Both Humoral and Cellular Immune Responses to SARS-CoV-2 Are Essential to Prevent Infection: a Prospective Study in a Working Vaccinated Population from Southern France.

COVID-19 vaccines have significantly decreased the number of severe cases of the disease, but the virus circulation remains important, and questions about the need of new vaccination campaigns remain unanswered. The individual's protection against SARS-CoV-2 infection is most commonly measured by the level and the neutralizing capacity of antibodies produced against SARS-CoV-2. T cell response is a major contributor in viral infection, and several studies have shown that cellular T cell response is crucial in fighting off SARS-CoV-2 infection. Actually, no threshold of protective immune response against SARS-CoV2 infection has been identified. To better understand SARS-CoV-2-mediated immunity, we assessed both B cell (measuring anti-Spike IgG titer and neutralization capacity) and T cell (measuring IFNγ release assay after specific SARS-CoV2 stimulation) responses to SARS-CoV-2 vaccination with or without virus encounter in a cohort of 367 working volunteers. Vaccinated individuals who had previously been infected had a stronger and more lasting immunity in comparison to vaccinated individuals naive to infection whose immunity started to decline 3 months after vaccination. IFNγ release ≥ 0.285 IU/mL and anti-Spike IgG antibodies ≥ 244 BAU/mL were associated with a sufficient immune response following vaccination preventing future infections. Individuals with comorbidities had a lower chance of reaching the protective thresholds of T cell and B cell responses as identified in multivariate analysis. A combined B cell and T cell analysis of immune responses to determine protective thresholds after SARS-CoV-2 vaccination will allow us to identify individuals in need of a booster vaccine dose, particularly in comorbid subjects.

Anti-rituximab antibodies demonstrate neutralizing capacity, associate with lower circulating drug levels and earlier relapse in lupus.

OBJECTIVES: High rates of anti-drug antibodies (ADA) to rituximab have been demonstrated in patients undergoing treatment for SLE. However, little is known with regard to their long-term dynamics, impact on drug kinetics and subsequent implications for treatment response. In this study, we aimed to evaluate ADA persistence over time, impact on circulating drug levels, assess clinical outcomes and whether they are capable of neutralizing rituximab. METHODS: Patients with SLE undergoing treatment with rituximab were recruited to this study (n = 35). Serum samples were collected across a follow-up period of 36 months following treatment (n = 114). Clinical and laboratory data were collected pre-treatment and throughout follow-up. ADA were detected via electrochemiluminescent immunoassays. A complement dependent cytotoxicity assay was used to determine neutralizing capacity of ADA in a sub-cohort of positive samples (n = 38). RESULTS: ADA persisted over the 36-month study period in 64.3% of patients undergoing treatment and titres peaked earlier and remained higher in those who had previously been treated with rituximab when compared with than those who were previously treatment naive. ADA-positive samples had a significantly lower median drug level until six months post rituximab infusion (P = 0.0018). Patients with persistent ADA positivity showed a significant early improvement in disease activity followed by increased rates of relapse. In vitro analysis confirmed the neutralizing capacity of ADA to rituximab. CONCLUSIONS: ADA to rituximab were common and persisted over the 36-month period of this study. They associated with earlier drug elimination, an increased rate of relapse and demonstrated neutralizing capacity in vitro.

Novel ELISA for thrombospondin type 1 domain-containing 7A autoantibodies in membranous nephropathy.

Autoantibodies against phospholipase A2 receptor 1 (PLA2R1) and thrombospondin type 1 domain-containing 7A (THSD7A) are emerging as biomarkers to classify membranous nephropathy (MN) and to predict outcome or response to treatment. Anti-THSD7A autoantibodies are detected by Western blot and indirect immunofluorescence test (IIFT). Here, we developed a sensitive enzyme-linked immunosorbent assay (ELISA) optimized for quantitative detection of anti-THSD7A autoantibodies. Among 1012 biopsy-proven MN patients from 6 cohorts, 28 THSD7A-positive patients were identified by ELISA, indicating a prevalence of 2.8%. By screening additional patients, mostly referred because of PLA2R1-unrelated MN, we identified 21 more cases, establishing a cohort of 49 THSD7A-positive patients. Twenty-eight patients (57%) were male, and male patients were older than female patients (67 versus 49 years). Eight patients had a history of malignancy, but only 3 were diagnosed with malignancy within 2 years of MN diagnosis. We compared the results of ELISA, IIFT, Western blot, and biopsy staining, and found a significant correlation between ELISA and IIFT titers. Anti-THSD7A autoantibodies were predominantly IgG4 in all patients. Eight patients were double positive for THSD7A and PLA2R1. Levels of anti-THSD7A autoantibodies correlated with disease activity and with response to treatment. Patients with high titer at baseline had poor clinical outcome. In a subgroup of patients with serial titers, persistently elevated anti-THSD7A autoantibodies were observed in patients who did not respond to treatment or did not achieve remission. We conclude that the novel anti-THSD7A ELISA can be used to identify patients with THSD7A-associated MN and to monitor autoantibody titers during treatment.

Phospholipase A2 Receptor 1 Epitope Spreading at Baseline Predicts Reduced Likelihood of Remission of Membranous Nephropathy.

The phospholipase A2 receptor (PLA2R1) is the major autoantigen in primary membranous nephropathy. Several PLA2R1 epitopes have been characterized, and a retrospective study identified PLA2R1 epitope spreading as a potential indicator of poor prognosis. Here, we analyzed the predictive value of anti-PLA2R1 antibody (PLA2R1-Ab) titers and epitope spreading in a prospective cohort of 58 patients positive for PLA2R1-Ab randomly allocated to rituximab (n=29) or antiproteinuric therapy alone (n=29). At baseline, the epitope profile (CysR, CysRC1, CysRC7, or CysRC1C7) did not correlate with age, sex, time from diagnosis, proteinuria, or serum albumin, but epitope spreading strongly correlated with PLA2R1-Ab titer (P<0.001). Ten (58.8%) of the 17 patients who had epitope spreading at baseline and were treated with rituximab showed reversal of epitope spreading at month 6. In adjusted analysis, epitope spreading at baseline was associated with a decreased remission rate at month 6 (odds ratio, 0.16; 95% confidence interval, 0.04 to 0.72; P=0.02) and last follow-up (median, 23 months; odds ratio, 0.14; 95% confidence interval, 0.03 to 0.64; P=0.01), independently from age, sex, baseline PLA2R1-Ab level, and treatment group. We propose that epitope spreading at baseline be considered in the decision for early therapeutic intervention in patients with primary membranous nephropathy.

Thrombospondin type-1 domain-containing 7A in idiopathic membranous nephropathy.

BACKGROUND: Idiopathic membranous nephropathy is an autoimmune disease. In approximately 70% of patients, it is associated with autoantibodies against the phospholipase A2 receptor 1 (PLA2R1). Antigenic targets in the remaining patients are unknown. METHODS: Using Western blotting, we screened serum samples from patients with idiopathic membranous nephropathy, patients with other glomerular diseases, and healthy controls for antibodies against human native glomerular proteins. We partially purified a putative new antigen, identified this protein by means of mass spectrometry of digested peptides, and validated the results by analysis of recombinant protein expression, immunoprecipitation, and immunohistochemical analysis. RESULTS: Serum samples from 6 of 44 patients in a European cohort and 9 of 110 patients in a Boston cohort with anti-PLA2R1-negative idiopathic membranous nephropathy recognized a glomerular protein that was 250 kD in size. None of the serum samples from the 74 patients with idiopathic membranous nephropathy who were seropositive for anti-PLA2R1 antibodies, from the 76 patients with other glomerular diseases, and from the 44 healthy controls reacted against this antigen. Although this newly identified antigen is clearly different from PLA2R1, it shares some biochemical features, such as N-glycosylation, membranous location, and reactivity with serum only under nonreducing conditions. Mass spectrometry identified this antigen as thrombospondin type-1 domain-containing 7A (THSD7A). All reactive serum samples recognized recombinant THSD7A and immunoprecipitated THSD7A from glomerular lysates. Moreover, immunohistochemical analyses of biopsy samples from patients revealed localization of THSD7A to podocytes, and IgG eluted from one of these samples was specific for THSD7A. CONCLUSIONS: In our cohort, 15 of 154 patients with idiopathic membranous nephropathy had circulating autoantibodies to THSD7A but not to PLA2R1, a finding that suggests a distinct subgroup of patients with this condition. (Funded by the French National Center for Scientific Research and others.).

Epitope Spreading of Autoantibody Response to PLA2R Associates with Poor Prognosis in Membranous Nephropathy.

The phospholipase A2 receptor (PLA2R1) is the major autoantigen in idiopathic membranous nephropathy. However, the value of anti-PLA2R1 antibody titers in predicting patient outcomes is unknown. Here, we screened serum samples from 50 patients positive for PLA2R1 for immunoreactivity against a series of PLA2R1 deletion mutants covering the extracellular domains. We identified reactive epitopes in the cysteine-rich (CysR), C-type lectin domain 1 (CTLD1), and C-type lectin domain 7 (CTLD7) domains and confirmed the reactivity with soluble forms of each domain. We then used ELISAs to stratify 69 patients positive for PLA2R1 by serum reactivity to one or more of these domains: CysR (n=23), CysRC1 (n=14), and CysRC1C7 (n=32). Median ELISA titers measured using the full-length PLA2R1 antigens were not statistically different between subgroups. Patients with anti-CysR-restricted activity were younger (P=0.008), had less nephrotic range proteinuria (P=0.02), and exhibited a higher rate of spontaneous remission (P=0.03) and lower rates of renal failure progression (P=0.002) and ESRD (P=0.01) during follow-up. Overall, 31 of 69 patients had poor renal prognosis (urinary protein/creatinine ratio >4 g/g or eGFR<45 ml/min per 1.73 m(2) at end of follow-up). High anti-PLA2R1 activity and epitope spreading beyond the CysR epitope were independent risk factors of poor renal prognosis in multivariable Cox regression analysis. Epitope spreading during follow-up associated with disease worsening (n=3), whereas reverse spreading from a CysRC1C7 profile back to a CysR profile associated with favorable outcome (n=1). We conclude that analysis of the PLA2R1 epitope profile and spreading is a powerful tool for monitoring disease severity and stratifying patients by renal prognosis.

Prediction of membranous nephropathy recurrence after transplantation by monitoring of anti-PLA2R1 (M-type phospholipase A2 receptor) autoantibodies: a case series of 15 patients.

BACKGROUND: The predictive value of anti-M-type phospholipase A2 receptor (PLA2R1) autoantibodies for membranous nephropathy (MN) recurrence after renal transplantation remains controversial. METHODS: Our aim was to monitor anti-PLA2R1 IgG4 activity using a sensitive enzyme-linked immunosorbent assay in 15 kidney transplant recipients with MN, and to test the correlation between antibody titres and MN recurrence. RESULTS: Five patients never exhibited anti-PLA2R1 antibodies, and one of them relapsed. Ten patients (67%) had IgG4 anti-PLA2R1 antibodies at the time of transplantation and during follow-up. The presence of IgG4 anti-PLA2R1 antibodies at the time of kidney transplantation does not imply MN recurrence (P = 0.600, n = 15). However, a positive IgG4 anti-PLA2R1 activity during follow-up (>Month 6) was a significant risk factor for MN relapse (P = 0.0048, n = 10). Indeed, four patients had persistent IgG4 anti-PLA2R1 activity after transplantation and relapsed. Among them, one was successfully treated with rituximab. Another had persistently high IgG4 anti-PLA2R1 activity and exhibited a histological relapse but no proteinuria while on treatment with renin-angiotensin system inhibitors. In contrast, the six other patients who did not relapse exhibited a decrease of their IgG4 anti-PLA2R1 activity following transplant immunosuppression, including two with proteinuria due to biopsy-proven differential diagnoses. A weak transplant immunosuppressive regimen was also a risk factor of MN recurrence (P = 0.0048, n = 10). Indeed, the six patients who received both an induction therapy and a combined treatment with calcineurin inhibitors/mycophenolate exhibited a decrease of IgG4 anti-PLA2R1 activity and did not relapse, while the four patients who did not receive this strong immunosuppressive treatment association had persistently high IgG4 anti-PLA2R1 activity and relapsed. CONCLUSION: The monitoring of IgG4 anti-PLA2R1 titres during follow-up helps to predict MN recurrence, and a strong immunosuppressive treatment of anti-PLA2R1 positive patients may prevent recurrence.

[New physiopathological roles for the PLA2R1 receptor in cancer and membranous nephropathy]. / Nouveaux rôles physiopathologiques pour le récepteur PLA2R1 dans le cancer et la glomérulonéphrite extramembraneuse.

PLA2R1 is a large transmembrane receptor of 180-kDa that belongs to the superfamily of C-type lectins. It was discovered because of its high affinity for secreted phospholipases A2 (sPLA2), enzymes that play a key role in lipid mediator synthesis. Early PLA2R1 physiological roles include the clearance of sPLA2 from the extracellular medium and/or promotion of their actions. Over the last four years, two independent studies suggested that PLA2R1 plays a role in cancer as a tumor gene suppressor and is the major target antigen of auto-immune antibodies involved in idiopathic membranous nephropathy, a severe human kidney disease. These novel findings shed light on PLA2R1 and pave the way for its use as a reliable biomarker and an attractive therapeutic target in these diseases.

Optimization of Rituximab Therapy in Adult Patients With PLA2R1-Associated Membranous Nephropathy With Artificial Intelligence.

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.

Patients' preferences regarding choice of end-stage renal disease treatment options.

BACKGROUND: Dialysis registries have reported a low take-up of home treatment. The aim of our study was to report patients' preferred treatment options for end-stage renal disease (ESRD) after information delivery, patients' characteristics by treatment preference, and the reasons for differences between treatment preference and the treatment delivered. METHODS: A prospective cohort study on patients seen in our nephrology department between January 2009 and June 2011 included all patients with chronic kidney disease (GFR <20 ml/min/1.73 m(2)) and incident dialysis patients who received an information program about ESRD treatment options. RESULTS: 228 patients received information delivery and either expressed a preference for a given renal replacement therapy (peritoneal dialysis, PD: 42%; hemodialysis, HD: 33%), remained undecided (20%) or expressed reluctance to undergo renal replacement therapy (5%). Multivariate analysis revealed that compared to HD preference, patients preferring PD were older (OR 1.02, 95% CI 1.0-1.04), had a lower BMI (OR 0.9, 95% CI 0.87-0.98) and were more likely to have been informed before rather than after starting dialysis (OR 3.4, 95% CI 1.5-7.4); home treatment was the main reason given for preferring PD. Undecided patients were mainly women and the majority were eventually treated by HD. Reluctant patients were the oldest (OR 1.12, 95% CI 1.02-1.22) and were rarely treated by dialysis. Only 24% of patients informed before and 8% of patients informed after starting dialysis were ultimately treated with PD. Reasons for a mismatch between dialysis modality preference and treatment delivered were equally distributed between medical and nonmedical. CONCLUSION: Patients should be systematically informed before starting dialysis, patients' preferences should be taken into account before organizing dialysis and all treatment modalities should be available in all centers.

Diagnostic significance of antineutrophil cytoplasmic antibody (ANCA) titres: a retrospective case-control study.

OBJECTIVES: To investigate the reliability of elevated titres of antineutrophil cytoplasmic antibody (ANCA) and to identify a cut-off titre in discriminating between ANCA-associated vasculitides (AAV) and its mimickers. METHODS: This retrospective observational single-centre study included patients over 18 years with positive myeloperoxidase (MPO)-ANCA and/or proteinase 3 (PR3)-ANCA immunoassays over an 8-year period (January 2010 to December 2018), via their electronic medical files. Patients were classified according to the 2022 ACR/EULAR criteria and alternative diagnoses categorised either as non-AAV autoimmune disorders (ANCA-AI) or disorders without autoimmune features (ANCA-O). Findings from the AAV group were compared with those of ANCA-AI and ANCA-O groups and followed by a multivariate logistic stepwise regression analysis of features associated with AAV. RESULTS: 288 ANCA-positive patients of which 49 had AAV were altogether included. There was no difference between patients between the ANCA-AI (n=99) and the ANCA-O (n=140) groups. The AUC for titres discriminating AAV from mimickers was 0.83 (95% CI, 0.79 to 0.87). The best threshold titre, irrespective of PR3-ANCA or MPO-ANCA, was 65 U/mL with a negative predictive value of 0.98 (95% CI, 0.95 to 1.00). On multivariate analysis, an ANCA titre ≥65 U/mL was independently associated with AAV with an OR of 34.21 (95% CI 9.08 to 129.81; p<0.001). Other risk factors were: pulmonary fibrosis (OR, 11.55 (95% CI, 3.87 to 34.47, p<0.001)), typical ear nose and throat involvement (OR, 5.67 (95% CI, 1.64 to 19.67); p=0.006) and proteinuria (OR, 6.56 (95% CI, 2.56 to 16.81; p<0.001)). CONCLUSION: High PR3/MPO-ANCA titres can help to discriminate between AAV and their mimickers in patients presenting with small-calibre vasculitides, with a threshold titre of 65 U/mL and above.

Kappa Free Light Chain Index Predicts Disease Course in Clinically and Radiologically Isolated Syndromes.

BACKGROUND AND OBJECTIVES: To evaluate whether the kappa free light chain index (K-index) can predict the occurrence of new T2-weighted MRI lesions (T2L) and clinical events in clinically isolated syndrome (CIS) and radiologically isolated syndrome (RIS). METHODS: All consecutive patients presenting for the diagnostic workup, including CSF analysis, of clinical and/or MRI suspicion of multiple sclerosis (MS) since May 1, 2018, were evaluated. All patients diagnosed with CIS and RIS with at least 1-year follow-up were included. Clinical events and new T2L were collected during follow-up. The K-index performances in predicting new T2L and a clinical event were evaluated using time-dependent ROC analyses. The time to clinical event or new T2L was estimated using survival analysis according to the binarized K-index using an independent cutoff of 8.9, and the ability of each variable to predict outcomes was compared using the Harrell c-index. RESULTS: One hundred and eighty two patients (146 CIS and 36 RIS, median age 39 [30; 48] y-o, 70% females) were included with a median follow-up of 21 [13, 33] months. One hundred five (58%) patients (85 CIS and 20 RIS) experienced new T2L, and 28 (15%; 21 CIS and 7 RIS) experienced a clinical event. The K-index could predict new T2L over time in CIS (area under the curve [AUC] ranging from 0.86 to 0.96) and in RIS (AUC ranging from 0.84 to 0.54) but also a clinical event in CIS (AUC ranging from 0.75 to 0.87). Compared with oligoclonal bands (OCBs), the K-index had a better sensitivity and a slight lower specificity in predicting new T2L and clinical events in both populations. In the predictive model, the K-index was the variable that best predict new T2L in both CIS and RIS but also clinical events in CIS (c-index ranging from 0.70 to 0.77), better than the other variables, including OCB. DISCUSSION: This study provides evidence that the K-index predicts new T2L in CIS and RIS but also clinical attack in patients with CIS. We suggest adding the K-index in the further MS diagnosis criteria revisions as a dissemination-in-time biomarker.

Scientific Integrity Requires Publishing Rebuttals and Retracting Problematic Papers.

Recently, an article by Seneff et al. entitled "Innate immunosuppression by SARS-CoV-2 mRNA vaccinations: The role of G-quadruplexes, exosomes, and MicroRNAs" was published in Food and Chemical Toxicology (FCT). Here, we describe why this article, which contains unsubstantiated claims and misunderstandings such as "billions of lives are potentially at risk" with COVID-19 mRNA vaccines, is problematic and should be retracted. We report here our request to the editor of FCT to have our rebuttal published, unfortunately rejected after three rounds of reviewing. Fighting the spread of false information requires enormous effort while receiving little or no credit for this necessary work, which often even ends up being threatened. This need for more scientific integrity is at the heart of our advocacy, and we call for large support, especially from editors and publishers, to fight more effectively against deadly disinformation.

Immune response to BNT162b2 SARS-CoV-2 vaccine in patients living with HIV: The COVIH-DAPT study.

Introduction: Data on immune response to SARS-CoV-2 vaccine in patients living with HIV (PLWH) over a period longer than 3 months are currently limited. We measured the immune response after BNT162b2 vaccination against SARS-CoV-2 in this population. Methods: We prospectively enrolled PLWH on successful antiretroviral therapy, initiating vaccination with two doses of the BNT162b2 SARS-CoV-2 vaccine administered at six-week interval. SARS-CoV-2 humoral and cellular responses and lymphocyte cell subsets were recorded at inclusion and 6 weeks (W6), 3 months (M3) and 6 months (M6) later. Humoral, humoral strong and cellular responders were defined by IgG titers >10, ≥264BAU/mL and IFN-γ T cell release, respectively. Results: Nineteen subjects without SARS-CoV-2 infection were included (74% men, mean age 51 years, CD4 nadir 399/mm3). All subjects were humoral responders, their antibody titer peak reached at M3. Strong responders' rates were 63% and 21% at M3 and M6, respectively. CD19+CD10+ B cells had increased significantly at W6 then decreased at M3, while CD19+CD27+ B cells remained unchanged. Rates of patients with a cellular response increased from 39% at W6 to 69% at M6. Cellular responders had significantly higher CD3+, CD4+ and CD8+ Effector Memory cells at inclusion (p=0.048, p=0.024, p=0.012, respectively) and CD4+ Terminally Differentiated Effector Memory cells at M3 (p=0.044). Discussion: PLWH have a robust immune response after SARS-CoV-2 vaccination, but a rapid decline in humoral response from 3 months onwards, due to a blunted memory B cell response. Analysis of lymphocyte subsets may help identify optimal times for vaccine boosters.

Breakthrough infections due to SARS-CoV-2 Delta variant: relation to humoral and cellular vaccine responses.

Introduction: COVID-19 vaccines are expected to provide effective protection. However, emerging strains can cause breakthrough infection in vaccinated individuals. The immune response of vaccinated individuals who have experienced breakthrough infection is still poorly understood. Methods: Here, we studied the humoral and cellular immune responses of fully vaccinated individuals who subsequently experienced breakthrough infection due to the Delta variant of SARS-CoV-2 and correlated them with the severity of the disease. Results: In this study, an effective humoral response alone was not sufficient to induce effective immune protection against severe breakthrough infection, which also required effective cell-mediated immunity to SARS-CoV-2. Patients who did not require oxygen had significantly higher specific (p=0.021) and nonspecific (p=0.004) cellular responses to SARS-CoV-2 at the onset of infection than those who progressed to a severe form. Discussion: Knowing both humoral and cellular immune response could allow to adapt preventive strategy, by better selecting patients who would benefit from additional vaccine boosters. Trial registration numbers: https://clinicaltrials.gov, identifier NCT04355351; https://clinicaltrials.gov, identifier NCT04429594.

Kappa Free Light Chain Biomarkers Are Efficient for the Diagnosis of Multiple Sclerosis: A Large Multicenter Cohort Study.

BACKGROUND AND OBJECTIVES: Kappa free light chains (KFLC) seem to efficiently diagnose MS. However, extensive cohort studies are lacking to establish consensus cut-offs, notably to rule out non-MS autoimmune CNS disorders. Our objectives were to (1) determine diagnostic performances of CSF KFLC, KFLC index, and KFLC intrathecal fraction (IF) threshold values that allow us to separate MS from different CNS disorder control populations and compare them with oligoclonal bands' (OCB) performances and (2) to identify independent factors associated with KFLC quantification in MS. METHODS: We conducted a retrospective multicenter study involving 13 French MS centers. Patients were included if they had a noninfectious and nontumoral CNS disorder, eligible data concerning CSF and serum KFLC, albumin, and OCB. Patients were classified into 4 groups according to their diagnosis: MS, clinically isolated syndrome (CIS), other inflammatory CNS disorders (OIND), and noninflammatory CNS disorder controls (NINDC). RESULTS: One thousand six hundred twenty-one patients were analyzed (675 MS, 90 CIS, 297 OIND, and 559 NINDC). KFLC index and KFLC IF had similar performances in diagnosing MS from nonselected controls and OIND (p = 0.123 and p = 0.991 for area under the curve [AUC] comparisons) and performed better than CSF KFLC (p < 0.001 for all AUC comparisons). A KFLC index of 8.92 best separated MS/CIS from the entire nonselected control population, with better performances than OCB (p < 0.001 for AUC comparison). A KFLC index of 11.56 best separated MS from OIND, with similar performances than OCB (p = 0.065). In the multivariate analysis model, female gender (p = 0.003), young age (p = 0.013), and evidence of disease activity (p < 0.001) were independent factors associated with high KFLC index values in patients with MS, whereas MS phenotype, immune-modifying treatment use at sampling, and the FLC analyzer type did not influence KFLC index. DISCUSSION: KFLC biomarkers are efficient tools to separate patients with MS from controls, even when compared with other patients with CNS autoimmune disorder. Given these results, we suggest using KFLC index or KFLC IF as a criterion to diagnose MS. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that KFLC index or IF can be used to differentiate patients with MS from nonselected controls and from patients with other autoimmune CNS disorders.

Advances in the Management of Primary Membranous Nephropathy and Rituximab-Refractory Membranous Nephropathy.

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.