Dietary amino acids as new and novel agents to enhance allograft survival

Immunonutrition in kidney and liver transplant recipients

The immunonutrients arginine and omega-3 fatty acids decrease adverse outcomes after solid organ transplant in humans and experimental animals. Kidney transplant recipients who received daily supplements with arginine (9 g) and canola oil (30 mL) had significantly lower frequencies of complications between 30 days to 3 years than transplant recipients who did not receive supplements. In another study in kidney transplant recipients, arginine combined with either canola oil or fish oil was safe, effective, and provided good protection against rejection in patients who had steroid-free immunosuppression. In the 27 patients (50%) who had omega-3 index (percent omega-3 component of all fatty acids in red blood cell membranes) > 6 there was no acute rejection by 1 year after transplant; in 27 patients who had omega-3 index < 6, there were 5 patients (19%) who had acute rejection (P ≤ .01). No studies are available in liver transplant patients that have provided adequate doses or duration of immunonutrients. A prospective, randomized, double-blind clinical trial using immunonutrients is proposed for patients having primary liver transplant. In summary, immunonutrition in kidney transplant recipients with high doses of oral arginine and omega-3 fatty acids is effective, safe, and inexpensive, and may decrease the frequency of complications such as rejection, infection, new onset diabetes and cardiovascular disease. Further study with similar protocols in liver transplant recipients is justified.

Simultaneous corticosteroid avoidance and calcineurin inhibitor minimization in renal transplantation

Steroids and calcineurin inhibitors (CNI) have been mainstays of immunosuppression but both have numerous side effects that are associated with substantial morbidity and mortality. This study was carried out to determine if steroids can be eliminated with early discontinuation of cyclosporine A (CsA) and later discontinuation of mycophenolate mofetil (MMF). Ninety-six patients with kidney transplants were entered into four subgroups of two pilot studies. All patients received Thymoglobulin induction, rapamycin (RAPA), and the immunonutrients arginine and an oil containing omega-3 fatty acids. Mycophenolate mofetil was started in standard doses and discontinued by 2 years. CsA was given in reduced doses for either 4, 6, or 12 months. Follow-up was 12-36 months. Thirteen first rejection episodes occurred during the first year (14%). Combining all patients, 86% were rejection-free at 1 year, 80% at 2 years and 79% at 3 years. No kidney has been lost to acute rejection. Ninety percent of the 84 patients at risk at the end of the study were steroid-free and 87% were off CNI. Fifty-seven percent of 54 patients with a functioning kidney at 3 years were receiving monotherapy with RAPA. We conclude that this therapeutic strategy is worthy of a prospective multi-center clinical trial.

The Influence of Immunomodulatory Diets on Transplant Success and Complications

BACKGROUND

Animal studies have shown that dietary supplementation with arginine and lipids containing the omega-3 and omega-9 fatty acids prolong allograft survival in animals receiving a short course of low-dose cyclosporine. They also reduce cardiovascular complications and infections in humans.

METHODS

Adult renal transplant patients receiving standard immunosuppression were stratified according to gender, diabetic state, donor source (LD or CD), and first versus repeat transplant, and randomized to receive or not receive supplemental arginine and canola oil (containing both omega-3 and omega-9 fatty acids) twice daily. Patients were followed for a minimum of 3 years.

RESULTS

Seventy-six patients were randomized to the supplement group (S) and 71 patients to the control group (C). Intent-to-treat analysis revealed that S patients had fewer post-30 day first rejection episodes (5.4%) when compared with the C group (23.7%) (P=0.01) and fewer post-30 day episodes of calcineurin inhibitor (CNI) drug toxicity (9.2% vs. 35.3%, P=0.003). S patients developed new onset diabetes mellitus (NODM) less frequently by 3 years (2.3% vs. 14.5%, P=0.04), had fewer cardiac events (5.0% vs. 17.1%, P=0.05), and fewer episodes of sepsis (6.5% vs. 18.7%, P=0.05).

CONCLUSIONS

Dietary supplementation with L-arginine and canola oil is a safe, inexpensive, and unique treatment, which is associated with decreased rejection rates and CNI toxicity after the first month in renal transplant patients. Due to reductions in NODM and cardiac events, long-term benefits for patient survival may be particularly important.

Acute renal transplant rejection possibly related to herbal medications

Use of herbal and alternative medications in the United States is increasing. Many of these medications have unknown mechanisms of actions, and possible metabolic interactions with prescribed medications. We report a case of late acute rejection after exposure to two popular herbal medications.

Blockade of the L-arginine/NO synthase pathway worsens hepatic apoptosis and liver transplant preservation injury

Organ graft preservation injury is a major problem complicating liver transplantation. The L-arginine/nitric oxide pathway has protective effects in several models of liver injury. The purpose of this study was to evaluate the role of the L-arginine/NO synthase (NOS) pathway on liver preservation injury and to characterize endogenous inducible NOS (iNOS) expression. Orthotopic liver transplantation was performed with 18-hour University of Wisconsin preservation solution in syngeneic rats. Recipient rats were either untreated or treated with L-arginine, D-arginine, nonspecific NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME), or iNOS selective inhibitor L-N(6)-(1-imino-ethyl)lysine (L-NIL) after revascularization. As early as 1 hour following reperfusion, circulating arginine levels decreased 10-fold and ornithine levels increased 4-fold. A corresponding increase in arginase I protein was detected in serum. To address the profound arginine deficiency, we supplemented recipients with arginine after transplantation. L-arginine (but not D-arginine) supplementation significantly reduced preservation injury 12 hours after reperfusion, suggesting that the protective effect of L-arginine was mediated through the generation of NO. iNOS protein expression peaked in the liver 6 to 12 hours following reperfusion. Blockade of the L-arginine/NO pathway with L-NAME significantly increased necrotic and apoptotic cell death in the transplanted graft. Addition of the iNOS selective inhibitor L-NIL mildly increased liver transaminase levels and also increased apoptosis in the liver graft. In conclusion, transplant recipients are profoundly arginine deficient postreperfusion due to arginase release. L-Arginine supplementation and NO synthesis decrease necrotic and apoptotic cell death and ameliorate liver transplant preservation injury.

A high isoflavone soy protein diet and intravenous genistein delay rejection of rat cardiac allografts

Genistein, a soy isoflavone, has in vitro immunosuppressive properties. We investigated whether genistein or dietary soy protein containing isoflavones could influence the outcome of rat cardiac allografts. Lewis rats were fed a diet with protein from high isoflavone soy protein fraction (HIS), casein (CAS) or casein with isoflavones added (CI) starting 1 wk before heart transplants from Wistar Furth donors, and continuing throughout the study. HIS-fed rats had significantly prolonged time to rejection compared with CAS- and CI-fed recipients (10.8 +/- 2.62 vs. 7.18 +/- 0.75 and 7.22 +/- 0.44 d, P < 0.001). Intravenous genistein [20mg/(kg. d) for 14 d] significantly prolonged heart survival compared with controls and dissolvent-treated recipients (23.2 +/- 7.4 vs. 8.4 +/- 1.3 and 11.4+/3.6 d, P < 0.0005), and had an additive effect when given to heart recipients also receiving low dose cyclosporine for 7 d (30.8 +/- 2.3 vs. 23.4 +/- 2.4 d, P < 0.005). Concanavalin A-stimulated lymphocytes, isolated from Lewis rats given intraperitoneal genistein for 7 d, had decreased production of interferon gamma compared with controls or dimethyl sulfoxide-treated groups (22.6 +/- 9.9 vs 149 +/- 105 and 154 +/- 103 micro g/L, P < 0.05). In conclusion, a high isoflavone soy diet and intravenous genistein, but not isoflavone extract alone, delay rejection of rat cardiac allografts, with an additive effect in cyclosporine-treated rats. In addition, intraperitoneal genistein has immunosuppressive properties in vivo.

Nutritional pharmacology in surgical patients

The use of pharmaconutrition for supportive care of surgical patients is now well established, but the field is still in its infancy. Complex pharmaconutrient formulas containing arginine, glutamine, and n-3 fatty acids have been proven to shorten hospital stay, decrease the incidence of infection, and reduce hospital costs in selected groups of patients. The effects are greatest in those patients with severe trauma including burn injury, those undergoing major surgical procedures, especially when malnourished, and those who are critically ill ICU patients including patients with existing infection. The complex interaction of pharmaconutrients and other pharmacologic agents are just now beginning to be investigated.

Oral arginine improves blood pressure in renal transplant and hemodialysis patients

BACKGROUND

Hypertension in kidney transplant (KT) patients may result from attenuated whole-body nitric oxide (NO) content and abnormal NO-mediated vasodilation. Increasing NO bioavailability with L-arginine (ARG) could theoretically restore the NO-mediated vasodilatory response and lower blood pressure.

METHODS

In a prospective pilot study, 6 normotensive volunteers and 10 KT patients received oral supplements of ARG (9.0 g/d) for 9 days, then 18.0 g/d for 9 more days. Six hemodialysis (HD) and 4 peritoneal dialysis patients received the same dose for 14 days. Five KT patients received 30 mL/d of canola oil (CanO) in addition to ARG. Systolic (SBP) and diastolic (DBP) blood pressure, creatinine clearance (CCr), and serum creatinine (Cr) were measured at baseline, day 9, and day 18. In a subsequent study, 20 hypertensive KT patients with stable but abnormal renal function were randomized in a crossover study to start ARG-only or ARG+CanO supplements for two 2-month periods with an intervening month of no supplementation. SBP, DBP, CCr, and Cr were measured monthly for 7 months.

RESULTS

In the pilot study, ARG reduced the SBP in HD patients from 171.5 +/- 7.5 mmHg (baseline) to 142.8 +/- 8.3 mmHg (p = .028). In the crossover study, SBP was reduced from baseline (155.9 +/- 5.0 mmHg), after the first 2 months (143.2 +/- 3.2 mmHg; p = .03) and subsequent 2 months (143.3 +/- 2.5 mmHg; p = .014) of supplementation. DBP was also reduced after supplementation in both studies. CanO had no effect on blood pressure. Renal function did not change.

CONCLUSIONS

Oral preparations of ARG (+/-CanO) were well tolerated for up to 60 consecutive days and had favorable effects on SBP and DBP in hypertensive KT and HD patients.