bluuebunny/crossref_metadata_2025_split huggingface dataset:
The CD16+ Monocyte Subset Is More Permissive to Infection and Preferentially Harbors HIV-1 In Vivo
Authors: Ellery Philip J. , Tippett Emma , Chiu Ya-Lin , Paukovics Geza , Cameron Paul U. , Solomon Ajantha , Lewin Sharon R. , Gorry Paul R. , Jaworowski Anthony , Greene Warner C. , Sonza Secondo , Crowe Suzanne M. 
Published: April 2014

Abstract
HIV-1 persists in peripheral blood monocytes in individuals receiving highly active antiretroviral therapy (HAART) with viral suppression, despite these cells being poorly susceptible to infection in vitro. Because very few monocytes harbor HIV-1 in vivo, we considered whether a subset of monocytes might be more permissive to infection. We show that a minor CD16+ monocyte subset preferentially harbors HIV-1 in infected individuals on HAART when compared with the majority of monocytes (CD14highCD16−). We confirmed this by in vitro experiments showing that CD16+ monocytes were more susceptible to CCR5-using strains of HIV-1, a finding that is associated with higher CCR5 expression on these cells. CD16+ monocytes were also more permissive to infection with a vesicular stomatitis virus G protein-pseudotyped reporter strain of HIV-1 than the majority of monocytes, suggesting that they are better able to support HIV-1 replication after entry. Consistent with this observation, high molecular mass complexes of apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) were observed in CD16+ monocytes that were similar to those observed in highly permissive T cells. In contrast, CD14highCD16− monocytes contained low molecular mass active APOBEC3G, suggesting this is a mechanism of resistance to HIV-1 infection in these cells. Collectively, these data show that CD16+ monocytes are preferentially susceptible to HIV-1 entry, more permissive for replication, and constitute a continuing source of viral persistence during HAART.
Recombinant gp120 Vaccine-Induced Antibodies Inhibit Clinical Strains of HIV-1 in the Presence of Fc Receptor-Bearing Effector Cells and Correlate Inversely with HIV Infection Rate
Authors: Forthal Donald N. , Gilbert Peter B. , Landucci Gary , Phan Tran 
Published: April 2014

Abstract
Nonneutralizing Abs may play a role in protecting animals and humans from lentiviral infections. We explored the Ab-dependent, cell-mediated virus inhibition (ADCVI) Ab response to recombinant gp120 (rgp120) vaccination in sera from 530 participants in the Vax 004 trial. Serum ADCVI activity was measured against a clinical R5 strain of HIV-1 using peripheral blood mononuclear effector cells from healthy donors. The level of vaccine-induced ADCVI activity correlated inversely with the rate of acquiring HIV infection following vaccination, such that for every 10% increase in ADCVI activity, there was a 6.3% decrease in the hazard rate of infection (p = 0.019). Some vaccinated individuals also mounted an ADCVI response against two other clinical R5 strains of HIV-1. However, ADCVI activity correlated poorly with neutralizing or CD4-gp120-blocking Ab activity measured against laboratory strains. Finally, the degree to which the ADCVI Ab response predicted the rate of infection was influenced by polymorphisms at the FcγRIIa and FcγRIIIa gene loci. These data indicate that rgp120 vaccination can elicit Abs with antiviral activity against clinical strains of HIV-1. However, such activity requires the presence of FcR-bearing effector cells. Our results provide further evidence that ADCVI may play a role in preventing HIV infection.
The CCL3 Family of Chemokines and Innate Immunity Cooperate In Vivo in the Eradication of an Established Lymphoma Xenograft by Rituximab
Authors: Cittera Elena , Leidi Marzia , Buracchi Chiara , Pasqualini Fabio , Sozzani Silvano , Vecchi Annunciata , Waterfield J. Douglas , Introna Martino , Golay Josée 
Published: April 2014

Abstract
The therapeutic mAb rituximab induced the expression of the CCL3 and CCL4 chemokines in the human lymphoma line BJAB following binding to the CD20 Ag. Induction of CCL3/4 in vitro was specific, was observed in several cell lines and freshly isolated lymphoma samples and also took place at the protein level in vitro and in vivo. To investigate the role of these β-chemokines in the mechanism of action of rituximab, we synthesized a N-terminally truncated CCL3 molecule CCL3(11–70), which had antagonist activity on chemotaxis mediated by either CCL3 or BJAB supernatant. We also set up an established s.c. BJAB tumor model in athymic mice. Rituximab, given weekly after tumors had reached 250 mm2, led to complete disappearance of the lymphoma within 2–3 wk. Treatment of mice with cobra venom factor showed that complement was required for rituximab therapeutic activity. Treatment of BJAB tumor bearing mice every 2 days with the CCL3(11–70) antagonist, starting 1 wk before rituximab treatment, had no effect on tumor growth by itself, but completely inhibited the therapeutic activity of the Ab. To determine whether CCL3 acts through recruitment/activation of immune cells, we specifically depleted NK cells, polymorphonuclear cells, and macrophages using mAbs, clodronate treatment, or Rag2−/−cγ−/− mice. The data demonstrated that these different cell populations are involved in BJAB tumor eradication. We propose that rituximab rapidly activates complement and induces β-chemokines in vivo, which in turn activate the innate immunity network required for efficient eradication of the bulky BJAB tumor.
TNF-α Induction of GM2 Expression on Renal Cell Carcinomas Promotes T Cell Dysfunction
Authors: Raval Gira , Biswas Soumika , Rayman Patricia , Biswas Kaushik , Sa Gaurisankar , Ghosh Sankar , Thornton Mark , Hilston Cynthia , Das Tanya , Bukowski Ronald , Finke James , Tannenbaum Charles S. 
Published: April 2014

AbstractPrevious studies from our laboratory demonstrated the role of tumor-derived gangliosides as important mediators of T cell apoptosis, and hence, as one mechanism by which tumors evade immune destruction. In this study, we report that TNF-α secreted by infiltrating inflammatory cells and/or genetically modified tumors augments tumor-associated GM2 levels, which leads to T cell death and immune dysfunction. The conversion of weakly apoptogenic renal cell carcinoma (RCC) clones to lines that can induce T cell death requires 3–5 days of TNF-α pretreatment, a time frame paralleling that needed for TNF-α to stimulate GM2 accumulation by SK-RC-45, SK-RC-54, and SK-RC-13. RCC tumor cell lines permanently transfected with the TNF-α transgene are similarly toxic for T lymphocytes, which correlates with their constitutively elevated levels of GM2. TNF-α increases GM2 ganglioside expression by enhancing the mRNA levels encoding its synthetic enzyme, GM2 synthase, as demonstrated by both RT-PCR and Southern analysis. The contribution of GM2 gangliosides to tumor-induced T cell death was supported by the finding that anti-GM2 Abs significantly blocked T cell apoptosis mediated by TNF-α-treated tumor cells, and by the observation that small interfering RNA directed against TNF-α abrogated GM2 synthase expression by TNF-transfected SK-RC-45, diminished its GM2 accumulation, and inhibited its apoptogenicity for T lymphocytes. Our results indicate that TNF-α signaling promotes RCC-induced killing of T cells by stimulating the acquisition of a distinct ganglioside assembly in RCC tumor cells.
Telomerase in T Lymphocytes: Use It and Lose It?
Authors: Akbar Arne N. , Vukmanovic-Stejic Milica 
Published: April 2014

AbstractThe enzyme telomerase counteracts telomere loss in proliferating cells and extends their capacity for replication. The importance of telomerase is highlighted by the award of the 2006 Albert Lasker Prize for Basic Medical Research for its discovery. Malignant cells subvert telomerase induction to their advantage, and up-regulation of this enzyme confers these populations with unlimited proliferative potential with obvious detrimental consequences. However this enzyme is also essential for the lifelong maintenance of normal cell populations that have a high rate of turnover. Thymic involution in early adulthood dictates that memory T cell populations have to be maintained by continuous proliferation. This highlights the inherent paradox that telomerase down-regulation in T cells may protect against malignancy yet also lead to replicative exhaustion of repeatedly activated memory T cells. In this article, we review the data on telomerase regulation in T lymphocytes and the implications this has for the maintenance of T cell memory.
Cutting Edge: TLR2 Directly Triggers Th1 Effector Functions
Authors: Imanishi Takayuki , Hara Hiromitsu , Suzuki Shinobu , Suzuki Nobutaka , Akira Shizuo , Saito Takashi 
Published: April 2014

Abstract
Toll-like receptors recognize pathogen-associated molecular patterns, activate innate immunity, and consequently modulate adaptive immunity in response to infections. TLRs are also expressed on T cells, and it has been shown that T cell activation is modulated by TLR ligands. However, the functions of TLRs on Th1 and Th2 effector cells and the molecular mechanisms underlying TLR-mediated activation are not fully understood. We analyzed TLR functions and downstream signaling events in both effector T cells. In mouse Th1 cells the stimulation by TLR2 but not by other TLRs directly induced IFN-γ production, cell proliferation, and cell survival without TCR stimulation, and these effects were greatly enhanced by IL-2 or IL-12 through the enhanced activation of MAPKs. In contrast, no TLR affected the function of effector Th2 cells. These results identify TLR2 as a new specific activator of Th1 cell function and imply the involvement in Th1-mediated responses.
Cutting Edge: Regulatory T Cells Induce CD4+CD25−Foxp3− T Cells or Are Self-Induced to Become Th17 Cells in the Absence of Exogenous TGF-β
Authors: Xu LiLi , Kitani Atsushi , Fuss Ivan , Strober Warren 
Published: April 2014

Abstract
Recent studies have shown that TGF-β together with IL-6 induce the differentiation of IL-17-producing T cells (Th17) T cells. We therefore examined whether CD4+CD25+Foxp3+ regulatory T cells, i.e., cells previously shown to produce TGF-β, serve as Th17 inducers. We found that upon activation purified CD25+ T cells (or sorted GFP+ T cells obtained from Foxp3-GFP knockin mice) produce high amounts of soluble TGF-β and when cultured with CD4+CD25−Foxp3− T cells in the presence of IL-6 induce the latter to differentiate into Th17 cells. Perhaps more importantly, upon activation, CD4+CD25+Foxp3+(GFP+) T cells themselves differentiate into Th17 cells in the presence of IL-6 (and in the absence of exogenous TGF-β). These results indicate that CD4+CD25+Foxp3+ regulatory T cells can function as inducers of Th17 cells and can differentiate into Th17 cells. They thus have important implications to our understanding of regulatory T cell function and their possible therapeutic use.
Cutting Edge: Th17 and Regulatory T Cell Dynamics and the Regulation by IL-2 in the Tumor Microenvironment
Authors: Kryczek Ilona , Wei Shuang , Zou Linhua , Altuwaijri Saleh , Szeliga Wojciech , Kolls Jay , Chang Alfred , Zou Weiping 
Published: April 2014

Abstract
Th17 cells play an active role in inflammation and autoimmune diseases. However, the nature and regulation of Th17 in the context of tumor immunity remain unknown. In this study, we show that parallel to regulatory T (Treg) cells, IL-17+ CD4+ and CD8+ T cells are kinetically induced in multiple tumor microenvironments in mice and humans. Treg cells play a crucial role in tumor immune pathogenesis and temper immune therapeutic efficacy. IL-2 is crucial for the production and function of Treg cells. We now show that IL-2 reduces IL-17+ T cell differentiation in the tumor microenvironment accompanied with an enhanced Treg cell compartment in vitro and in vivo. Altogether, our work demonstrates a dynamic differentiation of IL-17+ T cells in the tumor microenvironment, reveals a novel role for IL-2 in controlling the balance between IL-17+ and Treg cells, and provides new insight of IL-17+ T cells in tumor immune pathology and therapy.
Distinct Roles of Different NF-κB Subunits in Regulating Inflammatory and T Cell Stimulatory Gene Expression in Dendritic Cells
Authors: Wang Junmei , Wang Xingyu , Hussain Sofia , Zheng Ye , Sanjabi Shomyseh , Ouaaz Fatah , Beg Amer A. 
Published: April 2014

Abstract
TLRs play a critical role in inducing inflammatory and immune responses against microbial agents. In this study, we have investigated the role of NF-κB transcription factors in regulating TLR-induced gene expression in dendritic cells, a key APC type. The p50 and cRel NF-κB subunits were found to be crucial for regulating genes important for dendritic cell-induced T cell responses (e.g., CD40, IL-12, and IL-18) but not for genes encoding inflammatory cytokines (e.g., TNF-α, IL-1α, and IL-6). In striking contrast, the RelA subunit was crucial for expression of inflammatory cytokine genes but not T cell stimulatory genes. These novel findings reveal a fundamentally important difference in biological function of genes regulated by different NF-κB subunits. Focusing on RelA target gene specificity mechanisms, we investigated whether the κB site and/or the unique composition of RelA played the most crucial role. Surprisingly, studies of IL-6 expression showed that the κB site is not a primary determinant of RelA target gene specificity. Instead, a major specificity mechanism is the unique ability of RelA to interact with the transcriptional coactivator CREB-binding protein, a function not shared with the closely related cRel subunit. Together, our findings indicate novel and critically important overall roles of NF-κB in TLR-induced gene expression that are mediated by unique functions of distinct subunits.
Vaccinia Virus-Specific CD4+ T Cell Responses Target a Set of Antigens Largely Distinct from Those Targeted by CD8+ T Cell Responses
Authors: Moutaftsi Magdalini , Bui Huynh-Hoa , Peters Bjoern , Sidney John , Salek-Ardakani Shahram , Oseroff Carla , Pasquetto Valerie , Crotty Shane , Croft Michael , Lefkowitz Elliot J. , Grey Howard , Sette Alessandro 
Published: April 2014

Abstract
Recent studies have defined vaccinia virus (VACV)-specific CD8+ T cell epitopes in mice and humans. However, little is known about the epitope specificities of CD4+ T cell responses. In this study, we identified 14 I-Ab-restricted VACV-specific CD4+ T cell epitopes by screening a large set of 2146 different 15-mer peptides in C57BL/6 mice. These epitopes account for ∼20% of the total anti-VACV CD4+ T cell response and are derived from 13 different viral proteins. Surprisingly, none of the CD4+ T cell epitopes identified was derived from VACV virulence factors. Although early Ags were recognized, late Ags predominated as CD4+ T cell targets. These results are in contrast to what was previously found in CD8+ T cells responses, where early Ags, including virulence factors, were prominently recognized. Taken together, these results highlight fundamental differences in immunodominance of CD4+ and CD8+ T cell responses to a complex pathogen.
Regulation of Cell Adhesion by Affinity and Conformational Unbending of α4β1 Integrin
Authors: Chigaev Alexandre , Waller Anna , Zwartz Gordon J. , Buranda Tione , Sklar Larry A. 
Published: April 2014

Abstract
Rapid activation of integrins in response to chemokine-induced signaling serves as a basis for leukocyte arrest on inflamed endothelium. Current models of integrin activation include increased affinity for ligand, molecular extension, and others. In this study, using real-time fluorescence resonance energy transfer to assess α4β1 integrin conformational unbending and fluorescent ligand binding to assess affinity, we report at least four receptor states with independent regulation of affinity and unbending. Moreover, kinetic analysis of chemokine-induced integrin conformational unbending and ligand-binding affinity revealed conditions under which the affinity change was transient whereas the unbending was sustained. In a VLA-4/VCAM-1-specific myeloid cell adhesion model system, changes in the affinity of the VLA-4-binding pocket were reflected in rapid cell aggregation and disaggregation. However, the initial rate of cell aggregation increased 9-fold upon activation, of which only 2.5-fold was attributable to the increased affinity of the binding pocket. These data show that independent regulation of affinity and conformational unbending represents a novel and fundamental mechanism for regulation of integrin-dependent adhesion in which the increased affinity appears to account primarily for the increasing lifetime of the α4β1 integrin/VCAM-1 bond, whereas the unbending accounts for the increased capture efficiency.
Induction of Tolerance in CD8+ T Cells to a Transgenic Autoantigen Expressed in the Liver Does Not Require Cross-Presentation
Authors: Morimoto Junko , Tan Xiaoxio , Teague Ryan M. , Öhlén Claes , Greenberg Philip D. 
Published: April 2014

Abstract
Cross-presentation of normal self and candidate tumor Ags by bone marrow (BM)-derived APCs that have not been activated has been demonstrated as a major mechanism contributing to acquisition of tolerance by mature T cells that first encounter an Ag in the periphery (cross-tolerance). Following adoptive transfer of naive TCR-transgenic CD8+ T cells into a host expressing a transgenic Ag that is a potentially targetable tumor Ag in normal hepatocytes as a self-Ag, we found that the majority of Ag-specific CD8+ T cells were deleted, with the remaining cells rendered anergic. Studies in BM chimeric mice and with purified cell populations demonstrated that these events were not dependent on cross-presentation by BM-derived APCs including Kupffer cells or liver sinusoidal endothelial cells, and apparently can occur entirely as a consequence of direct recognition of Ag endogenously processed and presented by hepatocytes. Direct recognition of Ag-expressing hepatocytes in vivo induced a proliferative response and up-regulation of activation markers in responding CD8+ T cells, but proliferating cells did not accumulate, with most cells rapidly eliminated, and the persisting T cells lost the capacity to proliferate in response to repeated Ag stimulation. The results suggest that parenchymal tissues may retain the capacity to directly regulate in vivo responses to self-Ags processed and presented in the context of class I MHC molecules.
Type 2 Diabetes Impairs Insulin Receptor Substrate-2-Mediated Phosphatidylinositol 3-Kinase Activity in Primary Macrophages to Induce a State of Cytokine Resistance to IL-4 in Association with Overexpression of Suppressor of Cytokine Signaling-3
Authors: O’Connor Jason C. , Sherry Christina L. , Guest Christopher B. , Freund Gregory G. 
Published: April 2014

Abstract
Chronic elevation of proinflammatory markers in type 2 diabetes (T2D) is well defined, but the role of anti-inflammatory cytokines in T2D is less clear. In this study, we report that normal IL-4-dependent elaboration of IL-1 receptor antagonist (IL-1RA) requires IRS-2-mediated PI3K activity in primary macrophages. We also show that macrophages isolated from obese/diabetic db/db mice have impaired IRS-2-mediated PI3K activity and constitutively overexpress suppressor of cytokine signaling (SOCS)-3, which impairs an important IL-4 anti-inflammatory function. Peritoneal proinflammatory cytokine levels were examined in diabese (db/db) mice, and IL-6 was found to be nearly 7-fold higher than in nondiabese (db/+) control mice. Resident peritoneal macrophages were isolated from db/db mice and were found to constitutively overexpress IL-6 and were unable to elaborate IL-1RA in response to IL-4-like db/+ mouse macrophages. Inhibition of PI3K with wortmannin or blockage of IRS-2/PI3K complex formation with a cell permeable IRS-2-derived tyrosine phosphopeptide inhibited IL-4-dependent IL-1RA production in db/+ macrophages. Examination of IL-4 signaling in db/db macrophages revealed that IL-4-dependent IRS-2/PI3K complex formation and IRS-2 tyrosine phosphorylation was reduced compared with db/+ macrophages. SOCS-3/IL-4 receptor complexes, however, were increased in db/db mouse macrophages compared with db/+ mice macrophages as was db/db mouse macrophage SOCS-3 expression. These results indicate that in the db/db mouse model of T2D, macrophage expression of SOCS-3 is increased, and impaired IL-4-dependent IRS-2/PI3K formation induces a state of IL-4 resistance that disrupts IL-4-dependent production of IL-1RA.
Distinct Subsets of FoxP3+ Regulatory T Cells Participate in the Control of Immune Responses
Authors: Stephens Geoffrey L. , Andersson John , Shevach Ethan M. 
Published: April 2014

AbstractExpression of the transcription factor FoxP3 is the hallmark of regulatory T cells that play a crucial role in dampening immune responses. A comparison of the development and phenotype of FoxP3+ T cells in relation to the expression of conventional MHC molecules facilitated the identification of several distinct lineages of naive and effector/memory populations of Foxp3+ T cells. One subpopulation of effector/memory Foxp3+ T cells develops in the thymic medulla, whereas the second is thymic independent. Both lineages display a distinct activated phenotype, undergo extensive steady-state proliferation, home to sites of acute inflammation, and are unique in their capacity to mediate Ag-nonspecific suppression of T cell activation directly ex vivo. Effector FoxP3+ T cells may act as a sentinel of tolerance, providing a first line of defense against potentially harmful responses by rapidly suppressing immunity to peripheral self-Ags.
Altered Innate Immune Functioning of Dendritic Cells in Elderly Humans: A Role of Phosphoinositide 3-Kinase-Signaling Pathway
Authors: Agrawal Anshu , Agrawal Sudhanshu , Cao Jia-Ning , Su Houfen , Osann Kathryn , Gupta Sudhir 
Published: April 2014

AbstractAging represents a state of paradox where chronic inflammation is associated with declining immune responses. Dendritic cells (DCs) are the major APCs responsible for initiating an immune response. However, DC functions in aging have not been studied in detail. In this study, we have compared the innate immune functions of monocyte-derived myeloid DCs from elderly subjects with DCs from young individuals. We show that although phenotypically comparable, DCs from the aging are functionally different from DCs from the young. In contrast to DCs from the young, DCs from elderly individuals display 1) significantly reduced capacity to phagocytose Ags via macropinocytosis and endocytosis as determined by flow cytometry; 2) impaired capacity to migrate in vitro in response to the chemokines MIP-3β and stromal cell-derived factor-1; and 3) significantly increased LPS and ssRNA-induced secretion of TNF-α and IL-6, as determined by ELISA. Investigations of intracellular signaling revealed reduced phosphorylation of AKT in DCs from the aging, indirectly suggesting decreased activation of the PI3K pathway. Because the PI3K-signaling pathway plays a positive regulatory role in phagocytosis and migration, and also functions as a negative regulator of TLR signaling by inducing activation of p38 MAPK, this may explain the aberrant innate immune functioning of DCs from elderly subjects. Results from real-time PCR and protein expression by flow cytometry demonstrated an increased expression of phosphatase and tensin homolog, a negative regulator of the PI3K-signaling pathway, in DCs from the aging. Increased phosphatase and tensin homolog may thus be responsible for the defect in AKT phosphorylation and, therefore, the altered innate immune response of DCs from elderly humans.