Serial Galactose-Deficient IgA1 Levels in Children with IgA Nephropathy and Healthy Controls

Examining the association between serum galactose-deficient IgA1 and primary IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

IgA nephropathy (IgAN) is a common primary glomerular disease. The O-glycosylation status of IgA1 plays a crucial role in disease pathophysiology. The level of poorly-O-galactosylated IgA1, or galactose-deficient IgA1 (Gd-IgA1), has also been identified as a potential biomarker in IgAN. We sought to examine the value of serum Gd-IgA1 as a biomarker in IgAN, by investigating its association with clinical, laboratory, and histopathological features of IgAN.

METHODS

The review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations and was registered in PROSPERO (CRD42021287423). The literature search was conducted in PubMed, Web of Science, Cochrane, and Scopus, and the selected articles were evaluated for eligibility based on predefined criteria. The methodological quality of the studies was assessed using the Newcastle-Ottawa Scale. Statistical analysis was performed to calculate effect sizes and assess heterogeneity among the studies.

RESULTS

This review analyzed 29 out of 1,986 studies, conducted between 2005 and 2022, with participants from multiple countries. Gd-IgA1 levels were not associated with age and gender, while associations with hypertension, hematuria, and proteinuria were inconsistent. In the meta-analyses, a correlation between serum Gd-IgA1 and estimated glomerular filtration rate was identified, however, the relationships between Gd-IgA1 levels and chronic kidney disease (CKD) stage and progression to kidney failure were inconsistent.

CONCLUSIONS

Serum Gd-IgA1 levels were not associated with validated prognostic risk factors, but were negatively correlated with kidney function. Further research in larger studies using standardized assays are needed to establish the value of Gd-IgA1 as a prognostic risk factor in IgAN.

Measurement of galactosyl-deficient IgA1 by the monoclonal antibody KM55 contributes to predicting patients with IgA nephropathy with high risk of long-term progression

BACKGROUND AND OBJECTIVE

About 25% of patients with IgA nephropathy (IgAN) progress to stage 5 chronic kidney disease (CKD) after years of evolution. Various tools have been developed in recent years designed to predict which of the patients will had poorer outcomes. The value of circulating galactosyl-deficient IgA1 (Gd-IgA1) has been related to a worse evolution of IgAN in several studies. There are also some publications that relate higher APRIL values with a worse evolution. Recently, a new method has been developed that allows measuring the value of circulating Gd-IgA1 in a simpler way than those previously available. The objective of this study is to analyze the influence of circulating Gd-IgA1, measured by this method, on the progression of IgAN.

MATERIALS AND METHODS

Forty-nine patients with a diagnosis of IgAN demonstrated by renal biopsy were selected in our center, without having received prior immunosuppressive treatment, for whom frozen serum was available. The median follow-up was 4 years. Gd-IgA1 was measured by lectin-independent ELISA with the monoclonal antibody KM55 (IgA1 kit Cat. No. 30111694. IBL Int., Hamburg, Germany). Likewise, APRIL levels were also measured in these patients.

RESULTS

19 (38.8%) patients reached stage 5 CKD. The fourth quartile of circulating Gd-IgA1 was related to a higher cumulative risk of reaching stage 5 CKD in the Kaplan-Meier analysis (risk at the 5th year 39.4% vs. 24.3%, log rank p=0.019). The Gd-IgA1 value was related to an increased risk of CKD stage 5 (HR 1.147, 95% CI 1.035-1.270, p=0.009), regardless of glomerular filtration rate, proteinuria, the percentage of sclerosed glomeruli and the value of segmental sclerosis. We did not find significant differences in the APRIL values.

CONCLUSIONS

The value of circulating Gd-IgA1 measured by the monoclonal antibody KM55 is related to a worse evolution of patients with IgAN independently of other variables, so it could be included in the study of patients to improve the prediction of the risk of disease progression.

[Measurement of galactosyl-deficient IgA1 by the monoclonal antibody KM55 contributes to predicting patients with IgA nephropathy with high risk of long-term progression]

BACKGROUND AND OBJECTIVE

About 25% of patients with IgA nephropathy (IgAN) progress to stage 5 chronic kidney disease (CKD) after years of evolution. Various tools have been developed in recent years designed to predict which of the patients will had poorer outcomes. The value of circulating galactosyl-deficient IgA1 (Gd-IgA1) has been related to a worse evolution of IgAN in several studies. There are also some publications that relate higher APRIL values with a worse evolution. Recently, a new method has been developed that allows measuring the value of circulating Gd-IgA1 in a simpler way than those previously available. The objective of this study is to analyze the influence of circulating Gd-IgA1, measured by this method, on the progression of IgAN.

MATERIALS AND METHODS

Forty-nine patients with a diagnosis of IgAN demonstrated by renal biopsy were selected in our center, without having received prior immunosuppressive treatment, for whom frozen serum was available. The median follow-up was 4 years. Gd-IgA1 was measured by lectin-independent ELISA with the monoclonal antibody KM55 (IgA1 kit Cat. No. 30111694. IBL Int., Hamburg, Germany). Likewise, APRIL levels were also measured in these patients.

RESULTS

19 (38.8%) patients reached stage 5 CKD. The fourth quartile of circulating Gd-IgA1 was related to a higher cumulative risk of reaching stage 5 CKD in the Kaplan-Meier analysis (risk at the 5th year 39.4% vs. 24.3%, log rank p=0.019). The Gd-IgA1 value was related to an increased risk of CKD stage 5 (HR 1.147, 95% CI 1.035-1.270, p=0.009), regardless of glomerular filtration rate, proteinuria, the percentage of sclerosed glomeruli and the value of segmental sclerosis. We did not find significant differences in the APRIL values.

CONCLUSIONS

The value of circulating Gd-IgA1 measured by the monoclonal antibody KM55 is related to a worse evolution of patients with IgAN independently of other variables, so it could be included in the study of patients to improve the prediction of the risk of disease progression.

MicroRNA‑196b targets COSMC in pediatric IgA nephropathy

The aim of the present study was to investigate the effect of microRNAs (miRNAs) on the expression level of core1β3‑galactosyltransferase‑specific molecular chaperone (COSMC) in immunoglobulin A nephropathy (IgAN). miRNA expression levels were determined in pediatric patients with IgAN (IgAN group), in patients with other renal diseases (control group) and healthy pediatrics (control group). The target miRNAs of COSMC were investigated in the present study. Western blot analysis was performed to examine the effects of miRNAs on COSMC expression levels. In addition, galactose‑deficient IgA1 (Gd‑IgA1) expression levels were detected following the addition of miRNA‑196b. The present results suggested that the expression levels of 205 miRNAs significantly differed between the IgAN and healthy control groups. The present results also suggested that miRNA‑196b and miRNA‑33a‑3p targeted COSMC, and that miRNA‑196b expression in B lymphocytes was significantly higher in the IgAN group compared with the control group (P<0.0001). However, COSMC expression level was significantly downregulated in isolated B lymphocytes transfected with miRNA‑196b mimics, but Gd‑IgA1 expression levels were increased. Therefore, miRNA‑196b may play a role in the formation of Gd‑IgA1 and IgAN pathogenesis via COSMC regulation.

Significance of serum galactose deficient IgA1 as a potential biomarker for IgA nephropathy: A case control study

Background

IgA nephropathy(IgAN) is a common glomerular disease with a higher risk of progression to end stage renal disease (ESRD) in certain ethnic populations. Since galactose deficient IgA1(Gd-IgA1) is a critical molecule in its pathogenesis, it has generated interest as a biomarker for this disease.

Methods

We measured serum Gd-IgA1 levels using a non- lectin based enzyme linked immunoassay(ELISA) in 136 immunosuppression naïve patients with primary IgAN and 110 controls(60-non IgA glomerular diseases, 50-healthy volunteers).

Results

Median serum Gd-IgA1 levels were significantly higher in IgAN patients [13135.6(2723.3,59603.8)ng/ml] compared to those with non IgA glomerular disease [4954.8(892.9,18256.2) ng/ml] and healthy controls [6299.5(1993.2,19256) ng/ml] and this was observed even after log transformation and adjustment for age and gender(p<0.0001). Considering a cut-off value of serum Gd-IGA1≥7982.1ng/ml, the sensitivity for diagnosing IgAN compared to healthy controls was 74.3% and specificity was 72.0% with a positive predictive value of 87.8% and negative predictive value of 50.7%. The serum Gd-IgA1 level did not co-relate with baseline estimated glomerular filtration rate, urine protein creatinine ratio and the M, E, S, T and C scores on renal biopsy. The renal survival (absence of >30% decrease in eGFR, ESRD or death) was lower in patients with higher serum Gd-IgA1 levels(≥7982ng/ml) than those who had lower levels but it was not statistically significant(p = 0.486).

Conclusion

Serum Gd-IgA1 level is higher in IgAN patients compared to non-IgA glomerular diseases and healthy controls and has a good positive predictive value for diagnosis. However, it does not correlate with clinical and histological characteristics of disease severity and does not predict disease progression.

[Value of galactose-deficient IgA1 in the early diagnosis of Henoch-Schönlein purpura nephritis in children]

OBJECTIVE

To explore the value of galactose-deficient IgA1 (Gd-IgA1) in the early diagnosis of Henoch-Schönlein purpura nephritis (HSPN) in children.

METHODS

A total of 67 hospitalized children who were definitely diagnosed with HSPN between January and April 2018 and 58 hospitalized children with Henoch-Schönlein purpura (HSP) were enrolled in the study. Twenty children undergoing routine physical examinations served as controls. The levels of serum and urine Gd-IgA1 were determined using ELISA. The receiver operating characteristic curve was used to analyze the value of serum Gd-IgA1 and urine Gd-IgA1/urine creatinine ratio in the diagnosis of HSPN.

RESULTS

The level of serum Gd-IgA1 and urine Gd-IgA1/urine creatinine ratio in children with HSP or HSPN were significantly higher than those in healthy control group (P<0.01), with a significantly greater increase observed in children with HSPN (P<0.01). Serum Gd-IgA1 ≥1 485.57 U/mL and/or urine Gd-IgA1/urine creatinine ratio ≥105.74 were of favorable value in the diagnosis of HSPN. During the six-month follow-up of the 49 children with HSP, the incidence of HSPN was 47% (23/49), which included a 100% incidence in children with serum Gd-IgA1 ≥1 485.57 U/mL and a 73% incidence in children with urine Gd-IgA1/urine creatinine ratio ≥105.74.

CONCLUSIONS

Serum and urine Gd-IgA1 is of favorable clinical value in the early diagnosis of HSPN.

[Value of galactose-deficient IgA1 in the early diagnosis of Henoch-Schönlein purpura nephritis in children]

OBJECTIVE

To explore the value of galactose-deficient IgA1 (Gd-IgA1) in the early diagnosis of Henoch-Schönlein purpura nephritis (HSPN) in children.

METHODS

A total of 67 hospitalized children who were definitely diagnosed with HSPN between January and April 2018 and 58 hospitalized children with Henoch-Schönlein purpura (HSP) were enrolled in the study. Twenty children undergoing routine physical examinations served as controls. The levels of serum and urine Gd-IgA1 were determined using ELISA. The receiver operating characteristic curve was used to analyze the value of serum Gd-IgA1 and urine Gd-IgA1/urine creatinine ratio in the diagnosis of HSPN.

RESULTS

The level of serum Gd-IgA1 and urine Gd-IgA1/urine creatinine ratio in children with HSP or HSPN were significantly higher than those in healthy control group (P<0.01), with a significantly greater increase observed in children with HSPN (P<0.01). Serum Gd-IgA1 ≥1 485.57 U/mL and/or urine Gd-IgA1/urine creatinine ratio ≥105.74 were of favorable value in the diagnosis of HSPN. During the six-month follow-up of the 49 children with HSP, the incidence of HSPN was 47% (23/49), which included a 100% incidence in children with serum Gd-IgA1 ≥1 485.57 U/mL and a 73% incidence in children with urine Gd-IgA1/urine creatinine ratio ≥105.74.

CONCLUSIONS

Serum and urine Gd-IgA1 is of favorable clinical value in the early diagnosis of HSPN.

Clinical significance of serum and mesangial galactose-deficient IgA1 in patients with IgA nephropathy

Introduction

Galactose-deficient IgA1 (Gd-IgA1) is a critical pathogenic factor for IgA nephropathy (IgAN), but its value as a disease-specific biomarker remains controversial. We aimed to clarify the clinical significance of Gd-IgA1 in patients with IgAN.

Methods

We retrospectively reviewed 111 patients who were diagnosed with IgAN based on the findings of renal biopsies (RB) at Showa University Hospital since 2007. Serum Gd-IgA1 (s-Gd-IgA1) at the time of RB was compared among 111 IgAN patients, 18 Henoch-Schönlein purpura nephritis (HSPN) patients, 29 lupus nephritis (LN) patients, 28 ANCA-associated vasculitis (AAV) patients, and 13 minimal change disease (MCD) patients using ELISA with an anti-human Gd-IgA1-specific monoclonal antibody (KM55). We also immunohistochemically stained paraffin-embedded sections for mesangial Gd-IgA1 (m-Gd-IgA1) deposition using KM55.

Results

Although levels of s-Gd-IgA1 were comparable among IgAN and HSPN, s-Gd-IgA1 levels were significantly elevated in patients with IgAN compared with LN, AAV and MCD (IgAN vs. HSPN, LN, AAV, and MCD: 16.2 ± 9.1 vs. 14.2 ± 10.8, p = 0.263; 12.7 ± 9.4, p = 0.008; 13.1 ± 7.3, p = 0.059; and 8.2 ± 4.8 μg/mL, p<0.001, respectively). Mesangial-Gd-IgA1 deposition was specifically detected in IgAN or HSPN. The increase in s-Gd-IgA1 significantly correlated with m-Gd-IgA1 positivity in patients with IgAN, and s-Gd-IgA1 elevation and m-Gd-IgA1 deposition were evident in patients with histopathologically advanced IgAN. Moreover, s-Gd-IgA1 levels were significantly higher in IgAN patients with glomerular sclerosis and tubulo-interstitial lesions. Mesangial-Gd-IgA1 intensity negatively correlated with eGFR in IgAN. Multivariate analysis selected s-Gd-IgA1 elevation as a significant risk factor for a 30%-reduction in eGFR in IgAN (HR, 1.37; 95% CI, 1.02–1.89; p = 0.038).

Conclusions

Although IgAN and HSPN remain difficult to differentiate, s-Gd-IgA1 elevation and m-Gd-IgA1 deposition are reliable diagnostic factors that reflect IgAN severity. Serum-Gd-IgA1 could serve as a predictor of renal outcomes in IgAN. Thus, Gd-IgA1 could be significant biomarker for patients with IgAN.