A clinicopathological comparison between IgA nephropathy and Henoch–Schönlein purpura nephritis in children: use of the Oxford classification

Comparative study on clinicopathological features and prognosis of IgA vasculitis nephritis and IgA nephropathy in children

BACKGROUND

IgA vasculitis nephritis (IgAVN) and IgA nephropathy (IgAN) share several clinical and pathological characteristics, though distinctions also exist. Their interrelation, however, remains undefined. This study investigates the clinicopathological divergences and prognostic disparities in pediatric patients with IgAVN and IgAN.

METHODS

Our study encompasses 809 pediatric patients with IgAVN and 236 with IgAN, all of whom underwent kidney biopsy. We utilized the Semiquantitative Classification (SQC) scoring system to juxtapose the pathologies of the two conditions, and performed a COX regression analysis to examine factors influencing their prognoses.

RESULTS

Both patient groups demonstrated a predominance of males. A seasonality was observed, with a higher incidence of IgAN in the summer, and IgAVN in the fall (P < 0.0001). Patients with IgAN exhibited more severe tubulointerstitial injury, higher chronicity index, and total biopsy scores compared to those with IgAVN (P < 0.0001). Mesangial deposition intensity of complement C3, and the rate of pure IgA deposition, were found to be greater in patients with IgAVN compared to those with IgAN (P < 0.0001). The intensity of IgA deposition was also significantly higher in IgAVN patients (P = 0.003). IgAVN demonstrated a superior prognosis, with a higher rate of kidney remission (P < 0.0001). COX regression analysis indicated that interstitial fibrosis, as identified in the SQC pathology system, was associated with the prognosis of both conditions. Furthermore, the findings suggest that IgA deposition levels (IgA +  + and IgA +  + +) could potentially influence the prognosis of IgAVN.

CONCLUSIONS

Compared to IgAVN, IgAN manifests more severely with regard to renal impairment, interstitial damage, and prognosis. The disparities in immune complex deposition levels and locations within the kidneys support the hypothesis of IgAVN and IgAN as distinct diseases. Interstitial fibrosis may serve as a key pathological indicator within the SQC system associated with kidney prognosis in children with IgAVN and IgAN. The degree of IgA deposition could also be linked with the prognosis of IgAVN.

Diagnosis and treatment of IgA nephropathy and IgA vasculitis nephritis in Chinese children

IgA nephropathy (IgAN) and IgA vasculitis-associated nephritis (IgAVN) are among the most frequent childhood glomerular diseases and are characterized by significant variability in clinical manifestations, pathological presentation and long-term outcomes. IgAVN, alternatively called purpura nephritis, is pathologically indistinguishable from kidney-limited IgAN. In Chinese children, the clinical presentations and pathological manifestations of IgAN and IgAVN are variable. The severity of proteinuria and abnormalities in kidney function and blood pressure of children in China are comparable to those of children in Europe, the USA, and Japan. Compared to Caucasian children and Japanese children, crescents were more common in Chinese children with IgAN or IgAVN. Approximately 10-20% of childhood IgAN or IgAVN progresses to impaired kidney function in China. Since 2007, a series of guidelines on the diagnosis and treatment of pediatric kidney diseases has been published following the principles of evidence-based medicine. However, a large difference exists between the Chinese evidence-based guidelines and the guidelines developed by Kidney Disease: Improving Global Outcomes (KDIGO) in 2021. Chinese children with IgAN or IgAVN were more likely to be treated with steroids or immunosuppressive agents. Further studies exploring the optimal treatment regimen for childhood IgAN or IgAVN are needed in the future.

A modern approach to the morphological assessment of nephritis in Henoch–Schonlein purpura (IgA-vasculitis)

The authors analyzed clinical and morphological correlations between the manifestations and outcome in nephritis with Henoch– Schönlein purpura and assessed the effect of morphological data on achieving remission as per ISKDC, SQC, MEST-C classification.Patients and methods. 32 patients with nephritis in Henoch–Schönlein purpura (15 girls and 17 boys) were enrolled into retrospective longitudinal single-center study, median of primary admission to the nephrological department was 9.0 y. o. [5; 12 y.]. Clinical features of the onset (age, form of onset, glomerular filtration rate, daily proteinuria, hematuria, serum IgA level) and the course of the disease were analyzed in all children. The morphological data were assessed using such morphological classifications as ISKDC, SQC, MEST-C. A search for statistically significant relationships between clinical and morphological data and a comparative analysis of the influence of each morphological classification on the achievement of remission were carried out.Results. The sum of the SQC scores had a statistically significant effect on the outcome (p=0.006): in patients with complete remission, on average, 4 points were obtained, patients who did not achieve remission had 2 points more. When assessing the likelihood of detecting remission depending on the total score of the Oxford scale using the ROC-analysis, a statistically significant model was obtained (p=0.012). If the total MEST-C score was less than or equal to 3, remission was predicted (=0.032). The sensitivity and specificity of the method were both 75%.Conclusions. The practical application of the Oxford MEST-C classification and the new semi-quantitative SQC classification in comparison with the ISKDC classification for children with nephritis in Henoch–Schönlein purpura is promising for predicting an unfavorable renal outcome.

Contrast-enhanced ultrasonography for assessing histopathology in pediatric immunoglobulin A nephropathy and Henoch-Schönlein purpura nephritis

BACKGROUND

Glomerular disease, including immunoglobulin A nephropathy (IgAN) and Henoch-Schönlein purpura nephritis, is one of the most common kidney diseases in children. The diagnosis of these diseases depends on pathological biopsy, although this procedure is seriously limited by its invasive and high-risk nature.

OBJECTIVE

To investigate the potential of contrast-enhanced ultrasonography (CEUS) for evaluating the histopathological severity of IgAN and Henoch-Schönlein purpura nephritis (HSPN).

MATERIALS AND METHODS

We investigated a total of 13 children with IgAN and 12 children with HSPN confirmed by renal histopathology. We reevaluated the pathological lesions of the children according to the Oxford classification and the Lee grading system and then all the children underwent CEUS. Using SonoLiver software, we constructed time-intensity curves of CEUS for regions of interest in the renal cortex. We analyzed CEUS quantitative parameters for IgAN and HSPN and used Spearman correlation analysis to examine the correlation between CEUS parameters and clinicopathological indexes in the study cohort.

RESULTS

The CEUS parameters rise time (RT) and time to peak (TTP) were significantly higher in children with Lee grade IV than in those with Lee grades II or III. Spearman correlation analysis revealed a positive correlation between rise time and time to peak with Lee grade in the overall cohort of children, and a positive correlation between rise time and time to peak and severity of crescents in the Oxford classification scoring system.

CONCLUSION

Contrast-enhanced US may be used as a noninvasive imaging technique to evaluate the severity of renal pathology and formation of crescents in children with IgAN and HSPN.

Comparison of clinical, pathological and long-term renal outcomes of children with Henoch-Schonlein purpura nephritis and IgA nephropathy

PURPOSE

To compare clinical, pathological, and long-term renal outcomes of children with Henoch-Schonlein purpura nephritis (HSPN) and IgA nephropathy (IgAN).

METHODS

The medical records of patients diagnosed as HSPN and IgAN during childhood were evaluated retrospectively. HSPN and IgAN groups were compared in terms of gender, age, upper respiratory infection history, blood pressure; presence of nephrotic and/or nephritic syndrome; hemoglobin level, leukocyte count, C-reactive protein (CRP), serum albumin (sAlb), creatinine, complement 3 (sC3), complement 4 (sC4) and immunoglobulin A (sIgA) levels; estimated glomerular filtration rate (eGFR) and proteinuria levels; and renal pathology findings at the onset of disease; total follow-up time; and blood pressure, eGFR and proteinuria levels at the last visit.

RESULTS

Fifty-four patients were enrolled in the study [38 (70%) HSPN and 16 (30%) IgAN]. The median follow-up time was 60.5 and 72.0 months in HSPN and IgAN groups, respectively (p > 0.05). The HSPN and IgAN groups were also not different in terms of gender, age at the onset; leukocyte count, eGFR, sC3-sC4-sIgA levels; and the presence of endocapillary, extracapillary and mesangial proliferation, tubular atrophy, interstitial fibrosis and IgA, IgM, C3 accumulation in renal tissue. Upper respiratory tract infection history was more common in children with IgAN (8/16 vs 8/38, p = 0.045). sAlb (3.96 ± 0.58 vs 4.40 ± 0.46 g/dL, p = 0.005), hemoglobin (12.1 ± 1.3 vs 13.3 ± 1.2 g/dL, p = 0.004,) and the incidence of mesangial IgG deposition (15/38 vs 11/16, p = 0.049) were lower, while CRP (16.3 ± 7.2 vs 7.8 ± 4.4 mg/L, p = 0.002) and proteinuria (72.1 ± 92.4 vs 34.2 ± 37.9 mg/m²/24 h, p = 0.041) was higher in HSPN group at the onset of disease. Proteinuria and eGFR were similar between the two groups at last visit.

CONCLUSION

Children with HSPN and IgAN have little clinical and histological differences in our population. The most prominent difference at presentation with nephritis was higher proteinuria in HSPN probably associated with inflammation due to systemic vasculitis. Long-term renal outcome was good in both HSPN and IgAN.

Immunoglobulin A nephropathy in paediatrics: An up-to-date

Immunoglobulin A nephropathy is the main cause of glomerulonephritis globally and an important aetiology of end-stage renal disease in children. It has been considered an autoimmune disease that can lead to the production of autoantibodies against abnormal IgA1 and formation of immune complexes. These autoantibodies and immune complexes deposit in the glomeruli, resulting in renal injury. At the beginning of IgA nephropathy course, most patients are asymptomatic and the first clinical manifestations in children are macroscopic hematuria and proteinuria. The diagnosis is defined by the detection of IgA mesangial deposits in kidney biopsy using immunofluorescence techniques. The Oxford MEST-C score is the most used classification to associate histological findings and clinical outcomes, being validated for application in children. Recommended treatment options are antihypertensive and antiproteinuric therapy, corticosteroids, immunosuppressive agents, and other non-pharmacological approaches. There is no ideal prognosis indicator but new perspectives are in science's scope to find possible biomarkers of the disease through OMICS's research. This review aims to summarize and to up-to-date the scientific literature on paediatric IgA nephropathy, focusing on pathophysiology, clinical findings, histopathology, current treatment, prognosis, and future perspectives.

IgA Vasculitis and IgA Nephropathy: Same Disease?

Many authors suggested that IgA Vasculitis (IgAV) and IgA Nephropathy (IgAN) would be two clinical manifestations of the same disease; in particular, that IgAV would be the systemic form of the IgAN. A limited number of studies have included sufficient children or adults with IgAN or IgAV (with or without nephropathy) and followed long enough to conclude on differences or similarities in terms of clinical, biological or histological presentation, physiopathology, genetics or prognosis. All therapeutic trials available on IgAN excluded patients with vasculitis. IgAV and IgAN could represent different extremities of a continuous spectrum of the same disease. Due to skin rash, patients with IgAV are diagnosed precociously. Conversely, because of the absence of any clinical signs, a renal biopsy is practiced for patients with an IgAN to confirm nephropathy at any time of the evolution of the disease, which could explain the frequent chronic lesions at diagnosis. Nevertheless, the question that remains unsolved is why do patients with IgAN not have skin lesions and some patients with IgAV not have nephropathy? Larger clinical studies are needed, including both diseases, with a common histological classification, and stratified on age and genetic background to assess renal prognosis and therapeutic strategies.

Predictability of the Oxford classification of IgA nephropathy in Henoch-Schonlein purpura nephritis

BACKGROUND

Whether the Oxford classification of immunoglobulin A nephropathy can be utilized to predict the adverse renal outcome of Henoch-Schonlein purpura nephritis (HSPN) has been long-debated. We, therefore, performed a meta-analysis to evaluate the prognostic value of Oxford classification lesions in HSPN.

METHODS

We systematically searched Medline, EMBASE, Web of Science, and the Cochrane Library for articles published from January 1970 to August 2020. Cohort and case-control studies investigating the correlation between the Oxford classification and renal outcome were included, the quality of which was assessed by the Newcastle-Ottawa scale criteria. The pooled odds ratios (ORs) with their 95% confidence intervals (CIs) were calculated with a random-effects model or a fixed-effects model depending on the heterogeneity.

RESULTS

A total of 485 papers were reviewed and eventually 9 comparisons were included, providing data of 1688 patients with HSPN. ORs for adverse renal events were 2.83 (95% CI 1.84-4.35; P < 0.001), 1.96 (95% CI 1.28-2.98; P < 0.05), and 5.45 (95% CI, 3.15-9.45; P < 0.001) for patients with lesions of endocapillary hypercellularity (E), segmental sclerosis (S), and tubular atrophy /interstitial fibrosis (T), respectively, without significant heterogeneity (E: I² = 0.0%; P = 0.498; S: I² = 22.4%; P = 0.258; T: I² = 33.6%; P = 0.171). Subgroup analysis adjusted for age also supported the results that E, S, and T lesions could serve as poor predictors (P < 0.05). Additionally, crescents (C) were strongly associated with renal outcome (OR 2.22; 95% CI 1.62-3.04; P < 0.001), with moderate heterogeneity (I² = 49.3%; P = 0.066). However, it should be noted that it is not the presence but the proportions of crescent lesions that were related to the high risk of progression to adverse renal events, because the predictability of lower rates of crescent (C1, with crescents > 0 and ≤ 25%) was uncertain (OR 2.21; 95% CI 0.75-6.51; P > 0.05). Although the pooled OR revealed that lesions of mesangial hypercellularity (M) were correlated with poor renal prognosis (OR 2.41; 95% CI 1.07-5.43; P < 0.05), subgroup analysis separating children from adults indicated that there seemed to be no significant difference.

CONCLUSIONS

Oxford classification, especially for E, S, T, and C, might be recommended for patients with HSPN, regardless of children and adults.

[Efficacy and safety of mycophenolate mofetil versus cyclophosphamide in the treatment of Henoch-Schönlein purpura nephritis with nephrotic-range proteinuria in children: a prospective randomized controlled trial]

OBJECTIVE

To study the efficacy and safety of mycophenolate mofetil (MMF) versus cyclophosphamide (CTX) in the treatment of children with Henoch-Schönlein purpura nephritis (HSPN) and nephrotic-range proteinuria.

METHODS

A prospective clinical trial was conducted in 68 pediatric patients who were admitted to the Department of Nephrology, Children's Hospital Affiliated to Capital Institute of Pediatrics and who were diagnosed with HSPN and nephrotic-range proteinuria from August 2016 to November 2019. The patients were randomly divided into two groups:MMF treatment (n=33) and CTX treatment (n=35). The two groups were compared in terms of complete remission rate, response rate (complete remission + partial remission), urinary protein clearance time, and adverse events.

RESULTS

At months 3, 6, and 12 of treatment, there was no significant difference in the complete remission rate and the response rate between the MMF treament and CTX treatment groups (P > 0.05). There was also no significant difference between the two groups in the urinary protein clearance time and the incidence rate of adverse events (P > 0.05).

CONCLUSIONS

MMF and CTX have similar efficacy and safety in the treatment of HSPN children with nephrotic-range proteinuria.

IgA vasculitis (Henoch-Schönlein purpura) nephritis and psoriasis in a child: is there a relationship?

Background

Psoriasis is a chronic immune-mediated disorder that primarily affects the skin in both adults and children but can also have systemic involvement, particularly with arthritis and kidney injury. IgA nephropathy is the most frequent kidney disorder associated with psoriasis. Approximately one third of all cases of psoriasis begin in childhood, but association between psoriasis and renal disorders has scarcely been reported in pediatric patients. Henoch-Schönlein purpura (HSP) is a systemic vasculitis characterized by IgA deposits in the vessel walls of affected organs and in the mesangium of the kidney. HSP nephritis histopathology is identical to IgA nephropathy.

Case report

A 6-year-old boy with recent onset of psoriasis developed HSP with kidney involvement, clinically manifested by nephrotic-range proteinuria and hematuria. Kidney biopsy revealed fibrocellular glomerular crescents and mesangial IgA deposits compatible with IgA nephropathy. Treatment with systemic corticosteroids led to the control of hematuria, but as nephrotic-range proteinuria persisted, cyclophosphamide was added, leading to a gradual decrease in proteinuria.

Conclusions

We propose an underlying common mechanism in the pathogenesis of both HSP and psoriasis, involving a dysregulation of the IgA-mediated immune response, which could predispose to both entities as well as to kidney damage and IgA nephropathy in these patients.

Using MEST-C Scores and the International Study of Kidney Disease in Children Classification to Predict Outcomes of Henoch-Schönlein Purpura Nephritis in Children

Introduction: Henoch-Schönlein purpura nephritis (HSPN) and IgA nephropathy (IgAN) bear similarities in some aspects. The histological classification of HSPN was built on the International Study of Kidney Disease in Children (ISKDC) criteria, while IgAN was established on the 2016 Oxford classification (MEST-C scores). The purpose of this paper was to discuss the predictive value of the ISKDC classification and MEST-C scores in children with HSPN. Methods: We performed a retrospective study of 877 children with HSPN in a single center between 2001 and 2019. The primary outcome was defined as chronic kidney disease-estimated glomerular filtration rate (eGFR) <90 ml/min/1.73 m². Results: During the follow-up period of 23.3 (10.9-47.9) months, 51 (5.8%) patients reached the primary outcome. As revealed in a Kaplan-Meier plot, segmental glomerulosclerosis (S) (P < 0.001) and tubular atrophy/interstitial fibrosis (T) (P < 0.001) significantly predict poor renal outcome. Other Oxford lesions and the ISKDC classification, however, did not show a significant difference in a worse outcome. In a multivariate Cox model adjusted for pathological and clinical factors, eGFR [hazard ratio (HR) = 2.831, 95% confidence interval (95% CI) = 1.359-5.896], S lesion (HR = 3.936, 95% CI = 2.078-7.457), and T lesion (HR = 4.002, 95% CI = 1.733-9.242) were independent risk factors for the renal outcome. Conclusion: This series constitutes the largest series reported so far in the literature of such patients. According to our findings, S and T of the Oxford classification, which are ignored by the ISKDC classification, could be applied to predict the renal prognosis of children with HSPN.

Global Glomerulosclerosis and Segmental Glomerulosclerosis Could Serve as Effective Markers for Prognosis and Treatment of IgA Vasculitis With Nephritis

Background: This study was aimed at investigating the clinical significance and curative effect of global glomerulosclerosis (GS) and segmental glomerulosclerosis (S) in adult-onset IgA vasculitis with nephritis (IgAV-N) patients since there was no consensus pathological grading method for adult IgAV-N. Methods: A total of 188 biopsy-proven IgAV-N patients were prospectively identified. Patients were separately assigned to GS0/GS1/GS2 group and S0/S1/S2 based on the scores of global glomerulosclerosis and segmental glomerulosclerosis (0% /0-15% />15%, respectively). Results: GS0, GS1, and GS2 occurred in 56.4, 29.2, and 14.4% of the adult-onset IgAV-N, respectively. Patients in GS2 group tended to have the most serious renal deterioration and the highest levels of blood pressure. IgAV-N patients were also divided into S0 group (64.4%), S1 group (20.7%), and S2 group (14.9%), where no obvious differences in baseline data were noted. K-M curves indicated that GS2 group had the worst renal outcome (P = 0.05) while there seemed to be no significant differences between GS0 group and GS1 group. In addition, no remarkable differences in primary outcome were found among S0 group, S1 group, and S2 group though the prognosis of S2 group tended to be the worst. However, the prognosis of S0/S1 group was markedly better than that of S2 (P = 0.04). The discrimination of poor prognosis could be improved by adding the pathological indicators of global glomerulosclerosis and segmental glomerulosclerosis. Most importantly, immunosuppressive treatment might be a superior alternative in IgAV-N patients without sclerosis scores or with lower level of sclerosis scores. But addition of immunosuppression was not recommended in patients with higher sclerosis scores. Conclusions: Global glomerulosclerosis and segmental sclerosis might be used for management and treatment of adult-onset IgAV-N.

Use of liquid chromatography-tandem mass spectrometry to perform urinary proteomic analysis of children with IgA nephropathy and Henoch-Schönlein purpura nephritis

The emerging technology of urinary proteomics has become an efficient biological approach for identifying biomarkers and characterizing pathogenesis in renal involvement. In this study, we attempted to elucidate the relationship between IgAN and HSPN in children, employing LC-MS/MS to perform urinary proteomic analyses using the DIA method. Early-morning spot urine was collected from patients with biopsy-proven IgAN (n = 19) and HSPN (n = 19) prior to treatment and renal biopsy in the Department of Pediatrics, Jinling Hospital, Nanjing, China, and did healthy volunteers (n = 14), from June 2018 to December 2019. Two hundred seventy-six urinary proteins and 125 urinary proteins were determined to be differentially expressed in children with IgAN (n = 4) and HSPN (n = 4), respectively, compared to the urinary proteins of healthy children (n = 4) (p < 0.05). GO analysis demonstrated that the differentially expressed proteins of the two groups, which were located in the extracellular matrix and cell membrane, were primarily involved in biological processes, including metabolic processes, immune system processes, cellular adhesion, cell proliferation, signaling, and biological regulation. KEGG analysis revealed that the differentially expressed proteins of the two groups were associated with cell adhesion molecules, ECM-receptor interactions, the PI3K-Akt signaling pathway, the complement and coagulation cascades, regulation of actin cytoskeleton, cholesterol metabolism, and platelet activation. The target proteins (alpha-1B-glycoprotein (A1BG) and afamin (AFM)), which participated in the complement and coagulation cascades and the regulation of complement activation, were further investigated in the independent validation cohort by ELISA. These proteins were significantly increased in children with IgAN (n = 15) and HSPN (n = 15) compared with the proteins observed in healthy controls (n = 10, P < 0.05). The validated results were consistent with the mass spectrometry results. SIGNIFICANCE: IgAN and HSPN both result from the glomerular deposition of abnormally glycosylated IgA1 with mesangial proliferative changes, and both diseases are common glomerulopathies in the pediatric population that are believed to be correlated. Interestingly, our data, by combining urinary proteomic analyses, showed that several uniform enrichment pathways played an important role in the progression of IgAN and HSPN, suggesting that we might reduce the renal involvement of the two diseases in children through these pathways. The same urinary proteins along these pathways were observed to be differentially expressed in children with IgAN and HSPN, implying that these proteins may be potential biomarkers to identify the two diseases. Future studies examining larger cohorts are warranted to confirm the validity of our findings.

Age-adjusted global glomerulosclerosis predicts renal progression more accurately in patients with IgA nephropathy

The Oxford classification was developed to predict the outcome of IgA nephropathy (IgAN). Based on the upper reference limit (95^th percentile) for the number of globally sclerotic glomeruli (GSG) expected on biopsy according to age, we evaluated whether the prognosis of IgAN was affected by the age-calibrated numbers of GSG independent of the Oxford classification. Patients diagnosed with IgAN on renal biopsy in a single center from January 2011 to December 2018 were analyzed retrospectively. Patients with more GSG number than the upper reference limit expected on biopsy according to age were categorized in a group of GSG abnormal for age. We analyzed in two ways, calculating the median rate of decline in estimated glomerular filtration rate (eGFR) and time-to-event defined as a decline of eGFR level to 40% lower than the baseline. There were 111 patients in the group of GSG abnormal for age. In this group, the rate of eGFR decline was faster by 1.85 (3.68–0.03) ml/min/1.73 m² per year in the fully-adjusted robust regression model. The adjusted hazard ratio for eGFR decline for renal outcome was 29.10 (2.18–388.49). The cumulative incidence of CKD progression was significantly higher, especially for those with T score of 0 in the Oxford classification. We suggest that GSG abnormal for age is an independent risk factor in predicting the renal outcome of IgAN.