Monthly mini-dose rituximab for primary anti-PLA2R-positive membranous nephropathy: a personalized approach.

BACKGROUND: The currently recommended dose of rituximab for primary membranous nephropathy is as high as that for lymphoma. However, the clinical manifestations of membranous nephropathy vary widely. Therefore, achieving individualized treatment is a topic that needs to be explored. This study assessed the efficacy of monthly mini-dose rituximab monotherapy in patients with primary membranous nephropathy. METHODS: This retrospective study included 32 patients with primary membranous nephropathy treated at Peking University Third Hospital between March 2019 and January 2023. All patients were anti-phospholipase A2 receptor (PLA2R) antibody-positive and received rituximab 100 mg intravenously monthly for at least 3 months without other immunosuppressive therapy. Rituximab infusions were sustained until either remission of the nephrotic syndrome or a minimum serum anti-PLA2R titer ˂ 2 RU/mL was achieved. RESULTS: The baseline parameters included: proteinuria, 8.5 ± 3.6 g/day; serum albumin, 24.8 ± 3.4 g/L; and anti-PLA2R antibody, 160 (20-2659) RU/mL. B-cell depletion was achieved in 87.5% patients after the first dose of rituximab 100 mg and in 100% after the second equivalent dose. The median follow-up was 24 months (range 18-38). Twenty-seven (84%) patients achieved remission, with 11 (34%) patients achieving complete remission by last follow-up. The relapse-free survival from the last infusion was 13.5 months (range 3-27). Patients were stratified into the low-titer (< 150 RU/mL, n = 17) and high-titer groups (≥ 150 RU/mL, n = 15) based on the anti-PLA2R titer. Sex, age, urinary proteins, serum albumin, and estimated glomerular filtration rate at baseline did not differ significantly between the two groups. At 18 months, compared to the low-titer group, the rituximab dose (960 ± 387 vs 694 ± 270 mg, p = 0.030) was higher, while serum albumin (37.0 ± 5.4 vs 41.3 ± 5.4 g/L, p = 0.033) and the complete remission rate (13% vs 53%, p = 0.000) were both lower in the high-titer group. CONCLUSIONS: Monthly rituximab 100 mg appeared as a potential effective regimen for treating anti-PLA2R-associated primary membranous nephropathy with a low anti-PLA2R titer. The lower the anti-PLA2R titer, the lower the rituximab dose required to achieve remission. TRIAL REGISTRATION: A retrospective study, registered at ChiCTR (ChiCTR2200057381) on March 10, 2022.

Low serum IgG4 level: a potential diagnostic biomarker for IgA nephropathy.

BACKGROUND: In contrast to intense investigations of galactose-deficient immunoglobulin A (IgA)1 specific immunoglobulin G (IgG), little is known about the IgG subclasses in IgA nephropathy (IgAN). Low IgG4 levels in IgAN were noticed in our preliminary experiment. We aimed to verify the low IgG4 levels and investigate the related immune mechanism in IgAN. METHODS: A total of 112 healthy controls (HC) and 112 newly diagnosed IgAN patients were enrolled in this study. Patients with idiopathic membranous nephropathy (IMN), minimal change disease (MCD), or lupus nephritis (LN) were selected as disease controls (DC) (n=122). Serum IgG4 and IgG levels were detected by enzyme-linked immunosorbent assay (ELISA). The IgG4+ B, T helper 1 (Th1), and Th2 cells were measured by flow cytometry. Receiver operating characteristic curves (ROC) were performed to evaluate the diagnostic value of IgG4. RESULTS: Both IgG4 levels and IgG4/IgG in IgAN were lower than HC and DC (all P<0.001). Severe IgAN displayed lower IgG4 levels than mild IgAN (P=0.039). Patients with higher risk of renal progression (>50%) demonstrated lower IgG4 levels than lower-risk (≤15%) patients (P=0.019). The cutoff value of IgG4 in differentiating IgAN from HC and DC was 0.26 mg/mL [sensitivity 98.2%, specificity 82.4%, area under the curve (AUC): 0.941, P<0.0001] and 0.17 mg/mL (sensitivity 90.2%, specificity 85.2%, AUC: 0.937, P<0.0001), respectively. IgG4/IgG displayed similar diagnostic and differential ability. The IgG4+ B/B cells (P<0.0001) and Th2/Th (P=0.042) of IgAN were lower than HC. CONCLUSIONS: Serum IgG4 levels were low in IgAN. Lower IgG4 levels indicated more severe disease conditions and higher risk of renal progression. Low serum IgG4 seemed to be a potential diagnostic biomarker for IgAN. Decreased IgG4+ B cells and Th2 cells may contribute to the low IgG4 levels in IgAN.

Single-Cell Sequencing Confirms Transcripts and VHDJH Rearrangements of Immunoglobulin Genes in Human Podocytes.

Most glomerular diseases are associated with inflammation caused by deposited pathogenic immunoglobulins (Igs), which are believed to be produced by B cells. However, our previous study indicated that the human podocyte cell line can produce IgG. In this study, we aimed to confirm the transcripts and characterize the repertoires of Igs in primary podocytes at single cell level. First, single-cell RNA sequencing of cell suspensions from "normal" kidney cortexes by a 10xGenomics Chromium system detected Ig transcripts in 7/360 podocytes and Ig gene segments in 106/360 podocytes. Then, we combined nested PCR with Sanger sequencing to detect the transcripts and characterize the repertoires of Igs in 48 single podocytes and found that five classes of Ig heavy chains were amplified in podocytes. Four-hundred and twenty-nine VHDJH rearrangement sequences were analyzed; podocyte-derived Igs exhibited classic VHDJH rearrangements with nucleotide additions and somatic hypermutations, biased VH1 usage and restricted diversity. Moreover, compared with the podocytes from healthy control that usually expressed one class of Ig and one VHDJH pattern, podocytes from patients expressed more classes of Ig, VHDJH patterns and somatic hypermutations. These findings suggested that podocytes can express Igs in normal condition and increase diversity in pathological situations.

Expression of immunoglobulin G in human proximal tubular epithelial cells.

Proximal tubular epithelial cells (PTECs) have innate immune characteristics, and produce proinflammatory factors, chemokines and complement components that drive epithelial­mesenchymal transition (EMT). Our previous studies revealed that human mesangial cells and podocytes were able to synthesize and secrete immunoglobulin (Ig)A and IgG, respectively. The aim of the present study was to evaluate the expression of Igs in PTECs. Firstly, IgG was detected in the cytoplasm, the cell membrane and the lumen of PTECs in the normal renal cortex by immunohistochemistry. Secondly, Igγ gene transcription and V(D)J recombination were detected in single PTECs by nested PCR and Sanger sequencing. Thirdly, Igγ, Igκ and Igλ were clearly detected in an immortalized PTEC line (HK­2) by immunostaining and western blotting, in which RP215 (an antibody that predominantly binds to non­B cell­derived IgG) was used. In addition, Igγ, Igκ and Igλ gene transcripts, conservative V(D)J recombination in the Igγ variable region, recombination activating gene 1/2 and activation­induced cytidine deaminase were all detected in HK­2 cells. These data suggested that PTECs may express IgG in a similar manner to B cells. Furthermore, IgG expression was upregulated by TGF­ß1 and may be involved in EMT.

Prognostic implications of predialysis patients' symptoms in peritoneal dialysis patients.

BACKGROUND: As kidney disease progresses, patients often experience a variety of symptoms. There are very few studies reporting spectrum of predialysis patients' symptoms in peritoneal dialysis (PD) patients. Furthermore, the clinical significance of predialysis patients' symptoms for PD patients' prognosis remains unknown. METHODS: In this retrospective cohort study, patients who started PD during 1 January 2006 to 31 January 2018 were included. Patients' predialysis symptoms and clinical parameters were obtained. Both the short- and long-term patients' outcome were investigated by Cox regression and Kaplan-Meier's survival analysis to identify the relationship between clinical symptoms and patients' mortality on PD. RESULTS: A total of 898 incident PD patients were included. The anorexia (58%) was the most common predialysis symptom in the present cohort, followed by insomnia (32.7%), fatigue (27.6%), syndromes of heart failure (27.6%), and nausea (20.5%). The only symptom significantly associated with both six-months and 12-months mortality on PD was nausea (HR 2.359, 95% CI 1.377-4.040, p=.002 and HR 1.791, 95% CI 1.176-2.729, p=.007, respectively). But in the long-term, anorexia (HR 1.392, 95% CI 1.070-1.811, p=.014) was the only symptom significantly associated with patient's all-cause mortality after adjusting for other confounding factors. CONCLUSIONS: Our study demonstrated that nausea and anorexia were the most important predialysis symptoms, which was associated with patients' short- and long-term mortality on PD treatment, respectively. The results indicated that predialysis evaluation and management of symptoms of nausea and anorexia may be a possible way to improve patients' outcome on PD.

Idiopathic multicentric Castleman disease with Sjögren's syndrome and secondary membranous nephropathy: a case report and review of the literature.

BACKGROUND: Idiopathic multicentric Castleman disease (iMCD) is an uncommon lymphoproliferative disorder and lacks treatment consensus. Herein, we report a case of iMCD complicated with Sjögren's syndrome (SS) and secondary membranous nephropathy (SMN). CASE PRESENTATION: A 45-year-old female with dry mouth for 3 months and anasarca and proteinuria for 2 months was admitted. She also experienced chest tightness, wheezing, fever, weight loss, moderate proteinuria and hypoalbuminemia. A computed tomography (CT) scan revealed a tissue mass in the thymus area and enlarged multiple lymph nodes. Her symptoms did not improve after resection of the thymus mass. The pathological findings were "reactive hyperplasia of the mediastinal lymph nodes and thymic hyperplasia". Lymph node biopsy findings confirmed iMCD with human herpes virus-8 (HHV-8) negativity. Based on anti-nuclear antibody (ANA) 1:320, anti-SSA and anti-SSB antibody positivity, salivary flow less than 0.1 ml/min and lip biopsy with focal lymphocytic sialadenitis, SS was diagnosed. Kidney biopsy showed secondary membranous nephropathy with endocapillary cell proliferation and infiltration of plasma cells and lymphocytes in the tubulointerstitium. Serum interleukin-6 (IL-6) levels were significantly increased, and therapy with tocilizumab (anti-IL-6 receptor antibody) worked well. The combination of cyclophosphamide (CyS) with methylprednisolone (MP) maintained satisfactory remission. CONCLUSIONS: Our case of iMCD with SS and SMN is rare. There is a need for increased awareness of the disease to avoid unnecessary procedures and misdiagnoses. IL-6 was extremely high, and there was a rapid response to anti-IL-6 receptor agents. The combination of CyS with MP maintained complete remission.

Single-cell RNA sequencing confirms IgG transcription and limited diversity of VHDJH rearrangements in proximal tubular epithelial cells.

Increasing evidence has confirmed that immunoglobulins (Igs) can be expressed in non-B cells. Our previous work demonstrated that mesangial cells and podocytes express IgA and IgG, respectively. The aim of this work was to reveal whether proximal tubular epithelial cells (PTECs) express Igs. High-throughput single-cell RNA sequencing (scRNA-seq) detected Igs in a small number of PTECs, and then we combined nested PCR with Sanger sequencing to detect the transcripts and characterize the repertoires of Igs in PTECs. We sorted PTECs from the normal renal cortex of two patients with renal cancer by FACS and further confirmed their identify by LRP2 gene expression. Only the transcripts of the IgG heavy chain were successfully amplified in 91/111 single PTECs. We cloned and sequenced 469 VHDJH transcripts from 91 single PTECs and found that PTEC-derived IgG exhibited classic VHDJH rearrangements with nucleotide additions at the junctions and somatic hypermutations. Compared with B cell-derived IgG, PTEC-derived IgG displayed less diversity of VHDJH rearrangements, predominant VH1-24/DH2-15/JH4 sequences, biased VH1 usage, centralized VH gene segment location at the 3' end of the genome and non-Gaussian distribution of the CDR3 length. These results demonstrate that PTECs can express a distinct IgG repertoire that may have implications for their role in the renal tubular epithelial-mesenchymal transition.

Urinary angiotensin converting enzyme 2 increases in patients with type 2 diabetic mellitus.

BACKGROUND/AIMS: Angiotensin converting enzyme 2 (ACE2) is highly expressed in the kidney and recognized to be renoprotective by degrading Angiotensin II to Angiotensin (1-7) in diabetic nephropathy. However, little is known about the role of urinary ACE2 (UACE2) in diabetes. The present study was performed to evaluate UACE2 levels in type 2 diabetic patients with various degrees of albuminuria and its associations with metabolic parameters. The effect of RAS inhibitors on UACE2 excretion was also assessed. METHODS: A total of 132 type 2 diabetic patients with different degrees of albuminuria and 34 healthy volunteers were studied. UACE2 levels and activity were measured. RESULTS: Compared to healthy controls, UACE2 to creatinine (UACE2/Cr) levels were significantly increased in both albuminuric and non-albuminuric diabetic patients. UACE2/Cr levels were much higher in hypertensive diabetic patients compared with their normotensive counterparts and treatment with RAS inhibitors markedly attenuated the augmentation. Furthermore, UACE2/Cr was positively correlated with fasting blood glucose, hemoglobin A1C (HbA1C), triglyceride, and total cholesterol. In multiple regression analysis, UACE2/Cr was independently predicted by HbA1C and RAS inhibitors treatment. CONCLUSIONS: UACE2 increased in type 2 diabetic patients with various degrees of albuminuria and RAS inhibitors suppresses UACE2 excretion. UACE2 might potentially function as a marker for monitoring the metabolic status and therapeutic response of RAS inhibitors in diabetes.

Upregulation of soluble epoxide hydrolase in proximal tubular cells mediated proteinuria-induced renal damage.

Epoxyeicosatrienoic acids, hydrolyzed by soluble epoxide hydrolase (sEH), have multiple biological functions, including the regulation of vascular tone, renal tubular transport, and being anti-inflammatory. Inhibitors of sEH have been demonstrated to be antihypertensive and renal protective. To elucidate the role of sEH in glomerulonephritis, we first determined the expression of sEH in human kidney by examining biopsies from 153 patients with a variety of glomerulonephritis, including minimal-change, membranous, and IgA nephropathy. Immunohistochemical staining of frozen kidney biopsy samples revealed sEH preferentially expressed in the renal proximal tubular cells, and its expression increased in all patients with glomerulonephritis. The level of sEH in the cortex was positively correlated with proteinuria and negatively with serum albumin level. To investigate the role of sEH in proteinuria-induced renal damage, we incubated purified urine protein from patients with rat renal proximal tubular epithelial cells in vitro. The level of sEH was elevated, as were monocyte chemoattractant protein 1 and the process of tubular epithelial-to-mesenchymal transition, characterized with increased α-smooth muscle actin (α-SMA) and decreased E-cadherin. These effects were attenuated by administration of a potent sEH inhibitor and mimicked with adenovirus-mediated sEH overexpression. In adriamycin-induced nephropathic mice, sEH inhibitor did not ameliorate proteinuria or level of serum albumin but reduced the long-term elevated serum creatinine level, interstitial inflammation, fibrosis, and α-SMA expression. Thus upregulation of sEH in proximal tubular cells in chronic proteinuric kidney diseases may mediate proteinuria-induced renal damage; sEH inhibition by increasing renal eicosanoid levels could prevent the progression of chronic proteinuric kidney diseases.

Hospital-acquired and community-acquired acute renal failure in hospitalized Chinese: a ten-year review.

OBJECTIVES: To investigate the difference between hospital-acquired acute renal failure (HA-ARF) and community-acquired acute renal failure (CA-ARF) in hospitalized Chinese. METHODS: The diagnosis of ARF in Peking University Third Hospital from January 1994 to December 2003 was reconfirmed and subdivided into AC-ARF and HA-ARF. Data of epidemiology, etiology, prognosis, and associated factors were analyzed. Single-variable analysis and multivariate logistic regression analyses were performed to investigate the correlation between clinical features and prognosis respectively. Results among 205 reconfirmed CA-ARF had a predominance of 59.5%, but HA-ARF demonstrated an increase by 1.06 during the last five years (p = 0.003). In all, 70.5% CA-ARF was diagnosed in internal medicine with 45.9% in department of nephrology, whereas 59.1% HA-ARF was diagnosed in surgical department with 51.8% in ICU. Distribution difference among departments was significant (p < 0.01). Further, 90.2% CA-ARF was associated with a single factor, while 36.1% of HA-ARF had two or more causes (p < 0.01). Also, 26.5% HA-ARF and 18.9% CA-ARF was drug-associated (p > 0.05) while 24.1% HA-ARF and 12.3% CA-ARF was infection-associated (p < 0.01). HA-ARF vs. CA-ARF was 62.7% vs. 23.0% in mortality (p < 0.01), 0.54 +/- 0.24 vs. 0.27 +/- 0.18 in ATI-ISS index (p < 0.01) and 19.6 +/- 4.9 vs. 15.7 +/- 5.6 in APACHE II scores (p < 0.01). MODS and SIRS were common independent predictors with oliguria for HA-ARF and advanced age for CA-ARF, respectively. CONCLUSIONS: In hospitalized Chinese during the last ten years, CA-ARF was still predominant with simpler cause and lower mortality, whereas HA-ARF was increasing with more complicated cause and higher mortality.

[Comparison of clinical characteristics between hospital-acquired and community-acquired acute renal failure].

OBJECTIVE: To investigate the differences between hospital-acquired acute renal failure (HA-ARF) and community-acquired acute renal failure (CA-ARF) in epidemiology, etiology and prognosis. METHODS: The diagnosis of ARF of patients diagnosed with ARF from ICD-9 codes, who were discharged from Peking University Third Hospital from January 1994 to December 2003, was reconfirmed and categorized by two nephrologists independently. The indexes of epidemiology, etiology and prognosis were studied. Single-variable analysis and multivariate logistic regression analysis were performed to investigate the correlation between clinical features and prognosis respectively. RESULTS: Two hundred and five cases were collected and all were reconfirmed. CA-ARF had a predominance of 59.5%. HA-ARF, however, increased by 1.06 times in last 5 years (P<0.05); 59.0% of HA-ARF was diagnosed in department of surgery while 70.5% of CA-ARF was in medical department (both P<0.05); 36.1% HA-ARF patients had two or more pathogenic causes, while 91.2% CA-ARF only had one cause (P<0.05); 49.4% HA-ARF developed after operation; 26.5% HA-ARF and 18.8% CA-ARF were drug-related (P>0.05); 24.1% HA-ARF and 12.3% CA-ARF were infection-related (P=0.028). Mortality and recovery rates were 62.7% and 20.6%, respectively, in HA-ARF while 23.0% and 67.2% in CA-ARF respectively (both P<0.01). The percentage of oliguria, multiple organ failure (MOF), systemic inflammatory response syndrome (SIRS), and use of mechanical ventilation were significantly higher in HA-ARF than in CA-ARF (all P<0.01). Acute tubule necrosis-injury severity score (ATN-ISS), acute pathological and chronic health evaluation (APACHE II) score were 0.54+/-0.24 and 19.6+/-4.9 in HA-ARF, while they were 0.27+/-0.18 and 15.7+/-5.6 in CA-ARF (both P<0.01). Multiple regression analysis identified that both MOF and SIRS were common independent risk factors for HA-ARF and CA-ARF, and oliguria and advanced age were respective independent risk factor for HA-ARF and CA-ARF. CONCLUSION: CA-ARF prevails in hospitalized Chinese patients during the last 10 years, but HA-ARF is increasing in incidence significantly during the last 5 years. The etiology is mostly simple and the prognosis is relatively good in CA-ARF, while the pathogenic cause is mostly complicated and the outcome is much poorer in HA-ARF.

Retrospective analysis on Chinese patients diagnosed with acute renal failure hospitalized during the last decade (1994-2003).

OBJECTIVES: To investigate the epidemiology, diagnosis and prognosis of acute renal failure (ARF) in hospitalized Chinese during the last decade. METHODS: The diagnosis of patients with ARF in Peking University Third Hospital from January 1994 to December 2003 was reconfirmed and the data of epidemiology, etiology and prognosis were analyzed. RESULTS: Only 209 discharged cases were diagnosed with ARF and all were reconfirmed. Two peak occurrences were found at ages of 35-45 and 60-80 with a male predominance of approximately 59.7%. Patients diagnosed with ARF accounted for 1.19 per thousand of the admissions in the same period and increased significantly in the last 5 years (p = 0.038). The creatinine level at diagnosis was 345.8 +/- 122.6 micromol/l and had no significant change (p > 0.05). The percent of hospital-acquired ARF (HA-ARF) demonstrated a significant increase in 1999-2003 compared to 1994-1998 (p = 0.008). Intrarenal ARF accounted for 73.69% and was multifactorial, with drugs, infections and operations as leading causes. Renal biopsy was performed in 37.32% (78/209) with 53.84% (42/78) having acute interstitial nephritis. Maintenance dialysis was discontinued in 46.41% because their renal function completely or partially recovered. The overall mortality was 37.91% without improvement over time. The mortality was 6.25% for patients in nephrology department, but 65.51% in ICU (p < 0.001), and was 21.6% for patients in community-acquired ARF (CA-ARF), but 63.1% in HA-ARF (p < 0.001). CONCLUSIONS: During the past 10 years, the number of patients diagnosed with ARF has been rising in hospitalized Chinese. HA-ARF was the major source, and infections, drugs and operations were the leading causes. The diagnosis and prognosis of acute renal failure did not improve much in this population over the decade studied.

[Study on epidemiology and etiology of hospitalized patients with acute renal failure].

OBJECTIVE: To investigate the change in epidemiology and etiology of hospitalized patients with acute renal failure (ARF) during the last years. METHODS: The data of hospitalized patients with ARF in the Third Hospital of Peking University during the last 10 years were retrospectively analyzed. The changes in epidemiology and etiology and the relative factors were studied. RESULTS: Two hundred and eleven cases from January 1994 to March 2004 were diagnosed to have ARF during the last 10 years accounting for 0.12% hospitalized patients, with an increasing trend yearly. ARF occurred in patients of all ages with two peak in the 35-45 year and 60-80 years old. The ratio of male over female was about 3 : 2. Among 211 patients, only 33 (15.6%) had renal diseases previously while 178 (84.4%) had never. Eighty-four cases (39.8%)were hospital-acquired ARF which demonstrated a significant increase after 2000 (P<0.05). One hundred and twenty-four (58.8%) were diagnosed in internal medicine with a declining trend while 87 (41.2%) were diagnosed in surgical department with a rising trend. Fifty-eight cases (27.5%) were found in intensive care unit (ICU) which demonstrated a increase by 1 89-fold after 2000.Infections, drugs and operations were the major causes for development of ARF with 61 cases (28.9%), 46 cases (21.8%) and 41 cases (19.4%) respectively. Forty-one cases (19.4%) were pre-renal, 156 cases(73.9%) were intrinsic with 72 cases (46.2%) confirmed to be ARF developed from pre-renal factors, and 14 cases (6.6%) were developed from post-renal factors. One hundred and thirty-four cases (85.9%) were acute tubulointerstitial lesions. CONCLUSION: During the last 10 years, there is an increasing trend in the incidence of ARF in hospitalized patients which might be attributed to hospital-acquired ARF due to drug, infection and operation.