Tumor necrosis factor-mediated interactions between inflammatory response and tumor vascular bed

Summary: Solid tumor therapy with chemotherapeutics greatly depends on the efficiency with which drugs are delivered to tumor cells. The typical characteristics of the tumor physiology promote but also appose accumulation of blood-borne agents. The leaky tumor vasculature allows easy passage of drugs. However, the disorganized vasculature causes heterogeneous blood flow, and together with the often-elevated interstitial fluid pressure, this state results in poor intratumoral drug levels and failure of treatment. Manipulation of the tumor vasculature could overcome these barriers and promote drug delivery. Targeting the vasculature has several advantages. The endothelial lining is readily accessible and the first to be encountered after systemic injection. Second, endothelial cells tend to be more stable than tumor cells and thus less likely to develop resistance to therapy. Third, targeting the tumor vasculature can have dual effects: (i) manipulation of the vasculature can enhance concomitant chemotherapy, and (ii) subsequent destruction of the vasculature can help to kill the tumor. In particular, tumor necrosis factor α is studied. Its action on solid tumors, both directly through tumor cell killing and destruction of the tumor vasculature and indirectly through manipulation of the tumor physiology, is complex. Understanding the mechanism of TNF and agents with comparable action on solid tumors is an important focus to further develop combination immunotherapy strategies.     

Heat shock preconditioning modulates proliferation and apoptosis after superficial injury in isolated guinea pig gastric mucosa via an eicosanoid and protein synthesis-dependent mechanism

AIM: In restitution after superficial injury of the gastric mucosa, the epithelial continuity is restored by cellular migration. We have shown that heat shock preconditioning inhibits restitution after superficial injury. This study investigates the effect of heat shock preconditioning on tissue proliferation and apoptosis. EXPERIMENTAL DESIGN: Paired guinea pig gastric mucosae were mounted and perfused in Ussing chambers (37 degrees C). After heat shock preconditioning (42 degrees C) (30 min) and normothermic recovery (37 degrees C) (150 min) or normothermic perfusion, a superficial injury was induced by luminal exposure to 1.25 mol/L NaCl (5 min) followed by a 3 h restitution. During perfusion, the mucosa was exposed to 30 micromol/L arachidonic acid (AA) to enhance heat shock response, to 50 micromol/L quercetin (Q) to inhibit the metabolism of arachidonic acid via lipoxygenases, to 50 micromol/L indomethacin (In) to inhibit the metabolism of arachidonic acid via cyclo-oxygenases, or to 150 micromol/L cycloheximide (CHX) to inhibit de novo protein synthesis. After the experiment the mucosa was prepared for immunohistochemical analysis of the expression of Mib-1 proliferation antigen and pro-apoptotic protein Bax. RESULTS: Heat shock decreased Mib-1/Bax ratio and this effect was maintained after superficial injury and exposure to Q, to AA+CHX or to In+CHX. Exposure to CHX, to AA, to In+Q, to In+AA, In+AA+Q or to In+AA+CHX, however, blocked the effect of heat shock preconditioning. The decreasing effect of heat shock preconditioning on Mib-1/Bax ratio could be reversed by exposure to AA+Q or to In. CONCLUSION: The heat-preconditioning-induced effects on the mucosa are reversible and sensitive to exogenous pharmacological modulation. Heat shock preconditioning inhibits proliferation of superficially injured isolated gastric mucosa by a mechanism involving eicosanoid pathways and de novo protein synthesis.     

cDNA arrays: gene expression profiles of Hodgkin's disease and anaplastic large cell lymphoma cell lines

cDNA arrays are a powerful tool for the identification of differentially expressed genes in malignant tumors. We used this technique to study the gene expression profiles of anaplastic large cell lymphoma (ALCL) and Hodgkin's disease (HD). Gene expression of 11 lymphoma cell lines was analyzed covering 1176 cDNA sequences. Comparing these data to the expression profiles of B- and T-lymphocytes, we identified 27 genes that were deregulated in all cell lines or in a particular entity. For the establishment of gene expression profiles the 27 genes were assigned to four groups composed of genes deregulated in (i) all lymphoma cell lines, (ii) ALCL and HD, (iii) only HD, and (iv) ALCL exclusively. Our results indicate that ALCL and HD share the differential expression of at least five genes. In addition, both entities are characterized by the differentially deregulated expression of four genes in HD and seven genes in ALCL. Because the expression profiling was performed on cell lines, further studies are needed to clarify the biological significance of the differentially expressed genes.     

Identification of Two Laminin-Binding Fimbriae, the Type 1 Fimbria of Salmonella enterica Serovar Typhimurium and the G Fimbria of Escherichia coli, as Plasminogen Receptors

Escherichia coli strains carrying recombinant plasmids encoding either the type 1 fimbria of Salmonella enterica serovar Typhimurium or the G fimbria of E. coli exhibited binding of human ¹²⁵I-Glu-plasminogen and enhanced the tissue-type plasminogen activator-catalyzed conversion of plasminogen to plasmin. Purified type 1 or G fimbriae similarly bound plasminogen and enhanced its activation. The binding of plasminogen did not involve the characteristic carbohydrate-binding property of the fimbriae but was inhibited at low concentrations by the lysine analog -aminocaproic acid. Because these fimbrial types bind to laminin of basement membranes (M. Kukkonen et al., Mol. Microbiol. 7:229–237, 1993; S. Saarela et al., Infect. Immun. 64:2857–2860, 1996), the results demonstrate a structural unity in the creation and targeting of bacterium-bound proteolytic plasmin activity to basement membranes.     

The functional state of follicular dendritic cells in severe combined immunodeficient (SCID) mice: Role of the lymphocytes

In the present study, we have investigated the capacity of follicular dendritic cells (FDC) to trap immune complexes (IC) in the splenic white pulp of severe combined immunodeficient (SCID) mice and the influence of lymphocyte transfer on FDC function. FDC are absent in the splenic white pulp of naive SCID mice as revealed by in vitro IC trapping assay. One week after transfer of syngeneic lymphocytes, functional FDC with complement receptors appeared in the primary follicles coincident with B cell segregation, and IC were trapped on those FDC in a complement-dependent manner. Next, we immunized the reconstituted SCID mouse to see whether another type of FDC could be induced in the secondary follicle. Antigenic stimulation induced FDC with an additional capacity to capture IC via FcR γ II. As seen in immunocompetent mice, this type of FDC was located only in the light zone of the secondary follicle. The newly generated FDC did not carry H-2 antigen of transferred lymphocytes from F₁ mice. In SCID mice, in which normally no functional FDC are detectable, the microenvironments of the splenic white pulp have a capacity to develop and differentiate normally after transfer of lymphocytes. Apparently, the generation of functional IC-trapping FDC causes the induction of complement receptor(s) and Fc receptor on meshwork cells, which requires the presence of the lymphocytes.     

Self-reinforced polylactide/polyglycolide 80/20 screws take more than 1(1/2) years to resorb in rabbit cranial bone

The aim of this study was to assess tissue reactions to bioabsorbable self-reinforced polylactide/polyglycolide (SR-PLGA) 80/20 miniscrews in rabbit cranial bone. One PLGA screw was implanted on one side and one titanium screw on the other side of the sagittal suture (n = 21). Three animals were sacrificed after 2, 4, 8, 16, 24, 54, and 72 weeks. In histological examination the numbers of macrophages, giant cells, active osteoblasts, and fibrous tissue layers were assessed and degradation of the bioabsorbable screws was evaluated. After 2 weeks, macrophages were seen near the heads of both screws. After 4 and 8 weeks, the bioabsorbable screws were surrounded by fibrous tissue. Osteoblastic activity and groups of several giant cells were seen. After 24 weeks, a significant change in the morphology of the PLGA screws had occurred. Osteoblastic activity and the amount of giant cells had decreased. After 1 year, some PLGA biomaterial was still present. PLGA screws had been replaced by adipose tissue, fibrous tissue, and "foamy macrophages" that had PLGA particles inside them. After 1(1/2) years, the amount of biomaterial remaining had decreased remarkably. The particles of biomaterial were inside foamy macrophages. SR-PLGA 80/20 screws are biocompatible and have no clinically manifested complications when used in the cranial bone of rabbits. No contraindications as regards their clinical use in craniofacial surgery was found when these screws were studied in the cranial bones of rabbits.     

L-selectin ligands in rat high endothelium: multivalent sialyl Lewis x glycans are high-affinity inhibitors of lymphocyte adhesion

Lymphocyte homing is initiated by their tethering to and rolling on the high endothelium and is followed by extravasation into the lymph nodes. We show here that glycosylated cell adhesion molecule-1 (GlyCAM-1), CD34, and sialyl Lewis x (sLex) are present on rat lymph node high endothelium analyzed by using monoclonal antibodies. α(1,3)fucosyltransferase VII (Fuc-TVII), the last enzyme involved in the synthesis of the sLex sequence is also expressed on the rat lymph node high endothelium. We have synthesized a family of sLex-decorated oligosaccharide structures and used them to inhibit lymphocyte binding to high endothelium in the Stamper-Woodruff assay. Monovalent sLex, branched di- and tetravalent sLex, as well as a linear tetravalent sLex significantly reduce lymphocyte binding to endothelium. The branched and linear forms of tetravalent sLex were clearly superior inhibitors of the L-selectin-dependent lymphocyte adhesion, with IC50 values in low nanomolar range. In contrast, the fucose-free analogs having the same charge and approximately the same size as the corresponding sLex glycans had no effect on lymphocyte binding and served as negative controls. Taken together, these data show the crucial importance of sLex in the endothelial ligands for L-selectin. Furthermore, we suggest that L-selectin acts as an oligomer on the lymphocyte surface as it binds multivalent sLex glycans.