Kidney Transplantation From Old Deceased Donors: Impact of Uric Acid Level-A Quarter-Century of Experience in One Transplant Center

BACKGROUND

The long-term burden of higher donor age on graft function and survival after kidney transplantation remains uncertain. Because both recipient and donor characteristics have evolved and the general population age is on the increase, we looked at the causes of kidney graft outcome.

AIM

The aim of this study was to evaluate the impact of different clinical parameters on long-term outcome of older-donor kidney transplantation. This retrospective study included 345 adult patients (58 patients received kidney from donors at least 55 years old) transplanted between January 1993 and December 2005 and were followed in one center throughout the post-transplant course (median, 9.4 years). Data included recipient and donor age, cold ischemia time, delayed graft function, panel reactive antibodies, HLA mismatch, time on dialysis, graft function at different time points, uric acid level, proteinuria, immunosuppression, and biopsy-proven rejection.

RESULTS

Improvement of estimated glomerular filtration rate at 36 months after transplantation was a good prognostic factor for long-term kidney function. Higher donor age decreased the chance for improvement of kidney function by 2.8% per year of life (P = .0244). Hyperuricemia was found in 46% of the study population; estimated glomerular filtration rate less than 50 mL/min/1.72 m² was associated with hyperuricaemia. A higher uric acid level was associated with inferior kidney function in recipient of older kidneys. Graft failure occurred late (median, 6.3 years post-transplantation) in 26 (44.8%) of older-donor recipients and in 87 (30.3%) of the remaining patients.

CONCLUSIONS

Our results suggest an important association between older donor age and decreased allograft function in kidney recipients with elevated uric acid level. Recipients of older kidneys with normal uric acid level presented satisfactory outcomes.

Pretransplantation Oral Glucose Tolerance Test Can Prevent Posttransplant Diabetes Mellitus After Renal Transplantation: Preliminary Study

Posttransplant diabetes mellitus (PTDM) adversely affects renal graft and patient survival. Fasting plasma glucose (FPG) alone underestimates diagnosis of glucose metabolism disorders (GMD) detected using the oral glucose tolerance test (OGTT-75). Prediabetes including impaired fasting glucose (IFG): 100 to 125 mg/dL (5.6-6.9 mmol/L) and impaired glucose tolerance (IGT): 140 to 199 mg/dL (7.8-11 mmol/L) 2 hours post 75-g OGTT in the pretransplant period can have a connection with the occurrence of PTDM after renal transplantation (RTx). The aim of our study was to assess the benefit of performing OGTT-75 in dialyzed chronic kidney disease (stage 5) patients on the waiting list for kidney transplantation as a useful tool to prevent PTDM.

MATERIALS AND METHODS

Pretransplant glucose testing using OGTT-75 was performed in nondiabetic dialyzed chronic kidney disease patients on the waiting list for renal transplantation in the southwest region of Poland. GMD were diagnosed according to current criteria. Patients with recognized prediabetic stage were recommended a low carbohydrate diet, lifestyle modification, and increased physical activity. In the 12-month posttransplant period we estimated the prevalence of PTDM in the study group based on FPG >126 mg/dL (7 mmol/L) in 2 measurements or random blood glucose >200 mg/dL (11.1 mmol/L).

RESULTS

A total of 80 nondiabetic dialysis patients (65 hemodialysis/15 peritoneal dialysis; 47 male/33 female) met initial entry criteria. In pretransplant glucose testing prediabetes was found in 31 out of 80 patients (39%). Among them, 5 patients (6.25%) had combined IGT/IFG, 18 patients (22.5%) had IGT, and 8 patients (10%) had IFG. One year after RTx we recognized PTDM in 14% of all analyzed patients (11/80) and noticed a significant frequency of glucose disorders status change after RTx (P  =  .002).

CONCLUSION

Our findings suggest early detection of prediabetes using the OGTT-75 test in nondiabetic dialysis patients waiting for RTx to prevent occurrence of PTDM.

Endothelin A Receptors Expressed in Renal Blood Vessels of Renal Transplant Patients Are Connected With Acute Tubular Necrosis or Antibody-Mediated Rejection

BACKGROUND

The role of non-HLA antibodies named antiendothelin A receptor antibodies is potentially significant but not established. The significance of the endothelin A receptor (ETAR) and its expression in renal biopsy has not been defined. We decided to evaluate the presence and relevance of ETARs in renal transplant biopsy for cause. The aim of our study was to evaluate the immunoreactivity of the ETAR and its significance in patients who had a renal transplant biopsy due to deterioration of transplant function (biopsy for cause) with detailed characterization of staining in small and intermediate arteries of renal transplant biopsies.

METHODS

Immunohistochemical expression of ETARs was analyzed in 162 renal transplant biopsies. Microscopic evaluation of ETAR expression (polyclonal antibody) was performed on paraffin sections. ETAR expression was analyzed in renal blood vessels (small and intermediate arteries) based on three-step scale.

RESULTS

We analyzed 154 patients who had renal allograft biopsy between 6 days and 24 years (median 597 days) after transplantation. Positive staining of ETAR in small and intermediate arteries was noticed in 9 patients. Among these patients, 4 had early biopsies (<3 months after transplantation), all developed acute tubular necrosis, and 1 developed additionally acute humoral rejection. Further, 4 patients had late biopsy (1-8 years after transplantation) and all developed characteristics of antibody mediated rejection. Lastly, 1 patient had no characteristic changes in the biopsy 4 months after transplantation. Graft loss 1 year after biopsy was higher in patients who were ETAR-positive but statistical significance was not achieved.

CONCLUSIONS

The expression of endothelin receptors in renal blood vessels (small and intermediate arteries) seems to be important in diagnosis of damage during acute tubular necrosis and antibody-mediated rejection.

The Impact of Functioning Arteriovenous Fistula on Blood Pressure Control and Renal Allograft Function

INTRODUCTION

The prevalence of hypertension in renal graft recipients is high. It was postulated that central arteriovenous anastomosis may significantly reduce blood pressure. This preliminary study evaluates the impact of functioning arteriovenous fistula (AVF) on blood pressure control and renal allograft function.

MATERIALS AND METHODS

One hundred sixty-two previously hemodialyzed kidney transplant recipients (108 males, 54 females, aged 52.7 ± 13.2 years, mean 6.9 ± 5.1 years after transplantation), who had scheduled visits in the first two weeks of March 2015, were included in the study. The recipients were divided into two groups depending on AVF function (65 AVF+ and 97 AVF-).

RESULTS

Functioning AVF was more prevalent in males than females (47.2 % vs 25.9 %, P = .009). Both groups presented similar allograft function despite the fact that interval from transplantation to examination day in the AVF+ group was significantly shorter than in the AVF- group (5.2 ± 5.3 vs 8.1± 4.5 years; P < .001). The mean systolic blood pressure (135.0 ± 17.0 vs 138.7 ± 14.1 mm Hg, P = .13) was similar in both study groups, but diastolic blood pressure in the AVF+ group was lower than in the AVF- group (80.0 ± 7.0 vs and 83.7 ± 9.2 mm Hg, P = .006). The proportion of patients with diastolic blood pressure >80 mm Hg was significantly higher in patients without functioning AVF (35 % in the AVF- group vs 20 % in the AVF+ group, P= .038). In multivariate analysis, AVF presence was the only factor significantly influencing a diastolic blood pressure with odds ratio 0.43 (95% CI 0.19-0.99, P = .048), which supports AVF as a potentially positive influence on blood pressure control.

CONCLUSIONS

The presence of AVF in renal transplant recipients was associated with a slight decrease in diastolic blood pressure without clear effect on renal function.

Expression of PBMC TLR4 in Renal Graft Recipients Who Experienced Delayed Graft Function Reflects Dynamic Balance Between Blood and Tissue Compartments and Helps Select a Problematic Patient

Both Toll-like receptor 4 (TLR4) and monocytes focus stimuli, causing them to contribute differently to chronic injury of a transplanted kidney.

AIM

The aim of our study was to determine if TLR4 monocyte is a diagnostic tool and possibly a target for therapeutic intervention.

MATERIALS

We studied 143 kidney transplant (KT) patients (88 male, 55 female; 50.3 ± 12.8 years); median was 10.4 post KT, follow-up was 11.4 months, and 46 patients had delayed graft function (DGF+) history. Control group (38 healthy volunteers) had monocyte mRNA-TLR4 expression (TLR4ex). DGF+ were divided by median of TLR4ex (-0.1034) into 2 groups: low-TLR4 expression (L-TLR4ex) and high-TLR4 expression (H-TLR4ex).

RESULTS

We showed that in comparison with DGF-, the DGF+ had much lower TLR4ex, and worse KT function both currently (TLR-day) (serum creatinine [sCr] P = .002; estimated glomerular filtration rate [eGFR] P = .001) and post follow-up (sCr P = .006; eGFR P = .005). The DGF+ with L/H-TLR4ex comparison showed no differences in TLR-day KT function but did show differences in post follow-up (sCr P = .01; eGFR P = .02; ΔeGFR% P = .001). Regression analysis showed an association between recipient age, tacrolimus concentration, and uremic milieu (ie, TLR-day sCr and GFR with TLR4ex). Reverse regression analysis indicated an association of TLR4ex (especially L/H-TLR4ex) with post follow-up parameters of KT function and numeric/qualitative measures of change.

CONCLUSION

DGF affects the fate of a graft. Within a several months after transplantation, TLR4ex of peripheral blood mononuclear cells declines in DGF patients. Low LR4ex in patients with DGF+ is associated with poor prognosis for the efficiency of the KT. In patients with DGF+, the proper selection of immunosuppression (tacrolimus dosing) is very important. Higher concentrations of tacrolimus may improve prognosis. The analysis of TLR4ex change may be a useful parameter for the real assessment of immunosuppression efficacy. It is important for transplanted organ function that peripheral blood mononuclear cells effectively leave circulation and remain in the graft.

Increased plasma matrix metalloproteinase-2 (MMP-2), tissue inhibitor of proteinase-1 (TIMP-1), TIMP-2, and urine MMP-2 concentrations correlate with proteinuria in renal transplant recipients

BACKGROUND

The most frequent cause of kidney allograft loss is chronic allograft injury, often with proteinuria as the clinical feature. Occurrence of proteinuria late after kidney transplantation is associated with worse graft function and patient survival.

AIM

The aim of the study was to assess plasma and urine matrix metalloproteinases (MMP-2 and MMP-9) and tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) in proteinuric renal transplant recipients (RTRs). The factors were determined by enzyme-linked immunosorbent assay in 150 RTRs (51 women and 99 men), aged 49.2 ± 11.5 years, at mean 73.4 ± 41.2 months after kidney transplantation (range: 12 to 240 months).

RESULTS

Proteinuric RTRs compared with non-proteinuric RTRs had higher median plasma MMP-2 (P = .012), TIMP-1 (P = .0003), and TIMP-2 (P = .0021) concentrations, as well as higher urine MMP-2 (P < .0001) excretion. The presence of proteinuria had no impact on plasma MMP-9 and urine MMP-9, TIMP-1, and TIMP-2. Proteinuria and estimated daily proteinuria (uPr:uCr) correlated positively with plasma MMP-2 (rs = 0.226, P = .0054 and rs = 0.241, P = .003), TIMP-1 (rs = 0.305, P = .00015 and rs = 0.323, P = .000055), TIMP-2 (rs = 0.273, P = .0007 and rs = 0.269, P = .001) and urine MMP-2 (rs = 0.464, P < .0001 and rs = 0.487, P < .0001), respectively. Proteinuric RTRs had impaired graft function with higher median serum creatinine concentrations (1.91 [1.60-2.43] mg/dL versus 1.41 [1.20-1.65] mg/dL, P < .00001) and lower estimated glomerular filtration rate (36 [28-45] mL/min/1.73 m(2) versus 53 [43-61] mL/min/1.73 m(2), P < .00001) than RTRs without proteinuria.

CONCLUSIONS

Our research revealed that in RTRs, proteinuria was significantly associated with increased concentrations of enzymes involved in extracellular matrix (ECM) degradation: plasma MMP-2, TIMP-1, TIMP-2, and urine MMP-2. Findings strongly emphasize increased plasma TIMPs in proteinuric RTRs that inhibit degradation of ECM by MMPs and favor excessive deposition of ECM proteins.

Advanced age of renal transplant recipients correlates with increased plasma concentrations of interleukin-6, chemokine ligand 2 (CCL2), and matrix metalloproteinase 2, and urine concentrations of CCL2 and tissue inhibitor of metalloproteinase 1

BACKGROUND

Advanced age of renal transplant recipients (RTRs) has a negative impact on kidney allograft survival through impaired extracellular matrix degradation by the matrix metalloproteinases/tissue inhibitors of metalloproteinases (MMPs/TIMPs) system. Moreover, older RTRs are at risk of smoldering inflammation, known as inflammaging.

AIM

The aim of the study was to assess the impact of a RTR's age on plasma and urine concentrations of interleukin 6 (IL-6), chemokine ligand 2 (CCL2), and the MMPs/TIMPs system.

MATERIAL AND METHODS

One hundred fifty adult RTRs (8.7% ≥ 65 years) and 37 adult healthy volunteers (10.8% ≥ 65 years) were enrolled in the study. The studied factors (IL-6, CCL2, MMP-2, MMP-9, TIMP-1 and TIMP-2) were quantified in plasma and urine with enzyme-linked immunosorbent assay. The Mann-Whitney U test and Spearman's (rs) rank correlation were applied, and differences with a P < .05 were considered statistically significant.

RESULTS

There was a weak but significant positive correlation between increasing RTR's age and plasma IL-6 (rs = 0.18, P = .028), CCL2 (rs = 0.27, P = .001), and MMP-2 (rs = 0.20, P = .017), as well as urine CCL2 (rs = 0.16, P = 0.050) and TIMP-1 (rs = 0.20, P = .014) concentrations.

CONCLUSIONS

Advancing age of RTRs correlates with increasing plasma IL-6 and CCL2 concentrations, reflecting smoldering inflammation (known as inflammaging) and alterations in MMPs/TIMPs profiles, especially with increased plasma MMP-2 and urine TIMP-1 concentrations.

Impaired kidney allograft: how long can it function? A single-center study of the transplantation population

Impaired renal graft function is a matter of particular concern during post-transplantation care because low estimated glomerular filtration rate (eGFR) is a risk factor for graft loss. The aim of the study was to assess risk factors for inferior outcomes of kidney transplantations with low eGFRs. We identified 72 patients who underwent transplantation between 1999 and 2005 who had chronic renal graft dysfunction after 6 months post-transplantation (eGFR < 40 mL/min/1.73 m(2)), received a kidney transplant between 1999 and 2005, and were treated in one center through the entire post-transplantation course. Three patients who were lost for follow up after 6.4, 6.7, and 8.5 years are not included in this analysis. A group of 23 patients (33%) had chronic kidney disease stage 4 (eGFR < 30 mL/min/1.73 m(2)) at 6 months. In 39 patients (56%), delayed graft function was diagnosed. Forty-eight patients (70%) had at least one episode of acute graft rejection. Results were confirmed using biopsy in 39 patients. Eight patients (12%) died and 35 patients (51%) lost their grafts between 1.6 and 14 years (median, 6.3 years). The remaining 26 (38%) patients have still functioning allografts 11 years after transplantation (median). The initial immunosuppression included calcineurin inhibitor (CNI) in all cases. At the end of study, 6 (8.3%) patients received mammalian target of rapamycin inhibitor plus steroids, whereas the remaining were treated with CNIs. Improvement of kidney function by 15% was observed in 23% of the studied population between 6 and 24 months. This satisfactory outcome was a result of the careful follow-up examinations and comprehensive medical care provided by our dedicated staff of nurses and physicians. Improvement of kidney function may reflect a state of immune quiescence in some patients which allows them to sustain a functioning kidney despite injury.

Risk factors for glucose metabolism disorders after kidney transplantation with uneventful course

A wide range of glucose metabolic disorders (GMDs) often arise after renal transplantation that predispose to graft dysfunction, infections, and cardiovascular disease. This study evaluated the risk factors for GMDs among 50 patients including 30 males and overall mean age 44.9 +/- 12.1 years. All 50 subjects displayed normal glucose tolerance tests pretransplantation and no family history of diabetes. They were selected from the 99 consecutive patients transplanted from April 2005 to January 2006 based upon uneventful posttransplantation course, without rejection episodes or hepatitis C virus (HCV) infections. The study concentrated on risk factors originating during the dialysis period. Even in this selected group, the risk of posttransplant GMD development was high (28%). Patients with GMDs showed significantly worse renal function at 1 month after transplantation (serum creatinine concentration: 1.70 +/- 1.67 mg/dL in the GMD group vs. 1.44 +/- 0.96 mg/dL in the group without GMDs [P = .027] and eGFR, 56.68 +/- 22.70 mL/min/1.73 m(2) versus 71.29 +/- 27.37 mL/min/1.73 m(2), respectively, [(P = .099)]. In a logistic regression model, a statistically significant difference between the groups was shown only for cold ischemia time (P = .037). In the logistic regression model with two independent variables, statistical significance was observed (P = .038) for body mass index at the time of transplantation. In this model, a lower pretransplant serum insulin concentration showed an influence that bordered on significance (P = .074). This study confirmed that the etiology of GMD after kidney transplantation is multifactorial, and at least in part connected with the pre-transplantation period.

Mycophenolate mofetil severely depresses antibody response to CMV infection in early posttransplant period

Estimation of anti-CMV-IgG and anti-CMV-IgM is considered a relatively inexpensive screening tool of CMV status. The aim of study was to estimate how the immunosuppressive protocol influence serum anti-CMV IgG and IgM concentration in renal graft recipients and to estimate the adequacy of anti-CMV-IgG concentration and anti-CMV-IgM index as screening parameters of active CMV disease in patients receiving different immunosuppression. The study group consisted of 33 patients with clinical signs of CMV disease who received one of three types of immunosuppression: (1) azathioprine (Aza) + cyclosporine (CyA) + prednisone (Pr), 20 patients; (2) mycophenolate mofetil (MMF) + CyA + Pr, eight patients; tacrolimus (Tac) + MMF, five patients. Patients were enrolled when the pp65-antigen (pp65) of PBL was positive within 1 to 5 months after transplant (75 patients tested). The IgM-i in the Aza + CyA + Pr group was higher than in MMF + CyA + Pr group (2.73 + 1.8 vs 1.08 +/- 1.07, P =.021). The IgM-i in the Aza + CyA + Pr group was higher than in Tac + MMF (2.73 +/- 1.8 vs 0.78 +/- 0.69; P =.014). There was no difference in IgM-i between MMF + CyA + Pr and Tac + MMF. There was no difference in relative increase of IgG-c among all groups but there was a difference in relative increase of IgM-i between Aza + CyA + Pr and MMF + CyA + Pr groups (6.7 +/- 9.4 vs 2.3 +/- 5.9; P =.007) and between Aza + CyA + Pr and MMF + Tac groups (6.7 +/- 9.4 vs 0.6 +/- 0.54; P =.003). Immunosuppressive protocols including MMF exert an inhibitory influence on B-cell response and synthesis of anti-CMV-IgM. It makes the anti-CMV-IgM index an inadequate rough screening diagnostic parameter of active CMV disease.