A hot water extract of Curcuma longa inhibits adhesion molecule protein expression and monocyte adhesion to TNF-α-stimulated human endothelial cells

The recruitment of arterial leukocytes to endothelial cells is an important step in the progression of various inflammatory diseases. Therefore, its modulation is thought to be a prospective target for the prevention or treatment of such diseases. Adhesion molecules on endothelial cells are induced by proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), and contribute to the recruitment of leukocytes. In the present study, we investigated the effect of hot water extract of Curcuma longa (WEC) on the protein expression of adhesion molecules, monocyte adhesion induced by TNF-α in human umbilical vascular endothelial cells (HUVECs). Treatment of HUVECs with WEC significantly suppressed both TNF-α-induced protein expression of adhesion molecules and monocyte adhesion. WEC also suppressed phosphorylation and degradation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) induced by TNF-α in HUVECs, suggesting that WEC inhibits the NF-κB signaling pathway.     

Alterations in leucocyte trafficking in lupus-prone mice: an examination of the MRL/faslpr mouse

Systemic lupus erythematosus (SLE) is an autoimmune disease involving inappropriate inflammatory responses in a wide range of organs. The recruitment of leucocytes to these sites of inflammation is one of the key events in the development of tissue injury in SLE. However, the mechanisms responsible for this aberrant recruitment are poorly understood. Several studies have demonstrated upregulation of endothelial adhesion molecule expression in tissue biopsies from SLE patients. However, the progression to analysis of the functional roles of these adhesion molecules has entailed the use of animal models of SLE. Much of this work has involved the use of the MRL/faslpr mouse model of systemic autoimmune disease. This mouse develops a systemic inflammatory disease with similarities to human SLE. This review summarizes work by our laboratory and others which have examined alterations in the mechanisms of leucocyte trafficking in the MRL/faslpr mouse. These experiments have revealed upregulation of key adhesion molecules, alterations in leucocyte-endothelial cell interactions and in some cases protective effects of deletion of endothelial adhesion molecules. From analysis of a range of microvasculatures in the MRL/faslpr mouse, it is becoming clear that the roles of specific adhesion molecules vary according to the tissue under analysis. Furthermore, analysis of MRL/faslpr mice with targeted deletions of specific adhesion molecules indicates that their roles in development and progression of disease can vary from having key contributions to the development of disease, to attenuating disease via as yet unidentified mechanisms.     

Dynamic control of lymphocyte trafficking by fever-range thermal stress

Migration of blood-borne lymphocytes into tissues involves a tightly orchestrated sequence of adhesion events. Adhesion molecules and chemokine receptors on the surface of circulating lymphocytes initiate contact with specialized endothelial cells under hemodynamic shear prior to extravasation across the vascular barrier into tissues. Lymphocyte–endothelial adhesion occurs preferentially in high endothelial venules (HEV) of peripheral lymphoid organs. The continuous recirculation of naïve and central memory lymphocytes across lymph node and Peyer’s patch HEV underlies immune surveillance and immune homeostasis. Lymphocyte–endothelial interactions are markedly enhanced in HEV-like vessels of extralymphoid organs during physiological responses associated with acute and chronic inflammation. Similar adhesive mechanisms must be invoked for efficient trafficking of immune effector cells to tumor sites in order for the immune system to have an impact on tumor progression. Here we discuss recent evidence for the role of fever-range thermal stress in promoting lymphocyte–endothelial adhesion and trafficking across HEV in peripheral lymphoid organs. Findings are also presented that support the hypothesis that lymphocyte–endothelial interactions are limited within tumor microenvironments. Further understanding of the molecular mechanisms that dynamically promote lymphocyte trafficking in HEV may provide the basis for novel approaches to improve recruitment of immune effector cells to tumor sites.     

Molecular events during leukocyte diapedesis

The recruitment of leukocytes from the circulation into tissues requires leukocyte migration through the vascular endothelium. The mechanisms by which leukocytes attach and firmly adhere to the endothelial cell surface have been studied in detail. However, much less is known about the last step in this process, the diapedesis of leukocytes through the vascular endothelium. This minireview focuses on the interactions between leukocyte and endothelial cell adhesion molecules that are important during leukocyte extravasation. In the past few years a series of endothelial cell surface and adhesion molecules have been identified that are located at endothelial cell contacts and found to participate in leukocyte diapedesis. These junctional cell adhesion molecules are believed to have an active role in controlling the opening and closure of endothelial cell contacts to allow the passage of leukocytes between adjacent endothelial cells. Alternatively, leukocytes can cross the endothelium at nonjunctional locations, with leukocytes migrating through a single endothelial cell. Further work is clearly needed to understand, in greater detail, the molecular mechanisms that allow leukocytes to cross the endothelium via either the paracellular or the transcellular pathway.     

The role of junctional adhesion molecules in cell-cell interactions

Cell-cell-interactions are important for the regulation of tissue integrity, the generation of barriers between different tissues and body compartments thereby providing an effective defence against toxic or pathogenic agents, as well as for the regulation of inflammatory cell recruitment. Intercellular interactions are regulated by adhesion receptors on adjacent cells which upon extracellular ligand binding mediate intracellular signals. In the vasculature, neighbouring endothelial cells interact with each other through various adhesion molecules leading to the generation of junctional complexes like tight junctions (TJs) and adherens junctions (AJs) which regulate both leukocyte endothelial interactions and paracellular permeability. In this context, emerging evidence points to the importance of the family of junctional adhesion molecules (JAMs), which are localized in tight junctions of endothelial and epithelial cells and are implicated in the regulation of both leukocyte extravasation as well as junction formation and permeability.     

The angiostatic 16K human prolactin overcomes endothelial cell anergy and promotes leukocyte infiltration via nuclear factor-kappaB activation

The 16-kDa N-terminal fragment of human prolactin (16K hPRL) is a potent angiostatic factor that inhibits tumor growth in mouse models. Using microarray experiments, we have dissected how the endothelial-cell genome responds to 16K hPRL treatment. We found 216 genes that show regulation by 16K hPRL, of which a large proportion turned out to be associated with the process of immunity. 16K hPRL induces expression of various chemokines and endothelial adhesion molecules. These expressions, under the control of nuclear factor-kappaB, result in an enhanced leukocyte-endothelial cell interaction. Furthermore, analysis of B16-F10 tumor tissues reveals a higher expression of adhesion molecules (intercellular adhesion molecule 1, vascular cell adhesion molecule 1, or E-selectin) in endothelial cells and a significantly higher number of infiltrated leukocytes within the tumor treated with 16K hPRL compared with the untreated ones. In conclusion, this study describes a new antitumor mechanism of 16K hPRL. Because cellular immunity against tumor cells is a crucial step in therapy, the discovery that treatment with 16K hPRL overcomes tumor-induced anergy may become important for therapeutic perspectives.     

alpha-v-beta 3整合素与恶性肿瘤侵袭转移关系的研究进展

整合素家族是细胞粘附分子的重要种类之一,主要作用是介导细胞与细胞之间、细胞与细胞外基质之间的粘附效应。医学 研究证实整合素家族与肿瘤的侵袭及远处转移等生物学行为密切相关。整合素alpha-v-beta-3是整合素家族中的一种重要分子,肿瘤血管内 皮细胞中alpha-v-beta-3的表达水平对肿瘤侵袭转移及血管生成有着重要作用,调节琢v茁3的表达水平可明显影响肿瘤的侵袭转移及肿瘤组 织中新生血管的形成。深入研究整合素alpha-vbeta-3的分子调节机制可以为肿瘤治疗提供新的治疗靶点。     

New aspects of integrin-mediated leukocyte adhesion in inflammation: regulation by haemostatic factors and bacterial products

Leukocyte recruitment to sites of inflammation, infection or vascular injury is a complex event, depending on a tightly coordinated sequence of leukocyte-endothelial- and leukocyte-platelet interactions, which are controlled by the expression and activation of various adhesion receptors and protease systems. The present review will focus on novel aspects of the regulation of integrin-dependent leukocyte adhesion by haemostatic factors and bacterial products. In particular, after a short overview of leukocyte recruitment, the review (i) will focus on the crosstalk between haemostatic factors and adhesion molecules with respect to leukocyte extravasation based on the paradigms of the urokinase receptor and high molecular weight kininogen, (ii) will provide information on novel mechanisms for the regulation of leukocyte recruitment by bacterial proteins, on the basis of the anti-inflammatory role of Staphylococcus aureus extracellular adhesive protein and (iii) will draw attention to the junctional adhesion molecules, a novel family of adhesive receptors that are counter-receptors for leukocyte integrins and mediate vascular cell interactions. The better understanding of the interactions between vascular cells and particularly of integrin-dependent leukocyte adhesion may lead to the development of novel therapeutical concepts in inflammatory vascular disorders.     

Adhesion properties of adhesion-regulating molecule 1 protein on endothelial cells

Numerous adhesion molecules have been described, and the molecular mechanisms of lymphocyte trafficking across the endothelium is starting to be elucidated. Identification of the molecules involved in the organoselectivity of this process would help in the targeting of drug therapy to specific tissues. Adhesion-regulating molecule-1 (ARM-1) is an adhesion-regulating molecule previously identified on T cells. It does not belong to any known families of adhesion molecules. In this study, we show the presence of ARM-1 in endothelial cells, the adhesion partners of lymphocytes. ARM-1 mRNA was found to be differentially expressed in endothelial cell lines of various tissue origin and lymphocyte cell lines. Interestingly, ARM-1 is absent from skin endothelial cells. In our assay, skin endothelial cells display a distinct capacity to mediate adhesion of activated T lymphocytes. Overexpression of ARM-1 in skin endothelial cells increased adhesion of CEMT4 and NK lymphocytes, confirming that ARM-1 also regulates adhesion in endothelial cells. We also show that ARM-1 is a cytosolic protein associated with the plasma membrane. However, no cell surface expression of the protein was observed. These results suggest an indirect role of ARM-1 in adhesion rather than a direct role as an adhesion molecule itself.     

Interactions between leukocytes and endothelial cells in gout: lessons from a self-limiting inflammatory response

Interactions with endothelium are necessary for leukocytes to pass from the blood into extravascular tissues, and such interactions are facilitated in inflammation by the coordinated expression of endothelial adhesion molecules and chemoattractants. Although the general mechanisms and intracellular pathways of endothelial activation are now fairly well characterised in vitro, relatively little detailed information exists on how endothelial activation changes during the course of inflammatory responses and how such change influences the amount of leukocyte recruitment and the types of leukocytes recruited. Having developed a radiolabelled-antibody-uptake technique for quantifying the expression of endothelial adhesion molecules in relation to leukocyte trafficking, we have analysed the acute, self-limiting inflammatory response to injection of monosodium urate (MSU) crystals. Our studies have supported the view that endothelial activation is closely paralleled by leukocyte recruitment at the onset of the response and have highlighted separate vascular and extravascular stages of downregulation. More recent studies addressing the extravascular contribution to downregulation point to an important role for monocyte-macrophage differentiation in limiting further endothelial activation as a consequence of phagocytosis of MSU crystals.     

Nitric oxide modulates the expression of endothelial cell adhesion molecules involved in angiogenesis and leukocyte recruitment

Tumor angiogenesis and immune response have in common to be cell recognition mechanisms, which are based on specific adhesion molecules and dependent on nitric oxide (NO^•). The aim of the present study is to deepen the mechanisms of angiogenesis and inflammation regulation by NO^• to find out the molecular regulation processes that govern endothelial cell permeability and leukocyte transmigration.Effects of NO^•, either exogenous or produced in hypoxic conditions, were studied on microvascular endothelial cells from skin and lymph node because of their strong involvement in melanoma progression. We found that NO^• down-regulation of pseudo-vessel formation was linked to a decrease in endothelial cell ability to adhere to each other which can be explain, in part, by the inhibition of PECAM-1/CD31 expression. On the other hand, NO^• was shown to be able to decrease leukocyte adhesion on an endothelial monolayer, performed either in static or in rolling conditions, and to modulate differentially CD34, ICAM-1/CD54, ICAM-2/CD102 and VCAM-1/CD106 expression.In conclusion, during angiogenesis and leukocyte recruitment, NO^• regulates cell interactions by controlling adhesion molecule expression and subsequently cell adhesion. Moreover, each endothelial cell type presents its own organospecific response to NO^•, reflecting the functions of the tissue they originate from.     

Vimentin在肿瘤转移中的作用及药物研究进展

波形蛋白(vimentin)是存在于间充质细胞中的一种中间丝蛋白,近些年研究显示vimentin与肿瘤发生、转移密切相关。波形蛋白调节细胞骨架蛋白、细胞粘附分子等蛋白间的相互作用,参与肿瘤细胞和肿瘤相关内皮细胞、巨噬细胞的粘附、迁移、侵袭和细胞信号转导。其高度动态的聚合解聚间的平衡和其复杂的磷酸化形式可能是vimentin参与肿瘤转移过程及细胞-细胞间相互作用的调节机制。Vimentin在肿瘤中的功能提示,其可能是抗肿瘤转移治疗药物研究的新靶点。     

Mechanisms of selective leukocyte recruitment from whole blood on cytokine-activated endothelial cells under flow conditions

Selective recruitment of eosinophils to sites of allergic and parasitic inflammation involves specific adhesion and activation signals expressed on or presented by stimulated endothelial cells. Here we examined leukocyte recruitment on cytokine-activated HUVEC under flow conditions. We perfused whole blood through a flow chamber to examine mechanisms of selective leukocyte recruitment. Although there was substantial recruitment of leukocytes on TNF-alpha-stimulated HUVEC, we found no selective accumulation of any particular leukocyte subpopulations. In contrast, fewer leukocytes were recruited to IL-4-stimulated HUVEC, but the recruitment was selective for eosinophils. We examined the role of adhesion molecules in these interactions and found that eosinophil recruitment was completely blocked with an alpha4 integrin mAb at the shear rates examined. A significant number of neutrophils were also recruited to IL-4-stimulated HUVEC, and these interactions required P-selectin and P-selectin glycoprotein ligand-1. Thus, whole blood perfusion over cytokine-activated endothelium revealed that IL-4-stimulated HUVEC support selective recruitment of eosinophils, whereas TNF-alpha-stimulated HUVEC lack selectivity for any leukocyte subclass.     

Adhesion molecules and their role in cancer metastasis

This article describes various adhesion molecules and reviews evidence to support a mechanistic role for adhesion molecules in the process of cancer metastasis. A variety of evidence supports the involvement of specific adhesion molecules in metastasis.

1. For example, some cancer cells metastasize to specific organs, irrespective of the first organ encountered by the circulating cancer cells. This ability to colonize a specific organ has been correlated with the preferential adhesion of the cancer cells to endothelial cells derived from the target organ. This suggests that cancer cell/endothelial cell adhesion is involved in cancer cell metastasis and that adhesion molecules are expressed on the endothelium in an organ-specific manner.
2. Further, inclusion of peptides that inhibit cell adhesion, such as the YIGSR- or RGD-containing peptides, is capable of inhibiting experimental metastasis.
3. Metastasis can be enhanced by acute or chronic inflammation of target vessels, or by treatment of animals with inflammatory cytokines, such as interleukin-1. In vitro, cancer cell/endothelial cell adhesion can be enhanced by pretreating the endothelial cell monolayer with cytokines, such as interleukin-1 or tumor necrosis factor-α. This suggests that, in addition to organ-specific adhesion molecules, a population of inducible endothelial adhesion molecules is involved and is relevant to metastasis.
4. Further support for this model is found in the comparison to leukocyte/endothelial adhesion during leukocyte trafficking. Convincing evidence exists, both in vivo and in vitro, to demonstrate an absolute requirement for leukocyte/endothelial adhesion before leukocyte extravasation can occur. The relevance of this comparison to metastasis is reinforced by the observation that some of the adhesion molecules involved in leukocyte/endothelial adhesion are also implicated in cancer cell/endothelial adhesion. The involvement of adhesion molecules suggests a potential therapy for metastasis based on interrupting adhesive interactions that would augment other treatments for primary tumors.

     

Cyclosporine A enhances leukocyte binding by human intestinal microvascular endothelial cells through inhibition of p38 MAPK and iNOS. Paradoxical proinflammatory effect on the microvascular endothelium

The calcineurin inhibitor cyclosporine A (CsA) modulates leukocyte cytokine production but may also effect nonimmune cells, including microvascular endothelial cells, which regulate the inflammatory process through leukocyte recruitment. We hypothesized that CsA would promote a proinflammatory phenotype in human intestinal microvascular endothelial cells (HIMEC), by inhibiting inducible nitric-oxide synthase (iNOS, NOS2)-derived NO, normally an important mechanism in limiting endothelial activation and leukocyte adhesion. Primary cultures of HIMEC were used to assess CsA effects on endothelial activation, leukocyte interaction, and the expression of iNOS as well as cell adhesion molecules. CsA significantly increased leukocyte binding to activated HIMEC, but paradoxically decreased endothelial expression of cell adhesion molecules (E-selectin, intercellular adhesion molecule 1, and vascular cell adhesion molecule-1). In contrast, CsA completely inhibited the expression of iNOS in tumor necrosis factor-alpha/lipopolysaccharide-activated HIMEC. CsA blocked p38 MAPK phosphorylation in activated HIMEC, a key pathway in iNOS expression, but failed to inhibit NFkappaB activation. These studies demonstrate that CsA exerts a proinflammatory effect on HIMEC by blocking iNOS expression. CsA exerts a proinflammatory effect on the microvascular endothelium, and this drug-induced endothelial dysfunction may help explain its lack of efficacy in the long-term treatment of chronically active inflammatory bowel disease.     

The physiology of leukocyte recruitment: an in vivo perspective

The mechanisms of leukocyte recruitment have been studied extensively in vitro and have shed light on the basic molecular structure-function relationship of adhesion and signaling molecules involved in this essential immune response. This review will summarize how these in vitro observations extend to leukocyte behavior in inflamed blood vessels in the microcirculation. We highlight physiological results that might not have been predicted from in vitro systems. Special attention is placed on the physiology of rolling, adhesion, and intralumenal crawling in blood vessels. The importance of the glycocalyx, secondary tethers, shear, and the microenvironment are discussed. Docking structures forming rings of adhesion molecules together with a novel endothelial dome-like structure in vivo during transmigration are highlighted. Transcellular and paracellular emigration out of inflamed blood vessels is also discussed. The last section highlights leukocyte recruitment in some organs that do not always follow the accepted paradigm of leukocyte recruitment.     

Vascular adhesion and transendothelial migration of eosinophil leukocytes

Tissues respond to injury with inflammation in an effort to protect and repair the damaged site. During inflammation, leukocytes typically accumulate in response to certain chemicals produced within the tissue itself. The passage of leukocytes through the vascular lumen into tissues occurs in several phases, including rolling, activation, firm adhesion, transendothelial migration, and subendothelial migration. Although infiltration of eosinophil leukocytes is one of the most important aspects of allergic inflammatory reactions, eosinophils also participate in nonallergic inflammation. Eosinophil accumulation is regulated not only by endothelial adhesion molecules, but also by interactions between eosinophil adhesion molecules and extracellular matrix elements. This review summarizes the regulation of eosinophil leukocyte adhesion and migration. A better understanding of eosinophil recruitment responses may lead to the development of novel therapeutics for chronic allergic diseases.     

Mechanisms for reduction of endothelial activation by oleate: inhibition of nuclear factor-kappaB through antioxidant effects

In a model of early atherogenesis based on cultured endothelial cells, we observed that the incorporation of oleic acid in cellular lipids decreases the stimulated expression of several endothelial adhesion molecules and soluble products typically expressed during endothelial activation and involved in monocyte recruitment. We investigated possible mechanisms for this effect assessing the stimulated induction of nuclear factor-kappaB. In parallel, we also measured glutathione (GSH) content and the activity of antioxidant enzymes after oleate treatment and cytokine stimulation. Oleate prevented the stimulated depletion of GSH without any change in the activity of antioxidant enzymes. These results suggest an antioxidant mechanism by which oleate may exert direct vascular atheroprotective effects.