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Cell Surface Molecules (cell + surface_molecule)
Selected AbstractsBT-IgSF, a novel immunoglobulin superfamily protein, functions as a cell adhesion moleculeJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2005Hideki Harada BT-IgSF is a newly identified cell surface glycoprotein belonging to the immunoglobulin superfamily (IgSF). We have previously shown that the expression of the BT-IgSF gene was highly restricted to brain and testis, and its transcript was detected in both neurons and glial cells. In this study, to explore its function, we generated cells overexpressing BT-IgSF proteins and analyzed their phenotypes. We found that the constitutive expression of BT-IgSF in the myeloid leukemia cell line TF-1 -fms did not alter the growth rates, but caused the formation of large cell aggregates. The cell aggregates were also observed with mutant BT-IgSF lacking its cytoplasmic tail, the amino acid sequences of which were highly conserved among the BT-IgSF subgroup proteins. The neutralizing antibody to ,1 integrin did not diminish the cell aggregate formation. These results indicate that BT-IgSF functions as a cell adhesion molecule, that its cytoplasmic tail is not essential for the function, and that ,1 integrin is not involved in the function. We confirmed the cell adhesion function using NIH/3T3 fibroblastic cells expressing BT-IgSF in an inducible system. Flow cytometric analyses with the cells demonstrated that the cell aggregation mediated by BT-IgSF was through homophilic molecular interaction, and in a Ca2+/Mg2+ -independent manner. Coupled with its restricted pattern of the expression, the cell adhesion-inducing function of BT-IgSF suggests a role of the cell surface molecule in the development/function of the central nervous system and spermatogenesis. © 2005 Wiley-Liss, Inc. [source] Induction of triggering receptor expressed on myeloid cells 1 in murine resident peritoneal macrophages by monosodium urate monohydrate crystalsARTHRITIS & RHEUMATISM, Issue 2 2006Yousuke Murakami Objective Triggering receptor expressed on myeloid cells 1 (TREM-1) is a cell surface molecule that was recently identified on monocytes and neutrophils. TREM-1 has been implicated in the early inflammatory responses induced by microbes, but its pathophysiologic role in nonmicrobial inflammation remains unknown. In the present study, we investigated the role of TREM-1 in acute inflammation induced by monosodium urate monohydrate (MSU) crystals. Induction of TREM-1 expression by MSU crystal,stimulated murine resident peritoneal macrophages and infiltrating leukocytes in a murine air-pouch model of crystal-induced acute inflammation was determined. The biologic role of TREM-1 in crystal-induced cytokine production by resident peritoneal macrophages was also investigated. Methods TREM-1 expression by resident peritoneal macrophages and infiltrating leukocytes in a murine air-pouch model was determined by quantitative real-time polymerase chain reaction, Western blot analysis, and flow cytometry. Cytokine production by resident peritoneal macrophages after incubation with MSU crystals in the presence or absence of an anti,TREM-1 agonist antibody was determined by enzyme-linked immunosorbent assay. Results TREM-1 expression by resident peritoneal macrophages was significantly induced after stimulation with the crystals. Maximum expression of TREM-1 transcripts and protein occurred at 1 and 4 hours after exposure to the crystals, respectively. Costimulation of resident peritoneal macrophages with MSU crystals and an anti,TREM-1 agonist antibody synergistically increased the production of both interleukin-1, and monocyte chemotactic protein 1 compared with stimulation with the crystals alone. MSU crystals also induced TREM-1 expression in infiltrating leukocytes in a murine air-pouch model of crystal-induced acute inflammation. Conclusion These findings suggest that rapid induction of TREM-1 expression on resident peritoneal macrophages and neutrophils by MSU crystals may contribute to the development of acute gout through enhancement of inflammatory responses. [source] Cell-surface bound pertussis toxin induces polyclonal T cell responses with high levels of interferon-, in the absence of interleukin-12EUROPEAN JOURNAL OF IMMUNOLOGY, Issue 7 2003Ayako Wakatsuki Abstract Pertussis toxin (PTx), an exotoxin produced by Bordetella pertussis, has long been used as a mucosal adjuvant. We examined the T cell stimulatory properties of PTx in order to dissectits mechanisms of adjuvanticity. PTx or the B-oligomer of PTx (PTxB) failed to activate purified murine CD4+ or CD8+ T cells, as measured by a lack of proliferation or expression of early T cell activation markers. However, these T cells proliferated extensively in response to the toxin in the presence of syngeneic DC, and proliferation was accompanied by a high level of IFN-, production in the absence of IL-12. Interestingly, such responses were independent of signals mediated by MHC,TCR interaction. Both PTx and PTxB were found to bind stably to the surface of DC, and increased the adherence of DC to surrounding cells. These data suggest that polyclonal T cell responses mediated by the toxin are likely to be caused by the toxin bound on the surface of APC, either cross-linking cell surface molecules on T cells, or directly stimulating T cells together with the co-stimulatory molecules expressed on APC. B. pertussis may use this toxin as a mechanism to evade a specific immune response. [source] Characterization of the myo -inositol transport system in Trypanosoma cruziFEBS JOURNAL, Issue 9 2000Marcelo Einicker-Lamas myo -Inositol is a growth factor for mammalian cells as well as for the pathogenic protozoa Trypanosoma cruzi. Most of the cell surface molecules in this organism rely on myo -inositol as the biosynthetic precursor for phosphoinositides and glycosylated phosphatidylinositols. The aim of this work was to investigate the process of myo -inositol translocation across the parasite cell membrane. myo -Inositol uptake was concentration-dependent in the concentration range 0.1,10 µm with maximal transport obtained at 8 µm. Using sodium-free buffers, where Na+ was replaced by choline or K+, myo -inositol uptake was inhibited by 50%. Furosemide, an inhibitor of the ouabain-insensitive Na+ -ATPase, inhibited the Na+ -dependent and Na+ -independent myo -inositol uptake by 68 and 33%, respectively. In contrast, ouabain, an (Na++/K+) ATPase inhibitor, did not affect transport. Part of the myo -inositol uptake is mediated by active transport as it was inhibited when energy metabolism inhibitors such as carbonyl cyanide p -(trifluoromethoxy)-phenylhydrazone (34%), 2,4-dinitrophenol (50%), KCN (71%) and NaN3 (69%) were added to the medium, or the temperature of the medium was lowered to 4 °C. The addition of glucose (5,50 mm) or mannose (10 mm) did not change the myo -inositol uptake, whereas the addition of 10 mm nonlabeled myo -inositol totally inhibited this transport, indicating that the transporter is specific for myo -inositol. Phloretin (0.3 mm) and phoridzin (5 mm), but not cytochalasin B, were efficient inhibitors of myo -inositol uptake. A portion of the accumulated myo -inositol is converted to inositol phosphates and phosphoinositides. These data show that myo -inositol transport in T. cruzi epimastigotes is mediated by at least two specific transporters , one Na+ -dependent and the other Na+ -independent. [source] Genetic background of primary biliary cirrhosisHEPATOLOGY RESEARCH, Issue 2007Atsushi Tanaka The clustering of patients in a representative family as well as relatively high concordance rate in monozygotic twins strongly indicate that genetic factors play a crucial role in modulating primary biliary cirrhosis (PBC) by conferring susceptibility to, or providing protection from, the disease. Therefore, much like other autoimmune diseases, intensive investigations have attempted to elucidate which genes are incriminated in the etiology of PBC. So far, a number of genes, including major histocompatibility complex (MHC) class I and II, cytokines and cell surface molecules, have been examined to seek the possibility of whether single nucleotide polymorphisms (SNP) of the gene might be associated with susceptibility to PBC. Nevertheless, it appears that methodologicaldifficulties, mainly the limitation of the number of individuals tested in each study, hamper the detection of a convincing and reproducible link between genetic polymorphisms and the etiology of PBC. Also, the difference in genetic background among several ethnic groups may play a role in concealing the association. In this review, I will highlight the genetic association in PBC, and review the association of genetic polymorphisms with the etiology of PBC, which have been reported in various ethnicities. [source] The immunological basis of B-cell therapy in systemic lupus erythematosusINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 1 2010Mo Yin MOK Abstract Loss of B-cell tolerance is a hallmark feature of the pathogenesis in systemic lupus erythematosus (SLE), an autoimmune disease that is characterized by hypergammaglobulinemia and autoantibody production. These autoantibodies lead to formation of immune-complex deposition in internal organs causing inflammation and damage. Autoreactive B-cells are believed to be central in the pathophysiology of SLE. Other than its role in the production of antibodies that mediate humoral immune response, B-cells also function as antigen-presenting cells and are capable of activating T-cells. Activated B-cells may also produce pro-inflammatory cytokines that aggravate local inflammation. Abnormal B-cell homeostasis has been described in SLE patients. This may occur as a result of intrinsic B-cell defect or from aberrant regulation by maturation and survival signals. B-cell-based therapy is the current mainstream of research and development of novel therapies in SLE patients with severe and refractory disease. Potential cellular and molecular targets for B-cell therapies include cell surface molecules such as CD20 (rituximab) and CD22 (epratuzumab); co-stimulatory molecules involved in B-cell,T-cell interaction such as CTLA4 and B7 molecules (abatacept); maturation and growth factors such as B-cell activating factor and a proliferation-inducing ligand (belimumab, briobacept, atacicept) and B-cell tolerogen (abetimus). This article provides an overview on normal B-cell physiology and abnormal B-cell biology in SLE that form the immunological basis of B-cell-targeted therapy in the treatment of these patients with refractory diseases. [source] Markers for the lymphatic endothelium: In search of the holy grail?MICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2001Jonathan P. Sleeman Abstract The ability to discriminate reliably at the histological level between blood and lymphatic microcapillaries would greatly assist the study of a number of biological and pathological questions and may also be of clinical utility. A structure,function comparison of these types of microcapillary suggests that differences which could function as markers to allow discrimination between blood and lymphatic endothelium should exist. Indeed, to date a variety of such markers have been proposed, including basement membrane components, constituents of junctional complexes such as desmoplakin and enzymes such as 5,-nucleotidase. Additionally, a variety of cell surface molecules are thought to be differentially expressed, including PAL-E, VEGFR-3, podoplanin, and LYVE-1. Several of the lymphatic markers proposed in the literature require further characterization to demonstrate fully their lymphatic specificity and some have proven not to be reliable. The relative merits and drawbacks of each of the proposed markers is discussed. Microsc. Res. Tech. 55:61,69, 2001. © 2001 Wiley-Liss, Inc. [source] Expression of MHC Class II, CD70, CD80, CD86 and pro-inflammatory cytokines is differentially regulated in oral epithelial cells following bacterial challengeMOLECULAR ORAL MICROBIOLOGY, Issue 6 2003D. C. Han Oral epithelium may play a regulatory role in local immune responses when interacting with bacteria. The present study was undertaken to investigate the effects of selected bacterial pathogens found in periodontal and endodontic infections on oral epithelial cells. Expression of cell surface molecules (major histocompatibility complex (MHC) Class II, CD54, CD70, CD80 and CD86) and secretion of inflammatory cytokines (interleukin (IL)-1,, IL-6, and tumor necrosis factor (TNF)-,) in response to selected bacterial challenge were examined on an immortalized oral epithelial cell line, HOK-18A and a skin epithelial cell line, HaCaT. Actinomyces viscosus, Actinomyces israelii, Fusobacterium nucleatum lipopolysaccharide (LPS) or primary human periradicular exudate from a granuloma were co-cultured with epithelial cells for 4 or 24 h. Subsequently, cell surface expression of MHC Class II, CD54, CD70, CD80 and CD86, along with pro-inflammatory cytokine levels were determined using flow cytometry, ELISA and RT-PCR. Results indicated that the selected oral bacteria have greater effects on oral versus skin epithelial cells. F. nucleatum increased MHC Class II and CD54 (ICAM-1) cell surface expression on HOK-18A and HaCaT cells. A. israelii also had enhancing effects on the expression of CD54 and MHC Class II. A. israelii and LPS induced a 2.8-fold (P < 0.001) and 4.4-fold (P < 0.005) TNF-, secretion, respectively, while F. nucleatum and LPS induced a 10-fold (P < 0.0004) and 6-fold (P < 0.01) IL-1, secretion, respectively by HOK-18A. Interestingly, CD70, CD80, and CD86 were generally decreased upon bacteria and LPS challenge on HOK-18A. The effects of increased MHC Class II and decreased CD70 were also evident with challenge of human periradicular exudate on HOK-18A. The implications of the study are unique in that oral epithelial cells may play both activating and inhibitory roles in the host immune response towards infection by oral bacteria. We introduce a concept of ,dormancy' where the differential expression of key cell surface antigens on oral epithelial cells may keep the recruited immune effector cells in a state of unresponsiveness, thus contributing to the long term quiescent period observed in many periodontal and endodontic lesions. [source] Pooled Human Gammaglobulin Modulates Surface Molecule Expression and Induces Apoptosis in Human B CellsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2003Mieko Toyoda We have previously shown that the pooled human gammaglobulin (IVIG) inhibited mixed lymphocyte reaction (MLR). In this study, we examined (1) if IVIG contains blocking antibodies reactive with cell surface molecules required for alloantigen recognition and (2) if IVIG modulates these surface molecule expressions using flow cytometry. IVIG does not contain significant amounts of blocking antibodies against CD3, CD4, CD8, CD20, CD14, CD40, MHC class I and class II. It reduces the number of intact B cells and monocytes, reduces or modulates CD19, CD20 and CD40 expression on B cells, and induces morphological changes in B cells. This B-cell modulation results primarily because of apoptosis. IVIG also induces apoptosis in T cells and monocytes, but to a lesser degree. Induction of apoptosis requires the intact IgG molecule. Reduction of intact B cell and monocyte cell numbers, modulation of surface molecule expression on B cells, and deletion of B and T cells by apoptosis could result in inhibition of optimal T-cell activation. This likely represents the primary mechanism responsible for IVIG suppression of the MLR, and may account for many of the observed beneficial effects of IVIG seen in the treatment of human autoimmune and alloimmune disorders. [source] Mast cell,derived tryptase inhibits apoptosis of human rheumatoid synovial fibroblasts via rho-mediated signalingARTHRITIS & RHEUMATISM, Issue 4 2010Norifumi Sawamukai Objective An abundance of mast cells are found in the synovium of patients with rheumatoid arthritis (RA). However, the role of mast cells in the pathogenesis of RA remains unclear. This study was undertaken to elucidate a role for mast cells in RA by investigating the antiapoptotic effects of tryptase, a major product of mast cells, on RA synovial fibroblasts (RASFs). Methods RA synovial tissue was obtained from RA patients during joint replacement surgery, and histologic changes in the tissue were examined. The expression of cell surface molecules and apoptotic markers on RASFs were detected by flow cytometry. Rho activation was determined using a pull-down assay. Results Mast cells, bearing both c-Kit and tryptase, accumulated in the sublining area of proliferating synovial tissue from RA patients. Protease-activated receptor 2 (PAR-2), a receptor for tryptase, was expressed on RASFs in the lining area, close to tryptase-positive mast cells in the RA synovium. Fas-mediated apoptosis of RASFs was significantly inhibited, in a dose-dependent manner, by the addition of tryptase, and this effect correlated with increased activation of Rho kinase. Furthermore, Y27632, a Rho kinase inhibitor, reduced the antiapoptotic effect of tryptase on RASFs, suggesting that Rho was responsible for the antiapoptotic effects of tryptase. Conclusion These results demonstrate that tryptase has a strong antiapoptotic effect on RASFs through the activation of Rho. Thus, we propose that the release of tryptase by mast cells leads to the binding of tryptase to PAR-2 on RASFs and inhibits the apoptosis of RASFs via the activation of Rho. Such mechanisms could play a pivotal role in the marked proliferation of RASFs and hyperplasia of synovial tissue seen in RA synovium. [source] HLA,B27 heavy chains distinguished by a micropolymorphism exhibit differential flexibilityARTHRITIS & RHEUMATISM, Issue 4 2010Heinz Fabian Objective Although the products of the HLA subtypes B*2705 and B*2709 differ only in residue 116 (Asp versus His) within their peptide-binding grooves, they are differentially associated with inflammatory rheumatic diseases such as ankylosing spondylitis (AS): B*2705 occurs in AS patients, whereas B*2709 is only rarely encountered. The reasons for this distinct association are still unclear but could include subtype-specific conformational and dynamic properties of these antigens. The present study was undertaken to investigate structural and dynamic differences between B*2705 and B*2709 and their possible relationship to subtype-specific disease association. Methods The membrane-distal segments of the B*2705 and B*2709 heavy chains were expressed in vitro and reconstituted together with ,2 -microglobulin and a peptide. HLA,B27 complexes loaded with 2 self peptides (TIS [RRLPIFSRL] and pVIPR [RRKWRRWHL]) and a sequence-related viral peptide (pLMP2 [RRRWRRLTV]) were studied by isotope-edited infrared spectroscopy to detect differences in their structure and flexibility at physiologic temperature. Results Our analyses revealed the existence of subtype-specific conformational differences between the 2 HLA,B27 heavy chains at physiologic temperature, which are undetectable using x-ray crystallography. Irrespective of the bound peptide, the heavy chain of the B*2705 complex exhibited higher conformational flexibility than the B*2709 heavy chain. Conclusion The present study demonstrates the existence of previously undetected systematic conformational and dynamic differences between the heavy chains of the 2 HLA,B27 subtypes. Since effector cell recognition of cells expressing HLA antigens is dependent on the dynamic properties of the interacting cell surface molecules, this HLA,B27 subtype,specific heavy chain flexibility could have a role in the distinct association of HLA,B27 subtypes with spondylarthritides. [source] Cell-surface matrix proteins and sialic acids in cell-crystal adhesion; the effect of crystal binding on the viability of human CAKI-1 renal epithelial cellsBJU INTERNATIONAL, Issue 6 2003G. Kramer Objective To investigate the role of sialic acids and cellular matrix proteins as crystal-binding molecules in human calcium-oxalate nephrolithiasis. Materials and methods The well-defined human renal cancer cell line CAKI-1 was used a standard cell culture system. After enzymatic digestion of various cell surface molecules, the binding of ,2,6 (Sambucus nigra, SN-) and ,2,3 (Maackia amurensis, MA)-specific lectins to CAKI-1 cells was analysed. Simultaneously, the effect on adhesion and release of calcium oxalate monohydrate crystals was investigated (eight replicates). The effect of crystal adhesion on cell viability was assessed using Trypan blue exclusion (five replicates). Results Neuraminidase decreased MA-lectin binding of CAKI-1 cells by 39% (P < 0.05) but elevated SN-lectin binding by 812% (P < 0.05). Simultaneously, crystal binding to CAKI-1 cells was increased by 28% (P > 0.05). Pretreatment with collagenase type I, trypsin and dispase II reduced crystal-binding by 61,74% (P < 0.05) with no effect on sialic acid-specific lectin-binding. However, only collagenase type I and dispase (ratio 4 : 1) were also able to release crystals from their receptor-binding sites (P < 0.05). An increase in the number of cell surface-bound crystals correlated significantly with a decrease in cell viability (P < 0.05). Conclusions ,2,3-linked sialic acids protect cells from crystal-binding. Much greater SN-lectin binding associated with only moderately increased crystal binding argues against ,2,6-linked sialic acids as a main target structure of crystals. In contrast, collagen type I, type IV and/or fibronectin seem to be potent crystal-binding molecules on human renal epithelial cells, with collagen type I involved in a potential second step of crystal,cell interaction. [source] Modulation of dendritic cell development by immunoglobulin G in control subjects and multiple sclerosis patientsCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 3 2007K. Ohkuma Summary Intravenous immunoglobulin (IVIg) preparations are reportedly effective in inhibiting the relapse of multiple sclerosis (MS), but few reports have investigated the effect of IVIg on dendritic cells (DCs), which are thought to be involved in such relapses. In the system that uses monokines to differentiate DCs from peripheral blood monocytes (Mo-DCs), we investigated the effect of immunoglobulin G (IgG) on these antigen-presenting cells. Using monocytes derived from healthy volunteers, IgG partially inhibited the expression of CD1a, a marker of immature DCs (imDCs), and CD40 and CD80, which are markers associated with T cell activation. In contrast, IgG enhanced the expression of CD83, a marker of mature DCs (mDCs). Furthermore, IgG markedly inhibited the expression of CD49d [very late activation antigen (VLA)-4 ,4-integrin], the adhesion molecule required for mDCs to cross the blood,brain barrier. We obtained similar results on all the aforementioned cell surface molecules investigated in both healthy controls and MS patients. In addition, IgG treatment of cells from both healthy controls and MS patients inhibited the production of interleukin (IL)-12, a cytokine associated with mDC differentiation, but did not inhibit the production of IL-10. These results suggested the possibility that IgG treatment, apart from its known ability to regulate inflammation, may help to prevent relapses of MS by controlling DC maturation, consequently inhibiting invasion of immune cells into the central nervous system and affecting the cytokine profile. [source] | ||||||||||||||||||||||