A Global Evolutionary Trend of the Frequency of Primary Glomerulonephritis over the Past Four Decades

The burden of chronic kidney disease in Asia region: a review of the evidence, current challenges, and future directions

The disease burden of chronic kidney disease (CKD) and its impact on healthcare systems has been poorly studied in Asia, a socioeconomically diverse region with wide variations in availability, access, and quality of CKD care. The high CKD burden in this region is predominantly driven by an increased prevalence of risk factors including diabetes mellitus, hypertension, obesity, and use of traditional medicines and is further aggravated by challenges associated with effective implementation of population-based screening and surveillance systems in early detection and intervention of CKD. The Asian continent mostly comprised of low- and middle-income countries with resource restraints lacks robust population-based CKD registries resulting in a paucity of data on CKD incidence and prevalence, various treatment modalities, uptake of current guidelines, and the overall impact of implementation of developmental programs. There is an urgent need for a collaborative action plan between the healthcare community and governments in this region to detect CKD in its early stages and prevent its complications including kidney failure, cardiovascular disease, and death. Research- based evidence on the impact of early detection, sustainable treatment options, quality of life, delay or avoidance of dialysis, and related cost analysis is the need of the hour. We highlight successful implementation of strategic and policy-sharing programs adopted in a few countries; also, consolidate available region-specific data, quantify estimates of CKD burden and propose strategies with a multidisciplinary approach involving patients, the healthcare community and governmental bodies to combat CKD and its complications.

Integration of metabolomics and transcriptomics reveals the mechanism of TMEM30A downregulation induced FSGS podocyte injury

Podocyte injury plays a critical role in the pathogenesis and progression of focal and segmental glomerulosclerosis (FSGS). Transmembrane protein 30 A (TMEM30A) downregulation participates in podocyte injury. This study aimed to identify the critical pathways and molecules associated with the downregulation of TMEM30A in the context of FSGS podocyte injury. In our study, we found that TMEM30A and podocyte marker Synaptopodin were significantly downregulated in kidney tissues from patients with FSGS compared with those in normal controls. Using transcriptomic and metabolomic analyses, we characterized Tmem30a knockdown (KD) and normal mouse podocytes to identify differentially expressed genes and metabolites. Then, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Set Enrichment Analysis (GSEA), and Protein-Protein Interaction (PPI) network were constructed, and the differentially expressed genes and metabolites were enriched into glycolytic pathway. Furthermore, we found that the key glycolytic enzymes were downregulated in patients with FSGS, podocyte-specific Tmem30aLoxP/LoxP; NPHS2-Cre mice, and Tmem30a KD mouse podocytes. For rescue experiments, shTmem30a-resistant cDNA (resTmem30a) was created to intervene Tmem30a KD mouse podocytes. And we observed that podocyte-related molecules were downregulated in the Tmem30a KD group, along with glycolysis-related molecules, but the resTmem30a partially reversed this trend. Our findings clarified that TMEM30A downregulation initiates podocyte injury by reducing glycolysis-related molecules (ALDOA, HK2, LDHA, and GAPDH) in FSGS and has implications for early diagnosis, prevention, and treatment.NEW & NOTEWORTHY This study aimed to identify the key pathways and molecules of TMEM30A downregulation involved in FSGS podocyte injury. Through comprehensive transcriptomic and metabolomic analyses, as well as in vivo and in vitro experiments, we discovered that the downregulation of TMEM30A triggers podocyte injury by decreasing the levels of glycolysis-related molecules, including ALDOA, HK2, LDHA, and GAPDH, in FSGS.

Mendelian study on air pollution and membranous nephropathy outcomes associations

Membranous nephropathy (MN) is an autoimmune disease of the kidney glomerulus, which mainly leads to nephrotic syndrome. This study investigates the associations between air pollution and MN risk and from an epigenomic perspective. In this study, we examine the associations between genetically predicted deoxyribonucleic acid methylation related to air pollution and MN risk. The data of air pollution included particulate matter (PM) with a diameter of 2.5 µm or less (PM2.5), PM with a diameter between 2.5 and 10 µm (PM2.5-10), PM with a diameter of 10 µm or less (PM10), nitrogen dioxide, and nitrogen oxides. Inverse variance weighted method was used as the main analysis method, and weighted median model and Mendelian randomization-Egger methods were selected for quality control. To assess the reliability of the results of the analyses, heterogeneity test, horizontal pleiotropy test, and the leave-one-out method were applied. There was a causal relationship between nitrogen oxides and MN risk (P = .010). Other types of air pollution were found no statistical association with MN disease (PM2.5: P = .378; PM2.5-10: P = .111; PM10: P = .035; nitrogen dioxide: P = .094). There was no heterogeneity or pleiotropy in the results. Our study suggests the association between nitrogen oxides and membrane nephropathy (MN) risk from the genetic perspective. This provides a theoretical basis for the prevention of MN disease.

Regulatory role of the mTOR signaling pathway in autophagy and mesangial proliferation in IgA nephropathy

OBJECTIVES

IgA nephropathy (IgAN) is the most common primary glomerular disease in China, but its pathogenesis remains unclear. This study aims to explore the regulatory role of the mammalian target of rapamycin (mTOR) signaling pathway in autophagy and mesangial proliferation during renal injury in IgA.

METHODS

The activity of mTOR and autophagy was evaluated in kidney samples from IgAN patients and in an IgAN mouse model induced by oral bovine serum albumin and carbon tetrachloride (CCl4) injection. mTOR inhibitors (rapamycin) and activators [bpV(phen)] were administered to the IgAN mouse model to observe the effects of mTOR on autophagy and renal lesions. In human mesangial cells treated with polymeric IgA1 (p-IgA1) and mTOR modulators, the expression and distribution of cell cycle proteins were assessed, along with the effects of mTOR on mesangial cell proliferation and autophagy.

RESULTS

Increased mTOR activity and decreased autophagy were observed in kidney tissues from IgAN patients and the mouse model, as evidenced by elevated phosphorylated mTOR (p-mTOR) levels and reduced LC3 expression. In the IgAN mouse model, rapamycin inhibited mTOR, restored autophagy, reduced mesangial IgA deposition, alleviated mesangial cell proliferation, and decreased proteinuria (all P<0.05). In contrast, bpV(phen) activated mTOR, further suppressed autophagy, exacerbated kidney damage, and increased proteinuria (all P<0.05). In vitro, p-IgA1 induced mesangial cell proliferation and inhibited autophagy, effects that were reversed by rapamycin and aggravated by bpV(phen) (all P<0.05). mTOR regulated mesangial cell proliferation by altering cell cycle distribution, with rapamycin inducing G1 phase arrest and bpV(phen) promoting cell cycle progression. Additionally, cyclinD1 expression in renal cortex was up-regulated in the IgAN mouse model, further increased by bpV(phen), and reduced by rapamycin (all P<0.05).

CONCLUSIONS

Inhibition of the mTOR signaling pathway enhances renal autophagy, reduces mesangial cell proliferation, and improves renal injury in IgAN.

Glomerular IgG deposition predicts kidney disease progression in IgA nephropathy

Objective

We aimed to explore the relationship between the presence and intensity of glomerular IgG deposition and the occurrence of kidney progression events in IgA nephropathy (IgAN).

Methods

This retrospective study encompassed a total of 1207 patients with IgAN spanning the period from 2010 to 2022, and complete follow-up data were accessible for 736 patients. The IgG intensity was categorized as follows: low-level, defined as IgG (±) and IgG (+), and high-level, defined as IgG (++) and IgG (+++).

Results

We found that the IgG-positive deposited group (N = 113, 9.36%) had significantly higher levels of ESR, TC, LDL, uric acid, proteinuria, and blood glucose, and lower serum albumin level compared to the IgG-negative deposited group (N = 1094, 90.64%). In terms of pathology, the IgG-positive deposited group had a significantly higher percentage of T2 score compared to the IgG-negative deposited group (p = 0.002). At the end of the follow-up period, the IgG-positive deposited group had a higher eGFR decline (-5.7 ± 4.37 ml/year) compared to the IgG-negative deposited group (-4 ± 2.52 ml/year), however, there was not a statistically significant difference between the two groups (p = 0.096). We observed that the high-IgG group had significantly higher level of TG compared to the low-IgG group (p = 0.042). Further analysis revealed that the group of patients with high level of IgG deposition in the kidney experienced a higher incidence of composite kidney outcomes compared to the group with low level of IgG deposition (p = 0.009). Logistic regression analyses showed that high level IgG deposition was an independent risk factor for kidney progression of IgAN (HR 13.419; 95% CI 2.690-66.943, P = 0.029). Further analyses for a solid conclusion using Cox regression that we found high level IgG deposition (HR 115.277; 95% CI 2.299-5.779E3, P = 0.017), eGFR (HR 0.932; 95% CI 0.870-0.999, P = 0.047), and urine protein excretion (HR 1.001; 95% CI 1.000-1.002, P = 0.015) were independent risk factor for kidney progression of IgAN.

Conclusions

The intensity of IgG deposition has been found to be associated with the progression of IgAN. Future prospective studies should provide more robust evidence on the impact of IgG deposition on kidney outcomes in patients with IgAN.

Five-Year study on renal outcomes in biopsy-proven focal segmental glomerulosclerosis patients in Shiraz, Iran

Background

Focal segmental glomerulosclerosis (FSGS) is a prevalent glomerular disease that often leads to nephrotic syndrome. It is characterized by consolidating a portion of the glomerular capillary tuft connected to Bowman's capsule. This retrospective cohort study aimed to determine the demographic characteristics, risk factors, and prognostic indicators associated with FSGS in Shiraz, Iran.

Methods

The study included 53 primary FSGS patients aged over 18 years who were referred to clinics affiliated with Shiraz University of Medical Sciences. Data were collected through a comprehensive data-gathering sheet encompassing demographic information, medical history, laboratory test results, and histopathological findings. Statistical analysis was performed using SPSS 18, considering a significance level of p<0.05.

Results

A five-year follow-up was conducted on the 53 patients, with the mean age of 41.0±13.3 years. The most common FSGS variants observed were "not otherwise specified" (NOS, 13.2%) and tip variant (7.5%). Older patients exhibited higher disease activity, whereas remission rates were higher among younger individuals (P=0.012). Patients achieving remission had lower creatinine and Pro/Cr ratios and higher glomerular filtration rates (p<0.05). Treatment involving a combination of corticosteroids and mycophenolate mofetil showed a significant correlation with remission (P=0.036).

Conclusion

Older patients with higher creatinine levels, higher Pro/Cr ratios, and lower glomerular filtration rates at disease onset may require more aggressive treatment. Combination therapy with mycophenolate mofetil and corticosteroids yields better outcomes, leading to increased remission rates. These findings provide valuable insights for managing FSGS patients.

How to Choose the Right Treatment for Membranous Nephropathy

Membranous nephropathy is an autoimmune disease affecting the glomeruli and is one of the most common causes of nephrotic syndrome. In the absence of any therapy, 35% of patients develop end-stage renal disease. The discovery of autoantibodies such as phospholipase A2 receptor 1, antithrombospondin and neural epidermal growth factor-like 1 protein has greatly helped us to understand the pathogenesis and enable the diagnosis of this disease and to guide its treatment. Depending on the complications of nephrotic syndrome, patients with this disease receive supportive treatment with diuretics, ACE inhibitors or angiotensin-receptor blockers, lipid-lowering agents and anticoagulants. After assessing the risk of progression of end-stage renal disease, patients receive immunosuppressive therapy with various drugs such as cyclophosphamide, steroids, calcineurin inhibitors or rituximab. Since immunosuppressive drugs can cause life-threatening side effects and up to 30% of patients do not respond to therapy, new therapeutic approaches with drugs such as adrenocorticotropic hormone, belimumab, anti-plasma cell antibodies or complement-guided drugs are currently being tested. However, special attention needs to be paid to the choice of therapy in secondary forms or in specific clinical contexts such as membranous disease in children, pregnant women and patients undergoing kidney transplantation.

Years of life lost and long-term outcomes due to glomerular disease in a Southeast Asian Cohort

Death and end-stage kidney disease (ESKD) are major outcomes of glomerular disease. (GD) The years of potential life lost (YLL) may provide additional insight into the disease burden beyond death rates. There is limited data on premature mortality in GD. In this retrospective observational cohort study, we evaluated the mortality, ESKD rates, and YLL in Thais with biopsy-proven GD. The mortality and combined outcome rates were determined by log-rank test and ESKD by using a competing risk model. YLL and premature life lost before age 60 were calculated for different GD based on the life expectancy of the Thai population. Patients with GD (n = 949) were followed for 5237 patient years. The death rate and ESKD rates (95%CI) were 4.2 (3.7-4.9) and 3.3 (2.9-3.9) per 100 patient-years, respectively. Paraprotein-related kidney disease had the highest death rate, and diabetic nephropathy had the highest ESKD rate. Despite not having the highest death rate, lupus nephritis (LN) had the highest YLL (41% of all GD) and premature loss of life before age 60. In conclusion, YLL provided a different disease burden assessment compared to mortality rates and identified LN as the major cause of premature death due to GD in a Southeast Asian cohort.

The incidence and prevalence of IgA nephropathy in Europe

BACKGROUND

This study aimed to determine the incidence and prevalence of immunoglobulin A nephropathy (IgAN) in Europe based on high-quality data from national registries.

METHODS

IgAN incidences were obtained from a literature review of European studies of national kidney biopsy registry data in which IgAN diagnosis was biopsy-verified using contemporary techniques. Studies were eligible for the main analysis if published from 1990 to 2020. IgAN point prevalence was defined as the annual IgAN incidence multiplied by the estimated duration of disease. Incidence and prevalence estimates were made for three pooled populations: (i) patients of all ages; (ii) pediatric patients; and (iii) elderly patients.

RESULTS

Across 10 European countries, the estimated annual IgAN incidence was 0.76 per 100 000 in patients of all ages. The corresponding pooled IgAN point prevalence was 2.53 per 10 000 (95% confidence interval: 2.51-2.55), ranging from 1.14 per 10 000 in Spain to 5.98 per 10 000 in Lithuania. Applied to 2021 population estimates, the number of expected prevalent IgAN cases was 47 027 across all 10 countries and ranged from 577 in Estonia to 16 645 in Italy. Among pediatric patients, IgAN incidence was 0.20 per 100 000 children and IgAN point prevalence was 0.12 per 10 000 children. Among elderly patients, IgAN incidence was 0.30 per 100 000 and IgAN point prevalence was 0.36 per 10 000.

CONCLUSIONS

Based on high-quality data from European national registries, IgAN point prevalence was estimated at 2.53 per 10 000 in patients of all ages. Prevalence was considerably lower in pediatric and elderly populations.

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.

Clinical Course of Adult FSGS and Minimal Change Disease in North American and Japanese Cohorts

Key Points

Data from different geographical regions highlighted the differences in clinical manifestations and treatment response of adult FSGS/minimal change disease. There were shared factors that were associated with treatment response across the cohorts: FSGS, higher BP, and lower eGFR. Recognizing geographical difference allows us better understanding of disease biology, risk prediction, and design of future clinical trials.

Background

Regional differences in presentation and clinical course of nephrotic syndrome (NS) have not been studied well because few studies directly compared the data from different intercontinental regions.

Methods

We included adult nephrotic patients with FSGS and minimal change disease (MCD) who received immunosuppressive therapy (IST) in a North American (Nephrotic Syndrome Study Network [NEPTUNE], N =89) or Japanese (Nagoya Kidney Disease Registry [N-KDR], N =288) cohort. Baseline characteristics and rates of complete remission (CR) were compared. Factors associated with time to CR were evaluated by Cox regression models.

Results

NEPTUNE participants had more FSGS (53.9 versus 17.0%) and family history of kidney disease (35.2 versus 3.2%). N-KDR participants were older (median 56 versus 43 years) and demonstrated greater levels of urine protein creatinine ratio (7.73 versus 6.65) and hypoalbuminemia (1.6 versus 2.2 mg/dl). N-KDR participants showed higher proportion of CR (overall: 89.2 versus 62.9%; FSGS: 67.3 versus 43.7%; MCD: 93.7 versus 85.4%). A multivariable model showed that FSGS (versus MCD: hazard ratio [HR], 0.28; 95% confidence interval [CI], 0.20 to 0.41), systolic BP (per 10 mm Hg: HR, 0.93; 95% CI, 0.86 to 0.99), and eGFR (per 10 ml/min per 1.73 m2: HR, 1.16; 95% CI, 1.09 to 1.24) were associated with time to CR. There were significant interactions in patient age (P = 0.004) and eGFR (P = 0.001) between the cohorts.

Conclusions

The North American cohort had more FSGS and more frequent family history. Japanese patients showed more severe NS with better response to IST. FSGS, hypertension, and lower eGFR were shared predictors of poor treatment response. Identifying shared and unique features across geographically diverse populations may help uncover biologically relevant subgroups, improve prediction of disease course, and better design future multinational clinical trials.

Epidemiology and Outcomes of Glomerular Diseases in Low- and Middle-Income Countries

Glomerular diseases account for a significant proportion of chronic kidney disease in low-income and middle-income countries (LMICs). The epidemiology of glomerulonephritis is characterized inadequately in LMICs, largely owing to unavailable nephropathology services or uncertainty of the safety of the kidney biopsy procedure. In contrast to high-income countries where IgA nephropathy is the dominant primary glomerular disease, focal segmental glomerulosclerosis is common in large populations across Latin America, Africa, Middle East, and South East Asia, while IgA nephropathy is common in Chinese populations. Despite having a high prevalence of known genetic and viral risk factors that trigger focal segmental glomerulosclerosis, membranoproliferative glomerulonephritis also is common in adults and children in some African countries. Treatment of glomerular diseases in adults and children in LMICs largely is dependent on corticosteroids in combination with other immunosuppressive therapy, which often is cyclophosphamide because of its ready availability and low cost of treatment, despite significant adverse effects. Partial and/or complete remission status reported from studies of glomerular disease subtypes vary across LMIC regions, with high rates of kidney failure, mortality, and disease, and treatment complications often reported. Improving the availability of nephropathology services and ensuring availability of specific therapies are key measures to improving glomerular disease outcomes in LMICs.

The pathological spectrum of pediatric kidney disease: 18-Year experience from a single tertiary care center in northern Taiwan

BACKGROUND

Glomerular disease is one of the leading causes of chronic kidney disease in children worldwide. Recent studies outlined the changing spectrum of glomerular disease in certain countries. Therefore, our study aimed to evaluate the histopathological patterns and changes in pediatric kidney disease over the past 18 years in northern Taiwan.

METHODS

This was a retrospective chart review study of pediatric patients (≤18 years of age) undergoing percutaneous renal biopsies (PRBs) of native kidneys between January 2002 and July 2020 from a Pediatric Care Center at Chang Gung Memorial Hospital, Taoyuan, Taiwan.

RESULTS

This study analyzed a total of 339 pediatric native PRBs. The mean age of the subjects was 13.7 ± 7.0 years (184 girls and 155 boys). The most common indications of PRBs included acute nephritic syndrome (55.7%), idiopathic nephrotic syndrome (22.7%), persistent asymptomatic hematuria (13.9%), and unexplained renal failure (7.7%). Our study revealed that proliferative lupus nephritis (LN), minimal change disease (MCD)-related nephrotic syndrome, and IgA nephropathy (IgAN) were the most frequent biopsy-proven pediatric glomerular diseases. In addition, we showed that severe acute post-streptococcal glomerulonephritis (APSGN) was infrequent and has not even been diagnosed since 2010.

CONCLUSION

Our result revealed that the spectrum of biopsy-proven pediatric kidney disease has not changed significantly over the past two decades. Furthermore, proliferative LN, MCD, and primary IgAN continue to be the most common histopathological diagnoses among Taiwanese children.

The IRE1α pathway in glomerular diseases: The unfolded protein response and beyond

Endoplasmic reticulum (ER) function is vital for protein homeostasis ("proteostasis"). Protein misfolding in the ER of podocytes (glomerular visceral epithelial cells) is an important contributor to the pathogenesis of human glomerular diseases. ER protein misfolding causes ER stress and activates a compensatory signaling network called the unfolded protein response (UPR). Disruption of the UPR, in particular deletion of the UPR transducer, inositol-requiring enzyme 1α (IRE1α) in mouse podocytes leads to podocyte injury and albuminuria in aging, and exacerbates injury in glomerulonephritis. The UPR may interact in a coordinated manner with autophagy to relieve protein misfolding and its consequences. Recent studies have identified novel downstream targets of IRE1α, which provide new mechanistic insights into proteostatic pathways. Novel pathways of IRE1α signaling involve reticulophagy, mitochondria, metabolism, vesicular trafficking, microRNAs, and others. Mechanism-based therapies for glomerulopathies are limited, and development of non-invasive ER stress biomarkers, as well as targeting ER stress with pharmacological compounds may represent a therapeutic opportunity for preventing or attenuating progression of chronic kidney disease.

Clinical outcomes and performance indicators of patients with kidney failure and acute kidney injuries in ASEAN countries

INTRODUCTION

This review article reports clinical outcomes and performance indicators of patients with kidney failure (KF) and acute kidney injuries (AKI) in Association of South East Asian Nations (ASEAN) countries.

METHODOLOGY

Association of South East Asian Nations data, segregated by income status, from national registries and literature were collated, compared and benchmarked against international references.

RESULTS

The national incidence and prevalence of treated KF ranged from 172 to 479 per million population (pmp) and 36-2255 pmp, respectively. Brunei (79%), Malaysia (66%) and Singapore (66%) had world-leading proportions of diabetes-related KF. Hemodialysis (HD), Peritoneal Dialysis (PD) and transplant accounted for 68-100%, 0-27% and 0-18% of all KF replacement therapy, respectively. Transplant patient survival was superior with 90%-93% at 5 years and 71%-90% at 10 years, compared to PD (44%-54%) and HD (53-64%) at 5 years. Higher-income countries were able to achieve good anemia control, HD and PD adequacy targets, while usage of arteriovenous fistula in HD varied from 70% to 85%. Acute Kidney Injury rates ranged from 24.2% to 49.2% of high-dependency admissions. Lower incidences of PD peritonitis and HD catheter-related Bloodstream Infections; and PD-favouring quality-of-life were evident in higher-income countries.

CONCLUSION

Association of South East Asian Nations has a challenging burden of kidney disease, with extremely high incidence, prevalence, DM-related KF and AKI rates. The magnitude of the prevailing problem calls for the creation of a regional society under the auspices of ASEAN with a shared perspective of universal, equitable and charitable access to quality renal care; consistent with the founding premises and healthcare initiatives of ASEAN.

Epidemiological characteristics and pathological changes of primary glomerular diseases

Objective

By analyzing the pathological characteristics and clinical data of renal biopsy in our hospital in the past 20 years, to further understand the epidemic characteristics and pathological changes of primary glomerular disease, and to provide regional data for the big data of kidney disease in my country.

Methods

A retrospective analysis of 9448 patients with primary glomerular disease who were hospitalized in our hospital from January 1, 2000 to December 31, 2019, aged 18 years or older, and undergoing renal biopsy. Divided every 5 years into a group, a total of 4 groups (first group 2000.1.1–2004.12.31, second groups 2005.1.1–2009.12.31; third groups 2010.1.1–2014.12.31, fourth groups 2015.1.1–2019.12.31).

Results

① There were more males than females, and male: female vs 1.53:1. The proportion of men in the past five years has increased compared with the previous 15 years. ② Mostly middle-aged, with a median age of 41.39 years old. The age is increasing over time. There are differences between the four groups, P <0.001; ③ The most common clinical manifestations are nephrotic syndrome, followed by chronic glomerulonephritis. Occult glomerulonephritis, the proportion of patients with nephrotic syndrome increases over time, first to fourth group (40.08%< 42.64% < 47.08%< 53.69%); ④ The most common pathology type from 2000 to 2009 was mesangial proliferative glomerulonephritis. IgA nephropathy was the most common type from 2010 to 2014, but the proportion of membranous nephropathy increased year by year, and it became the most common pathological type from 2015 to 2019; ⑤ The clinical and pathological manifestations of different genders are different, but there is no statistical difference.

Conclusion

In the past 20 years, the primary glomerular disease is mainly middle-aged. There are more men than women. The most common type of clinical manifestation is nephrotic syndrome. The pathological type is mesangial proliferative glomerulonephritis. Over time, the average age is increasing, and the proportion of patients with renal syndrome is increasing. IgA nephropathy is the most common pathological type from 2010 to 2014, and membranous nephropathy has become the main pathological type in the past 5 years.

Proximity to petrochemical industrial parks and risk of chronic glomerulonephritis

This study determined whether individuals residing near petrochemical industrial parks (PIPs) have a higher risk of chronic glomerulonephritis (CGN). We performed population-based 1:4 case-control study by using Taiwan's National Health Insurance Research Database from 2000 to 2016. The subjects were aged 20-65 years, residing in western Taiwan, and did not have a history of any renal or urinary system disease in 2000. The case cohort included those who had at least three outpatient visits or one hospitalization between 2001 and 2016 with codes for CGN as per International Classification of Diseases (ICD)-Ninth and Tenth Revisions. Controls were randomly sampled age-, sex-, and urbanization-matched individuals without renal and urinary system diseases. Petrochemical exposure was evaluated by the distance to the nearest PIP of the residential township, and petrochemical exposure probability was examined considering the monthly prevailing wind direction. Conditional logistic regression was used to determine the association between petrochemical exposure and CGN risk. A total of 320,935 subjects were included in the final analysis (64,187 cases and 256,748 controls). After adjustment for potential confounders, living in townships within a 3-km radius of PIPs was associated with a higher risk of CGN (adjusted odds ratio [aOR] = 1.32, 95% confidence interval [CI] = 1.28-1.37). Compared with townships more than 20 km away from PIPs, those within 10 km of PIPs were associated with significantly increased risks of CGN in a dose-dependent manner. When prevailing wind was considered, townships with high exposure probability were associated with a significantly increased risk of CGN. We found that those residing near PIPs or with high petrochemical exposure probability had a higher risk of CGN. These findings highlight the need for monitoring environmental nephrotoxic substances and the renal health of residents living near PIPs.

Morphological Spectrum of Glomerulonephritis in Medical Renal Biopsies: A Single-Center Study

Background

Glomerulonephritis is among the most common and serious non-communicable diseases in the world, and some of them are major causes of chronic kidney disease, which eventually leads to kidney failure. In developing countries, it is the most common cause of end-stage renal disease (ESRD). Chronic kidney disease affects 10-16% of the adult population in Asia, including 21.2% in Pakistan. This study aims to determine the frequency and spectrum of glomerulonephritis at our center.

Methodology

This is a cross-sectional analysis of 81 renal core biopsies obtained between August 2020 and August 2021. The histopathological reports, demographic data, and relevant laboratory investigations, such as blood urea and creatinine levels, were collected. All cases were blindly reviewed by two pathologists with a special interest in medical renal pathology. Data were analyzed using SPSS version 22 (IBM Corp., Armonk, NY, USA).

Results

The majority of the patients (46.9%) were between the ages of 21 and 40 years. There was a slight male predominance, with 44 (54.3%) of the 81 participants being male. Hematuria was reported in 20 (24.7%) patients, with mean serum urea and creatinine levels of 75 mg/dL and 2.6 mg/dL, respectively. Nephrotic syndrome was the most common indication for a renal biopsy, accounting for 54 (67.7%) of the 81 cases. Chronic glomerulonephritis is classified into two categories, namely, primary and secondary glomerulonephritis. Focal segmental glomerulosclerosis (FSGS), the leading cause of primary glomerulonephritis, was found in 25 (30.9%) 81 patients. Furthermore, lupus nephritis (9.9%) and advanced glomerulonephritis (9.9%) were found in equal proportions among secondary glomerulonephritis.

Conclusions

According to our study, nephrotic syndrome was the most common indication for medical renal biopsy, with FSGS being the most common primary glomerulonephritis. Lupus nephritis and advanced glomerulonephritis were the most common secondary glomerulonephritis diagnoses.

Trends of primary glomerular disease in Turkey: TSN-GOLD registry report

BACKGROUND

Although several renal biopsy registry reports have been published worldwide, there are no data on primary glomerular disease trends in Turkey.

METHODS

Three thousand eight-hundred fifty-eight native kidney biopsy records were assessed in the Turkish Society of Nephrology Primary Glomerulopathy Working Group (TSN-GOLD) Registry. Secondary disease and transplant biopsies were not recorded in the registry. These records were divided into four periods, before 2009, 2009 to 2013, 2013-2017, and 2017-current.

RESULTS

A total of 3858 patients (43.6% female, 6.8% elderly) were examined. Nephrotic syndrome was the most common biopsy indication in all periods (58.6%, 53%, 44.1%, 51.6%, respectively). In the whole cohort, IgA nephropathy (IgAN) (25.7%) was the most common PGN with male predominance (62.7%), and IgAN frequency steadily increased through the periods (× 2 = 198, p < 0.001). MGN was the most common nephropathy in the elderly (> 65 years), and there was no trend in this age group. An increasing trend was seen in the frequency of overweight patients (× 2 = 37, p < 0.0001). Although the biopsy rate performed with interventional radiology gradually increased, the mean glomeruli count in the samples did not change over the periods.

CONCLUSIONS

In Turkey, IgAN is the most common primary glomerulonephritis, and the frequency of this is increasing.

Epidemiology of native kidney disease in Flanders: results from the FCGG kidney biopsy registry

Background

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry is the first population-based native kidney biopsy registry in Flanders, Belgium. In this first analysis, we report on patient demographics, frequency distribution and incidence rate of biopsied kidney disease in adults in Flanders.

Methods

From January 2017 to December 2019, a total of 2054 adult first native kidney biopsies were included. A ‘double diagnostic coding’ strategy was used, in which every biopsy sample received a histopathological and final clinical diagnosis. Frequency distribution and incidence rate of both diagnoses were reported and compared with other European registries.

Results

The median age at biopsy was 61.1 years (interquartile range, 46.1–71.7); male patients were more prevalent (62.1%) and biopsy incidence rate was 129.3 per million persons per year. Immunoglobulin A nephropathy was the most frequently diagnosed kidney disease (355 biopsies, 17.3% of total) with a similar frequency as in previously published European registries. The frequency of tubulointerstitial nephritis (220 biopsies, 10.7%) and diabetic kidney disease (154 biopsies, 7.5%) was remarkably higher, which may be attributed to changes in disease incidence as well as biopsy practices. Discordances between histopathological and final clinical diagnoses were noted and indicate areas for improvement in diagnostic coding systems.

Conclusions

The FCGG registry, with its ‘double diagnostic coding’ strategy, provides useful population-based epidemiological data on a large Western European population and allows subgroup selection for future research.

A Comprehensive Review Study on Glomerulonephritis Associated With Post-streptococcal Infection

Post-streptococcal glomerulonephritis (PSGN) is an immune-complex mediated inflammation that used to be considered one of the commonest causes of acute nephritis amongst children. PSGN is characterized by the proliferation of cellular elements called nephritogenic M type as a result of an immunologic mechanism following an infection of the skin (impetigo) or throat (pharyngitis) caused by nephritogenic strains of group A beta-hemolytic streptococci, a gram-positive bacteria that enters the body across pores in the skin or mucus epithelia and is responsible for more than 500,000 deaths annually due to multiple subsequence diseases such as rheumatic heart disease, rheumatic fever, PSGN, and other invasive infections. After the infection, the formation of an immune complex of antigen-antibody and complement system will take place and will deposit in the glomeruli where the injury occurs and leads to inflammation. The manifestations of PSGN can be explained by nephritic syndrome manifestation. PSGN is diagnosed by laboratory tests like microscopy and urinalysis. The imaging studies in PSGN could be used to assess the possible complications of PSGN such as pulmonary congestion and chronic kidney disease. The management of PSGN is symptomatic. If PSGN is not treated, the patient may develop chronic kidney disease. The main way to prevent PSGN is to treat group A streptococcal (GAS) infections by giving good coverage of antibiotic therapy to a patient who has primary GAS infections to prevent the development of the complication.

Clinical and histological features in pediatric and adolescent/young adult patients with renal disease: a cross-sectional analysis of the Japan Renal Biopsy Registry (J-RBR)

BACKGROUND

Only a few studies have investigated epidemiological and clinicopathological information regarding pediatric and adolescent and young adult (AYA) patients with renal disease. The purpose of this study was to clarify the differences and relationship of clinicopathological findings between pediatric and AYA patients using the Japan Renal Biopsy Registry (J-RBR).

METHODS

This cross-sectional study analyzed data from patients registered in the J-RBR between 2007 and 2017. Clinicopathological findings at diagnosis were analyzed for 3,463 pediatric (age < 15 years) and 6,532 AYA (age 15-30 years) patients.

RESULTS

Although chronic nephritic syndrome was the most common clinical diagnosis at age > 5 years, nephrotic syndrome was the most frequent diagnosis at age < 4 years. The most common pathological diagnosis as classified by pathogenesis in pediatric patients was primary glomerular disease (except IgA nephropathy), whereas IgA nephropathy was increased in AYA patients. Mesangial proliferative glomerulonephritis was the most common pathological diagnosis as classified by histopathology in both pediatric and AYA patients. Minor glomerular abnormalities were the most frequent histopathologic diagnoses of nephrotic syndrome in childhood, but their frequency decreased with age.

CONCLUSION

To the best of our knowledge, this is the first report of clinicopathological features of pediatric and AYA patients in a large nationwide registry of renal biopsy. There were differences of clinical, pathological and histopathologic findings between pediatric and AYA patients.

IgG deposits in the mesangium and capillary loops predict poor renal outcome in patients with IgA nephropathy: a single-center retrospective study

Background

Glomerular IgG deposition in patients with IgA nephropathy (IgAN) has been shown to be associated with poor renal survival; however, most published studies to date are too small-scale and inconsistent to provide guidance for clinical practice.

Methods

Based on renal biopsy findings, 742 patients were divided into the following groups: (i) IgA deposition alone (IgA) vs IgA + IgG deposition (IgA + IgG) and (ii) IgG co-deposition confined to the mesangium vs mesangium + capillary loops (CLs). The clinicopathological variables at biopsy and renal outcome were assessed.

Results

Of the 742 patients, 182 had IgG co-deposition and 51 had IgG deposits in the mesangium + CLs. Patients with IgG co-deposition were associated with severe clinical and pathological lesions, especially those with a location of IgG deposits in the mesangium +CLs. Kaplan–Meier analysis revealed that a lower renal cumulative survival rate was present in both patients with IgG co-deposition and those with a location of IgG deposits in the mesangium + CLs (all p < 0.05). Moreover, patients with a higher intensity of glomerular IgG deposits or C3 deposits or C1q deposits were also associated with a lower survival rate. A multivariate Cox regression model identified the location of IgG deposits in the mesangium + CLs as an independent risk factor for poor prognosis (HR, 2.11; 95% CI: 1.06–4.18; p = 0.005).

Conclusions

Glomerular IgG co-deposition and the location of glomerular IgG deposits in the mesangium + CLs were both associated with adverse renal outcomes, but only the location of glomerular IgG deposits in the CLs was an independent risk factor for poor prognosis in IgAN.

Changes in metabolic parameters and adverse kidney and cardiovascular events during glomerulonephritis and renal vasculitis treatment in patients with and without diabetes mellitus

BACKGROUND

Cardiovascular disease causes significant morbidity and mortality in patients with glomerulonephritis, which is increasingly diagnosed in older individuals who may have diabetes mellitus (DM). We evaluated the impact of DM on metabolic profile, renal and cardiovascular outcomes during treatment and follow-up of individuals with glomerulonephritis.

METHODS

We performed a retrospective cohort study of 601 consecutive adults with biopsy-proven glomerulonephritis for factors associated with kidney failure, hospitalization for cardiovascular events, and death. Biopsies with isolated diabetic nephropathy were excluded.

RESULTS

The median patient age was 49.8 years (36.7-60.9 years) with estimated glomerular filtration rate of 56.7 mL/min/1.73 m2 (27.7-93.2 mL/min/1.73 m2). DM was present in 25.4%. The most frequent diagnoses were minimal change disease (MCD) or focal segmental glomerulosclerosis (FSGS) (29.5%), lupus nephritis (21.3%), immunoglobulin A (IgA) nephropathy (19.1%), and membranous nephropathy (12.1%). The median follow-up was 38.8 months (interquartile range [IQR], 26.8-55.8 months). Among 511 individuals with lupus nephritis, anti-neutrophil cytoplasmic antibody-associated vasculitis, MCD/FSGS, membranous nephropathy, and IgA nephropathy, 52 (10.2%) developed kidney failure at a median 16.4 months (IQR, 2.3-32.2 months), while 29 (5.7%) had cardiovascular-related hospitalizations at 12.9 months (IQR, 4.8-31.8 months) and 31 (6.1%) died at 13.5 months (IQR, 2.5-42.9 months) after diagnosis. Cox regression analysis found that baseline DM was independently associated with kidney failure (adjusted hazard ratio [HR], 2.07; 95% confidence interval [CI], 1.06-4.05, p = 0.03) and cardiovascular-related hospitalization (adjusted HR, 2.69; 95% CI, 1.21-5.98, p = 0.02) but not with mortality.

CONCLUSION

DM was strongly associated with kidney failure and hospitalization for cardiovascular events in patients with biopsy-proven glomerulonephritis.

Diagnostic performance of glomerular PLA2R and THSD7A antibodies in biopsy confirmed primary membranous nephropathy in South Africans

Background:

Serum and tissue-based tests using phospholipase A2 receptor 1 (PLA2R) and thrombospondin type-1 domain containing 7A (THSD7A) are established immune biomarkers for the diagnosis of primary membranous nephropathy (PMN). This study assessed the diagnostic performance of these biomarkers in the diagnosis of PMN in South Africans.

Methods

This was a cross-sectional analysis from a single centre in Cape Town, South Africa. Relevant biodata was collected from all patients. Histology, including slides for PLA2R and THSD7A were processed and assessed by typical microscopic and immunohistochemical features. Biopsy tissues of patients with membranous lupus nephritis (LN-V) and diabetic nephropathy (DN) were used as controls. The diagnostic accuracy for diagnosis of PMN using positive PLA2R and THSD7A were evaluated.

Results

Of the 88 patients included, 41 had PMN with a mean age of 44.5 ± 17.5 years and 61.0% were female. Histologically, PLA2R and THSD7A were only positive in the PMN group (51.2% and 4.9%, respectively) but negative in both control groups. The sensitivity of PLA2R and THSD7A for identifying PMN was 51.2% and 4.9%, respectively. The sensitivity of both tests together was 53.7% while the specificity and positive predictive values (PPV) for any of the tests (alone or in combination) was 100%. There was no difference in the sensitivity and specificity when using PLA2R alone compared to combining the two tests (p=0.32).

Conclusion

Glomerular staining of PLA2R and THSD7A could have potential diagnostic values in South Africans. This has implications on how immunotherapies can be initiated and used in these settings.

Increased incidence and improved prognosis of glomerulonephritis: a national 30-year study

Background

While there are many cross-sectional studies of glomerulonephritis (GN) incidence, changes in incidence over time, particularly in the 21st century have received less attention. Similarly, little is known about temporal changes in GN prognosis. The presence in Denmark of comprehensive registries for renal biopsy results, end-stage renal disease (ESRD), comorbidity and mortality permit these questions to be addressed.

Methods

Data for all renal biopsies in Denmark between 1985 and 2014 were extracted from the Danish Renal Biopsy Registry and Patobank registries. The date of first dialysis or transplantation was extracted from the Danish Nephrology Registry for those patients developing ESRD. Dates of death and presence of chronic comorbid conditions at date of biopsy were extracted from the National Patient Registry. The incidence of GN, adjusted to the 2013 European standard population, was calculated. ESRD incidence and mortality were calculated, both in absolute terms and after correction for age, comorbidity and presence of renal tubulointerstitial fibrosis.

Results

The incidence rose from 33.3 patients per million (ppm)/year in 1985–94 to 46.5 ppm in 2005–14. The increase could in part be related to changes in renal biopsy policy. Large increases in Anti-neutropil cytoplasmic antibody (ANCA) vasculitis (ANCAV) (3.1–7.7 ppm/year) and focal segmental glomerulosclerosis (FSGS) (1.5–5.7 ppm/year) incidence were noted. The biopsy-proven prevalence of GN in 2014 was 748 ppm of which 155 ppm were being treated with dialysis or transplantation. Adjusted ESRD incidence fell by 25% during the study period, mortality by 62% and combined ESRD/mortality by 46%. The fall in ESRD incidence was limited to minimal change GN, FSGS, membranous GN and lupus nephritis, while reductions in mortality, and the combination of ESRD and/or death, were seen for nearly all GN diagnoses.

Conclusions

This study suggests that the incidence of GN has generally increased between 1985 and 2014, but some of the increase may be related to changes in renal biopsy policy. Major increases in FSGS and ANCAV incidence have occurred. The prognosis of GN, both as regards ESRD and mortality, has improved.

Podocytopathies

Podocytopathies are kidney diseases in which direct or indirect podocyte injury drives proteinuria or nephrotic syndrome. In children and young adults, genetic variants in >50 podocyte-expressed genes, syndromal non-podocyte-specific genes and phenocopies with other underlying genetic abnormalities cause podocytopathies associated with steroid-resistant nephrotic syndrome or severe proteinuria. A variety of genetic variants likely contribute to disease development. Among genes with non-Mendelian inheritance, variants in APOL1 have the largest effect size. In addition to genetic variants, environmental triggers such as immune-related, infection-related, toxic and haemodynamic factors and obesity are also important causes of podocyte injury and frequently combine to cause various degrees of proteinuria in children and adults. Typical manifestations on kidney biopsy are minimal change lesions and focal segmental glomerulosclerosis lesions. Standard treatment for primary podocytopathies manifesting with focal segmental glomerulosclerosis lesions includes glucocorticoids and other immunosuppressive drugs; individuals not responding with a resolution of proteinuria have a poor renal prognosis. Renin-angiotensin system antagonists help to control proteinuria and slow the progression of fibrosis. Symptomatic management may include the use of diuretics, statins, infection prophylaxis and anticoagulation. This Primer discusses a shift in paradigm from patient stratification based on kidney biopsy findings towards personalized management based on clinical, morphological and genetic data as well as pathophysiological understanding.