Deciphering the Reactivity of Autoantibodies Directed against the RNP-A, -C and 70 kDa Components of the U1-snRNP Complex: "Double or Nothing"?

Background: The positivity of anti-RNP autoantibodies as biological criteria for the diagnosis of mixed connective tissue disease (MCTD) has recently divided the rheumatology community. Autoantigenicity of the U1-snRNP complex tends to generate multiple autoantibodies against RNP-A, -C and -70 KDa or Sm proteins. The aim of this study is to identify the most informative autoantibodies in clinical practice, in particular, to contribute to differential diagnosis between MCTD and systemic lupus erythematosus (SLE). Methods: Sera from 74 patients positive for anti-RNP autoantibodies were selected over a period of one year of laboratory practice. Autoantibodies directed against extractable nuclear antigen, RNP proteins (A, C, 70 KDa) and 40 kDa fragments of RNP-70 KDa were investigated by using quantitative fluoroenzymatic assay and Western blot analysis. Results: Among the 74 patients, 40 patients were diagnosed with SLE, 20 with MCTD, six with another autoimmune disease, three with SARS-CoV-2 infection, three with cancer and two were healthy. No preferential clinical association of IgG or IgM autoantibodies directed against each of the RNP proteins was found between SLE and MCTD. In contrast, the proportion of autoantibodies directed against the RNP component within the U1-snRNP complex showed a significantly higher RNP index in patients with MCTD than in those with SLE (p = 0.011), with good performance (sensitivity: 69.2%, specificity: 88.9%). Conclusions: The analysis of the proportion of the different autoantibodies directed against the U1-snRNP complex is more informative than the analysis of each autoantibody separately. A follow-up of patients could be informative about the interest of the RNP index as a predictor of disease evolution.

Biopsy-proven kidney involvement in hypocomplementemic urticarial vasculitis.

BACKGROUND: Hypocomplementemic urticarial vasculitis (HUV) is a rare systemic vasculitis. We aimed to describe the kidney involvement of HUV in a multicenter national cohort with an extended follow-up. METHODS: All patients with HUV (international Schwartz criteria) with a biopsy-proven kidney involvement, identified through a survey of the French Vasculitis Study Group (FVSG), were included. A systematic literature review on kidney involvement of HUV was performed. RESULTS: Twelve patients were included, among whom 8 had positive anti-C1q antibodies. All presented with proteinuria, from mild to nephrotic, and 8 displayed acute kidney injury (AKI), requiring temporary haemodialysis in 2. Kidney biopsy showed membrano-proliferative glomerulonephritis (MPGN) in 8 patients, pauci-immune crescentic GN or necrotizing vasculitis in 3 patients (with a mild to severe interstitial inflammation), and an isolated interstitial nephritis in 1 patient. C1q deposits were observed in the glomeruli (n = 6), tubules (n = 4) or renal arterioles (n = 3) of 8 patients. All patients received corticosteroids, and 9 were also treated with immunosuppressants or apheresis. After a mean follow-up of 8.9 years, 6 patients had a preserved renal function, but 2 patients had developed stage 3-4 chronic kidney disease (CKD) and 4 patients had reached end-stage kidney disease (ESKD), among whom 1 had received a kidney transplant. CONCLUSION: Renal involvement of HUV can be responsible for severe AKI, CKD and ESRD. It is not always associated with circulating anti-C1q antibodies. Kidney biopsy shows mostly MPGN or crescentic GN, with frequent C1q deposits in the glomeruli, tubules or arterioles.

Lung involvement associated with anti-NXP2 autoantibodies in inflammatory myopathies: a French monocenter series.

BACKGROUND: Inflammatory myopathies (IM) are characterized by muscular inflammation that can be associated with systemic disorders including lung. Anti-NXP2 antibody (Ab) is a rare myositis-specific antibody and its association with pulmonary involvement is still unknown. In this study, we investigated the characteristics of lung disease in patients with IM associated with anti-NXP2 Ab. METHODS: Adult patients with confirmed IM and positive anti-NXP2 antibodies were recruited in our University departments (Assistance Publique- Hôpitaux de Marseille, France), between 2015 and 2019 to perform a retrospective study. RESULTS: Seven patients were identified. Mean age was 55 ± 13 years, with a predominance of females (71%). Two patients (29%) had respiratory symptoms. CT-scan shows abnormalities in three patients (organizing pneumonia, nonspecific interstitial pneumonia, and bilateral pleural effusion). An altered diffusing capacity for carbon monoxide was found in four patients. CONCLUSION: We observed that subclinical lung involvement is not rare in patients with IM associated with positive anti-NXP2 Ab, with various radiological patterns and a significant lung function defect. Such data deserve to be known by the pulmonologist in order to perform a complete lung screening in all patients with positive anti-NXP2 antibody and to detect earlier a concomitant lung impairment.

Monitoring of infliximab trough levels and anti-infliximab antibodies in inflammatory bowel diseases: A comparison of three commercially available ELISA kits.

BACKGROUND: There are many studies presenting data of biologics and several ELISA kits commercially available for monitoring infliximab serum trough levels (s-IFXt) and anti-drug antibodies (ADAb). We propose to compare technical characteristics and results of three different assays on a cohort of 35 patients under infliximab (IFX) and suffering from inflammatory bowel disease (IBD). PATIENTS AND METHODS: s-IFXt and ADAb were systematically measured with three ELISA kits: Lisa-Tracker® Duo infliximab (Theradiag®), Ridascreen® IFX Monitoring (R-Biopharm AG®) and Promonitor® IFX (Progenika Biopharma SA®). RESULTS: The main technical features that differed between kits for measuring s-IFXt were: (i) TNF coating, (ii) immune complexes revelation strategy and/or (iii) interference with other anti-TNFα agents. For kits measuring ADAb, they were revelation steps and unit of results. There was an excellent mathematical correlation of s-IFXt between assays however Bland-Altman analysis denoted (i) s-IFXt were on average 48 to 69% higher in Ridascreen® than in the other two assays, and (ii) elevated s-IFXt were higher with Promonitor® compared to Lisa-Tracker®. As a consequence, there were some substantial discrepancies between assays for classification of s-IFXt into concentration ranges. Despite unstandardized units, pairwise qualitative comparison showed a perfect agreement between the three pairs of ADAb assays. CONCLUSION: Our data show that the evaluated assays are not quantitatively interchangeable due to substantial variations in some results that could lead, for some patients, to divergent therapeutic decisions. We remind to be cautious when comparing study results issued from different kits and recommend using the same assay for the longitudinal follow-up of IBD patients.

Systemic Lupus Erythematosus and Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Overlap Syndrome in Patients With Biopsy-Proven Glomerulonephritis.

The aim of the study was to report the clinical, biological, and pathological characteristics of patients with glomerulonephritis (GN) secondary to systemic lupus erythematosus (SLE)/antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) overlap syndrome.A nationwide survey was conducted to identify cases of SLE/AAV overlap syndrome. Data were collected from SLE and AAV French research groups. Inclusion criteria were diagnosis of both SLE and AAV according to international classification criteria and biopsy-proven GN between 1995 and 2014. Additional cases were identified through a systematic literature review. A cohort of consecutive biopsy-proven GN was used to study the prevalence of overlapping antibodies and/or overlap syndrome.The national survey identified 8 cases of SLE/AAV overlap syndrome. All patients were female; median age was 40 years. AAV occurred before SLE (n = 3), after (n = 3), or concomitantly (n = 2). Six patients had rapidly progressive GN and 3/8 had alveolar hemorrhage. All patients had antinuclear antibodies (ANA); 7/8 had p-ANCA antimyeloperoxidase (MPO) antibodies. Renal biopsies showed lupus nephritis (LN) or pauci-immune GN. Remission was obtained in 4/8 patients. A literature review identified 31 additional cases with a similarly severe presentation. In the GN cohort, ANCA positivity was found in 30% of LN, ANA positivity in 52% of pauci-immune GN, with no correlation with pathological findings. The estimated prevalence for SLE/AAV overlap syndrome was 2/101 (2%).In patients with GN, SLE/AAV overlap syndrome may occur but with a low prevalence. Most patients have an aggressive renal presentation, with usually both ANA and anti-MPO antibodies. Further studies are needed to assess shared pathogenesis and therapeutic options.

TWEAK-binding autoantibodies are generated during psoriatic arthritis and are not influenced by anti-TNF therapy.

BACKGROUND: TNF weakly inducer of apoptosis (TWEAK) is member of the TNF ligand superfamily. Various data support that TWEAK produced by synovial macrophages may contribute to synovitis observed in psoriatic arthritis (PsoA). In PsoA, anti-TNF therapy has been successful in agreement with the key role of TNF in the pathogenesis and the generation by PsoA patients of anti-TNF autoantibodies referred as "beneficial autoimmunity to pro-inflammatory mediators". However, the role of TNF-alpha in the regulation of TWEAK modulation of inflammation during PsoA remains unknown. METHODS: We have studied level course during anti-TNF therapy of serum soluble TWEAK. In the same cohort, we have investigated the generation of TWEAK-binding autoantibodies by PsoA patients before and after anti-TNF therapy. RESULTS: Patients with PsoA had significantly higher serum levels of TWEAK compared with controls [respective means (±SEM) were 645 pg/ml (64) and 467 pg/ml (23); (p = 0.006)] but serum soluble TWEAK levels were not correlated with BASDAI (Spearman's coefficients <0.003, p > 0.05). Our study showed that soluble TWEAK levels were not modulated by etanercept therapy [respective Means (±SEM) were 605 (95) (week 12) and 744 (97) (week 24) pg/ml; (p > 0.23)]. Anti-TWEAK autoantibodies were detected in 9/13 (69.2 %) PsoA patients at inclusion and only in 3/57 (5.3 %) healthy blood donors (p < 0.0001). These circulating antibodies were persistent in PsoA patients and detected at similar levels during etanercept therapy. Moreover we showed that they had a down regulating effect on CCL-2 secretion by endothelial cells stimulated by rh TWEAK in vitro. CONCLUSION: Our study revealed that during psoriatic arthritis (1) serum TWEAK was up regulated and (2) TWEAK-binding autoantibodies are generated. Both parameters were not influenced by anti-TNF therapy and persisted at high levels during anti-TNF therapy. For the first time we described here TWEAK-binding IgG autoantibodies with a down regulating effect on CCL-2 secretion by endothelial cells stimulated by rh TWEAK in vitro. Finally, our results suggest that TWEAK may be involved in PsoA pathogeny. Trial registration This clinical trial was approved by the local Ethics Committee "Comité de Protection des Personnes Sud-Méditerranée V" with the registration number: 2011-002954-29, and French health minister registration number AFSSAPS A110784-42 obtained the 08/22/2011. This clinical trial is registered in Clinical trial.gov under the number: NCT02164214.

Heterogeneous clinical spectrum of anti-SRP myositis and importance of the methods of detection of anti-SRP autoantibodies: a multicentric study.

Anti-signal recognition particle (SRP) antibodies are important serological markers for the diagnosis and the prognosis of idiopathic inflammatory myopathy (IIM), especially to distinguish immune-mediated necrotizing myopathy (IMNM). This study was set up to investigate the phenotype associated with anti-SRP antibodies and to evaluate the methods for detecting these antibodies. Clinical and biological data were retrospectively obtained from 60 adult patients with anti-SRP antibodies detected by a dot immunoassay from 12 centers. Thirty-six (60 %) out of these 60 patients suffered from an IIM, and among them, 21 patients were diagnosed as IMNM. Among patients with a definite IIM, proximal weakness and myalgia were prominent symptoms at the time of diagnosis. Only few patients displayed severe extra-muscular symptoms such as cardiac involvement or severe myositis. Mean creatine kinase levels were high for all patients except for two of them. When testing by indirect immunofluorescence (IIF) on HEp2 cells, the fraction of patients displaying the typical anti-SRP fine speckled staining of the cytoplasm was higher in patients with IIM (30/36) (83 %) than in patients with non-IIM (3/24) (12.5 %) (p < 0.0001). Thirty (91 %) out of 33 patients with a positive immunodot and a characteristic IIF cytoplasmic staining suffered from a clinical definite myositis, whereas only 6 (22 %) out of 27 patients with a positive immunodot but a negative cytoplasmic pattern suffered from a myositis (p < 0.00001). This series highlights the strong heterogeneity of anti-SRP positivity that encompassed IMNM and non-IMNM and supports the necessity of considering both IIF and dot immunoassay to confirm the diagnosis of anti-SRP-associated myositis.

Antinuclear Antibodies in Patients with Psoriatic Arthritis Treated or Not with Biologics.

BACKGROUND: With the emergence of biotherapies, accurate diagnosis in early arthritis is needed. At this time, there is no biological marker of psoriatic arthritis. OBJECTIVE: To test whether antinuclear antibodies (ANA) can be used as a diagnostic tool in psoriatic arthritis (PsA), we evaluated the prevalence of ANA in biologic-naïve PsA patients and in healthy blood donors. METHODS: 232 patients from the Rheumatology department, St Marguerite's Hospital, Marseilles, who fulfilled the CASPAR criteria for PsA, underwent clinical and laboratory investigations. Antinuclear antibodies (ANA), anti-extractable nuclear antigen antibodies (ENA), rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) were assayed. Ninety-one healthy blood donors were also tested. RESULTS: Detection of ANA by indirect immunofluorescence was significantly more frequent in sera from PsA patients than those from controls at serum dilution of 1:100 (57% compared with 40%, Odds Ratio (OR) 1.98 (1.2-3.4) p<0.02) and 1:160 (52% compared with 24%, OR 3,7 (1.9-7.2) p<0.001). No patients had lupus specific autoantibodies, 15 % had RF (34/232), and 1.7 % had ACPA (4/232). CONCLUSIONS: Detection of ANA was more frequent in sera from PsA patients than in those from healthy controls. This suggests that ANA could be a diagnosis orientation tool in PsA. Nevertheless, the specificity of these antibodies still remains to be investigated.

Targeting tissular immune response improves diagnostic performance of anti-Saccharomyces cerevisiae antibodies (ASCA) in Crohn's disease.

Antibodies against Saccharomyces cerevisiae (ASCA) and Escherichia coli outer membrane porin C (anti-OmpC) are known to be detectable in the serum of patients with Crohn's disease (CD) but display a very poor sensitivity for the disease especially in forms with isolated colonic involvement. In this study we aimed at evaluating performances of these markers in supernatant of cultured colonic biopsies. Patients with colonic CD (n =  67), ulcerative colitis (UC) (n = 35) and control individuals (n = 37) were prospectively recruited for colonoscopy pinch biopsies and blood sampling. Serum and supernatant of culture tissues were analyzed for ASCA and anti-OmpC. Direct immunofluorescence was also performed on colonic tissues for total IgA detection. We detected for the first time ASCA IgA/IgG and anti-OmpC IgA in cultured colonic tissue supernatants. For both markers, sensitivities for diagnosing CD were better in supernatants (ASCA: 53.7%, anti-OmpC: 28.4%) than in serum (ASCA: 31.3%, anti-OmpC: 22.4%). Combination of results from a panel of these tests gave the greatest sensitivity ever described for CD diagnosis in colonic forms (70.2%). In this study, we described, for the first time, ASCA in supernatant of colonic tissue cultures. This assaying approach in CD diagnosis should be taken into consideration in the future especially in CD forms with isolated colonic involvement.

Anti-mitochondrial-2 antibodies (anti-PDC-E2): a marker for autoimmune hepatitis of children?

In an 8-year-old boy with biochemical hepatic disorders, an histological examination of a liver biopsy showed a severe chronic hepatitis without cirrhosis. The biliary tract was normal and no toxic or infectious etiologies were found. Spontaneous improvement of the clinical status was observed in the following weeks but biochemical abnormalities were persistent and a second episode occurred 3 years after. Immunological studies showed anti-mitochondrial-2 antibodies (AMA-2) confirmed by an immunoblot performed with rat mitochondrial proteins resolved by two-dimensional electrophoresis. We described here the second case in the literature of paediatric autoimmune hepatitis associated with well documented AMA-2.

Small size new silastic drains: life-threatening hypovolemic shock after thoracic surgery associated with a non-functioning chest tube.

We report a case of a massive haemothorax following bilateral surgical resection of apical bullae. Occult bleeding was not recognized until the onset of a life-threatening circulatory collapse associated with metabolic acidosis and a fall in haemoglobin level. Using a thoracotomy, large amounts of blood were evacuated from the thoracic cavity and bleeding originating from ruptured pleural adhesion was easily controlled. Thrombotic material with talc particles was found to obstruct the 19-French 4-channel Blake drain. Although this new silastic Blake tube has been recommended in cardiac surgical patients, extending its indication in thoracic surgery, particularly when talc pleurodesis is used, should be questioned given the enhanced postoperative prothrombotic state and risk of drain obstruction. In conclusion, caution should be exercised when new small-sized material is introduced in clinical practice, especially after talc pleurodesis following thoracic surgery.