Citations

Background: Optic neuritis (ON) is often associated with multiple sclerosis (MS). Early diagnosis is critical to optimal patient management. Objective: To estimate the incidence of acute ON and the rates of conversion to MS and antibody-mediated ON. Method: Population-based prospective study was performed in patients with ON from three ophthalmological departments and 44 practicing ophthalmologists from 2014 to 2016. Ophthalmological and neurological examination, magnetic resonance imaging (MRI), determination of aquaporin-4(AQP4)-IgG and myelin-oligodendrocyte glycoprotein (MOG)-IgG were investigated blindly. Results: In all, 63 patients were evaluated and 51 fulfilled the criteria for ON. All were Caucasian, with female:male ratio of 2.2:1 and a median age of 38 years (16–66); 44 (86%) had a single episode of ON (four bilateral), while 7/51 (14%) had recurrent ON. The overall age-specific incidence was 3.28 (2.44–4.31) per 100,000 person years, 2.02 for men and 4.57 for women. At follow-up, 20 patients met the diagnostic criteria for MS, MRI lesions disseminated in space and time in 17/20 patients. AQP4-IgG was detected in none, MOG-IgG was detected in two patients. Conclusion: The prospective incidence of ON was estimated. MRI enabled a diagnosis of MS in a subgroup of patients. Antibody-mediated ON with specificity for MOG was detected in 4% of cases.

Background: Serum immunoglobulin G targeting the astrocyte water channel aquaporin-4 (AQP4) in the central nervous system (CNS) is a biomarker for neuromyelitis optica spectrum disease (NMOSD). Co-existence of NMOSD with systemic lupus erythematosus (SLE) putatively suggests susceptibility to antibody-mediated autoimmune disease. Objective: To estimate the prevalence of NMOSD in SLE and investigate the immunogenetic background for an association of NMOSD and SLE. Methods: The study included a predominantly population-based cohort with clinical and serological investigations of 208 patients with SLE, followed prospectively since 1995. All patients received immunosuppressive treatment. NMOSD was evaluated retrospectively based on the 2015 International Panel for NMOSD Diagnosis (IPND) criteria. Polymorphisms in programmed cell death protein 1 (PDCD-1) PD-1.3 G/A were genotyped. AGP4-IgG and other autoantibodies, including myelin oligodendrocyte glycoprotein (MOG), was determined blinded to clinical diagnosis. Results: Of 208 patients with SLE, 45(22%) had neuropsychiatric (NP) SLE, and CNS involvement predominated in 30 of 45 (67%) patients. Serum AQP4-IgG was detected in 2 of 30 (6.7%) neuropsychiatric SLE (NPSLE) patients both of whom had myelitis and antiphospholipid syndrome; one patient also had myasthenia gravis. None had MOG-IgG. PD-1.3A allele was not associated with SLE nor with NPSLE. Conclusion: AQP4-IgG autoimmune syndrome may rarely co-exist with SLE, and such patients have other NMOSD-typical syndromes such as myelitis.

Abstract Aquaporin‐4 ( AQP 4) is a water channel protein that is most highly, but not exclusively, expressed in the central nervous system. In 2005 AQP 4 was shown to be the antigenic target of neuromyelitis optica‐immunoglobulin G ( NMO ‐IgG, or AQP 4‐IgG), an antibody found specifically in patients with NMO and in formes frustes of NMO , such as longitudinally extensive transverse myelitis (LETM) or optic neuritis (ON). This discovery facilitated the clinical, pathological, and radiological distinction of NMO and the spectrum of NMO ‐related disorders from classical multiple sclerosis. In addition to its use as a diagnostic tool, AQP 4‐IgG predicts a high risk of relapse in patients with a clinically isolated syndrome of either LETM or ON. As disability in NMO is attack‐related, early diagnosis and treatment are predicted to have a major effect on long‐term disability. Thus, the importance of sensitive and specific assays to detect AQP 4‐IgG cannot be overstated. Both academic institutions and commercial companies have developed assays to identify AQP 4‐IgG in patients' sera or cerebrospinal fluid. Both AQP 4 isoforms from different species have been used as the antigenic target in the form of frozen tissue sections in indirect immunofluorescence assays, partially purified protein for fluorescence immunoprecipitation assay, radioimmunoprecipitation assay or enzyme‐linked immunosorbent assay, or transfected into cells for cell based assays or flow cytometry. We carried out a systematic review of the literature reporting different methodologies used to identify AQP 4‐IgG, examine whether longitudinal AQP 4‐IgG titers predict relapses in seropositive patients, and attempt to establish a reasonable timeframe for retesting negative serum samples.