bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of Secretory and Endosomal Compartments in Presentation of an Exogenous Self-Glycolipid to Type II NKT Cells
Authors: Roy Keshab Chandra , Maricic Igor , Khurana Archana , Smith Trevor R. F. , Halder Ramesh C. , Kumar Vipin 
Published: April 2014

Abstract
Natural Killer T (NKT) cells recognize both self and foreign lipid Ags presented by CD1 molecules. Although presentation of the marine sponge-derived lipid αGalCer to type I NKT cells has been well studied, little is known about self-glycolipid presentation to either type I or type II NKT cells. Here we have investigated presentation of the self-glycolipid sulfatide to a type II NKT cell that specifically recognizes a single species of sulfatide, namely lyso-sulfatide but not other sulfatides containing additional acyl chains. In comparison to other sulfatides or αGalCer, lyso-sulfatide binds with lower affinity to CD1d. Although plate-bound CD1d is inefficient in presenting lyso-sulfatide at neutral pH, it is efficiently presented at acidic pH and in the presence of saposin C. The lysosomal trafficking of mCD1d is required for αGalCer presentation to type I NKT cells, it is not important for presentation of lyso-sulfatide to type II NKT cells. Consistently, APCs deficient in a lysosomal lipid-transfer protein effectively present lyso-sulfatide. Presentation of lyso-sulfatide is inhibited in the presence of primaquine, concanamycin A, monensin, cycloheximide, and an inhibitor of microsomal triglyceride transfer protein but remains unchanged following treatment with brefeldin A. Wortmannin-mediated inhibition of lipid presentation indicates an important role for the PI-3kinase in mCD1d trafficking. Our data collectively suggest that weak CD1d-binding self-glycolipid ligands such as lyso-sulfatide can be presented via the secretory and endosomal compartments. Thus this study provides important insights into the exogenous self-glycolipid presentation to CD1d-restricted T cells.
Splenic Stromal Microenvironment Negatively Regulates Virus-Activated Plasmacytoid Dendritic Cells through TGF-β
Authors: Li Li , Liu Shuxun , Zhang Ting , Pan Wei , Yang Xiao , Cao Xuetao 
Published: April 2014

Abstract
Plasmacytoid dendritic cells (pDCs) secrete large amounts of IFN-α upon exposure to virus, subsequently promoting and regulating innate and adaptive immune responses. However, little is known about the functional regulation of virus-activated pDCs after they exert functions in secondary lymph organs. Our previous studies show that splenic stromal microenvironment can down-regulate the T cell response by inducing generation of regulatory myeloid dendritic cells; therefore, we wondered whether the splenic stromal microenvironment can regulate the function of virus-activated pDCs. In this study, we provide evidences that the splenic stromal microenvironment can chemoattract vesicular stomatitis virus (VSV)-activated pDCs via stromal cell-derived dactor 1 (SDF-1), inhibit the secretion of IFN-α, IL-12, TNF-α, and expression of I-Ab, CD86, CD80, and CD40 by VSV-activated pDCs, and subsequently inhibit VSV-infected pDCs to activate NK cell IFN-γ production and cytotoxicity. Stroma-derived TGF-β participates in the negative regulation of VSV-activated pDCs. Therefore, we demonstrate that splenic stromal microenvironment negatively regulates the virus-activated pDCs through TGF-β, outlining an additional mechanistic explanation for maintenance of immune homeostasis.
Proliferative Expansion and Acquisition of Effector Activity by Memory CD4+ T Cells in the Lungs following Pulmonary Virus Infection
Authors: Wissinger Erika L. , Stevens Whitney W. , Varga Steven M. , Braciale Thomas J. 
Published: April 2014

Abstract
The memory CD4+ T cell response to the respiratory syncytial virus (RSV) attachment (G) protein in the lungs of primed BALB/c mice undergoing challenge pulmonary RSV infection is dominated by effector T cells expressing a single Vβ-chain, Vβ14. We have used Vβ14 expression to examine the kinetics of the activation, accumulation, and acquisition of the effector activity of memory CD4+ T cells responding to pulmonary infection. This analysis revealed that proliferative expansion and effector CD4+ T cell differentiation preferentially occur in the respiratory tract following rapid activation within and egress from the lymph nodes draining the respiratory tract. These findings suggest that, in response to natural infection at a peripheral mucosal site such as the lungs, memory CD4+ T cell expansion and differentiation into activated effector T cells may occur predominantly in the peripheral site of infection rather than exclusively in the lymph nodes draining the site of infection.
Expression of ICOS on Human Melanoma-Infiltrating CD4+CD25highFoxp3+ T Regulatory Cells: Implications and Impact on Tumor-Mediated Immune Suppression
Authors: Strauss Laura , Bergmann Christoph , Szczepanski Miroslaw J. , Lang Stephan , Kirkwood John M. , Whiteside Theresa L. 
Published: April 2014

Abstract
Objective: Interaction of ICOS with its ligand (ICOSL, B7-H2) promotes T cell responses. As CD4+CD25highFoxp3+ naturally occurring T regulatory cells in melanoma patients express ICOS, we investigated the impact of ICOS on naturally occurring T regulatory cell function. Methods: Expression of ICOS and T regulatory (Treg) cell markers was determined on CD4+CD25high T cells in PBMC and tumor-infiltrating lymphocytes from melanoma patients (n = 10) and PBMC of normal controls (n = 10) by multicolor flow cytometry. Suppression mediated by sorted ICOShigh and ICOSlow Treg was assessed in CFSE-based suppression assays with autologous CD4+CD25− responder cells (RC). Transwell inserts separating Treg from RC were used to evaluate suppression mechanisms used by Treg. ICOShigh or ICOSlow Treg were coincubated with RC ± TCR and IL-2 stimulation. ICOShigh and ICOS− Treg were also expanded under conditions previously shown to induce Tr1 from RC. Results: Treg in tumor-infiltrating lymphocytes expressed ICOS (mean fluorescence intensity = 70 ± 10), while Treg in PBMC had low ICOS expression (mean fluorescence intensity = 3.5 ± 2.5, p ≤ 0.001). ICOShigh Treg up-regulated Treg markers (p ≤ 0.0016) and mediated stronger suppression (p ≤ 0.001) relative to ICOSlow Treg. ICOShigh Treg induced Tr1 cells in nonactivated RC and Th2 cells in preactivated RC. ICOShigh Treg exposed to Tr1 cytokines expressed IL-10 and suppressed RC (92 ± 12%) in contrast to ICOSlow Treg, which mediated low suppression (21 ± 15%; p ≤ 0.0028). Conclusion: ICOShigh Treg can induce diverse immune responses in RC, depending on activation signals and cytokines present. ICOShigh Treg induce Tr1 or Th2 cells depending on the activation state of RC. In a “Tr1” cytokine milieu, ICOShigh Treg transit to Tr1.
Regulatory and Conventional CD4+ T Cells Show Differential Effects Correlating with PD-1 and B7-H1 Expression after Immunotherapy
Authors: Alderson Kory L. , Zhou Qing , Berner Vanessa , Wilkins Danice E. C. , Weiss Jonathan M. , Blazar Bruce R. , Welniak Lisbeth A. , Wiltrout Robert H. , Redelman Doug , Murphy William J. 
Published: April 2014

Abstract
Recently, our laboratory reported that secondary CD8+ T cell-mediated antitumor responses were impaired following successful initial antitumor responses using various immunotherapeutic approaches. Although immunotherapy stimulated significant increases in CD8+ T cell numbers, the number of CD4+ T cells remained unchanged. The current investigation revealed a marked differential expansion of CD4+ T cell subsets. Successful immunotherapy surprisingly resulted in an expansion of CD4+Foxp3+ regulatory T (Treg) cells concurrent with a reduction of conventional CD4+ T (Tconv) cells, despite the marked antitumor responses. Following immunotherapy, we observed differential up-regulation of PD-1 on the surface of CD4+Foxp3+ Treg cells and CD4+Foxp3− Tconv cells. Interestingly, it was the ligand for PD-1, B7-H1 (PDL-1), that correlated with Tconv cell loss after treatment. Furthermore, IFN-γ knockout (IFN-γ−/−) and IFN-γ receptor knockout (IFN-γR−/−) animals lost up-regulation of surface B7-H1 even though PD-1 expression of Tconv cells was not changed, and this correlated with CD4+ Tconv cell increases. These results suggest that subset-specific expansion may contribute to marked shifts in the composition of the T cell compartment, potentially influencing the effectiveness of some immunotherapeutic approaches that rely on IFN-γ.
Rat CD4+CD8+ Macrophages Kill Tumor Cells through an NKG2D- and Granzyme/Perforin-Dependent Mechanism
Authors: Baba Tomohisa , Iwasaki Sari , Maruoka Takako , Suzuki Akira , Tomaru Utano , Ikeda Hitoshi , Yoshiki Takashi , Kasahara Masanori , Ishizu Akihiro 
Published: April 2014

Abstract
We previously identified a subpopulation of monocyte/macrophage lineage cells expressing both CD4 and CD8. This subpopulation was expanded in rat peripheral blood and spleen after immunization with adjuvants containing killed tuberculosis germs. CD4+CD8+ monocytes/macrophages obtained from preimmunized rats exhibited a Th1-type cytokine/chemokine profile, expressed high levels of Fas ligand, perforin, granzyme B, and NKR-P2 (rat ortholog of human NKG2D), and killed certain tumor cells. In the present study, we confirmed that CD4+CD8+ monocytes/macrophages are distinct from splenic dendritic cells (DCs) or IFN-producing killer DCs. In vitro cytotoxic assays revealed that CD4+CD8+ macrophages killed tumor cells in a cell-cell contact-dependent manner and that expression of the retinoic acid early transcript 1 (a ligand for NKG2D) made tumor cells susceptible to killing by CD4+CD8+ macrophages. Furthermore, inhibitors of granzyme and perforin significantly decreased cytotoxic activities of CD4+CD8+ macrophages. Consistent with these in vitro findings, preimmunization with adjuvants containing killed tuberculosis germs elevated the expression of granzyme B in tumor-infiltrating CD4+CD8+ macrophages and significantly inhibited the growth of inoculated tumor cells. Our current work demonstrates that CD4+CD8+ macrophages are a unique subpopulation of monocyte/macrophage lineage cells that kill tumor cells in an NKG2D- and granzyme/perforin-dependent mechanism.
Blood Monocyte Subsets Differentially Give Rise to CD103+ and CD103− Pulmonary Dendritic Cell Populations
Authors: Jakubzick Claudia , Tacke Frank , Ginhoux Florent , Wagers Amy J. , van Rooijen Nico , Mack Matthias , Merad Miriam , Randolph Gwendalyn J. 
Published: April 2014

Abstract
There are two major myeloid pulmonary dendritic cell (DC) populations: CD103+ DCs and CD11bhigh DCs. In this study, we investigated in detail the origins of both myeloid DC pools using multiple experimental approaches. We show that, in resting lung, Ly-6ChighCCR2high monocytes repopulated CD103+ DCs using a CCR2-dependent mechanism, and these DCs preferentially retained residual CCR2 in the lung, whereas, conversely, Ly-6ClowCCR2low monocytes repopulated CD11bhigh DCs. CX3CR1 was required to generate normal numbers of pulmonary CD11bhigh DCs, possibly because Ly-6Clow monocytes in the circulation, which normally express high levels of CX3CR1, failed to express bcl-2 and may have diminished survival in the circulation in the absence of CX3CR1. Overall, these data demonstrate that the two circulating subsets of monocytes give rise to distinct tissue DC populations.
Prophylactic Treatment with Fms-Like Tyrosine Kinase-3 Ligand after Burn Injury Enhances Global Immune Responses to Infection
Authors: Bohannon Julia , Cui Weihua , Cox Robert , Przkora Rene , Sherwood Edward , Toliver-Kinsky Tracy 
Published: April 2014

Abstract
Severely burned patients are susceptible to infections with opportunistic organisms due to altered immune responses and frequent wound contamination. Immunomodulation to enhance systemic and local responses to wound infections may be protective after burn injury. We previously demonstrated that pretreatments with fms-like tyrosine kinase-3 (Flt3) ligand (Flt3L), a dendritic cell growth factor, increase the resistance of mice to a subsequent burn injury and wound infection by a dendritic cell-dependent mechanism. This study was designed to test the hypothesis that Flt3L administration after burn injury decreases susceptibility to wound infections by enhancing global immune cell activation. Mice were treated with Flt3L after burn injury and examined for survival, wound and systemic bacterial clearance, and immune cell activation after wound inoculation with Pseudomonas aeruginosa. To gain insight into the local effects of Flt3L at the burn wound, localization of Langerhans cells was examined. Mice treated with Flt3L had significantly greater numbers of CD25-expressing T cells and CD69-expressing T and B cells, neutrophils, and macrophages after, but not before, infection. Overall leukocyte apoptosis in response to infection was decreased with Flt3L treatment. Survival and local and systemic bacterial clearance were enhanced by Flt3L. Langerhans cells appeared in the dermis of skin bordering the burn wound, and further increased in response to wound infection. Flt3L augmented the appearance of Langerhans cells in response to both injury and infection. These data suggest that dendritic cell enhancement by Flt3L treatments after burn injury protects against opportunistic infections through promotion of local and systemic immune responses to infection.
Dermal Dendritic Cells, and Not Langerhans Cells, Play an Essential Role in Inducing an Immune Response
Authors: Fukunaga Atsushi , Khaskhely Noor M. , Sreevidya Coimbatore S. , Byrne Scott N. , Ullrich Stephen E. 
Published: April 2014

Abstract
Langerhans cells (LCs) serve as epidermal sentinels of the adaptive immune system. Conventional wisdom suggests that LCs encounter Ag in the skin and then migrate to the draining lymph nodes, where the Ag is presented to T cells, thus initiating an immune response. Platelet-activating factor (PAF) is a phospholipid mediator with potent biological effects. During inflammation, PAF mediates recruitment of leukocytes to inflammatory sites. We herein tested a hypothesis that PAF induces LC migration. Applying 2,4-dinitro-1-fluorobenzene (DNFB) to wild-type mice activated LC migration. In contrast, applying DNFB to PAF receptor-deficient mice or mice injected with PAF receptor antagonists failed to induce LC migration. Moreover, after FITC application the appearance of hapten-laden LCs (FITC+, CD11c+, Langerin+) in the lymph nodes of PAF receptor-deficient mice was significantly depressed compared with that found in wild-type mice. LC chimerism indicates that the PAF receptor on keratinocytes but not LCs is responsible for LC migration. Contrary to the diminution of LC migration in PAF receptor-deficient mice, we did not observe any difference in the migration of hapten-laden dermal dendritic cells (FITC+, CD11c+, Langerin−) into the lymph nodes of PAF receptor-deficient mice. Additionally, the contact hypersensitivity response generated in wild-type or PAF receptor-deficient mice was identical. Finally, dermal dendritic cells, but not LCs isolated from the draining lymph nodes after hapten application, activated T cell proliferation. These findings suggest that LC migration may not be responsible for the generation of contact hypersensitivity and that dermal dendritic cells may play a more important role.
Exosomes As a Short-Range Mechanism to Spread Alloantigen between Dendritic Cells during T Cell Allorecognition
Authors: Montecalvo Angela , Shufesky William J. , Beer Stolz Donna , Sullivan Mara G. , Wang Zhiliang , Divito Sherrie J. , Papworth Glenn D. , Watkins Simon C. , Robbins Paul D. , Larregina Adriana T. , Morelli Adrian E. 
Published: April 2014

Abstract
Exosomes are nanovesicles released by different cell types including dendritic cells (DCs). The fact that exosomes express surface MHC-peptide complexes suggests that they could function as Ag-presenting vesicles or as vehicles to spread allogeneic Ags for priming of anti-donor T cells during elicitation of graft rejection or induction/maintenance of transplant tolerance. We demonstrate that circulating exosomes transporting alloantigens are captured by splenic DCs of different lineages. Internalization of host-derived exosomes transporting allopeptides by splenic DCs leads to activation of anti-donor CD4 T cells by the indirect pathway of allorecognition, a phenomenon that requires DC-derived, instead of exosome-derived, MHC class II molecules. By contrast, allogeneic exosomes are unable to stimulate direct-pathway T cells in vivo. We demonstrate in mice that although graft-infiltrating leukocytes release exosomes ex vivo, they do not secrete enough concentrations of exosomes into circulation to stimulate donor-reactive T cells in secondary lymphoid organs. Instead, our findings indicate that migrating DCs (generated in vitro or isolated from allografts), once they home in the spleen, they transfer exosomes expressing the reporter marker GFP to spleen-resident DCs. Our results suggest that exchange of exosomes between DCs in lymphoid organs might constitute a potential mechanism by which passenger leukocytes transfer alloantigens to recipient’s APCs and amplify generation of donor-reactive T cells following transplantation.
Spontaneous Renal Allograft Acceptance Associated with “Regulatory” Dendritic Cells and IDO
Authors: Cook Charles H. , Bickerstaff Alice A. , Wang Jiao-Jing , Nadasdy Tibor , Della Pelle Patricia , Colvin Robert B. , Orosz Charles G. 
Published: April 2014

Abstract
MHC-mismatched DBA/2 renal allografts are spontaneously accepted by C57BL/6 mice by poorly understood mechanisms, but both immune regulation and graft acceptance develop without exogenous immune modulation. Previous studies have shown that this model of spontaneous renal allograft acceptance is associated with TGF-β-dependent immune regulation, suggesting a role for T regulatory cells. The current study shows that TGF-β immune regulation develops 30 days posttransplant, but is lost by 150 days posttransplant. Despite loss of detectable TGF-β immune regulation, renal allografts continue to function normally for &gt;200 days posttransplantation. Because of its recently described immunoregulatory capabilities, we studied IDO expression in this model, and found that intragraft IDO gene expression progressively increases over time, and that IDO in “regulatory” dendritic cells (RDC) may contribute to regulation associated with long-term maintenance of renal allografts. Immunohistochemistry evaluation confirms the presence of both Foxp3+ T cells and IDO+ DCs in accepted renal allografts, and localization of both cell types within accepted allografts suggests the possibility of synergistic involvement in allograft acceptance. Interestingly, at the time when RDCs become detectable in spleens of allograft acceptors, ∼30% of these mice challenged with donor-matched skin allografts accept these skin grafts, demonstrating progression to “true” tolerance. Together, these data suggest that spontaneous renal allograft acceptance evolves through a series of transient mechanisms, beginning with TGF-β and T regulatory cells, which together may stimulate development of more robust regulation associated with RDC and IDO.
Absence of CTL Responses to Early Viral Antigens Facilitates Viral Persistence
Authors: Schildknecht Anita , Welti Sarah , Geuking Markus B. , Hangartner Lars , van den Broek Maries 
Published: April 2014

Abstract
CD8+ T cells are crucial for the control of intracellular pathogens such as viruses and some bacteria. Using lymphocytic choriomeningitis virus (LCMV) infection of mice—the prototypic arenavirus evolutionarily closely related to human Lassa fever and South American hemorrhagic fever viruses, we have shown previously that the kinetics of Ag presentation determine immunodominance of the LCMV-specific CTL response due to progressive exhaustion of LCMV nucleoprotein (NP)-specific CTL upon increasing viral load. In this study, we provide evidence that CTL against early LCMV NP-derived epitopes are more important in virus control than those against late glycoprotein-derived epitopes. We show that mice that are tolerant to all NP-derived T cell epitopes are severely compromised in their ability to control larger inocula of LCMV, supporting our hypothesis that CD8+ T cells specific for early viral Ags play a major role in acute virus control. Thus, the kinetics with which virus-derived T cell epitopes are presented has a strong impact on the efficacy of the antiviral immunity. This aspect should be taken into consideration for the development of vaccines.
Vesicle-Associated Membrane Protein-8/Endobrevin Negatively Regulates Phagocytosis of Bacteria in Dendritic Cells
Authors: Ho Yong Hou Sunny , Cai Deyu Tarika , Wang Cheng-Chun , Huang Dachuan , Wong Siew Heng 
Published: April 2014

Abstract
Phagocytosis is a specialized mechanism used by mammalian cells, particularly the cells of the immune system, such as dendritic cells (DC) and macrophages, to protect the host against infection. The process involves a complex cascade of pathways, from the ligation of surface receptors of phagocytes with components of the microorganism’s surface, formation of phagosomes and subsequently phagolysosomes, to the eventual presentation of foreign Ags. Vesicle-associated membrane protein (VAMP)-8/endobrevin has been shown previously to function in the endocytic pathways. Our results showed that VAMP-8 colocalized with lysosome-associated membrane protein-2, and a significant amount of VAMP-8 was recruited to the phagosomes during bacterial ingestion. However, overexpression of VAMP-8 significantly inhibited phagocytosis in DC. We also found that the phagocytic activity of VAMP-8−/− DC was significantly higher than wild-type VAMP-8+/+ DC, thus further confirming that VAMP-8 negatively regulates phagocytosis in immature DC.
Knockdown of Mgat5 Inhibits Breast Cancer Cell Growth with Activation of CD4+ T Cells and Macrophages
Authors: Li Dongqing , Li Yanmei , Wu Xianglei , Li Qiao , Yu Jing , Gen Jie , Zhang Xiao-Lian 
Published: April 2014

AbstractN-acetylglucosaminyltransferase V (Mgat5 or GnT-V) is an enzyme that catalyzes β1–6 branching of N-acetylglucosamine on asparagine (N)-linked oligosaccharides (N-glycan) of cell proteins. The levels of Mgat5 glycan products commonly are increased in malignancies. Although Mgat5 is known to be important in tumor metastases, the effects of Mgat5 on host immune responses are not fully defined. In this study, a Mgat5 specific-short hairpin RNA (shRNA) vector was transfected into murine mammary adenocarcinoma MA782 cells to assess the effects of Mgat5 on tumor cell growth, T cells, and macrophages following inoculation of mice with shRNA-transfected cancer cells. The results showed that blocking expression of Mgat5-modified glycans in MA782 cells significantly suppressed tumor progression both in vivo and in vitro, strongly stimulated Th1 cytokine production, and enhanced opsonophagocytic capability of macrophages in vivo. Importantly, reduction of complex N-glycans on MA782 tumor cells by Mgat5-shRNA resulted in significantly increased proliferation and CD45 surface expression of CD4+ T cells. Our data suggest Mgat5-shRNA could serve as a useful tool to treat breast cancer as well as a powerful tool for the functional investigation of N-glycans and glycoprotein synthesis. Our data suggest that knockdown of Mgat5 inhibits breast cancer cells’ growth with activation of CD4+ T cells and macrophages.