An oral sphingosine 1-phosphate receptor 1 (S1P(1)) antagonist prodrug with efficacy in vivo: discovery, synthesis, and evaluation.

A prodrug approach to optimize the oral exposure of a series of sphingosine 1-phosphate receptor 1 (S1P(1)) antagonists for chronic efficacy studies led to the discovery of (S)-2-{[3'-(4-chloro-2,5-dimethylphenylsulfonylamino)-3,5-dimethylbiphenyl-4-carbonyl]methylamino}-4-dimethylaminobutyric acid methyl ester 14. Methyl ester prodrug 14 is hydrolyzed in vivo to the corresponding carboxylic acid 15, a potent and selective S1P(1) antagonist. Oral administration of the prodrug 14 induces sustained peripheral blood lymphocyte reduction in rats.

Effects of the novel protein kinase C inhibitor AEB071 (Sotrastaurin) on rat cardiac allograft survival using single agent treatment or combination therapy with cyclosporine, everolimus or FTY720.

NVP-AEB071 (AEB, sotrastaurin), an oral inhibitor of protein kinase C (PKC), effectively blocks T-cell activation. The immunosuppressive effects of oral AEB were demonstrated in a rat local graft versus host (GvH) reaction and rat cardiac transplantation models. T-cell activation was suppressed by 95% in blood from AEB-treated rats, with a positive correlation between T-cell inhibition and AEB blood concentration.

Experimental heart transplantation: effect of cyclosporine on expression and activity of metzincins.

Metzincins, such as matrix metalloproteases (MMP), and extracellular matrix (ECM) proteins are differentially regulated in inflammation. We hypothesised that metzincins are also dysregulated in experimental acute cardiac allograft rejection. We investigated the Dark Agouti-to-Lewis (DA-to-Lew) rat model of acute cardiac allograft rejection.

The chemokine receptor Cxcr3 is not essential for acute cardiac allograft rejection in mice and rats.

Chemokine receptors have gained attention as potential targets for novel therapeutic strategies. We investigated the mechanisms of allograft rejection in chemokine receptor Cxcr3-deficient mice using a model of acute heart allograft rejection in the strain combination BALB/c to C57BL/6. Allograft survival was minimally prolonged in Cxcr3-deficient mice compared to wild-type (wt) animals (8 vs.

A monoselective sphingosine-1-phosphate receptor-1 agonist prevents allograft rejection in a stringent rat heart transplantation model.

FTY720 is an immunomodulator with demonstrated efficacy in a phase II trial of relapsing multiple sclerosis. FTY720-phosphate, the active metabolite generated upon phosphorylation in vivo, acts as a potent agonist on four of the five known sphingosine-1-phosphate (S1P(1)) receptors. AUY954, an aminocarboxylate analog of FTY720, is a low nanomolar, monoselective agonist of the S1P(1) receptor.

Macrophage infiltration detected at MR imaging in rat kidney allografts: early marker of chronic rejection?

Purpose: To evaluate detection of iron-loaded macrophages at magnetic resonance (MR) imaging as a noninvasive means to monitor early signs of chronic allograft rejection in the life-supporting Fisher-to-Lewis rat kidney transplantation model.

Materials And Methods: Experiments followed the Swiss federal regulations of animal protection. Male Fisher (n = 37) and Lewis (n = 77) rats were used.

Evaluation of biomarker discovery approaches to detect protein biomarkers of acute renal allograft rejection.

Management of host responses to allografts by immunosuppressive therapy is the cornerstone of transplantation medicine, but it is still deficient in one important element: biomarkers that are readily accessible and predict the fate of the transplant early, specifically, and reliably. Using a Brown Norway (BN)-to-Lewis rat renal allograft model of kidney transplantation, this study aims at evaluating two proteomic approaches to discover biomarkers for acute rejection: SELDI-MS technology and 2D gel electrophoresis combined with mass spectrometry. Several novel potential serum biomarkers have been identified for follow up.

Transplantation-induced functional/morphological changes in rat aorta allografts differ from those in arteries of rat kidney allografts.

The functional/morphological changes observed in rat aorta allografts were compared with those seen in the arteries of rat kidney allografts. Untreated allografts (F344-to-LEW) were collected at various times post-transplantation (Tx). Vascular smooth muscle cell (SMC) constriction to phenylephrine (Phe) and endothelial cell (EC)-dependent relaxation to acetylcholine (Ach) were assessed.

Macrophage labeling by SPIO as an early marker of allograft chronic rejection in a rat model of kidney transplantation.

Anatomical and functional information (renography, perfusion) was obtained by MRI in a life-supporting transplantation model, in which Lewis rats received kidneys from Fisher 344 donors. Renography and perfusion analyses were carried out with Gd-DOTA and small particles of iron oxide (SPIO), respectively. Starting 12 weeks posttransplantation, images from grafts of untreated recipients exhibited distinctive signal attenuation in the cortex.

Mycophenolate sodium: tolerability and efficacy in transplantation in the rat.

Inhibition of inosine monophosphate dehydrogenase by mycophenolate compounds results in potent immunosuppression, as demonstrated by the efficacy of the marketed prodrug mycophenolate mofetil (MMF) in clinical allotransplantation. Side effects are well-known and include bone marrow depression and gastrointestinal intolerability. Mycophenolate sodium (MPS) is in clinical development as an enteric-coated formulation to alleviate this gastrointestinal adverse effect.

Transplantation-induced endothelial dysfunction as studied in rat aorta allografts.

Background: Clinical evidence indicates that vascular endothelial cell (EC) dysfunction occurs early after transplantation (Tx) and initiates chronic graft vasculopathy. This study explored this phenomenon in rat aorta Tx using the stringent Dark Agouti (DA)-to-Lewis (LEW) and the weak Fischer 344 (F344)-to-LEW strain combinations.

Methods: Donor abdominal aortae were orthotopically grafted into LEW rats.

Comparative efficacy of mycophenolate sodium (MPS) and mycophenolate mofetil (MMF) with and without cyclosporine in rat transplantation models.

Background: ERL is the enteric-coated sodium salt of mycophenolic acid, presently in clinical development. The drug substance mycophenolate sodium (MPS) was evaluated in rat transplantation models and compared with mycophenolate mofetil (MMF) for therapeutic window and synergy with cyclosporine (CsA).

Methods: Allotransplantation was performed in the Dark Agouti-to-Lewis (DA-to-Lewis; kidney, heart, and aorta) and Brown Norway-to-Lewis (BN-to-Lewis; kidney) strain combinations, and hamster heart xenotransplantation was performed in athymic and euthymic Lewis rats.

Tolerability profile of sodium mycophenolate (ERL080) and mycophenolate mofetil with and without cyclosporine (Neoral) in the rat.

Mycophenolic acid sodium salt (ERL080) is currently in Phase III clinical trials for the prophylaxis of kidney transplant rejection upon coadministration with Neoral (cyclosporin A microemulsion). To assess the relative side effect profile of ERL080 and MMF as drug substances in Lewis rats, a rat strain commonly used in transplantation experiments, a comparative 4-week tolerability study was performed. Escalating doses of ERL080 and MMF were administered orally at 10-30 mg/kg/d (i.

Endothelial dysfunction and denudation in rat aortic allografts.

Clinical evidence suggests that early endothelial cell (EC) dysfunction may predict the development of graft vascular disease. We wished to assess the early functional and morphological changes in the graft endothelium in a commonly used animal model of graft vascular disease, the rat aortic interposition allograft model. To assess graft EC function, regulation of vascular tone by ECs was monitored in aortic rings from grafts harvested at various times after transplantation (Tx).

Complete loss of functional smooth muscle cells precedes vascular remodeling in rat aorta allografts.

Background: The functional consequences of vascular remodeling in rat aorta allografts were studied at different times after transplantation (Tx).

Methods: At days 1, 3, 7, 14, 28, and 56 after Tx, rat aorta allografts (Dark Agouti [DA]-to-Lewis) were mounted as isolated organs, and their contractile properties tested with phenylephrine, KCl, or endothelin-1. Controls were native DA-aortae and DA-syngeneic grafts.

Side effects of brequinar and brequinar analogues, in combination with cyclosporine, in the rat.

Brequinar is an immunosuppressant with the potential to be combined with cyclosporine in synergistic combination therapy. The drug tends to accumulate when given daily per os, and pharmacokinetic interaction with cyclosporine appears to enhance toxicity. Analogues with similar immunosuppressive activity have been identified at Du Pont Merck Pharmaceutical Co.

Decreased lumen size after balloon injury despite inhibition of neointimal thickening and antivasospastic treatment.

Objective: Both calcium antagonists and angiotensin converting enzyme (ACE) inhibitors are known to diminish the development of intimal thickening after a balloon catheter lesion. It was previously shown that narrowing of carotid artery lumen induced by balloon injury was not influenced by treatment, even though the two ACE inhibitors used inhibited neointimal thickening. The aim of the present study was to include a calcium antagonist as well, in order to investigate whether vasospasm contributes to the persistence of lumen narrowing in ACE inhibitor treated rats after a balloon lesion.

Spirapril and cilazapril inhibit neointimal lesion development but cause no detectable inhibition of lumen narrowing after carotid artery balloon catheter injury in the rat.

Five groups of 12 rats were subject to balloon lesion of the left carotid artery and neointimal thickening was measured histologically 2 weeks after injury. Rat groups received either spirapril (3, 10 or 30 mg/kg/day, administered throughout the study in the food), cilazapril (10 mg/kg/day) or placebo. Spirapril caused a dose-dependent inhibition of the neointimal thickening of the rat carotid artery.

The effects of two synthetic glycoprotein IIb/IIIa antagonists, Ro 43-8857 and L-700,462, on platelet aggregation and bleeding in guinea-pigs and dogs: evidence that Ro 43-8857 is orally active.

In vitro platelet aggregation studies in whole blood were used to define the species-specificity profile of two synthetic GP-IIb/IIIa antagonists, Ro 43-8857 and L-700,462. Aggregation of rhesus monkey platelets was inhibited with a similar potency to human platelets, whereas both compounds were poor antagonists in mini-pig, rabbit or hamster blood. Compared to human platelets, Ro 43-8857 was 2-3-fold less active as an inhibitor of dog and guinea-pig platelet aggregation, whereas L-700,462 was, respectively, 4- and 14-fold less active in these species.

Similarities in the mechanism of action of two new vasodilator drugs: pinacidil and BRL 34915.

The present study compares the in vitro and in vivo activities of pinacidil with another new vasodilator drug, BRL 34915, claimed to act via the opening of K+ channels in vascular smooth muscle. In the rabbit aorta, BRL 34915 and pinacidil caused rightward shifts of the KCl concentration-response curve and noncompetitively antagonized angiotensin II contractions, yielding an IC50 of 5 and 10 microM, respectively. In 86Rb-loaded guinea pig portal veins, both BRL 34915 and pinacidil stimulated 86Rb+ efflux over the concentration range 0.