Utility of Oxford Classification in Post-Transplant Immunoglobulin A Nephropathy

Advancing the application of the analytical renal pathology system in allograft IgA nephropathy patients

BACKGROUND

The analytical renal pathology system (ARPS) based on convolutional neural networks has been used successfully in native IgA nephropathy (IgAN) patients. Considering the similarity of pathologic features, we aim to evaluate the performance of the ARPS in allograft IgAN patients and broaden its implementation.

METHODS

Biopsy-proven allograft IgAN patients from two different centers were enrolled for internal and external validation. We implemented the ARPS to identify glomerular lesions and intrinsic glomerular cells, and then evaluated its performance. Consistency between the ARPS and pathologists was assessed using intraclass correlation coefficients. The association of digital pathological features with clinical and pathological data was measured. Kaplan-Meier survival curve and cox proportional hazards model were applied to investigate prognosis prediction.

RESULTS

A total of 56 biopsy-proven allograft IgAN patients from the internal center and 17 biopsy-proven allograft IgAN patients from the external center were enrolled in this study. The ARPS was successfully applied to identify the glomerular lesions (F1-score, 0.696-0.959) and quantify intrinsic glomerular cells (F1-score, 0.888-0.968) in allograft IgAN patients rapidly and precisely. Furthermore, the mesangial hypercellularity score was positively correlated with all mesangial metrics provided by ARPS [Spearman's correlation coefficient (r), 0.439-0.472, and all p values < 0.001]. Besides, a higher allograft survival was noticed among patients in the high-level groups of the maximum and ratio of endothelial cells, as well as the maximum and density of podocytes.

CONCLUSION

We propose that the ARPS could be implemented in future clinical practice with outstanding capability.

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.

Indian scenario of IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

IgA nephropathy (IgAN) is most common primary glomerulopathy. There are variations in prevalence of IgAN and its clinical features in different studies from India.

AIM

To summarize overall scenario of IgAN in India.

METHODS

In this systematic review, studies related to IgAN and related renal disease were included. Data searched were PubMed, EMBASE, Google scholar, and Cochrane Database from inception to 31st January 2019.

RESULTS

Total 49 studies (N=2480) were included: 21 studies (N=2309) of primary IgAN; 19 studies (N=21) of Secondary IgAN; four studies (N=133) of IgA vasculitis nephropathy (IgAVN); and five studies (N=17) of IgA dominant nephropathy (IgADN). Prevalence of IgAN was 16.5% in India. Age of affected persons was ranging from 27.2±16.7 to 48.6±21.3 years . Male female ratio was 1.8:1. Clinical features of Primary IgAN, IgAVN, IgADN & Secondary IgAN were microscopic hematuria (49.6%, 44.4%, 15.6% & 59.5%), macroscopic hematuria (5.1%, 0.4%,40.9%,& 35.7%), Subnephrotic proteinuria (42.1%, 29.4%, 23.2%, & 52.3%), nephrotic proteinuria (16.0%, 4.4%, 76.8%,& 47.6%), and hypertension (25.8%,18.3%, 35.5%,& 47.6%).. The 24 hours proteinuria was ranging from 2.6±1.5 to 4.7±2.3 gm/day and serum creatinine (mg/dl) was ranging from 0.9±0 to 3.5±3.9 mg/dl. Histolomorphologically, all type of IgAN showed mesangial hypercellularity and Immunofluorescence revealed IgA deposition..

CONCLUSION

The overall prevalence of primary IgAN in India was 16.5%. The subnephrotic proteinuria and microscopic hematuria were common clinical features.