Proinflammatory cytokines and endotoxin stimulate ICAM-1 gene expression and secretion by normal human hepatocytes.

Hepatocytes in normal tissues express low or undetectable levels of intercellular adhesion molecule-1 (ICAM-1), as detected by immunohistochemistry. Up-regulation of ICAM-1 expression on these cells has been reported in inflammatory liver disease (hepatitis B virus infection, autoimmune liver disorders and liver allograft rejection), and the molecule has been implicated in the recruitment, retention and activation of inflammatory cells. There is, however, little information concerning the regulation of hepatocyte expression of ICAM-1. We show here, for the first time, the induction (within 30 min) of ICAM-1 gene expression in cultured normal human hepatocytes stimulated with interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma) or endotoxin. IFN-gamma was the most potent single inducer (up to fourfold at 6 hr), while further induction of ICAM-1 mRNA was achieved with cytokine combinations. Maximal mRNA expression was achieved within 10 hr. ICAM-1 could be detected readily by immunocytochemical staining on the hepatocyte surface by 12 hr, and by enzyme immunoassay in the culture medium by 24 hr. The data present clear evidence that cytokines, which have been implicated previously in inflammatory liver diseases, can up-regulate directly both ICAM-1 gene expression and protein secretion/shedding by human hepatocytes.     

细胞因子诱导HepG2细胞ICAM—1表达的研究

目的 研究IFN-γ、TNF-a和IL-1对HepG2细胞细胞间粘附分子-1（ICAM-1）表达的影响。方法 用IFN-γ、TNF-a和IL-1在体外诱导HepG2细胞表达ICAM-1,并用细胞FLISA检测HepG2细胞ICAM-1表达水平。结果 未经刺激的HepG2细胞ICAM-1表达水平很低。TNF-a、IL-1、IFN-γ刺激后,HepG2细胞ICAM-1表达均明显增强,其表达水平与细胞因子浓度呈一定的剂量依赖关系;随着细胞因子刺激时间的延长,HepG2细胞ICAM-1表达也逐渐增多。结论IFN-γ、TNF-a和IL-1等细胞因子能诱导体外培养HepG2细胞ICAM-1增强表达。     

Activation by interferon-gamma of expression of ICAM-1 and MHC class II antigens in tumour cells from colorectal carcinomas

Aims-To determine whether lack of MHC class II antigen and intercellular adhesion molecule-1 (ICAM-1) expression in some tumours is due to the inability of the tumour cells to respond to the cytokine interferon-gamma (IFN-gamma), an important activator of these surface molecules.Methods-Cells from 40 colorectal tumours which did not constitutively express class II MHC antigens or ICAM-1 were kept in short term culture after disaggregation for a few days to two weeks without significant loss of viability. These were treated with IFN-gamma. Expression of class II MHC antigens and ICAM-1 was determined using immunohistological techniques.Results-There was clear induction in vitro of both MHC class II antigens and ICAM-1 in cells from eight of the tumours, with between 50 and 80% of the tumour cells in the cultures staining positively. The staining was apparent within 24 hours, appeared maximal at about three days, and declined thereafter. There were no obvious differences in cell morphology or viability between the cultures which were inducible and those which were not, nor were there obvious differences between the tumours from which they were derived.Conclusions-Expression of MHC class II antigens and ICAM-1 may be induced by IFN-gamma in a small proportion of colorectal tumours which do not constitutively express these antigens, showing that only a minority of tumours are capable of responding to this cytokine.     

Activation by interferon-γ of expression of ICAM-1 and MHC class II antigens in tumour cells from colorectal carcinomas

Aims—To determine whether lack of MHC class II antigen and intercellular adhesion molecule-1 (ICAM-1) expression in some tumours is due to the inability of the tumour cells to respond to the cytokine interferon-γ (IFN-γ), an important activator of these surface molecules.     

Abnormal expression of MHC class II and ICAM-1 by melanocytes in vitiligo

The relationship between damage to cutaneous melanocytes and antimelanocyte autoimmunity in vitiligo is unclear. We have demonstrated abnormal expression of MHC class II molecules by perilesional melanocytes in 13/21 patients with vitiligo and a six-fold increase in the number expressing the intercellular adhesion molecule ICAM-1. These molecules have important roles in normal antigen presentation and activation of helper T lymphocytes, and their expression by melanocytes may contribute to the abnormal immune response in vitiligo. MHC class II is not expressed by melanocytes in psoriasis and is unlikely to be induced in vitiligo by cytokines released from activated non-melanocyte-specific T lymphocytes.     

The expression of MHC antigens by human teratocarcinoma derived cell lines

We have used flow microflourimetry to investigate quantitatively the expression of HLA-A, B and C antigens, and β₂ microglobulin, by cell lines derived from human teratocarcinomas. Although low levels of these cell surface molecules were expressed by all the lines examined, there was no evidence of discrete HLA-A, B, C/β₂-microglobulin positive and negative subpopulations in any cultures. In contrast, using similar techniques, no murine embryonal carcinoma cell line was found to express the homologous H-2 antigens. It is suggested that human embryonal carcinoma cells may differ from their mouse counterparts by expressing low levels of major histocompatibility antigens.     

The expression of MHC antigens on cultured oral keratinocytes and relationship to malignancy.

Major histocompatibility complex (MHC) antigen expression has been postulated to have an important role in host defences against tumour development. In this study the expression of MHC class I and class II antigens in vitro, both constitutive and in response to interferon gamma (IFN gamma), was examined in a series of cell lines established from a rat model of oral carcinogenesis. Constitutive expression of MHC class I and class II antigens was not related to the degree of malignancy of the cell lines, as reflected by their anchorage independence in agarose gels and their capacity to form tumours in athymic mice. MHC class I response to IFN gamma stimulation did not correlate with tumorigenicity, but the MHC class II response was significantly decreased in one of the four tumorigenic cell lines. The results show that the expression of MHC antigens in response to IFN gamma varied between different keratinocyte cell lines but did not consistently reflect the tumorigenic phenotype.     

Induction of ICAM-1 expression on human airway epithelial cells by inflammatory cytokines: effects on neutrophil-epithelial cell adhesion.

Inflammation of the human airways in diseases such as chronic bronchitis, cystic fibrosis with Pseudomonas endobronchial infection, and possibly asthma during late-phase reactions involves a local influx of neutrophils (PMN) that may participate in airway epithelial injury. PMN-mediated cellular injury is most efficient under conditions of PMN-target cell adhesion. PMN express adhesive glycoproteins of the CD11/CD18 family that are counter-receptors for intercellular adhesion molecule-1 (ICAM-1), found on various cell types. We proposed that adherence by PMN to human airway epithelial cells via ICAM-1 might be an important mechanism in inflammatory airway diseases. We found that although PMN adhere poorly (less than 5%) to monolayers of human tracheal epithelial cells (TEC) in primary culture, they adhere readily (45 to 50%) to an SV40-immortalized line of human TEC, designated 9HTEo-. We also found 6-fold greater surface expression of ICAM-1 on 9HTEo- compared with primary TEC. Blocking surface ICAM-1 on 9HTEo- cells with specific monoclonal antibody inhibited PMN adherence by about 50%. Thus, ICAM-1 plays a major role in this adherence, although it is possible that other epithelial ligands contribute also. Antibodies to CD11a, CD11b, and CD18 on PMN also inhibited PMN-epithelial adherence. Treatment of primary TEC monolayers with the proinflammatory cytokines interleukin-1 (IL-1) or tumor necrosis factor-alpha (TNF-alpha) caused a 3- to 4-fold increase in both cell surface ICAM-1 expression and support of PMN adhesion.(ABSTRACT TRUNCATED AT 250 WORDS)     

The expression of MHC antigens on cultured oral keratinocytes and relationship to malignancy

Major histocompatibility complex (MHC) antigen expression has been postulated to have an important role in host defences against tumour development. In this study the expression of MHC class I and class II antigens in vitro, both constitutive and in response to interferon gamma (IFN gamma), was examined in a series of cell lines established from a rat model of oral carcinogenesis. Constitutive expression of MHC class I and class II antigens was not related to the degree of malignancy of the cell lines, as reflected by their anchorage independence in agarose gels and their capacity to form tumours in athymic mice. MHC class I response to IFN gamma stimulation did not correlate with tumorigenicity, but the MHC class II response was significantly decreased in one of the four tumorigenic cell lines. The results show that the expression of MHC antigens in response to IFN gamma varied between different keratinocyte cell lines but did not consistently reflect the tumorigenic phenotype.     

The effect of fluid shear stress on ICAM-1 expression of rat brain microvascular endothelial cells.

Intercellular adhesion molecule-1 (ICAM-1) is an adherence molecule that is an important factor in many pathophysiological processes such as atherosclerosis, thrombosis and inflammation. It is secretion of endothelial cells by a variety of biochemical stimulations. But hemodynamic forces can also induce various functional changes in vascular endothelium. Some researches have proved that shear stress can modulate the expression of ICAM-1. But most of them examine the regulation of expression of ICAM-1 in human umbilical vein endothelial cells. There is no detail on the effect of shear stress (SS) on ICAM-1 expression of microvascular endothelial cells (RBMECs). In this experiment, we use cultured rat brain microvascular endothelial cells (RBMECs). By using the parallel plate flow chamber method, we give two magnitudes of lamminar shear stresses (0.2 dyn/cm2, 0.4 dyn/cm2) for different perieods of time on the slides of cells. Immunostaining method and image analysis shows a specific upregulation in ICAM-1 expression on RBMECs, which is different from endothelial cells of other species or vascular beds. Expression of ICAM-1 is increased 0.5h after the onset of SS, and reached its highest level 4h after onset of SS, then declines after that. The effect is time-dependent, not force magnitude-dependent. Endothelial cell surface expression of ICAM-1 in the supernatants of RBMECs exposed to SS was not modified excluding the possibility that RBMECs exposed to SS synthesize factors that upregulate ICAM-1. The experiment data are relevant to the current understanding of basic mechanisms that explain the signal transudation pathway occurring inside the endothelial cells under the effect of SS.     

Lymphocyte infiltration in oesophageal carcinoma: lack of correlation with MHC antigens,ICAM-1, and tumour stage and grade.

Infiltration by T lymphocytes into oesophageal carcinomas was assessed immunohistochemically, total T lymphocyte numbers by staining for CD3 and activated T lymphocytes by staining for CD25. Five squamous carcinomas and seven adenocarcinomas, resected without neoadjuvant treatment, were studied. Computer aided quantitation showed that total numbers of tumour infiltrating CD3 positive cells were highly variable (range 48-1673 cells/mm2). They were located largely in the stromal (87.9-99.2%) rather than intratumoral regions. Up to 84% of tumour infiltrating T lymphocytes were CD25 positive, although the median figure was 33%. There was no correlation between T lymphocyte infiltration or activation and expression of class I and II histocompatibility antigens, intercellular adhesion molecule-1, tumour stage or grade. These results imply that the local inflammatory response in oesophageal carcinomas is deregulated, which may be a factor contributing to the aggressive nature of the tumours.     

人白介素- 4对牛血管内皮细胞保护作用的研究

目的:研究人白介素-4(hIL-4)对经TNF-α活化的牛主动脉内皮细胞(BAEC)的保护作用。方法:用不同浓度的hIL-4与BAEC共孵育2h后,再与4μg/L的TNF-α共孵育6h或18h。应用细胞ELISA方法,检测BAEC表面的E选择素和ICAM-1的表达;用MTT比色法测定hIL-4对BAEC活性的影响。结果:在一定浓度内用hIL-4预处理BAEC后,能明显抑制TNF-α诱导活化BAEC上的E选择素与ICAM-1的表达,并呈现一定的剂量依赖性。用MTT比色法测定BAEC活性的实验表明,各实验组BAEC的活性与对照组无明显差异性。结论:hIL-4能明显抑制TNF-α诱导活化的BAEC表达E选择素与ICAM-1;hIL-4对BAEC的正常功能具有一定的保护作用。     

CIITA M1-RNA抑制HeLa细胞表面MHC II类抗原的表达

探讨MHC II类转录激活因子(CIITA)的M1-RNA对细胞表面MHC II类分子表达的抑制。M1-RNA是核糖核酸酶P的催化活性单位,设计并克隆针对CIITA第452、629位点的M1-RNA(分别为M1-452-GS、M1-629-GS)及其相应的CIITA靶基因,分别插入pUC19、pGEM-7zf(+)载体,进行细胞外切割活性筛选。将细胞外切割作用明显的M1-629-GS亚克隆入psNAV载体(psNAV-M1-629-GS,pA629)并稳定转染HeLa细胞株,流式细胞术检测经典的MHC II类抗原(HLA-DR、-DP、-DQ)的表达,RT-PCR检测CIITA的mRNA水平。在重组人γ干扰素诱导下,pA629阳性HeLa细胞株表面HLA-DR、-DP抗原表达分别降低了83.03%及89.91%;同时CIITA的mRNA含量明显减少(P<0.05)。CIITA的M1-RNA抑制了自身mRNA含量,从而阻止其调控的MHC II类分子的表达,为移植物抗宿主病的研究提供了一种新方法。     

Effects of 1 alpha,25-dihydroxyvitamin D3 and cytokines on the expression of MHC antigens, complement receptors and other antigens on human blood monocytes and U937 cells: role in cell differentiation, activation and phagocytosis.

The effect of calcitriol/1 alpha,25-dihydroxyvitamin D3, alone and in combination with cytokines, on the expression of various antigens (Ag) on human peripheral blood monocytes and U937 cells was studied by flow cytometry. Both constitutive and interferon-gamma (IFN-gamma), interleukin-4 (IL-4), IL-6 and tumour necrosis factor-alpha (TNF-alpha)-induced human leucocyte antigen (HLA)-DR, HLA-DP and HLA-DQ Ag expression on monocytes was significantly down-regulated by calcitriol, IL-10 and transforming growth factor-beta (TGF-beta). The effects of calcitriol were concentration dependent and reached maximal inhibitory levels after 3-5 days. Modulation of HLA-DR by calcitriol and IFN-gamma at the protein level correlated with the amount of mRNA specific for the HLA-DR alpha-chain, as judged by Northern blot analysis. The basal as well as IL-4, IL-6, IFN-gamma, TNF-alpha and TGF-beta-driven levels of HLA-ABC Ag were significantly diminished by calcitriol. On U937 cells calcitriol markedly induced CD11a and CD11b expression and weakly up-regulated CD11c whereas on monocytes, constitutive CD11a, CD11b and CD11c expression was significantly down-regulated by calcitriol. The expression of CD14 Ag was strongly induced on U937 cells but only modestly on monocytes. Both the basal level of CD71 and IL-4, IFN-gamma or TNF-alpha-driven expression was diminished on calcitriol-treated U937 cells. In addition, calcitriol suppressed the expression of CD71 Ag on monocytes. The ability of monocytes to phagocytize opsonized Escherichia coli was diminished by calcitriol. Our results demonstrate that calcitriol, alone or in combination with cytokines, modulates expression of MHC, CD11b, CD11c, CD14 and CD71 Ag on both monocytes and U937 cells, and impairs the phagocytic property of monocytes.     

泡球蚴原头蚴抗原和卡介苗对Th1/Th2转录因子和细胞因子的影响

目的探讨泡球蚴原头蚴抗原和卡介苗免疫小鼠对泡球蚴攻击感染的调节机制。方法用实时定量聚合酶链反应检测鼠脾组织中GATA-3及T-bet的mRNA表达水平;酶联免疫吸附法检测鼠血清中白介素4和γ干扰素的含量。结果卡介苗免疫攻击组与PBS对照组的转录因子(T-bet mRNA)和其标志性细胞因子(INF-γ)的表达量,差异有统计学意义(P<0.05)。结论实验证明卡介苗(BCG)有上调Th1型免疫反应的作用,用BCG可以干预或治疗由泡球蚴抗原诱导的晚期泡球蚴(AE)动物的免疫抑制状态。     

Apical topography and modulation of ICAM-1 expression on activated endothelium.

Leukocyte-endothelium interactions and general inflammatory responses are contributed by the regulated expression of intercellular adhesion molecule-1 (ICAM-1) on endothelium. It is now shown by confocal fluorescence microscopy and immunogold transmission electron microscopy that ICAM-1 was exclusively localized on the apical (luminal) membrane of cytokine-activated human umbilical vein endothelial cells. In contrast, other cell adhesion-promoting molecules, including beta 1 integrins, were expressed exclusively on the basolateral endothelial cell membrane, under the same experimental conditions. Kinetic binding studies of a 125I-labeled monoclonal antibody to ICAM-1 revealed that approximately 8% of membrane ICAM-1 on cytokine-activated endothelium was internalized in both coated and non-coated vesicles at 37 degrees C, with a t1/2 of approximately 18 min and a rate of approximately 3200 molecules/minute. This internalization pathway was directly dependent upon the level of ICAM-1 expression on the cell surface. Genetically engineered ICAM-1 transfectants, expressing a 10-fold higher receptor density than activated endothelium, internalized approximately 18% of membrane ICAM-1 at a rate of 75,000 molecules/minute with a t1/2 of approximately 22 min. These findings suggest that a combined pathway of polarized membrane topography and receptor trafficking may regulate ICAM-1-dependent adhesion at the site of vascular injury and endothelial cell activation.