bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: Secondary Lymphoid Organs Are Essential for Maintaining the CD4, But Not CD8, Naive T Cell Pool
Authors: Dai Zhenhua , Lakkis Fadi G. 
Published: April 2014

AbstractDespite declining thymic output with age, the peripheral naive T cell pool of an adult animal remains remarkably stable. Therefore, a central question in immunology is how the naive T cell pool is maintained. Here we show that the maintenance of the naive CD4, but not CD8, T cell population in the thymectomized adult mouse is dependent on the presence of secondary lymphoid tissues. This finding is explained by the inability of naive CD4 T cells to sustain normal levels of the survival molecule Bcl-2 or to undergo homeostatic proliferation in the absence of secondary lymphoid organs. Thus, naive CD4 T cells must traffic through secondary lymphoid organs to maintain a stable CD4 pool while naive CD8 T cells encounter their survival and proliferation signals outside the organized structures of secondary lymphoid tissues.
Multiple Levels of Activation of Murine CD8+ Intraepithelial Lymphocytes Defined by OX40 (CD134) Expression: Effects on Cell-Mediated Cytotoxicity, IFN-γ, and IL-10 Regulation
Authors: Wang Heuy-Ching , Klein John R. 
Published: April 2014

AbstractThe involvement of OX40 (CD134) in the activation of CD8+ intestinal intraepithelial lymphocytes (IELs) has been studied using freshly isolated IELs and in vitro CD3-stimulated IELs. Although freshly isolated CD8+ IELs exhibited properties of activated T cells (CD69 expression and ex vivo cytotoxicity), virtually all CD8+ IELs from normal mice were devoid of other activation-associated properties, including a lack of expression of OX40 and the ligand for OX40 (OX40L) and an absence of intracellular IFN-γ staining. However, OX40 and OX40L expression were rapidly up-regulated on CD8 IELs following CD3 stimulation, indicating that both markers on IELs reflect activation-dependent events. Unlike IELs, activated lymph node T cells did not express OX40L, thus indicating that OX40-OX40L communication in the intestinal epithelium is part of a novel CD8 network. Functionally, OX40 expression was exclusively associated with IELs with active intracellular IFN-γ synthesis and markedly enhanced cell-mediated cytotoxicity. However, OX40 costimulation during CD3-mediated activation significantly suppressed IL-10 synthesis by IELs, whereas blockade of OX40-OX40L by anti-OX40L mAb markedly increased IL-10 production. These findings indicate that: 1) resident CD69+OX40− IELs constitute a population of partially activated T cells poised for rapid delivery of effector activity, 2) OX40 and OX40L expression defines IELs that have undergone recent immune activation, 3) OX40+ IELs are significantly more efficient CTL than are OX40− IELs, and 4) the local OX40/OX40L system plays a critical role in regulating the magnitude of cytokine responses in the gut epithelium.
Soluble CD26/Dipeptidyl Peptidase IV Induces T Cell Proliferation Through CD86 Up-Regulation on APCs
Authors: Ohnuma Kei , Munakata Yasuhiko , Ishii Tomonori , Iwata Satoshi , Kobayashi Seiji , Hosono Osamu , Kawasaki Hiroshi , Dang Nam H. , Morimoto Chikao 
Published: April 2014

AbstractCD26 is a T cell costimulatory molecule with dipeptidyl peptidase IV enzyme activity in its extracellular region. We have previously reported that the addition of soluble CD26 (sCD26) resulted in enhanced proliferation of peripheral blood T lymphocytes induced by the recall Ag, tetanus toxoid (TT). However, the mechanism involved in this immune enhancement has not yet been elucidated. In this paper, we demonstrate that the enhancing effect of sCD26 on TT-induced T cell proliferation occurred in the early stages of immune response. The cells directly affected by exogenously added sCD26 are the CD14-positive monocytes in the peripheral blood. Mannose-6 phosphate interfered with the uptake of sCD26 into monocytes, suggesting that mannose-6 phosphate/insulin-like growth factor II receptor plays a role in the transportation of sCD26 into monocytes. When sCD26 was added after Ag presentation had taken place, enhancement in TT-induced T cell proliferation was not observed. In addition, enhancement of TT-mediated T cell proliferation by sCD26 does not result from trimming of the MHC-bound peptide on the surface of monocytes. Importantly, we also showed that exogenously added sCD26 up-regulated the expression of the costimulatory molecule CD86 on monocytes through its dipeptidyl peptidase IV activity, and that this increased expression of CD86 was observed at both protein and mRNA level. Therefore, our findings suggest that sCD26 enhances T cell immune response to recall Ag via its direct effect on APCs.
Engagement of OX40 Enhances Antigen-Specific CD4+ T Cell Mobilization/Memory Development and Humoral Immunity: Comparison of αOX-40 with αCTLA-4
Authors: Evans Dean E. , Prell Rodney A. , Thalhofer Colin J. , Hurwitz Arthur A. , Weinberg Andrew D. 
Published: April 2014

AbstractIncreasing the long-term survival of memory T cells after immunization is key to a successful vaccine. In the past, the generation of large numbers of memory T cells in vivo has been difficult because Ag-stimulated T cells are susceptible to activation-induced cell death. Previously, we reported that OX40 engagement resulted in a 60-fold increase in the number of Ag-specific CD4+ memory T cells that persisted 60 days postimmunization. In this report, we used the D011.10 adoptive transfer model to examine the kinetics of Ag-specific T cell entry into the peripheral blood, the optimal route of administration of Ag and αOX40, and the Ag-specific Ab response after immunization with soluble OVA and αOX40. Finally, we compared the adjuvant properties of αOX40 to those of αCTLA-4. Engagement of OX-40 in vivo was most effective when the Ag was administered s.c. Time course studies revealed that it was crucial for αOX40 to be delivered within 24–48 h after Ag exposure. Examination of anti-OVA Ab titers revealed a 10-fold increase in mice that received αOX40 compared with mice that received OVA alone. Both αOX40 and αCTLA-4 increased the percentage of OVA-specific CD4+ T cells early after immunization (day 4), but αOX40-treated mice had much higher percentages of OVA-specific memory CD4+ T cells from days 11 to 29. These studies demonstrate that OX40 engagement early after immunization with soluble Ag enhances long-term T cell and humoral immunity in a manner distinct from that provided by blocking CTLA-4.
In Vivo Neutralization of TNF-α Promotes Humoral Autoimmunity by Preventing the Induction of CTL
Authors: Via Charles S. , Shustov Andrei , Rus Violeta , Lang Thomas , Nguyen Phuong , Finkelman Fred D. 
Published: April 2014

AbstractNeutralization of TNF-α in humans with rheumatoid arthritis or Crohn’s disease has been associated with the development of humoral autoimmunity. To determine the effect of TNF-α neutralization on cell-mediated and humoral-mediated responses, we administered anti-TNF-α mAb to mice undergoing acute graft-vs-host disease (GVHD) using the parent-into-F1 model. In vivo neutralization of TNF-α blocked the lymphocytopenic features characteristic of acute GVHD and induced a lupus-like chronic GVHD phenotype (lymphoproliferation and autoantibody production). These effects resulted from complete inhibition of detectable antihost CTL activity and required the presence of anti-TNF-α mAb for the first 4 days after parental cell transfer, indicating that TNF-α plays a critical role in the induction of CTL. Moreover, an in vivo blockade of TNF-α preferentially inhibited the production of IFN-γ and blocked IFN-γ-dependent up-regulation of Fas; however, cytokines such as IL-10, IL-6, or IL-4 were not inhibited. These results suggest that a therapeutic TNF-α blockade may promote humoral autoimmunity by selectively inhibiting the induction of a CTL response that would normally suppress autoreactive B cells.
The Src-Protein Tyrosine Kinase Lck Is Required for IL-1-Mediated Costimulatory Signaling in Th2 Cells
Authors: al-Ramadi Basel K. , Welte Thomas , Fernandez-Cabezudo Maria J. , Galadari Sehamuddin , Dittel Bonnie , Fu Xin-Yuan , Bothwell Alfred L. M. 
Published: April 2014

AbstractSrc-protein tyrosine kinases are intimately involved in TCR-initiated signaling in T lymphocytes. One member of this family, Lck, is also involved in CD28-mediated costimulation in Th1 cells. In Th2 lymphocytes, the costimulatory signal can also be provided by the interaction of IL-1 with type I IL-1R (IL-1RI), culminating in the activation of NF-κB transcription factors. Proximal steps in the IL-1R pathway, however, remain poorly understood, and there is conflicting evidence as to the importance of tyrosine phosphorylation in IL-1R signaling. We have addressed this issue by examining the ability of IL-1 to costimulate the activation of Lck-deficient Th2 cells. Our data demonstrate that, in the absence of Lck, the IL-1 costimulatory pathway is blocked despite the expression of normal levels of IL-1RI. Moreover, the block is associated with a defective degradation of IκB-α and an incomplete activation of NF-κB heterodimeric complexes. Protein expression of NF-κB monomers, including p50, p65, and c-Rel, is equivalent in both wild-type and Lck-deficient Th2 cell clones. Finally, we demonstrate that, in normal Th2 cells, stimulation with IL-1 leads to a rapid induction in tyrosine phosphorylation of several substrates including Lck itself. These findings strongly suggest that Lck is required for signaling in the IL-1 costimulatory pathway in Th2 lymphocytes.
In Vivo and In Vitro Modulation of HLA-DM and HLA-DO Is Induced by B Lymphocyte Activation
Authors: Roucard Corinne , Thomas Claire , Pasquier Marie-Anne , Trowsdale John , Sotto Jean-Jacques , Neefjes Jacques , van Ham Marieke 
Published: April 2014

AbstractAg presentation via HLA class II molecules in B lymphocytes depends on the coordinated action of HLA-DM, the catalyst of class II-peptide loading, and HLA-DO, a pH-dependent modulator of DM, the expression of which is almost completely restricted to B lymphocytes. The relative expression levels of both class II modulators are critical for the composition of the HLA class II peptide repertoire. The data in this work demonstrate that DO and DM expression are both dependent on the cellular activation status in primary human B lymphocytes. In vivo low-density activated primary human B lymphocytes show a prominent reduction in DO and DM expression when compared with high-density resting primary B lymphocytes. In vitro, reduction of DO and DM expression can be induced by B lymphocyte activation via the B cell receptor or by use of the phorbol ester, PMA. Specific inhibition of protein kinase C resulted in a significant reduction of HLA-DO and is potentially due to protein degradation in lysosomal compartments as the phenomenon is reversed by chloroquine. Thus, the expression of the dedicated HLA class II chaperone DM and its pH-dependent modulator DO is regulated and tightly controlled by the activation status of the B lymphocyte.
IL-7 Enhances the Survival and Maintains the Size of Naive T Cells
Authors: Rathmell Jeffrey C. , Farkash Evan A. , Gao Wei , Thompson Craig B. 
Published: April 2014

AbstractT cells require continual presence of extrinsic signals from their in vivo microenvironment to maintain viability. T cells removed from these signals and placed in tissue culture atrophied and died in a caspase-independent manner. Atrophy was characterized by smaller cell sizes, delayed mitogenic responses, and decreased glycolytic rate. Bcl-2 expression remained constant in vitro despite ongoing cell death, indicating that endogenous Bcl-2 expression is insufficient to explain the life span and size control of lymphocytes in vivo and that cell-extrinsic signals provided may be required to maintain both cell viability and size in vivo. One such signal, IL-7, was found to maintain both the size and survival of neglected T cells in vitro. IL-7 was not unique, because the common γ-chain cytokines IL-2, IL-4, and IL-15, as well as the gp130 cytokine IL-6, also promoted both T cell survival and size maintenance. IL-7 did not induce resting T cells to proliferate. Instead, IL-7 stimulated neglected T cells to maintain their metabolic rate at levels comparable to freshly isolated cells. The survival and trophic effects of IL-7 could be separated because IL-7 was able to promote up-regulation of Bcl-2 and maintain cell viability independent of phosphatidylinositol 3-kinase and mammalian target of rapamycin activity but was unable to prevent cellular atrophy when phosphatidylinositol 3-kinase and mammalian target of rapamycin were inhibited. These data demonstrate that T cells require the continuous presence of extrinsic signals not only to survive but also to maintain their size, metabolic activity, and the ability to respond rapidly to mitogenic signals.
A Mandatory Role for STAT4 in IL-12 Induction of Mouse T Cell CCR5
Authors: Iwasaki Masayuki , Mukai Takao , Nakajima Chigusa , Yang Yi-Fu , Gao Ping , Yamaguchi Nobuya , Tomura Michio , Fujiwara Hiromi , Hamaoka Toshiyuki 
Published: April 2014

AbstractIL-12 was recently shown to induce CCR5 on TCR-triggered mouse T cells. Considering that STAT4 is the most critical of IL-12 signaling molecules, this study investigated the role for STAT4 in the induction of CCR5 expression. IL-12R was induced by stimulation with anti-CD3 plus anti-CD28 mAb similarly on T cells from wild-type (WT) and STAT4-deficient (STAT4−/−) mice, but the levels of IL-12R induced on IFN-γ-deficient (IFN-γ−/−) T cells were lower compared with WT T cells. Exposure of TCR-triggered WT T cells to IL-12 induced CCR5 expression. In contrast, TCR-triggered STAT4−/− T cells failed to express CCR5 in response to IL-12. IL-12 stimulation induced detectable albeit reduced levels of CCR5 expression on IFN-γ−/− T cells. Addition of rIFN-γ to cultures of IFN-γ−/− T cells, particularly to cultures during TCR triggering resulted in restoration of CCR5 expression. However, CCR5 expression was not induced in STAT4−/− T cells by supplementation of rIFN-γ. These results indicate that for the induction of CCR5 on T cells, 1) STAT4 plays an indispensable role; 2) such a role is not substituted by simply supplementing rIFN-γ; and 3) IFN-γ amplifies CCR5 induction depending on the presence of STAT4.
Epidermal Langerhans Cell-Targeted Gene Expression by a Dectin-2 Promoter
Authors: Bonkobara Makoto , Zukas Paul K. , Shikano Sojin , Nakamura Shinichiro , Cruz Ponciano D. , Ariizumi Kiyoshi 
Published: April 2014

AbstractDespite their critical function as APCs for primary immune responses, dendritic cells (DC) and Langerhans cells (LC) have been rarely used as targets of gene-based manipulation because well-defined regulatory elements controlling LC/DC-specific expression have not been identified. Previously, we identified dectin-2, a C-type lectin receptor expressed selectively by LC-like XS cell lines and by LC within mouse epidermis. Because these characteristics raised the possibility that dectin-2 promoter may direct LC/DC-specific gene expression, we isolated a 3.2-kb nucleotide fragment from the 5′-flanking region of the dectin-2 gene (Dec2FR) and characterized its regulatory elements and the transcriptional activity using a luciferase (Luc) reporter system. The Dec2FR contains a putative TATA box and cis-acting elements, such as the IFN-stimulated response element, that drive gene expression specifically in XS cells. Dec2FR comprises repressor, enhancer, and promoter regions, and the latter two regions coregulate XS cell-specific gene expression. In transgenic mice bearing a Dec2FR-regulated Luc gene, the skin was the predominant site of Luc activity and LC were the exclusive source of such activity within epidermis. By contrast, other APCs (DC, macrophages, and B cells) and T cells expressed Luc activity close to background levels. We conclude that epidermal LC are targeted selectively for high-level constitutive gene expression by Dec2FR in vitro and in vivo. Our findings lay the foundation for use of the dectin-2 promoter in LC-targeted gene expression systems that may enhance vaccination efficacy and regulate immune responses.
Exon 5 Encoding the Transmembrane Region of HLA-A Contains a Transitional Region for the Induction of Nonsense-Mediated mRNA Decay
Authors: Watanabe Yumiko , Magor Katharine E. , Parham Peter 
Published: April 2014

AbstractHLA class I alleles containing premature termination codons (PTCs) are increasingly being found. To understand their effects on MHC class I expression, HLA-A*2402 mutants containing PTCs were transfected into class I-deficient cells, and expression of HLA-A mRNA and protein was determined. In exons 2, 3, and 4, and in the 5′ part of exon 5, PTCs reduced mRNA levels by up to 90%, whereas in the 3′ part of exon 5 and in exons 6 and 7 they had little effect. Transition in the extent of nonsense-mediated mRNA decay occurred within a 48-nt segment of exon 5, placed 58 nt upstream from the exon 5/exon 6 junction. This transition did not conform to the positional rule obeyed by other genes, which predicted it to be ∼50–55 nt upstream of the exon 7/exon 8 junction and thus placing it in exon 6. Mutants containing extra gene segments showed the difference is caused by the small size of exons 5 and 6, which renders them invisible to the surveillance machinery. For the protein, a transition from secretion to membrane association occurs within a 26-nt segment of exon 5, 17 nt upstream of the exon 5/exon 6 junction. Premature termination in exon 5 can produce secreted and membrane-associated HLA-A variants expressed at high levels.
Immune Elimination ofLeishmania majorin Mice: Implications for Immune Memory, Vaccination, and Reactivation Disease
Authors: Uzonna Jude E. , Wei Guojian , Yurkowski Dean , Bretscher Peter 
Published: April 2014

AbstractInfection of susceptible BALB/c mice with a large, moderate, or low number of Leishmania major parasites respectively results in progressive disease, the formation of substantial but stable lesions, denoted as borderline disease, and the absence of a visible lesion. Infection with a low number of parasites results over the long term in either subclinical infections or an asymptomatic state. Subclinical mice produce a predominant Th1 response and are resistant to challenge, in contrast to their asymptomatic counterparts. Statistical and other evidence suggest that the asymptomatic state can arise from a subclinical state following parasite clearance, with consequent loss of resistance. Cell transfer studies demonstrate unequivocally that immune cells from subclinical mice can protect naive mice against a pathogenic challenge and can clear the parasite, leaving the mice susceptible to a rechallenge infection. This susceptibility is associated with the disappearance of both parasite-specific effector and memory T cells from secondary lymphoid organs. These findings have implications for vaccination, maintenance of memory, and prevention of reactivation disease.
CD4+ T Cells Are Required for the Development of Cytotoxic CD8+ T Cells DuringMycobacterium tuberculosisInfection
Authors: Serbina Natalya V. , Lazarevic Vanja , Flynn JoAnne L. 
Published: April 2014

AbstractThe control of acute and chronic Mycobacterium tuberculosis infection is dependent on CD4+ T cells. In a variety of systems CD8+ T cell effector responses are dependent on CD4+ T cell help. The development of CD8+ T cell-mediated immune responses in the absence of CD4+ T cells was investigated in a murine model of acute tuberculosis. In vitro and in vivo, priming of mycobacteria-specific CD8+ T cells was unaffected by the absence of CD4+ T cells. Infiltration of CD8+ T cells into infected lungs of CD4−/− or wild-type mice was similar. IFN-γ production by lung CD8+ T cells in CD4−/− and wild-type mice was also comparable, suggesting that emergence of IFN-γ-producing mycobacteria-specific CD8+ T cells in the lungs was independent of CD4+ T cell help. In contrast, cytotoxic activity of CD8+ T cells from lungs of M. tuberculosis-infected mice was impaired in CD4−/− mice. Expression of mRNA for IL-2 and IL-15, cytokines critical for the development of cytotoxic effector cells, was diminished in the lungs of M. tuberculosis-infected CD4−/− mice. As tuberculosis is frequently associated with HIV infection and a subsequent loss of CD4+ T cells, understanding the interaction between CD4+ and CD8+ T cell subsets during the immune response to M. tuberculosis is imperative for the design of successful vaccination strategies.
Cytokine Regulation of Facilitated Glucose Transport in Human Articular Chondrocytes
Authors: Shikhman Alexander R. , Brinson Diana C. , Valbracht Jean , Lotz Martin K. 
Published: April 2014

AbstractGlucose serves as the major energy substrate and the main precursor for the synthesis of glycosaminoglycans in chondrocytes. Facilitated glucose transport represents the first rate-limiting step in glucose metabolism. This study examines molecular regulation of facilitated glucose transport in normal human articular chondrocytes by proinflammatory cytokines. IL-1β and TNF-α, and to a lesser degree IL-6, accelerate facilitated glucose transport as measured by [3H]2-deoxyglucose uptake. IL-1β induces an increased expression of glucose transporter (GLUT) 1 mRNA and protein, and GLUT9 mRNA. GLUT3 and GLUT8 mRNA are constitutively expressed in chondrocytes and are not regulated by IL-1β. GLUT2 and GLUT4 mRNA are not detected in chondrocytes. IL-1β stimulates GLUT1 protein glycosylation and plasma membrane incorporation. IL-1β regulation of glucose transport in chondrocytes depends on protein kinase C and p38 signal transduction pathways, and does not require phosphoinositide 3-kinase, extracellular signal-related kinase, or c-Jun N-terminal kinase activation. IL-1β-accelerated glucose transport in chondrocytes is not mediated by endogenous NO or eicosanoids. These results demonstrate that stimulation of glucose transport represents a component of the chondrocyte response to IL-1β. Two classes of GLUTs are identified in chondrocytes, constitutively expressed GLUT3 and GLUT8, and the inducible GLUT1 and GLUT9.
Role of NF-κB in Endotoxemia-Induced Alterations of Lung Neutrophil Apoptosis
Authors: Kupfner John G. , Arcaroli John J. , Yum Ho-Kee , Nadler Steven G. , Yang Kuang-Yao , Abraham Edward 
Published: April 2014

AbstractAcute lung injury is frequently associated with endotoxemia and is characterized by the accumulation in the lungs of large numbers of neutrophils activated to produce proinflammatory mediators. In the setting of acute lung injury, the percentage of apoptotic cells among lung neutrophils is decreased. The transcriptional regulatory factor NF-κB is activated in neutrophils and other pulmonary cell populations after endotoxemia and appears to play a central role in the development of the acute inflammatory process that leads to lung injury. Because NF-κB can modulate apoptosis through increasing expression of anti-apoptotic proteins, activation of NF-κB may contribute to the alterations in lung neutrophil apoptosis associated with acute lung injury. In the present experiments, endotoxemia resulted in decreased apoptosis and increased expression of anti-apoptotic mediators among lung neutrophils. Amounts of A1, A20, and Bcl-xL, anti-apoptotic proteins whose transcription is dependent on NF-κB, were increased in lung neutrophils after endotoxemia. Inhibition of nuclear translocation of NF-κB increased the percentage of apoptotic lung neutrophils after endotoxemia, but not back to the levels found in unmanipulated animals. Although inhibition of nuclear translocation of NF-κB prevented endotoxemia-induced increases in Bcl-xL, A1, and A20 in lung neutrophils, this intervention did not prevent endotoxemia-associated elevation of Mcl-1, an anti-apoptotic protein primarily under the transcriptional regulation of CREB. These results demonstrate that mechanisms independent of NF-κB activation play an important role in modulating lung neutrophil apoptosis after endotoxemia,