Frequencies of circulating B-cell subpopulations before kidney transplantation identify patients at risk of acute rejection.

The response mediated by B lymphocytes has a crucial impact on kidney transplantation due to the role of anti-human leukocyte antigen antibodies in rejection and the contradictory observation of high B-lymphocyte numbers in tolerant kidney transplant recipients. The basis of the contradiction could lay in the different function of B-cell subsets depending on their degree of differentiation. We ought to measure circulating B-lymphocyte percentages in patients with end-stage renal disease before kidney transplantation to identify those with a high risk of acute rejection. Eighty patients on the waiting list for kidney transplantation followed up in our center were recruited from 2010, and samples were taken just before kidney transplantation. Eleven of 80 patients presented an episode of acute rejection (13.75%) and had an increased frequency of switched (SW) B cells compared with the rejection-free group (median [interquartile range] 24.5% [18.6% to 39.6%] vs 15.1 [8.45% to 23.4%]; P = .025). Subsequently, the frequency of SW B cells was assessed as a predicting factor of acute rejection. A value higher than 18.4% predicted patients at risk of suffering an acute rejection episode with a sensitivity of 81.8% and a specificity of 60.9% and an area under the curve of 71.2%. Moreover, a decrease in naïve B-cell subsets was related to patients at risk of acute rejection. The percentage of circulating B-cell subsets before kidney transplantation could be used as biomarker of risk to suffer acute rejection. These unicenter data must be validated in multicenter studies.

New-onset diabetes after transplantation: drug-related risk factors.

INTRODUCTION: New-onset diabetes after transplantation (NODAT), an important complication of renal transplantation leads to reduced graft function and increased patient morbidity and mortality. Because of its high incidence and immense impact on clinical outcomes, prevention of NODAT is highly desirable. Several modifiable and nonmodifiable risk factors for NODAT have been described. The aim of this study was to analyze the influence of various drugs on the development of NODAT during the first year. METHODS: A retrospective analysis was performed on 303 adult kidney transplant recipients free of previously known diabetes. NODAT was defined as a fasting plasma glucose level ≥ 126 mg/dL confirmed by repeat testing on a different day. We excluded patients with transiently elevated fasting plasma glucose during the first 3 months. RESULTS: NODAT was diagnosed in 37 recipients (12.2%). Univariate analysis identified several variables related to NODAT: recipient age (P < .001), body mass index (P < .001), donor age (P = .005), family history of diabetes (P < .001), statin use (P = .005), diuretic use (P = .040) and tacrolimus therapy (P = .029). After multivariate analysis, recipient age (relative risk [RR] = 1.060, 95% confidence interval [CI] 1.019- 1.102, P = .004), family history of diabetes (RR = 3.562, 95% CI 1.574-8.058, P = .002), smoking habit (RR 2.514, 95% CI 1.118-5.655, P = .026) and diuretic use (RR = 2.496, 95% CI 1.087-5.733, P = .031) were independently associated with NODAT development. CONCLUSIONS: In our population of kidney transplant recipients, the main nonmodifiable risk factors for NODAT were recipient age and a family history of diabetes. Diuretic use was a modifiable risk factor associated with the development of NODAT. To reduce NODAT incidence, it is necessary to consider not only immunosuppressive therapy, but also concomitant drugs such as diuretics.

Early prediction of new-onset diabetes mellitus by fifth-day fasting plasma glucose, pulse pressure, and proteinuria.

Renal transplant recipients are at high risk of cardiovascular disease (CVD). New-onset diabetes mellitus after transplantation (NODAT) contributes to the risk of CVD, reducing graft and patient survival. To improve outcome of kidney transplant recipients, it is of great interest to identify those patients who will develop NODAT. The aim of our study was to explore the predictive value of fifth-day fasting plasma glucose (FPG), third-month proteinuria, and pulse pressure (PP) for NODAT development. We analyzed 282 non-previously-diabetic kidney transplants in our center. Fifth-day FPG, PP, and third-month 24-hour proteinuria were collected. NODAT was defined at month 12 according to the "consensus guidelines": symptoms of diabetes plus casual glucose concentrations ≥ 200 mg/dL or FPG ≥ 126 mg/dL. Some 46 patients (16.3%) developed NODAT at month 12. Fifth-day FPG (133 ± 35 vs 108 ± 16 mg/dL, P < .001) and PP (57 ± 17 vs 49 ± 15 mm Hg, P = .007) were significantly higher in patients at risk for NODAT, but there was no difference in third-month proteinuria (652 ± 959 vs 472 ± 1336 mg, P = .390). A multivariate regression model showed an increased risk for NODAT associated with recipient age, body mass index, smoking habit, and a fifth-day FPG ≥ 126 mg/dL (relative risk 4.784, 95% confidence interval 2.121-10.788, P = .0002). The negative predictive value of a fifth-day FPG ≥ 126 mg/dL for predicting 1-year NODAT was 89.4%. Fifth-day FPG was independently related to NODAT development. The detection of a fifth-day FPG ≥ 126 mg/dL increases the risk of suffering NODAT more than 4 times. Fifth-day FPG < 126 mg/dL allows us to identify a transplant population with a low risk (near 10%) for NODAT.

Influence of interleukin-6 promoter polymorphism -174 g/c on kidney graft outcome.

BACKGROUND: The cytokine interleukin-6 (IL-6) is important in both immune responses and cardiovascular diseases. The IL-6 promoter polymorphism -174 G/C is associated with increased plasma concentrations of IL-6. The relationship between IL-6 polymorphisms and graft survival, cardiovascular events, and new-onset diabetes mellitus after kidney transplantation is controversial. OBJECTIVE: To analyze whether IL-6 (-174 G/C) polymorphism influences kidney graft survival or development of chronic allograft nephropathy, cardiovascular events, or new- onset diabetes. METHODS: The IL-6 promoter polymorphism (-174 G/C) was analyzed using the polymerase chain reaction with sequence-specific primers in 335 kidney transplant recipients. Data for graft survival, chronic graft nephropathy, cardiovascular events, and new-onset diabetes were obtained retrospectively from clinical records. Categorical variables were compared between individuals with CC, GG, and GC genotypes using χ2 tests. Survival analysis was performed using the Kaplan-Meier method, comparing groups using the log-rank test. RESULTS: No significant differences were observed in 5-year graft survival between individuals with CC and GC/GG genotypes (85.3% vs 77.1%; P=.22). Nor were significant differences noted in the rates of chronic allograft nephropathy (37.5% vs 33.8%; P=.48), cardiovascular events (10.0% vs 23.0%; P=.10), or new-onset diabetes (7.5% vs 11.8%; P=.28). CONCLUSION: There is no association between IL-6 (-174 G/C) polymorphism and graft survival or development of chronic allograft nephropathy, cardiovascular events, or new- onset diabetes.

Quantitative assessment of serum free light chains in renal transplantation.

Plasma cell dyscrasias can cause renal disease. Sensitive methods have recently been introduced to quantify serum free light chains (sFLCs). Renal function may influence the variability of these methods, as shown in chronic kidney disease (CKD) patients, but this problem has not been widely addressed in renal transplant patients. Herein, we examined the association between polyclonal sFLC concentrations and renal function among a population of renal transplant patients. We studied 102 kidney allograft recipients and 53 CKD patients classified according to KDOQI (Kidney Disease Outcomes Quality Initiative) stages. None of them had been diagnosed with monoclonal gammopathy. sFLCs were quantified by nephelometry. Both serum κ and λ free light chain concentrations rose progressively through each stage of KDOQI among both transplant and nontransplant patients (P<.0001). In the former setting, sFLC concentrations significantly correlated, using a Spearman coefficient, with serum creatinine, and serum cystatin concentrations as well as estimated glomerular filtration rate: namely, 0.723, 0.797, and -0.711 for sκFLC and 0.705, 0.759, and -0.694 for sλFLC, respectively (P<.0001 in all cases). Spearman correlation coefficients in nontransplant patients were: 0.559, 0.848, and -0.766 for sκFLC and 0.702, 0.875, and -0.855 for sλFLC, respectively (P<.0001 in all cases). In conclusion, sFLCs must be interpreted cautiously due to their clear association with renal function. Therefore, renal transplantation did not produce changes that were different from those dependent on renal function.

Number of peripheral blood regulatory T cells and lymphocyte activation at 3 months after conversion to mTOR inhibitor therapy.

BACKGROUND: Mammalian target of rapamycin (mTOR) inhibitors are effective for induction and maintenance of regulatory T cells (Tregs). OBJECTIVE: To assess the effects of conversion from calcineurin inhibitors (CNIs) to mTOR on the number of circulating Tregs and lymphocyte activation. PATIENTS AND METHODS: In 18 renal transplant recipients receiving CNI therapy (cyclosporine in 9, and tacrolimus in 9), treatment was converted to mTOR inhibitors (everolimus in 14, and rapamycin in 4). Peripheral blood samples were obtained before and 3 months after conversion. The number of circulating Tregs was measured using flow cytometry, and defined as CD4+/CD25high/CD127low/CD27+/CD62L+/CD45RO+/Foxp3+. Lymphocyte activation was assessed indirectly according to production of intracellular adenosine triphosphate (iATP) on polyclonal activation using a phytohemaglutinin assay (Immuknow; Cylex, Inc, Columbia, Maryland). RESULTS: In 15 patients (83.3%), the absolute number of Tregs increased significantly (P=.001) after conversion (median, 16.35 cells/mm3; 95% confidence interval [CI], 13.97-21.94) vs 3 months after conversion (32.03 cells/mm3; 95% CI, 26.25-41.66). The iATP production decreased from 326 ng/mL (95% CI, 302-419) to 248 ng/mL (95% CI, 196-318; P=.02), and increased in 4 patients (22.22%). No significant correlation was demonstrated between Treg concentration and change in iATP production. No rejection episodes were reported during follow-up. CONCLUSIONS: Despite the small number of patients in whom therapy was converted from CNI inhibitors to mTOR inhibitors, the data suggest an increase in the absolute number of Tregs after conversion. In addition, the concentration of activated peripheral CD4+ T cells decreased to nearly that associated with risk of infection due to overimmunosuppression.

Chronic renal disease in renal transplant patients: management of cardiovascular risk factors.

Kidney transplantation is the treatment of choice for patients with end-stage renal disease. Despite improvements in short-term patient and graft outcomes, there has been no major improvement in long-term outcomes. The aim of this study was to determine the prevalence of cardiovascular risk factors, such as hypertension, dyslipidemia, diabetes, chronic kidney disease, and obesity, and the impact of their control among 526 stable renal transplant recipients according to the guidelines in the general population. Mean blood pressure was 133 +/- 16/81 +/- 9 mm Hg. The proportion of patients on antihypertensive therapy was 75%, and on ACE inhibitors or angiotensin II receptor blockers, 26%. The mean cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides were 195 +/- 41, 115 +/- 32, 51 +/- 17, and 137 +/- 75 mg/dL, respectively. The proportion of patients on statin treatment was 49.7%, and those with body mass indices between 25 and 30, 30 and 35, and >35 kg/m(2) were 35%, 15%, and 4%. We observed a high prevalence of chronic kidney disease, hypertension, dyslipidemia, and obesity among renal transplant patients. Suboptimal control was frequent and control of some of these complications was far below targets established for nontransplant patients despite progressive intensification of therapy with functional graft decline. The findings of this study may have an impact on the management of renal transplant recipients.

T(H)17 versus Treg cells in renal transplant candidates: effect of a previous transplant.

INTRODUCTION: The T(H)1 and T(H)2 cells were described several years ago. However, this dichotomy has been disrupted by the description of other CD4(+) T cell subsets: the proinflammatory interleukin (IL)-17-producing T cells (T(H)17) and regulatory T cells (Tregs). The latter group inhibits the immune responses driven by T(H)1, T(H)2, and T(H)17 cells. IL-6 is involved in T(H)17 development, down-regulating Treg differentiation. Our hypothesis suggested that an imbalance between T(H)17 and Tregs enhances immune responses among renal transplant patients. MATERIALS AND METHODS: We studied 26 end-stage renal disease (ESRD) subjects and 10 patients awaiting a second renal transplant after previous graft dysfunction. We assessed the number of CD4(+)CD25(+)Foxp3(+) cells and serum levels of IL-17, the prototypic interleukin of T(H)17 cells. RESULTS: We observed a lower number of CD4(+)CD25(+)Foxp3(+) T cells among patients with previous graft dysfunction than those with ESRD (median 3.37 vs 8.63 cells/mm(3), P = .008). In contrast, IL-17 serum levels were augmented in graft dysfunction (median 4.45 pg/mL) compared with ESRD patients (1.39 pg/mL, P = .036), suggesting a proinflammatory state in patients awaiting a second renal transplant. CONCLUSION: The emerging alloresponse from a previous transplant favors the generation of T(H)17 instead of Treg cells. The enhanced activity of T(H)17 cells in retransplanted patients may down-regulate Treg cells, producing a proinflammatory environment that favors rejection of the next transplant.

Survival after dialysis initiation: a comparison of transplant patients after graft loss versus nontransplant patients.

BACKGROUND: A substantial number of patients return to dialysis therapy after a renal transplant fails. It is not clear whether mortality increases among patients with graft failure relative to those who initiate dialysis but who have not yet received a kidney transplant. PATIENTS AND METHODS: We compared the outcomes of an incident cohort of patients (n = 194) with a cohort of renal transplant patients who returned to dialysis after graft loss (n = 74). We analyzed the morbidity and mortality after dialysis initiation and the parameters during the year beforehand. RESULTS: Mortality among post-graft loss dialysis patients was higher than transplant-naive patients (relative risk [RR]: 2.05; 95% confidence interval [CI]: 1.26-3.35). Additionally, complications, such as the number of hospitalizations during the first year after dialysis initiation, were higher (29% vs 57%; P > .001). At dialysis initiation no differences were found in glomerular filtration rate, although hemoglobin and albumin levels were lower and C-reactive protein was higher in post-graft loss dialysis patients. CONCLUSIONS: Mortality among patients on dialysis therapy after graft loss increased significantly compared with mortality among patients who initiated dialysis for the first time, despite specialty physicians being aware of them. Additional studies are urgently needed to define the mechanisms of the increased risk and strategies to decrease mortality.

Changes in the expression of the immunoglobulin-like transcript 3 (ILT3) and ILT4 receptors in renal allograft recipients: effect of donor and recipient aging.

INTRODUCTION: The aim of the present study was to investigate the number and phenotype of pre- and posttransplant peripheral blood dendritic cells (DCs) in kidney graft recipients to correlate with CD4(+)CD25(high) Treg and CD8(+)CD28(-) cells. Data were analyzed according to the age of the donor-recipient pairs. MATERIALS AND METHODS: A cohort of 49 cadaveric kidney transplant recipients was prospectively studied pretransplant and 6 months posttransplant by three-color flow cytometry with specific monoclonal antibodies. Patients were subgrouped according to age (elderly were considered above 60 years old and young below 55 years old) in the following donor-recipient pairs: aged/aged, young/aged, aged/young, young/young. RESULTS: At 6 months posttransplant, the proportion of cells tended to increase when the donor was young, regardless of the recipient. Importantly, there was a significant correlation between the numbers of immunoglobulin-like transcript 4(+) DCs and CD4(+)CD25(high) Treg cells before transplantation (r = .476, P = .004) and at 6 months (r = .408, P = .013). A significant association was also observed between ILT4(+) DCs and CD8(+)CD28(-) pretransplant (r = .540, P = .001) and at 12 months posttransplant (r = .609, P = .012). CONCLUSIONS: Renal grafts from young but not from aged donors seem to induce DC of a tolerogenic phenotype, both in aged and young recipients. These preliminary results suggested that donor age may have consequences in terms of tolerance induction.

Association between serum soluble CD30 and serum creatinine before and after renal transplantation.

OBJECTIVE: There is increasing evidence that circulating levels of soluble CD30 (sCD30) may represent a biomarker for outcome in kidney transplantation. The aim of this study was to measure the pre- and posttransplantation serum levels of sCD30 in cadaveric kidney transplant recipients and correlate them with serum creatinine. PATIENTS AND METHODS: Serum sCD30 was measured by a commercial enzyme-linked immunosorbent assay (ELISA) from prospective samples of 38 kidney allograft recipients serially transplanted at our center. Samples were collected at day 0 pretransplantation and at months 6, 12, 18, and 24 posttransplantation. We also studied sera from 29 patients with chronic kidney disease (CKD) at different stages of the K/DOQI guidelines, as a control group. RESULTS: Serum levels of sCD30 decreased significantly in samples posttransplantation compared with pretransplantation. The significant decrease after transplantation may be related to the improvement in renal function since we observed a significant correlation between serum levels of sCD30 and creatinine (sCr) at all times of the study. In addition, the patients with chronic renal failure showed a significant association between serum sCD30 and sCr (r = .454; P = .013). CONCLUSIONS: Our results did not suggest that the measurement of sCD30 may be used as a valuable biomarker in renal transplantation. Increased levels may be related to a decrease in its renal elimination.

Cytokine polymorphisms and risk of infection after kidney transplantation.

INTRODUCTION: Infection remains a significant cause of morbidity and mortality after solid organ transplantation. Genetic background has an influence on the incidence of infection. The aim of our study was to analyze the relationship between cytokine polymorphisms and infection in our kidney transplant recipients. METHODS: DNA from 255 kidney transplant recipients was isolated routinely. Polymerase chain reaction sequence-specific primer was performed using commercially available cytokine genotyping primer packs to determine polymorphisms of interleukin (IL)-10, transforming growth factor-beta, tumor necrosis factor-alpha, interferon-gamma, IL-6, IL-4, IL-2, IL-12, IL-4R alpha, IL-1RA, IL-1R, IL-1 beta, and IL-1 alpha. The appearance and number of infections within the first year after transplantation were identified retrospectively. RESULTS: One hundred twenty-two patients experienced at least one episode of infection in the first year after transplant. The frequency of the -511 IL-1beta CC genotype and the frequencies of the -1188 IL-12 CA and CC genotypes were significantly higher among the infected patients compared with the noninfected patients. We failed to observe significant differences in the genotype distribution of the other analyzed cytokines regarding the incidence of infection. After adjusting, recipient IL-1beta (-511 CC) genotype (relative risk [RR] 2.67, 95% confidence interval (CI) 1.30 to 5.49, P = .007) and recipient IL-12 (-1188 CA and CC) genotypes (RR 2.57, 95% CI 1.22 to 5.38, P = .012) predicted independently the risk of infection in the first year after kidney transplantation. CONCLUSION: Kidney transplant recipients with -511 IL-1beta CC genotype or with -1188 IL-12 CA and CC genotypes were at higher risk of developing infections in the first year after transplantation. Patients with genetic susceptibility to infection may benefit from less potent immunosuppressive therapy and more intense preventive measures.

Biliopancreatic diversion in a renal transplant patient.

Surgery is usually the only solution to modify the evolution of morbid obesity and resolve the associated co-morbidities. There is very little written regarding malabsorptive surgery and transplantation. A 48-year-old male with hypertension, hyperuricemia and obesity underwent renal transplantation in 1994 for renal amyloidosis. He was maintained on oral immunosuppressive cyclosporine. The patient developed uncontrollable hypertension, hyperlipemia, hyperglycemia and increasing weight to a BMI of 44. Thus, in December 2004, he underwent biliopancreatic diversion (BPD). After 18 months follow-up, he has lost 85% of his excess weight, and his hypertension, hyperglycemia and hyperlipemia are markedly improved. Renal function was not modified, nor were the levels of cyclosporine. He has had no complications derived from the BPD, and has a better quality of life.

Impact of HLA antibodies on transplant glomerulopathy.

The influence of humoral rejection on the development of chronic allograft nephropathy (CAN) is controversial, especially in relation to transplant glomerulopathy. The aim of our study was to analyse the influence of anti-HLA antibodies on the development of transplant glomerulopathy (cg0, cg1, cg2, and cg3; Banff'97). We selected all renal transplants patients from 1975 to 2003 who had a functioning graft for at least 6 months and a clinically indicated graft biopsy with CAN and chronic glomerular changes (case group). We studied the presence of anti-HLA antibodies (Ab) in the last serum taken while the graft was functioning and divided them into three groups according to the severity of glomerular lesions. We also selected 52 contemporary and comparable cases without transplant glomerulopathy (control group). A total of 77 case had transplant glomerulopathy: 39 cg1, 29 cg2, and 9 cg3. Pretransplant Ab titers and number of previous blood transfusions were higher among the subgroup with the most severe glomerulopathy. Patients who developed posttransplant anti-HLA Ab more frequently showed transplant glomerulopathy. Serum creatinine and proteinuria were higher among cases with chronic glomerulopathy, and more grafts were lost in that group. Thus, the presence of HLA-Ab is a key factor in the development of transplant glomerulopathy and chronic allograft rejection.

Hypertension and long-term renal allograft survival: effect of early glomerular filtration rate.

BACKGROUND: For many years, hypertension has been related to long-term survival of patients and kidney grafts, although the nature of this relationship has not been completely defined. The aim of this study was to analyse the influence of early glomerular filtration rate on post-transplant hypertension and on graft survival. METHODS: A total of 432 kidney transplanted patients on cyclosporin therapy, with a functioning graft for at least 1 year, were studied. They were divided into two groups depending on their early creatinine clearance: group A [<60 ml/min (n=270)] and group B [>60 ml/min (n=162)]. RESULTS: There were no differences in sex, aetiology of renal failure, number of retransplants, PRA, HLA mismatches and pre-transplant blood pressure. One year after transplantation, blood pressure was higher in group A (systolic BP 148/diastolic BP 86/mean BP 117) than in group B (systolic BP 140/diastolic BP 82/mean BP 111) (P<0.003). We observed a negative correlation between early creatinine clearance and 1-year blood pressure (P<0.01). Five and 10 year graft survival was 60 and 37% in group A and 87 and 69% in group B, respectively (P<0.000). A multivariate Cox analysis showed that 1-year blood pressure (P<0.0029, RR=1.76) and early creatinine clearance (P<0.000, RR=3.27) had a significant influence on graft survival. CONCLUSIONS: The 1-year post-transplant blood pressure is a non-immunological risk factor in long-term graft survival. Patients with a lower initial glomerular filtration rate are more susceptible to the development of secondary hypertension and worse graft survival.