Recent advances in risk prediction, therapeutics and pathogenesis of IgA nephropathy

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.

Effects and mechanisms of Chinese herbal medicine on IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN), is the main cause of end-stage renal disease, that causes serious physical and psychological burden to patients worldwide. Some traditional treatment measures, such as blocking the renin-angiotensin-aldosterone system, controlling blood pressure, and following a low-protein diet, may not achieve satisfactory results. Therefore, more effective and safe therapies for IgAN are urgently needed.

PURPOSE

The aim of this review is to summarize the clinical efficacy of Chinese herbal medicines (CHMs) and their active ingredients in the treatment and management of IgAN based on the results of clinical trials, systematic reviews, and meta-analyses, to fully understand the advantages and perspectives of CHMs in the treatment of IgAN.

STUDY DESIGN AND METHODS

For this review, the following electronic databases were consulted: PubMed, ResearchGate, Science Direct, Web of Science, Chinese National Knowledge Infrastructure and Wanfang Data, "IgA nephropathy," "traditional Chinese medicine," "Chinese herbal medicine," "herb," "mechanism," "Meta-analysis," "systematic review," "RCT" and their combinations were the keywords to search the relevant literature. Data were collected from 1990 to 2022.

RESULTS

This review found that the active ingredients of CHMs commonly act on multiple signaling pathways in the clinical treatment of IgAN, mainly with antioxidant, anti-inflammatory and anti-fibrosis effects, and regulation of autophagy.

CONCLUSION

Compared with the single-target therapy of modern medicine, CHMs can regulate the corresponding pathways from the aspects of anti-inflammation, anti-oxidation, anti-fibrosis and autophagy to play a multi-target treatment of IgAN through syndrome differentiation and treatment, which has good clinical efficacy and can be used as the first choice or alternative therapy for IgAN treatment. This review provides evidence and research direction for a comprehensive clinical understanding of the protective effect of Chinese herbal medicine on IgAN.

Dyslipidemia may be a risk factor for progression in children with IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is often chronically progressive and commonly accompanied by dyslipidemia. However, the intrinsic relationship between dyslipidemia and IgAN remains to be elucidated. This study aimed to investigate the impact of different types of dyslipidemia on clinical and pathological characteristics in children with IgAN.

METHODS

In our retrospective cohort study from January 2006 to January 2021, 276 children with IgAN were ultimately included in the baseline analysis, and 169 were included in the follow-up analysis. The clinical and pathological features of different types of dyslipidemia and their effect on kidney prognosis were analyzed.

RESULTS

Children in the dyslipidemia group had more severe clinical characteristics (higher blood urea nitrogen, serum uric acid, and 24-h proteinuria; higher proportion of hypertension; and lower serum albumin and estimated glomerular filtration rate) and pathological changes (higher proportion of Lee grades IV-V and E1, S1, and C2 in MEST-C). Furthermore, the clinical and pathological characteristics were worse in the mixed hyperlipidemia group. Multivariate logistic analysis showed that hypertension, steroid treatment, lower serum albumin, severe proteinuria, and segmental glomerulosclerosis were independent risk factors for dyslipidemia in children with IgAN. The Kaplan-Meier analysis revealed that the probability of kidney survival in children with dyslipidemia was lower than that in those without dyslipidemia, with a median follow-up of 5.9 years.

CONCLUSIONS

Children with IgAN and dyslipidemia, especially mixed hyperlipidemia, are prone to more severe clinical and pathological changes. Our study provides further insight into dyslipidemia as a potential risk factor in children with IgAN. A higher resolution version of the Graphical abstract is available as Supplementary information.

Weight gain promotes the progression of IgA nephropathy in Asians: A protocol for systematic review and meta-analysis

INTRODUCTION

The relationship between weight gain and progression of IgA nephropathy (IgAN) has been investigated by many researchers but remains controversial. The incidence of IgAN is significantly higher in Asia than in other regions. Therefore, we investigated the relationship between weight gain and primary IgAN in the Asian population.

METHODS AND ANALYSIS

Seven databases were retrieved up to now. We stratified the included population by body mass index (BMI) and performed a meta-analysis of associated risk factors.

OBJECTIVES

In this study, Asian IgAN patients with different BMI were grouped together to clarify the relationship between BMI and IgAN progression in Asian populations, so as to provide more ideas and treatment means for the prevention and treatment of IgAN in the future.

The density of renal lymphatics correlates with clinical outcomes in IgA nephropathy

Introduction

IgA nephropathy (IgAN) is the most common primary glomerulonephritis (GN) worldwide. The disease course fluctuates, and the most important challenge is the considerable variation in the time lag between diagnosis and the development of a hard clinical end point, such as end-stage kidney disease (ESKD). The reaction of renal tissue to damage resembles the common wound-healing response. One part of this repair in IgAN is the expansion of lymphatic vessels known as lymphangiogenesis. The aim of this work was to establish the prognostic value of the density of lymphatic vessels in the renal biopsy at the time of diagnosis, for predicting the risk of ESKD in a Spanish cohort of patients with IgAN.

Methods

We performed a retrospective multicenter study of 76 patients with IgAN. The end point of the study was progression to ESKD. The morphometric analysis of lymphatic vessels was performed on tissue sections stained with antipodoplanin antibody.

Results

Density of lymphatic vessels was significantly higher in patients with IgAN with mesangial hypercellularity >50%, segmental sclerosis, higher degrees of interstitial fibrosis, and tubular atrophy. Patients with more lymphatic vessels had significantly higher values of proteinuria and lower estimated glomerular filtration rate (eGFR). A density of lymphatic vessels ≥8 per mm² was associated with a significantly higher rate of progression to ESKD at 3 years from biopsy. After adjustment for the International IgAN prediction score, at the multivariate logistic regression, high density of lymphatic vessels (≥8 per mm²) remained significantly associated with a higher rate of early progression to ESKD.

Conclusion

This study contributes to the understanding of the natural history of the progression to ESKD in patients with IgAN revealing the density of lymphatics vessels may optimize the prognostic value of the International IgA predicting tool to calculate the risk of ESKD, favoring the evaluation of new targeted therapies.

Association between urinary VEGFA and renal pathology of IgA nephropathy patients

BACKGROUND

Renal biopsy remains the golden standard for diagnosing and monitoring IgA nephropathy (IgAN). Vascular endothelial growth factor A (VEGFA) was crucial for the survival of glomerular cells. Our aim was to screen the expression pattern of urinary, circulating and renal VEGFA in IgAN patients to reveal their relationship with renal pathology and outcomes.

METHODS

Baseline VEGFA levels were determined with ELISA, real-time PCR and immunohistochemistry. Associations between VEGFA expression and clinical-pathological parameters, and renal outcomes were evaluated.

RESULTS

Compared with healthy controls, urinary VEGFA level was obviously elevated in IgAN patients (76.19 ± 63.67 pg/mg Cr vs 146.67 ± 232.71 pg/mg Cr, p = 0.0291) and not correlated with serum VEGFA level. Baseline urinary VEGFA was significantly associated with gender and tubular atrophy/interstitial fibrosis by stepwise multivariate regression analysis. Urinary VEGFA was higher in male patients accompanied with higher serum creatinine, larger proportion of hypertension and recurrent hematuria than in female patients. In the kidney of IgAN patients, VEGFA were robustly expressed in the parietal epithelial cells, podocytes, mesangial cells and tubular epithelial cells. After a follow-up duration of 38.53 ± 27.14 months, IgAN patients with higher urinary VEGFA level were found to have a poorer renal outcome of renal replacement therapy (HR = 1.027, p = 0.037) or composite outcome (HR = 1.023, p = 0.039) after adjusting for confounders.

CONCLUSIONS

Increased urinary VEGFA might reflect certain renal pathology and, although not fully specific, still could be served as a valuable noninvasive indicator in predicting renal progression of IgAN.

The prognostic effect of immunosuppressive therapy in IgA nephropathy with stage 3 or 4 chronic kidney disease

Background

It is debated whether patients with IgAN with heavy proteinuria and decreased eGFR benefit from aggressive treatment consisting of corticosteroids alone or combined with immunosuppressive agents.

Methods

A retrospective study was performed between January 2008 and December 2016 on patients with IgAN who had urinary protein excretion > 1.0 g/d and an eGFR between 15 and 59 mL/min/1.73 m². These patients were assigned to receive supportive care alone or supportive care plus immunosuppressive therapy. The primary outcome was defined as the first occurrence of a 50% decrease in eGFR or the development of ESKD.

Results

All 208 included patients were followed for a median of 43 months, and 92 (44%) patients experienced the primary outcome. Cumulative kidney survival was better in the immunosuppression group than in the supportive care group (p < .001). The median annual rate of eGFR decline in the immunosuppression group was −2.0 (−7.3 to 4.2), compared with −8.4 (–18.9 to −4.1) mL/min/1.73 m² in the supportive care group (p < .001). In multivariate Cox regression analyses, immunosuppressive therapy was associated with a lower risk of progression to ESKD, independent of age, sex, eGFR, proteinuria, MAP, kidney histologic findings and the use of RASi agents (HR = 0.335; 95% CI 0.209–0.601). Among the adverse events, infection requiring hospitalization occurred at similar rates in both groups (p = .471).

Conclusion

Immunosuppressive therapy attenuated the rate of eGFR decline and was associated with a favorable kidney outcome in IgAN patients with heavy proteinuria and decreased eGFR, and the side effects were tolerable.

IgA Nephropathy: "The Times They Are a-Changin"

Background

Primary IgA Nephropathy (IgA N) is a very common and often progressive glomerular disease. At present, the diagnosis of IgA N is totally dependent on kidney biopsy, but the prospect for a future diagnosis by means of a "liquid" biopsy is promising. A great deal is now understood regarding its diverse clinical and pathological features as well as its epidemiology, genetics, prognosis, and pathogenesis. Treatment approaches are now on increasingly solid evidence-based grounds, but many uncertainties continue to be devil the field. Better means of categorization of patients into a hierarchy of progression risk at the time of diagnosis will undoubtedly refine and personalize treatment decisions.

Summary

The panorama of treatment strategies is undergoing a rapid transformation, largely due to an increase in large randomized clinical trials testing available agents and novel therapeutic classes. It is anticipated that the combination of better prognostic tools and new strategies for treatment of IgA N will alter the landscape of therapeutic algorithms for patients with IgA N.

Key Messages

This review seeks to describe some of the evolutionary changes in the approach to treatment of IgA N, to place them in the context of current management, and to identify knowledge gaps that need to be addressed.

Large-scale site-specific mapping of the O-GalNAc glycoproteome

Protein glycosylation is one of the most common protein modifications. A major type of protein glycosylation is O-GalNAcylation, in which GalNAc-type glycans are attached to protein Ser or Thr residues via an O-linked glycosidic bond. O-GalNAcylation is thought to play roles in protein folding, stability, trafficking and protein interactions, and identification of the site-specific O-GalNAc glycoproteome is a crucial step toward understanding the biological significance of the modification. However, lack of suitable methodology, absence of consensus sequon of O-GalNAcylation sites and complex O-GalNAc glycan structures pose analytical challenges. We recently developed a mass spectrometry-based method called extraction of O-linked glycopeptides (EXoO) that enables large-scale mapping of site-specific mucin-type O-GalNAcylation sites. Here we provide a detailed protocol for EXoO, which includes seven stages of: (1) extraction and proteolytic digestion of proteins to peptides, (2) sequential guanidination and de-salting of peptides, (3) enrichment of glycopeptides, (4) solid-phase peptide conjugation and release of O-GalNAc glycopeptides using the OpeRATOR protease, (5) liquid chromatography with tandem mass spectrometry analysis of O-GalNAc glycopeptides, (6) identification of O-GalNAc glycopeptides by database search and (7) quantification of O-GalNAc glycopeptides. Using this protocol, thousands of O-GalNAcylation sites from hundreds of glycoproteins with information regarding site-specific O-GalNAc glycan can be identified and quantified from complex samples. The protocol can be performed by a researcher with basic proteomics skills and takes about 4 d to complete.