Predictive Value of Serum Antibodies and Point Mutations of AQP4, AQP1 and MOG in A Cohort of Spanish Patients with Neuromyelitis Optica Spectrum Disorders.

The detection of IgG aquaporin-4 antibodies in the serum of patients with Neuromyelitis optica (NMO) has dramatically improved the diagnosis of this disease and its distinction from multiple sclerosis. Recently, a group of patients have been described who have an NMO spectrum disorder (NMOsd) and who are seronegative for AQP4 antibodies but positive for IgG aquaporin-1 (AQP1) or myelin oligodendrocyte glycoprotein (MOG) antibodies. The purpose of this study was to determine whether AQP1 and MOG could be considered new biomarkers of this disease; and if point mutations in the gDNA of AQP4, AQP1 and MOG genes could be associated with the etiology of NMOsd. We evaluated the diagnostic capability of ELISA and cell-based assays (CBA), and analyzed their reliability, specificity, and sensitivity in detecting antibodies against these three proteins. The results showed that both assays can recognize these antigen proteins under appropriate conditions, but only anti-AQP4 antibodies, and not AQP1 or MOG, appears to be a clear biomarker for NMOsd. CBA is the best method for detecting these antibodies; and serum levels of AQP4 antibodies do not correlate with the progression of this disease. So far, the sequencing analysis has not revealed a genetic basis for the etiology of NMOsd, but a more extensive analysis is required before definitive conclusions can be drawn.

Recurrent pseudotumoral relapses in multiple sclerosis: a case report.

OBJECTIVES: Multiple sclerosis (MS) is the most common chronic disabling disease of the central nervous system (CNS) in young adults. It is characterized by the presence of multiple demyelinating inflammatory lesions disseminated in the CNS. Pseudotumoral lesions (PL) are rarely observed in patients with MS. METHODS: These atypical lesions can pose a diagnostic problem, especially when they are present at disease onset. RESULTS: Most MS patients with PLs only have a single episode throughout their disease course, which reflects its low tendency of recurrence. CONCLUSIONS: We report the rare case of a 34-year-old MS patient who suffered from recurrent pseudotumoral episodes during follow-up.

Comparative Analysis for the Presence of IgG Anti-Aquaporin-1 in Patients with NMO-Spectrum Disorders.

Detection of IgG anti-Aquaporin-4 (AQP4) in serum of patients with Neuromyelitis optica syndrome disorders (NMOSD) has improved diagnosis of these processes and differentiation from Multiple sclerosis (MS). Recent findings also claim that a subgroup of patients with NMOSD, serum negative for IgG-anti-AQP4, present antibodies anti-AQP1 instead. Explore the presence of IgG-anti-AQP1 using a previously developed cell-based assay (CBA) highly sensitive to IgG-anti-AQP4. Serum of 205 patients diagnosed as NMOSD (8), multiple sclerosis (94), optic neuritis (39), idiopathic myelitis (29), other idiopathic demyelinating disorders of the central nervous system (9), other neurological diseases (18) and healthy controls (8), were used in a CBA over fixed HEK cells transfected with hAQP1-EGFP or hM23-AQP4-EGFP, treated with Triton X-100 and untreated. ELISA was also performed. Analysis of serum with our CBA indicated absence of anti-AQP1 antibodies, whereas in cells pretreated with detergent, noisy signal made reliable detection impossible. ELISA showed positive results in few serums. The low number of NMOSD serums included in our study reduces its power to conclude the specificity of AQP1 antibodies as new biomarkers of NMOSD. Our study does not sustain detection of anti-AQP1 in serum of NMOSD patients but further experiments are expected.

An immunoassay that distinguishes real neuromyelitis optica signals from a labeling detected in patients receiving natalizumab.

BACKGROUND: Cell-based assays for neuromyelitis optica (NMO) diagnosis are the most sensitive and specific methods to detect anti-aquaporin 4 (AQP4) antibodies in serum, but some improvements in their quantitative and specificity capacities would be desirable. Thus the aim of the present work was to develop a sensitive quantitative method for detection of anti-AQP4 antibodies that allows clear diagnosis of NMO and distinction of false labeling produced by natalizumab treatment. METHODS: Sera from 167 individuals, patients diagnosed with NMO (16), multiple sclerosis (85), optic neuritis (24), idiopathic myelitis (21), or other neurological disorders (13) and healthy controls (8), were used as the primary antibody in an immunofluorescence assay on HEK cells transfected with the M23 isoform of human AQP4 fused with enhanced green fluorescent protein. Cells used were freshly transfected or stored frozen and then thawed just before adding the serum. RESULTS: Microscopic observation and fluorescence quantification produced similar results in fresh and frozen samples. Serum samples from patients diagnosed with NMO were 100% positive for anti-AQP4 antibodies, while all the other sera were negative. Using serum from patients treated with natalizumab, a small and unspecific fluorescent signal was produced from all HEK cells, regardless of AQP4 expression. CONCLUSIONS: Our cell-based double-label fluorescence immunoassay protocol significantly increases the signal specificity and reduces false diagnosis of NMO patients, especially in those receiving natalizumab treatment. Frozen pretreated cells allow faster detection of anti-AQP4 antibodies.

Pseudotumoral forms of multiple sclerosis: report of 14 cases and review of the literature.

BACKGROUND: The pseudotumoral form of multiple sclerosis (MS) is a rare condition with few descriptions in the literature. It supposes a diagnostic challenge especially when appearing at the onset of disease. METHODS: We retrospectively describe a case series of pseudotumoral MS patients that attended our hospital from 2004, analyzing demographic, clinical and radiological variables. We classified the lesions according to the recently proposed morphologic classification (infiltrative, megacystic, Baló or ring-like) and according to the contrast enhancement pattern (nodular, complete ring, incomplete ring and diffuse). RESULTS: Fourteen patients (11 female, 3 male), with a mean age of 35 years, were identified. All of them suffered from a relapsing-remitting form of MS. Eleven patients (78.57%) had symptomatic pseudotumoral lesions (PL), being the form of clinical presentation in the majority of those patients that were symptomatic (81.81%). Several patients presented atypical clinical manifestations such as cognitive impairment (21.42%) and epileptic seizures (14.28%). Full recovery was found in 53.84% of all symptomatic episodes. After a mean follow-up of 43 months, recurrent PL episodes were seldom observed (21.42%), the annualized relapse rate was 0.95 and the mean final Expanded Disability Status Scale score was 1.5. The majority of PLs were supratentorial, coexisted with typical demyelinating plaques and showed the ring-like morphology and the ring pattern of contrast enhancement. Three patients had more than one PL on the same scan, all of the lesions with similar morphology. CONCLUSIONS: Our findings contribute to a better characterization of pseudotumoral forms of MS. However, larger studies are required to define this atypical entity more exactly.