Cardiovascular disease posttransplant

Impact of Immunosenescence in Older Kidney Transplant Recipients: Associated Clinical Outcomes and Possible Risk Stratification for Immunosuppression Reduction

The number of older individuals receiving a kidney transplant as replacement therapy has significantly increased in the past decades and this increase is expected to continue. Older patients have a lower rate of acute rejection but an increased incidence of death with a functioning graft. Several factors, including an increased incidence of infections, post-transplant malignancy and cardiovascular comorbidity and mortality, contribute to this increased risk. Notwithstanding, kidney transplantation is still the best form of kidney replacement therapy in all patients with chronic kidney disease, including in older individuals. The best form of immunosuppression and the optimal dose of these medications in older recipients remains a topic of discussion. Pharmacological studies have usually excluded older patients and when included, patients were highly selected and their numbers insignificant to draw a reasonable conclusion. The reduced incidence of acute rejection in older recipients has largely been attributed to immunosenescence. Immunosenescence refers to the aging of the innate and adaptive immunity, accumulating in phenotypic and functional changes. These changes influences the response of the immune system to new challenges. In older individuals, immunosenescence is associated with increased susceptibility to infectious pathogens, a decreased response after vaccinations, increased risk of malignancies and cardiovascular morbidity and mortality. Chronic kidney disease is associated with premature immunosenescent changes, and these are independent of aging. The immunosenescent state is associated with low-grade sterile inflammation termed inflammaging. This chronic low-grade inflammation triggers a compensatory immunosuppressive state to avoid further tissue damage, leaving older individuals with chronic kidney disease in an immune-impaired state before kidney transplantation. Immunosuppression after transplantation may further enhance progression of this immunosenescent state. This review covers the role of immunosenescence in older kidney transplant recipients and it details present knowledge of the changes in chronic kidney disease and after transplantation. The impact of immunosuppression on the progression and complications of an immunosenescent state are discussed, and the future direction of a possible clinical implementation of immunosenescence to individualize/reduce immunosuppression in older recipients is laid out.

Association between endothelial and platelet function markers and adiponectin in renal transplanted recipients on cyclosporine and tacrolimus immunosuppression based therapy

AIM

Coagulation abnormalities, endothelial dysfunction and arteriosclerosis play a key role in cardiovascular disease state observed in transplanted patients. Plasma adiponectin levels are lower following kidney transplantation. However, there is still a debate about this topic in the literature. This study evaluated, adiponectin levels associated with markers of endothelial dysfunction and platelet function in renal transplant patients.

METHODS

Sixty-six renal transplant patients were studied. Patients were grouped according to immunosuppression regimen. Group 1 (n = 36) were treated with cyclosporine A based regimes and group 2 (n = 30) were treated with tacrolimus based regimes. Plasma adiponectin, asymmetric dimethyl arginine (ADMA), sP-selectin levels and platelet aggregation tests were studied and were compared with those in control group (n = 15, group 3).

RESULTS

Adiponectin, sP-selectin and ADMA levels were higher in group 1 and statistically significant differences were observed compared with those of group 2 and group 3, respectively (P < 0.001, P < 0.05, P < 0.05). Platelet aggregation values induced by agonists were lower in group 1 than group 2 and group 3, but the difference did not reach statistical significance (P > 0.05).

CONCLUSION

Adiponectin levels are elevated in line with ADMA and sP-selectin levels. Since CsA induces higher adiponectin levels, platelet activation and endothelial dysfunction. These changes may be responsible for the increased risk of post-transplant cardiovascular events in renal transplant patients.

Cardiovascular risk factors in children after kidney transplantation--from short-term to long-term follow-up

Cardiovascular-related mortality is 100-fold higher in pediatric renal transplant recipients than in the age-matched general population. Seventy-seven post-renal transplant children's charts were reviewed for cardiovascular risk factors at two and six months after transplantation (short term) and at two yr after transplantation and the last follow-up visit (mean 7.14 ± 3.5 yr) (long term). Significant reduction was seen in cardiovascular risk factors prevalence from two months after transplantation to last follow-up respectively: Hypertension from 52.1% to 14%, hypercholesterolemia from 48.7% to 33%, hypertriglyceridemia from 50% to 12.5%, anemia from 29.6% to 18.3%, hyperparathyroidism from 32% to 18.3% and hyperglycemia from 11.7% to 10%, and left ventricular hypertrophy from 25.8% at short term to 15%. There was an increase in the prevalence of obesity from 1.5% to 3.9% and of CKD 3-5 from 4.75% to 24%. The need for antihypertensive treatment decreased from 54% to 42%, and the percentage of patients controlled by one medication rose from 26% to 34%, whereas the percentage controlled by 2, 3, and 4 medications decreased from 21.9%, 5.5%, and 1.4% to 6%, 2%, and 0. Children after renal transplantation appear to have high rates of cardiovascular risk factors, mainly on short-term follow-up.

Normal adiponectin levels in kidney transplant patients with hypertension

BACKGROUND

Kidney transplant patients are a unique population where despite correction of their kidney function they are still considered to be at high cardiovascular (CV) risk. Adiponectin, an adipokine secreted from adipocytes, has protective CV properties. Patients with essential hypertension (HTN) have low adiponectin levels that are associated with a high CV risk. The aim of this study was to assess adiponectin levels in hypertensive renal transplant recipients.

MATERIALS AND METHODS

Fasting blood adiponectin levels were measured in hypertensive kidney transplant patients (n = 18), patients with essential HTN (n = 17) and healthy subjects (n = 14). Patients with diabetes mellitus and renal failure were excluded from the study. Anthropomorphic and metabolic parameters were also measured.

RESULTS

Patients with essential HTN had lower adiponectin levels than healthy controls (6 ± 0.7 μg/mL vs. 11 ± 0.9 μg/mL, p < 0.001), whereas hypertensive kidney transplant patients had adiponectin levels that were similar to adiponectin levels found in normal controls (11 ± 1.1 μg/mL). Adiponectin levels in healthy subjects were inversely correlated with plasma triglycerides (r = -0.876, p < 0.001) and with body weight (r = -0.7, p < 0.001). There was no such a correlation in patients with HTN.

CONCLUSION

Adiponectin in hypertensive kidney transplant recipients is not an appropriate CV risk marker as it does not adequately distinguish these patients from normal controls.

Adiponectin and cardiovascular outcomes among hemodialysis patients

BACKGROUND

Adiponectin (ADPN) levels are consistently elevated among patients with advanced chronic kidney disease, but its relationship with cardiovascular outcomes in this population remains controversial. The aim of our study was to measure the plasma levels of ADPN in patients with end-stage renal disease on maintenance hemodialysis (HD) and we studied its correlates to cardiovascular outcomes and mortality.

METHODS

Our study included 133 HD patients (79 male and 54 female patients) with a mean age of 54.6 ± 17.3 years who had been receiving regular HD for at least 6 months in the nephrology units of Theodor Bilharz Research Institute, Cairo, Egypt. The clinical and biochemical correlates of plasma ADPN levels were investigated and the predictive power of ADPN levels with respect to cardiovascular events and mortality was prospectively tested in HD patients, who were monitored for 24 ± 9 months. Plasma ADPN levels were measured by using a sensitive enzyme-linked immunosorbent assay.

RESULTS

Plasma ADPN levels were 3 times higher (p < 0.0001) among HD patients (18.1 ± 6.8 μg/ml) than among healthy subjects (6.2 ± 1.8 μg/ml). Plasma ADPN levels were lower (p < 0.007) among patients who experienced new cardiovascular events (13.9 ± 6.4 μg/ml) than among event-free patients (18.6 ± 8.4 μg/ml). The relative risk of cardiovascular events was 1.96 times (95% confidence interval 1.290-2.977, p = 0.0016) higher among patients in group 1 (ADPN <15.1 μg/ml), compared with those in group 2 (ADPN ≥15.1 μg/ml). Plasma ADPN levels were inversely related to BMI, insulin levels, homeostatic model assessment index values, triglyceride and LDL-C, CRP and left ventricular mass index. Furthermore, plasma ADPN levels were directly related to HDL-C.

CONCLUSION

Plasma ADPN is an independent (inverse) predictor of cardiovascular events and mortality among HD patients. The directions of the RELATIONSHIPS between ADPN and several metabolic risk factors indicate that ADPN has a protective role in prevention of CVD.

Long-term health and work outcomes of renal transplantation and patterns of work status during the end-stage renal disease trajectory

INTRODUCTION

The aim of this study was to examine the health- and work outcomes of renal transplant recipients long-term after transplantation as well as the pattern of work status, work ability and disability benefits during the end-stage renal disease (ESRD) trajectory that precedes transplantation.

METHODS

34 transplant recipients completed interviews 3, 13 months and >6 years posttransplantation. Health status (SF-36), work ability (WAI), and fatigue (CIS) were assessed by questionnaires, clinical data were derived from medical charts, and data on functional limitations were extracted from the social security system database. The work status trajectory preceding transplantation was examined retrospectively.

RESULTS

Of the 34 third wave transplant recipients, 29% were severely fatigued. Compared with the general working population, recipients experienced worse general health and less vitality. Non-working recipients had worse renal function and general health, and more limitations in physical functioning compared to working recipients. The WAI score indicated moderate work ability for 60% of the employed recipients. Although 67% were employed (45% parttime), 30% of those working still received some disability benefits. Social insurance physicians found variable levels of functional limitations. The mean work status trajectory showed more sickness absence and less work ability during dialysis, but after transplantation, both work status and work ability generally improved.

CONCLUSIONS

Transplant recipients have a compromised health status which leads to functional limitations and disability. Although work status improved after transplantation, a substantial number of the transplant recipients received disability benefits. The negative health consequences of anti-rejection medications may play an important role in long-term work ability. These results indicate that a 'new' kidney has advantages over dialysis with respect to work, but does not necessarily leads to 'normal' work outcomes.

Evaluation of adult kidney transplant candidates

Important advances in immunosuppressive therapy and refinement in surgical techniques have allowed renal transplantation to become the treatment of choice for virtually all suitable candidates with end-stage renal disease. Compared to dialysis, kidney transplantation improves both patient survival and quality of life and, over time, can reduce the total cost of medical care. It must be noted, however, that although the risk of death in the first year after transplantation is <5%, not all patients qualify for the surgery because of their unacceptable risks for complications. The transplant evaluation process requires a comprehensive assessment of each patient's medical, surgical, and psychosocial histories. Selection of the suitable transplant candidate remains a challenge for transplant physicians owing, predominantly, to the presence of complex medical issues in the potential candidates and nonstandardized criteria for acceptance or rejection among transplant centers. Furthermore, with the ever-increasing disparity between donor organ supply and demand and resultant increased wait-list times, the transplant physicians must further consider the optimal management and re-evaluation of wait-list patients during the waiting period. This article describes a systematic approach for the evaluation of a potential renal transplant candidate. Various medical issues that arise during the evaluation process are discussed.

New onset diabetes after transplantation (NODAT): an overview

Although renal transplantation ameliorates cardiovascular risk factors by restoring renal function, it introduces new cardiovascular risks including impaired glucose tolerance or diabetes mellitus, hypertension, and dyslipidemia that are derived, in part, from immunosuppressive medications such as calcineurin inhibitors, corticosteroids, or mammalian target of rapamycin inhibitors. New onset diabetes mellitus after transplantation (NODAT) is a serious and common complication following solid organ transplantation. NODAT has been reported to occur in 2% to 53% of all solid organ transplants. Kidney transplant recipients who develop NODAT have variably been reported to be at increased risk of fatal and nonfatal cardiovascular events and other adverse outcomes including infection, reduced patient survival, graft rejection, and accelerated graft loss compared with those who do not develop diabetes. Identification of high-risk patients and implementation of measures to reduce the development of NODAT may improve long-term patient and graft outcome. The following article presents an overview of the literature on the current diagnostic criteria for NODAT, its incidence after solid organ transplantation, suggested risk factors and potential pathogenic mechanisms. The impact of NODAT on patient and allograft outcomes and suggested guidelines for early identification and management of NODAT will also be discussed.

Cause of death with graft function among renal transplant recipients in an integrated healthcare system

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in renal transplant recipients with a functioning allograft. Modification of CVD risk factors may, therefore, decrease overall mortality in this patient population. We studied renal transplant recipients within an integrated healthcare system (IHS) that uses case management and electronic health records to determine mortality from CVD.

METHODS

We retrospectively collected data on all renal transplant recipients over a 10-year period. The primary endpoint was death with graft function (DWGF). Cardiovascular events were used as secondary endpoints. We determined the cause of death and collected laboratory data. The data were analyzed using Student's t test for continuous data, chi square for categorical data, and multivariate logistic regression. Survival was determined using the Kaplan-Meier product-limit method.

RESULTS

Death from "other" causes accounted for 29%. This was followed by CVD (24%), infection (16%), and malignancy (12%). The most common "other" causes were diabetes mellitus and end-stage renal disease. Overall, lower hemoglobin, uncontrolled blood pressure, and lower albumin levels were associated with DWGF. There were 184 cardiovascular events in total. Low-density lipid levels were lower in the group with cardiovascular events and DWGF. The use of antihypertensive and antihyperlipidemic agents was similar between the two groups with the exception of diuretics, which were used more often in the DWGF group.

CONCLUSIONS

There was a low rate of DWGF because of CVD within this IHS. It is possible that coordinated care within an IHS leads to improved cardiovascular mortality.

Macrophage activation is associated with poorer long-term outcomes in renal transplant patients

Long-term graft and patient survival after renal transplantation are largely determined by progression of chronic allograft dysfunction and cardiovascular disease. Inflammation plays a crucial role in both disease processes. We prospectively analyzed the association of early peri-transplant inflammatory burden on long-term outcomes in 144 consecutive deceased donor renal allograft recipients. Single time point and cumulative levels of markers of acute phase response (serum amyloid A [SAA] and C-reactive protein [SCRP]) and macrophage activation (serum and urine neopterin) were measured daily during the immediate post-operative period. Mean patient follow-up was 16 yr. Graft and patient survival rates at one-, five-, and 10-yr were 90%, 70%, and 51%, and 97%, 77%, and 59%, respectively. Graft loss occurred in 90 patients, of whom 71 died with a functioning graft and 19 returned to dialysis. CRP, SAA and neopterin (NEOP) levels were all elevated post-operatively. High levels of NEOP, in contrast to SAA or SCRP, were associated with poorer graft and patient survival (p < 0.05), specifically with death from cardiovascular events and cytomegalovirus IgG positivity. These findings strongly suggest that early post-transplant macrophage activation, as reflected by NEOP levels, is associated with poorer long-term graft and patient survival.

Adiponectin is associated with cardiovascular disease in male renal transplant recipients: baseline results from the LANDMARK 2 study

BACKGROUND

Adiponectin is a major adipocyte-derived protein with insulin-sensitizing, anti-inflammatory and anti-atherogenic properties. Adiponectin levels correlate inversely with renal function and higher levels are predictive of lower cardiovascular disease (CVD) in patients with normal renal function and chronic kidney disease. No data exists on the association between adiponectin and CVD in renal transplant recipients (RTR).

METHODS

Standard biochemistry, clinical data and adiponectin were collected from 137 RTR recruited to the LANDMARK 2 study at baseline. The LANDMARK 2 study is an ongoing randomized controlled study that compares the outcome of aggressive risk factor modification for cardiovascular disease versus standard post-transplant care in renal transplant recipients with impaired glucose tolerance or diabetes mellitus.

RESULTS

Mean patient age was 53.4 +/- 12 years and the median post-transplantation period was 5 (0.5-31.9) years. Mean serum adiponectin level was 12.3 +/- 7.1 microg/mL. On univariate analysis, adiponectin was positively associated with female gender (P = 0.01) and serum high-density lipoprotein (HDL) concentration (P < 0.001), and inversely with body mass index (P = 0.009), metabolic syndrome (P = 0.047), abnormal glucose tolerance (P = 0.01), C-reactive protein (P = 0.001) and serum triglyceride (P < 0.001). On stepwise multivariate analysis, adiponectin in males was negatively correlated with combined baseline CVD (P = 0.03), waist-hip ratio (P = 0.003) and glomerular filtration rate (P = 0.046), and positively with HDL (P < 0.001). In contrast, in females adiponectin was inversely associated with C-reactive protein (P = 0.001) and serum triglyceride.

CONCLUSION

In conclusion, adiponectin is positively correlated with inflammation, dyslipidemia and abnormal glucose tolerance in RTR. Furthermore, hypoadiponectinemia correlated with increased baseline CVD in male RTR.

Minimization of maintenance immunosuppression early after renal transplantation: an interim analysis

INTRODUCTION

Chronic allograft nephropathy is the main cause of long-term renal transplant failure. Chronic use of calcineurin inhibitors contributes to its pathogenesis. Here, we report on a multicenter randomized trial to study the effects of withdrawal of cyclosporine A (CsA) from a triple immunosuppressive regimen containing CsA, prednisolone (P), and mycophenolate sodium (MPS) early after transplantation.

METHODS

Patients continued on P/CsA, P/MPS, or P and everolimus (EVL). Before withdrawal, a transplant biopsy was performed ensuring no subclinical rejection was present. Drug levels were closely monitored. The primary outcome was interstitial graft fibrosis and hyalinosis. Secondary outcome was among others graft rejection.

RESULTS

According to trial regulations, an interim analysis was performed after enrollment of half of the intended number of patients (n=113). Mean follow-up was 14+/-5 months from transplantation and 8+/-5 months from conversion. After conversion, acute rejection percentages were 3% in the P/CsA group, 22% in the P/MPS group, and 0% in the P/EVL group (P<0.009).

CONCLUSIONS

We conclude that switching immunosuppressive therapy from P/CsA/MPS to therapy with P/CsA or P/EVL at 6 months after renal transplantation is effective in preventing rejection. Double therapy with P/MPS after withdrawal of P/CsA resulted in an increase in severe acute rejection episodes. These results were the immediate reason to halt the P/MPS arm. Serum creatinine values at the latest follow-up (8+/-5 months after conversion and 14+/-5 months after transplantation) in the P/EVL group were lower than in the P/CsA group.

Effects of immunosuppressive drugs on platelet aggregation and soluble P-selectin levels in renal transplant patients

BACKGROUND/AIM

Post-transplant cardiovascular events are associated with increased morbidity and mortality after renal transplantation. Though renal transplantation eliminates cardiovascular disease risk factors by restoring renal function, it introduces new cardiovascular risks derived partly from immunosuppressive medications. In this study, to assess the effects of various immunosuppressive drugs on platelet function of renal transplant patients, we measured soluble P selectin levels (sP-selectin) and performed platelet aggregation studies in patients who have undergone renal transplantation.

METHODS

sP-selectin levels and platelet aggregation induced by 5 microM adenosine diphosphate (ADP), 5 microM epinephrine, 1.25 mg/mL ristocetin, and 2 microg/mL collagen were studied by whole blood platelet lumi-aggregometer in 40 renal transplant patients. Patients in group 1 (n = 24) were treated with cyclosporine/mycophenolate mofetil/methylprednisolone, and group 2 (n = 16) were treated with tacrolimus/mycophenolate mofetil/methylprednisolone. Effects were compared with those in control groups of hypertensive subjects and healthy subjects.

RESULTS

Platelet aggregation values induced by ADP, epinephrine, ristocetin, and collagen were lower in cyclosporine-treated patients than tacrolimus-treated patients, hypertensive subjects, and healthy subjects, though the difference was not statistically significant (p > 0.05). sP-selectin levels were appreciably higher in cyclosporine-treated patients, and statistically significant differences were observed compared with those of tacrolimus-treated patients (p < 0.05), hypertensive subjects (p < 0.01), and healthy subjects (p < 0.05).

CONCLUSION

We conclude that cyclosporine-treated renal transplant patients show enhanced platelet activation in which anti-platelet therapy should be considered, in addition to management of other conventional cardiovascular risk factors, to decrease the cardiovascular morbidity and mortality in this high risk population.

Survival benefit in heart transplant recipients who have coronary artery disease confirmed using angiography and are receiving sirolimus

INTRODUCTION

The aim of this study was to assess efficacy and safety of sirolimus (SIR) in heart transplant recipients to prevent further development of coronary artery disease (TxCAD) already confirmed by using coronary angiography.

MATERIAL AND METHODS

We performed a retrospective case-control study involving all 60 heart transplant recipients receiving SIR in a number of combinations with other immunosuppressive drugs, and 60 matched individuals after heart transplantation treated without SIR. TxCAD was diagnosed using elective coronary angiography in 9 subjects in the study group (8 males and 1 female) of mean age 44 +/- 11 years, including ischemic cardiomyopathy in 4 members. The control group of 15 individuals 15 males of mean age 47 +/- 7 years, including ischemic cardiomyopathy in 8. We compared time to develop significant TxCAD and death caused by TxCAD, and all-cause deaths. Significance was assessed using log-rank and chi-square tests, when applicable.

RESULTS

Significant TxCAD (critical coronary lesions, myocardial infarction or death) was observed in 5 (56%) patients receiving SIR and 11 (73%) without SIR (P = not significant [NS]). Time to develop significant TxCAD was comparable. There were 2 (22%) deaths in the SIR group and 8 (53%) in the control group (P = NS). Survival time was significantly longer among subjects receiving SIR (P = .02). None of deaths in the study group was caused by TxCAD compared with 6 (40%) deaths among controls (P = .09). Time of freedom from death caused by TxCAD was significantly longer in the study group (P = .023).

CONCLUSION

SIR prolonged survival in heart transplant recipients with TxCAD confirmed using coronary angiography.

Kidney transplantation decreases the level and procoagulant activity of circulating microparticles

Microparticles (MP) are important players in cardiovascular disorders. Renal transplantation significantly improves the survival of hemodialyzed patients, in part because cardiovascular disease (CVD) progression is lessened. We hypothesized that the beneficial effect of renal transplantation on cardiovascular outcome might involve decreased levels of circulating MP. We evaluated the kinetics of MP subpopulations and their procoagulant activity (MP-PCA) in 52 patients before and 3, 6, 9 and 12 months after graft with reference to 50 healthy controls and we evaluated the impact of cardiovascular complications. During the follow-up, the increased levels of MP observed before graft were significantly decreased and reached normal values with different kinetics according to their cellular origin whereas MP-PCA remained significantly higher than in controls. From multivariate analysis, the levels of MP were negatively correlated with renal function. At 12 months, the decrease in MP and MP-PCA was more pronounced in patients without history of CVD than those with. In conclusion, we demonstrated that renal graft is associated with decreased levels of MP levels and MP-PCA, even more pronounced so in patients without history of CVD. Therefore, we suggest that MP lowering could be involved in the vascular dysfunction improvements reported after transplantation.

Cardiovascular disease in transplant recipients: current and future treatment strategies

A cardiovascular disease event in a transplant recipient may be the result of a pretransplantation disease process, a direct effect of immunosuppressant medications, or the result of exposure to a variety of traditional and nontraditional risk factors after transplantation. Although the understanding of posttransplantation cardiovascular disease remains incomplete, there is evidence that the impact of posttransplantation cardiovascular disease has been decreased, through increased attention to this problem. In the absence of controlled studies to guide therapy, this review summarizes treatment of cardiovascular disease risk factors for which there is strong evidence of benefit in the nontransplantation setting, observational evidence of a similar risk in transplant recipients, and evidence that treatment can be safely administered to transplant recipients. Putative risk factors for posttransplantation cardiovascular disease for which the current level of evidence is insufficient to support specific treatment recommendations are also discussed. Potential new strategies to decrease the risk for cardiovascular disease events after transplantation in the future, including aggressive pretransplantation risk reduction, individualized treatments to prevent different types of cardiovascular disease, dedicated efforts to reduce cardiovascular disease events during transitions between dialysis and transplantation, and manipulation of immunosuppressant protocols, are also introduced.

New onset diabetes mellitus after solid organ transplantation

This article presents an overview of the literature on the current diagnostic criteria for new onset diabetes mellitus after transplantation (NODAT) and discusses suggested risk factors for the development of NODAT, its potential pathogenic mechanisms, and its impact on post-transplant outcomes after solid organ transplantation. Suggested guidelines for early identification and management of NODAT are also discussed.