Long-Term Exposure to Air Pollution and Increased Risk of Membranous Nephropathy in China

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

Objective

The pattern of glomerulonephritis (GN) in Singapore is compared with that of 19 other countries to review changing trends in the evolution of GN in Asian, Eastern, and Western countries.

Method

Three thousand two hundred and eighty-nine renal biopsies in Singapore were reviewed and compared with that of 19 other countries.

Results

IgA nephritis is on the decline in many countries, including Singapore, though it still remains the commonest GN in Singapore. Membranous GN that if used to be more frequently present in Western countries has also declined though it continues a rising trend in countries such as Singapore and China. Worldwide, the frequency of focal sclerosing glomerulosclerosis (FSGS) continues to increase in many countries, but in some countries, the frequency is still low with mesangiocapillary GN remaining indigenous.

Conclusion

Urbanization and socioeconomic changes and less exposure to parasitic and other infestations have transformed Singapore's pattern, which is tending toward that of more developed countries. Antigenic exposure due to lifestyle changes, environmental, and industrial pollution are significant contributory factors that affect the evolutionary trend of GN in many countries. The rising trend in the frequency of FSGS may reflect aging and obesity.

Clinicopathologic correlations of renal biopsy findings from northeast China: A 10-year retrospective study

Renal biopsy is the cornerstone of diagnostic approaches in nephrology, as they provide invaluable diagnostic information. In this study, we analyzed and reported renal biopsy results from northeast China from the past 10 years to describe the epidemiological trend.We analyzed clinical features, indications, and histological diagnoses of renal biopsies collected between January 1, 2007, and December 31, 2016.There were 2725 identified cases (with a mean age of 41.24 ± 15.18 years, 55% male) during the study period. The main clinical indication was nephrotic syndrome (59.9%). Membranous nephropathy (29.1%) was the most common pathological finding in the entire study population, followed by IgA nephropathy (23.4%), minimal change disease (12.7%), and mesangio-proliferative glomerulonephritis (7.4%).We divided the study period into 2 subperiods: 2007 to 2011 (period 1) and 2012 to 2016 (period 2). Membranous nephropathy and minimal change disease were more frequent in period 2 than in period 1. Conversely, IgAN and non-IgA mesangio-proliferative glomerulonephritis were less frequent in period 2 than in period 1. Cases of Henöch-Schönlein purpura nephritis and lupus nephritis were observed less over time, while cases of nephroangiosclerosis increased significantly over time. Finally, there was a significant increase in the number of tubulointerstitial diseases observed over time, while there was a significant decrease in glomerulosclerosis and unclassified findings over time.Membranous nephropathy was the most common pathological finding from renal biopsy and the prevalence has increased significantly in recent years in northeast China.

Prognostic value of phospholipase A2 receptor in primary membranous nephropathy: a systematic review and meta-analysis

PURPOSE

We aimed to evaluate the prognostic value of serum anti-PLA2R and glomerular PLA2R deposit (gPLA2R) in predicting remission of proteinuria in Primary Membranous Nephropathy (PMN) patients.

METHODS

PUBMED, EMBASE, WEB OF SCIENCE, COCHRANE LIBRARY and CNKI were searched from 2008 January to December 2018. Heterogeneity was assessed by Cochran Q test and I². Source of heterogeneity was explored by subgroup analysis and sensitivity analysis.

RESULTS

Totally 2345 patients from 29 cohort studies were eligible for inclusion. The results suggested that PMN patients with negative anti-PLA2R at the time of biopsy had a 1.31 times (95% CI 1.12-1.46, p < 0.05) higher possibility in achieving remission than those with positive anti-PLA2R. The clearance of anti-PLA2R at the end of immunosuppressive therapy showed an even greater chance of achieving remission (RR = 2.86, 95% CI 1.75-4.69, p < 0.05). The relative ratios for complete remission and spontaneous remission with negative anti-PLA2R were 1.65 (95% CI 1.46-1.87, p < 0.05) and 1.93, respectively (95% CI 1.53-2.45, p < 0.05), and heterogeneity percentages were I² = 18% and 46%, respectively. The possibility for remission was significantly greater among PMN patients with negative gPLA2R (RR = 1.30, 95% CI 1.13-1.50, p < 0.05). Subgroup analyses revealed that retrospective design of study might be the potential source of heterogeneity.

CONCLUSIONS

Negative anti-PLA2R or gPLA2R might predict higher possibility of remission, and the presence of anti-PLA2R or gPLA2R might serve as a useful biomarker for clinical outcome and predicting response to immunosuppressive therapy in PMN.

Immunology of membranous nephropathy

Accounting for about 20 to 50% of cases of primary nephrotic syndrome, membranous nephropathy (MN) is the leading cause of nephrotic syndrome in adults. A rat model created nearly 60 years ago to research the primary MN disorder, Heymann nephritis, has provided us with a plethora of important information. Recently, our knowledge about MN has dramatically progressed. Heymann nephritis and human MN are now known to share a high degree of similarity in pathogenesis. This review summarizes our current understanding of MN pathogenesis while focusing particularly on the immunological aspects.

Clinical and Pathological Analysis of 4910 Patients Who Received Renal Biopsies at a Single Center in Northeast China

Purpose

To identify the epidemiology and pathological types of kidney diseases and their changes during the past decade, in a population from Northeast China.

Methods

We retrospectively analysed clinical and renal pathological data from 4910 patients who received renal biopsies in the Second Hospital of Jilin University from 2008 to 2017.

Results

Males received more renal biopsies than females (p < 0.001). The average age (p < 0.001) and percentage of elderly patients (p < 0.001) increased over time. The pathological types were primary glomerulonephritis (PGN, 73.2%), secondary glomerulonephritis (SGN, 23.7%), tubular-interstitial nephropathy (TIN, 2.8%), and hereditary nephropathy (HN, 0.3%). The most common forms of PGN were membranous nephropathy (MN, 37.2%) and IgA nephropathy (IgAN, 29.9%). Over time, the prevalence of IgAN decreased, but the prevalence of MN increased. MN was more common in middle-aged and elderly patients, but IgAN was most common in young adults. Analysis of SGN data indicated that lupus nephritis (LN, 34.0%), Henoch-Schönlein purpura glomerulonephritis (HSPN, 17.9%), and diabetic nephropathy (DN, 11.7%) were the most common forms. Over time, the prevalence of DN (p = 0.003), hypertension-associated renal damage (p = 0.005), and systemic vasculitis-associated nephritis (SVARD, p < 0.001) increased, but the prevalence of HSPN (p < 0.001) and hepatitis B virus-associated glomerulonephritis (HBV-GN, p = 0.001) decreased. Nephrotic syndrome was the main clinical manifestation of PGN.

Conclusion

From 2008 to 2017, renal biopsies were increasingly performed in the elderly. There were notable changes in the epidemiology and pathological types of kidney disease among renal biopsy patients at our centre.

Acute kidney injury in cancer patients: A nationwide survey in China

Cancer patients have a high risk for acute kidney injury (AKI); however, the incidence, severity, and risk factors of malignancy-related AKI (MR-AKI) are unclear. This study aimed to assess MR-AKI risk factors and provide reliable data for AKI prevention, diagnosis, and management in China. This cross-sectional study analysed data from 44 academic and local hospitals in China. AKI patients were identified based on 2 screening criteria: the 2012 Kidney Disease: Improving Global Outcomes-AKI definition and the expanded screening criteria for patients with no repeated serum creatinine (SCr) test within 7 days and those who recovered from AKI. Patients whose SCr level increased or decreased by 50% during hospitalization, compared with that at admission, were considered to have AKI according to the expanded criteria. A total of 7,604 AKI patients were enrolled (1,418 with MR-AKI). Patient characteristics were compared between the MR-AKI and non-MR-AKI groups. Multivariate logistic models were used to statistically assess risk factors. The proportions of MR-AKI patients in academic and local hospitals were 20.2% and 14.1%, respectively. The incidence of MR-AKI was higher in mid-China (the affluent region), elderly patients, and groups with higher per capita gross domestic product. Among MR-AKI cases, gastrointestinal cancer (50.1%) was the most common malignancy, followed by cancers of the reproductive (15.3%), haematological (13.1%), respiratory (11.8%), and other systems (8.3%), and cancers of unknown classification (1.4%). Of 268 hospital deaths, respiratory, haematological, gastrointestinal, reproductive, other system, and unknown classification cancers accounted for 29.3%, 18.8%, 18.6%, 12.9%, 16.9%, and 20.0%, respectively. Increased age, advanced AKI stage at peak, level of per capita gross domestic product, geographic region, and renal replacement therapy indication were risk factors for hospital mortality in patients with gastrointestinal MR-AKI, whereas cardiovascular disease history, AKI stage at peak, and geographic region were risk factors for mortality in patients with reproductive MR-AKI. The incidence and mortality of MR-AKI vary by hospital, economic level, age, geographic region, and malignancy type. High MR-AKI incidence was associated with gastrointestinal cancers and higher level of medical care provided by academic hospitals in affluent regions such as Beijing, Shanghai, and other provincial-level cities. Elderly patients with advanced gastrointestinal cancer in mid-China showed the highest incidence of MR-AKI and in-hospital mortality, and thus require special attention.

New risk score for predicting progression of membranous nephropathy

Background

Patients with Idiopathic membranous nephropathy (IMN) have various outcomes. The aim of this study is to construct a tool for clinicians to precisely predict outcome of IMN.

Methods

IMN patients diagnosed by renal biopsy from Shanghai Ruijin Hospital from 2009.01 to 2013.12 were enrolled in this study. Primary outcome was defined as a combination of renal function progression [defined as a reduction of estimated glomerular filtration rate (eGFR) equal to or over 30% comparing to baseline], ESRD or death. Risk models were established by Cox proportional hazard regression analysis and validated by bootstrap resampling analysis. ROC curve was applied to test the performance of risk score.

Results

Totally 439 patients were recruited in this study. The median follow-up time was 38.73 ± 19.35 months. The enrolled patients were 56 (15–83) years old with a male predominance (sex ratio: male vs female, 1:0.91). The median baseline serum albumin, eGFR-EPI and proteinuria were 23(8–43) g/l, 100.31(12.81–155.98) ml/min/1.73 m² and 3.98(1.50–22.98) g/24 h, respectively. In total, there were 36 primary outcomes occurred. By Cox regression analysis, the best risk model included age [HR: 1.04(1.003–1.08), 95% CI from bootstrapping: 1.01–1.08), eGFR [HR: 0.97 (0.96–0.99), 95% CI from bootstrapping: 0.96–0.99) and proteinuria [HR: 1.09 (1.01–1.18), 95% CI from bootstrapping: 1.02–1.16). One unit increasing of the risk score based on the best model was associated with 2.57 (1.97–3.36) fold increased risk of combined outcome. The discrimination of this risk score was excellent in predicting combined outcome [C statistics: 0.83, 95% CI 0.76–0.90].

Conclusions

Our study indicated that older IMN patients with lower eGFR and heavier proteinuria at the time of renal biopsy were at a higher risk for adverse outcomes. A risk score based on these three variables provides clinicians with an effective tool for risk stratification.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1792-8) contains supplementary material, which is available to authorized users.

Association of Exposure to Fine-Particulate Air Pollution and Acidic Gases with Incidence of Nephrotic Syndrome

Background: Air pollution has been associated with autoimmune diseases. Nephrotic syndrome is a clinical manifestation of immune-mediated glomerulopathy. However, the association between nephrotic syndrome and air pollution constituents remains unknown. We conducted this nationwide retrospective study to investigate the association between PM_2.5 and nephrotic syndrome. Methods: We used the Longitudinal Health Insurance Database (LHID) and the Taiwan Air Quality-Monitoring Database (TAQMD). We combined and stratified the LHID and the TAQMD data by residential areas of insurants linked to nearby air quality-monitoring stations. Air pollutant concentrations were grouped into four levels based on quartile. Univariable and multivariable Cox proportional hazard regression models were applied. Findings: Relative to Q1-level SO₂, subjects exposed to the Q4 level were associated with a 2.00-fold higher risk of nephrotic syndrome (adjusted HR = 2.00, 95% CI = 1.66⁻2.41). In NOx, relative to Q1 NOx concentrations, the adjusted HRs of nephrotic syndrome risk were 1.53 (95% CI = 1.23⁻1.91), 1.30 (95% CI = 1.03⁻1.65), and 2.08 (95% CI = 1.69⁻2.56) for Q2, Q3, and Q4 levels, respectively. The results revealed an increasing trend for nephrotic syndrome risk correlating with increasing levels of NO, NO₂, and PM_2.5 concentrations. Interpretation: High concentrations of PM_2.5, NO, NO₂, and SO₂ are associated with increased risk of nephrotic syndrome.

Changes in the diagnosis of glomerular diseases in east China: a 15-year renal biopsy study

Background: There have been some gradual changes in the distribution of renal biopsy pathological diagnoses during recent years. This study aimed to show changes in renal disease prevalence in China by investigating 10 patients diagnosed at our Kidney Disease Centre during the last 15 years.

Methods and results: All patients aged 15-year-old or older who underwent renal biopsy at the First Affiliated Hospital, Zhejiang University, from 2001 to 2015 were enrolled. There were 5 common types of primary glomerulonephritis: IgA nephropathy (IgA N), membranous nephropathy (MN), mesangial progressive glomerulonephritis (MsPGN), minimal change disease (MCD), and focal segmental glomerulosclerosis (FSGS), which represented 50%, 16.8%, 15.9%, 8.1% and 2.5% of total cases, respectively. IgA nephropathy was the most common type of primary glomerulonephritis (PGN).

Conclusions: Our results mostly showed a new trend that the diagnosis of IgA nephropathy was not increasing and the prevalence of membranous nephropathy had increased, becoming the second most common type of primary glomerulonephritis.

Key POINTS

Distinguished with other domestic studies, IgA nephropathy did not show a trend of continuous growth although it still had about the half proportion of PGN, whereas membranous nephropathy kept rising and became the second common PGN.

Concerning SGN, LN peaked in the younger-age and middle-age groups with a significant female prevalence, DN, BANS and SV had a male predominance peaking in the middle-age and old-age groups.

Characterization of autoantibodies in primary membranous nephropathy and their clinical significance

Introduction: Membranous nephropathy (MN) is the most common cause of a nephrotic syndrome in Caucasian adults. The identification of target antigens in MN in the last decade has had a major impact on the clinical approach to these patients. Areas covered: Since the discoveries in animal models in the 1980s that circulating autoantibodies induce disease upon in situ binding to glomerular podocytes, many attempts have been undertaken to define the human antigens responsible for disease induction. Only in 2009 was Phospholipase A₂ Receptor 1 described as the major antigen responsible for MN onset in about 70% of patients. Subsequently, in 2014, Thrombospondin Type-1 Domain-Containing 7A was identified as a second antigen, accounting for 2-3% of patients with MN. The knowledge of the role of these antibodies in MN has improved the diagnosis and management of patients and helped to better define the need for immunosuppressive treatment. Expert commentary: These discoveries over the last 10 years in the discipline of nephrology have clearly shown the improvements a better understanding of disease pathogenesis can bring for patient care.

Air pollution and kidney disease: review of current evidence

Along with amazing technological advances, the industrial revolution of the mid-19th century introduced new sources of pollution. By the mid-20th century, the effects of these changes were beginning to be felt around the world. Among these changes, health problems due to environmental air pollution are increasingly recognized. At the beginning, respiratory and cardiovascular diseases were emphasized. However, accumulated data indicate that every organ system in the body may be involved, and the kidney is no exception. Although research on air pollution and kidney damage is recent, there is now scientific evidence that air pollution harms the kidney. In this holistic review, we have summarized the epidemiology, disease states and mechanisms of air pollution and kidney damage.

Satellite-based short- and long-term exposure to PM2.5 and adult mortality in urban Beijing, China

Severe and persistent haze accompanied by high concentrations of fine particulate matter (PM_2.5) has become a great public health concern in urban China. However, research on the health effects of PM_2.5 in China has been hindered by the lack of high-quality exposure estimates. In this study, we assessed the excess mortality associated with both short- and long-term exposure to ambient PM_2.5 simultaneously using satellite-derived exposure data at a high spatiotemporal resolution. Adult registries of non-accidental, respiratory and cardiovascular deaths in urban Beijing in 2013 were collected. Exposure levels were estimated from daily satellite-based PM_2.5 concentrations at 1 km spatial resolution from 2004 to 2013. Mixed Poisson regression models were fitted to estimate the cause-specific mortality in association with PM_2.5 exposures. With the mutual adjustment of short- and long-term exposure of PM_2.5, the percent increases associated with every 10 μg/m³ increase in short-term PM_2.5 exposure were 0.09% (95% CI: -0.14%, 0.33%; lag 01), 1.02% (95% CI: 0.08%, 1.97%; lag 04) and 0.09% (95% CI: -0.23%, 0.42%; lag 01) for non-accidental, respiratory and cardiovascular mortality, respectively; those attributable to every 10 μg/m³ increase in long-term PM_2.5 exposure (9-year moving average) were 16.78% (95% CI: 10.58%, 23.33%), 44.14% (95% CI: 20.73%, 72.10%) and 3.72% (95% CI: -3.75%, 11.77%), respectively. Both associations of short- and long-term exposure with the cause-specific mortality decreased after they were mutually adjusted. Associations between short-term exposure to satellite-based PM_2.5 and cause-specific mortality were larger than those estimated using fixed measurements. Satellite-based PM_2.5 predictions help to improve the spatiotemporal resolution of exposure assessments and the mutual adjustment model provide better estimation of PM_2.5 associated health effects. Effects attributable to long-term exposure of PM_2.5 were larger than those of short-term exposure, which should be more concerned for public health.

Acute arterial cardiovascular events risk in patients with primary membranous nephropathy

BACKGROUND

Venous thromboembolism is a well established risk in patients with primary membranous nephropathy (MN) due to deficiency in natural anti-coagulants. Recent studies suggested a higher risk of arterial thrombotic events as well in this group.

AIM

To identify that risk in our cohort.

METHODS

We reviewed the data of all patients who had biopsy proven primary MN at our institute between 2003 and 2013. Clinical data were retrospectively reviewed until November 2016. The cardiovascular (CV) events, including acute coronary syndromes and strokes were determined and included only if occurred after the diagnosis of the nephropathy.

RESULTS

A total of 204 patients had biopsy proven MN. Follow up information was available for 166 patients. Thirty-one patients (18.6%) developed CV events during follow up. Thirty-eight per cent of total events occurred within 1 year of MN diagnosis. Forty-two per cent of those who developed CV events were not on anti-thrombotic medications and 60% were not on statin therapy. Male gender, age, diabetes and absence of statins therapy were associated with higher rates of CV events in this group.

CONCLUSION

There is an increased risk of arterial events in patients with primary MN. This risk is greatest in the first year of diagnosis. The risk should be highlighted in this group of patients and anti-platelets and statin therapy should be considered especially during the initial phase of the disease.

Identification of a two-SNP PLA2R1 Haplotype and HLA-DRB1 Alleles as Primary Risk Associations in Idiopathic Membranous Nephropathy

The associations of single nucleotide polymorphisms (SNPs) in PLA2R1 and HLA-DQA1, as well as HLA-DRB1*15:01-DQB1*06:02 haplotype with idiopathic membranous nephropathy (IMN) is well known. However, the primary associations of these loci still need to be determined. We used Japanese-specific SNP genotyping array and imputation using 2,048 sequenced Japanese samples to fine-map PLA2R1 region in 98 patients and 413 controls. The most significant SNPs were replicated in a separate sample set of 130 patients and 288 controls. A two-SNP haplotype of intronic and missense SNPs showed the strongest association. The intronic SNP is strongly associated with PLA2R1 expression in the Genotype-Tissue Expression (GTEx) database, and the missense SNP is predicted to alter peptide binding with HLA-DRB1*15:01 by the Immune Epitope Database (IEDB). In HLA region, we performed relative predispositional effect (RPE) tests and identified additional risk alleles in both HLA-DRB1 and HLA-DQB1. We collapsed the risk alleles in each of HLA-DRB1 and HLA-DQB1 into single risk alleles. Reciprocal conditioning of these collapsed risk alleles showed more residual significance for HLA-DRB1 collapsed risk than HLA-DQB1 collapsed risk. These results indicate that changes in the expression levels of structurally different PLA2R protein confer risk for IMN in the presence of risk HLA-DRB1 alleles.

Monoclonal gammopathy of undetermined significance in Chinese population: A prospective epidemiological study

The aim of this study was to identify the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in different groups of age and the clinical features in China. This multicenter prospective study enrolled 1797 health subjects. The overall prevalence of MGUS was 2.73%. The prevalence of different age groups was 1.19% (41‐50 y), 1.16% (51‐60 y), 2.19% (61‐70 y), 3.66% (71‐80 y), and 7.76% (≥81 y). The prevalence of MGUS in male (n = 843) was 2.97%, while the prevalence of MGUS in female (n = 952) was 2.52%, but this difference of the two groups was not statistically significant. As for subtype of MGUS, IgG subtype was 55.1% (27 cases), IgA subtype was 14.3%, and IgM subtype was 12.2%. The M protein of one case became negative after 3 months, and the others remained positive without obvious disease transformation (follow‐up duration: 3‐7 mo). Thus, the prevalence of MGUS in China was similar to that in Mexican Americans, but lower than that in the other Asian country, American Whites, American Blacks, and Africans, and had a trend of increase with age. Male had higher prevalence of MGUS in China. The most common subtype was IgG.

The Spectrum of Biopsy-Proven Glomerular Disease in China: A Systematic Review

Background:

Chronic kidney disease has become a leading public health concern in China, as it is associated with increased morbidity, mortality, and costs. However, the overall situation regarding common glomerular diseases in China remains unclear. Hence, the aim of this study was to assess the national profile of the common types of glomerulonephritis in China.

Methods:

We searched Medline, Embase, Cochrane Library, CNKI, SinoMed, VIP, and Wanfang databases for English and Chinese language articles from inception to September 2017. We also collected potentially relevant studies and reviews using a manual search. The following words in combinations are as keywords: “renal biopsy”, “kidney pathological diagnosis”, and “spectrum of pathological types”.

Results:

We identified 23 studies involving 176,355 patients from 15 provinces/cities in China. The detection rates of primary glomerulonephritis (PGN) and secondary glomerulonephritis (SGN) were 0.740 and 0.221, respectively. Over the past 30 years, the top five types of PGN were immunoglobulin A nephropathy (IgAN; 24.3%), mesangial proliferative glomerulonephritis (MsPGN; 10.5%), membranous nephropathy (MN; 12.6%), minimal change disease (MCD; 9.8%), and focal segmental glomerulosclerosis (FSGS; 4.6%), and the top four types of SGN were lupus nephritis (LN; 8.6%), Henoch-Schönlein purpura glomerulonephritis (4.1%), hepatitis B virus-associated glomerulonephritis (HBV-GN; 2.6%), and diabetic nephropathy (DN; 1.6%). The proportion of MN, MCD, HBV-GN, and DN tended to increase, while those of IgAN, MsPGN, FSGS, and LN tended to drop.

Conclusions:

Although the incidence of SGN is increasing gradually, PGN is still the leading form of kidney disease in patients undergoing renal biopsies in China. IgAN and LN are the most common types of PGN and SGN, respectively. Differences between regions are related to various factors such as nationality, environment, and diet. Furthermore, unified standards and norms for evaluating renal biopsies are urgently needed.

The clinical features and prognosis of the monoclonal gammopathy undetermined significance: A single center study

The aim of this study was to identify the clinical features and prognosis of monoclonal gammopathy of undetermined significance (MGUS) in China. This single center study enrolled 111 subjects visited in Peking University People's hospital including 62 males and 49 females. Among them, IgG subtype, IgA subtype and IgM subtype were 56.31%, 28.16%, 5.83% respectively. 10.7% patients had the abnormality of convectional cytogenetic testing, while the interphase fluorescence in situ hybridization (FISH) made the positive rate increased to 18.9%, and IgH rearrangement was most common. The positive rate of MAGE-C1/CT7 was 73.8% in MGUS, but the expression level was 0.33%, lower than that in MM. After a median follow-up of 15.9 months, 5 cases were determined disease progression (PD), and 1 patient had died of disease progression, two died of the complication. MGUS is becoming increasingly important in China. Male had higher prevalence of MGUS, the most common subtype was IgG, and the IgA subtype was much higher which may be related to the air pollution. MGUS patients had a high positive rate of MAGE-C1/CT7 gene, but the expression level was low. Some patients with MGUS could progress to MM, systemic amyloidosis and other malignant diseases.

Clinicopathological features of atypical membranous nephropathy with unknown etiology in adult Chinese patients

Membranous nephropathy is typically classified as idiopathic and secondary, but nowadays the number of atypical membranous nephropathy (aMN) is increasing, many of which cannot determine its etiology in China. In this study, we compared the clinical and pathological characteristics of idiopathic membranous nephropathy (iMN) with aMN with unknown etiology from a single center in China.We retrospectively reviewed the clinical data of 577 patients with iMN and aMN at Peking University People's Hospital from January 2006 to December 2015 over a 10-year period, and analyzed their clinical and pathological characteristics. The level of serum phospholipase A2 receptors (PLA2R) antibody was detected in 106 iMN and 162 aMN patients.There were 278 iMN patients and 299 aMN patients who were included into this study in 3210 cases of renal biopsy during a 10-year period in our hospital. The average age of patients with iMN was significantly older than those with aMN (54.77 ± 13.01 vs 47.13 ± 16.16, P < .001). Around 75 patients (27%) were smokers in iMN patients, and 111 patients (37.1%) in aMN patients (P = .009). The mainly clinical manifestation of these 2 groups was nephrotic syndrome (61.5% in iMN group vs 58.4% in aMN group), but there were more patients accompanied with nephritis syndrome in aMN group than iMN group (17.1% vs 6.1%, P < .001). The immunofluorescence of renal biopsy showed "full house" in aMN group; and IgG subclass of the glomeruli demonstrated IgG4 (90.4%) was commonest in iMN group, but IgG1 (94.6%) in aMN group. 51 (48.1%) patients with iMN were detected positive PLA2R antibody in their serum, and 93 (57.4%) in aMN patients (P = .168). The patients with positive PLA2R antibody had higher positive rate of microscopic hematuria and urinary protein, lower albumin.The aMN patients are younger, higher smoking rate, its main clinical manifestation is nephrotic syndrome, but more of them accompanied with nephritis syndrome than those in iMN patients. Serum PLA2R antibody could not distinguish aMN from iMN. aMN could be a special glomerular disease in China, and need a further research on a larger scale.

The Kidney Injury Induced by Short-Term PM2.5 Exposure and the Prophylactic Treatment of Essential Oils in BALB/c Mice

PM_2.5 is well known as a major environmental pollutant; it has been proved to be associated with kidney diseases. The kidney damage involves oxidative stress and/or inflammatory response. NOX4 is a major source of reactive oxygen species (ROS) generation in the kidney, and the excessive generation of ROS is recognized to be responsible for oxidative stress. To elucidate whether short-term PM_2.5 exposure could induce kidney damage, we exposed BALB/c mice to PM_2.5 intratracheally and measured the biomarkers of kidney injury (KIM-1, cystatin C), oxidative stress (MDA, SOD-1, and HO-1), and inflammatory response (NF-κB, TNF-α). Acute kidney damage and excessive oxidative stress as well as transient inflammatory response were observed after PM_2.5 installation. The overexpression of some components of the angiotensin system (RAS) after PM_2.5 exposure illustrated that RAS may be involved in PM_2.5-induced acute kidney injury. CEOs (compound essential oils) have been widely used because of their antioxidant and anti-inflammation properties. Treatment with CEOs substantially attenuated PM_2.5-induced acute kidney injury. The suppression of RAS activation was significant and earlier than the decrease of oxidative stress and inflammatory response after CEOs treatment. We hypothesized that CEOs could attenuate the acute kidney injury by suppressing the RAS activation and subsequently inhibit the oxidative stress and inflammatory response.

The Spectrum of Biopsy-Proven Glomerular Diseases among Children in China: A National, Cross-Sectional Survey

BACKGROUND AND OBJECTIVES

High-quality epidemiologic data on the spectrum of biopsy-proven glomerular diseases among children are limited. This study aimed to determine the profile of and temporal change in biopsy-proven pediatric glomerular diseases in China.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We previously conducted a nationwide kidney biopsy survey including 71,151 patients over an 11-year period from January 2004 to December 2014. A total of 7962 children younger than 18 years old from 115 hospitals across China with biopsy-proven glomerular diseases were included in this study. The demographic and clinical variables were extracted from referral records and pathology reports. The composition of pediatric glomerular diseases and clinicopathologic correlations in different sexes, age groups, and regions were assessed. The changing patterns of common glomerulopathies over the study period were examined.

RESULTS

Nephrotic syndrome (50%) was the most frequent indication for kidney biopsy in children. Minimal change disease was the most common primary glomerular disease (29%) followed by IgA nephropathy (17%). Henoch-Schonlein purpura nephritis (13%) and lupus nephritis (9%) were the most common secondary glomerular diseases. The proportion of minimal change disease was significant higher in boys (38%) than in girls (13%), whereas lupus nephritis was more prevalent in girls (20%) than in boys (3%). Purpura nephritis (23%) was the major pathologic pattern in younger children (0-12 years old), whereas minimal change disease (33%) was the most common glomerulopathy in adolescents (13-18 years old). The clinicopathologic correlations were slightly different between sexes and age groups. We observed increases in the proportions of minimal change disease, purpura nephritis, and membranous nephropathy over the study period that were contemporaneous with a fall in the proportion of FSGS.

CONCLUSIONS

The spectrum of glomerular diseases among children varied across sexes, age groups, and regions and changed substantially from 2004 to 2014 in China.

The mTOR/p70S6K1 signaling pathway in renal fibrosis of children with immunoglobulin A nephropathy

Aim:

The purpose of this study was to explore whether mTOR/p70S6K1 signaling is activated in renal fibrosis of immunoglobulin A nephropathy.

Methods:

Seventy-two children with immunoglobulin A nephropathy were divided into three groups according to their clinical features and pathological grades. Six normal renal specimens were included in the control group. The expression levels of angiotensin II, mTOR, p70S6K1, E-cadherin, and α-smooth muscle actin in renal tissues were determined by immunohistochemistry method, the potential correlations of these indexes and relationship between these indexes and the clinicopathological indexes were analyzed.

Results:

Compared to the control group, the expression levels of angiotensin II, mTOR, p70S6K1, and α-smooth muscle actin were significantly higher and the expression levels of E-cadherin were lower both in glomeruli and tubulointerstitium of immunoglobulin A nephropathy children. And the most significant differences were found in the nephrotic syndrome group and pathological grade IV group. In immunoglobulin A nephropathy renal tissues, the expression levels of angiotensin II in glomeruli and tubulointerstitium were both positively correlated with the expression levels of mTOR and α- smooth muscle actin, and negatively correlated with the expression levels of E-cadherin.

Conclusion:

The mTOR/p70S6K1 signaling was activated in renal tissues of children with immunoglobulin A nephropathy, and future studies will need to address the mechanism of mTOR/p70S6K1 signaling in the progress of renal fibrosis in immunoglobulin A nephropathy.

Expression of phospholipase A2 receptor and IgG4 in patients with membranous nephropathy

OBJECTIVES

The aims of this study were to detect the expression of M phospholipase A2 receptor (PLA2R) in the kidney tissue of patients with idiopathic membranous nephropathy (IMN), secondary membranous nephropathy (SMN), and the nonmembranous nephropathy (non-MN), to evaluate the value of PLA2R in the kidney tissue and serum anti-PLA2R antibody in the diagnosis of membranous nephropathy (MN), and to explore the relationship between PLA2R of the kidney tissue or serum anti-PLA2R antibody and clinical features of MN.

METHODS

The kidney tissue was collected by kidney biopsy. Immunofluorescence assay was used to detect the level of PLA2R and IgG4 antigen in kidney tissue. Furthermore, the level of the PLA2R was detected using the enzyme-linked immunosorbent assay (ELISA). The positive and negative rates of PLA2R and IgG4 in different diseases and the sensitivity and specificity, were calculated using the statistical method. The specificity and coincidence rate of PLA2R or anti-PLA2R used in the differential diagnosis of IMN and SMN were evaluated.

RESULTS

The expression intensities of anti-PLA2R antibody and IgG4 were significantly higher in patients with IMN than in patients with SMN but are not non-MN. There was no significant difference in anti-PLA2R antibody and IgG4 in patients with SMN and non-MN. The coincidence rate of serum anti-PLA2R antibody and PLA2R in kidney tissue was 100%.

CONCLUSION

The expression of PLA2R and IgG4 antibody had great significance in the pathological diagnosis of MN. The detection of the serum anti-PLA2R antibody had great diagnostic value in diagnosing MN.

Response Predictors to Calcineurin Inhibitors in Patients with Primary Membranous Nephropathy

BACKGROUND

Currently, there is an urgent need to find ways of identifying primary membranous nephropathy (PMN) patients who are likely to benefit from calcineurin inhibitors (CNI) or who are resistant to them. In this study, we employed nano-HPLC-MS/MS analysis to identify serum biomarkers that predict the clinical response to CNI therapy in PMN patients.

METHODS

The endpoint was complete remission (CR) after CNI treatment. PMN patients were grouped into no-remission (NR) or CR groups to screen predictive candidates using the nano-HPLC-MS/MS analysis.

RESULTS

Compared with NR patients, 3 upregulated proteins and 5 downregulated proteins were found to present a twofold change in CR patients' serum. Serum amyloid A1 protein (SAA1) was further validated by ELISA; it was decreased in patients in the NR group compared with patients in the CR group, but SAA1 in patients in these groups was lower than in healthy controls and minimal change disease patients. The area under the receiver operating characteristic (ROC) curve of SAA1 was used to distinguish PMN NR patients from those in remission and was 0.901, with a sensitivity of 78.3% and specificity of 86.8%, similar to that of the phospholipase A2 receptor (PLA2R) antibody. Combining SAA1 with the PLA2R antibody, the area under the ROC curve was 0.956, which was higher than that of SAA1 or the PLA2R antibody alone.

CONCLUSIONS

Serum SAA1 may be a candidate PMN biomarker that can be used to discriminate CNI NR cases from remission patients. The combination of SAA1 and the PLA2R antibody increases the accuracy of diagnosis.

The Genetic and Environmental Factors of Primary Membranous Nephropathy: An Overview from China

Background

Primary membranous nephropathy (pMN) is the most common cause of nephrotic syndrome in adults. The discovery of the 2 autoantigens, M-type phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A), has defined pMN as an autoimmune disease. A remarkable increase in the frequency of pMN in primary glomerular disease was witnessed in China. The genetic and environmental contributors to disease susceptibility have been investigated in these patients.

Summary

We reviewed recent publications in genetic and environmental studies of pMN, focusing mainly on those undertaken in China. Following a genome-wide association study, the gene-gene interaction between the 2 most significant risk factors, PLA2R1 and DQA1, was validated in Chinese patients with MN. Fine mapping on human leukocyte antigen (HLA) locus found that DRB1*1501 and DRB1*0301 were risk alleles. Three amino acid residues on positions 13 and 71 of HLA-DRβ1 chain may confer the susceptibility to pMN by presenting T-cell epitopes on PLA2R. Another study found that DRB3*0202 was the most likely culprit allele for the signal at DRB1*0301. One environmental risk factor for pMN has been identified as the long-term exposure to high levels of PM_2.5 in Chinese patients with MN. Each 10 μg/m³ increase in PM_2.5 concentration was associated with 14% higher odds for pMN in the regions with PM_2.5 above 70 μg/m³.

Key Message

A gene-environment interaction is suspected as an underlying mechanism for the increasing trend of pMN in China.

Marijuana Use and Renal Function Among US Adults

BACKGROUND

In recent years, the number of states that have legalized medical marijuana or retail sales has increased, bringing potential changes of marijuana use pattern among the general population. However, health effects of acute and chronic marijuana use on many relevant health outcomes, including renal function, remain largely unexamined. In this study, we aimed to assess the association between recent and past marijuana use and renal function.

METHODS

We conducted a cross-sectional study among 13,995 US adults aged 18 to 59 years in the National Health and Nutrition Examination Survey from 2007 to 2014. We examined associations between marijuana use and serum creatinine concentration, estimated glomerular filtration rate (eGFR), and odds of having stage 2 or greater chronic kidney disease using weighted multivariable linear regression.

RESULTS

In the study population, 6483 were never users, 5499 were past users, and 2013 were current users. Marijuana use did not have a significant association with serum creatinine, eGFR, or odds of having stage 2 or greater chronic kidney disease. Serum creatinine and eGFR had an increasing trend comparing past and current users with never users that did not reach statistical significance. All associations remained unchanged in the sensitivity analysis restricted to people without cardiovascular disease.

CONCLUSIONS

We did not observe any clinically significant association between current or past self-reported marijuana use and measures of kidney function.

The modern spectrum of biopsy-proven renal disease in Chinese diabetic patients-a retrospective descriptive study

Background

Renal biopsies performed in diabetic patients are increasing and becoming more complex. Comprehensive data on modern spectrum of biopsy-proven renal disease in Chinese diabetic patients are lacking.

Methods

In a nationwide renal biopsy survey including 71,151 native biopsies from 2004 to 2014, diabetic patients were identified according to the clinical diagnosis from referral records. The clinical data were extracted from referral records and pathological reports.

Results

A total of 1,604 diabetic patients, including 61 patients with T1DM, were analyzed in this study. The median age is 51.39 ± 11.37 years. Male patients accounted for 58% of the population. We found that only 44.7% of diabetic patients had the isolated pathological diagnosis of diabetic nephropathy (DN), while 49.1% had non-diabetic renal disease (NDRD) alone, and 6.2% had NDRD superimposed on DN. Nephrotic syndrome (n = 824, 51.4%) was the most common clinical indication for renal biopsy. Among 887 patients with NDRD, membranous nephropathy (n = 357) was the leading diagnosis, followed by IgA nephropathy (n = 179). Hypertensive renal disease (n = 32), tubulointerstitial nephropathy (n = 27) and acute tubular necrosis (n = 16) accounted for 3.5%, 2.9%, 1.7% of the NDRD cases respectively. Nearly a half (49.2%) of patients with T1DM had NDRD.

Discussion

Over 55% diabetic patients with kidney disease were diagnosed as non-diabetic renal disease, among which MN and IgAN were the most common two pathological types.

Traffic-related air pollution associated with chronic kidney disease among elderly residents in Taipei City

The associations of air pollution with chronic kidney disease (CKD) have not yet been fully studied. We enrolled 8,497 Taipei City residents older than 65 years and calculated the estimated glomerular filtration rate (eGFR) using the Taiwanese Chronic Kidney Disease Epidemiology Collaboration equation. Proteinuria was assessed via dipstick on voided urine. CKD prevalence and risk of progression were defined according to the KDIGO 2012 guidelines. Land-use regression models were used to estimate the participants' one-year exposures to PM of different sizes and traffic-related exhaust, PM_2.5 absorbance, nitrogen dioxide (NO₂), and NO_x. Generalized linear regressions and logistic regressions were used to examine the associations of one-year air pollution exposures with eGFR, proteinuria, CKD prevalence and risk of progression. The results showed that the interquartile range (IQR) increments of PM_2.5 absorbance (0.4 × 10^-5/m) and NO₂ (7.0 μg/m³) were associated with a 1.07% [95% confidence interval (CI): 0.54-1.57] and 0.84% (95% CI: 0.37-1.32) lower eGFR, respectively; such relationships were magnified in subjects who had an eGFR >60 ml/min/1.73 m² or who were non-diabetic. Similar associations were also observed for PM₁₀ and PM_2.5-10. Two-pollutant models showed that PM₁₀ and PM_2.5 absorbance were associated with a lower eGFR. The odd ratios (ORs) of CKD prevalence and risk of progression also increased with exposures to PM_2.5 absorbance and NO_2. In summary, one-year exposures to traffic-related air pollution were associated with lower eGFR, higher CKD prevalence, and increased risk of CKD progression among the elderly population. Air pollution-related impaired renal function was stronger in non-CKD and non-diabetic subjects.

Environmental pollution and kidney diseases

The burden of disease and death attributable to environmental pollution is becoming a public health challenge worldwide, especially in developing countries. The kidney is vulnerable to environmental pollutants because most environmental toxins are concentrated by the kidney during filtration. Given the high mortality and morbidity of kidney disease, environmental risk factors and their effect on kidney disease need to be identified. In this Review, we highlight epidemiological evidence for the association between kidney disease and environmental pollutants, including air pollution, heavy metal pollution and other environmental risk factors. We discuss the potential biological mechanisms that link exposure to environmental pollutants to kidney damage and emphasize the contribution of environmental pollution to kidney disease. Regulatory efforts should be made to control environmental pollution and limit individual exposure to preventable or avoidable environmental risk. Population studies with accurate quantification of environmental exposure in polluted regions, particularly in developing countries, might aid our understanding of the dose-response relationship between pollutants and kidney diseases.

Changes in the Spectrum of Kidney Diseases: An Analysis of 40,759 Biopsy-Proven Cases from 2003 to 2014 in China

Objectives

To evaluate the changing spectrum of kidney diseases over time in China using renal biopsy-proven cases.

Methods

All patients over the age of 14 years who were diagnosed with a kidney disease by renal biopsy in the Renal Biopsy Registry of the National Clinical Research Center of Kidney Diseases in Jinling Hospital, Nanjing, from 2003 to 2014 were included.

Results

In total, 40,759 cases of renal biopsy were analyzed. The mean age of the patients was 36.59 ± 14.12 years. 52.0$ of the patients were male. Primary glomerulonephritis (PGN), secondary glomerulonephritis, tubulointerstitial disease, and hereditary renal diseases accounted for 67.1, 26.4, 2.9, and 2.5$, respectively. IgA nephropathy (IgAN), membranous nephropathy (MN), minimal change disease, and focal segmental glomerulosclerosis were the leading PGN diagnoses. The frequency of MN increased significantly (p < 0.001) by doubling from 2003 to 2014. An analysis by age category indicated that the frequency of MN increased significantly over time (p < 0.001) in all age categories and increased by more than 2 times in the 14-24 age category. Lupus nephritis (LN) and Henoch-Schönlein purpura nephritis (HSPN) decreased significantly (p < 0.001), diabetic nephropathy (DN) increased nearly twice (p < 0.001), monoclonal immunoglobulin deposition disease (MIDD) tripled (p < 0.001), and hypertensive nephropathy (HT) (p < 0.001) and renal amyloidosis (AMY) (p < 0.05) showed an upward trend. An analysis by age category showed that hepatitis B-related nephritis has significantly decreased in the 14-24 age category (p < 0.001).

Conclusion

PGN continued to be the predominant kidney disease in China with IgAN being the most common PGN. The frequency of MN increased significantly, with a maximum increase in young adults. LN and HSPN decreased significantly, DN and MIDD increased significantly, and HT and AMY also showed an increasing trend. The kidney disease trends presented in this study serve as a reference point for patient care, disease prevention, and public health interventions.

Spatial distribution of kidney disease in the contaminated site of Taranto (Italy)

BACKGROUND

Exposure to heavy metals has been associated with kidney disease. We investigated the spatial distribution of kidney disease in the industrially contaminated site of Taranto.

METHODS

Cases were subjects with a first hospital discharge diagnosis of kidney disease. Cases affected by specific comorbidities were excluded. Standardized Hospitalization Ratios (SHRs) were computed for low/high exposure area and for modeled spatial distribution of cadmium and fine particulate matter.

RESULT

Using the high/low exposure approach, in subjects aged 20-59 years residing in the high exposure area a significant excess of hospitalization was observed in males and a non-significant excess in females. No excesses were observed in subjects aged 60 years and over. The analysis by the modeling approach did not show a significant association with the greatest pollution impact area.

CONCLUSION

Due to the excesses of hospitalization observed in the high/low exposure approach, a continuing epidemiological surveillance of residents and occupational groups is warranted.

Serum anti-PLA2R antibody as a diagnostic biomarker of idiopathic membranous nephropathy: The optimal cut-off value for Chinese patients

BACKGROUND

The M-type phospholipase A2 receptor (PLA2R) is a specific target autoantigen identified in idiopathic membranous nephropathy (IMN). The autoantibody against PLA2R (anti-PLA2R) may be used to diagnose IMN. However, the appropriate diagnosis cut-off value for Chinese patients with IMN has not been established.

METHODS

In total, 119 patients who underwent renal biopsy (57 patients with IMN and 62 patients with non-IMN glomerulonephritis) and 22 healthy individuals were recruited for our observation study from Qianfoshan Hospital between September 2011 and March 2016. The serum concentration of anti-PLA2R was measured using a quantitative enzyme-linked immunosorbent assay (ELISA). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and receiver operating characteristic (ROC) curve of anti-PLA2R in diagnosing IMN were analysed based on the ELISA detection.

RESULTS

The sensitivity, specificity, PPV, and NPV of anti-PLA2R in the diagnosis of IMN in the Chinese patients were 82.5, 75, 69.1, and 86.3% for the 2RU/ml cut-off value; 78.9, 91.7, 86.5, and 86.5% for the 2.6RU/ml cut-off value; 59.6, 95.2, 89.5, and 77.7% for the 14RU/ml cut-off value; 50.9, 96.4, 90.6, and 74.3% for the 20RU/ml cut-off value; and 47.4, 97.6, 93.1, and 73.2% for the 40RU/ml cut-off value, respectively. The area under the ROC curve was 0.879.

CONCLUSIONS

The cut-off value of 2.6RU/ml is recommended for the use of anti-PLA2R for the diagnosis of IMN in Chinese patients based on the ELISA.

Associations of ambient coarse particulate matter, nitrogen dioxide, and carbon monoxide with the risk of kidney disease: a cohort study

BACKGROUND

Experimental evidence and preliminary clinical evidence suggest that environmental air pollution adversely effects kidney health. Previous work has examined the association between fine particulate matter and risk of kidney disease; however, the association between ambient coarse particulate matter (PM₁₀; ≤10 μm in aerodynamic diameter), nitrogen dioxide (NO₂), and carbon monoxide (CO) and risk of incident chronic kidney disease, chronic kidney disease progression, and end-stage renal disease is not clear.

METHODS

We merged multiple large databases, including those of the Environmental Protection Agency and the Department of Veterans Affairs, to build a cohort of US veterans, and used survival models to evaluate the association between PM₁₀, NO₂, and CO concentrations and risk of incident estimated glomerular filtration rate (eGFR) of less than 60 mL/min per 1·73 m², incident chronic kidney disease, eGFR decline of 30% or more, and end-stage renal disease. We treated exposure as time-varying when it was updated annually and as cohort participants moved.

FINDINGS

Between Oct 1, 2003, and Sept 30, 2012, 2 010 398 cohort participants were followed up over a median of 8·52 years (IQR 8·05-8·80). An increased risk of eGFR of less than 60 mL/min per 1·73 m² was associated with an IQR increase in concentrations of PM₁₀ (hazard ratio 1·07, 95% CI 1·06-1·08), NO₂ (1·09, 1·08-1·10), and CO (1·09, 1·08-1·10). An increased risk of incident chronic kidney disease was associated with an IQR increase in concentrations of PM₁₀ (1·07, 1·05-1·08), NO₂ (1·09, 1·08-1·11), and CO (1·10, 1·08-1·11). An increased risk of an eGFR decline of 30% or more was associated with an IQR increase in concentrations of PM₁₀ (1·08, 1·07-1·09), NO₂ (1·12, 1·10-1·13), and CO (1·09, 1·08-1·10). An increased risk of end-stage renal disease was associated with an IQR increase in concentrations of PM₁₀ (1·09, 1·06-1·12), NO₂ (1·09, 1·06-1·12), and CO (1·05, 1·02-1·08). Spline analyses suggested a monotonic increasing association between PM₁₀, NO₂, and CO concentrations and risk of kidney outcomes.

INTERPRETATION

Environmental exposure to higher concentrations of PM₁₀, NO₂, and CO is associated with increased risk of incident chronic kidney disease, eGFR decline, and end-stage renal disease.

FUNDING

US Department of Veterans Affairs.

Particulate Matter Air Pollution and the Risk of Incident CKD and Progression to ESRD

Elevated levels of fine particulate matter <2.5 µm in aerodynamic diameter (PM_2.5) are associated with increased risk of cardiovascular outcomes and death, but their association with risk of CKD and ESRD is unknown. We linked the Environmental Protection Agency and the Department of Veterans Affairs databases to build an observational cohort of 2,482,737 United States veterans, and used survival models to evaluate the association of PM_2.5 concentrations and risk of incident eGFR <60 ml/min per 1.73 m², incident CKD, eGFR decline ≥30%, and ESRD over a median follow-up of 8.52 years. County-level exposure was defined at baseline as the annual average PM_2.5 concentrations in 2004, and separately as time-varying where it was updated annually and as cohort participants moved. In analyses of baseline exposure (median, 11.8 [interquartile range, 10.1-13.7] µg/m³), a 10-µg/m³ increase in PM_2.5 concentration was associated with increased risk of eGFR<60 ml/min per 1.73 m² (hazard ratio [HR], 1.21; 95% confidence interval [95% CI], 1.14 to 1.29), CKD (HR, 1.27; 95% CI, 1.17 to 1.38), eGFR decline ≥30% (HR, 1.28; 95% CI, 1.18 to 1.39), and ESRD (HR, 1.26; 95% CI, 1.17 to 1.35). In time-varying analyses, a 10-µg/m³ increase in PM_2.5 concentration was associated with similarly increased risk of eGFR<60 ml/min per 1.73 m², CKD, eGFR decline ≥30%, and ESRD. Spline analyses showed a linear relationship between PM_2.5 concentrations and risk of kidney outcomes. Exposure estimates derived from National Aeronautics and Space Administration satellite data yielded consistent results. Our findings demonstrate a significant association between exposure to PM_2.5 and risk of incident CKD, eGFR decline, and ESRD.

Particulate Matter (Fine Particle) and Urologic Diseases

Particulate matter (PM) has been found to damage vital body organs, including the lungs and heart, through vascular damage and oxidative stress. Recently, renal function and chronic urologic diseases have also been found to be related to PM. To investigate this, we reviewed the characteristics of PM related to renal toxicity, including recent studies on the associations of urologic diseases with PM. PM can include constituents that cause renal toxicity, such as lead, cadmium, arsenic, and crystalline silica, which result in renal tubular or interstitial damage. Since 2008, 7 studies have evaluated the renal effects of PM. Two prospective cohort studies and a quantitative study of consecutive patients showed that PM may be related to decreased renal function, as shown by the estimated glomerular filtration rate of diseased or aged participants. Two cross-sectional studies found an association between PM and chronic kidney disease. One of those studies identified the specific renal diseases of immunoglobulin A nephropathy and membranous nephropathy. Two studies that analyzed renal cancer and PM showed no evidence that renal cancer is related to PM. Nine studies were evaluated regarding the relationship of bladder and prostate cancer with PM. The evidence for an association of PM with bladder and prostate cancer is still inconclusive. Although some recently published studies have shown a significant relationship, the causal relationship is not clear. Further well-designed studies on specific renal diseases are required.

Blockage of the lysosome-dependent autophagic pathway contributes to complement membrane attack complex-induced podocyte injury in idiopathic membranous nephropathy

Dysregulation of autophagy-mediated podocyte homeostasis is proposed to play a role in idiopathic membranous nephropathy (IMN). In the present study, autophagic activity and lysosomal alterations were investigated in podocytes of IMN patients and in cultured podocytes exposed to sublytic terminal complement complex, C5b-9. C5b-9 upregulated the number of LC3 positive puncta and the expression of p62 in patient podocytes and in C5b-9 injuried podocyte model. The lysosomal turnover of LC3-II was not influenced, although the BECN1 expression level was upregulated after exposure of podocytes to C5b-9. C5b-9 also caused a significant increase in the number of autophagosomes but not autolysosomes, suggesting that C5b-9 impairs the lysosomal degration of autophagosomes. Moreover, C5b-9 exacerbated the apoptosis of podocytes, which could be mimicked by chloroquine treatment, indicating that C5b-9 triggered podocyte injury, at least partially through inhibiting autophagy. Subsequent studies revealed that C5b-9 triggered lysosomal membrane permeabilization, which likely caused the decrease in enzymatic activity, defective acidification of lysosomes, and suppression of DQ-ovalbumin degradation. Taken together, our results suggest that the lysosomal-dependent autophagic pathway is blocked by C5b-9, which may play a key role in podocyte injury during the development of IMN.

Oxidative Stress and Cardiovascular Risk: Obesity, Diabetes, Smoking, and Pollution: Part 3 of a 3-Part Series

Oxidative stress occurs whenever the release of reactive oxygen species (ROS) exceeds endogenous antioxidant capacity. In this paper, we review the specific role of several cardiovascular risk factors in promoting oxidative stress: diabetes, obesity, smoking, and excessive pollution. Specifically, the risk of developing heart failure is higher in patients with diabetes or obesity, even with optimal medical treatment, and the increased release of ROS from cardiac mitochondria and other sources likely contributes to the development of cardiac dysfunction in this setting. Here, we explore the role of different ROS sources arising in obesity and diabetes, and the effect of excessive ROS production on the development of cardiac lipotoxicity. In parallel, contaminants in the air that we breathe pose a significant threat to human health. This paper provides an overview of cigarette smoke and urban air pollution, considering how their composition and biological effects have detrimental effects on cardiovascular health.

PLA2R and THSD7A: Disparate Paths to the Same Disease?

The phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A) are the two major autoantigens in primary membranous nephropathy (MN), and define two molecular subclasses of this disease. Both proteins are large transmembrane glycoproteins expressed by the podocyte, and both induce IgG4-predominant humoral immune responses that produce circulating autoantibodies that can be used clinically for diagnostic and monitoring purposes. The biologic roles of these proteins remain speculative, although several features of THSD7A suggest a role in adhesion. PLA2R-associated MN was initially found to associate with risk alleles within HLA-DQA1, but subsequent studies have shifted the focus to the HLA-DRB locus. Three distinct humoral epitope-containing regions have been defined within the extracellular portion of PLA2R, and it appears that the number of targeted epitopes may determine disease severity. Although similar information is not yet available for THSD7A-associated MN, this form of MN may have a unique association with malignancy. Finally, it appears likely that other autoantigens in primary MN exist. Although protocols similar to those that identified PLA2R and THSD7A may be successful in the identification of novel antigenic targets in MN, newer techniques such as laser-capture mass spectrometry or protein arrays may be helpful as well.

Primary Membranous Nephropathy

Membranous nephropathy (MN) is a unique glomerular lesion that is the most common cause of idiopathic nephrotic syndrome in nondiabetic white adults. About 80% of cases are renal limited (primary MN, PMN) and 20% are associated with other systemic diseases or exposures (secondary MN). This review focuses only on PMN. Most cases of PMN have circulating IgG4 autoantibody to the podocyte membrane antigen PLA2R (70%), biopsy evidence PLA2R staining indicating recent immunologic disease activity despite negative serum antibody levels (15%), or serum anti-THSD7A (3%-5%). The remaining 10% without demonstrable anti-PLA2R/THSd7A antibody or antigen likely have PMN probably secondary to a different, still unidentified, anti-podocyte antibody. Considerable clinical and experimental data now suggests these antibodies are pathogenic. Clinically, 80% of patients with PMN present with nephrotic syndrome and 20% with non-nephrotic proteinuria. Untreated, about one third undergo spontaneous remission, especially those with absent or low anti-PLA2R levels, one-third progress to ESRD over 10 years, and the remainder develop nonprogressive CKD. Proteinuria can persist for months after circulating anti-PLA2R/THSD7A antibody is no longer detectable (immunologic remission). All patients with PMN should be treated with supportive care from the time of diagnosis to minimize protein excretion. Patients with elevated anti-PLA2R/THSD7A levels and proteinuria >3.5 g/d at diagnosis, and those who fail to reduce proteinuria to <3.5 g after 6 months of supportive care or have complications of nephrotic syndrome, should be considered for immunosuppressive therapy. Accepted regimens include steroids/cyclophosphamide, calcineurin inhibitors, and B cell depletion. With proper management, only 10% or less will develop ESRD over the subsequent 10 years.

Indoor air pollution and its association with poor lung function, microalbuminuria and variations in blood pressure among kitchen workers in India: a cross-sectional study

BACKGROUND

The present study is an attempt to explore the association between kitchen indoor air pollutants and physiological profiles in kitchen workers with microalbuminuria (MAU) in north India (Lucknow) and south India (Coimbatore).

METHODS

The subjects comprised 145 control subjects, 233 kitchen workers from north India and 186 kitchen workers from south India. Information related to the personal and occupational history and health of the subjects at both locations were collected using a custom-made questionnaire. Worker lung function was measured using a spirometer. Blood pressure was monitored using a sphygmomanometer. Urinary MAU was measured using a urine analyzer. Indoor air monitoring in kitchens for particulate matter (PM), total volatile organic compounds (TVOC), carbon dioxide (CO₂) and carbon monoxide (CO) was conducted using indoor air quality monitors. The size and shape of PM in indoor air was assessed using a scanning electron microscope (SEM). Fourier transform infrared (FTIR) spectroscopy was used to detect organic or inorganic compounds in the air samples.

RESULTS

Particulate matter concentrations (PM_2.5 and PM₁) were significantly higher in both north and south Indian kitchens than in non-kitchen areas. The concentrations of TVOC, CO and CO₂ were higher in the kitchens of north and south India than in the control locations (non-kitchen areas). Coarse, fine and ultrafine particles and several elements were also detected in kitchens in both locations by SEM and elemental analysis. The FTIR spectra of kitchen indoor air at both locations show the presence of organic chemicals. Significant declines in systolic blood pressure and lung function were observed in the kitchen workers with MAU at both locations compared to those of the control subjects. A higher prevalence of obstruction cases with MAU was observed among the workers in the southern region than in the controls (p < 0.01).

CONCLUSIONS

Kitchen workers in south India have lower lung capacities and a greater risk of obstructive and restrictive abnormalities than their north Indian counterparts. The study showed that occupational exposure to multiple kitchen indoor air pollutants (ultrafine particles, PM_2.5, PM₁, TVOC, CO, CO₂) and FTIR-derived compounds can be associated with a decline in lung function (restrictive and obstructive patterns) in kitchen workers with microalbuminuria. Further studies in different geographical locations in India among kitchen workers on a wider scale are required to validate the present findings.

[Clinical and pathological features in IgA nephropathy with IgG deposition in the glomerular mesangial area]

OBJECTIVE

To investigate the relationship between the clinical and pathological findings in IgA nephropathy with or without IgG deposition in the glomerular mesangial area.

METHODS

The data were collected from 122 patients with a diagnosis of IgA nephropathy by renal biopsy in the Third Affiliated Hospital of Southern Medical University between November, 2009 and February, 2016. All the samples were examined by light microscopy, immunofluorescence and electron microscopy. According to the results of immunofluorescence assay, the patients were divided into IgA group (n=63) and IgA-IgG group (n=59). The pathological classification of IgA nephropathy was analyzed according to Oxford classification and Lee's classification. The clinical and pathological findings were compared between the two groups.

RESULTS

Compared with the patients with IgA nephropathy but without IgG deposition, patients with IgA nephropathy with IgG deposition had higher serum creatinine, higher 24-h urine protein, higher blood uric acid, higher triglyceride levels (P<0.05) and lower eGFR (P<0.05); more of these patients were in Lee's grade IV-V, had renal tubular atrophy and/or interstitial fibrosis, and had MEST scores more than 3 (P<0.05).

CONCLUSION

Patients with IgA nephropathy with IgG deposition in the glomerular mesangial have severer clinical symptoms and more serious pathological changes. Measures should be taken to control IgG deposition in patients with IgA nephropathy to delay the progress of the disease.

[Clinical and pathological features in IgA nephropathy with IgG deposition in the glomerular mesangial area]

OBJECTIVE

To investigate the relationship between the clinical and pathological findings in IgA nephropathy with or without IgG deposition in the glomerular mesangial area.

METHODS

The data were collected from 122 patients with a diagnosis of IgA nephropathy by renal biopsy in the Third Affiliated Hospital of Southern Medical University between November, 2009 and February, 2016. All the samples were examined by light microscopy, immunofluorescence and electron microscopy. According to the results of immunofluorescence assay, the patients were divided into IgA group (n=63) and IgA-IgG group (n=59). The pathological classification of IgA nephropathy was analyzed according to Oxford classification and Lee's classification. The clinical and pathological findings were compared between the two groups.

RESULTS

Compared with the patients with IgA nephropathy but without IgG deposition, patients with IgA nephropathy with IgG deposition had higher serum creatinine, higher 24-h urine protein, higher blood uric acid, higher triglyceride levels (P<0.05) and lower eGFR (P<0.05); more of these patients were in Lee's grade IV-V, had renal tubular atrophy and/or interstitial fibrosis, and had MEST scores more than 3 (P<0.05).

CONCLUSION

Patients with IgA nephropathy with IgG deposition in the glomerular mesangial have severer clinical symptoms and more serious pathological changes. Measures should be taken to control IgG deposition in patients with IgA nephropathy to delay the progress of the disease.