Lymphocyte Binding Research Articles

Chemical Composition and Protective Possibilities of Juglans Nigra Leaves and Green Husks Extracts: DNA Binding and Micronucleus Assay in Human Lymphocytes.

To better understand the mechanism of action of the compounds in the ethanolic extracts of J. nigra leaves and green husks, their binding to CT-DNA was investigated. This study was conducted to elucidate the in vitro protective effect of extracts against chromosomal damage in mitogen-induced human lymphocytes and investigate the possible application of selec+ted extracts as a natural source of polyphenolic compounds. Using HPLC-MS analysis, 103 different compounds were identified as having a higher number of active species, which is consistent with their activity. The frequency of micronuclei (MN) was scored in binucleated cells, and the nuclear proliferation index was calculated. Cyclic voltammetry experiments demonstrate that the nature of the interaction between extracts and CT-DNA is a synergy of electrostatic and intercalative modes, where leaves extracts showed a higher ability to bind to DNA. Extracts showed excellent antioxidant activity. At a concentration of only 4 µg/mL, extract of J. nigra leaves and the green husks reduced the incidence of MN by 58.2% and 64.5%, respectively, compared to control cell cultures.

Inflammation scintigraphy imaging through a novel antimicrobial peptide labeled with technetium-99m in an animal model

Purpose Antimicrobial peptides (AMPs), due to their biological properties, have great potential for radiopharmaceutical development. In this research, a new antimicrobial peptide, derived from a 21-residue antimicrobial peptide microcinJ25 (MccJ25), was utilized to diagnose inflamed sites in mice bodies after labeling with [99mTc]Tc. Materials and methods An antimicrobial peptide derivative was connected with an efficient chelator, hydrazinonicotinamide, and then labeled with [99mTc]Tc. The binding of labeled microcinJ25 conjugate to lymphocyte was investigated in vitro. Turpentine oil-induced inflammation uptake and tissue distribution were assessed through the animal pattern. Detector scanning was done through scintigraphy post injection of [99mTc]Tc-radiopeptide within different time points. Results High radiochemical purity (>98%) was obtained for [99mTc]Tc-radiopeptide. Lymphocyte binding assessment showed specific cell binding. Binding Inhibition was observed when additional unlabeled conjugate was used. In in vivo biological distribution studies, the uptake for inflamed tissue was 1.52 ± 0.12%ID/g. The inflammation site was visualized by scintigraphy imaging at 1 up to 2 hours. Conclusion Based on our results this new designed [99mTc]Tc-radiopeptide was able to detect inflammation sites early and with high resolution, and could be considered a promising diagnostic candidate in inflammatory diseases.

Differential CTCF binding in motor neurons and lymphocytes

Background: Diversity is critical to lymphocyte roles in the immune system and to neurons, which form complex network structures in the brain. Emerging evidence suggests that an increasing number of molecules associated with the immune system are also expressed in various central nervous system (CNS) regions and play crucial roles in brain development. Examination of shared molecular mechanisms underlying neurogenesis and lymphocyte differentiation may clarify relevant pathways, and suggests additional biomarkers in lymphocytes for neurological disorders. These results can contribute to find biomarkers that can be monitored through patient lymphocyte populations. Methods: We analysed similarities and conserved regions in several genes regulated by CCCTC-binding factor (CTCF) during lymphocyte and neuronal developmental stages. We performed epigenetic analyses of CTCF binding Trak1, Gabpa, Gabpb1, Gabpb2, Gfi1, Gfi1b gene loci in T and B lymphocytes at different developmental stages, as well as in neural progenitor cells and motor neurons. Results: Common and shared CTCF binding events at Trak1 suggest additional transcriptional regulatory factors that control Trak1 gene expression levels differ in neurons and lymphocytes. Gabpb1 includes a common CTCF binding site shared with neurons and lymphocytes. Correlation of CTCF binding analysis and gene expression profile suggests that CTCF binding plays a role in epigenetic regulation of Gabpb1 gene. While Gfi1a is phylogenetically well-conserved and CTCF sites are occupied in lymphocytes, there are no CTCF binding occupied in neurons and neural progenitor cells. Although Gfi1b is highly homologous to Gfi1, differences in expression levels suggest that Gfi1b is critical for both lymphogenesis and neurogenesis. Neurons and lymphocytes have multiple common CTCF binding sites in the Gfi1b gene. Conclusions: The partial overlap in CTCF regulatory sites for some genes in neurons and lymphocytes suggests that there may be markers which can exhibit parallel changes in these cells and serve as biomarkers.

An improved in vitro model for studying the structural and functional properties of the endothelial glycocalyx in arteries, capillaries and veins.

The endothelial glycocalyx is a dynamic structure integral to blood vessel hemodynamics and capable of tightly regulating a range of biological processes (ie, innate immunity, inflammation, and coagulation) through dynamic changes in its composition of the brush structure. Evaluating the specific roles of the endothelial glycocalyx under a range of pathophysiologic conditions has been a challenge in vitro as it is difficult to generate functional glycocalyces using commonly employed 2D cell culture models. We present a new multi-height microfluidic platform that promotes the growth of functional glycocalyces by eliciting unique shear stress forces over a continuous human umbilical vein endothelial cell monolayer at magnitudes that recapitulate the physical environment in arterial, capillary and venous regions of the vasculature. Following 72hours of shear stress, unique glycocalyx structures formed within each region that were distinct from that observed in short (3days) and long-term (21days) static cell culture. The model demonstrated glycocalyx-specific properties that match the characteristics of the endothelium in arteries, capillaries and veins, with respect to surface protein expression, platelet adhesion, lymphocyte binding and nanoparticle uptake. With artery-to-capillary-to-vein transition on a continuous endothelial monolayer, this in vitro platform is an improved system over static cell culture for more effectively studying the role of the glycocalyx in endothelial biology and disease.

Strange blood — The Rise and Fall of Lamb Blood Transfusion in 19th Century Medicine and Beyond Medical Humanities, Volume 5, BoelBerner, (Transcript), 2020. ISBN‐978‐3‐8376‐5163‐8, 214 pages, including notes, sources and literature and an index

This is an interesting little volume seen from several angles. It concerns transfusion (part of the BJH repertoire), but notably it describes how transfusion of lamb's blood became a short-lived fancy among doctors, gaining traction in the 1870s and disappearing within a mere decade Though initially introduced by Riva in Rome in 1667, transfusion of lamb's blood was largely disregarded until the 1870s, when a treatise by Gesellius sought to summarize the literature. Concurrent with this, a series of wars had raised the wish in army doctors to attempt transfusions, most notably in the German Dr. Hasse from Nordhausen, who had served during the war with Denmark in 1864 and against France in 1870. Though blood from lambs had been used for humans every now and then, largely due to its easy availability and the fact that sheep red blood cells are smaller than their human counterparts, Dr. Hasse did significant scaling up and wrote his own book about it. The latter initiated a wave of lamb transfusions for a number of diseases in many Western countries. This book entertainingly describes these developments, both with respect to indications, techniques and actual procedures. In these troubled times, where nostrums for COVID-19 gain rapid and sometimes premature application, it is instructive to see how fast the idea and application of lamb blood transfusions spread. It is salutary in turn to find how quickly the practice disappeared. Although the author has a non-medical background, she has succeeded in amply describing the nature of the transfusion reactions seen. My first research project, in the mid-1970s, was to improve the E-rosette test, which measured the binding of human lymphocytes to sheep red blood cells and served as gold standard for identifying T cells. Reading about the sometimes dramatic reactions to even small volumes of lamb blood, I could not help wondering whether these were due to in vivo E-rosetting! Surprisingly, xenogeneic transfusion got a further but very brief renaissance in the 1890s as part of the serotherapy revolution, which culminated in Behring's tetanus antisera. It would have been instructive if the book had bridged that event and finished with Landsteiner's discoveries of blood groups in 1901 and 1909 which became the true foundation for today's transfusion medicine. Nevertheless, this is a good yarn, showing us how new treatments, also in the 19th century, were touted and ultimately ridiculed.

Proceeding of the European Group for Blood and Marrow Transplantation (EBMT) congress on sickle cell disease, 16–17 may 2019, Regensburg, Germany: What is the impact of antithymocyte globulin pharmacokinetics on haploidentical hematopoietic stem cell transplantation?

Antithymocyte globulin (ATG) is a widely accepted part of the conditioning regimen applied in the setting of hematopoietic stem cell transplantation (HSCT) to prevent graft rejection and graft-versus-host disease. Although weight-based dosing of ATG has been introduced to optimize ATG dosing, substantial variance in clearance of active ATG, the actual lymphocyte binding component, remains a challenge. Therefore, further research regarding ATG pharmacokinetics and pharmacodynamics in different HSCT settings and in patients with different types of underlying diseases is required.

Genome-Wide Measurement and Computational Analysis of Transcription Factor Binding and Chromatin Accessibility in Lymphocytes.

Cells of the adaptive immune system, including CD4+ and CD8+ T cells, as well as B cells, possess the ability to undergo dynamic changes in population size, differentiation state, and function to counteract diverse and temporally stochastic threats from the external environment. To achieve this, lymphocytes must be able to rapidly control their gene-expression programs in a cell-type-specific manner and in response to extrinsic signals. Such capacity is provided by transcription factors (TFs), which bind to the available repertoire of regulatory DNA elements in distinct lymphocyte subsets to program cell-type-specific gene expression. Here we provide a set of protocols that utilize massively parallel sequencing-based approaches to map genome-wide TF-binding sites and accessible chromatin, with consideration of the unique aspects and technical issues facing their application to lymphocytes. We show how to computationally validate and analyze aligned data to map differentially enriched/accessible sites, identify enriched DNA sequence motifs, and detect the position of nucleosomes adjacent to accessible DNA elements. These techniques, when applied to immune cells, can enhance our understanding of how gene-expression programs are controlled within lymphocytes to coordinate immune function in homeostasis and disease. © 2019 by John Wiley & Sons, Inc.

Continuous preparation and characterization of immunomodulatory peptides from type II collagen by a novel immobilized enzyme membrane reactor with improved performance.

In this study, a novel method of continuous coupling of immobilized enzymatic hydrolysis reactor and membrane separation (CIEH-MS) was used to isolate the immunomodulatory peptides from type II collagen (CII) in chick sternal cartilage. The immobilized neutral protease was successfully prepared with an activity of 400.5 U/g. The CIEH-MS system loaded with immobilized neutral protease had high operational stability with enzyme decay constant of 0.0077 and half-life of 89.61hr. Using a CIEH-MS system, the immunomodulatory peptides were obtained with lymphocyte proliferation of 66.23%, peptide yield of 23.43%, degree of hydrolysis (DH) of 22.41%, and permeate flux of 6.17 L/m2 h. The peptide fractions were further purified and the P3-2-4 fraction (RGQLGPM) with 760.4Da molecular weights exhibited the highest lymphocyte proliferation activity (85.54%) and binding ability to human leukocyte antigen-DRB1 (HLA-DRB1) molecules (133.2ng/ml). The results demonstrated that CIEH-MS system is an effective way to obtain immunomodulatory peptides from CII. PRACTICAL APPLICATIONS: Chick sternal cartilage is one of the by-products of meat processing, and it is often discarded as waste or used for low-value purposes. CII is the most abundant collagen in chick sternal cartilage, and recently studies have demonstrated that CII peptides possess the ability to induce immunologic tolerance for the treatment of chronic disease. In order to find potential applications for this by-product, immunomodulatory peptides from CII hydrolysates in chick sternal cartilage were isolated using a novel CIEH-MS system. The result showed that CII peptides exhibited a high immunomodulatory activity, and had a potential application in functional foods and medical fields.

Differential Elimination of Anti-Thymocyte Globulin of Fresenius and Genzyme Impacts T-Cell Reconstitution After Hematopoietic Stem Cell Transplantation.

Anti-thymocyte globulin (ATG) is a lymphocyte depleting agent applied in hematopoietic stem cell transplantation (HSCT) to prevent rejection and Graft-vs.-Host Disease (GvHD). In this study, we compared two rabbit ATG products, ATG-Genzyme (ATG-GENZ), and ATG-Fresenius (ATG-FRES), with respect to dosing, clearance of the active lymphocyte binding component, post-HSCT immune reconstitution and clinical outcome. Fifty-eigth pediatric acute leukemia patients (n = 42 ATG-GENZ, n = 16 ATG-FRES), who received a non-depleted bone marrow or peripheral blood stem cell graft from an unrelated donor were included. ATG-GENZ was given at a dosage of 6–10 mg/kg; ATG-FRES at 45–60 mg/kg. The active component of ATG from both products was cleared at different rates. Within the ATG-FRES dose range no differences were found in clearance of active ATG or T-cell re-appearance. However, the high dosage of ATG-GENZ (10 mg/kg), in contrast to the low dosage (6–8 mg/kg), correlated with prolonged persistence of active ATG and delayed T-cell reconstitution. Occurrence of serious acute GvHD (grade III–IV) was highest in the ATG-GENZ-low dosage group. These results imply that dosing of ATG-GENZ is more critical than dosing of ATG-FRES due to the difference in clearance of active ATG. This should be taken into account when designing clinical protocols.

Aggregating resistant Staphylococcus aureus induces hypocoagulability, hyperfibrinolysis, phagocytosis, and neutrophil, monocyte, and lymphocyte binding in canine whole blood.

Staphylococcus aureus is an opportunistic pathogen with the ability to form mobile planktonic aggregates during growth, in vitro. The in vivo pathophysiologic effects of Saureus aggregates on host responses are unknown. Knowledge of these could aid in combating infections. This study aimed to investigate the effect of increasing concentrations of two different aggregating Saureus strains on the hemostatic and inflammatory host responses in canine whole blood. The hypothesis was that aggregating bacteria would induce pronounced hemostatic and inflammatory responses. Citrate-stabilized whole blood from 10 healthy dogs was incubated with two strains of aggregating Saureus at three different concentrations. Each sample was analyzed using tissue factor-thromboelastography (TF-TEG) and the formed clot was investigated with electron microscopy. The plasma activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, and D-dimer tests were measured. Bacteria-leukocyte binding was evaluated with flow cytometry, and neutrophil phagocytosis was assessed using light and transmission electron microscopy. The highest concentration of bacteria resulted in a significantly shortened TF-TEG initiation time, decreased alpha, maximum amplitude, global strength, and increased lysis. In addition, significantly shortened PT, decreased fibrinogen, and increased D-dimers were demonstrated at the highest concentration of bacteria. Lower concentrations of bacteria showed no differences in TF-TEG when compared with controls. The findings were similar for both Saureus strains. Increased concentration-dependent binding of bacteria and leukocytes and neutrophil bacterial phagocytosis was observed. Two strains of Saureus induced alterations of clot formation in concentrations where bacterial aggregates were formed. A concentration-dependent cellular inflammatory response was observed.

Active Ingredients of Epimedii Folium and Ligustri Lucidi Fructus Balanced GR/HSP90 to Improve the Sensitivity of Asthmatic Rats to Budesonide

This study aimed to investigate the possible molecular mechanisms of active ingredients of Epimedii Folium (EF) and Ligustri Lucidi Fructus (LLF) combined with Budesonide (Bun) in asthmatic rats. Rats were divided into 5 groups, including normal group, asthma model group, Bun group, group of active ingredients of EL and LLF (EL), and group of coadministration of Bun with EL (Bun&EL). The asthmatic model was prepared by ovalbumin sensitizing and challenging. Lymphocyte apoptosis, GR protein and binding, and the protein and mRNA of GRα, GRβ, and HSP90 were tested. The results showed that Bun&EL ① markedly increased lymphocyte apoptosis, GR and HSP90 protein, and GR binding in BALF and ② enhanced the expressions of GRα and HSP90 and the ratio of GRα to GRβ or to HSP90 both in protein and in mRNA levels in lung, ③ while decrease occurred in GRβ mRNA and the mRNA ratio of GRβ to HSP90 compared with asthma or Bun group. Moreover, there was a significant correlation between GRα and GRβ in protein level, or between GRα and HSP90 both in protein and in mRNA levels. EL may effectively enhance the sensitivity of asthmatic rats to Bun via balancing GR/HSP90. And these findings will be beneficial for the treatment of asthma in the future.

Determination of morphology and immunophenotype of circulating lymphoma cells in patients with splenic marginal zone lymphoma using an anti-CD antibody microarray

We have studied the morphology and immunophenotype of circulating tumor cells isolated from peripheral blood of 22 patients with splenic marginal zone lymphoma and show that both of them are highly heterogeneous. Using a cell-binding microarray we have demonstrated that the circulating lymphoma cells are positive for CD19 (100 %), CD20 (100 %), CD22 (100 %), surface IgM (73 %), CD38 (23 %), CD5 (9 %), CD11c (36 %), CD103 (5 %), CD25 (32 %), CD23 (23 %) and these immunophenotypes are confirmed in all cases by flow cytometry. Higher surface density of lymphocyte binding onto anti-CD antibody microarray spots compared to blood smears permits to find circulating lymphoma cells even in leukopenic patients.

Rapid activation of lymph node lymphangiogenesis (IRC4P.458)

Abstract The lymphatic system delivers fluid and molecules from tissues to the lymph node (LN) to mediate immune system surveillance of self and foreign antigens. LN lymphatic endothelial cells (LECs) function in orchestration of the immune response, and in reinforcement of peripheral tolerance. Extensive LN lymphatic sinus growth (lymphangiogenesis) is involved in multiple diseases including cancer, arthritis, and inflammation. Lymphocytes and leukocytes regulate this lymphangiogenesis; however, the mechanism is not well defined. We identified a monoclonal antibody (10.1.1) that recognizes the LEC protein mCLCA1. Our studies identified mCLCA1 as an interacting partner for LFA-1 and Mac-1 that mediates lymphocyte and leukocyte adhesion. The 10.1.1 Ab blocks adhesion of lymphocytes to LECs in vitro to a greater extent than ICAM-1 neutralizing Ab, suggesting that while ICAM-1 interactions predominate in vascular endothelium, mCLCA1 interaction is more important for adhesion to LECs. In addition to mediating adhesion, the 10.1.1 Ab (but not control Ab) induces rapid LN lymphangiogenesis within 23 hours after injection into mice, which involves proliferation of LN LECs. This lymphangiogenesis is accompanied by LN remodeling involving multiple stromal cell types, resembling the LN response to inflammation. These findings suggest that 10.1.1 Ab mimics lymphocyte or leukocyte B2-integrin binding to LEC mCLCA1, to drive LN remodeling and lymphangiogenesis during immune responses.

FOXO1 regulates dendritic cell activity through ICAM-1 and CCR7.

The transcription factor FOXO1 regulates cell function and is expressed in dendritic cells (DCs). We investigated the role of FOXO1 in activating DCs to stimulate a lymphocyte response to bacteria. We show that bacteria induce FOXO1 nuclear localization through the MAPK pathway and demonstrate that FOXO1 is needed for DC activation of lymphocytes in vivo. This occurs through FOXO1 regulation of DC phagocytosis, chemotaxis, and DC-lymphocyte binding. FOXO1 induces DC activity by regulating ICAM-1 and CCR7. FOXO1 binds to the CCR7 and ICAM-1 promoters, stimulates CCR7 and ICAM-1 transcriptional activity, and regulates their expression. This is functionally important because transfection of DCs from FOXO1-deleted CD11c.Cre(+)FOXO1(L/L) mice with an ICAM-1-expressing plasmid rescues the negative effect of FOXO1 deletion on DC bacterial phagocytosis and chemotaxis. Rescue with both CCR7 and ICAM-1 reverses impaired DC homing to lymph nodes in vivo when FOXO1 is deleted. Moreover, Ab production following injection of bacteria is significantly reduced with lineage-specific FOXO1 ablation. Thus, FOXO1 coordinates upregulation of DC activity through key downstream target genes that are needed for DCs to stimulate T and B lymphocytes and generate an Ab defense to bacteria.

Natalizumab treatment in multiple sclerosis

Multiple sclerosis is a neurodegenerative and inflammatory immune disorder in the central nervous system (CNS). Most patients show relapse-remitting clinical course. Some disease modifying medications for preventing the relapses including natalizumab (NTZ) are approved in Japan. Natalizumab (NTZ), a monoclonal antibody against α4 integrin present on the surface of lymphocytes, inhibits the binding of lymphocytes to vascular cell adhesion molecule-1 (VCAM-1) of endothelial cells and blocks the penetration of encephalitogenic T cells into the CNS. This review provides an update on the efficacy of an inhibition of relapses, adverse effects including progressive multifocal leukoencephalopathy, treatment after NTZ discontinuation, and body weight based treatment.

Clever-1/stabilin-1 controls cancer growth and metastasis.

Immunosuppressive leukocytes and vasculature are important host cell components regulating tumor progression. Clever-1/Stabilin-1, a multifunctional scavenger and adhesion receptor, is constitutively present on a subset of type II macrophages and lymphatic endothelium, but its functional role in cancer is unknown. Here, we generated full Clever-1 knockout mice and cell-specific ones lacking Clever-1 either on macrophages or endothelium. We also used anti-Clever-1 antibody therapy to treat B16 melanoma and EL-4 lymphoma. Clever-1-deficient mice had smaller primary and metastatic tumors than wild-type (WT) controls. Growth of primary tumors, but not of metastases, was attenuated also in mice lacking Clever-1 selectively in macrophages or in vascular endothelium. Anti-Clever-1 antibody treatment inhibited tumor progression in WT mice. Both genetically and therapeutically induced absence of functional Clever-1 led to diminished numbers of immunosuppressive leukocyte types in tumors. Functionally Clever-1 mediated binding of immunosuppressive leukocytes to the intratumoral blood vessels aberrantly expressing Clever-1, and tumor cell traffic via the lymphatics. The antibody therapy did not aggravate autoimmunity. This work identifies Clever-1 in type II macrophages and in tumor vasculature as a new immunosuppressive molecule in cancer. Our finding that Clever-1 supports binding of tumor-infiltrating lymphocytes to tumor vasculature increases our understanding of leukocyte immigration to tumors. The ability of anti-Clever-1 antibody treatment to attenuate tumor progression in WT mice in vivo is therapeutically relevant. Thus, Clever-1 may be an emerging new target for modulating immune evasion and lymphatic spread in cancer.

Inhibition of Hyaluronan Synthesis Protects against Central Nervous System (CNS) Autoimmunity and Increases CXCL12 Expression in the Inflamed CNS

Hyaluronan (HA) may have proinflammatory roles in the context of CNS autoimmunity. It accumulates in demyelinated multiple sclerosis (MS) lesions, promotes antigen presentation, and enhances T-cell activation and proliferation. HA facilitates lymphocyte binding to vessels and CNS infiltration at the CNS vascular endothelium. Furthermore, HA signals through Toll-like receptors 2 and 4 to stimulate inflammatory gene expression. We assessed the role of HA in experimental autoimmune encephalomyelitis (EAE), an animal model of MS by administration of 4-methylumbelliferone (4MU), a well established inhibitor of HA synthesis. 4MU decreased hyaluronan synthesis in vitro and in vivo. It was protective in active EAE of C57Bl/6 mice, decreased spinal inflammatory infiltrates and spinal infiltration of Th1 cells, and increased differentiation of regulatory T-cells. In adoptive transfer EAE, feeding of 4MU to donor mice significantly decreased the encephalitogenicity of lymph node cells. The transfer of proteolipid protein (PLP)-stimulated lymph node cells to 4MU-fed mice resulted in a delayed EAE onset and delayed spinal T-cell infiltration. Expression of CXCL12, an anti-inflammatory chemokine, is reduced in MS patients in CSF cells and in spinal cord tissue during EAE. Hyaluronan suppressed production of CXCL12, whereas 4MU increased spinal CXCL12 in naive animals and during neuroinflammation. Neutralization of CXCR4, the most prominent receptor of CXCL12, by administration of AMD3100 diminished the protective impact of 4MU in adoptive transfer EAE. In conclusion, hyaluronan exacerbates CNS autoimmunity, enhances encephalitogenic T-cell responses, and suppresses the protective chemokine CXCL12 in CNS tissue. Inhibition of hyaluronan synthesis with 4MU protects against an animal model of MS and may represent an important therapeutic option in MS and other neuroinflammatory diseases.

The old but new IgM Fc receptor (FcμR).

IgM is the first Ig isotype to appear during phylogeny, ontogeny and the immune response. The importance of both pre-immune "natural" and antigen-induced "immune" IgM antibodies in immune responses to pathogens and self-antigens has been established by studies of mutant mice deficient in IgM secretion. Effector proteins interacting with the Fc portion of IgM, such as complement and complement receptors, have thus far been proposed, but fail to fully account for the IgM-mediated immune protection and regulation of immune responses. Particularly, the role of the Fc receptor for IgM (FcμR) in such effector functions has not been explored until recently. We have identified an authentic FcμR in humans using a functional cloning strategy and subsequently in mice by RT-PCR and describe here its salient features and the immunological consequences of FcμR deficiency in mice. Since the FcμR we cloned was identical to Toso or Fas inhibitory molecule 3 (FAIM3), there have been spirited debates regarding the real function of FcμR/Toso/FAIM3 and we will also comment on this topic.

Dynamic Changes in Endothelial Cell Adhesion Molecule Nepmucin/CD300LG Expression under Physiological and Pathological Conditions

Vascular endothelial cells often change their phenotype to adapt to their local microenvironment. Here we report that the vascular endothelial adhesion molecule nepmucin/CD300LG, which is implicated in lymphocyte binding and transmigration, shows unique expression patterns in the microvascular endothelial cells of different tissues. Under physiological conditions, nepmucin/CD300LG was constitutively and selectively expressed at the luminal surface of the small arterioles, venules, and capillaries of most tissues, but it was only weakly expressed in the microvessels of the splenic red pulp and thymic medulla. Furthermore, it was barely detectable in immunologically privileged sites such as the brain, testis, and uterus. The nepmucin/CD300LG expression rapidly decreased in lymph nodes receiving acute inflammatory signals, and this loss was mediated at least in part by TNF-α. It was also down-regulated in tumors and tumor-draining lymph nodes, indicating that nepmucin/CD300LG expression is negatively regulated by locally produced signals under these circumstances. In contrast, nepmucin/CD300LG was induced in the high endothelial venule-like blood vessels of chronically inflamed pancreatic islets in an animal model of non-obese diabetes. Interestingly, the activated CD4+ T cells infiltrating the inflamed pancreas expressed high levels of the nepmucin/CD300LG ligand(s), supporting the idea that nepmucin/CD300LG and its ligand interactions are locally involved in pathological T cell trafficking. Taken together, these observations indicate that the nepmucin/CD300LG expression in microvascular endothelial cells is influenced by factor(s) that are locally produced in tissues, and that its expression is closely correlated with the level of leukocyte infiltration in certain tissues.

How T cells trigger the dissociation of the endothelial receptor phosphatase VE-PTP from VE-cadherin

AbstractThe vascular endothelial (VE) receptor protein tyrosine phosphatase (VE-PTP) associates with VE-cadherin and supports endothelial cell contact integrity. This complex is rapidly dissociated by adhesion of leukocytes to endothelial cells or by vascular endothelial growth factor. We have shown recently that this dissociation is indeed required for the opening of endothelial cell contacts during leukocyte extravasation in vivo. The leukocyte receptor and signaling mechanism that stimulates VE-cadherin/VE-PTP dissociation are unknown. Here, we identify vascular cell adhesion molecule 1 as the relevant receptor for lymphocytes in this process. As signaling steps downstream of this receptor, we determined the activation of Rac1, the generation of reactive oxygen species by nicotinamide adenine dinucleotide phosphate oxidase and the activation of the redox-sensitive tyrosine kinase Pyk2 as essential for VE-cadherin/VE-PTP dissociation. These signaling steps are also required for the dissociation induced by VE growth factor. Searching for the molecular mechanism of complex dissociation, we found that a model substrate of VE-PTP represented by a tyrosine-phosphorylated peptide of Tie-2 dissociates VE-PTP from VE-cadherin when introduced with the help of a Tat peptide. We suggest that lymphocyte binding to vascular cell adhesion molecule 1 triggers a signaling process that enables a VE-PTP substrate to dissociate VE-PTP from VE-cadherin, thereby facilitating efficient transmigration.