bluuebunny/crossref_metadata_2025 huggingface dataset:
Zinc Signals Are Essential for Lipopolysaccharide-Induced Signal Transduction in Monocytes
Authors: Haase Hajo , Ober-Blöbaum Julia L. , Engelhardt Gabriela , Hebel Silke , Heit Antje , Heine Holger , Rink Lothar
Published: April 2014

Cytosolic alterations of calcium ion concentrations are an integral part of signal transduction. Similar functions have been hypothesized for other metal ions, in particular zinc (Zn2+), but this still awaits experimental verification. Zn2+ is important for multiple cellular functions, especially in the immune system. Among other effects, it influences formation and secretion of pro-inflammatory cytokines, including TNF-α. Here we demonstrate that these effects are due to a physiological signaling system involving intracellular Zn2+ signals. An increase of the intracellular zinc ion concentration occurs upon stimulation of human leukocytes with Escherichia coli, LPS, Pam3CSK4, TNF-α, or insulin, predominantly in monocytes. Chelating this zinc signal with the membrane permeable zinc-specific chelator TPEN (N,N,N′,N′-tetrakis-(2-pyridyl-methyl)ethylenediamine) completely blocks activation of LPS-induced signaling pathways involving p38 MAPK, ERK1/2, and NF-κB, and abrogates the release of proinflammatory cytokines, including TNF-α. This function of Zn2+ is not limited to monocytes or even the immune system, but seems to be another generalized signaling system based on intracellular fluctuations of metal ion concentrations, acting parallel to Ca2+.
IL-4-Induced Selective Clearance of Oligomeric β-Amyloid Peptide1–42 by Rat Primary Type 2 Microglia
Authors: Shimizu Eisuke , Kawahara Kohichi , Kajizono Makoto , Sawada Makoto , Nakayama Hitoshi
Published: April 2014

A hallmark of immunopathology associated with Alzheimer’s disease is the presence of activated microglia (MG) surrounding senile plaque deposition of β-amyloid (Aβ) peptides. Aβ peptides are believed to be potent activators of MG, which leads to Alzheimer’s disease pathology, but the role of MG subtypes in Aβ clearance still remains unclear. In this study, we found that IL-4 treatment of rat primary-type 2 MG enhanced uptake and degradation of oligomeric Aβ1–42 (o-Aβ1–42). IL-4 treatment induced significant expression of the scavenger receptor CD36 and the Aβ-degrading enzymes neprilysin (NEP) and insulin-degrading enzyme (IDE) but reduced expression of certain other scavenger receptors. Of cytokines and stimulants tested, the anti-inflammatory cytokines IL-4 and IL-13 effectively enhanced CD36, NEP, and IDE. We demonstrated the CD36 contribution to IL-4-induced Aβ clearance: Chinese hamster ovary cells overexpressing CD36 exhibited marked, dose-dependent degradation of 125I-labeled o-Aβ1–42 compared with controls, the degradation being blocked by anti-CD36 Ab. Also, we found IL-4-induced clearance of o-Aβ1–42 in type 2 MG from CD36-expressing WKY/NCrj rats but not in cells from SHR/NCrj rats with dysfunctional CD36 expression. NEP and IDE also contributed to IL-4-induced degradation of Aβ1–42, because their inhibitors, thiorphan and insulin, respectively, significantly suppressed this activity. IL-4-stimulated uptake and degradation of o-Aβ1–42 were selectively enhanced in type 2, but not type 1 MG that express CD40, which suggests that the two MG types may play different neuroimmunomodulating roles in the Aβ-overproducing brain. Thus, selective o-Aβ1–42 clearance, which is induced by IL-4, may provide an additional focus for developing strategies to prevent and treat Alzheimer’s disease.
Human Plasmacytoid Dendritic Cells Interact with gp96 via CD91 and Regulate Inflammatory Responses
Authors: De Filippo AnnaMaria , Binder Robert J. , Camisaschi Chiara , Beretta Valeria , Arienti Flavio , Villa Antonello , Della Mina Pamela , Parmiani Giorgio , Rivoltini Licia , Castelli Chiara
Published: April 2014

Glucose-regulated stress protein gp96 is known to be involved in the host response to pathogens and to cancer. Our study explored the relationships between gp96 and human blood plasmacytoid dendritic cells (pDC) and proved that gp96 directly targets pDC by a receptor-dependent interaction. Competition studies identified CD91 as a gp96 receptor on pDC, and laser confocal imaging indicated that CD91 triggering was followed by gp96 endocytosis and trafficking into early endosomes and later into the endoplasmic reticulum compartment. Using two alternative Abs, we showed that human blood pDC reproducibly expressed CD91, although different levels of expression were detectable among the analyzed donors. Moreover, CpG-matured pDC displayed CD91 receptor up-regulation that correlated with an increased gp96 binding. Functionally, gp96-pDC interaction activated the NF-κB pathway, leading to the nuclear translocation of the NF-κB complex. gp96-treated pDC maintained an immature phenotype, while they down-modulated the release of IL-8, suggesting an anti-inflammatory role of this pathway, and they strongly up-regulated the cell surface expression of the gp96 receptor CD91. CpG-matured or gp96-treated pDC, expressing high levels of the gp96 receptor CD91, antagonized the gp96-induced activation of monocyte-derived dendritic cells in terms of cell surface phenotype and cytokine production. Altogether, these results suggest that gp96-pDC interaction might represent an active mechanism controlling the strength of the immune response to free, extracellular available gp96; this mechanism could be particularly relevant in wounds and chronic inflammation.
CCR5 Deficiency Aggravates Crescentic Glomerulonephritis in Mice
Authors: Turner Jan-Eric , Paust Hans-Joachim , Steinmetz Oliver M. , Peters Anett , Meyer-Schwesinger Catherine , Heymann Felix , Helmchen Udo , Fehr Susanne , Horuk Richard , Wenzel Ulrich , Kurts Christian , Mittrücker Hans-Willi , Stahl Rolf A. K. , Panzer Ulf
Published: April 2014

The chemokine receptor CCR5 is predominantly expressed on monocytes and Th1-polarized T cells, and plays an important role in T cell and monocyte recruitment in inflammatory diseases. To investigate the functional role of CCR5 in renal inflammation, we induced a T cell-dependent model of glomerulonephritis (nephrotoxic serum nephritis) in CCR5−/− mice. Induction of nephritis in wild-type mice resulted in up-regulation of renal mRNA expression of the three CCR5 chemokine ligands, CCL5 (15-fold), CCL3 (4.9-fold), and CCL4 (3.4-fold), in the autologous phase of the disease at day 10. The up-regulated chemokine expression was paralleled by infiltration of monocytes and T cells, followed by renal tissue injury, albuminuria, and loss of renal function. Nephritic CCR5−/− mice showed a 3- to 4-fold increased renal expression of CCL5 (61.6-fold vs controls) and CCL3 (14.1-fold vs controls), but not of CCL4, in comparison with nephritic wild-type mice, which was accompanied by augmented renal T cell and monocyte recruitment and increased lethality due to uremia. Furthermore, CCR5−/− mice showed an increased renal Th1 response, whereas their systemic humoral and cellular immune responses were unaltered. Because the CCR5 ligands CCL5 and CCL3 also act via CCR1, we investigated the effects of the pharmacological CCR1 antagonist BX471. CCR1 blockade in CCR5−/− mice significantly reduced renal chemokine expression, T cell infiltration, and glomerular crescent formation, indicating that increased renal leukocyte recruitment and consecutive tissue damage in nephritic CCR5−/− mice depended on functional CCR1. In conclusion, this study shows that CCR5 deficiency aggravates glomerulonephritis via enhanced CCL3/CCL5-CCR1-driven renal T cell recruitment.
Activation of an Immunoregulatory and Antiviral Gene Expression Program in Poly(I:C)-Transfected Human Neutrophils
Authors: Tamassia Nicola , Le Moigne Vincent , Rossato Marzia , Donini Marta , McCartney Stephen , Calzetti Federica , Colonna Marco , Bazzoni Flavia , Cassatella Marco A.
Published: April 2014

Neutrophils, historically known for their involvement in acute inflammation, are also targets for infection by many different DNA and RNA viruses. However, the mechanisms by which they recognize and respond to viral components are poorly understood. Polyinosinic:polycytidylic acid (poly(I:C)) is a synthetic mimetic of viral dsRNA that is known to interact either with endosomal TLR3 (not expressed by human neutrophils) or with cytoplasmic RNA helicases such as melanoma differentiation-associated gene 5 (MDA5) and retinoic acid-inducible gene I (RIG-I). In this study, we report that intracellularly administered poly(I:C) stimulates human neutrophils to specifically express elevated mRNA levels encoding type I IFNs, immunoregulatory cytokines, and chemokines, such as TNF-α, IL-12p40, CXCL10, CXCL8, CCL4, and CCL20, as well as classical IFN-responsive genes (IRG), including IFIT1 (IFN-induced protein with tetratricopeptide repeats 1)/IFN-stimulated gene (ISG)56, G1P2/ISG15, PKR (dsRNA-dependent protein kinase), and IFN-regulatory factor (IRF)7. Investigations into the mechanisms whereby transfected poly(I:C) promotes gene expression in neutrophils uncovered a crucial involvement of the MAPK-, PKR-, NF-κB-, and TANK (TNF receptor-associated NF-κB kinase)-binding kinase (TBK1)/IRF3-signaling transduction pathways, as illustrated by the use of specific pharmacological inhibitors. Consistent with the requirement of the cytoplasmic dsRNA pathway for antiviral signaling, human neutrophils were found to constitutively express significant levels of both MDA5 and RIG-I, but not TLR3. Accordingly, neutrophils isolated from MDA5-deficient mice had a partial impairment in the production of IFN-β and TNF-α upon infection with encephalomyocarditis virus. Taken together, our data demonstrate that neutrophils are able to activate antiviral responses via helicase recognition, thus acting at the frontline of immunity against viruses.
Up-Regulation of Vascular Endothelial Growth Factor-D Expression in Clear Cell Renal Cell Carcinoma by CD74: A Critical Role in Cancer Cell Tumorigenesis
Authors: Liu Yu-Huei , Lin Chang-Yueh , Lin Wei-Chou , Tang Sai-Wen , Lai Ming-Kuen , Lin Jung-Yaw
Published: April 2014

Elevation of CD74 is associated with a number of human cancers, including clear cell renal cell carcinoma (ccRCC). To understand the role of CD74 in the oncogenic process of ccRCC, we ectopically expressed CD74 in human embryonic kidney 293 cells (HEK/CD74) and evaluated its oncogenic potential. Through overexpression of CD74 in HEK293 and Caki-2 cells and down-regulation of CD74 in Caki-1 cells, we show that vascular endothelial growth factor-D (VEGF-D) expression is modified accordingly. A significant, positive correlation between CD74 and VEGF-D is found in human ccRCC tissues (Pearson’s correlation, r = 0.65, p < 0.001). In HEK/CD74 xenograft mice, CD74 significantly induced the formation of tumor masses, increased tumor-induced angiogenesis, and promoted cancer cell metastasis. Blockage of VEGF-D expression by small interference RNA resulted in a decrease in cell proliferation, invasion, and cancer cell-induced HUVEC migration enhanced by CD74. Furthermore, we provide evidence that the intracellular signaling cascade responsible for VEGF-D up-regulation by CD74 is both PI3K/AKT- and MEK/ERK-dependent, both of which are associated with NF-κB nuclear translocation and DNA-binding activity. These results suggest that VEGF-D is crucial for CD74-induced human renal carcinoma cancer cell tumorigenesis.
Carcinoembryonic Antigen-Specific but Not Antiviral CD4+ T Cell Immunity Is Impaired in Pancreatic Carcinoma Patients
Authors: Tassi Elena , Gavazzi Francesca , Albarello Luca , Senyukov Vladimir , Longhi Renato , Dellabona Paolo , Doglioni Claudio , Braga Marco , Di Carlo Valerio , Protti Maria Pia
Published: April 2014

Pancreatic carcinoma is a very aggressive disease with dismal prognosis. Although evidences for tumor-specific T cell immunity exist, factors related to tumor microenvironment and the presence of immunosuppressive cytokines in patients’ sera have been related to its aggressive behavior. Carcinoembryonic Ag (CEA) is overexpressed in 80–90% of pancreatic carcinomas and contains epitopes recognized by CD4+ T cells. The aim of this study was to evaluate the extent of cancer-immune surveillance and immune suppression in pancreatic carcinoma patients by comparing the anti-CEA and antiviral CD4+ T cell immunity. CD4+ T cells from 23 normal donors and 44 patients undergoing surgical resection were tested for recognition of peptides corresponding to CEA and viral naturally processed promiscuous epitopes by proliferation and cytokine release assays. Anti-CEA CD4+ T cell immunity was present in a significantly higher number of normal donors than pancreatic cancer patients. Importantly, whereas CD4+ T cells from normal donors produced mainly GM-CSF and IFN-γ, CD4+ T cells from the patients produced mainly IL-5, demonstrating a skew toward a Th2 type. On the contrary, the extent of antiviral CD4+ T cell immunity was comparable between the two groups and showed a Th1 type. The immunohistochemical analysis of tumor-infiltrating lymphocytes showed a significantly higher number of GATA-3+ compared with T-bet+ lymphoid cells, supporting a Th2 skew also at the tumor site. Collectively, these results demonstrate that Th2-immune deviation in pancreatic cancer is not generalized but tumor related and suggests that the skew might be possibly due to factor(s) present at the tumor site.
Immunodominant Epitopes in Herpes Simplex Virus Type 2 Glycoprotein D Are Recognized by CD4 Lymphocytes from Both HSV-1 and HSV-2 Seropositive Subjects
Authors: Kim Min , Taylor Janette , Sidney John , Mikloska Zorka , Bodsworth Neil , Lagios Katerina , Dunckley Heather , Byth-Wilson Karen , Denis Martine , Finlayson Robert , Khanna Rajiv , Sette Alessandro , Cunningham Anthony L.
Published: April 2014

In human recurrent cutaneous herpes simplex, there is a sequential infiltrate of CD4 and then CD8 lymphocytes into lesions. CD4 lymphocytes are the major producers of the key cytokine IFN-γ in lesions. They recognize mainly structural proteins and especially glycoproteins D and B (gD and gB) when restimulated in vitro. Recent human vaccine trials using recombinant gD showed partial protection of HSV seronegative women against genital herpes disease and also, in placebo recipients, showed protection by prior HSV1 infection. In this study, we have defined immunodominant peptide epitopes recognized by 8 HSV1+ and/or 16 HSV2+ patients using 51Cr-release cytotoxicity and IFN-γ ELISPOT assays. Using a set of 39 overlapping 20-mer peptides, more than six immunodominant epitopes were defined in gD2 (two to six peptide epitopes were recognized for each subject). Further fine mapping of these responses for 4 of the 20-mers, using a panel of 9 internal 12-mers for each 20-mers, combined with MHC II typing and also direct in vitro binding assay of these peptides to individual DR molecules, showed more than one epitope per 20-mers and promiscuous binding of individual 20-mers and 12-mers to multiple DR types. All four 20-mer peptides were cross-recognized by both HSV1+/HSV2− and HSV1−/HSV2+ subjects, but the sites of recognition differed within the 20-mers where their sequences were divergent. This work provides a basis for CD4 lymphocyte cross-recognition of gD2 and possibly cross-protection observed in previous clinical studies and in vaccine trials.
Strategic Nonmyeloablative Conditioning: CD154:CD40 Costimulatory Blockade at Primary Bone Marrow Transplantation Promotes Engraftment for Secondary Bone Marrow Transplantation after Engraftment Failure
Authors: Xu Hong , Huang Yiming , Chilton Paula M. , Hussain Lala-Rukh , Tanner Michael K. , Yan Jun , Ildstad Suzanne T.
Published: April 2014

There is an increased risk of failure of engraftment following nonmyeloablative conditioning. Sensitization resulting from failed bone marrow transplantation (BMT) remains a major challenge for secondary BMT. Approaches to allow successful retransplantation would have significant benefits for BMT candidates living with chronic diseases. We used a mouse model to investigate the effect of preparative regimens at primary BMT on outcome for secondary BMT. We found that conditioning with TBI or recipient T cell lymphodepletion at primary BMT did not promote successful secondary BMT. In striking contrast, successful secondary BMT could be achieved in mice conditioned with anti-CD154 costimulatory molecule blockade at first BMT. Blockade of CD154 alone or combined with T cell depletion inhibits generation of the humoral immune response after primary BMT, as evidenced by abrogation of production of anti-donor Abs. The humoral barrier is dominant in sensitization resulting from failed BMT, because almost all CFSE-labeled donor cells were killed at 0.5 and 3 h in sensitized recipients in in vivo cytotoxicity assay, reflecting Ab-mediated cytotoxicity. CD154:CD40 costimulatory blockade used at primary BMT promotes allogeneic engraftment in secondary BMT after engraftment failure at first BMT. The prevention of generation of anti-donor Abs at primary BMT is critical for successful secondary BMT.
Characterization of the Antibody Response against NeuGcGM3 Ganglioside Elicited in Non-Small Cell Lung Cancer Patients Immunized with an Anti-Idiotype Antibody
Authors: Hernández Ana María , Toledo Darién , Martínez Darel , Griñán Tania , Brito Victor , Macías Amparo , Alfonso Sailyn , Rondón Teresa , Suárez Eduardo , Vázquez Ana María , Pérez Rolando
Published: April 2014

1E10 mAb is an anti-Id murine mAb (Ab2 mAb) specific for an Ab1 mAb that reacts with NeuGc-containing gangliosides, sulfatides, and Ags expressed in some human tumors. In preclinical studies, this Ab2 Ab was able to mimic NeuGc-containing gangliosides only in animals lacking expression of these Ags in normal tissues. In this study, we report on the immune responses elicited in 20 non-small cell lung cancer patients treated with 1 mg of aluminum hydroxide-precipitated 1E10 mAb. In the hyperimmune sera from 16 of 20 patients, a strong specific Ab response of both IgM and IgG isotypes against NeuGcGM3 ganglioside was observed. Patient immune sera were able to induce complement-independent cell death of NeuGcGM3-expressing X63 murine myeloma target cells. Significant immunoreactivity to NeuGcGM3 was still detected after the complete abrogation of the reactivity against 1E10 mAb by the adsorption of patient sera with this Ab. We hypothesize that Id−Ag+ Abs could reflect the activation of an autologous idiotypic cascade into the patients. Both Id+Ag+ and Id−Ag+ fractions were separated by affinity chromatography and characterized. Although IgG isotype Abs were found in both fractions, IgM isotype Abs were found only in the Id−Ag+ fraction. Both Id+Ag+ and Id−Ag+ Abs were able to specifically recognize and induce cell death in NeuGcGM3-expressing X63 myeloma target cells. Patients that developed IgG and/or IgM Abs against NeuGcGM3 showed longer median survival times.
Immunization with a Mimotope of GD2 Ganglioside Induces CD8+ T Cells That Recognize Cell Adhesion Molecules on Tumor Cells
Authors: Wierzbicki Andrzej , Gil Margaret , Ciesielski Michael , Fenstermaker Robert A. , Kaneko Yutaro , Rokita Hanna , Lau Joseph T. , Kozbor Danuta
Published: April 2014

The GD2 ganglioside expressed on neuroectodermal tumor cells has been used as a target for passive and active immunotherapy in patients with malignant melanoma and neuroblastoma. We have reported that immunization of mice with a 47-LDA mimotope of GD2, isolated from a phage display peptide library with anti-GD2 mAb 14G2a, induces MHC class I-restricted CD8+ T cell responses to syngeneic neuroblastoma tumor cells. The cytotoxic activity of the vaccine-induced CTLs was independent of GD2 expression, suggesting recognition of a novel tumor-associated Ag cross-reacting with 47-LDA. Glycan microarray and immunoblotting studies using 14G2a mAb demonstrated that this Ab is highly specific for the entire carbohydrate motif of GD2 but also cross-reacts with a 105 kDa glycoprotein expressed by GD2+ and GD2− neuroblastoma and melanoma cells. Functional studies of tumor cells grown in three-dimensional collagen cultures with 14G2a mAb showed decreases in matrix metalloproteinase-2 activation, a process regulated by the 105 kDa-activated leukocyte cell adhesion molecule (ALCAM/CD166). A recombinant CD166 glycoprotein was shown to be recognized by 14G2a Ab and inhibition of CD166 expression by RNA interference ablated the cell sensitivity to lysis by 47-LDA-induced CD8+ T cells in vitro and in vivo. The binding of 14G2a to CD166 was not disruptable by a variety of exo- and endo-glycosidases, implying recognition of a non-glycan epitope on CD166. These results suggest that the vaccine-induced CTLs recognize a 47-LDA cross-reactive epitope expressed by CD166, and reveal a novel mechanism of induction of potent tumor-specific cellular responses by mimotopes of tumor-associated carbohydrate Ags.
Bone Marrow-Derived IFN-Producing Killer Dendritic Cells Account for the Tumoricidal Activity of Unpulsed Dendritic Cells
Authors: Himoudi Nourredine , Nabarro Stephen , Buddle Jo , Eddaoudi Ayad , Thrasher Adrian J. , Anderson John
Published: April 2014

The CD11cintB220+NK1.1+CD49+ subset of cells has recently been described as IFN-producing killer dendritic cells (IKDC), which share phenotypic and functional properties of dendritic cells and NK cells. Herein we show that bone marrow-derived murine dendritic cell preparations contain abundant CD11cintB220+NK1.1+CD49+ cells, the removal of which results in loss of tumoricidal activity of unpulsed dendritic cells in vivo. Moreover, following s.c. injection, as few as 5 × 103 highly pure bone marrow-derived IKDC cells are capable of shrinking small contralateral syngeneic tumors in C57BL/6 mice, but not in immunodeficient mice, implying the obligate involvement of host effector cells in tumor rejection. Our data suggest that bone marrow-derived IKDC represent a population that has powerful tumoricidal activity in vivo.
Crucial Role of Aspartic Acid at Position 265 in the CH2 Domain for Murine IgG2a and IgG2b Fc-Associated Effector Functions
Authors: Baudino Lucie , Shinohara Yasuro , Nimmerjahn Falk , Furukawa Jun-Ichi , Nakata Munehiro , Martínez-Soria Eduardo , Petry Franz , Ravetch Jeffery V. , Nishimura Shin-Ichiro , Izui Shozo
Published: April 2014

Replacement of aspartic acid by alanine at position 265 (D265A) in mouse IgG1 results in a complete loss of interaction between this isotype and low-affinity IgG Fc receptors (FcγRIIB and FcγRIII). However, it has not yet been defined whether the D265A substitution could exhibit similar effects on the interaction with two other FcγR (FcγRI and FcγRIV) and on the activation of complement. To address this question, 34-3C anti-RBC IgG2a and IgG2b switch variants bearing the D265A mutation were generated, and their effector functions and in vivo pathogenicity were compared with those of the respective wild-type Abs. The introduction of the D265A mutation almost completely abolished the binding of 34-3C IgG2a and IgG2b to all four classes of FcγR and the activation of complement. Consequently, these mutants were hardly pathogenic. Although oligosaccharide side chains of these mutants were found to contain higher levels of sialic acids than those of wild-type Abs, the analysis of enzymatically desialylated D265A variants ruled out the possibility that very poor Fc-associated effector functions of the D265A mutants were due to an increased level of the mutant Fc sialylation. Thus, our results demonstrate that aspartic acid at position 265 is a residue critically implicated in triggering the Fc-associated effector functions of IgG, probably by defining a crucial three-dimensional structure of the Fc region.
CD69+CD4+CD25− T Cells, a New Subset of Regulatory T Cells, Suppress T Cell Proliferation through Membrane-Bound TGF-β1
Authors: Han Yanmei , Guo Qiuli , Zhang Minggang , Chen Zhubo , Cao Xuetao
Published: April 2014

The underlying mechanisms of tumor-induced immune suppression need to be fully understood. Regulatory T (Treg) cells have been shown to play an important role in tumor immune escape. Until now, many subsets of Treg cells have been described that can suppress T cell response via different mechanisms. CD69 is generally regarded as one of the activating markers; however, recent studies show that CD69 may exert regulatory function in the immune response. In this study, we have identified tumor-induced CD69+CD4+CD25− T cells as a new subset of CD4+ Treg cells. CD69+CD4+CD25− T cells increase dramatically along tumor progression, with up to 40% of CD4+ T cells in the advanced tumor-bearing mice. Distinct from the previously described CD4+ Treg cell subsets, CD69+CD4+CD25− T cells express high CD122, but they do not express Foxp3 and secrete IL-10, TGF-β1, IL-2, and IFN-γ. CD69+CD4+CD25− T cells are hyporesponsive and can suppress CD4+ T cell proliferation in a cell-cell contact manner. Interestingly, the fixed CD69+CD4+CD25− T cells still have suppressive activity, and neutralizing Abs against TGF-β1 can block their suppressive activity. We found that CD69+CD4+CD25− T cells express membrane-bound TGF-β1, which mediates suppression of T cell proliferation. Furthermore, engagement of CD69 maintains high expression of membrane-bound TGF-β1 on CD69+CD4+CD25− T cells via ERK activation. Our results demonstrate that CD69+CD4+CD25− T cells act as a new subset of regulatory CD4+ T cells, with distinct characteristics of negative expression of Foxp3, no secretion of IL-10, but high expression of CD122 and membrane-bound TGF-β1. Our data contribute to the better understanding of mechanisms for tumor immune escape.
An Essential Role for the Stalk Region of CD8β in the Coreceptor Function of CD8
Authors: Rettig Lorna , McNeill Louise , Sarner Nitza , Guillaume Philippe , Luescher Immanuel , Tolaini Mauro , Kioussis Dimitris , Zamoyska Rose
Published: April 2014

The CD8αβ heterodimer is integral to the selection of the class I-restricted lineage in the thymus; however, the contribution of the CD8β chain to coreceptor function is poorly understood. To understand whether the CD8β membrane proximal stalk region played a role in coreceptor function, we substituted it with the corresponding sequence from the CD8α polypeptide and expressed the hybrid molecule in transgenic mice in place of endogenous CD8β. Although the stalk-swapped CD8β was expressed on the cell surface as a disulfide-bonded heterodimer at equivalent levels of expression to an endogenous CD8β molecule, it failed to restore selection of CD8+ class I MHC-restricted T cells and it altered the response of peripheral T cells. Thus, the stalk region of the CD8β polypeptide has an essential role in ensuring functionality of the CD8αβ heterodimer and its replacement compromises the interaction of CD8 with peptide-MHC complexes.
Checkpoints in the Development of Thymic Cortical Epithelial Cells
Authors: Shakib Saba , Desanti Guillaume E. , Jenkinson William E. , Parnell Sonia M. , Jenkinson Eric J. , Anderson Graham
Published: April 2014

In the thymus, interactions between immature thymocytes and thymic epithelial cells (TECs) regulate the development and selection of self-tolerant MHC-restricted T cells. Despite the importance of cortical (cTEC) and medullary (mTEC) thymic epithelial cells in fostering T cell production, events in TEC development are still unclear. Although precursor-product relationships during mTEC development have been reported, and some genetic regulators of mTEC development have been identified, stages in cTEC development occurring downstream of recently identified bipotent cTEC/mTEC progenitors remain poorly defined. In this study, we combine analysis of differentiation, proliferation, and gene expression of TECs in the murine thymus, that has enabled us to identify cTEC progenitors, define multiple stages in cTEC development, and identify novel checkpoints in development of the cTEC lineage. We show an essential requirement for FoxN1 in the initial development of cTEC from bipotent progenitors, and demonstrate a stage-specific requirement for CD4−8− thymocytes in later stages of cTEC development. Collectively, our data establish a program of cTEC development that should provide insight into the formation and function of the thymic cortex for T cell development.
Deviation of the B Cell Pathway in Senescent Mice Is Associated with Reduced Surrogate Light Chain Expression and Altered Immature B Cell Generation, Phenotype, and Light Chain Expression
Authors: Alter-Wolf Sarah , Blomberg Bonnie B. , Riley Richard L.
Published: April 2014

B lymphopoiesis in aged mice is characterized by reduced B cell precursors and an altered Ab repertoire. This likely results, in part, from reduced surrogate L chains in senescent B cell precursors and compromised pre-BCR checkpoints. Herein, we show that aged mice maintain an ordinarily minor pool of early c-kit+ pre-B cells, indicative of poor pre-BCR expression, even as pre-BCR competent early pre-B cells are significantly reduced. Therefore, in aged mice, B2 B lymphopoiesis shifts from dependency on pre-BCR expansion and selection to more pre-BCR-deficient pathways. B2 c-kit+ B cell precursors, from either young or aged mice, generate new B cells in vitro that are biased to larger size, higher levels of CD43, and decreased κ L chain expression. Notably, immature B cells in aged bone marrow exhibit a similar phenotype in vivo. We hypothesize that reduced surrogate L chain expression contributes to decreased pre-B cells in aged mice. The B2 pathway is partially blocked with limited B cell development and reduced pre-BCR expression and signaling. In old age, B2 pathways have limited surrogate L chain and increasingly generate new B cells with altered phenotype and L chain expression.
Levels of Foxp3 in Regulatory T Cells Reflect Their Functional Status in Transplantation
Authors: Chauhan Sunil K. , Saban Daniel R. , Lee Hyung K. , Dana Reza
Published: April 2014

Foxp3 expressing CD4+CD25+ regulatory T cells (Tregs) have been shown to prevent allograft rejection in clinical and animal models of transplantation. However, the role of Foxp3 in regulating Treg function, and the kinetics and mechanism of action of Tregs in inducing allograft tolerance in transplantation, are still not fully understood. Thus, we investigated the kinetics and function of Tregs in a mouse model of orthotopic corneal transplantation, the most common form of tissue grafting worldwide. In this study, using in vitro functional assays and in vivo Treg adoptive transfer assays, we show that far more relevant than Treg frequency is their level of Foxp3 expression, which is directly associated with the potential of Tregs to prevent allograft rejection by producing regulatory cytokines and suppressing effector T cell activation. In addition, our data clearly demonstrate that Tregs primarily suppress the induction of alloimmunity in regional draining lymph nodes rather than suppressing the effector phase of the immune response in the periphery. These findings provide new insights on Treg dynamics in transplantation, which are crucial for designing therapeutic strategies to modulate Treg function and to optimize Treg-based cell therapies for clinical translation.
TCRμ Recombination and Transcription Relative to the Conventional TCR during Postnatal Development in Opossums
Authors: Parra Zuly E. , Baker Michelle L. , Lopez April M. , Trujillo Jonathan , Volpe Joseph M. , Miller Robert D.
Published: April 2014

Marsupials are a distinct lineage of mammals notable for giving birth to highly altricial (relatively less developed) young. The recent discovery of a unique TCR chain in marsupials, TCRμ, raises questions about its possible role in early development. Here we compare the timing of V(D)J recombination and appearance of TCRμ transcripts relative to the conventional TCRα, β, γ, and δ mRNA during postnatal development in the opossum. There are two TCRμ transcript isoforms, TCRμ1.0 and TCRμ2.0. TCRμ1.0, which uses prejoined V(D)J segments, is detectable as early as day 1, when the thymus is primarily undifferentiated epithelium. The other isoform, TCRμ2.0, which requires V(D)J recombination and contains an unusual double V configuration, is not detectable until day 13 when the thymus is histologically mature. Surprisingly, we were able to detect TCRα, β, and δ mRNA transcribed from loci that had completed V(D)J recombination as early as day 1 as well. At this early age there is apparent evidence for preference in the V segments used in the TCRα and β genes. In the case of Vα this preference appears to be associated with position in the TCRα/δ locus. In Vβ, however, preference may be due to the use of microhomology in the V, D, and J segments. Mature TCRγ transcripts were not detected until day 8, suggesting that, in contrast to eutherian mammals, in the opossum αβ T cell development precedes γδ T cell development. The results support that there may be differences in T cell subset development between marsupials and placental mammals.
Ly49D Engagement on T Lymphocytes Induces TCR-Independent Activation and CD8 Effector Functions That Control Tumor Growth
Authors: Merck Estelle , Voyle Roger B. , MacDonald H. Robson
Published: April 2014

Recent data showing expression of activating NK receptors (NKR) by conventional T lymphocytes raise the question of their role in the triggering of TCR-independent responses that could be damaging for the host. Transgenic mice expressing the activating receptor Ly49D/DAP12 offer the opportunity to better understand the relevance of ITAM signaling in the biology of T cells. In vitro experiments showed that Ly49D engagement on T lymphocytes by a cognate MHC class I ligand expressed by Chinese hamster ovary (CHO) cells or by specific Ab triggered cellular activation of both CD4 and CD8 populations with modulation of activation markers and cytokine production. The forced expression of the ITAM signaling chain DAP12 is mandatory for Ly49D-transgenic T cell activation. In addition, Ly49D stimulation induced T lymphocyte proliferation, which was much stronger for CD8 T cells. Phenotypic analysis of anti-Ly49D-stimulated CD8 T cells and their ability to produce high levels of IFN-γ and to kill target cells indicate that Ly49D ligation generates effector cytotoxic CD8 T cells. Ly49D engagement by itself also triggered cytotoxic activity of activated CD8 T cells. Adoptive transfer experiments confirmed that Ly49D-transgenic CD8 T cells are able to control growth of CHO tumor cells or RMA cells transfected with Hm1-C4, the Ly49D ligand normally expressed by CHO. In conclusion, Ly49D engagement on T cells leads to T cell activation and to a full range of TCR-independent effector functions of CD8 T cells.
CD4+ Th-APC with Acquired Peptide/MHC Class I and II Complexes Stimulate Type 1 Helper CD4+ and Central Memory CD8+ T Cell Responses
Authors: Umeshappa Channakeshava Sokke , Huang Hui , Xie Yufeng , Wei Yangdou , Mulligan Sean J. , Deng Yulin , Xiang Jim
Published: April 2014

T cell-T cell Ag presentation is increasingly attracting attention. We previously showed that the in vitro OVA-pulsed dendritic cell (DCOVA)-activated CD4+ Th cells acquired OVA peptide/MHC (pMHC) class I and costimulatory molecules such as CD54 and CD80 from DCOVA and acted as CD4+ Th-APC capable of stimulating OVA-specific CD8+ CTL responses. In this study, we further applied the OVA-specific TCR-transgenic OT I and OT II mice with deficiency of various cytokines or costimulatory molecule genes useful for studying the molecular mechanisms underlying in Th-APC’s stimulatory effect. We demonstrated that DCOVA-stimulated OT II CD4+ Th-APC also acquired costimulatory molecules such as CD40, OX40L, and 4-1BBL and the functional pMHC II complexes by DCOVA activation. CD4+ Th-APC with acquired pMHC II and I were capable of stimulating CD4+ Th1 and central memory CD8+44+CD62LhighIL-7R+ T cell responses leading to antitumor immunity against OVA-expressing mouse B16 melanoma. Their stimulatory effect on CD8+ CTL responses and antitumor immunity is mediated by IL-2 secretion, CD40L, and CD80 signaling and is specifically targeted to CD8+ T cells in vivo via acquired pMHC I. In addition, CD4+ Th-APC expressing OVA-specific TCR, FasL, and perforin were able to kill DCOVA and neighboring Th-APC expressing endogenous and acquired pMHC II. Taken together, we show that CD4+ Th-APC can modulate immune responses by stimulating CD4+ Th1 and central memory CD8+ T cell responses and eliminating DCOVA and neighboring Th-APC. Therefore, our findings may have great impacts in not only the antitumor immunity, but also the regulatory T cell-dependent immune tolerance in vivo.
Insights into the Role of STAT3 in Human Lymphocyte Differentiation as Revealed by the Hyper-IgE Syndrome
Authors: Tangye Stuart G. , Cook Matthew C. , Fulcher David A.
Published: April 2014

“Experiments of nature” due to single gene mutations resulting in human immunodeficiency states have revealed critical roles for several genes in regulating lymphocyte development and the generation of protective immunity. Recently, heterozygous mutations in STAT3 were found to cause autosomal dominant hyper-IgE syndrome, a condition affecting not only the immune system but also other mesenchymal and ectodermal tissues, including bones, cranium, teeth, and skin. STAT proteins operate to integrate signals from surface receptors, including cytokine receptors, that regulate growth and differentiation of multiple cell lineages. In this article, we will review how the study of STAT3 deficiency in humans and mice has highlighted nonredundant roles of STAT3, and of specific cytokines, in diverse cellular processes such as antimicrobial immunity and protection at epithelial barriers, the generation of functional humoral immune responses, bone formation, and keratinocyte biology.
Follistatin-Like Protein 1 Promotes Arthritis by Up-Regulating IFN-γ
Authors: Clutter Suzanne D. , Wilson David C. , Marinov Anthony D. , Hirsch Raphael
Published: April 2014

Follistatin-like protein-1 (FSTL-1) is a poorly characterized protein that is up-regulated in the early stage of collagen-induced arthritis and that exacerbates arthritis when delivered by gene transfer. The current study was designed to determine the mechanism by which FSTL-1 promotes arthritis. FSTL-1 was injected into mouse paws, resulting in severe paw swelling associated with up-regulation of IFN-γ transcript and the IFN-γ-induced chemokine, CXCL10. Mice depleted of T cells were protected. A central role for IFN-γ was confirmed by the finding that mice deficient in IFN-γ failed to exhibit paw swelling in response to injection of FSTL-1. Furthermore, IFN-γ secretion from mouse spleen cells exposed to a weak TCR signal was increased 5-fold in the presence of FSTL-1. FSTL-1 could be induced by innate immune signals, including TLR4 agonists and the arthritogenic cytokine, IL-1β, via an NFκB pathway. Finally, FSTL-1 was found to be overexpressed in human arthritis and its neutralization inhibited murine collagen-induced arthritis and suppressed IFN-γ and CXCL10 production in arthritic joints. These findings demonstrate that FSTL-1 plays a critical role in arthritis by enhancing IFN-γ signaling pathways and suggest a mechanism by which FSTL-1 bridges innate and adaptive immune responses.
Epigenetic Regulation of Foxp3 Expression in Regulatory T Cells by DNA Methylation
Authors: Lal Girdhari , Zhang Nan , van der Touw William , Ding Yaozhong , Ju Wenjun , Bottinger Erwin P. , Reid St. Patrick , Levy David E. , Bromberg Jonathan S.
Published: April 2014

Foxp3, a winged-helix family transcription factor, serves as the master switch for CD4+ regulatory T cells (Treg). We identified a unique and evolutionarily conserved CpG-rich island of the Foxp3 nonintronic upstream enhancer and discovered that a specific site within it was unmethylated in natural Treg (nTreg) but heavily methylated in naive CD4+ T cells, activated CD4+ T cells, and peripheral TGFβ-induced Treg in which it was bound by DNMT1, DNMT3b, MeCP2, and MBD2. Demethylation of this CpG site using the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (Aza) induced acetylation of histone 3, interaction with TIEG1 and Sp1, and resulted in strong and stable induction of Foxp3. Conversely, IL-6 resulted in methylation of this site and repression of Foxp3 expression. Aza plus TGFβ-induced Treg resembled nTreg, expressing similar receptors, cytokines, and stable suppressive activity. Strong Foxp3 expression and suppressor activity could be induced in a variety of T cells, including human CD4+CD25− T cells. Epigenetic regulation of Foxp3 can be predictably controlled with DNMT inhibitors to generate functional, stable, and specific Treg.
CTLA-4 Controls Regulatory T Cell Peripheral Homeostasis and Is Required for Suppression of Pancreatic Islet Autoimmunity
Authors: Schmidt Emily M. , Wang Chun Jing , Ryan Gemma A. , Clough Louise E. , Qureshi Omar S. , Goodall Margaret , Abbas Abul K. , Sharpe Arlene H. , Sansom David M. , Walker Lucy S. K.
Published: April 2014

The CTLA-4 pathway is recognized as a major immune inhibitory axis and is a key therapeutic target for augmenting antitumor immunity or curbing autoimmunity. CTLA-4-deficient mice provide the archetypal example of dysregulated immune homeostasis, developing lethal lymphoproliferation with multiorgan inflammation. In this study, we show that surprisingly these mice have an enlarged population of Foxp3+ regulatory T cells (Treg). The increase in Treg is associated with normal thymic output but enhanced proliferation of Foxp3+ cells in the periphery. We confirmed the effect of CTLA-4 deficiency on the Treg population using OVA-specific Treg which develop normally in the absence of CTLA-4, but show increased proliferation in response to peripheral self-Ag. Functional analysis revealed that Ag-specific Treg lacking CTLA-4 were unable to regulate disease in an adoptive transfer model of diabetes. Collectively, these data suggest that the proliferation of Treg in the periphery is tuned by CTLA-4 signals and that Treg expression of CTLA-4 is required for regulation of pancreas autoimmunity.
Antibodies to MHC Class I Induce Autoimmunity: Role in the Pathogenesis of Chronic Rejection
Authors: Fukami Naohiko , Ramachandran Sabarinathan , Saini Deepti , Walter Michael , Chapman William , Patterson G. Alexander , Mohanakumar Thalachallour
Published: April 2014

Alloimmunity to mismatched donor HLA-Ags and autoimmunity to self-Ags have been hypothesized to play an important role in immunopathogenesis of chronic rejection of transplanted organs. However, it is not known what role, if any, alloimmune response plays in inducing autoimmunity. To test whether Ab-developed posttransplantation to mismatched donor MHC induces autoimmunity and chronic rejection, we developed a murine model wherein anti-MHC class I Abs or control (C1.18.4/anti-keratin) were administered intrabronchially into native lungs. Animals receiving anti-MHC class I, but not control Abs, developed marked cellular infiltration around vessels and bronchiole of lung by day 15, followed by epithelial hyperplasia, fibrosis, and occlusion of the distal airways similar to chronic rejection following human lung transplantation. Lungs of mice receiving anti-MHC class I showed increased expression of chemokines, their receptors, and growth factors, and induced IL-17 as well as de novo Abs to self-Ags, K-α1 tubulin, and collagen V. IL-17 neutralization by anti-IL-17 resulted in reduction of autoantibody and lesions induced by anti-MHC class I Abs. Thus, our results indicate that Abs to donor MHC can induce autoimmunity, mediated by IL-17, which plays a pivotal role in chronic rejection postlung transplantation. Therefore, approaches to prevent autoimmunity should be considered for the treatment of chronic rejection postlung transplantation.
Estradiol Increases IL-8 Secretion of Normal Human Breast Tissue and Breast Cancer In Vivo
Authors: Bendrik Christina , Dabrosin Charlotta
Published: April 2014

IL-8 or CXCL8 has been associated with tumor angiogenesis, metastasis, and poor prognosis in breast cancer. Estrogen is crucial in breast carcinogenesis and tumor progression. Whether sex steroids affect IL-8 secretion of normal breast tissue or breast cancer is not known. Several cell types in a tissue secrete IL-8. Hence, regulatory mechanisms of IL-8 need to be investigated in whole tissue. We used microdialysis to sample IL-8 in normal human breast tissue in situ in pre- and postmenopausal women, preoperatively in breast cancers of women, and in experimental breast cancer in mice. We found a significant positive correlation between IL-8 and estradiol in normal breast tissue and hormone-dependent breast cancer in vivo. Ex vivo, estradiol exposure increased the IL-8 secretion of normal whole breast tissue in culture. In experimental breast cancer, estradiol increased IL-8 whereas the anti-estrogen tamoxifen inhibited the secretion of IL-8 both in vitro and extracellularly in vivo in tumors of nude mice. An anti-IL-8 Ab inhibited endothelial cell proliferation induced by cancer cell produced IL-8 and tumors with low IL-8 levels exhibited decreased angiogenesis. Our results strongly suggest that estradiol has a critical role in the regulation of IL-8 in normal human breast tissue and human breast cancer. IL-8 may present a novel therapeutic target for estrogen driven breast carcinogenesis and tumor progression.
Cutting Edge: Down-Regulation of MHC Class I-Related Chain A on Tumor Cells by IFN-γ-Induced MicroRNA
Authors: Yadav Deepak , Ngolab Jennifer , Lim Rod Seung-Hwan , Krishnamurthy Siddharth , Bui Jack D.
Published: April 2014

NKG2D is a receptor used by NK cells to detect virally infected and transformed cells. It recognizes ligands that are expressed constitutively on primary tumors and tumor cell lines. In this report, we have identified four microRNAs (miRNAs) that each was sufficient to reduce the expression of the NKG2D ligand MHC class I-related chain A (MICA). One of these miRNAs (miR-520b) was induced by IFN-γ, leading to a reduction in MICA surface protein levels. Interestingly, miR-520b acted on both the MICA 3′-untranslated region and the promoter region and caused a decrease in the levels of MICA transcript. In contrast, an antisense oligonucleotide inhibitor of miR-520b increased the expression of a reporter construct containing the MICA 3′-untranslated region but not the MICA promoter region. These findings demonstrate the novel regulation of an NKG2D ligand by an endogenous microRNA that is itself induced by IFN-γ.
Influence of B Cell Antigen Receptor Expression Level on Pathways of B Cell Tolerance Induction
Authors: Liu Xiaohe , Shen Shixue , Manser Tim
Published: April 2014

We have described an Ig-transgenic, autoreactive B cell clonotype that undergoes a novel tolerance pathway. Early in development this clonotype expresses average BCR levels, but these levels are progressively down-regulated as development proceeds efficiently to the mature, follicular compartment. This clonotype does not display conventional features of anergy and can be induced to undergo apoptosis and receptor editing in in vitro bone marrow cultures, but these pathways are not taken in vivo. These data suggested that autoantigen-driven down-regulation of BCR levels and, hence, avidity for autoantigen allows this clonotype to bypass conventional tolerance mechanisms. To test this idea, we enforced elevated levels of expression of BCR in this clonotype by making the transgenic Igh locus homozygous. This resulted in retarded clonotype development and L chain receptor editing in vivo. These data support a pivotal role for adaptive, autoantigen-induced adjustment of BCR expression levels in the regulation of primary B cell development and tolerance.