvested both from the corresponding patients, as well as from healthy donors. In contrast, we did not find any significant differences in the expression of tissue factor between monocytes and peritoneal macrophages. In conclusion, phenotypic differences exist between monocyte populations in the blood circulation of CAPD patients, and healthy individuals. We also show that transmigration of monocytes into the peritoneal cavity implies a selective up-regulation of functional receptors, preferentially related to adhesion, and antigen-presentation in a steady-state situation in non-infected CAPD patients.     

Upregulation of adhesion molecules induced by broncho-vaxom on phagocytic cells.

Whole blood was incubated with the bacterial extract Broncho-Vaxom (OM85) at various concentrations and for different periods of time. Expression of the beta 2-integrins (LFA-1, CD11a/CD18; MAC-1, CD11b/CD18; p150,95, CD11c/CD18) and ICAM-1 (CD54) by monocytes and granulocytes was studied using flow cytometry. OM85 enhanced the expression of MAC-1 and ICAM-1 on monocytes and granulocytes in a dose-dependent manner. Maximal expression was achieved with 1 mg/ml bacterial extract. The effect on MAC-1 expression was not due to the low concentration of endotoxin contaminating the preparation (less than 1 ng/mg) since polymyxin-B did not substantially affect the adhesion molecule upregulation induced by OM85. In addition, OM85 enhanced the expression of p150,95 on monocytes and granulocytes, and also increased expression of LFA-1 on monocytes, but not on granulocytes. While MAC-1 and p150,95 expression reached peak values between 1 and 6 h, levels of ICAM-1 rose constantly for 10 h. We suggest that the clinical interest of OM85 in the management of recurrent infections could be related to be upregulation of adhesion molecules induced by this bacterial extract.     

CD11b Expression on circulating leukocytes increases in preparation for parturition

PROBLEM: Initiation of parturition is associated with migration of leukocytes to the reproductive tract. This migration is controlled in part by expression of adhesion molecules on the surface of leukocytes and vascular endothelial cells. Within the reproductive tract, certain endothelial adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), are up-regulated at the end of gestation. ICAM-1 binds to the beta(2) integrin CD11b on the leukocytes. In this study, we wanted to investigate whether complementary changes occur in expression of adhesion molecules on maternal leukocytes in preparation for parturition. METHOD OF STUDY: We used flow cytometry to ascertain changes in adhesion molecules expression on leukocytes throughout third trimester and labor. RESULTS: We found a significant increase in the expression of CD11b on monocytes and granulocytes in women at >37 weeks of gestation. CONCLUSIONS: CD11b may be a key molecule for leukocyte trafficking to the reproductive tract at the end of pregnancy.     

Short exposure of intestinal epithelial cells to TNF-alpha and histamine induces Mac-1-mediated neutrophil adhesion independent of protein synthesis.

Neutrophils play an important role in intestinal inflammation by interacting with intestinal epithelial cells. In this study, we evaluated neutrophil adhesion to intestinal epithelial cells using intestinal epithelial cell line HT29 stimulated with tumor necrosis factor alpha (TNF-alpha) and histamine for a short time (30 min). The TNF-alpha and histamine stimulation markedly increased neutrophil adhesion. The increased adhesion was inhibited by anti-CD11b and anti-CD18 monoclonal antibodies (mAbs), but not by anti-CD11a and anti-CD54 (ICAM-1) mAbs. It is interesting that flow cytometric analysis revealed that ICAM-1 expression on HT29 cells was not changed by TNF-alpha and histamine stimulation. Moreover, the increased adhesion was inhibited by proteinase K treatment but not cycloheximide treatment of HT29 cells. Together these observations suggest that short exposure of HT29 cells to TNF-alpha and histamine induces CD11b/CD18 (Mac-1)-dependent but CD11a/CD18 (LFA-1)-independent neutrophil adhesion to intestinal epithelial cells, and ICAM-1 is not likely to be involved in the interactions. Furthermore, epithelial cell ligand(s) for neutrophils is likely protein molecule(s) that is expressed on the cell by stimulation independent protein synthesis. However, it is also possible that neutrophil activating factor(s), which stimulates neutrophils to bind with epithelial ligands via Mac-1, is expressed by epithelial cells during stimulation.     

Systemic upregulation of leukocyte integrins in response to lower body ischemia-reperfusion during abdominal aortic aneurysm repair

Ischemia and reperfusion in myocardial infarction and stroke are associated with upregulation of leukocyte adhesion molecules, which contributes to tissue injury by facilitating leukocyte adhesion and infiltration in the affected tissues. Surgical repair of the abdominal aortic aneurysm involves clamping and declamping of the aorta, which necessarily results in ischemia and reperfusion of the lower half of the body. Given the large volume of the affected tissues and unimpeded venous return during reperfusion, we hypothesized that the procedure may result in upregulation of leukocyte integrins in the systemic circulation. To test this hypothesis, we studied neutrophil and monocyte surface densities of CD11b and CD18 in patients undergoing elective infrarenal abdominal aortic aneurysm repair. Serial blood samples were collected from the radial artery and femoral vein during the operation and leukocyte CD11b and CD18 surface densities were quantified by flow cytometry. Following reperfusion, CD11b expression in neutrophils and monocytes increased significantly in femoral venous and arterial blood. The mean time to peak expression of CD11 b in neutrophils and monocytes during reperfusion was 34.4 and 31.4 minutes in venous and 38.5 and 36.4 minutes in arterial blood, respectively. Similar rises in CD18 expression on neutrophils and monocytes were observed in venous and arterial blood. The mean time to peak expression of CD18 in neutrophils and monocytes during reperfusion was 34.0 and 40.0 minutes in venous and 47.5 and 50.0 minutes in arterial blood, respectively.     

Increased CD11b expression on polymorphonuclear leucocytes and cytokine profiles in patients with Kawasaki disease

Clinical evidence implicates polymorphonuclear leucocytes in the pathogenesis of vasculitis in Kawasaki disease. We examined modulation of expression of adhesion molecules (CD11b and CD62L) on polymorphonuclear leucocytes and how this expression is related to serum cytokine concentrations. In 18 patients with Kawasaki disease and 15 control subjects, adhesion molecule expression was determined by two-colour immunofluorescence staining of blood leucocytes and flow cytometry. Eight cytokines and chemokines were also measured. In patients with Kawasaki disease, mean fluorescence intensity for CD11b before giving intravenous immunoglobulin was significantly higher than in normal subjects (P<0 x 005). After intravenous immunoglobulin, mean fluorescence intensity for CD11b decreased significantly. With coronary artery lesions present, mean CD11b fluorescence intensity was significantly higher than without coronary artery lesions (P=0 x 005 before intravenous immunoglobulin; P=0 x 024 after intravenous immunoglobulin). No differences were seen in CD62L expression on polymorphonuclear leucocytes between patients with Kawasaki disease and normal subjects. CD11b expression on polymorphonuclear leucocytes correlated positively with serum interleukin (IL)-6, IL-10, granulocyte colony-stimulating factor, percentage of neutrophils among white cells and C-reactive protein. Polymorphonuclear leucocytes from patients with Kawasaki disease showed increased CD11b expression, which was associated with increased serum cytokines and appeared to be related to coronary artery lesions.     

Inefficiency of C3H/HeN Mice to Control Chlamydial Lung Infection Correlates with Downregulation of Neutrophil Activation during the Late Stage of Infection

We previously reported that massive infiltration of neutrophils in C3H/HeN （C3H） mice could not efficiently control Chlamydia muridarum （Cm） infection and might contribute to the high susceptibility of these mice to lung infection. To further define the nature of neutrophil responses in C3H mice during chlamydial infection, we examine the expression of adhesion molecules and CDllb related to neutrophils infiltration and activation, respectively, following intranasal Cm infection. The results showed that the expression of selectins （E-selectin, P-selectin and L-selectin）, and intercellular cell adhesion molecule-1 （ICAM-1） in the lung of C3H mice increased more significantly than in C57BL/6 （B6） mice, the more resistant strain. These results correlated well with the massive neutrophils infiltration in C3H mice. In contrast, CDllb expression on peripheral blood and lung neutrophils in C3H mice exhibited a significant reduction compared with B6 mice during the late phage of infection （day 14）. These findings suggest that the high-level expression of adhesion molecules in C3H mice may enhance neutrophils recruitment to the lung, but the decline of CDllb expression on neutrophils may attenuate neutrophil function. Therefore, CDllb down-regulation on neutrophils may contribute to the failure of C3H mice to control chlamydial lung infection.     

Exposure of intestinal epithelial cell HT29 to bile acids and ammonia enhances Mac-1-mediated neutrophil adhesion

OBJECTIVE: Bile acids and ammonia (NH3/NH4+) are cytotoxic metabolic products, which are known to influence intestinal epithelial functions such as colonic chloride secretion. In this study, we have investigated the effect of bile acids and ammonia on neutrophil-intestinal epithelial adhesive interaction. MATERIALS AND METHODS: Confluently cultured HT29 cells were treated with bile acids or ammonium chloride. Then, 51Cr-labeled neutrophils were added to HT29 cell monolayers, and neutrophil adhesion was assessed by gamma-scintillation counting. RESULTS: Treatment of HT29 cells with 0.1 mM CDCA (chenodeoxycholic acid), DCA (deoxycholic acid), CA (cholic acid) or ammonium chloride but not UDCA (ursodeoxycholic acid) for 30 min increased neutrophil adhesion about 4-folds (p<0.01). The increased adhesion was inhibited 82-91% by 10 microg/ml anti-CD11b and anti-CD18 mAbs (p<0.01), but not by anti-CD11a and anti-CD54 (ICAM-1) mAbs. Interestingly, flow cytometric analysis revealed that ICAM-1 expression on HT29 cells was not changed by bile acid- or ammonia-treatment. In addition, the increased adhesion was inhibited about 65 % by proteinase K-treatment (10 microg/ml, 1 min, p<0.05) but not cycloheximide-treatment (1 microg/ml, 30 min) of HT29 cells. CONCLUSIONS: These observations indicate that exposure of HT29 cells to bile acids or ammonia induces CD11b/CD18 (Mac-1) dependent- but CD11a/CD18 (LFA-1) independent-neutrophil adhesion to intestinal epithelial cells, and ICAM-1 is unlikely involved in the interactions. Furthermore, epithelial ligand(s) for neutrophils are protein molecule(s) which are expressed on the cell surface independent of protein synthesis.