A Multicenter Study of the Predictive Value of Crescents in IgA Nephropathy

Podocyte injury as a potential therapeutic target in IgA nephropathy: should pathology guide us?

The Oxford histopathologic classification (MEST-C: scores for lesions indicating active glomerular inflammation, mesangial [M] and endocapillary [E] hypercellularity as well as cellular or fibrocellular crescents [C], and for segmental glomerulosclerosis [S] and interstitial fibrosis and/or tubular atrophy [T]) is useful in helping assess prognosis in patients with IgA nephropathy. Elements of this classification indicative of active glomerular inflammation, endocapillary hypercellularity and crescents, also have been found to be responsive to immunosuppressive therapy, potentially including newer agents specifically targeting mediators of such inflammation. In this issue of Kidney International, Bellur and coworkers identify histopathologic subtypes of segmental glomerulosclerosis in IgA nephropathy showing podocyte injury that also behave like active lesions, including showing improved outcomes with immunosuppression. This podocyte injury, identifiable only by kidney biopsy, may represent a potential therapeutic target in some patients with IgA nephropathy.

IgA vasculitis nephritis: insights from kidney biopsies

PURPOSE OF REVIEW

To present findings indicating the value of kidney biopsy in assessing prognosis and guiding clinical approach to patients with IgA vasculitis nephritis (IgAVN), including a recent international study examining the value of the Oxford (MEST-C) classification.

RECENT FINDINGS

Historically, kidney biopsies with IgAVN are scored using the International Society for Kidney Diseases in Children (ISKDC) classification. However, this classification has limited prognostic value, and most biopsies fall into just two of the six ISKDC grades. There are few studies examining the clinical value of the Oxford classification, which is well documented to be predictive of kidney outcomes in IgA nephropathy, in IgAVN. However, a recent study of 361 biopsied patients with IgAVN showed that endocapillary hypercellularity (Oxford E1) predicted a subclass of patients showing initial improvement in kidney function with immunosuppressive treatment, followed by a later decline.

SUMMARY

Kidney outcome in patients with biopsied IgAVN treated with immunosuppression is determined by clinical factors and endocapillary hypercellularity. The latter is not part of the ISKDC classification and supports including MEST-C scores in biopsy reports of IgAVN. Even patients showing a good initial response to immunosuppression require long-term follow-up due to risk of subsequent kidney function decline.

Artificial intelligence assists identification and pathologic classification of glomerular lesions in patients with diabetic nephropathy

BACKGROUND

Glomerular lesions are the main injuries of diabetic nephropathy (DN) and are used as a crucial index for pathologic classification. Manual quantification of these morphologic features currently used is semi-quantitative and time-consuming. Automatically quantifying glomerular morphologic features is urgently needed.

METHODS

A series of convolutional neural networks (CNN) were designed to identify and classify glomerular morphologic features in DN patients. Associations of these digital features with pathologic classification and prognosis were further analyzed.

RESULTS

Our CNN-based model achieved a 0.928 F1-score for global glomerulosclerosis and 0.953 F1-score for Kimmelstiel-Wilson lesion, further obtained a dice of 0.870 for the mesangial area and F1-score beyond 0.839 for three glomerular intrinsic cells. As the pathologic classes increased, mesangial cell numbers and mesangial area increased, and podocyte numbers decreased (p for all < 0.001), while endothelial cell numbers remained stable (p = 0.431). Glomeruli with Kimmelstiel-Wilson lesion showed more severe podocyte deletion compared to those without (p < 0.001). Furthermore, CNN-based classifications showed moderate agreement with pathologists-based classification, the kappa value between the CNN model 3 and pathologists reached 0.624 (ranging from 0.529 to 0.688, p < 0.001). Notably, CNN-based classifications obtained equivalent performance to pathologists-based classifications on predicting baseline and long-term renal function.

CONCLUSION

Our CNN-based model is promising in assisting the identification and pathologic classification of glomerular lesions in DN patients.

Circulating soluble CD30 is associated with renal tertiary lymphoid structures and the progression of IgA nephropathy

BACKGROUND

Renal tertiary lymphoid structures (TLSs) are involved in renal pathology and prognosis of IgA nephropathy (IgAN). CD30 and its ligands participate in the formation of renal TLSs. However, the relationship between circulating CD30 and renal prognosis is unclear. The objective of this study was to evaluate the relationship between circulating CD30 and prognosis in patients with IgAN.

METHODS

We conducted a retrospective study including 351 patients with biopsy proved IgAN. We collected clinical and pathologic features at the time of biopsy and recorded renal follow-up outcomes. Circulating CD30 levels in IgAN patients at the time of biopsy were measured via enzyme-linked immunosorbent assay (ELISA). The association between elevated CD30 levels and the composite endpoint (defined as a ≥ 50 % decline in eGFR from baseline, end-stage renal disease, or death) was investigated using Cox regression analysis.

RESULTS

During a median follow-up period of 5.12 years, 44 (12.5 %) patients in the cohort reached the composite endpoint. Kaplan-Meier survival curve analysis revealed a significant association between higher circulating CD30 levels and a poorer renal prognosis (log-rank P < 0.001). Cox regression analysis showed that high CD30 was an independent factor for the composite endpoints in multivariable-adjusted models (HR 3.397, 95 % CI: 1.230-9.384, P = 0.018). These associations were also observed in a subgroup of patients with concomitant renal TLSs formation (10.443, 95 % CI: 1.680-65.545, P = 0.012), proteinuria > 1 g/d (HR 12.287, 95 % CI: 1.499-100.711, P = 0.019), and female patients (HR 22.372, 95 % CI: 1.797-278.520, P = 0.016).

CONCLUSION

Elevated level of circulating CD30 is an independent risk factor for renal disease progression in patients with IgAN.

Histologic and Clinical Factors Associated with Kidney Outcomes in IgA Vasculitis Nephritis

BACKGROUND

Nephritis is a common manifestation of IgA vasculitis and is morphologically indistinguishable from IgA nephropathy. While MEST-C scores are predictive of kidney outcomes in IgA nephropathy, their value in IgA vasculitis nephritis has not been investigated in large multiethnic cohorts.

METHODS

Biopsies from 262 children and 99 adults with IgA vasculitis nephritis ( N =361) from 23 centers in North America, Europe, and Asia were independently scored by three pathologists. MEST-C scores were assessed for correlation with eGFR/proteinuria at biopsy. Because most patients ( N =309, 86%) received immunosuppression, risk factors for outcomes were evaluated in this group using latent class mixed models to identify classes of eGFR trajectories over a median follow-up of 2.7 years (interquartile range, 1.2-5.1). Clinical and histologic parameters associated with each class were determined using logistic regression.

RESULTS

M, E, T, and C scores were correlated with either eGFR or proteinuria at biopsy. Two classes were identified by latent class mixed model, one with initial improvement in eGFR followed by a late decline (class 1, N =91) and another with stable eGFR (class 2, N =218). Class 1 was associated with a higher risk of an established kidney outcome (time to ≥30% decline in eGFR or kidney failure; hazard ratio, 5.84; 95% confidence interval, 2.37 to 14.4). Among MEST-C scores, only E1 was associated with class 1 by multivariable analysis. Other factors associated with class 1 were age 18 years and younger, male sex, lower eGFR at biopsy, and extrarenal noncutaneous disease. Fibrous crescents without active changes were associated with class 2.

CONCLUSIONS

Kidney outcome in patients with biopsied IgA vasculitis nephritis treated with immunosuppression was determined by clinical risk factors and endocapillary hypercellularity (E1) and fibrous crescents, which are features that are not part of the International Study of Diseases of Children classification.

Identification of inflammatory biomarkers in IgA nephropathy using the NanoString technology: a validation study in Caucasians

OBJECTIVE AND DESIGN

Immunoglobulin A nephropathy (IgAN) is a kidney disease characterized by the accumulation of IgA deposits in the glomeruli of the kidney, leading to inflammation and damage to the kidney. The inflammatory markers involved in IgAN remain to be defined. Gene expression analysis platforms, such as the NanoString nCounter system, are promising screening and diagnostic tools, especially in oncology. Still, their role as a diagnostic and prognostic tool in IgAN remains scarce. In this study, we aimed to validate the use of NanoString technology to identify potential inflammatory biomarkers involved in the progression of IgAN.

SUBJECTS

A total of 30 patients with biopsy-proven IgAN and 7 cases of antineutrophil cytoplasmic antibody (ANCA)-associated pauci-immune glomerulonephritis were included for gene expression measurement. For the immunofluorescence validation experiments, a total of 6 IgAN patients and 3 controls were included.

METHODS

Total RNA was extracted from formalin-fixed paraffin-embedded kidney biopsy specimens, and a customized 48-plex human gene CodeSet was used to study 29 genes implicated in different biological pathways. Comparisons in gene expression were made between IgAN and ANCA-associated pauci-immune glomerulonephritis patients to delineate an expression profile specific to IgAN. Gene expression was compared between patients with low and moderate risk of progression. Genes for which RNA expression was associated with disease progression were analyzed for protein expression by immunofluorescence and compared with controls.

RESULTS

IgAN patients had a distinct gene expression profile with decreased expression in genes IL-6, INFG, and C1QB compared to ANCA patients. C3 and TNFRSF1B were identified as potential biomarkers for IgAN progression in patients early in their disease course. Protein expression for those 2 candidate genes was upregulated in IgAN patients compared to controls. Expression of genes implicated in fibrosis (PTEN, CASPASE 3, TGM2, TGFB1, IL2, and TNFRSF1B) was more pronounced in IgAN patients with severe fibrosis compared to those with none.

CONCLUSIONS

Our findings validate our NanoString mRNA profiling by examining protein expression levels of two candidate genes, C3 and TNFRSF1B, in IgAN patients and controls. We also identified several upregulated mRNA transcripts implicated in the development of fibrosis that may be considered fibrotic markers within IgAN patients.

IgA nephropathy in children with minimal proteinuria: to biopsy or not to biopsy?

BACKGROUND

Tubulointerstitial lesions and glomerular inflammation severity have been shown to correlate with proteinuria in children with IgA nephropathy (cIgAN). However, there is a lack of data regarding severity of histopathologic findings in cIgAN in patients with minimal to absent proteinuria since kidney biopsy indications are not well defined in these cases.

METHODS

Twenty-eight cIgAN patients with kidney biopsy from 4 different centers in Paris (France) and Montreal (Canada) with a urine protein/creatinine ratio (UPCr) ≤ 0.03 g/mmol and a normal estimated glomerular filtration rate (eGFR > 90 ml/min/1.73 m2) on the day of kidney biopsy prior to treatment were included.

RESULTS

Median age was 11.82 (9.32-13.45) years, and median follow-up was 4 years (2.87-6.53). At time of biopsy, median eGFR was 116 (102.3-139.7) ml/min/1.73 m2, and median UPCr was 0.02 (0.011-0.03) g/mmol. Microscopic or macroscopic hematuria was present in 35.7% and 64.3% of cases, respectively. Kidney biopsy microscopy analysis showed mesangial (M1), endocapillary (E1), or extracapillary (C1) hypercellularity in 53.5%, 32.1%, and 7.1% of patients, respectively. Chronic histological lesions were also present: glomerulosclerosis (S1) in 42.8% and tubular atrophy/interstitial fibrosis in 7.1%. Podocytopathic features were detected in 21.4%. An ACE inhibitor or immunosuppressive therapy (IS) was prescribed in 42.8% and 21.4% of these patients respectively. One-third (35.7%) received no treatment. At last follow-up, median eGFR was 111.9 (90.47-136.1) ml/min/1.73 m2, and median UPCr was 0.028 (0.01-0.03) g/mmol.

CONCLUSION

cIgAN with minimal proteinuria at time of biopsy might be linked with acute and chronic glomerular lesions.

The relationship between histopathological features, immunosuppression and outcome in patients undergoing native kidney biopsies

AIMS

To assess retrospectively the association between histopathological lesions on renal biopsy and subsequent impairment of renal function across the spectrum of kidney diseases and to explore the influence of immunosuppressive therapy within the first 6 months after biopsy on this association.

METHODS AND RESULTS

Clinical data from 488 adult patients having a renal biopsy reported at a single centre from 2017 to 2019 were obtained during a median follow-up period of 786 days. Seventeen semi-quantitative histology parameters were recorded at the time of biopsy, 14 of which were suitable for assessment of association with loss of eGFR by multivariable Cox regression analysis, measurement of eGFR slope and measurement of eGFR 12 months after biopsy. A widely used histopathological chronicity score was also assessed. Clinical baseline variables including prescription of immunosuppression were recorded. Seven of 14 histology parameters: mesangial matrix expansion, global glomerulosclerosis, tubular atrophy, interstitial fibrosis, arteriolosclerosis, mesangial hypercellularity and acute tubular injury; and the chronicity score, predicted loss of kidney function by all three measures. Prescription of immunosuppression was more likely in patients with active inflammatory pathology and less likely in patients with chronic fibrotic pathology, and was associated with reduced risk of loss of eGFR.

CONCLUSIONS

This retrospective study demonstrates the prognostic significance and complex relationship with immunosuppression of routinely reported histopathological variables in patients having native kidney biopsies, across the spectrum of kidney diseases. It provides useful information for renal biopsy prognostication and design of retrospective studies, including machine learning models.

Non-immunosuppressive treatment for IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerular disease, with approximately 20% to 40% of patients progressing to kidney failure within 25 years. Non-immunosuppressive treatment has become a mainstay in the management of IgAN by improving blood pressure (BP) management, decreasing proteinuria, and avoiding the risks of long-term immunosuppressive management. Due to the slowly progressive nature of the disease, clinical trials are often underpowered, and conflicting information about management with non-immunosuppressive treatment is common. This is an update of a Cochrane review, first published in 2011.

OBJECTIVES

To assess the benefits and harms of non-immunosuppressive treatment for treating IgAN in adults and children. We aimed to examine all non-immunosuppressive therapies (e.g. anticoagulants, antihypertensives, dietary restriction and supplementation, tonsillectomy, and herbal medicines) in the management of IgAN.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to December 2023 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of non-immunosuppressive agents in adults and children with biopsy-proven IgAN were included.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed search results, extracted data and assessed study quality. Results were expressed as mean differences (MD) for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CI) using random-effects meta-analysis. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

This review includes 80 studies (4856 participants), of which 24 new studies (2018 participants) were included in this review update. The risk of bias within the included studies was mostly high or unclear for many of the assessed methodological domains, with poor reporting of important key clinical trial methods in most studies. Antihypertensive therapies were the most examined non-immunosuppressive therapy (37 studies, 1799 participants). Compared to placebo or no treatment, renin-angiotensin system (RAS) inhibition probably decreases proteinuria (3 studies, 199 participants: MD - 0.71 g/24 h, 95% CI -1.04 to -0.39; moderate certainty evidence) but may result in little or no difference to kidney failure or doubling of serum creatinine (SCr), or complete remission of proteinuria (low certainty evidence). Death, remission of haematuria, relapse of proteinuria or > 50% increase in SCr were not reported. Compared to symptomatic treatment, RAS inhibition (3 studies, 168 participants) probably decreases proteinuria (MD -1.16 g/24 h, 95% CI -1.52 to -0.81) and SCr (MD -9.37 µmol/L, 95% CI -71.95 to -6.80) and probably increases creatinine clearance (2 studies, 127 participants: MD 23.26 mL/min, 95% CI 10.40 to 36.12) (all moderate certainty evidence); however, the risk of kidney failure is uncertain (1 study, 34 participants: RR 0.20, 95% CI 0.01 to 3.88; very low certainty evidence). Death, remission of proteinuria or haematuria, or relapse of proteinuria were not reported. The risk of adverse events may be no different with RAS inhibition compared to either placebo or symptomatic treatment (low certainty evidence). In low certainty evidence, tonsillectomy in people with IgAN in addition to standard care may increase remission of proteinuria compared to standard care alone (2 studies, 143 participants: RR 1.90, 95% CI 1.45 to 2.47) and remission of microscopic haematuria (2 studies, 143 participants: RR 1.93, 95% CI 1.47 to 2.53) and may decrease relapse of proteinuria (1 study, 73 participants: RR 0.70, 95% CI 0.57 to 0.85) and relapse of haematuria (1 study, 72 participants: RR 0.70, 95% CI 0.51 to 0.98). Death, kidney failure and a > 50% increase in SCr were not reported. These trials have only been conducted in Japanese people with IgAN, and the findings' generalisability is unclear. Anticoagulant therapy, fish oil, and traditional Chinese medicines exhibited small benefits to kidney function in patients with IgAN when compared to placebo or no treatment. However, compared to standard care, the kidney function benefits are no longer evident. Antimalarial therapy compared to placebo in one study reported an increase in a > 50% reduction of proteinuria (53 participants: RR 3.13 g/24 h, 95% CI 1.17 to 8.36; low certainty evidence). Although, there was uncertainty regarding adverse events from this study due to very few events.

AUTHORS' CONCLUSIONS

Available RCTs focused on a diverse range of interventions. They were few, small, and of insufficient duration to determine potential long-term benefits on important kidney and cardiovascular outcomes and harms of treatment. Antihypertensive agents appear to be the most beneficial non-immunosuppressive intervention for IgAN. The antihypertensives examined were predominantly angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. The benefits of RAS inhibition appear to outweigh the harms in patients with IgAN. The certainty of the evidence of RCTs demonstrating a benefit of tonsillectomy to patients with Japanese patients with IgAN was low. In addition, these findings are inconsistent across observational studies in people with IgAN of other ethnicities; hence, tonsillectomy is not widely recommended, given the potential harm of therapy. The RCT evidence is insufficiently robust to demonstrate efficacy for the other non-immunosuppressive treatments evaluated here.

Mortality in IgA Nephropathy: A Long-Term Follow-Up of an Eastern European Cohort

Background and Objectives: IgA nephropathy (IgAN), the most common primary glomerulonephritis, has been extensively studied for renal outcomes, with limited data on patient survival, particularly in Eastern Europe. We aimed to investigate the long-term survival rate of patients with IgAN and the associated risk factors in an Eastern European cohort. Materials and Methods: We conducted a retrospective analysis of 215 IgAN patients (median age 44, 71% male) diagnosed at a Romanian tertiary center between 2010 and 2017. We assessed clinical and pathological attributes, including the Charlson comorbidity index, the prevalence of diabetes, renal function, and treatment with renin-angiotensin-system inhibitors (RASIs). Results: Over a median 7.3-year follow-up, 20% of patients died, mostly due to cardiovascular diseases. Survival rates at 1, 5, and 10 years were 93%, 84%, and 77%, respectively. Deceased patients had higher Charlson comorbidity index scores, greater prevalence of diabetes, and poorer renal function. They were less frequently treated with RASIs and more frequently reached end-stage kidney disease (ESKD). Conclusions: We report a 20% mortality rate in our Eastern European IgAN cohort, primarily due to cardiovascular diseases. Death correlates with increased age, comorbidity burden, decreased renal function at diagnosis, and the absence of RASI use. RASI treatment may potentially improve survival, highlighting its importance in managing IgAN.

Glomerular spatial transcriptomics of IgA nephropathy according to the presence of mesangial proliferation

Mesangial proliferation is a diagnostic feature and a prognostic predictor of immunoglobulin A nephropathy (IgAN). We aimed to investigate the gene expression profiles of IgAN glomerulus according to the presence of mesangial proliferation. We performed spatial-specific transcriptomic profiling on kidney biopsy tissues using the GeoMx Digital Spatial Profiler. Twelve cases with three glomeruli for each case were profiled using direct pathologic classification (4 M1-IgAN, 4 M0-IgAN, and 4 donor controls). The results of enriched glom-specific genes demonstrated that M1-IgAN could be distinguished from controls (77 upregulated and 55 downregulated DEGs), while some DEGs were identified between M1-IgAN and M0-IgAN cases (24 upregulated and 8 downregulated DEGs) or between M0 and controls (1 upregulated and 16 downregulated DEGs). TCF21, an early podocyte damage marker, was the only differentially expressed gene (DEG) consistently upregulated in both M1-IgAN and M0-IgAN patients, whereas ATF3, EGR1, DUSP1, FOS, JUNB, KLF2, NR4A1, RHOB, and ZFP36 were consistently downregulated in IgAN cases. Glomeruli from M1-IgAN cases were significantly enriched for cell surface/adhesion molecules and gene expressions associated with vascular development or the extracellular matrix. Spatial transcriptomic analysis may contribute to dissecting structure-specific pathophysiology and molecular changes in IgAN.

Treatment of IgA Nephropathy: A Rapidly Evolving Field

The pivotal event in the pathophysiology of IgA nephropathy is the binding of circulating IgA-containing immune complexes to mesangial cells, with secondary glomerular and tubulointerstitial inflammation and fibrosis. The paramount difficulty in the management of IgA nephropathy is the heterogeneity in its clinical presentation and prognosis, requiring an individualized treatment approach. Goal-directed supportive care remains the bedrock of therapy for all patients, regardless of risk of progression. Sodium-glucose transporter 2 inhibitors and sparsentan should be integral to contemporary supportive care, particularly in patients with chronic kidney damage. Pending the development of reliable biomarkers, it remains a challenge to identify patients prone to progression due to active disease and most likely to derive a net benefit from immunosuppression. The use of clinical parameters, including the degree of proteinuria, the presence of persistent microscopic hematuria, and the rate of eGFR loss, combined with the mesangial hypercellularity, endocapillary hypercellularity, segmental glomerulosclerosis, tubular atrophy/interstitial fibrosis, crescents score, is currently the best approach. Systemic glucocorticoids are indicated in high-risk patients, but the beneficial effects wane after withdrawal and come at the price of substantial treatment-associated toxicity. Therapies with direct effect on disease pathogenesis are increasingly becoming available. While targeted-release budesonide has garnered the most attention, anti-B-cell strategies and selective complement inhibition will most likely prove their added value. We propose a comprehensive approach that tackles the different targets in the pathophysiology of IgA nephropathy according to their relevance in the individual patient.

The effect of fibrinoid necrosis on the clinical features and outcomes of primary IgA nephropathy

BACKGROUND

To explore the clinicopathologic features and outcomes of IgAN patients who presented with fibrinoid necrosis (FN) lesions or not and the effect of immunosuppressive (IS) treatment in IgAN patients with FN lesions as well.

METHODS

This was a retrospective cohort study with 665 patients diagnosed with primary IgAN from January 2010 to December 2020 in Tianjin Medical University General Hospital and having detailed baseline and follow-up characteristics. Patients were divided into two groups depending on the appearance of FN lesions. Patients with FN lesions were recruited into Group FN1, while patients who were not found FN lesions in their renal biopsy specimens were recruited into Group FN0. Compare the differences between Group FN0 and Group FN1 in baseline clinicopathologic features, treatment solutions and follow-up data as well. To evaluate the impact of different fractions of FN lesions on baseline characteristics and prognosis of IgAN, we subdivided patients in Group FN1 into 3 groups depending on the FN lesions distribution, Mild Group: 0 < FN% < 1/16; Moderate Group: 1/16 < FN% < 1/10; Severe Group: FN% > 1/10. Furthermore, we compared the differences in baseline clinicopathologic features, treatment solutions and follow-up data among these three groups. Kidney endpoint event was defined as patients went into end-stage kidney disease (ESKD), which estimated glomerular filtration rate (eGFR) < 15 ml/min/1.73 m^2, regularly chronic dialysis over 6 months or received renal transplantation surgery. The kidney composite endpoint was defined by a ≥ 30% reduction in eGFR, double Scr increase than on-set, ESKD, chronic dialysis over 6 months or renal transplantation. Compare the survival from a composite endpoint rate in different groups by Kaplan-Meier survival curve. The univariate and multivariate Cox models were used to establish the basic model for renal outcomes in patients with FN lesions.

RESULTS

(1) A total of 230 patients (34.59%) were found FN lesions in all participants. Patients with FN lesions suffered more severe hematuria than those without. On the hand of pathological characteristic, patients with FN lesions showed higher proportions of M1, E1, C1/C2 and T1/T2 lesions compared with those without FN lesions. (2) The 1-year, 3-year, and 5-year survival of the composite endpoint were lower in the FN1 group than FN0 group. (3) After adjusting for clinicopathological variables, the presence of FN lesions was a significantly independent risk factor for composite endpoint. By using multivariate Cox regression analyses, we also found when the fraction of FN lesions exceeded 10%, the risk of progression into composite endpoint increased 3.927 times.

CONCLUSION

Fibrinoid necrosis of capillary loops is an independent risk factor of poor renal outcomes. More effective treatment should be considered for those who had FN lesions.

Validating the association of Oxford classification and renal function deterioration among Taiwanese individuals with Immunoglobulin A nephropathy

Validation of the Oxford classification (MEST and MEST-C) for Immunoglobulin A nephropathy (IgAN) in the Taiwanese population is lacking. Our study aimed to validate this classification and assess individual lesion impact. We conducted a retrospective cohort study at Taichung Veterans General Hospital, Taiwan (Jan 2011-Jul 2023). Composite renal outcomes were evaluated using clinical conditions and estimated glomerular filtration rate (eGFR). We used Kaplan-Meier, univariable/multivariable logistic regression and ROC curves. Subgroup analysis considered eGFR < or ≥ 30.0 ml/min/1.73 m2. In 366 renal biopsies, serum creatinine was 1.34 mg/dl, eGFR 53.8 ml/min/1.73 m2, urine protein-creatinine ratio 1159 mg/g. T1/T2 lesions had lowest baseline eGFR (39.6/11.5 ml/min/1.73 m2), correlating with poorest renal survival (median survival 54.7/34.4 months). Univariable analysis linked all individual variables to worse renal outcomes. Multivariable analysis (MEST/MEST-C) showed only T1/T2 linked to worse outcomes. T score had highest predictive power (AUC 0.728, sensitivity 60.2%, specificity 83.6%), with MEST having high AUC (0.758). No extra predictive power was seen transitioning MEST to MEST-C. Subgroup analysis (eGFR < 30.0 ml/min/1.73 m2) associated C1 with improved renal outcomes (odds ratio 0.14, 95% CI 0.03-0.65). T lesion correlated with worse outcomes across subgroups. The T lesion consistently correlated with worse renal outcomes across all groups and baseline statuses. Integrating the C lesion into the transition from MEST to MEST-C did not enhance predictive power. Importantly, the C1 lesion was linked to improved renal outcomes in the eGFR < 30.0 ml/min/1.73 m2 subgroup, likely due to treatment effects.

The predictive value and response to immunosuppressive therapy of IgA nephropathy patients with crescents in a large retrospective Chinese cohort

Background

The prognostic value and response to immunosuppressive therapy (IST) of patients with crescents in the different backgrounds of pathological presentations in immunoglobulin A nephropathy (IgAN) is unclear.

Methods

A total of 1262 IgAN patients were enrolled. Crescents (C, 0/1/2), fibrinoid necrosis (FN, 0/1) and endocapillary hypercellularity (E, 0/1) were integrated into different degrees of glomerular activity (0-4 points): mild (0), moderate (1-2) and severe (≥3). The effect of IST on patients with different glomerular activity scores and chronic tubular and interstitial lesions (T, 0/1/2) were analysed using Cox regression analysis. The kidney outcome was defined as an estimated glomerular filtration rate decrease ≥30% or end-stage kidney disease.

Results

C2 was an independent risk factor for kidney outcomes {overall cohort: hazard ratio [HR] 1.85 [95% confidence interval (CI) 1.03-3.31], P = .040; T0 patients: HR 6.52 [95% CI 2.92-14.54], P < .001; reference to C0} in those without IST, while the HR decreased to 0.83 (95% CI 0.54-1.27; P = .396) in the overall cohort and 2.39 (95% CI 1.00-5.67; P = .049) in T0 patients with IST. For patients with severe glomerular activity, IST decreased the risk of kidney outcomes by 70% in the overall cohort [HR 0.30 (95% CI 0.12-0.74), P = .009; reference to those without IST] and 86% in T0 patients [HR 0.14 (95% CI 0.04-0.54), P = 0.005; reference to those without IST].

Conclusions

IST could reduce the risk for kidney outcomes in IgAN patients with C2 and T0 lesions together, as well as in those with crescents and at least one other active lesion, including FN and E1 lesions.

Long-term follow-up of an IgA nephropathy cohort: outcomes and risk factors

AIM

IgA nephropathy (IgAN), the most common glomerulopathy worldwide and in Uruguay, raised treatment controversies. The study aimed to analyze long-term IgAN outcomes and treatment.

METHODS

A retrospective analysis of a Uruguayan IgAN cohort, enrolled between 1985 and 2009 and followed up until 2020, was performed. The Ethics Committee approved the study. The inclusion criteria were (a) biopsy-proven IgAN; (b) age ≥12 years; and (c) available clinical, histologic, and treatment data. The patients were divided into two groups, with immunosuppressive (IS) or without (NoIS) treatment. Outcomes (end-stage kidney disease/kidney replacement therapy [ESKD/KRT] or all-cause death) were obtained from mandatory national registries.

RESULTS

The study population included 241 patients (64.7% men), median age 32 (19.5) years, baseline blood pressure <130/80 mmHg in 37%, and microhematuria in 67.5% of patients. Baseline proteinuria, glomerulosclerosis, and a higher crescent percentage were significantly more frequent in the IS group. Proteinuria improved in both groups. Renal survival at 20 years was 74.6% without difference between groups. In the overall population and in the NoIS group, bivariate Cox regression analysis showed that baseline proteinuria, endocapillary hypercellularity, tubule interstitial damage, and crescents were associated with a higher risk of ESKD/KRT or death, but in the IS group, proteinuria and endocapillary hypercellularity were not. In the multivariate Cox analysis, proteinuria in the NoIS group, crescents in the IS group and tubule interstitial damage in both groups were independent risk factors.

CONCLUSION

The IS group had more severe risk factors than the NoIS group but attained a similar outcome.

Oral glucocorticoids with intravenous cyclophosphamide or oral glucocorticoids alone in the treatment of IgA nephropathy present with nephrotic syndrome and mesangioproliferative glomerulonephritis

Background

Few studies have evaluated the treatment of immunoglobulin A nephropathy (IgAN) patients with nephrotic syndrome (NS) and mesangioproliferative glomerulonephritis (MPGN). The aim of this study was to compare the therapeutic effects of oral glucocorticoids (GCS) combined with intravenous cyclophosphamide (CTX) and oral GCS alone in the treatment of the MPGN-IgAN patients with NS.

Methods

Biopsy-proven primary IgAN patients who were aged ≥14 years at diagnosis, had coexistent NS and MPGN and estimated glomerular filtration rate (eGFR) ≥15 mL/min/1.73 m2, and were treated by oral GCS combined with intravenous CTX or oral GCS alone for 6-12 months were retrospectively included. The patients in the GCS + CTX (prednisone 0.6-0.8 mg/kg/day and intravenous CTX 0.6-1.0 g monthly) or GCS (prednisone 0.8-1 mg/kg/day) group were rather matched at a 1:1 ratio on key characteristics by propensity score matching. The primary outcome was defined as either complete remission or partial remission at Month 24. The secondary outcome was a composite renal endpoint defined as a 50% decline in eGFR, doubling of serum creatinine or progression to end-stage kidney disease.

Results

Among the 146 IgAN patients who met the inclusion criteria, 42 patients were enrolled in the GCS + CTX group, and 42 patients were enrolled in the GCS group after propensity score matching. The clinical and histological parameters were similar between the two groups. Remission occurred more frequently in the GCS + CTX group at Month 6 (88.1% vs 52.4%, P < 0.001), Month 12 (88.1% vs 56.1%, P = 0.001) and Month 24 (85.0% vs 47.5%, P < 0.001) than in the GCS group. Moreover, subgroup analysis revealed that the higher response rate at Month 24 in the GCS + CTX group than in the GCS group was also present in different subgroups defined by sex, age, eGFR or Oxford MEST-C. Notably, we found that eGFR decreased at a lower rate in patients from the GCS + CTX group than in patients from the GCS group [eGFR slope: 0.05(-3.09, 3.67) vs -2.56 (-11.30, 0.86) mL/min/1.73 m2/year, P = 0.03]. Based on multivariate Cox regression analysis, GCS + CTX treatment was found to be independently associated with a decrease in risk for the composite endpoint after adjusted by the International Risk Prediction Score with race (hazard ratio = 0.17, 95% confidence interval 0.04-0.83, P = .03). There was no significant difference in adverse events (50.0% vs 42.9%, P = 0.51) or serious adverse events (7.1% vs 11.9%, P = .71) between the two groups.

Conclusions

Oral GCS combined with intravenous CTX is superior to GCS alone in treating MPGN-IgAN patients combined with NS. As the retrospective design and small sample size, our findings need to be validated by a prospective study.

Evaluating Progression Risk in Patients With Immunoglobulin A Nephropathy

The highly variable rate of decline in kidney function in patients with immunoglobulin A nephropathy (IgAN) provides a major clinical challenge. Predicting which patients will progress to kidney failure, and how quickly, is difficult. Multiple novel therapies are likely to be approved in the short-term, but clinicians lack the tools to identify patients most likely to benefit from specific treatments at the right time. Noninvasive and validated markers for selecting at-risk patients and longitudinal monitoring are urgently needed. This review summarizes what is known about demographic, clinical, and histopathologic prognostic markers in the clinician's toolkit, including the International IgAN Prediction Tool. We also briefly review what is known on these topics in children and adolescents with IgAN. Although helpful, currently used markers leave clinicians heavily reliant on histologic features from the diagnostic kidney biopsy and standard clinical data to guide treatment choice, and very few noninvasive markers reflect treatment efficacy over time. Novel prognostic and predictive markers are under clinical investigation, with considerable progress being made in markers of complement activation. Other areas of research are the interplay between gut microbiota and galactose-deficient IgA1 expression; microRNAs; imaging; artificial intelligence; and markers of fibrosis. Given the rate of therapeutic advancement, the remaining gaps in biomarker research need to be addressed. We finish by describing our route to clinical utility of predictive and prognostic markers in IgAN. This route will provide us with the chance to improve IgAN prognosis by using robust, clinically practical markers to inform patient care.

Clinical and pathological characteristics in elderly patients with IgA nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is the most common cause of primary glomerulonephritis, with highly variable manifestations. Although the peak incidence of IgAN is in young adults, the diagnosis among elderly people is increasing. Here we explored the effect of aging on IgAN features, as well as cellular senescence in the kidney of IgAN.

Methods

A total of 910 patients with IgAN were enrolled, which contained 182 individuals in each age stage (aged ≥60, 50-59, 40-49, 30-39 and 20-29 years). Clinical and pathological manifestations at the time of renal biopsy were compared. Additionally, 38 patients with IgAN (19 aged over or equal to 60 years and 19 aged below 60 years) were randomly selected for p16INK4a staining by immunohistochemistry. The percentage of p16INK4a-positive cells in glomeruli, renal tubule and interstitium were separately quantified.

Results

Compared with young IgAN patients, elderly patients presented with higher levels of circulating IgA, uric acid and proteinuria, but lower estimated glomerular filtration rates (eGFR), as well as lower red blood cell counts, platelet counts and lymphocyte counts. Moreover, elderly IgAN patients showed higher incidence of hypertension, and lower incidence of prodromic infection. Regarding histological lesions in the kidney, young IgAN patients had higher degree of IgA and C3 deposits, while elderly IgAN patients had more severe Oxford-E lesions, but less severe Oxford-S lesions. The percentage of glomerular and tubular p16INK4a-positive cells in elderly patients showed an increasing trend, but statistical significance was not reached. The percentage of p16INK4a-positive nuclei in renal interstitium was positively associated with T score, while increased percentage of p16INK4a-positive nuclei in renal tubule was associated with eGFR and 24-h urinary protein level.

Conclusion

In our IgAN cohort, elderly IgAN patients presented with some aging-related features, and both aging- and IgAN-induced pathological injury contributed to the kidney lesions in patients with IgAN.

Nomogram for the prediction of crescent formation in IgA nephropathy patients: a retrospective study

BACKGROUND

The 2017 Oxford classification of immunoglobulin A nephropathy (IgAN) recently reported that crescents could predict a worse renal outcome. Early prediction of crescent formation can help physicians determine the appropriate intervention, and thus, improve the outcomes. Therefore, we aimed to establish a nomogram model for the prediction of crescent formation in IgA nephropathy patients.

METHODS

We retrospectively analyzed 200 cases of biopsy-proven IgAN patients. Least absolute shrinkage and selection operator(LASSO) regression and multivariate logistic regression was applied to screen for influencing factors of crescent formation in IgAN patients. The performance of the proposed nomogram was evaluated based on Harrell's concordance index (C-index), calibration plot, and decision curve analysis.

RESULTS

Multivariate logistic analysis showed that urinary protein ≥ 1 g (OR = 3.129, 95%CI = 1.454-6.732), urinary red blood cell (URBC) counts ≥ 30/ul (OR = 3.190, 95%CI = 1.590-6.402), mALBU ≥ 1500 mg/L(OR = 2.330, 95%CI = 1.008-5.386), eGFR < 60ml/min/1.73m2(OR = 2.295, 95%CI = 1.016-5.187), Serum IgA/C3 ratio ≥ 2.59 (OR = 2.505, 95%CI = 1.241-5.057), were independent risk factors for crescent formation. Incorporating these factors, our model achieved well-fitted calibration curves and a good C-index of 0.776 (95%CI [0.711-0.840]) in predicting crescent formation.

CONCLUSIONS

Our nomogram showed good calibration and was effective in predicting crescent formation risk in IgAN patients.

Hyperuricemia is associated with the progression of IgA nephropathy in children

BACKGROUND

The objective of the study was to explore the potential biomarkers and risk factors in children with immunoglobulin A nephropathy (IgAN).

METHODS

Untargeted metabolomics analysis was performed on children with IgAN before and after treatment. Subsequently, a retrospective study involving the past 15 years and a follow-up study were performed to verify the role of hyperuricemia in IgAN children.

RESULTS

Serum metabolomics analyses showed that levels of serum xanthosine were closely related to the outcome of IgAN, and KEGG analyses showed that differential metabolites were significantly enriched in purine metabolism. Furthermore, retrospectively analyses of 252 children with IgAN showed that hyperuricemia was associated with poorer renal outcome. Logistic regression analysis showed that BMI, serum creatinine, eGFR, Lee's grade III, and crescents were risk factors of hyperuricemia in children with IgAN. Kaplan-Meier analysis revealed that kidney progression-free survival in IgAN children with hyperuricemia was lower than that without hyperuricemia, especially in females.

CONCLUSIONS

We first performed a dynamic metabolomics study to reveal that hyperuricemia is closely related to the progression of IgAN in children. Then retrospective and follow-up studies confirmed that hyperuricemia is an important risk factor for poor renal outcomes. We need to pay more attention to the hyperuricemia in children with IgAN.

IMPACT

We first performed a dynamic metabolomics study to reveal that hyperuricemia was closely related to the progression of IgAN in children. Retrospective analyses in past 15 years confirmed that IgAN children with hyperuricemia had poorer renal function and worse renal pathology. The BMI, Scr, eGFR, Lee's grade III, and crescents were risk factors of hyperuricemia in children with IgAN. The long-term follow-up study showed that hyperuricemia was an important risk factor for poor renal outcome in children with IgAN. We need to pay more attention to hyperuricemia in children with IgAN, especially in females.

EGF-Receptor-Dependent TLR7 Signaling in Macrophages Promotes Glomerular Injury in Crescentic Glomerulonephritis

Glomerulonephritis (GN) is a group of inflammatory diseases and an important cause of morbidity and mortality worldwide. The initiation of the inflammatory process is quite different for each type of GN; however, each GN is characterized commonly and variably by acute inflammation with neutrophils and macrophages and crescent formation, leading to glomerular death. Toll-like receptor (TLR) 7 is a sensor for self-RNA and implicated in the pathogenesis of human and murine GN. Here, we show that TLR7 exacerbates glomerular injury in nephrotoxic serum nephritis (NTN), a murine model of severe crescentic GN. TLR7-/- mice were resistant to NTN, although TLR7-/- mice manifested comparable immune-complex deposition to wild-type mice without significant defects in humoral immunity, suggesting that endogenous TLR7 ligands accelerate glomerular injury. TLR7 was expressed exclusively in macrophages in glomeruli in GN but not in glomerular resident cells or neutrophils. Furthermore, we discovered that epidermal growth factor receptor (EGFR), a receptor-type tyrosine kinase, is essential for TLR7 signaling in macrophages. Mechanistically, EGFR physically interacted with TLR7 upon TLR7 stimulation, and EGFR inhibitor completely blocked the phosphorylation of TLR7 tyrosine residue(s). EGFR inhibitor attenuated glomerular damage in wild-type mice, and no additional glomerular protective effects by EGFR inhibitor were observed in TLR7-/- mice. Finally, mice lacking EGFR in macrophages were resistant to NTN. This study clearly demonstrated that EGFR-dependent TLR7 signaling in macrophages is essential for glomerular injury in crescentic GN.

Evaluation of the Modified Oxford Score in Recurrent IgA Nephropathy in North American Kidney Transplant Recipients: The Banff Recurrent Glomerulonephritis Working Group Report

BACKGROUND

The modified Oxford classification mesangial and endocapillary hypercellularity, segmental sclerosis, interstitial fibrosis/tubular atrophy, and the presence of crescents (MEST-C) of immunoglobulin A nephropathy (IgAN) was recently shown to be a predictor of graft failure in Asians with recurrent IgAN. We aimed to validate these findings in a cohort from North American centers participating in the Banff Recurrent Glomerulopathies Working Group.

METHODS

We examined 171 transplant recipients with end-stage kidney disease because of IgAN; 100 of them with biopsy-proven recurrent IgAN (57 of them had complete MEST-C scores) and 71 with no recurrence.

RESULTS

IgAN recurrence, which was associated with younger age at transplantation ( P  = 0.012), strongly increased the risk of death-censored graft failure (adjusted hazard ratio, 5.10 [95% confidence interval (CI), 2.26-11.51]; P  < 0.001). Higher MEST-C score sum was associated with death-censored graft failure (adjusted hazard ratio, 8.57 [95% CI, 1.23-59.85; P  = 0.03] and 61.32 [95% CI, 4.82-779.89; P  = 0.002] for score sums 2-3 and 4-5 versus 0, respectively), and so were the single components endocapillary hypercellularity, interstitial fibrosis/tubular atrophy, and crescents ( P  < 0.05 each). Overall, most of the pooled adjusted hazard ratio estimates associated with each MEST-C component were consistent with those from the Asian cohort (heterogeneity I2 close to 0%, and P  > 0.05).

CONCLUSIONS

Our findings may validate the prognostic usefulness of the Oxford classification for recurrent IgAN and support the inclusion of the MEST-C score in allograft biopsies diagnostic reports.

Learning more from the inter-rater reliability of interstitial fibrosis assessment beyond just a statistic

Interstitial fibrosis assessment by renal pathologists lacks good agreement, and we aimed to investigate its hidden properties and infer possible clinical impact. Fifty kidney biopsies were assessed by 9 renal pathologists and evaluated by intraclass correlation coefficients (ICCs) and kappa statistics. Probabilities of pathologists' assessments that would deviate far from true values were derived from quadratic regression and multilayer perceptron nonlinear regression. Likely causes of variation in interstitial fibrosis assessment were investigated. Possible misclassification rates were inferred on reported large cohorts. We found inter-rater reliabilities ranged from poor to good (ICCs 0.48 to 0.90), and pathologists' assessments had the worst agreements when the extent of interstitial fibrosis was moderate. 33.5% of pathologists' assessments were expected to deviate far from the true values. Variation in interstitial fibrosis assessment was found to be correlated with variation in interstitial inflammation assessment (r2 = 32.1%). Taking IgA nephropathy as an example, the Oxford T scores for interstitial fibrosis were expected to be misclassified in 21.9% of patients. This study demonstrated the complexity of the inter-rater reliability of interstitial fibrosis assessment, and our proposed approaches discovered previously unknown properties in pathologists' practice and inferred a possible clinical impact on patients.

Systematic Review of the Oxford Classification of IgA Nephropathy: Reproducibility and Prognostic Value

Key Points

The Oxford classification of IgA nephropathy defined five features scored subjectively in renal biopsies, identified by the initials MESTC. Two large studies with independent observers showed reproducibility was moderate for T, moderate or poor for M and S, and poor for E and C. In multivariate analyses including clinical features, T was related to 58% of outcomes, with no correlation of MESTC with 24% of outcomes.

Background

The Oxford classification of IgA nephropathy defined five prognostic features scored subjectively in renal biopsies: mesangial cellularity (M), endocapillary hypercellularity (E), segmental sclerosis (S), interstitial fibrosis/tubular atrophy (T), and (fibro)cellular crescents (C). Pathological scoring systems should be reproducible and have prognostic value independently of clinical features. Reproducibility of the classification was not previously investigated in a systematic review, and the most recent systematic reviews of prognostic value were in 2017.

Methods

This systematic review followed PRISMA 2020 guidelines. MEDLINE, PUBMED, and EMBASE databases were searched using the terms “IgA nephropathy” and “Oxford.” Eligible papers applied the classification and mentioned statistical analysis of interobserver reproducibility and/or included multivariate analysis of outcomes related to individual Oxford scores and clinical features, including treatment with corticosteroids or other immunosuppressive drugs.

Results

There were 99 suitable papers before September 23, 2022. Of 12 papers that mentioned reproducibility, only six reported statistics for MEST/MESTC scoring. Four of these were small studies and/or had observers at the same institution. These were considered less representative of application of the classification than two large studies with independent observers, in which agreement was moderate for T, either moderate or poor for M and S, and poor for E and C. In 92 papers with 125 multivariate analyses of various outcomes, the commonest Oxford element associated with outcomes was T (73 of 125, 58%), with no correlation of any element with outcomes in 30 analyses (24%). Treatment with immunosuppression was often related to scores, particularly C and E, without consistent relations between Oxford scores and outcomes in immunosuppressed patients.

Conclusions

This systematic review showed limitations of the Oxford classification in practice, particularly the moderate or poor reproducibility of scores. T was the Oxford score most often related to clinical outcomes, but even this was not consistently reliable as a prognostic indicator.

Independent Prognostic and Predictive Role of Interstitial Macrophages in Kidney Biopsies of IgA Nephropathy Patients

A relevant percentage of IgAN patients experience a progressive decline in kidney function. According to the KDIGO guidelines, proteinuria and eGFR are the only validated prognostic markers. The role of interstitial macrophages in kidney biopsies of IgAN patients and the outcome of patients treated with renin-angiotensin system inhibitors (RASBs) alone or combined with glucocorticoids were evaluated. Clinical and laboratory records (age, gender, hypertension, hematuria, proteinuria, eGFR, serum creatinine, and therapy), MEST-C parameters of the Oxford classification, C4d deposition, peritubular capillaries, and glomerular and interstitial macrophages in 47 IgAN patients undergoing kidney biopsy consecutively between 2003 and 2016 were examined. A high number of interstitial macrophages significantly correlated with peritubular capillary rarefaction and impairment of kidney function. Cox's multivariable regression analysis revealed that a value > 19.5 macrophages/HPF behaved as an independent marker of an unfavorable outcome. Patients exhibiting > 19.5 macrophages/HPF treated at the time of diagnosis with RASBs combined with methylprednisolone had an estimated probability of a favorable outcome higher than patients treated with RASBs alone. Thus, a value > 19.5 macrophages/HPF in IgAN biopsies can predict an unfavorable outcome and endorse a well-timed administration of glucocorticoids. Studies evaluating urine biomarkers associated with peritubular capillary rarefaction in patients with marked macrophage infiltration may help personalized treatment decisions.

Histological Features of IgA Nephropathy in Pediatrics and the Magnitude of the Disease in Saudi Children

Objectives

This review addresses the microscopic features of immunoglobulin A nephropathy (IgA nephropathy), its prognostic variables in children, and measures to which extent these features and variables differ from adults. Furthermore, it describes the extent of this disease process among children in Saudi Arabia and the rest of the Arab countries and compares it with the data from the West and the Far East.

Method

All the original work described the histological features of pediatric IgA nephropathy, and studies involved in developing the prognostic classification of IgA nephropathy, Oxford Classification, were reviewed. Moreover, the studies describing the crescent prevalence and outcome in pediatric IgA nephropathy in addition to thrombotic microangiopathy association were studied. National studies describing the prevalence of pediatric IgA nephropathy and pediatric crescentic glomerulonephritis were tracked with an overview of the regional data from the rest of the Arab world.

Results

IgA nephropathy in children showed more glomerular proliferative changes and less glomerular vascular and tubule-interstitial chronic injury compared to adults. The reference study that described the association between thrombotic microangiopathy and IgA nephropathy did not include the pediatric age group. Moreover, it was found that the data from the Middle East was not encountered in developing the original and updated IgA nephropathy Oxford Classification. Furthermore, the prevalence of IgA nephropathy in children is described in the regional literature, but its histological features were not well detailed. Finally, the percentage of crescentic glomerulonephritis (GN) due to IgA nephropathy is less in our country compared to the West and concords with the Far East findings.

Conclusion

A well-designed regional study addressing IgA nephropathy in Middle East children with a focus on histological features, association with crescent, and thrombotic microangiopathy and challenging the validity of the updated IgA nephropathy Oxford Classification is recommended.

Corticosteroid Therapy in Immunoglobulin A Nephropathy: A Friend or Foe?

BACKGROUND

The administration of corticosteroids in addition to supportive care to delay progressive immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis worldwide, remains controversial. This is partly due to the paucity of well-designed randomized controlled trials and well-known corticosteroid-related side effects. As a result, clinical equipoise in corticosteroid therapy exists depending on geographical regions and the clinician's preference.

SUMMARY

Better understanding around the pathogenesis of IgAN has prompted several clinical trials exploring the effects of immunosuppressive agents including corticosteroids. Earlier studies of corticosteroids were limited by suboptimal study designs, inadequate implementation of standard of care, and inconsistent adverse event data collection. Two well-designed, adequately powered, multi-centre randomized controlled trials, the STOP-IgAN and TESTING studies, have reported contrasting kidney outcomes that have further fuelled the clinical conundrum regarding the efficacy of corticosteroids. Both studies independently reported greater adverse events with corticosteroids. A novel targeted release formulation of budesonide, which has been hypothesized to reduce the adverse events associated with systemic corticosteroids, has shown promising results in the Phase 3 NefigaRD trial. Studies of treatments targeting B cells and the complement cascade are currently underway, and early data appear encouraging. This review provides an overview of the current literature around the understanding of the pathomechanisms and benefits and harm of corticosteroid use in IgAN.

KEY MESSAGES

Recent evidence suggests the use of corticosteroids in a selected cohort of people with IgAN at high risk of disease progression can improve kidney outcomes but comes with an associated risk of treatment-related adverse events, particularly with higher doses. Management decisions should therefore follow an informed patient-clinician discussion.

Serum sCD40L and IL-31 in Association with Early Phase of IgA Nephropathy

BACKGROUND

IgA nephropathy (IgAN) is a major cause of chronic glomerulonephritis worldwide. T cell dysregulation has been reported to contribute to the pathogenesis of IgAN. Methods We measured a broad range of Th1, Th2 and Th17 cytokines in the serum of IgAN patients. We searched for significant cytokines, which were associated with clinical parameters and histological scores in IgAN patients.

RESULTS

Among 15 cytokines, the levels of soluble CD40L (sCD40L) and IL-31 were higher in IgAN patients and were significantly associated with a higher estimated glomerular filtration rate (eGFR), a lower urinary protein to creatinine ratio (UPCR), and milder tubulointerstitial lesions (i.e., the early phase of IgAN). Multivariate analysis revealed that serum sCD40L was an independent determinant of a lower UPCR after adjustment for age, eGFR, and mean blood pressure (MBP). CD40, a receptor of sCD40L, has been reported to be upregulated on mesangial cells in IgAN. The sCD40L/CD40 interaction may directly induce inflammation in mesangial areas and may therefore be involved in the development of IgAN.

CONCLUSIONS

The present study demonstrated the significance of serum sCD40L and IL-31 in the early phase of IgAN. Serum sCD40L may be a marker of the beginning of inflammation in IgAN.

Tubulointerstitial B-cell infiltration and tertiary lymphoid tissue in adult-onset immunoglobulin A vasculitis with nephritis

PURPOSE

This study aimed to examine tubulointerstitial B-cell infiltration in patients with adult-onset immunoglobulin A vasculitis (IgAV) and nephritis (IgAV-N), and to evaluate whether B-cell infiltration correlated with clinicopathological variables at kidney biopsy and with short-term renal outcomes.

METHODS

Twenty patients with adult-onset IgAV-N and 10 control patients with thin basement membrane nephropathy (TBMN) were retrospectively examined. The lymphatic organization was graded based on B-cell infiltration and was classified into 4 groups: 0-T cells without B cells, 1-scattered B and T cells, 2-clustered B and T cells, and 3-nodular compartmentally arranged B- and T-cell aggregates, equivalent to tertiary lymphoid tissue (TLT).

RESULTS

The B-cell infiltration grade was significantly higher in patients with IgAV-N than in patients with TBMN, and no age differences were observed. The B-cell infiltration grade in patients with IgAV-N was significantly correlated with age, serum IgA level, renal dysfunction, and tubulointerstitial injury parameters, but was not correlated with duration after purpura or glomerular injury parameters. Most patients with IgAV-N were treated with corticosteroids. The proteinuria level was significantly decreased, but renal function was not improved in 12 patients after the 24-month follow-up compared with the values at baseline. The B-cell infiltration grade was significantly correlated with renal dysfunction after 24 months of follow-up.

CONCLUSIONS

The B-cell infiltration grade in patients with IgAV-N was associated with renal dysfunction and tubulointerstitial injuries but not with glomerular injury parameters. B-cell infiltration and TLT might have a pathologically significant role in irreversible renal dysfunction in patients with early phase adult-onset IgAV-N.

The Diagnostic Conundrum of Glomerular Crescents With IgA Deposits

Introduction

Glomerulonephritis (GN) with crescents and IgA deposits in kidney biopsy poses a frequent diagnostic and therapeutic dilemma because of multiple possibilities.

Methods

Native kidney biopsies showing glomerular IgA deposition and crescents (excluding lupus nephritis) were identified from our biopsy archives between 2010 and 2021. Detailed clinicopathologic features were assessed. One-year clinical follow-up on a subset of cases was obtained.

Results

A total of 285 cases were identified, and these clustered into IgA nephropathy (IgAN, n = 108), Staphylococcus or other infection-associated GN/infection-related GN (SAGN/IRGN, n = 43), and antineutrophil cytoplasmic antibody-associated GN (ANCA-GN, n = 26) based on a constellation of clinicopathologic features, but 101 cases (group X) could not be definitively differentiated. The reasons have been elucidated, most important being atypical combination of clinicopathologic features and lack of definitive evidence of active infection. Follow-up (on 72/101 cases) revealed that clinicians' working diagnosis was IgAN in 43%, SAGN/IRGN in 22%, ANCA-GN in 28%, and others in 7% of the cases, but treatment approach varied from supportive or antibiotics to immunosuppression in each subgroup. Comparing these cases as "received immunosuppression" versus "non-immunosuppression," only 2 features differed, namely C3-dominant staining, and possibility of recent infection (both higher in the no-immunosuppression group) (P < 0.05). Renal loss was higher in the non-immunosuppression subgroup, but not statistically significant (P = 0.11).

Conclusion

Diagnostic overlap may remain unresolved in a substantial number of kidney biopsies with glomerular crescents and IgA deposits. A case-by-case approach, appropriate antibiotics if infection is ongoing, and consideration for cautious immunosuppressive treatment for progressive renal dysfunction may be needed for best chance of renal recovery.

The Beneficial Effect of Three-month Induction Therapy with High-dose Prednisone and Mycophenolate Mofetil Followed by Maintenance Therapy in Acute Non-crescentic Nephritis Associated with Immunoglobulin A Deposition Disease in Adults

The data available on immunoglobulin A (IgA) deposition disease indicate an inherited predisposition to the disease with autoimmune triggering. Hence, we prospectively evaluated the role of a new autoimmune regimen in the treatment of severe nephrotic or nephritic flares associated with noncrescentic nephritis in adult patients. Thirty-six patients were included, and the regimen consisted of an initial 3-month induction phase of prednisone and mycophenolate mofetil (MMF), followed by a maintenance phase of MMF alone for 21 months. Complete remission (CR) (normalization of creatinine clearance [CrCl] and a decrease in protein output to <500 mg/day) was achieved in 29 of 36 patients, and a partial response (no further decline in CrCl and a decrease in proteinuria to <50%) was seen in seven patients. CrCl was maintained in patients with CR but was mildly reduced in partially responsive ones. Our study showed the short- and longterm safety and efficacy of this autoimmune regimen directed toward the autoimmune triggering factors in severe forms of noncrescentic IgA nephritis.

Outcomes and risk factors in patients with crescentic glomerulonephritis: a multicenter cohort study

BACKGROUND

Patients with crescentic glomerulonephritis have a poor prognosis despite immunosuppressive therapy. This study investigated the clinicopathologic features, outcomes, and risk factors in Chinese patients with crescentic glomerulonephritis.

METHODS

The multicenter cohort study included consecutive individuals with crescentic glomerulonephritis and a minimum follow-up of 1 year after biopsy, observed from January 2013 to December 2020. Primary outcome was the occurrence of death or end stage kidney disease (ESKD) for surviving patients. Multivariable adjusted Cox proportional hazards model was applied.

RESULTS

Of 109 patients enrolled, 73 (67%) suffered primary outcomes, including 39 deaths, and 34 ESKDs among the 70 surviving patients, with a mean follow-up of 26 months. All 26 patients with over 90% glomeruli with crescents reached a primary outcome. Patients with type III crescentic glomerulonephritis had the worst prognosis for primary outcomes (HR, 95% CI for type I vs. type III: 0.29, 0.14-0.58; type II vs. type III: 0.44, 0.22-0.91) and a significantly faster rate of eGFR decline after adjusting for baseline variables. In patients with 75%-100% glomeruli with crescents, the risk of a primary outcome increased nearly fourfold (HR 3.96; 95% CI 2.17-7.23) compared with patients with 50-75% glomeruli with crescents after adjusting for baseline variables. Type of crescentic glomerulonephritis and percentage of cellular and total glomeruli with crescents were independent risk factors for early primary outcomes (within 6 months).

CONCLUSIONS

This study provides new insights into crescentic glomerulonephritis, including a description of the worst outcomes occurring in patients with type III crescentic glomerulonephritis, and suggests that the quantification of the percentage of crescents may be of use for guiding therapeutic decisions, due to their role in identifying the risk of primary outcomes.

Association between geriatric nutritional risk index and pathological phenotypes of IgA nephropathy

Background

IgA nephropathy (IgAN) is an immune disease related to oxidative stress and inflammation. It is the most common type of glomerulonephritis in the world and is the cause of chronic kidney disease and end-stage renal disease (ESRD). The Geriatric Nutritional Risk Index (GNRI) is a practical and uncomplicated method to assess the risk of morbidity and mortality, but its ability to assess IgAN is still unclear. Here, we evaluated the association between the GNRI and clinical and histologic findings of IgAN.

Methods

In a cross-sectional study, we included 348 biopsy-verified IgAN patients. The Oxford classification was used to analyze the pathological characteristics of the included patients. Based on previous studies, the participants were divided into two groups using a cutoff value of 92. Differences in clinicopathological indices between the two groups were compared. The correlation between the GNRI and the indicators was evaluated by using a bivariate correlation analysis. A binary logistic regression analysis was conducted to determine the factors associated with the crescent lesions in IgAN.

Results

In this study, 138 out of 348 patients (39.7%) had low GNRI scores (GNRI < 92). Patients in the low GNRI group tended to have a significantly lower body mass index; lower hemoglobin, serum albumin, serum IgG, and serum C3 levels; and higher 24-h proteinuria. The proportions of females, Oxford M1 and Oxford C1/2 were higher in the low GNRI group. The GNRI was positively correlated with body mass index (r = 0.57, P < 0.001), hemoglobin (r = 0.35, P < 0.001), serum albumin (r = 0.83, P < 0.001), serum IgG (r = 0.32, P < 0.001), and serum C3 (r = 0.26, P < 0.001) and negatively correlated with 24-h proteinuria (r = -0.36, P < 0.001) and the proportion of crescents (r = -0.24, P < 0.001). The GNRI scores and serum IgG levels were considered independent factors influencing the crescent lesions in IgAN.

Conclusions

The GNRI can reflect the severity of clinical and histologic phenotypes in IgAN patients. Lower GNRI and serum IgG levels may suggest an increased risk of crescent lesions and are potential markers for disease monitoring in IgAN.

Clinical relevance of glomerular C4d deposition in children with early IgA nephropathy or Henoch-Schönlein purpura nephropathy

BACKGROUND

Both IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephropathy (HSPN) are characterized by glomerular mesangial IgA deposition. Several large studies on adults have suggested that glomerular C4d deposition has prognostic value in IgAN. However, there are few relevant studies on the clinical value of C4d deposition in children with IgAN or HSPN.

METHODS

We performed a retrospective cohort study in pediatric patients with IgAN or HSPN. Clinicopathological data were collected at the time of kidney biopsy. Kidney C4d deposition was analyzed by immunohistochemistry. The end point was defined as a ≥ 20% decrease in estimated glomerular filtration from baseline.

RESULTS

We enrolled 75 children, including 36 children with IgAN and 39 with HSPN. The prevalence of C4d deposition was 36% (27/75). C4d deposition was more abundant in children with proteinuria ≥ 50 mg/kg/day (51.9% versus 20.8%, P = 0.006) or nephrotic syndrome (37.0% versus 10.4%, P = 0.006). Mesangial hypercellularity (hazard ratio [HR], 5.745, 95% confidence interval [CI], 1.670-19.761, P = 0.006) and IgM deposition (HR, 4.522, 95% CI, 1.321-15.478, P = 0.016) were associated with C4d deposition. After a median follow-up of 22 months, seven (19.4%) IgAN patients and one (2.6%) HSPN patient had decreased kidney function. In children with IgAN, positive C4d was associated with decreased kidney function (P = 0.047).

CONCLUSION

Glomerular C4d deposition was associated with mesangial hypercellularity and glomerular IgM deposition in IgAN and HSPN. Glomerular C4d deposition may be a risk factor for eGFR decline in children with IgAN. A higher resolution version of the Graphical abstract is available as Supplementary information.

Excess selenium intake is associated with microalbuminuria in female but not in male among adults with obesity: Results from NHANES 2009-2018

Introduction

Selenium is a critical trace element with antioxidant activities that has been related to the preservation of kidney function. Few studies, however, have looked at the effects of excess selenium on kidneys. The purpose of the present study was performed to investigate the relationship between dietary selenium intake and the prevalence of microalbuminuria in American adults with obesity.

Methods

A total of 8,547 participants with obesity in the National Health and Nutrition Examination Survey (NHANES) with the age of 19 years or older were included in the present study. Multivariable regression and subgroup analyses were performed to examine the association between dietary selenium and microalbuminuria in the two genders, separately. A selenium intake above the median was defined as high selenium intake.

Results

Dietary selenium intake was significantly higher in men compared to women (139.49 μg/day vs. 101.06 μg/day; P < 0.0001). Among female participants, the prevalence of microalbuminuria was significantly higher in participants with a high selenium intake compared with those without a high selenium intake (13.82 vs. 9.96%; P = 0.008), whereas this difference did not exist in male participants (10.79 vs. 11.97%; P = 0.40). Dietary selenium is not significantly correlated with microalbuminuria (P = 0.68) in the male population, whereas each 1 μg/day of increase in selenium consumption was independently associated with a 6h higher risk of microalbuminuria (OR = 1.006; 95% CI, 1.001-1.011, P = 0.01) in females.

Conclusion

According to our research, excessive selenium consumption is positively correlated with microalbuminuria in females with obesity, but not in males with obesity.

IgA Nephropathy: Current Understanding and Perspectives on Pathogenesis and Targeted Treatment

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide, with varied clinical and histopathological features between individuals, particularly across races. As an autoimmune disease, IgAN arises from consequences of increased circulating levels of galactose-deficient IgA1 and mesangial deposition of IgA-containing immune complexes, which are recognized as key events in the widely accepted "multi-hit" pathogenesis of IgAN. The emerging evidence further provides insights into the role of genes, environment, mucosal immunity and complement system. These developments are paralleled by the increasing availability of diagnostic tools, potential biomarkers and therapeutic agents. In this review, we summarize current evidence and outline novel findings in the prognosis, clinical trials and translational research from the updated perspectives of IgAN pathogenesis.

Blind Spot in the Radar of MEST-C Score: Type and Severity of Tubulointerstitial Nephritis in IgA Nephropathy

Background

The updated version of predictive classification for immunoglobulin A nephropathy (IgAN) prognosis "The Oxford Classification" identifies five histopathological features including mesangial hypercellularity (M), endocapillary proliferation (E), segmental glomerulosclerosis (S), tubular atrophy/interstitial fibrosis (T) and crescents (C), the MEST-C. However, few studies suggest that tubulointerstitial inflammation, which is not included in the MEST-C, is also linked to disease progression and is, consequently, a neglected determinant of prognosis among others. Therefore, there is a need to evaluate this histopathological parameter in patients with IgA nephropathy.

Materials and Methods

This cross-sectional descriptive study was conducted at Shaukat Khanum Memorial Cancer Hospital and Research Center, Lahore, Pakistan. Data of histopathological and immunofluorescence proven renal biopsies (300) of IgA nephropathy patients from January 2016 through May 2022 were extracted using a convenient sampling technique. Biopsies were histologically reviewed for type and severity of tubulointerstitial inflammation, in addition to the MEST-C score. Renal biopsies of patients who had a history of transplant, autolyzed tissue, no glomeruli on histological examination, and/or a tubular atrophy/interstitial fibrosis score of 2 (T2) in MEST-C scoring were excluded. Data were analyzed using SPSS 20. An association between the variables was analyzed using the chi-square and Fischer exact tests. A p value less than 0.05 was considered statistically significant.

Results

A total of 247/300 biopsies were eligible for inclusion. The mean age at the time of biopsy was 31.90 ± 12.48 with 63.6% in the age group between 21 and 40 years, and 69.6% were male. Tubulointerstitial inflammation was observed in 90.2% cases with 49.4% showing moderate while 4.5% showing severe degree of inflammation. A strong association of both the type and severity of tubulointerstitial inflammation was found with M, E, T, and C scores (p value < 0.05).

Conclusion

The high-frequency and strong statistical association of tubulointerstitial inflammation with the M, E, T, and C scores in our study elucidate its prognostic role in the progression and management of IgA nephropathy.

Genetic Variants of the COL4A3 , COL4A4 , and COL4A5 Genes Contribute to Thinned Glomerular Basement Membrane Lesions in Sporadic IgA Nephropathy Patients

BACKGROUND

Thinned glomerular basement membrane (tGBM) lesions are not uncommon in IgA nephropathy (IgAN). Type IV collagen-built of α 3, α 4, and α 5 chains, encoded by COL4A3 / COL4A4 / COL4A5 genes-is the major component of glomerular basement membrane (GBM). In recent years, mutations in type IV collagen-encoding genes were also reported in patients with a histologic diagnosis of FSGS. Pathogenic COL4A3 / COL4A4 / COL4A5 variants were recently identified in familial cases of IgAN, but the contribution of these variants to sporadic IgAN is still unclear.

METHODS

We compared 161 patients with sporadic IgAN with tGBM lesions (IgAN-tGBM) to matched patients with IgAN without tGBM lesions and matched patients with thin basement membrane nephropathy (TBMN). Variants of COL4A3 / COL4A4 / COL4A5 genes were screened and evaluated after whole-exome sequencing. GBM thickness was measured, and levels of circulating galactose-deficient IgA1 (Gd-IgA1) were assessed by ELISA.

RESULTS

The patients with IgAN-tGBM manifested milder disease than did patients with IgAN without tGBM but had more severe features than the patients with TBMN. Exome sequence analysis of the 122 patients with IgAN-tGBM identified 37 diagnostic variants of the COL4A3 / COL4A4 / COL4A5 genes among 38 patients (31.1%). Furthermore, patients with IgAN-tGBM who had diagnostic variants had higher proportions of GBM thickness <250 nm and milder glomerular injury, whereas patients with IgAN-tGBM who did not have diagnostic variants showed more characteristic features of IgAN, including higher intensity of glomerular IgA deposits and elevated Gd-IgA1 levels. These findings suggest different mechanisms in patients with versus without diagnostic variants of these collagen genes.

CONCLUSIONS

COL4A3 / COL4A4 / COL4A5 variant detection is essential in evaluating patients with sporadic IgAN with tGBM lesions.

A novel clinical-radiomic nomogram for the crescent status in IgA nephropathy

OBJECTIVE

We used machine-learning (ML) models based on ultrasound radiomics to construct a nomogram for noninvasive evaluation of the crescent status in immunoglobulin A (IgA) nephropathy.

METHODS

Patients with IgA nephropathy diagnosed by renal biopsy (n=567) were divided into training (n=398) and test cohorts (n=169). Ultrasound radiomic features were extracted from ultrasound images. After selecting the most significant features using univariate analysis and the least absolute shrinkage and selection operator algorithm, three ML algorithms were assessed for final radiomic model establishment. Next, clinical, ultrasound radiomic, and combined clinical-radiomic models were compared for their ability to detect IgA crescents. The diagnostic performance of the three models was evaluated using receiver operating characteristic curve analysis.

RESULTS

The average area under the curve (AUC) of the three ML radiomic models was 0.762. The logistic regression model performed best, with AUC values in the training and test cohorts of 0.838 and 0.81, respectively. Among the final models, the combined model based on clinical characteristics and the Rad score showed good discrimination, with AUC values in the training and test cohorts of 0.883 and 0.862, respectively. The decision curve analysis verified the clinical practicability of the combined nomogram.

CONCLUSION

ML classifier based on ultrasound radiomics has a potential value for noninvasive diagnosis of IgA nephropathy with or without crescents. The nomogram constructed by combining ultrasound radiomic and clinical features can provide clinicians with more comprehensive and personalized image information, which is of great significance for selecting treatment strategies.

IgA nephropathy diagnosed as a result of acute exacerbation due to G-CSF administration

Granulocyte colony-stimulating factor (G-CSF) is commonly used to stimulate bone marrow production. G-CSF is usually safe but sometimes causes serious adverse effects and, in rare cases, exacerbates glomerulonephritis. We report a case of immunoglobulin A (IgA) nephropathy that was aggravated by G-CSF. A 56-year-old Japanese man with no relevant medical history was admitted to our hospital as a donor of peripheral blood stem cells (PBSCs) for transplantation. To mobilize PBSCs, he received subcutaneous G-CSF (lenograstim), 500 μg for 4 days. Three days after the first dose of lenograstim, gross hematuria appeared, and after administration on the fourth day, renal dysfunction and nephrotic-range proteinuria were observed. Renal biopsy and light microscopic study revealed mild mesangial proliferation with expansion in association with the presence of cellular segmental crescents. Immunofluorescence study revealed diffuse, granular staining in the mesangium for IgA, complement component 3 (C3), and lambda light chains. We diagnosed highly active IgA nephropathy and initiated treatment with prednisolone and azathioprine. Three months later, renal function returned to normal. Screening for hidden chronic glomerulonephritis should be performed when G-CSF is administered, as in PBSC donors. Immunosuppressant therapy, such as prednisolone or azathioprine, is considered for exacerbations of highly active glomerulonephritis.

IgA nephropathy: an overview of drug treatments in clinical trials

INTRODUCTION

IgA nephropathy (IgAN) is the commonest primary glomerulonephritis worldwide and may progress to end-stage kidney disease (ESKD) within a 10-20 year period. Its slowly progressive course has made clinical trials challenging to perform, however the acceptance of proteinuria reduction as a surrogate end point has significantly improved the feasibility of conducting clinical trials in IgAN, with several novel and repurposed therapies currently undergoing assessment. Already, interim results are demonstrating value to some of these, offering great hope to those with IgAN.

AREAS COVERED

This review explores the rationale, candidates, clinical precedents, and trial status of therapies that are currently or have recently been evaluated for efficacy in IgAN. All IgAN trials registered with the U.S. National Library of Medicine; ClinicalTrials.gov were reviewed.

EXPERT OPINION

For the first time, effective treatment options beyond supportive care are becoming available for those with IgAN. This is the culmination of commendable international efforts and signifies a new era for those with IgAN. As more therapies become available, future challenges will revolve around deciding which treatments are most appropriate for individual patients, which is likely to push IgAN into the realm of precision medicine.

The Presence of ANCA in IgA Crescentic Nephropathy Does Not Lead to Worse Prognosis with Intensive Rescue Treatment

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis worldwide. The concomitant presence of both crescentic proliferation and anti-neutrophil cytoplasmic autoantibodies (ANCA) in this pathology represents a rare coincidence. However, it is not clear to what extent the presence of ANCA (IgA or IgG) in these patients could have any clinical significance. The aim of the current work is to describe the presence of ANCA (IgA or IgG) in patients with IgAN and crescentic proliferation and its possible clinical implications.

METHODS

We retrospectively recruited all patients in our center with a histological diagnosis of IgAN with crescentic proliferation between January 2013 and December 2020. The main demographic and clinicopathologic data, fundamental histological characteristics, as well as the treatments implemented and main kidney outcomes, were collected and analyzed at a 6 and 12-month follow-up.

RESULTS

Between January 2013 and December 2020, a total of 17 adults were diagnosed with concomitant crescentic proliferation through a kidney biopsy of IgAN. Five (29.4%) patients showed ANCA, three (60%) showed IgA-ANCA and two (40%) showed IgG-ANCA. All ANCA-positive patients had some degree of crescentic proliferation. At diagnosis, the mean age of patients was 48 years old (range: 27-75). Nine of them were women (52%) and the most common clinical presentation was hypertension (71%). At the time of biopsy, the mean serum creatinine and proteinuria were 2.2 mg/dL (DS 1.42) and 3.5 g/mgCr (DS 1.22), respectively, with no statistical differences between ANCA-positive and -negative patients. Histological analyses showed that 11 out of the 12 (91%) ANCA-negative IgAN patients displayed less than 25% cellular crescents, whereas 100% of ANCA-positive IgAN patients displayed more than 25% cellular crescents (p = 0.04). Notably, five (30%) patients displayed fibrinoid necrosis, with four of them (80%) being IgAN-ANCA-positive (p = 0.01). Only one ANCA-negative patient needed renal replacement therapy (RRT) upon admission (5%). The mean serum creatinine and proteinuria were 1.94 mg/dL (DS 1.71) and 1.45 g/gCr (DS 1.78), respectively, within 6 months of immunosuppressive therapy. At 12-month follow-up, the mean creatinine was 1.57 mg/dL (DS 1). Four (23.5%) patients needed RRT at the end of the follow-up and four (23.5%) patients died.

CONCLUSIONS

Probably due to the limited number of IgAN-ANCA-positive and IgAN-ANCA-negative patients, no significant differences were found between the clinical and laboratory characteristics. IgAN-ANCA-negative patients seemed to display less extracapillary proliferation than IgAN-ANCA-positive patients, who tended to show significantly higher fibrinoid necrosis. There were no differences regarding renal prognosis and patient survival after aggressive immunosuppressive therapy within 6 and 12 months when comparing the two samples.

Rapidly progressive IgA nephropathy: clinicopathological characteristics and outcomes assessed according to the revised definition of the KDIGO 2021 Guideline

BACKGROUND

Rapidly progressive immunoglobulin A nephropathy (RPIgAN) is a severe clinical phenotype of IgAN associated with a poor outcome. The recently published Kidney Disease: Improving Global Outcomes (KDIGO) 2021 Guideline for the Management of Glomerular Diseases has proposed a new definition for RPIgAN that is based simply on a ≥50% decline in the estimated glomerular filtration rate (eGFR) over ≤3 months.

METHODS

In 1677 IgAN patients followed at a single centre in China, we evaluated the utility of this new definition to identify the highest-risk IgAN patients who might be suitable for combination immunosuppressive therapy.

RESULTS

The proportion of a ≥50% decline in eGFR over ≤3 months was 5.2%. The majority of these patients had reversible causes, with only 2.3% (39/1677) meeting the KDIGO 2021 criteria for RPIgAN. These patients had a significantly higher risk for end-stage kidney disease (ESKD) than non-RPIgAN patients (logrank P < 0.001). RPIgAN was an independent risk factor for ESKD [hazard ratio 3.99 (95% confidence interval 2.25-7.09); P <0.001]. A minority of the RPIgAN patients (25.6%) had ≥50% crescents. There was no significant difference in the risk for ESKD between patients in the RPIgAN group with ≥50% crescents and ˂50% crescents (logrank P = 0.27). Patients with RPIgAN and ≥50% crescents had a higher risk for ESKD than patients with non-RPIgAN and ≥50% crescents (logrank P = 0.04).

CONCLUSIONS

These data support the validity of the KDIGO 2021 definition but require independent validation in other non-Chinese cohorts.

Mizoribine halts kidney fibrosis in childhood IgA nephropathy: association with modulation of M2-type macrophages

BACKGROUND

The immunosuppressant mizoribine (Miz) can reduce progression of childhood IgA nephropathy (IgAN). This study examined whether Miz affects CD163⁺ M2-type macrophages which are associated with kidney fibrosis in childhood IgAN.

METHODS

A retrospective cohort of 90 children with IgAN were divided into groups treated with prednisolone (PSL) alone (P group; n = 42) or PSL plus Miz (PM group; n = 48) for a 2-year period. Normal human monocyte-derived macrophages were stimulated with dexamethasone (Dex), or Dex plus Miz, and analyzed by DNA microarray.

RESULTS

Clinical and histological findings at first biopsy were equivalent between patients entering the P and PM groups. Both treatments improved proteinuria and haematuria, and maintained normal kidney function over the 2-year course. The P group exhibited increased mesangial matrix expansion, increased glomerular segmental or global sclerosis, and increased interstitial fibrosis at 2-year biopsy; however, the PM group showed no progression of kidney fibrosis. These protective effects were associated with reduced numbers of glomerular and interstitial CD163⁺ macrophages in the PM versus P group. In cultured human macrophages, Dex induced upregulation of cytokines and growth factors, which was prevented by Miz. Miz also inhibited Dex-induced expression of CD300E, an activating receptor which can prevent monocyte apoptosis. CD300e expression by CD163⁺ macrophages was evident in the P group, which was reduced by Miz treatment.

CONCLUSION

Miz halted the progression of kidney fibrosis in PSL-treated pediatric IgAN. This was associated with reduced CD163⁺ and CD163⁺CD300e⁺ macrophage populations, plus in vitro findings that Miz can suppress steroid-induced macrophage expression of pro-fibrotic molecules. A higher resolution version of the Graphical abstract is available as Supplementary information.

Structural modeling for Oxford histological classifications of immunoglobulin A nephropathy

In immunoglobulin A nephropathy (IgAN), Cox regression analysis can select independent prognostic variables for renal functional decline (RFD). However, the correlation of the selected histological variables with clinical and/or treatment variables is unknown, thereby making histology-based treatment decisions unreliable. We prospectively followed 946 Japanese patients with IgAN for a median of 66 mo. and applied structural equation modeling (SEM) to identify direct and indirect effects of histological variables on RFD as a regression line of estimated glomerular filtration rate (eGFR) via clinical variables including amount of proteinuria, eGFR, mean arterial pressure (MAP) at biopsy, and treatment variables such as steroid therapy with/without tonsillectomy (ST) and renin–angiotensin system blocker (RASB). Multi-layered correlations between the variables and RFD were identified by multivariate linear regression analysis and the model’s goodness of fit was confirmed. Only tubular atrophy/interstitial fibrosis (T) had an accelerative direct effect on RFD, while endocapillary hypercellularity and active crescent (C) had an attenuating indirect effect via ST. Segmental sclerosis (S) had an attenuating indirect effect via eGFR and mesangial hypercellularity (M) had accelerative indirect effect for RFD via proteinuria. Moreover, M and C had accelerative indirect effect via proteinuria, which can be controlled by ST. However, both T and S had additional indirect accelerative effects via eGFR or MAP at biopsy, which cannot be controlled by ST. SEM identified a systemic path links between histological variables and RFD via dependent clinical and/or treatment variables. These findings lead to clinically applicable novel methodologies that can contribute to predict treatment outcomes using the Oxford classifications.

Validation of two IgA nephropathy risk-prediction tools using a cohort with a long follow-up

BACKGROUND

Recently, two immunoglobulin A nephropathy prediction tools were developed that combine clinical and histopathological parameters. The International IgAN Prediction Tool predicts the risk for 50% declines in the estimated glomerular filtration rate or end-stage renal disease up to 80 months after diagnosis. The IgA Nephropathy Clinical Decision Support System uses artificial neural networks to estimate the risk for end-stage renal disease. We aimed to externally validate both prediction tools using a Norwegian cohort with a long-term follow-up.

METHODS

We included 306 patients with biopsy-proven primary immunoglobulin A nephropathy in this study. Histopathologic samples were retrieved from the Norwegian Kidney Biopsy Registry and reclassified according to the Oxford classification. We used discrimination and calibration as principles for externally validating the prognostic models.

RESULTS

The median patient follow-up was 17.1 years. A cumulative dynamic time-dependent receiver operating characteristic analysis showed area under the curve values of ranging from 0.90 at 5 years to 0.83 at 20 years for the International IgAN Prediction Tool, while time-naive analysis showed an area under the curve value at 0.83 for the IgA Nephropathy Clinical Decision Support System. The International IgAN Prediction Tool was well calibrated, while the IgA Nephropathy Clinical Decision Support System tends to underestimate risk for patients with higher risk, and overestimates risk in the lower risk categories.

CONCLUSIONS

We have externally validated two prediction tools for IgA nephropathy. The International IgAN Prediction Tool performed well, while the IgA Nephropathy Clinical Decision Support System has some limitations.

Assessing prognosis in IgA nephropathy

Assessing the prognosis is essential in chronic diseases, such as IgA nephropathy. The 2021 Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend the "International IgAN Prediction Tool" (available at www.qxmd.com) for this. The key limitation was that the tool was only validated at the time of the kidney biopsy. An improved algorithm is now described, which allows assessing the prognosis at 1 or 2 years after biopsy. Herein, we review the strengths, limitations, and potential clinical usefulness of this new prediction tool.

The Significance of Crescents on the Clinical Features and Outcomes of Primary Immunoglobin A Nephropathy

Background

It is still controversial whether the proportion of crescents below 50% can be an independent predictive risk factor for poor prognosis in IgAN patients. We reported the significance of different proportions of crescents on the clinical features and the cut-off value of crescents in predicting the occurrence of end-stage kidney disease (ESKD) in patients with IgAN.

Methods

We retrospectively analyzed biopsy-proven primary IgAN patients in Sichuan Provincial People’s Hospital from 2007 to 2019. The patients were divided into 5 groups on the basis of crescent proportion as follows: 0 (n = 647), < 10% (n = 221), 10 to 24% (n = 272), 25 to 49% (n = 80), and ≥50% (n = 22). The primary endpoint was defined as ESKD, and the secondary endpoint was the combined renal endpoint (≥50% reduction in eGFR or ESKD). A validation cohort of 346 patients were enrolled from Affiliated Hospital of Southwest Medical University. Cox regression model and Kaplan-Meier survival analysis were performed.

Results

A total of 1242 eligible patients with biopsy-proven IgAN were recorded in the database, compared with the non-crescent group, patients in the crescent group had lower levels of hemoglobin (Hb) and albumin (Alb), higher levels of blood urea nitrogen (BUN), 24h urinary protein and hematuria, a higher proportion of mesangial hypercellularity (M1), endocapillary hypercellularity (E1), segmental glomerulosclerosis (S1), and tubular atrophy/interstitial fibrosis (T1/T2) (p < 0.05). A higher crescent proportion was associated with lower levels of Hb, ALB, eGFR and serum IgG (p < 0.05), higher levels of SCr, BUN, increasing amounts of 24 h urinary protein, increasing proportion of M1 and E1, and increasing severity of interstitial inflammatory infiltration. During the median follow-up of 43 months (range 6-151), 63 individuals (7.0%) reached the primary outcome of ESKD and 99 patients (11.1%) reached the combined renal endpoint. 34(7.5%), 21 (13.3%), 24(12.2%), 14(21.5%) and 6(31.6%) patients reached the combined renal endpoint in the above five groups in crescents 0, <10%, 10∼24%, 25∼49% and ≥50%, respectively. A total of 274(62.6%) cases in the crescent group and 254 (55.7%) cases in the non-crescent group received immunosuppressive therapy. Multivariate Cox regression showed that crescents ≥50% was an independent risk factor for the progression of ESKD (p = 0.003) and crescents ≥25% was an independent risk factor for the combined renal endpoint(p < 0.001). The receiver operating characteristic curve showed that IgAN patients with crescents ≥43.7% had a higher risk of ESKD, even with immunosuppressants (Sensitivity = 75.7%,specificity = 89.6%,p < 0.001). This discovery cohort and the validation cohort further confirmed that patients with crescents <43.7% had better renal prognosis than those with crescents ≥43.7% in the whole group and those with immunosuppressants (p < 0.001).

Conclusion

IgAN patients with crescents had more severe clinicopathological features and poorer prognosis. Crescents ≥50% was an independent risk factor for the progression of ESKD and crescents ≥25% was an independent risk factor for ≥50% reduction in eGFR or ESKD in treated and untreated IgAN patients. Crescents ≥43.7% was an independent risk factor for ESKD in those with immunosuppressants.