HLA-B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy

Nationwide Survey of Post-Transplant Glomerular Diseases, Based on the Japan Renal Biopsy Registry (J-RBR)

Background

Nationwide data on allograft kidney biopsies have been limited in number, in contrast to the large amount of accumulated data on native kidney biopsies. In this context, we have surveyed transplant biopsy data based on the nationwide database, the Japan Renal Biopsy Registry (J-RBR).

Material/Methods

A total of 2430 transplant biopsy cases were registered in the web-based J-RBR from January 2007 to January 2018. We categorized the entries regarding both the purpose of the biopsy and pathological diagnosis, and confirmed transplant glomerular diseases based on the clinical and pathological diagnosis.

Results

Of the 2430 total transplant biopsy cases, 637 cases, including 9 cases of baseline biopsy, 216 cases of protocol biopsy, and 232 cases of episode biopsy, had a pathological diagnosis, including glomerular diseases, rejection, calcineurin inhibitor nephropathy, and interstitial fibrosis and tubular atrophy. Of these, 127 cases presented with glomerular disease, including 8 cases of baseline biopsy, 23 of protocol biopsy, 59 of episode biopsy, and 37 of unknown purpose). A total of 127 biopsies with glomerular disease revealed a high prevalence of immunoglobulin A nephropathy (n=38, 29.9%), followed by mesangial proliferative glomerulonephritis (n=29, 22.8%) and focal segmental glomerulosclerosis (n=8, 6.3%) when focused on protocol and episode biopsies.

Conclusions

The nationwide transplant biopsy database demonstrated the pathological characteristics of 637 cases, including 127 cases of post-transplant glomerular disease. The protocol and episode biopsies included high prevalence rates of IgAN, followed by FSGS.

Recurrent and de novo Glomerulonephritis After Kidney Transplantation

The prevalence, pathogenesis, predictors, and natural course of patients with recurrent glomerulonephritis (GN) occurring after kidney transplantation remains incompletely understood, including whether there are differences in the outcomes and advances in the treatment options of specific GN subtypes, including those with de novo GN. Consequently, the treatment options and approaches to recurrent disease are largely extrapolated from the general population, with responses to these treatments in those with recurrent or de novo GN post-transplantation poorly described. Given a greater understanding of the pathogenesis of GN and the development of novel treatment options, it is conceivable that these advances will result in an improved structure in the future management of patients with recurrent or de novo GN. This review focuses on the incidence, genetics, characteristics, clinical course, and risk of allograft failure of patients with recurrent or de novo GN after kidney transplantation, ascertaining potential disparities between “high risk” disease subtypes of IgA nephropathy, idiopathic membranous glomerulonephritis, focal segmental glomerulosclerosis, and membranoproliferative glomerulonephritis. We will examine in detail the management of patients with high risk GN, including the pre-transplant assessment, post-transplant monitoring, and the available treatment options for disease recurrence. Given the relative paucity of data of patients with recurrent and de novo GN after kidney transplantation, a global effort in collecting comprehensive in-depth data of patients with recurrent and de novo GN as well as novel trial design to test the efficacy of specific treatment strategy in large scale multicenter randomized controlled trials are essential to address the knowledge deficiency in this disease.

[Current insights about recurrence of glomerular diseases after renal transplantation]

Recurrence of glomerular disease after renal transplantation is a frequent cause of graft loss. Incidence, risk factors and outcome of recurrence are widely due to the underlying glomerular disease. Graft biopsy analysis is required to confirm the definitive diagnosis of recurrence and to start an appropriate therapy that, in some cases, remains challenging to prevent graft failure. Increased use of protocol biopsy and recent advances in our understanding of the pathogenesis of some glomerular diseases with the identification of some relevant biomarkers provide a unique opportunity to initiate kidney-protective therapy at early stages of recurrence on the graft. This review summarizes our current knowledge on the management of many recurrent primary and secondary glomerulonephritis after kidney transplantation.

Primary IgA nephropathy: current challenges and future prospects

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide, exhibiting a variable clinical and pathological course and significantly contributing to the global burden of chronic kidney disease and end-stage renal disease. Current standards of care focus on optimization of antihypertensive and antiproteinuric therapies (typically renin- angiotensin system blockade) to reduce disease progression. Much recent attention has focused on whether additional immunosuppression confers better outcomes than supportive management alone, and indeed, several trials have demonstrated renoprotective effects following the use of oral corticosteroids. However, results have been inconsistent, and perceived benefits must be balanced against risks and adverse effects associated with generalized immunosuppression, as highlighted by the high-profile STOP-IgAN and TESTING clinical trials. Recent translational research in vitro and animal models of IgAN have generated greater insight into potential therapeutic targets for this complex autoimmune disease. Deeper understanding of the roles of the mucosal immune barrier, complement activation and deposition, T-cell dependent and independent mechanisms of B cell activation, and of the deposition and downstream inflammatory signaling pathways of nephritogenic polymeric IgA1 complexes (e.g., signaling of immune receptors via spleen tyrosine kinase) has formed the rationale for the development of novel agents and clinical trials of more targeted therapies. However, translating findings into clinical practice is challenging, with many immunopathological features of IgAN specific to humans. Recent comprehensive reviews outline current understanding of mechanisms of IgAN as well as ongoing and future clinical trials; it is not our aim to replicate this here. Instead, we take a mechanistic approach to current treatment strategies, outlining advantages and limitations of each before exploring ongoing research with potential translation into future targeted therapies for this complex disease.

Clinical Features, Treatment and Prognostic Factors of Post-Transplant Immunoglobulin A Nephropathy

Background

Initially described as a relatively benign condition, recent studies report graft loss in up to 50% of the patients with post-transplant IgA nephropathy. There is no evidence for the best therapeutic approach, and prognostic factors remain to be elucidated.

Material/Methods

Single center retrospective analysis of patients >12 years old, with clinically relevant post-transplant IgA nephropathy (proteinuria ≥1.0 g/g and/or graft dysfunction) and ≥6 months follow-up after diagnosis (n=47).

Results

Living donor transplants represented 85% of cases. Dysmorphic hematuria (100%), blood pressure elevation (95.7%), renal dysfunction (70.2%) and subnephrotic proteinuria (60.6%) predominated at presentation. Using the Oxford Classification, mesangial proliferation was the main histological lesion (91%). Treatment consisted mostly of blockade of the renin angiotensin system (89.4%) and modification of immunosuppression (85.1%), mainly by increasing oral steroids dose (83%), with venous pulse therapy in 63.8% of cases. Partial and complete remission occurred in 48.9% and 17% of cases, respectively. One patient died (sepsis) and 15 patients (31.9%) lost their grafts due to nephropathy. The percentage of decrease in glomerular filtration rate at diagnosis was independently associated with partial remission (HR 0.97, 95% CI 0.94–0.99, p=0.01) and graft loss (HR 1.13, 95% CI 1.06–1.20, p<0.001). Deceased donor (HR 28.04, 95% CI 4.41–178.39, p<0.001) and donor age (HR 1.1, 95% CI 1.04–1.16, p=0.001) were also risk factors for graft loss.

Conclusions

Despite treatment, most patients with post-transplant IgA nephropathy in this cohort study presented unfavorable outcomes, and graft dysfunction at diagnosis appeared to be the main prognostic marker.

Recurrence of primary glomerulonephritis: Review of the current evidence

In view of the availability of new immunosuppression strategies, the recurrence of allograft glomerulonephritis (GN) are reported to be increasing with time post transplantation. Recent advances in understanding the pathogenesis of the GN recurrent disease provided a better chance to develop new strategies to deal with the GN recurrence. Recurrent GN diseases manifest with a variable course, stubborn behavior, and poor response to therapy. Some types of GN lead to rapid decline of kidney function resulting in a frustrating return to maintenance dialysis. This subgroup of aggressive diseases actually requires intensive efforts to ascertain their pathogenesis so that strategy could be implemented for better allograft survival. Epidemiology of native glomerulonephritis as the cause of end-stage renal failure and subsequent recurrence of individual glomerulonephritis after renal transplantation was evaluated using data from various registries, and pathogenesis of individual glomerulonephritis is discussed. The following review is aimed to define current protocols of the recurrent primary glomerulonephritis therapy.

Predicting Post-Transplant Recurrence of IgA Nephropathy: The Importance of Crescents

BACKGROUND

Most studies that have assessed the predictors of recurrent IgA nephropathy (IgAN) in the renal allograft have focused on post-transplant features. Identifying high-risk pre-transplant features of IgAN is useful for counseling patients and may help in tailoring post-transplant immunosuppression.

METHODS

We investigated the pre-transplant clinical and biopsy features of 62 patients with IgAN who received transplants at Columbia University Medical Center from 2001 to 2012 and compared the characteristics and outcomes of patients with IgAN recurrence to those without recurrence. The primary outcome was time to recurrent IgAN. Secondary outcomes were a composite of doubling of creatinine or allograft failure, and recurrent IgAN as a cause of allograft dysfunction.

RESULTS

Of the 62 patients, 14 had recurrent IgAN in the allograft. Mean time to recurrence was 2.75 years. Those with recurrent disease were younger at the time of native kidney biopsy (29 vs. 41 years, p < 0.0009). Black race and Hispanic ethnicity composed a higher proportion of the recurrent disease group. On multivariable analysis, significant predictors of recurrent IgAN included age at diagnosis (hazards ratio (HR) 0.911, 95% CI 0.85-0.98), burden of crescents on native biopsy (HR 1.21 per 10% increase in crescents, 95% CI 1.00-1.47) and allograft rejection (HR 3.59, 95% CI 1.10-11.7).

CONCLUSIONS

Features of native IgAN can help predict the risk of recurrent disease in the renal allograft. In particular, immunologically active disease represented by earlier age of onset and greater burden of crescents on native biopsy is more likely to recur after transplant.

Recent advances in our understanding of recurrent primary glomerulonephritis after kidney transplantation

Recurrent glomerulonephritis (GN) is an important cause of kidney allograft failure, particularly in younger recipients. Approximately 15% of death-censored graft failures are due to recurrent GN, but this incidence is likely an underestimation of the magnitude of the problem. Overall, 18% to 22% of kidney allografts are lost due to GN, either recurrent or presumed de novo. The impact of recurrent GN on allograft survival was recognized from the earliest times in kidney transplantation. However, progress in this area has been slow, and our understanding of GN recurrence remains limited, in large part due to incomplete understanding of the pathogenesis of these diseases. This review focuses on recent advances in our general understanding of the pathophysiology of primary GN, the risk of recurrence in the allograft, and the consequences for kidney graft survival. We focus specifically on the most common forms of primary GN, including focal segmental glomerulosclerosis, membranous nephropathy, membranoproliferative glomerulonephritis, and IgA nephropathy. New understanding of the pathogenesis of these diseases has had direct clinical implications for transplantation, allowing better identification of candidates at high risk of recurrence and earlier diagnoses, and it is expected to lead to significance improvements in the therapy and perhaps even prevention of GN recurrence. More than ever, it is essential to fully characterize GN before transplantation as this information will direct our management posttransplantation. Further, the relative rarity of recurrent GN dictates the need for multicenter studies in order to evaluate, test, and validate recent advances and therapies.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

Association between Human Leukocyte Antigens (HLA-A, -B, and -DR) and end-stage renal disease in Kuwaiti patients awaiting transplantation

The number of patients with end stage renal disease (ESRD) is increasing considerably worldwide. Human Leukocyte Antigens (HLAs) are relevant for the expression of many immunological diseases and contribute to the development of different nephropathies. Therefore, we aimed from the present work to investigate the possible association between the frequency of HLA-A, -B, and -DR antigens and ESRD in Kuwaiti patients awaiting renal transplant. HLA-A, -B, and -DR typing was performed by complement-dependent cytotoxicity (CDC) method for 334 patients with ESRD awaiting renal transplantation and 191 healthy controls. The frequency of HLA-B8 antigen was significantly higher in ESRD patients (OR = 2.62, p = 0.001, pc = 0.038), and the frequency of HLA-A28, HLA-DR11 antigens was significantly higher in healthy controls (OR 0.42, p = 0.0001; pc = 0.0021, and OR = 0.44, p = 0.0007, pc = 0.01 respectively). While the HLA-B8 antigen may be a susceptibility risk factor for development of ESRD, the HLA-A28, and HLA-DR11 antigens may be protective against development of ESRD in Kuwaiti population.

Prognostic factors for renal allograft survival in patients with immunoglobulin A nephropathy: a case control study

The renal allograft survival rates of patients with immunoglobulin A nephropathy (IgAN), and patients with or without other glomerular diseases, have yet to be fully elucidated. In this study, the clinicopathological factors associated with long-term allograft survival for the prognosis of renal allograft recipients with IgAN were examined. All patients enrolled in this study were diagnosed with IgAN following clinical and pathological examinations. Patients underwent renal graft biopsy and were hospitalized at the Fuzhou General Hospital between June, 2004 and December, 2010. Common demographic and clinical indicators were recorded in patients who had graft loss and in those who had functional renal grafts. Forty-two of the 202 biopsy specimens (20.8%) met the diagnostic criteria for IgAN and were divided into two groups, the graft loss group (n=17) and the functional graft group (n=25). Patients were followed up for 1-257 months after kidney transplantation. The mean patient age was 40.6 ± 9.3 years at the time of renal graft biopsy. Examination results indicated concomitant proteinuria and hematuria in 25 patients (59.5%) and proteinuria alone in six patients (14.3%). Graft loss occurred in 17 patients during the follow-up period. Comparison of the graft loss and the functional graft groups indicated that patients in the graft loss group were more likely to have proteinuria (P=0.047), high creatinine levels at the time of biopsy (P=0.009), low glomerular filtration rates (P=0.013), low serum total protein (P=0.01), a high Banff score (P=0.001), extensive glomerulosclerosis (P=0.002), a greater likelihood of crescent formation (P=0.01), severe tubular atrophy (P=0.013) and more extensive interstitial fibrosis (P=0.033). However, the two groups showed no significant differences in blood pressure, hematuria, BUN, UA, Hb, TG and CHO levels. The allograft survival rate of patients with IgAN was identified to be similar to that of patients with and without other glomerular diseases.

Recurrence of glomerulonephritis after renal transplantation

Recurrence of glomerulonephritis following renal transplantation is considered an important cause of allograft failure. The incidence of recurrence of glomerulonephritis varies widely depending on the definition of recurrence (pathologic recurrence or clinicopathologic recurrence) and the original glomerular disease. Moreover the impact of recurrence of glomerular disease on allograft outcome varies widely between different forms of glomerulonephritis. Whereas IgA nephritis recurs in up to one third of transplanted patients, this is not associated with adverse effects on graft survival. In contrast, recurrent focal segmental glomerulosclerosis and membranoproliferative glomerulopathy have an unfavorable prognosis. Overall, long-term graft survival in patients transplanted for glomerulonephritis is comparable to survival in patients with other causes of ESRD. In recent years, several mechanisms for recurrent disease after transplantation (e.g. PLA2R antibodies in membranous nephropathy and suPAR in FSGS) have been identified, and these findings have helped to elucidate the pathogenesis of glomerular diseases. Although renal transplantation is the treatment of choice for end-stage renal disease as a consequence of glomerulonephritis, further studies are required to develop optimal strategies to prevent, diagnose and treat recurrent glomerular diseases.

Impact of graft loss among kidney diseases with a high risk of post-transplant recurrence in the paediatric population

BACKGROUND

Some kidney diseases tend to recur in the renal allograft after transplantation. We studied the risk of graft loss among primary renal diseases known for their high risk of recurrence and compared it with that of patients with hypoplasia and/or dysplasia.

METHODS

Within the European Society of Paediatric Nephrology and European Renal Association and European Dialysis and Transplant Association (ESPN/ERA-EDTA) registry, we studied children from 33 countries who received a kidney transplant before the age of 20 between 1990 and 2009. Patients were censored after 5 years of follow-up and cumulative incidence competing risk analysis was used to calculate survival curves.

RESULTS

Patients with focal and segmental glomerulosclerosis (FSGS), haemolytic uraemic syndrome (HUS), membranoproliferative glomerulonephritis Type I or II (MPGN), IgA nephropathy or Henoch Schönlein Purpura (HSP/IgA) or systemic lupus erythomatosus (SLE) underwent pre-emptive transplantation significantly less often than patients with hypoplasia and/or dysplasia. The rate of living donation was lower among patients with FSGS and SLE than in patients with hypoplasia and/or dysplasia. In comparison with hypoplasia and/or dysplasia patients with a risk of 14.4%, the 5-year risk of graft loss was significantly increased in patients with FSGS (25.7%) and MPGN (32.4%) while it was not significantly increased in children with HUS (18.9%), HSP/IgA (16.3%) or SLE (20.3%). One-year graft survival strongly improved among HUS patients from 17.1% in 1995-1999 to 3.6% in 2005-2009 and was not accompanied by a decrease in the number of transplantations.

CONCLUSION

The risk of graft loss is increased among specific causes of renal failure with a high risk of post-transplant recurrence. It seems likely that, due to anticipation of such risk, physicians perform less pre-emptive transplantation and provide fewer grafts from living related donors in patients with these conditions. Improved risk stratification by physicians, resulting in the identification of patients with HUS at higher or lower risk of recurrence, might explain the much improved graft survival rates.

Posttransplant recurrence of primary glomerulonephritis

All forms of primary GN may recur after kidney transplantation and potentially jeopardize the survival of the graft. IgA nephritis (IgAN) may recur in approximately one third of patients, more frequently in younger patients and in those with a rapid progression of the original disease. However, with the exception of few patients with rapid progression, there is no evidence that recurrence of IgAN has a deleterious effect on graft survival at least up to 10 years. Recurrence of focal segmental glomerulosclerosis (FSGS) is often associated with nephrotic proteinuria and is more frequent in children, in patients with rapid progression of the original disease, and in those who lost a previous transplant from recurrence. The natural course of recurrent FSGS is usually unfavorable. Early and intensive plasmapheresis may obtain complete or partial response in several patients. Good results have also been reported with rituximab. Idiopathic membranous nephropathy (IMN) may recur in 30% to 40% of patients. The graft survival in patients with IMN is not different than that of patients with other renal diseases. Good results with rituximab have been reported. Membranoproliferative GN (MPGN) may recur in 27% to 65% of patients. The recurrence is more frequent and the prognosis is more severe in type II MPGN. Although recurrent GN is relatively frequent and may worsen the outcome of renal allografts in some patients, its effect is diluted by several other risk-factors that may have a greater effect than recurrent GN on the long-term graft survival.