Immunosuppressant-induced nephropathy: pathophysiology, incidence and management

Disorders of potassium homeostasis after kidney transplantation

Disturbances of potassium balance are often encountered when managing kidney transplant recipients (KTR). Both hyperkalemia and hypokalemia may present either as medical emergencies or chronic outpatient abnormalities. Despite the high incidence of hyperkalemia and its potential life-threatening implications, consensus on its management in KTR is lacking. Hypokalemia in KTR is also well-described, although it is given less attention by clinicians compared to hyperkalemia. This article discusses the etiology, pathophysiology and management of both types of potassium disorders in KTR. Once any emergent situation has been corrected, treatment approaches include correcting insulin deficiency if present, adjusting non-immunosuppressive and immunosuppressive medications, eliminating or supplementing potassium as needed, and dietary counselling. Although commonly of multifactorial etiology, ascertaining the specific cause in a particular patient will help guide successful management. Monitoring KTR through regular laboratory testing is essential to detect serious disturbances in potassium balance since patients are often asymptomatic.

Peritransplant Renal Dysfunction in Liver Transplant Candidates

Renal function is intricately tied to Model for End-Stage Liver Disease score and overall prognosis among patients with cirrhosis. The estimation of glomerular filtration rate (GFR) and etiology of renal impairment are even more magnified among cirrhotic patients in the period surrounding liver transplantation. Novel biomarkers including cystatin C and urinary neutrophil gelatinase-associated lipocalin have been demonstrated to more accurately assess renal dysfunction and aid in the diagnosis of competing etiologies. Accurately identifying the severity and chronicity of renal dysfunction among transplant candidates is an imperative component with respect to stratifying patients toward simultaneous liver-kidney transplantation versus liver transplantation alone.

Reducing Adverse Effects of Immunosuppressive Agents in Kidney Transplant Recipients

Success in solid organ transplantation with minimal complications can now be achieved for most patients, and a remarkable rate of graft and patient survival can also be expected. However, the potential for adverse events and comorbid conditions increases with longer graft survival. Although the immunosuppressive regimen is central to the outcome of the transplant recipient and directly impacts the survival of the graft, chronic use of immunosuppressive agents is associated with metabolic disturbances such as hypertension, hyperlipidemia, loss of bone density, nephrotoxicity, and diabetes, which may contribute to other comorbid conditions. In addition, changes in appearance, gingival hyperplasia, hirsutism, alopecia, and weight gain disrupt quality of life and may lead to noncompliance with the immunosuppressive regimen. New immunosuppressive medications, including mycophenolate mofetil, sirolimus, basiliximab, and daclizumab, have allowed for experimentation with new regimens designed to reduce or allow discontinuation of corticosteroids and calcineurin inhibitors. This review highlights the impact and cost of immunosuppressive side effects and the potential for new immunosuppressive regimens to reduce this substantial clinical burden in transplantation.

THE PURVIEW OF PHYTOTHERAPY IN THE MANAGEMENT OF KIDNEY DISORDERS: A SYSTEMATIC REVIEW ON NIGERIA AND SOUTH AFRICA

BACKGROUND

The kidney is tasked with a number of metabolic functions in the body. In its role as a detoxifier and primary eliminator of xenobiotics, it becomes vulnerable to developing injuries. Currently, over 1 million people in the world are living on renal replacement therapies (RRTs). The case in sub-Sahara African countries like Nigeria and South Africa is not any better than the global trend.

MATERIALS AND METHODS

A systematic review of medicinal plants used in the treatment of kidney disorders was conducted. Information were gathered from published scientific journals, books, reports from national, regional and international institutions, conference proceedings and other high profile intellectual resources. MeSH words like 'prevalence of kidney disorders in Africa', 'renal replacement therapy', 'nephrotoxins or nephrotoxicants', 'nephroprotective plants', 'nephroprotective plants in Nigeria or South Africa' and 'nephroprotective phytocompounds' were used to retrieve information from online databases (Google, Pubmed, MEDLINE, Science Direct, Scopus and SID).

RESULTS

Interestingly, our findings revealed that phytotherapy has emerged and is being employed to protect renal functions and delay progression of renal pathological conditions into end episodes where the last resort is RRT. In fact, in recent times, Phytotherapists are not only interested in developing relatively safe, more affordable, easily accessible and potent nephroprotective formulations but also increasing awareness on the prevalence of the disease and educating the populace on the probable preventive measures. More importantly, efforts at scientifically elucidating the pharmacological efficacy of the identified nephroprotective plants yet to be validated must be intensified through informed expert opinions. Till date, there is paucity of information on the concept of nephroprotection in most developing countries where kidney disorder is a major threat. Although, the concept is just emerging in South Africa, evidences have given credence to its application in complementary and alternative system of medicine in Nigeria.

CONCLUSION

This review, therefore, reawaken researchers' consciousness in the continuous search for auspicious nephroprotective plants that could potentially be excellent candidates in developing new lead drugs to manage and treat renal disorders.

Incidence and risk factors for early renal dysfunction after liver transplantation

AIM: To determine renal dysfunction post liver transplantation, its incidence and risk factors in patients from a Belgian University Hospital.

METHODS: Orthotopic liver transplantations performed from January 2006 until September 2012 were retrospectively reviewed (n = 187). Patients with no renal replacement therapy (RRT) before transplantation were classified into four groups according to their highest creatinine plasma level during the first postoperative week. The first group had a peak creatinine level below 12 mg/L, the second group between 12 and 20 mg/L, the third group between 20 and 35 mg/L, and the fourth above 35 mg/L. In addition, patients who needed RRT during the first week after transplantation were also classified into the fourth group. Perioperative parameters were recorded as risk factors, namely age, sex, body mass index (BMI), length of preoperative hospital stay, prior bacterial infection within one month, preoperative ascites, preoperative treatment with β-blocker, angiotensin-converting enzyme inhibitor or non steroidal anti-inflammatory drugs, preoperative creatinine and bilirubin levels, donor status (cardiac death or brain death), postoperative lactate level, need for intraoperative vasopressive drugs, surgical revision, mechanical ventilation for more than 24 h, postoperative bilirubin and transaminase peak levels, postoperative hemoglobin level, amount of perioperative blood transfusions and type of immunosuppression. Univariate and multivariate analysis were performed using logistic ordinal regression method. Post hoc analysis of the hemostatic agent used was also done.

RESULTS: There were 78 patients in group 1 (41.7%), 46 in group 2 (24.6%), 38 in group 3 (20.3%) and 25 in group 4 (13.4%). Twenty patients required RRT: 13 (7%) during the first week after transplantation. Using univariate analysis, the severity of renal dysfunction was correlated with presence of ascites and prior bacterial infection, preoperative bilirubin, urea and creatinine level, need for surgical revision, use of vasopressor, postoperative mechanical ventilation, postoperative bilirubin and urea, aspartate aminotransferase (ASAT), and hemoglobin levels and the need for transfusion. The multivariate analysis showed that BMI (OR = 1.1, P = 0.004), preoperative creatinine level (OR = 11.1, P < 0.0001), use of vasopressor (OR = 3.31, P = 0.0002), maximal postoperative bilirubin level (OR = 1.44, P = 0.044) and minimal postoperative hemoglobin level (OR = 0.059, P = 0.0005) were independent predictors of early post-liver transplantation renal dysfunction. Neither donor status nor ASAT levels had significant impact on early postoperative renal dysfunction in multivariate analysis. Absence of renal dysfunction (group 1) was also predicted by the intraoperative hemostatic agent used, independently of the extent of bleeding and of the preoperative creatinine level.

CONCLUSION: More than half of receivers experienced some degree of early renal dysfunction after liver transplantation. Main predictors were preoperative renal dysfunction, postoperative anemia and vasopressor requirement.

Drug-related acute renal failure in hospitalised patients

INTRODUCTION

The information available on the incidence and the characteristics of patients with acute renal failure (ARF) related to drugs is scarce.

OBJECTIVES

To estimate the incidence of drug-related ARF in hospitalised patients and to compare their characteristics with those of patients with ARF due to other causes.

MATERIAL AND METHODS

We selected a prospective cohort of patients with ARF during hospital admission (July 2010-July 2011). Information on patients' demographics, medical antecedents, ARF risk factors, ARF severity according to the RIFLE classification and hospital drug administration was collected. We analysed the relationship of drugs with the ARF episodes using Spanish Pharmacovigilance System methods and algorithm.

RESULTS

A total of 194 cases had an episode of hospital-acquired ARF. The median age of patients was 72 years [IQR 20]; 60% were men. The ARF incidence during hospitalization was 9.6 per 1,000 admissions. According to the RIFLE classification, a risk of kidney damage or kidney injury was present in 77.8% of cases. In 105 (54.1%) cases, ARF was drug-related; the drugs most frequently involved were diuretics, agents acting on the renin-angiotensin system, immunosuppressants, β-blocking agents, calcium channel blockers, contrast media and non-steroid anti-inflammatory drugs. Patients with drug-related ARF had more multi-morbidity, fewer ARF risk factors and lower mortality.

CONCLUSIONS

Half of ARF episodes during hospitalisation were drug related. Patients with drug-related ARF had higher cardiovascular morbidity than those with ARF related to other causes, but they had a lower frequency of ARF risk factors and mortality.

Renal Deletion of 12 kDa FK506-Binding Protein Attenuates Tacrolimus-Induced Hypertension

Tacrolimus is a widely used immunosuppressive drug that inhibits the phosphatase calcineurin when bound to the 12 kDa FK506-binding protein (FKBP12). When this binding occurs in T cells, it leads to immunosuppression. Tacrolimus also causes side effects, however, such as hypertension and hyperkalemia. Previously, we reported that tacrolimus stimulates the renal thiazide-sensitive sodium chloride cotransporter (NCC), which is necessary for the development of hypertension. However, it was unclear if tacrolimus-induced hypertension resulted from tacrolimus effects in renal epithelial cells directly or in extrarenal tissues, and whether inhibition of calcineurin was required. To address these questions, we developed a mouse model in which FKBP12 could be deleted along the nephron. FKBP12 disruption alone did not cause phenotypic effects. When treated with tacrolimus, however, BP and the renal abundance of phosphorylated NCC were lower in mice lacking FKBP12 along the nephron than in control mice. Mice lacking FKBP12 along the nephron also maintained a normal relationship between plasma potassium levels and the abundance of phosphorylated NCC with tacrolimus treatment. In cultured cells, tacrolimus inhibited dephosphorylation of NCC. Together, these results suggest that tacrolimus causes hypertension predominantly by inhibiting calcineurin directly in cells expressing NCC, indicating thiazide diuretics may be particularly effective for lowering BP in tacrolimus-treated patients with hypertension.

ABCB1 genetic variant and its associated tacrolimus pharmacokinetics affect renal function in patients with rheumatoid arthritis

BACKGROUND

This study aimed to evaluate the blood exposure of and clinical responses to tacrolimus based on genetic variants of CYP3A5 and ABCB1 in patients with rheumatoid arthritis.

METHODS

Seventy rheumatoid arthritis patients treated with oral tacrolimus once daily were enrolled. Blood concentrations of tacrolimus and its major metabolite 13-O-demethylate at 12h after dosing were determined. The relationships between the tacrolimus pharmacokinetics and efficacy, renal function, and CYP3A5 and ABCB1 genotypes were evaluated.

RESULTS

Dose-normalized blood concentration of tacrolimus was significantly higher in the CYP3A5*3/*3 group than in the *1 allele carrier group. A lower metabolic ratio of 13-O-demethylate to tacrolimus was observed in the CYP3A5*3/*3 group. The ABCB1 3435TT group had higher dose-normalized blood concentrations of tacrolimus and 13-O-demethylate. The blood tacrolimus concentration was inversely correlated with the estimated glomerular filtration rate (eGFR). ABCB1 C3435T but not CYP3A5 genotype had decreased eGFR. Patients lacking the CYP3A5*3 allele had a higher incidence of tacrolimus withdrawal.

CONCLUSION

CYP3A5*3 increased the blood exposure of tacrolimus through its metabolic reduction. ABCB1 C3435T led to a higher blood exposure of tacrolimus and its major metabolite. The ABCB1 genetic variant and its associated tacrolimus pharmacokinetics affected renal function in rheumatoid arthritis patients.

Celecoxib, but not indomethacin, ameliorates the hypertensive and perivascular fibrotic actions of cyclosporine in rats: role of endothelin signaling

The immunosuppressant drug cyclosporine (CSA) is used with nonsteroidal antiinflammatory drugs (NSAIDs) in arthritic conditions. In this study, we investigated whether NSAIDs modify the deleterious hypertensive action of CSA and the role of endothelin (ET) receptors in this interaction. Pharmacologic, protein expression, and histopathologic studies were performed in rats to investigate the roles of endothelin receptors (ETA/ETB) in the hemodynamic interaction between CSA and two NSAIDs, indomethacin and celecoxib. Tail-cuff plethysmography measurements showed that CSA (20 mg kg(-1) day(-1), 10 days) increased systolic blood pressure (SBP) and heart rate (HR). CSA hypertension was associated with renal perivascular fibrosis and divergent changes in immunohistochemical signals of renal arteriolar ETA (increases) and ETB (decreases) receptors. While these effects of CSA were preserved in rats treated concomitantly with indomethacin (5 mg kg(-1) day(-1)), celecoxib (10 mg kg(-1) day(-1)) abolished the pressor, tachycardic, and fibrotic effects of CSA and normalized the altered renal ETA/ETB receptor expressions. Selective blockade of ETA receptors by atrasentan (5 mg kg(-1) day(-1)) abolished the pressor response elicited by CSA or CSA plus indomethacin. Alternatively, BQ788 (ETB receptor blocker, 0.1 mg kg(-1) day(-1)) caused celecoxib-sensitive elevations in SBP and potentiated the pressor response evoked by CSA. Together, the improved renovascular fibrotic and endothelin receptor profile (ETA downregulation and ETB upregulation) mediate, at least partly, the protective effect of celecoxib against the hypertensive effect of CSA. Clinically, the use of celecoxib along with CSA in the management of arthritic conditions might provide hypertension-free regimen.

Recalcitrant hypocalcaemia in autoimmune enteropathy

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome is a monogenic disorder associated with autoimmune destruction of both endocrine and nonendocrine tissues. The classic triad includes candidiasis, hypoparathyroidism, and Addison disease. Up to 25% of patients with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy syndrome also have gastrointestinal manifestations, which can have an impact on the management of other aspects of the disease. The management of the case discussed was challenging because of the complex interplay between the manifestations and treatment of his hypoparathyroidism, Addison disease, and autoimmune enteropathy. Attempts at management of hypocalcemia were largely unsuccessful until the introduction of immunosuppressive therapy for autoimmune enteropathy. This case supports early consideration of immunosuppression in this condition.

Drug-induced nephrotoxicity and its biomarkers

Nephrotoxicity occurs when kidney-specific detoxification and excretion do not work properly due to the damage or destruction of kidney function by exogenous or endogenous toxicants. Exposure to drugs often results in toxicity in kidney which represents the major control system maintaining homeostasis of body and thus is especially susceptible to xenobiotics. Understanding the toxic mechanisms for nephrotoxicity provides useful information on the development of drugs with therapeutic benefi ts with reduced side effects. Mechanisms for drug-induced nephrotoxicity include changes in glomerular hemodynamics, tubular cell toxicity, inflammation, crystal nephropathy, rhabdomyolysis, and thrombotic microangiopathy. Biomarkers have been identifi ed for the assessment of nephrotoxicity. The discovery and development of novel biomarkers that can diagnose kidney damage earlier and more accurately are needed for effective prevention of drug-induced nephrotoxicity. Although some of them fail to confer specificity and sensitivity, several promising candidates of biomarkers were recently proved for assessment of nephrotoxicity. In this review, we summarize mechanisms of drug-induced nephrotoxicity and present the list of drugs that cause nephrotoxicity and biomarkers that can be used for early assessment of nephrotoxicity.

Celecoxib offsets the negative renal influences of cyclosporine via modulation of the TGF-β1/IL-2/COX-2/endothelin ET(B) receptor cascade

Endothelin (ET) signaling provokes nephrotoxicity induced by the immunosuppressant drug cyclosporine A (CSA). We tested the hypotheses that (i): celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, counterbalances renal derangements caused by CSA in rats and (ii) the COX-2/endothelin ET(B) receptor signaling mediates the CSA-celecoxib interaction. Ten-day treatment with CSA (20 mg/kg/day) significantly increased biochemical indices of renal function (serum urea, creatinine), inflammation (interleukin-2, IL-2) and fibrosis (transforming growth factor-β₁, TGF-β₁). Histologically, CSA caused renal tubular atrophy along with interstitial fibrosis. These detrimental renal effects of CSA were largely reduced in rats treated concurrently with celecoxib (10 mg/kg/day). We also report that cortical glomerular and medullary tubular protein expressions of COX-2 and ET(B) receptors were reduced by CSA and restored to near-control values in rats treated simultaneously with celecoxib. The importance of ET(B) receptors in renal control and in the CSA-celecoxib interaction was further verified by the findings (i) most of the adverse biochemical, inflammatory, and histopathological profiles of CSA were replicated in rats treated with the endothelin ETB receptor antagonist BQ788 (0.1 mg/kg/day, 10 days), and (ii) the BQ788 effects, like those of CSA, were alleviated in rats treated concurrently with celecoxib. Together, the data suggest that the facilitation of the interplay between the TGF-β1/IL-2/COX-2 pathway and the endothelin ET(B) receptors constitutes the cellular mechanism by which celecoxib ameliorates the nephrotoxic manifestations of CSA in rats.

Glomerular and tubular function following orthotopic liver transplantation in children treated with tacrolimus

The aim of this study was to analyze the impact of TAC on medium term (three-yr follow-up) renal function in pediatric liver transplant (OLT) recipients. Glomerular and tubular indices were retrospectively analyzed in 24 consecutive OLT pediatric recipients on TAC. CrCl increased significantly each month post-OLT (p = 0.003), with a trend toward significance between pre-OLT and 36 months (p = 0.17). There was no correlation between CrCl and TAC troughs (p = 0.783). Sixteen percent of patients had CrCl <60 mL/min/1.73 m(2) pre-OLT vs. none at 36 months post-OLT. TRP values were normal throughout the study. UPr/Cr decreased insignificantly over time and correlated significantly with TAC trough levels (p = 0.031). UCa/Cr values normalized by the third-month post-OLT, decreasing significantly over the time (p = 0.000) but did not correlate with TAC troughs. At three months post-OLT, 65.2% of patients needed antihypertensive therapy, and no patients needed more than one antihypertensive treatment after one yr. Despite nephrotoxic side effects in the early postoperative phase, this study shows that 65.5% patients had a normal renal function by three yr post-OLT. Tubular indices correlated with TAC trough levels.

Conversion to everolimus in liver transplant patients with renal dysfunction

Calcineurin inhibitor (CNI) immunosuppressive therapy post-liver transplantation (OLT) is important to reduce graft rejection episodes. However, these drugs show important side effects, particularly renal dysfunction (RDF). Changing from CNI to a nonnephrotoxic drug, as mammalian target of rapamycin (mTOR) inhibitor may solve the problem. Our objective was to evaluate renal function (RF) among liver transplant patients initially receiving CNI, among whom the patients with RDF were converted completely or partially to an mTOR inhibitor like everolimus (EVE). We performed a prospective study in liver transplant patients from 2000 to 2009. Creatinine levels and creatinine clearances (Cockroft-Gault) expressed as mean values ± standard deviations were measured pre- and postswitch for comparisons using Wilcoxon nonparametric tests. Six patients were converted fully or partially to EVE. Their mean age at the moment of introducing the new therapy was 52.2 ± 13.6 years (range = 28-60). Immunosuppression time prior to switching from CNI to EVE was 23.8 ± 26.6 months (range = 6-70). Postconversion follow-up was 25.8 ± 16.5 months (range = 8-42). All patients showed improvement in RF. The creatinine level improvement was significant (P = .03) namely, from a mean of 2.26 ± 0.49 to 1.21 ± 0.57 mg/dL. Glomerular filtration rate improved from a mean of 40 ± 15.13 to 72.60 ± 17.3 mL/min/m(2) (P = .03). Conversion from CNI to EVE improved creatinine concentrations and creatinine clearances with long-term effects free of graft rejection.

Effects of erdosteine on cyclosporin-A-induced nephrotoxicity

AIM

In cyclosporin-A (CsA)-induced toxicity, oxidative stress has been implicated as a potential responsible mechanism. Therefore, we aimed to investigate the protective role of erdosteine against CsA-induced nephrotoxicity in terms of tissue oxidant/antioxidant parameters and light microscopy in rats.

MATERIALS AND METHODS

Wistar albino rats were randomly separated into four groups. Group 1 rats treated with sodium chloride served as the control, group 2 rats were treated with CsA, group 3 with CsA plus erdosteine, and group 4 with erdosteine alone. Animals were killed and blood samples were analyzed for blood urea nitrogen (BUN), serum creatinine (Cr), uric acid (UA), total protein (TP), and albumin (ALB) levels. Kidney sections were analyzed for malondialdehyde (MDA) and nitric oxide (NO) levels and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities, as well as for histopathological changes.

RESULTS

In the CsA group, MDA, GSH-Px, BUN, and Cr levels were increased. The TP and ALB levels were decreased. These changes had been improved by erdosteine administration. Other biochemical parameters did not show any significant change.

CONCLUSION

These results indicate that erdosteine produces a protective mechanism against CsA-induced nephrotoxicity and suggest a role of oxidative stress in pathogenesis.

A therapeutic exploratory study to determine the efficacy and safety of calcineurin-inhibitor-free de-novo immunosuppression after liver transplantation: CILT

Background

Immunosuppression with calcineurin inhibitors (CNI) increases the risk of renal dysfunction after orthotopic liver transplantation (OLT). Controlled trials have shown improvement of renal function in patients that received delayed and/or reduced-dose CNI after OLT. Delaying immunosuppression with CNI in combination with induction therapy does not increase the risk of acute rejection but reduces the incidence of acute renal dysfunction. Based on this clinical data this study protocol was designed to assess the efficacy and safety of calcineurin-inhibitor-free de-novo immunosuppression after liver transplantation.

Methods/Design

A prospective therapeutic exploratory, non-placebo controlled, two stage monocenter trial in a total of 29 liver transplant patients was designed to assess the safety and efficacy of de-novo CNI-free immunosuppression with basiliximab, mycophenolate sodium, prednisolone and everolimus. The primary endpoint is the rate of steroid resistant rejections. Secondary endpoints are the incidence of acute rejection, kidney function (assessed by incidence and duration of renal replacement therapy, incidence of chronic renal failure, and measurement glomerular filtration rate), liver allograft function (assessed by measurement of AST, ALT, total bilirubin, AP, GGT), treatment failure, (i. e., re-introduction of CNI), incidence of adverse events, and mortality up to one year after OLT.

Discussion

This prospective, two-stage, single-group pilot study represents an intermediate element of the research chain. If the data of the phase II study corroborates safety of de-novo CNI-free immunosuppressive regimen this should be confirmed in a randomized, prospective, controlled double-blinded clinical trial. The exploratory data from this trial may then also facilitate the design (e. g. sample size calculation) of this phase III trial.

Trial registration number

NCT00890253 (clinicaltrials.gov)

Calcineurin inhibitors promote chondrogenic marker expression of dedifferentiated human adult chondrocytes via stimulation of endogenous TGFbeta1 production

In vitro chondrocyte expansion is required for several cell-based approaches for the repair of chondral lesions. During expansion, loss of chondrogenic phenotype takes place (dedifferentiation). The objective of this study was to investigate calcineurin (Cn) as a potential target to improve chondrocyte phenotype for cartilage repair purposes. Cn activity in human articular chondrocytes was significantly increased during dedifferentiation and decreased during redifferentiation in vitro. Inhibition of Cn activity by FK506 increased the expression of chondrogenic markers collagen type 2, aggrecan, and SOX9 in culture-expanded cells. Addition of FK506 increased endogenous transforming growth factor 2 (TGF) beta1 expression on both mRNA and protein level. The effect of FK506 on chondrogenic markers was abolished by addition of anti-TGFbeta1 antibody, indicating that the endogenous TGFbeta1 was necessary to increase chondrogenic marker expression. We also showed that chondrocyte redifferentiation by TGFbeta requires calcium influx and does not depend on changes in Cn activity. In conclusion, inhibition of Cn activity by FK506 increases the expression of chondrogenic markers via endogenous TGFbeta1 production in human articular chondrocytes. Cn inhibitors might be an alternative for the application of (recombinant) TGFbeta, to promote chondrocyte phenotype for cell-based cartilage repair procedures.

Potassium homeostasis and renin-angiotensin-aldosterone system inhibitors

Inhibition of the renin-angiotensin-aldosterone system (RAAS) is a key strategy in treating hypertension and cardiovascular and renal diseases. However, RAAS inhibitors (angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aldosterone receptor antagonists, and direct renin inhibitors) increase the risk of hyperkalemia (serum potassium >5.5 mmol/L). This review evaluates the effects on serum potassium levels of RAAS inhibitors. Using PubMed, we searched for clinical trials published up to December 2008 assessing the effects on serum potassium levels of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aldosterone receptor antagonists, and direct renin inhibitors, alone and in combination, in patients with hypertension, heart failure (HF), or chronic kidney disease (CKD); 39 studies were identified. In patients with hypertension without risk factors for hyperkalemia, the incidence of hyperkalemia with RAAS inhibitor monotherapy is low (< or =2%), whereas rates are higher with dual RAAS inhibition ( approximately 5%). The incidence of hyperkalemia is also increased in patients with HF or CKD (5% to 10%). However, increases in serum potassium levels are small ( approximately 0.1 to 0.3 mmol/L), and rates of study discontinuation due to hyperkalemia are low, even in high-risk patient groups (1% to 5%). Patients with HF or CKD are at greater risk of hyperkalemia with RAAS inhibitors than those without these conditions. However, the absolute changes in serum potassium are generally small and unlikely to be clinically significant. Moreover, these patients are likely to derive benefit from RAAS inhibition. Rather than denying them an effective treatment, electrolyte levels should be closely monitored in these patients.

Treatment strategies to minimize or prevent chronic allograft dysfunction in pediatric renal transplant recipients: an overview

Long-term allograft survival poses a major problem in pediatric renal transplantation, with allograft nephropathy being the principal cause of graft failure after the first post-transplant year. The mechanisms of nephron loss resulting in graft dysfunction are multiple, comprising both immunologic factors such as acute and chronic antibody- or T-cell-mediated rejection and non-immunologic components. The latter include peri-transplant injuries and renovascular lesions (renal artery stenosis, thrombosis) as well as cardiovascular risk factors such as arterial hypertension and hyperlipidemia. Another relevant issue leading to progressive nephron loss and declining kidney transplant function is acute and chronic nephrotoxicity induced by the calcineurin inhibitors (CNIs) ciclosporin (cyclosporine microemulsion) and tacrolimus. Furthermore, the presence of an abnormal lower urinary tract as well as bacterial (recurrent pyelonephritis) and viral (cytomegalovirus [CMV], polyomavirus [BK virus; BKV]) infections are crucial factors involved in the incidence of chronic allograft dysfunction and graft failure. Renovascular lesions and lower urinary tract obstruction are typical indicators for surgical intervention. The aim of treatment in pediatric patients with renal failure secondary to a dysfunctional lower urinary tract is to create a sterile, continent, and nonrefluxive reservoir. Surgical techniques such as bladder augmentation and the introduction of intermittent catheterization and anticholinergic therapy have significantly improved graft outcome. Arterial hypertension, another factor responsible for graft function deterioration in pediatric renal transplant recipients, is controlled preferably by the use of angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor antagonists, which are known to possess nephroprotective properties in addition to their potent antihypertensive effects. Although treatment of subclinical rejection with augmented immunosuppression has been associated with better graft survival, an increase of the immunosuppressive level to avoid subclinical rejection should be weighed against the risk of infection. The majority of viral infections affecting kidney allografts are caused by CMV and BKV. Antiviral CMV prophylaxis or pre-emptive therapy with ganciclovir has been shown to have beneficial effects in the pediatric renal transplant population. Treatment of BKV-induced nephropathy is based on reduction of the immunosuppressant therapy, although specific antiviral agents such as cidofovir and leflunomide are known to inhibit BKV. However, cidofovir itself is nephrotoxic and should therefore be administered cautiously to pediatric renal transplant patients. Since CNIs are likewise known for their nephrotoxic effects, especially with long-term use, alteration of the immunosuppressant regimen is necessary in case of deteriorating graft function due to CNI-induced histopathologic changes. Complete CNI avoidance seems inappropriate because, in this situation in pediatric renal transplant recipients, other relatively potent immunosuppressant agents such as lymphocyte-depleting antibodies, which are frequently accompanied by a higher incidence of infections, are needed for rejection prophylaxis. CNI withdrawal and switching of the immunosuppressant regimen from CNI therapy to sirolimus may be an option for some pediatric renal transplant patients with less advanced graft function deterioration. Nevertheless, potential adverse events such as aggravation of proteinuria, hyperlipidemia, myelosuppression, and hypergonadotropic hypogonadism have to be considered, and controlled studies are lacking. At present, an immunosuppressant maintenance therapy composed of low-dose tacrolimus or ciclosporin (CNI minimization) and mycophenolate mofetil with low-dose corticosteroids appears to be the most promising strategy to adopt in pediatric renal transplant recipients at low or normal immunologic risk.

Kidney graft function in long-term cyclosporine and tacrolimus treatment: comparative study with nephrotoxicity markers

Calcineurin inhibitors improve kidney allograft survival in the posttransplantation period; however, they may cause nephrotoxicity. The objective of this study was to compare the effect of cyclosporine (CsA) and tacrolimus (Tac) treatment on the transplanted kidney. The study included 219 patients aged 21 to 65 years. Of these, 120 (39 women and 81 men) were treated with CsA and 99 (38 women and 61 men) were treated with Tac. Patients were divided into 4 groups depending on the time since kidney transplantation. We evaluated urine markers of nephrotoxicity: proximal tubular cells lysosomal enzymes (N-acetyl-beta-d-glucosaminidase [NAG] and its isoform NAG-B, beta-d-galactosidase, and beta-glucouronidase) and brush border enzymes (alanyl aminopeptidase and gamma-glutamyl transpeptidase). Urine activities of nephrotoxicity markers were compared in CsA- and Tac-treated patients groups depending on the duration of treatment and allograft function as measured by serum creatinine concentration. Correlation studies between CsA and Tac levels and enzyme activities were performed in both groups and in the entire patient cohort. NAG and its isoform NAG-B seemed to be the most reliable markers of nephrotoxicity. Despite the significant correlation between NAG urine activity and serum creatinine concentration in the CsA group, there were no significant differences in NAG or NAG-B activities between CsA- and Tac-treated graft recipients.

The calcineurin inhibitor FK506 (tacrolimus) is associated with transient metabolic acidosis and altered expression of renal acid-base transport proteins

Calcineurin inhibitors like FK506 (tacrolimus) are routinely used for immunosuppression following transplantation. Its use is limited by many side effects, including renal tubular acidosis (RTA), mainly of the distal type. In this study, rats were treated with FK506 and at baseline (after 9 days) systemic acid-base status was similar to that in control animals. However, FK506-treated rats given NH4Cl in the drinking water for 2 days developed a more severe metabolic acidosis than control animals. Urine pH was more alkaline, but net acid excretion was normal. After 7 days of acid load, all differences related to acid-base homeostasis were equalized in both groups. Protein abundance of type IIa Na-Pi cotransporter, type 3 Na+/H+ exchanger, and electrogenic Na+-bicarbonate cotransporter, and both a4 and B2 subunits of the vacuolar H+-ATPase were reduced under baseline conditions, while induction of metabolic acidosis enhanced protein abundance of these transporters in FK506-treated animals. In parallel, protein expression of AE1 was reduced at baseline and increased together with pendrin during NH4Cl loading in FK506 rats. Protein abundance of the Na+-bicarbonate cotransporter NBCn1 was reduced under baseline conditions but remained downregulated during metabolic acidosis. Morphological analysis revealed an increase in the relative number of non-type A intercalated cells in the connecting tubule and cortical collecting duct at the expense of principal cells. Additionally, subcellular distribution of the a4 subunit of the vacuolar H+-ATPase was affected by FK506 with less luminal localization in the connecting tubule and outer medullary collecting duct. These data suggest that FK506 impacts on several major acid-base transport proteins in the kidney, and its use is associated with transient metabolic acidosis and altered expression of key renal acid-base transport proteins.

The epidemiology of drug-induced disorders: the kidney

The epidemiology of drug-induced renal disorders is a complex topic. Drug-associated nephrotoxicity accounts for 18 - 27% of all acute kidney injury cases in US hospitals. Medications can affect all aspects of the kidney, and drugs that are associated with renal dysfunction are used commonly in clinical practice. The article reviews six major mechanisms of drug-induced renal dysfunction as well as lists the major medications involved. NSAIDs, aminoglycosides, amphotericin B and calcineurin inhibitors are just some examples of drugs that contribute to renal dysfunction. The medical community must be aware of patient risk factors for nephrotoxicity, as well as the drug's inherent nephrotoxic potential, when prescribing and administering medications.

Incidence and predictors of delayed chronic kidney disease in long-term survivors of hematopoietic cell transplantation

BACKGROUND

The authors investigated the risk of delayed chronic kidney disease (CKD) in 1190 adult hematopoietic cell transplantation (HCT) survivors who underwent HCT for hematologic malignancies or aplastic anemia between 1976 and 1997 and survived for at least 1 year.

METHODS

CKD was defined as a sustained elevation of serum creatinine that indicated a glomerular filtration rate of <60 mL per minute per 1.73 m2 for > or =3 months. The median age at HCT was 35 years (range, 18.1-68.6 years), and the median length of follow-up was 7.1 years after HCT (range, 1-24.3 years).

RESULTS

Sixty patients with CKD were identified, resulting in a cumulative incidence of 4.4% at 5 years (autologous HCT, 3.8%; matched-sibling HCT, 4.5%; unrelated donor HCT, 10%; P = .09 compared with autologous HCT). Older age at HCT (relative risk [RR] per 5-year increment, 1.33; 95% confidence interval [CI], 1.2-1.5), exposure to cyclosporine without tacrolimus (RR, 1.90; 95% CI, 1.1-3.4) or with tacrolimus (RR, 4.59; 95% CI, 1.8-11.5), and a primary diagnosis of multiple myeloma (RR, 2.51; 95% CI, 1.1-5.6) were associated with an increased risk of delayed CKD.

CONCLUSIONS

In this study, the authors identified a subpopulation of patients who underwent HCT and remained at increased risk for CKD. The current findings set the stage for appropriate long-term follow-up of vulnerable patients.

Acute kidney injury and chronic kidney disease after cardiac surgery

Kidney dysfunction is common after cardiac surgery and predicts mortality risk and poorer long-term outcome, particularly when acute injury superimposes upon chronic kidney disease. Numerous insults contribute to perioperative renal impairment including major surgical trespass, procedure-specific interventions (eg, deep hypothermic circulatory arrest), and postoperative complications. Regardless of cause, evidence supports a role for renal impairment and accumulation of "uremic toxins" as direct contributors to adverse outcome. No one has yet characterized a loss of renal function small enough to be insignificant. Despite considerable research focus, progress in development of interventions aimed at perioperative renoprotection has been disappointing. However, practice modifications can influence the likelihood of acute kidney injury, and several recent advances provide hope for the future. We review pathophysiologic understanding of this disorder; evaluate the confusing relationship (causal v epiphenomena) among acute kidney injury, chronic kidney disease, and adverse outcome after cardiac surgery; and provide an evidence-based assessment of the conduct of cardiac surgery and renoprotection strategies.

Induction of synapse associated protein 102 expression in cyclosporin A-stimulated hair growth

Cyclosporin A (CsA) has been used as a potent immunosuppressive agent for inhibiting the graft rejection after organ transplantation. However, CsA provokes lots of side effects including hirsutism, the phenomenon of abnormal hair growth in the body. In the present study, we investigated the hair growth stimulating effect of CsA using in vivo and in vitro test models. When topically applied on the back skin of mice, CsA induced fast telogen to anagen transition. In contrast, CsA had no effect on the growth of human hair follicle tissues cultured in vitro, indicating that it might not have the mitogenic effect on hair follicles. To identify the genes related with CsA-induced hair growth, we performed differential display RT-PCR. Among the genes obtained, the expression of synapse associated protein 102 (SAP102) was verified using competitive RT-PCR. The result showed that the expression of SAP102 was significantly induced by CsA treatment in the back skin of C57BL/6 mice. However, the increase of SAP102 mRNA was also seen in spontaneous anagen mice, suggesting that induction of SAP102 is one event of the anagen hair growth response regardless of how the growth state was induced. SAP102 was not expressed in cultured human hair outer root sheath and dermal papilla cells. Immunohistochemistry analysis showed that CsA induced the expression of SAP102 in perifollicular region of mouse anagen hair. Together, these results suggest that SAP102 is one of hair-cycle-dependent genes, whose expression is related with the anagen progression.

[Total glucosides of peony as adjuvant therapy for prevention of cardiac allograft rejection in rats]

OBJECTIVE

To evaluate the role of total glucosides of peony (TGP) as adjuvant therapy for prevention of cardiac allograft rejection in rats.

METHODS

Rats with cardiac allograft were randomly divided into control group, tacrolimus-treated group, TGP-treated group and tacrolimus plus TGP-treated group. Graft survival time was observed. Allografts in some cases were examined by histological study seven days after transplantation. At the same time, the levels of CD4(+) and CD8(+) T cell subsets in peripheral blood were examined by using flow cytometry; the hepatic function and renal function of recipients were also tested.

RESULTS

The graft survival time of the tacrolimus-treated group and tacrolimus plus TGP-treated group was (11.14+/-1.57) d and (13.57+/-1.99) d, respectively. The graft survival time of the tacrolimus plus TGP-treated group was longer than that of the tacrolimus-treated group (P<0.05). The histological study showed that the rejection of the tacrolimus plus TGP-treated group was slighter than that of the tacrolimus-treated group. The levels of CD4(+) T cell subset in the peripheral blood of the tacrolimus-treated and tacrolimus plus TGP-treated groups were (38.71+/-5.15)% and (32.43+/-4.39)% respectively 7 days after transplantation. The level of CD4(+) T cell subset in the tacrolimus plus TGP-treated group was lower than that in the tacrolimus-treated group (P<0.05). The level of CD8(+) T cell subset and the hepatic and renal function had no significant differences between the tacrolimus-treated group and the tacrolimus plus TGP-treated group.

CONCLUSION

Effects of tacrolimus plus TGP in prevention of rejection are better than tacrolimus monotherapy in rats with cardiac allograft and without increasing side effects.

New insights into the pathophysiology of cyclosporine nephrotoxicity: a role of aldosterone

Cyclosporine A (CsA), a calcineurin inhibitor, has improved allograft survival in solid organ transplantation and has been increasingly applied in the management of autoimmune diseases. While marked progress has been made in patient and allograft survival rates, clinical use of CsA is often limited by its nephrotoxic effect, which can be presented as two distinct and well-characterized forms: acute and chronic nephrotoxicity. The acute form is characterized by renal vasoconstriction, induced by an imbalance of vasoactive substances release, which leads to renal dysfunction. This form is reversible. The chronic toxicity, in contrast, is characterized by the vasoconstriction plus the development of structural damage that includes arteriolopathy and tubulointerstitial fibrosis that are often not reversible. The exact mechanisms of these deleterious effects are not fully understood, but major advances have occurred over the last few years. Here we review the current literature regarding the pathogenesis and strategies that have been used to ameliorate renal injury in chronic CsA nephrotoxicity. Recent observations suggest that aldosterone plays a central role in the pathogenesis of CsA nephrotoxicity and that spironolactone could be a useful agent to prevent it. These studies and the use of mineralocorticoid receptor blockade are discussed.

The Role of Immunosuppressive Drugs in Aggravating Renal Ischemia and Reperfusion Injury

Renal ischemia followed by reperfusion leads to acute renal failure in both native kidneys and renal allografts. Cyclosporine has known nephrotoxic effects. Thus, cyclosporine therapy subsequent to ischemia/reperfusion (I/R) injury may further exacerbate graft dysfunction. Rapamycin is a newer agent that suppresses the immune system by a different mechanism. In the present study, the effects of Cyclosporine and rapamycin at low and higher concentrations were investigated in an I/R-induced injury model.

METHODS

Cyclosporine (100 mg/kg or 50 mg/kg), rapamycin (3 mg/kg per day or 1.5 mg/kg), or both were administered to mice before being subjected to 45 minutes of ischemia. Blood and kidney samples were collected at 24, 48, and 120 hours after surgery. We quantified acute tubular necrosis and tubular regeneration.

RESULTS

Animals subjected to I/R showed impaired renal function that peaked at 24 hours (2.05 +/- 0.23 mg/dL), decreasing thereafter. Treatment with higher concentrations of cyclosporine or rapamycin caused even more renal dysfunction at 48 hours, which was sustained up to 120 hours after reperfusion (1.53 +/- 0.6 mg/dL), when compared to the low concentrations of cyclosporine or rapamycin (1.08 +/- 0.19 mg/dL; 0.99 +/- 0.14 mg/dL, P < .05, respectively). Cyclosporine delayed tubular regeneration, which was higher in controls at day 5 (67.0% vs 37.6%, P < .05).

CONCLUSIONS

These results demonstrated that cyclosporine or rapamycin might further aggravate ischemically injured organs, negatively affecting posttransplantation recovery in a concentration-dependent fashion.

Chronic cyclosporine nephrotoxicity: a pig model

Cyclosporine A (CsA) is one of the keystones in immunosuppressive treatment after solid organ transplantation, despite its major side effects such as nephrotoxicity. The chronic nephrotoxic effects of CsA seen in humans have been difficult to reproduce in small-animal models. The aim of the present study was to examine the chronic nephrotoxicity produced by therapeutic dosages of CsA in a pig model. Among 11 Gottingen minipigs included in the study, three died, yielding data from five animals given CsA (10 mg/kg/d, orally) for 6 months, and three controls. Body weight, blood pressure, glomerular filtration rate (GFR) by plasma clearance of (51)Cr-ethylenediamine-tetraacetic acid, CsA concentration, serum creatinine, and other values were measured every 5 weeks. Our results showed that the whole blood trough CsA levels were lower in pigs than in humans treated with similar CsA doses. Renal biopsies, which were obtained successfully, except one case of macroscopic hematuria, showed no histological changes in the kidney. No significant increase in serum creatinine or blood pressure was observed. Surprisingly, there was a significant increase in GFR during CsA treatment. We conclude that the pig model displays a hyperfiltration that warrants further investigation.

Cardiovascular complications of immunosuppressive agents in renal transplant recipients

Fatal and nonfatal cardiovascular events are the most important cause of graft loss in patients with a functioning graft following transplantation. The available data indicate that transplant patients have a high prevalence of hypertension, hyperlipidaemia and new onset diabetes mellitus after transplantation. The aetiology and pathogenesis of post-transplant hypertension, hyperlipidaemia and diabetes are multifactorial. In addition, disease of the native kidney and recurrence of renal disease can contribute to the development of cardiovascular disease in transplant recipients. Most transplant patients are at risk of clinically important drug-drug interactions involving immunosuppressive agents. Adverse reactions and drug-drug interactions should not be neglected when selecting an agent for treatment of cardiovascular risk factors in transplant recipients.

Everolimus treatment downregulates renocortical cyclooxygenase-2 expression in the rat kidney

Based on recent evidence that renal cyclooxygenase-2 (COX-2) gene expression is suppressed by immunosuppressive agents such as cyclosporin A (CsA), tacrolimus and dexamethasone, this study aimed to characterize the effect of the new immunosuppressant everolimus on COX-2 expression in the rat kidney. Oral application of everolimus (3 mg kg(-1) day(-1)) to male Sprague-Dawley rats (175-200 g; n=8) for 7 days lowered COX-2 expression in the rat renal cortex and outer medulla, while COX-2 expression in the inner medulla as well as COX-1 expression remained unaltered. Furthermore, everolimus decreased renocortical prostaglandin (PG) E(2) concentration. Everolimus also attenuated the stimulation of renocortical COX-2 expression by furosemide (12 mg day(-1) for 7 days; s.c. via osmotic minipumps), by low salt intake (0.02% NaCl, wt wt(-1)) or by a combination of low salt intake with the AT(1)-receptor antagonist valsartan (30 mg kg(-1) day(-1); oral). In line with these findings, everolimus decreased renocortical PGE(2) concentration during these treatment maneuvers. Everolimus moderately increased natriuresis and diuresis, while the urinary excretion of PGE(2), 6-keto PGF(1alpha) and thromboxane B(2) was decreased. These findings suggest that everolimus inhibits basal and also stimulated expression of renocortical COX-2 and of tissue prostanoid formation. Since inhibition of renal prostanoid formation by everolimus was associated by an increased rather than decreased natriuresis and diuresis, it appears as if everolimus also inhibits tubular salt and water resorption.

Physiologic Impact of Low-Dose Dopamine on Renal Function in the Early Post Renal Transplant Period

BACKGROUND

Low-dose dopamine (LDD) (< or =5.0 microg/kg/min) is often used in the early postrenal transplant period for its perceived improvements in renal function parameters. However, there is little published evidence to support its use. The aim of this study was to evaluate the effects of LDD on the physiologic parameters of the transplanted kidney.

METHODS

With local ethics approval, 20 consecutive adult patients (age range, 27-74 years), who underwent cadaveric renal transplantation with cyclosporine immunosuppression, were randomized into two study groups, each with 10 patients. The study period was over 9 hrs on the first postoperative day. This 9-hr block was divided into three 3-hr periods. Patient group 1 received a dopamine infusion over the second 3-hr period only, and patient group 2 received a dopamine infusion over both the first and third 3-hr periods. During these periods, urine flow rate (UFR), effective renal plasma flow (ERPF), creatinine clearance (CC), and total urinary sodium excretion rate (tUNa) were measured.

RESULTS

In both groups, there were significant (P<0.05, Wilcoxon rank sum test) increases in ERPF, UFR, CC, and tUNa during LDD infusion periods compared with periods of no LDD infusion. No changes in heart rate or mean arterial blood pressure were seen with LDD administration.

CONCLUSIONS

LDD significantly increases ERPF, UFR, CC, and tUNa in the transplanted allograft kidney treated with cyclosporine immunosuppression in the early posttransplant period.

Recovery of Chronic Renal Impairment With Sirolimus After Lung Transplantation

BACKGROUND

Standard immunosuppression after lung transplantation includes calcineurin inhibitors, azathioprine, and steroids. Calcineurin inhibitor administration is associated with an increased renal impairment. Sirolimus shows no renal toxicity and could be used in selected patients.

METHODS

We have prospectively administered sirolimus as an alternative to calcineurin inhibitors in 15 lung transplantation recipients with persistent drug nephrotoxicity. Eight patients had also bronchiolitis obliterans syndrome. The mean serum creatinine and azotemia were 2.7 +/- 1.1 mg/dL and 111 +/- 39 mg/dL. After starting sirolimus, azathioprine was reduced to 50%-25% of baseline, calcineurin inhibitors were gradually reduced and eventually stopped, and steroids were maintained stable. Patients started sirolimus with 2 to 5 mg/d orally; adjustments were made according to trough levels (4 to 12 ng/mL for combined sirolimus + calcineurin inhibitors; 12 to 20 ng/mL as monotherapy), toxicity, and perceived efficacy. Patients were monitored for renal and graft function and clinical status.

RESULTS

A significant creatinine decrease was observed after 6 months of treatment (p < 0.02); azotemia decreased after 1 month and remained stable (p < 0.01). Pulmonary function tests did not show any significant modification from before sirolimus baseline in patients without bronchiolitis obliterans syndrome. There were eight infectious complications and 10 episodes of toxicity (4 dermatitis, 2 epistaxis, 1 headache, 1 diarrhea, 1 nausea, 1 laryngeal cancer). Moderate leukocytopenia (n = 3) and hypertriglyceridemia (n = 6) responded to dose reduction. One patient was lost to follow-up. Three patients died of complications related to bronchiolitis obliterans. One patient underwent transplantation again.

CONCLUSIONS

Sirolimus administration allows amelioration of renal function with a relatively low morbidity and is useful for chronic renal impairment rescue after lung transplantation.

Cyclosporin A: a new drug in the field of canine dermatology

In the last few years, there has been growing interest in the use of cyclosporin to treat canine skin diseases. Cyclosporin exhibits potent immunomodulating properties that reflect its ability to block the transcription of cytokines genes in activated T lymphocytes. Cyclosporin also inhibits a number of immune allergic reactions that occur after activation of mast cells, Langerhans cells, eosinophils and keratinocytes. In randomized controlled trials, cyclosporin has proven to be as effective as glucocorticoids for treatment of canine atopic dermatitis at the inducing dosage of 5 mg kg(-1). The drug has also proven beneficial for the treatment of perianal fistulas in dogs. Other potential applications are suggested from small pilot open trials using dogs affected with various immune-mediated dermatological diseases. The pharmacokinetic properties of cyclosporin are very similar in dogs and man, but its safety margin is much wider in dogs. Therefore, routine cyclosporin blood level monitoring does not appear necessary. Although in man renal impairment and hypertension are often seen, even at low doses, these effects are not observed in dogs. Adverse reactions consist mainly of transient emesis and diarrhoea occurring during the first days of treatment. Other adverse reactions, such as gingival hyperplasia, verruciform lesions and hypertrichosis, appear to be dose-dependent, and occur rarely at therapeutic doses. An increased susceptibility to infections has not been reported in dogs receiving this drug.

Cyclosporine renal dysfunction

Cyclosporine (CsA), introduced as an immunosuppressive agent in the 1980s, quickly become the first-line treatment in organ transplantation. However, these improvements were associated with an increased incidence of renal dysfunction. CsA causes histopathological changes in renal transplants that are often difficult to distinguish from other processes, especially chronic allograft nephropathy. Enhanced angiotensin II, transforming growth factor-beta, and vascular endothelial growth factor expression together with down-regulation of nitric oxide synthesis may play roles in chronic CsA nephropathy. Efforts have recently focused upon protocols that minimize the risk of CsA nephrotoxicity while preserving low rates of acute rejection. Four types of CsA-sparing studies have emerged from recent clinical experience: (1) conversion studies in which a nonnephrotoxic drug is substituted to allow CsA reduction, (2) minimal CsA exposure studies in which reduced CsA doses are combined with nonnephrotoxic drugs, (3) withdrawal studies in which CsA is completely discontinued at some time after transplantation, and (4) CsA-free studies in which the drug is completely avoided from the time of transplantation. Monitoring of CsA immunosuppression according to C2 blood levels, which better correlate with the area under the time-concentration curve than trough concentrations, should reduce the risk for toxicity; however, the most appropriate target range has not yet been clearly established. Because of interindividual differences in CsA absorption and susceptibility to renal dysfunction, the current therapeutic drug monitoring should be supplemented with pharmacogenetic information on genetic variability of relevant genes for pharmacokinetic parameters and therapeutic targets. This approach may guide choices for immunosuppressants for particular patients, with low toxicity. Thus, despite of 20 years of its history, CsA renal dysfunction remains an important clinical challenge.

Calcineurin inhibitor-associated early renal insufficiency in cardiac transplant recipients: risk factors and strategies for prevention and treatment

Cardiac transplantation is the definitive treatment for eligible patients with end-stage cardiac failure. Techniques have evolved to reduce surgical mortality to under 5%. Immediate and subsequent long-term survival is more dependent on acute and chronic rejection and the complications of immunosuppressive therapy. Ten-year survival is greater than 50%.The success of transplantation over the last 20 years has been largely due to the advances in immunosuppression. The most notable and dramatic milestone was the introduction of cyclosporine in the early 1980s, which resulted in a significant improvement in allograft and patient survival. Cyclosporine is a peptide that inhibits the immune system by suppressing T-helper cell activation via inhibition of calcineurin, a critical intracellular enzyme. Tacrolimus has a similar (but not identical) mechanism of action, and was introduced in the 1990s. Drugs such as cyclosporine and tacrolimus, generically referred to as calcineurin inhibitors, have become the cornerstones of immunosuppressive protocols. As a group, calcineurin inhibitors have adverse effects, including neurotoxicity, hypertension, and nephrotoxicity, which complicate their use. Early renal insufficiency manifests as postoperative oliguria (<50 mL/h urine output) or rising serum creatinine levels. There are a variety of postulated causes for calcineurin inhibitor-associated early renal insufficiency including direct calcineurin inhibitor-mediated renal arteriolar vasoconstriction, increased levels of endothelin-1 (a potent vasoconstrictor), as well as decreased nitric oxide production and alterations in the kidney's ability to adjust to changes in serum tonicity. Once early renal insufficiency occurs, no single treatment has been shown to be effective. Approaches discussed in this paper include reduction in calcineurin inhibitor dosages, as well as various drugs to promote increased renal perfusion such as misoprostol and dopamine. In addition, the paper emphasizes the importance of ruling out other causes of renal insufficiency in the early postoperative period, including volume depletion, depressed cardiac output, and mechanical obstruction to urine flow. Given that there is no highly efficacious treatment for this syndrome, ways to avoid its occurrence are desirable. One paper is referenced that suggests that avoidance of rapid changes in tacrolimus level during the first three days of therapy is associated with a low occurrence of early renal insufficiency.

Salvage chemotherapy for refractory or relapsed post-transplant lymphoproliferative disorder in patients after solid organ transplantation with a combination of carboplatin and etoposide

This pilot study assessed the feasibility and efficacy of salvage chemotherapy (carboplatin and etoposide; CE) supported by granulocyte colony-stimulating factor (GCSF) in patients with refractory or relapsed post-transplant lymphoproliferative disorder (PTLD) following solid organ transplantation. Intensified salvage regimens were not feasible for these patients, due to their immunosuppressive conditions and potential organ (especially kidney and bone marrow) malfunctions. Salvage chemotherapy consisted of carboplatin [area under the curve (AUC) 4], on day 1, etoposide (120 mg/m2), on days 1-3 and GCSF (5 microg/kg) starting on day 5. This therapeutic regimen was planned to be repeated every 21 d. Nine patients (seven with refractory, two with relapsed disease) were enrolled. Five patients were heart transplant recipients, three liver transplant recipients and one patient had been a double lung transplant recipient. Five patients achieved a complete remission (CR), with follow-up at 92, 39, 55+, 17 and 9+ months. One patient showed stable disease after two cycles of CE and one patient had progressive disease. Two patients experienced early deaths, after the first and third cycles of chemotherapy respectively. One died of septic complications and one because of a perforated intestine, which had been infiltrated by lymphoma. In respect of the difficulties experienced in treating patients with refractory or relapsed PTLD after solid organ transplantation, the combination of carboplatin and etopoide with GCSF support (filgrastim) proved to be an effective regimen.