Chemoattraction of human T cells by IL-18

Cell locomotion is crucial to the induction of an effective immune response. We report here the chemoattraction of CD4(+) T cells by IL-18, a member of the IL-1 cytokine family. Recombinant IL-18 increased the proportion of T cells in polarized morphology in vitro and stimulated their subsequent invasion into collagen gels in an IL-18 concentration gradient-dependent manner. Immunofluorescent microscopy studies determined that the major cell type responding to IL-18 was IL-18R(+)CD4(+). Importantly, synovial CD4(+) T cells from patients with rheumatoid arthritis responded to IL-18, adopting polarized morphology and gel invasion without further activation ex vivo, indicating the physiologic relevance of our observations. Finally, injection of rIL-18 into the footpad of DBA/1 mice led to local accumulation of inflammatory cells. These data therefore demonstrate for the first time lymphocyte chemoattractant properties of a member of the IL-1 cytokine family and its relevance in inflammatory diseases.     

IL-18 enhances collagen-induced arthritis by recruiting neutrophils via TNF-alpha and leukotriene B4

IL-18 expression and functional activity have been associated with a range of autoimmune diseases. However, the precise mechanism by which IL-18 induces such pathology remains unclear. In this study we provide direct evidence that IL-18 activates neutrophils via TNF-alpha induction, which drives the production of leukotriene B(4) (LTB(4)), which in turn leads to neutrophil accumulation and subsequent local inflammation. rIL-18 administered i.p. resulted in the local synthesis of LTB(4) and a rapid influx of neutrophils into the peritoneal cavity, which could be effectively blocked by the LTB(4) synthesis inhibitor MK-886 (MK) or its receptor antagonist CP-105,696. IL-18-induced neutrophils recruitment and LTB(4) production could also be blocked by a neutralizing anti-TNF-alpha Ab. In addition, IL-18 failed to induce neutrophil accumulation in vivo in TNFRp55(-/-) mice. In an IL-18-dependent murine collagen-induced arthritis model, administration of MK significantly inhibited disease severity and reduced articular inflammation and joint destruction. Furthermore, MK-886-treated mice also displayed suppressed proinflammatory cytokine production in response to type II collagen in vitro. Finally, we showed that IL-18-activated human peripheral blood neutrophils produced significant amounts of LTB(4) that were effectively blocked by the MK. Together, these findings provide a novel mechanism whereby IL-18 can promote inflammatory diseases.     

Functional interaction between the c-Abl and Arg protein-tyrosine kinases in the oxidative stress response

The Abl family of mammalian nonreceptor tyrosine kinases consists of c-Abl and Arg. Recent work has shown that c-Abl and Arg are activated in the cellular response to oxidative stress. The present studies demonstrate that reactive oxygen species (ROS) induce the formation of c-Abl and Arg heterodimers. The results show that the c-Abl SH3 domain binds directly to a proline-rich site (amino acids 567-576) in the Arg C-terminal region. Formation of c-Abl.Arg heterodimers also involves direct binding of the Arg Src homology 3 domain to the C-terminal region of c-Abl. The results further demonstrate that the interaction between c-Abl and Arg involves c-Abl-mediated phosphorylation of Arg. The functional significance of the c-Abl-Arg interaction is supported by the demonstration that both c-Abl and Arg are required for ROS-induced apoptosis. These findings indicate that ROS induce c-Abl.Arg heterodimers and that both c-Abl and Arg are necessary as effectors in the apoptotic response to oxidative stress.     

Catalase is regulated by ubiquitination and proteosomal degradation. Role of the c-Abl and Arg tyrosine kinases

Catalase is a major effector in the defense of aerobic cells against oxidative stress. Recent studies have shown that catalase activity is stimulated by the c-Abl and Arg tyrosine kinases. Little, however, is otherwise known about the mechanisms responsible for catalase regulation. The present work demonstrates that mouse cells deficient in both c-Abl and Arg exhibit increased catalase stability. The results also show that catalase is subject to ubiquitination and degradation by the 26S proteosome. Significantly, ubiquitination of catalase is dependent on c-Abl- and Arg-mediated phosphorylation of catalase on both Y231 and Y386. In concert with these results, human 293 cells expressing catalase mutated at Y231 and Y386 exhibit attenuated levels of reactive oxygen species when exposed to hydrogen peroxide. These findings indicate that, in addition to stimulating catalase activity, c-Abl and Arg promote catalase degradation in the oxidative stress response.     

TIGR Gene Indices clustering tools (TGICL): a software system for fast clustering of large EST datasets

TGICL is a pipeline for analysis of large Expressed Sequence Tags (EST) and mRNA databases in which the sequences are first clustered based on pairwise sequence similarity, and then assembled by individual clusters (optionally with quality values) to produce longer, more complete consensus sequences. The system can run on multi-CPU architectures including SMP and PVM.     

Genetic Linkage Maps of the Guppy (Poecilia reticulata): Assignment of RAPD Markers to Multipoint Linkage Groups

Genetic linkage maps of the guppy (Poecilia reticulata) were constructed from independent crosses between the Tuxedo strain and a feral line (Wildtype). Segregation patterns of random amplified polymorphic DNA (RAPD) markers and phenotypic markers were investigated in F₂ offspring of Tuxedo × Wildtype and Wildtype × Tuxedo crosses. Among the 300 and 276 RAPD markers scored for the respective crosses, linkages were identified for 230 and 212, respectively. The Tuxedo × Wildtype and Wildtype × Tuxedo maps spanned 2100 Kosambi centiMorgans (cM_K) and 1900 cM_K, respectively, in 28 linkage groups. Average marker resolution was 10 cM_K. Genome length was estimated at 4410 cM_K and 4060 cM_K for the respective crosses, with an average physical distance of 166 kbp/cM_K. Several RAPD markers were closely linked to or mapped onto the loci for the sex-determining region (SdR), and the sex-linked black caudal-peduncle (Bcp) and red tail (Rdt) genes. These primary linkage maps are the initial step toward the construction of a composite high-density map to facilitate map-based cloning and marker-assisted selection of quantitative trait loci that are essential for the development of comprehensive breeding programs for the guppy.     

Large scale identification of human hepatocellular carcinoma-associated antigens by autoantibodies

Autoantibodies are often detected in hepatocellular carcinoma (HCC), and these responses may represent recognition of tumor Ags that are associated with transformation events. The identities of these Ags, however, are less well known. Using serological analysis of recombinant cDNA expression libraries (SEREX) from four HCC patients, we identified 55 independent cDNA sequences potentially encoding HCC tumor Ags. Of these genes, 15 are novel. Two such proteins, HCA587 and HCA661, were predominantly detected in testis, but not in other normal tissues, except for a weak expression in normal pancreas. In addition to HCC, these two Ags can be found in cancers of other histological types. Therefore, they can be categorized as cancer-testis (CT) Ags. Two other Ags (HCA519 and HCA90) were highly overexpressed in HCC and also expressed in cancer cell lines of lung, prostate, and pancreas, but not in the respective normal tissues. Four other Ags were identified to be expressed in particular types of cancer cell lines (HCA520 in an ovarian cancer cell line, HCA59 and HCA67 in a colon cancer cell line, HCA58 in colon and ovarian cancer cell lines), but not in the normal tissue counterpart(s). In addition, abundant expression of complement inactivation factors was found in HCC. These results indicate a broad range expression of autoantigens in HCC patients. Our findings open an avenue for the study of autoantigens in the transformation, metastasis, and immune evasion in HCC.     

T(H)1 and T(H)2 cells: a historical perspective

Demonstration of the existence and functions of T helper (T(H))1 and T(H)2 cells has had an enormous impact on basic and applied immunology. T(H)1 and T(H)2 cells have a crucial role in balancing the immune response. In this article, I attempt to trace the historical events contributing to the development of the T(H)1/T(H)2 concept, the current state of play, and briefly discuss the future prospects for the field.     

Expression of P450 aromatase and 17beta-hydroxysteroid dehydrogenase type 1 at fetal-maternal interface during tubal pregnancy

Steroidogenesis in the placenta has been studied widely, but little is known about steroid metabolism in ectopic pregnancy. Previous studies have indicated that trophoblast invasion and placentation in the uterus and the fallopian tube may be controlled by similar mechanisms. As far as 17β-estradiol (E₂) production is concerned, it has been well demonstrated that its biosynthesis in the placenta involves the action of P450 aromatase (P450arom) and 17β-hydroxysteroid dehydrogenase type 1 (17HSD1). The purpose of this study was to characterize the expression pattern of P450arom and 17HSD1 at the fetal–maternal interface, particularly in various trophoblast cells, in tubal pregnancy. Using in situ hybridization, P450arom mRNA was localized in syncytiotrophoblast (ST) cells, which are mainly responsible for hormone production during pregnancy, whereas no signal was detected in villous cytotrophoblast (VCT), column CT and extravillous CT (EVCT) cells. Immunohistochemical assays revealed that 17HSD1 is present in ST cells, a large portion of EVCT cells and 20% of column CT cells. On the other hand, no expression of 17HSD1 was detected in VCT cells. In addition, 17HSD1 was found in epithelial cells of the fallopian tube. Interestingly, the expression level of 17HSD1 in fallopian tube epithelium during tubal pregnancy was significantly higher than that during normal cycle. Our data provide the first evidence that normal and tubal pregnancies possess identical expression of P450arom and 17HSD1 in ST cells and therefore, similar E₂ production in the placenta. Further, the association of 17HSD1 with EVCT cells indicates that 17HSD1 perhaps play a role in trophoblast invasion. Finally, increased expression of 17HSD1 in epithelial cells of fallopian tube may lead to a local E₂ supply sufficient for the maintenance of tubal pregnancy.     

Applications of fluorescence correlation spectroscopy: measurement of size-mass relationship of native and denatured schizophyllan

Diffusion dynamics of a polysaccharide, schizophyllan has been studied by fluorescence correlation spectroscopy (FCS). Several different sizes of nondenatured and denatured schizophyllan have been labeled with rhodamine 6G in borate buffer. The length of the nondenatured schizophyllan was calculated from FCS data by using the Broersma's relationship for rod-like macromolecules. The obtained length was close to that obtained by atomic force microscopy (AFM) measurements. Denatured schizophyllan possesses a random coil conformation. Its hydrodynamic radius R(h) was measured by FCS. The relationship between R(h) and the molecular mass M has been studied and the scaling relationship R(h)--M(0.59) has been obtained, which is in agreement with the random coil model with excluded volume effect. The persistence length q(denat) of the denatured schizophyllan was determined by Hearst's relationship, to be equal to 5.16 +/- 0.75 (nm). The work demonstrates the utility of FCS method for dynamics investigations of biopolymers especially in diluted regime (concentration lower than 10(-8)M could be measured) where other techniques could not be used.