Hypertension in kidney transplant recipients. Effect on long-term renal allograft survival

Dietary Approach to Stop Hypertension (DASH) diet and risk of renal function decline and all-cause mortality in renal transplant recipients

Renal transplant recipients (RTR) are at risk of decline of graft function and premature mortality, with high blood pressure as an important risk factor for both. To study the association of the Dietary Approach to Stop Hypertension (DASH) diet with these adverse events, we conducted a prospective cohort study of adult RTR. Dietary data were collected using a validated 177-item food frequency questionnaire and an overall DASH-score was obtained. We included 632 stable RTR (mean ± standard deviation age 53.0 ± 12.7 years, 57% men). Mean DASH score was 23.8 ± 4.7. During median follow-up of 5.3 (interquartile range, 4.1-6.0) years, 119 (18.8%) RTR had renal function decline, defined as a combined endpoint of doubling of serum creatinine and death-censored graft failure, and 128 (20.3%) died. In Cox-regression analyses, RTR in the highest tertile of the DASH score had lower risk of both renal function decline (hazard ratio [HR] = 0.57; 95% confidence interval [CI], 0.33-0.96, P = .03) and all-cause mortality (HR = 0.52; 95%CI, 0.32-0.83, P = .006) compared to the lowest tertile, independent of potential confounders. Adherence to a DASH-style diet is associated with lower risk of both renal function decline and all-cause mortality. These results suggest that a healthful diet might benefit long-term outcome in RTR.

Steroid avoidance or withdrawal after renal transplantation increases the risk of acute rejection but decreases cardiovascular risk. A meta-analysis

INTRODUCTION

The morbidity related to long-term steroid therapy has led to continued interest in withdrawal of steroids from immunosuppressant regimens after renal transplantation. A number of recent trials have provided long-term information regarding the risks and benefits of steroid avoidance or withdrawal (SAW).

METHODS

A literature search was performed using Ovid Medline, Embase, the Cochrane Library, and the Transplant Library. Randomized controlled trials comparing a maintenance steroid group with complete avoidance or withdrawal of steroids were selected. All studies were assessed for methodological quality. Trials were pooled by meta-analysis to provide summary effects (relative risk [RR] or weighted mean difference) with 95% confidence intervals (CI).

RESULTS

Thirty-four studies including 5,637 patients met the inclusion criteria. SAW regimens significantly increased the risk of acute rejection (AR) over maintenance steroids (RR 1.56, CI 1.31-1.87, P<0.0001). No significant differences in corticosteroid resistant AR, patient survival, or graft survival were observed. Serum creatinine was increased and creatinine clearance was reduced with SAW. Cardiovascular risk factors including incidence of hypertension (RR 0.90, CI 0.85-0.94, P<0.0001), new onset diabetes (RR 0.64, CI 0.50-0.83, P=0.0006), and hypercholesterolemia (RR 0.76, CI 0.67-0.87, P<0.0001) were reduced significantly by SAW.

CONCLUSION

Despite an increase in the risk of AR with SAW protocols, there is only a small effect on graft function with no measurable effect on graft or patient survival. There are significant benefits in cardiovascular risk profiles after SAW. SAW protocols would seem justified with current immunosuppressive protocols in low-risk recipients.

Hypertension after renal transplantation

Hypertension is a common and serious complication after renal transplantation. It is an important risk factor for graft loss and morbidity and mortality of transplanted children. The etiology of posttransplant hypertension is multifactorial: native kidneys, immunosuppressive therapy, renal-graft artery stenosis, and chronic allograft nephropathy are the most common causes. Blood pressure (BP) in transplanted children should be measured not only by casual BP (CBP) measurement but also regularly by ambulatory BP monitoring (ABPM). The prevalence of posttransplant hypertension ranges between 60% and 90% depending on the method of BP measurement and definition. Left ventricular hypertrophy is a frequent type of end-organ damage in hypertensive children after transplantation (50-80%). All classes of antihypertensive drugs can be used in the treatment of posttransplant hypertension. Hypertension control in transplanted children is poor; only 20-50% of treated children reach normal BP. The reason for this poor control seems to be inadequate antihypertensive therapy, which can be improved by increasing the number of antihypertensive drugs. Improved hypertension control leads to improved long-term graft and patient survival in adults. In children, there is a great potential for antihypertensive treatment that could also result in improved graft and patient survival.

Improved control of hypertension in children after renal transplantation: results of a two-yr interventional trial

Hypertension is a frequent complication in children after renal transplantation and the control of post-transplant hypertension is unsatisfactorily low. The aim of this prospective interventional study was to improve the control of hypertension in children after renal transplantation. Thirty-six children fulfilled the inclusion criteria (> or =6 months after transplantation and no acute rejection in the last three months). BP was measured using ABPM. Hypertension was defined as mean ambulatory BP > or =95th-centile for healthy children and/or using antihypertensive drugs. The study intervention consisted of using intensified antihypertensive drug therapy - in children with uncontrolled hypertension (i.e., mean ambulatory BP was > or =95th centile in treated children), antihypertensive therapy was intensified by adding new antihypertensive drugs to reach goal BP <95th centile. ABPM was repeated after 12 and 24 months. Daytime BP did not change significantly after 12 or 24 months. Night-time BP decreased from 1.57 +/- 1.33 to 0.88 +/- 0.84 SDS for systolic and from 1.10 +/- 1.51 to 0.35 +/- 1.18 SDS for diastolic BP after 24 months (p < 0.05). The number of antihypertensive drugs increased from 2.1 +/- 0.9 to 2.7 +/- 0.8 drugs per patient (p < 0.05), this was especially seen with the use of ACE-inhibitors (increase from 19% to 40% of children, p < 0.05). In conclusion, this interventional trial demonstrated that, in children after renal transplantation, the control of hypertension, especially at night-time, can be improved by increasing the number of antihypertensive drugs, especially ACE-inhibitors.

Effect of Hypertension on Transplant Kidney Function: Three Year of Follow-up

BACKGROUND

Hypertension significantly increases the risk for chronic graft loss and accelerates the deterioration of transplanted kidney function. Aggressive control of blood pressure (BP) is recommended in the posttransplant period when maintenance levels of immunosuppressive drugs are achieved. The aim of this study was to investigate whether the improved control improved the graft survival.

METHODS

We compared transplant kidney function in two groups of hypertensive patients matched for age, gender, donor-recipient relation, primary disease, early posttransplant course, and immunosuppressant and hypertensive therapy during 3 years follow-up. The patients were divided into satisfactory and unsatisfactory controlled blood pressure. Group 1 consisted of 98 patients with satisfactory BP control (arterial pressure <160/90 mmHg) and group 2, 98 patients with unsatisfactory BP control.

RESULTS

The mean through levels of cyclosporine in whole blood were similar in both groups and did not exceed 185 ng/mL. A slow but significant increase in mean creatinine levels was observed among group 2 during 3 years follow-up, whereas, among group 1, graft function remained stable. Cardiovascular events were observed only in group 2: stroke in one patient and death because of heart failure in one patient. Factors which correlated with development of post transplant hypertension were age, gender, duration of disease before transplant, and underlying disease.

CONCLUSION

Lowering BP, even several years posttransplantation, was associated with improved graft and patient survival in renal transplant recipients.

The aetiology and pathogenesis of chronic allograft nephropathy

Renal transplantation is the ultimate form of renal replacement therapy, and is the treatment of choice for many patients with end-stage renal failure. The advent of calcineurin inhibitor based immunosuppression resulted in the 1-year renal allograft failure rate dropping from around 50% twenty years ago to less than 10% in more recent times. Despite a massive improvement in renal allograft survival in the first year following transplantation 10-year graft survival can be as low as 50%. Chronic allograft nephropathy (CAN) is recognised as the main cause of renal allograft failure following the first year after transplantation. The diagnosis of CAN can only be made histologically. Typically biopsy specimens in grafts with CAN demonstrate an overall fibrotic appearance effecting the vascular endothelium, renal tubules, interstitium, and glomerulus. The risk factors for CAN are divided into alloimmune and alloimmune independent. Alloimmune dependent factors include acute cellular rejection, severity of rejection, subclinical rejection and HLA mismatch. Alloimmune independent factors such as delayed graft function, donor age, Cytomegalovirus infection, donor/recipient co-morbidity and of course calcineurin inhibitor toxicity are important in the development of CAN. The pathogenesis of CAN is complex, multifactorial, and unfortunately incompletely understood. There are a number of pivotal steps in the initiation and propagation of the fibrosis seen in biopsy specimens from kidneys with CAN. Endothelial activation in response to one or more of the aforementioned risk factors stimulates leukocyte activation and recruitment. Recruited leukocytes subsequently infiltrate through the endothelium and induce key effector cells to secrete excessive and abnormal extracellular matrix (ECM). Enhanced deposition of ECM is a histological hallmark of CAN. This paper aims to present a concise yet accurate and up-to-date review of the literature concerning the aetiological factors and pathological processes which are present in the generation of CAN.

Chronic allograft nephropathy

With the advent of calcineurin inhibitors, the success of kidney and other solid-organ transplants has improved significantly from the standpoint of reducing the incidence of acute rejection. Over the past 2 decades, both short-term allograft survival and acute rejection rates have dramatically improved with improved diagnostic and therapeutic techniques such as standardized pathology scoring; potent antirejection drugs such as anti-thymocyte globulin, interleukin-2 receptor antibodies, cyclosporine, tacrolimus, sirolimus, and mycophenolate mofetil; and improved infection control such as valganciclovir and antifungal therapy. However, long-term graft loss has remained at nearly constant levels over the same period of time, with the average half-life of a deceased-donor kidney transplant in the United States remaining approximately 1 decade. In addition to death with a functioning allograft and calcineurin toxicity, a chronic fibrotic process-known at various times as chronic rejection, chronic allograft dysfunction, and chronic allograft nephropathy (CAN)-account for the leading causes of transplant failure.

Polymorphism of the renin-angiotensin-aldosterone system in patients with chronic allograft dysfunction

Polymorphism of the gene encoding components of the renin-angiotensin-aldosterone synthase system (RAAS) represents an area of intense research of cardiovascular disease associations. Numerous studies have addressed the role of RAAS gene polymorphisms in the development and progression of renal disease. Also, it has been reported that patient with ACE (DD) and angiotensinogen AGT (TT) genotypes are associated with chronic allograft dysfunction (CAD). We investigated the effects of gene polymorphisms of the renin-angiotensin-aldosterone system in renal transplant patients (81 males and 50 females; mean age 29.6+/-10.2 years). Genotypes were determined using polymerase chain reaction sequence specific primers and PCR followed by RFLP analysis. Renal allograft recipients with chronic allograft dysfunction had significantly higher frequencies of the MM genotype than those without CAD (P<0.05). The other genetic polymorphisms of the RAAS were not associated with CAD. This study proves that determination of AGT M235T genotype before transplantation may help identify patients who are at risk for chronic renal transplant dysfunction.

Pathomechanisms and the diagnosis of arterial hypertension in pediatric renal allograft recipients

Arterial hypertension is common in pediatric renal allograft recipients. While the causes are multifactorial, including chronic graft rejection, immunosuppressive therapy, and renal vascular disorders, the effect of hypertension on renal allograft function is detrimental. As in adults, if not treated early and aggressively, hypertension may lead to cardiovascular damage and graft failure. Pathophysiological changes in the arteries and kidney af-ter renal transplantation and the impact of receptor regulation have not been studied extensively in children. For identifying children with hypertension following renal transplantation casual blood pressure measurements do not accurately reflect average arterial blood pressure and circadian blood pressure rhythm. Ambulatory 24-h blood pressure monitoring should regularly be applied in trans-plant patients. The purpose of this review is to analyze pathophysiological aspects of risk factors for arterial hypertension and underline the importance of regular blood pressure monitoring and early therapeutic intervention.

Immunotoxin-treated rhesus monkeys: a model for renal allograft chronic rejection

BACKGROUND

Unlike acute and hyperacute rejection, chronic rejection (CR) still constitutes a poorly understood process. The onset is insidious, occurs in a period of months to years and, because the pathophysiology is not well understood, is untreatable. A reliable large-animal model for renal allograft CR is needed and has not been reported in the literature yet.

METHODS

CR biopsy changes were studied in major histocompatibility complex-mismatched renal allografts performed in nine rhesus monkeys that received CD3 T-lymphocyte depletion therapy with immunotoxin on the day of the transplantation (n=7) or 7 days before transplant (n=2).

RESULTS

Mean graft survival time was 613.77 days. Biopsy changes of CR were identified as soon as 84 days after transplant (mean, 336 days; range, 84-896 days). Most of the experimental animals had severe interstitial fibrosis, tubular atrophy, chronic transplant glomerulopathy, and chronic vascular rejection changes at the time of necropsy. A significant positive correlation between the severity of CR and the degree of CD68+ macrophage infiltrate of renal parenchyma and the degree of anemia and serum creatinine level elevations were also observed.

CONCLUSIONS

Our findings are similar to those seen in human renal chronic allograft nephropathy, but in contrast, our model excludes all the nonimmune factors associated with chronic allograft nephropathy, including donor disease, injury from prolonged preservation, drug toxicity, and underlying recipient disease. Immunotoxin-treated rhesus monkeys emerge as an outstanding animal model for assisting us in understanding the pathophysiology of CR.

Early posttransplantation hypertension and poor long-term renal allograft survival in pediatric patients

OBJECTIVE

To evaluate the effect of early hypertension on long-term allograft survival in children with kidney transplantation.

STUDY DESIGN

Data from a total of 159 patients (mean age, 12.8+/-4.8 years) who underwent kidney transplantation between 1978 and 1998 and whose allograft was functioning for at least 1 year were analyzed retrospectively. Patients were divided according to the presence of hypertension within the first year after transplantation. Primary outcome was time of allograft failure (death, return to dialysis, or retransplantation).

RESULTS

Kaplan-Meier analysis showed that systolic (P<.0001) and diastolic (P=.016) hypertension was associated with overall worse allograft survival. Children with systolic hypertension had a significantly higher graft failure rate regardless of the type of donor, cause of kidney failure, presence or absence of acute rejection, and allograft function at 1 year after transplantation. The multivariate Cox regression model proved that systolic hypertension was a significant and independent risk factor for poor graft survival (hazard ratio [HR], 1.79; P<.0001). Other predictors included allograft function at 1 year after transplantation (HR, 0.97; P<.0001), acquired cause of end-stage kidney disease (HR, 1.96; P=.01) and age <6 years (HR, 2.61; P=.045).

CONCLUSIONS

Early posttransplantation systolic hypertension strongly and independently predicts poor long-term graft survival in pediatric patients.

Hypertension increases expression of growth factors and MHC II in chronic allograft nephropathy

BACKGROUND

Hypertension of the recipient is strongly associated with chronic allograft nephropathy. It is unclear, however, whether hypertension is the cause or the consequence of chronic allograft nephropathy.

METHODS

The present study was performed in the Fisher to Lewis rat kidney transplant model. Transplanted rats (N = eight in each group) received either no treatment or were made hypertensive by administration of deoxycorticosteron acetate (DOCA) and salt. Proteinuria and systolic blood pressure was measured monthly, grafts were harvested at 3 and 6 months for semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and for immunohistology.

RESULTS

Systolic blood pressure was markedly elevated in rats receiving DOCA/salt. Allografts of hypertensive animals contained significantly more cells expressing the proliferating cell nuclear antigen compared to isografts and to allografts from normotensive animals (P < 0.05). Histologic staining and mRNA expression of major histocompatibility complex (MHC) II was markedly increased in allografts of hypertensive animals compared to all other groups (P < 0.05). Expression of mRNA for platelet-derived growth factor-B (PDGF-B), transforming growth factor-beta (TGF-beta) and collagen was higher in allografts than in isografts and was highest in hypertensive animals.

CONCLUSION

We conclude that hypertension augments the expression of growth factors in the allograft possibly aggravating the intimal hyperplasia observed in chronic allograft nephropathy. By increasing the expression of MHC II antigens, hypertension may render the allograft more susceptible to alloantigen-dependent damage. Hypertension and alloantigen-dependent factors appear to exert additive or synergistic effects on inflammatory pathways leading to graft injury.

Molecular mechanisms of renal allograft fibrosis

BACKGROUND

Chronic graft nephropathy (CGN) remains the leading cause of renal allograft loss after the first year following transplantation. Histologically it is characterized by glomerulosclerosis, intimal hyperplasia and interstitial fibrosis. The pathogenesis is unclear, but is likely to involve both immunological and non-immunological factors. Despite improvements in short-term graft survival rates, new immunosuppressive regimens have made no impact on CGN.

METHODS

A review of the current literature on renal transplantation, novel immunosuppression regimens and advances in the molecular pathogenesis of renal allograft fibrosis was performed.

RESULTS AND CONCLUSION

Recent advances in understanding of the underlying molecular mechanisms involved suggest autocrine secretion of cytokines and growth factors, especially transforming growth factor beta, are associated with a change in fibroblast phenotype leading to the deposition of extracellular matrix. Repeated insults trigger upregulation of the tissue inhibitors of matrix metalloproteinases, favouring accumulation of extracellular matrix. To date, no drug has proved effective in inhibiting or reducing allograft fibrosis. The deleterious consequences of chronic immunosuppression on the development of such fibrosis are now recognized; newer immunosuppressive drugs, including rapamycin and mycophenolate mofetil, reduce profibrotic gene expression in both experimental and clinical settings, and offer potential strategies for prolonging allograft survival.

Hypertension after renal transplantation

With current immunosuppression, elevated blood pressure is found in almost 90% of renal graft recipients. Major causes of this are impairment of renal function (secondary to chronic allograft nephropathy or less frequently recurrence of primary renal disease), the use of calcineurin inhibitors as immunosuppressants, uncontrolled renin secretion by the shrunken kidneys of the recipient, stenosing lesions of the transplant artery (or the upstream arteries of the recipient), polycythemia, and genetic predisposition to hypertension of the graft donor. Even minor degrees of blood pressure elevation have a significant impact on survival of the recipient and on graft survival, presumably by amplifying vascular injury to the graft. In this respect, elevation of systolic blood pressure and an abnormal circadian blood pressure profile are of particular relevance. In contrast to previous opinion, angiotensin converting enzyme inhibitors are indicated in treatment, but given the causal role of sodium retention and graft vasoconstriction, diuretics and calcium channel blockers remain mainstays of antihypertensive treatment in the renal allograft recipient.

Tolerance and chronic rejection

The most common cause of chronic allograft loss is an incompletely understood clinicopathological entity called chronic rejection (CR). Recent reports suggest an improvement in long-term renal allograft survival, although it is not clear from these data whether a true reduction of biopsy-proven CR has occurred. Although newer immunosuppressive medications have greatly reduced the incidence of acute rejection (AR) in the early post-transplantation period, the ideal therapy for both AR and CR would be to achieve a state of tolerance. By definition, such a state should allow for indefinite allograft survival, with no histopathological evidence of CR, despite immunocompetence in the host (i.e. without the need for chronic immunosuppression). Although several experimental studies are able to achieve tolerance, with clear improvement in allograft survival, detailed studies on graft function and morphology are often not included. This review will discuss possible ways that tolerance induction could lead to a CR-free state. General mechanisms of CR and transplantation tolerance induction are discussed as well as the difficulties in translating small animals studies into large animals and humans.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

How aggressively should blood pressure be treated in renal transplant recipients?

Renal transplantation is the treatment of choice for many patients with endstage renal disease. Patient survival is improved compared with dialysis for all patient ages and racial groups. Renal allograft survival is closely connected with recipient blood pressure. Blood pressure treatment goals that improve patient outcome have been defined for patients with nontransplant renal disease but not for patients with renal transplants. Extrapolating from data from nonrenal transplant patients suggests that aggressive treatment of hypertension in renal transplant patients may improve allograft and patient survival.

Renin-angiotensin system gene expression in post-transplant hypertension predicts allograft function

BACKGROUND

Registry analyses and single-center studies have demonstrated that hypertension significantly increases the risk for chronic graft loss. The graft itself may contribute to posttransplant hypertension, and intragraft vasoactive hormones therefore, may be dysregulated in posttransplant hypertension.

METHODS

We used the reverse-transcription polymerase chain reaction to assess the intragraft regulation of renin-angiotensin system transcripts in biopsy samples from 42 stable renal transplant patients with posttransplant hypertension. We also examined mRNA expression of inducible nitric oxide synthase, transforming growth factor-beta (TGF-beta), select cytokines, and metalloproteinase transcripts in biopsy tissue. Polymerase chain reaction products were quantitated using high performance liquid chromatography and normalized to beta-actin mRNA expression. Serum creatinine, glomerular filtration rate or creatinine clearance and tubular atrophy on biopsy were concurrently assessed.

RESULTS

Renin and select Thl cytokine mRNA expression correlated with blood pressure. Type 1 angiotensin II receptor mRNA expression significantly correlated with glomerular filtration rate or creatinine clearance (P = 0.034) and inversely correlated with Th1 cytokines, inducible nitric oxide synthase, and cyclooxygenase-1 mRNA expression (P< or =0.013 for each). Type 1 angiotensin II receptor mRNA also approached a significant inverse correlation with TGF-beta mRNA expression (P = 0.09). Conversely, angiotensin-converting enzyme mRNA expression directly correlated with Thl cytokine (P< or =0.008 for each) and TGF-beta mRNA expression (P = 0.006). Type 1 angiotensin II receptor mRNA expression also correlated with matrix metalloproteinase-1 promoter region, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and tissue inhibitor of matrix metalloproteinase-3 mRNA expression. Notably, matrix metalloproteinase-1 promoter region, tissue inhibitor of matrix metalloproteinase-2, and tissue inhibitor of matrix metalloproteinase-3 inversely correlated with TGF-beta mRNA expression (P< or =0.0027 for each). Type 1 angiotensin II receptor mRNA expression at biopsy directly correlated with glomerular filtration rate at 2 year's follow-up. However, angiotensin-converting enzyme mRNA expression at biopsy inversely correlated with glomerular filtration rate at 2 year's follow-up.

CONCLUSIONS

These data suggest that allograft-level RAS gene expression may be predictive of future graft function in the setting of diastolic hypertension.

Abnormal 24-hour blood pressure patterns in children after renal transplantation

Hypertension after renal transplantation occurs commonly and is associated with decreased allograft survival. Hypertension is usually diagnosed by casual blood pressure (BP) measurements in the outpatient clinic that may not reflect the overall 24-hour BP pattern. To better describe the pattern of BP in children after renal transplantation, 24-hour ambulatory BP monitoring (APBM) was performed in 42 patients with stable renal function. BP was measured every 20 minutes during the daytime and every 30 minutes at night. Mean patient age was 12.8 +/- 5.2 years, and mean time after transplantation was 34 +/- 36 months. Seventy-six percent of the patients were administered antihypertensive medications. Twenty-four-hour mean systolic BP (SBP) was 127 +/- 11 mm Hg, and diastolic BP (DBP) was 80 +/- 11 mm Hg. Mean 24-hour BP load values (percentage of BP readings > 95th percentile based on Task Force criteria) were 59% for SBP and 50% for DBP, which were significantly elevated compared with healthy children (P < 0.001). An attenuated decline in sleep BP (nondipping) was found in 78% of the patients for SBP and 50% for DBP. Sleep BP exceeded awake BP in 24% of the patients for SBP and 17% for DBP. Boys had a greater SBP load (66% versus 45%; P = 0.03) and DBP load (57% versus 38%; P = 0.04) than girls. These results confirm in children the high prevalence of hypertension by ABPM criteria after renal transplantation and show attenuation of normal sleep BP decreases. These BP disturbances may shorten renal allograft survival and predispose children to long-term hypertensive end-organ damage.

Use of anti-hypertensive medications and post-transplant renal allograft function in children

Post-transplant hypertension is a common occurrence in children. The relative effect of this hypertension on renal allograft function is uncertain. Examining the accumulated data for pediatric renal transplant recipients at our institution from monthly visits for up to three years, we determined whether the use of anti-hypertensive medications (anti-HTN medications) was associated with allograft dysfunction. Monthly clinical data included height, weight, serum creatinine, cyclosporin A (CsA) trough levels, number of acute rejection episodes, and number of anti-HTN medications. Estimated glomerular filtration rate (eGFR) was calculated monthly for each patient using the Schwartz formula. Time post-transplant was grouped into 6-month intervals. One thousand three hundred and sixty-three monthly data sets from 6 months (n = 76 patients) to 3 yr post-transplant (n = 47 patients) were analyzed. Overall mean eGFR was 75 mL/min/1.73 m2 at 6 months and 54 mL/min/1.73 m2 at 3 yr. A lower eGFR was found at all post-transplant time intervals for patients receiving anti-HTN medications compared with those who were not (p < 0.01). This lower eGFR was found at some but not all times post-transplant when patients were grouped by donor type or history of acute rejection episodes and analyzed separately. Mean CsA trough levels were higher at all post-transplant time intervals in patients receiving anti-HTN medications (p < 0.05). While a causal relationship between post-transplant hypertension and graft dysfunction cannot be established from this study, we conclude that the need for anti-HTN medications is associated with worse allograft function.

Carvedilol treatment of kidney graft recipients with chronic rejection

Carvedilol is an antihypertensive drug with properties that may be potentially beneficial for kidney graft recipients. The purpose of the study was to investigate if progression of an established chronic rejection may be attenuated or reversed by carvedilol. An open, single-centre, phase II, pilot study, with a 2-yr follow-up, was performed in 25 kidney graft recipients with chronic rejection or accelerated transplant atherosclerosis. Seventeen patients had stable graft function assessed by serum creatinine levels. Eight patients withdrew from the study due to lack of efficacy (increase in serum creatinine 174-477 micromol/L (46-191%) from the initial levels). However. these patients had higher serum creatinine levels and proteinuria already at the start of the study. Both systolic and diastolic blood pressure, as well as heart rate, were stable in all study patients. Low density lipoprotein (LDL)/high density lipoprotein (HDL) cholesterol ratio decreased from 4.7 +/- 1.9 at 1 month to 3.5 +/- 1.2 at 18 months (p < 0.05), and MDA plasma levels decreased from 0.714 +/- 0.119 to 0.493 +/- 0.073 micromol/L after 3 months of carvedilol treatment (p < 0.05). No attenuation of progression of chronic graft rejection by carvedilol treatment was observed in the study. It is suggested that the process of chronic rejection could not be reversed by carvedilol because the patients included in the study already had severe morphological and functional changes of the graft. In conclusion, our study demonstrated that carvedilol provides a good control of blood pressure in renal transplanted patients. Carvedilol treatment had a beneficial effect on lipid pattern and reduced lipid oxidation, but there was no obvious effect on progression of chronic rejection.

Antihypertensive medication and renal allograft failure: a North American Pediatric Renal Transplant Cooperative Study report

Hypertension after renal transplantation occurs commonly and, in adults, is associated with decreased graft survival. The North American Pediatric Renal Transplant Cooperative Study database was analyzed to determine: (1) the percent use of antihypertensive (anti-HTN) medication based on donor type, race, age, and acute rejection status; and (2) whether use of anti-HTN medication is associated with higher rates of subsequent graft failure. Data regarding anti-HTN medication use was available in 5251 renal allografts (4821 patients) with >30 d graft function. Posttransplant follow-up data were collected at 30 d, 6 mo, 12 mo, and then annually for 5 yr. At each follow-up, patients were selected for further analysis if the graft was functioning at that visit and subsequent follow-up data were available. Overall, anti-HTN medication use was 79% on day 30 and 58% at 5 yr. At each follow-up, anti-HTN medication use was higher (P < 0.01) for cadaveric donor versus living related donor, blacks versus whites, age >12 versus <12 yr, and > or = 1 versus 0 acute rejection episodes. Anti-HTN medication use at each annual follow-up was associated with significantly higher rates of subsequent graft failure. Multiple regression analysis controlling for all factors associated with increased use of anti-HTN medications revealed a relative risk of graft failure for use of anti-HTN medication of greater than 1.4 (P < 0.001). In recipients of cadaveric allografts, only acute rejection status predicted subsequent graft failure more strongly than use of anti-HTN medications. These data suggest that hypertension after renal transplantation in children, as evidenced by use of anti-HTN medications, is associated with increased rates of subsequent graft failure.

Early immunologic and nonimmunologic predictors of arterial hypertension after renal transplantation

We followed up a cohort of 680 renal transplant recipients receiving cyclosporine (CsA) immunosuppression with the aim of establishing an early-risk profile for early and late hypertension (HT) after renal transplantation (RTx), specifically comparing the predictive role of immunologic and nonimmunologic markers of graft prognosis. HT was defined as the need for antihypertensive drugs. The prevalence of HT was 65% at the time of RTx, increased to a peak of 78% at the end of the first year, and stabilized between 71% and 73% thereafter. Multivariate analysis identified HT at the time of RTx, basal renal disease, and grafting the right kidney as independent predictors of HT 3 months after RTx. The risk profile for HT 12 months after RTx included HT present at RTx, grafting the right kidney, markers of early ischemia-reperfusion injury (delayed graft function, cold and warm ischemia), and transplant from an elderly or female donor. Polytransfusion before RTx was associated with a decreased risk for HT, but retransplantation, increased reactivity against the lymphocyte panel, poor HLA compatibility, and early acute rejection did not portend an increased risk for the complication under study. The CsA schedule (dose, trough levels) correlated poorly with the blood pressure status of the patients, but simultaneous graft function was independently associated with late HT. In conclusion, the early predictive profile for HT after RTx includes, preferentially, nonimmunologic markers of graft prognosis. Hyperfiltration damage may be a significant pathogenic mechanism for this complication of RTx.

Antihypertensive drug treatment in chronic renal allograft rejection in the rat. Effect on structure and function

To gain insight into the contribution of immunologic and hemodynamic factors in the progressive demise of structure and function in chronic renal allograft dysfunction, we studied the histological changes, the immunostainable glomerular anionic sites, and glomerular capillary hydrostatic pressures of rat renal allografts with chronic rejection. Recipient animals were left untreated, received 8 weeks of treatment with the immunosuppressive drug cyclosporine, or received antihypertensive drugs consisting of the combination of reserpine, hydralazine and hydrochlorothiazide, the angiotensin-converting enzyme inhibitor cilazapril, or the angiotensin II receptor blocker L-158,809. Grafts in untreated recipients developed chronic interstitial inflammation, as well as vascular and glomerular lesions consistent with chronic rejection. These lesions were associated with immunohistochemical loss of the negatively charged heparan sulfate proteoglycan side chain. All treatment regimens decreased the systemic and glomerular capillary pressures and were associated with no loss of function, decreased proteinuria, and a tendency to improved graft function. Cyclosporine prevented all histological manifestations of rejection, and antihypertensive drugs decreased the extent of glomerular mesangiolysis and glomerulosclerosis; L-158,809 and cilazapril also inhibited graft atherosclerosis and tubular atrophy. We conclude that chronic rejection is primarily an immune-mediated process, but hemodynamic and angiotensin II-mediated effects may play a pivotal role in the expression of immune-mediated lesions.

Chronic renal allograft rejection: immunologic and nonimmunologic risk factors

The pathogenesis of chronic renal allograft rejection is unknown. It is also unclear why cyclosporine has failed to prevent chronic rejection. We examined possible risk factors for graft loss to chronic rejection among 706 renal transplants using the Cox proportional hazards model with fixed and time-dependent covariates. Both the number and the severity of acute rejection episodes were independent risk factors for chronic rejection [relative risk (95% confidence interval) 2.31 (2.04 to 2.60) and 1.53 (1.27 to 1.84), respectively]. Cyclosporine and cyclosporine withdrawal had no effect on chronic rejection. Acute rejections occurring within the first three months after transplantation, when cyclosporine most effectively prevented acute rejection, also had no effect on chronic rejection. Risk factors that were independent of acute rejection and not clearly attributable to immune mechanisms included serum albumin [0.20 (0.10 to 0.38) for each g/dl], proteinuria [1.42 (1.29 to 1.57) for each g/24 hr], and serum triglycerides -1.09 (1.03 to 1.16) for each 100 mg/dl-. These results suggest that the reduction in acute rejection episodes from cyclosporine has failed to reduce graft failure from chronic rejection, possibly because the early (within the first 3 months) and mild acute rejection episodes that are most effectively prevented by cyclosporine do not cause chronic rejection. In addition, the results suggest that there may be a number of nonimmunologic risk factors for chronic rejection.

Glomerular permselectivity in proteinuric patients after kidney transplantation

To characterize the defect in glomerular permselectivity responsible for proteinuria after renal transplantation, we studied 10 patients with moderate proteinuria (median 0.37 g/d, range 0.20-0.79), 16 patients with the nephrotic syndrome (6.73 g/d, 3.9-14.6), 8 living related donor transplant recipients without any history of rejection (median proteinuria 0.26 g/d, 0.06-0.58), and 12 healthy volunteers. The fractional clearance of neutral dextrans > 54 A was significantly higher in nephrotic patients, demonstrating a defect in glomerular size selectivity. Using a log-normal model of glomerular pore size distribution, r*(5%) and r*(1%), indices for the presence of large pores, were increased in the nephrotic patients. The fractional clearance of negatively charged dextran sulfate was significantly higher in all patient groups, indicating a loss of glomerular charge selectivity. Biopsy findings showed more prominent glomerular lesions in the nephrotic group compared with the moderately proteinuric group. We conclude that mild proteinuria late after renal transplantation is associated with a defect in glomerular charge selectivity. The development of nephrotic range proteinuria is associated also with a defect of glomerular size selectivity, which correlates with prominent glomerular pathology.

Hypertension two years after renal transplantation: causes and consequences

The incidence of hypertension 2 years after renal transplantation and the possible causes of hypertension were studied retrospectively. A group of 93 patients treated with cyclosporin (CyA), azathioprine (Aza), and/or prednisolone (Pred) were compared to a group of 31 patients treated with Aza and Pred. There were more patients with hypertension in the CyA group (73%) than in the Aza group (58%). Hypertension before transplantation predisposed to hypertension after transplantation. After transplantation, hypertension was most common among patients with polycystic kidney disease (46%), chronic glomerulonephritis (67%), and diabetes (71%). The accumulated immunosuppressive medication (CyA/Pred) did not affect the occurrence of hypertension. Hypertensive patients had significantly poorer graft function than did normotensive patients (serum creatinine level 229 mumol/l vs 162 mumol/l, P < 0.01). The 10-year graft survival was markedly impaired in the group with hypertension (42% vs 65% for normotensives, P < 0.05). The 10-year patient survival was 59% vs 79% (P = NS). The study further confirms the frequent finding that hypertension has a negative effect on graft and patient survival rates.

Chronic renal transplant loss

Chronic rejection results from recurrent episodes of subclinical or clinically evident acute rejection, with or without involvement of chronic rejection-specific allogeneic immune mechanisms. The tissue damage occurs over a prolonged period of time, which allows the emergence of antigen-independent tissue repair mechanisms and intrarenal adaptations in response to progressive loss of renal mass (Fig. 1). The combination of these mechanisms leads, very likely, to the tissue remodeling of chronic rejection. The heterogeneous expression of chronic rejection may result from different types and specificities of allogeneic immune reactions as well as different contributions of antigen-independent factors that modulate the antigen-dependent tissue responses to injury. The extent to which these mechanisms participate in the overall picture is presently unknown as immunological parameters are not measured routinely in the follow-up of patients with chronic graft dysfunction. Furthermore, some grafts may undergo tissue remodeling as a consequence of predominantly antigen-independent mechanisms. Therefore, the term chronic allograft dysfunction may clinically be preferable over chronic rejection to describe the gradual decline in graft function months or years after transplantation in the absence of a well-defined mechanism or an accepted treatment.

Hyperlipidemia accelerates allograft arteriosclerosis (chronic rejection) in the rat

The relevance of hyperlipidemia in allograft arteriosclerosis (chronic rejection) is controversial. Isolated hypercholesterolemia induced with cholesterol-cholic acid-diet (CC-diet) or hypertriglyceridemia induced with glycerol-diet (G-diet) had no or only a protective effect on aortic allograft arteriosclerosis in the rat. Combined hyperlipidemia with both diets (CC+G-diet) enhanced allograft arteriosclerosis by doubling intimal thickness and cellularity (P < .05) but had no effect on host arteries. Compared with normolipidemic controls, the CC+G-diet increased the total serum cholesterol concentration 4.8-fold (P < .05). Levels of VLDL2 and IDL increased 4.8- and 18.1-fold (P < .05), and their composition changed from triglyceride-rich to cholesterol-rich lipoproteins in an atherogenic direction. The CC+G-diet had no effect on the structure of inflammation in the vascular wall. Instead, significant lipid deposits were observed, and the expression of epidermal growth factor and insulin-like growth factor-1 was significantly elevated in the vascular wall. Thus, elevations in VLDL and IDL lipoprotein levels and their cholesterol content associate with the generation of allograft arteriosclerosis in rats. Deposition of lipids in the vascular wall seems to induce local synthesis of certain growth factors, which ultimately leads to the induction of smooth muscle cell replication.

Laparoscopic bilateral nephrectomy for renin-mediated hypertension

Hypertension arising from retained native kidneys complicates the management of recipients of renal transplants. Reluctance to administer angiotensin-converting enzyme inhibitor (ACEI) drugs to patients taking cyclosporine has reopened the question of performing native nephrectomies for poorly controlled, renin-dependent hypertension. We report the first published cases of simultaneous bilateral laparoscopic nephrectomies in 2 patients: 1 in preparation for living-related donor transplantation and the other ten months following cadaver transplantation in a patient whose end-stage renal disease was from malignant nephrosclerosis. Both had very severe hypertension resistant to multiple drugs and both became normotensive with little or no antihypertensive medication following nephrectomies. A bilateral nephrectomy is currently feasible using a laparoscopic approach.

Fosinopril prevents hyperfiltration and decreases proteinuria in post-transplant hypertensives

Hypertension and renal mass reduction induce glomerular hypertension (GH), hyperfiltration (HF) and renal injury. GH may contribute to allograft loss in post-transplant hypertensive patients (PT x HT). HF and GH may be evaluated by renal response to acute protein intake (API). Since ACE inhibition may prevent GH, the effects of fosinopril (Fos) were evaluated in 10 PT X HT on azathioprine and prednisone. Patients received 5 to 40 mg/day of Fos during 12 months. Baseline MAP (111.1 +/- 2.9 mm Hg) was significantly reduced by 10 to 12 mm Hg, rising to 114.7 +/- 2.7 mm Hg after Fos was administered. GFR (63.7 +/- 5.9 ml/min) decreased after 4 (48.1 +/- 4.6, P less than 0.05) and 12 months (50.7 +/- 4.6, P less than 0.05), rising to 59.4 +/- 5.6 after Fos was given. There was no GFR response to API before and after one month of Fos, however, a clear response became apparent at 4 (+ 27% P less than 0.05), and 12 months (+ 18%, P less than 0.05), disappearing after Fos discontinuation. Proteinuria (918.8 +/- 710.6 mg/d) decreased after 4 (72.3 +/- 21.6 mg/d, P less than 0.05) and 12 months, rising to 297.8 +/- 172.3 mg/day after therapy. GFR response to API in 22 controls and 17 uninephrectomized donors was 13 and 11%, respectively. Lack of response to API in PT x HT suggests HF and GH. Reduction of GFR, restoration of response to API and reduction of proteinuria, indicate that ACE inhibition with fosinopril ameliorates HF and GH. This effect may be beneficial in preventing hemodynamic-mediated allograft injury.