bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transgenic mice with hematopoietic and lymphoid specific expression of Cre
Authors: de Boer Jasper , Williams Adam , Skavdis George , Harker Nicola , Coles Mark , Tolaini Mauro , Norton Trisha , Williams Keith , Roderick Kathleen , Potocnik Alexandre J. , Kioussis Dimitris 
Published: February 2003

AbstractBacteriophage P1 Cre/loxP based systems can be used to manipulate the genomes of mice in vivo and in vitro, allowing the generation of tissue‐specific conditional mutants. Wehave generated mouse lines expressing Cre recombinase in hematopoietic tissues using the vav regulatory elements, or in lymphoid cells using the hCD2 promoter and locus control region (LCR). The R26R‐EYFP Cre reporter mouse line was used to determine the pattern of Cre expression in each line and enabled the assessment of Cre activity at a single‐cell level. Analysis showed that the vav promoter elements were able to direct Cre‐mediated recombination in all cells of the hematopoietic system. The hCD2 promoter and LCR on the other hand were able to drive Cre‐mediated recombination only in T cells and B cells, but not in other hematopoietic cell types. Furthermore, in the appropriate tissues, deletion of the floxed target was complete in all cells, thereby excluding the possibility of variegated expression of the Cre transgene. Both of these Cre‐transgenic lines will be useful in generating tissue‐specific gene deletions within all the cells of hematopoietic or lymphoid tissues.
Outer membrane protein A renders dendritic cells and macrophages responsive to CCL21 and triggers dendritic cell migration to secondary lymphoid organs
Authors: Jeannin Pascale , Magistrelli Giovanni , Herbault Nathalie , Goetsch Liliane , Godefroy Sylvie , Charbonnier Peggy , Gonzalez Alexandra , Delneste Yves 
Published: February 2003

AbstractOuter membrane protein A (OmpA) is a class of bacterial cell wall protein that is immunogenic without adjuvant. As specific immune responses are initiated in the lymph nodes (LN), we analyzed the effect of the OmpA from Klebsiella pneumoniae (KpOmpA) on chemokine/chemokine receptor expression by APC and on cell migration to the LN. Upon contact with KpOmpA, human immature DC andmacrophages acquire CCR7 expression and responsiveness to CCL21. In parallel, CCR1 and CCR5 expression is down‐regulated and CXCL8, CCL2, CCL3 and CCL5 production is up‐regulated. Mice injected subcutaneously with KpOmpA present a transient inflammatory reaction at the site of injection accompanied by an enlargement of the draining LN with a higher proportion of DC and macrophages. Lastly, when exposed to KpOmpA prior injection, DC but not macrophages migrate to the draining LN. In conclusion, KpOmpA confers a migratory phenotype to DC and triggers their migration to the
regional LN. This property contributes to explain how innate cells initiate adaptive immune response upon recognition of conserved bacterial components and also why OmpA is immunogenic in the absence of adjuvant.
Somatic hypermutation does not require Rad54 and Rad54B‐mediated homologous recombination
Authors: Bross Linda , Wesoly Joanna , Buerstedde Jean‐Marie , Kanaar Roland , Jacobs Heinz 
Published: February 2003

AbstractSecondary diversification of immunoglobulin (Ig) genes occurs through somatic hypermutation (SHM) in B cells of the germinal center (GC). The GC reaction is associated with a high frequency ofDNA double‐strand breaks (DSB) in the hypermutation domain of Ig genes. Homologous recombination (HR) is a prominent DSB repair pathway. Among the proteins involved in HR are the Rad‐54 paralogues,Rad54 and Rad54B. To investigate whether Rad54/Rad54B‐mediated HR is involved in SHM, we determined the ratio of mutated versus non‐mutated Vλ PCR products from memory (IgM–, IgD–, Vλ1+) and GC (PNAhigh, Vλ1+) B cells, the mutation load, the mutation frequency, the base exchange pattern and the distribution of somatic mutations along the rearranged Vλ light chain (VλLC) genes. All these parameters of SHM were unaltered in memory and GC B cells lacking one or both Rad54 paralogues. Thus, our data indicate that Rad54 and Rad54B‐mediated HR is not essential for SHM. In addition, the finding that the ablation of RAD51 paralogues causes an increase in SHM argues against a direct involvement of HR in promoting SHM.
Disparate peptide‐dependent thymic selection outcomes in β2M‐deficient mice versus TAP‐1‐deficient mice: implications for repertoire formation
Authors: Sasada Tetsuro , Yang Yuting , Lai Char‐Chang , Touma Maki , Clayton Linda K. , Liu Jin‐huan , Parisini Emilio , Wang Jia‐huai , Reinherz Ellis L. 
Published: February 2003

AbstractFetal thymic organ cultures of N15‐transgenic RAG‐2–/– H‐2b mice on normal, β‐2 microglobulin (β2M)–/– or transporter associated with antigen processing (TAP‐1)–/– MHCI‐deficient backgrounds were used to examine differentiation of thymocytes bearing a TCR specific for a viral peptide bound to H‐2Kb. Strong agonists mediate negative selection in all mice whereas weak agonists are positively selecting in β2M–/– mice but negatively selecting on TAP‐1–/– or normal backgrounds. Very weak agonists and very weak antagonists are generally without effect in β2M–/– mice yet foster differentiation in TAP‐1–/– animals. The 20–40‐fold reduction in β2M–/– thymic H‐2Kb surface expression suggests that the avidity of the TCR for peptide–MHCI accounts for these differences, consistent with effects of TCR density and individual thymic‐peptide abundance in peptide–MHC complexes. TCR–self‐MHC interaction dominates Kb‐based selection, subtly modulated by peptides as revealed by X‐ray crystallography.
Downmodulation of antigen presentation by H2‐O in B cell lines and primary B lymphocytes
Authors: Brocke Pascale , Armandola Elena , Garbi Natalio , Hämmerling Günter J. 
Published: February 2003

AbstractPeptide loading onto MHC class II molecules takes place in endosomal compartments along the endocytic pathway. There, loading is facilitated by the catalytic function of the accessory moleculeH2‐M, which helps to exchange the invariant chain‐derived CLIP peptide in the groove of class II molecules for antigenic peptide. H2‐O is another accessory molecule specific to the class II pathway, which is found tightly associated with H2‐M and selectively expressed in B cells. Using stable H2‐O ribozyme‐antisense transfectants, H2‐O overexpressing murine B cell lines, and H2‐O‐transgenic mice, we investigated the effects of H2‐O on antigen presentation. The results show that presentation of a variety of exogenous protein antigens to a panel of T cell hybridomas depended on the levelsof H2‐O in the antigen‐presenting B cells. Thus, increased H2‐O expression downmodulated, whereas reduced H2‐O levels, enhanced presentation. Presentation of endogenous antigen was also diminished by H2‐O. Despite the pronounced effects on antigen presentation, the mass spectrometric profiles of peptides eluted from Ab molecules were very similar in cells expressing different H2‐O levels. Theintracellular location of H2‐O inhibitory activity was investigated with the drug chloroquine, which prevents acidification of the endocytic pathway. The observations indicate that H2‐O predominantly inhibits antigen presentation in early endosomal compartments. Thus, H2‐O appears to skew peptide loading to late endosomal/lysosomal compartments. This may favor presentation of antigens taken up by the B cell receptor.
IL‐4 regulates IL‐12 p40 expression post‐transcriptionally as well as via a promoter‐based mechanism
Authors: Seegmüller Irene , Häcker Hans , Wagner Hermann 
Published: February 2003

AbstractIL‐12 and IL‐4, respectively, dominate Th1 versus Th2 polarization. Additionally IL‐4 can inhibit IL‐12 p40 production in DC. Here we show that macrophages respond to bacterial CpG‐DNA with IL‐12 p40 production in an IL‐4‐sensitive manner. Analysis of the molecular mechanism of this inhibition shows that IL‐4 acts by reducing the stability of IL‐12 p40 mRNA as well as by affecting promoter activity. IL‐4 did not affect early CpG‐DNA‐induced signal transduction. However, IL‐4 reduced the activity of the IL‐12 p40 promoter and when de novo transcription of IL‐12 p40 mRNA was blocked,IL‐4 led to acceleration of IL‐12 p40 mRNA degradation. These data show that IL‐4 regulates IL‐12 p40 expression by influencing promoter activity and by interfering with mRNA stability.
Mice transgenic for intracellular interleukin‐1 receptor antagonist type 1 are protected from collagen‐induced arthritis
Authors: Palmer Gaby , Talabot‐Ayer Dominique , Szalay‐Quinodoz Ildiko , Maret Michel , Arend William P. , Gabay Cem 
Published: February 2003

AbstractInterleukin‐1 receptor antagonist (IL‐1Ra) is a natural IL‐1 inhibitor, which competitively inhibits binding of IL‐1 to its receptors. IL‐1Ra is produced as four different isoforms, one secreted (sIL‐1Ra) and three intracellular (icIL‐1Ra1, 2, 3), derived from the same gene. We previously observed increased production of icIL‐1Ra1 in the joints of mice with collagen‐induced arthritis (CIA). However, due to its intracellular localization, the biological role of icIL‐1Ra1 remains unknown. The aim of the present study was to examine the effect of the icIL‐1Ra1 isoform, as compared to that of sIL‐1Ra, in the CIA model by comparing transgenic (tg) mice overexpressing icIL‐1Ra1 or sIL‐1Ra to their wild‐type littermates. Serum levels of tg human IL‐1Ra were elevated in sIL‐1Ra and, to a lesser extent, also in icIL‐1Ra1 mice. Clinical scoring indicated that none of the icIL‐1Ra1 or sIL‐1Ra tg mice developed CIA, whereas arthritis was present in, respectively, 60% and 100% of their wild‐type littermates. Histological and radiological analyses confirmed the absence of arthritis in icIL‐1Ra1 and sIL‐1Ra tg mice. Accordingly, circulating levels of the acute‐phase protein serum amyloid A tended to be lower in icIL‐1Ra1 tg mice than in their wild‐type littermates and were significantly lower in sIL‐1Ra tg mice than in controls. In contrast, no difference was observed between the groups regarding serum levels of anti‐type II collagen antibodies and ex vivo spleen cell proliferative response to collagen. In conclusion, icIL‐1Ra1, which is released into the extracellular space when produced in high amounts, has a similar anti‐arthritic effect as sIL‐1Ra.
Normal B‐1 cell development but defective BCR signaling in LCK–/– mice
Authors: Ulivieri Cristina , Valensin Silvia , Majolini M. Bernardetta , Matthews R. James , Baldari Cosima T. 
Published: February 2003

AbstractMature B cells are grouped into two major subsets, B‐1 and B‐2, believed to derive from separate lineages. We have recently shown that B‐1 cells, which are characterized by CD5 surface expression, specifically exhibit significant levels of the tyrosine kinase Lck in man. Here we show that also in mice Lck expression is restricted to B‐1 cells and address the potential role of Lck in B‐1 cell development and activation. Using as a model an Lck–/– mouse, we show that, while dispensable for B‐1 cell development, Lck is required for full and sustained activation of the tyrosine phosphorylation and MAP kinase cascades triggered by the BCR in CD5+, B‐1 cells. The data suggest a potential role for Lck in the achievement of the higher activation threshold required for productive BCR signaling in B‐1 as compared to B‐2 cells.
T cell costimulation by the hepatitis C virus envelope protein E2 binding to CD81 is mediated by Lck
Authors: Soldaini Elisabetta , Wack Andreas , D'Oro Ugo , Nuti Sandra , Ulivieri Cristina , Baldari Cosima T. , Abrignani Sergio 
Published: February 2003

AbstractBinding of the hepatitis C virus (HCV) envelope protein E2 to CD81 provides a costimulatory signal for human T cells. This phenomenon may play a role in liver damage and autoimmune manifestations associated with HCV infection. Here we show that cross‐linking of CD81 by HCV E2 induced a calcium flux in T cells that depends on Lck since it was blocked by PP1 and absent in Lck‐deficient Jurkat T cells. In wild‐type Jurkat cells, Lck was activated by CD81 cross‐linking, and CD81, like Lck, was found in lipid rafts. Indeed, the integrity of the raft compartment was required for the induction of a calcium flux by E2, since methyl‐β‐cyclodextrin abolished this response. A requirement for TCR/CD3 expression was indicated by the absence of a calcium flux following E2 stimulation of TCR/CD3‐deficient Jurkat cells. CD81 cross‐linking increased and prolonged the anti‐CD3‐induced tyrosine phosphorylation of TCRζ and of other proteins, indicating that the CD81‐mediated signal converges with the TCR/CD3 signaling cascade at its most upstream step. In conclusion, we propose that the costimulatory effects of HCV E2 on T cells depend on CD81 cross‐linking that activates Lck through raft aggregation and thus leads to enhanced TCR signaling.
Involvement of macrophage mannose receptor in the binding and transmission of HIV by macrophages
Authors: Nguyen Deborah Greene , Hildreth James E. K. 
Published: February 2003

AbstractThe human immunodeficiency virus (HIV) is an enveloped virus whose surface glycoprotein gp120 binds CD4 on target cell membranes to initiate infection. About half of the carbohydrates on gp120are terminally mannosylated, a pattern common to many pathogens. We have examined the ability of macrophage mannose receptor (MMR) on primary monocyte‐derived macrophages to bind HIV and facilitateits transmission to T cells. We adapted the tyramide signal amplification system for fluorescence detection of HIV bound to macrophages. Our data show that approximately 60% of the initial association of HIV with macrophages that lack expression of DC‐SIGN (a dendritic cell‐specific ICAM‐3 receptor/HIV‐1‐binding protein) is MMR mediated, as evidenced by inhibition with mannan, D‐mannose, EDTA, and soluble mannose‐binding lectin, but not by D‐galactose. This inhibition is not seen in cells that lack MMR. Macrophages are able to mediate transmission of bound HIV to co‐cultured T cells, and this transmission is blocked up to 80% by inhibitors of MMR binding. Unlike virus bound to DC‐SIGN, macrophage‐bound HIV has a slightly lower half‐life compared to free virus, with no transmission in co‐culture observed beyond 24 h after virus binding to macrophages. Results obtained with endocytosis inhibitors indicate that this decrease in viral longevity is due to rapid internalization of macrophage‐bound HIV. Together, these results suggest a substantial role for MMR in the binding and transmission of HIV‐1 by macrophages.
CCR8‐dependent activation of the RAS/MAPK pathway mediates anti‐apoptotic activity of I‐309/CCL1 and vMIP‐I
Authors: Louahed Jamila , Struyf Sofie , Demoulin Jean‐Baptiste , Parmentier Marc , Snick Jacques Van , Damme Jo Van , Renauld Jean‐Christophe 
Published: February 2003

AbstractWe have previously shown that the CC‐chemokine I‐309 (CCL1) protects mouse thymic lymphomas against corticoid‐induced apoptosis. Here, we analyzed the signal transduction pathways involved in this activity on BW5147 lymphoma. Inhibition of the CCL1 activity by pertussis toxin suggested the involvement of a G protein‐coupled chemokine receptor. The role of CCR8 was supported by the observation that vMIP‐I, another CCR8‐ligand identified from the genome of a T cell transforming herpes virus, shared CCL1 anti‐apoptotic activity. In addition to CCR8, BW5147 cells also expressed the CXCR4 receptor but its ligand, SDF‐1 (CXCL12) showed only a modest anti‐apoptotic activity. Other chemokines acting on CCR2, CCR4 and CCR5 failed to protect against apoptosis and to induce BW5147 chemotaxis, suggesting that these receptors were not functionally expressed. By contrast, both CCL1 and vMIP‐I up‐regulated ERK1/2 MAPK phosphorylation in BW5147 cells. Further analysis demonstrated thatCCL1 activates the MAPK pathway in CCR8‐transfected CHO cells. The implication of this pathway was confirmed by the fact that PD98059, an inhibitor of MEK kinases, as well as a dominant negative isoform of the M‐RAS protein specifically blocked the anti‐apoptotic activity of CCL1.
High antigen dose and activated dendritic cells enable Th cells to escape regulatory T cell‐mediated suppression in vitro
Authors: George Thaddeus C. , Bilsborough Janine , Viney Joanne L. , Norment Anne M. 
Published: February 2003

AbstractCD4+CD25+ regulatory T cells (Tregs) are critical for peripheral tolerance and prevention of autoimmunity. In vitro coculture studies have revealed that increased costimulation breaks Treg‐mediated suppression in response to anti‐CD3 or antigen. However, it was unclear whether loss of suppression arose from inactivation of Tregs or whether increased stimulationcaused Th cells to escape suppression. We have investigated conditions that allow or override Treg‐mediated suppression using DO11.10 TCR‐transgenic T cells and chicken ovalbumin peptide 323–339‐pulsed antigen‐presenting cells. Treg suppression of Th proliferation is broken with potent stimulation, using activated spleen cells and high antigen dose, but is intact at low antigen dose. Costimulation with CD80 and CD86 expressed on activated dendritic cells was essential for Th cell escape from suppression at a high antigen dose. Potently stimulated Tregs were functional since they reducedlevels of IL‐2, IFN‐γ, IL‐4 and Th CD25 expression in cocultures. Furthermore, Tregs responding to high antigen dose and activated splenocytes retained the ability to suppress proliferation, but only of Th cells responding to a sub‐optimal dose of independent antigen. Together, our results demonstrate that under conditions of strong antigen‐specific stimulation, Tregs remain functional, but Th cells escape Treg‐mediated suppression.
Characterization of H+,K+‐ATPase T cell epitopes in human autoimmune gastritis
Authors: Bergman Mathijs P. , Amedei Amedeo , D'Elios Mario M. , Azzurri Annalisa , Benagiano Marisa , Tamburini Carlo , van der Zee Ruurd , Vandenbroucke‐Grauls Christina M. , Appelmelk Ben J. , Prete Gianfranco Del 
Published: February 2003

AbstractHuman autoimmune gastritis (AIG) is an organ‐specific inflammatory disorder leading to gastric atrophy and pernicious anemia. Gastric H+,K+‐ATPase was identified as the autoantigen in both human disease and experimental murine AIG (EAIG). Studies of EAIG significantly contributed to current knowledge of human AIG, but to what extent EAIG mimics AIG is still debated, andthe autoantigenic epitopes in AIG are yet unknown. This study aimed to identify the H+,K+‐ATPase epitopes recognized by gastric T cell clones from AIG patients, to define their TCR Vβ usage and epitope‐induced cytokine response. Sixteen H+,K+‐ATPase‐reactive CD4+ gastric T cell clones of four AIG patients were tested for proliferation to overlapping 15‐mer peptides spanning the α and β chains of H+,K+‐ATPase. We identified 6 epitopes in the α chain and 5 in the β chain; TCR Vβ usage was not restricted. Four (36%) of the 11 H+,K+‐ATPase epitopes recognized in AIG were found to overlap with epitopes that are relevant in EAIG, including a previously described gastritogenic epitope. Gastric T cell recognition of the peptide epitopes resulted in secretion of Th1 cytokines. Our data suggest a striking similarity between human AIG and EAIG, at the epitope level, with regard to cytokinesecretion and likely also with regard to pathogenic mechanisms.
Adoptive transfer of an anti‐MART‐127–35‐specific CD8+ T cell clone leads to immunoselection of human melanoma antigen‐loss variants in SCID mice
Authors: Lozupone Francesco , Rivoltini Licia , Luciani Francesca , Venditti Massimo , Lugini Luana , Cova Agata , Squarcina Paola , Parmiani Giorgio , Belardelli Filippo , Fais Stefano 
Published: February 2003

AbstractThe identification of appropriate mouse models could be useful in carefully evaluating the actual role of the in vivo development of antigen‐loss variants during antigen‐specific vaccine therapy of human tumors. In this study we investigated the level of efficacy of a MART‐1/Melan‐A‐specific CD8+ T cell clone against its autologous melanoma in a severe combined immunodeficiency (SCID) mouse model, in which the tumor cells expressed in vivo heterogeneous and suboptimal levels of MART‐1. The subcutaneous co‐injection of the MART‐1/Melan‐A‐reactive T cell clone A42 with MART‐1/Melan‐A+ autologous human melanoma cells into SCID mice caused a total inhibition of tumor growth. However, the systemic treatment with A42 clone lymphocytes resulted inonly 50–60% inhibition of tumor growth, although the T cell clone targeted the tumors and the MART‐1+ cells virtually disappeared from the tumors. This study suggests that an immunotherapybased on the expansion of an antigen‐specific T cell clone generated in vitro is highly efficient in abolishing tumor growth when the target antigen is fully expressed, but leads to in vivoimmunoselection of antigen‐loss variants in the presence of suboptimal levels of antigen expression. Furthermore, this work shows that human tumors/SCID mouse models may be useful in evaluating thein vivo efficacy of adoptive immunotherapies.
The human TREM gene cluster at 6p21.1 encodes both activating and inhibitory single IgV domain receptors and includes NKp44
Authors: Allcock Richard J. N. , Barrow Alexander D. , Forbes Simon , Beck Stephan , Trowsdale John 
Published: February 2003

AbstractWe have characterized a cluster of single immunoglobulin variable (IgV) domain receptors centromeric of the major histocompatibility complex (MHC) on human chromosome 6. In addition to triggering receptor expressed on myeloid cells (TREM)‐1 and TREM2, the cluster contains NKp44, a triggering receptor whose expression is limited to NK cells. We identified three new related genes and two gene fragments within a cluster of ∼200 kb. Two of the three new genes lack charged residues in their transmembrane domain tails. Further, one of the genes contains two potential immunotyrosine inhibitory motifs in its cytoplasmic tail, suggesting that it delivers inhibitory signals. The human and mouse TREM clusters appear to have diverged such that there are unique sequences in each species. Finally, each gene in the TREM cluster was expressed in a different range of cell types.
Gender identity, ethnicity, acculturation, and drug use: Exploring differences among adolescents in the Southwest
Authors: Kulis Stephen , Marsiglia Flavio Francisco , Hurdle Donna 
Published: February 2003

AbstractThis article presents the findings of a survey completed by 1351 predominantly Mexican American middle school students residing in a large urban center in the U.S. Southwest. The study explores possible associations between drug use attitudes and behaviors and gender (biological sex), gender identity, ethnicity, and acculturation status. Based on the concepts of “machismo” and “marianismo” that have been used to describe Mexican populations, four dimensions of gender identity were measured: aggressive masculinity, assertive masculinity, affective femininity, and submissive femininity. In explaining a variety of indicators of drug use behaviors and anti‐drug norms, gender alone had limited explanatory power, while gender identity—often regardless of gender—was a better predictor. Aggressive masculinity was generally associated with higher risk of drug use, while the other three gender identity measures had selected protective effects. However, the impact of gender identity was strongly mediated by acculturation. Less acculturated Mexican American students reported lower aggressive masculinity scores than non‐Latinos. Less acculturated Mexican American girls reported both the lowest aggressive masculinity scores and the highest submissive femininity scores. More acculturated Mexican American students, along with the less acculturated Mexican American boys, did not appear to be following a polarized approach to gender identity (machismo and marianismo) as was expected. The findings suggest that some aspects of culturally prescribed gender roles can have a protective effect against drug use behaviors and attitudes, possibly for both girls and boys. © 2003 Wiley Periodicals, Inc.