Mycophenolate mofetil impairs the integrity of colonic anastomosis

BACKGROUND: The aim of this experimental study was to investigate the effect of mycophenolate mofetil (MMF) during the three phases of colonic anastomosis healing and specifically to check the effect of MMF on the expression of transforming growth factor-beta1 (TGF-beta1), one of the most important growth factors contributing to mechanical stability of colonic anastomosis. MATERIALS AND METHODS: Sixty male Wistar rats underwent colonic resection and end-to-end anastomosis. The animals were divided into two groups, a study group given MMF 40 mg/kg, intraduodenally and a control group given vehicle. The rats were sacrificed at 3, 7, and 14 days (10 animals in each group). The anastomoses were tested by measuring bursting pressure and hydroxyproline content. Histological examination and immunohistochemical expression of TGF-beta1 also were assessed. RESULTS: The mean bursting pressure in the study group was significantly lower on day 3 and 7, but there was no statistical significance on day 14. The mean hydroxyproline content was lower in the study group on days 3, 7, and 14. Histology showed decreased number of macrophages and fibroblasts on days 3 and 7 but no difference on day 14. The expression of TGF-beta1 was significantly reduced in the study group, with the difference being more pronounced on days 3 and 7. CONCLUSION: MMF weakens the integrity of colonic anastomosis, and this effect is more significant during the inflammatory phase of healing. MMF has a negative effect on macrophages and TGF-beta1 expression, resulting in decreased collagen accumulation at the anastomosis.     

Mycophenolate mofetil impairs healing of left-sided colon anastomoses

INTRODUCTION: Inadequate healing and consequent leakage from bowel anastomoses are a significant cause of postoperative morbidity and mortality. Immunosuppressive drugs are known to disturb healing processes and to impair the mechanical stability of bowel anastomosis. Mycophenolate mofetil (MMF) is an immunosuppressive agent that selectively inhibits the proliferation of T and B lymphocytes and has been shown to be effective in preventing allograft rejection after organ transplantation. Adverse effects are few; however, nothing is known in regard to possible adverse effects of MMF administration on the healing of bowel anastomosis. The aim of the present study was to evaluate the effect of systemic MMF administration on the healing of colon anastomoses in rats. METHODS: Rats underwent laparotomy, division of the left colon, and sigmoidostomy. MMF (25 mg/kg) or vehicle was administered intraperitoneally in two groups (n=21 per group) 3 days before surgery and then once daily until euthanization (7 animals per group; 2, 4, and 6 days after surgery). Bursting pressure measurements, histologic evaluation, morphometric analysis, mucin and collagen staining, and BrdU immunohistochemistry of the anastomotic site were performed. Furthermore, matrix protein expression at the anastomotic site was determined by collagen I and fibronectin Western blots. RESULTS: Administration of MMF significantly decreased anastomotic bursting pressure postoperatively. Accordingly, histology, mucin staining, and BrdU immunohistochemistry and measurements of the colonic crypt depth showed more extended inflammation, a significantly lower proliferation rate, and a significantly thinned mucosal layer in the MMF-treated groups when compared to control animals, whereas matrix synthesis at the anastomotic site was not different. CONCLUSIONS: The administration of the immunosuppressive agent MMF significantly impairs healing and mechanical stability of colon anastomosis in rats during the early postoperative period. MMF act to disturb host reparative processes mainly by impairment of reparative colonic epithelium proliferation and less by a disturbance of matrix synthesis.     

Mycophenolate mofetil and cyclosporine as graft-versus-host disease prophylaxis after allogeneic blood stem cell transplantation

BACKGROUND: Mycophenolate mofetil (MMF) is an inhibitor of purine nucleotide de novo synthesis leading to impaired proliferation of activated lymphocytes. Studies in animals show a synergistic effect of MMF and cyclosporine (CsA) in preventing acute graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation. We performed a pilot study evaluating the feasibility of the combined application of MMF and CsA as GVHD prophylaxis after allogeneic blood stem cell transplantation. Toxicity and the bioavailability of MMF in this setting were investigated. METHODS: Fourteen patients who had received grafts from HLA-compatible siblings received 2 g of oral MMF from day 1 to 14 combined with intravenous CsA at 4 mg/kg starting at day-1. Plasma levels of mycophenolic acid (MPA) and its glucoronide were measured by high-performance liquid chromatography. Fifteen patients treated with a combination of CsA and methotrexate at the same institution were referred to as the control group. RESULTS: Trilineage engraftment was achieved in all study and control patients. Acute GVHD > or = grade II was observed in 46.5% and 60% of the study and control patients, respectively. No major differences in the rate of acute toxicities were detectable. The mean trough blood level of MPA in 10 patients was 0.28 microg/ml, and 5.7 microg/ml for MPA glucoronide. Reduced peak levels of MPA indicate a reduced absorption rate of MMF in the early posttransplant phase. CONCLUSIONS: The combined administration of MMF and CsA was shown to be feasible in patients after allogeneic blood stem cell transplantation. Because of the decreased bioavailability of MMF, dose-finding studies for an intravenous formulation are warranted.     

Mycophenolate mofetil decreases endothelial prostaglandin E2 in response to allogeneic T cells or cytokines

BACKGROUND: Prostaglandin E2 (PGE2) is a powerful endogenous immune suppressant and interferes with various T-cell functions. However, it is not known in detail whether immunosuppressive drugs influence the PGE2-driven immune response in transplant patients. Therefore, we investigated the effect of several immunosuppressive compounds, in particular the novel drug mycophenolate mofetil (MMF), on endothelial PGE2 release. METHODS: Endothelial cells (HUVEC) were activated by either allogeneic CD4+ or CD8+ T cells, or by the cytokines interleukin-1 or gamma-interferon. Using an enzyme-linked immunosorbent assay, we analyzed PGE2 release of the activated HWEC in the presence of MMF, cyclosporine, or tacrolimus. As verapamil and mibefradil also possess immunosuppressive properties, they were included in the study as well. RESULTS: Activation of HUVEC with interleukin-1 or T cells resulted in a drastic accumulation of PGE2 in the supernatant. Cyclosporine or tacrolimus had no effect on PGE2 release. However, Ca2+ channel blockers, when applied at higher dosages, caused a significant increase in PGE2. Interestingly, MMF strongly diminished the PGE2 level in the cell culture supernatant in a concentration-dependent manner. CONCLUSION: The results demonstrate an inhibitory effect of MMF on PGE2 production, which may lower the benefits of the PGE2-triggered immune response after organ transplantation.     

Mycophenolate mofetil and cyclosporine therapy in membranous nephropathy

Idiopathic membranous nephropathy (IMN) remains one of the most common causes of the nephrotic syndrome (NS) in adults. Although the natural history is extremely variable, approximately two thirds of the patients will have persistent high-grade proteinuria and/or develop renal failure over a decade of observation. On the other hand, the remaining third of patients will remit spontaneously and potentially toxic therapy should be avoided in this group. Our capacity to predict which patient will progress at an early stage of the disease has improved substantially in the past 10 years. We present the data from studies of cyclosporine (CSA) and mycophenolate mofetil (MMF) treatment of IMN with their level of evidence in support of efficacy. In addition, based on data related to predicting prognosis, we assign a risk for progression category to the trial patients at entry into these studies. The data are presented in this format so the reader will be able to better discern the risk benefit of treatment within each category and the rationale for our subsequent grade of recommendation for the use of these agents in IMN. CSA has been shown in randomized controlled trials in both the medium and high risk of progression categories of IMN patients to improve proteinuria and preserve renal function at least in the short term in up to two thirds of patients. Other studies suggest prolonged therapy beyond 6 months to 1 year may reduce the high relapse rate after CSA treatment supporting more long-term, continuous, or combination therapy in IMN treatment. The data in favor of MMF treatment of this disease is much weaker and are derived from pilot studies. Only one report applied MMF specifically to IMN patients. In these medium to high risk of progression patients, approximately one-half had a 50% reduction in their baseline proteinuria without a significant alteration in their serum creatinine level. MMF's role as a single agent or as adjunctive therapy in the treatment of IMN needs more rigorous evaluation.     

Mycophenolate mofetil inhibits intimal hyperplasia and attenuates the expression of genes favouring smooth muscle cell proliferation and migration

AIM: Intimal hyperplasia remains the leading cause of late graft failure following heart transplantation. The immunosuppressive drug mycophenolate mofetil has been shown to inhibit the development of intimal hyperplasia. This study aimed to assess the efficacy of a combination of mycophenolate mofetil, calcineurin inhibition, and sirolimus on the development of intimal hyperplasia. METHODS: Male Sprague-Dawley rats received mycophenolate mofetil (30 mg/kg per day) and either tacrolimus (0.1 mg/kg per day), cyclosporine (5 mg/kg per day), or sirolimus (0.05 mg/kg per day) and were compared to an untreated control group. All animals underwent left common carotid artery balloon angioplasty. Morphometric analysis was performed on representative transverse sections, and intima medial ratios calculated at 2 weeks. Profibrotic gene expression was assessed with competitive RT-PCR at 2 weeks for metalloproteinase-2, metalloproteinase-9, TIMP-1, collagen III, and TGF-beta. Sections were stained with sirius red, and extracellular matrix deposition was quantified. RESULTS: Mycophenolate mofetil in combination with rapamycin was associated with the greatest reduction in intimal thickening (intima medial ratio 0.79; range 0.45-0.86), compared to its combination with either cyclosporine (1.41; range 1.06-1.68, P < .02) or tacrolimus (0.93; range 0.81-1.37, P < .05) and controls (1.47; range 1.02-2.04, P < .005). Mycophenolate mofetil and rapamycin significantly inhibited all profibrotic genes studied compared to controls (P < .01) but there were no differences between tacrolimus and cyclosporine. Mycophenolate mofetil and sirolimus significantly attenuated extracellular matrix deposition compared to tacrolimus and cyclosporin (P < .023). CONCLUSION: The benefits of mycophenolate mofetil in combination with sirolimus are preferential over those with cyclosporine or tacrolimus. Randomised trials are warranted to assess if mycophenolate mofetil should be an alternative agent to calcineurin-inhibitors when used in combination with sirolimus.     

In vivo control of diabetogenic T-cells by regulatory CD4+CD25+ T-cells expressing Foxp3

To understand the ability of regulatory T-cells to control diabetes development in clinically relevant situations, we established a new model of accelerated diabetes in young DP-BB rats by transferring purified T-cells from DR-BB rats made acutely diabetic. Transfer of 3, 5, 10, or 23 million pure in vitro-activated T-cells accelerated diabetes onset in >90% of the recipients, with the degree of acceleration being dosage dependent. Cotransfer of unfractionated leukocytes from healthy donors prevented diabetes. Full protection was achieved when protective cells were transferred 3-4 days before diabetogenic cells, whereas transfer 2 days before conferred only partial protection. Protection resided in the CD4(+) fraction, as purified CD4(+) T-cells prevented the accelerated diabetes. When CD25(+) cells were depleted from these cells before they were transferred, their ability to prevent diabetes was impaired. In contrast, two million CD4(+)CD25(+) cells (expressing Foxp3) prevented the accelerated diabetes when transferred both before and simultaneously with the diabetogenic T-cells. In addition, 2 million CD4(+)CD25(+) T-cells prevented spontaneous diabetes, even when given to rats age 42 days, whereas 20 million CD4(+)CD25(-) cells (with low Foxp3 expression) were far less effective. We thus demonstrated that CD4(+)CD25(+) cells exhibit powerful regulatory potential in rat diabetes.     

Mycophenolate mofetil and C-reactive protein in renal transplant recipients

BACKGROUND: C-reactive protein (CRP) is a strong predictor of cardiovascular disease, all-cause mortality, and renal allograft loss. Little is known about the effects of immunosuppressive and cardiovascular risk-modifying drugs on CRP in renal transplant recipients. METHODS: We retrospectively identified stable patients with > or =1 highly sensitive CRP measurements between January 1 and August 31, 2005. Variables collected included patient demographics; transplant, dialysis, and cardiovascular disease-related variables; and medication profiles. Univariate correlations with CRP were assessed by unpaired Student t testing, analysis of variance, or chi analysis and followed by multivariate linear regression with stepwise backward elimination until a final stable model was attained. RESULTS: CRP levels were obtained in 298 recipients. In univariate analysis, body mass index (P<0.0001) and systolic blood pressure (P=0.009) showed a positive correlation, whereas number of immunosuppressive drugs (P=0.05) and use of mycophenolate mofetil (MMF) (P=0.003) were negatively correlated with CRP levels. By multivariate analysis, only body mass index (P<0.0001) and MMF dose (P<0.0001) were independently and opposingly correlated with CRP. Mean CRP level was 5.18+/-5.7 mg/L in patients not taking MMF compared with 3.13+/-3.5 mg/L in those on 2000 mg per day (P=0.002). CONCLUSIONS: MMF use correlates inversely with CRP levels in renal transplant recipients, suggesting that immunosuppressive regime design may alter allograft and cardiovascular disease risk in these patients. Prospective study of the effects of MMF on novel cardiovascular disease risk factors such as CRP is warranted.     

Mycophenolate mofetil in the treatment of focal segmental glomerulosclerosis

AIMS: Primary focal segmental glomerulosclerosis (FSGS) is a common cause of end-stage renal disease in both children and adults. Our current treatments are suboptimal, and a significant percentage of cases are resistant to current therapy. PATIENTS AND METHODS: We performed an open-label, 6-month trial of the new immunosuppressive agent mycophenolate mofetil (MMF) in 18 biopsy-proven patients resistant to a course of corticosteroids therapy. Seventy-five percent had also failed to respond to a cytotoxic agent and/or a calcineurin inhibitor. RESULTS: A substantial improvement in proteinuria was seen in 44% (8/18) of the patients by 6 months. This was sustained for up to 1 year post treatment in 50% (4/8) of this group. No patient had a complete remission. No deterioration in renal function was observed in any patient over the treatment period, but 3 progressed to chronic kidney failure during follow-up. Adverse effects were mild. Only 1 patient required a dose reduction due to an intercurrent infection. CONCLUSIONS: MMF appears safe to use in this group of patients and did lower proteinuria in 44% of this cohort resistant to other forms of treatment. Relapses were common, suggesting more prolonged or combination therapy may be required. More rigorous trials utilizing this medication should be considered to further assess the risk-benefit ratio of treatment with MMF in patients with FSGS.