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Introduction: Rituximab is a first-line treatment for membranous nephropathy. Nephrotic syndrome limits rituximab exposure due to urinary drug loss. Rituximab underdosing (serum level <2 μg/ml at month-3) is a risk factor for treatment failure. We developed a machine learning algorithm to predict the risk of underdosing based on patients' characteristics at rituximab infusion. We investigated the relationship between the predicted risk of underdosing and the cumulative dose of rituximab required to achieve remission., Methods: Rituximab concentrations were measured at month-3 in 92 sera from adult patients with primary membranous nephropathy, split into a training (75%) and a testing set (25%). A forward-backward machine-learning procedure determined the best combination of variables to predict rituximab underdosing in the training data set, which was tested in the test set. The performances were evaluated for accuracy, sensitivity, and specificity in 10-fold cross-validation training and test sets., Results: The best variables combination to predict rituximab underdosing included age, gender, body surface area (BSA), anti-phospholipase A2 receptor type 1 (anti-PLA2R1) antibody titer on day-0, serum albumin on day-0 and day-15, and serum creatinine on day-0 and day-15. The accuracy, sensitivity, and specificity were respectively 79.4%, 78.7%, and 81.0% (training data set), and 79.2%, 84.6% and 72.7% (testing data set). In both sets, the algorithm performed significantly better than chance ( P  < 0.05). Patients with an initial high probability of underdosing experienced a longer time to remission with higher rituximab cumulative doses required to achieved remission., Conclusion: This algorithm could allow for early intensification of rituximab regimen in patients at high estimated risk of underdosing to increase the likelihood of remission., (© 2023 Published by Elsevier, Inc., on behalf of the International Society of Nephrology.)

Primary membranous nephropathy (pMN) is an auto-immune disease characterized by auto-antibodies targeting podocyte antigens resulting in activation of complement and damage to the glomerular basement membrane. pMN is the most common cause of nephrotic syndrome in adults without diabetes. Despite a very heterogeneous course of the disease, the treatment of pMN has for many years been based on uniform management of all patients regardless of the severity of the disease. The identification of prognostic markers has radically changed the vision of pMN and allowed KDIGO guidelines to evolve in 2021 towards a more personalized management based on the assessment of the risk of progressive loss of kidney function. The recognition of pMN as an antibody-mediated autoimmune disease has rationalized the use immunosuppressive drugs such as rituximab. Rituximab is now a first line immunosuppressive therapy for patients with pMN with proven safety and efficacy achieving remission in 60-80% of patients. For the remaining 20-40% of patients, several mechanisms may explain rituximab resistance: (i) decreased rituximab bioavailability; (ii) immunization against rituximab; and (iii) chronic glomerular damage. The treatment of patients with rituximab-refractory pMN remains controversial and challenging. In this review, we provide an overview of recent advances in the management of pMN (according to the KDIGO 2021 guidelines), in the understanding of the pathophysiology of rituximab resistance, and in the management of rituximab-refractory pMN. We propose a treatment decision aid based on immunomonitoring to identify failures related to underdosing or immunization against rituximab to overcome treatment resistance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Teisseyre, Cremoni, Boyer-Suavet, Ruetsch, Graça, Esnault, Brglez and Seitz-Polski.)

Patients with hematological malignancies have impaired immune response after two doses of BNT162b2 (Pfizer/BioNTech) vaccine against SARS-CoV-2. Here, in this observational study (registration number HDH F20210324145532), we measure SARS-CoV-2 anti-Spike antibodies, neutralizing antibodies and T-cell responses after immune stimulation with a third dose (D3) of the same vaccine in patients with chronic lymphocytic leukemia (n = 13), B cell non-Hodgkin lymphoma (n = 14), and multiple myeloma (n = 16)). No unexpected novel side effects are reported. Among 25 patients with positive anti-S titers before D3, 23 (92%) patients increase their anti-S and neutralizing antibody titer after D3. All 18 (42%) initially seronegative patients remain negative. D3 increases the median IFN-γ secretion in the whole cohort and induces IFN-γ secretion in a fraction of seronegative patients. Our data thus support the use of a third vaccine dose amongst patients with lymphoid malignancies, even though some of them will still have vaccine failure., (© 2022. The Author(s).)

Background: Renal involvement in syndrome coronavirus 2 (SARS-CoV-2) infection has been retrospectively described, especially acute kidney injury (AKI). However, quantitative proteinuria assessment and its implication in coronavirus disease 2019 (COVID-19) remain unknown., Methods: In this prospective, multicenter study in France, we collected clinical and biological data including urinary protein to creatine ratio (UPCR) in patients presenting with moderate to severe COVID-19. Clinical outcome was analyzed according to the level of UPCR., Results: 42/45 patients (93.3%) had renal involvement (abnormal urinary sediment and/or AKI). Significant proteinuria occurred in 60% of patients. Urine protein electrophoresis showed tubular protein excretion in 83.8% of patients with proteinuria. Inflammatory parametersand D-dimer concentrations correlated with proteinuria level. Patients who required intensive care unit (ICU) admission had higher proteinuria ( p = 0.008). On multivariate analysis, proteinuria greater than 0.3 g/g was related to a higher prevalence of ICU admission [OR = 4.72, IC95 (1.16-23.21), p = 0.03], acute respiratory distress syndrome (ARDS) [OR = 6.89, IC95 (1.41-53.01, p = 0.02)], nosocomial infections [OR = 3.75, IC95 (1.11-13.55), p = 0.03], longer inpatient hospital stay ( p = 0.003)., Conclusion: Renal involvement is common in moderate to severe SARS-CoV-2 infection. Proteinuria at baseline is an independent risk factor for increased hospitalization duration and ICU admission in patients with COVID-19., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ouahmi, Courjon, Morand, François, Bruckert, Lombardi, Esnault, Seitz-Polski, Demonchy, Dellamonica and Boyer-Suavet.)

Frontline health care workers (HCWs) have been particularly exposed to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) since the start of the pandemic but the clinical features and immune responses of those infected with SARS-CoV-2 have not been well described. In a prospective single center cohort study, we enrolled 196 frontline HCWs exposed to the SARS-Cov-2 and 60 patients with moderate and severe forms of the coronavirus disease 2019 (COVID-19). Serological tests and cytokines assay were performed to analyze SARS-CoV-2-specific humoral and cellular immunity. Of the 196 HCWs tested, 15% had specific antibodies against SARS-CoV-2 and 45% of seropositive HCWs were strictly asymptomatic. However, in comparison to moderate and severe forms, HCWs with mild or asymptomatic forms of COVID-19 showed lower specific IgA and IgG peaks, consistent with their mild symptoms, and a robust immune cellular response, illustrated by a high production of type I and II interferons. Further studies are needed to evaluate whether this interferon functional immune assay, routinely applicable, can be useful in predicting the risk of severe forms of COVID-19., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Cremoni, Ruetsch, Zorzi, Fernandez, Boyer-Suavet, Benzaken, Demonchy, Dellamonica, Ichai, Esnault, Brglez and Seitz-Polski.)

Background and Objectives: Patients with membranous nephropathy can have circulating autoantibodies against membrane-bound (phospholipase A2 receptor 1 [PLA2R1] and thrombospondin type-1 domain containing 7A [THSD7A]) and intracellular (aldose reductase, SOD2, and α-enolase) podocyte autoantigens. We studied their combined association with clinical outcomes., Design, Setting, Participants, & Measurements: Serum levels of anti-PLA2R1, anti-THSD7A, anti-aldose reductase, anti-SOD2, and anti-α-enolase autoantibodies were determined in 285 patients at diagnosis and during follow-up using standardized and homemade assays. An eGFR>60 ml/min per 1.73 m 2 and remission of proteinuria (<0.3/<3.5 g per d) after 12 months were the outcomes of interest., Results: At diagnosis, 182 (64%), eight (3%), and 95 (33%) patients were anti-PLA2R1 + , anti-THSD7A + , and double negative, respectively. The prevalence of a detectable antibody to at least one intracellular antigen was similarly distributed in patients who were anti-PLA2R1 + ( n =118, 65%) and double negative ( n =64, 67%). Positivity for anti-PLA2R1, anti-SOD2, and anti-α-enolase antibodies and higher titers at diagnosis were associated with poor clinical outcome independently to each other. Combined positivity for anti-PLA2R1, anti-SOD2, and anti-α-enolase was associated with highest risk of poor outcome (odds ratio, 5.5; 95% confidence interval, 1.2 to 24; P =0.01). In Kaplan-Meier analysis, patients who were anti-PLA2R1 + /anti-SOD2 + or anti-PLA2R1 + /anti-α-enolase + had lower eGFR at 12 months compared with patients who were anti-PLA2R1 + /anti-SOD2 - or anti-α-enolase - . Predictive tests (net reclassification index and area under the curve-receiver-operating characteristic analysis) showed that combined assessment of antibodies improved classification of outcome in 22%-34% of cases for partial remission of proteinuria and maintenance of normal eGFR. For patients with nephrotic syndrome at diagnosis, anti-SOD2 positivity and high anti-PLA2R1 titer were associated with a lack of complete remission. Patients who were anti-PLA2R1 - /anti-intracellular antigens - had the lowest proteinuria and the highest eGFR at diagnosis and the lowest risk of lower eGFR at 12 months. Epitope spreading was present in 81% of patients who were anti-PLA2R1 + and was associated with increased positivity for intracellular antigens and poor eGFR at diagnosis and 12 months., Conclusions: Combined serological analysis of autoantibodies targeting membrane-bound and intracellular autoantigens identifies patients with poor clinical outcomes., (Copyright © 2020 by the American Society of Nephrology.)

Membranous nephropathy (MN) is a rare autoimmune kidney disease. Most autoimmune diseases are associated with a pro-inflammatory Th17-immune response, but little is known about immune dysregulation in MN. In China, MN was associated with exposure to fine air particulate matter (PM 2.5 ) that could act as a danger signal and redirect immune response toward the Th2 or Th17 pathway. We aimed to analyze the cytokine profile of MN patients and to study the possible environmental factors involved in this immune reorientation, as well as the consequences on the prognosis of the disease. In this prospective study, 59 MN patients filled a comprehensive lifestyle questionnaire. Peripheral blood cells from MN patients were stimulated in vitro to measure the cytokines produced in supernatant. Cytokine profiles of MN patients were compared to 28 healthy donors and analyzed regarding individual PM 2.5 exposure. Compared to healthy donors, MN patients had higher serum levels of Th17 and Th2 cytokines IL-17A (62 pg/ml [IQR, 16-160] versus 31 [IQR, 13-51], P =0.035), IL-6 (66767 pg/ml [IQR, 36860-120978] versus 27979 [IQR, 18672-51499], P =0.001), and IL-4 (12 pg/ml [IQR, 0-33] versus 0 pg/ml [IQR, 0-0], P =0.0003), respectively, as well as a deficiency of Th1 and regulatory T cell cytokines IFN-γ (5320 pg/ml [IQR, 501-14325] versus 18037 [IQR, 4889-31329], P =0.0005) and IL-10 (778 pg/ml [IQR, 340-1247] versus 1102 [IQR, 737-1652], P =0.04), respectively. MN patients with high IL-17A levels lived in areas highly exposed to PM 2.5 : 51 μg/m 3 versus 31 μg/m 3 for patients with low IL-17A levels ( P =0.002) while the World Health Organization recommends an exposition below 10 μg/m 3 . MN patients with Th17-mediated inflammation had more venous thromboembolic events ( P =0.03) and relapsed more often ( P =0.0006). Rituximab treatment induced Th1 and regulatory T cell cytokines but did not impact Th17 cytokines. MN patients with Th17-mediated inflammation which appears to be related to an urban environment have worse prognosis. Alternative strategies targeting dysregulated cytokine balance could be considered for these patients at high risk of relapse., Competing Interests: Some co-authors are coinventors on the patents “Methods and kits for monitoring membranous nephropathy” (BS-P), and “Prognosis and monitoring of membranous nephropathy based on the analysis of PLA2R1 epitope profile and spreading” (BS-P, VE). The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Cremoni, Brglez, Perez, Decoupigny, Zorzi, Andreani, Gérard, Boyer-Suavet, Ruetsch, Benzaken, Esnault and Seitz-Polski.)

The phospholipase A2 receptor (PLA2R1) is the major autoantigen in idiopathic membranous nephropathy (MN). However, the pathogenic role of anti-PLA2R1 autoantibodies is unclear. Our aim was to evaluate the in vitro cytotoxicity of anti-PLA2R1 antibodies mediated by complement. Forty-eight patients with PLA2R1-related MN from the prospective cohort SOURIS were included. Anti-PLA2R1 titer, epitope profile, and anti-PLA2R1 IgG subclasses were characterized by ELISA. Cell cytotoxicity was evaluated by immunofluorescence in HEK293 cells overexpressing PLA2R1 incubated with patient or healthy donor sera in the presence or absence of rabbit complement or complement inhibitors. Mean cytotoxicity of anti-PLA2R1 sera for HEK293 cells overexpressing PLA2R1 was 2 ± 2%, which increased to 24 ± 6% after addition of rabbit complement ( p < 0.001) ( n = 48). GVB-EDTA, which inhibits all complement activation pathways, completely blocked cell cytotoxicity, whereas Mg-EGTA, which only inhibits the classical and lectin pathways, highly decreased suggesting a limited role of the alternative pathway. A higher diversity of IgG subclasses beyond IgG4 and high titer of total IgG anti-PLA2R1 were associated with increased cytotoxicity ( p = 0.01 and p = 0.03 respectively). In a cohort of 37 patients treated with rituximab, high level of complement-mediated cytotoxicity was associated with less and delayed remission at month 6 after rituximab therapy (5/12 vs. 20/25 ( p = 0.03) in 8.5 months ± 4.4 vs. 4.8 ± 4.0 ( p = 0.02)). Kaplan-Meier analysis demonstrated that high level of cytotoxicity (≥40%) ( p = 0.005), epitope spreading (defined by immunization beyond the immunodominant CysR domain) ( p = 0.002), and high titer of anti-PLA2R1 total IgG ( p = 0.01) were factors of poor renal prognosis. Anti-PLA2R1 antibodies containing sera can induce in vitro cytotoxicity mediated by complement activation, and the level of cytotoxicity increases with the diversity and the titer of anti-PLA2R1 IgG subclasses. These patients with high level of complement-mediated cytotoxicity could benefit from adjuvant therapy using complement inhibitor associated with rituximab to induce earlier remission and less podocyte injury., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2019 Maël Lateb et al.)