Serum uromodulin-a marker of kidney function and renal parenchymal integrity.

Background: An ELISA to analyse uromodulin in human serum (sUmod) was developed, validated and tested for clinical applications. Methods: We assessed sUmod, a very stable antigen, in controls, patients with chronic kidney disease (CKD) stages 1-5, persons with autoimmune kidney diseases and recipients of a renal allograft by ELISA. Results: Median sUmod in 190 blood donors was 207 ng/mL (women: men, median 230 versus 188 ng/mL, P = 0.006). sUmod levels in 443 children were 193 ng/mL (median). sUmod was correlated with cystatin C (rs = -0.862), creatinine (rs = -0.802), blood urea nitrogen (BUN) (rs = -0.645) and estimated glomerular filtration rate (eGFR)-cystatin C (rs = 0.862). sUmod was lower in systemic lupus erythematosus-nephritis (median 101 ng/mL), phospholipase-A2 receptor- positive glomerulonephritis (median 83 ng/mL) and anti-glomerular basement membrane positive pulmorenal syndromes (median 37 ng/mL). Declining sUmod concentrations paralleled the loss of kidney function in 165 patients with CKD stages 1-5 with prominent changes in sUmod within the 'creatinine blind range' (71-106 µmol/L). Receiver-operating characteristic analysis between non-CKD and CKD-1 was superior for sUmod (AUC 0.90) compared with eGFR (AUC 0.39), cystatin C (AUC 0.39) and creatinine (AUC 0.27). sUmod rapidly recovered from 0 to 62 ng/mL (median) after renal transplantation in cases with immediate graft function and remained low in delayed graft function (21 ng/mL, median; day 5-9: relative risk 1.5-2.9, odds ratio 1.5-6.4). Immunogold labelling disclosed that Umod is transferred within cytoplasmic vesicles to both the apical and basolateral plasma membrane. Umod revealed a disturbed intracellular location in kidney injury. Conclusions: We conclude that sUmod is a novel sensitive kidney-specific biomarker linked to the structural integrity of the distal nephron and to renal function.

Dynamics and Diagnostic Relevance of Kynurenine Serum Level after Kidney Transplantation.

BACKGROUND: Inflammatory events after kidney transplantation (Tx) may lead to activation of the tryptophane-catabolizing enzyme indoleamine 2,3-dioxygenase followed by the formation of kynurenine (KYN). Post-transplant KYN serum levels in kidney allograft recipients were analyzed for their diagnostic value. MATERIAL AND METHODS: This was a retrospective analysis of KYN levels (normal value: 2.7±0.6 nmol/ml) measured in 4083 blood samples collected from 355 kidney graft recipients in connection with uncomplicated courses, acute rejections (ARs), infections, and type of immunosuppression. We performed descriptive data analysis and analysis of variance. RESULTS: In 212 recipients with immediately functioning grafts, the KYN levels dropped from pre-Tx 13.3±5.9 nmol/ml to nearly normal values at day 5 (5.8±3.0 nmol/ml). In patients with delayed graft function, the KYN reduction started only after the last hemodialysis treatment. With respect to ARs in recipients with creatinine values <300 µmol/l pre-AR, the increase of KYN levels depended on the severity of ARs (steroid-sensitive ARs: from 4.5±1.4 to 6.0±6.1 nmol/ml; steroid-resistant ARs: from 6.1±3.1 to 12.9±7.1 nmol/ml; vascular rejections: from 5.8±3.0 to 16.9±9.1 nmol/ml). In patients with creatinine values ≥300 µmol/l pre-AR, a further increase of the KYN level (from 10.1 to 13.2 nmol/ml) was only observed in severe, steroid-resistant ARs. With respect to infections evaluated, the KYN levels before diagnosis/start of treatment were 5.7±3.4 nmol/ml in asymptomatic CMV infections, 7.5±4.4 nmol/ml in CMV diseases, 8.3±3.3 nmol/ml in pneumonia, and 10.4±6.5 nmol/ml in bacterial sepsis. CONCLUSIONS: Serum KYN seems to be a reliable diagnostic tool for the assessment of post-transplant inflammatory complications, already in an early stage, and for monitoring the efficacy of therapeutic interventions. Prospective studies are recommended.

Causes and prognostic value of pre-transplant elevated kynurenine level in kidney allograft recipients.

BACKGROUND: The activation of the tryptophane catabolizing enzyme Indoleamine 2,3-dioxygenase leads to the formation of kynurenine and other metabolites that counter-regulate immune activation resulting in restoration of immune homeostasis. But in chronic immune activation, as in hemodialysed patients, the immunosuppressive feedback mechanisms continue as indicated by elevated kynurenine concentrations. However, its relevance is still a matter of debate. MATERIAL/METHODS: This retrospective analysis presents the pre-transplant kynurenine levels (quantified photometrically) of 307 kidney graft recipients in connection with some pre- and post-transplant variables and the type of immunosuppression (cyclosporine-based triple drug therapy without/with ATG-Fresenius-induction). Statistical analyses performed were analysis of variance, Scheffé's test for pairwise comparisons, Cox regression, Spearman's rank correlation, and extended segmentation analysis. RESULTS: The pre-transplant kynurenine level was significantly elevated as compared to healthy adults (14.1±5.9 vs. 2.7±0.6 nmol/ml, p<0.0001), significantly higher in PRA positive than in PRA negative patients (16.1 vs. 12.9 nmol/ml, p<0.001) and, supporting this observation, also higher (p<0.0001) in a cohort with predominant (89.7%) pre-sensitized patients (16.4±6.4 nmol/ml) having the longest time on the waiting list (median 39 months) as compared to cohorts with fewer (16.8-22%) pre-sensitized patients (12.7±4.4 resp. 13.4±5.8 nmol/ml) having shorter times on the waiting list (16-24 months). Patients with immediately functioning grafts showed a lower pre-transplant kynurenine level than patients with non-immediately functioning grafts (13.5±6.0 vs. 14.9±5.7 nmol/ml, p=0.053). No associations were found with basic diseases, rejections, or graft survival. CONCLUSIONS: The pre-transplant elevated serum kynurenine levels were highly associated with the patient's pre-sensitization status and their longer time on hemodialysis treatments, but did not allow prognostic assessments.

High graft protection and low incidences of infections, malignancies and other adverse effects with intra-operative high dose ATG-induction: a single centre cohort study of 760 cases.

BACKGROUND: In 1990 we introduced the intra-operative single high-dose induction (HDI) with ATG-Fresenius as a novel renal sparing concept. The aim of this analysis was to compare both the long-term patient and graft survival and the incidences of adverse effects in recipients treated with standard triple-drug therapy (TDT) alone or with an additional HDI with ATG-F. MATERIAL AND METHODS: A total of 760 renal transplant recipients receiving either TDT, consisting of steroids, azathioprine and cyclosporine (n=238) or TDT + 9mg/kg ATG-F intra-operatively (n=522) were included in this retrospective analysis. RESULTS: Compared to the TDT cohort the graft and patient survival over the entire ten year period was significantly prolonged in the TDT+HDI cohort. In contrast, main adverse effects (TDT+HDI vs. TDT) such as malignancies (4.4 vs. 2.1%), PTLD (0.4 vs. 0.4%), CMV diseases (18.6 vs. 15.5%), Herpes zoster infections (2.9 vs. 1.3%), bacterial pneumonias (3.1 vs. 1.3%) and post-operative thrombocytopenia <50×10³/µl (0.5 vs. 1.3%) did not significantly differ between the two immunosuppressive regimens. Only CMV-IgM seroconversions occurred significantly more in the HDI cohort (39.3 vs. 23.5%). The absolute numbers of CD3, CD4 and CD8 cell counts were significantly reduced in TDT+ATG-F HDI cohort only over a time period of about five days. CONCLUSIONS: This world-wide largest single-centre cohort analysis clearly shows the superiority of the HDI with ATG-F compared to TDT alone in improving long-term graft survival without increasing the risk for infections, malignancies or other adverse effects.

Factors impacting short and long-term kidney graft survival: modification by single intra-operative -high-dose induction with ATG-Fresenius.

BACKGROUND: A majority of recipients benefited from the intra-operative single high-dose induction (HDI) with ATG-Fresenius (ATG-F) still leaving a group of recipients who did not profit from this kind of induction. Therefore the aim of this retrospective analysis was 1st to identify the risk factors impacting short and long-term graft survival, and 2nd to assess the efficacy of this type of induction in kidney graft recipients with or without these risk factors. MATERIAL/METHODS: A total of 606 recipients receiving two different immunosuppressive treatment regimens (1st: Triple drug therapy [TDT, n=196] consisting mainly of steroids, azathioprine and cyclosporine; 2nd: TDT + 9 mg/kg ATG-F intra-operatively [HDI, n=410]) were included in this analysis and grouped according to their kidney graft survival time (short GST: ≤1 yr, n=100 and long GST: >5 yrs, n=506). RESULTS: The main risk factors associated with a shortened graft survival were pre-transplant sensitization, re-transplantation, rejections (in particular vascular or mixed ones) and the necessity of a long-term anti-rejection therapy. Adding ATG-F single high dose induction to TDT was more efficient in prolonging kidney graft survival than TDT alone not only in recipients without any risk factors (p<0.005) but also in recipients with at least one risk factor (p<0.021). Only in 4.6% of recipients having two or more risk factors this effect could not be demonstrated. CONCLUSIONS: The intra-operative single high-dose induction with ATG-F significantly improves the kidney graft survival in recipients with or without risk factors and can therefore be recommended.

Improved long-term survival after intra-operative single high-dose ATG-Fresenius induction in renal transplantation: a single centre experience.

BACKGROUND: In organ grafts donor-specific sensitization is initiated immediately after revascularization. Therefore, in 1990 we introduced the intra-operative single high-dose ATG-Fresenius (ATG-F) induction in addition to standard triple drug therapy (TDT) consisting of steroids, azathioprine and cyclosporin. A total of 778 first renal transplantations from deceased donors, performed between 1987 and 1998, were included in this evaluation. MATERIAL/METHODS: This retrospective analysis of clinic records and electronic databases presents data of all recipients of first kidney grafts who received two different ATG-F inductions (1(st) group: 9 mg/kg body weight as single high-dose intra-operatively, n=484; 2(nd) group: 3 mg/kg body weight on 7 or 8 consecutive days as multiple-dose starting also intra-operatively, n=78) and standard TDT alone (3(rd) group: TDT alone, n=216). RESULTS: The 10-year patient survival rates were 72.6+/-2.6% (TDT + ATG-F single high-dose), 79.5+/-5.1% (TDT + ATG-F multiple-dose) and 67.2+/-3.7%% (TDT alone; Kaplan-Meier estimates with standard errors; ATG-F vs TDT alone, p=0.001). The 10-year graft survival rates with censoring of patients that died with a functioning graft were 73.8+/-2.4%, 57.7+/-5.8% and 58.4+/-3.6% (Kaplan-Meier estimates with standard errors; 1(st) vs 2(nd )and 3(rd) group, respectively, p<0.001) and the 10-year graft survival rates with patient death counted as graft failure were 58.3+/-2.7%, 55.7+/-5.8% and 48.2+/-3.5% (Kaplan-Meier estimates with standard errors; ATG-F single high-dose vs TDT, p=0.023). In pre-sensitized recipients there were also significant differences in favour of ATG-F, more notably in the single high-dose ATG-F induction. A total of 69% of the patients in the two cohorts receiving ATG-F did not experience any transplant rejections compared to 56% in patients undergoing TDT alone (p=0.018). The incidence of infectious complications was comparable across all groups. CONCLUSIONS: According to evidence obtained from the routine documentation of 778 renal transplantations, ATG-F induction therapy administered as a part of immunosuppressive therapy significantly improves patient survival and reduces the risk of graft failure and transplant rejections.

The dynamics of antidonor antibody formation early after clinical kidney transplantation measured by flow cytometry and microcytotoxicity test.

To study the dynamics of antidonor sensitization 92 patients were monitored for antibodies against donor T and B spleen lymphocytes before transplantation, within the first month after transplantation and 3 months after transplantation. Patients were monitored for donorreactive antibodies (DRA) of immunoglobulin G (IgG), IgA, and IgM isotype using flow cytometry (FC) and the standard microcytotoxicity test (CYT). Graft function was followed for at least 2 yrs, 51% of patients for 3 yrs after transplantation. Within the first month after transplantation the percentage of patients with antidonor sensitization detected by FC rose dramatically, so that the overall sensitization rate increased from 28 (30.4%) of 92 patients prior to transplantation to 63 (68.5%) of 92 patients after transplantation. Whereas preoperatively only one isotype (IgM for T lymphocytes, IgG for B lymphocytes) and only one target cell type (either T or B lymphocytes) dominated, the postoperative patterns of positive FC results were more variable regarding target and isotype, whereby FC-DRA of the IgA class substantially contributed. Appearance of donor-directed antibodies early after kidney transplantation is a frequent event. In our cases, sensitization with FC-DRA per se seemed not to be detrimental to the graft outcome (p > 0.05) but CYT-DRA did resulting in a significant poor graft outcome 3 months after transplantation (p < 0.001).

Eleven years intraoperative ATG bolus. A list of successes.

Induction therapy for organ transplantation using monoclonal antibodies has been in recent years reevaluated. Results from various centers indicate the value of such therapy, especially in sensitized patients undergoing kidney transplantation as well as in simultaneous kidney--pancreas transplant patients. Author presents the experience of eleven years of intraoperative ATG bolus administration in the Berlin--Friedrichshain Kidney Transplantation Center.