Pharmacology of immunosuppressive medications used in renal diseases and transplantation

2-Methoxyestradiol TPGS Micelles Attenuate Cyclosporine A-Induced Nephrotoxicity in Rats through Inhibition of TGF-β1 and p-ERK1/2 Axis

The immunosuppressant cyclosporine A (CSA) has been linked to serious renal toxic effects. Although 2-methoxyestradiol (2ME) possesses a wide range of pharmacological abilities, it suffers poor bioavailability after oral administration. The purpose of this study was to evaluate the potential of 2ME loaded D-ɑ-tocopheryl polyethylene glycol succinate (TPGS) micelles to prevent CSA-induced nephrotoxicity in rats. A 2ME-TPGS was prepared and showed particle size of 44.3 ± 3.5 nm with good entrapment efficiency and spherical structures. Male Wistar rats were divided into 5 groups, namely: Control, Vehicle, CSA, CSA + 2ME-Raw, and CSA + 2ME-Nano. CSA was injected daily at a SC dose of 20 mg/kg. Both 2ME-Raw and 2ME-Nano were given daily at oral doses of 5 mg/kg. Treatments continued for three successive weeks. 2ME-TPGS exerted significant protective effects against CSA nephrotoxicity. This was evidenced in ameliorating deterioration of renal functions, attenuation of pathological changes in kidney tissues, exerting significant anti-fibrotic, antioxidant, and anti-inflammatory effects together with significant anti-apoptotic effects. Western blot analyses showed both 2ME-Raw and 2ME-Nano significantly inhibited protein expression of TGF-β1 and phospho-ERK (p-ERK). It was observed that 2ME-TPGS, in almost all experiments, exerted superior protective effects as compared with 2ME-Raw. In conclusion, 2ME loaded in a TPGS nanocarrier possesses significant protective activities against CSA-induced kidney injury in rats. This is attributable to 2ME anti-fibrotic, antioxidant, anti-inflammatory, and anti-apoptotic activities which are mediated at least partly by inhibition of TGF-β1/p-ERK axis.

Treatment of Hypertension Because of Immunosuppressive Therapy After Solid Organ Transplantation-Pharmacological Approach

ABSTRACT

Solid organs transplantation procedures have been performed for more than half a century. Growing knowledge of immune response and development of new immunosuppressive regimens guarantee more and more successful outcomes. However, many of the applied drugs lead to cardiovascular complications, the most frequent of which is hypertension. This article describes epidemiology, pathogenetic mechanisms, and treatment of hypertension induced by immunosuppressive medication. The main impact is focused on drugs belonging to the following groups: calcineurin inhibitors, the inhibitors of the mammalian target of rapamycin, and glucocorticosteroids. We analyze the mechanism of action of the main hypertensive drugs and their influence on the reversing hypertonic action of the immunosuppressive agents. In the absence of current guidelines addressing this problem, this article is an attempt to fill the gap, helping clinicians to choose proper medication.

Hypertension in Kidney Transplant Recipients: Where Are We Today?

PURPOSE OF REVIEW

Cardiovascular disease is the leading cause of death and allograft loss among kidney transplant recipients, and hypertension is an independent risk factor for cardiovascular morbidity of this patient population. The etiology of hypertension is multifactorial, including pre-transplant volume overload, post-transplant recipient and donor-associated variables, and transplant-specific causes (immunosuppressive medications, allograft dysfunction and surgical complications such as transplant artery stenosis).

RECENT FINDINGS

No randomized controlled trials have assessed the optimal blood pressure targets and explored the best antihypertensive regimen for kidney transplant recipients. According to the large observational studies, it is reasonable to achieve a blood pressure goal of equal to or less than 130/80 mmHg in the long-term follow-up for minimizing the cardiovascular morbidity. The selection of antihypertensive agents should be based on the patient's co-morbidities; however, the initial choice could be calcium channel blockers especially in the first few months of transplantation. In patients with cardiovascular indications of renin-angiotensin-aldosterone system inhibition, given the well-described benefits in diabetic and proteinuric patients, it is reasonable to consider the use of renin-angiotensin-aldosterone system inhibitors. There is a need for future prospective trials in the transplant population to define optimal blood pressure goals and therapies.

Approach and Management of Hypertension After Kidney Transplantation

Hypertension is one of the most common cardiovascular co-morbidities after successful kidney transplantation. It commonly occurs in patients with other metabolic diseases, such as diabetes mellitus, hyperlipidemia, and obesity. The pathogenesis of post-transplant hypertension is complex and is a result of the interplay between immunological and non-immunological factors. Post-transplant hypertension can be divided into immediate, early, and late post-transplant periods. This classification can help clinicians determine the etiology and provide the appropriate management for these complex patients. Volume overload from intravenous fluid administration is common during the immediate post-transplant period and commonly contributes to hypertension seen early after transplantation. Immunosuppressive medications and donor kidneys are associated with post-transplant hypertension occurring at any time point after transplantation. Transplant renal artery stenosis (TRAS) and obstructive sleep apnea (OSA) are recognized but common and treatable causes of resistant hypertension post-transplantation. During late post-transplant period, chronic renal allograft dysfunction becomes an additional cause of hypertension. As these patients develop more substantial chronic kidney disease affecting their allografts, fibroblast growth factor 23 (FGF23) increases and is associated with increased cardiovascular and all-cause mortality in kidney transplant recipients. The exact relationship between increased FGF23 and post-transplant hypertension remains poorly understood. Blood pressure (BP) targets and management involve both non-pharmacologic and pharmacologic treatment and should be individualized. Until strong evidence in the kidney transplant population exists, a BP of <130/80 mmHg is a reasonable target. Similar to complete renal denervation in non-transplant patients, bilateral native nephrectomy is another treatment option for resistant post-transplant hypertension. Native renal denervation offers promising outcomes for controlling resistant hypertension with no significant procedure-related complications. This review addresses the epidemiology, pathogenesis, and specific etiologies of post-transplant hypertension including TRAS, calcineurin inhibitor effects, OSA, and failed native kidney. The cardiovascular and survival outcomes related to post-transplant hypertension and the utility of 24-h blood pressure monitoring will be briefly discussed. Antihypertensive medications and their mechanism of actions relevant to kidney transplantation will be highlighted. A summary of guidelines from different professional societies for BP targets and antihypertensive medications as well as non-pharmacological interventions, including bilateral native nephrectomy and native renal denervation, will be reviewed.

Fish oil for kidney transplant recipients

BACKGROUND

Calcineurin inhibitors used in kidney transplantation for immunosuppression have adverse effects that may contribute to nephrotoxicity and increased cardiovascular risk profile. Fish oils are rich in very long chain omega-3 fatty acids, which may reduce nephrotoxicity by improving endothelial function and reduce rejection rates through their immuno-modulatory effects. They may also modify the cardiovascular risk profile. Hence, fish oils may potentially prolong graft survival and reduce cardiovascular mortality.

OBJECTIVES

This review aimed to look at the benefits and harms of fish oil treatment in ameliorating the kidney and cardiovascular adverse effects of CNI-based immunosuppressive therapy in kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register (up to 17 March 2016) through contact with the Information Specialist using search terms relevant to this review.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs of fish oils in kidney transplant recipients on a calcineurin inhibitor-based immunosuppressive regimen. RCTs of fish oil versus statins were included.

DATA COLLECTION AND ANALYSIS

Data was extracted and the quality of studies assessed by two authors, with differences resolved by discussion with a third independent author. Dichotomous outcomes were reported as risk ratio (RR) and continuous outcome measures were reported as the mean difference (MD) with 95% confidence intervals using the random effects model. Heterogeneity was assessed using a Chi(2) test on n-1 degrees of freedom and the I(2) statistic. Data not suitable for pooling were tabulated and described.

MAIN RESULTS

Fifteen studies (733 patients) were suitable for analysis. All studies were small and had variable methodology. Fish oil did not significantly affect patient or graft survival, acute rejection rates, or calcineurin inhibitor toxicity when compared to placebo. Overall SCr was significantly lower in the fish oil group compared to placebo (5 studies, 237 participants: MD -30.63 µmol/L, 95% CI -59.74 to -1.53; I(2) = 88%). In the subgroup analysis, this was only significant in the long-course (six months or more) group (4 studies, 157 participants: MD -37.41 µmol/L, 95% CI -69.89 to -4.94; I(2) = 82%). Fish oil treatment was associated with a lower diastolic blood pressure (4 studies, 200 participants: MD -4.53 mm Hg, 95% CI -7.60 to -1.45) compared to placebo. Patients receiving fish oil for more than six months had a modest increase in HDL (5 studies, 178 participants: MD 0.12 mmol/L, 95% CI 0.03 to 0.21; I(2) = 47%) compared to placebo. Fish oil effects on lipids were not significantly different from low-dose statins. There was insufficient data to analyse cardiovascular outcomes. Fishy aftertaste and gastrointestinal upset were common but did not result in significant patient drop-out.

AUTHORS' CONCLUSIONS

There is insufficient evidence from currently available RCTs to recommend fish oil therapy to improve kidney function, rejection rates, patient survival or graft survival. The improvements in HDL cholesterol and diastolic blood pressure were too modest to recommend routine use. To determine a benefit in clinical outcomes, future RCTs will need to be adequately powered with these outcomes in mind.

The essential role of annexin A1 mimetic peptide in the skin allograft survival

Immunosuppressive drugs have a critical role in inhibiting tissue damage and allograft rejection. Studies have demonstrated the anti-inflammatory effects of the annexin A1 (AnxA1) in the regulation of transmigration and apoptosis of leucocytes. In the present study, an experimental skin allograft model was used to evaluate a potential protective effect of AnxA1 in transplantation survival. Mice were used for the skin allograft model and pharmacological treatments were carried out using either the AnxA1 mimetic peptide Ac2-26, with or without cyclosporine A (CsA), starting 3 days before surgery until rejection. Graft survival, skin histopathology, leucocyte transmigration and expression of AnxA1 and AnxA5 post-transplantation were analysed. Pharmacological treatment with Ac2-26 increased skin allograft survival related with inhibition of neutrophil transmigration and induction of apoptosis, thereby reducing the tissue damage compared with control animals. Moreover, AnxA1 and AnxA5 expression increased after Ac2-26 treatment in neutrophils. Interestingly, the combination of Ac2-26 and cyclosporine A showed similar survival of transplants when compared with the cyclosporine A group, which could be attributed to a synergistic effect of both drugs. Investigations in vitro revealed that cyclosporine A inhibited extracellular-signal-regulated kinase (ERK) phosphorylation induced by Ac2-26 in neutrophils. Overall, the results suggest that AnxA1 has an essential role in augmenting the survival of skin allograft, mainly owing to inhibition of neutrophil transmigration and enhancement of apoptosis. This effect may lead to the development of new therapeutic approaches relevant to transplant rejection.

In vivo toxicological evaluation of Anisomycin

Anisomycin is a pyrrolidine antibiotic isolated from Streptomyces griseolus. Recent studies have shown that Anisomycin as a novel immunosuppressive agent is superior to Cyclosporine A (J. Immunother. 31, 858-870, 2008). In order to make toxicological evaluation of Anisomycin, acute and four-week continuously intravenous toxicity studies were performed in mice. IC(50) value tested on peripheral lymphocytes was 25.44 ng/ml. The calculated LD(50) for Anisomycin was 119.64 mg/kg. The mice were intravenously injected through mouse tail vein with a total dose of 5, 15, 30 and 60 mg/kg/mice of Anisomycin every other day for 4 weeks. Just in the high-dose mice, death of three mice happened and body weight of the mice was significantly decreased. Statistically significant changes in organ index included increases in ratios of the spleen, liver, lung and brain to the body weight, and decrease in ratio of the thymus to the body weight. Changes in clinical biochemistry parameters included increases in the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities, and decreases in the glucose (GLU) activity. The distinct inflammation appeared in the lung, liver and kidney, and the number and size of megakaryocytes in the spleen were significantly increased. Anisomycin did not induce formation of the peripheral blood micronucleus, but increased the number of micronucleated polychromatic erythrocytes in bone marrow and sperm aberrations. However, the above aberrant changes occurred only in the mice treated with the high-dose Anisomycin. These results indicate that although Anisomycin has no significant side effects at effectively therapeutic doses, its over-dosage may lead to toxicity, particularly pulmo-, nephro- and hepato-toxicity.

Simvastatin-induced myoglobinuric acute kidney injury following ciclosporin treatment for alopecia universalis

Alopecia areata can affect the entire scalp (alopecia totalis) or cause loss of all body hair (alopecia universalis). Ciclosporin (CsA) has been suggested for its treatment, with controversial results. Concomitant use of statins and CsA may increase the risk of rhabdomyolysis due to drug–drug interactions.

Here we report the case of a 45-year-old woman treated with CsA for alopecia universalis, who presented a severe myoglobinuric acute kidney injury following the concomitant use of simvastatin. Upon admission to our unit, she was oligo-anuric. Her serum creatinine level was 13.8 mg/dl. CsA and simvastatin therapy were stopped, and haemodialysis treatment was started (eight daily dialysis sessions) until sufficient kidney function was regained. After 1 month, her serum creatinine level was 3.5 mg/dl; after 2 months and onwards (follow-up of 4 months), her serum creatinine level was 1.4 mg/dl and creatinine clearance was 43.2 ml/min.

In conclusion, physicians should be aware of the potential risks of the combined use of CsA and statins. Patients should be advised to report any muscle symptoms when they are on statins and CsA. The laboratory follow-up should include the monitoring of serum creatinine and muscle enzyme levels, blood CsA levels and liver function tests.

Down-regulation of transforming growth factor beta-2 expression is associated with the reduction of cyclosporin induced gingival overgrowth in rats treated with roxithromycin: an experimental study

Background

Gingival overgrowth (GO) is a common side effect of the chronic use of cyclosporine (CsA), an immunosuppressant widely used to prevent rejection in transplant patients. Recent studies have reported elevated levels of specific cytokines in gingival overgrowth tissue, particularly TGF-beta, suggesting that this growth factor plays a role in the accumulation of extracellular matrix materials. The effectiveness of azithromycin, a macrolide antibiotic, in the regression of this undesirable side effect has also been demonstrated.

Methods

In this study, we created an experimental model for assessing the therapeutic effect of roxithromycin in GO and the expression of transforming growth factor beta (TGF-beta2) through immunohistochemistry. We used four groups of rats totaling 32 individuals. GO was induced during five weeks and drug treatment was given on the 6th week as follows: group 1 received saline; group 2 received CsA and was treated with saline on the 6th week; group 3 received CsA and, on the 6th week, ampicilin; and group 4 received CsA during 5 weeks and, on the 6th week, was treated with roxithromycin.

Results

The results demonstrated that roxithromycin treatment was effective in reducing cyclosporine-induced GO in rats. Both epithelial and connective tissue showed a decrease in thickness and a significant reduction in TGF-beta2 expression, with a lower number of fibroblasts, reduction in fibrotic areas and decrease in inflammatory infiltrate.

Conclusion

The present data suggest that the down-regulation of TGF-beta2 expression may be an important mechanism of action by which roxithromycin inhibits GO.

Anisomycin inhibits the behaviors of T cells and the allogeneic skin transplantation in mice

There is still a lack of a high potent and low toxic immunosuppressive drug. We accidentally found that a quite low dose of anisomycin was sufficient to block proliferation of T cells. In this study, carboxy-fluorescein diacetate-succinimidyl ester staining showed that over 10.0 ng/mL of anisomycin markedly inhibited the proliferation of T cells induced by ConA. Propidium iodide staining revealed that anisomycin led to G0/G1 arrest and blocked S phase entry stimulated by ConA or phorbol 12, 13-dibutyrate plus ionomycin. Anisomycin down-regulated remarkably the CD69 and CD25 expression on the surface of T cells. The response of T cells was repressed by treatment of anisomycin, which was partly restored by adding exogenous interleukin-2, and there was no difference between anisomycin and dexamethasone, although the used dose of the latter was 100-fold of the former. The inhibition of cytotoxicity of T cells against 7919 cells by anisomycin was observed without the direct cytotoxicity to T cells or 7919 cells. The level of transforming growth factor-beta1 fell by <80.0 ng/mL in vitro and 30.0 mg/kg of anisomycin in vivo and enhanced by more than the doses. The treatment of anisomycin prolonged the survival of the transplanted skin and depressed the delayed type hypersensitivity development and the T-cell response in the skin-transplanted mice. Moreover, the effect of its restraining allograft rejection might be superior to cyclosporine A, with relatively slight toxic signs. These results indicate anisomycin significantly inhibits the behaviors of T cells and the transplantation rejection, providing important evidence for anisomycin as a novel immunosuppressant.

Comparison of Azithromycin and Oral Hygiene Program in the Treatment of Cyclosporine-Induced Gingival Hyperplasia

BACKGROUND

It has been shown that azithromycin improves cyclosporine-induced gingival hyperplasia (GH), but its efficacy was never compared against an efficient oral hygiene program (OHP). The aim of this study was to analyze the effects of azithromycin plus OHP versus OHP alone in patients with cyclosporine-induced GH.

METHODS

After periodontal evaluation, 20 renal transplant recipients received detailed oral hygiene instructions and a complete OHP, and were randomized to control (OHP) or azithromycin groups (OHP plus azithromycin). Patients were re-evaluated after 15 and 30 days. Both groups were similar in time after transplant, age, gender, cyclosporine dose, and cyclosporine through level and serum creatinine. The control group had fewer patients using calcium cannel blockers (10% vs. 70%, p = 0.02).

RESULTS

All patients improved in pain, halitosis, and gum bleeding after OHP. The control group did not improve plaque index (PI) or GH. In contrast, baseline PI decreased from 1.52 +/- 0.28 to 0.50 +/- 0.16 on day 15 (p < 0.01) and to 0.46 +/- 0.14 on day 30 (p < 0.01) in the azithromycin group, and the GH score decreased from 1.9 +/- 0.27 to 0.90 +/- 0.27 on day 15 (p < 0.05) and to 0.70 +/- 0.21 on day 30 (p < 0.01).

CONCLUSION

Azithromycin associated to efficient OHP induced a striking reduction in cyclosporine-induced GH, while efficient OHP alone improved oral symptoms but did not decrease cyclosporine-induced GH.

[Infections in the immunocompromised host. What is the role of the medications?]

Infections in patients with connective tissue diseases (CTD) are associated to considerable morbidity and mortality. Some patients with CTD suffer a certain degree of immune deregulation inherent to their rheumatic disease. Other factors such as advanced age, and the coexistence of other chronic diseases such as diabetes mellitus can also lead to the development of infection. Glucocoticosteroids induce a reduction in the synthesis of most of the known cytokines, an alteration in the migration of leukocytes from the blood with an alteration in antigen presentation and an abnormal cytotoxic response. Immunosuppresants fundamentally affect cellular immunity and its effect is related to the duration of treatment and dose. There is a clear relationship between the use of anti-TNF drugs and the reactivation of tuberculosis. Its clinical and histological manifestations are frequently atypical. In those cases in which active tuberculosis is suspected, anti-TNF must be suspended until infection is ruled out. Prophylactic treatment when faced with Pneumocystis jiroveci with cotrimoxazole has been recommended in patients that receive steroids and immunosuppressants, especially if the agent employed is cyclophosphmide or if lymphopenia develops.

Neurological complications after orthotopic liver transplantation

BACKGROUND

The number of orthotopic liver transplantation performed each year is increasing due to increased safety and logistic facilities. Therefore, the importance of reducing adverse events is progressively growing.

AIM

To review present knowledge on the neurological complications of orthotopic liver transplantation.

METHODS

The epidemiology, the clinical features and the pathophysiology of the neurological complications of orthotopic liver transplants, resulting from a systematic review of the literature in the last 25 years, are summarized.

RESULTS AND CONCLUSIONS

The review highlights that a relevant variety of neurological adverse events can occur in patients undergoing orthotopic liver transplantation. The knowledge of neurological complications of orthotopic liver transplantation is important for transplantation teams to reduce their prevalence and improve their management. In addition, the likelihood of neurological adverse effects provides evidence for the need of a careful cognitive and neurological work up of patients in the orthotopic liver transplantation waiting list, in order to recognize and interpret neurological dysfunction occurring after orthotopic liver transplantation.

Fish oil for kidney transplant recipients

BACKGROUND

Calcineurin inhibitors used in kidney transplantation for immunosuppression have adverse effects that may contribute to nephrotoxicity and increased cardiovascular risk profile. Fish oils are rich in very long chain omega-3 fatty acids, which may reduce nephrotoxicity by improving endothelial function and reduce rejection rates through their immuno-modulatory effects. They may also modify the cardiovascular risk profile. Hence, fish oils may potentially prolong graft survival and reduce cardiovascular mortality.

OBJECTIVES

To assess the benefits and harms of fish oil supplementation on kidney transplant recipients on a calcineurin inhibitor-based immunosuppressive regimen.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library, issue 2 2005), MEDLINE (1966-April 2005) and EMBASE (1980-April 2005).

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs of fish oils in kidney transplant recipients on a calcineurin inhibitor-based immunosuppressive regimen. RCTs of fish oil versus statins were included.

DATA COLLECTION AND ANALYSIS

Data was extracted and the quality of studies assessed by two authors, with differences resolved by discussion with a third independent author. Dichotomous outcomes were reported as relative risk (RR) and continuous outcome measures were reported as the mean difference (MD) with 95% confidence intervals using the random effects model. Heterogeneity was assessed using a Chi(2) test on n-1 degrees of freedom and the I(2) statistic. Data not suitable for pooling were tabulated and described.

MAIN RESULTS

Sixteen studies (733 patients) were suitable for analysis. Fish oil did not significantly affect patient or graft survival, acute rejection rates, calcineurin inhibitor toxicity or renal function, when compared to placebo. Fish oil treatment was associated with a lower diastolic blood pressure (MD 4.5 mmHg; P = 0.004) compared to placebo. Patients receiving fish oil for more than six months had a modest increase in HDL (MD 0.12 mmol/L; P = 0.01) compared to placebo. Fish oil effects on lipids were not significantly different from low-dose statins. There was insufficient data to analyse cardiovascular outcomes. Fishy aftertaste and gastrointestinal upset were common but did not result in significant patient drop-out.

AUTHORS' CONCLUSIONS

There is insufficient evidence from currently available RCTs to recommend fish oil therapy to improve renal function, rejection rates, patient survival or graft survival. The improvements in HDL cholesterol and diastolic blood pressure were too modest to recommend routine use. To determine a benefit in clinical outcomes, future RCTs will need to be adequately powered with these outcomes in mind.

Investigation of the Effect of Hyperbaric Oxygen on Experimental Cyclosporine Nephrotoxicity

Hyperbaric oxygen interacts with drugs which patients use concurrently with hyperbaric oxygen treatment, which may cause in potentiation or inhibition of both therapeutic and toxic effects. We examined the effect of hyperbaric oxygen therapy on experimental cyclosporine A nephrotoxicity. The study comprised four groups of rats: a control group, a cyclosporine A group (25 mg/kg/day intraperitoneally for four days), a hyperbaric oxygen group (60 min. every day for four days at 2.5 atmospheric pressure), and a cyclosporine A+hyperbaric oxygen group (CsA 25 mg/kg/day intraperitoneally for four days+hyperbaric oxygen for 60 min. every day for four days at 2.5 atmospheric pressure). Hyperbaric oxygen did not alter biochemical parameters. Cyclosporine A increased serum urea and serum creatinine levels and decreased creatinine clearance. In the cyclosporine A+hyperbaric oxygen group serum urea level increased more than in the cyclosporine A group. Cyclosporine A increased tubular epithelial cell apoptosis and necrosis score values. The numbers of apoptotic cells in proximal tubule epithelial cells in the cyclosporine A+hyperbaric oxygen group were significantly higher than those of the cyclosporine A group. We recommend that renal functions of the patients receiving cyclosporine A should be monitored during hyperbaric oxygen therapy.

Tacrolimus and nonsteroidal anti-inflammatory drugs: an association to be avoided

BACKGROUND

Tacrolimus (FK) and nonsteroidal anti-inflammatory drugs (NSAIDs) can cause acute nephrotoxicity. The expanding use of tacrolimus and the intense consumption of NSAIDS increase the chances of their simultaneous use.

METHODS

Rats receiving a nonselective COX inhibitor (diclofenac, D) and FK or a selective COX-2 inhibitor (rofecoxib, RO) and FK were treated with FK (2 mg/kg/day), D (10 mg/kg/day), RO (3 mg/kg/day), FK+D, FK+RO and vehicle for 7 days on low-salt diet.

RESULTS

Both associations significantly impaired glomerular filtration rate (GFR; 0.63 +/- 0.06 ml/min/100 g in FK+D, 0.83 +/- 0.06 ml/min/100 g in FK+RO) which did not occur with single drug therapy (0.98 +/- 0.03 ml/min/100 g in D, 1.06 +/- 0.04 ml/min/100 g in RO, 0.99 +/- 0.05 ml/min/ 100 g in FK) or vehicle (1.10 +/- 0.05 ml/min/100 g). GFR decrease was significantly higher with FK+D. GFR impairment occurred without RBF or RVR major changes. Mild tubular vacuolization and dilatation and acute degenerative changes were observed in tubular cells. FK+D animals showed a marked weight loss, not observed in the other groups. FK+NSAIDs association decreased FK blood levels (1.73 +/- 0.3 ng/ml in FK+D, 1.8 +/- 0.3 ng/ml in FK+RO, 3.2 +/- 0.4 ng/ml in FK, p < 0.05).

CONCLUSIONS

The association of FK and nonselective or COX-2 selective NSAIDs in salt-depleted animals caused a significant GFR impairment and decreased FK blood levels.

Nephrotoxic aspects of cyclosporine

Over the last 20 years cyclosporine (CsA) has improved the survival of kidney, heart, and liver transplants. However, with increasing use, evidence has accumulated that CsA therapy carries a variety of side effects, the most important being renal toxicity. CsA can lead to a wide spectrum of renal function impairments, including a marked and rapidly reversible decrease in renal hemodynamics (acute CsA nephrotoxicity), and a chronic form of renal damage that potentially progress irreversibly to end-stage renal disease (chronic CsA nephrotoxicity). All these manifestations are the consequence of the drug toxic effects on renal vessels and the tubulointerstitium. A proper diagnosis of CsA toxicity at early stages, the combination of low CsA doses with non-nephrotoxic immunosuppressants, and the development of more feasible strategies to monitor daily CsA exposure may contribute to a better CsA management, improve quality of life of transplant recipients, and prolong graft survival.

Influence of Age on Combined Effects of Cyclosporin and Nifedipine on Rat Alveolar Bone

BACKGROUND

There is some evidence showing that cyclosporin A (CsA) and nifedipine (NIF) affect bone metabolism. The purpose of this work was to study the effects of CsA and NIF, given alone or concurrently, on alveolar bone of rats of different ages.

METHODS

Rats 15, 30, 60, and 90 days old were treated daily with 10 mg/kg body weight of CsA subcutaneously injected and/or 50 mg/kg body weight of NIF/day given orally for 60 days. Alveolar bone of the first lower molars was morphologically and stereologically evaluated in serial 5 microm bucco-lingual paraffin sections, stained with hematoxylin and eosin. Serum calcium and alkaline phosphatase levels were measured in all animals at the end of the experimental period.

RESULTS

Rats treated with CsA or NIF alone or CsA and NIF concurrently showed decreased alveolar bone density. CsA was more effective than NIF. A significant decrease in serum calcium was found only in animals treated with CsA or CsA/NIF. The results were similar regardless of age.

CONCLUSIONS

These results indicate that the decrease in the alveolar bone volume in rats caused by CsA and NIF alone or concurrently is not age dependent. Furthermore, NIF (50 mg/kg) did not further increase the loss of alveolar bone volume induced by CsA (10 mg/kg).

Drug immunosuppression therapy for adult heart transplantation. Part 1: immune response to allograft and mechanism of action of immunosuppressants

In the early days of transplantation, immunosuppression therapy was rather broad and nonspecific, mainly using high-dose corticosteroids and azathioprine. Thereafter we progressively narrowed the target of immunosuppressive strategy starting with polyclonal antibodies. The introduction of cyclosporine, OKT3, and tacrolimus further narrowed the target on the T-cell pathways. More recently mycophenolate mofetil progressively took the place of azathioprine with its higher lymphocyte specificity and sirolimus and interleukin-2 receptor antibodies were introduced. In this field in constant movement the aim is to find a drug or a regimen that provides optimal immunosuppression therapy with minimal side effects, in other words to find the right balance between overimmunosuppression and underimmunosuppression therapy. This review is divided into two parts. The first part will provide a basic understanding of the immunologic response to allograft and explain how conventional and recently introduced immunosuppressive agents work. The second part will describe the clinical application of immunosuppressive drugs to provide practical information for those in charge of heart transplant recipients.

Calcineurin inhibitors in renal transplantation: what is the best option?

Recently, new calcineurin inhibitors, such as tacrolimus (FK-506) and microemulsion cyclosporin, have been approved for maintenance immunosuppression in renal transplant recipients and short-term outcomes have been accumulating. In the majority of patients, these calcineurin inhibitors have been used in combination with new immunosuppressive drugs, such as mycophenolate mofetil (MMF) or sirolimus. Under these circumstances, a comparison of cyclosporin and tacrolimus provides the answer to a very important controversial issue. Which drug should we choose in individual patients? In an attempt to answer this question, this review compared the use of tacrolimus and cyclosporin in modern immunosuppressive regimens, which have already been published in well designed clinical studies, and discusses how immunosuppression should be individualised in renal transplant patients.Overall, short-term patient and graft survival with cyclosporin microemulsion and tacrolimus is almost identical. The incidence of acute rejection is generally lower in tacrolimus/azathioprine- than in cyclosporin/azathioprine-treated patients. However, in conjunction with MMF, the difference in the incidence of acute rejection between tacrolimus- and cyclosporin-treated patients became smaller. Adverse events, such as hypertension, hyperlipidaemia and cosmetic changes (gum hypertrophy, hirsutism) seem to be less frequent in tacrolimus-treated than in cyclosporin-treated patients. Recent randomised studies showed that the incidence of post-transplant diabetes mellitus was almost identical between low-dose tacrolimus- and cyclosporin-treated patients. According to the data discussed in this review, the recommendation on the choice of calcineurin inhibitors at this moment is that either cyclosporin or tacrolimus can be used safely and effectively for patients without any risk factors. However, at our centre, we prefer tacrolimus to cyclosporin in patients with a high risk for rejection, such as those with ABO-incompatibility, delayed graft function, sensitisation, and African American race and some other risk factors, such as hypertension and hyperlipidaemia. Moreover, tacrolimus may be preferable to cyclosporin for women because of hirsutism and for children because of the steroid-sparing effect. We consider that cyclosporin should be chosen when patients experience tacrolimus-related adverse events, such as severe chest pain, tremor, gastrointestinal symptoms and encephalopathy. In conclusion, well tolerated and effective immunosuppression is feasible with both cyclosporin and tacrolimus. In the current immunosuppressive regimens, a calcineurin inhibitor, either tacrolimus or cyclosporin, is the essential basic standard immunosuppressant. Clinicians need to decide the best means of optimising therapy for individual patients, based on various risk factors, such as risk of rejection, i.e. sensitisation, delayed graft function and ABO-incompatibility, and some adverse events, such as hypertension, hyperlipidaemia and cosmetic changes.

Cyclosporine nephrotoxicity

After more than 20 years of cyclosporine use its nephrotoxicity remains a significant clinical problem. Cyclosporine-induced renal injury has been described in solid organs recipients and in patients treated for autoimmune diseases. It is manifested in 2 distinct and well characterized forms, acute nephrotoxicity and chronic nephrotoxicity. This communication reviews the current literature analyzing the available data about the pathogenesis and mechanisms of acute and chronic cyclosporine-induced nephrotoxicity. A working hypothesis for the possible mechanisms of chronic cyclosporine nephrotoxicity will be provided.

Calcium channel blockers as the treatment of choice for hypertension in renal transplant recipients: fact or fiction

Posttransplantation hypertension has been identified as an independent risk factor for chronic allograft dysfunction and loss. Based on available morbidity and mortality data, posttransplantation hypertension must be identified and managed appropriately. During the past decade, calcium channel blockers have been recommended by some as the antihypertensive agents of choice in this population, because it was theorized that their vasodilatory effects would counteract the vasoconstrictive effects of the calcineurin inhibitors. With increasing data becoming available, reexamining the use of traditional antihypertensive agents, including diuretics and beta-blockers, or the newer agents, angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers, may be beneficial. Transplant clinicians must choose antihypertensive agents that will provide their patients with maximum benefit, from both a renal and a cardiovascular perspective. Beta-blockers, diuretics, and ACE inhibitors have all demonstrated significant benefit on morbidity and mortality in patients with cardiovascular disease. Calcium channel blockers have been shown to possess the ability to counteract cyclosporine-induced nephrotoxicity. When compared with beta-blockers, diuretics, and ACE inhibitors, however, the relative risk of cardiovascular events is increased with calcium channel blockers. With the long-term benefits of calcium channel blockers on the kidney unknown and a negative cardiovascular profile, these agents are best reserved as adjunctive therapy to beta-blockers, diuretics, and ACE inhibitors.

Treatment of hypertension in renal transplant recipients

PURPOSE OF REVIEW

Hypertension is very common in renal transplant recipients and is a significant risk factor for mortality from cardiovascular diseases and for development of graft dysfunction.

RECENT FINDINGS

Recent guidelines for the treatment of hypertension (Joint National Committee on Prevention, Detection, and Treatment of High Blood Pressure VI Report and World Health Organization Guidelines) do not directly address post-transplant hypertension. Specific recommendations for the drug treatment of hypertension in renal allograft recipients have not been given in the Clinical Practice Guidelines of the American Society of Transplantation or those of the European Renal Association.

SUMMARY

The present paper summarizes some important aspects of post-transplant hypertension and discusses potential treatment strategies aimed at reducing blood pressure and thus improving patient and allograft survival.

Immunosuppressive therapy for paediatric transplant patients: pharmacokinetic considerations

Immunosuppressive therapy in paediatric transplant recipients is changing as a consequence of the increasing number of available immunosuppressive agents. Generic and other new formulations are now emerging onto the market, clinical experience is growing, and it is expected that clinicians should tailor immunosuppressive protocols to individual patients by optimising dosages and drugs according to the maturation and clinical status of the child. Most information about the clinical pharmacokinetics of immunosuppressive drugs in paediatrics is centred on cyclosporin, tacrolimus and mycophenolate mofetil in renal and liver transplant recipients; data regarding other immunosuppressants and transplant types are limited. Although the clinical pharmacokinetics of these drugs in paediatric transplant recipients are still under investigation, it is evident that the pharmacokinetic parameters observed in adults may not be applicable to children, especially in younger age groups. In general, patients younger than 5 years old show higher clearance rates irrespective of the organ transplanted or drug used. Another important factor that frequently affects clearance in this patient population is the post-transplant time. In accordance with these findings, and in contrast with the usual under-dosage in children, the need for higher dosages in younger recipients and during the early post-transplant period seems evident. To achieve the best compromise between prevention of rejection and toxicity, dosage individualisation is required and this can be achieved through therapeutic drug monitoring (TDM). This approach is particularly useful to ensure the cost-effective management of paediatric transplant recipients in whom the pharmacokinetic behaviour, target concentrations for clinical use and optimal dosage strategies of a particular drug may not yet be well defined. Although TDM may be a tool for improving immunosuppressive therapy, there is little information concerning its positive contribution to clinical events, including outcomes, for paediatric patients. Substantial information to support the use of TDM exists for cyclosporin and, to a lesser extent, for tacrolimus, but a diversity of options affects their implementation in the clinical setting. The role of TDM in therapy with mycophenolate mofetil and sirolimus has yet to be defined regarding both methods and clinical indications. Pharmacodynamic monitoring appears more suited to other immunosuppressants such as azathioprine, corticosteroids and monoclonal or polyclonal antibodies. If coupled with pharmacokinetic measurements, such monitoring would allow earlier and more precise optimisation of therapy. Very few population pharmacokinetic studies have been carried out in paediatric transplant patients. This type of study is needed so that techniques such as Bayesian forecasting can be applied to optimise immunosuppressive therapy in paediatric transplant patients.

Immunisations in solid-organ transplant recipients

Solid-organ transplant recipients are at increased risk of various infectious diseases, some of which are vaccine preventable mmunisations are among the most efficient interventions available. Solid-organ tranplant recipients would greatly benefit from effective immunisations, provided the recommendations are based on a careful risk-benefit analysis in which the effectiveness of the vaccine is weighed against possible adverse reactions, including graft rejection. In this review, we summarise the data from studies on relevant immunisations in solid-organ transplant recipients. The major issues are the immunogenicity and safety of immunisations, the factors associated with poor immune response, and recommendations for immunisation schemes.

Nephrotoxicity of immunosuppressive drugs: new insight and preventive strategies

Cyclosporine and tacrolimus reduce allograft rejection, improve allograft half-life and patient survival. Ironically, the nephrotoxicity of these agents may adversely affect allograft survival in renal transplant recipients or cause end-stage renal diseases in other solid organ and bone marrow transplant recipients. Acute dose-dependent and chronic non-dose-dependent nephrotoxicity has been reported in both transplant recipients and patients with autoimmune disorders. Preliminary evidence suggests that drug therapeutic monitoring has little value in the diagnosis or management of nephrotoxicity associated with calcineurin inhibitors. Although the exact mechanism of nephrotoxicity is not fully understood, several factors have been implicated in the pathogenesis of immunosuppressive-induced nephrotoxicity. Renal and systemic vasoconstriction, increased release of endothelin-1, decreased production of nitric acid and increased expression of TGF-beta are the major adverse pathophysiologic abnormalities of these agents. Reducing the dose of a calcineurin inhibitor, or using protocols without calcineurin inhibition may ultimately minimize the risk of drug toxicity and improve allograft and patient survival. New experiences with non-nephrotoxic agents and protocols including mycophenolate and sirolimus allow for early calcineurin inhibitor reduction or elimination without increasing the risk of allograft rejection.

Reactivation of tuberculosis after conversion from azathioprine to mycophenolate mofetil 16 years after renal transplantation

The incidence of tuberculosis among transplant recipients is greater than in the general population. Mycophenolate mofetil (MMF) is a potent immunosuppressive agent that has become part of most standard immunosuppressive protocols after renal transplantation. We have recently shown that conversion from azathioprine (AZA) to MMF in patients with chronic allograft dysfunction may be beneficial. Here, we report a patient with a history of pulmonary tuberculosis during his childhood. This patient was converted from AZA to MMF therapy 16 years after allogenic renal transplantation because of chronic allograft dysfunction. Two months later, he developed axillary lymph node tuberculosis caused by Mycobacterium tuberculosis. Because he denied contact with infectious persons, we diagnosed reactivation of old dormant tuberculosis. After surgical extirpation, quadruple antituberculous therapy was administered for 3 months (isoniazid, rifampicin, ethambutol, and pyrazinamide), followed by dual therapy for 3 months (isoniazid and rifampicin), and monotherapy for another 3 months (isoniazid). In the follow-up period, he remained asymptomatic with stable graft function. We conclude that MMF therapy in renal allograft recipients may cause reactivation of old dormant tuberculosis, even in the very late posttransplantation period. In these patients, close monitoring and isoniazid prophylaxis may be useful.

Immunosuppressant-induced nephropathy: pathophysiology, incidence and management

Immunosuppressant-induced nephrotoxicity, in particular chronic progressive tubulointerstitial fibrosis/arteriopathy induced by the calcineurin inhibitors cyclosporin and tacrolimus, has become the 'Achilles heel' of immunosuppressive agents. The use of calcineurin inhibitors as primary immunosuppressants in hepatic and cardiac transplantation has led to end-stage renal disease and dialysis. Calcineurin inhibitor-induced acute renal failure may occur as early as a few weeks or months after initiation of cyclosporin therapy. The clinical manifestations of acute renal dysfunction are caused by vasoconstriction of renal arterioles, and include reduction in glomerular filtration rate, hypertension, hyperkalaemia, tubular acidosis, increased reabsorption of sodium and oliguria. The acute adverse effects of calcineurin inhibitors on renal haemodynamics are thought to be directly related to the cyclosporin or tacrolimus dosage and blood concentration. However, new clinical data indicate that calcineurin inhibitor-induced chronic nephropathy can occur independently of acute renal dysfunction, cyclosporin dosage or blood concentration. Several strategies have been evaluated to attenuate cyclosporin-induced nephropathy, but their efficacy remains unknown. Cytokine release syndrome associated with the use of muronomab-CD3 (OKT-3) can also contribute to the pathogenesis of transient acute tubular necrosis and renal dysfunction following renal transplantation. Continued research and clinical experience should provide information regarding the aetiology of cyclosporin-induced chronic progressive tubulointerstitial fibrosis/arteriopathy and its potential treatment.

Increased risk of fracture in patients receiving solid organ transplants

The success of organ transplantation is related to advances in immunosuppressive therapy. These medications are associated with medical complications including bone damage. The objective of this study was to estimate and compare age, gender-specific fracture incidence between transplant recipients, and a large sample representative of the civilian noninstitutionalized United States population using the 1994 National Health Interview Survey (NHIS). This was a cohort study set in tertiary care centers. Five hundred and thirty-nine individuals who received abdominal organ and 61 heart transplants surviving at least 30 days at our institution from 1986 to 1996 were included in the study. Incident fractures were ascertained by mail, in-person interview, telephone survey, or medical record review. All fractures were verified. Organ-, age-, and gender-specific fracture numbers and rates and person-years of observation, were calculated for the transplant patients. Weighted age- and gender-specific fracture rates from the 1994 NHIS were applied to the number of person-years of observation for each organ-specific age and gender category of transplant patients to generate an expected number of fractures. The ratio of observed to expected number of fractures was used to compare fracture experience of transplant patients to that of the national sample from the 1994 NHIS. Fifty-six of 600 (9.3%) patients had at least one fracture following 1221 person-years of observation. The sites of initial symptomatic fracture were as follows: foot (n = 22), arm (n = 8), leg (n = 7), ribs (n = 6), hip (n = 4), spine (n = 3), fingers (n = 3), pelvis (n = 2), and wrist (n = 1). Fracture incidence was 13 times higher than expected in male heart recipients age 45-64 years; nearly 5 times higher in male kidney recipients age 25-44 and age 45-64 years; and 18 times and 34 times higher in female kidney recipients age 25-44 years and 45-64 years compared with NHIS data. We have shown an increased incidence of fractures and estimated the magnitude of this problem in patients undergoing solid organ transplantation. Our work defines the need for a long-term prospective study of fracture risk in these patients.

A randomized active-controlled trial of mycophenolate mofetil in heart transplant recipients. Mycophenolate Mofetil Investigators

BACKGROUND

After heart transplantation, 1-year and 5-year survival rates are 79% and 63%, respectively, with rejection, infection, and allograft coronary artery disease accounting for the majority of deaths. Mycophenolate mofetil (MMF), an inhibitor of the de novo pathway for purine biosynthesis, decreases rejection in animals and in human renal transplantation.

METHODS

In a double-blind, active-controlled trial, 28 centers randomized 650 patients undergoing their first heart transplant to receive MMF (3000 mg/day) or azathioprine (1.5-3 mg/kg/day), in addition to cyclosporine and corticosteroids. Rejection and survival data were obtained for 6 and 12 months, respectively. Because 11% of the patients withdrew before receiving study drug, data were analyzed on all randomized patients (enrolled patients) and on patients who received study medications (treated patients).

RESULTS

Survival and rejection were similar in enrolled patients (MMF, n=327; azathioprine, n=323). In treated patients (MMF, n=289; azathioprine, n=289), the MMF group compared with the azathioprine group was associated with significant reduction in mortality at 1 year (18 [6.2%] versus 33 deaths [11.4%]; P=0.031) and a significant reduction in the requirement for rejection treatment (65.7% versus 73.7%; P=0.026). There was a trend for fewer MMF patients to have > or = grade 3A rejection (45.0% versus 52.9%; P=0.055) or require the murine monoclonal anti-CD3 antibody or antithymocyte globulin (15.2% versus 21.1%; P=0.061). Opportunistic infections, mostly herpes simplex, were more common in the MMF group (53.3% versus 43.6%; P=0.025).

CONCLUSIONS

Substitution of MMF for azathioprine may reduce mortality and rejection in the first year after cardiac transplantation.

Interaction between tacrolimus and chloramphenicol in a renal transplant recipient

BACKGROUND

The metabolism of tacrolimus is influenced by several medications when they are given concurrently. We report the interaction between tacrolimus and chloramphenicol in a renal transplant recipient.

METHODS

An adolescent with vancomycin-resistant Enterococcus was given standard doses of chloramphenicol. Tacrolimus trough levels increased, and the dose was adjusted to maintain the target trough level. Pharmacokinetic studies were obtained during chloramphenicol administration and 14 days after its discontinuation.

RESULTS

Toxic levels of tacrolimus were seen on the second day of chloramphenicol administration, requiring an 83% reduction in the tacrolimus dose. The dose-adjusted area under the curve value for tacrolimus was 7.5-fold greater while the patient was on chloramphenicol. These data are consistent with inhibition of tacrolimus clearance by chloramphenicol

CONCLUSIONS

Chloramphenicol interferes with tacrolimus metabolism. Careful monitoring of tacrolimus trough levels during concomitant chloramphenicol therapy is recommended to avoid toxicity.

Prevention of transplant rejection: current treatment guidelines and future developments

In the past 2 decades, progressive improvements in the results of organ transplantation as a therapeutic strategy for patients with end-stage organ disease have been achieved due to greater insight into the immunobiology of graft rejection and better measures for surgical and medical management. It is now known that T cells play a central role in the specific immune response of acute allograft rejection. Strategies to prevent T cell activation or effector function are thus all potentially useful for immunosuppression. Standard immunosuppressive therapy in renal transplantation consists of baseline therapy to prevent rejection and short courses of high-dose corticosteroids or monoclonal or polyclonal antibodies as treatment of ongoing rejection episodes. Triple-drug therapy with the combination of cyclosporin, corticosteroids and azathioprine is now the most frequently used immunosuppressive drug regimen in cadaveric kidney recipients. The continuing search for more selective and specific agents has become, in the past decade, one of the priorities for transplant medicine. Some of these compounds are now entering routine clinical practice: among them are tacrolimus (which has a mechanism of action similar to that of cyclosporin), mycophenolate mofetil and mizoribine (which selectively inhibit the enzyme inosine monophosphate dehydrogenase, the rate-limiting enzyme for de novo purine synthesis during cell division), and sirolimus (rapamycin) [which acts on and inhibits kinase homologues required for cell-cycle progression in response to growth factors, like interleukin-2 (IL-2)]. Other new pharmacological strategies and innovative approaches to organ transplantation are also under development. Application of this technology will offer enormous potential not only for the investigation of mechanisms and mediators of graft rejection but also for therapeutic intervention.

Cyclosporine and tacrolimus: the mainstay of immunosuppressive therapy for solid organ transplantation

Orthotopic liver transplant is the only cure for end stage liver disease. Enormous progress has been made in the fields of graft and patient survival since the introduction of cyclosporine and tacrolimus. Scientists involved in basic and clinical research have dedicated their efforts to understanding the mechanisms of action and the side effects of these medications with the goal of finding the perfect balance between the well-being of the patient and the avoidance of rejection. A great deal of work has been done and now we can propose a variety of treatments suitable to different clinical scenarios. The introduction of new medications will offer even more options for the treatment of rejection in liver transplant patients.

Switching between cyclosporin formulations. What are the risks?

The introduction of cyclosporin, refinement in surgical techniques and improvement in allograft preservation have all led to an improvement in graft and ultimately patient survival. Cyclosporin is a lipophilic cyclic polypeptide produced by Trichoderma, a fungus isolated from Norwegian soil. Cyclosporin is a potent, selective and powerful immunosuppressive agent possessing a narrow therapeutic window. Substitution among different formulations of cyclosporin for economic reasons, without close monitoring of pharmacokinetics and pharmacodynamics, can induce undesirable toxic effects. A number of recent reports, largely anecdotal, of adverse drug reactions and acute cellular rejection after conversion from the standard formulation to the microemulsion formulation of cyclosporin have created uncertainty over the therapeutic equivalency of these agents. This leading article reviews the pharmacology, pharmacokinetics and adverse drug reactions of cyclosporin as well as the potential risks associated with switching between cyclosporin formulations in stable renal transplant recipients. Caution should be employed when switching between cyclosporin formulations. Since data are limited, long-term prospective studies are necessary to delineate the role of high peak concentrations obtained from the microemulsion formulation in relation to cyclosporin-induced chronic nephropathy. The significance of the reduction in pharmacokinetic variability with use of the microemulsion formulation in terms of graft and patient survival remains unclear.