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PubMedDate not supplied

Reconstructed human cornea produced in vitro by tissue engineering.

The aim of the present study was to produce a reconstructed human cornea in vitro by tissue engineering and to characterize the expression of integrins and basement membrane proteins in this reconstructed cornea. Epithelial cells and fibroblasts were isolated from human corneas (limbus or centre) and cultured on plastic substrates in vitro. Reconstructed human corneas were obtained by culturing epithelial cells on collagen gels containing fibroblasts. Histological (Masson's trichrome staining) and immunohistological (laminin, type VII collagen, fibronectin as well as beta1, alpha3, alpha4, alpha5, and alpha6 integrin subunits) studies were performed. Human corneal epithelial cells from the limbus yielded colonies of small fast-growing cells when cultured on plastic substrates. They could be subcultured for several passages in contrast to central corneal cells. In reconstructed cornea, the epithelium had 4-5 cell layers by the third day of culture; basal cells were cuboidal. The basement membrane components were already detected after 3 days of culture. Integrin stainings, except for the alpha4 integrin, were also positive after 3 days. They were mostly detected at the epithelium-stroma junction. Such in vitro tissue-engineered human cornea, which shows appropriate histology and expression of basement membrane components and integrins, provides tools for further physiological, toxicological and pharmacological studies as well as being an attractive model for gene expression studies.

Cell Division↗
PubMed1997

Propolypeptide of von Willebrand factor is a novel ligand for very late antigen-4 integrin.

We have previously reported that propolypeptide of von Willebrand factor (pp-vWF) promotes melanoma cell adhesion in a beta1 integrin-dependent manner. In this report, we identified the alpha subunit of the cell adhesion receptor for pp-vWF as alpha4. Human leukemia cell lines that express alpha4beta1 integrin (very late antigen-4, VLA-4), but not cell lines which lack VLA-4, attached well to pp-vWF substrate and these adhesions were completely inhibited by anti-alpha4 integrin monoclonal antibody HP2/1. Adhesion of mouse melanoma expressing alpha4 integrin was also inhibited by anti-mouse alpha4 mAb PS/2. Furthermore, transfection of human alpha4 cDNA into alpha4(-) Chinese hamster ovary cells resulted in an acquisition of adhesive activity to pp-vWF, indicating that pp-vWF is a ligand for VLA-4 integrin. Using a recombinant fragment of pp-vWF, the cell attachment site was shown to be located within amino acid residues 376-455 of pp-vWF. A series of synthetic peptides covering this region were tested for the ability to promote cell attachment and a 15-residue peptide designated T2-15 (DCQDHSFSIVIETVQ, residues numbered 395-409) promoted VLA-4 dependent cell adhesion. The peptide was also capable of inhibiting cell adhesion to pp-vWF, suggesting that this sequence represents the cell attachment site. By affinity chromatography using peptide T2-15-Sepharose, it was found that alpha4beta1 integrin complex from extracts of surface iodinated B16 cells specifically bound to the peptide. These results strongly suggest that pp-vWF is a novel physiological ligand for VLA-4.

Animals↗
PubMed2000

Selective upregulation of a functional beta7 integrin on differentiating eosinophils.

BACKGROUND: The sequence of adhesion-molecule expression during eosinophil differentiation remains unclear. METHODS: We analyzed the surface expression of alpha4, beta1, and beta7 integrins and compared it to established myeloid developmental markers, using the eosinophilic cell line HL-60 clone 15, as well as cord and peripheral blood differentiation assays. RESULTS: Cells induced to eosinophil differentiation by treatment with butyric acid, IL-5, and GM-CSF showed a significant upregulation of beta7 integrin expression coincident with a marked upregulation of CD35 and attenuation of CD33 and beta1 integrin expression. In addition, adhesion of induced HL-60 clone 15 cells to fibronectin was attenuated by a beta7 integrin antibody. CONCLUSIONS: Our data show that protein synthesis-dependent upregulation of the functional beta7 integrin occurs under conditions when beta4 and beta1 integrins are fully expressed, indicating a sequential appearance of specific adhesion molecules on differentiating eosinophil progenitors.

Antigens, CD↗
PubMed2005

Expression of cell adhesion molecules and chemokine receptors: angioinvasiveness in nasal NK/T-cell lymphoma.

Sinonasal natural killer (NK)/T-cell lymphoma (NKTCL) is closely associated with Epstein-Barr virus (EBV) infection and expresses latent membrane protein (LMP)-1 and EB nuclear antigen (EBNA)-1, i.e., latency II of EBV infection. Angioinvasion by neoplastic cells is a characteristic feature of NKTCL, but its mechanism is unknown. To elucidate the molecular mechanism of angio-invasiveness in NKTCL, expression of cell adhesion molecules and chemokine receptors at mRNA and protein levels was examined using real-time PCR and immunohistochemistry in 17 NKTCL together with 10 diffuse large B-cell lymphoma (DLBL) and 9 non-neoplastic nasal mucosa as controls. EBV DNA was detected in 14 of 16 NKTCL examined, and 7 of these 14 expressed LMP-1. mRNA expression levels of integrin subunits alpha4, alpha L, alpha M, and beta2 were significantly higher in NKTCL than non-neoplastic controls. Integrin subunits alpha2 and alpha M were expressed at a significantly higher level in NKTCL with angioinvasion than those without. Expression level of alpha M was significantly higher in 7 cases of NKTCL with LMP-1 expression than 7 without. Immunohistochemistry showed expression of these molecules in NKTCL cells. These findings suggest that EBV infection might be involved in the pathogenesis of angioinvasion of NKTCL through up-regulation of alpha M by LMP-1.

Adult↗
PubMed2005

Differential expression of endometrial integrins and progesterone receptor during the window of implantation in normo-ovulatory women treated with clomiphene citrate.

OBJECTIVE: To assess the effect of clomiphene citrate (CC) on endometrial epithelial integrins and P receptors (PR) during the window of implantation. DESIGN: Controlled, prospective, clinical study. SETTING: Teaching hospital and university research laboratory. PATIENT(S): Thirty-one fertile, normo-ovulatory women participated in this trial. Thirteen women exhibited a CC-stimulated cycle with 50 mg on days 5-9, and 18 women with spontaneous menstrual cycles served as controls. INTERVENTION(S): Endometrial biopsies in the midluteal phase. MAIN OUTCOME MEASURE(S): Immunohistochemical determination and endometrial cellular localization of alpha1, alpha v, beta3, and alpha4 epithelial integrins and PR during the window of implantation. The staining intensity was assessed by a semiquantitative index (HSCORE) and compared by nonparametric Mann-Whitney test. RESULT(S): Higher plasma levels of P and E2 and delayed histologic dating of the endometrium (38%) were features of CC-treated women. In addition, a low epithelial beta3 integrin expression and persistent PR were observed in glandular epithelial cells of "out-of-phase" endometrial biopsies from CC-treated women. In contrast, in "in-phase" biopsies, neither epithelial PR nor beta3 integrin were different from spontaneous control cycles. There was no difference in the expression of alpha1, alpha v, and alpha4 between the groups studied. CONCLUSION(S): The administration of clomiphene produces aberrant endometrial beta3 integrin expression in conjunction with a failure in the down-regulation of PR during the window of implantation in a significant number of normo-ovulatory women, notwithstanding the higher plasma P levels. Therefore, CC might affect the expression of endometrial receptivity markers.

Adult↗
PubMed2002

Adhesion of synchronized human hematopoietic progenitor cells to fibronectin and vascular cell adhesion molecule-1 fluctuates reversibly during cell cycle transit in ex vivo culture.

Ex vivo expansion of hematopoietic stem/progenitor cells may result in defective engraftment. Human cord blood CD34(+) progenitor cells were synchronized and assayed for adhesion and migration onto fibronectin (Fn) and vascular cell adhesion molecule-1 (VCAM-1) at different stages of a first cell cycle executed ex vivo. During S phase transit, adhesion to Fn was transiently increased while binding to VCAM-1 was reversibly decreased, after which adhesion to both ligands returned to baseline levels with cell cycle completion. Transmigration across Fn and VCAM-1 decreased irreversibly during S phase progression. The function of alpha4 and alpha5 integrins was assessed with specific neutralizing antibodies. In uncultured CD34(+) cells and long-term culture-initiating cells (LTC-ICs), both adhesion and migration on Fn were inhibited by anti-alpha4 but not by anti-alpha5 antibodies. In mitotically activated CD34(+) cells and LTC-ICs, adhesion and migration on Fn were mainly dependent on alpha5 integrin and to a lesser extent on alpha4 integrin. Changes in integrin function were not dependent on parallel modulation of integrin expression. In conclusion, Fn and VCAM-1 binding of progenitor cells fluctuates reversibly during cell cycle transit ex vivo. In addition, our data show that mitogenic activation induces a shift from a dominant alpha4 to a preferential alpha5 integrin-dependent interaction with Fn.

Antigens, CD↗
PubMed2002

Expression of integrins, cyclooxygenases and matrix metalloproteinases in three-dimensional human endometrial cell culture system.

The objective of this investigation was to establish a three-dimensionally cultured human endometrium which could be used as a tissue model for the mechanism study of implantation in vitro. By using human endometrial stromal (ES) and epithelial cells (EE) from hysterectomy specimens, reconstruction of endometrium in culture was established by first layering a collagen gel containing ES cells, then overlaying with the Matrigel containing endometrial epithelial (EE) cells. Ultrastructural examination of the 48 h-endometrial cell culture revealed monolayered columnar EE cells with microvilli on the collagen layer containing ES cells and appearance of the tight junctions and desmosomes between EE cells, a cell layer closely resembling the native endometrium. Immunohistochemical characterization of the reconstructed endometrium showed a strong immunoreactivity for cytokeratin, integrin alpha1, alpha4 and beta3 subunits, cyclooxygenases-1 and -2, matrix metalloproteinases-1, -2, -3 and -9, and tissue inhibitor of metalloproteinases-1 and -2 in the EE cells comparable to the native endometrial epithelium. ES cells also showed stronger immunoreactivity for cyclooxygenases, integrins and MMPs, but less for cytokeratin. Gelatin zymographic analyses of the media obtained from the reconstructed endometrium model showed gelatinase activity bands at 57, 60, 72, 92 and 97 kDa molecular weight, respectively. The present study provides a possibility that our three-dimensionally cultured endometrium model could mimic the morphological and functional characteristics of the native endometrium. The model could be used to clarify the roles of various molecules involved in the human implantation.

Adult↗
PubMed2002

Melanoma cell attachment, invasion, and integrin expression is upregulated by tumor necrosis factor alpha and suppressed by alpha melanocyte stimulating hormone.

We have previously shown alpha-melanocyte stimulating hormone to protect melanocytes and melanoma cells from the proinflammatory actions of tumor necrosis factor-alpha. The aim of the study was to extend this work to look into the influence of tumor necrosis factor-alpha on melanoma cell attachment, invasion, and integrin expression and ask to what extent alpha-melanocyte stimulating hormone might protect cells from tumor necrosis factor-alpha stimulation of increased integrin expression. HBL human melanoma cells were studied under resting and stressed conditions using tumor necrosis factor-alpha as a proinflammatory cytokine. Functional information on the actions of tumor necrosis factor-alpha on melanoma cells was obtained by examining the strength of attachment of melanoma cells to substrates and the ability of melanoma cells to invade through fibronectin. alpha3, alpha4, and beta1 integrin expression was detected by Western immunoblotting and the ability of alpha-melanocyte stimulating hormone to oppose the actions of tumor necrosis factor-alpha was studied on HBL cell attachment, invasion, and integrin subunit expression. Our results show that tumor necrosis factor-alpha increases the number of melanoma cells attaching to collagen (types I and IV) and tissue culture polystyrene, increases ability to invade through fibronectin, and upregulates the expression of alpha3 (28%), alpha4 (90%), and beta1 (65%) integrin subunit expression. In contrast, alpha-melanocyte stimulating hormone reduced cell attachment, invasion, and integrin expression and opposed the stimulatory effects of tumor necrosis factor-alpha. In conclusion this study provides further evidence of alpha-melanocyte stimulating hormone acting to "protect" melanoma cells from proinflammatory cytokine action. Our data support a hypothesis that an inflammatory environment would promote melanoma invasion and that the anti-invasive actions of alpha-melanocyte stimulating hormone are consistent with its working in an anti-inflammatory capacity.

Antineoplastic Agents↗
PubMed1999

Intraepithelial lymphocytes traffic to the intestine and enhance resistance to Toxoplasma gondii oral infection.

Toxoplasma gondii Ag-primed intraepithelial lymphocytes (IEL) from the mouse intestine have been shown to be protective against an lethal parasite challenge when adoptively transferred into recipient mice. In the present study, we observed that Ag-primed IEL traffic to the intestine of naive mice following i.v. administration. Primed and CD8beta+ IEL were the most efficient cells at homing to the host organ. In congenic mice, IEL migrated from intestine within several hours posttransfer. On Ag reexposure, the primed IEL return to the intestine where they enhance resistance as determined by reduction in the number of brain cysts. Treatment of recipient mice with anti-alpha4 and anti-alphaE Abs partially inhibited IEL intestinal homing. The Ab treatment dramatically impaired resistance to a subsequent oral infection. These finding indicate that lymphocyte homing is an important parameter in establishing long term immunity to recurrent infection with this parasite.

Adoptive Transfer↗
PubMed2002

H-Ras/mitogen-activated protein kinase pathway inhibits integrin-mediated adhesion and induces apoptosis in osteoblasts.

We have studied the relevance of H-Ras and its downstream effectors to osteoblast functions. 1) Purified human osteoblasts highly expressed integrins beta1, alpha4, alpha5, alpha6 and the activation epitope of beta1. However, these molecules were markedly down-regulated on osteoblasts transfected with expression vector encoding fully activated H-Ras(V12), H-Ras(V12)T35S, activating Raf-1/mitogen-activated protein kinase (MAPK), or an active Raf-1 but not on cells having H-Ras(V12)Y40C, a phosphoinositide 3-kinase (PI3K)-binding mutant. 2) Although osteoblasts spontaneously adhered to fibronectin and laminin in beta1-dependent manner, the expression of H-Ras(V12) or H-Ras(V12)T35S, but not H-Ras(V12)Y40C, in osteoblasts reduced their adhesion. 3) Osteoblasts bearing H-Ras(V12), H-Ras(V12)T35S, or Raf-1 failed to proliferate, whereas those with H-Ras(V12)Y40C proliferated well. (4) The up-regulation of Fas and down-regulation of Bcl-2 were observed in osteoblasts expressing H-Ras(V12), H-Ras(V12)T35S, or Raf-1. (5) Most of the cells having H-Ras(V12), H-Ras(V12)T35S, or Raf-1 became annexin-V(high)/propidium iodide (PI)(high or low) and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL)(high)/PI(low) after 24 and 72 h incubation, respectively. Thus, we propose that H-Ras signals followed by Raf-1/MAPK pathway but not PI3K not only reduces beta(1)-mediated adhesion of osteoblasts to matrix proteins but induces apoptosis presumably via the Fas up-regulation and Bcl-2 down-regulation.

Apoptosis↗
PubMed1996

Identification of eosinophils by flow cytometry.

A flow cytometric method to identify and characterize eosinophils in lysed whole blood samples was established. A gating protocol was applied that in the first step uses the high autofluorescence and the high sideward scatter of eosinophils. In the second step, eosinophils were differentiated from neutrophils by lack of CD16 expression or alternatively presence of CD49d expression. Eosinophils purified by density gradient centrifugation (purity: 93% eosinophils contaminated with 7% neutrophils) were used to evaluate the technique. We were able to identify eosinophils added back to lysed whole blood samples and to identify partial degranulated eosinophils after treatment with secretory IgA and anti-IgA. In addition we were able to show that due to a large overlap of sideward scatter, the technique is applicable to purified normodense as well as hypodense eosinophils. In addition, there was a good correlation (r = 0.921, P < 0.0001) between the percentage of eosinophils determined by flow cytometry and microscopic evaluation in 81 patients. In patients with atopic dermatitis there was a reasonable correlation between a severity score (SCORAD) and the number of eosinophils determined by flow cytometry (R = 0.6107, P = 0017). Since the technique proved to be able to identify activated eosinophils bearing the CD69 early activation antigen, the relation between serum creatinine and CD69 expression on peripheral blood eosinophils was analysed showing a positive correlation (r = 0.4344, P = 0.016).

Antigens, CD↗
PubMed2006

Recombinant therapeutics: from bench to bedside (if your health plan concurs).

A talented medical student at our institution was recently diagnosed with multiple sclerosis (MS). beta interferon was prescribed; however, her annual cap from student health insurance coverage for outpatient drug expenses is only Dollars 3000, a sum that would be exceeded within 3 months and leave her without coverage for symptomatic medications also required for her care. Unable to pay for the treatment from personal resources, she qualified to receive beta interferon without cost from a universal access program established by the manufacturer. Unfortunately, it was evident within a few months that she had a poor therapeutic response, so her physician prescribed natalizumab. Her health care plan requires that infusion therapy be given at the hospital's infusion center, yet for various reasons, the drug was not yet approved by the formulary. She remains unable to receive the drug.

Antibodies, Monoclonal↗
PubMed1997

Fibroblast dependency during early thymocyte development maps to the CD25+ CD44+ stage and involves interactions with fibroblast matrix molecules.

We have investigated the role of specific components of the thymic stroma during development of CD4-8-T cell precursors by separating and reaggregating precursor subsets with individual or combinations of stromal cells. We show that while the development of CD25+ 44+ precursors is dependent upon a combination of major histocompatibility complex (MHC) class II+ thymic epithelial cells and fibroblasts, their direct descendants, CD25+ 44- precursors, develop to the CD4+ 8+ stage in the presence of MHC class II+ thymic epithelial cells alone. Thus, CD25+ 44+ precursors are the last developmental stage to be dependent upon fibroblast support. In addition, while metabolically inactive, 1-ethyl-3-(3'-dimethylaminopropyl) carbodiimide (ECDI)-treated fibroblasts retain the ability to promote T cell development, prior treatment with hyaluronidase abrogates this effect, suggesting that fibroblast-associated extracellular matrix components are the key elements involved. In support of this, we show that fibroblasts are located in cortical regions of the thymus where T cell precursors are known to reside, and that these fibroblasts are associated with an extensive extracellular matrix not found on thymic epithelial cells. Finally, antibodies to alpha 4 integrin and CD44 interfere with the efficiency with which CD4+ 8+ cells are generated from CD25+ 44+ precursors in reaggregate cultures and also reduce the binding of the latter to 3T3 fibroblasts, suggesting these molecules play a role in bringing T cell precursors into contact with fibroblast-associated extracellular matrix.

3T3 Cells↗
PubMed2004

Defective up-regulation of CD49d in final maturation of NOD mouse macrophages.

Macrophages are potent regulators of both innate and adaptive immunity. They play a central role in the development of autoimmune diabetes and are among the first cells to appear in peri-islet infiltrates of NOD mice that spontaneously develop diabetes. Since efficient adhesion and migration are crucial for proper macrophage trafficking, we examined the migration and fibronectin (FN) adhesion capacity of NOD macrophages, as well as the regulation and expression of the FN receptors alpha4beta1 and alpha5beta1. When compared to macrophages from control strains, resident NOD macrophages showed a reduced ability to adhere to and migrate on FN, a delayed clearance following peritoneal inflammation, and substantially lower expression levels of the alpha4beta1 integrin alpha chain, CD49d. NOD bone marrow-derived macrophages were specifically defective in the LPS-induced increase in CD49d expression. Moreover, the mitogen-activated protein kinase extracellular signal-regulated kinase-1/2 negatively regulated macrophage CD49d expression and strongly suppressed its expression in NOD macrophages. The data presented herein indicate that the LPS-activated signaling cascade plays a critical role in CD49d expression of macrophages. Mature NOD macrophages are characterized by decreased CD49d expression and show defective CD49d-mediated adhesion to FN.

Animals↗
PubMed2006

In vivo CD44-CD49d complex formation in autoimmune disease has consequences on T cell activation and apoptosis resistance.

CD44 is involved in leukocyte migration and activation and has recently been reported to contribute to leukocyte extravasation by associating with CD49d. We explored whether similar changes in CD44 activity are seen in vivo using murine alopecia areata (AA) as a chronic, organ-related autoimmune disease model system. Expression of the activated, hyaluronan-binding form of CD44, and of CD49d, was elevated in draining lymph node cells (LNC) of AA-affected mice as compared to control mice. LNC of AA mice displayed increased motility, proliferative activity and apoptosis resistance, which were equally well inhibited by anti-CD44 and anti-CD49d. The latter is the sequelae of the association between CD44 and CD49d that is seen in activated lymphocytes. Significantly, due to CD44-CD49d complex formation, CD44 gains access to focal adhesion kinase and CD49d gains access to CD44-associated lck and ezrin, such that downstream kinases become activated via CD44 or CD49d engagement. Thus, by their association, CD44 and CD49d mutually avail themselves of the partner's signaling pathways and the ligand binding of each one triggers signaling pathways of both. This strongly influences the lymphocytes' activation state and function.

Alopecia Areata↗
PubMed2005

The class II phosphoinositide 3-kinase PI3K-C2beta regulates cell migration by a PtdIns3P dependent mechanism.

The biological and pathophysiological significance of class II phosphoinositide 3-kinase enzyme expression currently remains unclear. Using an in vitro scrape wound assay and time-lapse video microscopy, we demonstrate that cell motility is increased in cultures expressing recombinant PI3K-C2beta enzyme. In addition, overexpression of PI3K-C2beta transiently decreased cell adhesion, stimulated the formation of cytoplasmic processes, and decreased the rate of cell proliferation. Consistent with these observations, expression of PI3K-C2beta also decreased expression of alpha4 beta1 integrin subunits. Using asynchronous cultures, we show that endogenous PI3K-C2beta is present in lamellipodia of motile cells. When cells expressing recombinant PI3K-C2beta were plated onto fibronectin, cortical actin staining increased markedly and actin rich lamellipodia and filopodia became evident. Overexpression of a 2xFYVE(Hrs) domain fusion protein abolished this response demonstrating that the effect of PI3K-C2beta on the reorganization of actin filaments is dependent upon PtdIns3P. Finally, overexpression of PI3K-C2beta increased GTP loading of Cdc42. Our data demonstrates for the first time, that PI3K-C2beta plays a regulatory role in cell motility and that the mechanism by which it reorganizes the actin cytoskeleton is dependent upon PtdIns3P production.

Actins↗