Jorge Malheiro

Analysis of preformed donor-specific anti-HLA antibodies characteristics for prediction of antibody-mediated rejection in kidney transplantation

BACKGROUND The relevance of preformed donor specific antibodies (DSA) detected by Luminex assays, with a negative complement-dependent cytotoxicity (CDC) crossmatch, remains unsettled in kidney transplantation (KT). We aimed to analyze the impact of preformed DSA characteristics on kidney graft outcomes. METHODS In 462 patients that received a kidney graft in our unit, between 2007 and 2012, pre-transplant sera were analyzed by Luminex screening assay to determine the presence of anti-human leukocyte antigen (HLA) antibodies and single-antigen bead assay [positive if mean fluorescence intensity (MFI) ≥ 1000] to assign anti-HLA specificities. RESULTS Anti-HLA antibodies were present in 95 patients (20.6%), but only 40 (8.7%) had DSA. Antibody-mediated rejection (AMR) at 1-year was higher in patients with DSA (35.0%) than in those without them (0.9%) (P < 0.001). Only DSA with a MFI of >3000 were significantly associated with AMR occurrence. Receiver operator curves revealed that a MFI of >4900 in the highest DSA bead had a high sensitivity (85.7%) and that the sum of all DSA beads MFI > 11,000 had a high specificity (92.3%) for AMR prediction. Anti-thymocyte globulin versus basiliximab induction was more frequent in DSA+ AMR- (65.4%) versus DSA+ AMR+ (34.6%) patients (P = 0.072). Five-year censored graft survival was lower in DSA+ than in DSA- patients (respectively, 84.8% versus 94.9%, P = 0.006), although survival was only reduced in DSA+ AMR+ (68.8%) versus DSA+ AMR- (96.0%) patients (P = 0.038). CONCLUSIONS Preformed DSA is associated with kidney graft loss, in relation with AMR occurrence. DSA strength may be used to improve immunological risk stratification of sensitized patients and their clinical management.

The effect of delayed graft function on graft and patient survival in kidney transplantation: an approach using competing events analysis

In kidney transplantation, the impact of delayed graft function (DGF) on long‐term graft and patient survival is controversial. We examined the impact of DGF on graft and recipient survival by accounting for the possibility that death with graft function may act as a competing risk for allograft failure.

Predictors of steal syndrome in hemodialysis patients

Steal syndrome is a feared complication of dialysis vascular access in a population becoming older and frailer. The aim of this study was to determine the predictor factors of steal syndrome. All proximal arteriovenous fistulas (AVFs), patent at day 30, inserted between January 2008 and December 2009 were studied. Data on age, gender, diabetes mellitus (DM) status, presence of coronary or peripheral artery disease, date of initiation of renal replacement therapy, date of access construction, localization, type of anastomosis, previous interventions, and outcome for AVF and patients were analyzed. There were 324 AVFs placed into 309 individual patients. The mean age was 66.7 ± 15.3 years, and the majority (53.7%) of the patients was male. Mean follow‐up of all 324 fistulas was 18.6 ± 8.5 months. During follow‐up, steal syndrome occurred in 26 (8%) of the AVFs. Univariate analysis revealed correlations between steal syndrome and DM (P = 0.002), brachiomedian fistulas (P = 0.016), and side‐to‐side (STS) anastomosis (P = 0.003). However, in multivariate analysis, the presence of DM, STS anastomosis, and female gender were found to be the independent risk factors. The strongest predictive factor was DM (odds ratio: 6.7; 95% confidence interval: 2.5–17.9). Being diabetic is the factor most predictive of having steal syndrome. In diabetic women, with a proximal access, it seems preferable to construct fistulas with end‐to‐side anastomosis to minimize the risk.

Effect of Different Sensitization Events on HLA Alloimmunization in Kidney Transplantation Candidates

BACKGROUND HLA alloimmunization is caused by sensitization events (SEs), such as transfusion, pregnancy, or previous organ transplantation, and the effects of particular SEs have not been thoroughly studied. Our aim was to evaluate how each SE affected HLA alloimmunization by considering Luminex assays. METHODS Sera from 722 kidney transplantation candidates were screened per protocol by means of Luminex assays to determine the presence of anti-HLA class I/II antibodies; positive sera underwent single-antigen assay to determine the presence of specific antibodies against HLA A, B, C, DR, DQ, DP loci (positivity if median fluorescence intensity values were >1,000). The effect of each SE was analyzed considering only patients exposed to 1 kind of sensitization. RESULTS In the 453 candidates with ≥1 SE, anti-HLA class I positivity rates were significantly higher in patients with previous transfusion (18.9%; P = .014), pregnancy (38.3%; P < .001) or transplant (75%; P < .001) compared with those with no SE (similar results for class II). The strength (median fluorescence intensity) of specific antibodies was significantly higher in patients with previous transplantation than in those with previous transfusion for HLA-A (8,017 vs 2,302; P = .02), HLA-B (7,765 vs 2,901; P = .018), and HLA-DR (9,835 vs 2,060; P = .003). Other anti-HLA antibody strengths were similar between patients with previous pregnancy or transplantation. CONCLUSIONS Presence of any SE analyzed was associated with a higher prevalence of anti-HLA antibodies for class I ± II compared with nonsensitized patients. Transplantation had the strongest immunization effect on both classes, followed by pregnancy and then transfusion.

Impact of liver transplantation on the natural history of oculopathy in Portuguese patients with transthyretin (V30M) amyloidosis

Abstract Purpose: Evaluation of the impact of liver transplantation in the natural history of ocular disorders in familial amyloidotic polyneuropathy (FAP) amyloidosis TTR V30M related (ATTR V30M) patients. Design: A clinical, retrospective and cross-sectional study of 64 Portuguese FAP ATTR V30M patients was carried out between January 2005 and December 2011. Methods: Thirty-two liver transplanted patients (both eyes) aged 39.6–53.8 years old, 32/32 male/female, were paired with an equal number of non-transplanted patients, matching for age, gender, age at onset, disease duration and gender of transmitting parent. Intervention or observation procedure: Routine ophthalmological observation. Main outcome measures: Slit-lamp observation for abnormal conjunctival vessels (ACV), tears break-up time, iris, lens; fundus observation for vitreous, retina and optic disc; Schirmer test. Results: Liver transplantation had no influence on tears break-up time, deposition of amyloid on the iris and retinal amyloid angiopathy. Slight, non-statistically significant protective effects of liver transplantation were noted in the first years for some ocular manifestations (ACV and scalloped iris), except for the abnormal Schirmer test, which was significantly more prevalent in non-transplanted patients’ eyes (81% versus 56%, p = 0.002). On the other hand, deposition of amyloid on the lens, vitreous amyloidosis and glaucoma were apparently more common in transplanted patients. Those differences tended to disappear with time. Conclusions: Ocular manifestations of FAP were not influenced by liver transplantation in a meaningful way. Both transplanted and non-transplanted FAP patients need similar regular follow-up due to long-term risk of serious ocular disease.

Ophthalmological manifestations in hereditary transthyretin (ATTR V30M) carriers: a review of 513 cases

Abstract Purpose: Assessment of ocular involvement in transthyretin-related familial amyloidosis with polyneuropathy (FAP) in a large cohort of Portuguese patients. Methods: We reviewed the medical records of 513 Portuguese FAP mutation carriers, at the Ophthalmology Service, Centro Hospitalar do Porto, between 1 January 2008 and 31 January 2013. Abnormal conjunctiva vessels (ACV), Schirmer test, tear break-up time (TBUT), amyloid deposition on the iris (DAI), scalloped iris, amyloid deposition on the anterior capsule of the lens (DAL), vitreous amyloidosis, retinal amyloid angiopathy and glaucoma were evaluated and registered. Results: Of the 513 carriers, 477 (93%) had clinical systemic disease with a median duration of 9.3 (5.1–13.7) years and 247 were men. Of these, 343 (72%) had been liver transplanted, on median of 6.6 (3.3–10.8) years before inclusion in this study. No ocular abnormalities were identified in the asymptomatic carriers (7%). The abnormalities observed with decreasing frequency were abnormal TBUT (379 patients, 79.5%, 751 eyes), abnormal Schirmer test (320 patients, 67%, 635 eyes), DAI (183 patients, 38.4%, 350 eyes), DAL (157 patients, 32.9%, 308 eyes), scalloped iris (133 patients, 27.9%, 238 eyes), glaucoma (97 patients, 20%, 165 eyes), vitreous amyloidosis (83 patients, 17.4%, 139 eyes), ACV (68 patients, 14%, 136 eyes) and amyloidotic retinal angiopathy (21 patients, 4%, 32 eyes). Patients with abnormal Schirmer test (p < 0.001), scalloped iris (p = 0.006) and vitreous amyloidosis (p = 0.007) were significantly older than the others. According to their age of onset of systemic disease, the patients have been split into early-onset (<40 years old), intermediate-onset (40–50 years old), late onset (>50 years old) and asymptomatic carriers. We observed a statistically significant difference in the prevalence of ACV (p = 0.045) and of an abnormal Schirmer test (p = 0.004) between groups. Transplanted patients have a significantly higher prevalence of DAI (p = 0.001), DAL (p = 0.009) and vitreous amyloidosis (p = 0.025) than non-transplanted patients. Of the 165 eyes with glaucoma, 92.1% had scalloped iris (p < 0.001) and of 32 eyes with retinal amyloidotic angiopathy, 68.8% had vitreous amyloidosis (p < 0.001). All prevalences increased with time of disease. The earliest ocular manifestations were abnormal Schirmer test and abnormal TBUT (12% and 17% at 5 years of clinical disease) and the least prevalent was retinal amyloid angiopathy (8% at 15 years of clinical disease). Conclusion: Ocular disorders in FAP patients are common, and their prevalence increases with disease duration. Prevalence is influenced by several factors, such as the age at onset of FAP and liver transplantation.

Determining donor‐specific antibody C1q‐binding ability improves the prediction of antibody‐mediated rejection in human leucocyte antigen‐incompatible kidney transplantation

Detrimental impact of preformed donor‐specific antibodies (DSAs) against human leucocyte antigens on outcomes after kidney transplantation are well documented, however, the value of their capacity to bind complement for predicting antibody‐mediated rejection (AMR) and graft survival still needs to be confirmed. We aimed to study DSA characteristics (strength and C1q binding) that might distinguish harmful DSA from clinically irrelevant ones. We retrospectively studied 60 kidney‐transplanted patients with preformed DSA detected by single antigen bead (SAB) assays (IgG and C1q kits), from a cohort of 517 kidney graft recipients (124 with detectable anti‐HLA antibodies). Patients were divided into DSA strength (MFI < vs. ≥ 15 000) and C1q‐binding ability. AMR frequency was high (30%) and it increased with DSA strength (P = 0.002) and C1q+ DSA (P < 0.001). The performance of DSA C1q‐binding ability as a predictor of AMR was better than DSA strength (diagnostic odds ratio 16.3 vs. 6.4, respectively). Furthermore, a multivariable logistic regression showed that C1q+ DSA was a risk factor for AMR (OR = 16.80, P = 0.001), while high MFI DSAs were not. Graft survival was lower in high MFI C1q+ DSA in comparison with patients with C1q− high or low MFI DSA (at 6 years, 38%, 83% and 80%, respectively; P = 0.001). Both DSA strength and C1q‐binding ability assessment seem valuable for improving pretransplant risk assessment. Since DSA C1q‐binding ability was a better predictor of AMR and correlated with graft survival, C1q‐SAB may be a particularly useful tool.

Over Ten-Year Kidney Graft Survival Determinants

Kidney graft survival has been mainly evaluated using an up to 10-year threshold. Instead, in this study our aim was to evaluate predictive variables that impact long-term kidney graft survival (≥10 years). We enrolled 892 patients in our analysis: 638 patients with functioning graft at 10 years PT and 254 patients with graft failure at 10 years PT (considering patient death with a functioning graft <10 years PT as graft failure). Between groups comparisons were done using Mann-Whitney and chi-square test. To determine independent predictive variables for long-term graft survival a multivariate-adjusted logistic regression was performed. Significant predictors of long term graft survival were lower 12-month PT creatinine (OR = 0.26, P < 0.001), lower donor age (OR = 0.98, P = 0.004), shorter time on dialysis (OR = 0.93, P = 0.044), recipient positive CMV IgG (OR = 1.59, P = 0.040), absence of AR episodes (OR = 1.57, P = 0.047), 0 to 1 (versus 2) HLA-B mismatch (OR = 1.80, P = 0.004), and recipients male gender (OR = 1.84, P = 0.005). Our results show that an early KT, younger donor age, and an optimal first year graft function are of paramount importance for long-term graft survival. Measures that address these issues (careful donor selection, preemptive KT, and effective immunosuppressive protocols) are still warranted.

Leptin and Adiponectin During the First Week After Kidney Transplantation: Biomarkers of Graft Dysfunction?

CONTEXT AND OBJECTIVE Based on evidence that leptin and adiponectin are removed from circulation primarily by the kidney, we designed a study to examine the longitudinal changes of these adipokines during the first week after kidney transplantation (KTx) and to test the hypothesis that higher levels of leptin and/or adiponectin could be early biomarkers of delayed graft function (DGF=dialysis requirement during the first post-transplant week) and acute rejection. STUDY DESIGN Repeated-measures prospective study. MATERIAL AND METHODS Forty consecutive adult patients with end-stage renal disease who were undergoing KTx. Leptin and adiponectin were measured in blood samples that were collected before (day-0) and after KTx (days-1, 2, 4 and 7). Linear mixed-models, receiver operating characteristic and area under curve (AUC-ROC) were used. RESULTS At post-transplant day-1, leptinemia and adiponectinemia declined 43% and 47%, respectively. At all times studied after KTx, the median leptin levels were significantly higher in patients developing DGF (n=18), but not adiponectin levels. Shortly after KTx (day-1), leptin values were significantly higher in DGF recipients in contrast to patients with promptly functioning kidneys, approximately two times higher when controlling for gender and BMI. The leptin reduction rate between pre-tranplant and one-day after KTx moderately predicted DGF (AUC=0.73). On day-1, serum leptin predicted DGF (AUC-ROC=0.76) with a performance slightly better than serum creatinine (AUC-ROC=0.72), even after correcting for BMI (AUC-ROC=0.73). Separating this analysis by gender showed that the performance of leptin in predicting DGF for male gender (AUC-ROC=0.86) improved. CONCLUSIONS Kidney graft function is an independent determinant of leptin levels, but not of adiponectin. Leptin levels at day-1 slightly outperformed serum creatinine in predicting the occurrence of DGF, and more accurately in male gender. No significant association was detected with acute rejection.

Diagnosis and Treatment of Acute Humoral Kidney Allograft Rejection

Acute humoral rejection (AHR) is a severe form of rejection associated with poor graft survival. Prompt diagnosis and rapid institution of therapy are crucial to improve the prognosis. A therapeutic approach based on plasmapheresis, intravenous imunoglobulin, and rituximab seems to be effective in refractory cases. Herein we have described our experience with 11 patients with biopsy-proven AHR who were treated between January 2005 and June 2008. Seven of these patients had panel reactive antibodies titers more than 50%. The diagnosis was based on Banff 2001 criteria; treatment consisted of a combination of plasmapheresis and intravenous immunoglobulin. Four refractory cases were also treated with a single dose of rituximab. One graft was lost due to thrombosis. All other patients recovered graft function with an average creatinine level of 1.6 mg/dL at 8.6 +/- 2.7 months of follow-up.