Reduced Immune Response to Borrelia burgdorferi in the Absence of �æ� T Cells

Little is known regarding the function of γδ T cells, although they accumulate at sites of inflammation in infections and autoimmune disorders. We previously observed that γδ T cells in vitro are activated by Borrelia burgdorferi in a TLR2-dependent manner. We now observe that the activated γδ T cells can in turn stimulate dendritic cells in vitro to produce cytokines and chemokines that are important for the adaptive immune response. This suggested that in vivo γδ T cells may assist in activating the adaptive immune response. We examined this possibility in vivo and observed that γδ T cells are activated and expand in number during Borrelia infection, and this was reduced in the absence of TLR2. Furthermore, in the absence of γδ T cells, there was a significantly blunted response of adaptive immunity, as reflected in reduced expansion of T and B cells and reduced serum levels of anti-Borrelia antibodies, cytokines, and chemokines. This paralleled a greater Borrelia burden in γδ-deficient mice as well as more cardiac inflammation. These findings are consistent with a model of γδ T cells functioning to promote the adaptive immune response during infection.     

Function of Helper T Cells in the Memory CTL-mediated Anti-tumor Immunity

CD4 Tcellsarerequiredforthegenerationandmainte nanceofcytolyticCD8 Tcellsandareessentialforthe generationofbothcellularandhumoralimmuneresponses. However,thecontributionofCD4 Tcellstothemainte nanceofanti tumorimmunityisstillthesubjectofintense investig…     

Differentiated Epidermal Cells Regain the Ability to Regenerate a Skin Equivalent by Increasing the Level of β-Catenin in the Cells

Epidermal stem cells are of major importance for skin regeneration and tissue engineering, but differentiated epidermal cells lost their proliferative capacity and are no longer able to regenerate a skin equivalent. Here, we investigated the role of β-catenin in regulating regenerative functions of differentiated epidermal cells. Lithium chloride and a highly specific glycogen synthase kinase (GSK)-3β inhibitor were applied to induce the expression of β-catenin in differentiated epidermal cells. After a 6-day induction, the large flat-shaped cells with a small nuclear-cytoplasmic ratio had changed into small round-shaped cells with a large nuclear-cytoplasmic ratio. Phenotypic assays showed a remarkably higher expression of CK19, β(1)-integrin, Oct4 and Nanog in induced cells than in the control group (p < 0.01). In addition, the results of growth and functional investigations demonstrated that the induced epidermal cells exhibited a high colony-forming ability, a long-term proliferative potential and the ability to regenerate a skin equivalent, which were regarded as the most important features of epidermal stem cells. These results suggest that the activation of β-catenin favors the reversion or dedifferentiation of differentiated epidermal cells to an immature or a less differentiated state. This study may also offer a new approach to yield enough epidermal stem cells for skin regeneration and tissue engineering.     

A Comparative Study of the JAM Test and 51Cr‐Release Assay to Assess the Cytotoxicity of Dendritic Cells on Hematopoietic Tumor Cells

Dendritic cells (DCs) are potent antigen presenting cells and possess a direct anti‐tumor cytotoxic ability. Nevertheless, the mechanism of anti‐tumor cytotoxicity by DCs and the methods for its evaluation are not fully elucidated. In order to clarify this mechanism of cytotoxicity, we examined the ability of DCs 1) to suppress [³H] thymidine (³H‐TdR) uptake by tumor cells; 2) to induce cytolysis on ⁵¹Cr‐labeled tumor cells; 3) and to induce DNA fragmentation on ³H‐TdR labeled tumor cells (JAM test). Cytolysis and DNA fragmentation are markers of necrotic and apoptotic mechanisms of cytotoxicity in vitro, respectively. DCs inhibited approximately 38.6% to 54.8% of the growth of B4D6, NB4, U937, and Daudi cells as evaluated by the uptake of ³H‐TdR. However no cytolysis was verified by ⁵¹Cr‐release assay. On the other hand, cytotoxicity rates found using the JAM test ranged from 3 to 81% depending on the cell line and the effector to target cell ratio. The discrepancy of cytotoxicity between ⁵¹Cr‐release assay and the JAM test may be due to the phagocytosis of apoptotic tumor cells or the absorption of released ⁵¹Cr by DCs surrounding the target cells. In conclusion, the JAM test was more sensitive than the 4‐h and the 10‐h ⁵¹Cr‐release assay to investigate cytotoxicity mediated by DCs toward hematopoietic tumor cell lines in vitro.     

Accumulation of Activated Invariant Natural Killer T Cells in the Tumor Microenvironment after α-Galactosylceramide-Pulsed Antigen Presenting Cells

Purpose

The intravenous administration of α-Galactosylceramide (α-GalCer)-pulsed antigen presenting cells (APCs) is well tolerated and the increased IFN-γ producing cells in the peripheral blood after the treatment appeared to be associated with prolonged survival. An exploratory study protocol was designed with the preoperative administration of α-GalCer-pulsed APCs to clarify the mechanisms of these findings, while especially focusing on the precise tumor site.

Methods

Patients with operable advanced lung cancer received an intravenous injection of α-GalCer-pulsed APCs before surgery. The resected lung and tumor infiltrating lymphocytes (TILs) as well as peripheral blood mononuclear cells were collected and the invariant NKT (iNKT) cell-specific immune responses were analyzed.

Results

Four patients completed the study protocol. We observed a significant increase in iNKT cell numbers in the TILs and augmented IFN-γ production by the α-GalCer-stimulated TILs.

Conclusion

The administration of α-GalCer-pulsed APCs successfully induced the dramatic infiltration and activation of iNKT cells in the tumor microenvironment.     

Research of the Effect of the Shear Stress on Endothelial Cells

1 IntroductionCellular mechanism is one of the foundations of regenerating medicine and tissue engineering, which is also an advanced subject in cell mechanism in recent years~([1]). The form and function of a cell, and the growing, reproducing and death, even canceration are related to the characteristics of cell mechanism. While the research of the shear stress on endothelial cells is an important field in cell mechanism. The main bio-functions of endothelial cells are as follows: anti-cruor…     

Do Regulatory T Cells Play a Role in the Control of Homeostatic Proliferation?

The control of peripheral lymphocyte numbers is a fundamental aspect of the immune system. Regulatory T cells are involved in the suppression of autoimmune, antitumor, allergic, and other inflammatory responses, as well as in facilitating graft acceptance. In this paper, we discuss whether the control of homeostatic proliferation is another facet of the immune system that is controlled by regulatory T cells. A review of the published data connecting regulatory T cells with the control of homeostatic proliferation indicates that several key questions remain open. One of these relates to the stage at which regulatory T cells could play a role (i.e., T-cell proliferation vs. survival).     

CD4+CD7− T Cells: A Separate Subpopulation of Memory T Cells?

The CD7 molecule is apparently involved in T cell activation but is absent in a substantial subpopulation of human T cells under physiological and certain pathological conditions. The majority of CD7^– T cells expresses TCR / and is of CD4⁺ helper and CD45R0⁺CD45RA^– memory phenotype. After birth, percentages and absolute numbers of circulating CD7^– T cells increase significantly during aging. A number of molecules thought to be involved in organ-specific T cell homing are preferentially expressed within the subset of CD4⁺CD7^– T cells. Specific absence of CD7 antigen expression on T cells is observed in a variety of pathologic conditions such as cutaneous T cell lymphoma, HIV infection, rheumatoid arthritis, and kidney transplantation. Current in vitro results suggest that specific downregulation of CD7 antigen expression in T cells reflects a separate and stable differentiation state occurring late in the immune response. Expansion of CD7^– T cells in vivo has been found in certain diseases associated with chronically repeated T cell stimulation. The potential pathophysiological significance of this T cell subset in certain human diseases is discussed.     

Early Reconstitution of NK and γδ T Cells and Its Implication for the Design of Post-Transplant Immunotherapy

Relapse is the most frequent cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Natural killer (NK) cells and γδ T cells reconstitute early after allo-HSCT, contribute to tumor immunosurveillance via major histocompatibility complex–independent mechanisms and do not induce graft-versus-host disease. Here we performed a quantitative and qualitative analysis of the NK and γδ T cell repertoire in healthy individuals, recipients of HLA-matched sibling or unrelated donor allo-HSCT (MSD/MUD-HSCT) and umbilical cord blood-HSCT (UCB-HSCT). NK cells are present at high frequencies in all allo-HSCT recipients. Immune reconstitution (IR) of vδ2⁺?cells depended on stem cell source. In MSD/MUD-HSCT recipients, vδ2⁺?comprise up to 8% of the total lymphocyte pool, whereas vδ2⁺?T cells are barely detectable in UCB-HSCT recipients. Vδ1⁺?IR was driven by CMV reactivation and was comparable between MSD/MUD-HSCT and UCB-HSCT. Strategies to augment NK cell mediated tumor responses, similar to IL-15 and antibodies, also induced vδ2⁺?T cell responses against a variety of different tumor targets. Vδ1⁺?γδ T cells were induced less by these same stimuli. We also identified elevated expression of the checkpoint inhibitory molecule TIGIT (T cell Ig and ITIM domain), which is also observed on tumor-infiltrating lymphocytes and epidermal γδ T cells. Collectively, these data show multiple strategies that can result in a synergized NK and γδ T cell antitumor response. In the light of recent developments of low-toxicity allo-HSCT platforms, these interventions may contribute to the prevention of early relapse.     

Cytochemical Demonstration of Calcium in the Chromaffin Cells

Available studies have shown that the secretion of the chromaffin cells evoked by nicotinic agents is related to the influx of extracellular calcium. The present investigation attempt to localize the intracellular calcium in adrenal and extra-adrenal chromaffin cells by employing pyroantimonate technique. The adrenal medulla from male adult rats and newborn rabbits and the para-aortic body     

Antigen-Driven Clonal Accumulation of Peritoneal γδ T Cells in vivo

How the clonality of γδ T cells changes in response to exogenous antigens is uncertain. Here we analyzed kinetics of Vγ1.1 and Vγ2 T cell clonality after intraperitoneal injection of purified protein derivatives (PPD) by the heterogeneity of the third complementarity determining region (CDR3) length in Vγ1.1-Jγ4-Cγ4 and Vγ2-Jγ1-Cγ1 junctions. The V-J junctions were analyzed in intrahepatic lymphocytes (IHL), spleen cells, and peritoneal exudate cells (PEC) by polyacrylamide gel electrophoresis. γδ T cells expressing Vγ1.1 and Vγ2 genes were heterogeneous in normal mice. Accumulation of specific Vγ1.1 T cell clones was transiently detected 7 days after the injection in PEC, but no accumulation was observed in IHL and spleen cells. The accumulated clones disappeared by 4 weeks. Transient accumulation of Vγ2 T cell clones was also observed in PEC at the early phase after the injection. These results suggest that γδ T cells with specific TCR respond to PPD and temporary accumulate in the peritoneal cavity, but not in liver and spleen.     

Complementary Function of γδ T-Lymphocytes and Dendritic Cells in the Response to Isopentenyl-Pyrophosphate and Lipopolysaccharide Antigens

Dendritic cells and γδ T-lymphocytes play a crucial role in the early response to microbial infections. Since both dendritic cells and γδ T-lymphocytes may be activated by specific microbial products, we analyzed their interplay in the presence of such respective ligands: lipopolysaccharide and isopentenyl-pyrophosphate. Activated γδ T-cells increased the maturational state of dendritic cells induced by lipopolysaccharide, increasing the expression of co-stimulatory and MHC class I and II molecules. IL-12 production by dendritic cells was strongly amplified in the presence of activated γδ T-cells and the Th1 polarization of naïve CD4⁺ T-lymphocytes was significantly increased. On the other hand, dendritic cells enhanced γδ T-cell functions induced by isopentenyl-pyrophosphate and promote their IL-2 independent proliferation through CD86 contact. Altogether, dendritic cells and γδ T-cells exert a complementary function promoting an optimal immune response to non peptidic microbial antigens.These authors contributed equally to the work.     

Generation and Regulation of CD8＋ Regulatory T Cells

Research into the suppressive activity of CD4＋FoxP3＋ T regulatory cells （Treg） has defined a sublineage of CD4＋ cells that contribute to self-tolerance and resistance to autoimmune disease. Much less attention has been given to the potential contribution of regulatory sublineages of CD8＋ cells. Analysis of a small fraction of CD8＋ cells that target autoreactive CD4＋ cells through recognition of the MHC class Ib molecule Qa-1 in mouse and HLA-E in human has revitalized interest in CD8＋ Treg. Here we summarize recent progress and future directions of research into the role of this CD8＋ sublineage in resistance to autoimmune disease. Cellular ＆ Molecular Immunology. 2008; 5（6）：401-406.     

Self-Reactive CD4+ T Cells and B Cells in the Blood in Health and Autoimmune Disease: Increased Frequency of Thyroglobulin-Reactive Cells in Graves’ Disease

The mechanisms underlying activation of potentially self-reactive circulating B cells and T cells remain unclear. We measured the uptake of a self-antigen, thyroglobulin, by antigen presenting cells, and the subsequent proliferation of CD4⁺ T cells and B cells from healthy controls and patients with autoimmune thyroiditis. In Hashimoto's thyroiditis, B cells bound increased amounts of thyroglobulin in a complement- and autoantibody-dependent manner, and the thyroglobulin-elicited proliferation of CD4⁺ T cells and B cells was complement dependent. Increased proportions of Tg-responsive CD4⁺ T cells and B cells were found in patients with Graves’ disease. Notably, both patient groups and healthy controls exhibited higher proliferative responses to thyroglobulin than to a foreign recall antigen, tetanus toxoid. Our results suggest that self-tolerance can be broken by exposure of circulating lymphocytes to high local concentrations of self-antigen, and that complement plays a role in the maintenance of autoimmune processes, at least in Hashimoto's thyroiditis.     

Quantitative BOLD response of the renal medulla to hyperoxic challenge at 1.5 T and 3.0 T

The aim of this study was to gage the magnitude of changes of the apparent renal medullary transverse relaxation time (ΔT₂*) induced by inhalation of pure oxygen (O₂) or carbogen (95% O₂, 5% CO₂) versus baseline breathing of room air. Eight healthy volunteers underwent 2D multi‐gradient echo MR imaging at 1.5 T and 3.0 T. Parametrical T₂* relaxation time maps were computed and average T₂* was measured in regions of interest placed in the renal medulla and cortex. The largest T₂* changes were measured in the renal medulla, with a relative ?T₂* of 33.8 ± 22.0% (right medulla) and 34.7 ± 17.6% (left medulla) as compared to room air for oxygen breathing (p > 0.01), and 53.8 ± 23.9% and 53.5 ± 33.9% (p < 0.01) for carbogen breathing, respectively at 3 T. At 1.5 T, the corresponding values were 13.7 ± 18.5% and 24.1 ± 17.1% (p < 0.01) for oxygen breathing and 23.9 ± 17.2% and 38.9 ± 37.6% (p < 0.01) for carbogen breathing. As a result, we showed that renal medullary T₂* times responded strongly to inhalation of hyperoxic gases, which may be attributed to the hypoxic condition of the medulla and subsequent reduction in deoxyhemoglobin. Copyright © 2012 John Wiley & Sons, Ltd.     

γδ T Lymphocytes—Selectable Cells Within the Innate System?

Lymphocytes expressing γδ T cell receptors (TCR) constitute an entire system of functionally specialized subsets that have been implicated in the regulation of immune responses, including responses to pathogens and allergens, and in tissue repair. The γδ TCRs share structural features with adaptive receptors and peripheral selection of γδ T cells occurs. Nevertheless, their specificities may be primarily directed at self-determinants, and the responses of γδ T cells exhibit innate characteristics. Continuous cross talk between γδ T cells and myeloid cells is evident in histological studies and in in vitro co-culture experiments, suggesting that γδ T cells play a functional role as an integral component of the innate immune system.     

Levels of Circulating Th17 Cells and Regulatory T Cells in Ankylosing Spondylitis Patients with an Inadequate Response to Anti−TNF-α Therapy

Purpose

To investigate the effects of TNF-α blockage on levels of circulating Th17, Treg and their related cytokines in ankylosing spondylitis (AS) patients with different response to anti-TNF-α therapy.

Methods

The frequencies of circulating Th17 and Treg and serum levels of related cytokines were determined using flow cytometry analysis and ELISA, respectively, in 222 AS patients both before (baseline) and 6 months after anti-TNF-α therapy. Therapeutic response was defined according to ASAS (Assessment in Spondyloarthritis International Society) response criteria.

Results

Significantly higher baseline circulating Th17 and serum TNF-α, IL-6, IL-17, IL-23 were observed in active AS patients than in healthy controls. After anti-TNF-α therapy, 168 patients (75.7 %) were responders and 54 (24.3 %) were non-responders. Frequencies of Th17 significantly decreased in responders, but significantly increased in non-responders. Treg increased significantly in responders but decreased significantly in non-responders. Levels of TNF-α, IL-6, IL-17, and IL-23 were significantly decreased in responders. In contrast, IL-17 and IL-23 significantly increased in non-responders. TGF-β were significantly increased only in responders, whereas no significant changes were seen in IL-10 in either responders or non-responders. Spearman correlation analysis showed that frequencies of Th17 and levels of TNF-α, IL-6, IL-17, and IL-23 were positively correlated with BASDAI score. They were also positively correlated with BASFI score except for IL-6. Treg were found to be negatively correlated with BASDAI score.

Conclusions

The beneficial effect of anti-TNF-α therapy in AS might not only neutralize the effects of TNF-α but also down-regulate Th17 and Th17-related cytokines accompanied by up-regulating the Treg/TGF-β axis in responders.     

Differential Sensitivity of Naïve and Memory Subsets of Human CD8+ T Cells to TNF-α-Induced Apoptosis

In this investigation, we have examined the relative sensitivity of human naïve, central memory (T_CM), and two types of effector memory CD8+ T cells (T_EM and T_EMRA) to TNF-α-induced apoptosis. Our data show that naïve and T_CM CD8+ T cells were sensitive, whereas T_EM and T_EMRA CD8+ T cells were relatively resistant to TNF-a-induced apoptosis. The apoptosis profile correlated with the activation of caspase-8 and caspase-3. However, no correlation was observed between relative sensitivity of four CD8 + T cell subsets to apoptosis and the expression of TNFR-I or TNFR-II. T_EM and T_EMRA CD8+ T cells displayed increased phosphorylation of IKKα/β and IκB and increased NF-κB activity as compared to naïve and T_CM CD8+ T cells. Bcl-2, Bcl-x_L and FLIP_L expression was higher and Bax expression was lower in T_EM and T_EMRA CD8+ T cells as compared to naïve and T_CM CD8+ T cells. These data suggest that signaling molecules downstream of TNFRs may be responsible for differential sensitivity among subsets of CD8+ T cells to TNF-α-induced apoptosis.