Showing papers by "Daniel Graf published in 2007"

Tumor Necrosis Factor-α Promotes Malignant Pleural Effusion

Abstract: Tumor necrosis factor (TNF)-alpha is present in the microenvironment of human tumors, including malignant pleural effusion (MPE). Although the cytokine is produced in the pleural cavity by both tumor and host cells, its effects on MPE formation are unknown. In these studies, we sought to determine the role of TNF-alpha in the pathogenesis of MPE and to assess the therapeutic effects of its neutralization in a preclinical model. For this, MPEs were generated in immunocompetent mice using intrapleural injection of mouse lung adenocarcinoma cells. The roles of tumor- and host-derived TNF-alpha were assessed using combined experimentation with TNF-alpha gene-deficient mice and in vivo TNF-alpha neutralization. To expand the scope of preclinical data, TNF-alpha and vascular endothelial growth factor (VEGF) expression were determined in human cancer cell lines and human MPE. In the MPE model, TNF-alpha of host and tumor origin was present. TNF-alpha neutralization significantly limited tumor dissemination, effusion formation, vascular hyperpermeability, TNF-alpha and VEGF expression, and angiogenesis, thereby improving survival. In contrast, these variables were not different between TNF-alpha gene-sufficient and TNF-alpha gene-deficient mice. In mouse cancer cells, TNF-alpha functioned via nuclear factor-kappaB- and neutral sphingomyelinase-dependent pathways to induce TNF-alpha and VEGF, respectively. These results were recapitulated in human cancer cells, and a correlation was detected between TNF-alpha and VEGF content of human MPE. We conclude that tumor-derived TNF-alpha is important in the development of MPE in mice, and provide preclinical evidence supporting the efficacy of TNF-alpha blockade against malignant pleural disease.

Characterization of B7S3 as a Novel Negative Regulator of T Cells

Abstract: T cell activation by APCs is regulated by B7-like costimulatory molecules In this study, we describe a new B7 superfamily member, B7S3, with two differentially spliced isoforms expressed in lymphoid and nonlymphoid tissues A soluble B7S3-Ig protein bound to professional APC constitutively as well as to activated but not naive T cells B7S3-Ig treatment greatly inhibited T cell proliferation and IL-2 production B7S3-Ig also reduced cytokine production by effector T cells Interestingly, although human genome appears to contain a single-copy B7S3 homolog, the mouse B7S3 gene has 10 relatives within a 2-Mb region constituting a B7S3 gene family This study identifies B7S3 as a novel negative regulator of T cells, and suggests evolutionarily divergent T cell regulation mechanisms in mammals

Generation and characterization of conditional alleles for bmp-2 and bmp-7

Abstract: INTRODUCTION: Bone Morphogenetic Proteins play multiple and important roles in embryonic development and homeostasis and tissue repair in adult tissues. In the adult or later stage embryos, systematic functional studies have so far been hampered by lack of mice that would allow conditional gene ablation, a prerequisite to overcome the early or complex phenotypes of straight null alleles. We present here the generation of conditional alleles for BMP-2 and BMP-7. Both molecules are highly conserved across mammalian species. Thus allele design is of prime importance, as particular care has to be taken not to create hypomorph alleles. For this reason, for targeting construct assembly we used Bacterial Homologous Recombination (BHR) on Bacterial Artificial Chromosomes (BAC), a technology that allows genome manipulation with base-pair precision and enabled us to take locus idiosyncrasies into consideration. For the generation of the conditional alleles we have adapted the classic two loxP-site strategy to BHR. Functional analysis in mice carrying these conditional alleles showed that they behave like null alleles following Cremediated recombination, making them suitable tools for in vivo studies.