bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reductions in IκBε and Changes in NF-κB Activity during B Lymphocyte Differentiation
Authors: Doerre Stefan , Mesires Kristin Perkins , Daley Kylle M. , McCarty Thomas , Knoetig Sonja , Corley Ronald B. 
Published: April 2014

Abstract
The levels and stability of IκBε have been examined in unstimulated and stimulated splenic B cells and compared with that of IκBα and IκBβ. Primary murine splenic B cells but not T cells were found to contain high levels of IκBε protein, equivalent to levels of the abundant IκBα. Most agents that activate IκBα and IκBβ degradation do not induce rapid degradation of IκBε. Interestingly, however, the levels of IκBε, but not of IκBα or IκBβ, are dramatically reduced upon the stimulation of B cells both in vivo and in vitro. Since IκBε exhibits substrate specificity for NF-κB Rel homodimers, this suggested the possibility that changes in NF-κB-responsive genes might also occur during this transition. Consistent with this hypothesis, we found that a NF-κB reporter construct sensitive to p65/RelA homodimers is activated at the time that IκBε levels decline following B cell stimulation. In IgG+ B cell lines, which contain low levels of IκBε, this same reporter construct was inactive, suggesting that the increases in Rel homodimer activity that accompany B cell stimulation are transient. However, there are differences in the level of expression of NF-κB-responsive genes in these IgG+ B cell lines compared with their IgM+ counterparts. From these data, we conclude that there are transient changes in NF-κB activity due to reductions in IκBε, which might contribute to long-term, persistent changes that accompany B cell differentiation. We propose an important role for IκBε in the differential regulation of nuclear NF-κB activity in stimulated B cells.
Innate Immunity in the Human Female Reproductive Tract: Antiviral Response of Uterine Epithelial Cells to the TLR3 Agonist Poly(I:C)
Authors: Schaefer Todd M. , Fahey John V. , Wright Jacqueline A. , Wira Charles R. 
Published: April 2014

Abstract
The objective of this study was to examine the expression of TLR by human primary uterine epithelial cells (UEC) and to determine whether exposure to the TLR agonist poly(I:C) would induce an antiviral response. The secretion of several cytokines and chemokines was examined as well as the mRNA expression of human β-defensin-1 and -2 (HBD1 and HBD2), IFN-β, and the IFN-β-stimulated genes myxovirus resistance gene 1 and 2′,5′ oligoadenylate synthetase. The expression of TLR1–9 by UEC was demonstrated by RT-PCR, with only TLR10 not expressed. Stimulation of UEC with the TLR3 agonist poly(I:C) induced the expression of the proinflammatory cytokines TNF-α, IL-6, GM-CSF, and G-CSF, as well as the chemokines CXCL8/IL-8, CCL2/MCP-1, and CCL4/MIP-1β. In addition, poly(I:C) exposure induced the mRNA expression of HBD1 and HBD2 by 6- and 4-fold, respectively. Furthermore, upon exposure to poly(I:C) UEC initiated a potent antiviral response resulting in the induction of IFN-β mRNA expression 70-fold and myxovirus resistance gene 1 and 2′,5′ oligoadenylate synthetase mRNA expression (107- and 96-fold), respectively. These results suggest that epithelial cells that line the uterine cavity are sensitive to viral infection and/or exposure to viral dsRNA released from killed epithelial cells. Not only do UEC release proinflammatory cytokines and chemokines that mediate the initiation of an inflammatory response and recruitment of immune cells to the site of infection, but they also express β-defensins, IFN-β, and IFN-β-stimulated genes that can have a direct inhibiting effect on viral replication.
Sphingolipids and the Balancing of Immune Cell Function: Lessons from the Mast Cell
Authors: Olivera Ana , Rivera Juan 
Published: April 2014

Abstract
Recent studies reveal that metabolites of sphingomyelin are critically important for initiation and maintenance of diverse aspects of immune cell activation and function. The conversion of sphingomyelin to ceramide, sphingosine, or sphingosine-1-phosphate (S1P) provides interconvertible metabolites with distinct biological activities. Whereas ceramide and sphingosine function to induce apoptosis and to dampen mast cell responsiveness, S1P functions as a chemoattractant and can up-regulate some effector responses. Many of the S1P effects are mediated through S1P receptor family members (S1P1–5). S1P1, which is required for thymocyte emigration and lymphocyte recirculation, is also essential for Ag-induced mast cell chemotaxis, whereas S1P2 is important for mast cell degranulation. S1P is released to the extracellular milieu by Ag-stimulated mast cells, enhancing inflammatory cell functions. Modulation of S1P receptor expression profiles, and of enzymes involved in sphingolipid metabolism, particularly sphingosine kinases, are key in balancing mast cell and immune cell responses. Current efforts are unraveling the complex underlying mechanisms regulating the sphingolipid pathway. Pharmacological intervention of these key processes may hold promise for controlling unwanted immune responses.
Cutting Edge: TLR Ligands Are Not Sufficient to Break Cross-Tolerance to Self-Antigens
Authors: Hamilton-Williams Emma E. , Lang Andreas , Benke Dirk , Davey Gayle M. , Wiesmüller Karl-Heinz , Kurts Christian 
Published: April 2014

Abstract
Cross-presentation of peripheral self-Ags by dendritic cells (DC) can induce deletion of autoreactive CTL by a mechanism termed cross-tolerance. Activation of DC by microbial TLR ligands is thought to result in adaptive immunity. However, activation of tolerogenic DC may cause autoimmunity by stimulating instead of deleting autoreactive CTL. To investigate this scenario, we have monitored the response of autoreactive CTL in specific for the transgenic self Ag, OVA, expressed in pancreatic islets of RIP-mOVA mice injected with ligands of TLR2, 3, 4, and 9. This somewhat enhanced proliferation and cytokine production, and moderately reduced the CTL number able to induce autoimmunity. Nevertheless, physiological CTL numbers were deleted before disease ensued, unless specific CD4 T cell help was provided. In conclusion, DC activation by TLR ligands was insufficient to break peripheral cross-tolerance in the absence of specific CD4 T cell help, and triggered autoimmunity by stimulating the early effector phase of autoreactive CTL only when their precursor frequency was extremely high.
Impaired Recall of CD8 Memory T Cells in Immunologically Privileged Tissue
Authors: Dai Zhenhua , Nasr Isam W. , Reel Michael , Deng Songyan , Diggs Lonnette , Larsen Christian P. , Rothstein David M. , Lakkis Fadi G. 
Published: April 2014

AbstractForeign Ags that enter immunologically privileged sites such as the eye, brain, and testis persist for an extended period of time, whereas the same Ags are rapidly eliminated at conventional sites. Immune privilege, therefore, provides unwanted refuge for pathogens and tumor cells but is beneficial for the survival of allogeneic grafts. In this study, we asked whether memory T cells can eliminate foreign Ags deposited at an immunologically privileged site by studying CD8 memory T cell-mediated rejection of pancreatic islet allografts placed either in the testis (a privileged organ) or under the kidney capsule (a nonprivileged site) of diabetic mice. We found that CD8 memory T cells reject intratesticular grafts at a significantly slower rate than the rejection of intrarenal grafts. Delayed graft rejection in the testis was not due to reduced homing or proliferation of memory T cells but due to their increased apoptosis at that site. Apoptosis was mediated by the combined actions of two TNFR family members that are up-regulated on activated memory T cells, Fas, and CD30. Therefore, memory T cells survey immunologically privileged tissues but are subject to the immunosuppressive mechanisms present at these sites.
Different Competitive Capacities of Stat4- and Stat6-Deficient CD4+ T Cells during Lymphophenia-Driven Proliferation
Authors: Sanchez-Guajardo Vanesa , Borghans José A. M. , Marquez Maria-Elena , Garcia Sylvie , Freitas Antonio A. 
Published: April 2014

Abstract
The outcome of an immune response relies on the competitive capacities acquired through differentiation of CD4+ T cells into Th1 or Th2 effector cells. Because Stat4 and Stat6 proteins are implicated in the Th1 vs Th2 generation and maintenance, respectively, we compare in this study the kinetics of Stat4−/− and Stat6−/− CD4+ T cells during competitive bone marrow reconstitution and lymphopenia-driven proliferation. After bone marrow transplantation, both populations reconstitute the peripheral T cell pools equally well. After transfer into lymphopenic hosts, wild-type and Stat6−/− CD4+ T cells show a proliferation advantage, which is early associated with the expression of an active phospho-Stat4 and the down-regulation of Stat6. Despite these differences, Stat4- and Stat6-deficient T cells reach similar steady state numbers. However, when both Stat4−/− and Stat6−/− CD4+ T cells are coinjected into the same hosts, the Stat6−/− cells become dominant and out-compete Stat4−/− cells. These findings suggest that cell activation, through the Stat4 pathway and the down-regulation of Stat6, confers to pro-Th1 T cells a slight proliferation advantage that in a competitive situation has major late repercussions, because it modifies the final homeostatic equilibrium of the populations and favors the establishment of Th1 CD4+ T cell dominance.
Polarized Development of Memory Cell-Like IFN-γ-Producing Cells in the Absence of TCR ζ-Chain
Authors: Krymskaya Ludmila , Lee Wen-Hui , Zhong Lingwen , Liu Chih-Pin 
Published: April 2014

Abstract
TCR/CD3 complex-mediated signals play critical roles in regulating CD4+ Th cell differentiation. In this report, we have examined the in vivo role of a key TCR/CD3 complex molecule ζ-chain in regulating the differentiation of Th cells. We have studied T cells from ζ-chain-deficient mice (ζKO mice), ζ-chain-bearing mice (ζ+ mice), and from ζKO mice expressing a FcRγ chain transgene (FcRγTG, ζKO mice). Our results demonstrated that, compared with those of control mice, CD4+ T cells and not CD8+ T cells from ζKO mice were polarized into IFN-γ-producing cells. Some of these IFN-γ-producing cells could also secrete IL-10. Interestingly, ζKO mouse T cells produced IFN-γ even after they were cultured in a Th2 condition. Our studies to determine the molecular mechanisms underlying the polarized IFN-γ production revealed that the expression level of STAT4 and T-bet were up-regulated in freshly isolated T cells from ζKO mice. Further studies showed that noncultured ζKO mice CD4+ T cells and thymocytes bore a unique memory cell-like CD44high, CD62Llow/neg phenotype. Altogether, these results suggest that, in the absence of the ζ-chain, CD4+ T cells develop as polarized IFN-γ-producing cells that bear a memory cell-like phenotype. The ζ-chain-bearing T cells may produce a large amount of IFN-γ only after they are cultured in a condition favoring Th1 cell differentiation. This study may provide important implications for the down-regulation of ζ-chain in T cells of patients bearing a variety of tumors, chronic inflammatory and infectious diseases.
Induction of Impaired Antitumor Immunity by Fusion of MHC Class II-Deficient Dendritic Cells with Tumor Cells
Authors: Tanaka Yasuhiro , Koido Shigeo , Ohana Masaya , Liu Chunlei , Gong Jianlin 
Published: April 2014

Abstract
To dissect the role of Ag presentation through MHC class I and/or II pathways by dendritic cell (DC)-tumor fusion cells, we have created various types of DC-tumor fusion cells by alternating fusion cell partners. Fusions of MC38/MUC1 carcinoma cells with DC from wild-type (WT-DC), MHC class I knockout (IKO-DC), class II knockout (IIKO-DC), or class I and II knockout (I/IIKO-DC) mice created WTDC-fusion cells (FC), IKO-FC, IIKO-FC, and I/IIKO-FC, respectively. MHC class II- and MUC1-positive fusion cells were constructed by fusion of B16/MUC1 melanoma cells with IKO-DC (IKO/B16-FC). Immunization of MUC1 transgenic mice with 5 × 105 WTDC-FC, IKO-FC, IIKO-FC, or I/IIKO-FC provided 100, 91.7, 61.5, and 15.4% protection, respectively, against tumor challenge with MC38/MUC1 cells. In contrast, all mice immunized with irradiated MC38/MUC1 tumor cells or WT-DC developed tumors. One group of mice was immunized with 5 × 105 IKO/B16-FC and then challenged with B16/Ia+/MUC1 on one flank and MC38/MUC1 on the other flank. Immunization of these mice with IKO/B16-FC resulted in 100 and 78.6% protection against B16/Ia+/MUC1 and MC38/MUC1 tumor challenge, respectively. The antitumor immunity induced by immunization with IKO/B16-FC was able to inhibit the growth of MHC class II-negative tumor. In addition, in vivo results correlated with the induction of Ag-specific CTL. Collectively, the data indicate that MHC class II Ag presentation targeting activation of CD4 T cells is indispensable for antitumor immunity.
IFN-γ Suppresses STAT6 Phosphorylation by Inhibiting Its Recruitment to the IL-4 Receptor
Authors: Huang Zan , Xin Junping , Coleman John , Huang Hua 
Published: April 2014

Abstract
Polarized Th1 cells show a stable phenotype: they become insensitive to IL-4 stimulation and lose the potential to produce IL-4. Previously, we reported that IFN-γ played a critical role in stabilizing Th1 phenotype. However, the mechanism by which IFN-γ stabilizes Th1 phenotype is not clear. In this study, we compared STAT6 phosphorylation in wild-type (WT) and IFN-γ receptor knockout (IFNGR−/−) Th1 cells. We found a striking diminution of STAT6 phosphorylation in differentiated WT Th1 cells, but not in differentiated IFNGR−/− Th1 cells. The impairment of STAT6 phosphorylation in differentiated WT Th1 cells was not due to a lack of IL-4R expression or phosphorylation. Jak1 and Jak3 expression and phosphorylation were comparable in both cell types. No differential expression of suppressor of cytokine signaling 1 (SOCS1), SOCS3, or SOCS5 was observed in the two cell types. In addition, Src homology 2-containing phosphatase mutation did not affect IL-4-induced STAT6 phosphorylation in differentiated Th1 cells derived from viable motheaten (mev/mev) mice. These results led us to focus on a novel mechanism. By using a pulldown assay, we observed that STAT6 in WT Th1 cells bound less effectively to the phosphorylated IL-4R/GST fusion protein than that in IFNGR−/− Th1 cells. Our results suggest that IFN-γ may suppress phosphorylation of STAT6 by inhibiting its recruitment to the IL-4R.
CD70 Signaling Is Critical for CD28-Independent CD8+ T Cell-Mediated Alloimmune Responses In Vivo
Authors: Yamada Akira , Salama Alan D. , Sho Masayuki , Najafian Nader , Ito Toshiro , Forman John P. , Kewalramani Reshma , Sandner Sigrid , Harada Hiroshi , Clarkson Michael R. , Mandelbrot Didier A. , Sharpe Arlene H. , Oshima Hideo , Yagita Hideo , Chalasani Geetha , Lakkis Fadi G. , Auchincloss Hugh , Sayegh Mohamed H. 
Published: April 2014

Abstract
The inability to reproducibly induce robust and durable transplant tolerance using CD28-B7 pathway blockade is in part related to the persistence of alloreactive effector/memory CD8+ T cells that are less dependent on this pathway for their cellular activation. We studied the role of the novel T cell costimulatory pathway, CD27-CD70, in alloimmunity in the presence and absence of CD28-B7 signaling. CD70 blockade prolonged survival of fully mismatched vascularized cardiac allografts in wild-type murine recipients, and in CD28-deficient mice induced long-term survival while significantly preventing the development of chronic allograft vasculopathy. CD70 blockade had little effect on CD4+ T cell function but prevented CD8+ T cell-mediated rejection, inhibited the proliferation and activation of effector CD8+ T cells, and diminished the expansion of effector and memory CD8+ T cells in vivo. Thus, the CD27-CD70 pathway is critical for CD28-independent effector/memory CD8+ alloreactive T cell activation in vivo. These novel findings have important implications for the development of transplantation tolerance-inducing strategies in primates and humans, in which CD8+ T cell depletion is currently mandatory.
Intestinal Dendritic Cell Subsets: Differential Effects of Systemic TLR4 Stimulation on Migratory Fate and Activation In Vivo
Authors: Turnbull Emma L. , Yrlid Ulf , Jenkins Christopher D. , MacPherson G. Gordon 
Published: April 2014

AbstractDendritic cells (DC) present peripheral Ags to T cells in lymph nodes, but also influence their differentiation (tolerance/immunity, Th1/Th2). To investigate how peripheral conditions affect DC properties and might subsequently regulate T cell differentiation, we examined the effects of a potent DC-activating, TLR-4-mediated stimulus, LPS, on rat intestinal and hepatic DC in vivo. Steady-state rat intestinal and hepatic lymph DC are αE2 integrinhigh (CD103) and include two subsets, signal regulatory protein α (SIRPα)hi/low, probably representing murine CD8αα−/+ DC. Steady-state lamina propria DC are immature; surface MHC class IIlow, but steady-state lymph DC are semimature, MHC class IIhigh, but CD80/86low. Intravenous LPS induced rapid lamina propria DC emigration and increased lymph DC traffic without altering SIRPαhigh/SIRPαlow proportions. CD80/86 expression on lymph or mesenteric node DC was not up-regulated after i.v. LPS. In contrast, i.v. LPS stimulated marked CD80/86 up-regulation on splenic DC. CD80/86 expression on intestinal lymph DC, however, was increased after in vitro culture with TNF-α or GM-CSF, but not with up to 5 μg/ml LPS. Steady-state SIRPαlow DC localized to T cell areas of mesenteric nodes, spleen, and Peyer’s patch, whereas SIRPαhigh DC were excluded from these areas. Intravenous LPS stimulated rapid and abundant SIRPαhigh DC accumulation in T cell areas of mesenteric nodes and spleen. In striking contrast, i.v. LPS had no effect on DC numbers or distribution in Peyer’s patches. Our results suggest that any explanation of switching between tolerance and immunity as well as involving changes in DC activation status must also take into account differential migration of DC subsets.
Analysis of Marginal Zone B Cell Development in the Mouse with Limited B Cell Diversity: Role of the Antigen Receptor Signals in the Recruitment of B Cells to the Marginal Zone
Authors: Kanayama Naoki , Cascalho Marilia , Ohmori Hitoshi 
Published: April 2014

Abstract
The quasimonoclonal (QM) mouse provides an intelligible model to analyze the B cell selection as the competition between two major 4-hydroxy-3-nitrophenylacetyl-specific B cell populations whose BCR are comprised of the knockin VH17.2.25 (VHT)-encoded H chain and the λ1 or λ2 L chain. In this study, we show the QM system is useful to examine how BCR signals guide a subset of B cells to the marginal zone (MZ). Compared with the control C57BL/6 mice, the QM mice had ∼2.7-fold increased number of B cells exhibiting the MZ B cell phenotype and a larger MZ area in the spleen. Interestingly, VHT/λ2 B cells significantly predominated over VHT/λ1 B cells in MZ-(VHT/λ1:VHT/λ2 ≈ 3:7) and transitional 2-B cell subsets, while these two populations were comparable in immature, transitional 1, and mature counterparts. Thus, the biased use of λ2 in the MZ B cells may be the result of selection in the periphery. The enlargement of MZ B cell compartment and the preferred recruitment of the VHT/λ2 B cells were further augmented by doubling the VHT gene, but dampened by the dysfunction of Bruton’s tyrosine kinase, suggesting a positive role of BCR signaling in this selection. Comparison of Ag specificity between VHT/λ1 and VHT/λ2 IgM mAbs revealed a polyreactive nature of the VHT/λ2 BCR, including the reactivity with ssDNA. Taken together, it is suggested that polyreactivity (including self-reactivity) of BCR is crucial in driving B cells to differentiate into the MZ phenotype.
Differentiation and Expansion of T Cells with Regulatory Function from Human Peripheral Lymphocytes by Stimulation in the Presence of TGF-β
Authors: Rao Patricia E. , Petrone Andria L. , Ponath Paul D. 
Published: April 2014

Abstract
T cells with immunoregulatory function have been described in human and mouse systems. In both systems these cells can be differentiated either in the thymus or from peripheral T cells. To date, more progress has been made in the study of murine regulatory T cells, because it has been very difficult to isolate human regulatory T cells of sufficient purity and in sufficient numbers to permit detailed examinations of their biochemistry. We report in this study that human T cells with regulatory function can be differentiated in vitro from naive (CD4+CD45RA+) cord blood or peripheral T cells by stimulation with anti-CD3 and anti-CD28 in the presence of TGF-β. Cells derived in this manner express a surface phenotype (CD25+, CD122+, HLA-DR+, glucocorticoid-induced TNF receptor-related gene+, CD103+, CTLA-4+) described for human and mouse regulatory T cells and express protein and message for the transcription factor forkhead/winged helix transcription factor (FOXP3). They produce primarily TGF-β and IL-10, with lesser amounts of IFN-γ and IL-13, when stimulated through their TCRs and are capable of inhibiting cytokine production and proliferation by stimulated naive T cells. Unlike Th1 and Th2 cells, these TGF-β-derived regulatory T cells do not appear to be dependent on the protein kinase Cθ pathway of NF-κB activation for Ag-induced responses.
Differential Control of CD28-Regulated In Vivo Immunity by the E3 Ligase Cbl-b
Authors: Krawczyk Connie M. , Jones Russell G. , Atfield Alexandre , Bachmaier Kurt , Arya Sudha , Odermatt Bernhard , Ohashi Pamela S. , Penninger Josef M. 
Published: April 2014

Abstract
The E3 ubiquitin ligase Casitas B cell lymphoma-b (Cbl-b) plays a critical role in the development of autoimmunity and sets the threshold for T cell activation. In the absence of Cbl-b, T cells stimulated via the TCR respond similarly to those that have received a CD28-mediated costimulatory signal, suggesting that the absence of Cbl-b substitutes for CD28-mediated costimulation. In this study, we show that loss of Cbl-b restores Ig class switching and germinal center formation in Vav1 mutant mice in response to an in vivo viral challenge. Genetic inactivation of Cbl-b also rescues impaired antiviral IgG production in CD28-mutant mice. Moreover, loss of CD28 results in disorganization of follicular dendritic cell clusters, which is also rescued by the Cbl-b mutation. Intriguingly, despite restored antiviral in vivo immunity and follicular dendritic cell clusters, loss of Cbl-b did not rescue germinal center formation in CD28-deficient mice. Mechanistically, in vivo vesicular stomatitis virus-induced IL-4 and IFN-γ production and up-regulation of the inducible costimulatory molecule ICOS were dependent on CD28, and could not be rescued by the loss of Cbl-b. These data provide genetic evidence that CD28-dependent in vivo immune responses and Ig class switching can be genetically uncoupled from germinal center formation and ICOS induction by Cbl-b-Vav1-regulated signaling pathways.