Fluvastatin in combination with rad significantly reduces graft vascular disease in rat cardiac allografts

Clinical recommendations for the use of everolimus in heart transplantation

Proliferation signal inhibitors (PSIs), everolimus (EVL), and sirolimus are a group of immunosuppressor agents indicated for the prevention of acute rejection in adult heart transplant recipients. Proliferation signal inhibitors have a mechanism of action with both immunosuppressive and antiproliferative effects, representing an especially interesting treatment option for the prevention and management of some specific conditions in heart transplant population, such as graft vasculopathy or malignancies. Proliferation signal inhibitors have been observed to work synergistically with calcineurin inhibitors (CNIs). Data from clinical trials and from the growing clinical experience show that when administered concomitantly with CNIs, PSIs allow significant dose reductions of the latter without loss of efficacy, a fact that has been associated with stabilization or significant improvement in renal function in patients with CNI-induced nephrotoxicity. The purpose of this article was to review the current knowledge of the role of PSIs in heart transplantation to provide recommendations for the proper use of EVL in cardiac transplant recipients, including indications, treatment regimens, monitoring, and management of the adverse events.

The use of proliferation signal inhibitors in the prevention and treatment of allograft vasculopathy in heart transplantation

Cardiac allograft vasculopathy (CAV) currently represents one of the most important causes of long-term morbidity and mortality in the heart transplant population. In well-designed studies with de novo patients, the use of proliferation signal inhibitors (PSIs; everolimus and sirolimus) has been shown to significantly prevent the intimal growth of graft coronary arteries in comparison to other immunosuppressive regimens, reducing the incidence of vasculopathy at 12 and 24 months. In addition, conversion to PSIs in maintenance patients with established CAV has also shown promising results in the reduction of the progression of the disease and its clinical consequences. For these reasons the interest shown by various transplantation units in the potential role of PSIs in this field is growing. The aim of the present article is to review the information obtained to date on the use of PSIs in heart transplant recipients, both in the prevention and the treatment of CAV. The principal published recommendations on the introduction and appropriate management of these drugs in clinical practice are also collected, as well as certain recommendations given by the authors based on their experience.

Pitavastatin suppresses acute and chronic rejection in murine cardiac allografts

INTRODUCTION

HMG-CoA reductase inhibitors play several roles in the maintenance of organ transplants. We investigated the role of pitavastatin, a potent and newly developed HMG-CoA reductase inhibitor, in cardiac allograft rejection and mechanism of graft arterial disease (GAD) suppression.

METHODS

Balb/c mice hearts were transplanted into C3H/He mice (a full allomismatch combination) to assess acute rejection or C57BL/6 hearts into B6.C-H2(<bm12>)KhEg (a class II mismatch combination) to examine the extent of GAD. Pitavastatin was administered orally to mice everyday (3 mg/kg/day). To assess the effect in acute rejection, mixed lymphocyte reaction was performed and cytokine mRNA expression was examined with ribonuclease protection assay.

RESULTS

Pitavastatin significantly prolonged allograft survival. Lymphocyte proliferation was inhibited by pitavastatin, and RPA showed down-regulation of interleukin-6 in pitavastatin-treated cardiac allografts. Allografts in the pitavastatin-treated group after 8 weeks showed less GAD compared with the control group. In vitro, pitavastatin suppressed the smooth muscle cell proliferation in response to activated T cells and inhibited extracellular signal-regulated kinase 1/2 activation.

CONCLUSION

Pitavastatin could be effective in the suppression of acute rejection and GAD development in cardiac transplantation.

Inhibition of Chemokine Receptor CCR2 and CCR5 Expression Contributes to Simvastatin-induced Attenuation of Cardiac Allograft Vasculopathy

BACKGROUND

Accumulating evidence reveals that statins possess pleiotropic properties beyond cholesterol reduction, which may contribute to the attenuation of cardiac allograft vasculopathy (CAV). Recent in vitro data suggest that statins could down-regulate chemokine receptors. This study was designed to test the hypothesis that simvastatin ameliorates CAV development via the inhibition of chemokine receptor expression in an inbred rat model of cardiac transplantation.

METHODS

Animals were divided into four groups: isograft; control (cyclosporine [CsA] + vehicle); low-dose simvastatin (LSIM; CsA + 5 mg/kg simvastatin); and high-dose simvastatin (HSIM; CsA + 10 mg/kg simvastatin). Donor hearts from Fisher 344 rats were transplanted heterotopically into Lewis rat recipients. CsA was administered at 1.5 mg/kg/day for 2 weeks post-operatively. In addition, recipients were treated daily with simvastatin or vehicle for 8 weeks. Donor hearts were harvested for histopathologic and immunohistochemical examination. Intragraft concentration of chemokines and chemokine receptor expression were analyzed using enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction, respectively.

RESULTS

Both low and high doses of simvastatin significantly decreased the CAV score; inhibited recruitment of T lymphocytes and macrophages; reduced levels of intragraft MCP-1 (monocyte chemoattractant protein-1), RANTES (regulated on activation, normal T-cell expressed and secreted) protein and IP-10 (interferon-inducible protein-10); and down-regulated expression of chemokine receptors CCR2 and CCR5. CXCR3 expression was not affected by simvastatin treatment.

CONCLUSIONS

Our results demonstrate that simvastatin may attenuate CAV development, possibly through retarding intragraft chemokine accumulation and chemokine receptor expression.

Recommendations for the use of everolimus (Certican) in heart transplantation: results from the second German-Austrian Certican Consensus Conference

Everolimus (Certican; Novartis Pharma AG, Basel, Switzerland) represents the latest generation of proliferation signal inhibitors (PSIs). Everolimus is indicated for use as an immunosuppressive drug in renal and heart transplantation. This report reflects the recommendations of the second German-Austrian Certican Consensus Conference, held in January 2006, for the clinical use of everolimus.

Synergistic suppression of rat neointimal hyperplasia by rapamycin and imatinib mesylate: implications for the prevention of accelerated arteriosclerosis

BACKGROUND

Accelerated arteriosclerosis remains a major limitation to therapeutic interventions such as angioplasty, stent deployment, and solid organ transplantation. Rapamycin, a powerful new immunosuppressant set to replace calcineurin inhibitors in the transplant setting, and imatinib mesylate, a receptor tyrosine kinase inhibitor, are both angioprotective. Here, we explored the pharmacological and therapeutic interactions of these two agents in a rat model of neointimal hyperplasia.

METHODS

Wistar rats, subjected to balloon catheter-induced aortic injury, received daily drug treatment until postoperative day 14 and were subsequently sacrificed or followed up to day 40 without further treatment. Development of neointimal lesions was assessed histologically and immunohistochemically. Steady-state rapamycin levels in whole blood were determined by HPLC-UV.

RESULTS

Rapamycin and imatinib, administered individually or in combination, produced no signs of overt toxicity. Continuous postoperative therapy with either rapamycin (0.5-1.5 mg/kg/day) or imatinib (2- 50 mg/kg/day) dose-dependently suppressed neointimal hyperplasia on day 14. Combined treatment (0.5 or 1 + 10 mg/kg/day, respectively) showed a trend towards synergistic action on day 14. Withdrawal of medication on day 14 nullified the early therapeutic effect of either agent by day 40. In contrast, early combination therapy (1 + 10 mg/kg/day) achieved long-term suppression of neointimal hyperplasia by approximately 81%. Notably, coadministration of imatinib appeared to reduce exposure to rapamycin, although this finding did not reach statistical significance.

CONCLUSIONS

Short-term combination therapy with rapamycin and imatinib is well tolerated and produces synergistic, sustained suppression of neointimal hyperplasia in rats. Subject to clinical evaluation, this new drug regimen may afford definitive prophylaxis against accelerated arteriosclerosis.

Occult pretransplantation systemic inflammation and posttransplantation vascular changes in a primate arterial allograft model

BACKGROUND

Occult systemic inflammation, as manifested by increased levels of C-reactive protein (CRP), identify patients at increased risk for renal allograft rejection. The mechanisms linking occult systemic inflammation to these adverse outcomes remain unclear. The purpose of this study was to examine the anatomic and physiologic effects of occult pretransplantation systemic inflammation on posttransplantation allograft outcome in a nonhuman primate model.

METHODS

Seventy-one healthy male Rhesus macaques were stratified into quartiles based on serum CRP. Five high quartile and six low quartile animals underwent common iliac artery transplantation from male donors. Duplex ultrasound measured graft flow at 3 weeks postoperatively; luminal narrowing was assessed by graft/femoral peak systolic velocity ratio. At 6 weeks, the grafts were harvested and morphometry studies were performed. Vessel wall changes were assessed by measuring the intimal medial area.

RESULTS

The allografts placed in high CRP quartile animals had more luminal narrowing by 3 weeks than those placed in low quartile animals, as evidenced by a higher mean graft/femoral peak systolic velocity ratio (1.6 vs. 0.90, P=0.006). Morphometry studies after graft harvest showed increased vessel wall area in the high quartile group versus the low quartile group (1.39 mm vs. 1.03 mm, P=0.018).

CONCLUSIONS

Occult pretransplantation systemic inflammation is associated with increased intimal thickening and stenosis after arterial allograft transplantation in a primate model. Additional studies are needed to confirm these results and to further investigate potential mechanisms linking pretransplantation systemic inflammation to adverse outcomes after transplantation.

Long-Term Treatment With a Specific Rho-Kinase Inhibitor Suppresses Cardiac Allograft Vasculopathy in Mice

Cardiac allograft vasculopathy (CAV) continues to be a major cause of late graft failure after cardiac transplantation. We have demonstrated that Rho-kinase, an effector of the small GTPase Rho, plays an important role in the pathogenesis of arteriosclerosis. In this study, we examined whether the Rho-kinase–mediated pathway is also involved in the pathogenesis of CAV using a specific Rho-kinase inhibitor and a dominant-negative Rho-kinase. Hearts from AKR mice were heterotopically transplanted to C3H/He (allograft) or AKR mice (isograft), and the effects of long-term oral treatment with fasudil, which is metabolized to a specific Rho-kinase inhibitor hydroxyfasudil, on CAV were examined at 2 and 4 weeks after the transplantation. Coronary remodeling in the allografts characterized by intimal thickening and perivascular fibrosis was dose-dependently suppressed in the fasudil group compared with the control group ( P <0.01, n=9 to 10). The inhibitory effects of hydroxyfasudil were mimicked by in vivo gene transfer of dominant-negative Rho-kinase ( P <0.05, n=4). Among the proinflammatory cytokines examined, those of macrophage migration inhibitory factor, interferon-γ, and transforming growth factor-β1 were upregulated in the control group and were dose-dependently inhibited in the fasudil group ( P <0.01, n=5). Vascular inflammation in the allografts, as evidenced by accumulation of inflammatory cells (macrophages and T cells), was also significantly inhibited in the fasudil group ( P <0.05, n=5 to 10). These results indicate that long-term treatment with fasudil suppresses CAV in mice, suggesting that Rho-kinase is an important therapeutic target for the prevention of CAV.

Pravastatin decreases cold ischemia--but not alloantigen-dependent transplant arteriosclerosis

BACKGROUND

Alloantigen mismatch and cold ischemia have been shown to induce transplant arteriosclerosis. Pravastatin (PR) decreases arteriosclerosis probably related to an immunosuppressive effect. Statins possess other nonimmune properties that may be beneficial to transplantation. We studied the effect of PR on cold ischemia and alloantigen-induced transplant arteriosclerosis in syngeneic (SYN) and allogeneic (ALLO) aortic transplantation models.

METHODS

Lewis rats served as the donors and recipients for SYN transplants and Brown Norway rats were donors for ALLO transplants. Aortic segments that had been preserved at 4 degrees C in Euro-Collins solution for 0 or 24 hours were transplanted to the infrarenal aorta of the recipients PR (10 mg/kg/d) was administered for 12 weeks prior to morphometric studies. Areas of intimal thickness and its relation to total vessel area were calculated. Lipid levels were measured at 12 weeks.

RESULTS

Aorta rings preserved for 24 hours showed marked intimal thickening compared to controls (SYN, CI 0 hours = 21.5% +/- 16.5% vs SYN, CI 24 hours = 50.7 +/- 9.5%, P <.05). PR significantly decreased thickening (SYN, CI 24 hours + PR = 41.7 +/- 12.2 (P <.05) vs SYN, CI 0 hours on SYN, CI 24 hours). There was a nonsignificant decrease in thickening among ALLO transplants treated with PR (ALLO = 31.4 +/- 15.9 vs ALLO + PR = 23.8 +/- 18.8; P >.05). PR had no effect on lipid levels. PR decreases cold ischemia induced transplant arteriosclerosis in this syngeneic aortic transplant model, but does not affect an alloantigen-mediated process. The beneficial effect of PR is not related to its lipid-lowering properties but probably to a nonimmune effect.

Delayed graft function and cast nephropathy associated with tacrolimus plus rapamycin use

Delayed graft function (DGF) occurs in 15 to 25% (range, 10 to 62%) of cadaveric kidney transplant recipients and up to 9% of living donor recipients. In addition to donor, recipient, and procedural factors, the choice of immunosuppression may influence the development of DGF. The impact of immunosuppression on DGF was studied. The frequency of DGF was evaluated in first cadaveric or living donor kidney allograft recipients (n = 144) transplanted at the University of Washington from November 1999 through September 1, 2001. Donor, recipient, and procedural factors, as well as biopsy results, were compared between patients who developed DGF and those who did not. DGF was more common in patients treated with rapamycin than without (25% versus 8.9%, P = 0.02) and positively correlated with rapamycin dose (P = 0.008). In those developing DGF, the duration of posttransplant dialysis increased with donor age (P = 0.003) but decreased with mycophenolate mofetil use (P = 0.01). All biopsies during episodes of DGF demonstrated changes of acute tubular injury. Of the patients with tubular injury, 12 treated with rapamycin and tacrolimus developed intratubular cast formation indistinguishable from myeloma cast nephropathy. Histologic, immunohistochemical, and ultrastructural studies indicated that these casts were composed at least in part of degenerating renal tubular epithelial cells. These findings suggest that rapamycin therapy exerts increased toxicity on tubular epithelial cells and/or retards healing, leading to an increased incidence of DGF. Additionally, rapamycin treatment combined with a calcineurin inhibitor may lead to extensive tubular cell injury and death and a unique form of cast nephropathy.