Nonimmunologic causes of late renal graft loss

Circulating CTRP9 correlates with the prevention of aortic calcification in renal allograft recipients

Background

Cardiovascular disease (CVD) due to atherosclerosis is a major cause of death in renal allograft recipients. Recently, C1q/TNF-α related protein-9 (CTRP9), which is a paralog of adiponectin (ADPN), has been suggested to be related to the prevention of atherosclerosis and the occurrence of CVD, but this relationship has not been confirmed in renal allograft recipients.

Subjects and methods

The relationships among the serum CTRP9 concentration, serum ADPN concentration, and vascular calcification were investigated in 50 kidney transplantation recipients at our hospital. Calcification of the abdominal aorta was evaluated according to the aortic calcification area index (ACAI) calculated from CT images. Changes in the serum CTRP9 and ADPN fractions and ACAI were examined for 8 years. In addition, the expression of CTRP9 and ADPN and their respective receptors AdipoR1 and R2 in muscular arteries of the kidney was examined by immunofluorescence.

Results

In renal allograft recipients, the serum CTRP9 concentration at the start of the observation was not significant correlated with eGFR or serum high-molecular-weight (HMW)-ADPN concentration (rS = -0.009, p = 0.950; rS = -0.226, p = 0.114, respectively). However, the change in the serum CTRP9 concentration was positively correlated with the change in the serum HMW-ADPN concentration (rS = 0.315, p = 0.026) and negatively correlated with the change in ACAI (rS = -0.367, p = 0.009). Multiple regression analysis revealed that the serum HMW-ADPN concentration was a significant positive factor for the change in the serum CTRP9 concentration. Moreover, for ACAI, an increase in the serum CTRP9 concentration was an improving factor, but aging was an exacerbating factor. Furthermore, colocalization of CTRP9 and AdipoR1 was noted in the luminal side of intra-renal arterial intima.

Conclusion

In renal allograft recipients, both CTRP9 and HMW-ADPN were suggested to prevent the progression of aortic calcification through AdipoR1.

The impact of donor and recipient weight incompatibility on renal transplant outcomes

BACKGROUND

Donor/recipient size mismatching and correlation to allograft outcome remains poorly defined. This study assessed the impact of donor body weight (DBW) to recipient body weight (RBW) ratio on allograft function and survival.

METHODS

A total of 898 deceased donor renal transplant recipients were included in the study. Patients were divided into quartiles depending on the ratio of DBW/RBW: Q1 (≤ 0.88), Q2 (0.89-1.00), Q3 (1.01-1.22) and Q4 (> 1.22). Donor and recipient characteristics were obtained from the national kidney transplant service database. Serum creatinine and estimated glomerular filtration rate (eGFR) at 1 and 5 years after transplant were compared.

RESULTS

Q4 patients had a higher eGFR 1 year post-transplant (median 59.5 ml/min, IQR 46.8-76.2) compared to Q1-Q3 which had median eGFRs of 54.3, 54.8 and 55.3 ml/min, respectively (p < 0.001). At 5 years post-transplant, there were modest differences in the eGFR across the four quartiles, Q1-4 with median eGFRs of 56.9, 61.1, 61.2 and 58.6 ml/min, respectively (p = 0.02). However, there were no significant differences in 1- and 5-year allograft survival between groups.

CONCLUSIONS

In the setting of deceased donor renal transplantation, mismatching of donor to recipient weight had no impact on 5-year allograft survival, but a low DBW/RBW ratio is modestly associated with lower eGFR.

Hepatitis C and kidney transplantation

Hepatitis C virus (HCV) infection is relatively common among patients with end-stage kidney disease (ESKD) on dialysis and kidney transplant recipients. HCV infection in hemodialysis patients is associated with an increased mortality due to liver cirrhosis and hepatocellular carcinoma. The severity of hepatitis C-related liver disease in kidney transplant candidates may predict patient and graft survival after transplant. Liver biopsy remains the gold standard in the assessment of liver fibrosis in this setting. Kidney transplantation, not haemodialysis, seems to be the best treatment for HCV+ve patients with ESKD. Transplantation of kidneys from HCV+ve donors restricted to HCV+ve recipients is safe and associated with a reduction in the waiting time. Simultaneous kidney/liver transplantation (SKL) should be considered for kidney transplant candidates with HCV-related decompensated cirrhosis. Treatment of HCV is more complex in hemodialysis patients, whereas treatment of HCV recurrence in SLK recipients appears effective and safe.

Estimation of renal allograft half-life: fact or fiction?

INTRODUCTION

Renal allograft half-life time (t½) is the most straightforward representation of long-term graft survival. Since some statistical models overestimate this parameter, we compare different approaches to evaluate t½.

PATIENTS AND METHODS

Patients with a 1-year functioning graft transplanted in Spain during 1990, 1994, 1998 and 2002 were included. Exponential, Weibull, gamma, lognormal and log-logistic models censoring the last year of follow-up were evaluated. The goodness of fit of these models was evaluated according to the Cox-Snell residuals and the Akaike's information criterion (AIC) was employed to compare these models.

RESULTS

We included 4842 patients. Real t½ in 1990 was 14.2 years. Median t½ (95% confidence interval) in 1990 and 2002 was 15.8 (14.2-17.5) versus 52.6 (35.6-69.5) according to the exponential model (P < 0.001). No differences between 1990 and 2002 were observed when t½ was estimated with the other models. In 1990 and 2002, t½ was 14.0 (13.1-15.0) versus 18.0 (13.7-22.4) according to Weibull, 15.5 (13.9-17.1) versus 19.1 (15.6-22.6) according to gamma, 14.4 (13.3-15.6) versus 18.3 (14.2-22.3) according to the log-logistic and 15.2 (13.8-16.6) versus 18.8 (15.3-22.3) according to the lognormal models. The AIC confirmed that the exponential model had the lowest goodness of fit, while the other models yielded a similar result.

CONCLUSIONS

The exponential model overestimates t½, especially in cohorts of patients with a short follow-up, while any of the other studied models allow a better estimation even in cohorts with short follow-up.

Outcome of Pregnancy in Renal Allograft Recipients: SIUT Experience

The course of pregnancy and its outcome was studied in renal allograft recipients. Between November 1985 and November 2005, a total of 1481 renal transplants were carried out at the Sindh Institute of Urology and Transplantation (SIUT); among them were 348 females, with 73 potential females for pregnancy. All patients received cyclosporine and prednisolone, with 82% also receiving azathioprine and 4 patients mycophenolate mofetil as a third immunosuppressant drug. We evaluated incidence of hypertension, diabetes, pre-eclampsia, urinary tract infection (UTI), rejection during pregnancy and during 3 months' postdelivery as well as outcomes of pregnancy. Among 73 potential candidates, 31 had 47 pregnancies, after an average of 31 months (8-86 months). Of 31 subjects, 21 subjects were hypertensive on one or two drugs prior to conception. A rise in blood pressure during pregnancy was noticed in 7 patients. Albuminuria from trace to 3+ appeared in 13 patients and glycosuria in one other. Blood sugar levels remained within normal range in all subjects. UTIs occurred during pregnancy in 7 patients. Among 47 pregnancies, 9 had abortions (7 spontaneous, 2 therapeutic) and 6 had preterm deliveries. The others were full-term deliveries: 12 via a lower segment caesarean section and 20 were normal vaginal deliveries. Average birth weight was 4.8 lbs. At an average follow-up of 38 months the serum creatinine values ranged from 0.94 to 2.3 mg %. One patient developed acute irreversible graft dysfunction soon after delivery. Our study demonstrated that pregnancy did not reduce renal graft survival, but newborns are at greater risk of premature birth and low birth weight.

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.

Mast cell numbers and protease expression patterns in biopsy specimens following renal transplantation from living-related donors predict long-term graft function

In human kidney transplantation the main cause of declining long-term graft function is chronic allograft nephropathy (CAN). Recent studies have implicated human mast cells (MC) in chronic inflammation and fibrosis, MC can be subtyped according to protease content: MC(T) containing tryptase only and MC(TC) containing both tryptase and chymase. We investigated immunohistochemically whether numbers and subtypes of MC in biopsy specimens 100 d after transplantation could predict subsequent fibrosis and graft dysfunction. The total number of MC/high-power field at 100 d after transplantation correlated significantly with change in creatinine clearance (DeltaCcr), defined as (Ccr at 100 d) - (Ccr at 3 yr) (R = 0.597, p = 0.0021); fibrosis index (FI) at 100 d (R = 0.583, p = 0.0066); and DeltaFI, defined as (FI at 3 yr) - (FI at 100 d) (R = 0.406, p < 0.05). The ratio of MC(TC) to total MC at 100 d also correlated with DeltaCcr (R = 0.491, p = 0.0148), FI at 100 d (R = 0.527, p = 0.0081), and DeltaFI (R = 0.417, p < 0.05). Thus, increases in number of total MC and the ratio of MC(TC) to total MC in early biopsy specimens were related to decline of long-term graft function and fibrosis.

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.

Calcineurin Inhibitor–Free Immunosuppression in Renal Transplantation

PURPOSE

To describe our initial results using a calcineurin inhibitor-free immunosuppression protocol in renal transplants.

PATIENTS AND METHODS

Between October 2001 and June 2003, 56 recipients of a renal allografts were started on an immunosuppression protocol without calcineurin inhibitors, consisting of basiliximab, sirolimus, mycophenolate mofetil, and steroids. We analyzed patient and graft survival, acute rejection episodes, and renal function.

RESULTS

The mean follow-up was 19.6 months. Actuarial patient survival at 1 and 2 years was 98.1% and 95.3%, respectively. Actuarial graft survival at 1 and 2 years was 92.9% and 87.6%, respectively. Acute rejection occurred in 27.8% of the patients, usually Banff 1 (73.3%). There was stable renal function with mean serum creatinine of 1.3, 1.4, 1.3, and 1.3 mg/dL at 1, 6, 12, and 24 months after transplant.

CONCLUSIONS

The use of immunosuppression free of calcineurin inhibitors is effective and safe. Further follow-up is needed to evaluate the impact on long-term results.

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.

Interferon therapy in hemodialysis patients with chronic hepatitis C: study of tolerance, efficacy and post-transplantation course

BACKGROUND

The potential benefit of pre-transplant treatment of chronic hepatitis C on long-term evolution after renal transplantation is not clear.

METHODS

Fifty successive renal transplant candidates had their sera positive for HCV RNA and a biopsy-proven chronic hepatitis. Out of these, 18 patients received a standard course of interferon-alpha2b (IFN; 3 MU three times weekly after hemodialysis sessions for 6 months).

RESULTS

IFN was discontinued in 2 patients (11%) due to persistent leukopenia. HCV RNA turned negative in 10 patients of the treatment group and in none of the control group. Two patients of the IFN group had a virological relapse post-transplantation. Post-transplant follow-up periods were 41.5 +/- 15 and 50 +/- 16 months for the treated and control groups respectively. Transaminases remained normal in all patients of the IFN group after transplantation. In contrast, biochemical evidence of acute and chronic hepatitis was observed in 5 (p = 0.03) and 13 (p = 0.002) patients, respectively, of the control group. Logistic regression analysis identified non-receiving IFN before transplantation as a risk factor for post-transplant hepatic dysfunction (odds ratio = 11.7, p = 0.003) and for chronic allograft nephropathy (odds ratio = 11.6, p = 0.02).

CONCLUSIONS

IFN-treated patients had a significantly better post-transplant hepatic function and significantly lower rates of chronic allograft nephropathy.

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.

Different effects of tacrolimus and cyclosporine on renal hemodynamics and blood pressure in healthy subjects

BACKGROUND

The side effects of cyclosporine, nephrotoxicity and hypertension, contribute to long-term renal graft failure and cardiovascular morbidity in graft recipients. It is not clear whether tacrolimus is as nephrotoxic and hypertensive as cyclosporine. Data on this subject are not consistent because of differences in dosage and duration of treatment and the presence of comorbidity in the studied patients. A comparison of both drugs with respect to renal hemodynamics and blood pressure has not been performed yet in healthy subjects.

METHODS

We studied blood pressure, glomerular filtration rate, and effective renal plasma flow in eight healthy subjects at baseline and after 2 weeks administration of cyclosporine and tacrolimus, in randomized order. Trough levels of either drug were within the currently recommended therapeutical range of 100-200 ng/ml for cyclosporine and 5-15 ng/ml for tacrolimus.

RESULTS

Tacrolimus did not influence renal hemodynamic parameters, in contrast to cyclosporine. During cyclosporine, glomerular filtration rate decreased from 98+/-9 ml/min/1.732 to 85+/-10 ml/min/1.732 (P<0.05), and ERPF decreased from 597+/-108 ml/min/1.732 to 438+/-84 ml/min/1.732 (P<0.01). Mean arterial blood pressure increased from 93+/-8 mmHg to 108+/-10 mmHg (P<0.05) during cyclosporine and remained unchanged during tacrolimus.

CONCLUSIONS

We conclude that tacrolimus given during 2 weeks in the currently advised dosage has no unfavorable effects on renal hemodynamics and blood pressure in healthy individuals. The use of tacrolimus in organ transplant recipients may in the long-term lead to better renal function and less cardiovascular morbidity than the use of cyclosporine.

Transforming growth factor-beta1 expression in early biopsy specimen predicts long-term graft function following pediatric renal transplantation

The main cause of late graft loss or declining long-term graft function is chronic allograft nephropathy (CAN), characterized by progressive interstitial fibrosis. Transforming growth factor (TGF)-beta1 plays a key role in fibrogenesis. We immunohistochemically investigated whether the degree of TGF-beta1 expression in early biopsy specimens routinely obtained from stable allografts at 100 d could predict fibrosis and graft dysfunction in the late phase. Patients were children with grafts from related donors. We immunohistochemically determined intracellular and extracellular expression of TGF-beta1 in the graft using LC antibody (LC) for intracellular TGF-beta1 and CC antibody (CC) for extracellular TGF-beta1. The change in creatinine clearance between 100 d and 3 yr after transplantation (DeltaCcr) was used as an index of long-term graft function. We also used image analysis to calculate the relative area involved by interstitial fibrosis in the trichrome-stained section of graft biopsy specimens at 100 d and 3 yr, designating the change as DeltaFI. DeltaCcr was -4.2+/-9.4 mL/min in subjects with minimal early immunoreactivity for CC and -20.5+/-15.9 mL/min in subjects with strong reactivity (p<0.05). DeltaCcr was -14.5+/-18.6 mL/min in subjects with minimal early immunoreactivity for LC and -11.7+/-12.8 mL/min in those with strong reactivity. DeltaFI in subjects with minimal CC reactivity (1.28+/-4.11%) tended to be lower than that in subjects with strong reactivity (8.45+/-15.47%). Neither fibrosis at 100 d nor DeltaFI differed between subjects with minimal and strong LC reactivity. Thus, strong extracellular TGF-beta1 expression in grafts at 100 d after transplantation is associated with a long-term decline in graft function and tends to be associated with increased graft fibrosis at 3 yr.

Cardiovascular risk factors in renal transplant patients: cyclosporin A versus tacrolimus

The hypertensive and hyperlipidemic effects of cyclosporin A (CsA) may contribute to the high cardiovascular morbidity in renal transplant patients and to the development of chronic transplant nephropathy. Tacrolimus is reported to have less effect on BP and lipids, but steroids, other drugs, and renal function may confound this. This study assessed 24-h BP and lipid profile in stable renal transplant recipients (n = 17) while they were receiving CsA, after 4 wk of receiving tacrolimus, and again after 4 wk of receiving CsA. Antihypertensives were stopped at least 3 wk before. A few patients used low-dose steroids and lipid-lowering drugs, which were not changed during the study. Mean daytime BP decreased from 149 +/- 12 and 95 +/- 8 mmHg to 138 +/- 13 and 87 +/- 9 mmHg (P: < 0.001) after patients were switched to tacrolimus. Mean nighttime BP also decreased, from 140 +/- 12/86 +/- 7 mmHg to 132 +/- 17/79 +/- 10 mmHg (P: < 0.05). Total and low-density lipoprotein cholesterol decreased from 6.1 +/- 0.7 and 3.84 +/- 0.79 mmol/L to 5.1 +/- 0.8 and 2.98 +/- 0.75 mmol/L (P: < 0.001). Return to CsA caused an increase in BP and cholesterol to values similar as during the first CsA period. The conclusion is that tacrolimus has fewer unfavorable effects on BP and lipids than does CsA. Elective conversion from CsA to tacrolimus in stable renal transplant recipients may lead to attenuation of cardiovascular morbidity and chronic transplant nephropathy in the long term.

Hyperlipidemia as a risk factor of renal allograft function impairment

In this study, the graft outcome in renal allograft recipients with [high cholesterol group (HCG), n = 30] or without [normal cholesterol group (NCG), n = 42] hypercholesterolemia and with [high triglyceride group (HTG), n = 33] or without [normal triglyceride group (NTG), n = 36] hypertriglyceridemia were prospectively compared. At 6 months post-transplantation, no significant difference was observed between the groups (NTG compared with HTG, and NCG compared with HCG) regarding age, presence of arterial hypertension, kind of donor (living related or cadaveric), immunosuppressive therapy, number of rejection episodes per patient, frequency of patients with acute cellular rejection, prevalence of patients with diabetes mellitus or proteinuria > 3 g/24 h, and mean serum creatinine. The probability of doubling serum creatinine during follow-up was statistically different between NTG and HTG (12 months: NTG = 0.03, HTG = 0.15; 36 months: NTG = 0.08, HTG = 0.33: 60 months: NTG = 0.08, HTG = 0.48; and 120 months: NTG = 0.18, HTG = 0.48), but not between NCG and HCG (12 months: NCG = 0.05, HCG = 0.13; 36 months: NCG = 0.13, HCG = 0.24; 60 months: NCG = 0.19, HCG = 0.31; 84 months: NCG = 0.27, HCG = 0.31). There was no significant difference in actuarial graft survival between HCG and NCG or between NTG and HTG. Hypertriglyceridemia, but not hypercholesterolemia, was associated with loss of graft function.

Acute rejection-associated tubular basement membrane defects and chronic allograft nephropathy

BACKGROUND

Acute rejection is a major risk factor for chronic allograft nephropathy, although the link(s) between these events is not understood. The hypothesis of this study is that alterations in tubular basement membranes (TBMs) that occur during acute rejection may be irreversible and thereby play a role in the development of chronic allograft nephropathy.

METHODS

Fourteen renal transplant patients were selected, each having had two or more biopsies performed (42 total). All biopsies were scored for acute and chronic rejection using Banff 1997 criteria. The initial biopsy showed only acute interstitial rejection (type I rejection). No biopsies contained significant chronic arterial lesions of chronic vascular rejection. The entire cortex was examined on Jones methenamine silver-stained sections at x400 for interruption in TBM staining. The number of tubules with TBM abnormalities was counted, and the renal cortical area was measured by image analysis. Periodic acid-Schiff/immunoperoxidase stain was performed on 12 acute rejection biopsies stained for laminin, cytokeratin 7, CD3, CD20, and CD68. Controls consisted of 11 biopsies (8 negative for rejection and 3 acute tubular necrosis).

RESULTS

Numerous TBM alterations in silver staining were identified as being associated with acute rejection and tubulitis, consisting of abrupt TBM discontinuities and/or extreme attenuation with segmental or complete absence of TBM. A loss of TBM matrix proteins was confirmed by absent laminin staining in areas of acute rejection and tubulitis. There was herniation of tubular cells into the interstitium through TBM defects confirmed by cytokeratin staining. The TBM defects were spatially associated with inflammatory cells, particularly macrophages. When the biopsies were divided into two groups, <10 and> 10 TBM breaks/mm2, there were statistically significant morphologic and clinical correlations. The number of TBM disruptions correlated with the serum creatinine at the time of biopsy, a combined Banff t + i score, the difference in tubular atrophy between the initial and most recent biopsy and the difference between the nadir creatinine and most recent creatinine.

CONCLUSION

Damage to TBM develops in acute rejection as a consequence of interstitial inflammation and tubulitis. These lytic events correlate with the later development of clinical and morphologic evidence of chronic injury in the absence of arterial injury of chronic rejection. We suggest that chronic allograft nephropathy may have an inflammatory interstitial origin.

Hyperhomocyst(e)inemia in chronic stable renal transplant patients

PURPOSE

Hyperhomocyst(e)inaemia is an important risk factor for atherosclerosis, which is currently a major cause of death in renal transplant patients. The aim of this study was to assess the influence of immunosuppressive therapy on homocyst(e)inemia in renal transplant recipients.

METHODS

Total serum homocysteine (by high performance liquid chromatography), creatinine, lipid profile, folic acid (by radioimmunoassay-RIA) and vitamin B12 (by RIA) concentrations were measured in 3 groups. Group I patients (n=20) were under treatment with cyclosporine, azathioprine, and prednisone; group II (n=9) were under treatment with azathioprine and prednisone; and group III (n=7) were composed of renal graft donors for groups I and II. Creatinine, estimated creatinine clearance, cyclosporine trough level, lipid profile, folic acid, and vitamin B12 concentrations and clinical characteristics of patients were assessed with the aim of ascertaining determinants of hyperhomocyst(e)inemia.

RESULTS

Patient ages were 48.8 +/- 15.1 yr (group I), 43.3 +/- 11.3 yr (group II); and 46.5 +/- 14.8 yr (group III). Mean serum homocyst(e)ine (tHcy) concentrations were 18.07 +/- 8.29 mmol/l in renal transplant recipients; 16.55 +/- 5.6 mmol/l and 21.44 +/- 12.1 mmol/l respectively for group I (with cyclosporine) and group II (without cyclosporine) (NS). In renal donors, tHcy was significantly lower (9.07 +/- 3.06 mmol/l; group I + group II vs. group III, p<0.008). There was an unadjusted correlation (p<0.10) between age (r=0.427; p<0.005) body weight (r=0.412; p<0.05), serum creatinine (r=0.427; p<0.05), estimated creatinine clearance (r=0.316; p<0.10), and tHcy in renal recipients (group I +II). Independent regressors (r2=0.46) identified in the multiple regression model were age (coefficient= 0.253; p=0.009) and serum creatinine (coefficient=8.07; p=0.045). We found no cases of hyperhomocyst(e)inemia in the control group. In contrast, 38% of renal recipients had hyperhomocyst(e)inemia: 7 cases (35%) on cyclosporine and 4 (45%) without cyclosporine, based on serum normal levels.

CONCLUSIONS

Renal transplant recipients frequently have hyperhomocyst(e)inemia. Hyperhomocyst(e)inemia in renal transplant patients is independent of the scheme of immunosuppression they are taking. The older the patients are and the higher are their serum creatinine levels, the more susceptible they are to hyperhomocyst(e)inemia following renal transplantation.

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.

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.

Transforming growth factor-beta levels in human allograft chronic fibrosis correlate with rate of decline in renal function

BACKGROUND

Long-term renal transplant function is limited primarily by a progressive scarring process loosely termed "chronic rejection, chronic allograft nephropathy, or allograft fibrosis." Although the etiology of transplant fibrosis is uncertain, several possible factors including chronic cyclosporin A (CsA) exposure may contribute to its pathogenesis. CsA stimulates renal fibrosis perhaps through the induction of the potent pro-sclerotic growth factor, transforming growth factor beta (TGFbeta). Previously, we demonstrated that, in human transplant biopsies, acute CsA toxicity but not acute tubular necrosis is associated with elevated levels of renal TGFbeta protein. We now examine whether long-term CsA treatment (>1 year) is associated with elevated levels of intra-allograft TGFbeta and whether heightened expression of TGFbeta is clinically significant.

METHODS

Using immunohistochemical techniques, we determined the relative level of expression of intrarenal TGFbeta protein in transplant biopsies. We studied biopsies obtained from 40 CsA-treated patients that were diagnosed as having chronic allograft fibrosis. Biopsies were scored as having minimal or high levels of TGFbeta.

RESULTS

Seventy-two percent of patients expressed high levels of intra-allograft TGFbeta. This group of patients lost renal function at an average rate of -19.5+/-17.3 ml/min/year. In contrast, patients with minimal or no TGFbeta expression experienced a decline of only -6.2+/-4.1 ml/min/year (P=0.01).

CONCLUSIONS

These results suggest that the majority of CsA-treated patients with biopsy proven chronic fibrosis have elevated levels of intra-graft TGFbeta that correlates with an increased rate of decline in renal function.

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.

The poor accuracy of indirect measurements of cadaveric donor kidney weights

Reports that examined the issue of whether transplantation of inadequate nephron mass may be a risk factor for long-term allograft failure yielded conflicting results. One of the more accurate methods of estimating glomerular mass is kidney weight. Most of the clinical studies used body surface area (BSA) or kidney length as estimates of kidney weight. To test the hypothesis that indirect measures of kidney weight are accurate estimates of kidney weight, we compared the kidney weight of 41 consecutive cadaveric kidneys to donor BSA, dimensions measured with calipers at the time of transplantation, and dimensions supplied by the Organ Procurement Agency (OPA). Linear regression analysis was used with kidney weight as the dependent variable and BSA, kidney length, or kidney volume as the independent variable. Kidney length measured with calipers was also compared to kidney length supplied by the OPA. Kidney weight had the best correlation with kidney volume and kidney length determined by caliper measurements (r = 0.640 and 0.646, respectively). The regression analysis showed that the correlation of kidney weight with BSA was 0.487. The correlation of OPA-provided kidney length with kidney weights was poor (r = 0.410). The linear regression of caliper-measured kidney length versus OPA length yielded a slope of 0.360, instead of an ideal slope of 1. The assumption has been made that kidney weight or a surrogate of kidney weight has an excellent correlation with nephron mass. Some of the variability in studies that attempted to examine the effect of transplanted nephron mass on allograft outcome may be due to inaccurate estimates used for kidney weight. Our data suggest that surrogate measurements of kidney weight may not be accurate. We recommend that measured kidney weight should be used in studies examining the effect of donor renal mass on allograft outcomes.

Apoptosis and expression of cytotoxic T lymphocyte effector molecules in renal allografts

Cytotoxic T lymphocyte (CTL) mediated apoptosis is thought to play a major role in the rejection of renal allografts following transplantation, however, the CTL effector mechanism that is primarily responsible for immunological rejection is unknown. The two major effector pathways of CTL killing which lead to apoptosis involve the Fas/Fas ligand (Fas L) lytic pathway, and the perforin/granzyme degranulation pathway. The expression of CTL effector molecules which influence these pathways include Fas, Fas L and TiA-1 (cytotoxic granule protein). This study has investigated apoptosis by in situ terminal deoxytransferase-catalysed DNA nick end labelling (TUNEL), and the expression of CTL effector molecules by immunohistochemistry, in renal allograft biopsies obtained from patients following kidney transplantation. Renal biopsies were classified into three histological groups; acute cellular rejection, chronic rejection, or no rejection. The extent of T-cell infiltration of renal tissues was assessed by immunohistochemical staining with an anti-CD3 monoclonal antibody. Numerous TUNEL positive cells were detected in all transplant biopsies examined; these consisted mainly of renal tubular cells and infiltrating cells, with some TUNEL positive cells also detected in the glomeruli. In the case of normal kidney tissue, renal cells also stained positive for TUNEL but there was no lymphocytic infiltration. There was significantly more T-cell infiltration observed in acute rejection biopsies compared to the no rejection biopsies. In the case of Fas L expression, there was little expression in all three biopsy groups, apart from one case of chronic rejection. Conversely, although there were no significant differences in TiA-1 expression between the three biopsy groups, TiA-1 expression was more prominent in acute rejection biopsies. Furthermore, Fas expression was significantly decreased in acute rejection biopsies when compared to those of chronic and no rejection in which Fas was predominantly localized in the renal tubular cells. These results indicate that the mechanism of CTL killing leading to the rejection of renal allografts may be different in acute and chronic rejection. Moreover, our data indicate the potential for cytotoxic granule-based CTL killing in acute renal allograft rejection but not in chronic rejection.

Early proteinuria in renal transplant recipients treated with cyclosporin

PURPOSE

To establish the risk profile for the development of proteinuria in the first months after renal transplantation and to disclose the prognostic significance of this finding.

DESIGN

We conducted an observational historic cohort study.

SETTING

We conducted the study in a tertiary care hospital renal transplantation unit covering a potential population of approximately 2 million. We made extensive use of suboptimal donors.

POPULATION

In our unit, 560 cadaveric renal transplants were performed between January 1988 and June 1997, under Cyclosporine immunosuppression, with a minimum follow up of 1 year.

METHOD

The risk profile analysis explored early clinical factors reported to be related to the late course of renal transplantation. The study of the prognostic significance of proteinuria included survival analysis and correlation with late markers of graft dysfunction, taking into consideration the intensity and persistence of early proteinuria. A multivariate approach was used in all cases.

RESULTS

Early proteinuria was strongly associated with delayed graft function (odds ratio [OR] 1.03/day of dialysis), acute rejection (OR 1.7 for steroid-sensitive and 6.2 for steroid-resistant rejection), renal transplant to a hypersensitized recipient (OR 2.5), and pediatric (<5 years)(OR 4.1) or older (>60 years)(OR 3.0) donors. The predictive model for persistency of proteinuria was very similar, whereas transient proteinuria could not be adequately modeled. Increasing intensity of proteinuria was strongly associated with poor patient and graft survival. Persistent, but not transient, proteinuria supported this relationship.

CONCLUSIONS

Proteinuria appearing early after renal transplantation is strongly associated with delayed graft function, acute rejection, and the use of pediatric or older donors. Whatever its background, proteinuria is a strong predictor of poor patient and graft survival. This effect is directly related to the intensity and persistence of the disorder.

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.

Low-dose cyclosporine and mycophenolate mofetil in renal allograft recipients with suboptimal renal function

BACKGROUND

Cyclosporine (CsA) nephrotoxicity can be identified by functional changes and chronic renal damage. CsA-associated renal fibrosis has been related to the overproduction of transforming growth factor (TGF)-beta1, a fibrogenic cytokine. Mycophenolate mofetil (MMF) may allow CsA dose reduction without increasing the risk of rejection.

METHODS

We studied the impact of CsA dose reduction in association with MMF on renal function and TGF-beta1, production in 16 long-term renal allograft recipients with suspected CsA nephrotoxicity. Two grams/day of MMF were introduced, and CsA dose was reduced to reach whole-blood levels between 40 and 60 ng/ml within 1 month. CsA dose and levels, renal function parameters, and platelet-poor plasma TGF-beta1 levels were evaluated before and 6 months thereafter.

RESULTS

MMF allowed a decrease in both the mean dose of CsA (3.8+/-1.35 vs. 2.2+/-0.73 mg/kg/day; P<0.01) and CsA levels (148+/-36 vs. 53+/-19 ng/ml; P<0.001). The reduction of CsA was associated with a decrement of serum creatinine levels (210+/-46 vs. 172+/-41 micromol/L; P<0.001) and an increase in both the glomerular filtration rate (32.9+/-12 vs. 39.1+/-14 ml/min/1.73 m2; P<0.02) and renal plasma flow (195+/-79 to 218.6+/-74.02 ml/min/1.73 m2; P<0.02). There was a reduction in plasma TGF-beta1 levels (4.6+/-4.2 vs. 2.0+/-1.4 ng/ml; P=0.003) and CsA levels correlated with TGF-beta1 (r=0.536, P=0.002). No rejection episodes occurred, and an improvement in both systolic (149+/-13 vs. 137+/-12 mmHg; P<0.01) and diastolic blood pressure (89+/-14 vs. 83+/-10 mmHg; P<0.04) were observed.

CONCLUSIONS

These short-term results show that MMF introduction allows a CsA dose reduction, which improves renal function, reduces TGF-beta1 production, and improves the control of hypertension, without increasing the incidence of acute rejection.

Elevated neointimal endothelin-1 in transplantation-associated arteriosclerosis of renal allograft recipients

BACKGROUND

Chronic renal allograft rejection is characterized histologically by transplantation-associated arteriosclerosis and glomerulosclerosis (Tx-AA and Tx-AGS). Recent studies in animal models implicate the mitogenic and pressor actions of endothelin-1 (ET-1) in Tx-AA. In humans, however, a link between elevated ET-1 secretion and Tx-AA or Tx-AGS remains unclear. In this study we analyzed expression of ET-1 in the vasculature of renal transplant patients with chronic or acute rejection and in normal controls.

METHODS

Renal vascular and glomerular ET-1 was assessed by immunohistochemistry in 12 patients with clinically and histologically defined chronic rejection, in 11 patients with acute rejection, and in 5 normal kidneys. ET-1 staining was also correlated with various clinical parameters and with a morphometric index of neointima formation. ET-1 secretion was measured by ELISA in cultured human vascular cell types treated with T cell- and macrophage-associated cytokines.

RESULTS

We found that renal allografts with chronic rejection and Tx-AA expressed 6.1-fold more ET-1 in the vasculature relative to allografts with acute rejection or to normal kidneys (P < 0.01). In Tx-AA, ET-1 was detected predominantly in the neointima, which contained mostly endothelial cells and smooth muscle cells. A strong positive correlation (r = 0.82, P < 0.01) was observed between vascular ET-1 peptide expression and hypertension in patients with chronic rejection. We also showed that macrophage-associated cytokines, but not T cell-associated cytokines, stimulated ET-1 secretion in human endothelial cells, vascular smooth muscle and mesangial cells.

CONCLUSIONS

These results demonstrate that elevated ET-1 in the neointima is associated with Tx-AA and chronic rejection. In addition, these results point to an important role for endothelial dysfunction in chronic renal allograft rejection.

Mechanisms and management of acute renal allograft rejection

We used RT-PCR for the molecular characterization of human renal graft rejection. The studies showed that intragraft display of mRNA encoding cytotoxic attack molecule granzyme B, and immunoregulatory cytokines IL-10 or IL-2 are correlates of acute rejection, and intrarenal expression of TGF-1 mRNA, of chronic rejection. The current immunosuppressive protocol involves the use of multiple drugs, each directed at a discrete site in the T-cell activation cascade and each with distinct side effects. The immunosuppressants can be classified as inhibitors of: transcription (CsA, tacrolimus); nucleotide synthesis (azathioprine, mycophenolate mofetil, and mizoribine); growth factor signal transduction (sirolimus); and differentiation (DSG). Polyclonal antibodies and monoclonal antibodies directed at cell surface proteins are quite effective as induction therapy or anti-rejection drugs.

Measurement of total and bioactive interleukin-2 in tissue samples by immunoaffinity-receptor affinity chromatography

The detection and measurement of cytokines is an important issue in the clinico-pathological diagnosis of several clinical entities, including organ transplant rejection. Existing techniques, although sensitive, measure only total cytokine concentrations and cannot measure bioactivity. A chromatographic system combining immunoaffinity chromatography with an immobilized receptor detection cartridge has been developed for measuring total and bioactive interleukin (IL)-2 concentrations in tissue extracts prepared from biopsy materials taken from renal transplant recipients during both rejection and drug-induced nephrotoxic episodes. The technique employs a short high-pressure chromatography column packed with antibody-coated glass beads for the initial analyte separation and concentration, followed by detection of bioactive molecules through their interactions with specific, immobilized receptors. This system compares favourably with both conventional bioassays and immunoassays for measuring IL-2 in tissue samples.

Quantitation of change in the medullary compartment in renal allograft by ultrasound

Twenty-three renal allograft recipients with uncomplicated post-transplant courses were sonographically evaluated on the 3rd, 10th, 30th, and 90th post-operative day. The cortical thickness (CT), pyramidal length (PL), pyramidal width (PW), corticomedullary ratio (CMR), and medullary pyramidal index (MPI) were determined at each examination. The measurements obtained from the donor before implantation were used as the baseline. PW increased significantly in the absence of rejection and obstruction in renal allograft during the early post-transplant period. Although the MPI, and to a lesser extent the CMR, detected changes in dimensions of the medullary compartment, there was considerable intra- and inter-individual variation in their values during the post-operative period.