A comparison of the beta-D-xyloside, odiparcil, to warfarin in a rat model of venous thrombosis

BACKGROUND

A significant need exists for new chronic oral anticoagulation therapies to replace warfarin. Previous studies have shown that beta-D-xylosides, which prime glycosaminoglycan (GAG) synthesis, have antithrombin and antithrombotic activity. In the following report, a new orally active beta-D-xyloside (odiparcil) has been characterized in a rat model of venous thrombosis and its efficacy and bleeding liability compared to warfarin. Additionally, studies were conducted to investigate odiparcil's ex vivo antithrombin and antiplatelet activity, and also to explore the potential utility of protamine sulfate as a neutralizing agent.

METHODS AND RESULTS

In vivo thrombosis studies were conducted in a rat inferior vena cava model, and bleeding studies in a rat tail transection model. Following oral dosing, warfarin and odiparcil produced dose-related suppression of thrombus formation. A therapeutically relevant dose of warfarin in this model (international normalized ratio; INR 3.0) achieved approximately 65% inhibition of thrombus formation. Warfarin caused dose-related significant increases in bleeding indices. Odiparcil antithrombotic activity was limited by its mechanism to a maximum suppression of thrombus formation of 65-70%, and did not prolong bleeding indices. Additionally, odiparcil-induced heparin cofactor II (HCII)-dependent antithrombin activity was shown to be a function of dermatan sulfate-like GAG production. Other than thrombin-related effects, no odiparcil effects on platelet function were observed. In antidote studies, it was demonstrated that odiparcil-induced antithrombotic activity could be partially neutralized by protamine sulfate.

CONCLUSIONS

These experiments suggest that an antithrombotic approach based upon xyloside induction of circulating GAGs may have the potential to approximate the efficacy of warfarin and yet with a reduced risk to hemostasis.

A randomized, double-blind, placebo-controlled, parallel-group study to assess the efficacy and safety of dual ACE/NEP inhibitor GW660511X in mild-to-moderate hypertensive patients

This multicentre, double-blind, placebo-controlled, parallel-group study determined the efficacy and safety of GW660511 200 mg, a dual inhibitor of angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP), in mild-to-moderate hypertensive patients (diastolic blood pressure (DBP), > or =90 and < or =109 mm Hg; systolic blood pressure (SBP), > or =150 and < or =180 mm Hg). After a single-blind 2- to 4-week placebo run-in period, 123 patients (aged 18-65 years) were randomized to either placebo (n=62) or to active treatment (n=61) consisting of two consecutive 3-day dose titration periods of GW660511X 50 mg once daily and 100 mg once daily followed by GW660511X 200 mg once daily for 14 days. GW660511X 200 mg significantly lowered (baseline and placebo-corrected) both trough mean cuff SBP (-8.00 mm Hg, P=0.002) and DBP (-5.38 mm Hg, P=0.003). GW660511X 200 mg significantly reduced placebo-corrected mean 24-h and daytime but not night-time ambulatory SBP and DBP. Over the 0-24 h time period following GW660511X 200 mg, there were significant (P<0.001) reductions in serum ACE activity and significant (P<0.001) increases in plasma ANP concentration compared with placebo in terms of both peak and trough effects. In addition, treatment with GW660511X 200 mg significantly (P=0.003) increased (placebo-corrected, 1.52-fold) urinary excretion of cGMP over the 0-24 h interval. Treatment-related adverse events were experienced by 43% of the patients administered GW660511X 200 mg and 44% of those dosed with placebo with headache the most commonly reported. In conclusion, GW660511X 200 mg is an effective antihypertensive in mild-to-moderate hypertensive patients with potent effects on biological markers of ACE and NEP inhibition.

A Gilbert's syndrome UGT1A1 variant confers susceptibility to tranilast-induced hyperbilirubinemia

Tranilast (N-(3'4'-demethoxycinnamoyl)-anthranilic acid (N-5)) is an investigational drug for the prevention of restenosis following percutaneous transluminal coronary revascularization. An increase in bilirubin levels was observed in 12% of patients upon administration of tranilast in a phase III clinical trial. To identify the potential genetic factors that may account for the drug-induced hyperbilirubinemia, we examined polymorphisms in the uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene in over a thousand patients. Our results suggested that the TA repeat polymorphism in UGT1A1, which predisposes some individuals to Gilbert's syndrome, predicted the susceptibility to tranilast-induced hyperbilirubinemia. The (TA)(7)/(TA)(7) genotype was present in 39% of the 127 hyperbilirubinemic patients vs 7% of the 909 controls (P=2 x 10(-22)). Rapid identification of genetic factors accounting for the observed adverse effect during the course of a double-blind clinical trial demonstrated the potential application of pharmacogenetics in the clinical development of safe and effective medicines.

Identification of a pharmacogenetic effect by linkage disequilibrium mapping

A practical limitation to the identification of genetic profiles predictive of drug-induced adverse events is the number of patients with the adverse event that can be tolerated before the drug is withdrawn. Whole genome screening for regions of linkage disequilibrium (LD) associated with a particular phenotype may provide the mechanism to rapidly discover specific and sensitive profiles. We have used data from a large phase III clinical trial of tranilast and typed 76 SNPs over a 2.7 megabase region flanking the uridine diphosphate glucuronosyltranserferase 1A1 gene. Three SNPs within one LD block showed strong association with tranilast-induced hyperbilirubinemia (P<10(-13)). Our data illustrated that a genome-wide LD scan of 100,000-200,000 SNPs is sufficient to identify a pharmacogenetic association with a drug-induced adverse event.

Beneficial effects of targeting CCR5 in allograft recipients

BACKGROUND

The chemokine receptor, CCR5, and its three high-affinity ligands, macrophage inflammatory protein- (MIP) 1alpha, MIP-1beta, and regulated on activation normal T cell expressed and secreted (RANTES), are expressed by infiltrating mononuclear cells during the rejection of clinical and experimental organ allografts, although the significance of these molecules in the pathogenesis of rejection has not been established.

METHODS

We studied intragraft events in four allograft models. First, we studied cardiac transplants in fully MHC-mismatched mice that were deficient in CCR5 or two of its ligands, MIP-1alpha or RANTES. Second we tested the effects of a neutralizing rat anti-mCCR5 monoclonal antibody on allograft survival. Third we assessed whether a subtherapeutic course of cyclosporine would potentiate enhance survival in CCR5-deficient recipients. Finally, we tested the effect of targeting CCR5 in a class II-mismatched model.

RESULTS

Whereas mice deficient in expression of MIP-1alpha or RANTES reject fully MHC-mismatched cardiac allografts normally, CCR5-/- mice, or CCR5+/+ mice treated with a neutralizing mAb to mCCR5, show enhanced allograft survival. MHC class II-disparate mismatched are permanently accepted in CCR5-/- but not CCR5+/+ recipients. Finally, the beneficial effects of targeting of CCR5 are markedly synergistic with the effects of cyclosporine, resulting in permanent engraftment without development of chronic rejection.

CONCLUSIONS

We conclude that CCR5 plays a key role in the mechanisms of host T cell and macrophage recruitment and allograft rejection, such that targeting of CCR5 clinically may be of therapeutic significance.

Conditional abatement of tissue fibrosis using nucleoside analogs to selectively corrupt DNA replication in transgenic fibroblasts

Progressive tissue fibrosis can compromise epithelial function resulting in organ failure. Appreciating evidence suggests that fibroblasts provide fibrogenic collagens during such injury. We further tested this notion by attempting to reduce the physiologic consequences of organ fibrosis through the selective killing of fibroblasts at sites of injury. Here, we report the conditional reduction of tissue fibroblasts using the coding sequence for herpesvirus thymidine kinase (DeltaTK) put under the control of a cell-specific promoter from the gene encoding fibroblast-specific protein 1 (FSP1). Transgenic fibroblasts from mice carrying FSP1.DeltaTK minigenes expressed thymidine kinase concordantly with native FSP1 and, compared to transgenic epithelium, were selectively susceptible to the lethal effects of nucleoside analogs either in culture or during experimental renal fibrosis. The numbers of fibroblasts in fibrogenic kidney tissue were reduced on exposure to nucleoside analogs as was the degree of type I collagen deposition and the extent of fibrosis. Fibroblast reduction following the stress of DNA chain termination highlights the important contribution of cell division during fibrogenesis. Our findings convey a proof of principle regarding the importance of FSP1(+) fibroblasts in fibrosis as well as providing a new approach to treating the relentless scarification of tissue.

Expression of apoptosis regulatory proteins in tubular epithelium stressed in culture or following acute renal failure

BACKGROUND

While tubular cell death is a characteristic of acute renal failure (ARF), the molecular mechanisms that modulate this cell death are unclear. Cell fate in acute renal failure hinges on a balance of survival and mortality factors in a changing environment. We further explored this issue by studying selected cell death-related proteins in experimental renal failure.

METHOD

The expression of genes that promote (c-myc, Bax, BclxS) or protect (Bcl2, BclxL) from cell death was studied by Northern blot, Western blot, and immunohistochemistry in murine kidneys following ARF induced by folic acid or in renal tubular epithelial cells (MCT) stressed in culture.

RESULTS

Renal mRNA levels encoding for c-myc and BclxL were elevated in ARF while the Bcl2/Bax ratio was decreased (Bcl2 decreased and Bax increased; P < 0.05). Protein levels of BclxL increased and Bcl2 protein decreased. Expression of tumor necrosis factor (TNF-alpha), a mediator of ARF, was also increased. Immunohistochemistry further demonstrated that BclxL was increased in some tubuli and absent in others, while Bcl2 expression decreased diffusely. Bax staining was also patchy among tubuli and individual cells in the tubular wall and lumen. As a relative deficit of survival factors is present in ARF, MCT epithelium were deprived of serum survival factors. This resulted in apoptosis, decreased Bcl2/Bax and BclxL/Bax ratios (P < 0.05) and sensitization to TNF-alpha-induced apoptosis (P < 0.05). The latter was prevented by enforced overexpression of BclxL (P < 0.01). TNF-alpha increased the mRNA levels encoding for c-myc and decreased BclxL expression. Neither MCT cells nor the kidney expressed BclxS.

CONCLUSIONS

A relative deficit of survival factors likely contributes to changes in levels of BclxL and Bax in ARF. These deficits predispose to cell death induced by persistent lethal factors such as TNF-alpha that is increased in ARF and a potential source of increased c-myc, a downstream facilitator of cell death. These findings implicate members of the Bcl2 family of proteins as regulators of tubular cell death in ARF and single them out as potential therapeutic targets.

Identification of a novel cis-acting element for fibroblast-specific transcription of the FSP1 gene

The FSP1 gene encodes a filament-binding S100 protein with paired EF hands that is specifically expressed in fibroblasts. This led us to look for cis-acting elements in the FSP1 promoter that might engage nuclear transcription factors unique to fibroblasts. The first exon of FSP1 is noncoding, therefore, a series of luciferase reporter minigenes were created containing varying lengths of 5'-flanking sequence, the first intron, and the noncoding region of the second exon. A position and promoter-dependent proximal element between -187 and -88 bp was shown to be active in fibroblasts but not in epithelium. Sequence in the first intron from +777 to +964 had an enhancing effect that was not cell type specific. Hsv TK reporter constructs driven by this promoter/intron cassette in transgenic mice were coexpressed appropriately with FSP1 in tissue fibroblasts. Gel mobility shift competitor assays identified a novel domain, FTS-1 (fibroblast transcription site-1; TTGAT from -177 to -173 bp), that specifically interacts with nuclear extracts from fibroblasts. The necessity of this binding site was confirmed by site-specific mutagenesis. Database searches also turned up putative FTS-1 sites in the early promoter regions of other fibroblast expressed proteins, including the alpha1 and alpha2(I), and alpha1(III) collagens and the alphaSM-actin gene. We hypothesize that the selective engagement of FTS-1 elements may contribute to the mesenchymal phenotype of fibroblasts and perhaps other dedifferentiated cells.

Susceptibility to anti-glomerular basement membrane disease and Goodpasture syndrome is linked to MHC class II genes and the emergence of T cell-mediated immunity in mice

We developed a new mouse model of human anti-glomerular basement membrane (GBM) disease to better characterize the genetic determinants of cell-mediated injury. While all major histocompatibility complex (MHC) haplotypes (H-2a, k, s, b, and d) immunized with alpha3 NC1 domains of type IV collagen produce anti-alpha3(IV) NC1 antibodies that cross-react with human Goodpasture [anti-GBM/anti-alpha3(IV) NC1] autoantibodies, only a few strains developed nephritis and lung hemorrhage associated with Goodpasture syndrome. Crescentic glomerulonephritis and lung hemorrhage were MHC-restricted in haplotypes H-2s, b, and d (A beta/A alpha region in H-2s) and associated with the emergence of an IL-12/Th1-like T cell phenotype. Lymphocytes or anti-alpha3(IV) NC1 antibodies from nephritogenic strains transfer disease to syngeneic recipients. However, passive transfer of isogenic alpha3(IV) NC1 antibodies into -/- T cell receptor-deficient mice failed to produce nephritis. Finally, nephritis and its associated IL-12/Th1-like T cell response attenuate in disease-susceptible mice tolerized orally to alpha3(IV) collagen before immunization. Our findings suggest collectively, as a hypothesis, that anti-GBM antibodies in mice only facilitate disease in MHC haplotypes capable of generating nephritogenic lymphocytes with special T cell repertoires.

Early role of Fsp1 in epithelial-mesenchymal transformation

A seamless plasticity exists among cells shifting between epithelial and mesenchymal phenotypes during early development and again later, in adult tissues, following wound repair or organ remodeling in response to injury. Fsp1, a gene encoding a fibroblast-specific protein associated with mesenchymal cell morphology and motility, is expressed during epithelial-mesenchymal transformations (EMT) in vivo. In the current study, we identified several cytokines that induce Fsp1 in cultured epithelial cells. A combination of these factors, however, was most efficacious at completing the process of EMT. The optimal combination identified were two of the cytokines classically associated with fibrosis, i.e., transforming growth factor-beta1 (TGF-beta1) and epidermal growth factor (EGF). To confirm that it was the induction of Fsp1 by these cytokines mediating EMT, we used antisense oligomers to block Fsp1 production and subsequently measured cell motility and markers of EMT phenotype. The antisense oligomers suppressed Fsp1 expresison and epithelial transformation; therefore, we conclude that the appearance of Fsp1 is an important early event in the pathway toward EMT.

Regulation of Fas and Fas ligand expression in cultured murine renal cells and in the kidney during endotoxemia

Fas ligand (FasL) and Fas belong to a recently described family of cytokines and receptors with similarities to tumor necrosis factor (TNF) and its receptors. Upon engagement by specific antibodies or by FasL, Fas transduces a signal for apoptosis in permissive cells. Although apoptosis occurs during renal development and following injury to mature cells, the factors responsible for programmed renal cell death are uncertain. We have studied Fas expression by renal cells in vitro and during endotoxemia in mice. Several renal cell types, including glomerular mesangial cells and tubular epithelial cells express a Fas transcript in culture. Lipopolysaccharides (LPS), interleukin-1 beta, interferon-gamma (IFN-gamma), and TNF-alpha increase the levels of Fas mRNA in cultured mesangial and tubular cells. TNF-alpha and LPS raise the level of Fas mRNA in a time- and dose-dependent manner with Fas receptor expression peaking after 72 h of exposure to LPS. Anti-Fas antibodies can induce the death of cultured mesangial cells. This cell death shows the characteristic changes of apoptosis, including DNA fragmentation and pyknotic changes of the nucleus. Increases in Fas by LPS, TNF-alpha, and IFN-gamma enhance the killing induced by the anti-Fas antibody. FasL is also expressed by cultured renal cells, and TNF-alpha treatment of mesangial cells increases its expression. In vivo, Fas mRNA is present at low level in normal kidney. LPS increases the levels of Fas mRNA and protein in kidney and produces evidence of apoptosis along nephrons. These data suggest that transcripts encoding natural FasL and Fas are induced by LPS and may play a role in endotoxemia-induced acute renal failure and organ dysfunction.

Enhanced expression of inducible nitric oxide synthase in murine macrophages and glomerular mesangial cells by elevated glucose levels: possible mediation via protein kinase C

Increased blood flow and vascular permeability of early diabetes have been associated with increased nitric oxide formation in diabetic rats, but the specific nitric oxide synthase responsible is unknown. We examined the modulation of the induction and activity of the inducible NOS isoform by high glucose concentration in a murine macrophage cell line, RAW 264.7, and murine glomerular mesangial cells. Culturing both cell types in high glucose concentration led to significant increases in nitrite production and the mRNA encoding iNOS upon stimulation with LPS plus interferon-gamma, as compared with normal glucose concentration. High glucose also modestly enhanced LPS/IFN-gamma-induced stimulation of the iNOS promoter in transient transfection experiments in mesangial cells. Protein kinase C activation led to enhanced mRNA expression of iNOS, and inhibitors of protein kinase C blocked nitrite accumulation in mesangial cells. These findings suggest that high glucose in combination with stimulation by LPS plus IFN-gamma enhances iNOS expression, and protein kinase C activation may be playing a role in this enhancement.

Cloning, genomic organization, and chromosomal localization of the Scya5 gene encoding the murine chemokine RANTES

RANTES is a member of the C-C subfamily of chemokines that functions as a proinflammatory chemoattractant for CD4+ T cells, monocytes, and eosinophils, and as an activator of basophils to release histamine. Like other members of the chemokine superfamily, RANTES has been implicated in a number of chronic inflammatory and autoimmune processes based on its function and its pattern of regulation. To begin study of the transcriptional regulation of RANTES, we have determined the genomic organization of the gene encoding the small inducible cytokine A5 (Scya5) and performed an initial analysis of its promoter elements. The Scya5 gene is located on chromosome 11. By Southern blot, it is a single-copy gene approximately 4.5 kb long composed of 3 exons. This chromosomal localization and pattern of genomic organization is conserved among the other C-C subfamily of chemokines. Primer extension analysis was used to identify the transcriptional initiation site that is located 27 bp downstream of a typical TATAA box. Sequence analysis of 1040 bp 5' to the start site of the Scya5 gene revealed a number of regulatory motifs that are also shared among the chemokine family including a PU.1 box, a NF-kappa B, and an IFN regulatory factor-1 response element. This region of genomic DNA was also cloned into a luciferase reporter vector. Transfection of this reporter construct into murine proximal tubular cells reveals that TNF-alpha can induce a transcriptional activation of the gene, as would be predicted from the rise in mRNA transcripts encoding RANTES in cells stimulated with TNF-alpha.

Cloning, genomic organization, and chromosomal localization of the Scya5 gene encoding the murine chemokine RANTES

RANTES is a member of the C-C subfamily of chemokines that functions as a proinflammatory chemoattractant for CD4+ T cells, monocytes, and eosinophils, and as an activator of basophils to release histamine. Like other members of the chemokine superfamily, RANTES has been implicated in a number of chronic inflammatory and autoimmune processes based on its function and its pattern of regulation. To begin study of the transcriptional regulation of RANTES, we have determined the genomic organization of the gene encoding the small inducible cytokine A5 (Scya5) and performed an initial analysis of its promoter elements. The Scya5 gene is located on chromosome 11. By Southern blot, it is a single-copy gene approximately 4.5 kb long composed of 3 exons. This chromosomal localization and pattern of genomic organization is conserved among the other C-C subfamily of chemokines. Primer extension analysis was used to identify the transcriptional initiation site that is located 27 bp downstream of a typical TATAA box. Sequence analysis of 1040 bp 5' to the start site of the Scya5 gene revealed a number of regulatory motifs that are also shared among the chemokine family including a PU.1 box, a NF-kappa B, and an IFN regulatory factor-1 response element. This region of genomic DNA was also cloned into a luciferase reporter vector. Transfection of this reporter construct into murine proximal tubular cells reveals that TNF-alpha can induce a transcriptional activation of the gene, as would be predicted from the rise in mRNA transcripts encoding RANTES in cells stimulated with TNF-alpha.

Epidermal growth factor receptor numbers in male and female mouse primary hepatocyte cultures

Epidermal growth factor receptors (EGF-R) were measured in adult male and female mouse primary hepatocyte cultures. On culture day 1, female hepatocytes had significantly fewer EGF-R than male hepatocytes (1.3 x 10(4) versus 6.2 x 10(5) per cell). Over the next three days, morphological changes consistent with progressive heptocyte dedifferentiation were observed. During this period, EGF-R numbers progressively increased in female cultures and decreased in male cultures, and by day 4 the sexual difference in EGF-R numbers was obliterated. These results indicate that a relationship exists between the degree of differentiation in hepatocyte cultures and the expression of EGF-R on the cell surface.

Murine sex-limited protein expression requires androgens and pituitary hormones

Levels of the murine sex-limited protein (Slp) were measured by an enzyme-linked immunosorbent assay in normal and hypophysectomized female CDF1 (Slpa) mice before and after a 15-day treatment with testosterone proprionate. Both groups of mice initially had undetectable levels of circulating Slp. After treatment, Slp serum levels of the nonhypophysectomized group had risen significantly above the Slp serum levels of the hypophysectomized group and the pretreatment controls. This indicates that the pituitary gland is necessary for the androgen-induced expression of Slp.