Nephrotic syndrome after stem cell transplantation

Kidney Biopsy Findings Among Allogenic Hematopoietic Stem Cell Transplant Recipients With Kidney Injury: A Case Series

Rationale and Objective

The incidence of kidney disease is high in patients after allogeneic hematopoietic cell transplantation (aHCT). Although rarely performed, kidney biopsy may be useful to make a precise diagnosis because several mechanisms and risk factors can be involved, and to adjust the treatment accordingly. This case series aimed to report the spectrum of biopsy findings from patients with kidney injury after aHCT.

Study Design

Single-center retrospective case series.

Setting and Participants

All individuals who underwent a native kidney biopsy, among all adult patients who received aHCT in a tertiary hospital in Montreal (Canada) from January 1, 2010, to December 31, 2020, were identified, and the clinical data were extracted from their medical records.

Results

A total of 17 patients were included. Indications for biopsy included acute kidney injury (n=6), chronic kidney disease (n=5), nephrotic syndrome (n=4), and subnephrotic proteinuria (n=2). Pathologic findings from the kidney biopsy were heterogenous: 10 patients showed evidence of thrombotic microangiopathy (TMA), 5 of acute tubular injury, and 4 of membranous nephropathy. Cases of acute interstitial nephritis, BK virus nephropathy, immune complex nephropathy, focal and segmental glomerulosclerosis, minimal change disease, and karyomegalic-like interstitial nephritis were also described.

Limitations

There was no systematic kidney biopsy performed for all patients with kidney injury after aHCT. Only a small proportion of patients with kidney damage underwent biopsy, making the results less generalizable.

Conclusions

Kidney biopsy is useful in patients with kidney disease after aHCT to make a precise diagnosis and tailor therapy accordingly. This series is one of the few published studies describing pathologic findings of biopsies performed after aHCT in the context of acute kidney injury and chronic kidney disease. TMA was widely present on biopsy even when there was no clinical suspicion of such a diagnosis, suggesting that the current clinical criteria for a diagnosis of TMA are not sensitive enough for kidney-limited TMA.

Impact of severe acute kidney injury and chronic kidney disease on allogeneic hematopoietic cell transplant recipients: a retrospective single center analysis

Acute kidney injury (AKI) increases early mortality in allogeneic hematopoietic cell transplant (allo-HCT) recipients and may accelerate chronic kidney disease (CKD) development. We analyzed prospective variables related to AKI and CKD in 422 allo-HCT recipients to establish risk factors of severe acute renal failure and CKD. Renal function and creatinine were periodically assessed from baseline till the last follow-up. Sixty-three patients (14%) developed severe AKI (AKI-3) at 100 days post transplant and 15% at 12 months. Variables associated with AKI-3 were age above 55 years [hazard ratio (HR): 2.4; p = 0.019], total body irradiation (TBI) (HR: 1.8; p = 0.044), high-risk cytomegalovirus reactivation (HR: 1.8; p = 0.041), and methotrexate as GVHD prophylaxis (HR: 2.1; p = 0.024). AKI-3 increased the mortality risk (HR: 2.5, 95% confidence interval: 1.9-3.4). The CKD prevalence in 161 living patients was 10.2% at the last follow-up and in most, CKD developed 1 year post HCT, independent of AKI. The CKD at 1 year post HCT was associated with increased mortality (HR: 3.54; p < 0.001). Interestingly, pretransplant CKD was associated with early mortality (HR: 5.6; p < 0.001). In fact, pre- and posttransplant CKD had independent unfavorable long-term outcomes. These pretransplant factors can potentially be targeted to improve allo-HCT outcomes.

De novo glomerular diseases after renal transplantation: How is it different from recurrent glomerular diseases?

The glomerular diseases after renal transplantation can occur de novo, i.e., with no relation to the native kidney disease, or more frequently occur as a recurrence of the original disease in the native kidney. There may not be any difference in clinical features and histological pattern between de novo glomerular disease and recurrence of original glomerular disease. However, structural alterations in transplanted kidney add to dilemma in diagnosis. These changes in architecture of histopathology can happen due to: (1) exposure to the immunosuppression specifically the calcineurin inhibitors (CNI); (2) in vascular and tubulointerstitial alterations as a result of antibody mediated or cell-mediated immunological onslaught; (3) post-transplant viral infections; (4) ischemia-reperfusion injury; and (5) hyperfiltration injury. The pathogenesis of the de novo glomerular diseases differs with each type. Stimulation of B-cell clones with subsequent production of the monoclonal IgG, particularly IgG3 subtype that has higher affinity to the negatively charged glomerular tissue, is suggested to be included in PGNMID pathogenesis. De novo membranous nephropathy can be seen after exposure to the cryptogenic podocyte antigens. The role of the toxic effects of CNI including tissue fibrosis and the hemodynamic alterations may be involved in the de novo FSGS pathophysiology. The well-known deleterious effects of HCV infection and its relation to MPGN disease are frequently reported. The new concepts have emerged that demonstrate the role of dysregulation of alternative complement pathway in evolution of MPGN that led to classifying into two subgroups, immune complex mediated MPGN and complement-mediated MPGN. The latter comprises of the dense deposit disease and the C3 GN disease. De novo C3 disease is rather rare. Prognosis of de novo diseases varies with each type and their management continues to be empirical to a large extent.

Nephrotic syndrome as a complication of chronic graft-versus-host disease after allogeneic haemopoietic stem cell transplantation

Nephrotic syndrome (NS) is a rare complication following allogeneic haemopoietic stem cell transplantation (allo-HSCT), with limited current understanding of its pathogenesis. Here, we describe four cases of NS following allo-HSCT diagnosed at our institutions to identify key clinical and pathological features. In addition, a PubMed search was performed to identify existing reports that were pooled together with our cases for analysis. NS occurred as a late complication following allo-HSCT, with median onset 19.5 months after transplant (range: 3.9-84 months). The most common histopathology observed was membranous nephropathy; however, cases of minimal change disease have also been reported. There is a high incidence of prior extra-renal graft-versus-host disease (GvHD), with all four of our cases and 82% of published cases having prior GvHD. Glucocorticosteroids are the most common treatment, with variable degrees of response. Responses to immunosuppression with calcineurin inhibitors and rituximab have been described in steroid-refractory cases.

Renal dysfunction following bone marrow transplantation

Acute kidney injury and long-term renal dysfunction are common problems following bone morrow transplantation (BMT) and highly related to mortality. The frequency and risk of renal dysfunction are directly related to the method of BMT, with myeloablative allogeneic BMT being associated to the highest risk followed by non-myeloablative allogeneic and myeloablative autologous BMT. The type of BMT is, thus, more important than co-factors such as advanced age, comorbidities, or high baseline serum creatinine. The causes for renal failure are multiple and include chemotherapy and high-dose radiation with fluid loss by diarrhea or vomiting, sepsis or nephrotoxic drugs such as calcineurin inhibitors and antimicrobials. Additionally, there are BMT-specific reasons for renal dysfunction including marrow infusion toxicity, hepatic veno-occlusive disease, thrombotic microangiopathy (TMA) and graft versus host disease (GvHD). Once the kidney has been damaged, the therapy depends on the underlying disease. Particularly in cases of TMA and GvHD, immunosuppressive therapy is essential. In TMA, plasma exchange therapy or eculizumab should be additionally considered if the complement system is affected. Hence, patients with these causes should preferably be referred to tertiary centers to allow early diagnosis and appropriate treatment.

Adult Nephrotic Syndrome after Hematopoietic Stem Cell Transplantation: Renal Pathology is the Best Predictor of Response to Therapy

Nephrotic syndrome (NS) after allogeneic hematopoietic stem cell transplantation (HSCT) is a rare phenomenon usually associated with graft-versus-host disease (GVHD). This systematic review of post-HSCT NS cases reported in the literature aimed to identify risk factors and unique features of the disease in this clinical setting. One hundred sixteen cases of post-HSCT NS published in the English literature between 1988 and 2015 were revealed and analyzed. The median onset of NS was 20.5 months (range, 3 to 174) post-HSCT. NS development was associated with acute or chronic GVHD in 87.2% of cases. Membranous nephropathy (MGN) was the most frequent pathology (65.5%), followed by minimal change disease (MCD) (19%). Complete remission of the NS was achieved in 63.5% of patients (59.1% of MGN cases and 81.3% of MCD cases; P = .15). Patients presenting with MCD recovered at a median of 1.75 months (range, 1 to 12) and with MGN a median of 7 months (range, 1 to 53) (P = .001). NS was treated with corticosteroids alone in 16.8% of patients and with a combination of corticosteroids and other immunosuppressive agents in 73.5% of patients. Univariate analysis failed to identify a single predictive factor of response to therapy. In conclusion, post-HSCT NS usually develops concomitant to GVHD and is associated with high rates of response to therapy. Although most patients were treated with a combination of immunosuppressive drugs, single-agent therapy with steroids may be sufficient in some cases.

De novo glomerulitis associated with graft-versus-host disease after allogeneic hematopoietic stem cell transplantation: A single-center experience

BACKGROUND

Nephrotic syndrome (NS) and proteinuria are uncommon, often unrecognized manifestations of graft-versus-host disease (GVHD) after hematopoietic stem cell transplantation (HSCT). Only a few isolated case reports and case series involving smaller number of patients who developed NS after HSCT have been published.

METHODS

We reviewed the renal histopathological examination findings and clinical records of 15 patients who developed proteinuria after HSCT at Seoul and Yeouido St. Mary's Hospital (Seoul, Korea). We also measured the anti-PLA2R antibodies (M-type phospholipase A2 receptor) in the serum samples from the seven patients at the time of renal biopsy.

RESULTS

All patients had GVHD. The most common indication for biopsy was proteinuria (>1 g/day), with nine patients having nephrotic range proteinuria. The most common histopathological finding was membranous nephropathy (MN; n = 12). Other findings were membranoproliferative glomerulonephritis, C1q nephropathy, and diabetic nephropathy. Eleven patients were treated with immunosuppressive agents, and three patients were treated only with angiotensin II receptor blocker. The overall response rate, including complete remission (urinary protein level <0.3 g/day) and partial remission (urinary protein level = 0.31-3.4 g/day), was 73%. The mean follow-up period was 26 months, and none of the patients developed end-stage renal disease. All of the seven patients with MN had negative findings for anti-PLA2R antibodies, measured using an enzyme-linked immunosorbent assay kit.

CONCLUSION

In this study the findings of 15 renal biopsies were analyzed and to our knowledge this is the largest clinicopathological study of GVHD-related biopsy-proven nephropathy. Approximately 80% of the patients were MN and 73% responded either partially or completely to immunosuppressive treatment. Currently, there is an increase in the incidence of GVHD-mediated renal disease, and therefore, renal biopsy is essential for diagnosing the nephropathy and preventing the progression of renal disease.

De novo membranous nephropathy (MN) in kidney allografts. A peculiar form of alloimmune disease?

De novo membranous nephropathy (MN) is an uncommon complication of kidney transplantation, which shows histological findings similar to those seen in recurrent MN, but with some distinct differences. The clinical presentation may be variable, from asymptomatic to nephrotic proteinuria. The disease may run an indolent course or may have an accelerated course leading to allograft loss. De novo membranous nephropathy (MN) can develop in transplant recipients with viral hepatitis, Alport syndrome, ureteral obstruction, renal infarction, or in conjunction with recurrent IgA nephritis. Histologic signs of allograft rejection are often associated with or can antedate de novo MN. These findings suggest that donor-specific antibodies and antibody-mediated rejection might play a pathogenetic role in some patients with de novo MN. However, signs of rejection were absent in a number of cases, and in some instances the disease developed in recipients of "full house" HLA- matched kidneys. Thus, it seems possible that de novo MN is not because of allograft rejection per se, but is triggered by different injuries that can create an inflammatory environment, activate innate immunity, and expose hidden (cryptic) antigens, probably different from those observed to be involved in idiopathic MN. These events can lead to the production of circulating antibodies and in situ formation of immune complexes (IC) and the morphological lesion of MN.

The role of graft-versus-host disease in haematopoietic cell transplantation-associated glomerular disease

BACKGROUND

Glomerular disease among haematopoietic cell transplantation recipients has been attributed to chronic graft-versus-host disease. Clinical outcomes of this population may be influenced by the haematopoietic cell transplantation conditioning regimen, donor factors and chronic graft-versus-host disease.

METHODS

In this review, 95 cases of haematopoietic cell transplantation-associated glomerular disease were identified from literature review for analysis. Patient characteristics, the association of chronic graft-versus-host disease with glomerular diseases, and the impact of host and haematopoietic cell transplantation regimen on outcomes were evaluated.

RESULTS

The median onset of glomerular disease from haematopoietic cell transplantation and from cessation of immunosuppressive agents was 15.5 and 1 month, respectively. Although chronic graft-versus-host disease was common among haematopoietic cell transplant recipients with glomerulonephritis (72%), this was no different from that observed in the overall haematopoietic cell transplantation population. Membranous nephropathy and minimal change disease are the most prevalent glomerular diseases among haematopoietic cell transplantation recipients. Chronic graft-versus-host disease, donor factors and haematopoietic cell transplant regimen did not significantly impact outcomes in this study population.

CONCLUSIONS

Pathogenic mechanisms in addition to (or other than) chronic graft-versus-host disease are likely contribute to haematopoietic cell transplantation-associated glomerular disease. Further investigation will be required to delineate clearly the pathogenesis.

Chronic kidney disease in long-term survivors of myeloablative allogeneic haematopoietic cell transplantation: prevalence and risk factors

BACKGROUND

Chronic kidney disease (CKD) seems to be common in long-term survivors of haematopoietic cell transplantation (HCT). However, the range of its frequency is very wide, likely due to variability in the definitions of CKD and the periods of follow-up.

METHODS

We conducted a cross-sectional and retrospective study in 158 adults who received myeloablative allogeneic HCT for lymphohaematologic malignancies at least 3 years ago and are alive today. The mean survival time was 6.15 +/- 4.88 years (range: 3-16 years). CKD was defined as a sustained decrease in glomerular filtration rate (GFR) or persistent proteinuria for a period more than 3 months. GFR was calculated based on serum creatinine (Cr) using the Modification of Diet in Renal Disease formula. Serum Cr and proteinuria were measured at least on three occasions separated by one or more months before the investigation. CKD was classified according to the National Kidney Foundation CKD staging. Proteinuria was defined as positive dipstick test > or =1+. The factors associated with the presence of CKD with a decrease of GFR (CKD > or = stage 3) were examined using multivariate logistic regression analysis, adjusted for demographic and clinical characteristics.

RESULTS

The prevalence of proteinuria was found in 36 out of 158 patients (22.8%). The prevalence of each CKD stage was as follows: Stage 0 (no CKD), 98 patients (62.0%); Stage 1, 18 patients (11.4%); Stage 2, 15 patients (9.5%); Stage 3, 8 patients (5.1%); Stage 4, 10 patients (6.3%) and Stage 5, 9 patients (5.7%). Initiation of chronic dialysis treatment or transplant was performed in seven CKD stage-5 patients (4.4%) at a mean of 10.9 +/- 3.72 years after HCT. Multivariate analysis identified acute kidney injury with HCT [odds ratio (OR), 9.920; 95% confidence interval (CI), 2.084-39.68; P = 0.0051], hypertension after HCT (OR, 4.031; 95% CI, 1.044-13.06; P = 0.0346) and survival time after HCT (OR, 4.275; 95% CI, 2.823-23.04; P = 0.0481) as significant factors associated with the presence of CKD > or = stage 3.

CONCLUSIONS

A remarkably high percentage of long-term survivors had evidence of proteinuria and all stages of CKD. CKD in transplant recipients may result from incomplete recovery from acute renal insults, hypertension and increasing longevity. The CKD cohort should be at a great risk for end-stage renal disease and cardiovascular morbidity and mortality. The burden of CKD should be recognized as a significant public health problem.

Late effects of chronic graft-versus-host disease

Hematopoietic-cell transplantation (HCT) has become applicable to a broader range of ages and underlying diagnoses through advances in the utilization of alternative donors and stem-cell sources, reduced-intensity preparative regimens, and improved supportive care. The reduction in early transplant-related mortality means that more survivors will potentially develop chronic graft-versus-host disease (cGVHD) and associated late effects. Recipients of HCT are at risk for late end-organ dysfunction as a complication of chemoradiotherapy given before HCT, but disturbances are often multifactorial. This review focuses on problems arising predominantly as a result of cGVHD and its therapies. Disabilities caused by severe or inadequately treated cGVHD include keratoconjunctivitis sicca, bronchiolitis obliterans, skin ulcers, joint contractures, esophageal and vaginal stenosis, osteoporosis, avascular necrosis, and others. Almost all organ systems may be involved, and a broad approach is needed to allow recognition and anticipation of problems so that prevention or early intervention is possible.

Renal pathology in hematopoietic cell transplantation recipients

Hematopoietic cell transplantation-associated renal injury may be related to a combination of factors including chemotherapy, radiation, infection, immunosuppressive agents, ischemia, and graft-versus-host disease. Renal biopsy specimens from hematopoietic cell transplant recipients at two institutions (Stanford University Medical Center and Oregon Health & Science University) were reviewed in correlation with clinical data. Fifteen cases were identified (post hematopoietic cell transplant time 0.7-14.5 years), including six with autologous hematopoietic cell transplant. Indications for renal biopsy included proteinuria (n=13; nephrotic range in 8), increased serum creatinine (n=10), or both (n=6). Many patients had multiple pathologic findings on renal biopsy. Membranous glomerulonephritis was the most common diagnosis (n=7), including two patients with autologous hematopoietic cell transplant and five with evidence of chronic graft-versus-host disease elsewhere. Four membranous glomerulonephritis patients achieved sustained remission with rituximab therapy. Other glomerular pathology included focal segmental glomerulosclerosis (n=1) and minimal change disease (n=1). Evidence of thrombotic microangiopathy was common (in isolation or combined with other pathology), as was acute tubular necrosis and tubulointerstitial nephritis. Of 14 patients with follow-up (2-64 months, mean 19 months), 6 had chronic renal insufficiency (serum creatinine >1.5 mg/dl), 2 had end stage renal disease, and 6 had essentially normal renal function. Our retrospective study shows that renal dysfunction in hematopoietic cell transplant recipients is often multifactorial, and biopsy may reveal treatable causes. Membranous glomerulonephritis is seen in autologous and allogeneic hematopoietic cell transplant recipients, and may respond to anti-B-cell therapy, which has implications regarding pathogenesis and relationship to graft-versus-host disease.

Target antigens and nephritogenic antibodies in membranous nephropathy: of rats and men

Membranous nephropathy, a disease characterized by an accumulation of immune deposits on the outer aspect of the glomerular basement membrane, is the most common cause of idiopathic nephrotic syndrome in white adults. In the rat model of Heymann nephritis, the target antigen of antibodies is megalin, a multiligand receptor expressed at the podocyte cell surface. This review summarizes key findings provided by this experimental model and by our discovery of neutral endopeptidase being the alloantigen involved in neonatal cases of membranous nephropathy. We discuss the role of alloimmunization as a new mechanism of renal disease and the approach that we use to identify new podocyte antigens. We also summarize current knowledge on the mechanism of proteinuria, with special emphasis on the role of complement. In conclusion, substantial progresses have been made in understanding molecular mechanisms of membranous nephropathy, which should lead to novel therapeutic approaches.

Spectrum of renal pathology in hematopoietic cell transplantation: a series of 20 patients and review of the literature

BACKGROUND AND OBJECTIVES

Hematopoietic cell transplantation is a common treatment option for a variety of hematopoietic malignancies. As a result of the use of total body irradiation and/or chemotherapeutic agents, renal dysfunction often ensues. Many pharmacologic agents, such as cyclosporine and high-intensity conditioning regimens, have been linked with thrombotic microangiopathy. In addition, an association between membranous nephropathy and graft-versus-host disease has been reported in this clinical setting.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

A study of autologous and allogeneic hematopoietic cell transplantation patients with renal dysfunction was conducted to document the spectrum of renal manifestations. The pathology files at the University of Washington and University of Chicago Medical Centers were reviewed, and 20 patients with a kidney biopsy after hematopoietic cell transplantation were identified. The histologic findings were correlated with relevant clinical information.

RESULTS

A wide spectrum of renal diseases could be classified into four categories: (1) Complications related to hematopoietic cell transplantation (conditioning regimen, immunosuppression, or posttransplantation complications), (2) podocytopathy, (3) membranous nephropathy, or (4) recurrence or persistence of original hematologic disease. Pathologic diagnoses included thrombotic microangiopathy, polyoma virus nephropathy, acute kidney injury/acute tubular necrosis, acute and chronic interstitial nephritis, minimal-change disease, "tip" variant of focal segmental glomerulosclerosis, membranous nephropathy, amyloidosis, and myeloma cast nephropathy. Membranous nephropathy, minimal-change disease, and amyloidosis were common causes of severe proteinuria. Because of the conditioning regimens, posttransplantation complications, and potential nephrotoxic agents used during hematopoietic cell transplantation, it was difficult to attribute the subsequent renal dysfunction to specific factors.

CONCLUSIONS

The renal biopsy remains essential for diagnosing the underlying injury that can affect one or more compartments of the kidney in this unique clinical setting.

Minimal-change nephrotic syndrome in a hematopoietic stem-cell transplant recipient

BACKGROUND

A 61-year-old woman received standard immunizations, including Haemophilus influenzae type B, diphtheria, tetanus toxoid, and unconjugated 23-valent pneumococcal vaccine (Pneumovax), Merck & Co., Inc., Whitehouse Station, NJ), 1 year after undergoing nonmyeloablative hematopoietic stem-cell transplantation for acute myelogenous leukemia. After 5 days, she developed fatigue with progressive weight gain and edema, and 14 days after immunization she presented with anasarca and was found to have acute renal failure and nephrotic proteinuria.

INVESTIGATIONS

Physical examination, serum chemistry, examination of urine sediment, renal ultrasound using Doppler scanning, 24 h urine collection, and renal biopsy.

DIAGNOSIS

Minimal-change nephrotic syndrome with acute tubular injury.

MANAGEMENT

Aggressive diuresis and oral corticosteroid therapy.

New insights into the pathogenesis of membranous glomerulonephritis

PURPOSE OF REVIEW

Membranous nephropathy is one of the most common glomerulopathies. Current treatments are entirely empirical, and concept-driven therapies are dramatically lacking. This review focuses on new pathophysiologic aspects of the disease, with special emphasis on the antigenic targets of pathogenic antibodies.

RECENT FINDINGS

Neutral endopeptidase - a podocyte antigen that can digest biologically active peptides - was recently identified as the target antigen of antibodies deposited in the subepithelial space of glomeruli in a subset of patients with antenatal membranous nephropathy. The mothers became immunized because they are deficient in neutral endopeptidase due to truncating mutations in the gene. Membranous nephropathy could be transferred to the rabbit by injection of mothers' immunoglobulin. Development of the renal disease was associated with anti-neutral endopeptidase IgG1.

SUMMARY

Membranous nephropathy most likely is a heterogeneous disease, although a common denominator may be that podocytes provide antigenic targets for in-situ formation of glomerular immune deposits. Identification of neutral endopeptidase and additional (podocyte) antigens and characterization of their epitopes should make it possible to design more effective and better tolerated therapies. Fetomaternal alloimmunization is a novel mechanism of renal disease that may apply to other organs as well.

Nephrotic syndrome in a child after umbilical-cord-blood transplantation

We report a 12-year-old girl who developed nephrotic syndrome 6 months after umbilical-cord-blood transplantation (UCBT) for acute lymphoblastic leukemia (L2). In addition to nephrotic syndrome, she also showed autoimmune hemolytic anemia, thrombocytopenia and gastrointestinal symptoms. Since these symptoms were manifested during the course of tapering immunosuppressive agents, a diagnosis of chronic graft-versus-host disease (GVHD) was made. Findings from a kidney biopsy were compatible with minimal-change disease (MCD), and focal glomerular capillary thrombosis and mild tubular damage were also noted. She was treated with methylprednisolone pulse therapy followed by oral prednisolone. Proteinuria disappeared in 14 days. Gastrointestinal symptoms, anemia and thrombocytopenia were also corrected. This is a case report of nephrotic syndrome as a manifestation of chronic GVHD developed after stem-cell transplantation. A review of the cases reported in the literature is also made.

Mesangial Proliferative Glomerulonephritis After Autologous Stem Cell Transplantation

Although glomerulonephritis and renal failure have been observed after allogenic stem cell transplantation, only a few such reports were published about patients undergoing autologous stem cell transplantation. We report a case of mesangial proliferative glomerulonephritis developing 4 months after autologous stem cell transplantation for chronic lymphatic leukemia. Serological test results, together with histological, immunohistochemical, and electronic microscopic findings of a kidney biopsy specimen, confirmed the diagnosis of mesangial proliferative glomerulonephritis in our patient. Complement and immunoglobulin A were not present in the kidney biopsy specimen. An abnormal clone, not previously reported, with the translocation t(5;11)(q31;q13) in blood and bone marrow was observed. The reason for and whether progenitor cells in stem cell transplantations could contribute to the development of glomerulonephritis remain open questions. Kidney biopsy should be performed in patients with microscopic hematuria and/or proteinuria after autologous stem cell transplantation.

Mechanisms of Disease: alloimmunization in renal diseases

Graft rejection has long been considered the paradigm of renal diseases induced by alloimmunization, particularly alloimmunization directed against HLA antigens. Accumulating evidence indicates that non-HLA immunity also has an important role in clinical transplantation. Targets of alloimmunization include antigens of tubular basement membrane, tubular epithelial cells and endothelial cells. They can be polymorphic allovariants (as shown in the rat) or 'hidden' antigens exposed when the graft is damaged. Alloimmunization can also occur when a person genetically deficient in a renal protein (e.g. the alpha5 (IV) collagen chain in X-linked Alport's syndrome or nephrin in Finnish-type nephrotic syndrome) is transplanted to treat end-stage renal failure. The non-mutated protein in the donor kidney is recognized as a foreign antigen, and the resulting alloimmune response can damage the graft. We have demonstrated that alloimmunity can also affect the native kidney. We have characterized a novel fetomaternal disease in which a genetic defect in the MME gene encoding neutral endopeptidase (NEP) in the mother leads to the development of membranous nephropathy in her fetus (maternal anti-NEP antibodies bind to NEP on fetal podocytes). Our findings raise the possibility that mutations or genetic polyporphisms in MME or other genes expressed by the podocyte are involved in alloimmune-mediated development of membranous nephropathy after kidney or bone marrow transplantation.

Nephrotic syndrome after allogeneic hematopoietic stem cell transplantation as a late complication of chronic graft-versus-host disease

BACKGROUND

This study aims to determine the incidence and outcome of nephrotic syndrome in patients who underwent allogeneic stem cell transplantation in a single center.

METHODS

Records of 279 adult patients with hematological diseases who underwent allogeneic hematopoietic stem cell transplantation were analyzed to evaluate the incidence and outcome of nephrotic syndrome. The diagnosis of chronic graft-versus-host disease was based on clinical evidence with histological confirmation whenever possible.

RESULTS

Of the 279 patients, 105 with a minimum follow-up of 100 days developed chronic graft-versus-host disease: six of these had nephrotic syndrome. The cumulative incidence of nephrotic syndrome was 8% at day +1,681. Patients grafted with peripheral blood stem cells had a higher probability of developing nephrotic syndrome than did those grafted with bone marrow: 24% and 3%, respectively. The pathological diagnosis was membranous glomerulonephritis in four patients, and minimal change disease in one; the diagnosis could not be histologically confirmed in the sixth patient. All patients had extensive chronic graft-versus-host disease and were receiving treatment with cyclosporine A and steroids (four patients). Response to immunosuppressive therapy with cyclosporine A and steroids was achieved in all patients at a median time of 12 weeks after transplantation.

CONCLUSION

Patients with chronic graft-versus-host disease may be considered to be at risk of nephrotic syndrome: careful monitoring of renal function is advisable, particularly in patients receiving allogeneic peripheral stem cell grafts.

Nephrotic syndrome after hematopoietic cell transplantation: do glomerular lesions represent renal graft-versus-host disease?

Glomerular disease associated with nephrotic syndrome has rarely been recognized as a distinct complication of allogeneic hematopoietic cell transplantation. Case reports in the English and Japanese literature since 1988 have described variable glomerular histology, comprising mainly membranous glomerulonephritis (MGN) in almost two thirds and minimal change disease (MCD) in nearly one quarter of patients. Review of the literature reveals a close temporal relationship between the development of nephrotic syndrome shortly after cessation of immunosuppression and the diagnosis of chronic graft-versus-host disease (GVHD). An association of glomerular disease with simultaneous GVHD was seen in 47% of patients overall. Nephrotic syndrome followed GVHD within 5 months in 60% of the combined MCD and MGN reports. A decrease in immunosuppressive medication use was linked to nephrotic syndrome occurrence within 9 months in 63% of patients with MCD and MGN. MCD occurred earlier after hematopoietic cell transplantation, was diagnosed sooner after medication change, and exhibited a better prognosis in comparison with MGN. Glomerular lesions after hematopoietic cell transplantation may therefore represent the renal manifestation of GVHD. Further studies are warranted to delineate the pathogenesis of this complication.