Glomerular crescents are associated with worse graft outcome in allograft IgA nephropathy

Post-transplant glomerular diseases: update on pathophysiology, risk factors and management strategies

In recent years, advancements in immunosuppressive medications and post-transplant management have led to a significant decrease in acute rejection rates in renal allografts and consequent improvement in short-term graft survival. In contrast, recent data have shown an increased incidence of post-transplant glomerular diseases, which currently represent a leading cause of allograft loss. Although pathogenesis is not fully understood, growing evidence supports the role of inherited and immunological factors and has identified potential pre- and post-transplant predictors. In this review, we illustrate recent advancements in the pathogenesis of post-transplant glomerular disease and the role of risk factors and immunological triggers. In addition, we discuss potential prevention and management strategies.

Tubulo-interstitial inflammation increases the risk of graft loss after the recurrence of IgA nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is the most frequent recurrent disease in kidney transplant recipients and its recurrence contributes to reducing graft survival. Several variables at the time of recurrence have been associated with a higher risk of graft loss. The presence of clinical or subclinical inflammation has been associated with a higher risk of kidney graft loss, but it is not precisely known how it influences the outcome of patients with recurrent IgAN.

Methods

We performed a multicentre retrospective study including kidney transplant recipients with biopsy-proven recurrence of IgAN in which Banff and Oxford classification scores were available. 'Tubulo-interstitial inflammation' (TII) was defined when 't' or 'i' were ≥2. The main endpoint was progression to chronic kidney disease (CKD) stage 5 or to death censored-graft loss (CKD5/DCGL).

Results

A total of 119 kidney transplant recipients with IgAN recurrence were included and 23 of them showed TII. Median follow-up was 102.9 months and 39 (32.8%) patients reached CKD5/DCGL. TII related to a higher risk of CKD5/DCGL (3 years 18.0% vs 45.3%, log-rank 7.588, P = .006). After multivariate analysis, TII remained related to the risk of CKD5/DCGL (HR 2.344, 95% CI 1.119-4.910, P = .024) independently of other histologic and clinical variables.

Conclusions

In kidney transplant recipients with IgAN recurrence, TII contributes to increasing the risk of CKD5/DCGL independently of previously well-known variables. We suggest adding TII along with the Oxford classification to the clinical variables to identify recurrent IgAN patients at increased risk of graft loss who might benefit from intensified immunosuppression or specific IgAN therapies.

Clinical and Pathological Significance of Mesangial C1q Deposition in Kidney Transplant Recipients with Recurrent IgA Nephropathy and Patients with Native IgA Nephropathy

INTRODUCTION

In kidney transplant recipients (KTRs) whose primary disease is IgA nephropathy (IgAN), IgAN recurrence occurs in approximately half of patients by 5 years postoperatively and is associated with graft survival. Although the alternative and lectin pathways are important in the primary pathogenesis of IgAN, the significance of mesangial C1q deposition, which triggers the classical pathway, is unknown. We investigated the clinicopathological significance of mesangial C1q deposition in both recurrent IgAN in KTRs and native IgAN.

METHODS

Between 2000 and 2021, we conducted a 1:2 matched case-control study of 18 KTRs diagnosed with recurrent IgAN, with a group of native IgAN patients as the control. We evaluated the rate and presence/absence of mesangial C1q deposition in terms of pathological findings and kidney outcomes in each group.

RESULTS

The rate of mesangial C1q deposition was significantly higher in the recurrent IgAN patients in KTRs than in native IgAN patients (11/18 [61.1%] vs. 5/36 [13.9%], p = 0.001). In the former group, the incidence of glomerular crescents was relatively higher in C1q-positive patients. There was no significant difference in the annual rate of estimated glomerular filtration rate decline between C1q-positive and C1q-negative patients in either group.

CONCLUSION

Mesangial C1q deposition was more frequent in KTRs with recurrent IgAN than in patients with native IgAN, but we found no difference in kidney outcomes with respect to mesangial C1q deposition. Further large-scale investigations of the importance of mesangial C1q deposition are needed in both KTRs with recurrent IgAN and patients with native IgAN.

Recurrent glomerulonephritis after kidney transplantation: a practical approach

PURPOSE OF REVIEW

This review will provide a practical approach in the assessment of kidney failure patients with primary glomerulonephritides (GN) being considered for kidney transplantation, focusing on high-risk subtypes of immunoglobulin A nephropathy, focal segmental glomerulosclerosis, idiopathic membranous glomerulonephritis and membranoproliferative glomerulonephritis.

RECENT FINDINGS

Recurrent glomerulonephritis remains one of the most common causes of allograft loss in kidney transplant recipients. Although the epidemiology and clinical outcomes of glomerulonephritis recurrence occurring after kidney transplantation are relatively well-described, the natural course and optimal treatment strategies of recurrent disease in kidney allografts remain poorly defined. With a greater understanding of the pathophysiology and treatment responses of patients with glomerulonephritis affecting the native kidneys, these discoveries have laid the framework for the potential to improve the management of patients with high-risk glomerulonephritis subtypes being considered for kidney transplantation.

SUMMARY

Advances in the understanding of the underlying immunopathogenesis of primary GN has the potential to offer novel therapeutic options for kidney patients who develop recurrent disease after kidney transplantation. To test the efficacy of novel treatment options in adequately powered clinical trials requires a more detailed understanding of the clinical and histological characteristics of kidney transplant recipients with recurrent glomerulonephritis.

A case of early recurrent immunoglobulin A nephropathy and T-cell-mediated rejection in a transplant patient with Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-chromosome recessive immunodeficiency disease characterized by the triad of thrombocytopenia, eczema, and susceptibility to infection owing to WAS protein gene abnormalities. Kidney transplantation is rarely offered to WAS patients with end-stage renal disease because of concerns that thrombocytopenia and immune disorders may affect the clinical outcome. Here, we report the case of a 20-year-old kidney transplant patient who developed end-stage renal disease owing to immunoglobulin (Ig)A nephropathy caused by WAS. Despite recurrent IgA nephropathy and T-cell-mediated rejection 7 months after transplantation, two rounds of steroid pulse therapy attenuated his renal function and urinary abnormality. His serum creatinine level was maintained at approximately 1.5 mg/dL 1 year after transplantation. No other WAS-related complications were observed throughout the clinical course. Although WAS can cause poor prognosis in kidney transplant patients, careful follow-up may allow kidney transplantation to be performed.

The glomerular crescent: triggers, evolution, resolution, and implications for therapy

PURPOSE OF REVIEW

Crescents are classical histopathological lesions found in severe forms of rapidly progressive glomerulonephritis, also referred to as crescentic glomerulonephritis (CGN). Crescent formation is a consequence of diverse upstream pathomechanisms and unraveling these mechanisms is of great interest for improving the management of patients affected by CGN. Thus, in this review, we provide an update on the latest insight into the understanding on how crescents develop and how they resolve.

RECENT FINDINGS

Cellular crescents develop from activated parietal epithelial cells (PECs) residing along Bowman's capsule and their formation has as a consequence the decline in glomerular filtration rate (GFR). Cellular crescents can be reversible, but when multilevel growth of PECs associate with an epithelial--mesenchymal transition-like change in cell phenotype, fibrous crescents form, and crescents become irreversible also in terms of GFR recovery. Different molecular pathways trigger the activation of PECs and are a prime therapeutics target in CGN. First, crescent formation requires also vascular injury causing ruptures in the glomerular basement membrane that trigger plasmatic coagulation within Bowman's space. This vascular necrosis can be triggered by different upstream mechanisms, such as small vessel vasculitides, immune complex glomerulonephritis, anti-GBM disease, and C3 glomerulonephritis, that all share complement activation but involve diverse upstream immune mechanisms outside the kidney accessible for therapeutic intervention.

SUMMARY

Knowing the upstream mechanisms that triggered crescent formation provides a tool for the development of therapeutic interventions for CGN.

Renal Outcomes in Brazilian Patients with Immunoglobulin A Nephropathy and Cellular Crescentic Lesions

BACKGROUND AND AIM

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulopathy. The Oxford classification was recently updated to include crescents as markers of poor prognosis. The aim of this study was to evaluate the impact of cellular crescents on the prognosis of patients with IgAN in Brazil.

METHODS

This was a single-centre retrospective analysis of medical records and renal biopsies in patients with IgAN. The renal biopsy findings were classified according to the revised Oxford classification: mesangial hypercellularity, endocapillary hypercellularity (E), segmental glomerulosclerosis (S), tubular atrophy or interstitial fibrosis (T), and crescent formation (C). We evaluated a composite outcome (progression to end-stage renal disease or creatinine doubling). We performed analyses between the patients with crescents in the renal biopsy specimen (C1/C2 group) and those without such crescents (C0 group).

RESULTS

We evaluated 111 patients, of whom 72 (65.0%) were women, 80 (72.0%) self-identified as White, 73 (65.6%) were hypertensive, and 95 (85.6%) had haematuria. The distribution of patients according to cellular crescentic lesions was: C0, 80 (72%); C1, 27 (24.4%); C2, 4 (3.6%). The composite outcome was observed in 33 (29.72%) of the 111 patients. In comparison with the C0 group, the C1/C2 group had higher proportions of patients with hypertension (p = 0.04), haematuria (p = 0.03), worse serum creatinine (p = 0.0007), and worse estimated glomerular filtration rate (p = 0.0007). The C1/C2 group also had higher proportions of patients in whom the biopsy specimen was classified as E1 (p = 0.009), S1 (p = 0.001), or T1/T2 (p = 0.03), In addition, the mean follow-up period was shorter in the C1/C2 group (p < 0.0001). Furthermore, the composite outcome was observed in a greater proportion of patients and in a shorter length of time in the C1/C2 group than in the C0 group (p = 0.002 and p = 0.0014, respectively). In a Cox regression analysis, the independent risk factors for the composite outcome had Oxford classifications of S1, T1/T2, and C1/C2.

CONCLUSION

Oxford classification findings of S1, T1/T2, or C1/C2 were independent risk factors for the composite outcome, corroborating previous studies.

IgA Nephropathy After Renal Transplant: Recurrences and De Novo Cases

IgA nephropathy (IgAN) recurrence in the renal graft is variable. Several factors can influence the risk of recurrence of IgAN and renal graft failure. We carried out a retrospective observational study between the years 1990 and 2018. The study group was patients diagnosed, by means of biopsy, as having post-renal transplant (RT) IgAN in our hospital in the study period. The control group was patients with pre-RT histologic diagnosis of IgAN who did not develop recurrence of the disease after the RT. A total of 1535 RTs were performed in our center in the study period. Of those, 24 patients developed IgAN in the renal graft. The time elapsed from the RT to the development of allograft IgAN was 7 (SD, 5.3) years. The patients with allograft IgAN tended to be younger (P = .069), and HLA-DR4 was more common in these patients (P = .078). We observed a very significant difference in the use of induction immunosuppressive therapy (study group vs control group: 13.6% vs 57.7%, P < .001). The 3 patients who presented crescents in the biopsy specimen lost the renal graft. As in the native kidney, the presence of crescents is an indicator of poor prognosis. In our experience, the patients with post-RT IgAN received induction therapy less frequently; this finding would support the conclusion that such treatments should be applied to patients with pre-RT diagnosis of IgAN.

Efficacy of corticosteroids in immunoglobulin A nephropathy with less than 25% crescents

BACKGROUND

Crescent formation in immunoglobulin A nephropathy (IgAN) has been demonstrated to be a risk factor for worse outcomes. For IgAN patients with 0-25% crescentic glomeruli (C1), whether corticosteroids (CS) can improve the prognosis remains unclear. We tried to investigate the need for using CS in IgAN patients with C1 in different proteinuria levels.

METHODS

A total of 120 eligible IgAN patients with C1 from two academic medical centers were retrospectively studied, and 57 (47.5%) received CS. Patients were grouped according to with or without CS. The outcomes were the rate of estimated glomerular filtration rate (eGFR) decline (ml/min per 1.73 m²/year) and a composite outcome (50% decrease in eGFR, end stage renal disease (ESRD) or death due to kidney disease). The progression of adverse outcome among them were analyzed in Kaplan-Meier curve. The independent significance of CS on renal outcome or eGFR decline rate were analyzed by multivariable Cox regression or linear regression.

RESULTS

Unadjusted Kaplan-Meier showed that the outcome of treated patients was better than that of the untreated patients. Multiple Cox regression and linear regression analysis found that CS independently protected the renal outcome and decreased the eGFR decline rate. In the subgroup analysis, multivariate linear regression showed that CS decreased the eGFR decline rate both in proteinuria ≥ 1 g/day and < 1 g/day.

CONCLUSIONS

CS protected the renal outcome and slowed the eGFR decline rate of IgAN patients with C1, it also decreased the eGFR decline rate even in those with initial proteinuria < 1 g/day.

Clinical importance of the updated Oxford classification in allograft IgA nephropathy

With the recent update to the Oxford classification for allograft IgA nephropathy (IgAN), additional investigations on the clinical significance of the updated components are warranted. We performed a retrospective cohort study at two tertiary hospitals. Kidney transplant recipients diagnosed with allograft IgAN were included in the study after additional review by specialized pathologists. We applied the updated Oxford classification and determined the MEST-C scores of the patients. The main study outcome was death-censored graft failure within 10 years after the establishment of allograft IgAN diagnosis and was assessed using the Cox regression analysis. Three hundred thirty-three allograft IgAN patients were reviewed: 100 patients with confirmed native IgAN and 233 patients with other, clinical, or unknown primary causes for end-stage renal disease (ESRD). The updated Oxford classification for allograft IgAN demonstrated prognostic value for graft failure, and patients with multiple MEST-C components had worse outcomes. M, E, S, and C were significantly associated with the prognosis of recurred IgAN and T was the only independent prognostic parameter for allograft IgAN without confirmed native IgAN. Therefore, we suggest reporting MEST-C scores in allograft biopsies and careful interpretation of the results according to the primary cause of ESRD.

Possible beneficial association between renin-angiotensin-aldosterone-system blockade usage and graft prognosis in allograft IgA nephropathy: a retrospective cohort study

BACKGROUND

Although immunoglobulin A nephropathy (IgAN) is associated with an increased risk of renal allograft failure, evidences for its treatment, including renin-angiotensin-aldosterone system blockade (RAASB) usage, remain limited.

METHODS

In this bi-center retrospective cohort study, we included patients who were recently diagnosed with IgAN through allograft biopsies. We identified their 6-month antihypertensive medication prescriptions and investigated the association between the medication types, albuminuria changes, and risk of 5-year death-censored-graft-failure (DCGF). The mixed effect model and cox regression analysis were used.

RESULTS

A total of 464 allograft IgAN patients were included: 272, 38, 33, and 121 patients in the no antihypertensive medication, single agent RAASB, single agent beta blocker (BB)/calcium channel blocker (CCB), and combination therapy groups, respectively. High-degree albuminuria after 6 months of allograft IgAN diagnosis was an important prognostic parameter and a partial mediator for the association between the subgroups and 5-year DCGF. The usage of single RAASB was associated with decrement of albuminuria from allograft IgAN diagnosis (P for interaction = 0.03). The single BB/CCB group demonstrated significantly worse prognosis than the single RAASB group (adjusted hazard ratio, 2.76 [1.09-6.98]; P = 0.03).

CONCLUSIONS

In conclusion, RAASB may be beneficial for graft prognosis in early allograft IgAN patients who require single antihypertensive medication therapy, by means of reducing albuminuria. Further investigation of treatment strategy in allograft IgAN is warranted.