Remission of proteinuria improves prognosis in IgA nephropathy

Advancing the application of the analytical renal pathology system in allograft IgA nephropathy patients

BACKGROUND

The analytical renal pathology system (ARPS) based on convolutional neural networks has been used successfully in native IgA nephropathy (IgAN) patients. Considering the similarity of pathologic features, we aim to evaluate the performance of the ARPS in allograft IgAN patients and broaden its implementation.

METHODS

Biopsy-proven allograft IgAN patients from two different centers were enrolled for internal and external validation. We implemented the ARPS to identify glomerular lesions and intrinsic glomerular cells, and then evaluated its performance. Consistency between the ARPS and pathologists was assessed using intraclass correlation coefficients. The association of digital pathological features with clinical and pathological data was measured. Kaplan-Meier survival curve and cox proportional hazards model were applied to investigate prognosis prediction.

RESULTS

A total of 56 biopsy-proven allograft IgAN patients from the internal center and 17 biopsy-proven allograft IgAN patients from the external center were enrolled in this study. The ARPS was successfully applied to identify the glomerular lesions (F1-score, 0.696-0.959) and quantify intrinsic glomerular cells (F1-score, 0.888-0.968) in allograft IgAN patients rapidly and precisely. Furthermore, the mesangial hypercellularity score was positively correlated with all mesangial metrics provided by ARPS [Spearman's correlation coefficient (r), 0.439-0.472, and all p values < 0.001]. Besides, a higher allograft survival was noticed among patients in the high-level groups of the maximum and ratio of endothelial cells, as well as the maximum and density of podocytes.

CONCLUSION

We propose that the ARPS could be implemented in future clinical practice with outstanding capability.

External Validation of the International Prognosis Prediction Model of IgA Nephropathy

BACKGROUND

The International IgA Nephropathy (IgAN) Network developed and validated two prognostic prediction models for IgAN, one incorporating a race parameter. These models could anticipate the risk of a 50% reduction in estimated glomerular filtration rate (eGFR) or progression to end-stage renal disease (ESRD) subsequent to an IgAN diagnosis via renal biopsy. This investigation aimed to validate the International IgA Nephropathy Prediction Tool (IIgANPT) within a contemporary Chinese cohort.

METHODS

Within this study,185 patients diagnosed with IgAN via renal biopsy at the Center for Kidney Disease, Second Affiliated Hospital of Nanjing Medical University, between January 2012 and December 2021, were encompassed. Each patient's risk of progression was assessed utilizing the IIgANPT formula. The primary outcome, a 50% decline in eGFR or progression to ESRD, was examined. Two predictive models, one inclusive and the other exclusive of a race parameter, underwent evaluation via receiver-operating characteristic (ROC) curves, subgroup survival analyses, calibration plots, and decision curve analyses.

RESULTS

The median follow-up duration within our cohort spanned 5.1 years, during which 18 patients encountered the primary outcome. The subgroup survival curves exhibited distinct separations, and the comparison of clinical and histological characteristics among the risk subgroups revealed significant differences. Both models demonstrated outstanding discrimination, evidenced by the areas under the ROC curve at five years: 0.882 and 0.878. Whether incorporating the race parameter or not, both prediction models exhibited acceptable calibration. Decision curve analysis affirmed the favorable clinical utility of both models.

CONCLUSIONS

Both prognostic risk evaluation models for IgAN exhibited remarkable discrimination, sound calibration, and acceptable clinical utility.

Long-term renal survival in patients with IgA nephropathy: a systematic review

The management strategy for IgA nephropathy (IgAN), has undergone constant improvements since the disease entity was first described 50 years ago. However, it is still unknown how these changes affected the long-term renal survival of IgAN patients. We systematically evaluate changes in IgAN renal survival by searching PubMed, Embase, and the Cochrane Library Database of Systematic Reviews from inception to 19 May 2024. We included a large sample of 103076 IgAN cases from 158 studies. Renal survival rates were 94.16% (95% CI: 94.02% to 94.31%), 88.68% (95% CI: 88.48% to 88.87%), and 78.13% (95% CI: 77.82% to 78.43%) at three, five, and ten-year, respectively. Over the past few decades, there haven't been any sound changes in the 3-year and 5-year renal survival rates. The kidney survival rate in developed countries is higher than in developing countries. Researchers consistently show that while proteinuria < 1.0 g/24 h, renal survival rates increase dramatically. In IgAN, long-term renal survival fluctuated rather than continuously improving over time. Our system review's findings indicate that supportive care-the most important recommendation for managing IgAN has shown promising results. The long-term outcomes of IgAN could be significantly improved by the latest developed treatment options.

Causal relationship between Helicobacter pylori infection and IgA nephropathy: a bidirectional two-sample mendelian randomization study

IgA nephropathy (IgAN) is one of the most common primary glomerulonephritis, and serum Helicobacter pylori (H. pylori) antibody levels are increased in patients with IgA N, but the role of H. pylori infection in the pathogenesis of IgAN is unclear. In this study, we investigated whether there is a causal relationship and reverse causality between IgAN and H. pylori infection by using a bidirectional two-sample Mendelian randomization (MR) analysis. This study was estimated using inverse variance weighted (IVW), MR-Egger and weighted median methods, with the IVW method having the strongest statistical efficacy. Seven common serum H. pylori antibodies were selected as exposure factors for positive MR analysis. The results showed that there was no evidence of a causal relationship between H. pylori infection and IgAN. Reverse MR analysis showed that there was also no evidence that the occurrence of IgAN leads to an increased risk of H. pylori infection.

The role of complement in kidney disease: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

Uncontrolled complement activation can cause or contribute to glomerular injury in multiple kidney diseases. Although complement activation plays a causal role in atypical hemolytic uremic syndrome and C3 glomerulopathy, over the past decade, a rapidly accumulating body of evidence has shown a role for complement activation in multiple other kidney diseases, including diabetic nephropathy and several glomerulonephritides. The number of available complement inhibitor therapies has also increased during the same period. In 2022, Kidney Diseases: Improving Global Outcomes (KDIGO) convened a Controversies Conference, "The Role of Complement in Kidney Disease," to address the expanding role of complement dysregulation in the pathophysiology, diagnosis, and management of various glomerular diseases, diabetic nephropathy, and other forms of hemolytic uremic syndrome. Conference participants reviewed the evidence for complement playing a primary causal or secondary role in progression for several disease states and considered how evidence of complement involvement might inform management. Participating patients with various complement-mediated diseases and caregivers described concerns related to life planning, implications surrounding genetic testing, and the need for inclusive implementation of effective novel therapies into clinical practice. The value of biomarkers in monitoring disease course and the role of the glomerular microenvironment in complement response were examined, and key gaps in knowledge and research priorities were identified.

Contemporary review of IgA nephropathy

IgA nephropathy (IgAN) is considered the most common primary glomerulonephritis worldwide with a predilection for Asian-Pacific populations and relative rarity in those of African descent. Perhaps 20%-50% of patients progress to kidney failure. The pathogenesis is incompletely understood. Mesangial deposition of immune complexes containing galactose-deficient IgA1 complexed with anti-glycan IgG or IgA antibodies results in mesangial cell activation and proliferation, inflammatory cell recruitment, complement activation, and podocyte damage. Diagnosis requires a biopsy interpreted by the Oxford criteria. Additional pathologic features include podocytopathy, thrombotic microangiopathy, and C4d staining. Biomarkers predicting adverse outcomes include proteinuria, reduced GFR, hypertension, and pathology. Acceptable surrogate endpoints for therapeutic trials include ongoing proteinuria and rate of eGFR decline. The significance of persisting hematuria remains uncertain. The mainstay of therapy is supportive, consisting of lifestyle modifications, renin-angiotensin inhibition (if hypertensive or proteinuric), sodium-glucose-transporter 2 inhibition (if GFR reduced or proteinuric), and endothelin-receptor antagonism (if proteinuric). Immunosuppression should be considered for those at high risk after maximal supportive care. Corticosteroids are controversial with the most positive results observed in Chinese. They carry a high risk of serious side effects. Similarly, mycophenolate may be most effective in Chinese. Other immunosuppressants are of uncertain benefit. Tonsillectomy appears efficacious in Japanese. Active areas of investigation include B-cell inhibition with agents targeting the survival factors BAFF and APRIL and complement inhibition with agents targeting the alternate pathway (Factors B and D), the lectin pathway (MASP-2), and the common pathway (C3 and C5). Hopefully soon, the who and the how of immunosuppression will be clarified, and kidney failure can be forestalled.

Long-term outcomes of patients with IgA nephropathy in the German CKD cohort

Background

The importance of albuminuria as opposed to proteinuria in predicting kidney outcomes in primary immunoglobulin A nephropathy (IgAN) is not well established.

Methods

From 2010 to 2012, 421 patients with biopsy-proven IgAN have been enrolled into the German Chronic Kidney Disease (GCKD) cohort, a prospective observational cohort study (N = 5217). Adjudicated endpoints include a composite kidney endpoint (CKE) consisting of eGFR decline >40%, eGFR <15 ml/min/1.73 m2 and initiation of kidney replacement therapy; the individual components of the CKE; and combined major adverse cardiac events (MACE), including non-fatal myocardial infarction, non-fatal stroke and all-cause mortality. The associations between the incidence of CKE and baseline factors, including demographics, laboratory values and comorbidities were analysed using the Cox proportional hazards regression model.

Results

The mean age of IgAN patients at baseline was 51.6 years (± 13.6) and 67% were male. The patient-reported duration of disease at baseline was 5.9 ± 8.1 years. Baseline median urine albumin:creatinine ratio (UACR) was 0.4 g/g [interquartile range (IQR) 0.1-0.8] and mean eGFR was 52.5 ± 22.4 ml/min/1.73 m2. Over a follow-up of 6.5 years, 64 (15.2%) patients experienced a >40% eGFR decline, 3 (0.7%) reached eGFR <15 ml/min/1.73 m2, 53 (12.6%) initiated kidney replacement therapy and 28% of the patients experienced the CKE. Albuminuria, with reference to <0.1 g/g, was most associated with CKE. Hazard ratios (HRs) at UACRs of 0.1-0.6 g/g, 0.6-1.4 g/g, 1.4-2.2 g/g and >2.2 g/g were 2.03 [95% confidence interval (CI) 1.02-4.05], 3.8 (95% CI 1.92-7.5), 5.64 (95% CI 2.58-12.33) and 5.02 (95% CI 2.29-11-03), respectively. Regarding MACE, the presence of diabetes [HR 2.53 (95% CI 1.11-5.78)] was the most strongly associated factor, whereas UACR and eGFR did not show significant associations.

Conclusion

In the GCKD IgAN subcohort, more than every fourth patient experienced a CKE event within 6.5 years. Our findings support the use of albuminuria as a surrogate to assess the risk of poor kidney outcomes.

Time-Varying Proteinuria and Progression of IgA Nephropathy: A Cohort Study

RATIONALE & OBJECTIVE

Proteinuria is a surrogate end point for predicting long-term kidney outcomes in IgA nephropathy (IgAN) with levels<1g/day identified as a therapeutic target. However, this threshold has not been sufficiently studied. We quantified the associations of progression of IgAN with various levels of proteinuria.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

1,530 patients with IgAN and at least 12 months of follow-up at Peking University First Hospital.

EXPOSURE

Proteinuria levels updated over time (time-varying proteinuria, TVP).

OUTCOME

A composite kidney outcome of a 50% reduction in the estimated glomerular filtration rate or end-stage kidney disease.

ANALYTICAL APPROACH

Marginal structural models.

RESULTS

After a median follow-up period of 43.5 (IQR, 27.2-72.8) months, 254 patients (16.6%) developed the composite kidney outcome. A graded association was observed between TVP and composite kidney outcomes with higher risk among those with proteinuria of≥0.5g/day. Compared with TVP<0.3g/day, the HRs for proteinuria levels of 0.3 to<0.5g/day, 0.5 to<1.0g/day, 1.0 to<2.0g/day, and≥2.0g/day were 2.22 (95% CI, 0.88-5.58), 4.04 (95% CI, 1.93-8.46), 8.46 (95% CI, 3.80-18.83), and 38.00 (95% CI, 17.62-81.95), respectively. The trend was more pronounced in patients with baseline proteinuria of≥1.0g/day, among whom a higher risk was observed with TVP of 0.3 to<0.5g/day compared with TVP<0.3g/day (HR, 3.26 [95% CI, 1.07-9.92], P=0.04). However, in patients with baseline proteinuria levels of<1g/day, the risk of composite kidney outcome only began to increase when TVP was≥1.0g/day (HR, 3.25 [95% CI, 1.06-9.90]).

LIMITATIONS

Single-center observational study, selection bias, and unmeasured confounders.

CONCLUSIONS

This study showed that patients with IgAN and proteinuria levels of>0.5g/day, have an elevated risk of kidney failure especially among patients with proteinuria levels≥1.0g/day before initiating treatment. These data may serve to inform the selection of proteinuria targets in the treatment of IgAN.

PLAIN-LANGUAGE SUMMARY

The presence of proteinuria has often been considered a surrogate end point and a possible therapeutic target in clinical trials in IgA nephropathy (IgAN). Some guidelines recommend a reduction in proteinuria to<1g/day as a treatment goal based on the results of previous longitudinal studies. However, these findings may have been biased because they did not properly adjust for time-dependent confounders. Using marginal structural models to appropriately account for these confounding influences, we observed that patients with IgAN and proteinuria levels≥0.5g/day have an elevated risk of kidney failure, especially among patients who had proteinuria levels of≥1.0g/day before initiating treatment. These data may serve to inform the selection of proteinuria targets in the treatment of IgAN.

Application of the updated International IgA Nephropathy Prediction Tool in children one or two years post-biopsy

The pediatric International IgA Nephropathy (IgAN) Prediction Tool comprises two models with and without ethnicity and is the first method to predict the risk of a 30% decline in estimated glomerular filtration rate (eGFR) or kidney failure in children at the time of biopsy using clinical risk factors and Oxford MEST histology scores. However, it is unknown if the Prediction Tool can be applied after a period of observation post-biopsy. Using an international multi-ethnic cohort of 947 children with IgAN, 38% of whom were followed into adulthood, the Prediction Tool was updated for use one year after biopsy. Compared to the original pediatric Prediction Tool, the updated post-biopsy Prediction Tool had a better model fit with higher R2D (51%/50% vs 20%), significant increase in 4-year C-statistics (0.83 vs 0.73/0.69, ΔC 0.09 [95% confidence interval 0.07-0.10] and ΔC 0.14 [0.12-0.15]) and better 4-year calibration with lower integrated calibration indices (0.74/0.54 vs 2.45/1.01). Results were similar after internal validation and when the models were applied two years after biopsy. Trajectories of eGFR after a baseline one year post-biopsy were non-linear and those at higher predicted risk started with a lower eGFR and experienced a more rapid decline over time. In children, eGFR had a variable rate of increase until 15-18 years old and then decreased linearly with a more rapid decline in higher risk groups that was similar to young adults of comparable risk. Thus, the original pediatric Prediction Tool should be used in children at the time of biopsy, and the updated pediatric Prediction Tool should be used to re-evaluate risk one or two years after biopsy.

Development and External Validation of a Multidimensional Deep Learning Model to Dynamically Predict Kidney Outcomes in IgA Nephropathy

Key Points

A dynamic model predicts IgA nephropathy prognosis based on deep learning. Longitudinal clinical data and deep learning improve predictive accuracy and interpretability in GN.

Background

Accurately predicting kidney outcomes in IgA nephropathy is crucial for clinical decision making. Insufficient use of longitudinal data in previous studies has limited the accuracy and interpretability of prediction models for failing to reflect the chronic nature of IgA nephropathy. The aim of this study was to establish a multivariable dynamic deep learning model using comprehensive longitudinal data for the prediction of kidney outcomes in IgA nephropathy.

Methods

In this retrospective cohort study of 2056 patients with IgA nephropathy from 18 kidney centers, a total of 28,317 data points were collected by the sliding window method. Among them, 15,462 windows in a single center were randomly assigned to training (80%) and validation (20%) sets and 8797 windows in 18 kidney centers were assigned to an independent test set. Interpretable multivariable long short-term memory, a deep learning model, was implemented to predict kidney outcomes (kidney failure or 50% decline in kidney function) based on time-invariant variables measured at biopsy and time-variant variables measured during follow-up. Risk performance was evaluated using the Kaplan–Meier analysis and C-statistic. Trajectory analysis was performed to assess the various trends of clinical variables during follow-up.

Results

The model achieved a higher C-statistic (0.93; 95% confidence interval, 0.92 to 0.95) on the test set than the machine learning prediction model that we developed in a previous study using only baseline information (C-statistic, 0.84; 95% confidence interval, 0.80 to 0.88). The Kaplan–Meier analysis showed that groups with lower predicted risks from the full model survived longer than groups with higher risks. Time-variant variables demonstrated higher importance scores than time-invariant variables. Within time-variant variables, more recent measurements showed higher importance scores. Further interpretation showed that certain trajectory groups of time-variant variables such as serum creatinine and urine protein were associated with elevated risks of adverse outcomes.

Conclusions

In IgA nephropathy, a deep learning model can be used to accurately and dynamically predict kidney prognosis based on longitudinal data, and time-variant variables show strong ability to predict kidney outcomes.

A comparison of the clinical efficacy of tonsillectomy with steroid pulse therapy and tonsillectomy therapy alone for patients with immunoglobulin A nephropathy: a retrospective observational study

BACKGROUND

Tonsillectomy with steroid pulse therapy (TSP) and tonsillectomy monotherapy (T) have improved the prognosis of patients with immunoglobulin A nephropathy (IgAN). However, a consensus has not been reached on the best treatment for these patients. This study aimed to compare the efficacies of TSP and T.

METHODS

Data of patients with IgAN who received TSP or T were retrospectively analyzed. The exclusion criterion was a serum creatinine level > 1.5 mg/dL. The clinical remission and renal survival rates were compared.

RESULTS

Patients were divided into groups based on the treatment method: the TSP (n = 82) and T groups (n = 41). No significant differences were observed in patient characteristics, except for the observation period (TSP: 60 months, T: 113 months). The log-rank test revealed that the clinical remission rate was significantly higher in the TSP group than in the T group (p < 0.05). The superiority of TSP was also observed in the urinary protein excretion (> / = or < 1 g/day) of the two subgroups. According to the Cox proportional-hazards model, the treatment method and daily urinary protein extraction were independent factors affecting clinical remission. The 10-year renal survival rates in the TSP and T groups were 100% and 92.5%, respectively. The log-rank test revealed a tendency for a higher renal survival rate in the TSP group than in the T group (p = 0.09).

CONCLUSION

The clinical remission rate was significantly higher with TSP than with T, regardless of urinary protein levels. TSP tended to have a better renal survival rate than T.

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

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

Childhood-onset IgA nephropathy: is long-term recovery possible?

BACKGROUND

IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. While studies have primarily focused on identifying risk factors for disease progression, very few data exist on the likelihood of achieving complete recovery from the disease.

METHODS

We conducted a single-center retrospective study on all consecutive patients with biopsy-proven IgAN diagnosed between 1986 and 2018 in our pediatric center. Biopsies were classified according to the MEST-C Oxford classification score. "Complete clinical remission" was defined as the absence of proteinuria, hematuria, and hypertension in patients with normal kidney function who had been off therapy for more than 2 years.

RESULTS

Overall, 153 patients with age at onset of 10.6 ± 4 years were enrolled in the study. Of these, 41 achieved "complete clinical remission." The estimated probability of complete clinical remission at 10 years was 43% (95%CI 33-54). However, seven patients relapsed within 10 years. Multivariable analysis showed that higher age at onset (HR 0.89, 95%CI 0.80-0.98, p = 0.017) and segmental glomerulosclerosis lesions (HR 0.28, 95%CI 0.10-0.79, p = 0.017) decreased significantly the chances of achieving complete clinical remission. Immunosuppressive therapy was not significantly associated with clinical outcomes.

CONCLUSIONS

Approximately one-third of patients with pediatric-onset IgAN achieve prolonged remission, in particular, very young children at disease onset without sclerotic glomerular lesions. Longer term follow-up is needed to assess if these patients have achieved permanent remission.

Primary IgA Nephropathy: New Insights and Emerging Therapies

Primary IgA nephropathy (IgAN) is a common glomerular disorder defined by predominant mesangial IgA deposition. Once thought to follow a progressive course in 10-20% of those diagnosed, emerging evidence now suggests most will progress to kidney failure over their lifetimes. Although the lack of safe and effective treatments to impede disease progression continues to present a challenge, the landscape of IgAN has dramatically evolved over the last 2 years. Driven by fundamental changes to accepted end points for IgAN clinical trials as well as fascinating new insights into the pathophysiology of IgAN, a swathe of novel and repurposed therapies are currently being evaluated. Already, two novel drugs, targeted-release formulation budesonide and sparsentan, have received conditional approvals for the treatment of IgAN, with sodium glucose co-transporter 2 inhibitors establishing themselves as further options. Soon to join this ensemble are likely to be treatments that modulate the complement system and B-cell activity; several are currently undergoing clinical trials in IgAN with promising interim results. In this review, we provide an overview of evolving epidemiological insights, disease mechanisms, emerging therapies, and contemporary challenges surrounding the management of IgAN.

New therapies for immunoglobulin A nephropathy: what's the standard of care in 2023?

PURPOSE OF REVIEW

As the most common primary glomerulonephritis, immunoglobulin A (IgA) nephropathy (IgAN) is an important cause of kidney failure and mortality. Until recently, therapeutic options were limited. Fortunately, there have been numerous recent clinical trials demonstrating efficacy of new therapies in slowing chronic kidney disease (CKD) progression at varying stages of disease.

RECENT FINDINGS

The TESTING trial has provided high-quality evidence for slowing estimated glomerular filtration rate (eGFR) decline with a reduced-dose glucocorticoid regimen, while demonstrating an improved safety profile. Targeted-release budesonide represents a well tolerated therapy for reducing eGFR decline. Mycophenolate mofetil may reduce CKD progression in some populations, while hydroxychloroquine is efficacious in reducing proteinuria. Sodium-glucose cotransporter (SGLT2) inhibitors and sparsentan are effective therapies for CKD due to IgAN, but should not be used in lieu of disease-modifying immunosuppressive therapy. Many new therapies are approaching readiness for clinical use.

SUMMARY

Numerous therapeutic options now exist and include disease-modifying and nephroprotective drugs. Identifying the right treatment for the right patient is now the clinical challenge and, with new drugs on the horizon, represents the primary unmet research need in this rapidly-developing field.

Corticosteroid in IgA nephropathy with moderate proteinuria: A retrospective cohort study

BACKGROUND

Corticosteroids remain contentious as a therapeutic option for IgA nephropathy. We conducted a retrospective cohort study to explore whether corticosteroid therapy is efficient and safe for IgAN patients with moderate proteinuria.

METHODS

A total of 336 patients with renal biopsy-confirmed IgAN, estimated glomerular filtration (eGFR) over 15 mL/min/1.73 m2 and urine protein levels of 0.75-3.5 g/d were enrolled. According to the treatment protocol, we classified the enrolled patients into two groups: one receiving corticosteroids and the other receiving supportive care. Complete remission, partial remission, and no remission were applied to describe the efficacy assessments. The endpoint was defined as a 40% reduction in eGFR, the onset of ESRD, or renal disease-related death.

RESULTS

Clinical and pathological progression risk factors were higher in corticosteroid-treated individuals. Logistic regression analysis revealed that the corticosteroid group was considerably related to a higher remission rate after adjustment for confounding factors. The occurrence of serious adverse events between the two groups was not found to be statistically significantly different. Then, we matched 95 couples of patients with similar baseline levels in both groups by propensity score matching. The results showed that corticosteroid-treated patients showed higher overall and complete remission rates than untreated patients. However, due to the relatively short follow-up period, no significant differences in the incidence of endpoint and survival analyses have been observed thus far.

CONCLUSION

Corticosteroid therapy may benefit IgAN patients with moderate proteinuria via proteinuria reduction and renal function preservation.

Drugs in Development to Treat IgA Nephropathy

IgA nephropathy is a common glomerulonephritis consequent to the autoimmune response to aberrant glycosylated immunoglobulin (Ig) A antibodies. Although it has historically been considered a benign disease, it has since become clear that a substantial percentage of patients reach end-stage kidney failure over the years. Several therapeutic attempts have been proposed, with systemic steroids being the most prevalent, albeit burdened by possible serious adverse events. Thanks to the more in-depth knowledge of the pathogenesis of IgA nephropathy, new treatment targets have been identified and new drugs developed. In this narrative review, we summarise the molecules under clinical development for the treatment of IgA nephropathy. As a search strategy, we used PubMed, Google, ClinicalTrials.gov and abstracts from recent international congresses. TRF budesonide and sparsentan are the two molecules at a more advanced stage, just entering the market. Other promising agents are undergoing phase III clinical development. These include anti-APRIL and anti-BLyS/BAFF antibodies and some complement inhibitors. Other new possible strategies include spleen tyrosine kinase inhibitors, anti-CD40 ligands and anti-CD38 antibodies. In an era increasingly characterised by 'personalised medicine' and 'precision therapy' approaches and considering that the potential therapeutic armamentarium for IgA nephropathy will be very broad in the near future, the identification of biomarkers capable of helping the nephrologist to select the right drug for the right patient should be the focus of future studies.

[Immunoglobulin A nephropathy-New treatment possibilities]

Immunoglobulin A (IgA) nephropathy is the most frequent glomerulonephritis in adults in Central Europe. It is characterized by microhematuria and occasionally macrohematuria, proteinuria and a chronic loss of kidney function. The diagnosis is made based on a kidney biopsy. The progressive kidney damage must always be slowed down by normalizing blood pressure, using angiotensin inhibitors and consistently avoiding additional toxic substances. In many cases this is not sufficient and then sodium-glucose transporter 2 (SGLT-2) inhibitors and immunomodulators are used. In particular, the SGLT-2 inhibitors show a very significant reduction in proteinuria and slow down the deterioration of the estimated glomerular filtration rate (eGFR). While systemic corticosteroids are now only indicated in rare cases, a special budesonide formulation shows good effects. Further pathophysiologically based pharmacotherapies are currently being tested in clinical studies. These include, among others, the dual endothelin type A receptor and angiotensin II receptor antagonist sparsentan, which has already been shown to reduce proteinuria as well as inhibitors of complement activation, which is important for kidney damage. Initial findings for these as well as for the B‑lymphocyte proliferation inhibitor sibeprenlimab, suggest that they could enrich the armamentarium for the treatment of IgA nephropathy in the future.

Immunoglobulin A glomerulonephropathy: A review

In this editorial, we comment on the article by Meng et al published in the World Journal of Clinical Cases. We comprehensively review immunoglobulin A nephropathy (IgAN), including epidemiology, clinical presentation, diagnosis, and management. IgAN, also known as Berger's disease, is the most frequent type of primary glomerulonephritis (GN) globally. It is mostly found among the Asian population. The presentation can be variable, from microscopic hematuria to a rapidly progressive GN. Around 50% of patients present with single or recurring episodes of gross hematuria. An upper respiratory infection and tonsillitis often precede these episodes. Around 30% of patients present microscopic hematuria with or without proteinuria, usually detected on routine examination. The diagnosis relies on having a renal biopsy for pathology and immunofluorescence microscopy. We focus on risk stratification and management of IgAN. We provide a review of all the landmark studies to date. According to the 2021 KDIGO (kidney disease: Improving Global Outcomes) guidelines, patients with non-variant form IgAN are first treated conservatively for three to six months. This approach consists of adequate blood pressure control, reduction of proteinuria with renin-angiotensin system blockade, treatment of dyslipidemia, and lifestyle modifications (weight loss, exercise, smoking cessation, and dietary sodium restrictions). Following three to six months of conservative therapy, patients are further classified as high or low risk for disease progression. High-risk patients have proteinuria ≥ 1 g/d or < 1 g/d with significant microscopic hematuria and active inflammation on kidney biopsy. Some experts consider proteinuria ≥ 2 g/d to be very high risk. Patients with high and very high-risk profiles are treated with immunosuppressive therapy. A proteinuria level of < 1 g/d and stable/improved renal function indicates a good treatment response for patients on immunosuppressive therapy.

Kidney Failure Events, Cardiovascular Disease Events, and All-Cause Mortality in Patients with IgA Nephropathy in a Real-World Database

Key Points

In our US real-world cohort study of patients with IgA nephropathy, elevated proteinuria and progression to kidney failure (KF) were associated with a higher risk of cardiovascular disease/mortality events. Elevated pre-KF proteinuria was also associated with progression to KF/mortality events. Incremental costs associated with CKD stage, nephrotic syndrome, and cardiovascular disease events and of these events were high.

Background

IgA nephropathy (IgAN)–associated glomerular injury leads to proteinuria, hematuria, and progressive loss of GFR, with progression to kidney failure (KF). This retrospective study evaluated the prognostic effects of proteinuria and progression to KF on cardiovascular disease (CVD)/mortality events and KF/mortality events in the United States.

Methods

We conducted a noninterventional, retrospective cohort study in adult patients with IgAN using Optum's deidentified Market Clarity Data (January 1, 2007, to March 31, 2021). Adult (age ≥18 years) patients with at least two signs, disease, symptoms natural language processing term entries for IgAN, within 180 and ≥30 days apart within the identification period were included. Outcomes were assessed by time-dependent proteinuria (≥1 versus <1 g/d) and KF status (pre versus post). Descriptive statistics were used for categorical and continuous variables. Multivariable Cox proportional hazard models with time-dependent predictors were used to estimate differences across groups.

Results

Patients with pre-KF status and proteinuria ≥1 g/d were more likely to have a CVD/mortality event during follow-up (adjusted hazard ratio [HR; 95% confidence interval (CI)]: 1.80 [1.12 to 2.89]; P < 0.001) or a KF/mortality event (adjusted HR [95% CI]: 2.10 [1.73 to 2.56]; P < 0.001). Patients with post-KF status were more likely to have a CVD/mortality event during follow-up (adjusted HR [95% CI]: 3.28 [2.82 to 3.81]; P < 0.001).

Conclusions

Elevated proteinuria and progression to KF were associated with a higher risk of CVD/mortality events. Elevated pre-KF proteinuria was also associated with progression to KF/mortality events. On the basis of our real-world retrospective database analysis, we hypothesize that novel IgAN therapies that reduce proteinuria and slow the rate of progression to KF have the potential to reduce CVD risk, improve kidney outcomes, and prolong/increase overall survival.

Distinct characteristics and prognosis of IgA nephropathy patients with nephrotic syndrome: a propensity score-matched cohort study

Introduction

IgA nephropathy (IgAN) is the most prevalent primary glomerulonephritis globally. While nephrotic syndrome (NS) is uncommon in IgAN, its significance remains unclear.

Methods

We conducted a retrospective analysis of 170 IgAN patients, classifying them into NS (n = 85) and non-NS (n = 5) groups. Our study aims to compare their clinical characteristics, treatment responses, and prognoses. Patients were selected based on renal biopsy from 2003 to 2020. Propensity score matching ensured comparability. Clinical, pathological, and immunological data were analyzed. Composite endpoints were defined as end-stage kidney disease (ESKD) or a 30% decline in estimated glomerular filtration rate (eGFR).

Results

NS patients showed higher eGFR (74.3 ± 36.8 vs. 61.5 ± 33.6 mL/min.1.73 m2, p = 0.02), severe hematuria (35.0 (4.7,147.5) vs. 4.0 (1.8,45,0) cells/μl, p < 0.001), severe foot process effacement (p = 0.01), and lower C3 levels (1.0 ± 0.3 vs. 1.1 ± 0.2 g/L, p = 0.03). In contrast, the non-NS group had higher BMI (24.3 ± 4.0 vs. 26.8 ± 3.7 kg/m2, p < 0.001) and elevated serum uric acid levels (376 (316,417) vs. 400 (362, 501) mmol/L, p = 0.001), suggesting metabolic factors might contribute to their condition. Both groups exhibited similar MESTC scores. NS patients had higher complete remission rates (26.2% vs. 14.1%, p = 0.04). Cox regression revealed NS independently associated with a higher risk of composite endpoints (HR = 1.97, 95% CI 1.05-3.72, p = 0.04). Linear mixed models did not show significant eGFR trajectory differences.

Discussion

This study has established that IgAN patients with NS exhibit distinct characteristics, including active disease and increased complement activation. NS is independently associated with a poorer prognosis, emphasizing the need for targeted interventions in this subgroup.

An Update on Current Therapeutic Options in IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) remains the leading cause of primary glomerular disease worldwide. Outcomes are poor with high rates of progressive chronic kidney disease and kidney failure, which contributes to global healthcare costs. Although this disease entity has been described, there were no disease-specific treatments until recently, with the current standard of care focusing on optimal supportive measures including lifestyle modifications and optimization of the renin-angiotensin-aldosterone blockade. However, with significant advances in the understanding of the pathogenesis of IgAN in the past decade, and the acceptance of surrogate outcomes for accelerated drug approval, there have been many new investigational agents tested to target this disease. As these agents become available, we envision a multi-pronged treatment strategy that simultaneously targets the consequences of ongoing nephron loss, stopping any glomerular inflammation, inhibiting pro-fibrotic signals in the glomerulus and tubulo-interstitium, and inhibiting the production of pathogenic IgA molecules. This review is an update on a previous review published in 2021, and we aim to summarize the developments and updates in therapeutic strategies in IgAN and highlight the promising discoveries that are likely to add to our armamentarium.

Non-immunosuppressive treatment for IgA nephropathy

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

The Treatment of Primary IgA Nephropathy: Change, Change, Change

IgA nephropathy (IgAN) is the most common glomerular disease in the world. However, the approach to treatment remains controversial. There has been an explosion of clinical trials over the past decade both to further examine corticosteroid use and usher in additional treatment considerations, including 2 newly approved therapies for IgAN. Sodium glucose cotransporter 2 inhibitors are proving to be effective therapy across proteinuric chronic kidney diseases, and IgAN is not likely to be an exception. Further supportive agents are looking highly promising and so are novel agents that specifically focus on the pathophysiology of this disease, including endothelin blockade, complement inhibition, and B-cell targeted strategies. We suggest a present-day approach to treatment of individuals with IgAN, expose the limitations in our knowledge, and discuss new treatments that may arise, hoping they come with evidence about optimal utilization. Change appears to be inevitable for our approach to the treatment of IgA nephropathy. This is truly an exciting and optimistic time.

The role of BAFF and APRIL in IgA nephropathy: pathogenic mechanisms and targeted therapies

Immunoglobulin A nephropathy (IgAN), characterized by mesangial deposition of galactose-deficient-IgA1 (Gd-IgA1), is the most common biopsy-proven primary glomerulonephritis worldwide. Recently, an improved understanding of its underlying pathogenesis and the substantial risk of progression to kidney failure has emerged. The "four-hit hypothesis" of IgAN pathogenesis outlines a process that begins with elevated circulating levels of Gd-IgA1 that trigger autoantibody production. This results in the formation and deposition of immune complexes in the mesangium, leading to inflammation and kidney injury. Key mediators of the production of Gd-IgA1 and its corresponding autoantibodies are B-cell activating factor (BAFF), and A proliferation-inducing ligand (APRIL), each playing essential roles in the survival and maintenance of B cells and humoral immunity. Elevated serum levels of both BAFF and APRIL are observed in patients with IgAN and correlate with disease severity. This review explores the complex pathogenesis of IgAN, highlighting the pivotal roles of BAFF and APRIL in the interplay between mucosal hyper-responsiveness, B-cell activation, and the consequent overproduction of Gd-IgA1 and its autoantibodies that are key features in this disease. Finally, the potential therapeutic benefits of inhibiting BAFF and APRIL in IgAN, and a summary of recent clinical trial data, will be discussed.

Prognostic factors affecting long-term outcomes in patients with concurrent IgA nephropathy and membranous nephropathy

Background

The incidence of concurrent immunoglobulin A nephropathy and membranous nephropathy (cIgAN/MN) is low and rarely reported, and the prognosis of patients with cIgAN/MN remains unclear. This study was designed to compare the clinical and prognostic characteristics of cIgAN/MN with IgAN and MN and to identify crucial factors influencing the outcomes of patients with cIgAN/MN.

Methods

We included biopsy-proven cIgAN/MN patients between December 2012 and December 2020 at Xijing Hospital. In the same period, propensity score matching was employed to select an equal number of IgAN and MN patients according to the following criteria: age, sex, and follow-up time. The primary endpoint was defined as a composite of eGFR decline ≥30 %, end-stage renal disease, or death. The patient survival rate was examined using Kaplan-Meier survival curves. Univariate and multivariate Cox regression analysis models were utilized to identify the risk factors affecting renal prognosis.

Results

A total of 135 patients were finally included in this study and 35 (25.9 %) reached the primary endpoint. The median follow-up time of cIgAN/MN was 45.9 (24.0, 72.0) months. Compared to the IgAN group, the cIgAN/MN group exhibited a lower cumulative incidence rate of composite renal endpoints (P = 0.044), while no significant difference was found between MN and cIgAN/MN patients (P = 0.211). Univariate Cox analysis revealed that mean arterial pressure, serum potassium, blood urea nitrogen, serum IgA, segmental glomerulosclerosis (S1), and MN staging were associated with an increased risk of renal composite endpoints. The multivariate Cox regression analysis of clinical variables plus histological lesion scoring demonstrated that potassium (HR = 14.350, 95 % CI 2.637-78.090, P = 0.002), serum IgA (HR = 1.870, 95 % CI 1.109-3.153, P = 0.019), and S1 (HR = 11.965, 95 % CI 2.166-66.105, P = 0.004) were independent risk factors influencing renal outcomes in cIgAN/MN patients.

Conclusion

The prognosis of cIgAN/MN patients may exhibit an intermediate pattern between IgAN and MN, leaning towards being more similar to MN in certain aspects. Within the cIgAN/MN cohort, potassium, and serum IgA may be more predictive of rapid progression of renal endpoints, and S1 may indicate a more aggressive disease course.

Clinicopathological prognostic stratification for proteinuria and kidney survival in IgA nephropathy: a Japanese prospective cohort study

Background

We require a clinicopathological risk stratification method for immunoglobulin A nephropathy (IgAN) to predict kidney outcomes. We examined a renal failure risk group (RF-RG) classification system created following a prior multicentre, retrospective study to determine if RF-RG could predict kidney outcomes.

Methods

We collected data from Japanese patients with IgAN registered between 1 April 2005 and 31 August 2015. The primary outcome was a composite 50% increase in serum creatinine from baseline or dialysis induction. The secondary outcomes were times to proteinuria remission (ProR) and haematuria remission (HemR).

Results

The enrolled 991 patients from 44 facilities were followed for a median of 5.5 years (interquartile range 2.5-7.5), during which 87 composite events (8.8%) occurred. RF-RG was significantly associated with the primary outcome {hazard ratio [HR] II 2.78 [95% confidence interval (CI) 1.12-6.93], III 7.15 (2.90-17.6), IV 33.4 (14.1-79.0), I as a reference, P < .001}.The discrimination performance was good [C-statistic 0.81 (95% CI 0.76-0.86)] and the time-dependent C-statistics exceeded 0.8 over 10 years. Among the 764 patients with proteinuria and 879 patients with haematuria at baseline, 515 and 645 patients showed ProR and HemR, respectively. ProR was significantly less frequent in patients with advanced disease [subdistribution HR: II 0.79 (95% CI 0.67-0.94), III 0.53 (0.41-0.66), IV 0.15 (0.09-0.23), I as a reference, P < .001]. We also observed an association between HemR and RF-RG.

Conclusions

RF-RG demonstrated good predictive ability for kidney outcomes.

Treatment of IgA Nephropathy: A Rapidly Evolving Field

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

Practical Considerations for the Use of Sparsentan in the Treatment of Patients with IgAN in Clinical Practice

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. It is characterized by the mesangial deposition of IgA-containing immune complexes, triggering damage to the glomerular filtration barrier that is amplified by the tandem action of endothelin-1 and angiotensin II at their receptors. Proteinuria and progressive glomerular damage cause loss of kidney function in up to 50% of patients within 10-20 years. The risk of progression is strongly associated with persistent proteinuria (>0.75-1 g/day). Current standard of care involves interventions to decrease proteinuria and control blood pressure. Immunosuppressive agents, used in selected patients at high risk for progression, can be associated with significant side effects. Sparsentan, a novel non-immunosuppressive single-molecule Dual Endothelin Angiotensin Receptor Antagonist (DEARA), received FDA accelerated approval based on interim results from the PROTECT trial, which demonstrated that sparsentan-treated patients achieved a significantly greater reduction in proteinuria from baseline versus the active control irbesartan and that sparsentan was generally safe and well tolerated. Sparsentan is the first non-immunosuppressive treatment to be FDA-approved for the reduction of proteinuria in adults with IgAN at high risk of disease progression. We provide practical guidance for the clinical use of sparsentan in adults with IgAN.

Optimal Conservative Therapy Use among Adult Cure Glomerulonephropathy Participants with IgA Nephropathy

Optimal supportive therapy with BP and proteinuria control is pivotal in treating patients with IgA nephropathy. Suboptimal treatment of hypertension and proteinuria persisted in many patients with IgA nephropathy in the Cure Glomerulonephropathy Network study. Many patients had above-target proteinuria despite optimal BP control and may benefit from novel therapies or clinical trials.

Ethnicity and IgA nephropathy: worldwide differences in epidemiology, timing of diagnosis, clinical manifestations, management and prognosis

Immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis, is one of the major causes of end-stage renal disease. Significant variances in epidemiology, clinical manifestation, timing of diagnosis, management and renal prognosis of IgAN have been reported worldwide. The incidence of IgAN is the most frequent in Asia, followed by Europe, and lower in Africa. Moreover, Asian patients show more frequent acute lesions in renal histology and present poorer renal outcomes compared with Caucasians. The comorbidities also show the difference between Asians and Caucasians. Although the frequency of gross hematuria with upper respiratory tract infection is not different, comorbidities with gastrointestinal diseases are reported to be higher in Europe. Recently, genetic studies for variant ethnic patients revealed widely ranging genetic risks in each ethnicity. A genetic risk score is most elevated in Asians, intermediate in Europeans and lowest in Africans, consistent with the disease prevalence of IgAN globally. Ethnic variance might be highly affected by the difference in genetic background. However, it is also essential to mention that the different timing of diagnosis due to variant urinary screening systems and the indication for renal biopsy in different countries may also contribute to these variances. The management of IgAN also varies internationally. Currently, several novel therapies based on the pathogenesis of IgAN are being assessed and are expected to become available soon. Further understanding the ethnic variance of IgAN might help establish individualized care for this disease. Here, we review the issues of ethnic heterogeneities of IgAN.

The contribution of a proliferation-inducing ligand (APRIL) and other TNF superfamily members in pathogenesis and progression of IgA nephropathy

Advances in our understanding of the pathogenesis of immunoglobulin A nephropathy (IgAN) have led to the identification of novel therapeutic targets and potential disease-specific treatments. Specifically, a proliferation-inducing ligand (APRIL) has been implicated in the pathogenesis of IgAN, mediating B-cell dysregulation and overproduction of pathogenic galactose-deficient IgA1 (Gd-IgA1). Animal and clinical studies support the involvement of APRIL in the pathogenesis and progression of IgAN. An elevated level of APRIL is found in IgAN when compared with controls, which correlates with the level of Gd-IgA1 and associates with more severe disease presentation and worse outcomes. Conversely, anti-APRIL therapy reduces pathogenic Gd-IgA1 and IgA immune complex formation and ameliorates the severity of kidney inflammation and injury. Genome-wide association studies in IgAN have identified TNFSF13 and TNFRSF13B, a cytokine ligand-receptor gene pair encoding APRIL and its receptor, respectively, as risk susceptibility loci in IgAN, further supporting the causal role of the APRIL signalling pathway in IgAN. Several novel experimental agents targeting APRIL, including atacicept, telitacicept, zigakibart and sibeprenlimab, are currently under investigation as potential therapies in IgAN. Preliminary results suggest that these agents are well-tolerated, and reduce levels of Gd-IgA1, with corresponding improvement in proteinuria. Further studies are ongoing to confirm the safety and efficacy of anti-APRIL approaches as an effective therapeutic strategy in IgAN.

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.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

IgA nephropathy

IgA nephropathy (IgAN), the most prevalent primary glomerulonephritis worldwide, carries a considerable lifetime risk of kidney failure. Clinical manifestations of IgAN vary from asymptomatic with microscopic or intermittent macroscopic haematuria and stable kidney function to rapidly progressive glomerulonephritis. IgAN has been proposed to develop through a 'four-hit' process, commencing with overproduction and increased systemic presence of poorly O-glycosylated galactose-deficient IgA1 (Gd-IgA1), followed by recognition of Gd-IgA1 by antiglycan autoantibodies, aggregation of Gd-IgA1 and formation of polymeric IgA1 immune complexes and, lastly, deposition of these immune complexes in the glomerular mesangium, leading to kidney inflammation and scarring. IgAN can only be diagnosed by kidney biopsy. Extensive, optimized supportive care is the mainstay of therapy for patients with IgAN. For those at high risk of disease progression, the 2021 KDIGO Clinical Practice Guideline suggests considering a 6-month course of systemic corticosteroid therapy; however, the efficacy of systemic steroid treatment is under debate and serious adverse effects are common. Advances in understanding the pathophysiology of IgAN have led to clinical trials of novel targeted therapies with acceptable safety profiles, including SGLT2 inhibitors, endothelin receptor blockers, targeted-release budesonide, B cell proliferation and differentiation inhibitors, as well as blockade of complement components.

A closer look: ultrastructural evaluation of high-risk progression IgA nephropathy

This retrospective, cross-sectional study sought to examine the ultrastructural characteristics of glomerular lesions using Transmission Electron Microscopy (TEM) in IgA nephropathy (IgAN) and their relationship with the high risk of progression phenotype defined by KDIGO guideline as proteinuria ≥1 g/24 hours despite 3 months of optimized supportive care. We analyzed 81 IgAN patients (median age 41 years, 67% male, eGFR 43.8 mL/min, proteinuria 1.04 g/day); 42 (52%) of them had high risk of progression. There were no differences in terms of age, sex, comorbidities, eGFR, and hematuria between the two groups. High-risk patients more often had segmental glomerulosclerosis (29% vs 8%, p 0.01) in optical microscopy, while in TEM had more frequent podocyte hypertrophy (62% vs 26%, p 0.001) and podocyte foot process detachment from the glomerular basement membrane (19% vs 8%, p 0.05), more often thicker (19% vs 5%, p 0.05) and duplicated (26% vs 10%, p 0.05) glomerular basement membrane, and the presence of subendothelial and subepithelial deposits (31% vs 13%, p 0.05). However, in multivariate binary logistic regression analysis, only podocyte hypertrophy (OR 3.14; 95%CI 1.12, 8.79) was an independent risk factor for high-risk progression in IgAN. These findings highlight the importance of podocytopathy in IgAN progression.

Dietary fatty acids intake and all-cause and cardiovascular mortality in patients on peritoneal dialysis

BACKGROUND & AIMS

The relationship between dietary fatty acids (FA) and clinical outcomes are relatively lacking in non-dialyzed and dialyzed chronic kidney disease (CKD) population, resulting in insufficient guide about the dietary FA intake in this population. In this study, we aimed to observe the association between the intake of total or different types of FA and all-cause and cardiovascular (CV) mortality in patients undergoing peritoneal dialysis (PD).

METHODS

This is a prospective cohort study with data retrospectively analyzed in 881 patients undergoing PD. Dietary FA intake measured by 3-day dietary records. The outcomes were defined as all-cause and CV death. Baseline FA intake and time-averaged FA intake were categorized by tertiles based on the distribution among the study population. We used univariate and multivariate Cox proportional regression models to determine the association between amounts and types of FA and all-cause and CV mortality.

RESULTS

During a median follow up of 45 months, 93 patients were still being maintained on PD, 467 had died, including 189 (40.5%) attributable to CV death. Compared to patients in the low tertile of total FA (TFA) intake at baseline group, the middle or/and high tertile groups were more likely to be male, younger, well-educated and better nutritional status (P < 0.05). At the baseline, no association was found between all-cause and CV death in either total or different types of FA after adjusting for nutritional variables. As for time-averaged analyses, the associations of TFA, saturated FA (SFA), monounsaturated FA (MUFA), ω-3 and ω-6 polyunsaturated FA (PUFA) and all-cause mortality were weakened after adjustment for laboratory and nutrients variables. However, PUFA independently reduced 5% of mortality even after adjustment for laboratory and nutrients variables [HR 0.95 (0.91, 0.99), P = 0.023], and the ratio of MUFA/PUFA was positively associated with the risk for all-cause mortality [HR 1.05 (1.01, 1.09), P = 0.008]. Furthermore, each 10% increase of the ratio of ω-6/ω-3 was only weakly associated with the risk for all-cause mortality [HR 1.02 (1.00, 1.04), P = 0.034]. As for CVD mortality, the impacts of total and each type of FA disappeared after adjustment for laboratory or nutrients variables.

CONCLUSIONS

Time-averaged PUFA intake was independently associated with a lower risk for all-cause mortality in our PD cohort, while the higher ratio of MUFA/PUFA and ω-6/ω-3 increased all-cause mortality. More observational and interventional researches are needed to determine these associations.

Targeting the Endothelin A Receptor in IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and carries a substantial risk of kidney failure. New agency-approved therapies, either specifically for IgAN or for chronic kidney disease (CKD) in general, hold out hope for mitigating renal deterioration in patients with IgAN. The latest addition to this therapeutic armamentarium targets the endothelin-A receptor (ETAR). Activation of ETAR on multiple renal cell types elicits a host of pathophysiological effects, including vasoconstriction, cell proliferation, inflammation, apoptosis, and fibrosis. Blockade of ETAR is renoprotective in experimental models of IgAN and reduces proteinuria in patients with IgAN. This review discusses the evidence supporting the use of ETAR blockade in IgAN as well as addressing the potential role for this class of agents among the current and emerging therapies for treating this disorder.

Neuroblastoma suppressor of tumorigenicity 1 is associated with the severity of interstitial fibrosis and kidney function decline in IgA nephropathy

INTRODUCTION

Recently, circulating neuroblastoma suppressor of tumorigenicity 1 (NBL1) was shown to be strongly associated with kidney disease progression and histological lesions in patients with diabetic kidney disease. This study aimed to examine whether serum NBL1 level was also associated with kidney function and renal histological findings in patients with IgA nephropathy.

METHODS

We evaluated the levels of NBL1 in 109 patients with newly diagnosed biopsy-proven primary IgAN, between 2009 and 2018, at the Nihon University School of Medicine Itabashi Hospital, Tokyo, Japan, using serum obtained immediately before the renal biopsy, and examined the relationship between serum NBL1, renal function and renal histological findings assessed using the Oxford Classification (MEST score). Furthermore, we analyzed the association of serum NBL1 with kidney function decline over time in patients with IgA nephropathy who had follow-up data on the estimated glomerular filtration rate (n = 76).

RESULTS

Serum NBL1 levels in patients with newly diagnosed IgA nephropathy were elevated, as compared to those in healthy individuals (n = 93). Logistic regression analysis demonstrated that the serum NBL1 level was independently and significantly associated with tubular atrophy/interstitial fibrosis. Immunohistochemical staining revealed that NBL1 was highly expressed in the tubulointerstitium. Furthermore, Spearman's rank correlation identified a significant correlation between serum NBL1 level and estimated glomerular filtration rate slope.

CONCLUSIONS

The serum NBL1 level was significantly associated with the severity of renal interstitial fibrosis and kidney disease progression in patients with newly diagnosed IgA nephropathy. Thus, circulating NBL1 may serve as a good biomarker for evaluating renal interstitial fibrosis and the risk of kidney disease progression.

A novel prognostic nomogram predicts premature failure of kidney allografts with IgA nephropathy recurrence

BACKGROUND

Recurrence of immunoglobulin A nephropathy (IgAN) limits graft survival in kidney transplantation. However, predictors of a worse outcome are poorly understood.

METHODS

Among 442 kidney transplant recipients (KTRs) with IgAN, 83 (18.8%) KTRs exhibited biopsy-proven IgAN recurrence between 1994 and 2020 and were enrolled in the derivation cohort. A multivariable Cox model predicting allograft loss based on clinical data at the biopsy and a web-based nomogram were developed. The nomogram was externally validated using an independent cohort (n = 67).

RESULTS

Patient age <43 years {hazard ratio [HR] 2.20 [95% confidence interval (CI) 1.41-3.43], P < .001}, female gender [HR 1.72 (95% CI 1.07-2.76), P = .026] and retransplantation status [HR 1.98 (95% CI 1.13-3.36), P = .016] were identified as independent risk factors for IgAN recurrence. Patient age <43 years [HR 2.77 (95% CI 1.17-6.56), P = .02], proteinuria >1 g/24 hours [HR 3.12 (95% CI 1.40-6.91), P = .005] and C4d positivity [HR 2.93 (95% CI 1.26-6.83), P = .013] were found to be associated with graft loss in patients with IgAN recurrence. A nomogram predicting graft loss was constructed based on clinical and histological variables, with a C statistic of 0.736 for the derivation cohort and 0.807 for the external validation cohort.

CONCLUSIONS

The established nomogram identified patients with recurrent IgAN at risk for premature graft loss with good predictive performance.

IgA nephropathy in adults-treatment standard

Immunoglobulin A nephropathy (IgAN) is the most common primary form of glomerular disease worldwide and carries a high lifetime risk of kidney failure. The underlying pathogenesis of IgAN has been characterized to a sub-molecular level; immune complexes containing specific O-glycoforms of IgA1 are central. Kidney biopsy remains the gold-standard diagnostic test for IgAN and histological features (i.e. MEST-C score) have also been shown to independently predict outcome. Proteinuria and blood pressure are the main modifiable risk factors for disease progression. No IgAN-specific biomarker has yet been validated for diagnosis, prognosis or tracking response to therapy. There has been a recent resurgence of investigation into IgAN treatments. Optimized supportive care with lifestyle interventions and non-immunomodulatory drugs remains the backbone of IgAN management. The menu of available reno-protective medications is rapidly expanding beyond blockade of the renin-angiotensin-aldosterone system to include sodium-glucose cotransporter 2 and endothelin type A receptor antagonism. Systemic immunosuppression can further improve kidney outcomes, although recent randomized controlled trials have raised concerns regarding infectious and metabolic toxicity from systemic corticosteroids. Studies evaluating more refined approaches to immunomodulation in IgAN are ongoing: drugs targeting the mucosal immune compartment, B-cell promoting cytokines and the complement cascade are particularly promising. We review the current standards of treatment and discuss novel developments in pathophysiology, diagnosis, outcome prediction and management of IgAN.

Validation of the international IgA nephropathy prediction tool in a French cohort beyond 10 years after diagnosis

INTRODUCTION

The International IgA Nephropathy Network developed a tool (IINN-PT) for predicting the risk of end-stage renal disease (ESRD) or a 50% decline in the estimated glomerular filtration rate (eGFR). We aimed to validate this tool in a French cohort with longer follow-up than previously published validation studies.

METHODS

The predicted survival of patients with biopsy-proven immunoglobulin A nephropathy (IgAN) from the Saint Etienne University Hospital cohort was computed with IINN-PT models with or without ethnicity. The primary outcome was the occurrence of either ESRD or a 50% decline in eGFR. The models' performances were evaluated through c-statistics, discrimination and calibration analysis.

RESULTS

There were 473 patients with biopsy-proven IgAN, with a median follow-up of 12.4 years. Models with and without ethnicity showed areas under the curve (95% confidence interval) of 0.817 (0.765; 0.869) and 0.833 (0.791; 0.875) and R2D of 0.28 and 0.29, respectively, and an excellent discrimination of groups of increasing predicted risk (P < .001). The calibration analysis was good for both models up to 15 years after diagnosis. The model without ethnicity exhibited a mathematical issue of survival function after 15 years.

DISCUSSION

The IINN-PT provided good performances even after 10 years post-biopsy as showed by our study based on a cohort with a longer follow-up than previous cohorts (12.4 versus <6 years). The model without ethnicity exhibited better performances up to 15 years but became aberrant beyond this point due to a mathematical issue affecting the survival function. Our study sheds light on the usefulness of integrating ethnicity as a covariable for prediction of IgAN course.

Effect of SGLT2 inhibitors on the proteinuria reduction in patients with IgA nephropathy

Backgroud

Recent trials suggest sodium-glucose cotransporter 2 inhibitors (SGLT2i) significantly reduced proteinuria in patients with IgA nephropathy (IgAN). While little was known its efficacy in clinical practice especially in those already received full dose reninangiotensin-aldosterone system (RAAS) inhibitors.

Methods

A cohort of 93 Chinese patients with biopsy-proven IgAN and persistent proteinuria underwent full supportive therapy, including optimal blood pressure control and full dose angiotensin-converting enzyme-inhibitor or angiotensin receptor blocker therapy. Proteinuria reduction at three and six months after initiating SGLT2i therapy was analyzed.

Results

A total of 93 patients were enrolled in this study and 62 of them completed the six-month follow-up. After SGLT2i administration, a significant reduction in proteinuria was observed, with a decrease of 22.9% (p < 0.001) at three months and 27.1% (p < 0.001) at six months. During the six-month follow-up period, a decline of 3.0 mL/min/1.73m2 in estimated glomerular filtration rate (eGFR) (p = 0.012) and an increase of 0.8 g/L in albumin (p = 0.017) were observed. The anti-hypertensive effect of SGLT2i was not significant (p > 0.05). Notably, a consistent antiproteinuric effect of SGLT2i was observed across various settings, including different age groups, baseline levels of proteinuria/eGFR, use of immunosuppressive agents, and the presence of comorbid diabetes and hypertension (all p values >0.05).

Conclusion

The proteinuria was significantly reduced after SGLT2i administration in IgAN patients with full dose angiotensin-converting enzyme-inhibitor or angiotensin receptor blocker therapy. Importantly, the antiproteinuric effect of SGLT2i was observed independently of immunosuppressive agent therapy, age, baseline eGFR and proteinuria levels, as well as the history of hypertension and diabetes.

Clinicopathological Characteristics of Adult IgA Nephropathy in the United States

Introduction

IgA nephropathy (IgAN) is a progressive autoimmune kidney disease and a leading cause of glomerular disease that can result in kidney failure (KF). The median age at diagnosis is 35 to 37 years and approximately 50% of patients will progress to KF within 20 years. We aimed to enhance the understanding of renal histology and chronic kidney disease (CKD) stage at the time of IgAN diagnosis using a large real-world biopsy cohort.

Methods

This retrospective cohort study evaluated biopsy data and clinical characteristics from adult patients within the US who were diagnosed with IgAN between January 1, 2016 to May 31, 2020. Descriptive statistics were summarized and relationship(s) between each Oxford Classification (MEST-C) component score with 24-hour proteinuria or CKD stage were examined using regression analysis.

Results

A total of 4375 patients (mean age 47.7 years, 62.7% male) met eligibility criteria. Mild to moderate mesangial hypercellularity (47.3%), segmental sclerosis (65.0%), tubular atrophy ≥25% (57.4%), and crescents (18.5%) were identified; and 74.6% of patients were at CKD stage ≥3. Proteinuria ≥1 g/d was associated with higher MEST-C scores, and the odds of mesangial hypercellularity, segmental sclerosis, tubular atrophy, and crescents increased with CKD stage.

Conclusion

Most patients with IgAN in our US cohort were diagnosed at CKD stage ≥3 and had high MEST-C scores and proteinuria that are suggestive of significant disease burden at the time of kidney biopsy. Strategies are required to raise awareness and promote earlier detection of asymptomatic urinary abnormalities before extensive irreversible kidney damage has occurred.

Immunosuppression versus Supportive Care on Kidney Outcomes in IgA Nephropathy in the Real-World Setting

BACKGROUND

The efficacy of immunosuppression in the management of immunoglobulin A (IgA) nephropathy remains highly controversial. The study was conducted to assess the effect of immunosuppression, compared with supportive care, in the real-world setting of IgA nephropathy.

METHODS

A cohort of 3946 patients with IgA nephropathy, including 1973 new users of immunosuppressive agents and 1973 propensity score-matched recipients of supportive care, in a nationwide register data from January 2019 to May 2022 in China was analyzed. The primary outcome was a composite of 40% eGFR decrease of the baseline, kidney failure, and all-cause mortality. A Cox proportional hazard model was used to estimate the effects of immunosuppression on the composite outcomes and its components in the propensity score-matched cohort.

RESULTS

Among 3946 individuals (mean [SD] age 36 [10] years, mean [SD] eGFR 85 [28] ml/min per 1.73 m 2 , and mean [SD] proteinuria 1.4 [1.7] g/24 hours), 396 primary composite outcome events were observed, of which 156 (8%) were in the immunosuppression group and 240 (12%) in the supportive care group. Compared with supportive care, immunosuppression treatment was associated with 40% lower risk of the primary outcome events (adjusted hazard ratio, 0.60; 95% confidence interval, 0.48 to 0.75). Comparable effect size was observed for glucocorticoid monotherapy and mycophenolate mofetil alone. In the prespecified subgroup analysis, the treatment effects of immunosuppression were consistent across ages, sexes, levels of proteinuria, and values of eGFR at baseline. Serious adverse events were more frequent in the immunosuppression group compared with the supportive care group.

CONCLUSIONS

Immunosuppressive therapy, compared with supportive care, was associated with a 40% lower risk of clinically important kidney outcomes in patients with IgA nephropathy.

Treatment and outcome of IgA nephropathy in children from one single center experience

BACKGROUND

There is no standard recommendation for IgA nephropathy treatment in children.

METHODS

This is a retrospective study. From 2012 to 2020, newly diagnosed primary IgAN followed up for at least 1 year were enrolled. The correlation of MESTC scores and clinical index including proteinuria, gross hematuria and renal dysfunction was analyzed. Treatment and clinical response of 6 month, 1year and 3 year at follow up were also analyzed. Complete renal remission was calculated with Kaplan-Meier analysis.

RESULTS

The median follow up was 36 months, from 12 months to 87months in 40 IgAN children. Angiotensin-converting enzyme inhibitor (ACEI) was applied to all patients. 30% received ACEI alone; 15% received glucocorticoids; 37.5% received glucocorticoids plus cyclophosphamide, 17.5% received glucocorticoids plus mycophenolate mofetil. Individuals with diffuse mesangial hypercellularity (M1) were more likely to have nephrotic range proteinuria compared to patients with M0 (80% vs. 20%, P < 0.01). Complete renal remission at 6-month, 1-year and 3-year follow up is 50.25%, 70% and 87.5% respectively. Five-year complete renal remission calculated by Kaplan-Meier analysis is 58.4%. Although without significant difference, there is trend of better survival with complete renal remission in group of nephrotic range proteinuria onset. There is no severe adverse effect.

CONCLUSION

This study supports the use of glucocorticoids plus immunosuppressive in addition to ACEI in IgA nephrology pediatric patients with proteinuria. We suggest proactive immunosuppressive treatment in IgA nephropathy in children. This is from a single center in China as may not same results in other population.

Urinary N-Acetyl-Beta-D-Glucosaminidase levels predict immunoglobulin a nephropathy remission status

BACKGROUND

Tubulointerstitial lesions play a pivotal role in the progression of IgA nephropathy (IgAN). Elevated N-acetyl-beta-D-glucosaminidase (NAG) in urine is released from damaged proximal tubular epithelial cells (PTEC) and may serve as a biomarker of renal progression in diseases with tubulointerstitial involvement.

METHODS

We evaluated the predictive value of urinary NAG (uNAG) for disease progression in 213 biopsy-proven primary IgAN patients from January 2018 to December 2019 at Zhongshan Hospital, Fudan University. We compared the results with those of serum cystatin C (sCysC).

RESULTS

Increased uNAG and sCysC levels were associated with worse clinical and histological manifestations. Only uNAG level was independently associated with remission status after adjustment. Patients with high uNAG levels (> 22.32 U/g Cr) had a 4.32-fold greater risk of disease progression. The combination of baseline uNAG and clinical data may achieve satisfactory risk prediction in IgAN patients with relatively preserved renal function (eGFR ≥ 60 ml/min/1.73 m2, area under the curve [AUC] 0.760).

CONCLUSION

Our results suggest that uNAG is a promising biomarker for predicting IgAN remission status.

The Effects of Perilla frutescens Extracts on IgA Nephropathy: A Systematic Review and Meta-Analysis

(1) Background: Chronic renal disorders (CRD) are associated with significant comorbidities and necessitate complex therapeutic management. As time passed, Perilla frutescens (PF) became a promising therapeutic option for CRD. The aim of this systematic review and meta-analysis was to outline the therapeutic effects of PF extracts on various models of immunoglobulin a (IgA) nephropathy; (2) Methods: Medline, Embase, and Cochrane databases were used to find relevant studies. All prospective interventional studies that evaluated the effect of PF extract versus placebo on rat models of chronic renal disorders were assessed according to the international guidelines; (3) Results: Our search yielded 23 unique records, out of which only five were included in the analysis. Our results showed that administration of PF extracts led to a statistically significant reduction in proteinuria and PCNA levels in rats that received high doses of the extract as well as in the PCNA level and DNA synthesis in rats that received low doses of the extract. The evaluated outcomes benefited from a low degree of heterogeneity; (4) Conclusions: Some of the evaluated outcomes were significantly reduced by both high and low doses of extracts from Perilla frutescens. Further studies are needed to determine the exact effect over IgA nephropathy in human subjects.