Altered expression of adhesion molecules in inflammatory cervical smears

Objective:  The aim of the present study was to evaluate the expression of pan-cadherin and β-catenin in cervical smears with various types of infectious agents.
Patients and Methods:  Cervical smears obtained from 53 women, aged 21–65 years, with a diagnosis of specific inflammation were examined in our study. Eighteen subjects were infected by Candida albicans , 18 by Gardnerella vaginalis , nine by Bacteroides spp. and eight by Chlamydia trachomatis . All infectious agents found in the smears were at the same time confirmed by the microbiological laboratory methods. We performed a biotin–streptavidin-peroxidase immunocytochemical method using anti-β-catenin (Clone 12F7) and anti-pan-cadherin (pan, polyclonal) antibodies.
Results:  Aberrant expression of pan-cadherin was found in the cytoplasmic membrane of glandular, metaplastic, superficial and intermediate squamous cells in all types of infections. With regard to β-catenin, this was expressed in majority (90%) of glandular and metaplastic cells in all types of infections and in a small proportion (15%) of superficial and intermediate squamous cells in infections caused by C. albicans and G . vaginalis .
Conclusion:  Our data show that infectious agents may cause alterations in the expression and distribution of these adhesive molecules, which can be recognized in cervical smears. Additional studies in larger sets of patients should help clarify this issue further.     

Prevention of neuronal cell death by neural adhesion molecules L1 and CHL1

The effects of L1-Fc and CHL1-Fc fusion proteins on neuronal survival were investigated. Cerebellar granule neurons of mouse and hippocampal neurons of rat embryo undergo apoptosis when cultured in serum-free medium. Treatment with chimeric proteins containing the extracellular domains of the neural adhesion molecules L1 or CHL1 fused to the Fc region of human immunoglobulin significantly enhanced the survival of neurons. Compared to the control, the percentage of surviving neurons increased about 60% and 45% with L1 and CHL1 fusion proteins, respectively. A fusion protein containing the extracellular domain of NCAM had no effect on survival. The L1 and CHL1 fusion proteins were effective both in soluble form or when offered as a substrate, with the maximal effect at about 1 microg/mL. To explore the intracellular events related to the neuronal survival effects of L1-Fc fusion protein, Bcl-2 and c-Jun expression were analyzed by Western blotting. The level of Bcl-2 in cerebellar granule neurons was increased by treatment with L1-Fc at both 1 and 5 days of culture. The level of c-Jun was not significantly affected at the early time point and was reduced by L1-Fc fusion protein after long-term culture. The results demonstrate that the neural adhesion molecule L1 and its relative CHL1 are potential neuronal survival factors for neurons of the central nervous system. Bcl-2 may serve as one of the intracellular mediators of the neuronal survival effects of L1.     

丁苯酞对七氟醚诱导神经细胞损伤的保护作用

目的探讨丁苯酞（BNP）对七氟醚诱导神经细胞损伤的影响及其可能的机制。 方法取胎鼠海马组织,分离培养神经细胞,分为对照组（正常神经细胞）、七氟醚组（3%七氟醚通气）、低剂量BNP组（1 μmol/L的BNP处理6 h+3%七氟醚通气）、中剂量BNP组（5 μmol/?L的BNP处理6 h + 3%七氟醚通气）以及高剂量BNP组（10 μmol/L的BNP处理6?h + 3%七氟醚通气）,采用MTT法检测细胞生存率,采用流式细胞术检测细胞凋亡情况,采用Western bolt法检测各组细胞Bcl-2、Bax以及Caspase-3蛋白表达情况,生存率、凋亡率比较采用t检验或方差分析。 结果24、48和72 h,七氟醚同期处理各组细胞生存率较对照组明显降低[对照组（88.31±8.20）%,（80.42±9.04）%,（75.63±7.84）%;七氟醚组（71.53±6.95）%,（61.35±7.38）%,（45.40±5.42）%,t = 3.491、3.654、7.092,P均< 0.001;低剂量BNP组（72.41±8.42）%,（67.22±6.46）%,（50.11±5.71）%,t = 3.025、2.657、17.411,P?= 0.016、0.027、0.000;中剂量BNP组（76.68±5.95）%,（72.53±5.10）%,（54.58±6.73）%,t = 2.567、2.030、4.556,P = 0.028、0.034、0.000;高剂量BNP组（79.32±6.44）%,（75.68±5.47）%,（60.09±4.28）%;t = 2.183、2.048、3.890,P = 0.023、0.036、0.000],而BNP各处理组细胞生存率明显高于单纯七氟醚处理组[七氟醚组（71.53±6.95）%,（61.35±7.38）%,（45.40±5.42）%,低剂量BNP组（72.41±8.42）%,（67.22±6.46）%,（50.11±5.71）%,t = 1.180、2.038、2.317,P?= 0.216、0.030、0.019;中剂量BNP组（76.68±5.95）%,（72.53±5.10）%,（54.58±6.73）%,t?= 2.180、2.787、2.376,P = 0.028、0.017、0.020;高剂量BNP组（79.32±6.44）%,（75.68±5.47）%,（60.09±4.28）%,t = 2.206、3.488、4.756,P = 0.022、0.000、0.000],且随着BNP浓度的升高,细胞生存率明显升高[低剂量BNP组（72.41±8.42）%,（67.22±6.46）%,（50.11±5.71）%;中剂量BNP组（76.68±5.95）%,（72.53±5.10）%,（54.58±6.73）%;高剂量BNP组（79.32±6.44）%,（75.68±5.47）%,（60.09±4.28）%;F = 2.182、2.491、2.384,P = 0.020、0.024、0.022]。采用流式细胞技术检测各组神经细胞凋亡情况,采用七氟醚通气处理的各组神经细胞凋亡率均显著高于对照组[七氟醚组（67.49±7.92）%,低剂量BNP组（60.72±8.33）%,中剂量BNP组（44.95±7.21）%,高剂量BNP组（31.86±6.50）%,对照组（19.42±4.58）%,F = 6.583,P < 0.001],而采用BNP处理的各组神经系统凋亡率明显低于七氟醚组（P < 0.05）,且随着BNP剂量的增加,凋亡率明显降低（P < 0.05）。七氟醚通气各组细胞Bcl-2表达较对照组降低,而BNP处理各组细胞Bcl-2表达较七氟醚组有所升高,且随着BNP剂量增加Bcl-2表达增加;七氟醚通气各组细胞Bax以及Caspase-3蛋白表达较对照组增加,而BNP处理各组细胞Bax以及Caspase-3蛋白表达较七氟醚组有所降低,且随着BNP浓度的升高Bax以及Caspase-3蛋白表达降低。 结论七氟醚可诱导神经细胞凋亡,从而对神经系统造成损伤,而BNP则可有效抑制七氟醚诱导的神经细胞凋亡,对神经系统损伤具有保护作用,其可能的机制与促进Bcl-2蛋白表达,抑制Bax、Caspase-3蛋白表达有关。     

On the adhesion of vesicles by cell adhesion molecules.

This paper gives a detailed analysis of experiments on the kinetics of aggregation of lipid vesicles containing neural cell adhesion molecules (N-CAM). An explanation for the dependence of the "initial aggregation rate," kagg, on the square of the vesicle concentration is given, accounting both for Brownian motion of the vesicles and shear effects. A model in which trimers of N-CAM are one-half of the molecular unit bridging two vesicles explains the observed dependence of kagg on up to the sixth power of the lateral N-CAM concentration and corroborates electron micrographic evidence for N-CAM "triskelions."     

Plasticity in epithelial cell phenotype: modulation by expression of different cadherin cell adhesion molecules

A primary function of cadherins is to regulate cell adhesion. Here, we demonstrate a broader function of cadherins in the differentiation of specialized epithelial cell phenotypes. In situ, the rat retinal pigment epithelium (RPE) forms cell-cell contacts within its monolayer, and at the apical membrane with the neural retina; Na+, K(+)-ATPase and the membrane cytoskeleton are restricted to the apical membrane. In vitro, RPE cells (RPE-J cell line) express an endogenous cadherin, form adherens junctions and a tight monolayer, but Na+,K(+)-ATPase is localized to both apical and basal-lateral membranes. Expression of E- cadherin in RPE-J cells results in restriction and accumulation of both Na+,K(+)-ATPase and the membrane cytoskeleton at the lateral membrane; these changes correlate with the synthesis of a different ankyrin isoform. In contrast to both RPE in situ and RPE-J cells that do not form desmosomes, E-cadherin expression in RPE-J cells induces accumulation of desmoglein mRNA, and assembly of desmosome-keratin complexes at cell-cell contacts. These results demonstrate that cadherins directly affect epithelial cell phenotype by remodeling the distributions of constitutively expressed proteins and by induced accumulation of specific proteins, which together lead to the generation of structurally and functionally distinct epithelial cell types.     

Differential expression of extracellular matrix and cell adhesion molecules in the olfactory nerve and glomerular layers of adult rats

Owing to the continual turnover of afferent input, the olfactory system offers a unique opportunity to study development and reorganization of neuronal networks in adults. To explore substrates that may underlie these processes in the adult olfactory system, we examined the expression and distribution of extracellular matrix and cell adhesion molecules (CAM) thought to be involved in axon guidance/extension. N-CAM, laminin, and tenascin were all detected by immunocytochemistry in the nerve and glomerular layers of the adult rat olfactory bulb, although the intensity and laminar distribution were varied. Antisera for N-CAM_total, N-CAM₁₈₀, and tenascin bound to fascicles within the olfactory nerve layer and the glomerular neuropil. However, binding was nonuniform in that only subsets of axon fascicles and restricted glomeruli showed evidence of immunoreactivity. Antilaminin and a polyclonal antitenascin similarly exhibited heterogeneous intralaminar immunoreactivity. Tenascin colocalized with glial processes at the borders of glomeruli and subcompartments of the glomerular neuropil. Laminin immunoreactivity was evident in subsets of olfactory nerve fascicles and, to a lesser extent, the glomeruli. The data are consistent with the notion that ongoing axon extension and glomerular targeting in the olfactory system is subserved in part by a heterogeneous expression of the same extracellular matrix and CAMs present at higher levels during perinatal development. © 1998 John Wiley & Sons, Inc. J Neurobiol 34: 271–282, 1998     

Methyl mercury triggers endothelial leukocyte adhesion and increases expression of cell adhesion molecules and chemokines

Cardiovascular disease is the leading cause of morbidity, mortality, and health care costs in the USA, and around the world. Among the various risk factors of cardiovascular disease, environmental and dietary exposures to methyl mercury, a highly toxic metal traditionally labeled as a neurotoxin, have been epidemiologically linked to human cardiovascular disease development. However, its role in development and promotion of atherosclerosis, an initial step in more immediately life-threatening cardiovascular diseases, remains unclear. This study was conducted to examine the role that methyl mercury plays in the adhesion of monocytes to human microvascular endothelial cells (HMEC-1), and the underlying mechanisms. Methyl mercury treatment significantly induced the adhesion of monocyte to HMEC-1 endothelial cells, a critical step in atherosclerosis, while also upregulating the expression of proinflammatory cytokines interleukin-6, interleukin-8. Further, methyl mercury treatment also upregulated the chemotactic cytokine monocyte chemoattractant protein-1 and intercellular adhesion molecule-1. These molecules are imperative for the firm adhesion of leukocytes to endothelial cells. Additionally, our results further demonstrated that methyl mercury stimulated a significant increase in NF-κB activation. These findings suggest that NF-κB signaling pathway activation by methyl mercury is an important factor in the binding of monocytes to endothelial cells. Finally, by using flow cytometric analysis, methyl mercury treatment caused a significant increase in necrotic cell death only at higher concentrations without initiating apoptosis. This study provides new insights into the molecular actions of methyl mercury that can lead to endothelial dysfunction, inflammation, and subsequent atherosclerotic development.     

Altered expression of tight junction molecules in alveolar septa in lung injury and fibrosis

The dysfunction of alveolar barriers is a critical factor in the development of lung injury and subsequent fibrosis, but the underlying molecular mechanisms remain poorly understood. To clarify the pathogenic roles of tight junctions in lung injury and fibrosis, we examined the altered expression of claudins, the major components of tight junctions, in the lungs of disease models with pulmonary fibrosis. Among the 24 known claudins, claudin-1, claudin-3, claudin-4, claudin-7, and claudin-10 were identified as components of airway tight junctions. Claudin-5 and claudin-18 were identified as components of alveolar tight junctions and were expressed in endothelial and alveolar epithelial cells, respectively. In experimental bleomycin-induced lung injury, the levels of mRNA encoding tight junction proteins were reduced, particularly those of claudin-18. The integrity of the epithelial tight junctions was disturbed in the fibrotic lesions 14 days after the intraperitoneal instillation of bleomycin. These results suggest that bleomycin mainly injured alveolar epithelial cells and impaired alveolar barrier function. In addition, we analyzed the influence of transforming growth factor-β (TGF-β), a critical mediator of pulmonary fibrosis that is upregulated after bleomycin-induced lung injury, on tight junctions in vitro. The addition of TGF-β decreased the expression of claudin-5 in human umbilical vein endothelial cells and disrupted the tight junctions of epithelial cells (A549). These results suggest that bleomycin-induced lung injury causes pathogenic alterations in tight junctions and that such alterations seem to be induced by TGF-β.     

Calcium-dependent cell adhesion molecules

The adhesive function of Ca2(+)-dependent CAMS has in the past been studied only indirectly, mainly using immunological techniques. The molecular cloning and information about the primary structure of several CAMs has been an important step in a more detailed molecular analysis. If there is a homophilic interaction between CAMs of neighbouring cells, an important question concerns the specificity of each CAM-mediated adhesiveness. Has each CAM a unique specificity and can this specificity be linked to a defined amino acid sequence? It will be important to elucidate the molecular mechanism of how each CAM interacts with the other. The experiments of Volk et al. (1987) suggest that an interaction of two different CAMs can occur. Since during development a given cell can express more than one CAM such an heterophilic interaction could play some regulatory role. Alternative splicing mechanisms or different protein forms during development or on different cell types have not yet been observed for Ca2(+)-dependent CAMs. However, uvomorulin is assumed to have a slightly different function during development and in adult tissues. During development uvomorulin is involved in the condensation, the pattern formation, and the sorting out of cells. In these processes the uvomorulin-mediated adhesiveness should be controlled, since cells reorganize and migrate during development. For the maintenance of the histoarchitecture in adult tissues uvomorulin might act more as a glue. This argues for the existence of mechanisms to regulate the strength of adhesiveness, and the cytoplasmic domain might be involved in these processes. The association of the cytoplasmic domain of uvomorulin with catenins could be an important observation in this respect.(ABSTRACT TRUNCATED AT 250 WORDS)     

Epithelial cell adhesion molecules

Recognition and binding between cells are of fundamental importance for a proper function of multicellular organisms, both during embryonic development and in the adult stage. Recently several cell surface proteins that are involved in these phenomena have been discovered. In the identification of these proteins, called cell adhesion molecules (CAMs), immunological methods have played a significant role. In a different approach to studies of cell-cell binding at the molecular level, the chemical composition of intercellular junctions is being studied. Intercellular junctions are specialized cell surface domains that have been identified by electron microscopy. They are particularly well developed in epithelia. Several proteins in the junctions have now been identified and characterized. This review deals with the biochemical properties of epithelial CAMs, and those proteins that are candidates for cell-to-cell binding in the junctions. In particular, the relationships between the various CAMs and junctional proteins are discussed. The tentative biological functions of these molecules are also considered.     

T cell adhesion molecules

Cell adhesion or conjugate formation between T lymphocytes and other cells is an important early step in the generation of the immune response. Although the antigen-specific T cell receptor confers antigen recognition and specificity, a number of other molecules expressed on the T cell surface are involved in the regulation of lymphocyte adhesion. T cell molecules that function to strengthen adhesion include lymphocyte function-associated antigen (LFA)-1, CD2, CD4, and CD8. Their ligands have recently been identified. LFA-1 is a member of the integrin family of adhesion receptors and one of its ligands is intercellular adhesion molecule-1 (ICAM-1); a ligand for CD2 is LFA-3; and ligands for CD4 and CD8 appear to be major histocompatibility complex class II and class I molecules, respectively. In addition, T cells express a number of receptors thought to be involved in cell matrix adhesion. The function and significance of these T cell adhesion receptors and their ligands are reviewed.     

Pathway recognition by neuronal growth cones: genetic analysis of neural cell adhesion molecules in Drosophila.

Genetic analysis has finally come of age in the study of neural cell adhesion molecules and their function during growth cone guidance in Drosophila. Recent studies have shown that fasciclin II, a neural cell adhesion molecule of the immunoglobulin superfamily, functions as a recognition molecule for the MP1 axon pathway, thus serving as the first molecular confirmation for the existence of functional labels on specific axon pathways in the developing organism.     

Distribution and possible interactions of actin-associated proteins and cell adhesion molecules of nerve growth cones

Actin filaments and their interactions with cell surface molecules have key roles in tissue cell behaviour. Axonal pathfinding during embryogenesis, an especially complex cell behaviour, is based on the migration of nerve growth cones. We have used fluorescence immunocytochemistry to examine the distribution in growth cones, their filopodia and lamellipodia of several actin-associated proteins and nerve cell adhesion molecules. The leading margins of chick dorsal root ganglion nerve growth cones and their protrusions stain strongly for f-actin, filamin, alpha-actinin, myosin, tropomyosin, talin and vinculin. MAP2 is absent from DRG growth cones, and staining for spectrin fodrin extends into growth cones, but not along filopodia. Thus, organization of the leading margins of growth cones may strongly resemble the leading lamella of migrating fibroblasts. The adhesion-mediating molecules integrin, L1, N-CAM and A-CAM are all found on DRG neurites and growth cones. However, filopodia stain relatively more strongly for integrin and L1 than for A-CAM or N-CAM. In fact, the 180 X 10(3) Mr form of N-CAM may be absent from most of the length of filopodia. DRG neurones cultured in cytochalasin B display differences in immunofluorescence staining which further emphasize that these adhesion molecules interact differentially with the actin filament system of migrating growth cones. Several models for neuronal morphogenesis emphasize the importance of regulation of the expression of adhesion molecules. Our results support hypotheses that cellular distribution and transmembrane interactions are key elements in the functions of these adhesion molecules during axonal pathfinding.     

Integrins and other cell adhesion molecules

Cell-cell and cell-substratum interactions are mediated through several different families of receptors. In addition to targeting cell adhesion to specific extracellular matrix proteins and ligands on adjacent cells, these receptors influence many diverse processes including cellular growth, differentiation, junction formation, and polarity. Several families of adhesion receptors have been identified. These include: 1) the integrins, heterodimeric molecules that function both as cell-substratum and cell-cell adhesion receptors; 2) the adhesion molecules of the immunoglobulin superfamily, which are involved in cell-cell adhesion and especially important during embryo-genesis, wound healing, and the inflammatory response; 3) the cadherins, developmentally regulated, calcium-dependent homophilic cell-cell adhesion proteins; 4) the LEC-CAMs, cell adhesion molecules with lectin-like domains that mediate white blood cell/endothelial cell adhesion; and 5) homing receptors that target lymphocytes to specific lymphoid tissue. In this review we summarize recent data describing the structure and function of some of these cell adhesion molecules (with special emphasis on the integrin family) and discuss the possible role of these molecules in development, inflammation, wound healing, coagulation, and tumor metastasis.     

Higher-order architecture of cell adhesion mediated by polymorphic synaptic adhesion molecules neurexin and neuroligin

Polymorphic adhesion molecules neurexin and neuroligin (NL) mediate asymmetric trans-synaptic adhesion, which is crucial for synapse development and function. It is not known whether or how individual synapse function is controlled by the interactions between variants and isoforms of these molecules with differing ectodomain regions. At a physiological concentration of Ca(2+), the ectodomain complex of neurexin-1 β isoform (Nrx1β) and NL1 spontaneously assembled into crystals of a lateral sheet-like superstructure topologically compatible with transcellular adhesion. Correlative light-electron microscopy confirmed extracellular sheet formation at the junctions between Nrx1β- and NL1-expressing non-neuronal cells, mimicking the close, parallel synaptic membrane apposition. The same NL1-expressing cells, however, did not form this higher-order architecture with cells expressing the much longer neurexin-1 α isoform, suggesting a functional discrimination mechanism between synaptic contacts made by different isoforms of neurexin variants.     

C-reactive protein induced expression of adhesion molecules in cultured cerebral microvascular endothelial cells

Ischemic stroke can trigger an acute phase response resulting in a rise of plasma concentration of C-reactive protein (CRP). Clinical data about the relationship between CRP and prognosis suggest that CRP might be involved in the pathogenesis of cerebral ischemia. In the present work, a significant increase of circulating level of CRP was observed in an vivo rat brain ischemia model of middle cerebral artery occlusion. To determine the possible effects of CRP on brain microvessel endothelium, we performed a dose-dependent experiment in mouse brain microvascular endothelial cells (bEnd.3 cells) with emphasis on its relation to cell adhesions molecules. Incubation with CRP (1-75 mg/L) for 24 h significantly increased Lactate dehydrogenase (LDH) leakage from bEnd.3 cells (P<0.01) in a dose-dependent manner, and induced significant up-regulations of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expressions analyzed by Western blotting (P<0.01). In contrast to earlier report, CRP also induced significant increase in ICAM-1 expression in the absence of serum (P<0.01). In conclusion, the present results suggest that CRP may be involved directly in the development of inflammation in response to cerebral ischemia.