Graft failure of IgA nephropathy in renal allografts following living donor transplantation: predictive factor analysis of 102 biopsies

Advancements in understanding the role of intestinal dysbacteriosis mediated mucosal immunity in IgA nephropathy

IgA nephropathy, presently recognized as the foremost primary glomerular disorder, emerges as a principal contributor to renal failure globally, with its pathogenesis yet to be fully elucidated. Extensive research has highlighted the critical role of gut microbiome in the onset and progression of IgA nephropathy, underscoring its importance in accurately delineating the disease's etiology. For example, gut microbiome dysbacteriosis can lead to the production of nephritogenic IgA1 antibodies, which form immune complexes that deposit in the kidneys, causing inflammation and damage. The gut microbiome, a source of numerous bioactive compounds, interacts with the host and plays a regulatory role in gut-immune axis modulation, earning it the moniker of the "second brain." Recent investigations have particularly emphasized a significant correlation between IgA nephropathy and gut microbiome dysbacteriosis. This article offers a detailed overview of the pathogenic mechanisms of IgA nephropathy, specifically focusing on elucidating how alterations in the gut microbiome are associated with anomalies in the intestinal mucosal system in IgA nephropathy. Additionally, it describes the possible influence of gut microbiome on recurrent IgA nephropathy following kidney transplantation. Furthermore, it compiles potential therapeutic interventions, offering both theoretical and practical foundations for the management of IgA nephropathy. Lastly, the challenges currently faced in the therapeutic approaches to IgA nephropathy are discussed.

Immunoglobulin A Deposits In Renal Allografts: A Prospective Longitudinal Single-Center Study

AIMS AND BACKGROUND

To describe the prevalence of IgA deposits (IgAD) in renal allografts in a cohort of renal transplant recipients and to analyze their management strategies and histopathology. To assess graft function and proteinuria after 1 year of follow-up.

MATERIALS AND METHODS

A prospective longitudinal follow-up study was carried out in VPS Lakeshore Hospital and Research Centre, Kochi, Kerala, over a period of 5 years (July 2015 to June 2020). Kidney transplant recipients with allograft biopsies that reported IgAD on immunofluorescence were included in the study. Light microscopy and immunofluorescence studies were performed. Mesangial hypercellularity (M); segmental glomerulosclerosis (S); endocapillary hypercellularity (E); tubular atrophy/interstitial fibrosis (T); crescents (C) (MEST-C) Scoring was done in patients with pathogenic IgAD. Treatment strategies included increased baseline steroid dosage, rituximab administration, and plasma exchange. Clinical details and management strategies were analyzed, and patients were followed up for 1 year after diagnosis. Changes in graft function (S. Creatinine) and proteinuria (Urine Protein/Creatinine ratio) were analyzed. Clinico-pathologic correlation with the MEST-C scores was also done.

RESULTS

Out of 1036 kidney transplants done in the study period, 760 graft biopsies were performed. Sixty-four cases had post-transplant deposition of IgA (8%). The mean age was 45 ± 11.25SD years. The study had 51 men and 13 women. Induction immunosuppression comprised rabbit antithymocyte globulin in 29 (45%) patients and basiliximab in 35 (54%). Maintenance immunosuppression in all comprised tacrolimus, mycophenolate mofetil, and steroids. There were 2 groups: group A (pathogenic IgAD) and group B (incidental IgAD). Group A had 46 cases (71.9%), out of which 8 had "active" IgA nephropathy (endocapillary proliferation, crescents, and IgA vasculitis), and 38 had "inactive" IgAD. In patients with active deposits, 3 had cellular crescents (18%, 30%, and 23%), all 8 had endocapillary proliferation, and 2 had vasculitis. Group B had 18 cases (28.1%), comprising T cell-mediated rejections (5), antibody-mediated rejection (8), BK virus nephropathy (1), and interstitial fibrosis and tubular atrophy (4). In group A, 22 (47.8%) presented with graft dysfunction, 8 (17.3%) with isolated proteinuria, and 14 (30.4%) patients presented with a combination. Two (4.3%) patients had neither. Fourteen (30.4%) patients presented within 1 month of renal transplant. In patients of group A, at the end of 1 year of treatment, the mean S. Creatinine reduced to 1.68 mg/dL from 1.84 mg/dL, and the mean protein/creatinine ratio reduced from 1.2 to 0.5 (±1.17). In patients with "active IgA" lesions, at the end of 1 year of treatment, the mean S. Creatinine increased slightly to 1.68 mg/dL (±0.47SD) from 1.48 mg/dL (±0.52SD), and the mean protein/creatinine ratio reduced from 2.32 (±1.56SD) to 1.05 (±1.70SD). In the 16 patients with IgAD and proteinuria, at the end of 1 year of treatment, the mean S. Creatinine decreased to 1.41 ± 0.32 SD mg/dL from 1.47±0.37SD mg/dL and the mean protein/creatinine ratio reduced from 1.12 ± 1.31 SD to 0.39±0.75 SD. In the remaining 22 patients with acute tubular injury, at the end of 1 year, the mean S. Creatinine decreased to 1.920.32 SD mg/dL from 2.10.8SD mg/dL, and the mean protein/creatinine ratio reduced from 1.1 ± 1.31 SD to 0.66 ± 1.45 SD. In the MEST-C scoring analysis, all scores were 0 in 20 (43.4%) biopsies, only M1 score in 11 (23.9%) biopsies, only E1 score in 10 biopsies (21.7%), S1 in 13 (28.2%) cases.

CONCLUSION

Immunoglobulin A deposits occur commonly after transplant; these may represent recurrence, de novo IgA, or donor-derived IgAD. Although commonly benign, some may cause significant graft dysfunction and graft loss. IgAD can present as varying combinations of graft dysfunction and proteinuria. Active IgA pathologies may occur early in the post-transplant course, may have significant graft dysfunction, and need proactive management. There is a correlation between segmental sclerosis and proteinuria. Evidence for the efficacy of Rituximab, plasma exchange, and prolonged courses of steroids is wanting; however, some benefits are possible. Long-term follow-up is essential.

A novel prognostic nomogram predicts premature failure of kidney allografts with IgA nephropathy recurrence

BACKGROUND

Recurrence of immunoglobulin A nephropathy (IgAN) limits graft survival in kidney transplantation. However, predictors of a worse outcome are poorly understood.

METHODS

Among 442 kidney transplant recipients (KTRs) with IgAN, 83 (18.8%) KTRs exhibited biopsy-proven IgAN recurrence between 1994 and 2020 and were enrolled in the derivation cohort. A multivariable Cox model predicting allograft loss based on clinical data at the biopsy and a web-based nomogram were developed. The nomogram was externally validated using an independent cohort (n = 67).

RESULTS

Patient age <43 years {hazard ratio [HR] 2.20 [95% confidence interval (CI) 1.41-3.43], P < .001}, female gender [HR 1.72 (95% CI 1.07-2.76), P = .026] and retransplantation status [HR 1.98 (95% CI 1.13-3.36), P = .016] were identified as independent risk factors for IgAN recurrence. Patient age <43 years [HR 2.77 (95% CI 1.17-6.56), P = .02], proteinuria >1 g/24 hours [HR 3.12 (95% CI 1.40-6.91), P = .005] and C4d positivity [HR 2.93 (95% CI 1.26-6.83), P = .013] were found to be associated with graft loss in patients with IgAN recurrence. A nomogram predicting graft loss was constructed based on clinical and histological variables, with a C statistic of 0.736 for the derivation cohort and 0.807 for the external validation cohort.

CONCLUSIONS

The established nomogram identified patients with recurrent IgAN at risk for premature graft loss with good predictive performance.

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.

Early Recurrence of Immunoglobulin A Nephropathy after Kidney Transplantation in a Patient with Down Syndrome

A 39-year-old male kidney transplant recipient with Down syndrome (DS) was admitted to our hospital for biopsy. He had proteinuria at age 9, was diagnosed with immunoglobulin A nephropathy (IgAN) at age 22, had a tonsillectomy at age 35, and underwent ABO-compatible kidney transplantation (from his mother) at age 36. His serum creatinine was stable at 2.21 mg/dL 3 months after the kidney transplant, and his urine protein was 0.11 g/day. A protocol biopsy was performed 7 months after the kidney transplant, and there was suspicion of early recurrence of IgAN. One year after the transplant, urine erythrocytes were elevated and proteinuria was 0.41 g/day; at 3 years and 5 months after the kidney transplant, hematuria was evident along with proteinuria (0.74 g/day). Therefore, an episode biopsy was performed. A total of 23 glomeruli were obtained, four of which exhibited global sclerosis; three others showed intra- and extracapillary proliferative glomerulonephritis compatible with IgAN recurrence. Here, we report a rare case of early recurrence of IgAN with disease progression despite tonsillectomy in a patient with DS.

Current Status and Perspectives on Recurrent IgA Nephropathy after Kidney Transplantation

IgA nephropathy (IgAN) is the most common form of glomerulonephritis worldwide. IgAN progresses to end-stage kidney disease in 20-40% of patients within 20 years of diagnosis. Kidney transplantation is the most effective option for patients with end-stage kidney disease caused by IgAN, but recurrence can occur in the transplanted kidney. The IgAN recurrence rate varies from 1% to 10% per year and varies according to the follow-up period, diagnostic modality, and biopsy criteria. Of note, studies based on protocol biopsies have reported a higher incidence of recurrence, which also occurred earlier after transplantation. In addition, recent data show that recurrence of IgAN is a more significant cause of allograft failure than previously believed. Little is known about the pathophysiology of IgAN recurrence, but several potential biomarkers have been investigated. Among them, galactose-deficient IgA1 (Gd-IgA1), IgG anti-Gd-IgA1 antibodies, and soluble CD89 could play a pivotal role in disease activity. This review aims to describe the current status of recurrent IgAN, including the incidence, clinical characteristics, risk factors, and future perspectives, with a focus on the available therapeutic approaches.

Color Doppler Ultrasound and Hemodynamics for Evaluating Graft Dysfunction in Recurrent Immunoglobulin A Nephropathy

BACKGROUND The aim of this study was to investigate the diagnostic and prognostic utility of color Doppler ultrasound for graft dysfunction in recurrent immunoglobulin A nephropathy (IgAN). MATERIAL AND METHODS We selected a series of 78 biopsies diagnostic of recurrent IgAN following living-donor transplantation from July 2004 to January 2019. Based on Lee's classification, Doppler parameters in different degrees of histopathological injury were retrospectively analyzed. RESULTS The 4-year cumulative graft survival rate after biopsy was 66.3%, and the difference among the Kaplan-Meier curves of Lee's classification (P<0.01) was significant. Doppler parameters showed that echo enhancement, decreasing blood flow distribution, decreasing end-diastolic velocity (EDV) of the main renal artery (MRA), segmental renal atery (SRA) and interlobar renal artery (IRA), and an elevated resistance index (RI) of the arcuate renal artery (ARA) were significantly different among grades I-V of Lee's classification (P<0.05). Logistic multivariate analysis indicated that echo enhancement (HR 13.6, 95% CI 2.7-68.4) and decreasing EDV of the SRA (HR 1.1 for a 1-cm/s, 95% CI 1.0-1.2) were independent predictors of severe injury (IV-V). The ROC curve fitted by echo enhancement and decreasing EDV of the SRA had an area under the curve of 0.87. The cutoff was 17.5 cm/s (decreasing EDV of the SRA) without echo enhancement. The sensitivity and specificity were 72.2% and 91.7%, respectively. CONCLUSIONS Color Doppler ultrasound successfully evaluated the graft dysfunction in recurrent IgAN; a decreasing EDV of the SRA indicated severe histopathological injury and poor prognosis.