No abstract

BMS-488043 is a small-molecule human immunodeficiency virus type 1 (HIV-1

Tumor necrosis factor 13 (TNF-P) (lymphotoxin) may play an important role in the immune response and pathologic inflammatory diseases. Insulitis is an important early step in the development of insulin-dependent diabetes mellitus. To understand better the role of TNF-fl in the regulation of infamation and type 1 diabetes, we produced transgenic mice in which the murine TNF-fi gene was regulated by the rat insulin H promoter. The transgene was expressed in the pancreas, kidney, and skin of transgenic mice. The expression of TNF-f8 in the pancreas of transgenic mice resulted in a leukocytic inflammatory infiltrate consisting primarily of B220+ IgM+ B cells and CD4+ and CD8+ T cells. The insulitis is reminiscent of the early stages of diabetes, though the mice did not progress to diabetes.The relationship between inflammation and autoimmunity is of considerable interest. Our goal was to determine whether the inappropriate expression of inflammatory cytokines within the islets of Langerhans would be sufficient to induce an inflammatory infiltrate and, if so, whether that inflammatory infiltrate was a sufficient condition to lead to insulindependent diabetes mellitus (IDDM). Such a model could prove useful in defining basic mechanisms of autoimmune pathogenesis and provide insight into prophylaxis and treatment. Although little is known about the contribution of tumor necrosis factor 1 (TNF-(3) to the inflammatory response in vivo, several in vitro studies implicate TNF-13 in processes that may contribute to inflammation and pathogenesis in general and in IDDM in particular. TNF-,B activates human endothelial cells in vitro to express a number of leukocyte adhesion molecules (1), and major histocompatibility complex class I and class II molecules (2) and also synergizes with interferon 'y (IFN-y) in inducing HLA class II gene expression in human islets (3). As such, TNF-,8 might be expected to enhance lymphocyte traffic and antigen presentation to T cells in those tissues in which the cytokine is present.IDDM is an autoimmune inflammatory disease that results in destruction of 3 cells in the pancreatic islets of Langerhans. The trigger for this inflammation, presumably due to reactivity with an as yet unidentified autoantigen, has not been defined. Susceptibility to diabetes in the human population, and in rodent models of the disease, is linked to the major histocompatibility complex. Recently, it was shown that diabetic individuals heterozygous for DR3.4 have a higher frequency of a particular TNF-,( polymorphism (a 10.5-kilobase Nco I restriction fragment length polymorphism) than nondiabetic DR3.4 individuals (4). This implicates additional genes that are linked to the major histocompatibility complex on chromosome 6, such as TNF, in diabetes.In the present study, we addressed two issues with respect to the biological activity of TNF-,B in vivo. We demonstrate that local production of TNF-,f is sufficient to initiate and maintain an islet-specific inflammatory response consisting primarily ofB and T lymph...

The tsetse thrombin inhibitor, a potent and specific low molecular mass (3,530 Da) anticoagulant peptide, was purified previously from salivary gland extracts of Glossina morsitans morsitans (Diptera: Glossinidae). A 303-bp coding sequence corresponding to the inhibitor has now been isolated from a tsetse salivary gland cDNA library by using degenerate oligonucleotide probes. The full-length cDNA contains a 26-bp untranslated segment at its 5 end, followed by a 63-bp sequence corresponding to a putative secretory signal peptide. A 96-bp segment codes for the mature tsetse thrombin inhibitor, whose predicted molecular weight matches that of the purified native protein. Based on its lack of homology to any previously described family of molecules, the tsetse thrombin inhibitor appears to represent a unique class of naturally occurring protease inhibitors. Recombinant tsetse thrombin inhibitor expressed in Escherichia coli and the chemically synthesized peptide are both substantially less active than the purified native protein, suggesting that posttranslational modification(s) may be necessary for optimal inhibitory activity. The tsetse thrombin inhibitor gene, which is present as a single copy in the tsetse genome, is expressed at high levels in salivary glands and midguts of adult tsetse flies, suggesting a possible role for the anticoagulant in both feeding and processing of the bloodmeal.The saliva of hematophagous invertebrates contains a diverse array of potent antithrombotic molecules, including anticoagulants, vasodilators, and inhibitors of platelet function (1-3). In the case of certain ''pool-feeding'' insects, particularly biting flies, these antihemostatic agents are thought to facilitate the rapid formation of a subcutaneous hematoma, from which the insect can suck blood efficiently. By inhibiting the critical steps through which the mammalian thrombotic response limits blood loss at the site of tissue damage, these insects are able to feed quickly, often requiring only seconds to complete their meal. It is during feeding that many of these arthropods also transmit important infectious pathogens, including protozoa, nematodes, and viruses, which are injected into or deposited on the skin as the insect probes for blood (4, 5).Tsetse flies (Diptera: Glossinidae) are the invertebrate hosts of African trypanosomes, protozoan parasites that cause sleeping sickness in humans and related diseases in cattle. These bloodfeeding insects have been known for decades to produce a potent salivary anticoagulant (6). First characterized as an ''antikinase'' (7), this activity was ultimately identified as an inhibitor of thrombin (8,9). Recently, the tsetse thrombin inhibitor (TTI), a potent (K i * ϭ 584 fM) 32-aa peptide, was purified to homogeneity from salivary gland extracts of Glossina morsitans morsitans (10). This inhibitor is highly specific for thrombin, showing no activity against a panel of 10 serine proteases, including components of the human coagulation͞thrombolytic cascade, as well as trypsin a...