Autoantibodies Specific for the Phospholipase A2 Receptor in Recurrent and De Novo Membranous Nephropathy

Recent findings in idiopathic membranous nephropathy (MN) suggest that in most patients, the disease is because of anti‐phospholipase A₂ receptor (PLA₂R1) autoantibodies. Our aim was to analyze the prevalence and significance of anti‐PLA₂R1 antibodies in recurrent and de novo MN after transplantation. We assessed circulating PLA₂R1 autoantibodies by a direct immunofluorescence assay based on human embryonic kidney cells transfected with a PLA₂R1 cDNA, and the presence of PLA₂R1 antigen in immune deposits. We showed that PLA₂R1 was involved in 5 of 10 patients with recurrent MN, but in none of the 9 patients with de novo MN. We also showed a marked heterogeneity in the kinetics and titers of anti‐PLA₂R1, which may relate to different pathogenic potential. We provide evidence that some patients with PLA₂R1‐related idiopathic MN and anti‐PLA₂R1 antibodies at the time of transplantation will not develop recurrence. Because PLA₂R1 autoantibody was not always associated with recurrence, its predictive value should be carefully analyzed in prospective studies.     

Temporal IgG Subtype Changes in Recurrent Idiopathic Membranous Nephropathy

Determination of the IgG subtypes within the immune deposits in membranous nephropathy (MN) may be helpful in the differential diagnosis. IgG4 is the predominant subtype in idiopathic MN and recurrent MN, while IgG1, IgG2, and IgG3 subtypes are more common in secondary MN and de novo disease in the allograft. The temporal change of IgG subclasses in individual patients and its correlation with clinical variables have not been studied. We reviewed all posttransplantation protocol and indication biopsies (49) in 18 patients with recurrent MN who underwent transplantation at our center between 1998 and 2013 and performed IgG subtyping (IgG1–4). We tested serum for M‐type phospholipase A₂ receptor (PLA₂R) autoantibodies or performed PLA₂R antigen staining on the kidney biopsy. IgG4 was the (co)dominant IgG subtype in 10 of 14 biopsies at the diagnosis of recurrence regardless of PLA₂R association. In 8 of 12 transplantations with serial biopsies, the (co)dominant subtype did not change over time. There was a trend toward IgG1 and IgG3 (co)dominance in biopsies >1 year from recurrence and more IgG1 (co)dominant subtyping in the setting of more‐advanced EM deposits. Treatment with rituximab did not affect the IgG subtype. In conclusion, the dominant IgG subtype did not change over time in recurrent MN.     

Phospholipase A2 Receptor Autoantibodies and Clinical Outcome in Patients with Primary Membranous Nephropathy

Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in adults, with an uncertain clinical outcome. The characterization of the phospholipase A₂ receptor (PLA₂R) as the major target antigen in primary MN and the detection of circulating autoantibodies in these patients is a major advance in understanding this disease. To test whether PLA₂R antibody levels reflect disease activity or clinical outcome, we performed a prospective multicenter study of 133 adult patients with primary MN and detectable serum PLA₂R antibodies who had not received immunosuppressive therapy. Patients were followed ≤24 months. PLA₂R antibody levels associated with clinical disease activity (proteinuria) in patients with immunosuppressive therapy (n=101) or supportive care (n=32). Within 3 months, immunosuppressive therapy led to a sustained 81% reduction in PLA₂R antibody levels paralleled by a 39% reduction in proteinuria. Patients who experienced remission of proteinuria after 12 months had significantly lower PLA₂R antibody levels at the time of study inclusion compared with patients with no remission. Patients with high PLA₂R antibody levels achieved remission of proteinuria significantly later than patients with low PLA₂R antibody levels. PLA₂R antibody levels fell over time in patients with spontaneous remission but remained elevated in patients who did not show a reduction in proteinuria. Multivariable Cox regression analysis confirmed PLA₂R antibody level as an independent risk factor for not achieving remission of proteinuria. We conclude that a decrease in PLA₂R antibody level is associated with a decrease of proteinuria in patients with primary MN.Since the landmark discovery that circulating autoantibodies against the phospholipase A₂ receptor (PLA₂R) are specific for patients with primary membranous nephropathy (MN) completely new paradigms for the diagnosis and clinical care of these patients are possible.¹ These are urgently needed because the clinical outcome of patients with primary MN varies and ranges from spontaneous clinical remissions to end stage renal failure.^2,3 Because of the absence of reliable predictors of clinical outcome, the best documented methods to predict outcome and hence make a decision to treat patients with an immunosuppressive agent or maintain them on supportive medications currently require prolonged follow-up measurements of proteinuria.^4,5 Furthermore, in patients who receive immunosuppressive therapy, the intensity and duration of the treatment currently depend on changes in proteinuria, which do not necessarily reflect the severity or activity of the immunologic disease. On the other hand, patients who clinically do not respond to immunosuppressive agents may have insufficient therapy and still have active immunologic disease. A marker that reflects immunologic disease activity in real time and indicates clinical outcome could substantially improve the care of these patients. The availability of recently developed and easily applicable assays to measure PLA₂R antibody levels in the serum^6–8 makes it possible to study patients prospectively and to analyze whether PLA₂R antibody levels are related to disease activity. To address this question, we conducted a multicenter open prospective study in patients with biopsy-proven MN.     

Identification of the Immunodominant Epitope Region in Phospholipase A2 Receptor-Mediating Autoantibody Binding in Idiopathic Membranous Nephropathy

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. Recent clinical studies established that >70% of patients with idiopathic (also called primary) MN (IMN) possess circulating autoantibodies targeting the M-type phospholipase A₂ receptor-1 (PLA₂R) on the surface of glomerular visceral epithelial cells (podocytes). In situ, these autoantibodies trigger the formation of immune complexes, which are hypothesized to cause enhanced glomerular permeability to plasma proteins. Indeed, the level of autoantibody in circulation correlates with the severity of proteinuria in patients. The autoantibody only recognizes the nonreduced form of PLA₂R, suggesting that disulfide bonds determine the antigenic epitope conformation. Here, we identified the immunodominant epitope region in PLA₂R by probing isolated truncated PLA₂R extracellular domains with sera from patients with IMN that contain anti-PLA₂R autoantibodies. Patient sera specifically recognized a protein complex consisting of the cysteine-rich (CysR), fibronectin-like type II (FnII), and C-type lectin-like domain 1 (CTLD1) domains of PLA₂R only under nonreducing conditions. Moreover, absence of either the CysR or CTLD1 domain prevented autoantibody recognition of the remaining domains. Additional analysis suggested that this three-domain complex contains at least one disulfide bond required for conformational configuration and autoantibody binding. Notably, the three-domain complex completely blocked the reactivity of autoantibodies from patient sera with the full-length PLA₂R, and the reactivity of patient sera with the three-domain complex on immunoblots equaled the reactivity with full-length PLA₂R. These results indicate that the immunodominant epitope in PLA₂R is exclusively located in the CysR-FnII-CTLD1 region.     

Circulating antibodies to α-enolase and phospholipase A2 receptor and composition of glomerular deposits in Japanese patients with primary or secondary membranous nephropathy

Background

Phospholipase A₂ receptor (PLA₂R) is recognized as a target antigen in primary membranous nephropathy (MN); Anti-α-enolase antibody in primary and secondary MN has been proposed, however, little is known about the potential contribution of α-enolase to the pathogenesis of MN.

Methods

We evaluated circulating antibodies to α-enolase by a dot blotting system and PLA₂R by indirect immunofluorescence, and glomerular deposition of these proteins in 25 patients with primary MN, 20 patients with secondary MN, 44 patients with collagen disease or severe infection, 60 patients with nephritis (each ten patients of IgA nephropathy, focal segmental gloemrulosclerosis, minimal change nephrotic syndrome, membranoproliferative glomeurlonephritis, diabetic glomerulosclerosis, and tubulointerstitial nephritis) as disease control, and 20 healthy subjects.

Results

In primary MN, 18 of 25 sera (72 %) showed anti-α-enolase antibody (IgG1 and IgG4, 11 pts; IgG4 alone, six pts; IgG1 alone, one pt). In secondary MN, 15 of 20 sera (75 %) contained anti-α-enolase antibody (IgG1 and IgG3, 13 pts; IgG3 alone, two pts). No circulating anti-α-enolase antibody was found in 44 collagen diseases or septic patients, 60 nephritis without MN, and 20 healthy subjects. Twelve of 25 sera (48 %) from patients with primary MN were positive for anti-PLA₂R antibody, whereas all patients with secondary MN were negative. Eight of the 12 PLA₂R-positive patients (67 %) with primary MN also had anti α-enolase antibody. Although PLA₂R antigen was present in a subepithelial pattern in 10 of 19 (52 %) patients with primary MN, α-enolase was never detected in glomerular deposits in 19 and ten patients with primary and secondary MN, respectively.

Conclusions

Circulating anti-α-enolase antibodies are highly present in both primary and secondary MN (about 70 %, respectively), while anti-PLA₂R antibodies are specific for primary MN (48 %) with a prevalence apparently lower in the Japanese population than in Chinese and Caucasian populations. The absence of α-enolase from subepithelial immune deposits suggests that anti-α-enolase antibodies do not contribute directly to immune-deposit formation, although they may have other pathogenic effects.

     

Recurrent Idiopathic Membranous Nephropathy: Early Diagnosis by Protocol Biopsies and Treatment with Anti‐CD20 Monoclonal Antibodies

Membranous nephropathy (MN) recurs posttransplant in 42% of patients. We compared MN recurrence rates in a historical cohort transplanted between 1990 and 1999 and in a current cohort diagnosed by protocol biopsies, we analyzed the progression of the disease and we assessed the effects of anti‐CD20 antibodies (Rituximab) on recurrent MN. The incidence of recurrent MN was similar in the historical (53%) and the current cohorts (41%), although in the later the diagnosis was made earlier (median, 4[2–21] months vs. 83[6–149], p = 0.002) and the disease was clinically milder. Twelve out of 14 patients (86%) with recurrent MN in the current cohort had progressive increases in proteinuria. Eight recipients were treated with Rituximab after their proteinuria increased from median, 211 mg/day (64–4898) at diagnosis to 4489 (898–13 855) (p = 0.038). Twelve months post‐Rituximab, 75% of patients had either partial (PR) or complete remission (CR). After 24 months 6/7 (86%) had PR/CR and one patient relapsed. Posttreatment biopsies showed resorption of electron dense immune deposits in 6/7 cases and were negative for C3 (4/7) and IgG (3/7). Protocol biopsies allow early diagnosis of subclinical recurrent MN, which is often progressive. Treatment of recurrent MN with Rituximab is promising and should be evaluated in a prospective randomized controlled trial.     

Autoantibodies against phospholipase A2 receptor in Brazilian patients with glomerular diseases

Background

Recently, great progress has been made in understanding the pathogenesis of membranous nephropathy (MN) with the discovery of autoantibodies (Abs) to M-type phospholipase A2 receptor (PLA2R) in serum and in immunocomplexes deposited in glomerulus in most adult patients with primary MN.

Objective

To evaluate the diagnostic performance of anti-PLA2R in Brazilian patients with MN, as well as to verify the possible association of anti-PLA2R serum levels with disease activity.

Methods

117 patients with glomerular diseases confirmed by renal biopsy underwent routinely clinical and laboratory evaluation (serum creatinine and albumin, 24-h proteinuria, urinalysis, tests for etiological investigation) and determination of serum anti-PLA2R by ELISA.

Results

67.5% of the patients had MN, 9.4% focal segmental glomerulosclerosis, 7.7% lupus nephritis class V and 15.4%, other proteinuric glomerular diseases. The mean level of glomerular filtration rate (estimated by the CKD-EPI formula) was 79.43 mL/min (12.00–151.20 mL/min), 24 h proteinuria of 2.89 g (0–14.90 g), serum albumin of 3.79 g/dL (1.20–4.80 g/dL). Anti-PLA2R was detected in 27 patients, all with active MN, being 26 primary and 1 secondary MN. Sensitivity and specificity rates for the test were 60.5–94.7%, and positive (PPV) and negative (NPV) predictive values were 92.9 and 67.9%, respectively.

Conclusions

Anti-PLA2R showed high specificity and PPV for the diagnosis of primary MN in Brazilian patients. There was a strong correlation between disease activity and positive anti-PLA2R. This biomarker represents an important diagnostic tool for primary MN and may contribute to the monitoring of disease activity in such patients.

     

Pancreatic autoantibodies after pancreas–kidney transplantation – do they matter?

Type 1 diabetes recurrence has been documented in simultaneous pancreas–kidney transplants (SPKT), but this diagnosis may be underestimated. Antibody monitoring is the most simple, noninvasive, screening test for pancreas autoimmune activity. However, the impact of the positive autoimmune markers on pancreas graft function remains controversial. In our cohort of 105 SPKT, we studied the cases with positive pancreatic autoantibodies. They were immunosuppressed with antithymocyte globulin, tacrolimus, mycophenolate, and steroids. The persistence or reappearance of these autoantibodies after SPKT and factors associated with their evolution and with graft outcome were analyzed. Pancreatic autoantibodies were prospectively monitored. Serum samples were collected before transplantation and at least once per year thereafter. At the end of the follow‐up (maximum 138 months), 43.8% of patients were positive (from pre‐transplant or after recurrence) for at least one autoantibody – the positive group. Antiglutamic acid decarboxylase was the most prevalent (31.4%), followed by anti‐insulin (8.6%) and anti‐islet cell autoantibodies (3.8%). Bivariate analysis showed that the positive group had higher fasting glucose, higher glycated hemoglobin (HbA1c), lower C‐peptide levels, and a higher number of HLA‐matches. Analyzing the sample divided into four groups according to pre‐/post‐transplant autoantibodies profile, the negative/positive group tended to present the higher HbA1c values. Multivariate analysis confirmed the significant association between pancreas autoimmunity and HbA1c and C‐peptide levels. Positivity for these autoantibodies pre‐transplantation did not influence pancreas survival. The unfavorable glycemic profile observed in the autoantibody‐positive SPKT is a matter of concern, which deserves further attention.     

The acquisition time of infection: a determinant of the severity of hepatitis C virus-related liver disease in renal transplant patients

Abstract: Background: The aim of this study was to compare the clinical and histopathological course of HCV infection acquired before and during or after renal transplantation. Methods: According to HCV status, 197 RT patients were divided into three groups. At the time of RT, anti‐HCV antibody was positive in 47 patients (pre‐RT HCV group). In 27 patients, in whom anti‐HCV negative at the time of RT, anti‐HCV and/or HCV RNA was found to be positive following an ALT elevation episode after RT (post‐RT HCV group). Both anti‐HCV and HCV RNA were negative at all times in remaining 123 patients (control group). Results: Liver biopsy was performed in 31 of 47 patients in pre‐RT and 24 of 27 in post‐RT HCV group after RT. Duration of follow‐up was similar in all groups with a mean of 7.1 ± 4.0 yr. Ascites and encephalopathy were seen in only post‐RT HCV group (22%). Histological grade (6.5 ± 2.7 vs. 4.1 ± 1.4) and stage (2.0 ± 1.5 vs. 0.8 ± 0.8) was significantly severe in post‐RT HCV group (p < 0.01). Three patients died due to liver failure in post‐RT HCV group. Conclusions: HCV infection acquired during or after RT shows a severe and rapidly progressive clinicopathological course, which is significantly different from pre‐transplant anti‐HCV positive patients.     

Pre‐transplant angiotensin receptor II type 1 antibodies and risk of post‐transplant focal segmental glomerulosclerosis recurrence

Post‐kidney transplant recurrence of focal segmental glomerulosclerosis (FSGS) is a major problem. AT1R is expressed on podocyte; its expression is elevated in the proteinuric state. Using an ELISA, we tested pre‐transplant sera of 28 patients with history of idiopathic FSGS for anti‐AT1R levels and serum soluble urokinase‐type plasminogen activator receptor (suPAR) as a biomarker for risk of recurrence of FSGS. Sera from 11 patients with polycystic kidney disease (PKD) were used as controls. Twelve patients had biopsy proven post‐transplant FSGS recurrence at 1.5 months. No difference was found in the pre‐transplant suPAR levels of FSGS patients (5993 ± 2292 pg/mL) vs. PKD (7334 ± 4538 pg/mL) (p = 0.23). Serum suPAR levels in patients with FSGS recurrence (5786 ± 1899 pg/mL) vs. no FSGS recurrence (6149 ± 2598 pg/mL) (p = 0.69) were not different. Anti‐AT1R levels in patients with FSGS were 12.66 ± 11.85 U/mL vs. 8.69 ± 6.52 U/mL in PKD (p = 0.32); however, a difference was found in patients with and without FSGS recurrence 20.41 ± 14.36 U/mL 6.84 ± 4.181 U/mL, respectively (p < 0.01). Area under curve for suPAR and anti‐AT1R to predict post‐transplant FSGS recurrence was 0.51 and 0.84, respectively. Pre‐transplant anti‐AT1R levels appear to be a helpful biomarker in identifying patients at high risk of post‐transplant FSGS recurrence.     

Recurrent Membranous Nephropathy After Kidney Transplantation Associated With Phospholipase A2 Receptor and Successfully Treated With Rituximab: A Case Report

Primary membranous nephropathy (MN) is an organ-specific autoimmune disease mainly caused by autoantibodies acting against the podocyte antigen M-type phospholipase A2 receptor 1 (PLA2R). Herein we present the clinical and histologic findings, including PLA2R staining, of early recurrent MN after kidney transplantation that was successfully treated with rituximab.A 60-year-old Japanese man had end-stage renal failure due to steroid-resistant primary MN and underwent ABO-incompatible living donor kidney transplantation. At 1 month after transplantation, a protocol biopsy revealed positive granular staining of IgG, C4d, and PLA2R on glomerular capillaries (GCs) without any abnormalities on light microscopy (LM). Although the patient had low-level proteinuria, recurrent MN was suspected based on the positive PLA2R staining; he was treated with an angiotensin receptor blocker and a single dose of 200 mg rituximab. However, proteinuria gradually increased to 877 mg/d. At 21 months after transplantation, a graft biopsy revealed spikes along the outer aspects of GC on LM, with stronger staining for PLA2R than that at 1 month after transplantation. A single dose of 500 mg rituximab was added, which effectively reduced proteinuria, and clinical remission continued until 3 years after transplantation. The latest graft biopsy showed reduced staining of PLA2R. The disease activity and therapeutic effect were well-reflected in the intensity of PLA2R staining.An approach intending an early diagnosis by protocol biopsy using PLA2R immunostaining is made and early treatment with rituximab will help reduce the risk of kidney graft loss due to recurrent primary MN.     

Pre‐transplant phospholipase A2 receptor autoantibody concentration is associated with clinically significant recurrence of membranous nephropathy post‐kidney transplantation

Previous studies that have assessed the association of pre‐transplant antiphospholipase A2 receptor autoantibody (PLA2R‐Ab) concentration with a recurrence of membranous nephropathy (rMN) post‐kidney transplant have yielded variable results. We tested 16 consecutive transplant patients with a history of iMN for pre‐transplant PLA2R‐Ab. Enzyme‐linked immunosorbent assay titers (Euroimmun, NJ, USA) >14 RU/mL were considered positive. A receiver operating characteristic (ROC) analysis was performed after combining data from Quintana et al. (n = 21; Transplantation February 2015) to determine a PLA2R‐Ab concentration which could predict rMN. Six of 16 (37%) patients had biopsy‐proven rMN at a median of 3.2 yr post‐transplant. Of these, five of six (83%) had a positive PLA2R‐Ab pre‐transplant with a median of 82 RU/mL (range = 31–1500). The only patient who had rMN with negative PLA2R‐Ab was later diagnosed with B‐cell lymphoma. One hundred percent (n = 10) of patients with no evidence of rMN (median follow‐up = five yr) had negative pre‐transplant PLA2R‐Ab. In a combined ROC analysis (n = 37), a pre‐transplant PLA2R‐Ab > 29 RU/mL predicted rMN with a sensitivity of 85% and a specificity of 92%. Pre‐transplant PLA2R‐Ab could be a useful tool for the prediction of rMN. Patients with rMN in the absence of PLA2R‐Ab should be screened for occult malignancy and/or alternate antigens.     

Cholestatic syndromes in renal transplant recipients with HCV infection

Abstract We present two distinct types of cholestatic syndrome identified in eight renal transplant (RTx) patients with HCV infection. Four patients developed fibrosing cholestatic hepatitis (FCH) and four, vanishing bile duct syndrome (VBDS). All patients with FCH were anti‐HCV (‐) at the time of Tx and developed a cholestatic profile 1‐4 months post‐Tx, with high HCV‐RNA levels. Immunosuppressive therapy was drastically reduced. Two patients died of sepsis and liver failure 16 and 18 months post‐Tx, and the other two showed marked improvement and seroconverted to anti‐HCV. Regarding the patients with VBDS, three were anti‐HCV (‐) and one was anti‐HCV (+)/HBsAg (+) at the time of RTx. Two patients became anti‐HCV (+) 1 year, and one patient, 3 years post‐Tx. Two patients developed progressive VBDS and died of liver failure 2 and 3 years after onset, and two showed marked improvement after withdrawal of immunosuppression. In two of the patients, the progression of the disease coincided with elevation in serum HCV RNA levels. We concluded that a progressive cholestatic syndrome acquiring features of FCH or VBDS may develop in HCV‐infected RTx patients. The association with high viral load implicated the virus in the pathogenesis. Drastic reduction of immunosuppression may favourably affect the outcome.     

Anti-Phospholipase A2 Receptor Antibody Titer Predicts Post-Rituximab Outcome of Membranous Nephropathy

Rituximab induces nephrotic syndrome (NS) remission in two-thirds of patients with primary membranous nephropathy (MN), even after other treatments have failed. To assess the relationships among treatment effect, circulating nephritogenic anti-phospholipase A₂ receptor (anti-PLA₂R) autoantibodies and genetic polymorphisms predisposing to antibody production we serially monitored 24-hour proteinuria and antibody titer in patients with primary MN and long-lasting NS consenting to rituximab (375 mg/m²) therapy and genetic analyses. Over a median (range) follow-up of 30.8 (6.0–145.4) months, 84 of 132 rituximab-treated patients achieved complete or partial NS remission (primary end point), and 25 relapsed after remission. Outcomes of patients with or without detectable anti-PLA₂R antibodies at baseline were similar. Among the 81 patients with antibodies, lower anti-PLA₂R antibody titer at baseline (P=0.001) and full antibody depletion 6 months post-rituximab (hazard ratio [HR], 7.90; 95% confidence interval [95% CI], 2.54 to 24.60; P<0.001) strongly predicted remission. All 25 complete remissions were preceded by complete anti-PLA₂R antibody depletion. On average, 50% anti-PLA₂R titer reduction preceded equivalent proteinuria reduction by 10 months. Re-emergence of circulating antibodies predicted disease relapse (HR, 6.54; 95% CI, 1.57 to 27.40; P=0.01), whereas initial complete remission protected from the event (HR, 6.63; 95% CI, 2.37 to 18.53; P<0.001). Eighteen patients achieved persistent antibody depletion and complete remission and never relapsed. Outcome was independent of PLA2R1 and HLA-DQA1 polymorphisms and of previous immunosuppressive treatment. Therefore, assessing circulating anti-PLA₂R autoantibodies and proteinuria may help in monitoring disease activity and guiding personalized rituximab therapy in nephrotic patients with primary MN.     

Xenoreactive CD4+ memory T cells resist inhibition by anti-CD44 mAb and reject islet grafts via a Th2-dependent pathway

Peng YZ, Chen JB, Shao W, Wang FY, Dai HL, Cheng PP, Xia JJ, Wang F, Huang R, Zhu Q, Qi Z. Xenoreactive CD4⁺ memory T cells resist inhibition by anti‐CD44 mAb and reject islet grafts via a Th2‐dependent pathway. Xenotransplantation 2011; 18: 252–261. © 2011 John Wiley & Sons A/S. Abstract: Background: Memory T cells are a significant barrier to the induction of transplant tolerance. Our previous study demonstrated that multiple applications of anti‐CD44 monoclonal antibody (mAb) could significantly inhibit CD4⁺ memory T cells from mediating rejection of cardiac allografts. Now, we sought to explore the effect and mechanism of anti‐CD44 mAb on the rejection of islet allografts and xenografts mediated by CD4⁺ memory T cells. Methods: In this study, we first engrafted skin grafts of C57BL/6 (B6) mice or Dark Agouti (DA) rats onto BALB/c mice to induce donor‐reactive memory T cells. We adoptively transferred purified CD4⁺ memory T cells to BALB/c origin nude mice and then transplanted islet allografts and xenografts to produce the Allo‐Tx and Xeno‐Tx models, respectively. We subsequently administered multiple anti‐CD44 mAb and observed changes in the survival times of the islet grafts. Results: In the Allo‐Tx model, the mean survival time (MST) of the grafts was 7.7 days in the isotype group, and 20.3 days in the anti‐CD44 group. In the Xeno‐Tx model, the MST of the grafts was 7.2 days in the isotype group and 8.2 days in the anti‐CD44 group. Compared with the isotype group, CD4⁺ T cells on the grafts in the anti‐CD44 group were significantly decreased in both the Allo‐Tx and Xeno‐Tx models, but the proportion of CD4⁺ memory T cells in the spleens and draining lymph nodes of the recipient nude mice in the anti‐CD44 group was significantly decreased in the Allo‐Tx model, while it was increased in the Xeno‐Tx model. The production of donor‐specific IgG antibody in the anti‐CD44 group did not vary in the Allo‐Tx model, while it was markedly elevated in the Xeno‐Tx model. Furthermore, the expression of interferon gamma in the anti‐CD44 group was markedly decreased in both the Allo‐Tx and Xeno‐Tx models, while the expression of IL‐4 in the anti‐CD44 group was significantly increased only in the Xeno‐Tx model. Conclusion: Multiple applications of the anti‐CD44 mAb could significantly inhibit donor‐reactive CD4⁺ memory T cells from rejecting grafts via a Th1‐dependent pathway, but xenoreactive CD4⁺ memory T cells can avoid the effects of anti‐CD44 mAb to reject islet xenografts via a Th2‐dependent pathway.     

Characteristics of patients with coexisting IgA nephropathy and membranous nephropathy

Background: Coexistence of IgA nephropathy (IgAN) and membranous nephropathy (MN) in the same patient is rare. Few studies have reported the clinical and pathological features of patients with combined IgAN and MN (IgAN–MN).

Methods: The clinico-pathological features, levels of galactose-deficient IgA1 (Gd-IgA1) and autoantibodies against M-type transmembrane phospholipase A₂ receptor (anti-PLA₂R) in sera were compared among IgAN–MN, IgAN, and MN patients.

Results: Twenty-six patients with biopsy-proven IgAN–MN were enrolled. The mean age at biopsy was 43.6?±?15.9?years, and 65.4% were male. Proteinuria and estimated glomerular filtration rate (eGFR) levels in patients with IgAN–MN were similar to that of MN patients. Compared with the IgAN patients, IgAN–MN patients showed a higher median proteinuria level (4.3 vs. 1.2?g/day, p?2, p?p?=?.801). Percentage of IgAN–MN patients with detectable serum levels of anti-PLA₂R was lower than that of MN patients (38.5% vs. 68.6%, p?=?.011).

Conclusions: IgAN–MN patients display similar clinical features to MN patients and milder pathological lesions than IgAN patients. IgAN–MN patients have similar levels of Gd-IgA1 to those of IgAN patients, and a lower proportion of anti-PLA₂R than MN patients.     

Low prevalence of HBV DNA in the liver allograft from anti‐HBc‐positive donors: a single‐center experience

Pan J‐J, Oh S‐H, Soldevila‐Pico C, Nelson DR, Liu C. Low prevalence of HBV DNA in the liver allograft from anti‐HBc‐positive donors: a single‐center experience.
Clin Transplant 2011: 25: 164–170. © 2010 John Wiley & Sons A/S. Abstract: Allografts from donors positive for antibody to hepatitis B core antigen (anti‐HBc⁺) can transmit hepatitis B virus (HBV) to the recipients. We aimed to study the prevalence of HBV DNA in liver allografts from anti‐HBc⁺ donors. Between January 2003 and December 2008, this retrospective study identified 18 patients who received a liver from an anti‐HBc⁺ donor. Pre‐ and post‐transplantation HBV serology and serum HBV DNA level of the study subjects were reviewed. DNA extracted from liver biopsy tissue was used for PCR assay. Immunohistochemistry was also performed to determine viral protein expression. We observed a low prevalence of HBV DNA in allografts from anti‐HBc⁺ donors even among patients who did not receive prophylaxis. Only one of 18 patients had detectable HBV DNA in the liver allograft. This recipient was seronegative for HBV before transplantation and did not receive prophylaxis after transplantation, and developed de novo hepatitis B. Of the five patients who were positive for both antibody to hepatitis B surface antigen and anti‐HBc before transplantation and did not receive prophylaxis after transplantation, none developed HBV infection. Prophylaxis for HBV is important for seronegative recipients receiving a liver from an anti‐HBc⁺ donor. Such prophylaxis may not be necessary for recipients who do not have detectable HBV DNA in the liver allograft.     

Soluble CD30 and ELISA‐detected human leukocyte antigen antibodies for the prediction of acute rejection in pediatric renal transplant recipients

Biomarker‐based post‐transplant immune monitoring for the prediction of impending graft rejection requires validation in specific patient populations. Serum of 28 pediatric renal transplant recipients within the framework of a well‐controlled prospective randomized trial was analyzed pre‐ and post‐transplant for soluble CD30 (sCD30), a biomarker reflecting mainly T‐cell reactivity, and anti‐human leukocyte antigen (anti‐HLA) antibody reactivity, a biomarker for B‐cell activation. A sCD30 concentration ≥40.3 U/ml on day 14 was able to discriminate between patients with or without biopsy‐proven acute rejection (BPAR) with a sensitivity of 100% and a specificity of 76%. Six of seven patients (86%) with BPAR showed a sCD30 above this cut‐off, whereas only 3/21 patients (14%) without BPAR had a sCD30 above this cut‐off (P = 0.004). For pre‐ and post‐transplant anti‐HLA class II reactivities by enzyme‐linked immunosorbent assay, a cut‐off value of 140 optical density was able to discriminate rejecters from nonrejecters with a sensitivity of 86% or 71% and a specificity of 81% or 90%, respectively. Withdrawal of steroids was associated with a approximately twofold higher serum sCD30 compared to controls, but did not affect anti‐HLA reactivities. An increased post‐transplant sCD30 serum concentration and positive pre‐ and post‐transplant anti‐HLA class II reactivities are informative biomarkers for impending BPAR in pediatric renal transplant recipients. (TWIST, Clinical Trial No: FG‐506‐02‐43)     

Impact of kidney transplantation on sleep apnea severity: A prospective polysomnographic study

Fluid overload has been associated with a high prevalence of sleep apnea (SA) in patients with end‐stage kidney disease (ESKD). In this prospective study, we hypothesized that improvement in kidney function and hydration status after kidney transplantation (Tx) may result in an improvement in SA severity. A total of 196 patients on the kidney Tx waiting list were screened for SA using home nocturnal polysomnography (PSG) to measure the apnea‐hypopnea index (AHI) and underwent bioimpedance to assess body composition. Of 88 participants (44.9%) with SA (AHI ≥ 15/h), 42 were reassessed 6 months post‐Tx and were compared with 27 control patients. There was a significant, but small, post‐Tx improvement in AHI (from 44.2 ± 24.3 to 34.7 ± 20.9/h, P = .02) that significantly correlated with a reduction in fluid overload (from 1.8 ± 2.0 to 1.2 ± 1.2 L, P = .02) and body water (from 54.9% to 51.6%, P = .003). A post‐Tx increase in body fat mass (from 26% to 30%, P = .003) possibly blunted the beneficial impact of kidney Tx on SA. All parameters remained unchanged in the control group. In conclusion, SA is a frequent condition in ESKD patients and partially improved by kidney Tx. We suggest that SA should be systematically assessed before and after kidney Tx. ClinicalTrials.gov Identifier: NCT02020642.     

Desensitization for renal transplantation: depletion of donor‐specific anti‐HLA antibodies,preservation of memory antibodies,and clinical risks

Desensitization protocols reduce donor‐specific anti‐HLA antibodies (DSA) and enable renal transplantation in patients with a positive complement‐dependent cytotoxic cross‐match (CDC‐CXM). The effect of this treatment on protective antibody and immunoglobulin levels is unknown. Thirteen patients with end‐stage renal disease, DSA and positive CDC‐CXM underwent desensitization. Sera collected pre‐ and post‐transplantation were analysed for anti‐tetanus and anti‐pneumococcal antibodies, total immunoglobulin (Ig) levels and IgG subclasses and were compared to healthy controls and contemporaneous renal transplant recipients treated with standard immunosuppression alone. Ten patients developed negative CDC‐CXM and enzyme‐linked immunosorbent assay (ELISA) and underwent successful transplantation. Eight recipients achieved good graft function without antibody‐mediated or late rejection, BK virus or cytomegalovirus infection. One patient had primary non‐function due to recurrent oxalosis, and one patient with immediate graft function died from septicaemia. Seven recipients required post‐operative transfusion and three developed septicaemia. DSA remained negative by ELISA at 12 months, but were detectable by Luminex^®. Anti‐tetanus and anti‐pneumococcal antibodies, total Ig and IgG subclasses were below the normal range but comparable to levels in renal transplant recipients who had not undergone desensitization. Desensitization protocols effectively reduce DSA and allow successful transplantation. Post‐operative bleeding and short‐term infectious risk is increased. Protective antibody and serum immunoglobulin levels are relatively preserved.