Recurrent and de novo glomerular disease after renal transplantation: a report from renal allograft disease registry

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.

Deriving and understanding the risk of post-transplant recurrence of nephrotic syndrome in the light of current molecular and genetic advances

After renal transplantation, recurrence of the original disease is the second most common cause of graft loss, after rejection. The most dramatic manifestation of this phenomenon is in patients with nephrotic syndrome (NS). NS is a descriptive term describing a clinical picture centred on proteinuria arising from damage to the glomerular filtration barrier (GFB). There are many different drivers of that damage, ranging from immune dysregulation to genetic disorders and chronic disease/infections. The main categories in childhood are "idiopathic" (presumed immune mediated) and genetic NS, with further stratification of the idiopathic group according to steroid responses. A significant proportion of patients with NS progress to established renal failure, requiring transplantation, and one of the most difficult clinical scenarios faced by nephrologists is the recurrence of the original disease in up to 50% of patients, usually rapidly post-transplant. This is thought to be the archetypal "circulating factor" disease, in which as yet unknown circulating plasma "factor(s)" in the recipient target the donor kidney. The ability to predict in advance which patients will suffer recurrence would enhance our ability to counsel patients and families, and potentially identify those patients before transplant for tailored immunosuppressive preparation. Until very recently, stratification based on clinical categorisations has been poor in being able to predict those patients in whom disease will recur, and laboratory biomarkers are yet to be adequately refined. However, by mapping our growing understanding of disease mechanisms to clinical phenotypes, and with greatly improved genetic diagnostics, we have made progress in being able to stratify patients more specifically, and allow better predictive algorithms to be developed. Using our knowledge of podocyte biology, circulating factor-induced specific biomarkers are also being tested. This review is aimed at outlining those advances, and suggesting how we can move further forward in both clinical and biological markers of disease type.

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.

A reassessment of soluble urokinase-type plasminogen activator receptor in glomerular disease

It has been suggested that soluble urokinase receptor (suPAR) is a causative circulating factor for and a biomarker of focal and segmental glomerulosclerosis (FSGS). Here we undertook validation of these assumptions in both mouse and human models. Injection of recombinant suPAR in wild-type mice did not induce proteinuria within 24 hours. Moreover, a disease phenotype was not seen in an inducible transgenic mouse model that maintained elevated suPAR concentrations for 6 weeks. Plasma and urine suPAR concentrations were evaluated as clinical biomarkers in 241 patients with glomerular disease from the prospective, longitudinal multi-center observational NEPTUNE cohort. The serum suPAR concentration at baseline inversely correlated with estimated glomerular filtration rate (eGFR) and the urine suPAR/creatinine ratio positively correlated with the urine protein/creatinine ratio. After adjusting for eGFR and urine protein, neither the serum nor urine suPAR level was an independent predictor of FSGS histopathology. A multivariable mixed-effects model of longitudinal data evaluated the association between the change in serum suPAR concentration from baseline with eGFR. After adjusting for baseline suPAR concentration, age, gender, proteinuria and time, the change in suPAR from baseline was associated with eGFR, but this association was not different for patients with FSGS as compared to other diagnoses. Thus, these results do not support a pathological role for suPAR in FSGS.

Long-term cyclophosphamide treatment for recurrent type I membranoproliferative glomerulonephritis after transplantation

The incidence of recurrent type I membranoproliferative glomerulonephritis (MPGN) after renal transplant is approximately 30%, and the rate of graft loss due to recurrent MPGN type I is higher than 50%. The treatment of this disease has not been defined. We report a case of recurrent MPGN type diagnosed 4 months after a cadaveric renal transplantation. The patient was treated with cyclophosphamide and was able to maintain her graft function. Cyclophosphamide was interrupted three times during the course. Each time her renal function deteriorated and her serum albumin decreased. The patient currently has a functional renal graft 3 years after transplantation while receiving low-dose therapy with cyclophosphamide. We suggest treating recurrent type I MPGN with cyclophosphamide while continuing the calcineurin inhibitor and prednisone.