Inosine 5'-Monophosphate Dehydrogenase Activity for the Longitudinal Monitoring of Mycophenolic Acid Treatment in Kidney Allograft Recipients.

BACKGROUND: Mycophenolic acid (MPA) is a standard immunosuppressant in organ transplantation. A simple monitoring biomarker for MPA treatment has not been established so far. Here, we describe inosine 5'-monophosphate dehydrogenase (IMPDH) monitoring in erythrocytes and its application to kidney allograft recipients. METHODS: IMPDH activity measurements were performed using a high-performance liquid chromatography assay. Based on 4203 IMPDH measurements from 1021 patients, we retrospectively explored the dynamics early after treatment start. In addition, we analyzed the influence of clinically relevant variables on IMPDH activity in a multivariate model using data from 711 stable patients. Associations between IMPDH activity and clinical events were evaluated in hospitalized patients. RESULTS: We found that IMPDH activity reflects MPA exposure after 8 weeks of constant dosing. In addition to dosage, body mass index, renal function, and coimmunosuppression affected IMPDH activity. Significantly lower IMPDH activities were found in patients with biopsy-proven acute rejection as compared to patients without rejection (median [interquartile range]: 696 [358-1484] versus 1265 [867-1618] pmol xanthosine-5'-monophosphate/h/mg hemoglobin, P < 0.001). The highest IMPDH activities were observed in hospitalized patients with clinically evident MPA toxicity as compared to patients with hospitalization not related to MPA treatment (1548 [1021-2270] versus 1072 [707-1439] pmol xanthosine-5'-monophosphate/h/mg hemoglobin; P < 0.001). Receiver operating characteristic curve analyses underlined the usefulness of IMPDH to predict rejection episodes (area, 0.662; confidence interval, 0.584-0.740; P < 0.001) and MPA-associated adverse events (area, 0.632; confidence interval, 0.581-0.683; P < 0.001), respectively. CONCLUSIONS: IMPDH measurement in erythrocytes is a novel and useful strategy for the longitudinal monitoring of MPA treatment.

The selective biomarker IL-8 identifies IFTA after kidney transplantation in blood cells.

Cellular and antibody-mediated rejection processes and also interstitial fibrosis/tubular atrophy (IFTA) lead to allograft dysfunction and loss. The search for accurate, specific and non-invasive diagnostic tools is still ongoing and essential for successful treatment of renal transplanted patients. Molecular markers in blood cells and serum may serve as diagnostic tools but studies with high patient numbers and differential groups are rare. We validated the potential value of several markers on mRNA level in blood cells and serum protein level in 166 samples from kidney transplanted patients under standard immunosuppressive therapy (steroids±mycophenolic acid±calcineurin inhibitor) with stable graft function, urinary tract infection (UTI), IFTA, antibody-mediated rejection (ABMR), and T-cell-mediated rejection (TCMR) applying RT-PCR and ELISA. The mRNA expression of RANTES, granulysin, granzyme-B, IP-10, Mic-A and Interferon-γ in blood cells did not distinguish specifically between the different pathologies. We furthermore discovered that the mRNA expression of the chemokine IL-8 is significantly lower in samples from IFTA patients than in samples from patients with stable graft function (p<0.001), ABMR (p<0.001), Borderline (BL) TCMR (p<0.001), tubulo-interstitial TCMR (p<0.001) and vascular TCMR (p<0.01), but not with UTI. Serum protein concentrations of granzyme-B, Interferon-γ and IL-8 did not differ between the patient groups, RANTES concentration was significantly different when comparing UTI and ABMR (p<0.01), whereas granulysin, Mic-A and IP-10 measurement differentiated ongoing rejection or IFTA processes from stable graft function but not from each other. The measurement of IL-8 mRNA in blood cells distinguishes clearly between IFTA and other complication after kidney transplantation and could easily be used as diagnostic tool in the clinic.

Free microRNA levels in plasma distinguish T-cell mediated rejection from stable graft function after kidney transplantation.

The potential diagnostic value of circulating free miRNAs in plasma compared to miRNA expression in blood cells for rejection processes after kidney transplantation is largely unknown, but offers the potential for better and timely diagnosis of acute rejection. Free microRNA expression of specific blood cell markers was measured in 160 plasma samples from kidney transplant patients under standard immunosuppressive therapy (steroids±mycophenolic acid±calcineurin inhibitor) with stable graft function, urinary tract infection, interstitial fibrosis and tubular atrophy, antibody-mediated rejection (ABMR), Borderline (Banff3), tubulo-interstitial (Banff4-I) and vascular rejection (Banff4-II/III) applying RT-PCR. The expression levels of specific microRNAs miR-15B, miR-103A and miR-106A discriminated patients with stable graft function significantly (p-values 0.001996, 0.0054 and 0.0019 resp.) from patients with T-cell mediated rejection (TCMR) and from patients with urinary tract infection (p-values 0.0001, <0.0001 and 0.0001, resp.). A combined measurement of several microRNAs after multivariate logistic regression improved the diagnostic value supported by subsequent cross-validation. In conclusion, the measurement of circulating microRNAs in plasma from patients with renal transplants distinguishes TCMR and urinary tract infection from stable graft function. In contrast to miRNA expression measurement in blood cells it does not allow a discrimination from ABMR or interstitial fibrosis and tubular atrophy.

Identification of T Cell-Mediated Vascular Rejection After Kidney Transplantation by the Combined Measurement of 5 Specific MicroRNAs in Blood.

BACKGROUND: MicroRNAs (miRNAs, miR) hold important roles in the posttranscriptional regulation of gene expression. Their function has been correlated with kidney disease, and they might represent a new class of biomarkers for frequent evaluation of renal graft status. We analyzed their potential in identifying severe T cell-mediated vascular rejection (TCMVR) (Banff 4-II/III) in kidney transplanted patients. METHODS: Microarray experiments and semiquantitative real-time reverse transcription polymerase chain reaction were performed with total RNA isolated from blood cells of kidney graft recipients. Initial microarray analysis revealed 23 differentially expressed miRNAs distinguishing patients with TCMVR from patients with stable grafts. From these, we validated and further determined the expression of 6 differentially expressed miRNAs and 2 control miRNAs in 161 samples from patients with T cell-mediated rejection (Banff 3-Borderline, Banff 4-I/II/III), Banff-2 antibody-mediated rejection, Banff-5 interstitial fibrosis/tubular atrophy, in samples from stable patients and in samples from patients with urinary tract infection using real-time reverse transcription polymerase chain reaction. RESULTS: Expression levels of all 6 candidate miRNAs were significantly downregulated in blood of TCMVR patients compared to the other groups and displayed high sensitivities and specificities for diagnosing TCMVR. The combination of 5 miRNAs, identified by an unbiased multivariate logistic regression followed by cross-validation, enhanced the sensitivity and specificity for the diagnosis of TCMVR after renal transplantation. CONCLUSIONS: The combined measurement of miRNA-15B, miRNA-16, miRNA-103A, miRNA-106A, and miRNA-107 may help to better identify TCMVR after renal transplantation in a precise and clinically applicable way.

Conversion to Belatacept based regimen does not change T-cell phenotype and function in renal transplantation.

Belatacept offers a new option for renal allograft recipients who are suffering from side effects of calcineurin inhibitors or mTOR inhibitors,which may result in renal and extrarenal benefits.We prospectively performed flow cytometric immunophenotyping with a T-cell panel. In total we were able to fully investigate the immunophenotypic change in 8 patients before and after conversion from calcineurin inhibitor (n = 5) or mTOR inhibitor (n=2) to Belatacept or additional administration (n=1). Cells were analysed pre conversion, 1 month, 3 months, 6 months and 12 months after first Belatacept administration. The percentage of central memory, naïve, effector memory and terminally differentiated effector memory CD4+ and CD4− T-cells was determined. CD28, CD25 and CD69 expression on CD4+ and CD4− T-cells was measured ex vivo and also after 3 days of mitogen stimulation. Intracellular cytokines IFNgamma and IL-2 were measured after polyclonal cellular stimulation. The expression of activation markers and intracellular cytokines as well as the percentage of T-cell subsets did not change significantly during the observation period compared to the time-point pre conversion. Therefore the conversion of calcineurin inhibitor or mTOR inhibitor to Belatacept seems to have no obvious impact on the immunophenotype of T-cells in patients after kidney transplantation.

Safety and efficacy of regional citrate anticoagulation in continuous venovenous hemodialysis in the presence of liver failure: the Liver Citrate Anticoagulation Threshold (L-CAT) observational study.

INTRODUCTION: Regional citrate anticoagulation (RCA) for continuous renal replacement therapy is widely used in intensive care units (ICUs). However, concern exists about the safety of citrate in patients with liver failure (LF). The aim of this study was to evaluate safety and efficacy of RCA in ICU patients with varying degrees of impaired liver function. METHODS: In a multicenter, prospective, observational study, 133 patients who were treated with RCA and continuous venovenous hemodialysis (RCA-CVVHD) were included. Endpoints for safety were severe acidosis or alkalosis (pH ≤7.2 or ≥7.55, respectively) and severe hypo- or hypercalcemia (ionized calcium ≤0.9 or ≥1.5 mmol/L, respectively) of any cause. The endpoint for efficacy was filter lifetime. For analysis, patients were stratified into three predefined liver function or LF groups according to their baseline serum bilirubin level (normal liver function ≤2 mg/dl, mild LF >2 to ≤7 mg/dl, severe LF >7 mg/dl). RESULTS: We included 48 patients with normal liver function, 43 with mild LF, and 42 with severe LF. LF was predominantly due to ischemia (39 %) or multiple organ dysfunction syndrome (27 %). The frequency of safety endpoints in the three patient strata did not differ: severe alkalosis (normal liver function 2 %, mild LF 0 %, severe LF 5 %; p = 0.41), severe acidosis (normal liver function 13 %, mild LF 16 %, severe LF 14 %; p = 0.95), severe hypocalcemia (normal liver function 8 %, mild LF 14 %, severe LF 12 %; p = 0.70), and severe hypercalcemia (0 % in all strata). Only three patients showed signs of impaired citrate metabolism. Overall filter patency was 49 % at 72 h. After censoring for stop of the treatment due to non-clotting causes, estimated 72-h filter survival was 96 %. CONCLUSIONS: RCA-CVVHD can be safely used in patients with LF. The technique yields excellent filter patency and thus can be recommended as first-line anticoagulation for the majority of ICU patients. TRIAL REGISTRATION: ISRCTN Registry identifier: ISRCTN92716512 . Date assigned: 4 December 2008.

Soluble guanylate cyclase stimulator BAY 41-8543 and female sex ameliorate uremic aortic remodeling in a rat model of mild uremia.

BACKGROUND: Cardiovascular disease is the leading comorbidity in renal patients and has been related to impaired nitric oxide signaling. Estrogens exert protective effects on the vascular system. This study investigates the effects of biological sex and nitric oxide-independent soluble guanylate cyclase (sGC) stimulator BAY 41-8543 on aortic remodeling in experimental mild uremia. METHOD: Age-matched male and female Wistar rats were assigned for 18 weeks into sham-operated, subtotally nephrectomized (SNX), SNX + BAY 41-8543 and SNX + hydralazine. Analysis involved functional, histological, and molecular kidney and thoracic aorta parameters. RESULTS: SNX significantly increased SBP, which was comparably reduced to control levels by BAY 41-8543 and hydralazine. In SNX males, uremic aortic remodeling was characterized by marked media thickening and increased media-to-lumen ratio (P < 0.01), vascular smooth muscle cell (VSMC) proliferation, macrophage infiltration, extracellular matrix turnover, decreased aortic elastin-to-collagen ratio (P < 0.01) and endothelial nitric oxide-synthase (eNOS) mRNA expression (P < 0.05). No significant alterations of aortic media-to-lumen ratio, VSMC proliferation, macrophage infiltration, matrix metalloproteinase-2, and eNOS mRNA expressions were seen in female uremic animals. BAY 41-8543 significantly ameliorated uremic aortic remodeling and stiffening involving reduced VSMC proliferation, collagen I-deposition, extracellular matrix turnover, and increased elastin content and eNOS mRNA expression. Hydralazine treatment did not substantially alter aortic remodeling. CONCLUSION: Experimental mild uremia leads to pronounced aortic hypertrophic remodeling and stiffening with sex-dependent alternations, and these are more severe in male rats. BAY 41-8543 ameliorates uremic aortic remodeling in a blood pressure-independent manner. The results suggest that sGC-stimulators may offer a novel treatment mode for pathological arterial wall remodeling in patients with impaired renal function.

Midterm echocardiographic follow-up of cardiac function after living kidney donation.

BACKGROUND: Living kidney donation (LKD) has become increasingly important as more patients reach end-stage renal disease. While safety of the donor is of utmost importance, recent data have suggested an increased risk for cardiovascular mortality after LKD. Therefore, we assessed the changes of cardiac structure and function after LKD by advanced echocardiographic methods. METHODS: 30 living kidney donors were evaluated by medical examination, laboratory testing, and echocardiography before and after LKD (median follow-up 19.5 months). Left ventricular (LV) and right ventricular (RV) function was assessed by echocardiographic standard indices. Longitudinal 2D strain of the LV and left atrium (LA) was determined by 2D speckle tracking. RESULTS: Serum creatinine increased significantly from 0.80 ± 0.12 mg/dL to 1.18 ± 0.21 mg/ dL (p < 0.001) after LKD. There was a trend to higher blood pressure after LKD, accompanied with significantly higher intake of antihypertensive drugs. Echocardiographic parameters of LV, LA, and RV function did not change significantly after LKD. N-terminal pro-brain natriuretic peptide (NT-proBNP) levels remained within normal ranges after LKD. CONCLUSION: The rise in serum creatinine and blood pressure indicates that patients have a potentially higher cardiac risk after LKD. However, our pilot study found no evidence for detrimental effects of LKD on cardiac structure and function within a relatively short-term follow-up.

Pretransplant virtual PRA and long-term outcomes of kidney transplant recipients.

Virtual panel-reactive antibodies (vPRA) have been implemented to gauge sensitization worldwide. It is unclear how it associates with long-term outcomes, and its correlation with peak (pPRA) or actual (aPRA) has not been studied. We retrospectively reviewed data from 18- to 65-year-old kidney-only transplant patients during 1.1.1996-31.7.2011 in our center. PRAs were calculated based on solid-phase techniques. Of the 726 qualified cases, regardless of the PRA type, sensitized patients (PRA > 5%) had more females and previous transplant. Highly sensitized (HS, PRA > 50%) had longer waiting time, lower transplant rate, less living donor, more delayed graft function, and acute rejection. The conformity between vPRA and pPRA in HS was 75%, 57% between pPRA and aPRA. Forty-three percent (61/142) patients whose pPRA was >5% had no detectable aPRA and maintained similar outcomes as sensitized patients. Multivariate analysis showed consistently lower death-censored graft survival in HS defined by vPRA [HR 2.086 (95% CI 1.078-4.037), P < 0.05] and pPRA [HR 2.139 (95% CI 1.024-4.487), P < 0.05]. Both vPRA and pPRA provided reliable way estimating sensitization and predicting long-term graft survival, while aPRA might underestimate true sensitization. vPRA might be the most objective parameter to gauge sensitization.

Evaluation of acid-base control, electrolyte balance, and filter patency of a Prismaflex-based regional citrate anticoagulation protocol for pre-dilution continuous veno-venous hemodiafiltration.

BACKGROUND: Regional citrate anticoagulation (RCA) is increasingly used in patients requiring continuous renal replacement therapy (CRRT). This study evaluated a new RCA protocol based on the Prismaflex® dialysis device and an isotonic citrate solution (prismocitrate) for pre-dilution continous veno-venous hemodiafiltration. METHODS: The Prismaflex®/Prismocitrate-based protocol involved an AN69ST® membrane (Prisma Flex ST100), a blood flow of 120 mL/min, 1.8 L/h Prismocitrate (10 mmol/L citrate/2 mmol/L citric acid) substitution fluid in pre-dilution mode, and 0.8 L/h dialysate flow (PrismOcal) at the start. In parallel, infusions of potassium, calcium, and magnesium were initiated. Blood pH, bicarbonate, base excess, and ionized calcium levels were measured in 6 hours intervals and magnesium levels every 24 hours. Scheduled hemofilter run time was 72 hours. RESULTS: A consecutive series of 25 continuous renal replacement treatments was analyzed in 15 patients. After at least 6h of RRT, 69.9% of bicarbonate concentrations and 84.6% base excess (BE) calculations were below normal range. During CRRT, mean bicarbonate decreased from 22.9 to 20.2 mmol/L and mean BE from -1.5 to -4.2 mmol/L. In addition, 66.3% of ionized systemic calcium concentrations were out of the normal range, while 54.1% of the magnesium readings were above normal range. Five filters reached the scheduled run time of 72 hours, 19 treatments stopped prematurely because of RRT related reasons (5 filter clottings, 2 severe metabolic disarrangements, 12 major Prismaflex® hardware or software handling problems). One patient was switched to intermittent hemodialysis. CONCLUSIONS: The evaluated Prismaflex®/ Prismocitrate-based citrate anticoagulation protocol provides insufficient control of blood acid-base and electrolyte balance.

Incidence and outcome of metabolic disarrangements consistent with citrate accumulation in critically ill patients undergoing continuous venovenous hemodialysis with regional citrate anticoagulation.

BACKGROUND: Systemic citrate accumulation is a complication of regional citrate anticoagulation (RCA) during continuous renal replacement therapy (CRRT). Our objective was to determine the incidence of clinical signs consistent with citrate accumulation in a large and representative cohort of intensive care unit patients undergoing RCA-CRRT. METHODS: Patients treated with RCA-CRRT during 2008-2010 were retrospectively analyzed. Decreased systemic ionized calcium (iCa), increased demand for calcium substitution, elevated total calcium to iCa ratio, and metabolic acidosis were evaluated as indicators for citrate accumulation. RESULTS: In the 3-year period, 1070 patients were treated with RCA-continuous venovenous hemodialysis. Metabolic signs of citrate accumulation occurred in 32 patients (2.99%, 64.5 ± 14.0 years, 65.6% male, Acute Physiology and Chronic Health Evaluation score 34.2 ± 9.7): systemic iCa decreased to 1.01 ± 0.10 mmol/L with a simultaneous increase of the calcium substitution rate to 129% ± 26%, and the mean total calcium to iCa ratio increased to 2.51 ± 0.54. All 32 patients had therapy-resistant shock with severe lactic acidosis (pH 7.20 ± 0.11, lactate 136 ± 61 mg/dL), indicating severe intracellular hypoxia. None of the patients survived. CONCLUSIONS: The incidence of disarrangements consistent with citrate accumulation in patients undergoing RCA-continuous venovenous hemodialysis was low, taking place exclusively in patients with severe lactic acidosis due to multiorgan failure. This suggests that the appearance of citrate accumulation is secondary to a severe failure of cellular respiration.

Volume matters: CT-based renal cortex volume measurement in the evaluation of living kidney donors.

Currently, no international standard for the pre-transplant evaluation of living donor renal function exists. Following a standardized questionnaire on current practice in all Eurotransplant (ET) centers, we compared a new CT-based technique to measure renal cortex volume with our standard of DTPA-clearance combined with MAG3-scintigraphy (DTPA × MAG3) and with creatinine-based methods in 167 consecutive living kidney donors. Most ET centers use creatinine-clearance (64%) to measure total renal function and radioistopic methods (82%) to assess split renal function. Before transplantation, CT-measured total cortex volume (r = 0.67; P < 0.001) and estimated GFR using the Cockcroft-Gault formula [eGFR(CG)] (r = 0.55; P < 0.001) showed the strongest correlation with DTPA-clearance. In contrast, the correlation between DTPA-clearance and creatinine clearance was weak (r = 0.21; P = 0.02). A strong correlation was observed between CT-measured split cortex volume and MAG3-measured split renal function (r = 0.93; P < 0.001). A strong correlation was also found between pre-transplant split renal function assessed by eGFR(CG) together with cortex volume measurement and post-transplant eGFR(CG) of both, the donor (r = 0.83; P < 0.001) and the recipient (r = 0.75; P < 0.001). In conclusion CT-based assessment of renal cortex volume bears the potential to substitute existing methods to assess pre-transplant living donor split renal function.

Tyrosine kinases inhibition by Imatinib slows progression in chronic anti-thy1 glomerulosclerosis of the rat.

BACKGROUND: Chronic progressive mesangioproliferative nephropathy represents a major cause of end-stage renal disease worldwide. Until now, effective approaches to stop or even slow its progression are limited. We tested the effects of an inhibitor of PDGF receptor, abl and c-kit tyrosine kinases, Imatinib, in a chronic progressive model of mesangioproliferative glomerulosclerosis. METHODS: Anti-thy1 glomerulosclerosis was induced by injection of anti-thy1 antibody into uninephrectomized Wistar rats. One week after disease induction, according to the degree of proteinuria, animals were stratified and assigned to chronic glomerulosclerosis (cGS) and cGS plus Imatinib (10 mg/kg body weight/day). In week 20, renoprotective actions of Imatinib were analyzed by a set of functional, histological and molecular biological parameters. RESULTS: Untreated cGS rats showed elevation of systolic blood pressure and marked progression in proteinuria, renal fibrosis, cell infiltration, cell proliferation and function lost. Administration of Imatinib went along significantly with lower systolic blood pressure (-10 mmHg) and proteinuria (-33%). Imatinib administration was paralled by significant reductions in tubulointerstitial accumulation of matrix proteins (-44%), collagen I deposition (-86%), expression of TGF-beta1 (-30%), production of fibronectin (-23%), myofibroblast differentiation (-87%), macrophage infiltration (-36%) and cell proliferation (-45%), respectively. In comparison with untreated cGS animals, Imatinib therapy lowered also blood creatinine (-41%) and blood urea concentrations (-36%) and improved creatinine clearance (+25%). Glomerular fibrotic changes were lowered moderately by Imatinib. CONCLUSIONS: Therapy with Imatinib limits the progressive course of chronic anti-thy1 glomerulosclerosis towards tubulointerstitial fibrosis and renal insufficiency. This was paralleled by direct and indirect sign of TGF-ß1 and PDGF inhibition. The findings suggest that the pharmacological principal of inhibition of tyrosine kinases with drugs such as Imatinib might serve as approach for limiting progression of human mesangioproliferative glomerulosclerosis.

Combined standard and novel immunosuppressive substances affect B-lymphocyte function.

A considerable fraction of renal transplanted patients is susceptible to humoral rejection. Today well-established therapy regimens are available to control antibody-mediated rejection in the short term. Nevertheless, donor-specific antibodies persist and graft function deteriorates over time. This might be due to insufficient maintenance immunosuppression - which always consists of two to three drugs with different mechanisms of action. Since T- and B-cell functions always depend on each other in the alloimmune response it is of interest to analyze the effects of combined standard and new immunosuppressive substances with T-cell inhibitory properties on B-cell function. The effectiveness of complementary administrations of sotrastaurin, mycophenolic acid and everolimus on the activation and function of human primary B-lymphocytes was tested. Everolimus and mycophenolic acid alone and in combination proved to be highly effective in suppressing B-cell activation, whereas the proteinkinase C inhibitor sotrastaurin had an unexpected and reverse impact on various B-cell functions when applied in combination with the mammalian target of rapamycin and the inosine monophosphate dehydrogenase inhibitor.

Effective elimination of dabigatran by haemodialysis. A phase I single-centre study in patients with end-stage renal disease.

Dabigatran, a specific, reversible direct thrombin inhibitor, is used to prevent ischaemic and haemorrhagic strokes in patients with atrial fibrillation. As with every anticoagulant, there is a need to rapidly reverse its effects in emergency situations. In an open-label, single-centre phase I study with two fixed multiple dosing periods, we investigated the pharmacokinetics, pharmacodynamics and safety of dabigatran before, during and after 4 hour haemodialysis sessions with either 200 or 400 ml/min targeted blood flow in seven end-stage renal disease patients without atrial fibrillation. Dabigatran was administered over three days in a regimen designed to achieve peak plasma concentrations comparable to those observed in atrial fibrillation patients receiving 150 mg b.i.d. and to attain adequate distribution of dabigatran in the central and peripheral compartments. Plasma concentration-time profiles were similar in both periods on Day 3 (Cmax: 176 and 159 ng/ml). Four hours of haemodialysis removed 48.8% and 59.3% of total dabigatran from the central compartment with 200 and 400 ml/minute targeted blood flow, respectively. The anticoagulant activity of dabigatran was linearly related to its plasma levels. There was a minor redistribution of dabigatran (<16%) after the end of the haemodialysis session. In conclusion, a 4 hour haemodialysis session can rapidly eliminate a substantial amount of dabigatran from the central compartment with a concomitant marked reduction in its anticoagulant activity. There was a clinically negligible redistribution of dabigatran after haemodialysis. These results demonstrate that haemodialysis can be a suitable approach to eliminate dabigatran in emergency situations.

Identification and therapeutic management of highly sensitized patients undergoing renal transplantation.

Sensitization is generally referred to as the development of alloantibodies, specifically anti-human leukocyte antigen (HLA) immunoglobulin G (IgG) antibodies, most commonly caused by pregnancy, blood transfusion or a previous transplant. Despite being a well known phenomenon, there has not been a general consensus on its definition, monitoring or management. Today, 25% of the patients waitlisted for kidney transplant in the US have a panel reactive antibody (PRA) of >10% while, in the Eurotransplant zone, 14% have a PRA of >5%. Sensitized patients have more difficulty in finding a well HLA-matched donor, and have a higher risk of experiencing longer waiting times, more rejection episodes and eventually inferior long-term graft or patient survival. We review the currently available strategies in identifying and managing highly sensitized patients undergoing renal transplantation. We discuss the progress and limitations in laboratory techniques to elaborate on challenges in defining sensitized patients. The main management options (i.e. the Acceptable Mismatch Program, donor exchange programmes and the desensitization approach) and their mechanisms, related policies, advantages and outcomes, as well as medications and methods being investigated, are updated. In addition, particular emphasis is given to sensitization prevention, a practice that is neglected with our increasing ability to suppress the immune system.

Effects of sotrastaurin, mycophenolic acid and everolimus on human B-lymphocyte function and activation.

Humoral rejection processes may lead to allograft injury and subsequent dysfunction. Today, only one B-cell-specific agent is in clinical use and the effects of standard and new immunosuppressant substances on B-cell activation and function are not fully clarified. The impact of sotrastaurin, mycophenolic acid and everolimus on human B-lymphocyte function was assessed by analysing proliferation, apoptosis, CD80/CD86 expression and immunoglobulin and IL-10 production in primary stimulated B cells. In addition, B-cell co-cultures with pre-activated T cells were performed to evaluate the effect of the different immunosuppressive agents on T-cell-dependent immunoglobulin production. Sotrastaurin did not inhibit B-cell proliferation, CD80/CD86 expression, and IgG production and had only minor effects on IgM levels at the highest concentration administered. In contrast, mycophenolic acid and everolimus had strong effects on all B-cell functions in a dose-dependent manner. All immunosuppressive agents caused decreased immunoglobulin levels in T-cell-dependent B-cell cultures. The data provided here suggest that mycophenolic acid and everolimus, but not sotrastaurin, are potent inhibitors of human B-lymphocyte function and activation.

Plasmablastic posttransplant lymphoma: cytogenetic aberrations and lack of Epstein-Barr virus association linked with poor outcome in the prospective German Posttransplant Lymphoproliferative Disorder Registry.

BACKGROUND: Plasmablastic posttransplant lymphoma is a rare subtype of monomorphic B-cell posttransplant lymphoproliferative disorder (PTLD). There is little published clinical data to guide treatment. METHODS: The German prospective PTLD registry D2006-2012 records baseline features, treatment, and outcome of rare PTLD subtypes in adults after solid organ transplantation. Treatment is at the discretion of the local physician. Clinical data on the patients in the registry is collected before, during, and at least 4 weeks, 6 months, 12 and 24 months after treatment. RESULTS: Eight cases of plasmablastic posttransplant lymphoma were reported to the registry until 2011. The majority occurred as late PTLD in male heart transplant recipients. Extranodal manifestations were common in stage I and in stage IV disease. Histological Epstein-Barr virus (EBV) association was confirmed in five of eight cases. MYC/IGH rearrangement was present in two of six patients examined. Although five of eight patients died from early disease progression, we observed that long-term survival can be achieved in localized (2/3) and in disseminated disease (1/5) by immunosuppression reduction (IR) followed by immediate systemic chemotherapy. However, all patients with cytogenetic aberrations and patients with non-EBV-associated PTLD were refractory to IR and to chemotherapy. Chemotherapy parallel to IR was associated with a high rate of infectious complications. CONCLUSIONS: In this series, IR and local therapy were not sufficient to treat plasmablastic posttransplant lymphoma even in localized disease whereas IR and systemic chemotherapy (CHOP-21) could achieve lasting complete remissions. Cytogenetic aberrations and lack of EBV association were linked with poor outcome.

Extended daily on-line high-volume haemodiafiltration in septic multiple organ failure: a well-tolerated and feasible procedure.

BACKGROUND: The outcome of patients with septic multiple organ failure (MOF) remains poor. There are experimental and clinical data indicating a beneficial effect of high-volume haemofiltration. Delivering high-volume therapy is only cost effective using on-line devices because of high costs for additional solution bags in conventional continuous renal replacement therapy (CRRT). We investigated feasibility and effectiveness of extended daily on-line high-volume haemodiafiltration (HDF) with technically maximum convective volume in patients with septic MOF in a pilot study. METHODS: We included 21 consecutive critically ill patients with septic MOF having a mortality risk >50% (SAPS II >50, APACHE II >25). Renal replacement therapy (RRT) was applied with extended daily HDF for 6-23 h using the AK 200 Ultra S dialysis machine in the ultracontrol pre-dilution mode. Dialysate and substitution fluid were prepared on-line. Patients underwent 289 treatments. RESULTS: The mean convective volume was 17.8 ± 3.7 L/h and 208 ± 66 mL/kg/h, respectively, median treatment time was 10:15 h/day. Seventeen of 21 patients survived 28 days (81%). The 90-day survival rate was 52% (11/21) versus 19% compared to the survival rate predicted by APACHE II (33.6 mean) and SAPS II (68.6 mean) scores. Haemodynamics improved significantly during the treatment procedures. Material costs per treatment amounted to 35 €. CONCLUSIONS: Extended daily on-line HDF using maximum convective volume seems to improve the outcome of septic MOF, especially in the early phase. The investigated mode of treatment proved to be feasible, well tolerated and highly cost effective compared to conventional CRRT. At present, this procedure would be applicable at every ICU facility with nephrological support.

Comparison between bortezomib and rituximab in the treatment of antibody-mediated renal allograft rejection.

BACKGROUND: Antibody-mediated rejection (ABMR) following kidney transplantation is associated with poor allograft survival. Conventional treatment based on plasmapheresis (PPH) and the administration of intravenous immunoglobulins (IVIG) is not satisfactory. Two compounds, more specifically targeting B cells and plasma cells, may help to improve the prognosis: rituximab, a B-cell-depleting monoclonal antibody, and bortezomib, a proteasome inhibitor causing apoptosis of plasma cells. METHODS: Starting in February 2009, we treated 10 consecutive patients with ABMR according to current Banff criteria with one cycle of bortezomib [1.3 mg/m(2) intravenously (i.v.), Day 1, 4, 8, 11]. This group was compared to a historical control group of patients (n = 9) treated with a fixed single dose of rituximab (500 mg i.v.). All patients received PPH (6×) and IVIG (30 g). Patients with acute ABMR additionally received methylprednisolone (3 × 500 mg i.v.). RESULTS: Patient survival in both groups was 100%. At 18 months after treatment, graft survival was 6/10 in the bortezomib group as compared to 1/9 functioning grafts in the rituximab group (P = 0.071). Renal function was superior in patients treated with bortezomib as compared to rituximab-treated patients (serum creatinine at 9 months: 2.5 ± 0.6 versus 5.1 ± 2.1 mg/dL, P = 0.008). Proteinuria was not different between both groups (9 months: 1.3 ± 1.0 versus 1.6 ± 1.6 g/day, P = n.s.). CONCLUSIONS: Treatment of ABMR with bortezomib in addition to standard therapy was partially effective, whereas treatment with a fixed dose of rituximab in addition to standard therapy with PPH and IVIG did not result in sufficient long-term graft survival. In the future, new strategies including the combination of both substances and the application of higher doses must be discussed.