Membranous nephropathy: a review on the pathogenesis, diagnosis, and treatment

Development of a time-resolved fluoroimmunoassay for rituximab and its application to therapeutic drug monitoring

BACKGROUND

Rituximab pharmacokinetics in patients with membranous nephropathy (MN) exhibit significant interindividual variability. Accurate measurement of serum rituximab concentrations is essential for effective therapeutic monitoring. This study develops a highly sensitive time-resolved fluoroimmunoassay (TRFIA) for rituximab (rituximab-TRFIA) with a wide detection range, aimed at enhancing therapeutic drug monitoring in MN treatment.

METHODS

A capture -type rituximab-TRFIA was developed using streptavidin-coated microplates, biotinylated anti-rituximab idiotypic antibodies, and Eu3+-labeled mouse anti-human IgG targeting the Fc fragment of rituximab. The assay was used to measure rituximab serum concentrations in MN patients treated with rituximab.

RESULTS

The linear range of rituximab-TRFIA is 0.50 to 2500 ng/mL, with a limit of detection (LOD) of 0.062 ng/mL. The intra-assay coefficient of variation (CV) ranges from 1.97 % to 9.50 %, while the inter-assay CV ranges from 7.44 % to 9.99 %. The recovery rate ranges from 99.14 % to 107.75 %. No cross-reactivity was observed with other monoclonal antibody drugs (mAbs). The detection range is two orders of magnitude higher, and the sensitivity is six times greater than that of the enzyme-linked immunosorbent assay (ELISA). Rituximab-TRFIA showed strong consistency within the same measurement range compared to ELISA (P < 0.0001). The serum rituximab levels in MN patients were significantly higher than those in the control group (P < 0.0001). Among patients who did not achieve remission, 60 % to 70 % had insufficient drug concentrations, and rituximab pharmacokinetics followed the expected trends.

CONCLUSIONS

The rituximab-TRFIA provides high sensitivity, a wide detection range, and reliable performance for monitoring serum rituximab concentrations in MN patients, supporting personalized treatment strategies.

Research progress on the role and inhibitors of Keap1 signaling pathway in inflammation

Inflammation is a protective mechanism against endogenous and exogenous pathogens. It is a typical feature of numerous chronic diseases and their complications. Keap1 is an essential target in oxidative stress and inflammatory diseases. Among them, the Keap1-Nrf2-ARE pathway (including Keap1-Nrf2-HO-1) is the most significant pathway of Keap1 targets, which participates in the control of inflammation in multiple organs (including renal inflammation, lung inflammation, liver inflammation, neuroinflammation, etc.). Identifying new Keap1 inhibitors is crucial for new drug discovery. However, most drugs have specificity issues as they covalently bind to cysteine residues of Keap1, causing off-target effects. Therefore, direct inhibition of Keap1-Nrf2 PPIs is a new research idea. Through non-electrophilic and non-covalent binding, its inhibitors have better specificity and ability to activate Nrf2, and targeting therapy against Keap1-Nrf2 PPIs has become a new method for drug development in chronic diseases. This review summarizes the members and downstream genes of the Keap1-related pathway and their roles in inflammatory disease models. In addition, we summarize all the research progress of anti-inflammatory drugs targeting Keap1 from 2010 to 2024, mainly describing their biological functions, molecular mechanisms of action, and therapeutic roles in inflammatory diseases.

Prognostic value of serum complement cleavage factor Bb in idiopathic membranous nephropathy and establishment of nomogram model

Complement activation is involved in idiopathic membranous nephropathy (IMN). We aimed to investigate the relationship of serum complement cleavage factor Bb with IMN progression, and to establish a model for early prediction of kidney outcomes. We measured serum factor Bb in a retrospective cohort of 449 IMN patients at the time of kidney biopsy. Cox regression analysis showed that higher levels of serum factor Bb were independently associated with IMN progression event defined as end-stage renal disease or ≥ 40% decline in estimated glomerular filtration rate. Patients in the middle and highest tertiles of serum factor Bb had respectively 2.1-, and 2.6-fold higher risk for disease progression compared with those in the lowest tertile. We developed an optimized prognostic nomogram model incorporating age, log serum anti-PLA2R antibody, log serum Bb, proteinuria and tubular atrophy/interstitial fibrosis. The model demonstrated good predictive ability with a concordance index of 0.77 (bootstrap-corrected of 0.76) for predicting 3-, and 5-year kidney survival. Calibration curves and decision curve analysis confirmed the model's good calibration and clinical utility. Our findings suggest that serum factor Bb may serve as an essential prognostic indicator of IMN. The novel nomogram model may offer important guidance on the management of this patient population.

Villous Adenoma: A Rare Cause of Neural Epidermal Growth Factor-Like 1-Positive Membranous Nephropathy

We report the case of a 70-year-old woman diagnosed with neural epidermal growth factor-like 1 antigen-positive membranous nephropathy and nephrotic syndrome. Following thorough exclusion of autoimmune diseases, medications, or infections as potential causes, colonoscopy was performed as part of malignancy evaluation, revealing an 18 mm villous adenoma in the sigmoid colon and a 7 mm tubulovillous adenoma in the cecum. Despite the absence of gastrointestinal symptoms initially and the absence of high-grade dysplasia in the pathology report, the patient experienced a remarkable improvement in symptoms and a reduction in nephrotic-range proteinuria following polypectomy, observed within a few months.

From Diagnosis to Dialysis: Managing Primary Membranous Nephropathy in a Patient Living With Human Immunodeficiency Virus (HIV)

Membranous nephropathy (MN) is a significant cause of nephrotic syndrome in adults, with both primary and secondary etiologies contributing to its pathogenesis. This case report explores the clinical course of a 69-year-old African American man with human immunodeficiency virus (HIV) who developed primary MN, progressing to end-stage renal disease (ESRD) despite treatment efforts. Initially diagnosed with IgA nephropathy and HIV-associated immune complex kidney disease (HIVICK), the patient later developed anti-phospholipase A2 receptor (anti-PLA2R) antibody-positive MN. Despite immunosuppressive therapy and partial remission with rituximab, non-adherence to treatment led to disease exacerbation and eventual hospitalization for acute heart failure and worsening renal function. A subsequent renal biopsy revealed severe interstitial fibrosis and tubular atrophy, limiting further therapeutic options. This case underscores the challenges in managing MN, particularly in high-risk patients with comorbidities such as HIV, and highlights the importance of adherence to treatment and tailored management strategies to optimize outcomes in this complex condition.

Glomerulus-Targeted ROS-Responsive Polymeric Nanoparticles for Effective Membranous Nephropathy Therapy

Membranous nephropathy (MN) is a common immune-mediated glomerular disease that requires the development of safe and highly effective therapies. Celastrol (CLT) has shown promise as a therapeutic molecule candidate, but its clinical use is currently limited due to off-target toxicity. Given that excess levels of reactive oxygen species (ROS) contributing to podocyte damage is a key driver of MN progression to end-stage renal disease, we rationally designed ROS-responsive cationic polymeric nanoparticles (PPS-CPNs) with a well-defined particle size and surface charge by employing poly(propylene sulfide)-polyethylene glycol (PPS-PEG) and poly(propylene sulfide)-polyethylenimine (PPS-PEI) to selectively deliver CLT to the damaged glomerulus for MN therapy. Experimental results show that PPS-CPNs successfully crossed the fenestrated endothelium, accumulated in the glomerular basement membrane (GBM), and were internalized by podocytes where rapid drug release was triggered by the overproduction of ROS, thereby outperforming nonresponsive CLT nanotherapy to alleviate subepithelial immune deposits, podocyte foot process effacement, and GBM expansion in a rat MN model. Moreover, the ROS-responsive CLT nanotherapy was associated with significantly lower toxicity to major organs than free CLT. These results suggest that encapsulating CLT into PPS-CPNs can improve efficacy and reduce toxicity as a promising treatment option for MN.

A Neanderthal haplotype introgressed into the human genome confers protection against membranous nephropathy

Class 2 HLA and PLA2R1 alleles are exceptionally strong genetic risk factors for membranous nephropathy (MN), leading, through an unknown mechanism, to a targeted autoimmune response. Introgressed archaic haplotypes (introduced from an archaic human genome into the modern human genome) might influence phenotypes through gene dysregulation. Here, we investigated the genomic region surrounding the PLA2R1 gene. We reconstructed the phylogeny of Neanderthal and modern haplotypes in this region and calculated the probability of the observed clustering being the result of introgression or common descent. We imputed variants for the participants in our previous genome-wide association study and we compared the distribution of Neanderthal variants between MN cases and controls. The region associated with the lead MN risk locus in the PLA2R1 gene was confirmed and showed that, within a 507 kb region enriched in introgressed sequence, a stringently defined 105 kb haplotype, intersecting the coding regions for PLA2R1 and ITGB6, is inherited from Neanderthals. Thus, introgressed Neanderthal haplotypes overlapping PLA2R1 are differentially represented in MN cases and controls, with enrichment In controls suggesting a protective effect.

Recurrence of Idiopathic Membranous Nephropathy in the Kidney Allograft: A Systematic Review

INTRODUCTION

The recurrence of idiopathic membranous nephropathy (iMN) after kidney transplantation is common, although its exact clinical significance remains unclear. This systematic review aims to elucidate the effects of iMN recurrence on graft survival.

MATERIALS AND METHODS

A literature search was performed by systematically searching Medline, Scopus, Web of Science, and Google Scholar from inception. Cohort studies examining iMN recurrence after kidney transplantation were deemed eligible. Meta-analysis was performed by fitting random-effects models.

RESULTS

Twelve (12) articles published from 1995 to 2016 reporting on 139 transplant patients with recurrent iMN were included. The median time of the diagnosis of recurrent iMN was 18 months during follow-up from 35 to 120 months. Risk factors for iMN recurrence in the renal allograft are a positive serum test for anti-PLA2R antibodies pretransplant, female sex, younger age, high proteinuria pretransplant, the longest interval from initial disease to end-stage chronic kidney disease, and the combination of alleles HLA DQA1 05:01 and HLA DQB1 02:01. In the pretransplant period, 37 (26.61%) patients had a positive serum test and 18 (12.94%) patients had a positive biopsy stain for anti-PLA2R antibodies. The sensitivity of the pretransplant positive serum test for these antibodies ranges from 57% to 85.30% and the specificity is 85.10-100%. A total of 81.80% of patients who received rituximab as treatment for iMN recurrence achieved complete and partial remission, while 18.20% had no response to treatment. iMN recurrence was not associated with significantly different rates of graft loss (odds ratio = 1.03, 95% CI: 0.52-2.04, p = 0.524, I2 = 0.00%). Recurrence of iMN was not associated with increased risk of graft loss independently of whether patients were treated with rituximab (OR: 0.98, 95% CI: 0.39-2.50, I2: 0%) or not (OR: 1.22, 95% CI: 0.58-2.59, I2: 3.8%). Patients with iMN recurrence who achieved remission had significantly reduced risk of graft loss (OR: 0.14, 95% CI: 0.03 to 0.73).

CONCLUSION

The main outcome from this systematic review is that there is no statistically significant difference in graft survival in patients with iMN recurrence compared to those without recurrence in long-term follow-up. The achievement of remission is associated with significantly reduced risk of graft loss.

Expression and Clinical Significance of Non B Cell-Derived Immunoglobulins in the Urinary System and Male Reproductive System

The urinary system comprises kidneys, ureters, bladder, and urethra with its primary function being excretion, referring to the physiological process of transporting substances that are harmful or surplus out of the body. The male reproductive system consists of gonads (testis), vas deferens, and accessory glands such as the prostate. According to classical immunology theory, the tissues and organs mentioned above are not thought to produce immunoglobulins (Igs), and any Ig present in the relevant tissues under physiological and pathological conditions is believed to be derived from B cells. For instance, most renal diseases are associated with uncontrolled inflammation caused by pathogenic Ig deposited in the kidney. Generally, these pathological Igs are presumed to be produced by B cells. Recent studies have demonstrated that renal parenchymal cells can produce and secrete Igs, including IgA and IgG. Glomerular mesangial cells can express and secrete IgA, which is associated with cell survival and adhesion. Likewise, human podocytes demonstrate the ability to produce and secrete IgG, which is related to cell survival and adhesion. Furthermore, renal tubular epithelial cells also express IgG, potentially involved in the epithelial-mesenchymal transition (EMT). More significantly, renal cell carcinoma, bladder cancer, and prostate cancer have been revealed to express high levels of IgG, which promotes tumour progression. Given the widespread Ig expression in the urinary and male reproductive systems, continued efforts to elucidate the roles of Igs in renal physiological and pathological processes are necessary.

Large B-cell Lymphoma-Associated Membranous Nephropathy With Positive PLA2R on Kidney Biopsy

Large B-cell lymphoma associated with membranous nephropathy (MN) is a rare and complex medical condition that involves the simultaneous presence of two distinct diseases: a malignant lymphoma and a kidney disorder called membranous nephropathy. In this case, there is an additional element of interest, which is the presence of positive Phospholipase A2 Receptor (PLA2R) in the kidney. The case involves a 53-year-old Caucasian male with a three-week history of lower leg edema and a past medical history of recurrent upper respiratory infections. The upper respiratory infections were characterized by symptoms of fever, sore throat, and headache, and they required multiple rounds of antibiotics for treatment, including Augmentin and Keflex. A diagnosis of nephrotic syndrome was made based on proteinuria of fourteen grams with no RBC cast on urinalysis. Kidney biopsy stained positive for antiposophlipase A2 receptor on a frozen section. Thrombospondin type 1 domain-containing 7A (THSD7A) was not detected.  Given his biopsy and absence of clinical symptoms, he was treated as a case of primary membranous nephropathy with angiotensin-converting enzyme (ACE) inhibitors, steroids, and immunosuppressive. Three months following the treatment, his condition deteriorated, and after a thorough investigation, he appeared to have large B-cell lymphoma as a secondary cause of membranous glomerulopathy (MGN). When large B-cell lymphoma is associated with membranous nephropathy, it presents a unique clinical challenge. The interaction between these two conditions is not fully understood, but it is believed that the lymphoma may provoke an immune response that leads to the development of membranous nephropathy. Moreover, the presence of positive PLA2R in the kidney indicates a specific mechanism at play in this complex disease scenario. Treatment for this condition typically involves addressing both the lymphoma and the kidney disorder. This may include chemotherapy or other treatments to target the lymphoma and immunosuppressive therapy to manage the autoimmune response causing membranous nephropathy. Close monitoring and coordination between oncologists and nephrologists are essential for the best possible outcome in managing this rare and challenging condition.

Diagnostic utility of serum and urine biomarkers in idiopathic membranous nephropathy: a systematic review and meta-analysis

BACKGROUND

Membranous nephropathy is an autoimmune nephropathy that is one of the most common pathological types of nephrotic syndrome. It is important to find and apply specific biomarkers for the noninvasive diagnosis of idiopathic membranous nephropathy (IMN). However, there are limited data about their diagnostic value. Therefore, an overall meta-analysis helps to identify effective biomarkers for the clinical diagnosis of IMN.

METHODS

A systematic literature search was carried out in PubMed, Embase, Cochrane and Web of Science from inception until December 31, 2020. Two researchers searched for studies that met the inclusion criteria. The results of the joint study were expressed in terms of sensitivity and specificity.

RESULTS

The meta-analysis included 24 studies with biomarkers for the clinical diagnosis of IMN, including antibody against phospholipase A2 receptor (PLA2R-AB), antibody against thrombospondin type I domain-containing 7A (THSD7A-AB), lysosome membrane protein-2 (LIMP-2) and circular RNAs. The diagnostic efficiency of PLA2R-AB for IMN had a combined sensitivity of 60% and a combined specificity of 100%. The diagnostic efficiency of THSD7A-AB for IMN had a combined sensitivity of 3% and a combined specificity of 99%. The diagnostic efficiency of urinary LIMP-2 for IMN was 100%, and the specificity was 100%. The diagnostic efficiency of exosomal circRNAs for IMN was 100%, and the specificity was 100%.

CONCLUSIONS

This meta-analysis shows that PLA2R-AB and THSD7A-AB are of important diagnostic value for IMN. More studies are needed in the future to reveal the diagnostic value of LIMP-2 and circRNAs for IMN.

Towards the Definition of the Molecular Hallmarks of Idiopathic Membranous Nephropathy in Serum Proteome: A DIA-PASEF Approach

Idiopathic membranous nephropathy (IMN) is a pathologically defined disorder of the glomerulus, primarily responsible for nephrotic syndromes (NS) in nondiabetic adults. The underlying molecular mechanisms are still not completely clarified. To explore possible molecular and functional signatures, an optimised mass spectrometry (MS) method based on next-generation data-independent acquisition combined with ion-mobility was applied to serum of patients affected by IMN (n = 15) or by other glomerulopathies (PN) (n = 15). The statistical comparison highlighted a panel of 57 de-regulated proteins with a significant increase in lipoprotein-related proteins (APOC1, APOB, APOA1, APOL1 and LCAT) and a substantial quantitative alteration of key serpins (including A4, D1, A7, A6, F2, F1 and 1) possibly associated with IMN or NS and podocyte stress. A critical dysregulation in metabolisms of lipids (e.g., VLDL assembly and clearance) likely to be related to known hyperlipidemia in IMN, along with involvement of non-classical complement pathways and a putative enrolment of ficolin-2 in sustaining the activation of the lectin-mediated complement system have been pinpointed. Moreover, mannose receptor CD206 (MRC1-down in IMN) and biotinidase (BTD-up in IMN) are able alone to accurately distinguish IMN vs. PN. To conclude, our work provides key proteomic insights into the IMN complexity, opening the way to an efficient stratification of MN patients.

Spectrum and Distribution of Biopsy-proven Kidney Diseases: A 12-year Survey of a Single Center in Iran

Data about the prevalence of biopsy-proven kidney diseases in Iran are rare, and none of the previous studies used electron microscopy for diagnosis. This study aimed to analyze the prevalence of biopsy-proven kidney diseases in Iran's primary referral center. To the best of our knowledge, this is the most extensive study carried out in Iran. Reports of kidney biopsy samples from patients referred to our center in 2007-2018 were reviewed for demographic data, clinical presentation, and final diagnosis. Statistical analyses were performed. Among the 3455 samples received, 2975 were analyzed. Nephrotic syndrome (39%) was the most common cause of biopsy, followed by subnephrotic proteinuria (18%), hematuria in association with proteinuria (15%), renal failure (9%), isolated hematuria (6%), and lupus nephritis (LN) (4%). The most common diagnoses were membranous glomerulonephritis (17.9%), focal segmental glomerulosclerosis (FSGS) (15.9%), LN (13.7%), minimal histopathological findings (unsampled FSGS vs. minimal change disease, 12.1%), Immunoglobin A nephropathy (IgAN) (6.5%) and Alport syndrome (6.1%). NS and proteinuria were the most common indications for a kidney biopsy. IgAN and LN were the most common causes of primary and secondary glomerulonephritis, presenting with hematuria and proteinuria, respectively. Although membranous glomerulonephritis was the most common disease, it has been replaced by FSGS in recent years.

Membranous nephropathy: Mechanistic insights and therapeutic perspectives

Membranous nephropathy (MN) is one of the most common causes of non-diabetic nephrotic syndrome in adults. About 80% of cases are renal limited (primary MN) and 20% are associated with other systemic diseases or exposures (secondary MN). Autoimmune reaction is the main pathogenic factor of MN, and the discovery of autoantigens including the phospholipase A₂ receptor and thrombospondin type-1 domain-containing protein 7A has led to new insights into the pathogenesis, they can induce humoral immune responses led by IgG₄ makes them suitable for the diagnosis and monitoring of MN. In addition, complement activation, genetic susceptibility genes and environmental pollution are also involved in MN immune response. In clinical practice, due to the spontaneous remission of MN, the combination of supportive therapy and pharmacological treatment is widely used. Immunosuppressive drugs are the cornerstone of MN treatment, and the dangers and benefits of this approach vary from person to person. In summary, this review provides a more comprehensive review of the immune pathogenesis, interventions and unresolved issues of MN in the hope of providing some new ideas for clinical and scientific researchers in the treatment of MN.

The efficacy and safety of Sanqi Qushi Granule in patients with idiopathic membranous nephropathy --protocol of a multicenter, randomized control trial (SQ-AUTUMN)

BACKGROUND

Adult nephropathy is mainly caused by idiopathic membranous nephropathy (IMN). In cases of proteinuria, Modified Ponticelli Regimens (MPR) are often successful. However, it can cause adverse side effects. Oral Sanqi Qushi Granule (SQG) with MPR is effective in patients with IMN. However, whether it can improve the remission rate of IMN and shorten the remission time is unknown. In this trial, SQG with MPR on IMN will be evaluated clinically for its efficacy and safety.

METHODS

We will randomly assign IMN patients who meet the criteria to receives SQG plus cyclical Cyclophosphamide (CTX)/steroids or with placebo plus cyclical CTX/steroids for 6 months. A 12-month follow-up will be conducted on them. Status of remission will be used to assess treatment efficacy.

DISCUSSION

This study aims to appraise whether treatment with SQG plus cyclical CTX/steroids is superior to placebo plus cyclical CTX/steroids in the remission rate of patients with adult IMN. Adverse events of SQG plus MPR will be also evaluated for further researches about Chinese Medicine and MPR on whether it can improve the remission rate of IMN in half a year and shorten the remission time and relieve adverse effects will also be clarified.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200061953 . Registered on 13 July 2022.

Serum metabolomics analysis reveals metabolite profile and key biomarkers of idiopathic membranous nephropathy

Background

Idiopathic membranous nephropathy (IMN) is an organ-specific autoimmune disease with multiple and complex pathogenic mechanisms. Currently, renal biopsy is considered the gold standard for diagnosing membranous nephropathy. However, there were limitations to the renal puncture biopsy, such as the relatively high cost, longer time consuming, and the risk of invasive procedures. We investigated the profile of serum metabolites in IMN patients based on the UHPLC-QE-MS metabolomics technique for exploring the potential disease biomarkers and clinical implementation.

Methods

In our research, we collected serum samples from healthy control (n = 15) and IMN patients (n = 25) to perform metabolomics analysis based on the UHPLC-QE-MS technique.

Result

We identified 215 differentially expressed metabolites (DEMs) between the IMN and healthy control (HC) groups. Furthermore, these DEMs were significantly identified in histidine metabolism, arginine and proline metabolism, pyrimidine metabolism, purine metabolism, and steroid hormone biosynthesis. Several key DEMs were significantly correlated with the level of clinical parameters, such as serum albumin, IgG, UTP, and cholesterol. Among them, dehydroepiandrosterone sulfate (DHEAS) was considered the reliable diagnostic biomarker in the IMN group. There was an increased abundance of actinobacteria, phylum proteobacteria, and class gammaproteobacterial in IMN patients for host-microbiome origin analysis.

Conclusion

Our study revealed the profiles of DEMs from the IMN and HC groups. The result demonstrated that there were disorders of amino acids, nucleotides, and steroids hormones metabolism in IMN patients. The down-regulation of DHEAS may be associated with the imbalance of the immune environment in IMN patients. In host-microbiome origin analysis, the gut microbiota and metabolite disturbances were present in IMN patients.

Comparative analysis of the efficacy of different treatments for idiopathic membranous nephropathy: a retrospectively real-world study

BACKGROUND

This study aimed to explore the clinical efficacy of different treatment regimens for idiopathic membranous nephropathy (IMN).

METHODS

Patients with IMN were retrospectively analyzed by dividing into two groups: glucocorticoids combined with cyclophosphamide group (GC + CYC) and glucocorticoids combined with calcineurin inhibitor group (GC + CNIs). After 1 year of treatment, those who found that the initial treatment was not effective were switched to another regimen. Patients continued to be followed up for at least 1 year to observe the treatment effects of different treatment regimens.

RESULTS

This study found that the rate of complete and partial remission (CR + PR) in the GC + CYC and GC + CNIs groups was 76.19 vs. 82.63% after 1 year of follow-up (p > .05). In the GC + CYC and GC + CNIs groups, 27.78 and 11.95% of the patients switched treatment regimens, respectively. After 2 years of follow-up, the CR + PR rate was significantly higher in the change to GC + CNIs group after the switch compared to before the switch (80.00 vs. 31.43%, p < .001). It was also significantly higher in the change to GC + CYC group compared to before the switch (68.42 vs. 31.58%, p = .023). The recurrence rate was significantly higher in the maintain GC + CNIs and change to GC + CNIs groups than in the maintain GC + CYC and change to GC + CYC groups (25.14 vs 6.36%, p < .001). The disengagement rate from immunotherapy was significantly higher in the maintain GC + CYC group and the change to GC + CYC group than in the maintain GC + CNIs group and the change to GC + CNIs group (76.36% vs 29.71%, p < .001). High titer of anti-phospholipase A2 receptor (anti-PLA2R) antibody (95%CI: 0.199-0.947, p = .036) and serum C3 (95%CI: 0.030-0.570, p = .007) were independent risk factors, while serum IgG (95%CI: 1.000-1.331, p = .050) was a favorable factor for achieving CR. Anti-PLA2R antibody was the independent risk factor that affected the worse renal condition (p = .023).

CONCLUSIONS

Timely change of treatment regimen can significantly enhance therapeutic effect. Compared with patients administered with CYC, those administered with CNIs were less likely to leave treatment and had a higher recurrence rate.

From KDIGO 2012 towards KDIGO 2021 in idiopathic membranous nephropathy guidelines: what has changed over the last 10 years?

The recommendations in the Kidney Disease: Improving Global Outcomes (KDIGO) 2021 guidelines regarding Idiopathic Membranous Nephropathy (IMN) management include significant changes as compared to those published in 2012. According to the recent guidelines, a biopsy is not always needed for IMN diagnosis; since diagnosis can be allowed for by the detection of circulating antibodies against the M-type transmembrane phospholipase A2 receptor (anti-PLA2R). Moreover, alterations in anti-PLA2R concentrations, along with other serum and urinary markers, may guide further follow-up. The findings of numerous recent studies which compared different immunosuppressive treatments resulted in substantial changes in treatment indications in the KDIGO 2021 guidelines, suggesting the stratification of patients into four risk categories. The definition of resistant cases and relapses was likewise modified. All the above will lead to a more granular and personalized approach, whose results need to be tested over time. In this commentary, we discuss the changes in the 2012 and 2021 guidelines, adding information from the most recent literature.

Discovery of seven novel putative antigens in membranous nephropathy and membranous lupus nephritis identified by mass spectrometry

Multiple autoantigens have been identified in membranous nephropathy (MN) by tissue-based proteomics. However, antigenic targets of disease are unknown for over 10% of patients with MN and over half of those with membranous lupus nephritis (MLN). Here, we identified multiple new targets in PLA2R-/THSD7A-/EXT-/NELL1-quadruple negative MN biopsies through mass spectrometry of immune complexes recovered from biopsy tissue of patients with MN. Patients with MN negative for these four antigens were identified from Arkana Laboratories case archives. Protein G immunoprecipitation recovered immune complexes from frozen biopsy tissue from 142 quadruple-negative cases and 278 cases of known antigen type, followed by interrogation by mass spectrometry. Potential putative antigens were confirmed through paraffin immunofluorescence and co-localization with IgG within immune deposits. Consecutive series of 165 cases of PLA2R-negative MN and 142 MLN biopsies were screened to determine the frequency for each potential antigen. Seven putative antigens were discovered within immune complexes from biopsies of patients with MN including FCN3, CD206, EEA1, SEZ6L2, NPR3, MST1, and VASN. Peptides from these proteins were not enriched in the 278 cases of known antigen type. Between three to 30 unique peptides were detected for each new target. Frequencies of each biomarker, determined by staining consecutive case series, ranged from under 1 to 4.9%. NPR3 and CD206 were only positive in index cases. All cases showed co-localization of IgG within the immune deposits. Thus, seven putative antigens were newly identified in MN and MLN. Due to the number of antigens identified, it is becoming impractical to type PLA2R-negative MN or MLN cases through immunostaining alone. A multiplex approach is needed for subtyping of these diseases.

Rapid diagnosis of membranous nephropathy based on serum and urine Raman spectroscopy combined with deep learning methods

Membranous nephropathy is the main cause of nephrotic syndrome, which has an insidious onset and may progress to end-stage renal disease with a high mortality rate, such as renal failure and uremia. At present, the diagnosis of membranous nephropathy mainly relies on the clinical manifestations of patients and pathological examination of kidney biopsy, which are expensive, time-consuming, and have certain chance and other disadvantages. Therefore, there is an urgent need to find a rapid, accurate and non-invasive diagnostic technique for the diagnosis of membranous nephropathy. In this study, Raman spectra of serum and urine were combined with deep learning methods to diagnose membranous nephropathy. After baseline correction and smoothing of the data, Gaussian white noise of different decibels was added to the training set for data amplification, and the amplified data were imported into ResNet, AlexNet and GoogleNet models to obtain the evaluation results of the models for membranous nephropathy. The experimental results showed that the three deep learning models achieved an accuracy of 1 for the classification of serum data of patients with membranous nephropathy and control group, and the discrimination of urine data was above 0.85, among which AlexNet was the best classification model for both samples. The above experimental results illustrate the great potential of serum- and urine-based Raman spectroscopy combined with deep learning methods for rapid and accurate identification of patients with membranous nephropathy.

Computer-aided diagnosis of primary membranous nephropathy using expert system

BACKGROUND

The diagnosis of primary membranous nephropathy (PMN) often depends on invasive renal biopsy, and the diagnosis based on clinical manifestations and target antigens may not be completely reliable as it could be affected by uncertain factors. Moreover, different experts could even have different diagnosis results due to their different experiences, which could further impact the reliability of the diagnosis. Therefore, how to properly integrate the knowledge of different experts to provide more reliable and comprehensive PMN diagnosis has become an urgent issue.

METHODS

This paper develops a belief rule-based system for PMN diagnosis. The belief rule base is constructed based on the knowledge of the experts, with 9 biochemical indicators selected as the input variables. The belief rule-based system is developed of three layers: (1) input layer; (2) belief rule base layer; and (3) output layer, where 9 biochemical indicators are selected as the input variables and the diagnosis result is provided as the conclusion. The belief rule base layer is constructed based on the knowledge of the experts. The final validation was held with gold pattern clinical cases, i.e., with known and clinically confirmed diagnoses.

RESULTS

134 patients are used in this study, and the proposed method is defined by its sensitivity, specificity, accuracy and area under curve (AUC), which are 98.0%, 96.9%, 97.8% and 0.93, respectively. The results of this study present a novel and effective way for PMN diagnosis without the requirement of renal biopsy.

CONCLUSIONS

Through analysis of the diagnosis results and comparisons with other methods, it can be concluded that the developed system could help diagnose PMN based on biochemical indicators with relatively high accuracy.

A Genetic Risk Score Distinguishes Different Types of Autoantibody-Mediated Membranous Nephropathy

Introduction

Membranous nephropathy (MN) is the leading cause of nephrotic syndrome in adults and is characterized by detectable autoantibodies against glomerular antigens, most commonly phospholipase A2 receptor 1 (PLA2R1) and thrombospondin type-1 domain containing 7A (THSD7A). In Europeans, genetic variation in at least five loci, PLA2R1, HLA-DRB1, HLA-DQA1, IRF4, and NFKB1, affects the risk of disease. Here, we investigated the genetic risk differences between different autoantibody states.

Methods

1,409 MN individuals were genotyped genome-wide with a dense SNV array. The genetic risk score (GRS) was calculated utilizing the previously identified European MN loci, and results were compared with 4,929 healthy controls and 422 individuals with steroid-sensitive nephrotic syndrome.

Results

GRS was calculated in the 759 MN individuals in whom antibody status was known. The GRS for MN was elevated in the anti-PLA2R1 antibody-positive (N = 372) compared with both the unaffected control (N = 4,929) and anti-THSD7A-positive (N = 31) groups (p < 0.0001 for both comparisons), suggesting that this GRS reflects anti-PLA2R1 MN. Among PLA2R1-positive patients, GRS was inversely correlated with age of disease onset (p = 0.009). Further, the GRS in the dual antibody-negative group (N = 355) was intermediate between controls and the PLA2R1-positive group (p < 0.0001).

Conclusion

We demonstrate that the genetic risk factors for PLA2R1- and THSD7A-antibody-associated MN are different. A higher GRS is associated with younger age of onset of disease. Further, a proportion of antibody-negative MN cases have an elevated GRS similar to PLA2R1-positive disease. This suggests that in some individuals with negative serology the disease is driven by autoimmunity against PLA2R1.

Multi-Scale Investigation of Human Renal Tissue in Three Dimensions

Histopathology as a diagnostic mainstay for tissue evaluation is strictly a 2D technology. Combining and supplementing this technology with 3D imaging has been proposed as one future avenue towards refining comprehensive tissue analysis. To this end, we have developed a laboratory-based X-ray method allowing for the investigation of tissue samples in three dimensions with isotropic volume information. To assess the potential of our method for micro-morphology evaluation, we selected several kidney regions from three patients with cystic kidney disease, obstructive nephropathy and diabetic glomerulopathy. Tissue specimens were processed using our in-house-developed X-ray eosin stain and investigated with a commercial microCT and our in-house-built NanoCT. The microCT system provided overview scans with voxel sizes of [Formula: see text] and the NanoCT was employed for higher resolutions including voxel sizes from [Formula: see text] to 210 nm. We present a methodology allowing for a precise micro-morphologic investigation in three dimensions which is compatible with conventional histology. Advantages of our methodology are its versatility with respect to multi-scale investigations, being laboratory-based, allowing for non-destructive imaging and providing isotropic volume information. We believe, that after future developmental work this method might contribute to advanced multi-modal tissue diagnostics.

Yi Shen An, a Chinese traditional prescription, ameliorates membranous glomerulonephritis induced by cationic bovine serum albumin in rats

CONTEXT

Yi Shen An (YSA) is an investigational composite of traditional Chinese medicine (Reference: 2010L000974) for the treatment of renal disease.

OBJECTIVE

To investigate the protective effects of YSA against membranous glomerulonephritis (MGN).

MATERIALS AND METHODS

Male Sprague-Dawley rats were injected with cationic bovine serum albumin (C-BSA) to create a model of MGN. Then, rats were orally treated with YSA at doses of 0.25, 0.5, 1 and 2 g/kg for 35 successive days; prednisone (5 mg/kg) was used as a positive control. At the end of the experimental period, we performed a series of tests, including 24 h urinary protein, and biochemical, immunological, antioxidative, coagulation indices, and histopathological examination.

RESULTS

YSA-1 g/kg significantly lowered urinary protein from 68.37 to 30.74 mg (p < 0.01). Meantime, total protein (TP) and albumin (ALB) recovered from 66.26 and 20.51 g/L to 76.08 and 35.64 g/L (p < 0.01), respectively. YSA removed the deposition of immunoglobulin G (IgG) and complement 3c (C3c), prevented inter-capillary cell hyperplasia on the glomerular basement membrane (GBM), and reduced electron-dense deposits and fusion of podocytes. In addition, serum IgG and superoxide dismutase were significantly elevated. In contrast, malondialdehyde, total cholesterol, triglyceride, circulating immune complex (CIC), and immunoglobulin M decreased in the YSA-treated group. Moreover, the blood coagulation dysfunction was adjusted.

DISCUSSION AND CONCLUSIONS

These findings indicate YSA may exert a therapeutic effect against MGN through the inhibition of CIC formation, and the removal of IgG and C3c deposition from the GBM, thus supporting the development of further clinical trials.

Rituximab in patients with membranous nephropathy and kidney insufficiency

Introduction: Patients with membranous nephropathy and kidney insufficiency have an extremely high risk of progression to end-stage renal disease. Whether rituximab can effectively treat membranous nephropathy patients with renal dysfunction remains unknown at present. The aim of our study was to evaluate the effectiveness and safety of rituximab (RTX) in membranous nephropathy with kidney insufficiency.

Methods: We retrospectively analyzed the clinical data of 35 membranous nephropathy patients with kidney insufficiency administered in the First Affiliated Hospital of Zhengzhou University between January 2020 and December 2021. Patients were followed every 1–3 months for a total of 6 months. Clinical data were collected including anti-phospholipase A2 receptor antibody (anti-PLA2R antibody) quantification, 24-h urinary protein, serum albumin, and serum creatinine. The percentage of patients who achieved clinical remission was measured.

Results: There were 7 (20%) patients who achieved complete or partial response at 6 months after RTX treatment. After 6 months of treatment, patients were clinically improved as evidenced by significant improvements in anti- PLA2R antibody titer [7.70 (5.72, 16.72) vs. 59.20 (17.70, 187.50) RU/ml, p < 0.001], 24-h urine protein [7.04 (4.43, 8.90) vs. 10.15 (4.83, 13.57) g/d, p < 0.001], serum albumin [30.55 (24.97, 33.27) vs. 21.40 (16.75, 25.00)g/L, p < 0.001], serum creatinine [99.50 (75.25, 140.25) vs. 152.00 (134.50, 232.50) µmol/L, p = 0.022], and estimated glomerular filtration rate (eGFR) [78.29 (50.15, 101.55) vs. 41.12 (26.53, 51.41) ml/min/1.73 m², p = 0.045]. There were no significantly differences between responders and nonresponders in the baseline levels of anti-PLA2R antibodies, proteinuria, serum albumin, and renal function. After the RTX treatment, anti-PLA2R antibodies turned negative in all responders, but the antibody level persisted maintained positive in all but 5 nonresponders. The patients who achieved response maintained a stable kidney function during the study period, with eGFR 29.03 (28.76, 35.07) ml/min/1.73 m² before rituximab treatment and 62.73 (62.34, 63.13) ml/min/1.73 m² at the end of follow-up (p = 0.053).

Conclusion: RTX therapy might be an alternative treatment in reducing proteinuria and maintaining stable renal function among membranous nephropathy patients even with kidney insufficiency.

Discovery of anti-Formin-like 1 protein (FMNL1) antibodies in membranous nephropathy and other glomerular diseases

Evidence has shown that podocyte-directed autoantibodies can cause membranous nephropathy (MN). In the present work we investigated sera of MN patients using a high-density peptide array covering the whole coding sequences of the human genome encompassing 7,499,126 tiled peptides. A panel of 21 proteins reactive to MN sera were identified. We focused our attention on Formin-like 1 (FMNL1), a protein expressed by macrophages in MN patients tissues. High levels of anti-FMNL1 IgG4 were demonstrated in sera of MN patients with an orthogonal methodology (ELISA) contemporary demonstrating FMNL1 positive cells in kidney co-staining with CD68 in glomeruli. High levels of circulating anti-FMNL1 IgG4 were associated with lack of remission of proteinuria, potentially indicating that autoantibodies directed against cells other than podocytes, involved in tissue repair, might play a role in MN disease progression. High serum levels of anti-FMNL1 IgGs were also observed in other non-autoimmune glomerolonephrites, i.e. idiopathic and genetic FSGS, IgAGN. These findings are suggestive of a broader role of those autoantibodies in other glomerular disease conditions.

Intrarenal Single-Cell Sequencing of Hepatitis B Virus Associated Membranous Nephropathy

To date, the pathogenesis of hepatitis B virus (HBV)-associated membranous nephropathy (MN) remains elusive. This study aimed to decipher the etiopathogenesis of HBV-associated MN by performing single-cell RNA sequencing (scRNA-seq) of kidney biopsy specimens from a patient with HBV-associated MN and two healthy individuals. We generated 4,114 intrarenal single-cell transcriptomes from the HBV-associated MN patient by scRNA-seq. Compared to healthy individuals, podocytes in the HBV-associated MN patient showed an increased expression of extracellular matrix formation-related genes, including HSPA5, CTGF, and EDIL3. Kidney endothelial cells (ECs) in the HBV-associated MN were enriched in inflammatory pathways, including NF-kappa B signaling, IL-17 signaling, TNF signaling and NOD-like receptor signaling. Gene ontology (GO) functional enrichment analysis and Gene Set Variation Analysis (GSVA) further revealed that differentially expressed genes (DEGs) of ECs from the HBV-associated MN patients were enriched in apoptotic signaling pathway, response to cytokine and leukocyte cell-cell adhesion. The up-regulated DEGs in glomerular ECs of HBV-associated MN patients were involved in biological processes such as viral gene expression, and protein targeting to endoplasmic reticulum. We further verified that the overexpressed genes in ECs from HBV-associated MN were mainly enriched in regulation of protein targeting to endoplasmic reticulum, exocytosis, viral gene expression, IL-6 and IL-1 secretion when compared with anti-phospholipase A2 receptor (PLA2R)-positive idiopathic membranous nephropathy (IMN). The receptor-ligand crosstalk analysis revealed potential interactions between endothelial cells and other cells in HBV-associated-MN. These results offer new insight into the pathogenesis of HBV-associated MN and may identify new therapeutic targets for HBV-associated MN.

Multi-scale attention network for segmentation of electron dense deposits in glomerular microscopic images

Electron dense deposit on the epithelial side of the glomerular capillary basement membrane is one of the pathological changes of membranous nephropathy. Automatic segmentation of deposits can relieve clinicians from the tedious and manual effort of identifying and localizing region of interest (ROI) in medical images and also assist to diagnose membranous nephropathy. Electron dense deposits are characterized by different sizes, irregular shapes, and low contrast to surrounding tissue structures in glomerular electron microscopy images. Considering the characteristics of dense deposits, we propose a multi-scale attention network for automatic segmentation of electron dense deposits of glomeruli in electron microscope images. Our method is built on the fully convolutional network but also takes advantages of the multi-scale skip connections and attention mechanism. Specifically, the multi-scale skip connection combines feature maps of different scales, makes the segmentation field larger, and integrates the shallow features of the image and high-level semantic information, which is more conducive to distinguishing dense deposits. At the same time, attention mechanism can focus on salient structures that normally produces a distinguishable feature representation. To evaluate the segmentation performance of the proposed method, we also collected a dataset of electron microscope images of membranous nephropathy. To the best of our knowledge, this is the largest image dataset for segmentation of glomerular basement membrane dense deposits. Experimental result shows that our model can accurately segment ordinary-sized dense deposits. Compared with state-of-the-art methods, our proposed method lower both false positive and false negative segmentation of small-sized protein sediments.

The Association Between Serum Complement 4 and Kidney Disease Progression in Idiopathic Membranous Nephropathy: A Multicenter Retrospective Cohort Study

Introduction

Complement system plays an important role in the pathogenesis of idiopathic membranous nephropathy (IMN), however, the relationship between serum complement 4 (C4) and kidney disease progression in IMN is unclear. This study aims to investigate the association of serum C4 level with the risk of kidney disease progression among patients with IMN.

Methods

The retrospective cohort assessed 1,254 participants with biopsy-proven IMN from three centers in Xi ‘an, Shaanxi Province, China. Baseline serum C4 levels were measured at renal biopsy. The association between baseline serum C4 and the risk of renal function progression, defined as a 30% decline in renal function or end stage renal disease, was evaluated in Cox proportional hazards models.

Results

A total of 328 patients with IMN and nephrotic proteinuria were eligible, and 11.3% (37/328) of them attained the renal function progression events after a median follow-up of 51 months (37-59 months). After adjustment for other confounders, a higher value of serum C4 was independently associated with a higher risk of renal function progression event with a hazard ratio (HR) of 4.76 (95% confidence interval [95% CI], 1.77-12.79) per natural log-transformed C4. In reference to the low level of C4, the adjusted HRs were 2.72 (95% CI, 1.02-7.24) and 3.65 (95% CI, 1.39-9.60), respectively, for the median and high levels of C4 (P for trend=0.008). Additionally, the results were robust and reliable in the sensitivity and subgroup analyses.

Conclusion

Among patients with IMN and nephrotic proteinuria, serum C4 at renal biopsy is an independent predictor for kidney disease progression regardless of other confounders.

The Role of Anti-PLA2R and Anti-THSD7A Antibodies in the Pathogenesis and Diagnostics of Primary Membranous Nephropathy: A Review of Current Knowledge for Clinical Practice

Primary membranous nephropathy (PMN) is considered a major cause of nephrotic syndrome. The discovery of circulating autoantibodies directed against glomerular podocytes helped to classify them as autoimmune diseases. Over the past years, there has been an increasing significance of anti-Phospholipase A2 Receptor (anti-PLA₂R), which has been detected in 70–80% of PMN cases, and relevance of anti-Thrombospondin type I domain-containing 7A (anti-THSD7A) even though they are present in 2–5% of patients. The results of clinical and experimental studies indicate that these antibodies are pathogenic. It radically changed the diagnostic and therapeutic approach. Measurement of antibody titers in the serum seems to be a valuable tool for identifying PMN and for the assessment of disease activity. By monitoring pathogenic antibodies levels rather than proteinuria or reduced glomerular filtration rate (GFR) as an indicator of glomerular disease, physicians would easier divide patients into those with active and inactive PMN disease and decide about their therapy. The aim of this review is to evaluate scientific evidence about the role of autoantibodies, namely anti-PLA₂R and anti-THSD7A, as PMN biomarkers. The present manuscript focuses on PMN pathogenesis and key data of diagnosis, monitoring of the disease, and treatment strategies that are currently being used in clinical practice.

Ocular manifestations and full house membranous nephropathy as a rare presentation of secondary syphilis

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Ocular symptoms and membranous nephropathy as a presentation of secondary syphilis.

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Secondary syphilis presenting with a full house staining pattern on renal biopsy.

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Diagnostic challenge with positive autoimmune labs confounding the diagnosis.

Syphilis is an often-overlooked diagnosis and without timely diagnosis and treatment, can have serious repercussions. Although its prevalence had decreased with the introduction of penicillin, it has had a resurgence over the years. Discerning the proper patient population to test for syphilis should be led by a patient’s risk factors. Here, we present a patient diagnosed with secondary syphilis, with initial concern for a possible concomitant lupus diagnosis. He initially presented with visual symptoms and optic nerve inflammation, along with a positive antinuclear antibody (ANA). Due to an unprotected sexual encounter, there was suspicion for a sexually transmitted infection. Testing revealed reactive rapid plasma reagin (RPR) (≥1:256 titer) and reactive treponemal antibody, consistent with active syphilis. He was immediately started on intravenous Penicillin G. Lumbar puncture was consistent with a reactive venereal disease research laboratory test (VDRL). Urinalysis revealed nephrotic range proteinuria, which along with the positive ANA, prompted renal biopsy. This showed membranous nephropathy with full house staining, which is seen primarily in lupus nephritis and further confounded the diagnosis. He completed a two-week course of penicillin and steroids inpatient with clinical improvement. On follow up, his RPR improved (≥1:64 titer), and lumbar puncture showed a non-reactive VDRL. Due to the resolution of proteinuria, decrease of the ANA titer and no further positive testing or symptoms convincing for a concomitant rheumatologic disorder, the presence of lupus was collectively determined to be of low concern. and the sole diagnosis of secondary syphilis was made.

Revisiting immunological and clinical aspects of membranous nephropathy

Idiopathic or primary membranous nephropathy (IMN) is one of the most frequent causes of nephrotic syndrome in adults and the elderly. It is characterized by a thickening of the wall of the glomerular capillaries due to the presence of immune complex deposits. 85% of membranous nephropathy cases are classified as primary or idiopathic (IMN). The rest are of secondary origin (SMN), caused by autoimmune conditions or malignant tumors as lung cancer, colon and melanomas. It is an organ-specific autoimmune disease in which the complement system plays an important role with the formation of the membrane attack complex (MAC; C5b-9), which produces an alteration of the podocyte structure. The antigen responsible for 70-80% of IMN is a podocyte protein called M-type phospholipase A2 receptor (PLA2R). More recently, another podocyte antigen has been identified, the "Thrombospondin type-1 domain-containing 7A" (THSD7A), which is responsible for 10% of the cases of negative IMN for anti- PLA2R.

Renal autoimmunity: The role of bacterial and viral infections, an extensive review

Autoimmunity is a process by which the loss of self-tolerance results in an immune attack against the body own tissues and organs. For autoimmunity to occur, various elements serving as triggers were described by which infections are considered one of the leading factors. In turn, renal involvement in autoimmune diseases, whether by an organ-specific attack, or as part of a systemic disease process, is well known. As bacterial and viral infections are considered to be common triggers for autoimmunity in general, we aimed to study their association with renal autoimmunity in particular. We performed an extensive search of the recent and relevant medical literature regarding renal autoimmunity syndromes such as infection-associated glomerulonephritis and vasculitis, associated with bacterial and viral infections. By utilizing PubMed and Google Scholar search engines, over 200 articles and case reports were reviewed. Among other mechanisms, direct infection of the renal parenchyma, molecular mimicry, induction of B-cells or secretion of superantigens, bacterial and viral pathogens were found to correlate with the development of renal autoimmunity. Nevertheless, this was not true for all pathogens, as some mimic autoimmune diseases and others show a surprisingly protective effect. The exact immunopathogenesis is yet to be determined, however. For conclusion, bacterial and viral infections are linked to renal autoimmunity by both direct damage and as mediators of systemic diseases. Further research particularly on the immunopathogenetic mechanisms of renal autoimmunity associated with infections is required.

Efficacy and safety of tripterygium wilfordii multiglycosides in idiopathic membranous nephropathy: Protocol for an open-label randomized controlled clinical trial

OBJECTIVE

Tripterygium wilfordii multiglycosides has been demonstrated to be effective in reducing proteinuria and alleviate edema in patients with chronic kidney disease. We aim to evaluate its efficacy and safety in idiopathic membranous nephropathy.

METHODS AND ANALYSIS

This is an randomized, open-labeled, controlled clinical trial. Twenty eligible patients with idiopathic membranous nephropathy will be randomly assigned into the intervention group and the control group at a rate of 1:1. Patients in the intervention group will receive tripterygium wilfordii multiglycosides tablets (1-1.5 mg/kg body weight/d, orally) in addition to the original treatment of angiotensin converting enzyme inhibitor/angiotensin receptor blocker, while the control group will continue with the original treatment of angiotensin converting enzyme inhibitor/angiotensin receptor blocker. The treatment course is 6 months, and clinical variables of patients will be measured at baseline and each monthly follow-up. The primary efficacy outcome measure is absolute decrease in urinary protein quantity after 6 months of treatment compared with baseline at randomization. The secondary efficacy outcome measures include absolute decrease in urine albumin-creatinine ratio in spot urine after 6 months of treatment compared with baseline at randomization, the percentage of patients who reached effective clinical response, and the percentage of patients who developed composite renal endpoint. Safety outcome measures include incidence of adverse events, incidence of serious adverse events, and death.

MicroRNAs: Potential mediators between particulate matter 2.5 and Th17/Treg immune disorder in primary membranous nephropathy

Primary membranous nephropathy (PMN), is an autoimmune glomerular disease and the main reason of nephrotic syndrome in adults. Studies have confirmed that the incidence of PMN increases yearly and is related to fine air pollutants particulate matter 2.5 (PM2.5) exposure. These imply that PM2.5 may be associated with exposure to PMN-specific autoantigens, such as the M-type receptor for secretory phospholipase A2 (PLA2R1). Emerging evidence indicates that Th17/Treg turns to imbalance under PM2.5 exposure, but the molecular mechanism of this process in PMN has not been elucidated. As an important indicator of immune activity in multiple diseases, Th17/Treg immune balance is sensitive to antigens and cellular microenvironment changes. These immune pathways play an essential role in the disease progression of PMN. Also, microRNAs (miRNAs) are susceptible to external environmental stimulation and play link role between the environment and immunity. The contribution of PM2.5 to PMN may induce Th17/Treg imbalance through miRNAs and then produce epigenetic affection. We summarize the pathways by which PM2.5 interferes with Th17/Treg immune balance and attempt to explore the intermediary roles of miRNAs, with a particular focus on the changes in PMN. Meanwhile, the mechanism of PM2.5 promoting PLA2R1 exposure is discussed. This review aims to clarify the potential mechanism of PM2.5 on the pathogenesis and progression of PMN and provide new insights for the prevention and treatment of the disease.

The optimal anti-phospholipase A2 receptor cutoff for the diagnosis of idiopathic membranous nephropathy: a single-center retrospective study

BACKGROUND/AIMS

Anti-phospholipase A2 receptor (PLA2R) autoantibody is the main biomarker of idiopathic membranous nephropathy (IMN). We aimed to find a new cutoff value of anti-PLA2R for patients with IMN and to explore the relevance between this antibody and baseline clinical parameters.

METHODS

A total of 670 subjects including 374 IMN cases and 296 non-IMN controls were included between January 2017 and January 2020. All clinical parameters were collected at the time of renal biopsy. The levels of anti-PLA2R were detected by a commercial enzyme-linked immunosorbent assay (ELISA) kit. The optimal cutoff value was calculated by a receiver operating characteristic curve and compared in diagnostic efficiency.

RESULTS

The optimal cutoff value of anti-PLA2R for IMN was 7.45 RU/mL with the highest Youden index, and the corresponding sensitivity, specificity, positive predictive value and negative predictive value were 80.75%, 97.97%, 98.05% and 80.11%, respectively. Anti-PLA2R levels in IMN patients demonstrated a significant positive correlation with serum creatinine and 24-hour urinary protein, while they showed a negative correlation with serum albumin and estimated glomerular filtration rate.

CONCLUSION

The recommended cutoff value of anti-PLA2R is 7.45 RU/mL using ELISA detection for distinguishing IMN from non-IMN nephropathy. The level of anti-PLA2R is related to baseline renal function in IMN. This new threshold can improve the diagnostic efficiency and facilitate early diagnosis of IMN.

Immunosuppressive treatment for primary membranous nephropathy in adults with nephrotic syndrome

BACKGROUND

Primary membranous nephropathy (PMN) is a common cause of nephrotic syndrome in adults. Without treatment, approximately 30% of patients will experience spontaneous remission and one third will have persistent proteinuria. Approximately one-third of patients progress toward end-stage kidney disease (ESKD) within 10 years. Immunosuppressive treatment aims to protect kidney function and is recommended for patients who do not show improvement of proteinuria by supportive therapy, and for patients with severe nephrotic syndrome at presentation due to the high risk of developing ESKD. The efficacy and safety of different immunosuppressive regimens are unclear. This is an update of a Cochrane review, first published in 2004 and updated in 2013.

OBJECTIVES

The aim was to evaluate the safety and efficacy of different immunosuppressive treatments for adult patients with PMN and nephrotic syndrome.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 1 April 2021 with support from the Cochrane Kidney and Transplant Information Specialist using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) investigating effects of immunosuppression in adults with PMN and nephrotic syndrome were included.

DATA COLLECTION AND ANALYSIS

Study selection, data extraction, quality assessment, and data synthesis were performed using Cochrane-recommended methods. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Sixty-five studies (3807 patients) were included. Most studies exhibited a high risk of bias for the domains, blinding of study personnel, participants and outcome assessors, and most studies were judged unclear for randomisation sequence generation and allocation concealment. Immunosuppressive treatment versus placebo/no treatment/non-immunosuppressive treatment In moderate certainty evidence, immunosuppressive treatment probably makes little or no difference to death, probably reduces the overall risk of ESKD (16 studies, 944 participants: RR 0.59, 95% CI 0.35 to 0.99; I² = 22%), probably increases total remission (complete and partial) (6 studies, 879 participants: RR 1.44, 95% CI 1.05 to 1.97; I² = 73%) and complete remission (16 studies, 879 participants: RR 1.70, 95% CI 1.05 to 2.75; I² = 43%), and probably decreases the number with doubling of serum creatinine (SCr) (9 studies, 447 participants: RR 0.46, 95% CI 0.26 to 0.80; I² = 21%). However, immunosuppressive treatment may increase the number of patients relapsing after complete or partial remission (3 studies, 148 participants): RR 1.73, 95% CI 1.05 to 2.86; I² = 0%) and may lead to a greater number experiencing temporary or permanent discontinuation/hospitalisation due to adverse events (18 studies, 927 participants: RR 5.33, 95% CI 2.19 to 12.98; I² = 0%). Immunosuppressive treatment has uncertain effects on infection and malignancy. Oral alkylating agents with or without steroids versus placebo/no treatment/steroids Oral alkylating agents with or without steroids had uncertain effects on death but may reduce the overall risk of ESKD (9 studies, 537 participants: RR 0.42, 95% CI 0.24 to 0.74; I² = 0%; low certainty evidence). Total (9 studies, 468 participants: RR 1.37, 95% CI 1.04 to 1.82; I² = 70%) and complete remission (8 studies, 432 participants: RR 2.12, 95% CI 1.33 to 3.38; I² = 37%) may increase, but had uncertain effects on the number of patients relapsing, and decreasing the number with doubling of SCr. Alkylating agents may be associated with a higher rate of adverse events leading to discontinuation or hospitalisation (8 studies 439 participants: RR 6.82, 95% CI 2.24 to 20.71; I² = 0%). Oral alkylating agents with or without steroids had uncertain effects on infection and malignancy. Calcineurin inhibitors (CNI) with or without steroids versus placebo/no treatment/supportive therapy/steroids We are uncertain whether CNI with or without steroids increased or decreased the risk of death or ESKD, increased or decreased total or complete remission, or reduced relapse after complete or partial remission (low to very low certainty evidence). CNI also had uncertain effects on decreasing the number with a doubling of SCr, temporary or permanent discontinuation or hospitalisation due to adverse events, infection, or malignancy. Calcineurin inhibitors (CNI) with or without steroids versus alkylating agents with or without steroids We are uncertain whether CNI with or without steroids increases or decreases the risk of death or ESKD. CNI with or without steroids may make little or no difference to total remission (10 studies, 538 participants: RR 1.01, 95% CI 0.89 to 1.15; I² = 53%; moderate certainty evidence) or complete remission (10 studies, 538 participants: RR 1.15, 95% CI 0.84 to 1.56; I² = 56%; low certainty evidence). CNI with or without steroids may increase relapse after complete or partial remission. CNI with or without steroids had uncertain effects on SCr increase, adverse events, infection, and malignancy. Other immunosuppressive treatments Other interventions included azathioprine, mizoribine, adrenocorticotropic hormone, traditional Chinese medicines, and monoclonal antibodies such as rituximab. There were insufficient data to draw conclusions on these treatments.

AUTHORS' CONCLUSIONS

This updated review strengthened the evidence that immunosuppressive therapy is probably superior to non-immunosuppressive therapy in inducing remission and reducing the number of patients that progress to ESKD. However, these benefits need to be balanced against the side effects of immunosuppressive drugs. The number of included studies with high-quality design was relatively small and most studies did not have adequate follow-up. Clinicians should inform their patients of the lack of high-quality evidence. An alkylating agent (cyclophosphamide or chlorambucil) combined with a corticosteroid regimen had short- and long-term benefits, but this was associated with a higher rate of adverse events. CNI (tacrolimus and cyclosporin) showed equivalency with alkylating agents however, the certainty of this evidence remains low. Novel immunosuppressive treatments with the biologic rituximab or use of adrenocorticotropic hormone require further investigation and validation in large and high-quality RCTs.

Increased risk for central serous chorioretinopathy in nephrotic syndrome patients: A population-based cohort study

BACKGROUND

Nephrotic syndrome (NS) is characterized by various etiologies that damage the glomerulus. Central serous chorioretinopathy (CSCR) is a retinal disease characterized by neurosensory detachment of the retina. Several case reports have described the relationship between both. Therefore, we try to analyze the epidemiological associations between NS and CSCR using the National Health Insurance Research Database in Taiwan.

METHODS

Data spanning 14 years were extracted from the National Health Insurance Research Database and sub-grouped. The variables were analyzed using Pearson's chi-squared test and Fisher's exact test. The risk factors for disease development with or without comorbidities were examined using an adjusted hazard ratio (aHR). Kaplan-Meier analysis was performed to evaluate the cumulative incidence of CSCR with or without NS.

RESULTS

A total of 14 794 patients with NS and 14 794 matched controls without NS were enrolled in this cohort study. The incidence rate of CSCR was higher in the study cohort than in the control cohort (aHR = 3.349, p < 0.001). The overall incidence of CSCR was 44.51 per 100 000 person-years in the study cohort and 33.39 per 100 000 person-years in the control cohort. In both groups, CSCR occurred more frequently in males than in females. Patients aged 40-49, 50-59, and ≥60 years in the study cohort had a significantly higher risk of developing CSCR than those in the control cohort (aHR = 3.445, 5.421, and 4.957, all p < 0.001). NS patient with a 4-week history of steroid usage has a higher risk of developing CSCR (aHR = 2.010, p < 0.001).

CONCLUSION

Our data showed that patients with NS have an increased risk of developing subsequent CSCR. Physician should routinely refer their NS patients to ophthalmologist for ophthalmic evaluation. This is the first nationwide epidemiological study reporting the association between these two diseases. Further studies are needed to clarify this relationship.

Serum complement factor B is associated with disease activity and progression of idiopathic membranous nephropathy concomitant with IgA nephropathy

PURPOSE

Few studies have reported the roles of the complement system in concomitant idiopathic membranous nephropathy and IgA nephropathy (IMN-IgAN). Complement factor B (CFB) is a crucial factor that involved in the alternative complement pathway. We aimed to evaluate the association between disease activity (eGFR, anti-PLA2R antibody levels and 24 h urinary protein excretion), progression and serum CFB levels of IMN-IgAN patients.

METHODS

In total, 39 IMN-IgAN patients (median follow-up, 46.6 months), 99 IMN patients and 92 IgAN patients participated in this study. The disease progression event was defined as end-stage renal disease (ESRD) or a 30% decline in estimated glomerular filtration rate (eGFR). The serum CFB concentration was measured by enzyme-linked immunosorbent assay.

RESULTS

Serum CFB levels were lower in IMN-IgAN patients than in patients with IgAN only (P < .001). Serum CFB levels correlated positively with serum creatinine levels, anti-PLA2R antibody levels and 24 h urinary protein excretion (P < .05). Kaplan-Meier analysis revealed that IMN-IgAN patients with high serum CFB levels had a significantly lower cumulative renal survival rate than patients with low levels (log-rank test, P = .009). Multivariate Cox regression analysis showed that high baseline serum CFB levels were significantly associated with poor renal outcome in patients with IMN-IgAN (HR: 2.727, 95% CI 1.076-6.913, P = .034).

CONCLUSION

High serum CFB levels correlated with increased serum creatinine, anti-PLA2R antibody and urinary protein excretion as well as poor renal prognosis in patients with IMN-IgAN, indicating that serum CFB may be a marker of disease activity and progression.

Label-free quantitative proteomic and phosphoproteomic analyses of renal biopsy tissues in membranous nephropathy

PURPOSE

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. However, the underlying mechanisms of its occurrence and development are not completely clear. Thus, it is essential to explore the mechanisms.

EXPERIMENTAL DESIGN

Here, we employed label-free quantification and liquid chromatography-tandem mass spectrometry analysis techniques to investigate the proteomic and phosphoproteomic alterations in renal biopsy tissues of MN patients. Samples were collected from 16 MN patients and 10 controls. Immunohistochemistry (IHC) was performed to validate the hub phosphoprotein.

RESULTS

We focused on the changes in the phosphoproteome in MN group versus control group (CG). Totally, 1704 phosphoproteins containing 3241 phosphosites were identified and quantified. The phosphorylation levels of 216 phosphoproteins containing 297 phosphosites were differentially regulated in stage II MN group versus CG, and 333 phosphoproteins containing 461 phosphosites were differentially phosphorylated in stage III MN group versus CG. In each comparison, several differential phosphoproteins were factors, kinases and receptors involved in cellular processes, biological regulation and other biological processes. The subcellular location of most of the differential phosphoproteins was the nucleus. Protein-protein interaction analysis showed that the connections among the differential phosphoproteins were extremely complex, and several signalling pathways probably associated with MN were identified. The hub phosphoprotein was validated by IHC.

CONCLUSIONS AND CLINICAL RELEVANCE

This investigation can provide direct insight into the global phosphorylation events in MN group versus CG and may help to shed light on the potential pathogenic mechanisms of MN.

Application of direct stochastic optical reconstruction microscopy (dSTORM) to the histological analysis of human glomerular disease

Electron microscopy (EM) following immunofluorescence (IF) imaging is a vital tool for the diagnosis of human glomerular diseases, but the implementation of EM is limited to specialised institutions and it is not available in many countries. Recent progress in fluorescence microscopy now enables conventional widefield fluorescence microscopes to be adapted at modest cost to provide resolution below 50 nm in biological specimens. We show that stochastically switched single-molecule localisation microscopy can be applied to clinical histological sections stained with standard IF techniques and that such super-resolved IF may provide an alternative means to resolve ultrastructure to aid the diagnosis of kidney disease where EM is not available. We have implemented the direct stochastic optical reconstruction microscopy technique with human kidney biopsy frozen sections stained with clinically approved immunofluorescent probes for the basal laminae and immunoglobulin G deposits. Using cases of membranous glomerulonephritis, thin basement membrane lesion, and lupus nephritis, we compare this approach to clinical EM images and demonstrate enhanced imaging compared to conventional IF microscopy. With minor modifications in established IF protocols of clinical frozen renal biopsies, we believe the cost-effective adaptation of conventional widefield microscopes can be widely implemented to provide super-resolved image information to aid diagnosis of human glomerular disease.

Membranous Glomerulonephritis as an Uncommon Presentation of Secondary Syphilis: A Reminder on Therapeutic Decision-Making in Clinical Practice

Membranous glomerulonephritis is one of the common causes of nephrotic syndrome in the adult population. It is idiopathic in the majority of patients, but the secondary forms can be seen in the setting of autoimmune disease, cancer, infection, and following exposure to certain medications. However, subclinical syphilis-related membranous nephropathy remains a particularly rare clinicopathologic entity in modern times. In this article, we chronicle an interesting case of latent syphilis masquerading as membranous glomerulonephritis, which resolved with benzathine penicillin without requiring immunosuppressive treatment. We further supplement this paper with a concise review of the relevant literature that delineates the utility of appropriate antibiotic therapy in the management of luetic membranous nephropathy. Clinicians should remain cognizant of secondary syphilis while evaluating patients for possible glomerulonephritis or those presenting with proteinuria. Additionally, patients with hepatitis B, hepatitis C, and human immunodeficiency virus infections are not infrequently coinfected with Treponema pallidum. Therefore, a high index of suspicion for systemic manifestations of syphilis such as nephrotic syndrome is warranted in the setting of a coinfection. Prompt diagnosis and treatment of syphilis may result in resolution of proteinuria, without the need for standard immunosuppressive therapy commonly used in clinical practice.

Advances in antigens associated with Idiopathic Membranous Nephropathy

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. Idiopathic MN (IMN), one of the forms of MN, usually has an unknown etiology. IMN is described as an autoimmune disease, and its pathogenesis is quite complex. The discovery of the M-type phospholipase A₂ receptor (PLA₂R) plays an important role in promoting our understanding of IMN, although the exact mechanisms of its occurrence and development are still not completely clear. Other target antigens have been discovered one after another, as considerable progress has been made in the molecular pathomechanisms of IMN. Here, we review the findings about the target antigens associated with IMN in recent years. It is hoped that this article can provide researchers with some scientific issues or innovative ideas for future studies of IMN, which will provide clinicians with more knowledge about further improving their abilities to provide better medical care for IMN patients.

Rituximab Treatment in a Patient with Kimura Disease and Membranous Nephropathy: Case Report

Kimura disease (KD) is a chronic, inflammatory disorder with slowly developing subcutaneous tumor-like swellings, often occurring in the head and neck region. KD is diagnosed based on histology, elevated levels of immunoglobulin type E, and increased peripheral eosinophil granulocytes. KD may coexist with glomerular renal diseases, and this case report is based on a patient with KD-associated membranous nephropathy. Patients with membranous nephropathy without KD have demonstrated responsiveness to treatment with monoclonal anti-CD20 antibodies. This case report is the first to investigate the effect of rituximab treatment in a patient with KD-associated membranous nephropathy. A 30-year-old Italian man living in Denmark was diagnosed with Kimura's disease based on subcutaneous nodules with eosinophil angiolymphoid hyperplasia. The patient was admitted to the hospital due to nephrotic syndrome. Serology showed eosinophil granulocytosis and negative PLA2-receptor antibody. Renal biopsy showed membranous nephropathy, and the patient was treated with systemic methylprednisolone followed by cyclosporin and then cyclophosphamide with only partial remission. Ultimately, treatment with intravenous rituximab was initiated, which resulted in overall remission and no nephrotic relapses at 30 months of follow-up. Thus, intravenous rituximab effectively decreased proteinuria and prevented nephrotic relapses in a patient with treatment-refractory membranous nephropathy due to KD.

Rapidly Progressing Primary Membranous Nephropathy in a Hispanic Male With Elevated Levels of Anti-phospholipase A2 Receptor Antibodies

A 49-year-old Hispanic male presented to the Emergency Department with progressively worsening swelling in his extremities for the past two months. Physical examination was significant for diffuse edema, with concomitant initial laboratory tests revealing hypoalbuminemia, hypercholesteremia, and proteinuria. A renal biopsy was performed, and the histopathology confirmed a diagnosis of membranous nephropathy through immunofluorescence and electron microscopy. Anti-phospholipase A2 receptor (anti-PLA2R) antibodies were detected on immunofluorescence, as well as high levels being discovered in the patient's serum, indicating a diagnosis of primary membranous nephropathy. The patient underwent adequate diuresis and was discharged. The patient presented six months later due to severe anasarca with laboratory tests indicating a rapid decline in renal function. He was then started on immunosuppressive therapy. Our rare case of a Hispanic male presenting with rapidly deteriorating renal function secondary to primary membranous nephropathy seeks to highlight the possibility of using anti-PLA2R antibodies as a marker for early initiation of immunosuppressive therapy as well as to encourage additional research on the course of disease progression in the Hispanic population. 

Outcomes of primary membranous nephropathy based on serum anti-phospholipase A2 receptor antibodies and glomerular phospholipase A2 receptor antigen status: a retrospective cohort study

Introduction

Primary membranous nephropathy (PMN) is associated with the anti-phospholipase A2 receptor (anti-PLA2R) antibody in 70% of cases. Some anti-PLA2R-negative patients have the PLA2R antigen in renal tissue. This study examined the prognosis of patients with PMN according to their serum anti-PLA2R antibody (SAb) and glomerular PLA2R antigen (GAg) status.

Methods

Patients diagnosed with PMN were included retrospectively. Patients were grouped according to their PLA2R status into the SAb−/GAg−, SAb−/GAg+, and SAb+/GAg + groups. Baseline data, renal biopsy results, treatment, and clinical data were compared among the groups. Cox univariable and multivariable analyses examined the factors related to complete remission (CR).

Results

A total of 114 patients were enrolled; 10 (9%) in the SAb−/GAg−, 23 (20%) in the SAb−/GAg+, and 81 (71%) in the SAb+/GAg+ groups. Cumulative CR rate showed a significant difference between the SAb−/GAg − and SAb+/GAg+ groups (log-rank p = 0.003). The multivariable Cox proportional hazard analysis showed that age (HR = 0.968; 95%CI = 0.946–0.990; p = 0.005), SAb+/GAg+ versus SAb−/GAg− (HR = 0.387; 95%CI = 0.190–0.788; p = 0.009), SAb−/GAg+ versus SAb−/GAg− (HR = 0.398; 95%CI = 0.169, 0.939; p = 0.035), total renal chronicity score ≥2 (HR = 0.461, 95%CI: 0.277–0.766, p = 0.003), and IgA deposition (HR = 2.596; 95%CI = 1.227–5.492; p = 0.013) were all independently related (p < 0.05) to CR.

Conclusions

The SAb and GAg status was an indicator of PMN prognosis. The patients with SAb−/GAg − had an increased likelihood of achieving CR than those with SAb−/GAg+ and SAb+/GAg+.

Renal expression of PLA2R, THSD7A, and IgG4 in patients with membranous nephropathy and correlation with clinical findings

BACKGROUND

Membranous nephropathy (MN) is the most common cause of nephrotic syndrome in nondiabetic adults. M-type phospholipase A2 receptor (PLA2R), thrombospondin type-1 domain-containing 7A (THSD7A) are known as target podocyte antigens in membranous nephropathy (MN). Antibodies against these podocyte antigens are used in the initiation of treatment and response monitoring. However, the relationship between renal podocyte antigens and treatment response is not clear yet. We evaluated the relationship between immunohistochemical PLA2R, THSD7A and IgG4 staining, clinical findings and treatment response in kidney biopsies.

METHODS

Fifty-eight patients with MN were included in this retrospective study. In the renal biopsy samples of the patients, PLA2R, THSD7A and IgG4 were stained immunohistochemically and evaluated by light microscopy. The clinical, laboratory and treatment results of the patients were obtained from the hospital records.

RESULTS

The study included a total of 58 patients with MN and a mean follow-up period of 32.3 ± 19.7 months. In patients with primary MN; PLA2R, THSD7A and IgG4 were positive in 57.1% (n = 28), 12.2% (n = 6) and 69.4% (n = 34), respectively. Only PLA2R staining was distinctly higher in patients with primary MN than secondary MN (P = .025). Dual positivity (PLA2R + THSD7A) was detected in five (10.2%) of patients with primary MN. We did not determine any relationship between the PLA2R, THSD7A and IgG4 staining patterns and treatment response of the patients.

CONCLUSION

It was found no correlation between PLA2R, THSD7A and IgG4 staining in kidney tissue and treatment response. Interestingly, dual positivity (PLA2R + THSD7A) was detected only in primary MN.

Nephrotic syndrome secondary to alpha-1 antitrypsin deficiency

We report a 64-year-old caucasian woman diagnosed with membranous nephropathy secondary to alpha-1 antitrypsin deficiency (AATD). AATD is a rare autosomal codominant genetic disorder. Its clinical manifestations are mostly observed in the lungs, with early-onset emphysema. Nephropathy due to AATD is still very rare and only a few cohort studies have been reported. It has been recognised that alpha-1 antitrypsin has a protective role in the kidneys which enhances the possibility of development of kidney failure, such as nephrotic syndrome, in cases of AATD. Further clinical investigation is needed to understand the relationship between the development of nephropathy, namely membranous nephropathy, and AATD.

Circ_0000524/miR-500a-5p/CXCL16 axis promotes podocyte apoptosis in membranous nephropathy

BACKGROUND

Podocytes apoptosis is a hallmark of membranous nephropathy (MN). Circ_0000524 has been reported to be associated with patients with MN, whereas the effect of circ_0000524 on podocytes apoptosis and the underlying mechanisms in MN have not been elaborated.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were performed to detect the expressions of circ_0000524, microRNA-500a-5p (miR-500a-5p), and C-X-C chemokine ligand 16 (CXCL16) in MN tissues and podocytes. Podocyte injury was induced by angiotensin II (AngII). Cell apoptosis was detected by flow cytometry. Caspase-3 or caspase-9 activity was evaluated using a caspase-3 or caspase-9 activity assay kit, respectively. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and pull-down assay were used to address the relationship among circ_0000524,miR-500a-5p and CXCL16.

RESULTS

Upregulation of circ_0000524 and CXCL16 and low expression of miR-500a-5p were observed in MN tissues. AngII treatment induced the overexpression of circ_0000524 and CXCL16, a decrease of miR-500a-5p, and induced cell apoptosis in podocytes. Circ_0000524 negatively modulated the expression of miR-500a-5p. Circ_0000524 depletion inhibited podocyte apoptosis, which was rescued by loss of miR-500a-5p. miR-500a-5p contained the binding sites with CXCL16. Circ_0000524 knockdown hampered CXCL16 expression by upregulating miR-500a-5p expression. Additionally, miR-500a-5p upregulation suppressed AngII-induced podocyte apoptosis, which was rescued by enhanced expression of CXCL16.

CONCLUSION

Circ_0000524/miR-500a-5p/CXCL16 pathway regulated podocyte apoptosis in MN.