Immunosuppressant Agents as Add-On Therapy Failed to Improve the Outcome of Immunoglobulin A Nephropathy with Crescent Score C1

INTRODUCTION

The renoprotective benefits of adding immunosuppressant therapy to corticosteroid (CS) treatment for immunoglobulin A nephropathy (IgAN) patients with less than 25% crescent formation (C1) remain uncertain, warranting further research.

METHODS

A retrospective study was conducted on IgAN patients with crescent C1 lesions confirmed by renal biopsy at Xinqiao Hospital between May 1, 2017, and May 1, 2020. Patients were stratified into either the CS treatment group or the CS combined with an additional immunosuppressant therapy group. Follow-up assessments were conducted within 24 months. Propensity score analysis was used to match patients receiving CS and CS + immunosuppressant drug treatment in a 1:1 ratio. Primary outcomes included changes in estimated glomerular filtration rate (eGFR) and urine albumin-to-creatinine ratio (UACR). Subgroup analyses were performed to evaluate the benefits of different populations. Composite endpoint outcomes comprised a 30% eGFR decrease, end-stage kidney disease (ESKD) necessitating dialysis or transplant, or kidney disease-related mortality. Adverse events were also compared between the two groups.

RESULTS

296 IgAN patients with C1 lesions were included in the analysis. Baseline characteristics indicated that IgAN patients in the CS + immunosuppressant group exhibited poorer renal function and higher UACR levels. Propensity score analysis effectively minimized the influence of baseline clinical characteristics, including age, serum creatinine, initial eGFR, UACR, and 24-h proteinuria. Both treatment groups demonstrated continuous eGFR improvement and significant UACR reduction during follow-up, especially at 6 months. However, no significant differences in eGFR and UACR reduction rates were observed between the two groups throughout the entire follow-up period, both before and after matching. Subgroup analysis revealed improved eGFR in both treatment groups, notably among patients with an initial eGFR below 90 mL/min/1.73 m2. Conversely, IgAN patients with C1 lesions and a cellular crescent ratio exceeding 50% treated with CS and immunosuppressant therapy experienced a significant improvement in renal function and a decline in urinary protein creatinine ratio. Composite endpoint outcomes did not significantly differ between the two groups, while the incidence of adverse events was comparable.

CONCLUSION

Our findings suggest that the addition of immunosuppressant therapy to corticosteroid monotherapy did not confer significant therapeutic advantages in patients with C1 lesions compared to CS monotherapy, although some specific patient populations appeared to derive modest benefits from this combined approach.

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.

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.

Microscopic hematuria as a risk factor for IgAN progression: considering this biomarker in selecting and monitoring patients

Hematuria-either macroscopic hematuria or asymptomatic microscopic hematuria-is a clinical feature typical but not specific for immunoglobulin A nephropathy (IgAN). The only biomarker supported by the Kidney Disease: Improving Global Outcomes group as a predictor of progression, identifying patients needing treatment, is proteinuria >1 g/day persistent despite maximized supportive care. However, proteinuria can occur in the setting of active glomerulonephritis or secondary to sclerotic renal lesions. Microscopic hematuria is observed in experimental models of IgAN after IgA-IgG immunocomplex deposition, activation of inflammation and complement pathways. Oxidative damage, triggered by hemoglobin release, is thought to contribute to the development of proteinuria and progression. Despite being a clinical hallmark of IgAN and having a rational relationship with its pathophysiology, the value of microscopic hematuria in assessing activity and predicting outcomes in patients with IgAN is still debated. This was partly due to a lack of standardization and day-to-day variability of microhematuria, which discouraged the inclusion of microhematuria in large multicenter studies. More recently, several studies from Asia, Europe and the USA have highlighted the importance of microhematuria assessment over longitudinal follow-up, using a systematic approach with either experienced personnel or automated techniques. We report lights and shadows of microhematuria evaluation in IgAN, looking for evidence for a more consistent consensus on its value as a marker of clinical and histological activity, risk assessment and prediction of treatment response. We propose that hematuria should be included as part of the clinical decision-making process when considering when to use immunosuppressive therapy and as part of criteria for enrollment into clinical trials to test drugs targeting the inflammatory reaction elicited by immune pathway activation in IgAN.

Is serum hemoglobin level an independent prognostic factor for IgA nephropathy?: a systematic review and meta-analysis of observational cohort studies

BACKGROUND

Decreased serum hemoglobin (Hb) level is associated with Immunoglobulin A nephropathy (IgAN) progression. However, whether serum Hb level is an independent prognostic factor of IgAN remains controversial. Herein, we aimed to investigate the prognostic value of serum Hb level in IgAN.

METHODS

The Cochrane Library, Embase, PubMed and Open Grey databases were systematically searched and reviewed. Kidney disease progression of IgAN was defined as a doubling of serum creatinine (SCr), a 30% reduction in estimated glomerular filtration rate (eGFR), end-stage renal disease (ESRD), or death. We evaluated the hazard ratio (HR) between serum Hb level and the incidence of kidney disease progression in IgAN before and after adjusting for relevant covariates.

RESULTS

We included nine studies with 10006 patients in the meta-analysis. As a continuous variable, we found that serum Hb was an independent prognostic factor of IgAN [unadjusted HR = 0.89, 95% confidence interval (CI) = 0.84-0.95, I² = 98%; adjusted HR = 0.85, 95% CI = 0.79-0.91, I² = 0%]. The sensitivity analysis confirmed the stability of these results. Consistently, as a dichotomous variable defined as the below/above cutoff for anemia, we observed a positive correlation between serum Hb and kidney disease progression in IgAN (unadjusted HR = 2.12, 95% CI = 1.44-3.12, I² = 79%; adjusted HR = 1.65, 95% CI = 1.20-2.27, I² = 0%).

CONCLUSION

Serum Hb level was independently correlated with the incidence of kidney disease progression in IgAN.

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.

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.

Clinicopathologic features in childhood-onset lupus nephritis with antineutrophil cytoplasmic antibody positivity--a multi-center retrospective study

BACKGROUND

Positive antineutrophil cytoplasmic antibody (ANCA) serology in adult-onset lupus nephritis (LN) is associated with more active disease and distinct renal pathology, but data with respect to childhood-onset LN remain scarce. Here, we aimed to determine the impact of positive ANCA serology on clinical and histopathologic features and renal outcomes in children with LN from multiple centers.

METHODS

Clinical and histopathologic data of 61 ANCA-positive and 330 ANCA-negative LN children (1<age≤18 years) retrospectively enrolled from three pediatric nephrology centers were analyzed. Among them, 217 children were followed and survival analysis was performed.

RESULTS

Among 61 ANCA-positive LN children, 86.9% of them had antimyeloperoxidase antibodies. Both ANCA-positive and ANCA-negative children had high disease activities with median SLEDAI-2K of 16 (13, 20). Hematuria was more prominent (urinary RBC +++ ∼ ++++: 45.9% vs 26.7%, p = 0.011), while fever (42.6% vs. 58.2%, p = 0.035), alopecia (3.3% vs. 14.5%, p = 0.019), photosensitivity (0% vs. 8.2%, p = 0.013), and pleurisy (4.9% vs. 15.8%, p = 0.026) were less common in ANCA-positive children. Higher proportions of segmental sclerosis (23.7% vs. 9.8%, p = 0.025), crescentic formation (36.4% vs. 16.3%, p = 0.009), and capillary wall thickening (24.5% vs. 11.0%, p = 0.01) were observed in biopsies of ANCA-positive children. Long-term renal survival did not differ significantly between two groups (p = 0.300).

CONCLUSIONS

Positive ANCA serology in LN children was associated with different clinical and histopathologic features compared to those with negative ANCA serology. Further studies are needed to clarify the pathogenic role of ANCAs in childhood-onset LN and confirm their association with prognosis.

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.

Crescents and IgA Nephropathy: A Delicate Marriage

IgA nephropathy (IgAN) is a progressive disease with great variability in the clinical course. Among the clinical and pathologic features contributing to variable outcomes, the presence of crescents has attracted particular interest as a distinct pathological feature associated with severity. Several uncontrolled observations have led to the general thought that the presence and extent of crescents was a prognostic indicator associated with poor outcomes. However, KDIGO 2021 guidelines concluded that either the presence or the relative number of crescents should not be used to determine the progression of IgAN nor should they suggest the choice of immunosuppression. Our aim is to report and discuss recent data on the debated issue of the value of active (cellular and fibrocellular) crescents in the pathogenesis and clinical progression of IgAN, their predictive value, and the impact of immunosuppression on renal function. We conclude that the value of crescents should not be disregarded, although this feature does not have an independent predictive value for progression in IgAN, particularly when considering immunosuppressed patients. An integrated overall evaluation of crescents with other active MEST scores, clinical data, and novel biomarkers must be considered in achieving a personalized therapeutic approach to IgAN patients.

Clinicopathological characteristics, risk factors and renal outcome in IgA nephropathy with crescents

BACKGROUND/AIMS

The aim of the study was to investigate the clinicopathological characteristics, risk factors and renal outcome in IgA nephropathy (IgAN) patients with crescents.

METHODS

Four hundred and fifty-eight biopsy-proven primary IgAN patients included between January 2010 and October 2021 for a retrospective analysis were divided into three groups according to crescent score of the updated Oxford classification: C0 group (n = 255), C1 group (n = 187) and C2 group (n = 16). The clinicopathological features and renal outcomes were recorded. In univariate and multivariate models, the association between crescents and renal outcome and C2-associated clinical factors were analyzed.

RESULTS

Patients with a higher proportion of crescents presented worse clinical characteristics with regard to kidney function, proteinuria, hematuria, hemoglobin, uric acid, cholesterol, and serum albumin, while global glomerulosclerosis, segmental adhesion, tuft necrosis, segmental glomerulosclerosis (S1), tubular atrophy/interstitial fibrosis (T1/2), and lymphocyte and monocyte infiltration were more severe. By multivariate logistic regression analysis, eGFR (OR 0.981, 95% CI 0.964-0.999, P = 0.039), proteinuria (OR 1.655, 95% CI 1.180-2.321, P = 0.004), and hematuria (OR 4.752, 95% CI 1.426-15.835, P = 0.011) were significantly associated with C2. C2 was significantly associated with poorer renal survival even in patients receiving immunosuppressive therapy. Nevertheless, only eGFR at baseline, rather than crescents, was an independent predictor for renal survival in multivariate Cox analyses.

CONCLUSION

IgAN patients with crescents presented more severe clinical and pathological features. Renal function, proteinuria and hematuria contributed to identifying patients with crescents. Crescents were associated with poorer renal survival, even in patients receiving immunosuppressive therapy, but it was not an independent predictor.

The effectiveness and safety of corticosteroid therapy for IgA nephropathy with crescents: a prospective, randomized, controlled study

Background

Pozzi protocol (methylprednisolone intravenous infusion in 1st-3rd-5th months and oral steroid for 6 months) has been thought to be the classic therapy for IgA nephropathy (IgAN) patients with proteinuria> 1.0 g/24 h. There is no consensus on the treatments for IgAN with active pathological changes, especially for IgAN patients with crescents proportion < 50%. This study aimed to evaluate the effectiveness and safety of the treatment protocol of methylprednisolone intravenous infusion at the 1st-2nd-3rd months for IgAN patients with crescents.

Methods

In this prospective, randomized, controlled, non-blind study, 68 IgAN patients with crescents proportion < 50% were divided into the 1–2-3 group receiving 0.25 g/d methylprednisolone intravenously for 3 consecutive days in the 1st-2nd-3rd months, and oral prednisone 0.5 mg/kg/d on consecutive days for 6 months and the 1–3-5 group with the same intravenous methylprednisolone treatment in the 1st-3rd-5th months, and the same oral prednisone. The primary outcome measure was remission of proteinuria (complete or partial); while the secondary outcome measures were deterioration of renal function (evidenced by a 50% rise from baseline serum creatinine levels, or a 25% decline from baseline eGFR levels).

Results

There was no significant difference in incidence of crescents (median 14.66% vs. 11.45%, p = 0.143) between the 1–2-3 and 1–3-5 groups. From month 1 to month 6, there was a decreasing trend in the levels of urine protein and serum creatinine and an increasing trend in eGFR in both groups. The mean period of remission in the 1–2-3 group seemed shorter. Overall, there were 55 (80.89%) patients meeting remission. The rates of remission in the 1–2-3 group and 1–3-5 group were 85.3 and 76.47%, respectively (P = 0.644). The 1–2-3 group had lower creatinine and higher eGFR than the 1–3-5 group, but the difference was not significant. The complication rate was 11.11 and 15.79% in the two groups, respectively. There was no significant difference in the complications between groups.

Conclusions

Both the 1st-3rd-5th and 1st-2nd-3rd protocols can effectively alleviate proteinuria and protect renal function in IgAN patients with crescents but the 1st-2nd-3rd protocol seemed to have better effectiveness.

Trial registration

ClinicalTrials.gov, Identifier: NCT02160132, Registered June 10, 2014.

Randomized clinical study to evaluate the effect of personalized therapy on patients with immunoglobulin a nephropathy

Background

Randomized controlled trials (RCTs) have been conducted, stratifying idiopathic immunoglobulin A nephropathy (IgAN) patients based on the laboratory findings [serum creatinine, estimated glomerular filtration rate (eGFR) and daily proteinuria]. In contrast, data from kidney biopsy have been used only for clinical diagnosis. Therefore, IgAN patients with active or chronic renal lesions have been receiving the same therapy in experimental and control arms of randomized clinical trials (RCTs).

Methods

Our clinical study of IgAN (CLIgAN) is a multicentre, prospective, controlled and open-label RCT based on patients’ stratification at the time of their kidney biopsy. We will consider, first, the type of renal lesions, followed by serum creatinine values, eGFR and proteinuria. Primary and secondary endpoints will be monitored. Then, we will determine whether personalized therapy can slow the decline of renal function and delay end-stage kidney disease.

Results

We will enrol 132 IgAN patients with active renal lesions (66 patients per arm) in the first RCT (ACIgAN). They will receive corticosteroids combined with renin–angiotensin system blockers (RASBs) or only RASBs. A total of 294 IgAN patients with chronic or moderate renal lesions at high or very high risk of chronic kidney disease (147 patients per arm) will be enrolled in the second RCT (CHRONIgAN), in which they will receive dapagliflozin, a sodium–glucose cotransporter 2 inhibitor, combined with RASBs, or RASBs alone.

Conclusion

Using this approach, we hypothesize that patients could receive personalized therapy based on renal lesions to ensure that the right drug gets to the right patient at the right time.

Clinicopathological characteristics and prognosis of patients with IgA nephropathy and renal vasculitic lesions

BACKGROUND

We studied patients with IgA nephropathy (IgAN) and compared those with and without renal vasculitic lesions (RVLs).

METHODS

From January 2006 to December 2011, patients with biopsy-proven primary IgAN at our institution were retrospectively examined and assigned to an RVL group or a no-RVL group. RVLs were defined as thromboses in arteries and/or arterioles, necrosis of capillary loops, crescent formation, and fibrinoid necrosis of small blood vessels. The association of RVLs with clinical outcomes was analyzed using multivariate models. The primary composite endpoint was end-stage renal disease or doubling of serum creatinine.

RESULTS

There were 1570 patients, 50.2% (788) with RVLs and 49.8% (782) without RVLs. The RVL group was younger; had shorter disease course, more severe proteinuria and hematuria, worse renal function; and were prescribed more steroids and/or immunosuppressants. The RVL group had a greater prevalence of global glomerular sclerosis, more crescents, and a higher Oxford classification grade. A total of 501 patients in the RVL group (50.7%) and 487 in the no-RVL group (49.3%) completed follow-up. The RVL group was more likely to reach the composite endpoint after 1, 3, and 5 years (all P < 0.001). Proteinuria, anemia, low eGFR, and global and segmental sclerosis were independent predictors of progression to the composite endpoint in patients with RVLs.

CONCLUSIONS

Almost half of our IgAN patients had RVLs, and these patients were younger and had worse renal function, with more severe proteinuria, hematuria, and severe pathologic lesions. IgAN patients with RVLs had worse renal outcomes than those without RVLs.

Increasing prescription of renin-angiotensin-aldosterone system blockers associated with improved kidney prognosis in Korean IgA nephropathy patients

BACKGROUND

We aimed to describe the characteristics of immunoglobulin A nephropathy (IgAN) in Korea with assessment for time trends.

METHODS

We performed a multicenter retrospective observational cohort study including biopsy-confirmed native IgAN cases from four tertiary hospitals in Korea. Time eras of diagnosis were stratified into 1979-2003, 2004-9 and 2010-17. The prognostic variable was progression to end-stage kidney disease (ESKD) analyzed by multivariable Cox regression analysis.

RESULTS

We included 1366 (from 1979 to 2003), 1636 (from 2004 to 2009) and 1442 (from 2010 to 2017) IgAN patients in this study. In the recent periods, IgAN had relatively better clinical characteristics, as patients had higher estimated glomerular filtration rates and lower baseline blood pressures than before. The use of renin-angiotensin-aldosterone system (RAAS) blockers increased from 57.7% in 1979-2003 to 80.0% in 2010-17. During a median follow-up duration of 11.3 years, 722 patients progressed to ESKD with an incidence rate of 12.5 per 1000 person-years. The 10-year risk of progression to ESKD was lower in 2010-17 compared with that of 1979-2003 [adjusted hazard ratio 0.692 (95% confidence interval 0.523-0.915)], even after adjustment for multiple clinicopathologic characteristics. The use of RAAS blockers was a significant mediator (P < 0.001) for the association between time trends and lower 10-year ESKD risk.

CONCLUSIONS

Clinicopathologic characteristics of IgAN in Korea have changed over time. Although the limitation of a retrospective observational study remains, the result showed that the prognosis of IgAN has improved over the study period, possibly related to increased prescription of RAAS blockers.

Validation of an international prediction model including the Oxford classification in Korean patients with IgA nephropathy

BACKGROUND

Recently, a new international risk prediction model including the Oxford classification was published which was validated in a large multi-ethnic cohort. Therefore, we aimed to validate this risk prediction model in Korean patients with IgA nephropathy.

METHODS

This retrospective cohort study was conducted with 545 patients who diagnosed IgA nephropathy with renal biopsy in three medical centers. The primary outcome was defined as a reduction in estimated glomerular filtration rate (eGFR) of >50% or incident end-stage renal disease (ESRD). Continuous net reclassification improvement (cNRI) and integrated discrimination improvement (IDI) were used to validate models.

RESULTS

During the median 3.6 years of follow-up period, 53 (9.7%) renal events occurred. In multivariable Cox regression model, M1 (hazard ratio [HR], 2.22; 95% confidence interval [CI], 1.02-4.82; p = .043), T1 (HR, 2.98; 95% CI, 1.39-6.39; p = .005) and T2 (HR, 4.80; 95% CI, 2.06-11.18; p < .001) lesions were associated with increased risk of renal outcome. When applied the international prediction model, the area under curve (AUC) for 5-year risk of renal outcome was 0.69, which was lower than previous validation and internally derived models. Moreover, cNRI and IDI analyses showed that discrimination and reclassification performance of the international model was inferior to the internally derived models.

CONCLUSION

The international risk prediction model for IgA nephropathy showed not as good performance in Korean patients as previous validation in other ethnic group. Further validation of risk prediction model is needed for Korean patients with IgA nephropathy.

Clinical and prognostic significance of C1q deposition in IgAN patients-a retrospective study

BACKGROUND/AIM

IgA nephropathy (IgAN) is the most prevalent primary glomerular disease worldwide and is responsible for 45-50% of primary glomerular diseases in China. We are essentially dependent on the degree of proteinuria to determine prognosis and it has been reported that histopathologic lesions are risk factors for the progression of IgAN. The aim of this study was to investigate the clinicopathologic features and prognosis of IgAN with C1q deposition in adult Chinese patients.

METHODS

The patients of primary IgAN diagnosed by renal biopsy from January 2002 to December 2018 at the Second Hospital of Shanxi Medical University were retrospectively analyzed and divided into C1q deposit group and C1q negative group according to glomerular immunofluorescence examination. We evaluated their serologic and histopathologic findings. We collected data of patients during January 1, 2015 to December 31, 2018 and performed the clinical follow-up until the patient's estimated glomerular filtration rate (eGFR) decreased by more than 30%, entering end-stage renal disease (ESRD). Kaplan-Meier survival analysis was used to evaluate the cumulative incidence of renal progression in two groups. Univariate and multivariate Cox proportional hazard regression models were used to analyze the effect of C1q deposition on the prognosis of patients with IgA nephropathy.

RESULTS

The baseline data of total 491 cases were available and 172 cases had the follow-up data. The baseline eGFR and plasma albumin (ALB) levels in C1q deposit group were lower than those in the C1q negative group, while the levels of serum creatinine (Scr), total cholesterol (TC), 24 h urine protein, low-density lipoprotein (LDL), β2 microglobulin, etc. were higher than those in C1q negative group (all P < 0.05). Pathological indexes: glomerular segment sclerosis and adhesion (S), renal tubular atrophy/interstitial fibrosis (T), and cell/fibroblastic crescent (C) scores in C1q deposit group were higher than those in C1q negative group (all P < 0.05). With a median follow-up time of 32.5 (24,42) months, a total of 18 patients (C1q deposit: 11; C1q negative: 7) developed to endpoints. Kaplan-Meier survival curve analysis showed that there was significant decrease in cumulative incidence of renal progression between the two groups (Log-rank test χ2 = 4.78, P = 0.029). Cox regression analysis showed that the risk of renal end-point events in IgAN patients with C1q deposit group was 6.35 times higher than that in C1q negative group (HR = 6.35, 95% CI: 1.21-33.30, P = 0.029).

CONCLUSION

The clinical and renal pathological changes of IgAN patients with C1q deposition are more severe than those of C1q negative patients, and has a worse outcome. C1q deposition is an independent risk factor for the progression of renal function and contributes to a poor renal prognosis in adult IgAN patients.

RNA-Seq profiling of microdissected glomeruli identifies potential biomarkers for human IgA nephropathy

Few studies have examined gene expression changes occurring in the glomeruli of IgA nephropathy (IgAN) using a sensitive transcriptomic profiling method such as RNA sequencing (RNA-Seq). We collected glomeruli from biopsy specimens from patients with IgAN with relatively preserved kidney function (estimated glomerular filtration rate ≥ 60 mL·min^-1·1.73 m^-2 and urine protein-to-creatinine ratio < 3 g/g) and from normal kidney cortexes by hand microdissection and performed RNA-Seq. Differentially expressed genes were identified, and gene ontology term annotation and pathway analysis were performed. Immunohistochemical labeling and primary mesangial cell cultures were performed to confirm the findings of RNA-Seq analysis. Fourteen patients with IgAN and ten controls were included in this study. Glomerulus-specific genes were highly abundant. Principal component analysis showed clear separation between the IgAN and control groups. There were 2,497 differentially expressed genes, of which 1,380 were upregulated and 1,117 were downregulated (false discovery rate < 0.01). The enriched gene ontology terms included motility/migration, protein/vesicle transport, and immune system, and kinase binding was the molecular function overrepresented in IgAN. B cell signaling, chemokine signal transduction, and Fcγ receptor-mediated phagocytosis were the canonical pathways overrepresented. In vitro experiments confirmed that spleen tyrosine kinase (SYK), reported as upregulated in the IgAN transcriptome, was also upregulated in glomeruli from an independent set of patients with IgAN and that treatment with patient-derived IgA1 increased the expression of SYK in mesangial cells. In conclusion, transcriptomic profiling of the IgAN glomerulus provides insights in the intraglomerular pathophysiology of IgAN before it reaches profound kidney dysfunction. SYK may have a pathogenetic role in IgAN.

Crescents formations are independently associated with higher mortality in biopsy-confirmed immunoglobulin A nephropathy

BACKGROUND AND OBJECTIVES

Immunoglobulin A Nephropathy (IgAN) is the most common type of glomerulonephritis with variable renal outcome. The association between IgAN and patient survival is limited. The effect of crescents on patient survival was never studied.

MATERIALS

We conducted a retrospective cohort study between January 2003 and December 2013. All patients with the biopsy-proved IgAN was enrolled for the analysis of patient survival and renal survival. Cox regression model was used analyze the associated factors for patient survival.

RESULTS

All 388 participants with IgAN were enrolled, in which 45 patients with crescents. The mean percentage of glomeruli involvement was 23±18.9%. After long-term follow-up, crescents group had both worse renal (p = 0.034) and patient survivals (p = 0.016). In univariate Cox regression model, the age (HR = 1.08, 95% CI = 1.05-1.12, p<0.001), crescents (HR = 3.93, 95% CI = 1.18-13.07, p = 0.025), serum albumin (HR = 0.023, 95%CI = 0.11-0.50, p<0.001), blood total protein (HR = 0.46, 95%CI = 0.28-0.75, p = 0.002), HDL (HR = 0.95, 95%CI = 0.91-0.99, p = 0.009), daily urine protein (HR = 1.14, 95%CI = 1.01-1.29, p = 0.038), urine PCR (HR = 1.07, 95%CI = 1.02-1.12, p = 0.003), serum IgM (HR = 0.98, 95%CI = 0.96-1.00, p = 0.036), BUN (HR = 1.02, 95%CI = 1.01-1.02, p = 0.005), and eGFR (HR = 0.097, 95%CI = 0.94-0.99, p = 0.0011) were associated with patient survival. After multivariate Cox regression analysis, age (HR = 1.08, 95%CI = 1.01-1.13, p = 0.013), crescents (HR = 5.57, 95%CI = 1.14-29.05, p = 0.034), and HDL (HR = 0.94, 95%CI = 0.90-0.99, p = 0.026) were associated with patient survival. Crescents IgAN is with the highest risk (up to 5.75 of HR) for patient mortality.

CONCLUSIONS

The major strengths of the present study is that crescents IgAN had worse patient survival compared to non-crescents IgAN. Clinicians should be more careful to care patients with crescents IgAN.

Validation of the revised Oxford classification for IgA nephropathy considering treatment with corticosteroids/immunosuppressors

The Oxford classification for IgA nephropathy (IgAN) was updated in 2017. We have validated the revised Oxford classification considering treatment with corticosteroids/immunosuppressors. In this retrospective analysis, 871 IgAN patients were enrolled. Patients were divided into two groups, those treated with or without corticosteroids/immunosuppressors. The 20-year renal prognosis up to end-stage renal disease was assessed using the Oxford classification. In all patients, the renal survival rate was 87.5% at 10 years and 72.6% at 20 years. The T score alone was significantly related to renal prognosis in the Kaplan–Meier analysis and multivariate Cox regression analysis. In the non-treatment group (n = 445), E, S, T, and C scores were significantly related to renal survival rates, however, in the treatment group (n = 426), T score alone was significantly related to renal prognosis on Kaplan–Meier analysis, indicating that corticosteroids/immunosuppressors improved renal prognosis in E1, S1, and C1. In patients with E1, S1, or C1, the treatment group showed significantly better renal prognosis than the non-treatment group in univariate and multivariate analysis. The Oxford classification and T score were used to determine renal prognosis in IgAN patients. Corticosteroids/immunosuppressors improved renal prognosis, especially E1, S1, and C1 scores.

Clinical course of Immunoglobulin A nephropathy with crescents in a multi-ethnic Southeast Asian cohort

AIM

Clinical presentation and course of Immunoglobulin A nephropathy vary by ethnicity and geography and significance of extracapillary proliferation or crescents (IgAN-C) in Southeast Asia is not well described. We aimed to describe the clinical course of IgAN-C in Singapore.

METHODS

Retrospective cohort study of adult biopsy-proven IgAN diagnosed between February 2011 and October 2016 in 2 hospital-based nephrology units. Outcome was chronic kidney disease (CKD) progression, defined as reduction in eGFR ≥50% or end stage renal failure (ESRF).

RESULTS

One hundred and forty-five patients were studied. Among individuals with IgAN-C (n = 44, 30%), 38 patients had cellular or fibrocellular crescents in 1 to 25% of the glomeruli and 6 had crescents in >25%. Median eGFR was 54 (33, 83) mL/min/1.73 m² . Compared to IgAN without crescents, IgAN-C had greater proteinuria (median 2.9 [1.4, 5.4] g/g vs 1.9 [1.1, 3.6] g/g, P = .03) and more had endocapillary hypercellularity (96% vs 39%, P < .001). IgAN-C were also more likely to receive immunosuppressants (66% vs 43%, P = .01) such as prednisolone (63% vs 38%, P = .006) and cyclophosphamide (12% vs 2%, P = .03). Median follow up was 27 (12, 46) months. IgAN-C were more likely to achieve proteinuria reduction ≥50% at 6 months (66% vs 44%, P = .03). CKD progression within 12 months was not different among those with and without crescents (13% vs 10% respectively, P = .73). However, immunosuppressant treatment of IgAN-C was associated with reduced ESRF (0 vs 20%, P = .03).

CONCLUSION

Immunosuppressants may attenuate the risk of ESRF in IgAN-C.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Complement activation is associated with crescent formation in IgA nephropathy

IgA nephropathy (IgAN) is common chronic glomerulonephritis with variable prognosis, ranging from minor urinary abnormalities to end-stage renal disease. The revised Oxford classification of IgAN explains that cellular/fibrocellular crescents are associated with poor renal prognosis, proposing an extension to the MEST-C score. C3 immunofluorescent staining follows a distribution similar to IgA staining. Therefore, complement activation was reported to play a pivotal role in IgAN pathogenesis. This study included 132 IgAN patients diagnosed by renal biopsies. The clinical parameters at the time of the biopsies were obtained from patient data records. We classified the patients into C ≥ 1 and C0 groups, and compared clinical, light microscopic, and immunofluorescent features. In the C ≥ 1 group, 2 (1.5%) and 31 (23.5%) patients were assigned to C2 and C1, respectively. The remaining 99 patients (75%) were classified as C0. The C ≥ 1 group had lower average age and rate of hypertension, and higher score of urinary occult blood and E score. The C ≥ 1 group had significantly higher average immunofluorescence scores for IgA, C5b-9, mannose-associated serine protease (MASP) 1/3, MASP2, properdin, factor B, and kappa. The steroid use rate was significantly higher in the C ≥ 1 group. During the follow-up period of 2.90 years on average, the rate of renal dysfunction was not significantly different between groups. Crescent formation in IgAN was associated with activation of the lectin and alternative pathways. The C ≥ 1 group had significantly increased use of steroids, which probably caused comparable renal function during the follow-up period.