bluuebunny/crossref_metadata_2025 huggingface dataset:
ATP release and effects in pancreas
Authors: Novak Ivana , Amstrup Jan , Henriksen Katrine L. , Hede Susanne E. , Sørensen Christiane E.
Published: May 2003

ATP and other nucleotides are released from various cells, but the pathway and physiological stimulus for ATP release are often unclear. The focus of our studies is the understanding of ATP release and signaling in rat exocrine pancreas. In acinar suspension mechanical stimulation, hypotonic shock and, most importantly, cholinergic stimulation released 5–20nM ATP into the medium, as monitored by luminescence of the luciferin/luciferase reaction. ATP release was visualized at the single acinus level as luciferin consumption detected by confocal laser scanning microscopy (CLSM). The estimated ATP concentrations were higher, about 10µM, around acinar cells after cholinergic stimulation. Fluorescence of quinacrine and MANT‐ATP indicated that some ATP is stored in secretory granules. Pancreatic acini have transcripts for P2X1, P2X4, P2Y2, and P2Y4 receptors, but measurements of Ca2+ signals in isolated acini using Fura‐2 and CLSM revealed that only about 15% of acini respond to extracellular ATP or UTP. Hence, in acini only a few P2 receptors are functional and the distribution seems heterogenous. In contrast, pancreatic ducts have transcripts for P2Y2, P2Y4, P2X4, and P2X7 receptors that consistently increase intracellular Ca2+. Patch‐clamp studies show that P2Y2/P2Y4 receptors inhibit K+ channels, and thus downregulate secretion. P2X4/P2X7 channels stimulate Na+/Ca2+ influx and may upregulate secretion by yet unknown mechanisms. Taken together, our studies show that pancreatic acini release ATP, primarily in response to cholinergic stimulation, and thus ATP may be a paracrine mediator between pancreatic acini and ducts. Drug Dev. Res. 59:128–135, 2003. © 2003 Wiley‐Liss, Inc.
Expression of multiple P2Y receptors by MDCK‐D1 cells: P2Y1 receptor cloning and signaling
Authors: Hughes Richard J. , Torres Brian , Zambon Alexander , Arthur David , Bohmann Christine , Rump L. Christian , Insel Paul A.
Published: May 2003

The Madin Darby canine kidney (MDCK) cell line, a well‐differentiated renal epithelial cell line, is a useful model to examine P2Y receptor signaling and response. Our studies with MDCK‐D1, a clonal isolate, demonstrate that these cells release ATP in response to mechanical stimulation and activation of certain G‐protein‐coupled receptors. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) studies document that MDCK cells express multiple P2Y receptors, including P2Y1, P2Y2, P2Y6, and P2Y11 receptors. We isolated cDNAs for several of the P2Y receptor genes and expressed these in cells, such as the 1321N1 astrocytoma cell line, that lack native P2Y receptor expression. We report here the molecular cloning of the MDCK P2Y1 receptor, heterologous expression in 1321N1 cells, and the ability of the heterologously expressed receptors to increase intracellular calcium and phosphoinositide hydrolysis. ADP, methylthioATP, and ADPβS are agonists with the greatest potency, while ATP and ATPγS show lower potency and efficacy, and benzoylbenzoylATP, UTP, and UDP lack efficacy at the cloned P2Y1 receptor. Several antagonists, including MRS2179, A3P5PS, suramin, and PPADS blocked response at the cloned P2Y1 receptors. With their ability to respond to ADP and ATP, P2Y1 receptors, along with other P2Y receptors expressed in MDCK cells, contribute to the response of these cells to ATP (or its breakdown product, ADP) released from the cells and to exogenously added nucleotides. Drug Dev. Res. 59:1–7, 2003. © 2003 Wiley‐Liss, Inc.
2,2′‐Nitrophenylisatogen potentiates P2X1 receptor mediated vascular contraction and blood pressure elevation
Authors: Wihlborg Anna‐Karin , Slätt Johnny , Sun Xiangyang , Zhao Xiao‐He , Bergman Jan , Hedner Thomas , Erlinge David
Published: May 2003

The objective of this research was to examine the effects of chemical compounds with possible P2 receptor modulating effects and to characterize the potentiating effects of 2,2′‐nitrophenylisatogen (NPI) on P2X1 receptors in vitro and in vivo. Chemical compounds were tested in an in vitro pharmacological assay using vascular segments from the rat mesenteric artery stimulated by P2 receptor‐specific agonists. Contractions were expressed as a percentage of 60 mM K+‐induced contractions. Blood pressure was evaluated in pithed rats. NPI (30 μM) added 15 min before addition of the P2X1 receptor‐specific agonist αβ‐MeATP increased the maximum vasoconstriction from 23% to 49% (an increase of 113%). Furthermore, NPI prevented the desensitization of repeated αβ‐MeATP contractions. Related compounds were examined, and 2‐(3‐methoxy‐phenyl)‐1‐oxy‐indol‐3‐one (MPI) had similar effects as NPI, but several others lacked effect. NPI had no effect on ADPβS (P2Y1) or acetylcholine‐mediated vasodilatation, nor on UTP (P2Y2/4), UDP (P2Y6), or noradrenaline‐mediated contractions. In pithed rats, the blood pressure response to 50 nmol/kg‐infusion of αβ‐MeATP was increased from 50±6 to 63±5 mmHg (P<0.05), but had no effect on basal blood pressure or on the cardiovascular response to preganglionic nerve stimulation. In conclusion, NPI and MPI potentiates P2X1 receptor vascular contractions in vitro and (NPI) blood pressure effects in vivo. It is possible that the effect is mediated by an inhibition of P2X1 receptor desensitization. Drug Dev. Res. 59:82–87, 2003. © 2003 Wiley‐Liss, Inc.
Neurone‐to‐astrocyte communication by endogenous ATP in mixed culture of rat hippocampal neurones and astrocytes
Authors: Koizumi Schuichi , Fujishita Kayoko , Tsuda Makoto , Inoue Kazuhide
Published: May 2003

ATP is recognized as an important intercellular signaling molecule in the peripheral and CNS. Glutamate is reported to be an important neurone‐to‐glia mediator being released from neurones and astrocytes that activates astrocytic and neuronal Ca2+ responses, respectively. We demonstrate here that endogenous ATP could be an extracellular molecule for neurone‐to‐astrocyte communication in cocultured rat hippocampal neurones and astrocytes. Hippocampal neurones reveal synchronized Ca2+ oscillation, which was due to glutamatergic synaptic transmission. When analyzed in a fura‐2 method, a slight and very slow increase in intracellular Ca2+ concentration ([Ca2+]i) elevation was observed in some population of astrocytes. Such astrocytic [Ca2+]i elevation was dramatically inhibited by apyrase, though apyrase itself had no effect on neuronal Ca2+ oscillation. For a detail analysis, we investigated changes in [Ca2+]i in cells using a confocal microscopy. When cocultured hippocampal neurones and astrocytes were depolarized electronically in the presence of glutamate‐receptor antagonists, a transient elevation in [Ca2+]i was observed in neurones, which was followed by a slowly initiated and small rise in [Ca2+]i in astrocytes. Apyrase or P2 receptor antagonists almost abolished the [Ca2+]i rises in astrocytes, suggesting that depolarization‐evoked ATP release from neurones should produce astrocytic [Ca2+]i elevation via P2 receptors. Using a luciferin–luciferase bioluminescence assay, we found that neurones could release ATP in an activity‐dependent manner. These findings suggest that endogenous ATP should be an important intercellular mediator between neurones and astrocytes and that functions of these cells should be fine‐tuned by endogenously released ATP in situ. Drug Dev. Res. 59:88–94, 2003. © 2003 Wiley‐Liss, Inc.
Expression and function of A2B adenosine receptors in the U87MG tumor cells
Authors: Zeng Dewan , Maa Tenning , Wang Uerica , Feoktistov Igor , Biaggioni Italo , Belardinelli Luiz
Published: May 2003

Adenosine is released in increased amounts during hypoxic conditions and is a potential mediator of angiogenesis. The aims of this study were to determine the effect of adenosine on the release of angiogenic factors from the glioblastoma cell line U87MG and the subtypes of adenosine receptors that mediate this effect of adenosine. The adenosine analog NECA increased the release of IL‐8 to 160±13% of control at 24 h. As a positive control, cobalt (100 µM), a metal ion capable of inducing hypoxia‐like effects, increased the release of IL‐8 to 362±99% of control at 24 h. Using real‐time RT‐PCR, it was found that U87MG cells expressed mRNA transcripts of the A1, A2A, and A2B adenosine receptors. The functional presence of A2B adenosine receptors in this cell line was confirmed using pharmacological approaches. NECA stimulated cAMP accumulations with an EC50 value of 2.93±0.91 µM and this effect of NECA was inhibited by the selective A2B antagonist IPDX. In addition, NECA also caused an increase in the intracellular calcium concentration. Furthermore, cobalt increased the level of A2B mRNA to 187±16% and 259±37% of the vehicle control at 5 h and 24 h, respectively. In conclusion, these results suggest that A2B adenosine receptors are upregulated during hypoxia and may play an important role in mediating the effect of adenosine to increase the release of angiogenic factor IL‐8 by tumor cells. Drug Dev. Res. 58:405–411, 2003. © 2003 Wiley‐Liss, Inc.
P2Y receptors in brain astroglial cells: Identification of a gliotic P2Y receptor coupled to activation of a calcium‐independent ras/ERK1/2 pathway
Authors: Brambilla Roberta , Neary Joseph T. , Fumagalli Marta , Cottini Lorenzo , Cattabeni Flaminio , Schiller Paul R. , Abbracchio Maria P.
Published: May 2003

Exposure of rat cortical astrocytes to αβmethyleneATP results in features of reactive astrogliosis via activation of a novel P2Y receptor linked to cyclooxygenase‐2 (COX‐2) upregulation [Brambilla et al., J Neurochem 2002, 83:1285–1296]. Here, we have investigated the role of extracellular signal‐regulated kinases (ERK1/2) in αβmethyleneATP‐induced gliosis. Challenge of cultures with αβmethyleneATP resulted in early (5–10 min) and marked time‐dependent ERK1/2 activation. Pertussis toxin completely abolished this effect. ERK1/2 activation was also completely prevented by the selective ERK1/2 inhibitor PD 098059 and by the P2 antagonist pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulphonic acid. Because αβmethyleneATP induced no changes of intracellular calcium concentrations “Brambilla et al., 2002”, a role for phosphoinositide‐specific phospholipase C was ruled out. Conversely, D609, an inhibitor of phosphatidylcholine‐PLC (PC‐PLC) and PLD, fully abolished both αβmethyleneATP‐induced ERK1/2 activation and the associated gliosis. The Ras inhibitor FTI‐277 could also partially abolish ERK1/2 activation. Exposure of cells to αβmethyleneATP resulted in a time‐dependent increase in the DNA binding activity of AP‐1 and NF‐κB, two transcription factors known to be phosphorylated by ERKs and involved in COX‐2 gene transcription. We conclude that stimulation of a gliotic P2Y receptor leads to ERK1/2 activation via multiple parallel signaling pathways involving Gi/o‐dependent and calcium‐independent stimulation of PC‐PLC and/or PLD, and consequent activation of the Ras/Raf systems. We are currently trying to clone this receptor from these cells. Its molecular identification may lead to the development of a new class of antineurodegenerative agents, which, by counteracting excessive gliosis and COX‐2 upregulation, may prove useful in neurological disorders characterized by astrogliosis and inflammation. Drug Dev. Res. 59:161–170, 2003. © 2003 Wiley‐Liss, Inc.
CD40‐dependent and ‐independent activation of human tonsil B cells by CpG oligodeoxynucleotides
Authors: Gantner Florian , Hermann Patrice , Nakashima Kosuke , Matsukawa Satoko , Sakai Katsuya , Bacon Kevin B.
Published: May 2003

Immunostimulatory CpG oligodeoxynucleotide (CpG‐ODN) sequences are known to directly activate B cells. We investigated the expression of the CpG receptor, Toll‐like receptor 9 (TLR9), in humantonsil B cells, and determined functional responses following stimulation by a well‐characterized stimulatory CpG‐containing ODN sequence in the human immune system, ODN 2006. Tonsil B cells were found to express high amounts of TLR9 mRNA and protein, and exposure of B cells to CpG‐ODN but not to an inactive control ODN induced a concentration‐ and time‐dependent up‐regulation of the activation markers CD23, CD25, CD40, CD54, CD80, CD86 and HLA‐DR. However, significant induction of proliferation and the release of IL‐6, IL‐10, IgG and IgM were only noted when B cells were co‐incubated with irradiated CD40L‐expressing CHO cells. Endogenous IL‐10 was identified as a critical mediator of Ig production, whereas all activating effects were independent of IL‐6. Further, CpG‐ODN counteracted IgE production induced by IL‐4. Collectively, these findings suggest a synergistic role of the TLR9/CD40 system and a critical role for the immunomodulatory cytokine IL‐10 in the orchestration of CpG‐ODN‐induced responses in B lymphocytes.
Deficiency of CD26 results in a change of cytokine and immunoglobulin secretion after stimulation by pokeweed mitogen
Authors: Yan Shuling , Marguet Didier , Dobers Jörg , Reutter Werner , Fan Hua
Published: May 2003

To investigate the role of CD26 in the immune system, CD26 gene knockout mice with C57BL/6 background were used to study the immune response after stimulation with PWM. CD26–/– mice display an apparently normal phenotype. However, in their spleen lymphocyte population the percentage of CD4+ T cells is lower, and that of NK cells is higher, than that in CD26+/+ mice. In their peripheral blood, CD26–/– mice present a conspicuously decreased proportion of CD4+ NKT lymphocytes. In vitro, the PWM‐stimulated IL‐4 production was decreased by 60–80% in the supernatants of spleen lymphocytes of CD26–/– mice compared to that of CD26+/+ mice, whereas levels of IL‐10 and IFN‐γ were increased. No significant differences were found in the production of IL‐2, IL‐5, IL‐6 and IL‐13 between knockout and wild‐type mice. After immunization of mice with PWM in vivo, serum levels of total IgG, IgG1, IgG2a and IgE were markedly lower in CD26–/– mice than those in CD26+/+ mice, while no difference was found in IgM production. Further analysis of cytokine levels in vivo revealed a reduced IL‐4, IL‐2 and delayed IFN‐γ production in sera of CD26–/– mice upon immunization with PWM. These results indicate that CD26 contributes to the regulation of development, maturation and migration of CD4+ T, NK and NKT cells, cytokine secretion, T cell‐dependent antibody production and immunoglobulin isotype switching of B cells.
Unique T cell proliferation associated with PKCμ activation and impaired ZAP‐70 phosphorylation in recognition of overexpressed HLA/partially agonistic peptide complexes
Authors: Irie Atsushi , Chen Yu‐Zhen , Tsukamoto Hirotake , Jotsuka Toko , Masuda Masako , Nishimura Yasuharu
Published: May 2003

Altered peptide ligands (APL) induce T cell responses different from those induced by the original agonistic peptide. As shown for CD4+ T cells, partial agonists induce partial T cellactivation without proliferation because of lower affinities and higher off rates to TCR than those of agonists. To determine whether overexpression of partially agonistic TCR ligands on antigen‐presenting cells provides high‐avidity TCR ligands, we generated L cell transfectants expressing various numbers of HLA‐DR4 covalently linked with APL derived from a streptococcal peptide and observed responses of the cognate T cells. Some overexpressed HLA‐DR4/partially agonistic APL complexes induced T cell proliferation in a density‐dependent manner. However, tyrosine phosphorylation of zeta‐associated protein‐70 (ZAP‐70) and linker for activation of T cells and kinase activity of ZAP‐70 were not detectable. T cell proliferation stimulated with L cell transfectants was sensitive to thePKC inhibitor Gö6976, but to a lesser extent to Gö6983, suggesting the involvement of μ isotype of PKC (PKCμ). In vitro kinase assays revealed that PKCμ activity was up‐regulated only in T cells stimulated with L cell transfectants that induced T cell proliferation. Our data suggest the presence of a unique signaling pathway coupling TCR ligation with T cell proliferation associated with PKCμ activation and impaired ZAP‐70 activation.
Neutropenia alters lung cytokine production in mice and reduces their susceptibility to pulmonary cryptococcosis
Authors: Mednick Aron J. , Feldmesser Marta , Rivera Johanna , Casadevall Arturo
Published: May 2003

Neutrophils are generally considered to contribute to host defense through their potent microbicidal activity. However, there is accumulating evidence that neutrophils also have an important regulatory role in establishing the balance of Th1 and Th2 responses. This study investigated the role of neutrophils in defense against pulmonary Cryptococcus neoformans infection using neutrophil‐depleted BALB/c mice generated by administering mAb RB6–8C5. Neutropenic mice with pulmonary infection survived significantly longer than control mice, but there was no difference between groups infected intravenously. On day 1 of infection, neutropenic mice had significantly smaller fungal burdens than control mice. On day 7, neutropenic mice had significantly higher lung concentrations of IL‐10, TNF‐α, IL‐4, and IL‐12 than control mice, but there was no difference in IFN‐γ and MCP‐1 levels. Neutrophils influenced the outcome of cryptococcal infection in mice through mechanisms that did not involve a reduction in early fungal burden. The absence of neutrophils in lung tissue during the initial stages of infection appeared to alter the inflammatory response in a manner thatwas subsequently beneficial to the host. Higher levels of Th1‐ and Th2‐associated cytokines in neutropenic mice could have simultaneously promoted a strong cellular response while reducing inflammatory damage to the lung. Our results support the emerging concept that neutrophils play an important function in modulating the development of the immune response.
B cell apoptosis accelerates the onset of murine lupus
Authors: Trébéden‐Nègre Hélène , Weill Bernard , Fournier Catherine , Batteux Frédéric
Published: May 2003

To investigate whether the increased rate of lymphocyte apoptosis in systemic lupus erythematosus is involved in the onset of the disease, apoptotic or necrotic T or B lymphocytes from variouscell lines were injected intraperitoneally into pre‐autoimmune (NZB×NZW)F1 mice (BW) and non‐autoimmune BALB/c mice. The intraperitoneal production of cytokines and chemokines, the specific T cell response in the spleen, and the production of anti‐histone and anti‐dsDNA Ab were investigated. The onset of the disease was characterized by creatinine levels and evaluation of glomerular IgG deposits. In BW, but not in BALB/c mice, injection of apoptotic and not necrotic cells up‐regulated IL‐6 and IL‐10 in resident macrophages. Administration of apoptotic cells augmented the number of Th2 and B lymphocytes recruited in the peritoneal cavity. Only the treatment with apoptotic B cells promoted a systemic Th2 autoimmune response to H2 histones, associated with earlier occurrence of high levels of anti‐dsDNA autoantibodies, higher creatinine levels and more numerous glomerular IgG deposits than in BW controls not injected with apoptotic B cells. In genetically susceptible mice exposure to apoptotic of B, but not T, lymphocytes can elicit a Th2 response to H2 histones that helps B cell production of anti‐dsDNA Ab and finally triggers the onset of lupus.
Targeting of immunostimulatory DNA cures experimental visceral leishmaniasis through nitric oxide up‐regulation and T cell activation
Authors: Datta Neeta , Mukherjee Snigdha , Das Lopamudra , Das Pijush K.
Published: May 2003

Active targeting of CpG‐containing oligodeoxynucleotide (CpG‐ODN) to macrophages was studied by incorporating it in mannose‐coated liposomes, using visceral leishmaniasis as the model macrophage disease. Mannosylated liposomal CpG‐ODN was more effective than liposomal or free CpG‐ODN in inhibiting amastigote multiplication within macrophages. Moreover, in a 60‐day mouse model of visceralleishmaniasis, complete elimination of spleen parasite burden was achieved by mannosylated liposomal CpG‐ODN, compared to 62% and 81% parasite suppression by free and liposomal ODN, respectively, at a similar dose. Although in vitro exposure of CpG‐ODN did not induce marked nitric oxide (NO) generation by macrophages, considerably enhanced amount of NO was generated by macrophages ofCpG‐ODN‐treated animals. Their splenocytes secreted soluble factors required for the induction of NO generation, and the increased NO generation was paralleled by an increase in antileishmanial activity. Inducible NO generation was suppressed by treating splenocyte supernatants with anti‐IFN‐γ or anti‐IL‐12 antibodies, whereas in vivo administration of these anti‐cytokine Ab along with CpG‐ODN reversed protection against infection. CpG‐ODN treatment resulted in reduced levels of IL‐4, but increased levels of IFN‐γ, IL‐12 and inducible NO synthase in infected spleen cells, which was magnified by encapsulation in mannose‐coated liposomes. This targeted treatment was not only curative, but it also imparted resistance to reinfection. These results represent a general approach for intracellular targeting of CpG‐ODN, which effectively enhances its therapeutic potential in redirecting curative Th1 responses in Th2‐driven disorders.
Heat shock factor 1‐independent activation of dendritic cells by heat shock: implication for the uncoupling of heat‐mediated immunoregulation from the heat shock response
Authors: Zheng Hong , Benjamin Ivor J , Basu Sreyashi , Li Zihai
Published: May 2003

The induction of heat shock proteins by heat shock is classically defined as the heat shock response, which is involved in cytoprotection, inflammation and immune responses. Whereas the cytoprotective properties of heat shock have been well characterized, the immunomodulating roles of the heat shock response on the immune system are just emerging. In particular, it is not known whether immunomodulating functions of heat are mediated by the heat shock response. We addressed this question genetically, using a murine model that is unable to mount the heat shock response because of deletion of a major transcriptional factor, heat shock factor 1 (Hsf1). We focused on the roles of heat shock on modulating the functions of dendritic cells (DC) because of their important roles in both innate and adaptive immunity. We found that heat shock matures CD11c+ DC both in vitro and in vivo, phenotypically and functionally, in the absence of any exogenous inflammatory stimuli. Furthermore, heat‐shock‐mediated DC maturation is independent of Hsf1, as Hsf1–/– DC can be matured by heat shock equally well as wild‐type DC. Our novel findings demonstrate that heat shock, one of the most primitive biological responses, can modulate the immune response without the requirement for the transcriptional induction/repression of target genes mediated by Hsf1.
Selective absence of CD8+ TCRα β+ intestinal epithelial cells in transgenic mice expressing β2‐microglobulin‐associated ligands exclusively on thymic cortical epithelium
Authors: Capone Myriam , Lees Rosemary K. , Finke Daniela , Ernst Bettina , Meerwijk Joost P. M. Van , MacDonald H. Robson
Published: May 2003

Whereas interactions between the TCRα β and self MHC:peptide complexes are clearly required for positive selection of mature CD4+ and CD8+ T cells during intrathymic development, the role of self or foreign ligands in maintaining the peripheral T cell repertoire is still controversial. In this report we have utilized keratin 14‐β2‐microglobulin (K14‐β2m)‐transgenic mice expressing β2m‐associated ligands exclusively on thymic cortical epithelial cells to address the possible influence of TCR:ligand interactions in peripheral CD8+ T cellhomeostasis. Our data indicate that CD8+ T cells in peripheral lymphoid tissues are present in normal numbers in the absence of self MHC class I:peptide ligands. Surprisingly, however, steady state homeostasis of CD8+ T cells in the intestinal epithelium is severely affected by the absence of β2m‐associated ligands. Indeed TCRα β+ IEL subsets expressing CD8α β or CD8α α are both dramatically reduced in K14‐β2m mice, suggesting that the development, survival or expansion of CD8+ IEL depends upon interaction of the TCR with MHC class I:peptide or other β2m‐associated ligands elsewhere than on thymic cortical epithelium. Collectively, our data reveal an unexpected difference in the regulation of CD8+ T cell homeostasis by β2m‐associated ligands in the intestine as compared to peripheral lymphoid organs.
Rational design of new CpG oligonucleotides that combine B cell activation with high IFN‐α induction in plasmacytoid dendritic cells
Authors: Hartmann Gunther , Battiany Julia , Poeck Hendrik , Wagner Moritz , Kerkmann Miren , Lubenow Norbert , Rothenfusser Simon , Endres Stefan
Published: May 2003

Two different types of CpG motif‐containing oligonucleotides (CpG ODN) have been described: CpG‐A with high induction of IFN‐α in plasmacytoid dendritic cells; and CpG‐B with little induction of IFN‐α, but potent activation of B cells. In this study, we demonstrate that CpG‐A fail to activate B cells unless plasmacytoid dendritic cells are present. We identified a new set of CpG ODN sequences which induces high levels of IFN‐α in plasmacytoid dendritic cells but remains capable of directly activating B cells. These new CpG ODN (termed CpG‐C) are more potent stimulants of B cells than CpG‐B due to their ability of directly and indirectly (via plasmacytoid dendritic cells) activating B cells. The sequence of CpG‐C combines structural elements of both CpG‐A and CpG‐B. The most potent sequence, M362, contains a 5′‐end ‘TCGTCG‐motif’ and a ‘GTCGTT‐motif’, both of which are present in CpG‐B (ODN 2006); a palindromic sequence characteristic for CpG‐A (ODN 2216); but no poly G motif required for CpG‐A. In conclusion, we defined the first CpG‐containing sequences that potently activate both TLR9‐expressing immune cell subsets in humans, the plasmacytoid dendritic cell and the B cell. CpG‐C may allow for improved therapeutic immuno‐modulation in vivo.
Role of Toll‐like receptors in costimulating cytotoxic T cell responses
Authors: Schwarz Katrin , Storni Tazio , Manolova Vania , Didierlaurent Arnaud , Sirard Jean‐Claude , Röthlisberger Peter , Bachmann Martin F.
Published: May 2003

Stimulation of Toll‐like receptors (TLR) by pathogen‐derived compounds leads to activation of APC, facilitating the induction of protective immunity. This phenomenon is the basis of most adjuvant formulations currently in development. Here, we tested the ability of TLR2, 3, 4, 5, 7 and 9 signaling to enhance CTL responses upon vaccination with virus‐like particles. Stimulation of TLR2 and 4 failed to increase CTL responses, whereas ligands for TLR3, 5 and 7 exhibited moderate adjuvant function. In contrast, stimulation of TLR9 dramatically increased CTL responses, indicating that ligands for TLR9 are likely to be the most promising candidates for the development of novel adjuvant formulations for stimulating CTL responses.
The natural killer cell‐mediated killing of autologous dendritic cells is confined to a cell subset expressing CD94/NKG2A, but lacking inhibitory killer Ig‐like receptors
Authors: Chiesa Mariella Della , Vitale Massimo , Carlomagno Simona , Ferlazzo Guido , Moretta Lorenzo , Moretta Alessandro
Published: May 2003

The cognate NK–DC interaction in inflamed tissues results in NK cell activation and acquisition of cytotoxicity against immature DC (iDC). This may represent a mechanism of DC selection required for the control of downstream adaptive immune responses. Here we show that killing of monocyte‐derived iDC is confined to the NK cell subset that expresses CD94/NKG2A, but not killer Ig‐like receptors (KIR). Consistent with these data, the expression of HLA‐E (i.e. the cellular ligand of CD94/NKG2A) was down‐regulated in iDC. On the other hand, HLA‐B and HLA‐C down‐regulation in iDC was not sufficient to induce cytotoxicity in NK cells expressing KIR3DL1 or KIR2DL. Remarkably, CD94/NKG2A+KIR– NK cells were heterogeneous in their ability to kill iDC and an inverse correlation existed between their CD94/NKG2A surface density and the magnitude of their cytolytic activity. It is conceivable that the reduced CD94/NKG2A surface density enables these cells to efficiently sense the decrease of HLA‐E surface expression in iDC. Finally, most NK cells that lysed iDC did not kill mature DC that express higher amounts of HLA class I molecules (including HLA‐E)as compared with iDC. However, a small NK cell subset was capable of killing not only iDC but also mature DC.
XAS, ESR and Potentiometric Studies of Three DinuclearN,N′‐para‐Xylylenebis(tetraazamacrocycle)copper(II) Complexes − X‐ray Crystal Structure of [N,N′‐p‐Xylylenebis(cyclen)]copper(II)
Authors: Soibinet Mathieu , Déchamps‐Olivier Isabelle , Guillon Emmanuel , Barbier Jean‐Pierre , Aplincourt Michel , Chuburu Françoise , Le Baccon Michel , Handel Henri
Published: May 2003

Dicopper complexes withN,N′‐p‐xylylenebis(cyclam or cyclen) and with the heteroditopicN,N′‐p‐xylylenebis(cyclam‐cyclen) were synthesized. An X‐ray study of theN,N′‐p‐xylylenebis(cyclen)dicopper complex showed that the copper(II) ion is five‐coordinate with an H2O molecule in apical position. With this ligand, a polymeric chain was also obtained in the presence of KSCN. The terminal donor atoms of the bridging NCS−anion are coordinated in apical position to the square‐pyramidal copper(II) ion. Two alternating kinds of Cu2L4+moieties are present in the chain, the first with two N4S chromophores and the second with two N5chromophores. EXAFS and XANES results are in agreement with a five‐coordinate copper ion in the cyclen unit and a six‐coordinate copper ion in the cyclam unit. Thermodynamic constants were determined by potentiometry. The existence of dinuclear Cu2L4+species (ligand/metal ratio < 1) and mononuclear CuLHn(2+n)+species (ligand/metal ratio > 1) were confirmed by an ESR study at variable pH. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of [RuX(CO){η2‐C,N‐C6H4C(H)=NC6H4‐4‐NO2}(PPh3)2] (X = F, Cl, Br, I): Evidence of Non‐Conventional Ru−X Hydrogen Bonds Leading to Octahedral Coordination at the Halide Atom
Authors: Flower Kevin R. , Pritchard Robin G. , Warren John E.
Published: May 2003

Treatment of [RuCl(CO){η2‐C,N‐C6H4C(H)=NC6H4‐4‐NO2}(PPh3)2] (4‐Cl) with Ag[BF4] in acetone/CH2Cl2 gives the cationic complex [Ru{O=C(CH3)2}(CO){η2‐C,N‐C6H4C(H)=NC6H4‐4‐NO2}(PPh3)2][BF4] (not isolated), which then reacts with NaX (X = F, Br, I) to afford the new compounds [RuX(CO){η2‐C,N‐C6H4C(H)=NC6H4‐4‐NO2}(PPh3)2] (X = F, Br, I) (4‐F, 4‐Br, and 4‐I). All of the new compounds have been characterised by elemental analysis (C, H, and N), 1H, 13C{1H}, 31P{1H} NMR spectroscopy and IR spectroscopy. The IR data support the hypothesis that the fluoride ligand is the strongest halogen π‐donor to the metal centre. In addition, the compounds 4‐Br·1.5CHCl3, 4‐Cl·1.5CHCl3, 4‐F·2CDCl3, and 4‐I·1.5CHCl3 have been characterised by single‐crystal X‐ray diffraction studies; all show Ru−X···HCCl3 interactions with the Ru−F interaction being the strongest. In addition, there is evidence for the presence of competing RuX···ClCHCl2 (X = Cl, Br) interactions in compounds 4‐Br and 4‐Cl; these appear to be charge transfer in nature. The generality of these interactions has been probed using searches of the Cambridge Crystallographic Database and the data obtained suggests that these interactions have some, but limited, precedence. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Reactivity of Metallophosphide Anions with Electrophilic (Arene)tricarbonylmetal Complexes
Authors: Comte Virginie , Tranchier Jean Philippe , Rose‐Munch Françoise , Rose Eric , Perrey Danièle , Richard Philippe , Moïse Claude
Published: May 2003

Reaction of metallophosphide anions [(CO)xM′PPh2]− (M′ = Cr, Fe) with neutral tricarbonyl(η6‐fluoroarene)chromium and cationic (η6‐arene)tricarbonylmanganese complexes give rise to the formation of dinuclear complexes. These complexes are obtained either by substitution of the fluoride anion in the (arene)chromium complexes, or by addition to the ring in the (arene)manganese complexes. The X‐ray structure of one homodimetallic (Cr−Cr) complex was obtained and compared with its solution structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A Rigid Molecular Scaffold Affixing a (Polypyridine)ruthenium(II)‐ and a Nickel(II)‐Containing Complex: Spectroscopic Evidence for a Weakly Coupled Bichromophoric System
Authors: Pellegrin Yann , Berg Katja E. , Blondin Geneviève , Anxolabéhère‐Mallart Elodie , Leibl Winfried , Aukauloo Ally
Published: May 2003

The synthesis of DppztBuSalH2 (7), a rigid conjugated ditopic ligand containing a Dppz (dipyrido[3,2‐a:2′,3′‐c]phenazine) skeleton and a salophen‐type chelate, is reported. The complexes DppztBuSalNi (10), [Ru(bpy)2(DppztBuSalH2)]2+ (11), and [Ru(bpy)2(DppztBuSalNi)]2+ (12) have been prepared and characterised using common spectroscopic methods. Electrochemical, UV/Vis spectroelectrochemical and EPR studies were conducted on compounds 7, 10, 11, and 12. The singly reduced radical forms of 7 and 10 can be generated electrochemically, with the lone electron located on the low‐lying phenazine π*‐molecular orbital. Complexes 11 and 12 show several reduction waves and electronic and EPR data obtained for the electrogenerated singly reduced species show them to be closely related to the radical species 7·− and 10·−, respectively. The presence of nickel(II) in compound 12 renders the addition of the second electron on the phenazine group reversible. Both 11 and 12 show common features on the cathodic side of their cyclic voltammograms, with reversible one‐electron ruthenium‐centred oxidation. An additional low‐potential reversible‐oxidation wave is observed for 12, and this is ascribed to oxidation of the nickel(II) ion. The combined spectroscopic data best describe the ruthenium‐containing complexes as weakly coupled bichromophoric systems. Photophysical studies attest to the formation of a charge‐separated state for 11, whereas a strong quenching is detected for 12. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Coordination Modes in a (Thiosemicarbazone)copper(II)/Oxalato System − Structures of [{Cu(L)}2(ox)]·2H2O, [Cu(HL)(ox)(H2O)], [{Cu(HL)}2(ox)][Cu(ox)2]·2H2O and [{Cu(HL)}2(ox)](NO3)2 − Ferro‐ vs. Antiferromagnetic Behavior in Dinuclear Compounds
Authors: Gómez‐Saiz Patricia , García‐Tojal Javier , Maestro Miguel , Mahía José , Lezama Luis , Rojo Teófilo
Published: May 2003

Complexes with the formula [{Cu(L)}2(ox)]·2H2O (1), [Cu(HL)(ox)(H2O)] (2), [{Cu(HL)}2(ox)][Cu(ox)2]·2H2O (3) and [{Cu(HL)}2(ox)](NO3)2 (4) (HL = C7H8N4S, pyridine‐2‐carbaldehyde thiosemicarbazone) have been synthesized from Cu(L)(NO3) and oxalic acid while modulating the stoichiometries and the pH of the media. Single crystal X‐ray diffraction studies show that the structures of 1 and 4 contain dinuclear entities with distorted square pyramidal copper(II) ions. The dinuclear complexes are centrosymmetric in 1 and non‐centrosymmetric in 4. The metal centers are coordinated to the NNS atoms from the tridentate thiosemicarbazone ligand and to two oxygen atoms from the oxalato coligand. The latter ligand exhibits tetradentate behavior and acts as a bridge between the copper(II) ions. The thiosemicarbazone ligand is either present in the anionic (1) or the neutral (4) form. Compound 2 is composed of monomeric species containing square pyramidal copper(II) ions that are coordinated to the thiosemicarbazone ligand, one water molecule and one monodentate oxalato coligand. It is important to note that the oxalato is highly twisted in this complex, the O(1)−C(8)−C(9)−O(3) dihedral angle between the carboxylate groups is 79.9(4)°. Compound 3 contains both the dinuclear cationic species, analogous to those described for compound 4, and square planar (bisoxalato)copper(II) anions. Strong hydrogen bonds and π‐π stacking are present in these complexes. Structural and spectroscopic results suggest the presence of relevant ligand‐to‐metal charge transfers in these compounds. The EPR spectra of 1, 2 and 4 exhibit rhombic symmetry. Magnetic measurements on 1 and 4 show antiferromagnetic and ferromagnetic coupling, respectively. The susceptibility data were fitted to the Bleaney−Bowers equation for copper(II) dinuclear complexes. The J/k values obtained are −6.20 and +7.73 K for compounds 1 and 4, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Crystal Structures and Intercalation Reactions of Three‐Dimensional Coordination Polymers [M(H2O)2]2[Mo(CN)8]·4H2O (M = Co, Mn)
Authors: Willemin Stéphanie , Larionova Joulia , Clérac Rodolphe , Donnadieu Bruno , Henner Bernard , Le Goff Xavier Fréderic , Guérin Christian
Published: May 2003

Two coordination polymers [MII(H2O)2]2[MoIV(CN)8]·4H2O [MII = Co (1), Mn (2)] were prepared as monocrystals and structurally characterised. These compounds crystallise in the tetragonal systems I4/m (1) and I4/mcm (2) and form three‐dimensional networks containing channels occupied by two types of water molecules, i.e. coordinated to MII and crystallised ones. The dehydration of these materials occurs topochemically to give [MII(H2O)]2[MoIV(CN)8] compounds having an open metal coordination site on the MII ions that may be accessible to coordination by other species and serve as a reaction site. The intercalation of water, ammonia and amines has been studied. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structural, Magnetochemical and Electrochemical Studies of Dinuclear Complexes Containing the [VVO]2, [VIVO]2, CrIII2, MnIII2 and FeIII2 Cores of a Potentially Pentadentate Phenol‐Containing Ligand with (O,N,O,N,O)‐Donor Atoms
Authors: Mukherjee Soumen , Weyhermüller Thomas , Bothe Eberhard , Chaudhuri Phalguni
Published: May 2003

Dinuclear complexes [L2FeIII2] (1), [L2MnIII2] (2a), [L2MnIII2(THF)2] (2b), [L2CrIII2] (3), [L(VIVO)2(OCHMe2)] (4) and [L2(VVO)2] (5) with a pentadentate phenol‐containing ligand H3L (= C6H2(CH3)(OH){[C(CH3)3]2(OH)NCH}2) bearing the N2O3 donor atoms have been synthesized and the X‐ray structures of 1, 2b, 4 and 5 are reported. The compounds were characterized by IR, UV/Vis and Mössbauer spectroscopy, mass spectrometry, electrochemical and variable‐temperature (2−295 K) magnetic susceptibility measurements. Analysis of the susceptibility data demonstrates antiferromagnetic interactions between the metal centers establishing diamagnetic ground states for complexes 1−4. The electrochemical results suggest the generation of ligand‐centered oxidation processes attributable to the phenoxyl radicals, rather than the formation of unusually high oxidation states at the central metal centers. The ligand H3L has the potential to act in a multidentate fashion as evidenced by the X‐ray structures of 2b and 5. In compound 2b the central phenolate oxygen of the p‐cresol ring does not function as a bridging atom between two manganese centers, whereas in 5 the ligand is tetradentate with one noncoordinating nitrogen atom. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Preparation, Reactivity and Peptide Labelling Properties of (η6‐Arene)ruthenium(II) Complexes with Pendant Carboxylate Groups
Authors: Stodt Ralf , Gencaslan Susan , Müller Iris M. , Sheldrick William S.
Published: May 2003

(η6‐Arene)ruthenium(II) complexes of the type [{[η6‐C6H5(CH2)nCOOH]Ru(µ‐Cl)Cl}2] (2a, n = 1; 3, n = 3) with tethered carboxylate groups can be obtained by dehydrogenation of the appropriate cyclohexadiene with RuCl3·3H2O. Formation of a κO‐coordinated chelate in weakly acidic solution is observed by means of a 1H NMR titration for both [{η6‐C6H5(CH2)3COOH}Ru(aq)](OTf)2 (3a′) and [{η6‐C6H5(CH2)3COOH}Ru(phen)(aq)](OTf)2 (5′). Sandwich complexes of the type [{η6‐C6H5(CH2)3COOH}Ru(η6‐amino acid)](OTf)2 [amino acid = AcpheOH (6), ActyrOEt (7), ActrpOH (8)] can be prepared by treating [{η6‐C6H5(CH2)3COOH}Ru(acetone)3](OTf)2 with the appropriate aromatic bioligand in CF3COOH (6/8) or CH2Cl2 (7). Chemospecific η6‐labelling of the C‐terminal indole function is observed for the peptide HphetrpOH in the analogous complex 9. Quantitative formation of 8 can also be achieved in aqueous solution in the presence of a 3:1 excess of the {η6‐C6H5(CH2)3COOH}RuII fragment. This can also be employed for the N‐terminal labelling of amino acids and peptides in its sandwich complex [(η6‐C6Me6)Ru{η6‐C6H5(CH2)3COOH}](OTf)2 (10). Coupling reactions by the carbodiimide method with EDC afford water‐stable complexes of the type [(η6‐C6Me6)Ru{η6‐C6H5(CH2)3C(O)R}](OTf)2 [R = trpOMe (11), pheOMe (12), glyglyOEt (13)] in good yields. X‐ray structures of [(η6‐C6H5CH2COOC2H5)RuCl(phen)](OTf) (4b′) and 10 are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Kinetic and Equilibrium Studies of Reactions of N‐Heterocycles with Dimeric and Monomeric Oxorhenium(V) Complexes
Authors: Espenson James H. , Nabavizadeh S. Masoud
Published: May 2003

Equilibrium constants have been evaluated for the reaction {MeReO(edt)}2 + 2 L ⇄ 2 MeReO(edt)L, where edt is 1,2‐ethanedithiolate and L is any of 13 N‐donor heterocyclic ligands. The values of K range from 1.37(27)×10−2 for pyrimidine to 1.95(6)×106 for imidazole at 25 °C in chloroform. A successful correlation of logK with log (Ka) of HL+ was realized except in the case of the 2‐substituted ligands 2‐picoline and quinoline, where steric effects make K smaller than expected from the proton basicity of L. The kinetics of the same reactions were studied; the rate law for the reaction in the forward direction is given by −d[{MeReO(edt)}2]/dt = {ka + kb[L]}[L] × [{MeReO(edt)}2]. Except for 2‐picoline and quinoline, the major pathway is provided by the term that shows the quadratic dependence on [L]. Values of log (kb) also correlate with log K, and therefore necessarily with log (Ka).
NIR Dyes Based on [M(R,R′timdt)2] Metal‐Dithiolenes: Additivity of M, R, and R′ Contributions To Tune the NIR Absorption (M = Ni, Pd, Pt; R,R′timdt = Monoreduced Form of Disubstituted Imidazolidine‐2,4,5‐trithione)
Authors: Aragoni M. Carla , Arca Massimiliano , Cassano Tiziana , Denotti Carla , Devillanova Francesco A. , Frau Romina , Isaia Francesco , Lelj Francesco , Lippolis Vito , Nitti Luigi , Romaniello Pina , Tommasi Raffaele , Verani Gaetano
Published: May 2003

With the aim of preparing new dyes for Q‐switching and/or mode‐locking Nd‐based lasers, such as Nd:YLF and Nd:YAG (emission wavelengths 1053 and 1064 nm, respectively), the syntheses of about 30 new neutral dithiolenemetal complexes belonging to the class [M(R,R′timdt)2] have been carried out [M = Ni (4a−c; 4g−j), Pd (5a−j), Pt (6a−j); R,R′timdt = monoreduced form of disubstituted imidazolidine‐2,4,5‐trithione]. The examination of the effects induced on the intense NIR absorption by changing M, R, and R′ has allowed for the recognition of the additive contributions (Δλ) of the central metal ion and of the substituents to the λM,R,R′max position of the NIR absorption maximum, which is in the region of 1000 nm. The high Δλ values due to aromatic substituents have been elucidated by means of Hybrid‐DFT calculations performed on the model compound [Ni(H2timdt)(Ph,H‐timdt)]. Both the λM,R,R′max values and the molar extinction coefficients vary with the solvent. Complex 5f [M = Pd, R = p‐F‐C6H4, R′ = m,m,p‐(MeO)3‐C6H2] shows that it has been possible to exactly match the emission wavelength of the Nd:YLF and Nd:YAG lasers in chloroform and toluene, respectively (by choosing the appropriate combination of metal ion and substituents). The highest extinction coefficient ever observed for a metal‐dithiolene (120000 M−1·cm−1 at 1034 nm in toluene) is also reported for complex 6g [M = Pt, R = p‐F‐C6H4, R′ = naphthyl]. Time‐resolved absorption dynamics measurements on 5f have also been carried out by means of pump‐probe experiments, with a picosecond Nd:YAG Q‐switched and mode‐locked laser. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Co‐Ligand Involvement in Ground and Excited States of Electron‐Rich (Polypyridyl)PtII Complexes
Authors: Klein Axel , Slageren Joris van , Záliš Stanislav
Published: May 2003

The electronic absorption and luminescence properties of electron‐rich organometallic platinum(II) complexes with aromatic α‐diimine ligands [(α‐diimine)PtR2] (R = alkyl, alkynyl, Ph or Mes, Mes = 2,4,6‐trimethylphenyl) were examined. The crystal and molecular structures of [(bpy)PtMe2], [(tap)PtPh2] and [(tmphen)PtMes2] were determined from single‐crystal XRD and discussed in view of intermolecular interactions that influence the emission behaviour. The combination of theoretical calculations (DFT) and spectroscopic techniques (absorption and emission) revealed the character of electronic transitions and excited states. In particular they showed that the co‐ligand involvement in the frontier orbitals is small for R = Me, but large in case of R = alkynyl, Ph or Mes. Depending on the chelate ligand and its substitution pattern, the emission efficiencies of the complexes cover a wide range from strong emission in fluid solution at ambient temperature to very weak emission in rigid matrices (glasses) at low temperatures with no emission at ambient temperature. The emission lifetimes, determined at low temperature in solvent glasses, mainly depend on the chelate ligand and not on the co‐ligands. The emission quantum yields of the complexes in solution at room temperatures are much larger for R = Mes than for R = Ph or Me. The emission bands for the complexes with unsaturated co‐ligands show slight structuring at low temperatures in contrast to the alkyl‐substituted ones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Exchange Interactions at the Supramolecular Level − Synthesis, Crystal Structure, Magnetic Properties, and EPR Spectra of [Mn(MAC)(TCNQ)2] (MAC = Pentaaza Macrocyclic Ligand; TCNQ·− = Radical Anion of 7,7,8,8‐Tetracyano‐p‐quinodimethane)
Authors: Madalan Augustin M. , Voronkova Violeta , Galeev Ravil , Korobchenko Ludmila , Magull Jörg , Roesky Herbert W. , Andruh Marius
Published: May 2003

The reaction between [Mn(MAC)(H2O)2]Cl2·4H2O and LiTCNQ (MAC = 2,13‐dimethyl‐3,6,9,12,18‐pentaazabicyclo[12.3.1]octadeca‐1(18),2,12,14,16‐pentaene) affords a complex with the formula [Mn(MAC)(TCNQ)2] (1), whose crystal structure has been determined. Its structure consists of neutral mononuclear entities. The manganese(II) ion is heptacoordinated, with a pentagonal bipyramidal geometry. The apical positions are occupied by the TCNQ·− radicals, while the macrocyclic ligand is coordinated at the equatorial positions. The seven Mn−N distances range from 2.273(3) to 2.301(6) Å. The strong intermolecular π−π stacking interactions between the TCNQ radicals (3.2 Å) leads to weave‐like infinite chains, which propagate along the crystallographic c axis. The cryomagnetic investigation of 1 revealed a weak intermolecular antiferromagnetic coupling of the Mn2+ ions (J = −0.18 cm−1), which is mediated by the diamagnetic (TCNQ)22− pairs resulting from the stacking interactions in the crystal. The intermolecular exchange interaction between the Mn2+ ions was further confirmed by variable temperature EPR spectroscopic measurements [|J| = 0.15(5) cm−1], which have been carried out in both the X and Q bands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)