Factors affecting renal allograft function in long-term recipients

The Effect of a 26-Hour Fast in Living Kidney Donors

BACKGROUND

Living kidney donation is widely practiced, and short- and long-term outcomes are acceptable. Within the living kidney donor population there are unique ethnic groups who practice customs that affect kidney function. In Judaism, Yom Kippur (Day of Atonement) is a 25- to 26-hour fast practiced yearly. There are no studies describing the effect of this fast on LKDs.

METHODS

Living kidney donors were approached via e-mail. Exclusion criteria were conditions considered prohibitive of fasting. Control participants were potential living kidney donors approved by the standard medical evaluation but that had not yet donated. Blood and urine samples were obtained at 3 time points: baseline: 3 months before fast; fasting: 1 hour after fast; and follow-up: 14 days after fast.

RESULTS

In total, 85 living kidney donors and 27 control participants were included. Donors were older (42.8 vs 38.8 years) and had a higher baseline creatinine (103 vs 72 umol/L). All other parameters were the same. The percent change between fasting and nonfasting creatinine was smaller in living kidney donors than in control participants (0.12% vs 0.21% change, P = .04). Values of sodium, albumin, and osmolarity were not different between groups. Time from donation did not influence results.

CONCLUSIONS

Living kidney donors practicing a day fast showed a different pattern regarding the change in creatinine levels. This pattern cannot be considered hazardous for living kidney donors. The emotional wellbeing of living kidney donors is of utmost importance, and this first report of the safety of a 24-hour fast is reassuring. These findings may be of interest to other religious groups, for example, the Muslim community which observes Ramadan.

Diet-induced increase in plasma oxidized LDL promotes early fibrosis in a renal porcine auto-transplantation model

BACKGROUND

In kidney transplantation, the prevalence of hypercholesterolemia as a co-morbidity factor known to affect graft function, is rising due to the increased number of older donors in response to organ shortage as well as to the hyperlipidemic effects of immunosuppressors in recipient. This study aimed to characterize the effects of hypercholesterolemia on renal graft outcome, investigating the role of oxidized low-density lipoprotein (OxLDL).

METHODS

In vivo, we used a porcine preclinical model of renal auto-transplantation modulated by two experimental diets: a normal (n = 6) or a hyperlipidemic diet (n = 5) maintained during the 3 month follow-up after the surgical procedure. Kidney function and OxLDL levels were monitored as well as fibrosis, LOX-1 and TGF beta signaling pathways. In vitro, we used human artery endothelial cells subjected to OxLDL to investigate the TGF beta profibrotic pathway and the role of the scavenger receptor LOX-1.

RESULTS

Hyperlipidemic diet-induced increase in plasma OxLDL levels at the time of surgery correlated with an increase in proteinuria 3 months after transplantation, associated with an early graft fibrosis combined with an activation of renal TGF beta signaling. These data suggest a direct involvement of OxLDL in the hyperlipidemic diet-induced activation of the pro-fibrotic TGF beta pathway which seems to be activated by LOX-1 signaling. These results were supported by studies with endothelial cells incubated in culture medium containing OxLDL promoting TGF beta expression inhibited by LOX-1 antibody.

CONCLUSIONS

These results implicate OxLDL in the hyperlipidemic diet-promoted fibrosis in transplanted kidneys, suggesting LOX-1 as a potential therapeutic target and reinforce the need to control cholesterol levels in kidney transplant recipients.

Living or deceased donor kidney transplantation: a comparison of results and survival rates among Iranian patients

OBJECTIVE

Kidney transplantation is the selective treatment of end-stage renal disease. Although most previous studies have concluded that living kidney donation achieves better graft survival, some factors may limit this type of donation. This study investigated the survival rates of living and deceased donor kidney transplantations among Iranian patients.

MATERIALS AND METHODS

The records of kidney transplantations up to year 2005 were used to compare 50 deceased (group I) with 50 living donor transplants (group II). The recipients were matched by transplantation time. We used SPSS version 15 software to analyze the data.

RESULTS

Group I patients included 28 males and 22 females of mean age of 38 +/- 13 years, while 26 males and 24 females in group II had a mean age of 34.6 +/- 14 years. The rejection and graft nephrectomy rates were significantly higher among group I than group II (P = .01, P = .02). The first-year graft survival was higher in group II (P = .001). The graft survival was significantly lower in recipients who needed a biopsy or dialysis (P = .006 and P = .02, respectively) and higher among those who had a urine volume >4200 mL within the first 24 hours after transplantation (P = .003). Patient survivals were not significantly different between the groups.

CONCLUSION

Living donor kidney transplantations showed higher graft survival and lower acute rejection rates compared with those from deceased donors.

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.

Open prospective multicenter study of conversion to tacrolimus therapy in renal transplant patients experiencing ciclosporin-related side-effects

The hyperlipidemic and hypertensive effects of ciclosporin constitute a cardiovascular risk. Cosmetic side-effects are known to reduce patients' quality of life. This was a 6-month, open, prospective, multicentre study in 296 adult kidney transplant patients to evaluate the conversion from ciclosporin to a tacrolimus-based regimen. Primary indications for conversion were hyperlipidemia (n =77), hypertension (n = 72), hypertrichosis (n = 32) and gingival hyperplasia (n = 115). At month 6, hyperlipidemia and hypertension were at least moderately improved in 59.1% and 63.5% of patients, and strongly or completely resolved in 29% and 25%. Gingival hyperplasia and hypertrichosis were strongly or completely resolved in 73% and 72% of patients. Mean total cholesterol was reduced from 255 to 218 mg/dl. Mean systolic blood pressure (SBP) was reduced from 152.9 to 137.5 mmHg and mean diastolic blood pressure (DBP) from 90.7 to 85.8 mmHg. Ciclosporin-related side-effects resolved or improved after conversion to tacrolimus.

Improved Attainment of NKF Classified Lipid Target Levels After Conversion From Cyclosporine to Tacrolimus in Renal Graft Recipients

In an open, prospective, multicenter study, stable renal graft recipients were converted to tacrolimus because of cyclosporine-related side effects. Seventy-five patients were switched primarily because of hyperlipidemia. After the switch to tacrolimus, mean total cholesterol was reduced by 15% at month 6. One hundred seventy-seven additional patients were switched primarily for other indications: hypertrichosis, gingival hyperplasia, and arterial hypertension, and these symptoms also improved after the switch. In this analysis, serum lipid levels were categorized according to a modified standard classification of lipid parameters for renal transplant patients (published by the NKF Work Group). The aim was to estimate the proportion of patients reaching normal lipid levels after the conversion to tacrolimus therapy. In patients with primary indication hyperlipidemia, the proportion with normal cholesterol levels increased significantly from 5.6% at baseline to 37.5% at month 6 (P < .05). For LDL cholesterol, the increase was from 54.1% at baseline to 64.9% at month 6, and for triglycerides the improvement was from 25.4% to 33.8%. HDL cholesterol levels remained stable. Similar changes of lipid parameters were also observed in the subgroups of patients converted to tacrolimus primarily because of other indications. After conversion from cyclosporine to tacrolimus, a significantly higher proportion of stable renal graft recipients reached normal total cholesterol levels. For LDL cholesterol and triglycerides, a trend for normalization was observed. Thus, the improvement of serum lipid levels resulted for many patients in a change to a better level class and improved or normalized their cardiovascular risk parameters.

Prognostic factors affecting graft and patient survival in cadaveric and living kidney transplantation

Numerous studies have reported various prognostic factors that affect graft and patient survival in living and cadaveric donor kidney transplantation (KT). The purpose of this study was to evaluate the clinical outcomes and prognostic factors affecting graft and patient survivals in living and cadaveric donor KT. Between February 1995 and December 2001, 421 patients who had undergone cadaveric donor KT (group I: 216 cases, 51.3%) or living donor KT (group II: 205 cases, 48.7%), were retrospectively analyzed. Five-year overall graft survival rates in living was significantly better than that in cadaveric donor KT, respectively (P = .0234). There was no difference in patient survival rates between the two groups. Such factors as absence of rejection, female donor, female recipient, adult KT according to recipient age (>14 years), and donor serum creatinine level just before transplantation (< 2.5 mg/dL) were significantly associated with good graft survival among cadaveric donor KT, whereas two factors-absence of rejection and adult KT according to recipient age (>14 years)-influenced graft survival in living donor KT. In multivariate analysis, the only significant prognostic factor related to graft survival was the presence of rejection. In conclusion, we suggest that the presence of rejection is the only factor that impairs graft survival in both cadaveric and living donor KT, while other factors affected graft survival differently in the two groups.

Disease progression and outcomes in chronic kidney disease and renal transplantation

BACKGROUND

It is unknown whether renal transplant recipients (RTR) have better outcomes and disease progression rates compared to patients with chronic kidney disease (CKD) when matched for the level of kidney function.

METHODS

We analyzed data on 1762 patients with CKD (N = 872) and RTR (N = 890) over 16 years, applying the new Kidney/Disease Outcomes Quality Initiative (K/DOQI) staging system for CKD in a single center retrospective study. Patients were further divided based their native kidney disease. We determined disease progression by the slope of creatinine clearance decline and patient and kidney survival rates adjusted for age, gender and stage of kidney function, using Cox proportional hazards models.

RESULTS

The overall rate of creatinine clearance decline in patients with CKD was -6.6 +/- 8.7 mL/min/year compared to -1.9 +/- 4.7 mL/min/year in RTR (P < 0.0001). The rate of decline per stage of CKD was also significantly lower in RTR. Whereas overall kidney survival was higher in RTR compared to patients with CKD (49.6% vs. 17.2%, respectively, P < 0.001), patient survival was not statistically different between the two groups (74.7% vs. 80.3%, respectively, P = 0.25).

CONCLUSION

RTR had similar mortality rates compared to patients with CKD despite enjoying slower rates of disease progression and better kidney survival rates. These data suggest that RTR are a unique subset of patients with CKD whose comorbid conditions likely offset the potential benefits of slower rates of progression.

Hyperlipidemia in pediatric kidney transplant recipients treated with cyclosporine

Hyperlipidemia is a risk factor for cardiovascular disease in adult kidney transplant (Tx) recipients. We sought to determine the prevalence of, and the risk factors associated with, hyperlipidemia in pediatric kidney Tx recipients on cyclosporine (CsA). We identified 59 patients (mean age 8.2+/-5.7 years) transplanted between 1 January 1991 and 31 December 1993. Pre Tx, 34% had elevated total cholesterol [TC >200 mg/dl (5.17 mmol/l)]; 54% had elevated triglycerides [TG >200 mg/dl (2.26 mmol/L)]. Mean TG was higher pre Tx in dialysis (versus nondialysis) patients: 306 mg/dl (3.46 mmol/l) versus 228 mg/dl (2.58 mmol/l) ( P=0.04). Mean TC was higher in peritoneal dialysis than hemodialysis patients: 222 mg/dl (5.74 mmol/l) versus 169 mg/dl (4.37 mmol/l) ( P=0.03). Pre Tx and 3-year values correlated (TC, r=0.49, P=0.0008; TG, r=0.41, P=0.001); 3- and 5-year TC values correlated ( r=0.57, P=0.003). At 5 years post Tx, 41% of the recipients had elevated TC; 14% had elevated TG. Recipients with elevated TC had higher mean CsA concentrations at 1 year post Tx ( P=0.03). Recipients with elevated TG tended to receive more prednisone ( P=0.06). At 5 years post Tx, recipients had a high prevalence of hyperlipidemia. The identification and treatment of hyperlipidemia should be included in pediatric kidney Tx protocols.

Predicting kidney graft failure using time-dependent renal function covariates

Chronic rejection and recurrent disease are the major causes of late graft failure in renal transplantation. To assess outcome, most researchers use Cox proportional hazard analysis with time-fixed covariates. We developed a model adding time-dependent renal function covariates to improve the prediction of late graft failure. We studied 692 kidney transplants at the Leiden University Medical Center that had functioned for at least 6 months. Graft failure from chronic rejection or recurrent disease occurred in 106 patients. The reciprocal of last recorded serum creatinine (RC), the ratio of RC and RC at 6 months (RC6), and the time elapsed since last observation (TEL) were used as time-dependent covariates. Cadaveric donor transplantation, a lower RC, and a lower ratio of RC/RC6 were independently associated with graft failure. The impact of the last recorded RC was dependent on its value, TEL, and the time since transplantation. Validation of the model confirmed much higher failure predictions in those with subsequent graft failure compared with nonfailures. This study illustrates that the prediction of late graft failure could be improved significantly by using time-dependent renal function covariates.

Recipient hypertension potentiates chronic functional and structural injury of rat renal allografts

BACKGROUND

Systemic hypertension affects many allograft recipients, is an important risk factor for chronic graft dysfunction, and is linked to reduced graft survival. The condition may up-regulate the expression of inflammatory host cells and their products. These, in turn, may significantly injure vascular endothelium and other components of allografted kidneys.

METHODS

Lewis rats received orthotopic F344 renal allografts, a standard model of chronic rejection. Renovascular hypertension was produced by placing a silver clip (0.25 mm) on the renal artery of the retained contralateral native kidney 4 weeks after transplantation. Sham-clipped rats served as normotensive controls. Four recipient groups (Gp) were studied: Gp 1, rats with an allograft plus a clipped native kidney; Gp 2, those with an allograft and a sham-clipped native kidney; Gp 3, isografted animals with a clipped native kidney; and Gp 4, those bearing an isograft and a sham-clipped native kidney. Systolic blood pressure and proteinuria were measured every 2 weeks for 24 weeks. Grafts were assessed serially for morphologic and immunohistologic changes.

RESULTS

Systemic blood pressure rose to hypertensive levels in Gps 1 and 3 within a week of clipping but never increased in Gps 2 and 4. Proteinuria developed in hypertensive animals but remained at baseline in normotensive controls. Intimal thickening of allograft arteries progressed to luminal obliteration with extensive perivascular and interstitial fibrosis by 24 weeks. In contrast, vascular changes in isografts of hypertensive hosts were restricted to medial hypertrophy. Tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, platelet derived growth factor (PDGF), endothelin, Il-6, major histocompatibility complex (MHC) class II, and B7 were up-regulated in allografts in hypertensive hosts. Vascular deposition of immunoglobulin (IgG) was increased. These changes were markedly less pronounced in Gp 3 isografts and minimal in the kidneys of the normotensive animals of Gps 2 and 4.

CONCLUSIONS

An experimental model is presented that examines the influence of recipient hypertension in the pathogenesis of chronic dysfunction and injury developing in rat renal allografts over time.

Kidney transplantation in patients with type 1 diabetes mellitus: long-term prognosis for patients and grafts

Kidney transplantation is the best therapeutic choice to improve survival and quality of life in patients with end-stage diabetic nephropathy. Long-term prognosis in diabetic patients who received kidney transplants, however, has not been delineated. We, therefore, studied patient and graft survival, graft function and cause of graft failure in 78 Type I diabetic kidney transplant recipients in The Rogosin Institute/The Weill-Cornell Medical Center, New York who had functioning grafts for more than one year. The results were compared with 78 non-diabetic patients who had functioning grafts for more than one year and were matched for age, gender, donor source, time of transplantation and immunosuppressive therapy protocol. Cumulative patient survival rates for diabetic patients were significantly lower than those of non-diabetic patients (86% vs. 97% at 5 years and 74% vs. 95% at 10 years, respectively; p < 0.05). The most common cause of death was cardiovascular disease. Graft survival rates for diabetic patients were also lower than that of non-diabetic patients (71% vs. 80% at 5 years and 58% vs. 72% at 10 years, respectively), but the differences did not reach statistical significance. Among the 22 failed grafts in diabetic patients, 7 (32%) were due to patient death rather than primary graft failure. If the patients who died with a functioning graft were censored, graft survival rates of diabetic patients approached those of non-diabetic patients (80% vs. 81% at 5 years and 65% vs. 73% at 10 years, respectively). Creatinine clearances in diabetic patients were lower than that in non-diabetic patients through the follow-up period, but the differences were significant only for the first few years. At no time was there a higher creatinine clearance for diabetic patients. Among the 16 patients who had transplant kidney biopsies two to seven years post-transplant, 6 showed morphological changes consistent with diabetic nephropathy. One patient lost graft function solely by recurrent diabetic nephropathy. We conclude that long-term patient survival for diabetic patients is significantly lower than that of non-diabetic patients, due primarily to cardiovascular disease. Graft survival is comparable between the two groups. Creatinine clearances of diabetic patients are lower than those of non-diabetic patients. There is no apparent glomerular hyperfiltration at any time in diabetic patients. Recurrence of diabetic nephropathy is a rare cause of graft failure in the first 10 year post-transplant period. Aggressive intervention to modify cardiovascular risk factors should improve patient and graft survival in diabetic kidney transplant recipients.

The relationship between reduced functioning kidney mass and chronic rejection in rats

Interest has recently increased in the role of alloantigen-independent factors in chronic rejection. In this context, we examined the long-term effects of reduced functioning kidney mass in a F344-->LEW allograft (A) model. Animals were divided into three groups depending upon the amount of retained kidney. Renal arterial branches in the hilus were ligated so that one-third or two-thirds of the graft remained viable (1/3 and 2/3 groups, respectively); organs were left intact in the third (3/3) group. Urine protein concentrations were determined 4, 6, 8 and 10 weeks after engraftment and organs (five/group/time) were harvested and examined morphologically and immunohistologically. Proteinuria increased progressively in all 1/3, 2/3 and 3/3A animals, but faster in those with reduced kidney mass. This functional decline correlated well with increasing numbers of macrophages followed by interstitial fibrosis and glomerular sclerosis, which had become prominent by week 6 in group 1/3A and by 8 weeks in groups 2/3A and 1/3I (I, isografted), with animals beginning to die. IL-1, IL-6 and TNF production correlated well with the location and number of macrophages in all groups. These results suggest that kidney mass exerts a significant alloantigen-independent influence on chronic rejection. Allogenicity of the graft accelerates and amplifies the process.

Hypercholesterolemia is associated with increased kidney graft loss caused by chronic rejection in male patients with previous acute rejection

BACKGROUND

Whereas acute rejection is the main risk factor for the occurrence of chronic rejection, mechanisms in addition to the donor-specific immune response probably contribute to late allograft failure. In this study, we investigated the possible role of hypercholesterolemia in the incidence of chronic kidney graft loss.

METHODS

By using the actuarial method, we retrospectively analyzed the long-term loss of cadaveric kidney grafts in patients who had a functioning graft at 1 year and had received a transplant and undergone cyclosporin A therapy in our center between 1983 and 1997.

RESULTS

As observed previously, patients with acute rejection during the 1st posttransplant year (n=198) had significantly higher actuarial graft loss at 10 years compared with those free of acute rejection (n=244). In patients free of acute rejection at 1 year, hypercholesterolemia (> or =250 mg/dl) had no impact on graft loss at 10 years. On the contrary, in patients with previous acute rejection, those with hypercholesterolemia (n=59) had a higher immunological (36.0% vs. 19.2%; P<0.01) and overall (50.0% vs. 25.3%; P<0.01) graft loss at 10 years compared with patients with serum cholesterol <250 mg/dl (n=139). Among patients with 1st year acute rejection, hypercholesterolemia was associated with a significant increase in graft loss in male but not in female recipients. Multivariate analysis confirmed that hypercholesterolemia was an independent risk factor for chronic graft loss in male patients (P<0.05).

CONCLUSION

Hypercholesterolemia is an independent risk factor for kidney graft loss from chronic rejection in male patients with previous acute rejection. Correction of hypercholesterolemia could help to reduce kidney graft loss caused by chronic rejection in this category of patients.

Fibrous intimal thickening at implantation as a risk factor for the outcome of cadaveric renal allografts

BACKGROUND

During the past decade, the donor age of cadaveric renal allografts steadily increased. Because cerebrovascular injury is the main cause of death in this donor population, an increased prevalence of atherosclerotic lesions in the retrieved grafts could be anticipated. In a prospective study, we investigated the predictive value of morphologic lesions at implantation for the functional and morphologic outcome of cadaveric renal allografts at 1 1/2 years.

METHODS

In 50 consecutive adult recipients of a cadaveric renal allograft, under cyclosporine-based regimen, implantation biopsies and subsequent protocol biopsies at 18 months were performed, and morphometrically analyzed for the extent of glomerulosclerosis, interstitial fibrosis, and atherosclerosis. Risk factors were assessed at implantation and during the subsequent observation period of 18 months. Endpoints for this study were: the 24-hr creatinine clearance (normalized for body surface area) and the fractional interstitial volume at 1 1/2 years.

RESULTS

In multivariate analysis, fibrous intimal thickening at implantation (FIT) was the main determinant of the functional and morphologic outcome at 1 1/2 years. FIT represented a relative risk of 4.55 for interstitial fibrosis (95% CI=1.855-11.138), and 1.89 for impaired renal function (95% CI=1.185-3.007) at 1 1/2 years. FIT adversely affected fractional interstitial volume at 1 1/2 years (34.3 vs. 27.7%, P=0.004), as well as renal function (54 vs. 68 ml/min/1.73 m2, P=0.028).

CONCLUSIONS

Fibrous intimal thickening at implantation is a determinant risk factor for the functional and morphologic outcome of cadaveric renal allografts at 1 1/2 years.

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.

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.

Quantitation of allograft fibrosis and chronic allograft nephropathy

Despite improvements in the prevention and treatment of acute renal allograft rejection, the long-term survival of renal transplants has not increased. Immunologic and non-immunologic factors contribute to the gradual deterioration of graft function and to the histologic lesion characterized by vascular and interstitial fibrosis ('chronic rejection'). Quantitation of this process has been attempted using various invasive and non-invasive methods. These methods, performed at different times post-transplant, are reviewed in this article. In particular, pathology scoring systems and the potential of using computerized image analysis of biopsy material are discussed.

Chronic allograft nephropathy: An update

Chronic allograft nephropathy is the most prevalent cause of renal transplant failure in the first post-transplant decade, but its pathogenesis has remained elusive. Clinically, it is characterized by a slow but variable loss of function, often in combination with proteinuria and hypertension. The histopathology is also not specific, but transplant glomerulopathy and multilayering of the peritubular capillaries are highly characteristic. Several risk factors have been identified, such as advanced donor age, delayed graft function, repeated acute rejection episodes, vascular rejection episodes, and rejections that occur late after transplantation. A common feature of chronic allograft nephropathy is that it develops in grafts that have undergone previous damage, although the mechanism(s) responsible for the progressive fibrosis and tissue remodeling has not yet been defined. Hypotheses to explain chronic allograft nephropathy include the immunolymphatic theory, the cytokine excess theory, the loss of supporting architecture theory, and the premature senescence theory. The most effective option to prevent chronic allograft nephropathy is to avoid graft injury from both immune and nonimmune mechanisms.

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.

Report of the Radionuclides in Nephrourology Committee for evaluation of transplanted kidney (review of techniques)

Comprehensive evaluation of renal transplants has been important in differential diagnosis of medical and surgical complications in the early post-transplantation period and in the long-term follow-up. If performed well, it yields excellent functional and good anatomic information about the graft that can be effectively used in the patient. That includes selection of patients for biopsy and for various drug regimens. This is true especially in patients with anuric acute tubular necrosis (ATN) and in patients with developing chronic rejection. Improving indices of renal function (effective renal plasma flow, uptake of tubular tracers) can indicate resolution of tubular injury (ATN) while there is still no improvement in plasma creatinine. In patients with chronic rejection, plasma creatinine increases only after approximately 30% of renal function is lost due to graft fibrosis. Early recognition of this condition could permit treatment and delay of retransplantation. The protocol recommended at the Copenhagen meeting includes a flow study, scintigram of the kidneys, prevoid and postvoid bladder image, injection site image (quality control), time/activity curves of the graft and bladder, and quantitative data of perfusion, function, and tracer transit. The flow study obtained during the initial transit of the bolus through the graft could be performed either with 99mTc mercaptoacetyltriglycine, or 99mTc diethylenetriaminepentaacetate (DTPA). Quantitative analysis of perfusion facilitates interpretation of the study during the early post-transplantation period. ATN, common in cadaver transplants, typically shows adequate perfusion. The function phase should include images and time/activity curves. Images alone are insufficient. Quantitative data such as clearance or other indices of function and indices of tracer transit are essential for correct interpretation of the results. Normal images and normal graft function reliably exclude clinically important complications. A single scintigram demonstrating prolonged tracer transit with decreased function cannot separate acute rejection and ATN. On serial studies, decline in function and poor perfusion are indicative of acute rejection. A normally appearing scintigram without cortical retention, but with low function, is consistent with chronic rejection. Pharmacological intervention to exclude obstruction (diuretic renogram) or hemodynamically significant renal artery stenosis (angiotensin converting enzyme challenge) should be used whenever indicated.

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.

Chronic allograft failure: the clinical problem

Long-term survival statistics for organ allografts have not improved substantially over time, despite improved immunosuppression and organ preservation and better surgical and perioperative management. Chronic rejection is the most important long-term limitation in allografts and increasingly seems to be caused by a multifactorial series of antigen-dependent and antigen-independent factors. Early injury is critical to late events, whether antigen driven (early acute rejection episodes and human leukocyte antigen mismatching) or antigen independent (ischemia/reperfusion injury and brain death). Ongoing alloimmunologic injury to the host and inadequate organ mass functioning (donor age, gender, race, and organ size) also seem to be important to this persisting process. Associated recipient conditions, which includes hypertension and hyperlipidemia, and postoperative complications, which include drug nephrotoxicity and infections, may affect this late-phase graft loss. These deleterious risk factors for chronic rejection of long-functioning allografts are an important subject for future investigation.

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.

Infection-associated cellular activation accelerates chronic renal allograft rejection in rats

The etiology of chronic rejection is unknown, although acute rejection, viral infection, and initial graft ischemia have been implicated. To test the effects of infections on the process of chronic rejection, we simulated bacterial infection by the administration of the endotoxin lipopolysaccharide (LPS), a potent activator of various cell types in an established rat model of chronic rejection. Lewis recipients of Fisher 344 kidneys were treated with a single dose of LPS or vehicle 8 weeks following transplantation and grafts were examined at various time points. In the chronically rejecting controls, leukocytic infiltration and the expression of cytokines peaked at 16 weeks. In LPS-treated hosts, leukocyte infiltration and cytokine expression peaked at 12 weeks. By 16 weeks, glomeruli in LPS-treated recipients had become far more sclerotic than those in controls, mimicking the changes observed in controls at 24 weeks. We conclude that infections may play an important role in the development of chronic rejection.

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.

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.