Differential binding of autoantibodies to MOG isoforms in inflammatory demyelinating diseases

Objective: To analyze serum immunoglobulin G (IgG) antibodies to major isoforms of myelin oligodendrocyte glycoprotein (MOG-alpha 1-3 and beta 1-3) in patients with inflammatory demyelinating diseases. Methods: Retrospective case-control study using 378 serum samples from patients with multiple sclerosis (MS), patients with non-MS demyelinating disease, and healthy controls with MOG alpha-1-IgG positive (n = 202) or negative serostatus (n = 176). Samples were analyzed for their reactivity to human, mouse, and rat MOG isoforms with and without mutations in the extracellular MOG Ig domain (MOG-ecIgD), soluble MOG-ecIgD, and myelin from multiple species using live cell-based, tissue immunofluorescence assays and ELISA. Results: The strongest IgG reactivities were directed against the longest MOG isoforms alpha-1 (the currently used standard test for MOG-IgG) and beta-1, whereas the other isoforms were less frequently recognized. Using principal component analysis, we identified 3 different binding patterns associated with non-MS disease: (1) isolated reactivity to MOG-alpha-1/beta-1 (n = 73), (2) binding to MOG-alpha-1/beta-1 and at least one other alpha, but no beta isoform (n = 64), and (3) reactivity to all 6 MOG isoforms (n = 65). The remaining samples were negative (n = 176) for MOG-IgG. These MOG isoform binding patterns were associated with a non-MS demyelinating disease, but there were no differences in clinical phenotypes or disease course. The 3 MOG isoform patterns had distinct immunologic characteristics such as differential binding to soluble MOG-ecIgD, sensitivity to MOG mutations, and binding to human MOG in ELISA. Conclusions: The novel finding of differential MOG isoform binding patterns could inform future studies on the refinement of MOG-IgG assays and the pathophysiologic role of MOG-IgG

KCNA2 IgG autoimmunity in neuropsychiatric diseases

http://dx.doi.org/10.13039/501100001674 Fondation Leducqhttp://dx.doi.org/10.13039/501100002347 Bundesministerium für Bildung und Forschunghttp://dx.doi.org/10.13039/501100009318 Helmholtz Associationhttp://dx.doi.org/10.13039/100016021 Corona-Stiftunghttp://dx.doi.org/10.13039/501100001659 Deutsche Forschungsgemeinschafthttp://dx.doi.org/10.13039/501100000780 European Commissio

Finite element analysis of stiffened plates

The paper presents the development of a new plate/shell stiffener element and the subsequent application in determine frequencies, mode shapes and buckling loads of different stiffened panels. In structural modelling, the plate and the stiffener are treated as separate finite elements where the displacement compatibility transformation takes into account the torsion - flexural coupling in the stiffener and the eccentricity of internal (contact) forces between the beam - plate/shell parts. The model becomes considerably more flexible due to this coupling technique. The development of the stiffener is based on a general beam theory, which includes the constraint torsional warping effect and the second order terms of finite rotations. Numerical tests are presented to demonstrate the importance of torsion warping constraints. As part of the validation of the results, complete shell finite element analyses were made for stiffened plates

Antibodies against neural antigens in patients with acute stroke: joint results of three independent cohort studies

Background and purpose: Ischemic stroke (IS) and hemorrhagic stroke (HemS) typically lead to a breakdown of the blood–brain barrier with neural antigen presentation. This presentation could potentially generate destructive auto-immune responses. Pre-existing antineuronal and antiglial antibodies (AA), predominantly NMDA receptor antibodies, have been reported in patients with stroke. This article summarizes three independent prospective studies, the Lübeck cohort (LC), Barcelona cohort (BC), and Heidelberg cohort (HC), exploring the frequency and clinical relevance of AA in patients with acute stroke (AS). Methods: In all cohorts together, 344 consecutive patients admitted with AS (322 × IS, 22 × HemS) were screened for AA in serum at admission. Clinical outcome parameters as well as a second AA screening were available at 30 days in the LC or at 90 days in the BC. A control group was included in the BC (20 subjects free from neurological disease) and the HC (78 neurological and ophthalmological patients without evidence for stroke). Results: The rate of positivity for AA was similar in control subjects and AS patients (13%, 95% CI [7%, 22%] vs. 13%, 95% CI [10%, 17%]; p = 0.46) with no significant difference between cohorts (LC 25/171, BC 12/75, HC 9/98). No patient had developed new AA after 30 days, whereas 2 out of 60 patients had developed new AA after 90 days. AA positive patients did not exhibit significant differences to AA negative patients in stroke subtype (LC, BC), initial stroke severity (BC, LC, HC), infarct volume (BC), and functional status at admission (BC, LC, HC) and follow-up (BC, LC). Conclusions: AS does not induce AA to a relevant degree. Pre-existing AA can be found in the serum of stroke patients, but they do not have a significant association with clinical features and outcomes.The research leading to these results received funding from the European Union’s Seventh Framework Program FP7 under Grant Agreement 607962 (nEUROinflammation) and from the ISCIII-Subdirección General de Evaluación (FIS PI15/00430, PI Prof. Ángel Chamorro) cofinanced by the Fondo Europeo de Desarrollo Regional (FEDER)

Routine detection of serum anti-desmocollin autoantibodies is only useful in patients with atypical pemphigus

Autoantibodies against the 3 desmocollin (Dsc; Dsc1-Dsc3) isoforms have been described in different pemphigus variants. Here, we developed state-of-the-art detection systems for serum anti-Dsc1, Dsc2 and Dsc1 IgG and IgA. These assays were applied in 5 different cohorts including pemphigus vulgaris (PV) patients with compatible direct immunofluorescence (IF) microscopy but no reactivity against desmogleins 1 and 3 (n = 24) and sera from patients with autoimmune blistering diseases with positive direct IF microscopy taken at the time of diagnosis (n = 749). We found that detection of anti-Dsc serum reactivity is not helpful in the routine diagnosis of PV, pemphigus foliaceus and paraneoplastic pemphigus but may be valuable in pemphigus vegetans

Anti-GP2 IgA autoantibodies are associated with poor survival and cholangiocarcinoma in primary sclerosing cholangitis

Objective: Pancreatic autoantibodies (PABs), comprising antibodies against glycoprotein 2 (anti-GP2), are typically associated with complicated phenotypes in Crohn's disease, but have also been observed with variable frequencies in patients with UC. In a previous study, we observed a high frequency of primary sclerosing cholangitis (PSC) in patients with anti-GP2-positive UC. We therefore aimed to characterise the role of anti-GP2 in PSC. Design: In an evaluation phase, sera from 138 well-characterised Norwegian patients with PSC were compared with healthy controls (n=52), and patients with UC without PSC (n=62) for the presence of PABs by indirect immunofluorescence. Further, 180 German patients with PSC served as a validation cohort together with 56 cases of cholangiocarcinoma without PSC, 20 of secondary sclerosing cholangitis (SSC) and 18 of autoimmune hepatitis. Results: Anti-GP2 IgA specifically occurred at considerable rates in large bile duct diseases (cholangiocarcinoma=36%, PSC and SSC about 50%). In PSC, anti-GP2 IgA consistently identified patients with poor survival during follow-up (Norwegian/German cohort: p Log Rank=0.016/0.018). Anti-GP2 IgA was associated with the development of cholangiocarcinoma in both PSC cohorts, yielding an overall OR of cholangiocarcinoma in patients with anti-GP2 IgA-positive PSC of 5.0 (p=0.001). Importantly, this association remained independent of disease duration, bilirubin level and age. Conclusions: Anti-GP2 IgA can be hypothesised as a novel marker in large bile duct diseases. In particular, in PSC, anti-GP2 IgA identified a subgroup of patients with severe phenotype and poor survival due to cholangiocarcinoma. Anti-GP2 IgA may therefore be a clinically valuable tool for risk stratification in PSC. The final version of this research has been published in Hepatology. © 2016 Wile

Intracellular and non-neuronal targets of voltage-gated potassium channel complex antibodies

Objectives Autoantibodies against the extracellular domains of the voltage-gated potassium channel (VGKC) complex proteins, leucine-rich glioma-inactivated 1 (LGI1) and contactin-associated protein-2 (CASPR2), are found in patients with limbic encephalitis, faciobrachial dystonic seizures, Morvan’s syndrome and neuromyotonia. However, in routine testing, VGKC-complex-antibodies without LGI1- or CASPR2-reactivities (“double-negative”) are commoner than LGI1- or CASPR2-specificities. Therefore, the target(s) and clinical associations of double-negative antibodies need to be determined. Methods Sera (n=1131) from several clinically-defined cohorts were tested for IgG-radioimmunoprecipitation of 125I-DTX-labelled VGKC-complexes from mammalian brain extracts. Positive samples were systematically tested for live hippocampal neuron reactivity, IgG-precipitation of 125I-DTX and 125I-DTX-labelled Kv1-subunits, and by cell-based assays which expressed Kv1-subunits, LGI1 and CASPR2. Results VGKC-complex-antibodies were found in 162 of 1131 (14%) sera. Ninety of these (56%) had antibodies targeting the extracellular domains of LGI1 or CASPR2. Of the remaining 72 double-negative sera, ten (14%) immunoprecipitated 125I-DTX itself, and 27 (38%) bound to solubilized co-expressed Kv1.1/1.2/1.6 subunits and/or Kv1.2 subunits alone, at levels proportionate to VGKC-complex-antibody levels (r=0.57, p=0.0017). The sera with LGI1- and CASPR2-antibodies immunoprecipitated neither preparation. None of the 27 Kv1-precipitating samples bound live hippocampal neurons or Kv1-extracellular domains, but 16 (59%) bound to permeabilised Kv1-expressing HEK cells. These intracellular Kv1-antibodies mainly associated with non-immune disease aetiologies, poor longitudinal clinical-serological correlations, and a limited immunotherapy-response. Conclusions Double-negative VGKC-complex-antibodies are often directed against cytosolic epitopes of Kv1-subunits, and occasionally against non-mammalian DTX. These antibodies should no longer be classified as neuronal-surface antibodies. They consequently lack pathogenic potential, and do not in themselves support use of immunotherapies